O & M Manual

.

.

OPERATION & MAINTENANCE

MANUAL

FOR 2 X 20TPH

WASTE HEAT RECOVERY BOILER ON COKE OVEN

SUPPLIED TO

THERMAX POWER A/C BHATIA ENERGY& STEELS LTD

GUMMIDIPOONDI, TAMILNADU

THERMAX PROJECT NO.: PL 0501 – 02

THERMAX LIMITED

BOILER & HEATER GROUP

PUNE, INDIAPSK &

SD23.07.2010 AA 23.07.2010 USU 23.07.2010 0

PREPARED BY CHECKED BY APPROVED BY REVISIONDESC. /

REMARK

Operation & Maintenance Manual

Contents

Volume 1 — Boiler Description ....................................................................................................1Section A................................................................................................................................2

1 Design SpeciÞcation of WHRB ....................................................................................22 Flue Gas Data ............................................................................................................23 Technical SpeciÞcation ................................................................................................3

3.1 Flue gas Velocity proÞle: (for design case) ..........................................................33.2 Flue gas Temperature proÞle:(For Design case)...................................................33.3 Water / Steam Temperature proÞle: (For Design case) ........................................33.4 Flue gas Pressure drop proÞle: (for design case) .................................................4

4 MOC And SpeciÞcation of Euqipments .........................................................................44.1 Steam Drum......................................................................................................44.2 Superheater- II ..................................................................................................44.3 Superheater IA / IB / Support Coils .....................................................................54.4 Evaporator / Convection Bank Tubes ..................................................................64.5 Economiser .......................................................................................................64.6 Attemperator .....................................................................................................74.7 Insulation ..........................................................................................................74.8 Blow Down Tank ................................................................................................7

5 Utilities .......................................................................................................................75.1 Electrical power .................................................................................................75.2 Cooling Water....................................................................................................85.3 DM Water..........................................................................................................85.4 Instrument Air....................................................................................................85.5 Deaerator Steam ...............................................................................................85.6 Chemicals for Dosing.........................................................................................9

6 ID Fans ......................................................................................................................97 Deaerator ...................................................................................................................98 HP/ LP Dosing System ................................................................................................99 Boiler Feed Pump ..................................................................................................... 1010 Soot Blower ............................................................................................................ 1011 Gauge Glass ........................................................................................................... 1112 Safety Valve............................................................................................................ 1113 Safety Relief Valve .................................................................................................. 1214 EMR Valve.............................................................................................................. 1215 Gauge Glass........................................................................................................... 13

Section B.............................................................................................................................. 141 Section Overview ...................................................................................................... 142 Water And Steam System.......................................................................................... 16

2.1 Component Description.................................................................................... 163 Boiler Pressure Part Description................................................................................. 19

3.1 Economizer ..................................................................................................... 193.2 Steam Drum.................................................................................................... 203.3 Silencer .......................................................................................................... 223.4 Air Vent ........................................................................................................... 223.5 Evaporator ...................................................................................................... 223.6 Super Heater .................................................................................................. 233.7 Super Heater I ................................................................................................. 233.8 Attemperator ................................................................................................... 233.9 Super Heater II ................................................................................................ 233.10 Steam Temperature Control Loop ................................................................... 23

4 Main Steam Piping .................................................................................................... 245 Operational Control .................................................................................................. 24

5.1 Steam and Water System Technical Performance Data ...................................... 25

i


6 Boiler Blowdown System ........................................................................................... 256.1 Other Drains.................................................................................................... 266.2 Continuous Blow Down Control ........................................................................ 26

7 Chemical Dosing & Sampling System......................................................................... 277.1 HP Dosing System........................................................................................... 277.2 Mixing Tank ..................................................................................................... 277.3 Preparation of 5% Phosphate Solution in the tank.............................................. 277.4 Phosphate Dosing Pump.................................................................................. 277.5 Water And Steam Quality Control And Monitoring .............................................. 297.6 Maintaining Quality of Steam............................................................................ 307.7 Operational Control.......................................................................................... 31

8 Flue Gas System ...................................................................................................... 318.1 System Description.......................................................................................... 318.2 Operational Control.......................................................................................... 32

9 Soot Blower System .................................................................................................. 329.1 Soot Blower..................................................................................................... 32

10 Boiler Protection & Interlock ..................................................................................... 3510.1 Alarms And Interlocks .................................................................................... 3510.2 Operational Control........................................................................................ 3510.3 Automatic Control .......................................................................................... 35

Section C ............................................................................................................................. 381 Section Overview ...................................................................................................... 382 Operation Procedure ................................................................................................. 383 Pre-requisites to Be Attended Before Start up ............................................................. 38

3.1 Feed Water Supply .......................................................................................... 383.2 Valve Settings ................................................................................................. 383.3 Filling With Water............................................................................................. 393.4 Heating Up...................................................................................................... 39

4 Boiler Start Up .......................................................................................................... 404.1 Cold Start Up Procedure .................................................................................. 404.2 Hot Startup Procedure .................................................................................... 42

5 Boiler Shutdown........................................................................................................ 425.1 Normal Shutdown Procedure............................................................................ 425.2 Emergency Shutdown Procedure...................................................................... 435.3 During Black - Out Procedure Condition ............................................................ 435.4 Operator Action Required During Boiler Cold Start up ........................................ 43

6 Paralleling WHRB To The Plant steam Mains.............................................................. 437 Cooling of Shutdown WHRB & Its Preservation ........................................................... 44

7.1 System Description.......................................................................................... 447.2 Natural Cooling................................................................................................ 447.3 Forced Cooling ................................................................................................ 44

8 Do�s and Dont�s......................................................................................................... 449 WHRB Log Sheet...................................................................................................... 4610 Emergency Procedures ........................................................................................... 48

10.1 Low Water Level ............................................................................................ 4810.2 High Water Level ........................................................................................... 4810.3 Tube Failure .................................................................................................. 48

11 Alarms and Interlocks .............................................................................................. 4912 Troubleshooting Chart ............................................................................................. 5113 Water Quality Recommendations ............................................................................. 5414 Safety In WHRB House ........................................................................................... 55

Section D ............................................................................................................................. 561 Section Overview ...................................................................................................... 562 Recommended Maintenance Practices....................................................................... 563 Preventive Maintenance ............................................................................................ 56

ii


3.1 Preventive Maintenance Program for Valve ....................................................... 573.2 Preventive Maintenance Program for Spares..................................................... 57

4 Conditioned Based Maintenance................................................................................ 574.1 Daily Checks ................................................................................................... 574.2 Daily Maintenance ........................................................................................... 604.3 Monthly Checks............................................................................................... 604.4 Checks Every Six Months................................................................................. 614.5 Checks Every Year .......................................................................................... 614.6 Annual Maintenance Check Sheet .................................................................... 62

5 Boiler Annual Maintenance and Overhaul ................................................................... 675.1 Planning Before Overhaul ................................................................................ 675.2 Shutdown and Cooling the Boiler ...................................................................... 675.3 Inspection after Cooling.................................................................................... 675.4 Drum Inspection .............................................................................................. 675.5 Inspection of Screen, Primary & Secondary Superheaters, Evaporators I/II &

Economiser................................................................................................ 685.6 Expansion Joints ............................................................................................. 685.7 Insulation and Cladding.................................................................................... 685.8 Other Equipment ............................................................................................. 685.9 Feed & Boiler Water Conditioning ..................................................................... 68

6 Boiler Preservation Procedure.................................................................................... 716.1 DeÞnition of Water Quality ................................................................................ 716.2 Dry Storage Preservation ................................................................................. 716.3 Wet Storage Preservation ................................................................................ 726.4 Nitrogen Blanket .............................................................................................. 736.5 Hot Draining .................................................................................................... 736.6 Alkaline Water Dozed With Hyderzine ............................................................... 746.7 Preservation of Extra Surfaces of Pressure Parts of WHRB During Long

shutdown................................................................................................... 746.8 Boiler Lay Up Procedures................................................................................. 756.9 Preservation of Rotating Equipments ................................................................ 756.10 Preservation of Instruments ............................................................................ 756.11 Tube Thickness Survey .................................................................................. 75

7 Tube Failures............................................................................................................ 767.1 Tube Failure Investigation / Analysis Method ..................................................... 767.2 Tube Thickness Survey Data Collection � Format .............................................. 787.3 Failure Reporting Formats................................................................................ 78

8 Welding Procedure SpeciÞcations .............................................................................. 808.1 Window Patch Welding .................................................................................... 80

9 General Principle Of Weld Repairs ............................................................................. 819.1 Furnace and Boiler Tubes ................................................................................ 819.2 Weld Repair Of Small Cracks in Tube ............................................................... 829.3 Plugging Tubes in Drums & Headers................................................................. 829.4 Replacement of Tube Section........................................................................... 849.5 Removing Tubes from Drums, Headers & Tube Plates ....................................... 849.6 Plugging of Tubes Drawings ............................................................................. 84

10 Water Chemistry ..................................................................................................... 9310.1 Undissolved and Suspended Solid Materials ................................................... 9310.2 Dissolved Salts and Minerals .......................................................................... 9310.3 Dissolved Gases............................................................................................ 9410.4 Other Materials .............................................................................................. 9410.5 pH Value of the Water and its Importance ........................................................ 9410.6 Effects of Impurities ....................................................................................... 94

Section E.............................................................................................................................. 971 Lubrication Schedule................................................................................................. 97

iii


Volume 2 — Drawings................................................................................................................ 98List of Drawings .................................................................................................................... 99

Volume 3 — Drawings.............................................................................................................. 100E & I SpeciÞcations ............................................................................................................. 101

Section 01 ................................................................................................................... 101Section 02 ................................................................................................................... 101Section 03 ................................................................................................................... 101Section 04 ................................................................................................................... 101Section 05 ................................................................................................................... 101Section 06 ................................................................................................................... 101Section 07 ................................................................................................................... 101Section 08 ................................................................................................................... 101Section 09 ................................................................................................................... 101Section 10 ................................................................................................................... 101Section 11.................................................................................................................... 101Section 12 ................................................................................................................... 101Section 13 ................................................................................................................... 102Section 14 ................................................................................................................... 102Section 15 ................................................................................................................... 102

Volume 4 — Vendor Manuals ................................................................................................... 103Section 01 .......................................................................................................................... 104

Pressure Transmitter � Emerson.................................................................................. 104Section 02 .......................................................................................................................... 104

Temperature Transmitter � Emerson ............................................................................ 104Section 03 .......................................................................................................................... 104

Pressure Switch � Switzer Instruments......................................................................... 104Section 04 .......................................................................................................................... 104

4.1 Pressure Gauge � Gauges Bourdon ....................................................................... 1044.2 Temperature Gauge � Goa Instruments .................................................................. 104

Section 05 .......................................................................................................................... 104Power Cylinder � Keltron ............................................................................................ 104

Section 06 .......................................................................................................................... 104Loop Power Indicator � Switzer Instruments ................................................................. 104

Section 07 .......................................................................................................................... 104I to P Converter � ABB ................................................................................................ 104

Section 08 .......................................................................................................................... 1058.1 Flow Nozzle � Starmech Controls........................................................................... 1058.2 Thermocouple � Thermal Instruments..................................................................... 105

Section 09 .......................................................................................................................... 105Control Valves� MIL .................................................................................................... 105

Section 10 .......................................................................................................................... 105Motorised Valve Actuator� Auma India Ltd.................................................................... 105

Volume 5 — Vendor Manuals ................................................................................................... 106Section 01 .......................................................................................................................... 107

ID Fan - Flakt Woods.................................................................................................... 107Section 02 .......................................................................................................................... 107

BFW Pump � KSB Pumps .......................................................................................... 107Section 03 .......................................................................................................................... 107

LP / H.P Dosing System - Metapow Industries................................................................ 107Section 04 .......................................................................................................................... 107

4.1 Long Retractable Soot Blower - R.R. Techno ............................................................ 1074.2 Rotary Soot Blower - Sitson India Ltd. ...................................................................... 108

Section 05 .......................................................................................................................... 1085.1 Motors� Siemens .................................................................................................. 108

iv


5.2 ARC Valve � Schroedahl........................................................................................ 108Volume 6 — Vendor Manuals ................................................................................................... 109

Section 01 .......................................................................................................................... 110Safety Valve � Tyco Sanmar ......................................................................................... 110

Section 02 .......................................................................................................................... 110Safety Relief Valves � Tyco Sanmar............................................................................. 110

Section 03 .......................................................................................................................... 110Drum Level Gauge � Hitech......................................................................................... 110

Section 04 .......................................................................................................................... 110Level Gauge (Tubular ) � Chemtrol ............................................................................... 110

Section 05 .......................................................................................................................... 110Reßex Level Gauge � Chemtrols.................................................................................. 110

Section 06 .......................................................................................................................... 111Process Valve � KSB ................................................................................................. 111

Section 07 .......................................................................................................................... 111Process Valve � Xomox Sanmar .................................................................................. 111

Section 08 .......................................................................................................................... 111Blow Down Valve � Levcon Instruments ....................................................................... 111

Section 09 .......................................................................................................................... 1119.1 Spring Hanger Support � Techno Industries ............................................................ 1119.2 Hanger Support � Pipe Support ............................................................................... 111

Section 10 .......................................................................................................................... 111Damper - United Technomech Engineers Pvt. Ltd. ......................................................... 111

Index.................................................................................................................................. 113

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vi


Volume 1 — Boiler Description

Chapters Covered in this Part

♦ Section A♦ Section B♦ Section C♦ Section D♦ Section E

Volume 1 � Boiler Description 1


Section A

Topics Covered in this Chapter

♦ Design SpeciÞcation of WHRB♦ Flue Gas Data♦ Technical SpeciÞcation♦ MOC And SpeciÞcation of Euqipments♦ Utilities♦ ID Fans♦ Deaerator♦ HP/ LP Dosing System♦ Boiler Feed Pump♦ Soot Blower♦ Gauge Glass♦ Safety Valve♦ Safety Relief Valve♦ EMR Valve♦ Gauge Glass

1 Design Specification of WHRB

NUMBER & TYPE OF BOILER

Two nos. 20-TPH, Water tube, Natural Circulation, Single-Drum Coke Oven WHR Boiler. BottomSupported Pressure parts

PARAMETERS UNIT VALUE

Boiler Rating [MCR] TPH 20

Steam Pressure at Main SteamStop Valve Outlet from minimumLoad upto MCR

Kg/cm2 66

Steam Temperature at the MainSteam Stop valve at MCR Deg C 485±5

Main Steam TemperatureControl range at the MainSteam Stop Valve Outlet (@950 deg C Inlet Flue Gas Temp)

% MCR 60 � 100

Maximum allowable workingpressure Kg/cm2 75

Hydraulic Test Pressure Kg/cm2 112.5

Design Pressure Kg/cm2 75

Boiler Performance TestingProcedure ASME PTC 4.4 Energy Balance

DESIGN CODE ASME SECTION-1

2 Flue Gas Data

PARAMETERS VALUE

Boiler Rating [MCR] Nm3/Hr ( Per Boiler) 52,935

Inlet Temperature °C 950

Section A 2


PARAMETERS VALUE

Outlet Temperature °C 180 ± 5

Flue Gas Composition (% V/V):-

CO2 4.45

H2 O 6.2

N2 75.79

O2 13.45

SO2 100 ppm

Dust Loading 100 m g/Nm3

3 Technical Specification

3.1 Flue gas Velocity profile: (for design case)

SrNo. Component Velocity, m/s

1 Radiation cavity 8

2 Superheater 12 to 15

3 Evaporator 10 to 11

4 Economiser 8 to 9

3.2 Flue gas Temperature profile:(For Design case)

SrNo. Component Deg C

1 Radiation chamber inlet / outlet 950 / 878

Pre Evaporator cum Support Tube2

(Pass 1) inlet / outlet878 / 849

3 Superheater II (Pass 1) inlet / outlet 849 / 723

4 Superheater 1A (Pass 1) inlet / outlet 723 / 669

5 Superheater 1B (Pass 1) inlet / outlet 669 / 590

6 Evaporator I (Pass 1) inlet / outlet 590 / 390

7 Evaporator II (Pass 2) inlet / outlet 390 / 336

8 Inlet of Economiser 336

9 Outlet of Economiser 180

3.3 Water / Steam Temperature profile: (For Design case)

Sr Component Deg C

1 Radiation chamber inlet / outlet 285 / 285

Pre Evaporator cum Support Tube2

(Pass 1) inlet / outlet285 / 285

3 Superheater II (Pass 1) inlet / outlet 328 / 485

Section A 3


Sr Component Deg C

4 Superheater 1A (Pass 1) inlet / outlet 368 / 428

5 Superheater 1B (Pass 1) inlet / outlet 285 / 368

6 Evaporator I (Pass 1) inlet / outlet 285 / 285

7 Evaporator II (Pass 2) inlet / outlet 285 / 285

8 Inlet of Economiser 120

9 Outlet of Economiser 258

3.4 Flue gas Pressure drop profile: (for design case)

SrNo. Component (at outlet) Pressure mmWC

1 Radiation cavity +Bends+Screen -5

2 Superheater -30

3 Evaporator -85

4 Economiser -165

4 MOC And Specification of Euqipments

4.1 Steam Drum

SrNo. Description Value

1 Design code IBR 1950 with its latest amendments

2 Design pressure 75 kg/cm² g

3 Design temperature 291 °C

4 Hydrotest pressure 112.5 kg/cm² g

5 Length 4000 mm

6 Inner diameter 1375 mm

7 Thickness 50 mm

8 Material of construction SA 516 Gr 70 / Equiv.

9 Quantity per boiler 1 no.

10 Corrosion allowance As per IBR

11 Internals Demister pad

12 Quantity of safety valves 2 nos.

13 Capacity of each safety valve 7500 kg/hr

14 Set pressure of Þrst safety valve 74.5 Kg/cm² g

15 Set pressure of second safety valve 75 kg/cm² g

4.2 Superheater- II




Section A 4



3 Design temperature

SH II 529 °C

Support Coils 319 °C

4 Design temperature of headers 490 °C


6 Type Horizontal

7 Heat transfer area(Thermal) 86.18 m²

8 Type of tubes Bare

9 Tube outer diameter OD 38.1mm x 4.06 mm thk

10 Tube thickness As per IBR

11 MOC of tubes SA 213 T22 HFS

12 MOC of Support Coils SA 210 Gr A1

13 Safety valve relieving capacity 5000 kg/hr

14 Safety valve set pressure 71 kg/cm²g

4.3 Superheater IA / IB / Support Coils




Design temperature of SH IA 467 °C

Design temperature of SH IB 407 °C

3 Design temperature of support coils 319 °C

4 Design temperature of headers

SH IB Inlet Header 291 °C

SH IA Outlet Header 428 °C

SH II Inlet Header 428 °C

SH II Outlet Header 490 °C


6 Type Horizontal

7 Heat transfer area(Thermal) 43.09 m² + 71.187 m²


9 Tube outer diameter OD 38.1 mm x 4.06 mm thk


11 MOC of SH IA tubes SA 213 Gr T11 HFS

MOC of SH IB / support coils tubes SA 210 T22 Gr A1 HFS

12 MOC of headers SA 335 P11

13 Header outer diameter OD 168.3 mm x 14.27 mm thk

Section A 5


4.4 Evaporator / Convection Bank Tubes




3 Design temperature of coils 319°C



6 Type Horizontal

Heat transfer area (thermal Area)

A) Convection Panel (Pass 1) 190.05 m²

B) Pre Evaporator cum Support Tube 7.182 m²

C) Evaporator I (Pass 1) 258.54 m²

7

D) Evaporator II (Pass 2) 206.832 m²


9 Tube outer diameter OD 38.1 mm x 3.66 mm thk


11 MOC of tubes SA 210 GR A1

12 MOC of Water wall tubes SA 210 GR A1 HFS

13 Tube OD of water wall tubes OD 63.5 mm x 4.06 thk mm

14 Tube thickness of water wall tubes As per IBR

15 MOC of headers SA 106 Gr B

16 Header outer diameter OD 219.1mm x 18.26 mm thk

17 Header thickness As per IBR

4.5 Economiser

Sr No. Description Value



3 Design temperature of coils 269 °C



6 Type Horizontal

7 Heat transfer area 827.33 m²


9 Tube outer diameter OD 38.1 mm x 3�.66 mm thk


11 MOC of tubes SA 210 GR A1

12 MOC of headers SA 106 Gr B

Section A 6



13 Header outer diameter mm OD 114.3 mm x 13.49 mm thk

14 Header thickness mm As per IBR

4.6 Attemperator


1 Type Spray type Attemperator

2 Nos One

3 Location Between SH I & SH II

4 Water Flow at MCR (kg/h) Later

5 MOC of headers SA 335 P11

6 Header outer diameter mm OD 219.1 mm x 12.7 mm thk x 5000mm long

7 Header thickness mm As per IBR

8 Desidn Temperature 428 deg C

4.7 Insulation


1 Type Mineral wool mattress

100 Kg/M3 up to 400 Deg C2 Density

120 Kg/M3 above 400 Deg C

3 Cladding Aluminum sheet of 24 SWG

4 Skin Temperature 30 Deg C above ambient temp.

4.8 Blow Down Tank

Sr. Description Value


2 Design pressure 3.5 kg/cm² g

3 Design Metal Temperature 150 °C


5 Shell Hight 1500 mm

6 Shell ID 960 mm

7 Shell thickness 10 mm

8 Type of ends Dished

9 Material of construction SA 516 Gr. 70

5 Utilities

5.1 Electrical power

Parameters Units Value

For LT motors (UPTO AND INCLUDING 200 KW)

Voltage V 415 +/- 10%

Section A 7


Parameters Units Value

Frequency Hz 50 +/- 5%

Type AC, 3 Phase, 4 wire

For Instrumentation (field switches, Level gauge illumination, solenoid valves etc.)

Voltage V 110

Frequency Hz 50

Type Single Phase, 2 wire

For Field Transmitters

Voltage V 24

Frequency Hz NA

Type DC

5.2 Cooling Water

Parameters Unit Value

Supply Pressure Kg/cm2(g) 3�4 @ Battery Limit

Supply Temperature Deg C Ambient @ Battery Limit

Quality Clear & colourless

Duty BFP Pump cooling & Sample cooler

Quantity (for BFP pump) Kg/Hr 1000 (Normal) , 1200 (Maximum)

Quantity (for Sample cooler) Kg/Hr 600 (Normal) , 720 (Maximum)

5.3 DM Water


Supply Pressure KSC (g) 5 @ Battery Limit

Supply Temperature Deg C Ambient @ Battery Limit

Flow Kg/Hr 1200 (Normal) , 15000 (Maximum)

5.4 Instrument Air


Pressure Kg/cm2(g) 5� 6

Dew point Deg c -40

Temperature Deg c Ambient

Quality � Oil & moisture free

Quantity scfm 50 (continuous) & 25 (Intermittent)

5.5 Deaerator Steam


Pressure Kg/cm2(g) 4.0 (Normal) , 9.0 (Maximum)

Temperature Deg c 185

Quanlity Kg/hr 5000 (Normal)

Section A 8


5.6 Chemicals for Dosing

HP Dosing Tri sodium phosphate

LP Dosing Hydrazine

6 ID Fans


1 Type of fan Centrifugal

2 Quantity 02 nos

2 Drive Electric motor

3 Coupling Resilient type coupling

4 Rated head 410 mmWC

5 Rated capacity 31.6 m3/sec

6 MOC of casing IS 2062 Gr A (MS)

7 MOC of impeller SAILMA 350

8 MOC of shaft EN 8

9 Fan speed 980 rpm

10 Cooling water requirement Not required.

11 Type of ßow control By variable frequency control & Pneumaticoperated multi louver damper.

12 Type of isolation Not required

13 Type of Lubrication Grease (Servo Gem; EP2)

7 Deaerator

Description Valve

Deaeration capacity 48 m3/hr (Max)

Storage tank Capacity (Full) 27 m3

Storage tank capacity 16 m3

Operating pressure 1.76 bar(g)

Operating temperature 120° C (case 1) & 130 ° C (case 2)

Design pressure 3.0 Kg/cm2(g)

Design temperature 200 ° C

Design & Construction code ASME SECT. VIII DIV Edition 2004, ADDENDA2006 (WITH �U� STAMPING)

8 HP/ LP Dosing System

Make : Metapow Industries


1 Major parts Storage tank � 1 no, Stirrer � 1 no., Dosingpumps � 2 nos.

Storage tank Details

Section A 9



1 Size of storage tank 600 mm x 800 mm x 5 mm

2 Tank capacity 150 liters

3 MOC of tank IS 2062 MSRL; Rubber lined 3mm

4 MOC of chemical basket SS 304

Dosing pump Details

1 Pump make VK Pumps / Equiv.

2 Pump capacity (HP/LP) 0� 6 LPH

3 Pump type Reciprocating Plunger type

4 Operating Pressure (HP/LP) 76 kg/cm2 / 6.35 kg/cm2

5 Safety Relief Valve Set Pressure (HP/LP) 102 kg/cm2 / 8 kg/cm2

6 Type of Lubrication / Quantity ISO VG 460 / 0.8 liters

7 Motor Details Crompton Greaves

Stirrer details

1 Type of operation Motorised

2 Motor Details 0.5 HP / 1000 RPM (HP); 750 RPM (LP)

9 Boiler Feed Pump

DESCRIPTION UNIT VALUE

MAKE KSB PUMPS LTD.

Type & Size HAD 65/15

Quantity NO 3 (2W/1 SB)

Fluid FEED WATER

Pump Speed RPM 2900

Capacity m3/hr 26

Design Head M 960

Fluid Temp °C 130

Gear type Spacer Coupling

Coupling Type (Make - Rathi)

Lubrication OIL SERVO SYSTEM / ENKLO- 46

Motor kW/RPM 160 /2985 (Make � Siemens)

10 Soot Blower

Sr No. Description Long Retractable sootblower Rotary soot blower

1 Location Super heater & EvaporatorZone Economizer Zone

2 Steam temperature deg c : Saturated

3 Steam pressure kg/cm2(g) 20

Section A 10


Sr No. Description Long Retractable sootblower Rotary soot blower

4 Source of Steam Saturated steam from Steam Drum

5 Drive Motorised

11 Gauge Glass

Drum level Gauge

Description Details

Make HI TECH SYSTEM & SERVICES LTD

Tag No.11� LG � 143/ 11� LG � 144 & 12� LG � 143/ 12�LG � 144

Type Bi Colour Duco Gauge

Location Steam drum

Operating pressure. 69 kg/cm2 (g)

Hydrotest pressure 112.5 kg/cm2 (g)

C/c distance 750 mm

Visibility Range 314 mm 5 Ports

Operating temp. 285 °C Normal Operating

Blow Down Level Gauge

Description Details

Make Chemtrol Samil

Tag No. 11� LG� 601

Type Tubular Level Gauge Assly

Location Blow Down Tank

Working pressure. 5 kg/cm2 (g)

C/c distance 500 mm

Visibility range 360 mm

Operating temp. 200 °C (Saturated) Normal Operating

12 Safety Valve

DESCRIPTIONAPPLICATION UNIT DRUM #1 DRUM #2 SH

TYPE - SPRING LOADED

MAKE ANDERSON GREENWOOD CROSBY

TAG NO - 11-PSV-001 11-PSV-002 11-PSV-003

SIZE ORIFICE -

SETPRESSUR. Kg/cm2 74.5 75 71

OPERATINGTEMP. DEG.C 285 285 485

Section A 11


DESCRIPTIONAPPLICATION UNIT DRUM #1 DRUM #2 SH

RELIEVINGCAPACITY TPH 8000 8000 6000

QUANTITY - 1 1 1

FLUID - Sat Steam Sat Steam Sup Steam

13 Safety Relief Valve

DESCRIPTION /APPLICATION UNIT Details


MAKE - TYCO SANMAR LTD

SIZE ORIFICE - 2.5 X JX 4.0

SET PRESSURE Kg/Sq.cm 23

Model JOS�H�E�35-C-IBR-SPL

Relieving Capacity Rated/ Requried Kg/hr 10595/8000

QUANTITY 1 / BLR

14 EMR Valve

DESCRIPTION /APPLICATION UNIT Details


MAKE - TYCO SANMAR LTD

SIZE ORIFICE - 2.5 X 4.0

SET PRESSURE Kg/Sq.cm 100

Model HPV-ST-68W-IBR

Relieving Capacity Rated/ Requried Kg/hr 20611/2750

Section A 12


15 Gauge Glass

Drum level Gauge

Description Details

Make HI-TECH SYSTEMS & SERVICES LTD.

Tag No. LI�34101 and LI-34102

Type Bi-Colour duco Level Gauge Assly

Location Steam drum

Operating pressure. 101.0 kg/cm2 (g)

Rating pressure 210 Bar

Hydrotest pressure 315 kg/cm2 (g)

C/c distance 750 mm

Visibility Range 314 mm 5 Ports


Blow Down Level Gauge

Description Details

Make Levcon Instruments

Tag No. LI �35001

Type Tubular Level Gauge Assly

Location Blow Down

Working pressure. 10 kg/cm2 (g)

C/c distance 1000+/-1

Visibility range 860 mm


Section A 13


Section B


♦ Section Overview♦ Water And Steam System♦ Boiler Pressure Part Description♦ Main Steam Piping♦ Operational Control♦ Boiler Blowdown System♦ Chemical Dosing & Sampling System♦ Flue Gas System♦ Soot Blower System♦ Boiler Protection & Interlock

1 Section Overview

This section gives a brief overview of the boilerand its associated systems. The description ofthe various systems that form part of the boilerpackage is also included. The aim of this sectionis to make the reader familiar with the boilerpackage components before introducing theoperation and maintenance sections.

Brief Overview

The Operation and Maintenance manual ofTHERMAX LTD (B & H Group) in Subsequentvolumes, provide useful information, guidelinesand data required for the safe operation andmaintenance of the two WHRB�s supplied toM/s Bhatia Energy & Steels Ltd AT GetanamalliTehsil, Gummudipondi, Tamilnadu. Contents ofeach of the volumes have been listed else wherein these manuals. It is expected that the BhatiaEnergy & Steels Ltd Engineers and Operatorswill familiarize themselves with these data beforeoperating the boilers.

The WHRB is designed to extract maximumrecoverable heat from the exhaust gas of thecoke oven. For this purpose the exhaust gas ßowfrom the oven is arranged in a direction counterto the water/ steam circuit of WHRB. The exhaustgas from the coke oven enters the super-heaters.From the Super-heaters, the exhaust gases travelthrough the HP boiler evaporator and economisermodules before exhausted to the atmosphere bythe stack.

To achieve better controllability of Þnal steamtemperature on varying loads, two stagesuper-heater is envisaged with an inter stagespray type attemperator.

The steam drum placed above the evaporatorserves as a balancing vessel for water and steam.

It receives feed-water from the Economiser andmaintains positive water supply to the evaporatormodules. Drum receives the mixture of steam andwater from the evaporator modules by the heattransfer. After separating water from the steam/ water mixture at drum, the saturated steam issupplied to the super-heaters.

Economisers installed behind the evaporatormodules serve to preheat the feed-water fed tothe steam drum recovering heat energy from theexhaust gas.

