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High Efficient Cogeneration in Seshasayee Paper -Erode
Dr T.G.Sundara Raman
Seshasayee Paper and Boards Ltd.
National Workshop for
Promoting Industrial Energy Efficiency
KEP/BEE New Delhi
8th Nov. 2016
WHAT IS
COGENERATION
Grid Power Generation Station Power Consumption
T&D Losses
Net Power from TPS
Net Power Avail at Plant
Net Power for Process Req.
Power Generation in HP Cogen
APC @ Cogen
HP Steam Generation Co-Gen
Plant
ASC Net Steam to Process
Power Borrowed from Grid to Cogen Process
CHP needs +Surplus Power for Export
Power for
Export
SPECIFICATIONS OF THE 2 HP COGEN UNITS
CPP Chemical Recovery Cogen
Boiler #10 Parameter Boiler #11
AFBC Boiler Type Chemical Recovery Boiler
117 TPH
ECR : 106 TPH
Rated Steam
Evaporation
95TPH(Phase1*)
140TPH(Phase2)
106 kg/cm² SOP 65 kg/cm²
510˚C SOT 465˚C
135˚C Feed inlet temperature 135˚C
Imported coal
Fuel
Black liquor
@ 70% solids concn.
21 MW- DEC STG 16 MW- EBP
10.5/4.0 kg/cm² E1/E2 10.5/4.5 kg/cm²
0.09 ata Condensing --
20.4 MW Capacity 11 MW(Phase1*) /
16 MW(Phase2)
5
E2
E1 E1
E2
BLR#10 VHP BLR#11
HP
P2 P1
21 MW
DEC
16 MW
EBP
LP LP
MP
STEAM & POWER OPTIMISATION WITH
2 HP COGEN BATTERY ON LINE
Atmospheric Fluidised Bed Combustion High Pressure Boiler [#10]
[Babcock UK] -Original Design
• Bubbling Fluidised Bed Combustion Boiler with economizer & air-heater at back-end
• High pressure (106 ksc) unit
• 510ºC Steam Temperature
• No in-bed Superheater
• Rifle bore Studded Bed Coils
• Under-Bed Feeding
• 135ºC Feed water Temperature
• Enviro-Coal (Low S & Ash content)
• High Thermal Efficiency ( > 80 % )
Rifle bore bed
coil tube
INNOVATIVE PROJECT - 1
Conversion of Bubbling to Spouted AFBC HP Boiler with increased bed heating
surface for enhanced High Pressure Steam & Power generation
Date of Commencement : 05.03.15 Date of Completion : 26.04.15
Investment : Rs 10 Crores Monetary savings : Rs 11.94 Crores
Increasing bed coil heating surface accommodated within the existing
furnace area, thereby increasing steam generation in HP Boiler
8
BEFORE RETROFIT – SINGLE
HEADER SINGLE BED COIL
DESIGN
DECK PLATE / BOTTOM
WATER WALL DECK PLATE
AFTER RETROFIT – DOUBLE
HEADER DOUBLE BED COIL
DESIGN
Imported Coal
A.Proximate Analysis
Constituent Unit As Fired
Moisture % 20
Ash % 4.3
Volatile Matter % 35-36
Fixed Carbon % 40-41
GCV kcal/kg 5410
B. Elemental Analysis
Carbon
:
48.7 %
Hydrogen : 5.3 %
Nitrogen : 1.0 %
Sulphur : 0.5 %
Oxygen : 20.2 %
Halogens : Traces
Heavy Metals : BDL
High Combustion efficiency : >99%
Design
• LOI [Design] : ~15%
• UBC Loss : 1.1 %
____________________________________
Actual
• LOI : 9 to 10%
• UBC Loss : 0.6- 0.7%
• CO in flue gas : Traces
• Combustion effy : > 99 %
Action Initiated
• Stoppage of PA Fan
• Fuel Nozzles thoroughly cleaned during the last shut
• Bed material topped up with fresh material when required.
Steam Cost Reduction through Switch from Low to High Grade Coal
in Upgraded Boiler # 10
Parameter Units Earlier Present Remarks
Low GCV High GCV Switch to higher
grade coal
GCV ( arb) Kcal/kg 4730 5400 As received basis
TM % 27 19-20 Total Moisture
Landed Cost Rs/te 5000 4850 Imported Coal
Efficiency % 78 83 Boiler thermal η
Steam Evapn. t/t 5.4 6.6 Fuel based
Net Steam to fuel t/t 5.2 6.35 Incl transf & carpet
losses
Spec Energy Consn
redn.
