Pump final

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Pumps & Pumping Pumps & Pumping SystemsSystems

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PUMP

Pumping System Types of Pump Design Calculations

Introduction

Bernoulli’s Theorem

Characteristic Curves

Cavitation

Centrifugal

Positive Displacement

Gear

Vane

Pump Efficiency

NPSH, NPSHa, NPSHr

Reciprocating

Rotary

Screw

Lobe

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IntroductionIntroduction

Objective of pumping system

(US DOE, 2001)

Pump is a device which converts mechanical energy into pressure energy due to which the fluid moves from one point to another.

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Pumps – Bernoulli’s Theorem

• Pressure head: measure of fluid’s mech. PE• Velocity head: measure of fluid’s mech. KE• Friction head: measure of energy lost that

heats fluid

Z1 + P1/ + V12/2g = Z2 + P2/ + V2

2/2g + [(U2 – U1) – W – Q]

q + wshaft = (h2 – h1) + (v22 – v1

2)/2 + g(z2 –z1)

Z/z: fluid height; P: fluid pressure; : fluid density

V/v: fluid velocity U: internal energy W/w: work

Q/q: heat transferred h: enthalpy g: grav. acceleration

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PUMP CHARACTERISTICS :- It is the relationship between Capacity, Head, Power and Efficiency.- The graphs, showing the inter-relationship between Capacity, Head, Power and Efficiency, are called Pump Characteristic Curves.

Capacity :- It is the quantity of fluid flowing through the Pump for a

given time of period.- It is expressed in m3/hr.- It is measured by weight method, volumetric method, orifice plate or by weirs.

Head :- It is the measure of energy to move the fluid from one point to another.- It is expressed in metres of liquid column.

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SYSTEM HEAD :

- It is the total head of a system against which a pump must operate.

- For a given capacity, it is expressed as

System Head = Total Static Head from supplying level to discharge level + Discharge Pressure - Suction Pressure - Friction losses - entrance and exit losses

Head (in feet) = Pressure (psi) X 2.31 Specific gravity

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Total Static Head

Total static head = static discharge head + static suction lift

Total static head = static discharge head – static suction head

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Head vs. Pressure - continued

Lighter than water like oil Sp. Gr. = 0.85Heavier than water like brine Sp. Gr. = 1.15For most cases water Sp. Gr. = 1.0

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Power :

- The horse power produced by the liquid is called as Water Horse Power (WHP) or Liquid Horse Power which is expressed as

WHP = ( Q H) / 75

where Q = m3/sec , H = mlc & = kg/m3

- The power required to drive the pump is called as Brake Horse Power (BHP) which is expressed as

BHP = ( Q H) / 75 where is the efficiency of Pump.

Efficiency :

- It is the measure of the Pump performance.

- It is the ratio of WHP to BHP.

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• Pump shaft power (Ps) is actual horsepower delivered to the pump shaft

• Pump output/Hydraulic/Water horsepower (Hp) is the liquid horsepower delivered by the pump

Calculation of Pump Performance

Hydraulic power (Hp):Hp = Q (m3/s) x Total head, hd - hs (m) x ρ (kg/m3) x g (m/s2) / 1000

Pump shaft power (Ps):Ps = Hydraulic power Hp / pump efficiency ηPump

Pump Efficiency (ηPump): ηPump = Hydraulic Power / Pump Shaft Power

hd - discharge head hs – suction head, ρ - density of the fluid g – acceleration due to gravity

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CHARACTERISTIC CURVE OF A PUMP

1000

1200

1400

1600

1800

HE

AD

(m

lc)

0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450SU C TIO N FLO W (cub. m . / h r.)

0

10

20

30

40

50

60

70

80

90

EF

FIC

IEN

CY

(%

)

0

5

10

15

20

NP

SH

R (

mlc

)

500

1000

1500

2000

PO

WE

R (

kW)

50 Hz52.5 Hz

47.5 Hz

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Pump operating point

• Duty point: rate of flow at certain head

• Pump operating point: intersection of pump curve and system curve

Flow

Head

Static head

Pump performance curve

System curve

Pump operating point

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Pumping System

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Pump suction performance (NPSH)

• Cavitation or vaporization: bubbles inside pump

• If vapor bubbles collapse

• Erosion of vane surfaces

• Increased noise and vibration

• Choking of impeller passages

• Net Positive Suction Head

• NPSH Available: how much pump suction exceeds liquid vapor pressure

• NPSH Required: pump suction needed to avoid cavitation

NPSHA > NPSHR

Otherwise pump will cavitate.