General Capacity

The main parameters of the boiler are

Maximum ContinuousRating

20 TPH

Steam Pressure 66 kg/cm2

Steam Temperature 485+/- 5 Deg C

Generation capacity of theWHRB at the base loadis 20 TPH at super-heater outlet pressure of 66kg/cm2(g) and temperature of 485+/- 5 ° C.

General description of WHRBinstrumentation

The latest generation of the Þeld instrumentsis used to facilitate monitoring and control ofthe process variables, generating alarms andtrips. Differential pressure Transmitters for themeasurement of process variables like Pressure,drum Level and Flow are used. Thermocoupleswith transmitters are used for the measurementof temperature. Control valves with positiontransmitter and proximity switches form a partof control system and act as the Þnal controlelement to control the process variables. Positiontransmitters allow the monitoring of the controllingelement position. Closed control loops areconÞgured in DCS (by customer).

Process switches and transmitters monitor theprocess variables and generate alarms and safeshutdown of WHRB.

Control Loops:

Following closed loop controls are provided for theWHRB operation:

� Drum level Control

� Steam temperature Control

� Furnace Pressure Control

� Soot Blower Pressure Control

� De-aerator Level and Pressure Control

Section B 14


Control philosophy of these loops is described inthe document submitted separately.

Referance Drawings:

� D12-0WH-09484 - P & ID for Waste Heatrecovery Boiler � Refer latest revision.

This O & M manual shall be for applicable for boththe 02 boilers. The description in the manual ofthe instrument and valve tag no. is dealt withtypically one boiler. However the tag no. for the

rest of boiler�s instrument and valves shall be asper the following nomenclature.

Refer the P & I diagram for the tagging procedure.

Instrument Tagging Procedure.Tag numbers of Instruments, motorized valves,pneumatic control valves, safety valves, manualvalves, & drives to be preÞxed with 10 forcommon items. 11 & 12 for WHRB 1 & 2respectively

Section B 15


2 Water And Steam System

AIM

The water and steam system covered in thischapter describes the components of the WHRBwhich transfer heat from the exhaust gas of theCoke oven to the feed water ßowing from thefeed water main to convert it to HP steam of 66Kg/cm²(g) at a temperature of 485 °C (±5°C). Thecomponents in the serial order of water ßow ofpath are,

� Deaerator

� Boiler Feed Water Station

� Boiler Feed Control Station

� Integral Economizers

� Evaporators I & II

� Superheater I

� Attemperator

� Superheater II

The exhaust gas from the Oven ßows in adirection counter to the water / steam ßow path,with the hottest gas entering across SuperheaterII, followed by all the components mentionedabove in reverse order. The exhaust gas,after transferring all its recoverable heat tothe Superheaters, Evaporators & Economizersexhausted to the atmosphere through the Stack.

2.1 Component Description

2.1.1Deaerator

PURPOSE OF DEAERATION

Deaeration removes the corrosive gases such asdissolved oxygen and free carbon dioxide fromthe boiler feed water. This ensures protectionof the feed water lines, steam lines, boiler tubesand other pressure parts of the boiler againstcorrosion and pitting, saves costly boiler re-tubingand expensive plant shutdowns. Further as thetemperature of feed water is raised from ambientto Deaerator operating temperature of 120 0Cor 130 0C [which corresponds to the operatingpressure of 1.76 kg /cm2 (g)] and then fed toboilers through feed pumps, the overall boilerthermal efÞciency also increases.

Heating the feed water with steam doesdeaeration. Vigorously scrubbing the waterwith this steam removes the last traces ofnon-condensable gases and brings down wellbelow the recommended level in feed water.

CONSTRUCTION FEATURE

The Deaerator supplied is of Thermal -Mechanical Deaerator in which DM water/makeup feed water is heated to its boilingtemperature at the operating pressure by steam.At boiling point all the dissolved gases such asOxygen, Carbon Dioxide, Etc. are liberated assolubility of gases decreases with increase intemperature. The mechanical scrubbing betweenwater and heating steam ensures release of thedissolved gases.

Deaerator is of spray and trays type, consists of astorage tank and a vapour tank. Water is sprayedfrom the top of the vapour tank by spray nozzleson set of multi level trays below it. Steam is fedfrom the supply pipe to the distribution headersinside the storage tank below the water level.Partial scrubbing of the steam and water takesplace in the storage tank water and the rest istaking place in the vapour tank with the incomingwater spray.

Vapour tank is mounted upon the storagetank. Both the tanks are connected withsteam connection Nozzle at the middle. Thisinterconnection nozzle of 1000 OD is ßushed withinner wall of the vapour tank�s dished end andembedded inside the water level of storage tankto facilitate the feed water ßow from vapour tank tothe storage tank. Interconnection accommodatesconcentrically the steam balancing connectionassembly. This steam connection is projectedinside the vapour tank and masked from the waterßow direction by a hood Þtted at the top, thusfacilitates the steam ßow from storage tank tovapour tank.

DM water enters to the vapour tank throughthe topside nozzle N18 to the distribution ringheader. Five spray nozzles are Þxed on thering header to spray the water into Þne particlescovering the entire cross section of the tank sothat easy and complete scrubbing with steamis possible. Perforated stainless steel trays atsix levels are placed inside the vapour tank toprovide enough delay time to scrub the feedwater with the upcoming steam. Feed water fromvapour tank ßows into the storage tank throughthe interconnection pipe.

Condensate enters to the vapour tank through thetopside nozzle N23 to the distribution ring header.Nozzles are Þxed on the ring header to spray thewater into Þne particles covering the entire crosssection of the tank so that easy and completescrubbing with steam is possible.

Heating Steam is supplied through the supply pipe(Nozzle N10) to the steam distribution headerskept inside the storage tank well below the water

Section B 16


level. Two steam distribution headers connectedto the supply pipe are lied at the bottom and alongthe length of the storage tank. These headers areperforated pipes to distribute the steam along theentire length of the storage tank water space.

Steam rises from the bottom of StorageTank, heating the water and rises throughthe interconnection pipe into the Vapor Tank.Perforated Trays inside the Vapor tank increasethe residence time of water and Heating Steam.Oxygen, Carbon dioxide and other dissolvedgases are vented out along with Vent Steamthrough the nozzle N13.

The dissolved Oxygen level in the feed waterby mechanical deaeration can be brought to0.02 to 0.03 ppm. If required the residualdissolved Oxygen can be further scavengedby the reaction with chemicals such as sodiumsulphite (catalyzed or un-catalyzed) or Hydrazine.By chemical scavenging the dissolved Oxygenlevel can be brought down to as low as 0.007ppm. Chemical may be dosed in the storagesection of the deaerator through a header. NozzleN4 is provided for this and can be utilised. Thedosing of the particular chemicals is done inpredetermined quantity and concentration. Asample cooler provided in the feed water outletpiping is used to collect the sample for analysisof water.

Storage tank is supported by saddle supports.One of the saddles is Þxed and the other is slidingone to take care of thermal expansion. PTFEsheets are provided under the sliding saddle forfree movement of saddle. Platforms and laddersare provided for tanks and condenser for O & Mfeasibility.

THE ACCESSORIES AND THE MOUNTINGS

Deaerator Level Control

The desired normal water level (NWL), which ismaintained through a level control valve [10-LCV102] of DM water line & condensate return line.Level in the storage tank is monitored remotelyby the level transmitter [10-LT 102 A & B ]. Twonozzles (N11 A/B) at this elevation are providedfor LT connection at distance of 301 mm aboveand 1392 mm below the NWL.

A Feed back control loop with the electroniccontroller [10-LIC 102] is provided for automaticlevel control. Process variable signal for the levelcontroller is transmitted by the [10-LT 102 A & B]. Set point of the level controller is to be kept at�0� mmWC, which corresponds, to NWL.

Apart from this remote level indication direct levelgauge glass [10-LG 103 & 104] are provided tocover the height between very low level and uptoover ßow level. These level gauge are mountedon a water column connected to the Nozzles N10A/B

Over Flow Shut Off Valve

[10-XV 109] shut off valve is provided to drainthe excess water from deaerator if level increasesbeyond recommended value. Connection N6 isassigned for that.

Pressure Control

The deaerator operating pressure of 1.76kg/cm2(g) is maintained by the pressure controlloop, which contains the pressure control valves[10-PCV 105] in the steam line, a pressuretransmitter [10-PT 105] mounted on the storagetank nozzle N12 and an electronic pressureindicating controller [10-PIC 105] in the controlroom. Set point for the pressure controller shallbe kept at 1.76 kg/cm2 (g).

Pressure Relief Valve (10-PSV 005)

A Nozzle N17 is provided at the top of vapourtank to mount a relief valve. Relief valve wouldrelieve the steam at the design set pressure of 3bar(g), when there is excessive pressure build-upinside the vessels (system) incase of suddenreduction of water out ßow/ intake to deaerator ormalfunctioning of pressure control loop.

Temperature Gauge

A temperature gauge [10-TE 107] is Þxed on to thestorage tank nozzle (N14).

Vacuum Breaker

A Vacuum Breaker assembly consists of NonReturn Valves directed towards vapor Tank fromatmosphere mounted on the Nozzle N18. This isto prevent Deaerator from operating at vacuum ornegative Pressure. Vacuum condition inside theDeaerator would mean that the Deaerator is notbeing supplied with enough Steam with respect tothe water ßow leading to condensation of heatingSteam. In case the Deaerator happens to gounder vacuum, atmospheric air will rush throughthese Non Return Valves breaking the vacuum.

Air vent

Air vent is provided (nozzle N2) on topside of thevapour tank. Air vent is provided with an oriÞceand a globe Valve in parallel with it. Through theAir vent, Steam and dissolved gases are vent out

Section B 17


to the atmosphere. The Valve shall be throttled tominimize the outßow of Steam. N20 is also oneconnection provided for air vent without oriÞce.

Other Connections

Feed water outlet nozzle N3 is provided. Wateroutlet piping going to the boiler feed water pumpssuction header.

A drain nozzle (N4) for draining the storage tank.

Pegging steam connection (Nozzle N22): Aperforated pipe connected to the nozzle is laidalong the length of the storage tank below thewater level. Admitting steam in a small quantitythrough pegging line and heating the water toa temperature upto 80 Deg C before admittingthe main steam in large quantity will reduce thepossible hammering.

Steam connection N5 is provided for admitting theLP steam for heating the deaerator after initialwarm up.

Nozzle N16(A to F) are provided for recirculationline from the boiler feed water pumps.

A Manhole is provided each for storage andvapour tank.

A sample cooler is provided in the water outlet ofdeaerator for the analysis of the water sample.Sample cooler is a coil & shell heat exchanger,sample water is passing through the coil andcooling water through the shell. Needle valvesare provided at the inlet and outlet respectively toregulate the sample ßow.

Condensate return line is provided at connectionN21

Balancing leak off line from feed pumps areprovided at connections N19 (A to F) .

REFERENCE DRAWINGS

P & I Diagram for Deaerator,FWP & dosing - D12-1WH-59879 Rev 3

P & I Diagram for WHRB - D12 -0WH-09484 Rev4

Assly of Deaerator - W21-1WH-63955 Rev0

2.1.2Boiler Feed Water Pumps

Deaerated water from the deaerator is deliveredto the boiler by means of boiler feed pumps.There are three motor driven feed water pumpsavailable. One pump is a standby pump. TheFeed water pumps are of Multistage Centrifugaltype. The Vendor�s manual is to be referred formore details on operation and maintenance.

Feed water pump’s associated system

Suction piping

Common suction header for both the pumpsis connected from the deaerator outlet piping,providing necessary suction to the pump.

Individual pump is provided with isolation valves[LFW-VG-117 / 118 / 119] and a suction Þlter.Filter prevents foreign particle entry into the pump.Pressure gauge installed at the pump inlet toindicate the available suction head while the pumpis running. Differential pressure transmittershelps to monitor the condition of strainer. Ifthe dP of suction strainer increases beyond therecommended value, then the feed pumps getssignal for trip

Balancing piping

Pump is provided with a balancing line, which isconnected to suction line of pump.

Minimum circulation piping

The minimum circulation piping is provided withindividual pump. This ensures that during theoperation of the pump there will always be aminimum ßow across the pump even when thereis no discharge into the boiler.

An auto re-circulation valve is provided onindividual pump discharge line for the abovepurpose

Throttle valve � for controlling the ßow through thecirculation line.

Non-return valve � to prevent the back ßow.

Discharge Piping

Discharge of each pump is connected to thecommon discharge header, which supplies feedwater to the boiler. A pressure gauge [10-PG124 / 125 / 126] & transmitter [10-PT136 / 137/ 138] are installed on the discharge header forobserving the discharge pressure.

Auto re-circulation valve (ARC) installed at thepump discharge maintains the minimum ßowrequired through the pump, when the ßow to boileris low. This minimum circulation ßow is takenthrough a line connected back to the deaeratorstorage tank with a NRV [LFW-VC-131/134/137]and a globe valve [LFW-VC 130/133/136].

Cooling Water Piping

Feed Pump Gland cooling arrangement isprovided for stufÞng boxes + lift off devices at DEand NDE side. The cooling water is fed throughplant cooling water system. Refer the pumpvendor drawing for details.

Section B 18


Note

Vendor manual for pumps to be referredfor more operation and maintenancedetails.

2.1.3Feed Control Station

WHRB, when it is in service, must be keptcontinuously supplied with feed water to maintainnear normal level in the drum. Feed water isobtained at battery limit (at the inlet of feed watercontrol station) from the feed water pump at apressure of 70.5 Kg/cm² and a temperature of120ºC. There is one feed control station, which isin service when the WHRB is operational.

� 100% Flow control FCV-137

The 100% ßow control valve FCV-137 is capableof feeding the WHRB when the steam ßow fromWHRB is from initial stage.

HFW-VL-124 is by pass for 100% FCV.

The following are installed in the common inlet linefrom the Plant feed main to the feed regulationstation

� Pressure indicator 11-PG-136 to indicate feedwater pressure

� Tap off for Attemporater spray waterwith manually operated Isolating valve[DSW-VG-101]

� Flow nozzle 11-FE-137 with impulseconnections to ßow transmitter 11-FT-137

� A temperature Element 11-TE-138 forindicating temperature of inlet feed water to theDCS indication.

� Pressure indicator 11-PG-139 to indicate feedwater pressure at economiser header inlet

The ßow transmitters provide feed ßow signal tothe feed Indicating controller 11-FIC-137 (whichwill be described later).

2.1.4100% Feed Controller 11-FCV-137

Manually operated valve HFW-VG-121 is theinlet isolating valve. HFW-VG-127 is the outletisolating valve which normally remains open.Drain valves at upstream and downstream of11-FCV 137 are used for draining only whenthe line is isolated for inspection/maintenance ofvalve 11-FCV 137.

Valve 11-FCV-137 is a full load feed regulatingvalve for maintaining drum water level and ispneumatically operated by a spring opposeddiaphragm actuator. The valve opens full onloss of control air and has no manual over ride.

The valve 11-FCV-137 is positioned by the ßowindicating controller 11-FIC-137.

11-FIC-137 is a three element controller, whichtakes into account not only the drum level, but alsothe steam ßow from WHRB and the current feedwater ßow, to correctly position the feed regulatingvalve FCV-137.

The drum level signal, compensated for drumpressure, is received in controller11-LIC-142.A linearised steam ßow signal, compensatedfor steam pressure and temperature is alsoreceived in 11-FIC-137. The drum level which isa measured variable signal, is computed with theanticipatory signal of steam ßow in 11-FI-137 anda resultant error signal is fed to feed indicatingcontroller 11-FIC-137. 11-FIC-137 comparesthe level error signal with the feed ßow signalit receives from ßow transmitters 11-FI-157 &11-FI-137 and computes a control current signalbased on its set point (usually normal level). Thevalve position is transmitted to the DCS. On theDCS, current drum level, steam ßow, feed ßow &the feed control valve position can be monitored.

The three element control adopted for the 100%ßow control valves FCV-137 takes into accountthe drum level, steam ßow and feed water ßow forpositioning the control valve as well as it takes onlydrum level for its operation at low load.

3 Boiler Pressure Part Description

This boiler is a Single-drum, natural circulation,top supported, and membrane wall construction.Various pressure parts are grouped as follows:

1. Economiser

2. Steam drum

3. Silencer

4. Air Vent

5. Evaporator

6. Super heater

7. Attemperator

8. Steam Temperature Control

3.1 Economizer

The Economizer located on the last stages of theexhaust gas path of the WHRB.

Feed water from the feed regulating station,enters the Bottom header of the ECO ßows upwards.

Economizer is provided with air vent and drains.ECO is hung from the top by two guide supports

Section B 19


and anchor support with provision for downwardthermal expansion.

The drain valves are used for draining the ECOtubes when the WHRB is not in service, if requiredfor maintenance.

Feed water, after picking up heat from theEconomizer, enters the Drum through tEconomizer outlet pipe. Temperature Indication/ Recording Instruments 11-TE-138 / 141 aremeant for indicating feed water temperaturesbefore and after Economizer respectively. Thereare pressure gauges 11-PG-139 / 140 at inlet andoutlet header of economiser to monitor the feedwater pressure.

3.2 Steam Drum

The Steam Drum is a long (4000mm approx.) allwelded cylindrical vessel made of SA-516 Grade70 material. The steam drum is supported bythe main down comers and the down comersare placed on the WHRB structure over beams.The sliding arrangement permits a limited shiftdue to thermal expansion. The drum is insulatedby lightly resin bonded mineral wool mats. Twomanholes, at either end of the drum, provideaccess to the drum. The drum is closed tightat either end cover plates bolted against themanhole rim by two holding bars. A gasket is Þttedbetween the cover plate and the mating machinedsurfaces in the dished ends. The cover platesswing inside, for convenience during opening.

Steam Drum is Þtted with several componentsto perform important functions, which are listedbelow:

(a) Steam Drum receives feed water fromthe Economizer outlet through feed pipes anddistributes the feed water along the length of thedrum by a perforated pipe 80NB tomaintain a nearconstant level (Normal water level) for continuoussupply to the evaporator. (to be described furtherlater) through down comer pipes. While ßowingthrough the evaporator panels, by absorbing heatfrom the coke oven exhaust gas, the hot watergets converted to water / steam mixture and ßowsback to the Drum through riser tubes.

(b) Steam drum receives the water – steammixture from the evaporator panels through theriser tubes, the water � steam mixture ßowstangentially through the Diemeister pad installedin the steam drum. In this tangential ßow, water,which is heavier, is separated from steam andtrickle down to mix with the water in the steamdrum. Saturated dry steam collects at the top ofthe drum and distributed to the Superheater I.

(c)Conditioning of Boiler Water

Due to continuous evaporation of boiler water inthe drum, minor impurities present in the feedwater, concentrate to high impermissible levelsin the boiler water. Rise in hardness of water(conductivity), content of chlorides, silica etc.,have to be kept to a minimum to prevent scaleformation or deposits, in the evaporator tubes anddrum.

Sample of Boiler water is collected from thecontinuous blow down line through a samplecooler. If the analysis indicate high conductivity,(chlorides, silica) etc., small pre-determinedamount of water is continuously drained fromthe steam drum through the continuous Blowdown valve CBD-104 with a needle valve forcontrolling the ßow to reduce their concentrationto permissible levels in the steam drum.

Tri-Sodium phosphate is dosed into steam in theboiler drum to maintain a phosphate concentrationand a pH. The Phosphate has the capacity toconvert hardness producing insoluble calcium/magnesium salts to soluble sodium salts, whichare drained through the blow down. A typicalreaction can be as follows.

3 CaSO4 + 2 Na3 PO4 →Ca3 (PO4)2↓ + 3Na2SO4.

The dozed phosphate also provides desiredalkalinity to the boiler water. An alkaline pHminimizes the possibilities of corrosion.

The following facilities have been provided in thesteam Drum for the above operations:

(d) Emergency Blow Down (EBD)

During WHRB startup situations arise resultingin high drum water levels. As high drum waterlevels are not permissible provision has beenmade for quickly draining some water from theboiler drum under this condition. The EBD line,drawn from the entire length of the drum consistsof a manually operated inlet isolating valveEBD-VG-101, a manual operated parallel slideemergency blow down valve EBD-102, The EBDline drains to the blow down tank. The isolatingvalves are normally kept closed and are openedonly when emergency blow down has to be done.Ensure that the EBD should be close to BlowDown tank so that the operator can easily operatethe valve during emergency.

(e) Level Gauges, Level Indicators, LevelTransmitters

As maintaining normal water level in the steamdrum is one of the important parameters to be

Section B 20


monitored and controlled, elaborate provisionsfor level instrumentation has been made onthe Steam Drum. Brief mention of theseinstrumentation will be made in this section.

(f)Continuous Blow Down Line

To enable the water drained from the drum toreßect the true composition of Boiler water, aperforated pipe 25NB is laid along the water spaceof the drum and connected to the CBD line tothe Blow down tank. There is one isolating valveCBD-VG-101,a needle valve CBD-104. The valvefor Boiler water continuous Blow down (CBD) ispositioned to drain continuously a pre-calculatedquantity.

(g)Sampling Line

The CBD line provided to the sample coolerthrough two isolating valves CBD-VG-102 &CBD-VL-103.

(h)HP (Phosphate) Dozing Line

Dosing of phosphate to the Boiler water is to bedone in a manner that it quickly mixes with thewhole of Boiler water. To enable this, a perforatedpipe, 25 NB has been laid along the length of thedrum and connected to the HP dosing line througha non-return valve HPC-VC-117 and an isolatingvalve HPC-VG-118.

(i)Level Gauges (11-LG 143 / 144)

The Level Gauges is of multi-port type. The top ofthe gauge glass is connected to the steam sideof the drum through two isolating valves. Thebottom portion of the gauge glass is connected tothe water side of the drum through two isolatingvalves. Care is taken to ensure that the center lineof the center port coincides with the center line ofthe drum which is the required normal water level.Twin drain valves are Þtted to each gauge. Thedrains normally remain shut when the gauge is inservice with steam side and water side isolatingvalves open.

The level gauges are simple direct readinginstruments and serve for quick and accuratereading of the drum level. During the start up ofWHRB, level gauges may be the only instrumentswhich can be relied upon as other instrumentsmay not be accurate. The level gauges are alsoused to verify the readings of other instruments.

The level gauges being located at the drumlevel are not convenient for regular operation ofthe Boiler. The level gauges however must bemaintained in service as IBR requires that atleastone of the level gauges must be in service tooperate the WHRB.

3.2.1 Drum Level Control

Control of water Level in the steam relies on thefollowing Instruments.

Level Transmitters and indicators 11-LI- 142A /142B.

WHRB ID fan trip has been envisaged on Drumlevel very Low conditions. To avoid a false tripfrom malfunction of any one instrument, two outof the above three instruments must vote for a tripaction.

The level transmitters provide drum level signal tothe single element and three element controllers.

The above level instruments are connected to thesteam drum, steam and water space through twinisolating valves. The reading of the steam drumwater level by the above instruments are sensitiveto the drum pressure.

Transmitter 11-PT-145 (through twin isolatingvalves) mounted on the steam drum, providea pressure compensation signal to the leveltransmitters, so that their signals represent truelevel neutralizing variations due to pressurechanges. They also provide steam drum pressuresignal to DCS.

11-PG-146 is a local instrument indicating Drumpressure at the drum elevation.

3.2.2 Drum Safety Valve

To protect the boiler and personnel againstconsequences of abnormal pressure increasescaused by sudden load decrease, malfunctionof Þring system, closure of steam valves etc.,two spring loaded safety valves have been Þttedon the drum. On increase of steam pressurebeyond a pre- determined set value, the safetyvalve opens automatically to relieve steam fromthe drum to the atmosphere. The safety valvecloses when the steam pressure falls by around4% of the set value. IBR prescribes norms forinstallation, care and testing of the safety valves,which are mandatory. Safety valve, 11-PSV-001and 11-PSV-002 along with the 11-PSV-003 havethe capacity, as per IBR, to relieve steam fromthe WHRB in such a manner that pressure riseabove 103% of the working pressure is preventedon any condition.

As the spring loaded safety valves result in highnoise levels when they open, the exhaust of thesafety valves are connected through a silencer tosubstantially reduce the noise level.

Installation, adjustment and maintenanceinstructions for safety valves are enclosed which

Section B 21


may be referred for a full understanding of thesafety valves.

3.3 Silencer

Mention was made that the exhaust of varioussafety valves, steam dump & startup valves areexhausted through Silencers. The Silencers areacoustically & mechanically designed to attenuatethe large noise made during operation of thesevalves

The silencers are made out of suitable casing inwhich the sound absorbing materials are packedin a certain pattern & wrapped by scrim cloth andwire mesh to avoid �ßy off� of sound absorbingmaterials during operation of silencer at high ßowrates

The process ßuid enters the annular spacebetween the sound absorbing materials packingwhere the sound energy is absorbed throughoutthe length of the silencer.

The Silencers are mounted on separate structureson top of the WHRB and the exhaust pipes fromthe valves are connected to the silencers.

As the silencer contain no moving parts, nooperational care is needed except opening thedrain plug provided in the drain line, once in threemonths to drain the line.

3.4 Air Vent

An air vent on the drum to vent out air during initialboiler Þlling, before start up and during start up.During start up, the air vents are closed at a drumpressure of 2 Kg/cm² (g) and when copious steamis passing. The air vents are opened after shutdown of the boiler when the boiler pressure fallsto 2 kg/cm2.

3.5 Evaporator

EVAPORATORFigure 1

The Evaporators convert hot boiler water receivedfrom the Drum through down comer pipes intoa steam water mixture, by absorption of heatfrom the Coke oven exhaust gas. The steamwater mixture is led back to the drum from theevaporators through riser pipes.

There are two sections of Evaporators,Evaporator 1 & Evaporator II.

The Evaporators are hung from the top headersin the ßue path, on two guide supports andone anchor support with provision for thermalexpansion downward & in the sides.

Hot water ßow to the evaporators from the drumand steam / water mixture to the drum from theEvaporators through risers. A down comer headerof the Evaporator spans all the Evaporator panels.The top headers of the panel are connected tothe drum by riser tubes .The circulation throughEvaporator panels takes place as follows

� Heated Boiler water from the drum ßowsthrough the two down comer pipes to downcomer header.

� From the down comer header, the hot waterßows to the lower headers, and then throughEvaporation panel tubes, to the Evaporationpanel top headers. During its passage through

Section B 22


the Evaporation panel tubes, the hot waterabsorbs heat from the exhaust gas of the cokeoven and gets converted to a water/steammixture. This circulation is assisted by thehigher density of water in the down comercompared to the lower density of water / steammixture in evaporator and riser tubes

� The water / steam mixture from the top headersof the Evaporation panel, ßows in the steamdrum.

� In the steam drum, the steam water mixtureßows through the separators where water &steam are separated and saturated steamßows to the Superheaters. Seperated watermixes with boiler water to ßow through theEvaporator panels again.

3.6 Super Heater

Superheating of saturated steam from drumis done in two stages in Superheater I & inSuperheater II. Between Superheater I & II, anattemperator is located to control the temperatureof Þnal steam outlet at 485°±5°C.

Superheaters are made of modules, eachconsisting of a top header and a bottom header,with tubes between the headers. Superheatermodules are hung from their top headers withprovision for thermal expansion down wards & inthe sides.

3.7 Super Heater I

Saturated steam from the drum ßows to the Þrstsuper heater top header of Superheater I. Fromthe top header of the SH l, steam ßows throughthe panel tubes to the bottom header of the samepanel, absorbing heat. Then the steam ßowsthrough the super heater II.

Super Heater I top header (being the top mostpoint) is provided with Air vents (HPS-VL-106 &HPS-VG 105). The interconnecting pipes of theSuperheater and lower headers (Lowest point),are provided with two drains (HPS-VG-107/108).These drains are operated manually. The airvents & drains are opened before light up of theboiler. They are closed at a drum pressure of 2To 5 Kg/cm².

3.8 Attemperator

The function of the attemperator is to control thetemperature of HHS steam at Superheater I outletand Super heater II inlet to 410°C.

An inter-stage attemperator is provided inthe superheater to maintain the Þnal steamtemperature. Spraying a controlled quantity offeed water into the superheated steam lowers itstemperature as it looses some heat in evaporatingthe sprayed water.

The attemperator is a header, whichaccommodates an inner sleeve shaped like aventuri. A spray nozzle is Þxed at the entranceto the restricted venturi section. The sleeveis held in position Þrmly by the locating pinswelded to the header at the steam entry side.The sleeve is free to expand at the steam exitside. Water is sprayed through the spray nozzle.The steam passes through the venturi picks upthe spray, which completes the evaporation andthoroughly mixes the steam. The connection ofthe inlet to the spray nozzle embodies a thermalsleeve construction to protect the steam line fromtemperature differential between the spray waterand the steam. A drain connection is provided atthe exit of the attemperator.

3.9 Super Heater II

Superheater II receives the steam from bottomheader of Superheater I. From the top header ofthe SH II, steam ßows through the panel tubes tothe bottom header of the same panel, absorbingheat. Then the steam ßows into main steam line.

Super Heater II top header (being the top mostpoint) is provided with Air vents (HPS-VL-110 &HPS-VG 109). The interconnecting pipes of theSuperheater and lower headers (Lowest point),are provided with two drains (MSS-VG-101/102).These drains are operated manually. The airvents & drains are opened before light up of theboiler. They are closed at a drum pressure of 2To 5 Kg/cm².

3.10 Steam Temperature Control Loop

Attemperator spray control is designed tomaintainthe steam temperature at 485 deg C. As the heatpickup in the superheater increases with load, thespray water requirement increases with load.

The spray water line for the Attemperator, spraywater is obtained from the Boiler Feed water main,before the ßow transmitter 11-FE 137. The spraywater line consists of the following.

An manually operated isolation valveDSW-VG-101. The isolation valve needs to beopened when attemperator is to be taken intoservice.

Section B 23


Drain valves DSW-VG-112/113, these drainvalves are opened to drain the line formaintenance.

Pneumatically operated ßow control valve11-TCV-153. The ßow control valve isprovided with inlet/outlet Isolating valvesDSW-VG-102/108. The inlet/out Isolatingvalves remain normally open. The drainvalves DSW-VG-103/104/106/107 which remainnormally closed. These drain valves are openedafter closing inlet/outlet Isolating valves, whencontrol valve is to be taken for maintenance.

The spray water line connects to the spraynozzle of the attemperator through a non returnvalve DSW-VC-111. Pressure gauge 11-PI-159,indicates pressure of the spray water ßowing tothe nozzle.

Temperature Indicators 11-TE-151 & 11-TE 152provides steam temperature indication before andafter the attemperator to judge the effectiveness ofattemperation.

4 Main Steam Piping

The SH steam line connecting the top header ofSuperheater II to the plant steam main.

This line incorporates the following.

� ELECTRICALLY OPERATED SH STEAMSTOP VALVE 11-MV 302 This valve Isolatesthe WHRB from the plant / Common steamheader. This valve is provided with anelectrically operated, integral by pass valve11-MV 303.

� SAFETY VALVE 11-PSV-003 This is a springloaded, valve set at 71 Kg/cm², pressure toprotect the boiler against over pressures. Thesafety valve is similar to Drum safety valvesdescribed earlier. The exhaust of the safetyvalve is piped to a silencer to reduce the noiselevels when the safety valve is operating. Thesilencer is mounted on a separate structure ontop of the WHRB.