% Basis 4-5% Impact on PAT
Increase in Steam generation : 80 to 105 TPH
Increase in Power generation through 21MW STG :
13.5 to 19 MW
Station Power consumption reduction : 7000 units/day
Power Export : 3 to 4 MW (Commencement from Nov 2015)
Grid Power Import drastically reduced
Additional LP Steam for Process : Ensured
12
Boiler 10 upgradation
Impact on overall Operational Results & Analysis
INNOVATIVE PROJECT - 2
Coal fired Boiler 10 - Station Power consumption reduction by
integrating Energy Efficient Boiler feed Pump with Low
Differential Pressure Control Valve.
Date of Commencement : Aug 2015 Date of Completion : Oct 2015
Investment : Rs 2 Lakhs Monetary savings : Rs 32 Lakhs
Prelude : High pressure drop across the control valve of Boiler Feed pump had
triggered the design of a control valve with lower differential Pressure so as to
retain the existing energy efficient Boiler feed pump.
Benefits achieved :
• Station power consumption reduction : 5000 KWh /day
• Net power available for export : 0.2 MW
• Annual GHGE reduction : 2000 tCO2e (2015-16)
Why it is innovative: Energy efficient Boiler Feed Pump integrated with specially
designed control valve with lower differential pressure to effect station power
consumption reduction - first of its kind in Manufacturing Industry .
Replication potential: Can be replicated by all industries for their
boiler feed pumps.
13
Advanced Energy Conservation Scheme
BFP for H.P. Steam Generator [Boiler 10]
Efficiency [%] of BFP in Operation
40
50
60
70
80
70 84 98 112 126 140
LargeBFP EFBFP
Feed Water Flow to Boiler 10 [ TPH]
BF
P E
ffic
iency [
%]
DP across EFBFP Control valves –Boiler 10
0
10
20
30
40
70 82 94 106 117
CV original CV LowDP
Feed Water Flow to Boiler 10 [ TPH]
DP
across B
FP
CV
[b
ar]
Energy Saving : 1000 units/day Energy Saving : 4500 units/day
Boiler
Steam
Rate
TPH
Efficiency
%
Power
Consumption
Power
Savings
%
Daily
Power
Savings
in Units
Standby
BFP 105 55-60 20600 Basis Basis
EE BFP + Low DP CV 105 70 15200 25 5400
Energy Efficient BFP with Low DP Control Valve to suit
Innovative Project
Power Management – Boiler Feed Pump
.
Process condensate polishing
Waste heat recovery through PHE
Condensate polishing resin bed
ACF MB
ST
FWT
Process Hot /
Condensate Tank
Filter
Polished
Condensate
To Deaerators
PHEs Hot
Fluid
Process Condensate : 90°C to 40°C
DM Water Preheating : from 32°C
Heat Recovery : 4 MWt
CPU+ HRU - INTEGRATED WATER &
ENERGY MANAGEMENT -BOILERS
Higher Cycle efficiency of STG relating to increased Power
generation
Increased Condensing loading resulting in lowered Specific
Steam Consumption
Marginal increase in Generator efficiency due to increase in
Power Generation
Maintaining rated Main steam temperature of ~ 505 °C
18
Impact on Enhanced performance of DEC STG
– Boiler #10 upgradation
CPP- Power Generation Enhancement
Increase in Gross Cycle efficiency
Successful Implementation of
Innovative schemes , had resulted in :
Net Power generation enhancement -through:
1. Minimize Exhaust steam Dryness Fraction
2. Maximize Condenser Vacuum
3. Generator efficiency enhancement
4. Minimizing/Non-operation of inefficient MP Boiler(s)
5. Reduction in Station Power Consumption through High
Energy Efficiency BFP with low DP Control Valve in place
21 MW 16 MW
Type Double Extraction cum
Condensing
Extraction cum Back
Pressure
Design 97.6 % 97.7 %
Actual 97.9 % 98.1 %
[Industry Record]
Gain 0.07 MW 0.06 MW 23
High Generator Efficiency
21 MW, 16 MW Steam Turbo-Generators
13.6
11.7
10.5
11
11.5
12
12.5
13
13.5
14
2014-15 2015-16
Cogen Station Power Consumption[%] S
PC
[%
]
INNOVATIVE PROJECT - 3
DM water switch related to heat recovery from Turbo-generator winding heat dissipation for increased Cycle efficiency
Date of Commencement : Jan 2016 Demonstration done : Aug 2016
Investment : Re 1 Lakh Monetary savings :Rs 20 Lakhs
Proposal : DM water instead of cooling tower water is supplied to generator air cooler
and is returned to the De-aerator at a higher temperature thereby reducing LP steam.
25
STEAM
TURBINE
G
COOLING TOWER
WATER IN
COOLING TOWER
WATER OUT
GENERATOR AIR COOLER
STEAM
TURBINE
DM
WATER IN
DM
WATER OUT
G
GENERATOR AIR COOLER
EXISTING MODIFIED
INNOVATIVE PROJECT - 3
BACKGROUND : Energy wasted through the cooling tower and the fouling of generator tubes triggered the scheme development.