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NPSHA _ net positive suction head (available)

g

phZ

g

pNPSH v

fiia

A ..

Temp°F

Vapor press. P.S.I.A

212 14.7

210 14.1

208 13.7

206 13.0

204 12.5

202 12.0

200 11.5

190 9.3

160 4.7

120 1.7

80 0.5

40 0.1

Pa - atmospheric or reservoir pressure

Zi - height from water level to pump inlet

Pv - vapor pressure of the fluid

hfi - friction losses on the suction side

g

phZ

g

pNPSH v

fiia

A ..

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NPSHA

NPSHA = 2.31 (PA-PV) + (HE-HF)

SP.GR.

= 2.31 (14.7-0.69) + (10-1.5)

0.99

= 32.7 + 10 –1.5

= 41.2 ft NPSHA

vent

Water at 90°F SP.GR. = .99 PV = 0.69 psia

Friction loss in suction line HF = 1 ½ ft.

Atmospheric pressure (PA) = 14.7 psia

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NPSHA

Water at 90°F Sp. Gr. = 0.99 PV = 0.69 psia

Friction loss in suction pipe with strainer and gate valve HF = 1½ ft.

Atmospheric pressure (PA) = 14.7 psia StrainerGate Value

Foot value

In selection the pump it would be necessary to see that the NPSHR required did not exceed 13 to 14 ft at the duty point, otherwise noise and cavitation would occur at the pump

A

FEVA

A

NPSHft 15.2

17.5-32.7

)5.2(-150.99

0.69)2.31(14.7

)H(HSp.Gr.

)P2.31(PNPSH

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System Head Curve

For Example 550 G.P.M. the pump head as selected from the system head curve will be 98 ft. T.D.H.

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• Very destructive phenomena that occurs when the pressure of the fluid

drops below vaporization point. The result is the formation of tiny bubles that colapses when pressure increase on the impeller. Those implosions work as small “explosions” on the impeller that will destroy it.

• It’ll happen mainly for 3 reasons: Bad system design. Clogging of pre-filters. Valves closed on the suction side.

• Cavitation is audible in the form of high pitch screeching.

CAVITATION

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Pumps

Centrifugal Pump Positive Displacement Pump

Reciprocating Pump Rotary Pump

Rotary Vane ScrewGear

Types of Pumps

Lobe

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Positive Displacement Pump

• Reciprocating pump– Displacement by reciprocation of piston plunger

– Used only for viscous fluids and oil wells

• Rotary pump– Displacement by rotary action of gear, cam or vanes

– Several sub-types

– Used for special services in industry

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Reciprocating Pump

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Gear Pump

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External Gear Pump

1.Liquid flows into the cavity and is trapped by the gear teethas they rotate.2. Liquid travels around the interior of the casing in the pocketsbetween the teeth and the casing3. Finally, gears forces liquid through the outlet port under pressure.

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Internal Gear Pump1. Liquid enters the suction portbetween the rotor and idler teeth.2. Liquid travels between the teeth ofthe "gear-within-a-gear" principle.The crescent shape divides theliquid and acts as a seal betweenthe suction and discharge ports.3. forcing the liquid out of thedischarge port.4. Rotor and idler teeth meshcompletely to form a sealequidistant from the discharge andsuction ports. This seal forces theliquid out of the discharge port.

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Lobe Pump

1. Liquid flows into the cavityand is trapped by the lobes as they rotate.2. Liquid travels around theinterior of the casing in thepockets between the lobes and the casing3. Finally, the lobes forces liquidthrough the outlet port under pressure.