� START UP VENT VALVE 11-PCV 154 is anpneumatically operated regulating start up ventvalve. 11-MV 301 is an electrically operatedIsolating valve preceding 11-PCV 154. Theoutlet of the start up vent valve is exhausted toatmosphere through a silencer. The start upvent valve is to be kept open while start up. Ifprovides initial steam ßow for the superheaters.

� STEAM LINE DRAIN The steam line drainconsists of the following valves manuallyoperated MSS-VG-101/102/108/109. These

valves are kept opened during start up upto 5kg/cm2 pressure.

� FLOW NOZZLE Flow nozzle 11-FE-157 isinstalled on the steam line to provide impulseto upstream & down stream pressure readingsto steam ßow transmitter 11-FT-157. The ßowtransmitter reading, after steam pressure &temperature compensation is used for thefollowing,

� Steam ßow reading. (11-FI 157)

� Steam ßow compensation for feed ßow,steam temperature controllers

� SH STEAM TEMPERATURE INPUTTemperature transmitter 11-TE 153 provide thesteam temperature input for the following

� Temperature Indicating controller 11-TIC-153which provides steam temperature High &low alarms and also controls positioningof the attemperator spray control valve asdescribed earlier.

� Temperature compensation signal to the feedßow, steam ßow instruments.

5 Operational Control

This section explains the major operational controlpoints described in this chapter.

Steam Drum

� Maintain Feed water, Boiler water quality, andphosphate concentration.

� Maintain water level in the drum withinpermissible low and high levels. The protectionsystem envisages boiler trip at very high andvery low levels, which should not be by passed.

� Maintain drum level gauge glasses LI 3401 &PI 34102 in good working condition. Operatorsmay verify the readings of level transmitterswith the readings of the drum level gaugeglasses once a day.

� Drain superheaters thoroughly during startup.

� THERMAL STRESSES IN DRUM DURINGSTART UP AND SHUT DOWN Steam Drumis a large cylindrical shell. Before light up of aboiler, the inner and outer surfaces of the drumare at the same temperature. When boileris lighted up, the inner surface gets heatedup Þrst by the water (and then by steam) andtransmits heat to the outer surface of drum.The heat transfer is by conduction and is a bitslow. For short time after light up, there can be

Section B 24


differences of temperature between steam andwater surfaces of the drum. Such a differencecan set up thermal stresses, which are notdesirable, and an alarm sounds at DCS. Tominimize the thermal stresses, the operatormust restrict the Þring rate when starting theWHRB by modulating the diverter damper.Boiler water temperature rise rate must not beabove 56 0C per hour till operating pressureis reached.

� SWELLING During WHRB startup, as theBoiler water temperature reaches 90°C,there is an increase of water level caused byincrease in the volume of hot water. Suchswelling, if not controlled, can cause a HighLevel trip. To avoid this, initial Þlling is normallyrestricted to low level (say � 100 to 150 mm)and the smart Operator anticipates a swell anduses the IBD to drain and control the level.

� Do not operate the WHRB with safety valvesgagged. Passing safety valves must beattended during the next planned shut down.

Super Heaters & Attemporator

� Super heaters must be drained after shut downand cooling of the boiler. They must also bekept open before a cold start up till 2 - 3 kg/cm2pressure is built up. During hot light ups theyare opened for a few minutes.

� Soot blowing of Super Heaters may be doneonce a shift to keep their surfaces clean, itliquid fuels are burnt.

� Super heat steam temperatures at exit ofSuper Heater- 1, Super Heater 2 main steamtemperatures must be monitored to see thereis no excessive heat pick up. Compare theseÞgures with predicted performance values.High steam temperatures may mean highmetal temperatures.

General

� Boiler water can be drained after a shut downonly after depressurizing to 2 kg/sq. cm andafter cooling to 80 °C

� Draining of Boiler water must preferably donethrough the blow down tank.

� If a tube failure is detected, it is advisable toplan for an early shut down. It may be possibleto quickly repair the failed tube and returnto service. If the shut down is in-ordinatelydelayed, there are possibilities of largersecondary damages, which may prolong theshut down, required for repairs.

� Manually operated valves must be closed handtight only. Use of levers on hand wheels is notdesired.

5.1 Steam and Water SystemTechnical Performance Data

WHRB HEATING SURFACES

ECO Modules (Pass 2) - 827.33 m²

Evaporator I & II - 662.6 m²

Superheater I & II - 200.45 m²

WHRB Design Pressure : Maximum workingpressure - 75.0 kg / cm2 (g)

Set pressure and capacity of safety valves

Tag NoSet Pressurekg / sq. cm

(g)

Capacity(Kg/Hr)

11-PSV-001(Drum) 74.5 7500

11-PSV-002(Drum) 75 7500

11-PSV-003(MS Line) 71 5000

Drum Level Gauge

Normal Water Level Drum Axis (�0� mm)� 50 %

High Level Alarm 65%

Low Level Alarm 35%

Low Level Trip 25%

6 Boiler Blowdown System

AIM

This chapter describes the WHRB blow downsystem for safe draining of high pressure / Hightemperature steam and water from the boilerusing the blow down tank.

System Description

The P & ID of the steam and water system showsthe various drains from the WHRB, SH steam lineand the soot blower system. Large quantities ofsteam or high pressure / temperature water arenot to be drained through open canals for thefollowing reasons:

a) Such draining will cause splashing of highvolumes of steam, which can be a nuisance by

Section B 25


the noise it creates, and also it affects the visibilityaround the draining area.

b) High temperatures of these drains can causescalding injuries to workmen who may come incontact with it.

c) The force and temperature of these drains willerode the linings of the drain canals.

d) Low-pressure steam, which can be recovered,if required, is wasted.

HIGH PRESSURE / HIGH TEMPERATURESTEAM AND WATER DRAINS

Sr.No. Source Valve Nos Temp of drain °C Frequency of usage

1. Continuous blowdown CBD-104 291°C

Continuous, quantitydepending on qualityof baler water

2. Emergency blowdown EBD-102 Upto 291°C

Occasional duringhigh levels in drum,during start up

The drains indicated above table are connectedto the blow down tank. The blow down tankis capable of separating steam from the drainwater. The drains are connected tangentially inthe upper half of the drum, to direct the drain ßuidcircumferentially around the inner wall of the tank,to aid separation of steam and water by theirdifferences in densities. A vent line of the tank isconnected to Deaerator.

Level of water is maintained by a control valve11-FCV-137 through level controller 11-LIC-142

6.1 Other Drains

The drains indicated above table are connectedto the blow down tank. The blow down tankis capable of separating steam from the drainwater. The drains are connected tangentially inthe upper half of the drum, to direct the drain ßuidcircumferentially around the inner wall of the tank,to aid separation of steam and water by theirdifferences in densities. A vent line of the tank isprovided open to atmosphere.

It can be seen that drains have been provided inthe feed water line and the attemperator spraywater lines connected to the drain canal. Asthese drains are either for operation to drain theselines after an isolation or for short time duringcharging, their connections to the open canal isnot expected to pose a problem.

� All level control station drain

� All pressure control station drain

� Steam drum level indicator.

� Steam drum safety valve drains

� Sample cooler sample let off drain

6.2 Continuous Blow Down Control

CBD control involves the following operations

� Obtaining a sample of boiler water from thesteam drum.

� Analyzing the sample for conductivity,hardness, NaCL, Silica, Fe, etc., and workingout a rate of draining of boiler water to maintainthe concentrations as suggested in Boilerwater.

� Manually positioning the CBD valve is to bedecided depending on the sample analysis

� Repeating the sampling, analysis andrepositioning the CBD valve after certaininterval is necessary to maintain the requiredBoiler water quality. This system of manualcontrol requires the services of a sampler, achemist and a laboratory round the clock.

The arrangements provided for CBD control is:

� A perforated pipe, laid along the water spacein the steam drum connects through a stub tothe continuous blow down line.

� CBD line from drum connects to the blow downtank.

� A tap off from the CBD line is taken to thesample cooler for continuous analysis of boilerwater conductivity and also for a grab sample

Sampling of CBD / Boiler water is done in oneof the sample coolers of the sampling package.This package provides analysis of the followingsamples to provide a comprehensive informationof quality of steam and water of WHRB.

� Samples of saturated steam from Top saturatedsteam header of WHRB.

Section B 26


� Samples of main steam from Steam headerof WHRB.

� Samples of boiler water (CBD) from the steamdrum of WHRB.

� Samples of feed water.

While all the samples above are analyzed forconductivity by separate analyzers, the CBDsample and the feed water samples are analyzedin addition for pH also. A brief description of thesalient features of the sample cooler of the CBDanalyser is given. Care of other sample coolersis identical. CBD-104 is normally kept open tomaintain small continuous ßow of boiler water tothe blow down tank. This is required to ensurethe sample at any time to the sample cooler istruly representative of the sample being analysed.This continuous ßow also ensures that these linesdo not get chocked for want of adequate ßow.

Valves CBD-VG-102 & CBD-VL-103 are isolatingvalves to the sample cooler which remains open.The sample cooler is a tube and shell type heatexchanger with the boiler water ßowing throughtubes and the cooling water in the outer shell, withthe speciÞc purpose of sampling. Cooling wateris provided from the plant fresh water (DM watercircuit) in a closed loop.

Tri-sodium phosphate dosing to Boiler water tomaintain its phosphate content at 2 to 6 PPM. Thetri-sodium phosphate at the suggested levels,maintains the alkalinity of the boiler water (pH 9.5to 10.2) and also converts the harmful, insolublecalcium and magnesium salts which forms theresidual hardness of boiler water, to benignsoluble, sodium salts, in the form of a soft sludge,to be drained by the CBD. Phosphate dosing,prevents corrosion of the water washed parts ofthe steam drum and the evaporator tubes, byadjusting the speed or the stroke of the pumpprovided as described below. Excess as well asreduced phosphate levels in Boiler water shouldbe avoided. (The phosphate dosing is also sometimes called as "HP dosing" as the pump useddevelops high pressure to dose against the boilerdrum pressure).

7 Chemical Dosing & SamplingSystem

7.1 HP Dosing System

The equipment, which are of stainless steel,provided for phosphate dosing (�HP dosing�), areshown in P & I diagram and consists of

� A mixing tank for preparation of 5% tri-sodiumsolution.

� Two dosing pumps (with one stand by)� DM Water source for preparation of thephosphate solution as well as for ßushing

7.2 Mixing Tank

The Mixing tank is a stainless steel coveredcylindrical vessel of 150 litres capacity; with alevel indicating gauge glass (11-LI-701), DMwater inlet line (with a manual isolating valve)HPC-VL-101, an over ßow drain line, a tank drainline with a manual isolating valve HPC-VB-121, abasket for placing required quantity of tri-sodiumphosphate powder for preparation of the solution.A solution inlet connection to the pumps witha manual isolating valves HPC-VB-105/106. Amotor operated stirrer is also Þtted for preparationof chemical solutions.

The level of the mixing tank is monitored by levelswitch (11-LSL-701). Availability of a minimumlevel is a required permissive condition for startingor continued service of a dosing pump.

7.3 Preparation of 5% PhosphateSolution in the tank

� Tank drain valve HPC-VB-121 is closed.� Gauge glass inlet cocks are opened and itsdrain is closed.

� The lid of the tank is opened, and a calculatedquantity of phosphate to prepare 150 litres ofsolution is placed in the basket and lid closed.

� The water inlet valve HPC-VL-101 is openedto admit water (from the DM water line). Thelevel gauge is watched and when the level inthe tank is nearly full, the water inlet valve isclosed.

� The stirrer is placed in service for 30 minutesby operating its switch in the local panel.Availability of a minimum level is a preconditionfor starting and running of the stirrer.

7.4 Phosphate Dosing Pump

Two phosphate dosing pumps are provided, outof which one is in service at a time, and the otheris a standby. The pumps are plunger operatedreciprocating, positive displacement type. Thestroke of the plunger can be altered. The motor isprovided with a variable frequency drive througha gear box for continuous speed control. Thevendor manual of the pump and gearbox is to beprovided for full information on construction andparts detail.

Each pump is connected to a common dischargeline with the following valve arrangement:

Section B 27


� An inlet valve with a "Y" strainer at the pumpinlet. Y strainer traps dirt or other solid particlesin its basket. The Y strainer is to be cleanedonce a month, after stopping the pump andclosing its inlet and outlet isolating valves.

� On the discharge side of the pump, a pressuregauge and an outlet isolating valve is Þttedbefore the common discharge line. A safetyrelief valve has also been Þtted on thedischarge line to relieve any over pressures incase of closure of valves on the discharge line.The outlet of the relief valve is returned to themixing tank. The relief valve must be tested forits operation at the set pressure atleast oncea year. The pump must not be operated withthe relief valve continuously operating. (causeof relief valve operation must be found andrectiÞed).

� The common discharge line is connected tothe HP dosing line of the steam drum throughan NRV and an isolating valve1. The isolatingvalve is veriÞed open before boiler light up andnormally remains open all the time. Phosphatedosing is through a perforated pipe along thefull length of the water space in the drum.

Availability of a minimum level in the mixingtank is a pre condition for starting or running ofthe dosing pumps. Out of the two pumps, onepump is selected for service and the other is inreserve (DCS macro, Local panel). The pumpsare interlocked such that when a working pumptrips, the reserve pump starts automatically.

A phosphate pump is placed immediately inservice after the WHRB start up in the followingmanner:

� Boiler water sample is analyzed and phosphatecontent is determined.

� The pump is prepared by opening the outletvalve from the mixing tank, opening the inletand the two outlet valves of the pump. Twominutes are allowed after opening the inletvalve for the pump to get Þlled with phosphatesolution. The pump is started by switching on

the motor. The pressure gauge is observed. Itshould show a reading, higher than the steamdrum pressure. An accumulator on the pumpdischarge line dampens the pulsations whichotherwise would be there as this is a positivedisplacement reciprocating pump.

� Any abnormal noise from the pump, motoror gearbox is noted. The safety relief valveshould not also be operating. If there are noabnormalities the pump is allowed to run.

� Every four hours, the phosphate content in theboiler water is checked by laboratory sampleanalysis and also by the pH meter. The pumpspeed stroke is increased or decreased tomaintain the phosphate content within 8 to 10PPMS by continuous pump operation.

� The phosphate solution level is observed in themixing tank by the gauge glass. If the levelfalls to 25% of the gauge glass level, additionalsolution is prepared as stated above.

FLUSHING THE PHOSPHATE PUMP ANDTHE LINES WITH WATER DURING LONGSTOPPAGE OF THE WHRB:

If the WHRB is to be stopped for more than a fewdays for servicing or maintenance, the phosphatepumps and the line are ßushed with water to keepthem clean in the following manner.

A (ßushing) line is connected from the tanksolution preparation DM waterline to the inlet lineof the pumps . The pump which was in serviceearlier is run, for about 30 minutes to one hour.DM Water ßushes the phosphate solution fromthe pump and the lines to the steam drum andcleans them. The pump is stopped. The outletvalve from the mixing tank, is not opened till theboiler is again lighted and a phosphate pump isrequired in service. At that time the isolating valveon the DM line is closed.

NOTE:Do not operated the Stirrer of the HPdosing pump when the HP tank is dry or notÞlled with water or the dosing solution. The dryoperation of the stirrer can lead to failure of thestirrer (misalignment of the stirrer).

Section B 28


7.5 Water And Steam Quality ControlAnd Monitoring

AIM

This chapter describes the standards for the boilerfeed water and boiler water for corrosion and scale

free operation of the WHRB and for obtaining puresteam. Methods of control of boiler water are alsoexplained.

Suggested quality of boiler feed water (andattemperator water) fed to the WHRB is given infollowing table:

PARAMETER Max. permissible value

pH at 25°C 8.5-9.5

Total hardness as CACO3 Nil

Chlorides as NACL Not traceable

Silica as SIO2 <0.02ppm

Total Iron as FE < 0.01 ppm

Copper as CU < 0.003ppm

Dissolved Oxygen < 0.007cc/lit

Sodium Sulphate Not traceable

Residual Hydrazine Traces

Organic matter Nil

Oil Nil

Total dissolved solids < 0.1 PPM

Conductivity at 25°C after cation exchanger andCO2 removal < 0.15 micro siemens per cm

Total CO2 Nil

Sodium + Potassium Not traceable

Section B 29


Note

� Alkaline levels of feed water minimizescorrosion of steel

� Chlorides, Silica, Iron, Copper, Organicmatter etc., present in the feed waterconcentrate further in Boiler water.Their higher concentration calls forincreased blow down (CBD) of boilerwater causing loss of useful heat

� Silica in boiler water vaporizes to SiO2and escapes through steam

� Copper present in water, deposits onthe inner surfaces of evaporator tubesand is harmful

� Chlorides in boiler water depressthe pH level and renders boiler wateracidic and may cause acceleratedcorrosion.

� Oxygen in boiler water promotescorrosion of boiler tubes

� Oil present in feed water depositon tubes and interferes with heattransfer. Considering all these factors,maximum permissible values forcontaminants in feed water have beensuggested in Table - 8 .

Following TABLE gives the Boiler Water Quality tobe maintained in the Drum.

PARAMETER MAX permissible

Conductivity at 25°C after neutralization. < 50 micro siemens/cm

pH value at 25°C 9.5 to 10.2

Silica as SiO2 <1.2 mg/kg

Sodium Phosphate as PO4 2 to 6 mg/kg

�p� value < 0.1 m Val/kg

Minor permissible contaminants present in theWHRB feed water concentrate to high levels inboiler water due to continuous evaporation in thesteam drum - evaporator circuits. Two controlsare exercised on Boiler water to avoid corrosionof WHRB tubes and the drum water - washedsurfaces. The controls are :

� Continuous blow control to restrict thecontaminants to prescribed levels suggestedfor Boiler water ( Table � 9 )

� Tri-sodium phosphate dozing to convertthe hardness producing insoluble calcium,magnesium salts to soluble sodium salts whichcan be drained by CBD and to maintain thealkalinity levels of boiler water.

7.6 Maintaining Quality of Steam

Good Quality steam is obtained if the followingrequirements are met:

� Proper assembly of bafßes, demister pad inthe steam drum as per erection instructions(checked before commissioning of the Boiler)

� Boiler feed water as per norms as suggestedabove. (monitor the feed water conductivity &PH analysers)

� Control of Boiler water quality as suggestedabove.

� Monitor the saturation steam & main steamconductivity

Section B 30


� Increase of saturation steam conductivity maybe a warning for check of drum internals ormaintaining high water levels in steam drum.

It should be understood that if the quality of Boilerfeed water deteriorates, the steam quality isdirectly affected as the attemperator spray wateris by boiler feed water..

After several years of service, during a boilerover haul, bafßes and demister are checked fordamage or erosion holes, which may bypasssteam from the separation devices. Steam whichbypasses the separation devices carry with itmoisture, with its salt contaminants to steam.

Higher than permissible levels of Silica in boilerwater will result in Silica carry over in steam.

7.7 Operational Control

� The water chemistry for determining lowlevels of impurities in water calls for specialinstruments, special analytical procedures andan experienced chemist. These should beavailable from the time of commissioning theboiler.

� In a chemical process plant, in spite of the bestavailable demineralization facilities the boilerfeed water may occasionally get contaminatedby return condenses from the system. Aprocedure to systematically check the returncondensates (particularly for contamination byFe, Chlorides and Oil) must be established andcontaminated condensates must be discarded.

� pH & Conductivity meters must be calibratedonce a month.

� Phosphate dosing must be adjusted forcontinuous operation.

8 Flue Gas System

This chapter describes the sponge iron kilnexhaust ßow through the WHRB, insulation andcasing of WHRB and the Stack, various sealingair connections are also indicated..

8.1 System Description

The steam drum & WHRB pressure part panelsare supported on column structures. Insulation& steel casing is applied enclosing the panelsto provide a gas tight passage for the exhaustgas from the Sponge iron kiln. WHRB panels &drum are supported on structures. The panelsare covered fully with insulation and aluminumscladding. The insulation is held by strips andthe screws as shown in the respective drawing.Exhaust gas from the Sponge iron kiln enters

the WHRB through an expansion bellow. Thefollowing are the instruments in the ßue gassystem.

Exhaust gas from the Sponge iron kiln entersthe WHRB through an expansion bellow. Thefollowing are the instruments in the ßue gassystem.

BEFORE SUPER HEATER:

� Flue gas pressure at DCS, from pressuretransmitter 11-PT-160.

� Temperature transmitters 11-TE-162 &11-TE-164 for remote indication in DCS.

� These temperature transmitters measure thetemperature of exhaust gas. This is providedto safeguard the Superheater II, SuperheaterI, Evaporator panels.

� Pressure transmitter for remote indication11-DG-161/163

AFTER SH II

� Temperature indication at DCS 11-TE-165.

(An increase in pressure drop for the same inletconditions or drop in heat pickup may suggestfouling of SH II panels and a need for soot blowing)

AFTER SH I

� Temperature indication at DCS 11-TI-167

� Local pressure indication 11-DG-166

AFTER EVAPORATOR I

� At DCS 11-TE-168 the instruments are formeasuring the heat pickup in Evaporator I andto institute soot blowing if fouling is suspectedin Evaporator panels.

� Local pressure gauge 11-DG-169 formeasuring draft.

AFTER EVAPORATOR II

� At DCS 11-TE-170 the instruments are formeasuring the heat pickup in Evaporator I andto institute soot blowing if fouling is suspectedin Evaporator panels.

� Local pressure gauge 11-DG-171 formeasuring draft.

AFTER ECONOMISER

� AT DCS : Temperature indicator 11-TE-172 tomeasure the heat pickup in Economizer and toevaluate fouling if any on Economizer panels.

� Local pressure gauge 11-DG-171 formeasuring draft

STACK (CHIMNEY)

Section B 31


The oven exhaust gas after ECO is exhaustedthrough the Stack. The stack is a hollowcylindrical structure (Customer scope)

Aviation warning lights are Þtted at two elevationson the stack. Sampling probes for measurementof CO, NO2 & SO2 are Þxed at two suitableelevations on the Stack. There are Þve platformsproviding access to the aviation lights, sampleprobes and ease of repainting the Stack. Theplatforms are accessible from the ground byladders. On the top 20metres of the Stack, helicalwind breakers are built around the outer shell, toprovide stability to the Stack against wind forces.


� The anticipated performance Þgures bothsteam / water and gas side has been givenin following section. The operator shallfamiliarize himself with these Þgures. Elaborateinstrumentation has been provided to measureeach of these factors. Alarms also havebeen provided to alert the operator in case ofdeviations for several of these readings

� Operator attention is needed particularly forthe following - Kiln Exhaust Gas inlet pressureand temperature - Gas side pressure andtemperature drop, Steam/Water side heat pickup across pressure parts like,

� SH II� SH I� Evaporator Panels� ECOEvaluating these Þgures the operator shoulddecide the need for soot blowing. (Or otherchecks during a shut down).

� Levels of CO, NOX, SOX emissions mustbe monitored and any abnormalities must bereported to the shift in charge

� Healthiness of aviation warning lamps are tobe check periodically

9 Soot Blower System

9.1 Soot Blower

AIM

Soot blowers, 09 in number, have been providedfor SH II, SH I, Evaporators and Economisers.A PLC based local control panel for operationand control of these soot blowers are provided.Vendor manuals of the soot blowers and the localcontrol panel have been included in Volume VIIIof this manual, which may be referred for detailsof their construction and mode of operation. Thischapter explains steam supply to the soot blowersand deals with the need for soot blowing, factorsdetermining the optimum frequency and care tobe taken during its operation.

9.1.1System Description

Operating environment of Soot blowers

Soot BlowerNumber LRSB LRSB LRSB & RSB RSB

Between Between Between BetweenPosition

SH II & I SH I & Evap I Evap I & II Evap II & Ecomodules

Angle of rotation° 0-360° 0-360° 0-180° 0-360°

9.1.2Steam Supply

Steam supply required for soot blowing is takenfrom the steam drum, which is at a pressure of 66

kg/cm². Pressure controller 11-PSV-147 exists onthe steam supply line to maintain pressure.

The Long retract soot blowers remain fullyretracted to their parking position when not

Section B 32


in use. The steam admission to the LRSB isautomatically established as soon as the LRSBenters the ßue gas path. Cleaning operation, byjetting steam from the LRSB takes place bothduring its advancing and retracting cycles. Thesteam ßow through the lance also serves to coolthe lance tube from the excessive heat of the ßuegas. For this reason, the LRSB should never beadvanced, When an WHRB is in service, withoutsteam, if an LRSB is being operated, occasionallyit may happen that it gets stuck in the extendedposition due to overload. ("Blower MechanicalJamming", Soot blower motor overload" Traveltime exceeded alarms on panel). When thishappens, steam from the lance nozzles will bejetting against the same position on the tubepanels which may cause on erosion of thosetubes leading to a possible tube failure at a laterdate. To avoid such steam cutting of the tubes,the operator must declutch and manually retractthe soot blower immediately using the handcranks provided (see soot blower vendor manual).("Travel time exceeded alarm"). Steam must notbe closed to the LRSB till it is fully retracted forcooling requirement. Special care is needed forretraction of soot blowers 1 to 3 which work inpossible high temperature zone which will getdamaged without cooling steam.

Soot blowers are operated in a deÞnite sequencein the line of ßue gas ßow, starting from SH IIthrough SH I, Evaporators, Economizer. Whena soot blower is operated, say from SH II, thesoot dislodged from it is likely to resettle onany of the subsequent heating surfaces (SH I,Evap II, II, ECO modules) etc. When the sootblowing is done in the speciÞed sequence, all thesoot, including those which resettle are cleared.Resettlement of soot however will be morepronounced on cooler heating surfaces (ECO) forinstance.

Frequency of soot blowing : When theWHRB are on line, once in a day may beconsidered. An optimum frequency can only beestablished by carefully studying the beneÞtsof soot blowing or excessive fouling caused byinadequate soot blowing. When the WHRB isin continuous service, a fouled super heater willmake attaining the design steam temperaturedifÞcult. Unabsorbed heat from Evaporatorsand Economizers will increase the ßue gas exittemperature from WHRB higher than design,reducing the thermal efÞciency. Effectiveness ofeach soot blowing can be studied by noting downthe following performance parameters before andafter soot blowing.

� Flue gas temperature across super heaters,Evaporators, Economizers.

� Feed water / steam temperature pick up acrosssuper heaters, Evaporators, Economizers.

� Spray water ßow through de-super heaterEffective soot blowing increases the heat pickup. De-super heater spray water ßow mayincrease.

It can also happen that there is no change aftera soot blowing. From a careful study of theseparameters, an optimum soot blowing programcan be established related to the fuel.

An effective soot blowing can only be done whenthe WHRB steam ßow is above 50% MCR. Sootblowing at lesser loads may disturb the ßue gasregime. The Þrst soot blowing after the WHRBstart up is done as soon as 50% MCR steam ßowis established on theWHRB. Similarly when a shutdown is planned on the WHRB for inspection ormaintenance, the last operation before reducingthe load below 50%MCR should be a soot blowingso that the panel tubes remain clean during theshut down without harmful effects of corrosion.

9.1.3Operation and Control

The operation & control is described by a write-upon sequential soot blowing operation

9.1.4Pre Interlocks

Soot blowing operation can be selected either inAuto mode from PLC or manual mode by usingselector (soft) switch available in PLC. In automode following interlocks need to be satisÞed forstarting the operation.

� All soot blowers in rest position, feedbacktaken from individual S.B. Limit switches

� SB Steam isolation valve open and drain valveclosed

With these, Soot Blowing in Auto Lamp will glow.Auto sequence can be started from PLC by givingstart command with following conditions in healthystate

� SB in Auto selected (a knob is provided in thecontrol room which can select the SB in Autoor Manual mode, to continue the sequence ofthe SB, Auto mode needs to be selected)

� SB sequence reset PB not operated

With this, auto sequence ON lamp will glow andsequence continues on sheet 3 for drain valve

Section B 33


open logic. Reset P.B. is used for resettingbefore restarting the sequence and resetting themechanical fault condition

DRAIN VALVE OPERATION (OPEN)

Drain Valve to be kept open before starting thesoot blowing cycle for LRSB and RSB. Thisensures removal of condensate accumulatedinside the piping.

The removal of condensate is important becausethe water if injected during soot blowing operationwill result in water hammering effect, erosion ofsoot blower lance, erosion of tube surface andmore temperature gradient than required at thatzone causing thermal stresses.

S.B. STEAM ISOLATION VALVE OPEN

Ensure that the inlet isolation valve MPS-VG-101is in open condition. The upstream anddownstream valves of soot blower pressurecontrol station should be in open condition.

DRAIN VALVE OPERATION (CLOSE)

Close the drain valves of LRSB and RSBsteam piping after ensuring complete removal ofcondensate.

However it is advisable to kee the drain valvescrack open during the entire soot blower cyclecompletion for continuous removal of condensateand maintaining the required steam temperature

9.1.5 SOOT BLOWING SEQUENCE

SB-1 (RETRACTABLE)

Sequence continues from SB -1 forwardingsequence starts with a time delay of 5 secs withfollowing satisÞed.

� Sequence continued to SB 2 conditionunhealthy. This ensures that there is no repeatoperation of S.B.1 after completion of its onecycle

� SB1 is pre-selected (if not pre-selectedoperation of SB1 is skipped and sequencecontinues to SB 2 or next pre-selected S.B)

� Forward position limit switch is not operated

� Retract P.B. is not operated

� SB Steam isolation valve is opened

� DV is closed

� Steam temperature is achieved

� SB 1 is not retracting

� SB 1 fault (overload) is not operated (contactfrom MCC)

Positive feedback of forwarding contactor in MCCis taken for SB1 forwarding lamp indication.

As soon as the S.B.1 forward position L.S.is operated in forwarding operation of SB-1, forwarding command shall break & SB1forwarding shall stop. Also if any of the abovementioned condition goes unhealthy stateforwarding shall stop. Simultaneously Retractingcommand shall start retracting operation withfollowing conditions satisÞed.

� Fault (overload) not operated

� S.B 1 is not forwarding

� S.B 1 rest position limit switch is not operated

In retracting operation when SB1 hits the restposition limit its retracting stop pulse commandstops the retraction. Sequence is continued tonext pre selected soot blower.

Manual operation of SB1 forwarding is possiblefrom Local P.B. when manual mode is selectedfrom PLC (which is Auto mode de selected).Manual operation of retracting is possible fromlocal P.B. in both auto and manual mode. Itis also ensured that if any of the soot blowersis somewhere in mid position when the powersupply is switched ON, the SB shall Þrst retractand comes to its rest position irrespective ofAuto/Manual mode.

Positive feedback of retracting contractor in MCCis taken for SB 1 retraction and lamp indication

SEQUENCE COMPLETE

With the sequence continued from SB Steamisolation valve close logic and following conditionsatisÞed sequence completes an respective lampglows

1. All soot blowers in rest position .

2. SB Steam isolation valve close

Sequence complete signal is used as preinterlocks.