BENEFITS ESTIMATED:
• De-aerator LP steam consumption reduction by 12 TPD
• Annual GHG emission reduction – 1100 tCO2e
• Fouling of generator air cooler tubes is avoided
• Enhanced winding temperature reduction.
REPLICATION POTENTIAL :
• Steam turbines with condensing units related to Cogeneration can take advantage of the scheme through implementation .
• Concept can be suitably modified for Thermal Power plants by utilizing turbine condensate instead of DM water.
26
RECOVERY COGEN ENERGY
DISTRIBUTION
.
Boiler
MSL
APH
EBP
Turbine P
LP Steam
for Process
PRDS
Fuel-
Input Energy
Deaerator
BFP
Evaporator
MP Steam
for Process
APH
Recausticizing
Fuel Heating
Innovation related to Low Carbon Economy
Maximizing Green Power generation in
Recovery Cogen through:
• Minimal/No extraction & maximizing Exhaust
LP flow in 16 MW STG
• Maximizing steam inlet temperature through
operating the Recovery Boiler at high SOT &
effecting reduction in steam temperature loss
through highly effective advanced state of
the art insulation of Main steam pipe-line
16 MW STG : Energy Management
Maximizing E2 steam with E1 minimal
------------------------------------------------------------
•Power gen. increase …. : 0.4 MW
•Addl. power gen. through
increase in flow of E2 ... : 0.05 MW
•Addl Green power gen. : 0.45 MW
•REC ………… : 300 units/month
•GHGE reduction : 1800 tCO2/yr
Waste to Power
Advanced Boiler Main steam
pipeline reinsulation- online
------------------------------------------------------------------------------
Replacement of existing insulation
with fresh insulation mattress of
higher thickness [210mm]& density
[140kg/m3] ; Advanced cladding pin
design
Steam temperature drop redn. from
10/12°C to 5/6 °C.
Radn & convecn heat loss redn.
Enthalpy gain in 16MW STG: 3kcal/kg
Addl. Power genern : 0.3 MW
GHGE Reduction : 2400 tCO2/ yr
Increased Feed Water inlet temperature
from 136 to 141° C to Economiser
Power gen. increase …. : 0.06 MW
Green Power enhancement:0.5 MU/yr
REC ………… : 40 units/month
•GHGE reduction : 250 t CO2e / yr
31
Recovery HP Cogen : Energy Management
Increased Feed water inlet temperature to Boiler :Case Study
Conclusions
Energy Efficiency Gains through Modified Boiler Design
• Quantum increase in HP Boiler Steam generation at rated steam temperature
• Overall Heat rate of Boiler House [CPP] efficiency enhancement with high steam economy-Steam loading reduced on inefficient MP Boilers
• Consequent increase in turbine steam loading had resulted in high cycle efficiency
• Surplus Power available for Grid Export [ ~3MW ]
• Availability of Boiler 10 with 21 MW STG : high at >98%
• GHG Emission reduction of over 35000 tCO2 /annum
Leveraging Aux. Steam Consumption Process condensate
polishing with HRU
Reduced DM water
consumption and lowered
Deaerator steam consumption
Higher feed water temperature Increase in Steam economy
High Feed water quality Low Blow-down ;
Pressure part healthiness
Combustion intake air reducting
planned
LP steam consumption lowered
LEVEREGING ELECTRICAL POWER IN HP COGEN
• Set Steam Inlet Temperature to Turbine at
Design Maximum
5 to 10 kwh/t
• Low Enthalpy Drop through economic sizing
and heavy insulation of main steam line
5 to 10 kwh/t
• High Energy Efficient Boiler Feed Pumps
integrated with Low DP Control Valves
7000 units/day
• Increase in Steam Generation with Boiler
Water Temp. at 141°C (instead of 105°C)
+30 kwh/t
• High Efficiency Turbine (With lower exhaust
steam dryness) for DEC Steam Turbine
30 to 50 kwh/t
• Identifying & Changing from MP to LP Steam
(Steam Switch) for Process needs
To Suit
Cleaner Environment Facets
Low S ( < 0.4 %)in coal SOx emission low
Low Ash ( 3 to 4 %) in coal Bottom/Fly-ash handling
minimal
High efficiency 3 field ESP Low SPM & RPM in stack gas
< 30 mg/Nm³
Imported coal with high
GCV
Particulates, SO2 & NOX
quantity discharged : Low
GHG Annual Emission
Reduction
42000 tCO2e
For further enquiry please contact:
Dr T.G.Sundara Raman
Mob. No,: 9443340731
email : [email protected]
36
Thank You