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Screw Pump

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VANE PUMP1. As the impeller rotates and fluid enters the pump, centrifugal force, hydraulicpressure, and/or pushrods push the vanes to the walls of the housing.2. The housing and cam force fluid into the pumping chamber through holes in the cam. Fluid enters the pockets created by the vanes, rotor, cam, and sideplate.3. The vanes sweep the fluid to the opposite side of the crescent where it is squeezed through discharge holes ofthe cam as the vane approaches the point of the crescent. Fluid then exits the discharge port

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• Centrifugal pumps are the most widely used pump

• Centrifugal pumps depend on centrifugal forces

• The advantages of the centrifugal pump are its simple construction and operation, space requirements and rotary action.

Centrifugal Pump

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Centrifugal Pump

• Liquid forced into impeller

• Vanes pass kinetic energy to liquid: liquid rotates and leaves impeller

• Volute casing converts kinetic energy into pressure energy

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Centrifugal Pump

Rotating and stationary components

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Centrifugal Pump

Impeller

• Main rotating part that provides centrifugal acceleration to the fluid

• Number of impellers = number of pump stages

• Impeller classification: direction of flow, suction type and shape/mechanical construction

Shaft

• Transfers torque from motor to impeller during pump start up and operation

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Centrifugal Pump

Casings

• Functions• Enclose impeller as “pressure vessel”

• Support and bearing for shaft and impeller

• Volute case• Impellers inside casings

• Balances hydraulic pressure on pump shaft

• Circular casing• Vanes surrounds impeller

• Used for multi-stage pumps

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AFFINITY LAWS :

- All Centrifugal Pumps follow the Affinity Laws which are given below :

Q N Q D

H N2 and H D2

P N3 P D3

where N is the Speed of the Pump (rpm) &

D is the Diameter of the Impeller

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Major pumps in a power station :-

BOILER FEED PUMPS BOILER FEED BOOSTER PUMPS CONDENSATE EXTRACTION PUMPS CIRCULATING WATER PUMPS AUX COOLING WATER PUMPS

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Function of Pumps in a thermal power station

BFPs are used to feed water from deaerator feed storage tank to the boiler

Booster pumps are provided ahead of BFPs to ensure adequate NPSH to BFP for its cavitation free performance

CEPs are used to transfer condensate from condenser hotwell to deaerator

CWPs are used to circulate cooling water through condenser for condensing steam and ACWPs to supply cooling water to various auxiliary coolers

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BOILER FEED PUMP

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BFP BARREL & CARTRIDGE

Barrel

Cartridge

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BOILER FEED PUMP

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Boiler Feed BOOSTER PUMP

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BOOSTER PUMP

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CONDENSATE EXTRACTION PUMP

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CIRCULATING WATER PUMP

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CIRCULATING WATER PUMPS

DRY WELL WET WELL

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DESIGN OPTIONS FOR CWPs

Wet well / Dry well Pull out / Non pull out Single / Double foundation With / Without thrust block at discharge elbow With / Without non reversible ratchet With/ Without shaft inclosing tube

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SUMP MODEL STUDIES

Improper sump design results in :

Vortex formation, swirl and poor flow distribution Loss of hydraulic performance Noise and vibration Accelerated wear of components Mechanical failures

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Multiple CW Pumps installations

Sump Dimensions - Plan view

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Sump Dimensions- Elevation view

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Sump Dimensions versus Flow

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RECOMMENDED NOT RECOMMENDED

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Turbine Auxiliaries (~30% of total power consumption)

CEP, BFP and TG integral auxiliaries like vacuum pump, GSC exhauster, oil purifier, oil vapour exhauster etc.

Power consumption for TG Auxiliaries for 500 MW shall be ~4% of total power consumption with TD BFP’s in operation

Boiler Auxiliaries (~30% of total power consumption)

Mills, ESP, ID / FD / PA fans and LT drives

Boiler Circulating Water Pumps for 500 MW unit

CLASSIFICATION OF AUXILIARIES

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CLASSIFICATION OF AUXILIARIES (contd..)