MECHANICAL FAULT

In case, any of the soot blowers remains inoperation for more than 300 sec. Which is anabnormal condition in operation, mechanical faultalarm is generated. This condition shall occurbecause of mechanical failure of soot blower.Corrective action can be taken on the same

ELECTRICAL FAULT

In case Retractable soot blower trips on overload,indication Lamp shall glow. One commonoverload for all retractable soot blowers is

Section B 34


provided as at a time only one soot blower is inoperation.

GENERAL NOTES

� Open, close on commands going to actuatorsand MCC are isolated potential free contactsof relays.

� Actuators shall receive only open or closecommand from PLC other necessaryinterlocking of switch gears for open closeoperation is done inside the actuator integralstarter

10 Boiler Protection & Interlock

AIM

This chapter lists out various protections andinterlocks provided in the WHRB.

As the system protections and interlocks havebeen described in the preceding chapters alongwith the description of equipment, a listing ofthese protections will only be made with briefnotes on their signiÞcance. Testing of theseinterlocks & protections is to be done before theÞrst start up of WHRB and at suitable intervalssubsequently.

Safety Valve on Steam Drum & Superheater

To protect the boiler safety valves have beenprovided with set points and blow down capacitiesas indicated below

Sr.No Location Valve No Set pr kg/cm² Blow down tons/hour

1 Steam drum 11-PSV-001 74.5

2 Steam drum 11-PSV-002 757500

3 Superheater 11-PSV-003 71 5000

10.1 Alarms And Interlocks

Interlocks provided for various systems ensuresafe and sequential operation at any point ofoperation which includes start up, shut down andemergency conditions. Kindly refer the Section-Cfor the detailed description of the Alarms &Interlocks Description.


The interlocks are to be tested beforecommissioning. Repeat tests are advised once ayear. Any malfunction noted during operation hasto be attended early.

10.3 Automatic Control

AIM

To describe the automatic controls provided foroperation of the WHRB.

Steam Temperature Control

The steam temperature control has followingfunction:

To position the spray water control valve such amanner that S.H. steam temperature at outlet ofSH II is controlled at 540 Deg C.

The control acts on spray control valve, which is apneumatically operated control valve, positionedby positioner.

Drum Level Control

It includes:

� Single Element Control

� Three Element Control

SINGLE ELEMENT CONTROL After densitycompensation the drum level signal is usedfor indication, control and generation of, Lowalarm, and High alarm.Input goes as PV to thesingle element Controller 11 LIC-142A. Out putof this controller is feed to the level control valve11-FCV-137. Single element controller shouldbe used up to 30% load of the boiler. Abovethat select three element control to maintain andcontrol the Drum level with respective to boilerload.

In case of bad PV both control should go toManual mode automatically. And alarm should begenerated.

PV tracking and SP tracking should be providedto this controller for Auto/ Manual bump-lesstransfer.

THREE ELEMENT CONTROL

Section B 35


In Three element control O/P of 11 LIC-142Bgoes to the summation block where the steamßow signal (0-100%) is added to 11 LIC-142Boutput. Action of 11 LIC-142B controller isreverse. The output of summation block isused as a remote set point for the feed waterßow controller 11 FIC-137. Remote set pointcalculation is given below.

Remote SP for Water Flow Controller (11-FCV137) = Drum Level Controller (11-LIC 142B) O/Pin % + (Steam ßow signal (11-FT-157) in % * Gain)+ (Bias in %)

On Bad value of PV, the controller 11-FCV -137shall be automatically switched to manual mode.

� If (11-FCV 137) is put in manual mode, then(11-LIC 142B) is to be forced to manual mode.

� SP tracking shall be provided for (11-LIC 142A& B) in manual mode.

� (11-LIC 600A & B) SP shall track its PV inmanual mode and shall have its local setpoint.

Water ßow is measured using transmitter 11-FT-137 which receives DP from ßow nozzle 11-FE-137, the square rooting to be done at DCSside and is used as process variable for Feedwater ßow controller 11- FIC-137. The outputof 11- FIC-137 is used to control the feed watercontrol valve 11- FCV-137.

Steam ßow is measured using a steam ßowtransmitter 11 FT-157 connected to ßow nozzle;the steam ßow transmitter shall be square rootedat DCS side.

Pressure and temperature compensation ofsteam ßow is carried out to take care of errorsarising due to density variation of steam, whenboiler is operating at conditions different fromdesign conditions.

Comp. Steam ßow = Indicated steam ßow *[Square Root ({ (P1+1.033) * (T2+273) } / {(P2+1.033) * (T1+273) } ]

where

P1- Measured pressure signal (Kg/Cm2)

T1- Measured temperature signal in deg C.

P2- Design pressure (Kg/Cm2)

T2- Design Temp of steam, in deg C

[P2 = 66Kg/cm2 absolute & T2 = 485+5 Deg C]

11 LIC-142A Controller action should be direct i.e.Controller output will increase if PV increases.

The action of the 11 LIC-142B (Three Elementcontroller) is Reverse i.e. out put of the controllerwill decrease if the PV increases.

The action of 11 FIC-137 controller shall be directaction i.e. as the Feed water ßow goes above setpoint; the 11-FCV-137 should close (i.e. the 4-20mA output should increase).

(11 FIC 137) shall have only two modes ofoperation. 1. Manual mode 2.Cascade mode

(11 LIC 142A & 11-LIC-142B shall have only twomodes of operation namely. 1. Manual mode 2.Auto mode

SP shall track its PV in manual mode and shallhave its local setpoint.

Indications and alarms to be conÞgured as shownin the control schematic. Trends, Totalizers,indicators and alarms shall be conÞgured in theDCS as indicated the Control Schematic drawing.

Totaliser 11 FIQ-137, 11 FIQ-157 to be conÞguredin DCS.

Following are trip interlocks on Drum level LowLow

� a) ID fan trip

� b) Open ßue gas process stack inlet damper(11-DI-004)

� c) Close ßue gas damper to boiler inlet(11-DI-003)

� d) Close damper in recirculation line(11-DI-005)

FURNACE PRESSURE CONTROL

The furnace pressure is measured using pressuretransmitter 11 PT 160. This is used as a processvariable (PV) and is then compared with a Þxedset point in the Proportional-Integral controller 11PIC-160. The resultant control signal actuates thedamper actuator of the ID fan or VFD of ID fanmotor.

ID fan actuator close limit switch 11 ZSC-160 istaken to DCS as start-up interlock to start ID fanmotor when started in Bypass damper mode. Thisis to ensure that the motor starts under no loadcondition.

� Action of controller 11 PIC-160 is Direct. Theaction of the PID can be changed at sitedepending on linkage

� HIC-160A and HIC-160B shall have Auto/Manual selection.

Section B 36


� On Selection of VFD mode damper of samefan should not go to Auto mode

� Furnace presses Low & high alarms aregenerated from 11 PIC-160. � Trends,indications and alarms shall be conÞgured inthe DCS.

Note

� The ID fan not running signal is takenfrom drive logic to close the ID fandamper when ID fan not running.

� When furnace pressure is controllingthrough VFD mode then ID fan damperwill be 100 % open & controlling isthrough VFD

� When furnace is controlling throughdamper then ID fan motor is in fullspeed & controlling is through Damper.

STEAM TEMPERATURE CONTROL

The temperature of Þnal steam is controlled byattemperation i.e. by spraying feed water into thesteam after the primary super heater.

11 TIC-153 receives Þnal steam temperatureas the process value from 11 TT-153. Thetemperature controller shall have 485 °C set pointfor the Þnal steam temperature. The out put of theTIC will be given to the Attemperator temperaturecontrol valve 11 TCV-153. The controller shallhave Reverse action. The controller shall havePV tracking for manual to auto bump less transfer.

� Steam Temperature Low,High and High Highalarms are to be conÞgured from 11 TIC-153

� The action of the Steam Temp. Controller 11TIC-153 is Reverse

� The actuator of Steam Temp. Control valve: 11TCV-153 is air to close type.

� Fail safe action is Stay put /Tends to Open.

� Trends, indications and alarms shall beconÞgured in the DCS.

SOOT BLOWER PRESSURE CONTROL

The soot blower pressure is measured usingpressure transmitter 11 PT 147. This is used asa process variable (PV) and is then compared

with a Þxed set point in the Proportional-Integralcontroller 11 PIC-147. The resultant control signalactuates soot blower control valve 11-PCV-147.

� Soot blower pressure Low & High alarms areto be conÞgured from 11 PIC-147

� The action of the soot blower pressure.Controller 11 PIC-147 is Reverse.

� Fail safe action is close.

� Trends, indications and alarms shall beconÞgured in the DCS.

DEAEARATOR PRESSURE & LEVELCONTROL

Pressure transmitters 11-PT-105 measures thedeaerator pressure & fed to the 11-PIC-105 forDeaerator Pressure Controller as a PV . Theoutput of 11-PIC 105 acts on the deaeratorPressure Control Valve 11-PCV-105. Thecontroller shall have Reverse action. Thecontroller shall have PV tracking for manual toauto bumpless transfer.

� The action of the Deaerator Pressure Controllershall be reverse.

� Action of DA Pressure control valve 11-PCV-105 is air to open type.

� Fail safe action is air fail to close.

Deaerator pressure High & Low alarms aregenerated from 11-PIC 105 signal.

Level transmitter 11-LT-102A & 11-LT-102Bmeasures the deaerator level.The output of thesegiven to 11-LY-102 1002 block .The output of11-LY-102 fed to the 11-LIC-102 as the PV forDeaerator Level controller. The output of 11-LIC102 acts on the Deaerator Level control Valve11-LCV-102. The controller shall have directaction. The controller shall have PV tracking formanual to auto bumpless transfer.

� The action of the DA Level Controller shall bedirect.

� Action of DA Level control valve LCV-002 isair to close type.

� Fail safe action is open on air fail..

Deaerator Level High & Low alarms are generatedfrom LIC 102

Section B 37


Section C


♦ Section Overview♦ Operation Procedure♦ Pre-requisites to Be Attended Before Start up♦ Boiler Start Up♦ Boiler Shutdown♦ Paralleling WHRB To The Plant steam Mains♦ Cooling of Shutdown WHRB & Its Preservation♦ Do�s and Dont�s♦ WHRB Log Sheet♦ Emergency Procedures♦ Alarms and Interlocks♦ Troubleshooting Chart♦ Water Quality Recommendations♦ Safety In WHRB House

1 Section Overview

This section describes the start up, shut downprocedures of the WHRB. WHRB operation &safety are also described here.

2 Operation Procedure

(Please refer the P & I Diagram for Waste HeatRecovery Boiler Drg No.- D12-1WH-6203P for thevalve references described in this section)

3 Pre-requisites to Be AttendedBefore Start up

� All pre-commissioning activities like RefractoryDry Out, Alkali Boil Out, pressure test of thecomplete system, Safety Valve ßoating checkand steam blowing of pipe lines should havebeen completed prior to start up of boiler forcontinuous operation

� All instruments should be taken on line andchecked for proper functioning. Switch onpower supply to MCC and control panel.Ensure all the safety interlocks are in operationand functioning. Necessary personal protectionequipment and Þeld safety gear should be keptin place.

� Provide all manholes and hand-holes withproper gaskets. Use sealant for proper holdingof gaskets.

� Flush all piping like feed water piping, drainlines, CBD / EBD piping etc with water toensure no clogging in pipelines.

� Open isolation valves for level transmitters &level gauge for steam drum. Run the feedwater pump with minimum opening of ßow

control valve. Fill the system with fresh boilerfeed water up to common below normalwater level. Close the manual valve at pumpdischarge and stop the pump.

� Check system for any leaks or mal-functioningequipment.

� Reduce the water level by operating blow-downvalve and check the operation of level lowalarms from transmitter are functioningproperly. Also check readings on leveltransmitter and level gauges are matching.

� Keep water level 2 inches below the normaloperating level.

� Adjust valves for boiler operation according toVALVE SETTINGS.

� Ensure all retractable soot blowers are in restpositions.

� Check electrical and pneumatic motorisedoperation of valves and dampers

� Ensure ßow and pressure of instrument air andcooling water is as per requirement.

3.1 Feed Water Supply

Primarily before allowing the ßue gases to theWaste Heat Boiler, a thorough check should bemade of all feed water supply equipment to insurea continuous and adequate supply of treated andde-aerated feed water to the boiler. The feedwater quality should be maintained as speciÞedin the latest Thermax P Diagram. (Drg. No.D12-0WH-09484). Refer concerned chapter forrecommended water chemistry.

3.2 Valve Settings

Make an inspection of the unit noting the positionof all valves. All valves on blow-down lines,water wall panel drains, Instrument drainsshould be closed. Take level control loop forDe-aerator tank on auto mode and maintainNormal Operating Level in the tank. Line up theboiler feed water pump and takes the stand-bypump on auto-change over mode (if applicable).Keep all the respective manual valves in thefeed water piping in open position. Initially,feed water should be introduced to boiler by�MANUAL MODE� operation of the feed watercontrol valve FCV 137 or manually operating theglobe valve HFW-VL-124 on feed water controlvalve bypass. Keep economizer vent valvesHFW-VL-136,HFW-VG-135 on the outlet headerin fully opened position to remove all air pockets.Vent on the steam drum SD-VG-119,SD-VL-120should be opened fully during boiler water Þlling.It is also advisable to trace feed water piping from

Section C 38


supply to boiler insuring that proper valves areopened or closed as the case may be.

3.2.1See the following valves are closedpositively

� Feed water regulating valves are closed andare in manual control.

� All blow-down and drain valves on boiler andwater walls

� Soot blower steam supply valve� Main steam stop valve� Attemperator control and bypass valves� Drain valves for instruments.

3.2.2Open the following valves:

� All steam drum vents(SD-VG-119,SD-VL-120),Puppy headervent(HPS-VG- 101,HPS-VL-102)

� All instrument and control connection to theboiler

� Superheater header ventsHPS-VL-106/110,HPS-VG-105/109, drainsHPS-VG-107/108, MSS-VG-101/102, startupvent MV-301,PCV-154, and main steam linedrains MSS-VG-108/109.

3.3 Filling With Water

Fill the boiler to about 2 inches below normalwater level on the level gauge, thus allowingroom for expansion of water with heating andpressure rise. Only boiler quality feed watershould be used for Þlling. It is desirable to Þllthe boiler with de-aerated feed water. Fillingwith hot water is permissible provided wateris added slowly and ßow does not exceedcapacity of de-aerating heater. Strains set up inthe waste heat recovery boiler from hot waterÞlling are minor compared to strains inducedfrom heating cold water rapidly. When Þllingwith water, drum vent(SD-VG-119,SD-VL-120)should be opened to permit escape ofsteam or air. The super-heater header drainvalves(HPS-VG-107/108,MSS-VG-101/102) areall kept open for removal of condensate (i.e. soonafter taking the ßue gas in to the boiler). All therespective valves on the startup vent piping areto be kept open.

3.4 Heating Up

Once the boiler has been Þlled with water, the ßuegas may be taken into the boiler. The ßue gas

temperature and the steam drum pressure is tobe controlled as mentioned in the Start-up curveattached. Annexure � I.

1. Minimum 1/3rd of steam generation tobe vented to assist natural circulation ofboiler and to control superheated steamtemperature. At any point of time duringstartup the superheater steam temperatureshould not exceed the temperaturementionedin the curve. By Adjusting the Attemperatorwater ßow and ßue gas ßow this can beachieved.

Note

� CLOSE ALL THE SUPERHEATERDRAIN VALVES WHEN THEHEADERS ARE FREE OFCONDENSATE

� CLOSE DRUM VENTS(SD-VG-119,SD-VL-120) ASPRESSURE REACHES TO 3KG/CM2

� CLOSE PUPPY HEADERVENT Puppy headervent(HPS-VG-101,HPS-VL-102)AND SUPERHEATER VENTSHPS-VL-106/110,HPS-VG-105/109AS PRESSURE REACHES TO 5KG/CM2.

2. As the steam pressure reaches 60% ofoperating pressure open the bypass ofmain steam stop valve(MV-303) graduallyand allow heating up of steam pipingapproximately for 30-45 min. This will helpdraining of condensate through the steamtrap bypass line and attaining operatingtemperature of piping. After attaining therequired temperature & pressure graduallyopen the main steam stop valve MV-302and close the startup vent valve PCV-154,bypass of main steam stop valve MV-302.After achieving the above, opens the stopvalve fully. All steam traps should be linedup and the by pass valve to be closed andcheck periodically for proper removal ofcondensate..

3. During all the above steps, maintain normalwater level in the steam drum. Initially, thecontrols should be on manual mode onlyand once the steam supply to the processis started, change the controls in auto modeand monitor continuously.

Section C 39


4 Boiler Start Up

This chapter describes the boiler start up and shutdown procedures as applicable for the followingboiler conditions:

1. Start up of a cold boiler

2. Start up of a warm / Hot boiler

3. Boiler shut down

NOTE

� Procedures explained in this chapter applyfor start up of the boiler already commissioned.Commissioning a new boiler calls for severaladditional requirements.

� It is assumed that operators are fully familiar withthe design and construction features described inthe earlier section.

� It is assumed that Operators are trained inoperation of similar type of boilers and have beenlicensed to operate boilers by the State BoilerAuthority.

� Owner is encouraged to evolve standardoperating procedures (SOP) based on theframework and recommendations that areexplained in the subsections below. The SOPshave to be well understood by operating personnelfor safe and reliable operation.

4.1 Cold Start Up Procedure

1. In general, superheaters are located in areasof high temperatures and as a result, thedanger of oxidizing or burning the superheatertubes always exists. Thus, like it is importantto maintain the water in the boiler, it is equallyimportant to maintain steam ßow through asuperheater and at a rate sufÞcient to absorband carry away the heat surrounding thesuperheater. The rate of steam ßow mustcompensate for the rate of heat input to thesuperheater. It is not only true during periodsof normal operation but also during startupand shutdown periods. Bearing these inmind, the following procedure is described forcold start up.

2. Flue gas temperature at boiler inlet tobe kept below 400°C until the steamcirculation in the superheater is established.Prior to placing a superheater inservice, the superheater headers drainsHPS-VG-107/108, MSS-VG-101/102, ventsHPS-VL-106/110,HPS-VG-105/109 anddrum vents (SD-VG-119,SD-VL-120), Puppy

header vents (HPS-VG-101,HPS-VL-102)should be opened to clear all water,condensate and entrained air. These ventsand drains, should all remain open until thesteam pressure reaches about 4 to 5 Kg/cm2G and a deÞnite ßow of steam through thesuperheater have been noted. At this time,the steam drum vents should be closed.

3. It is necessary to leave the superheater drainand vent open until the unit is on line anda deÞnite steam ßow is obtained throughthe superheater tubes. It is essential thatsteam should ßow through the superheaterat all times when it is subjected to high gastemperature.

4. Please follow the pressure rising curve fordetermining the rate of increasing the steamdrum pressure.

5. Gradually reduce the water level in the drumduring warming up period to normal waterlevel by blowing down the boiler as requiredto maintain the water level in the gauge glass.This is to drain the water level swelling duringheating up.

6. While the boiler is heating up make frequentchecks of the boiler expansion movements. Incase of any abnormalities, stop ßue gas ßowand carry out remedial action.

7. Check the boiler water concentration andconstituents as frequently as required tomaintain proper boiler water concentration byblow down.

8. As the drum pressure increases,progressively throttle the finalsuperheater outlet header drain andstartup vent. Do not close startup ventcompletely until steam flow through themain steam line is established.

9. As the steam pressure reaches 60% ofoperating pressure open the bypass ofmain steam stop valve(MV-303) graduallyand allow heating up of steam pipingapproximately for 30-45 min. This will helpdraining of condensate through the steamtrap bypass line and attaining operatingtemperature of piping. After attaining therequired temperature & pressure graduallyopen the main steam stop valve MV-302and close the startup vent valve PCV-154,bypass of main steam stop valve MV-302.After achieving the above, opens the stopvalve fully. All steam traps should be lined upand the by pass valve to be closed and checkperiodically for proper removal of condensate.

Section C 40


10. During all the above steps, maintain normalwater level in the steam drum. Initially, thecontrols should be on manual mode onlyand once the steam supply to the processis started, change the controls in auto modeand monitor continuously.

Note

NOTE:IT IS ADVISED TO AVOIDFREQUENT STARTUP ANDSTOPPAGE, AS THIS WILL LEADTO THERMAL CYCLIC LOADINGOF THE BOILER AND PREMATUREFAILURES

Figure 2

Section C 41


4.2 Hot Startup Procedure

1. Restarting the boiler after banked conditionagain requires controlled ßue gas ßow rateso as to prevent the superheater fromoverheating. This procedure is applicablefor starting of boiler after a short stop. Theconditions should apply:

2. Drum pressure must be > or equal to 45Kg/cm2.

3. Drum water level should be at normal waterlevel.

4. The main steam stop valve MV 302 will be inclosed condition. Open the start up vent valvePCV 154 to minimum venting and monitorsuperheater outlet steam temperature (TT153).

5. Admit approximately 10% of the ßue gas fora period of 30 minutes. Keep a close watchon the superheater outlet steam temperature(TT-153). Adjust attemperator water ßow(TCV 153) and start-up vent valve(PCV 154)as required

6. Open SH drain valves (MSS-VG-108/109) &removes condensate and open bypass formain steam stop valve (MV-103)and warm upthe steam line leading to turbine.

7. Now gradually increase the ßue gas ßow andincrease the steam drum pressure (PT-145)as per the pressure rising curve. Adjust theßue gas quantity and / or start-up vent valve(PCV-154) opening as required.

8. As the steam pressure reaches operatingparameter, open main steam stop valve(MV-302) & charge steam to turbine.Gradually close the start up vent (PCV-154)and bypass for main steam stop valve(MV-303).

9. Take all the controls on auto mode and checkfor stable operation.

Note

IT IS ADVISED TO AVOIDFREQUENT STARTUP ANDSTOPPAGE, AS THIS WILL LEADTO THERMAL CYCLIC LOADINGOF THE BOILER AND PREMATUREFAILURES.

5 Boiler Shutdown

Boiler shut down can be of two types:

1. Planned Shutdown, where the operator getsadvance notice and adequate time to shutdown the boiler in an orderly manner.

2. Boiler Trip on interlock protection oremergency shutdown by the Operator.

If the shut down is only for few hours, it is notrecommended to cool the bed material.

If the shut down is for few days, it is recommendedto cool the bed material.

5.1 Normal Shutdown Procedure

The following procedure for normal shutdown isbased on the assumption that the unit is operatingat full load on automatic control and the unit shouldbe brought to zero pressure and cool the boilercompletely

1. Gradually reduce the load on the unit reducingthe ßue gas ßow rate in line with decreasingsteam ßow. Allow the pressure drop with thereduction in load to accelerate cooling. Steamtemperature control may be left on automaticuntil the point is reached where better controlcan be obtained on manual.

2. Open the start up vent (PCV-154) graduallyand close the main steam stop valve(MV-302).

3. Open the By pass duct damper (DI-004)and stop I. D fan. Close the boiler inlet ductisolation damper (DI-003) and damper at IDFan outlet (HV-179A/B).

4. Reduce the boiler pressure. As the boilerpressure drops below 5 Kg/cm2, open steamdrum vent (SD-VG-119, SD-VL-129).

5. Immediately after the boiler is off line, wideopen the superheater vents (HPS-VG-105/09,HPS-VL-106/10) and drains(HPS-VG-107/8,MSS-VG-101/2),PuppyHeader Vent (HPS-VG-101/2), main steamline drain (MSS-VG-108/9) .

6. After the boiler is completely depressurized,then the cooling process can be initiatedin order to permit entry into the unit formaintenance, proceed as follows : Purge theunit ,Cool the unit by opens all the manhole &Maintain water level at normal.

7. Stop chemical dosing pumps

8. During long shut down of the boiler, Feedwater pump can be shut down only afterstabilizing drum level.

9. If the boiler is to be emptied the boiler watertemperature should be reduced to at least70°C before draining.)

10. Open the manhole when the ßue gastemperature is below 50 Deg. C.

Section C 42


5.2 Emergency Shutdown Procedure

1. Open the By pass duct damper (DI-004)and close the damper at boiler inlet (DI-003)and ID fan outlet damper(HV-179A/B) andregulating damper DM-001.

2. Open the start up vent PCV-154 gradually andclose the main steam stop valve MV-302.

3. Follow pt. No. 4 to 10 of normal shut downprocedure

5.3 During Black - Out ProcedureCondition

� During the Black out condition

� Open the by pass duct damper DI-004 andclose the damper at boiler inlet (DI-003) & IDFan out let (HV-179A/B), regulating damper(DM-001).

� Ensure that ID fan inlet controlling damper is infail-safe position i.e., close condition.

� Close the MSSV (MV-302) and open thestartup vent (PCV-154) to minimum positionjust for protecting the superheater (ensureto avoid overshooting of main steam temp(TT-153).

� The BFP should start with in 3-min with thehelp of emergency power supply and manuallymaintain the water level in the steam drum.

� Emergency power supply has to be provided tothe MSSV, Startup vent, inlet hot gas damper,ID Fan discharge damper and by pass ductdamper. The steam drum pressure and thelevel has to be manually maintained.

� Once ßue gas temp at boiler inlet drops below400 deg C the boiler can be hot boxed up.

5.4 Operator Action Required DuringBoiler Cold Start up

� Ensuring permissible rate of heat input toWHRB during start up

� Operator can also check the local exhaust gasand temperature indications

� Monitor the water level in the drum (LY-142). Asthe temperature reaches about 90°C, a hugeswelling of water level in the drum takes place.The operator anticipates this and controls thelevel by opening the EBD valve (EBD-102).

� Initially, a careful assessment of water level inthe drum is made by checking the local levelgauges (LG-143/44).

� Observe the air vent on drum. Air gets expelledand steady steam starts coming out of the airvents

� Observe drum pressure (PT-145) at DCS asalso local pressure gauge PG-146

� When drum pressure shows 2kg/cm², drum airvents can be closed SD-VG-119, SD-VL-120

� When the steam pressure builds up to 2 kg/cm². super heater drain valves are to be closed(HPS-VG-107/8,MSS-VG-101/2)

� When the swelling phase of drum water level isover and the level shows a decreasing trend,the 25% feed control can be taken into serviceby opening isolating valves .it can be positionedas required manually to maintain drum level

� Ensure CBD, feed water and super heatedsteam samples are ßowing to the coolers andthe pH, conductivity meters are in operation.Verify pH and conductivity are within permissivevalues.

� Allow the WHRB steam pressure andtemperature to build up to rated temperatureand pressure by suitably adjusting ID fanspeed.

� When steady feeding is established throughthe feed control valve, the same can be takenon auto mode, by switching into automode.If sluggish, continue manual operation of forsome more time before trying again.

� � Monitor the steam drum water level(LT-142A/B).

� Monitor the parameters, which can cause aWHRB trip

6 Paralleling WHRB To The Plantsteam Mains

Paralleling WHRB to the steam mains of the plantis an important operation to be carefully donewithout affecting the temperature of steam in theplant. The pre requisites for this operation are:

� Building the steam pressure in WHRB to apressure (PT-156) slightly more than plantsteam pressure.

� With the build up of required steam pressureand temperature in WHRB, the main steamstop valve (MV-302) can be opened

� Initiate an open command for MSSV With theopening of valve , WHRB is ready for supplyof steam to the plant.

� Slowly Increase ID fan speed

Section C 43


� Reduce the opening of the start up ventvalve (PCV-154) to about 15%. This valvecan be completely closed later (onceboiler is connected to plant completely.) �Desuperheater TCV-153 can be taken inservice if SH II outlet temperature TT-153 isexceeding rated value.

� Observe steam temperatures after SHII TT-153� Observe the feed control station. When steamßow established FCV-137 can be taken in automode.

� Observe the feed control station. Whensteam ßow exceeds 25%, full load controlstation comes into service (based on operatorselection)

7 Cooling of Shutdown WHRB &Its Preservation

This chapter describes the methods of cooling ashut down WHRB and the steps to be taken topreserve the WHRB to minimize corrosion.

7.1 System Description

WHRB after shut down has to be cooled carefully.Permissible cooling rate of the WHRB is only halfthe permissible rate of heating. If the coolingrate is accelerated, thermal stresses develop inthe thick components such as the steam drum,Economiser, Evaporator, Super Heater headers,Attemperator etc.,

A WHRB is shut down either for keeping it inreserve as a stand by unit or for maintenanceand inspection. The purpose of the shut downdetermines the method of cooling to be adopted.

7.2 Natural Cooling

The WHRB after a shut down is allowed to coolslowly in a �boxed up condition�. The followingvalves are also closed.

� HP dosing to Drum HPC-VG-118� CBD from Drum CBD-104� Sample line to WHRB water sample cooler� Sample line to saturated steam sample cooler& SH steams sample coolers

The WHRB cools slowly, loosing its heat byradiation to the environment. Till the steam drumpressure drops to 2 kg/cm2 (g), permissiblewater level is maintained in the drum (+150mmto � 250mm) by intermittent feeding. Afterthe steam drum pressure falls below 2 kg/cm2(g) maintaining water level in the drum is notessential.

When the steam drum pressure is less than2 kg/cm2 (g), the access doors in the WHRBare kept open to create a natural draft throughthe WHRB to the chimney. WHRB cools to anaccessible level in about three-four days.

7.3 Forced Cooling

If the WHRB has to be made available forinspection or repair and the shut down time hasto be reduced to a minimum, forced cooling of theWHRB is done.

After the shut down of the WHRB, the HP dosing,CBD, IBD and sample cooler valves are closedas for natural cooling. Water level in the drum isalso maintained between permissible levels till thesteam drum pressure falls to 2kg/ cm2 (g).

For 8 hours after the shut down, the WHRB isallowed to cool naturally in the boxed up condition.After 8 hours, access doors on WHRB are openedto allow airßow through the WHRB to the stack.

The de-pressurization of steam in the WHRB isalso speeded up by controlled opening of the startup valve PCV-154.

However forced cooling is not done unlessabsolutely essential.

8 Do’s and Dont’s

DO’S

1. Maintain all instruments and interlocks in goodworking condition.

2. All equipment interlocks should always be inline

3. Maintain normal water level in steam drum4. Maintain water quality as per the

recommended limits. A table showing theDM water & drum water quality is included atthe end of this section

5. Pressure raising from cold start must be doneas per the cold start up curve

6. All the duct joints must be leak proof7. Use proper lubricant and maintain

the schedule as recommended by themanufacturers

8. Operate the WHRB within the recommendedoperation limits

9. WHRB, piping, ducts must be properlyinsulated

10. Servicing of equipments should be done asper the manufacturer�s schedule

11. Maintain proper operation log sheets regularly

Section C 44


12. Maintain the instrument air free from moistureand oily matters and the pressure asrecommended

13. Carry out regular cleaning of direct water levelgauge glasses of WHRB drum

14. Use proper valve gland packing to avoidleakage

15. Use proper gaskets for ßange joints16. Operate the blowdown valves as per

recommendation17. In case of power failure close the steam stop

valve18. If the water level goes up above the limits

operate the emergency blowdown valveimmediately and maintain the water level tonormal

19. Maintain the feedwater temperature ateconomizer inlet and ßue gas temperature ateconomizer outlet as recommended

20. Use genuine spares21. WHRB surroundings and equipments must be

properly illuminated

DONT’S

1. Don�t bypass any instruments and safetyinterlocks

2. Don�t use raw water as WHRB feedwater

3. Don�t operate the WHRB beyond theoperation limits

4. Don�t leave the furnace door open while theWHRB is in operation

5. Don�t mix up different lubricants

6. Don�t alter the equipment maintenanceschedule

7. Don�t leave the instrument control panelunattended

8. Don�t allow unauthorized persons to operatethe WHRB and associated equipments

9. If WHRB is running under combustion controlmanual mode, then while increasing loadair should be increased Þrst followed bygas. Ensure always-proper air to fuel ratiocorresponding to load.

Section C 45


9 WHRB Log Sheet

� It is suggested to record the WHRB parametersduring startup and normal operation. Observedabnormalities (if any) recorded can be usedfor analysis, troubleshooting and maintenancepurposes.

� Log sheet to be Þlled once in every hour by theoperating staff.

� Feed water, WHRB water qualities are also tobe noted once in four hours.

� Total gas consumption and steam productionof a day to be noted.

� Logbook should furnish the details about

� WHRB trips with reasons and time.

� WHRB running hours.

� WHRB shut down details (forced or planned,outage hours, jobs carried out, etc.,)

� Sample log sheet is enclosed.

SLNO PARAMETER UNIT Time

1 Turbine load MW

2 ID fan speed %

3 DRUM LEVEL MmWC

4 MAIN STEAM PRESSURE Bar G

5 MAIN STEAM TEP DEG C

6 STEAM FLOW TPH

7 FEED WATERFLOW TPH

8 ATTEMPERATOR I WATER FLOW TPH

9 STEAM FLOW TOTALISER MT

10 FEED WATER FLOW TOTALISER MT

11 ATTEMPERATOR I FLOW TOTALISER MT

12FEED WATER PRESSURE AT CONTROLSTATION INLET Bar G

13 FEED WATER TEMP.AT ECO . INLET DEG C

14 FEED WATER TEMP.AT ECO. OUTLET DEG C

15 STEAM TEP AT SH I INLET DEG C

16 STEAM TEP AT SH I OUT LET DEG C

17 STEAM TEP AT SH II INLET DEG C

18 STEAM TEP AT SH II OUT LET DEG C

19 FLUE GAS TEP. AT BOILER INLET DEG C

20 FLUE GAS TEMP. AT SH I INLET DEG C

21 FLUE GAS TEMP. AT EVAPORATOR INLET DEG C

22FLUE GAS TEMP. AFTER EVAPORATOR DEGC

23 FLUE GAS TEMP. AFTER ECO DEG C

24 FLUE GAS PRESSURE AT BOILER INLET mmWC

25 FLUE GAS PR. AFTER ECO mmWC

Section C 46


SLNO PARAMETER UNIT Time

FEED WATER ANALYSIS:

PH

CONDUCTIVITY

TDS

SILICA

HARDNESS

26

OXYGEN

DRUM WATER ANALYSIS:

PH

TDS

ALKALINITY AS CaCO3

SILICA

PHOSPHATE AS PO4

27

SULPHITE AS SO3

OPERATOR NAME: SIGNATURE: DATE:

Section C 47


10 Emergency Procedures

This Section Describes Causes of Emergency andAction on .

10.1 Low Water Level

10.1.1Causes

� Feed water control system failure.

� BFP failure 3

� Tube leak

10.1.2Action

Compare control room indication with gaugeglass level. If the water level falls out of sight dueto momentary failure of water supply system, dueto negligence of the operator, due to momentaryßuctuations that might occur with extraordinarychanges in load, appropriate action should betaken at once to trip the fuel. Any decision tocontinue to operate, even if only for a short timeat a reduced rating would have to be made bysomeone in authority who is thoroughly familiarwith the circumstances that led to the emergencyand positively certain that the water level can berestored immediately without damaging the boiler.In the absence of such a decision

� Stop the ID fan and open the stack cap

� Shut off steam ßow

Simultaneously, if feed water has becomeavailable and the operator is assured that nopressure part has been damaged

� Take the feed water control system into manualmode.

� Allow the water ßow to boiler gradually tonormal water level. (Do not hurry up whichmay lead to sudden quenching and tube leak)if pressure part damage is suspected

� Reduce the steam pressure gradually

� Open the drum air vent when the pressuredrops below 2 kg/cm2

� Cool the boiler so as to examine the extent ofdamage

� Drain the boiler after cooling

� If any tube rupture and bulging is observedrectify the same

� After the repairs conduct Hydrotest

� Determine the cause of low water

10.2 High Water Level

10.2.1Causes

CAUSES

� Feed water control malfunction

� Operator error

� Instrument air supply failure

� Foaming

10.2.2Action

� Take the drum level control loop into manualmode

� Reduce the water level immediately byoperating the emergency blow down tomaintain the drum level

� Reduce the steam discharge rate, if necessary

� Start the stand by compressor if required

10.3 Tube Failure

Operating the boiler with a known tube leak is notrecommended. Steam or water escaping froma small leak at pressure can cut other tubes byimpingement and set up a chain reaction of tubefailures. Large leaks can be dangerous. Theboiler water may be lost, boiler casing can getdamaged.

Small leaks can sometime be detected by the lossof water in the cycle or system. A loss of boilerwater chemicals or by the noise made by the leak.If a leak is suspected the boiler should be shutdown as soon as possible by following the normalshutdown procedure.

After the exact location of the leak or leaks islocated, the leaks may be repaired by replacingthe failed tube or by splicing in a new section oftube, conforming to relevant ASME code.

An investigation of the tube failure is veryimportant so that the condition causing the tubefailure can be eliminated and future failures canbe prevented. This investigation should includea careful visual inspection of the failed tube andin some cases a lab analysis.It is recommendedthat every effort be made to Þnd the cause of tubefailures before operation is resumed.

Section C 48


11 Alarms and Interlocks

ALARM LIST FOR WHRB BOILER

Sr. No. Tag No. Service Alarm Alarm value InterlockDetails

1. PAH 105 DeaeratorPressure HIGH 2 kg/cm.2 (g)

2. PAL 105 DeaeratorPressure LOW 1.5 kg/cm.2 (g)

3. LAH 102 Deaeratorlevel HIGH 60%

4. LAHH 102 Deaeratorlevel HIGH HIGH 75%

5. LAL 102 Deaeratorlevel LOW 40%

6. LALL 102 Deaeratorlevel LOW LOW 30% BFWP TRIP

7. LAH 142 Steam drumlevel High 100 mmWC

8. LAHH 142 Steam drumlevel HIGH HIGH 200 mmWC

9. LAL 142 Steam drumlevel Low -100mmWC

from NWL

Open Bypassduct damper10. LALL 142 Steam drum

level Very Low -250 mmWCfrom NWL

Trip ID Fan

11. ID 160A/B ID fan motor Trip

Close Boilerinlet damper &simultaneouslyopen by passduct damper.

12. TAL 153 Super Heatersteam temp. Low 480°C

13. TAH 153 Super Heatersteam temp. High 500°C

14. PAH 178ID Fandischarge FGpressure

HIGH 40 mmWC

15. PAL 178ID Fandischarge FGpressure

LOW 30 mmWC

16. PAL 160 FG pr. at boilerinlet Low -70 mmWC

17. PAH 160 FG pr. at boilerinlet High -10 mmWC

18. PAL 147 Soot blowerPressure Low 15 kg/cm.2 (g)

Section C 49


Sr. No. Tag No. Service Alarm Alarm value InterlockDetails

19. PAH 147 Soot blowerpressure High 23 kg/cm.2 (g)

20. DPH 118 DP acrossBFWP strainer High 0.1 kg/cm.2 (g)

21. DPHH 118 DP acrossBFWP strainer High high 0.15 kg/cm.2

(g) BFWP trip

Note

� Interlock is indicated in BOLD

� All the values mentioned are preliminary may undergo revision at time of commissioning ifrequired.

Section C 50


12 Troubleshooting Chart

Indication Probable Source Probable Cause Repair method &Preventive Measures

Tube Leak

Remove boiler fromservice at Þrstconvenient time.Hydrostatic test tobe done to locate leak.Repair by welding orsplicing as indicatedand as approved byinsurance or StateInspection. Determinecause of failure andcorrect it.

Unable to maintainboiler waterconcentration

Hideout

Slight leakage frompitting or cracking oftube .

Operation at normalloads should putchemical back insolution.

Sound of steamblowing in furnaceor seeing visible steamfrom the stack.

Tube leakSubstantial leakfrom tube/tubes.Over-heating

The same as above

Steam explosion infurnace followed byinability to maintainwater level.

Tube rupture

Failure of tube from lowwater, tube blockageor erosion of exteriormetal surface.

Remove boiler fromthe line immediately.Inspect or determinewhether tube splicingor wholesale tubereplacement isnecessary.

High conductivitySolids carry over in thesteam or high CO2 orNH3 in boiler water

High boiler waterconcentrations,excessive water levelßuctuation drum bafßeleakage or deposits onscrubbers

Check for bafße leaksin steam drum whenout of service, or boilerwater contamination.Check of degasiÞedsteam sample willindicate if CO2 or NH3is high

Excessive water levelßuctuation

Water load or controlconditions

High boilerconcentrations,extreme load swings,varying supplypressure or controlloop adjustment

Correct conditionleading to the problem

Section C 51



Bowed water wallgenerating tubes Overheating

Internal deposit or lowwater. Usually internaldeposits result in tubesbowing away from thefurnace & low water/starve results bowingtoward the furnace.

Severity of bowingwill determine extentof tube replacement.Internal scale will callfor internal cleaning. Iflow water is indicated athorough inspection fordrum damage and tubeseat leakage must bemade. Take steps toprevent recurrence orlow water condition

Tube blisters Localized overheating Internal deposit

Repair by retubingor welding in tubesection or by heatingand driving backblister dependingupon insurance carrieror State Inspector�sapproval. Cleaninternally by turbiningor acid cleaning.

Depth and extent ofpitting determinesneed and extent oftube replacement.Extensive drum pittingcan be welded but issubject to approval byeither the manufacturer& insurance carrier orState.

Internal pitting sharpedged and coveredwith barnacles in drumor tubes.

Corrosion Oxygen in Boiler water

Source of oxygenmust be located andeliminated

Internal loss of metalnot sharply deÞned andaccompanied by blackiron oxide

Overheating resultingin breakdown of waterinto H & O2

(Fe 3 O4 )

CorrosionCause is usually fromsludge letdown orpluggage.

Individual inspectionwill determine extent orreplacement, internalcleaning and correctionof water conditions arerequired

Section C 52



Extent of repair mustbe determined byindividual inspection.In emergency tubesout of high heat zonecan be plugged, beingsure they are cut tovent and to preventdifferential expansionwith adjacent tubes.

Proper externalcleaning can preventout of servicecorrosion.

External pitting Corrosion

From corrosive ashdeposit and moistureeither from dew pointor external source suchas leaking soot blowingtube.

Locate and eliminatesource of moisture. Ifdew point is from in-service corrosion, takesteps to raise metaltemperature

When accessible andwith insurance or Stateapproval, the crackscan be ground outand welded, otherwisesplice in section orreplace tube. Locate& eliminate source ofexpansion difÞcultyby inspection or hotto cold expansionmeasurements.

Tube cracking

Mechanical stressor a combination ofstress corrosion or tubevariation.

Interference withexpansion ordifferential expansionwith adjacent partsto give mechanicalstress or this stressplus corrosion attack.Vibration set up byturbulent gas ßowcharacteristics overtubes.

Using tube spacers canstop vibration.

External metal loss.Highly polished area Erosion

Mechanical abrasionfrom soot bloweraction.

Where accessible andwith insurance or Stateapproval pad weld orsplice in a tube section.Eliminate channelingof steam from sootblowers or use tubeshields

External metal loss.Oxidized Þre scalearea.

Overheating Prolonged or repeatedoverheating.

Extent of metalloss will determineextent of tube or tubesection replacement.Inspection or athermocoupleinstallation willdetermine cause ofoverheating

Section C 53


13 Water Quality Recommendations

AIM

This chapter describes the standards for the boilerfeed water and boiler water for corrosion and scalefree operation of the WHRB and for obtaining puresteam. Methods of control of boiler water are alsoexplained.

NOTE

This chapter must be read in conjunction with thefollowing vendor manuals.

� HP dosing system -

� Steam and Water analysis system

Suggested quality of boiler feed water (andattemperator water) fed to the WHRB is given infollowing table:

FEEDWATER

PARAMETER MAX. permissible value

pH at 25°C 8.5-9.5

Total hardness as CACO3 Nil

Chlorides as NACL Not traceable

Silica as SIO2 <0.02ppm

Total Iron as FE < 0.01 ppm

Copper as CU < 0.003ppm

Dissolved Oxygen < 0.007cc/lit

Sodium Sulphate Not traceable

Residual Hydrazine Traces

Organic matter Nil

Oil Nil

Total dissolved solids < 0.1 PPM

Conductivity at 25°C after cation exchanger andCO2 removal < 0.15 micro siemens per cm

Total CO2 Nil

Sodium + Potassium Not traceable

NOTE

� Alkaline levels of feed water minimizescorrosion of steel

� Chlorides, Silica, Iron, Copper, Organicmatter etc., present in the feed waterconcentrate further in Boiler water. Their higherconcentration calls for increased blow down(CBD) of boiler water causing loss of usefulheat

� Silica in boiler water vaporizes to SiO2 andescapes through steam

� Copper present in water, deposits on the innersurfaces of evaporator tubes and is harmful

� Chlorides in boiler water depress the pH leveland renders boiler water acidic and may causeaccelerated corrosion.

� Oxygen in boiler water promotes corrosion ofboiler tubes

� Oil present in feed water deposit on tubes andinterferes with heat transfer.

DRUM WATER

PARAMETER MAX permissible

Conductivity at 25°C after neutralization. < 50 micro siemens/cm

pH value at 25°C 9.5 to 10.2

Silica as SiO2 <1.2 mg/kg

Sodium Phosphate as PO4 2 to 6 mg/kg

�p� value < 0.1 m Val/kg

Section C 54


Minor permissible contaminants present in theWHRB feed water concentrate to high levels inboiler water due to continuous evaporation in thesteam drum - evaporator circuits. Two controlsare exercised on Boiler water to avoid corrosionof WHRB tubes and the drum water - washedsurfaces. The controls are:

� Tri-sodium phosphate dozing to convertthe hardness producing insoluble calcium,magnesium salts to soluble sodium salts whichcan be drained by CBD and to maintain thealkalinity levels of boiler water. The controlsare described below.

NOTE The drum water quality shouldbe continuously monitored and suitableadjustment in blowdown to be made tomaintain the drum water as per aboverecommendations.

14 Safety In WHRB House

� It is expected that BHATIA ENERGY & STEELLTD will evolve a comprehensive safetycode for all operations in the plant. A fewsuggestions are listed below which can formpart of the plant safety code for the WHRB.

� Hazards of High pressure, high temperaturesteam, water must be recognized by the WHRBoperation and maintenance staff.

� Fire extinguishing equipment should always beavailable around WHRB

� Do not attempt to open the observation portsin a working WHRB without observing propersafety procedure.

� For personal safety in handling hot valves,piping, oil guns etc. wear protective gloveswhile working around the WHRB.

� Never enter drums, ducts, furnace etc., untilthe WHRB has been shut down and cooled.

� When you need illumination for inspection,only use low voltage extension cords with lowvoltage bulbs with the cords properly earthed.The power supply be from an earth leak circuitbreaker (ELCB)

� Do not open or enter rotating equipment suchas fans, unless it has been isolated and taggedfrom power supply and the rotating equipmenthas come to a complete stop.

� Before removing manholes or ßanges in drumor pipeline, ensure that the drum/line has beenisolated and drained.

� Do not use toxic ßuids like CTC for cleaning ina conÞned space without adequate ventilation.

� Install and strictly follow a system of permitsand tagging for any maintenance or inspectionwork to be done by any person in the WHRBhouse.

� Operators trained in Fire Fighting, First AID,handling electric shocks etc may save livesand property in an Emergency.

Section C 55


Section D


♦ Section Overview♦ Recommended Maintenance Practices♦ Preventive Maintenance♦ Conditioned Based Maintenance♦ Boiler Annual Maintenance and Overhaul♦ Boiler Preservation Procedure♦ Tube Failures♦ Welding Procedure SpeciÞcations♦ General Principle Of Weld Repairs♦ Water Chemistry

1 Section Overview

This section describes the various maintenancepractices, overhauling, and preservationtechniques. Also discussed are failures andrepair techniques.

This section covers the following

� RECOMMENDED MAINTENANCEPRACTICES

� PREVENTIVE MAINTENANCE PROGRAM

� CONDITION BASED MAINTENANCE

� Maintenance check list for daily, weekly,Monthly and Annual inspection

� SHUTDOWN AND COOLING THE BOILER

� INSPECTION AFTER COOLING

� PRESSURE PART & EQUIPMENT CHECKS

� BOILER PRESERVATION

� TUBE THICKNESS SURVEY

� WELDING PROCEDURE SPECIFICATIONS

� TUBE FAILURE INVESTIGATION

� PLUGGING TUBES

� REPAIRED AND NOT PLUGGING TUBES

� REPLACEMENT OF SECTIONS OF TUBES

2 Recommended MaintenancePractices

Systematic maintenance is essential to keepthe boiler and its auxiliaries in good conditionand to obtain reliable operation of the boiler withhigh availability and plant load factor. Effectivemaintenance aims at timely inspection of partsto repair or replace defective components and toprevent their failure when the boiler is in service.

Maintenance can be classiÞed as -

� Preventive maintenance � mostly conditionbased

� Annual Boiler overhauls to clean and inspectpressure parts.

The shutdown period of the overhaul is alsoutilized to attend to systems and parts whichcannot be attended during short shutdowns orwhen the boiler is in operation

The vendor manuals of the fans, motors, controlvalves with their positioners and actuators,instruments and controls, power cylindersetc., prescribe certain minimum maintenancerequirements which are to be carried out in oneof the above two maintenance categories.

It is suggested to maintain a defect register in thecontrol room to register all the items, which needmaintenance.

3 Preventive Maintenance

The objective of the preventive maintenanceprogram is to obtain trouble free service from thecomponent till the next maintenance.

Vendor manuals for various equipments suggestinspection periods, checks to be done andrecommended spares. The true objective of themaintenance program can only be realized, if amaster plan of maintenance of all the componentsis prepared as per vendor instructions.

Full beneÞts of maintenance can be obtained onlyif proper parts are used. Mandatory spare partlist covers most of the spares required. It may befound that in the Þrst two years of operation dueto variations of site conditions, some additionalspares not included are also required. Action hasto be initiated to procure such spares.

Some equipment have 100% reserve standbyunits. (Feed water pumps etc.). Maintenance ofsuch equipments can be organized even whenthe boiler is in service, although some minimumrisk is involved. Equipment such as igniters,scanners have replacement spares which can beutilized when the working equipment are to bemaintained without affecting the boiler operation.The prepared master plan for maintenance shouldbe periodically reviewed during the Þrst threeyears of the boiler operation.

It may be found that due to varying site conditions,the frequencies and quantum of work scheduledas per vendor manuals are either too much or tooless. Based on site experience, the frequenciesand work schedules can be modiÞed. A

Section D 56


scientiÞc method of preparation of the preventivemaintenance schedules is to make them conditionbased. In condition based maintenance, theequipment and components of the plant areinspected daily, weekly monthly etc., as pera suggested schedule by the local operatorsand deteriorating conditions if any observed arereported. Suggested inspection program is givenin this section. Based on operator reports of suchinspection, maintenance works are planned forthe next available planned shut down. Mandatoryinspections prescribed by the vendors are alsotaken care of, irrespective of the equipmentcondition.

3.1 Preventive Maintenance Programfor Valve

A preventive maintenance program for valvesonce in two years can be done with one or moreof the following works:

� Dismantle the bonnet, clean the trim and valveseat, lapping them if necessary.

� Cleaning the valve stem and re-lubrication ofthe operating threads

� Renewing the bonnet joint, and assembling thetrim on the valve seat

� Renewing the gland packing

� Renewing the valve ßange joint, if necessary.

3.2 Preventive Maintenance Programfor Spares

It may be found that in the Þrst two years ofoperation due to variations of site conditions,some additional spares are also required. Actionhas to initiate to procure such spares.

The prepared master plan for maintenance shouldbe periodically reviewed during the Þrst threeyears of the boiler operation.

It may be found that due to varying site conditions,the frequencies and quantum of work scheduledas per vendor manuals are either too much or tooless. Based on site experience, the frequenciesand work schedules can be modiÞed

A scientiÞc method of preparation of thepreventive maintenance schedule is to makethem condition based.

In condition based maintenance, the equipmentand components of the plant are inspecteddaily, weekly, monthly etc. as per suggestedschedule by the local operators and thedeteriorating conditions if any observed arereported. Suggested inspection program is givenin this chapter. Based on operator reports of suchinspection, maintenance works are planned forthe next available planned shutdown. Mandatoryinspections prescribed by the vendors are alsotaken care of, irrespective of the equipmentcondition.

4 Conditioned Based Maintenance

The schedule of daily, weekly and monthlyinspections given in the following pages do notrequire a boiler shutdown and in fact can onlybe done when the boiler is in service. Threeand six monthly inspections are done utilizing anavailable planned shutdown approximately in thespeciÞed time period.

Objective of these inspections is to ensure that:

1. The components are in trouble free condition.

2. To carry out any minor repairs or adjustmentswhich can be done with the boiler in service.

3. To plan for repair of such items, which cannotbe attended when the boiler is in service,during the next available shutdown.

4. To collect a database to determine optimumservice life of the systems and componentsbefore maintenance if required.

The schedule can be expanded, curtailed ormodiÞed based on experience in the Þrst twoyears of operation.

4.1 Daily Checks

To be done once a day by the local operator duringhis walkdown checks. Such walkdown checks areto be encouraged to be done in each shift by thelocal operators. Only those operational checks,

Section D 57


which require maintenance work for correction,have been included.

EQUIPMENT CHECK WORK TO BE DONE

Local level gauges on steamdrum

� Check illumination is proper.

� Leaking valve glands.

� leaking ports

� Blurred level

� Replace fused bulbs.

� Isolate level gauge and tightenleaking glands.

� Replace leaking ports.

� Steam wash mica as suggestedby vendor (not to be donetoo frequently)

Comparison of levelsindicated by local level gaugewith that of remote levelindicators in the control room

Compare the levels after verifyingthere are no leaks from valves,glands etc. of the level gauge andindicators. Report discrepancies.

If there are serious discrepanciescalibration of the remote levelindicators has to be plannedimmediately.

Traces of water, oil spots onboiler ßoor, buck stay beams,boiler cladding etc.

Such spots are indicative of valveleaks, instrument tapping leaksetc., Trace the source of leak.

Maintenance to be plannedto eliminate the source eitherimmediately or during nextplanned shut down (depending onthe source and quantity of leak)and accessibility for maintenance.

Lubricating oil levels of Fans,& feed pumps bearings,dosing pump gear box etc.

Check adequacy of oil level. Top up if required (immediately)

If leakage through oil seals,gaskets drain plugs etc. arenoticed plan for maintenanceduring next planned shutdown.

Fans, BFW pumps dozingpumps

� Check bearing temperatures .

� Check for Vibration Levels

If higher than normal bearingtemperatures are noticed checkfor cause proper oil level, correctgrade and quality of oil or grease,abnormal sound or vibration.

If bearing temperatures are veryhigh, start the reserve equipment (if avl.) and plan for a maintenancechecks .

If vibrations are above thesatisfactory limits. Check formechanical looseness and startthe reserve equipment ( if avl.)and plan for a maintenance check.

Section D 58



Drum and super heatersafety valves.

Check for passing of safetyvalves (noise or wisp of steamthrough silencer)

� Hand pop the affected safetyvalve one or two times toclear any dirt sticking tothe valve seats

� Lightly tap on the stem ofthe safety valves.

� If these measures do notsucceed, if request for checkof the safety valve during nextplanned shutdown.

Purity of instrument air Check by visual observationthat the instrument air is oil andmoisture free.

(Oil and moisture content canalso be checked by laboratoryexamination as per standards)

Oil and moisture in the instrumentair is likely to clog the positionersof pneumatic controllers /solenoids and make theiroperation sluggish or unreliable.

Open drain valves of air receiversfor short time to drain condensateif any.

If these measures arenot successful, inform theMaintenance group.

Steam or water leakagesfrom valves and from ßangejoints

� Loose valve gland

� Loosened bolts of ßange jointand / or failed gasket.

� Tighten the gland nuts.If the leakage not gettingarrested, plan for maintenanceduring shut down.

� Tighten the bolts. If thegasket failed then plan for themaintenance during shut down.

Boiler cladding, air duct orßue gas duct.

Check for hot spots Hot spots may be due to leakageof ßue gas or hot air. Source ofleakage has to be located afterselective removal of insulation (tobe planned for the next plannedshutdown)

Section D 59


4.2 Daily Maintenance

Maintenance Check List During Operation

1. Check the correctness of water level in the control desk with direct level glass.

2. Check the level indicators for proper illumination.

3. Check for unusual noises for steam / water leakage.

4. Check for unusual noises for from pumps.

5. Check for vibration in rotary equipments.

6. Check for unusual traces of water on ßoor, buck stays or casings

7. Check for valve & gland leakages.

8. Check for air / gas leakages from ducts and ßue.

9. Check for hot spots, bulging etc. on casings, ducts etc.

10. Check the positions of dampers and cleanliness

11. Check for safety valve steam leakages.

12. Check the bearings for lubrication and cooling water systems.

13. Check all alarm annunciation with respect to set points.

14. Check for water, oil along with instrument air

15. Check the Þeld instruments for its proper indications.

16. Check the stack for any unusual smoke conditions.

4.3 Monthly Checks

Fans, Dosing pumps, With the vibration analyser recordvibration, sound levels andmeasure bearing temperature Notethe pressure, ßow of air, suctiondamper opening, (Capacity of theFD Fan) pressure (seal air blowers,HP dosing pump)

By monthly recording of data,establish a data base for decidingthe overhaul time of the equipment.An overhaul once in two or threeyears may be adequate. Databasewill help in deciding the time frame.Sharp increase in vibration levelsbearing temperatures or soundlevels may call of early schedulingof overhauls.

BFW pumps Check for coupling alignmentbetween motor and pump. Checkthe impeller is not rubbing withpump body. Check operation ofNRV at pump discharge.

By monthly recording of data,establish a database for decidingthe overhaul time of the equipment.An overhaul once in two or threeyears may be adequate. Databasewill help in deciding the time frame.Sharp increase in vibration levelsbearing temperatures or soundlevels may call of early schedulingof overhauls.

Safety valve operation Increase the boiler pressure andcheck the operation of valves.

If necessary do the adjustments.

Feed water tank /internals

Deposits of foreign particles Clean with normal water

Section D 60


Dosing system Cleanliness of dosing tank,operation of pressure relief valve,lubrication oil level in pump.

Clean dosing tank with normalwater, Adjust relief valve ,if requiredFill lubrication oil , if required

D P Manometer Choking of impulse tubes Liquidlevel in manometer

Clean impulse tube with air Keepliquid level at zero

Level switch for steamdrum water level very low

Close the steam out let valve andgas by pass damper. Open blowdown valve and check for levelswitch very low alarm.

If switch or alarm is not working, dothe rectiÞcation work.

4.4 Checks Every Six Months

During a planned shut down of the boiler, thefollowing checks can be done.


Boiler safety interlocks,start permissive, boiler tripprotection.

Coinciding with a plannedshut down of boiler, carryout the checks to identifymalfunctioning or sluggishpressure, temperature switches,solenoid operated valves,positioners, proximity switches,actuators etc.,

Plan for maintenance orre-calibration of defective items ifany noticed, during the shut downperiod.

4.5 Checks Every Year

(See also jobs listed under Boiler overhaul)


Pressure temperature, Flowlevel, differential pressurecontrollers

Utilizing the boiler annual shutdown for overhaul, recalibrate allpressure, temperature, ßow, leveland d/p controllers as per vendormanuals

Carry out any maintenancereplacement or adjustmentneeded to secure initial calibrationvalues as per commissioningrecords

Pressure gauges,temperature gauges,Pressure/temperatureSwitches

Recalibrate, Verify functioning ofpressure/temperature switchesas per design

Repairs or adjustments asnecessary

Positioners, actuators Verify functioning of positionersand actuators by feedingcurrent inputs to positioners andmeasuring the air pressure outputof the positioners and openingclosing of actuators

Repairs or adjustments asnecessary as per vendor manualsto obtain performance as percommissioning records. Verifyfunctioning of proximity switcheswhere provided. Clean Þlters ofair regulators. Check functioningof air regulators. Verify tightnessof air connections.

Section D 61


4.6 Annual Maintenance Check Sheet

COMPONENT NAME INSPECTION REQD FOR

Drums (water side ) � Corrosion

� Scale / deposits

� Pitting

� Metal reduction

� Manhole seat

� Process / instrument tappings

� Internal cleanliness

Feed water pipe in steam drum. � Plugging

� Tightness

� Holes orientation

� Corrosion

� Piping

Chemical dosing � Plugging

Pipe in steam drum � Tightness

� Holes orientation

� Corrosion / Pitting

Continuous blow down � Plugging

Pipe in steam Drum � Tightness

� Hole orientation

� Corrosion / pitting

Furnace tubes

(water side)

� Corrosion

� Scale

� Pitting

� Metal reduction

Furnace tubes

(gas side)

� Corrosion

� Build up

� Blisters

� Sagging

� Over heating

� Fly ash erosion

� Sealing

� Supports

� Cracks

� Expansion clearance

Section D 62



� Steam impingement

� Refractory status

� Insulation

� Erosion

Inbed evaporator coils

� Þre side

� Erosion

� Corrosion

� Build up

� Blisters

� Sagging

� Over heating

� Sealing

� Cracks



Super heater if provided.

(steam side)

� Corrosion

� Erosion

� Scale

� Pitting

� Metal reduction

� Flare cracking

� Deposits

Super heaters if provided.

(gas side)

� Corrosion

� Build up

� Sagging

� Over heating

� Fly ash erosion

� Sealing

� Supports

� Cracks

� Exp clearance



� Insulation

Economiser

(water side)

� Corrosion

� Scale

� Pitting

Section D 63



Economiser

(gas side)

� Corrosion

� Build up

� Blisters

� Sagging

� Over heating

� Fly ash erosion

� Sealing

� Supports

� Cracks



� Tightness of access

� Doors

Refractory � Looseness

� Missing pieces

� Erosion

� Sealing

� burner throat

� Refractory

� Flame impingement on refractory

� Refractory holding arrangements.

� Bafße tile status

� Corrosion

� Erosion

� Leakages

� Clearance between

� Rotor and casing

� Damper operating

� Mechanisms

� Bearings conditions

� Bearings clearances

� Lubrication argt.

� Cooling water argt.

� Fly ash deposits

� Shaft seals conditions

� Coupling alignment

Section D 64



Dampers � Blades rigidity

� Open/ close positions

� Expansion clearance condition of blades

� Erosion of blades

� Bearing freeness

� Lubrications

� Damper linkages

� Interlock mechanisms.