Plant auxiliaries (~ 40% of aux. power )

• CW, ACW, DMCW & Plant Water System • DM plant & pre-treatment plant• HP/ LP dosing & chlorination plant• Hydrogen generation plant• Coal and Ash handling plant• Compressed air system• Air conditioning & ventilation system• Fuel oil system / Electric tracing • Electrical system: GT, UAT, ST losses & lighting load

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Auxiliary power consumption along with heat rate are the two important technical parameters used by the power utilities to assess the performance of power plants

AUXILIARY POWER

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AUXILIARY POWER (contd..)

Auxiliary power consumption can be defined as “the difference between gross electric power generated at generator terminals and net exportable power to grid

Power plant itself consumes nearly 8 – 10% of energy generated

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Optimisation Areas in Pumps

Sizing and design margins

Mechanical design

Materials of construction

Quality / Inspection checks

Performance testing

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OPTIMISATION OF AUXILIARY POWER

Aux. power can be brought down by proper sizing of pumps, selection of technology and equipments

The following factors having impact on auxiliary power consumption need to be considered during design stage of the project:

• Optimisation of sizing & design margins

• Proper selection of equipments

• Layout options

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Optimisation of sizing & design margins

Design margins are provided on equipment / systems to cater for ageing, wear & tear, uncertainties etc

Conservative designs with large margins ( e.g. on flow and head of pumps) and specifying suitability for abnormal operating conditions result in lower efficiency and higher auxiliary power consumption

Proper standby philosophy based on efficiency of operation, availability & reliability, like

1x100% Working + 1x100% Standby or

1x100% Working + 1x30% Startup or

2x50% Working + 1x50% Standby etc.

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OPTIMUM DESIGN MARGINS COMPARISON OF 500 MW CEP PARAMETERS

Vindhyachal Stage-II *

Simhadri

Capacity (M3/Hr) 835 800

Head (MLC) 350 275Power at Pump Input (KW) 971 731Efficiency (%) 81 81

Capacity (M3/Hr) 617 615

Power at Pump Input (KW) 840 628Efficiency (%) 79.5 80

Parameters CEP

Design Parameters

Parameters at 100% Load

* FOR VINDHYACHAL CEP PARAMETERS WERE WORKED OUT BY NTPC

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CEP SIZING CRITERIA (Typical)

A. Flow calculations

Description Unit Max. flow

NormalFlow

Under frq Turbine Bypass

1 Temperature of the condensate 0C 40.00 45.00 40.00 40.00

2 Density of water kg/m3 992.16 990.20 992.16 992.16

3 Condensate flow (HRSG with 0% BD) TPH 163.89 155.24 163.89 208.89

4 HRSG blow down (3% Con , 2% Int) TPH 8.19 7.76 8.19 10.44

5% 5% 5% 5%

5 Total flow ( 3+4) TPH 172.08 163.00 172.08 219.33

6 Flow with margin due to low frequency

TPH NA NA 181.14 NA

7 Flow with 10% margin . Only 4% in turbine bypass

TPH 189.29 NA NA 228.11

8 Required flow from each pump TPH 189.29 163.00 181.14 228.11

9 Required flow from each pump m3/hr 190.79 164.61 182.57 229.91

Say m3/hr 191 165 183 230

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B. Head calculations


NormalFlow

Under frq

Turbine Bypass

1 Deaerator operating pressure Kg/cm2 1.23 1.23 1.23 1.23

2 Static head up to Deaerator nozzle(22 mts above ground)

Kg/cm2 2.20 2.20 2.20 2.20

2a Static head from ground level to eye of impeller(4 mts)

Kg/cm2 0.40 0.40 0.40 0.40

3 Pressure drop in Deaerator spray nozzles Kg/cm2 0.20 0.20 0.20 0.20

4 Pressure drop in flow control valve Kg/cm2 1.50 1.50 1.50 1.50

5 Pressure drop in CPH Kg/cm2 4.36 3.92 4.36 5.89

6 Pressure drop in Flow nozzles (2 nos) Kg/cm2 0.60 0.60 0.60 0.60

7 Pressure drop in piping Kg/cm2 1.00 1.00 1.00 1.00

8 Pressure drop in Gland steam condenser Kg/cm2 0.80 0.80 0.80 0.80

9 Pressure drop in SJAE Kg/cm2 1.00 1.00 1.00 1.00

10 Margin on variable pressure drop {21% of (sum of 3 to 9 above) or min 1.0 kg/cm2}

Kg/cm2 1.99 NA NA 2.31

11 Total required discharge pressure. Kg/cm2 15.28 12.85 13.29 17.12

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C. Differential Head calculations