Convection pass � Erosion and material accumulation.

� Signs of gas channeling.

� Water walls for erosion patterns.

� Economiser support beams for erosion.

� Lower water wall headers for erosion / cracks.

� Seal at economiser and superheaterpiping penetration.

� All penetration for erosion.

� Superheater supports Furnace rear wall

� Riser roof

� For penetrations

� Sealing and cracks.

� Walls for erosion at the top of the tube/ refractory interface.

� Roof refractory for erosion or damage.

� Erosion coupons and pins for theRefractory thinning.

� Refractory on furnace rear wall outlet headerfor erosion or damage.

� Thermocouples and pressure taps forerosion / corrosion.

� Pressure taps for plugs

� All penetration for sealing and erosion.

� All penetration and plates for warpage or damage.

Casing � Bent

� Bulging

� Gas leakages

� Access door tightness

� Corrosion

� Erosion

Section D 65



Water level gauges � Cleanliness

� Leaks

� Visibility

� Illumination

� Reßectors

� Mirrors

� Gauge cocks status


� Internal deposits

� Insulation

� High/low water alarms/tripping

Valves � Erosion

� Corrosion

� Leakages

� Spindle movement

� Handle rigidity

� Drive mechanisms

� Lubrications

Safety valves � Valve nozzle conditions

� Disc seat conditions

� Corrosion of internals

� Pitting

� Cracks

� Valve spring status

� Spring stiffness

� Corrosion of spring

Silencer status � Spring stiffness

� Drain line status

� Drain line rigidity

� Discharge pipe rigidity

� Expansion clearances

� Valve settings

Section D 66



Remote level gauges � Cleanliness

� Leaks

� Visibility

� Illumination

� Gauge cocks status

� Internal deposits

� Insulation

� Liquid status (if any)

Dosing pumps As per manuals

Power cylinders As per manuals

5 Boiler Annual Maintenance andOverhaul

In addition to the check and inspections listedunder preventive maintenance, the boiler requiresan annual shut down of about 10 to 15 daysfor cleaning, inspection ad overhaul of boilerpressure parts. The shut down period is restrictedto a minimum by deploying adequate resources.If required, Field Engineering department ofThermax Ltd. can assist the customer in carryingout the boiler overhaul.

The annual shutdown is utilized for cleaning andinspection of the pressure parts and to collectdata on the wear pattern of boiler, superheaterand economizer pressure parts. The shutdownopportunity is also utilized for overhaul of safetyvalves, regulating and isolating valves andcomponents, which can not be attended when theboiler is in service. (The valve overhauls neednot be done every year).

5.1 Planning Before Overhaul

1. Prepare a list of jobs to be done during theoverhaul based on earlier inspection reportsand the jobs listed below.

2. Ensure availability of spares required for theproposed jobs.

3. Ensure tools, tackles, scaffolding materialsrequired for the job.

4. Ensure availability of manpower requiredfor the job (Own sources, contract labouretc) services of Thermax Ltd. is alsoavailable for carrying out annual overhaulsand inspections.

5.2 Shutdown and Cooling the Boiler

1. Shutdown the boiler in a planned manner.2. Don�t force cool the boiler.

3. Open all access and inspection doors.

5.3 Inspection after Cooling

1. Carry out a preliminary inspection aftercooling to check cleanliness and sign ofdeposition on water wall panels and needsany cleaning.

5.4 Drum Inspection

1. Open the access doors at either side of thedrum.

2. Allow the drum to ventilate for about 8 hours.If necessary a fan cooler can be Þtted overtemporary stand to force air through the drum.

3. From the time the drum manholes are openedtill they are closed after inspection, thearea around the drum must be cordoned torestrict entry only to speciÞcally authorizedpersonnel.

4. The names of persons who are entering thedrum for inspection, along with tools theycarry must be entered in a register. Personscoming out of the drum after inspectionshould be asked to account for the materialthey carried into the drum. This precautionis to prevent accidental dropping of foreignmaterial through the water wall tubes, whichmay block water circulation through them andcan cause tube failures.

5. Carry out a preliminary inspection of the drumto check for deposits on the water side of thedrum.

Section D 67


6. Using nylon brushes, the deposits (which arenormally soft) are cleaned, collected on traysand disposed off outside the drum. Washingdown the deposits to the boiler tubes is notrecommended.

7. In case of excessive deposits, the chemist isasked to analyze the nature of the deposits.Incase of excessive deposits, a reviewof phosphate concentrations (higher than10ppm) and boiler water quality control ( highconductivity ?) may be made to reduce thedeposit in the next year of operation.

After cleaning the following examinations can bemade.

1. Examine the boiler drum metal for scale,pitting, corrosion and metal wastage. (Drumthickness is measured at a few selected spotsusing ultrasonic instruments and comparedto design thickness).

2. Inspect fastenings of the bafßes, cyclones,and demisters to see that they are intact,without corrosion pitting or holes. Eroded orcorroded drum internals can be patched bywelding. No welding however is permitted onthe drum metal. The cyclones and demisterscan be examined in position. They need notbe dismantled. Reasonable water tightnessof the bafßes and cyclones are to be ensured.

3. Examine that feed water pipe is intact withßange connections tight and discharge exitcorrectly oriented.

4. Examine that the continuous blow down pipeand dosing pipes is not plugged or corrodedtheir supports are normal, their holes havebeen correctly oriented.

5. Examine that there are no cracks in the stubwelding s of the drum.

After the inspection, clean the manhole seatsand provide new gaskets. Sometimes the boilerinspector may like to inspect the steam drum.After this inspection and after verifying that allmen and material have been removed from thedrum, close the manholes and bolt them tight.

5.5 Inspection of Screen, Primary& Secondary Superheaters,Evaporators I/II & Economiser

Check the above mentioned sections for any

1. Suspicion of abnormalities. If yes, consultM/s THERMAX LTD. or a metallurgist fornecessary advice

2. Evidence of pitting / erosion / corrosion ontube outer surfaces (exposed to the ßue gaspath)

3. Evidence of overheating (bulging of tubes,blue color of tubes, blisters, disturbed verticalalignment of panels)

5.6 Expansion Joints

Examine the expansion joints. Eroded / corrodedparts can be patched by welding. When severeerosion is noticed (after several years of service)the expansion joints are to be replaced. Collapseor stretching of the expansion joints is usuallydue to forces exerted by the connecting ducts.Readjustment of duct supports will solve theproblem and will assist the expansion joints toregain their original dimensions.

5.7 Insulation and Cladding

1. Verify insulation as per drawings and correctwherever necessary.

2. Inspect cladding for damages due pitting,hotspots, dislocation etc. Repaired asnecessary.

5.8 Other Equipment

Overhaul of fans, pumps, fuel feeders, controlvalves, actuators etc., is scheduled as per vendorinstructions and condition monitoring describedunder preventive maintenance

5.9 Feed & Boiler Water Conditioning

1. INTRODUCTION

The successful use of boiler is dependent onproper water conditioning and treatment. Thequality of water must have accurate for troublefree operation of boiler.

The water as available to industry is not suitablefor boiler use. A complete pre-treatment andinternal chemical treatment is necessary to makeraw water suitable for boiler feed.

The objective of the water treatment is:

� Eliminate scaling - deposition in boiler whichcause tube over heating leading to accidents.

� Control corrosion of boiler system, which causefailure of boiler tubes, leading to unscheduledshutdowns.

Section D 68


� Reduce carry over of water with steam, which isthe cause of deposition on super heater/turbineblades, leading to the expensive failures.

� To maintain peak boiler efÞciency by keepingcomplete boiler water system clean.

In order to meet above objectives, it is necessaryto maintain certain chemical conditions in boiler,condense and feed water systems. A brief reviewof important factors is given in this section to assistthose taking charges of new boiler equipment. It isnot possible to cover the subject fully, there fore, itis recommended that the care and control of waterquality be entrusted to water treatment specialist.

2. NEED FOR WATER TREATMENT

A. CORROSSIVE CONTROL

Water is corrosive to boiler metal. Typicallycorrosion due to water will reduce thickness oftube @ 1 mm/year. Thus the life and safety ofboiler entirely depends on the rate of corrosionof boiler metal. In order to protect boiler fromcorrosion, pre-treatment is done to removeexcessive corrosion ions like chloride, sulphateetc. However, further chemical conditioning isrequired to protect boiler and auxiliary systemsfrom corrosion.

Tri sodium phosphate, caustic, ammonia andamines are used as corrosion inhibitors. Thesechemicals form a protective Þlm over metalsurface and reduce corrosion. It is necessaryto maintain prescribed concentration of thesechemicals in boiler water systems continuously.

B. OXYGEN CORROSION INHIBITOR:

Oxygen is present in dissolved form in water.At high temperature, oxygen reacts with metalto cause pitting corrosion. Thus prevention ofoxygen lead to pin holes in economizer, steamdrums and steam tubes.

Most of the oxygen is removed externally bydeaerator and preheating of feed water. However,traces of residual oxygen must be removed bychemical conditioning.

Sodium sulÞte, hydrazine and amines arerecommended for oxygen removal. Thesechemicals react with residual oxygen makingit inactive and protect metal against pittingcorrosion. Catalyzed oxygen scavengers areused for quick reaction.

C. SCALE / DEPOSIT CONTROL:

Raw water contains dissolved solids, hardnesssalts and suspended matters.

External treatment is used to remove suchimpurities.

� ClariÞcation - To remove suspended matters.

� Filtration - To remove residual turbidity

� Softening - To remove hardness salts

Dealkaliser - To remove hardness salts andexcessive alkalinity

� Demineralization - To remove residual saltsand silica

� Mixed bed - To remove residual salts and silicafrom DM water.

A combination of above equipments are used toremove undesirable impurities in raw water.

SCALE CONTROL

Hardness salts in feed water cause formation inboiler. Under temperature and pressure inside theboiler and due to concentration, hardness saltsprecipitate in tubes as calcium carbonate, calciumsulphate and Ca/Mg silicate scales.

External treatment like softening,demineralization or de-alkalisation removes mostof the hardness salts from boiler feed water.However, malfunctioning of this equipment,occasional bypassing of the softener/DM plant orcontamination of condensate or feed water withraw water often led to ingress of hardness in theboiler.

All hardness salt precipitate inside boiler leadingto hard scale formation on tubes. Such scalehas lower conductivity causing increase in metaltemperature, leading to bursting of tubes inextreme conditions.

Therefore, inspire of elaborate external treatment,internal chemical conditioning is alwaysrecommended as additional safety. Followingchemical methods are used for internal treatment.

PHOSPHATE CONDITIONING

Trisodium phosphate is commonly used.Hardness salts react with trisodium phosphateto form calcium phosphate precipitate. Thisprecipitate above pH of 9.5 colloidal in natureand therefore do not allow for form hard scaleof carbonate and silicates. The precipitatedhardness salts are then removed through blowdown as sludge and boiler tubes are kept scalefree.

Trisodium phosphate, apart from actingas hardness conditioning agent, also is a

Section D 69


good corrosion inhibitor. The recommendedconcentration in boiler water is given in Table -1

Note 1 : TSP will act as hardness conditioner,only when boiler pH is above 9.5 . Below 9.5pH TSP may cause hard scale formation of Ca3(PO)2. Therefore, coordinated or congruentphosphate treatment is recommended. The watertreatment experts can advise you right treatmentafter studying your water quality and operationconditions.

Thermax Chemicals can provide services forarriving at right chemical treatment for your boiler.

Chelant- Polymer treatment:

Hardness scales do not precipitate in presence ofchelant like NTA/EDTA The chelant treatment isrecommended when hardness ingress in boiler isexperienced regularly.

Excessive chelant dosing causecorrosion of boilerHence balanced chelant program asrecommended by experts should beused.

Organic polymer conditioners are used toprevent hardness scales. Such organic polymerdisperse scale forming compounds like CaCO3& Ca(PO4)2 in colloidal form facilitating theirremoval through blow down. Polymer andcopolymer of acrylic, methacrylic, styrene maleicacrylics are commonly used. Most of the polymersare proprietary in nature and therefore dosage isbest recommended by manufacturer.

D. FOULING CONTROL

Suspended matter, oil/grease /oxygen & ironsalts commonly cause fouling inside the boiler.Most of the suspended matter and iron salts areremoved by external treatment. However due tomfg. of these equipment, contamination throughcondensate and concentration in boiler causefouling of boiler tubes.

Similar to hardness scales, such foulants arepoor conductor of heat. Thus fouling causesoverheating of tubes.

Fouling can best be avoided bymaintaining qualityof feed water as per norms. In case of upsetsor occasional contamination, polymeric disersenthelp to prevent fouling due to turbidity and organicmatter. Iron is picked up mostly in condensatesystem due to corrosion of condensate line. Insuch case, condensate corrosion inhibitor like

ammonia cyclohexylamine and Þlming amine isrecommended.

E. TURBINE / SUPERHEATER DEPOSITIONCONTROL:

The solids in boiler feed water get concentratedin boiler. The concentration of solids in boiler isdecided blowdown and feed water quality. Thecarryover of boiler water with steam depends on;

Mechanical Factors:

� Boiler load - Higher the load, lower is the steampurity

� Water level in boiler - Higher the water level indrum, lower is steam purity.

� Load Variation - Sudden increase in loadreduce steam purity for short time.

� Separation efÞciency - Higher efÞciency, betteris steam purity.

Chemical Factors:

� TDS - Higher TDS in boiler, lower is steampurity.

� Total Alkalinity - Higher alkalinity as % of TDSlower is steam purity

� Organics - Higher the organic contamination,lower is steam purity.

� Foaming - Higher the foaming character ofwater, Lower is steam purity.

The water carried over with steam due toabove reasons is exactly similar in quality toblow-down or boiler water. In superheater or inturbines, water evaporates, leaving dissolved andsuspended matter as scales or deposits.

Thus severity of scaling and fouling of superheaterand turbine depends on boiler water quality andsteam purity.

Maintaining boiler water quality as per norms andmaximum steam purity is the only way to preventdeposition due to carryover of water with steam.Antifoam agents help to some extend to improvesteam purity in case of excessive in boiler.

F. SILICA DEPOSIT CONTROL:

Silica is volatile under high temperatureand pressure inside boiler. In turbines, theevaporated silica precipitates during pressureand temperature reduction and form hard scales.

Maximum allowable concentration of silicadepends on water analysis. Expert�s best decidethe maximum permissible concentration afterstriding the operating parameters.

Section D 70


G. CONDENSATE CORROSION CONTROL:

The carbon dioxide is present in boiler feed waterin dissolved and combined from as carbonate.Under boiler pressure and temperature it isliberated and carried over with steam as CO2gas. This gas re dissolves in steam condensateto form carbonic acid.

CO2 + H2O = H2CO3

H. MAINTENANCE OF PEAK EFFICIENCY:

Corrosion, scaling, fouling carryover andcondensate corrosion can cause unscheduledshutdown, accidents and deterioration of systemefÞciency.Therefore for trouble free operationand maintenance peak operation efÞciency,a combination of various internal chemicaltreatments is essential along with a good controlover boiler water quality.

Maintaining boiler water quality by usingcommodity chemicals likes TSP, Hydrazine, andSodium sulÞte. However, it is recommendedthat the care and control of water chemistry beentrusted to specialist.

6 Boiler Preservation Procedure

INTRODUCTION

Both the gas and waterside of a boiler should beprotected against corrosion during out of serviceperiods. It is known that many of the corrosionproblems of boiler and auxiliary equipment havetheir inception during storage. Rusting of tubesurfaces, as indicated by the formation of the redhematite (Fe2O3), not only cause a roughenedtube surface but also results in attack of parentmetal.

The advantages of efÞcient feedwater and boilerwater treatment during operation may be lost ifthe same diligence is not applied to protect heat.Transfer surfaces during idle periods. Protectionfrom corrosion during storage becomes vitallyimportant considering the number of times duringthe life of a boiler when it and its auxiliaryequipment are idle.

To minimize the possibility of corrosion, boiler tobe placed into storage must be carefully preparedfor the idle period and closely watched duringthe outage. There are two methods availablefor storing the unit dry storage and wet storage.Although the wet storage procedures is preferredsuch factors as availability of good quality water,ambient weather conditions, length of storageperiod, auxiliary supply of heat, etc may dictatethat the dry storage procedure is more practical.

6.1 Definition of Water Quality

Some cleaning procedures, hydrostatic testingand storage require water of higher qualitythan others. For the purpose of economy andconvenience the lowest water quality consistentwith requirements is speciÞed in these variousprocedures. The terms that identify the differentwater qualities along with their deÞnitions are listbelow: Station service water - Water normallyused for drinking, Þre protection, etc.

Softened water - Filtered, sodium zeolite softenedwater with total hardness less than 1 ppm.

Two- bed demineralised water - Water thenhas been passed through cation and anion ionexchanges in series.

Mixed bed demineralised water - Water that hasbeen passed through a mixed bed demineraliser.Water from an evaporator is considered to be ofequal quality.

Treated demineralised water - Mixed beddemineralised water that has 200 ppm ofhydrazine and enough ammonia added to giveÞnal concentration of 10 ppm (or a pH of 10.0).In this procedure, condensate is considered to betreated demineralised water.

6.2 Dry Storage Preservation

When it is known that a boiler is to be idle fora considerable length of time and that a briefperiod will be allowed for preparation to return it toservice, the dry storage method is recommended.In this method the unit is emptied, thoroughlycleaned internally and externally dried, and thenclosed up tight to exclude both moisture andair. Trays of lime, silica gel, or other moistureabsorbent may be placed in the drums to draw offthe moisture in the air trapped by the closing upof the boiler.

The following general procedure is recommendedwhen placing a unit into dry storage.

1. Fire the boiler according to the normalstart-up procedure and establish upto3.5-kg/cm2G-drum pressure. Stop Þring.Secure the boiler and when the pressuredecays to 1.3 kg/cm2G, immediately drainthe boiler and headers under air. As soonas possible, open the drums to allow air tocirculate for drying of all internal surfaces.

This step is included for a unit that has been inservice and is to be placed into storage. For aunit that has never been in service, start withStep 2.

Section D 71


2. If the unit is full of water and cold, drain theunit under air. All non-drainable boiler tubesshould be blown with compressed air. If anexternal source of heat is available such asa steam coil air heater, portable heaters, etc.,operate these heaters to assist in drying theinternal boiler surfaces.

Install trays (of non-porous constructionand capable of passing through the drummanhole) containing the moisture absorbent(silica gel is preferred) into the drums. Insertthe trays into the drum being certain thatnone of the absorbent comes into contactwith the metal surface of the drum. Toinsure against an overßow of corrosive liquidafter the moisture has been absorbed, thetrays should not be more than ½ full of dryabsorbent. The amount of absorbent canvary but the recommended minimum is oneKg of absorbent per 1000 Kg per hour steamßow capacity of the unit.

3. Open the isolation valve for nitrogenconnection, on the steam drum, close allother vents and drains and pressurize theboiler to 0.3 to 0.6 kg/cm2G with nitrogen.The amount of nitrogen required will varyaccording to the volume of the unit.

4. With the boiler pressurized, alternately openall boiler drains to purge air from the unit untilpressure decays to zero. It may be necessaryto repeat this process several times to reducethe amount of oxygen left in the unit to aminimum.

The unit should now be stored under 0.3 to0.6-kg/cm2G nitrogen pressure maintainedat the steam drum. To maintain the nitrogenpressure, all connections and valves shouldbe blanked or tightly closed. Check gaspressure daily to ensure protection.

We would recommend that periodicinspection of the unit be performed every 3months to assure that no corrosive action istaking place and to replenish the absorbentas required. Since air will enter the unit duringthis inspection, it will be necessary to repeatSteps 3 & 4 to expel the air.

The unit should be properly taggedand the appropriate warning signsattached noting that the boiler isstored under nitrogen pressure andthat complete exhaustion of thenitrogen must occur before anyoneenters the drum. Before enteringdrums test to prove that the oxygenconcentration is at least 19.5%.

The above procedure is intended to includethe economizer.

6.3 Wet Storage Preservation

The advantage of employing the wet storageprocedure is that the unit is stored completelywet with the recommended levels of chemicalsto eliminate a wet-dry interface where possiblecorrosion can occur. It is suggested that volatilechemicals be used to avoid increasing the levelof dissolved solids in the water to be used forstorage.

In preparing a unit for wet storage, the followingprocedure is recommended.

1. The unit should be Þlled with deaerated,Demineralised water treated with 200 ppmhydrazine (N2H4) for oxygen removal andsufÞcient ammonia (NH3) in order to attaina pH of 10 (for demineralised water, this willrequire approximately 10 ppm ammonia).

2. We strongly recommend pre-mixing of thechemicals with the water to insure a uniformmixture entering the boiler. This can beaccomplished by the blend-Þll method. Theblend-Þll method consists of blending thechemicals with the demineralised water at acontinuous rate such that a uniform mixtureis entering the boiler. Simply introducing thechemicals through the drum after establishingwater level will not insure adequate dispersionof chemicals to all internal surfaces, unlesssufÞcient heat is delivered to the furnace (i.e.Þring the boiler) to induce natural circulationthroughout the boiler.

3. Fill the unit with the treated demineralisedwater to the normal centerline of the steamdrum. Stop Þlling further.

4. Back-Þll the with treated Demineralisedwater until a rise in steam drum level isnoted. Continue Þlling until water exitsfrom the steam drum vents. After Þlling,

Section D 72


all connections should be blanked or tightlyclosed.

5. A source of low-pressure nitrogen should beconnected at the steam drum to maintain 0.3to 0.6 Bar G to prevent air from entering theunit during the storage period.

The unit should be properly taggedand the appropriate warning signsattached noting that the boiler isstored under nitrogen pressure andthat complete exhaustion of thenitrogen must occur before anyoneenters the drum. Before enteringdrums test to prove that the oxygenconcentration is at least 19.5%.

If storage continues into winter, ambienttemperatures below the freezing point of watercreate a real hazard to the boiler pressure partsand it will be necessary to provide a means ofkeeping the unit warm to avoid damage.

At some later date when the unit is to be placedinto service, the boiler can be drained to normalstart-up water level and placed into operation.

In some cases, an expansion tank or surge tank(such as a 55-gallon drum) above the steamdrum elevation may be required to accommodatevolume changes due to temperature changes.This tank is equipped with a tight cover and sightglass and contains properly treated water. Thetank should be connected to an available opening,such as a vent line at the top of the steam drumin order to create a hydrostatic head. This tankwill provide a ready, visual check of water level orin leakage during lay up.

A source of low-pressure nitrogen should beconnected to the surge tank to maintain 0.3 to 0.6Bar G to prevent air from entering the unit duringthe storage period.

The treated demineralised water should beanalyzed weekly, and when necessary, sufÞcientchemicals should be added through thechemical feed line, to establish the proper levelsrecommended. Samples of the treated water canbe taken at the continuous blowdown line or anysuitable drain connection.

No unit should be stored wet when there is anypossibility of a temperature drop to the freezingpoint unless sufÞcient heat can be provided to the

unit to eliminate the danger of water freezing andsubsequent damage to pressure parts.

6.4 Nitrogen Blanket

Nitrogen can be introduced at the followinglocations

1. Through the steam drum

2. Through the main steam line

The nitrogen required to seal the drainablecomponents may be supplied from a permanentnitrogen system or portable tanks located nearthe vent elevations. Due to differences in plantlayout, the owner should choose his own methodof piping the nitrogen, either from their permanentsystem or from portable tanks, to the vent (ordrain) locations listed.

The unit should be properly tagged and theappropriate warning signs attached notingthat the boiler is stored under nitrogenpressure and that complete exhaustion ofthe nitrogen must occur before anyoneenters the drum.Before entering drums test to prove that theoxygen concentration is at least 19.5 %

6.5 Hot Draining

If the WHRB shut down is for a short periodof less than seven days and during that periodmaintenance work on pressure parts have to beundertaken, the WHRB can be preserved by hotdraining

The shut down WHRB is allowed to depressurizeupto 2kg/cm2 (g) pressure on the drum. Waterlevel is maintained upto prescribed levels till thattime.

When the steam drum pressure drops to 1.5kg/cm2 (g), the air vents of the steam drum, Superheaters, economizer are opened and the WHRBis drained through the economizer, evaporator(or only the sections required) by opening therequired drain valves.

When all the water is drained, the residual heatof the water wall, economizer, Super Heater andsteam drum, ßash dries most of the moisturepresent on the tube surfaces. As the pressureparts remain dry, corrosion is prevented. This

Section D 73


method of preservation however is not effectivefor move than a week.

6.6 Alkaline Water Dozed WithHyderzine

If a WHRB has to be preserved for long periods(two months or more) an effective method ofpreservation is to Þll the WHRB, Super Heaterand economizer with water treated with ammoniato a pH of 10.5 and dozed with 200 PPM or morehydrazine.

This water is completely Þlled in the water andsteam space of the WHRB and a pressure of 5kg/cm2 (g) is maintained in the drum by a pump.

This method is effective but requires additionalequipment such as a tank, and a pump with aconnection to one of the drain headers.

All the possible methods of preservation of a shutdown WHRB, the nitrogen blanketing method issimple and suitable for the type of preservation,which may be ordinarily required.

6.7 Preservation of Extra Surfaces ofPressure Parts of WHRB DuringLong shutdown

During WHRB shut downs exceeding a few days,the external surfaces of the pressure parts ofespecially in a chemical plant environment, maycome under corrosive attacks by moisture, SO2,SO3 vapors etc.

Keeping inspection doors tightly closed (when noinspection is being planned) may minimise suchcorrosion.

Water lancing with hot water or mild alkalinewater once a month may wash out the corrosivecomponents from the external surfaces of thepressure parts. (See maintenance volume)

Section D 74


6.8 Boiler Lay Up Procedures

TYPE OF SHUTDOWN PROCEDURE

SHORT OUTAGES4 DAYS OR LESS. UNIT NOT DRAINED

Maintain the same hydrazine and ammoniaconcentration as present during normal operation.Establish 0.3 to 0.6 kg/cm2G nitrogen cap on thesteam drum

SHORT OUTAGES4 DAYS OR LESS. UNIT IS DRAINED

Drain and open only those sections require repair.Isolate remainder of the unit under 0.3 to 0.6 BarGnitrogen pressure where possible. Maintain thesame nitrogen and ammonia concentration for waterremaining in the cycle

LONG OUTAGESLONGER THAN 4 DAYS UPTO 15 DAYS.UNIT IS DRAINED

Fill the boiler with Polish water having 200 ppm ofhydrazine and 10 ppm of ammonia to maintain pH10.

Establish nitrogen cap of 0.3 to 0.6 kg/cm2G over thesteam drum.

LONG OUTAGESMORE THAN 15 DAYS - UNIT IS DRAINED.

Dry storage of boiler with nitrogen alone is preferredprocedure. Nitrogen cap of 0.3 to 0.6 kg/cm2G to bemaintained on the steam drum. Installed silica geltray in the steam drum to soakmoisture if any presentin the drum atmosphere.

6.9 Preservation of RotatingEquipments

1. Put the rotating equipment in service once inevery 48 hours or atleast once in a week

2. If the equipment is going to be under longshutdown

a. Fill bearing block full of oil to preserve thebearing and rotate the Fan/Pump Shaft by90o once in every 48 hours ( If bearinghousing is oil lubricated)

b. Rotate the fan / pump shaft by 900 oncein 48 hours ( for bearing housings withgrease )

c. Cover the bearing block & uncoveredportion of shaft with plastic sheets toprevent dust/water ingress

d. Ensure no dust/water accumulates on therotating equipment.

6.10 Preservation of Instruments

1. Cover all Þeld instruments with plastic sheets

2. Power up the panel instruments and check theoperation

3. Keep the control room dust and moisture free

4. Operate control valves, power cylinders oncea week and check operation.

5. Operate quick shutoff valves frequently(Twice a week)

6. Ensure that O2 analyzer is powered up andreference air supply is given when ßue gas ispresent.

7. Check operation of Ignition Transformer oncein 2 weeks if burners are provided.

8. Check operation of Flame Scanners & FlameAmpliÞers once in 2 weeks if burners areprovided.

6.11 Tube Thickness Survey

The following checks relate only to externalerosion / corrosion of the tubes and that tooqualitatively.

To make a quantitative assessment of wastage oftubes (both internal and external) a tube thicknesssurvey using ultrasonic tube thickness gaugesis recommended. For a useful tube thicknesssurvey program, measurement locations on inbedevaporators, Furnace water wall, superheatersand economizer tubes must be speciÞed andindicated on a drawing. Vulnerable locations areusually chosen. On request, the Field EngineeringDepartment of TL can establish such a program.

Each document should have the followingminimum vital information.

Tube thickness measurements at the selectedlocations are made and recorded after water

Section D 75


washing and drying, during the Þrst annualoverhaul. The base value is the design thicknessof the tubes. Subsequent measurements aremade at the same locations, every alternate year.The tube thickness survey provides useful dataon corrosion / erosion rates and can alert theowner when serious loss of thickness is noticed.

Details with sketches and drawings will givemore clarity for analysis

� Date of inspection

� Tube no / Coil no.

� Inner coil / Outer coil details

� Location. � RHS / LHS

� Clock position.

� Reference points.

� Thickness including decimals.

� Visual observations

� Condition of studs.

7 Tube Failures

Operating a boiler with a known tube leak is notrecommended. Steam or water escaping from asmall leak can cut other tubes by impingementand set up a chain reaction of tube failures. Largeleaks can be dangerous. The boiler water may belost, the ignition may be lost, and the boiler casingmay be damaged.

Small leaks can some times be detected by theloss of water in the cycle or system, a loss in boilerwater chemicals or by the noise made by the leak.If a leak is suspected the boiler should be shutdown as soon as possible by following normal shutdown procedures (If situation permits).

After the exact locations of the leak or leaks areidentiÞed, the leaks may be repaired by replacingthe failed tube or by splicing in a new section oftube, conÞrming to IBR code.

An investigation of tube failure isvery important so that the conditioncausing the tube failure can beeliminated and future failures can beprevented. This investigation shouldinclude a careful visual inspection ofthe failed tube and in some cases alaboratory analysis.

� It is recommended that every effort be made toÞnd the cause of tube failures before operationis resumed.

� It should be ensured that, whenever a spoolpiece is inserted in the failed zone, the weldjoint needs to be of proper weld quality.

� Free from excess weld penetration to avoidany obstruction in the water / steam mixtureßow inside the tube. Excess weld penetrationcan cause internal tube erosion and results intube failures.

� It is suggested to have all the joints are x-rayedand interpreted by qualiÞed / experiencedradiographer.

7.1 Tube Failure Investigation /Analysis Method

Investigation / analysis methodology is listed asfollows, which needs to be followed to Þnd theactual root cause of the problems.

Please fill up the enlcosed form duly filled andthe same may be sent to Thermax along withtube sample for analysis.

Objectives of Failure Investigation

Boiler tube failures are the largest cause of forcedoutages experienced by a utility. To avoid orminimize outages and the associated economicpenalties, it is important to identify the mechanismand root cause of tube failures. Informed visualinspection is often adequate for this purpose,however failure analysis involving detailedmetallurgical investigation is necessary. Tubefailures may be due to overheating, corrosion,erosion, fatigue, hydrogen damage etc. A failureinvestigation and subsequent analysis shoulddetermine the primary cause of a failure, andbased on determination, corrective action shouldbe initiated that will prevent similar failures.

Stages of Failure AnalysisAlthough the sequence is subject to variation,depending upon the nature of a speciÞc failure, theprincipal stages that comprise the investigation &analysis of a failure are:

1. Collection of background & selection ofsamples

2. Preliminary examination of the failedpart(visual examination & record keeping)

3. Nondestructive testing

4. Mechanical testing (including hardness &toughness testing)

Section D 76


5. Selection, identiÞcation, preservation, and/orcleaning of all specimens.

6. Macroscopic examination andanalysis(fracture surfaces, secondary cracks,& other surface phenomena)

7. Microscopic examination and analysis

8. Selection & preparation of metallographicsections

9. Examination and analysis of metallographicsections

Collection of Background OperatingDataBoiler operating data just before & at the timeof a tube failure is very important as it will giveinformation of the service conditions faced by thetube at the time of failure. This operating datashould also be co-related with the past operationdata & abnormalities if any should be taken careoff. Water chemistry analysis, fuel analysis shouldalso form an important part of this data. This data& the metallurgical analysis will help us in truesense to arrive at the exact cause of a tube failure.

Investigation of Tube Failure in aBoiler1. Study the boiler log sheet & water chemistry

record prior to tube failure and after tubefailure. Preserve the copies of these logsheets. Record, if any abnormality noticed,such as mal operation, malfunction, veryhigh or low temp. / loads, ßuctuating loads,sudden increase in load or temp., poor waterchemistry, start up vent crack open / closeetc. etc. (if possible collect and send thewater samples, internal scale from drum &tubes, external scale samples).

2. After entering in boiler and before proceedingto tube failure location inspect & recordthe condition of boiler and pressure partswithout disturbing the evidence i.e. distortionof pressure parts/coils, bulging of pressureparts, scaling / lump formation on pressureparts, blockage of ßue gas path, other /secondary failures etc. etc. In such casetaking photographs will help in great extent inanalyzing of the tube failure, boiler problem.

The failed pressure part tube should not behammered, any mechanical impact should beavoided.

3. Inspect the failed tube and record all Þndingson the same as well as its adjacent tubes.Carry out dimensional measurement of failedtube and affected adjacent tubes.

4. Number mark the failed tube for its location,ßue gas ßow, steam ßow with oil paint.After completion of inspection, recordingand photography, cut the failed tube andaffected adjacent tube, if any, with the helpof HACKSAW only. Gas cutting of the tubesshould be avoided as much as possible.The failed tube, keeping the failed portionin middle should be cut for total length ofminimum 350 mm. Immediately after cuttingthe tube sample both the ends should becovered with plastic caps. While doing thisthe internal or external scale of tube shouldnot fall down.

5. The failed tube samples nicely packed inplastic bag / wooden case accompanying dulyÞlled format with water chemistry of boiler logsheets should be sent to H.O Pune.

Removal of Failed Tube Sample1. The tube sample should be cut with a

hacksaw blade. Gas cutting should beavoided.

2. The sample should be cut approx. 8-10inches above & below the affected area.

3. & elevation should be marked on the tubesample.

4. The direction of the ßuid ßow should bemarked on the tube sample.

5. Immediately after cutting the tube sampleboth the ends should be covered with plasticcaps. While doing this the internal or externalscale of tube should not fall down.

The failed tube sample nicely packed in plasticbag / wooden case accompanying duly Þlledformat as given below with water chemistryof boiler log sheets should be sent to H.O formetallurgical investigations.

Section D 77


7.2 Tube Thickness Survey DataCollection – Format

(FURNACE / BOILER BANK / ECONOMISERTUBES)

BOILER NUMBER :

DATE OF INSPECTION :

UNIT NO :

CUSTOMER :

COIL NO CLOCKPOSITION

TUBETHICKNESS

STUD LENGTH VISUALOBSERVATIONS

DATA COLLECTION BY

NAME & SIGNATURE

7.3 Failure Reporting Formats

THERMAX LIMITED

ENERGY BUILDING, D1 BLOCK, MIDC, R.D AGA ROAD,

CHINCHWAD, PUNE – 411 019 - INDIA

TELEPHONE 020 – 66126464

FAX : 020 – 27479048

WEB SITE : http://www.thermaxindia.com

EMAIL : [email protected]

[email protected]

DEAR CUSTOMER,

WE WANT TO HEAR FROM YOU,

WE STRIVE TO CONTINUOUSLY IMPROVE THE QUALITY AND PERFORMANCE OF OURPRODUCTS. WE WOULD LIKE TO HEAR FROM YOU, SHOULD YOU EXPERIENCE PROBLEMSWITH OUR EQUIPMENT OR SHOULD YOU WANT TO SUGGEST IMPROVEMENTS,

JUST FILL IN THE INFORMATION NEEDED AT THE ENCLOSED FORMAT AND FAX / POST IT TOOUR CUSTOMER SERVICE DEPARTMENT TO THE ABOVE MENTIONED ADDRESS.

KINDLY USE ADDITIONAL SHEETS IF REQUIRED.

PLEASE PROVIDE ADEQUATE INFORMATION / DRAWINGS REFERENCE / LOG SHEETREADINGS ETC FOR PROPER ANALYSIS & FEED BACK

WEWILLGLADLYREVIEWYOURSUGGESTIONSANDREPLY TOYOUWITH IN AREASONABLETIME.

WE ARE AT YOUR SERVICES ALWAYS,

U.S. UMALE

DY GENERAL MANAGER (FIELD ENGG.)

Section D 78


CUSTOMER FEEDBACK FORM CUSTOMER DETAILS:

COMPANY NAME

COMMUNICATION ADDRESS

TELEPHONE NUMBER

FAX NUMBER

E-MAIL ADDRESS

CONTACT PERSON

OTHER DETAILS (IF ANY)

BOILER DETAILS

BOILER NUMBER :

DATE OF COMMISSIONING;

BOILER CAPACITY – MCR

STEAM PRESSURE

STEAM TEMPERATURE

FUEL FIRED

EQUIPMENT DETAILS

S.N PROBLEMDETAILS

OBSERVATIONS CORRECTIVEACTIONS TAKEN

COMMENTS /RECOMMENDATIONS

1.

2.

OTHER INFORMATION:

EXPECTATIONS FROM TBW :

REPLY AWAITED / SERVICE ENGINEER VISIT :

SIGNATURE & DATE

Section D 79


8 Welding ProcedureSpecifications

The pressure part of the boiler is made of severaltypes of steel of varying thickness. Welding isthe basic technique used in the fabrication of theboiler. The joints produced by welding shouldhave strength not less than that of the parentmetal. In the weld joint, the parent metals shouldfuse together, without cracks, blowholes, slaginclusions or defects of any kind. The weld jointapart from proving its mechanical strength intension must also be able to resist bending withoutcracking. Such requirements can only be met ifthe welding process used is strictly controlled.

ASME (and other organizations) classify materialsinto categories (P1 P2, P3, ... P9) as per carboncontent and alloying metals (chromium, Nickel,Molybdenum etc.) and specify the procedureto be used for welding materials of the samecategory or one category with another category.A speciÞcation of the materials and shapesadopted by Thermax can be obtained on request.The welding procedure distinguishes betweenwelding of thin and thick material. The weldingprocess speciÞcation deÞnes the following foreach category of welding.

� Edge preparation (angle, shape)

� Joint preparation (cleaning, gap) and tagging

� Joint pre-inspection before welding

� Pre-heat of the weld joint, if any required(method of pre-heating, temperature method ofchecking temperature)

� Root weld (gas welding, TIG or Arc, size ofelectrode, type of electrode)

� Radiographic inspection of root weld if required

� Subsequent runs of welding (TIG, Arc or othermethods, size of electrode, type of electrode,number of runs)

� Post weld heat treatment if any required(temperature, rate of increase of temperature,method of increasing temperature, holdingtime, rate of cooling)

� Radio graphic examination of the weld joint,indicating defects if any to be corrected

� Correction of weld defects

� Final acceptance of the weld joint

The WPS indicates compatible categories ofmaterials that can be welded. The WPS also laysdown the type of electrode to be used for each

category of welding. As the electrode depositsmaterials, the composition of the electrode mustbe compatible with the material welded and addstrength. The coating of the electrode also mustmeet speciÞc requirements.

TheWPSmust be used not only during fabricationof the boiler, but also when any repair ormaintenance works are to be done. Thermaxhas WPS to cover every welding job connectedwith fabrication of the boiler in the factory anderection of the boiler at site, conforming to IBRrequirements. The Field Engineering Departmentof Thermax will be glad to provide a WPS for anysite repair weld jobs required for maintenance.

8.1 Window Patch Welding

PURPOSE

The purpose of the window patching method is toallow the welding of tubes that could not otherwisebe welded because of limited access to part of thetube diameter. This procedure is restricted to thatuse.

PREPARATION

1. The area to be patched shall be cleaned tobare metal.

2. The patch shall be made from tube materialof same type, diameter and thickness, as thetube being welded

3. The area of the tube to be removed shall becarefully marked out as close as possible tocontour of the patch. The tube section maythen be removed using an oxyacetylene gascutting torch or by mechanical means

4. The weld preparation shall be made as per theFigure #1. The Þt up of the patch weld gapshall be 2.4 ±0.8 mm

Welding

1. A welder qualiÞed to the requirementsof ASME shall make the tube and patchwelds in accordance with an approved weldprocedure.

2. The root pass shall be done with GTAWprocess. The weld may then be completedwith either SMAW or GTAW process. Someacceptable weld procedure speciÞcations arelisted in Table below

TESTING

All the tube and patch welding shall be subjectto close visual inspection and 100% radiography

Section D 80


in accordance with the requirements of ASMEsection V. The standard for accepting /rejecting isspeciÞed in ASME section I

� Completed welds are subject to hydrostatic test

Base Material Filler Metal

P1 TO P1 Carbon Steel To Carbon Steel ER 70S.2 E7018

P3 TO P3 Carbon ½ Moly To Carbon ½ Moly ER80S.B2 E7018A1

P3 TO P3 ½ Cr ½ Moly To ½ Cr ½ Moly ER80S.B2 E8018B2L

P4 TO P4 1-1/4 Cr TO 1-1/4 Cr ER80S.B2 E8018B2L

P5 TO P5 2-1/4 Cr 1 Moly To 2-1/4 Cr 1 Moly ER90S.B3 E9018B3L

P8 TO P8 Stainless To Stainless ER308 ER308-16

Figure 3

9 General Principle Of WeldRepairs

9.1 Furnace and Boiler Tubes

1. The minimum replacement tube length shouldbe not less than 150 mm. A damaged tubeshould be cut at least 75 mm each side of thedefective area.

2. Backing rings must not to be used in weldingheat absorbing tubes carrying water ormixture of steam and water.

3. If a backing ring is not used, the Þrst passof the weld must be made with inert gas-arcor oxy acetylene. The weld passes may becompleted by either process, or by a manualmetal arc.

4. Pre heat or post heat is not required forwelding carbon steel furnace or boiler tubes.

5. Prior to welding, clean the tube ends to brightmetal inside and outside for at least 40 mm

from the weld area. Remove all deposits ofoxide, boiler water salts and slag to avoid gasor slag inclusions in the weld.

6. Fit-up of the weld joints is important. It isdifÞcult to obtain accurate cuts on furnacetubes especially those in welded furnacewalls. However, it is worth to spend extratime to get the existing tube ends squaredand correctly chamfered and to cut thereplacement tube to the correct length.Poor Þt-up increase the possibility of anunsuccessful weld.

7. Allow for shrink in the welding, remember, theweld metal and parent metal are melted in thewelding process and the molten metal shrinksas it solidiÞes. A butt weld in the tube willshorten the total tube length about 1.6 mm.

8. Use a clamp or guide lug to hold one endof the replacement tube alignment while theÞrst weld is made. Do not tack weld bothend of the replacement tubes particularly if theexisting tubes are rigidly supported

9. As a general rule, Þrst complete the weldsat the lower end of the replacement tube.Do not start welding the upper end of thereplacement tube until both the replacementand the existing tubes have cooled to ambienttemperature.

WELD REPAIR OF SMALL CRACKS IN TUBE

In the interest of saving time and cost, it is betterto weld small cracks rather than replace a lengthof the tube.The crack must be ground out to forman acceptable welding groove. The groove shouldcontinue well beyond the ends of the crack. Inertgas arc or oxy acetylene process must make theÞrst pass of the weld.

Note

1. This type of the repairs entails some risk.Internal deposits. Particularly copper, mayexist under the crack which will result in

Section D 81


damaging the parent and/or weld metalcausing failure in a short period of time.

2. Over-heating the tube may have caused thelongitudinal crack. In this case, the tubehas swollen and the weld thickness reduced.In the modern welded wall construction, itis difÞcult to accurately measure the tubediameter or circumference to detect the minorswelling. If visual indicates swelling andreduction of wall thickness at the crack, acomplete replacement of the damaged tubelength is the best solution.

3. A circumferential crack indicates a failuredue to excessive stress applied by expansionrestriction, bending or fatigue; welding canrepair such cracks. However, unless thecause of failure is diagnosed and corrected,another similar failure could occur at or nearthe original crack.

4. Also the tube cannot be cleaned from insideand there is always a possibility internaldeposits will contaminate the weld.

9.2 Weld Repair Of Small Cracks inTube

In the interest of saving time and cost, it is betterto weld small cracks rather than replace a lengthof the tube.The crack must be ground out to forman acceptable welding groove. The groove shouldcontinue well beyond the ends of the crack. Inertgas arc or oxy acetylene process must make theÞrst pass of the weld.

Note

1. This type of the repairs entails some risk.Internal deposits. Particularly copper, mayexist under the crack which will result indamaging the parent and/or weld metalcausing failure in a short period of time.

2. Over-heating the tube may have caused thelongitudinal crack. In this case, the tubehas swollen and the weld thickness reduced.In the modern welded wall construction, itis difÞcult to accurately measure the tubediameter or circumference to detect the minorswelling. If visual indicates swelling andreduction of wall thickness at the crack, acomplete replacement of the damaged tubelength is the best solution.

3. A circumferential crack indicates a failuredue to excessive stress applied by expansionrestriction, bending or fatigue; welding canrepair such cracks. However, unless thecause of failure is diagnosed and corrected,

another similar failure could occur at or nearthe original crack.

4. Also the tube cannot be cleaned from insideand there is always a possibility internaldeposits will contaminate the weld.

9.3 Plugging Tubes in Drums &Headers

1. Often after a tube failure, it is desirable to plugthe failed tube in the drum or header shellso the boiler may be returned to service withthe least possible delay. It is recommendedthat the failed tube be replaced wheneverpossible in lieu of plugging. If the leak isremote from the tube seats and accessible,the faulty section of the tube should be cutout and replaced rather than plugging.

2. Water wall tubes (space tube) should bereplaced if possible and plugged only as alast resort. The plugged tube must be freeto expand and distort with respect to theadjacent tubes. Membrane tubes must berepaired and not plugged.

3. When tubes are plugged, the old tube shouldbe removed from the boiler setting since itprobably will burn off due to lack of coolingand could become displaced and obstruct gaslanes, foul up soot blowers, be dangerous topersonnel after shutdown, and etc. If the tubeis not removed from the setting, a deÞnitehole must be punched or drilled in the tubeto prevent a possible dangerous buildup ofpressure between the tube plugs.

4. A expanded tube leaking at the seat shouldbe removed from its seat and

a. a new tube rolled in

b. a new short stub rolled in and plugged

c. the tube end seal welded to the shell or, ifthe drum shell is internally counter bored,a cylindrical plug must be installed andseal welded to the drum shell.

Note: Point. (a) is the preferred Þx with Point.(c) the least preferred.

5. Seal welding of tube ends, tapered plugs, orcylindrical plugs to the shell should be donein such a manner as to minimize the heatingof adjacent tube seats, which may becomeloose. It is essential that the welding processshould be as per standard procedure forcarbon steel shells and tubes to be followedvery closely to ensure success. Deviationsfrom these parameters will normally result

Section D 82


in unsatisfactory connections. The majorwelding parameters for shells or tubesother than carbon steel may be obtainedfrom qualiÞed welding procedures. Ensurethat welders are qualiÞed in accordancewith ASME Section IX and local provincialrequirements. They must also ensure thatthe welding is done to the applicable qualiÞedweld procedure.It also to be ensured thatthe proposed repair has been approved bythe Boiler Inspection Branch of the localjurisdiction.

6. Machined tube stubs and plugs are usedwhere the old tube can be removed fromits seat without seat damage and for newconstruction that is drilled for future additionof tubes. The rolled-in tube stub extends intothe shell and a solid plug is installed and sealwelded to the stub. These stubs and plugsare standardized to have only one tube stuband one plug for each standard tube hole.

7. Before rolling stubs in, they should be cleanedinside and outside with a wire brush, abrasivepaper, or a liquid cleaner until the metal is freeof all foreign substances. In general, stubsdo not require cleaning beyond the removalof dirt, rust, scale or foreign material.The stubseat (tube hole) should be similarly cleaned. Ifa liquid solvent is used to clean either the stuband/or tube hole, caremust be taken to dry themetal completely. Liquid trapped between thestub and its seat prevents contact of the twometal surfaces.

8. Before the expanding tool is inserted, theinside of the stub should be lubricatedwith a suitable compound. The compoundselected should be water soluble to facilitatecleanup. The rolling process should not berushed since heat generated during rolling isdetrimental to the strength of the rolled joint.The tube stub is properly expanded when thewall thickness in the seat is reduced by 6 to10 percent for generating tubes and 10 to 14percent for other boiler tubes. The tube stubwall reduction for thin shells should be lessthan that for thicker shells. This is to preventover rolling which could cause adjacent tubeseats to leak. Since the stub wall itself cannotbe measured after it is rolled in its seat, theonly alternative is to calculate the increase inthe stub ID that is necessary to prove that thewall has in fact been reduced by the requiredpercentage. This depends upon the tubeseat ID (hole diameter), tube stub OD, theclearance between these two and also thestub wall. An example of this conversion for

a 2 ½" OD by 0.150-inch wall tube stub for a10% wall reduction is as follows

Measure Hold Dia=

2.531

Measure Stub OD=

-2.500

0.031 Clearance

Measure Stub ID = 2.200

Clearance = 0.031

2,231 Stub ID @Contact

Stub ID @ Contact=

2,231

10% of 0.150 x 2 = 0.030

2.261 Stub ID afterexpanding

9. Plug all internal counter bored holes in theÞeld with the cylindrical plug when the tubeis still in the seat. Some counter bores maybe shallow enough that the tube ends areexposed sufÞciently to permit seal welding toa tapered plug. 9.6 See Figure 04, page84. If the tube seat is leaking, then the tubemust either be seal welded to the drum shellor the counter bore can be plugged with thecylindrical plug and seal welded per Figures04 and 12. It may be necessary to machinethe tube ends back in order to provide a seatfor the cylindrical plug installation. See Figure05 and Figure 06.

10. Figure 07 shows the details of this cylindricalplug and gives instruction for the speciÞc plugsize desired.

11. Tapered plugs are used to plug existing tubeswhere it is not practical to remove the tubefrom its seat and there is no internal counterbore. These plugs must be tailor made foreach tube diameter and tube wall thickness.Figure 08 shows the details of this taperedplug and give instructions for a plug to Þttube diameters from 1-3/4" through 4 ½" ODand any wall thickness. Figure 09 shows thearrangement of the tapered plug seal weldedto the tube.

12. The plugs and seal welds described aboveare designed for the boiler pressure to be onthe head (seal weld side) of the plug only. The¾ inch diameter by 1/8-inch thick button weldon the plug is to eliminate leakage through the�piping� which can occur at the center of somebar stock.

Section D 83


13. Figure 10 shows a tube seal welded to theshell. This arrangement may be used whenthe tube seat is leaking and it is not practicalto replace or remove the tube and use a rolledstub and plug.

14. Economizer headers and superheaterheaders may be plugged as shown in Figure11 & Figure 12 where external access isavailable and the conditions shown on theÞgures are met. If those conditions cannot besatisÞed, tube replacement is recommended.In these two Þgures, the pressure is on theinternal end of the plug and the externalstrength weld restrains the plug.

15. Plugged tubes that are below the horizontalcenterline of the shell will not drain.Therefore, after chemical cleaning it isnecessary that the plug to be removed and thestub swabbed out to remove the chemicalsin these stubs. The plug can then be weldedback in or in some cases it will have beendestroyed in the removal process and anewone will have to be installed. Care must betaken in the plug removal process to notdamage or thin the tube stubs wall.

9.4 Replacement of Tube Section

Experienced personnel must do the replacementof a section of failed tube.

1.

� The length of the replaced section shouldbe a minimum of 12 inches

Usual practice is to cut out the defectivesection with an oxyacetylene torch, but it ispreferable to use a hack saw or wafer disc.Care must be taken to prevent slag fromentering the tube. The ends are prepared forwelding by grinding or with special tools

2. The root pass of the joint should be depositedwith the gas tungsten arc process.

A 3/32 - inch diameter shielded metalarc-welding electrode is recommended forthe remainder of the joint.

The welding parameters for tubes may beobtained from qualiÞed Welding Procedures.

9.5 Removing Tubes from Drums,Headers & Tube Plates

1. The removal of tubes from their tube seatsmust be done very carefully to prevent

damage to the tube seats. If the tube seatis damaged, it may be impossible to everroll another tube in and make a tight seal.Gouging of the tube seat could also affect theligaments between tube holes and integrity ofthe shell. Tubes can be removed from theirseats without seat damage if the followingprocedures are carefully followed. With light-gage tubes, it is often possible to cold crimpthe tube end to loosen it in its seat, then driveor "jack" the tube out.

2. When the tubes are too heavy for coldcrimping, the two-stage heating method maybe used. Heat is applied to the inside of thetube end with a torch. Heat is Þrst applied fora short period - not long enough for it to betransferred to the tube sheet. When the tubeend cools, the joint will have loosened enoughso that the second heat will not be transferredreadily to the tube sheet. The tube end canthen be heated sufÞciently for crimping andthe tube can be pushed out of its seat. Ifneither of these methods is applicable, thefollowing methods may be employed.

3. To remove light tube tubs, it is advisable tocut grooves about 3/4 inch apart with a roundnose chisel. When the tongue (the metalbetween the two grooves) is knocked free, thetube can be collapsed and removed.

4. To remove heavy gage tubes, the type ofgrooving tool shown in Þgure 12 is usedto prepare the tongues without damage tothe tube seat. It is used with a pneumatichammer, but it is necessary that the tool besuited to the tube thickness so that it willcut the grooves as deep as possible and yetleave a minimum thickness of metal overthe tube seat. In very heavy gage tubes, athird groove is often cut, as nearly oppositethe tongue as possible, so that less heavypounding will be required to collapse thestub. These latter two methods require thatthe ßare on the end of the tube be crimpedstraight before starting, to cut the grooves forcollapsing the tube. Of course, the seal weldaround the end of any tube must be groundor machined off before attempting to cut thegrooves for collapsing the tube. This must bedone carefully to prevent damage to the drumshell.

9.6 Plugging of Tubes Drawings

Attached Þgures 04 to 12

Section D 84


Tapered plug application for shallow internal CTR’B Tube end must be exposed sufficiently for seal welding.Figure 4

Section D 85


Figure 5

Section D 86


Figure 6

Section D 87


Figure 7

Section D 88


Figure 8

Section D 89


Figure 9

Figure 10

Notes:

• T1 is the greater of 1.25 x Nominal tube wall or 3/16”

• Plug Head O.D = nominal Tube I.d – 3/32”

• Plug length is 1’ up thru 3’ O.D tube over 3” O.D

• Tube use 2” Length

• Plug of SA 181 Gr70 preferrred

• SA 105 is acceptable.

Section D 90


Figure 11

Notes:

• T1 is the greater of 1.25 x nominal wall or 3/16

• Plug diameter = Nominal tube I.D – 3/32”

• Plug length is 1” up thru 4 ½’ O.D tube

• Plug of SA 181 Gr 70 material preferred

• Sa 105 is also accepted

Section D 91


Figure 12

Section D 92


10 Water Chemistry

INTRODUCTION

The natural water contains solid, liquid andgaseous impurities and therefore, this cannot beused for the generation of steam in the boilers.The impurities present in the water should beremoved before its use for steam generation.The necessity for reducing the corrosive natureand quantity of dissolved and suspended solidsin feed water has become increasingly importantwith the advent of high pressure, critical andsupercritical boilers.

The impurities present in the feed water areclassiÞed as given below

1. Un dissolved and suspended solid materials.

2. Dissolved salts and minerals.

3. Dissolved gases.

4. Other materials (a soil, acid) either in mixedand unmixed forms.

10.1 Undissolved and Suspended SolidMaterials

A) TURBIDITY AND SEDIMENT:

Turbidity in the water is suspended insolublematter including coarse particles (mud, sedimentsand etc,) that settle rapidly. Amounts rangesfrom almost zero in most ground waters and60,000 ppm. in muddy and turbulent river water.The turbidity of feed water should not exceed5 ppm. These materials can be removed bysettling coagulation and Þltration. Their presenceis undesirable because heating or evaporationproduces hard stony scale deposits on theheating surface and clog ßuid system. Both areobjectionable as they cause damage to the boilersystem. A standard of measurement of hardnessis taken as being the amount of calcium carbonate(CaCO3) in the water and is referred to in part permillion (ppm) or grains per gallon (grain/gallon) X17.1 = ppm.

B) SODIUM AND POTASSIUM SALTS:

These are extremely soluble in water and donot deposit unless highly concentrated. Theirpresence is troublesome as they are alkaline innature and accelerate the corrosion.

C) CHLORIDES:

Majority of the chloride causes increasedcorrosive action of water.

D) IRON:

Most common soluble iron in water is ferrousbicarbonate. The water containing ferrousbicarbonate deposits becomes yellowish andreddish sediment of ferric hydroxide if exposedto air. Majority of ground surface water containsless than 5 ppm but 0.3 ppm, can create troublein the feed water system by soft scale formationand accelerating the corrosion.

E) MANGANESE:

It also occurs in similar form as iron and it is alsoequally troublesome.

F) SILICA:

Most natural water contains silica ranging from 1to 100 ppm. Its presence is highly objectionableas it forms very hard scale in boilers and formsinsoluble deposits on turbine blades. In modernhigh-pressure boilers its presence is reduced aslow as 10-50 ppm.

G) MICROBIOLOGICAL GROWTHS:

Various growths occur in surface water (lakeand river). The microorganisms include diatons,molds, bacterial slimes, algae; manganese andsulfate reducing bacteria and many others. Thesecan cause coating on heat exchanger and clogthe ßow passages and reduce the heat transferrates.

H) COLOR:

Surface waters from swampy areas becomehighly colored due to decaying vegetation. Colorof feed water is objectionable as it causes foamingin boilers and may interfere by chlorinating ofabsorption by activated carbon.

10.2 Dissolved Salts and Minerals

A) CALCIUM AND MAGNESIUM SALTS:

The calcium and magnesium salts present in thewater in the form of carbonates, bicarbonates,sulfates and chlorides. The presence of thesesalts is recognized by the hardness of the water(hardness of water is tested by soap test). Thehardness of water is classiÞed as temporary andpermanent hardness. The temporary hardnessis caused by the bicarbonates of calcium andmagnesium and can be removed by boiling. Theboiling converts the soluble bicarbonates intoless soluble carbonates, which can be removedby simple blow-down method. The presenceof chlorides, sulfates and nitrates of calcium

Section D 93


cause the permanent hardness of the water andmagnesium and they cannot be removed just byboiling because they form a hard scale on heatingsurfaces.

10.3 Dissolved Gases

A) OXYGEN:

It presents in surface water in dissolved form withvariable percentage depending upon the watertemperature and other solid contents in water. Itspresence is highly objectionable, as it is corrosiveto iron, zinc, brass and other metals. It causescorrosion and pitting of water lines, boilers andheat exchangers. Its effect is further acceleratedat high temperature.

B) CARBON DIOXIDE:

The river water contains 50 ppm & well watercontains 2-50 ppm of CO2. It also helps toaccelerate the corrosive action of oxygen.

The other gases are H2S, CH4, N2 and manyothers but their percentage are negligibleTherefore their effects are not discussed here.

10.4 Other Materials

A) FREE MINERAL ACID:

Usually present as sulfuric or hydrochloric acidand causes corrosion. The presence is requiredby neutralization with alkalis.

B) OIL:

Generally the lubricating oil is carried with steaminto the condenser & thorough the feed system tothe boiler. It causes sludge, scale & foaming inboilers. Strainers and bafße separators generallyremove it.

The effects of all the impurities present in thewater are the scale formation on the differentparts of the boiler system and corrosion. Thescale formation reduces the heat transfer ratesand clogs the ßow passage and endangers thelife of the equipment by increasing the tempabove the safe limit. The corrosion phenomenonreduces the life of the plant rapidly. Therefore itis absolutely necessary to reduce the impuritiesbelow a safe limit for the proper working of thepower plant.

10.5 pH Value of the Water and itsImportance

The pH value of the feed water plays veryimportant controlling the corrosion. pH is a

number denoting the degree of acidity or alkalinityof a substance. It does not indicate the quantityof acid or alkali in a solution as found by Þltrationmethod. It is derived by measuring the amount ofhydrogen ion (H+) in grams per liter of solution.The greater the amount of hydrogen ions presentin solution its acid reaction becomes stronger.Therefore, pure water is being neutral solution,any solution producing more hydrogen ion thanpure water will be acidic and degree is governedby difference and other solution producing lesshydrogen ions than pure water will be alkaline andthe degree is also governed by the difference.

THE ROLE OF pH IN CORROSION:

The role of pH in corrosion of metals is extremelyimportant. The corrosion rate of iron in theabsence of oxygen is proportional to pH up to avalue of 9.6. At this point, hydrogen gas formationand dissolving of iron practically stops. This isthe came pH produced by a saturated solution offerrous hydroxide Fe (OH) 2.

The Oxygen in the water unites with ferroushydroxide to form ferric hydroxide. This reactionlowers pH of the solution and levels to stimulatecorrosion.

Alkalinity adjustment and Þlm formation areclosely related. The pH value of feed water shouldbe maintained greater than 9.6 to reduce thecorrosion effects caused by the reason mentionedabove. The required alkalinity of feed water isadjusted by adding soda ash caustic soda ortrisodium phosphate. The calcium hardness,alkalinity and pH are inter-related variables inscale control. Calcium carbonate is one of themost troublesome deposits responsible for scaleformation.

10.6 Effects of Impurities

The major troubles caused by the feeding ofwater of undesirable quality are scale formation,corrosion, foaming, caustic embrittlement,carry-over and priming. The details describedbelow: -

1. SCALE FORMATION

Feed water containing a group of impurities indissolved and suspended form ßows into theBoiler for continuos generation of Steam. Withconversion of water into steam in Boiler, solidsare left behind to concentrate the remainingwater. The scale formation tendency increaseswith the increase in temperature of feed water.Because, the solubility of some salts (as calciumsulphite) decreases with the increase in feedwater temperature. Calcium sulphite has solubility

Section D 94


of 3200 ppm. at 15 Deg. C and it reduces to 55ppm. at 230 Deg. C and 27 ppm. At 320 Deg. C.