NormalFlow

Under frq

Turbine Bypass

Net Differential head to be developed by pump (B11-C6)

Kg/cm2 14.84 12.37 12.85 16.64

Margin due to change in frequency i.e applying factor {(50/47.5)2-1}

Kg/cm2 NA NA 1.34 NA

Required differential pressure Kg/cm2 14.84 12.37 14.19 16.64

Required differential pressure mwc 149.6 124.9 143.0 167.8

Say (rounding up to next 5mwc) mwc 150 125 145 170

D. Final parameters

Capacity of each pump m3/hr 191 165 183 230

Pump differential head required mwc 150 125 145 170

Head developed as per curve mwc 188 198 190 170

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BOILER

GEN.

CEP/ BFP Sizing during turbine bypass condition

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BFP SIZING CRITERIA (Typical)



NormalFlow

Underfrequency

Transient Condition

1 Temperature of the feed water 0C 105 105 105 105

2 Density of water kg/m3 954.74 954.74 954.74 954.74

3 HRSG capacity ( with super heater spray built in)

TPH 43.60 41.20 43.60 43.60

4 HRSG blow down (3% Con , 2% Intermittent)

TPH 2.18 0.82 2.18 2.18

5 Total feed water flow requirement(3+4)

TPH 45.78 42.02 45.78 45.78

5 Flow with margin due to low frequency

TPH NA NA 2.41 NA

6 Feed water flow with 20% margin during transient operation

TPH NA NA NA 9.16

7 Capacity of each Pump TPH 45.78 42.02 48.19 54.04

8 10% design margin on flow (allowance for ageing)

TPH 4.58 NA NA NA

9 Required flow from each pump TPH 50.36 42.02 48.19 54.94

10 SELECTED CAPACITY IN CMH m3/hr 53.00 44.00 50.00 58.00

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B. Discharge Head calculations


NormalFlow

Under frequency

TRANSIENT OPERATION

1 Highest safety valve set pressure Kg/cm2 (a) 91.63 NA NA NA

2 Drum Operating Pressure Kg/cm2 (a) NA 81 81 81

3 Over Pressure ( 3 %) Kg/cm2 2.75 NA NA NA

4 Static pr. due to drum height (21.6 m){height) x sp.gravity/10 }

Kg/cm2 2.06 2.06 2.06 2.06

5 Pr. Drop in Economizer Kg/cm2 3.00 3.00 3.00 3.00

6 Pr. Drop in feed control station Kg/cm2 1.50 1.50 1.50 1.50

7 Pr. Drop in discharge piping including fittings, valves, etc.

Kg/cm2 1.0 0.69 0.89 1.20

8 Pr. Drop in flow element Kg/cm2 0.30 0.21 0.27 0.36

9 Pr. Drop in ARC valve at discharge Kg/cm2 1.0 0.69 0.89 1.20

10 Total variable pressure drop (5+6+7+8+9)

Kg/cm2 6.80 6.09 6.55 7.25

11 Margin on variable pr. drop (21%)

(min. 1 kg/cm2)

Kg/cm2 1.43 NA NA 2.31

12 Pressure at discharge of Pump

(1 + 2 + 3 + 4 + 10 + 11)

Kg/cm2(a) 140.67 89.15 89.61 90.32

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C. Suction Head calculations


NormalFlow

Under fr TRANSIENT OPERATION

1 Pressure of De-aerator Kg/cm2 (a) 1.23 1.23 1.23 1.23

2 Pr. due to Height of the De-aerator LWLL from BFP suction nozzle

Kg/cm2 (a) 1.38 1.38 1.38 1.38

3 Total of above (1+2) Kg/cm2 2.61 2.61 2.61 2.61

4 Pr.drop in suction strainer-50% clogged(normal pr. drop approx. 0.1 Kg/cm2)

Kg/cm2 0.2 0.2 0.2 0.2

5 Pr. drop in suction piping, inclusive of fittings, valves, etc

Kg/cm2 0.20 0.14 0.18 0.24

6 Pr. loss on suction side of BFP (4+5) Kg/cm2 0.40 0.34 0.38 0.44

7 Available pr. on pump section side (3 – 6) Kg/cm2 2.21 2.27 2.23 2.17

8 Available NPSH (7 – 1) Kg/cm2 0.98 1.04 1.00 0.94

mwc 10.26 10.92 10.50 9085

9 Considering margin between NPSHA & NPSHR as minm. 2.5 m, the NPSHR of the pumps shall be limited to max. ( 50 % for rated flow)

Kg/cm2 5.13 8.42 8.00 7.35

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D. Differential Head calculations


NormalFlow

Under frequency

Transient Condition

Net Differential head to be developed by pump

Kg/cm2 102.46 86.88 87.38 88.15

Margin due to change in frequency i.e. applying factor {(50/47.5)2-1}

Kg/cm2 NA NA 9.44 NA

Required differential pressure Kg/cm2 102.46 86.88 96.82 88.15

Required differential pressure mwc 1073.16 909.14 1014.07 923.25

Final selected differential pressure mwc 1074 910 1015 924

E. Final parameters

Capacity of each pump m3/hr 53.00 44.00 50.00 58.00

Pump differential head required mwc 150 125 145 170

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CWP SIZING CRITERIA (Typical)



NormalFlow

Under frequency

Transient condition

1 Temperature of the feed water 0C 32 32 32 32

2 Density of water kg/m3 1000 1000 1000 1000

3 Maximum water demand CMH 8750 8750 8750 8750

4 Capacity shared by each pump (50%) CMH 4375 4375 4375 4375

5 Margin in flow due to low frequency on feed water flow

CMH NA NA 230.26 NA

6 Feed water flow with 20% margin

during transient operation CMH NA NA NA 875

7 Capacity of each Pump

CMH 4375 4375 4605.26 5250.00

8 10% design margin on flow (allowance for ageing)

CMH 437.50 NA NA NA

9 Thus, capacity of each pump with margin

CMH 4812.50 4375 4606 5250

10 Selected capacity of each pump CMH 4815 4375 4606 5250

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CWP SIZING CRITERIA (Typical)B. Discharge Head calculations


NormalFlow

Under frequency

Transient Condition

1 Cooling tower spray nozzle elevation from ground level including pr. drop in spray nozzle

MWC 7.00 7.00 7.00 7.00

2 Pump impeller / bell mouth level below pump-base plate level

MWC 4.50 4.50 4.50 4.50

3 Atmospheric head MWC 10.30 10.30 10.30 10.30

4 Total static head (1+2+3) MWC 21.80 21.80 21.80 21.80


MWC 1.60 1.60 1.60 1.60

6 Pump Internal losses MWC 1.10 1.10 1.10 1.10


MWC 3.0 3.0 3.0 3.0

8 Pr. Drop in flow element MWC 1.60 1.60 1.60 1.60

9 Pressure drop in Condenser MWC 6.00 4.95 5.49 7.13

10 Pressure drop in rubber expansion joint MWC 0.5 0.5 0.5 0.5

11 Pressure drop in nozzle MWC 0.8 0.8 0.8 0.8

12 Pressure drop in return line MWC 0.5 0.5 0.5 0.5

13 Total variable pressure drop(5+6+7+8+9+10+11+12)

MWC 13.50 10.65 11.19 12.83

14 Margin on variable pr. drop

(21% subject to min. 5 mwc)

MWC 5.00 NA NA NA

15 Bowl discharge head of Pump (4 +13+14)

MWC 40.30 32.45 32.99 34.63

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C. Suction Head calculations