Scale formation takes place mainly due to saltsof calcium and magnesium. Sometimes, it iscemented into a hard mass by Silica. Among all,calcium is the principal offender and particularly,Calcium sulphate, magnesium sulphate and otherChlorides are sufÞciently soluble in water and arenot much troublesome. Sodium salts are highlysoluble in water and are non-scale forming.

The scale formation takes place mainly in feedwater piping and Boiler Tubes. Its Þrst effect onthe piping system is to choke the ßow of water byreducing the ßow area and increases the pressurerequired to maintain the water delivery. Anothereffect of scale formation is to reduce the transferof heat form the hot gases to water. Real dangersof the scale formation exist in radiant heat zonewhere boiler tubes are directly exposed to thecombustion. The scale formation retards the ßowof heat and metal temperature increases. Even athin layer of scale in high heat zone can over-heatthe metal enough to rupture the tubes. The metaltubes weakened due to over-heating yield topressure providing a protrusion known as bag.Such bag provides a pocket for the accumulationof sludge and scale, which eventually causesfailure. The over-heating of metal causes layer ofmetal to separate and form a blister.

2. CORROSION

The corrosion is eating away process of boilermetal. It causes deterioration & failure of theequipment, eventually this cause for major repairsor expensive shut -downs or replacements.

The corrosion of boilers, economizers, feedwater heaters & piping is caused by an acid orlow PH in addition to the presence of dissolvedoxygen & carbon dioxide in the boiler feed water.The presence of oxygen is mostly responsiblefor corrosion among all other factors. Thepermissible limit of oxygen content varies with theacidity of water. Generally it should not shouldexceed 0.5 cc per liter .O2 generally entersinto closed system through make up condenserleakage and condensate pump packing.

CO2 is next to O2, which is responsible forcorrosion. The CO2 comes out of bicarbonateson heating and combines with water to form weakacids known as carbonic acid. This acid slowlyreacts with iron and other metals to form theirbicarbonates. The newly formed bicarbonates ofmetals decompose by heat once more and CO2 isagain liberated. This gas again unites with water

to form carbonic acid and the cycle is repeated.Adding alkali solution to neutralize acids inwater and raise the PH value can minimize thecorrosion. The effect of CO2 is minimized by theaddition of ammonia or neutralizing the amines inwater. This is necessary because CO2 lowers thePH of the boiler feed water and dissolved solidsto leave the boiler.

The priming is a violent discharge of water withsteam from the boiler. It can be compared to thepumping of water that frequently accompaniesrapid heating in a open vessel. In priming thewater level in the boiler undergoes rapid andgreat changes and there are violent dischargesof bursting bubbles. Therefore �sludge� of boilerwater is thrown over with the steam.

The priming is caused due to improper boilerdesign, improper method of Þring, overloading,sudden load changing or a combination of thesefactors. The priming effect is reduced by installingsteam puriÞer, lowering water level in the boilerand maintains constant load on boilers.

The foaming is the formation of small andstable bubbles throughout the boiler water. Thehigh percentage of dissolved solids, excessivealkalinity and presence of oil in water areresponsible for foaming.

Boiler water solids are also carried over in themoisture mixed with steam even when there isno indication of either priming or foaming. Thisis known as �carry-over�. The carry-over of boilerwater solids is partly a mechanical and partly achemical problem. The amount of suspendedsolids and alkalinity in the boiler water is alsoimportant in addition to other reasons like boilerdesign, high water level, and overloading andßuctuating loads on boiler.

3. CAUSTIC EMBRITTLEMENT

The caustic embrittlement is the weakening ofboiler Steel as a result of inner crystalline cracks.This is caused by long exposure of boiler steel tocombination of stress and highly alkaline water.

The course of embrittlement takes place underfollowing condition:

a) When boiler water contains free hydroxide,alkalinity and some silica. It has been alwaysfound that the feed water was high in sodiumbicarbonate, which broke down into sodiumcarbonate in the boiler and partially hydralizedas shown by the following reaction in case ofembrittlement.

Section D 95


Na2CO3 + HOH = CO2 + 2 NaOH

b) Slow leakage of boiler water through a joint orseam.

c) Boiler metal is highly stressed at the point ofleakage. This may be caused by faulty design andexpansion etc.

The prevention of caustic embrittlement consistsof reducing the causticity or adding inhibiting

agents to the feed water. The most practicalmethod of preventing caustic embrittlement is toregulate the chemical composition of the boilerwater. The obvious solution to embrittlement isto eliminate all free NaOH from feed water byaddition of Phosphates.

Section D 96


Section E


♦ Lubrication Schedule

1 Lubrication Schedule

This section holds the Lubrication Schedule for the Waste Heat Recovery Boiler on Coke Oven

Lubrication Schedule

Section E 97

./O & M Manual.pdf.ditaLinks/Lubrication Schedule_PL0501-02.pdf


Volume 2 — Drawings


♦ List of Drawings

Volume 2 � Drawings 98


List of Drawings

COMMON DRAWINGS FOR BOILER 1 & 2 WHRB

01. P & ID for Waste Heat Boiler (Coke Oven Plant)_D12-0WH-09484_4

02. P & ID for Deaerator & Pumping Ststion_D12-1WH-59879_3

03. Refractory for Boiler_R11-1WH-67044_0

DRAWINGS FOR BOILER NO. 1 ( PL 0501 )

04. G.A. of Boiler No.1_D11-0WH-09485_3

05. Pressure Part Assembly_D11-1WH-66536_1

06. Steam Drum_ P21-1WH-60701_0

07. Steam Drum Internals (Part I)_P21-1WH-60845_0

08. Steam Drum Internals (Part -II)_P21-1WH-60846_0

09. Steam Drum Internal Attachments_P21-1WH-60847_0

10. Detail of Superheater Coil 1A & 1B_PA1-1WH-59631_1

11. Detail of Superheater Coil II_PA2-1WH-59632_1

12. Assembly of Deaerator_W21-1WH-63955_1

DRAWINGS FOR BOILER NO. 2 ( PL 0502 )

13. General Arrangement of Boiler No..2_D11-0WH-09451_3

14..Pressure Part Assembly_D11-1WH-66537_1

15. Steam Drum_P21-1WH-61431_1

16. Steam Drum Internals (Part -I )_P21-1WH-61520_0

17. Steam Drum Internal (Part - II)_P21-1WH-61521_0

18. Detail of Superheater Coil IA & 1B_PA1-1WH-60871_1

19. Detail of Superheater Coil -II_PA2-1WH-60872_1


./O & M Manual.pdf.ditaLinks/01. P & ID for Waste Heat Boiler (Coke Oven Plant)_D12-0WH-09484_4.pdf

./O & M Manual.pdf.ditaLinks/02. P & ID for Deaerator & Pumping Ststion_D12-1WH-59879_3.pdf

./O & M Manual.pdf.ditaLinks/03. Refractory for Boiler_R11-1WH-67044_0.pdf

./O & M Manual.pdf.ditaLinks/04. G.A. of Boiler No.1_D11-0WH-09485_3.pdf

./O & M Manual.pdf.ditaLinks/05. Pressure Part Assembly_D11-1WH-66536_1.pdf

./O & M Manual.pdf.ditaLinks/06. Steam Drum_ P21-1WH-60701_0.pdf

./O & M Manual.pdf.ditaLinks/07. Steam Drum Internals (Part I)_P21-1WH-60845_0.pdf

./O & M Manual.pdf.ditaLinks/08. Steam Drum Internals (Part -II)_P21-1WH-60846_0.pdf

./O & M Manual.pdf.ditaLinks/09. Steam Drum Internal Attachments_P21-1WH-60847_0.pdf

./O & M Manual.pdf.ditaLinks/10. Detail of Superheater Coil 1A & 1B_PA1-1WH-59631_1.pdf

./O & M Manual.pdf.ditaLinks/11. Detail of Superheater Coil II_PA2-1WH-59632_1.pdf

./O & M Manual.pdf.ditaLinks/12. Assembly of Deaerator_W21-1WH-63955_1.pdf

./O & M Manual.pdf.ditaLinks/13. G.A. of Boiler No..2_D11-0WH-09451_3.pdf

./O & M Manual.pdf.ditaLinks/14.Pressure Part Assembly_D11-1WH-66537_1.pdf

./O & M Manual.pdf.ditaLinks/15. Steam Drum_P21-1WH-61431_1.pdf

./O & M Manual.pdf.ditaLinks/16. Steam Drum Internals (Part -I )_P21-1WH-61520_0.pdf

./O & M Manual.pdf.ditaLinks/17. Steam Drum Internal (Part - II)_P21-1WH-61521_0.pdf

./O & M Manual.pdf.ditaLinks/19. Detail of Superheater Coil -II_PA2-1WH-60872_1.pdf

./O & M Manual.pdf.ditaLinks/19. Detail of Superheater Coil -II_PA2-1WH-60872_1.pdf


Volume 3 — Drawings


♦ E & I SpeciÞcations



E & I Specifications

Section 01

Instruments Hook Up Diagram

Section 02

2.1 Control Schematic Diagram

2.2 Control Narration

Section 03

DCS Input Output List

Section 04

Soot Blower Input Output List

Section 05

Logic Diagram for Drives

Section 06

Electrical System Required For Motor Selection

Section 07

SpeciÞcation for MOV Valve Actuator

Section 08

8.1 Electrical Load List

8.2 Power & Control Cable Schedule

Section 09

SpeciÞcation for PLC Based SB Panel

Section 10

10.1 Electrical Motor Selection for ID Fan Motor

10.2 Electrical Motor Selection for BFW Pump Motor

Section 11

11.1 Instruments Cable Schedule for Boiler 1

11.2 Instruments Cable Schedule for Boiler 2

Section 12

12.1 SpeciÞcation for Transmitters & Analysers

12.2 SpeciÞcation for Gauges & Switches


./O & M Manual.pdf.ditaLinks/1 Inst Hook Up Diagram__D13-4WH-1382E.pdf

./O & M Manual.pdf.ditaLinks/2.1 Control Schematic Diagram_D13-4WH-1859E S-1 (1.pdf

./O & M Manual.pdf.ditaLinks/2.2 Control Narration_D13-WH-CS-37672.pdf

./O & M Manual.pdf.ditaLinks/3 DCS I O List_D13-WH-CS-37662.pdf

./O & M Manual.pdf.ditaLinks/4 SB IO List_D13-WH-CS-38503.pdf

./O & M Manual.pdf.ditaLinks/5 Logic Diagram for Drives_D14-4WH-15098.pdf

./O & M Manual.pdf.ditaLinks/6 EMS-1_D14-WH-CS-36937.pdf

./O & M Manual.pdf.ditaLinks/7 MOV & Actuator_D14-WH-CS-37070.pdf

./O & M Manual.pdf.ditaLinks/8.1 Electrical Load List_D14-WH-CS-39034.pdf

./O & M Manual.pdf.ditaLinks/8.2 Power & Control Cable Schedule_D14-WH-CS-38506.pdf

./O & M Manual.pdf.ditaLinks/9 PLC & Starter Panel for S B Operation_E12-WH-CS-38500.pdf

./O & M Manual.pdf.ditaLinks/10.1 EMS 2 ID Fan Motor_G35-WH-CS-38086.pdf

./O & M Manual.pdf.ditaLinks/10.2 EMS 2 BFW Pump_W44-WH-CS-37483.pdf

./O & M Manual.pdf.ditaLinks/11.1 Instruments Cable Schedule_I21-WH-CS-37165.pdf

./O & M Manual.pdf.ditaLinks/11.2 Inst Cable Schedule Blr 2_I21-WH-CS-37730.pdf

./O & M Manual.pdf.ditaLinks/12.1 Inst spec forTransmitter_I31-WH-CS-37698.pdf

./O & M Manual.pdf.ditaLinks/12.2 Inst Spec for Gauges & Switches_I32-WH-CS-37699.pdf


12.3 SpeciÞcation for Valves & Actuators

12.4 SpeciÞcation for Sensors

12.5 SpeciÞcation for Actuators

Section 13

13.1. ARC Valve SpeciÞcation

13.2. CBD Valve SpeciÞcation

13.3. EBD Valve SpeciÞcation

Section 14

14.1 Process Valve Schedule for Boiler 1

14.2 Process Valve Schedule for Boiler 2

Section 15

Soot Blower Panel wiring Diagram Expert Inst


./O & M Manual.pdf.ditaLinks/12.3 Inst Spec for COntrol valve_I33-WH-CS-37700.pdf

./O & M Manual.pdf.ditaLinks/12.4 Inst Spec for Sensors_I34-WH-CS-37701.pdf

./O & M Manual.pdf.ditaLinks/12.5 Inst Spec for Actuator_I35-WH-CS-38260.pdf

./O & M Manual.pdf.ditaLinks/13.1 ARC Valve Spec_W47-WH-CS-37932.pdf

./O & M Manual.pdf.ditaLinks/13.2 CBD Valve Scec_Z29-WH-CS-37517.pdf

./O & M Manual.pdf.ditaLinks/13.3 EBD Valve_Z29-WH-CS-37594.pdf

./O & M Manual.pdf.ditaLinks/14.1 Valve Schedule_Z22-WH-CS-37518.pdf

./O & M Manual.pdf.ditaLinks/14.2 Valve Schedule Blr 2_Z22-WH-CS-37764.pdf

./O & M Manual.pdf.ditaLinks/15 Panel Wiring Diagram_Expert.pdf


Volume 4 — Vendor Manuals


♦ Section 01♦ Section 02♦ Section 03♦ Section 04♦ Section 05♦ Section 06♦ Section 07♦ Section 08♦ Section 09♦ Section 10

Volume 4 � Vendor Manuals 103


Section 01

Pressure Transmitter — Emerson

O & M Manual

PRESSURE TRANSMITTERS (MODEL 3051)

Section 02

Temperature Transmitter — Emerson

O & M Manual

TEMPERATURE TRANSMITTERS (MODEL 644HA)

Section 03

Pressure Switch — Switzer Instruments

O & M Manual

Pressure Switch Manual

Section 04

4.1 Pressure Gauge — Gauges Bourdon

O & M Manual

Pressure Gauge Manual

4.2 Temperature Gauge — Goa Instruments

O & M Manual

Temperature Gauge Manual

Section 05

Power Cylinder — Keltron

O & M Manual

Damper Actuator - Keltron Manual

Section 06

Loop Power Indicator — Switzer Instruments

O & M Manual

Loop Power Indicator Manual Model (K5105 )

Section 07

I to P Converter — ABB

O & M Manual


./O & M Manual.pdf.ditaLinks/3051 press transmitters.pdf

./O & M Manual.pdf.ditaLinks/644H& 644R Smart Temp Transmitter-Emerson.pdf

./O & M Manual.pdf.ditaLinks/PRESSURE SWITCH - SWITZER.pdf

./O & M Manual.pdf.ditaLinks/Pressure Gauge new.pdf

./O & M Manual.pdf.ditaLinks/GOA.PDF

./O & M Manual.pdf.ditaLinks/Damper Actuator - Keltron.pdf

./O & M Manual.pdf.ditaLinks/IM-K-5105 DTS indicating controller_Loop Powered Indicator.pdf


I to P Converter � ABB_Manual

Section 08

8.1 Flow Nozzle — Starmech Controls

Manual for Flow Nozzle

Data Sheets of OriÞce Plate Boiler 1

Data Sheets of OriÞce Plate Boiler 2

8.2 Thermocouple — Thermal Instruments

Data Sheets

Section 09

Control Valves— MIL

O & M Manual

MIL 41000 HEAVY DUTY BALANCED CAGE GUIDED CONTROL VALVES - MANUAL

MIL 21000 HEAVY DUTY BALANCED CAGE GUIDED CONTROL VALVES - MANUAL

MIL 37 �38 SPRING DIAPHRAGM PNEUMATIC ACTUATOR - MANUAL

8013 Valve Positioner Manual

400 L Positional Transmitter

496 Rotary Electric Switch

776 Air Lock Valve

Solenoid Valve Rotex

Data Sheet & Drawings

Control Valve Data Sheets

Section 10

Motorised Valve Actuator— Auma India Ltd.

Manual

Actuator Manual

MOV G. A. Drawings


./O & M Manual.pdf.ditaLinks/TEIP 11 - ABB.pdf

./O & M Manual.pdf.ditaLinks/Inst Manual.pdf

./O & M Manual.pdf.ditaLinks/Flow Nozzle1.pdf

./O & M Manual.pdf.ditaLinks/Flow Nozzle2.pdf

./O & M Manual.pdf.ditaLinks/Thermocouple -TH drawing.pdf

./O & M Manual.pdf.ditaLinks/41000 HEAVY DUTY BALANCED CAGE GUIDED CONTROL VALVES - MIL.pdf

./O & M Manual.pdf.ditaLinks/21000 Original Guide.pdf

./O & M Manual.pdf.ditaLinks/37 38 6A.pdf

./O & M Manual.pdf.ditaLinks/8013 positionaer.pdf

./O & M Manual.pdf.ditaLinks/400 L Position Trans.pdf

./O & M Manual.pdf.ditaLinks/496_Orig.pdf

./O & M Manual.pdf.ditaLinks/776 Control Valves.pdf

./O & M Manual.pdf.ditaLinks/Ball Valve with Actuator.pdf

./O & M Manual.pdf.ditaLinks/CV data sheet for Bhatia.pdf

./O & M Manual.pdf.ditaLinks/Actuater SAI SARI 6 - 100.pdf

./O & M Manual.pdf.ditaLinks/MOV GAD.pdf




♦ Section 01♦ Section 02♦ Section 03♦ Section 04♦ Section 05



Section 01

ID Fan - Flakt Woods

O & M Manual

Fan - Flakt_Manual

Drawings

General Arrangement Drawing of ID Fan

Section 02

BFW Pump — KSB Pumps

O & M Manual

Cover Page

Index of Manual

HDA Manual

Technical Appendix Sheets

Pump Data Sheets

Proposed Performance Curve

Drawings

1. General Arrangement Drawing for Pump

2. Cross Section Drawing for Pump

3. List of Components

4. P&I Diagram for Pump

5. P&I Diagram Part List

Section 03

LP / H.P Dosing System - Metapow Industries

O & M Manual

Dosing System Manual

Drawings

L.P. Dosing System Drawing

H.P. Dosing System Drawing

Section 04

4.1 Long Retractable Soot Blower - R.R. Techno

O & M Manual

LR Soot Blower Manual

Drawings

1. General Arrangement Drawing for LRSB for Boiler 1


./O & M Manual.pdf.ditaLinks/HA Series Fan Manual.pdf

./O & M Manual.pdf.ditaLinks/ID Fan Drawings.pdf

./O & M Manual.pdf.ditaLinks/BFW Cover Page.pdf

./O & M Manual.pdf.ditaLinks/Index.pdf

./O & M Manual.pdf.ditaLinks/HDA Manual.pdf

./O & M Manual.pdf.ditaLinks/Thechnical Data.pdf

./O & M Manual.pdf.ditaLinks/Pump Data Sheets.pdf

./O & M Manual.pdf.ditaLinks/Performance Curve.pdf

./O & M Manual.pdf.ditaLinks/GA Drawing.pdf

./O & M Manual.pdf.ditaLinks/Sectional Drawing.pdf

./O & M Manual.pdf.ditaLinks/List of Component.pdf

./O & M Manual.pdf.ditaLinks/P & I Diagram.pdf

./O & M Manual.pdf.ditaLinks/PID Part List.pdf

./O & M Manual.pdf.ditaLinks/Metapow Dosing System Vk.pdf

./O & M Manual.pdf.ditaLinks/LP Dosing GAD 3.pdf

./O & M Manual.pdf.ditaLinks/HP Dosing GAD.pdf

./O & M Manual.pdf.ditaLinks/Long Retractable Soot Blower - R.R. TECHNO.pdf

./O & M Manual.pdf.ditaLinks/LR SB GAD LRSB_R2.pdf


4.2 Rotary Soot Blower - Sitson India Ltd.

O & M Manual

Rotary Soot Blower Manual

Drawings

1. General Arrangement Drawing for RSB for Boiler 1

2. General Arrangement Drawing for RSB for Boiler 2

Section 05

5.1 Motors— Siemens

Manual

Motor Manual

Data Sheets

Data Sheets for ID Fan Motor

Data Sheets for BFW Pump

5.2 ARC Valve — Schroedahl

Manual

ARC Valve Manual

Data Sheets

Data Sheets for ARC Valve


./O & M Manual.pdf.ditaLinks/Rotary Soot Blower.pdf

./O & M Manual.pdf.ditaLinks/GA Drawings RSB Sitson Boiler1.pdf

./O & M Manual.pdf.ditaLinks/GA Drawings RSB Sitson Blr 2.pdf

./O & M Manual.pdf.ditaLinks/1LA0_1PD0_1MA0 Superbreed Motors - Siemens.pdf

./O & M Manual.pdf.ditaLinks/Motor Data S Fan.pdf

./O & M Manual.pdf.ditaLinks/Motor Data S Pump.pdf

./O & M Manual.pdf.ditaLinks/TDM Series ARC Valve.pdf

./O & M Manual.pdf.ditaLinks/ARC Valve Datas.pdf




♦ Section 01♦ Section 02♦ Section 03♦ Section 04♦ Section 05♦ Section 06♦ Section 07♦ Section 08♦ Section 09♦ Section 10



Section 01

Safety Valve – Tyco Sanmar

O & M Manual

HCI Model Manual

Drawing & Data sheet

Safety Valve Datasheet

Safety Valve Drawing

Section 02

Safety Relief Valves — Tyco Sanmar

O & M Manual

SAFETY VALVES (JOS � JLT Manual)

Data Sheet & Drawings

SpeciÞcation Sheets

Drawings

Section 03

Drum Level Gauge — Hitech

O & M Manual

Drum Level Gauge Manual

Drawings & Datasheet

Drum Level Gauge Drawings

Section 04

Level Gauge (Tubular ) – Chemtrol

O & M Manual

Tubular Level Gauge Manual

Drawings

Tubular Level Gauge Drawing

Section 05

Reflex Level Gauge — Chemtrols

O & M Manual

Reßex Level Gauge � Chemtrols_Manual

Drawings & Datasheet

Reßex Level Gauge - Chemtrol_Drawing


./O & M Manual.pdf.ditaLinks/HCI.pdf

./O & M Manual.pdf.ditaLinks/SV Data Sheets.pdf

./O & M Manual.pdf.ditaLinks/SV GAD.pdf

./O & M Manual.pdf.ditaLinks/JOS-E Relief Valve.pdf

./O & M Manual.pdf.ditaLinks/SRV Data Sheets.pdf

./O & M Manual.pdf.ditaLinks/SRV GA Drgs.pdf

./O & M Manual.pdf.ditaLinks/IOM - Narvik DLG17 & 27 DUCO Gauge.pdf

./O & M Manual.pdf.ditaLinks/DLG drawings PL 0501-02.pdf

./O & M Manual.pdf.ditaLinks/Tubular level gauge.pdf

./O & M Manual.pdf.ditaLinks/Tubular LGG.pdf

./O & M Manual.pdf.ditaLinks/Reflex Level Gauge.pdf

./O & M Manual.pdf.ditaLinks/Reflex LGG.pdf


Section 06

Process Valve — KSB

O & M Manual

Process Valve Manual

Section 07

Process Valve — Xomox Sanmar

O & M Manual

Process Valve Manual

Section 08

Blow Down Valve — Levcon Instruments

O & M Manual

Blow Down Valve Manual

Section 09

9.1 Spring Hanger Support — Techno Industries

O & M Manual

Spring Hanger supports Manual

Support Drawing

9.2 Hanger Support – Pipe Support

O & M Manual

Hanger supports Manual

Support Drawing

Section 10

Damper - United Technomech Engineers Pvt. Ltd.

O & M Manual

Manual Guillotion Damper Manual

Pneumatic Guillotion Damper Manual

Pneumatic Operated Multilouvre Damper Manual

Drawings

Manual Guillotion Damper Drawing

Pneumatic Guillotion Damper Drawing

Pneumatic Operated Multilouvre Damper Drawing


./O & M Manual.pdf.ditaLinks/Process Valve KSB.pdf

./O & M Manual.pdf.ditaLinks/Xomox Process Valves.pdf

./O & M Manual.pdf.ditaLinks/parallel slide Blow Down Valve-levcon pvt ltd.pdf

./O & M Manual.pdf.ditaLinks/Veriable Support - Techno Indust.pdf

./O & M Manual.pdf.ditaLinks/Spring Hanger Techno.pdf

./O & M Manual.pdf.ditaLinks/Spring Support manual- Pipe Support.pdf

./O & M Manual.pdf.ditaLinks/Pipe Support Data S.pdf

./O & M Manual.pdf.ditaLinks/Manual Guillotion Damper Manual.pdf

./O & M Manual.pdf.ditaLinks/Pneumatic Guillotion Damper Manual.pdf

./O & M Manual.pdf.ditaLinks/Pneumatic Operated Multilouvre Damper Manual.pdf

./O & M Manual.pdf.ditaLinks/Manual Guillotion Damper Drawings.pdf

./O & M Manual.pdf.ditaLinks/Pneumatic Guillotion Damper Drawings.pdf

./O & M Manual.pdf.ditaLinks/Pneumatic Operated Multilouvre Damper Drawings.pdf




Index

100% Feed Controller ................................... 19

AAir Vent ........................................................ 22Alarms and Interlocks ................................... 49Alarms And Interlocks ................................... 35Annual Maintenance Check Sheet ................. 62Attemperator .............................................7, 23Automatic Control ......................................... 35

BBlow Down Tank............................................. 7Boiler Annual Maintenance andOverhaul .................................................... 67Boiler Blowdown System............................... 25Boiler Feed Pump......................................... 10Boiler Feed Water Pumps ............................. 18Boiler Lay Up Procedures.............................. 75Boiler Preservation Procedure ....................... 71Boiler Pressure Part Description .................... 19Boiler Protection & Interlock .......................... 35Boiler Shutdown ........................................... 42Boiler Start Up.............................................. 40

CChecks Every Six Months.............................. 61Checks Every Year ....................................... 61Chemical Dosing & Sampling System ............ 27Chemicals for Dosing...................................... 9Cold Start Up Procedure ............................... 40Component Description................................. 16Conditioned Based Maintenance ................... 57Continuous Blow Down Control ..................... 26Cooling of Shutdown WHRB & ItsPreservation ............................................... 44Cooling Water................................................. 8

DDaily Checks ................................................ 57Daily Maintenance ........................................ 60Deaerator..................................................9, 16Deaerator Steam ............................................ 8Dissolved Gases .......................................... 94Dissolved Salts and Minerals......................... 93DM Water....................................................... 8Do�s and Dont�s ............................................ 44Drum Inspection ........................................... 67Drum Level Control....................................... 21Drum Safety Valve ........................................ 21

Dry Storage Preservation .............................. 71During Black - Out Procedure Condition ......... 43

EEconomiser .................................................... 6Economizer .................................................. 19Effects of Impurities ...................................... 94Electrical power .............................................. 7Emergency Procedures................................. 48Emergency Shutdown Procedure................... 43EMR Valve ................................................... 12Evaporator ................................................... 22Evaporator / Convection Bank Tubes ............... 6Expansion Joints .......................................... 68

FFailure Reporting Formats............................. 78Feed & Boiler Water Conditioning .................. 68Feed Water Control Station ........................... 19Feed Water Supply ....................................... 38Filling With Water.......................................... 39Flue Gas Data ................................................ 2Flue gas Pressure drop proÞle: (for designcase)............................................................ 4Flue Gas System .......................................... 31Flue gas Temperature proÞle : ( For Designcase)............................................................ 3Flue gas Velocity proÞle: (for design case) ......... 3Forced Cooling ............................................. 44Furnace and Boiler Tubes ............................. 81

GGauge Glass ........................................... 11, 13General Principle Of Weld Repairs................. 81

HHigh Water Level .......................................... 48Hot Startup Procedure .................................. 42HP Dosing System........................................ 27HP/LP Dosing System..................................... 9

IID Fans.......................................................... 9Inspection after Cooling ................................ 67Inspection of Screen, Primary & SecondarySuperheaters, Evaporators I/II &Economiser ................................................ 68Instrument Air................................................. 8

113


Insulation ....................................................... 7Insulation and Cladding................................. 68

LLow Water Level........................................... 48

MMain Steam Piping........................................ 24Maintaining Quality of Steam......................... 30Mixing Tank .................................................. 27MOC And SpeciÞcation of Euqipments............. 4Monthly Checks............................................ 60

NNatural Cooling............................................. 44Normal Shutdown Procedure......................... 42

OOperation and Control................................... 33Operation Procedure..................................... 38Operational Control............................ 24, 31�32Operator Action Required during BoilerCold Start up .............................................. 43Other Drains................................................. 26Other Equipment .......................................... 68Other Materials............................................. 94

PParalleling WHRB To The Plant steamMains ......................................................... 43pH Value of theWater and its Importance......... 94Phosphate Dosing Pump............................... 27Planning Before Overhaul ............................. 67Plugging Tubes in Drums & Headers.............. 82Pre-requisites to Be Attended Before Startup: ............................................................. 38Preparation of 5% Phosphate Solution inthe tank ...................................................... 27Preservation of Instruments........................... 75Preservation of Rotating Equipments ............. 75Preventive Maintenance................................ 56Preventive Maintenance Program forSpares ....................................................... 57Preventive Maintenance Program forValve.......................................................... 57

RRecommended Maintenance Practices .......... 56Removing Tubes from Drums, Headers &Tube Plates ................................................ 84

Replacement of Tube Section........................ 84

SSafety In WHRB House................................. 55Safety Relief Valve........................................ 12Safety Valve ..................................................11Section Overview.....................................38, 56Shutdown and Cooling the Boiler ................... 67Silencer ....................................................... 22Soot Blower.............................................10, 32Soot Blower System ..................................... 32SOOT BLOWING SEQUENCE...................... 34Steam and Water System TechnicalPerformance Data....................................... 25Steam Drum..............................................4, 20Steam Supply............................................... 32Steam Temperature Control Loop .................. 23Super Heater................................................ 23Super Heater I .............................................. 23Super Heater II ............................................. 23Superheater IA / IB / Support Coils .................. 5Superheater- II ............................................... 4System Description............................ 31�32, 44

TTECHNICAL SPECIFICATIONS ...................... 3Tube Failure ................................................. 48Tube Failures ............................................... 76Tube Thickness Survey................................. 75Tube Thickness Survey Data Collection �Format ....................................................... 78

UUndissolved and Suspended SolidMaterials .................................................... 93Utilities........................................................... 7

VValve Settings:.............................................. 38

WWater / Steam Temperature proÞle: (ForDesign case) ................................................ 3Water And Steam Quality Control AndMonitoring .................................................. 29Water And Steam System ............................. 16Water Chemistry........................................... 93Water Quality Recommendations................... 54Weld Repair Of Small Cracks in Tube ............ 82Welding Procedure SpeciÞcations(WPS) ........................................................ 80

114


Wet Storage Preservation ............................. 72WHRB Log Sheet ......................................... 46

Window Patch Welding ................................. 80

115

Documents

O & M Manual