NormalFlow

Under frequency

Transient Condition

1 Pump bell mouth / impeller level below sump min. water level

MWC 2.30 2.30 2.30 2.30

2 Atmospheric head MWC 10.30 10.30 10.30 10.30

3 Total of above (1+2) MWC 12.60 12.60 12.60 12.60

4 Pr.drop in inline-strainer MWC 1.00 1.00 1.00 1.00

5 Available pr. on pump suction side (3-4) MWC 11.60 11.60 11.60 11.60

6 Vapour pressure head of water at 32ºC MWC 0.61 0.61 0.61 0.61

7 Available NPSH (5-6) MWC 10.99 10.99 10.99 10.99

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D. Differential Head calculations


NormalFlow

Under frequency

Transient Condition

1 Differential Bowl Head of pump mwc 28.70 20.85 21.39 23.03

2 Margin due to change in frequency i.e. applying factor {(50/47.5)2 -1}

mwc NA NA 9.44 NA

3 Net Differential Pump Pr. (1+2)

mwc 28.70 20.85 23.70 23.03

4 Selected Differential Bowl Head of pump mwc 29.00 21.00 24.00 24.00

E. Final parameters

Capacity of each pump m3/hr 4815 4375 4606 5250

Pump differential head required mwc 29.00 21.00 24.00 24.00

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PROPER SELECTION OF EQUIPMENT

Pumps are selected based on Parameters :

- pump flow rate

- total dynamic head

- operating temperature

- suction pressure / NPSH available Developments in design & technology have made

available reliable & efficient products & systems aimed to reduce auxiliary power consumption

The best efficiency shall preferably be between design and normal point. Design capacity shall be within 80-110% of the best efficiency capacity

Pumps shall have stable Q-H characteristics Continuous head rise to shut off of atleast 10%

preferred for parallel operation

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VARIABLE SPEED DRIVES

Boiler Feed Pumps (BFPs), Forced Draft (FD) fans and ID Fans are large consumers

Constant speed drives use throttling elements incurring energy losses in the system

Variable speed drives are being increasingly used due to several advantages they have over the conventional fixed speed drives

Use of hydraulic coupling reduces the losses to some extent as efficiency of coupling itself is very low at lower speed

VFD enables operation over a wide range of load at high efficiency with low energy consumption at lower speeds

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Optimisation of Mechanical Design

Mechanical design parameters like the design pressure of pump casings etc. are specified corresponding to the most severe possible scenario such as ;

- over frequency of operation at 51.5 Hz

- highest operating speed of the pump

- shut off head at zero flow

The above criteria results in higher values for design pressures thereby increasing the pump component costs. In actual site operation, eventuality of pump subjected to all the above severe operating conditions simultaneously is remote.

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Optimisation of Materials of construction

Bronze Cast iron Cast steel 400 series Stainless steel 300 series Stainless steel etc.

Selection criteria for materials :•corrosion resistance•abrasive wear resistance•cavitation resistance•casting & machining properties•endurance limit•notch sensitivity•galling characteristics•cost

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Optimisation of Quality / Inspection checks

Too much ambitious quality checks like LPI, MPI, UT and Radiography for 100% quantity & 100% area would add to cost of product as well as increased cycle time in view of the CHPs involved

Too much ambitious special/type tests like NPSH test on all the contracted pumps would add to cost of product as well as increased cycle time in view of the CHPs involved

Routine test is ok

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PERFORMANCE TESTING

Routine tests on all pumps

Mechanical performance to check :

- Vibrations- Temperatures- Leakages

Hydraulic performance to check :

- Flow Vs Head Characteristic - Flow Vs Power Characteristic

- Flow Vs Efficiency Characteristic

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Type tests as optional

• HOT WATER PERFORMANCE TEST• COMBINED STRING TEST• AXIAL THRUST MEASUREMENTS• PRESSURE PULSATION TEST• DRY RUN TEST• THERMAL SHOCK TEST• VISUAL CAVITATION TEST

Special tests on Boiler feed pumps :

• NPSH TEST

PERFORMANCE TESTING

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Conclusion

• Optimisation of sizing, selection, mechanical design, quality/inspection checks and performance testing

results in :– lower auxiliary power– lower cost &– lower cycle time

• Hence utmost attention is to be given for the optimisation of the above

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Thank You

Documents

Pump final