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PUMPS for Process Industries Ranjeet Kumar M.Tech - Chemical
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Pumps for Process Industries

Aug 11, 2014

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Ranjeet Kumar

This presentation will give a broad idea about selecting pumps in process industies. Design parameters are also discussed.
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Page 1: Pumps for Process Industries

PUMPSfor

Process Industries

Ranjeet KumarM.Tech - Chemical

Page 2: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 2

Equation of Energy

A pump converts Electrical energy to Pressure Energy via Kinetic Energy.

Electric energy K.E. K.E Pressure Energy

ImpellerRotating Part

VoluteStatic Part

Page 3: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 3

Types of Pumps

Centrifugal - Impeller & Volute Reciprocating - Piston / Plunger Rotary - Screw, Gear, Lobe, Progressive

Cavity, Sliding Vane Vertical - Peristaltic - Series of rollers to push through

tubing

Page 4: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 4

Basis for selection of Pump

Capacity – No. of pumps in parallel Total Head – No. of stages Physical, Chemical properties of Liquids Viscosity @ Frictional Loss @ Power Required Corrosive Fluid @ MOC

Site conditions Source of Power

>>>Capacity & Head required are most important selection criteria and define size of the pump.

Page 5: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 5

Capacity

Volume of liquid to be pumped in unit time May vary as per Max, Min & Normal requirement – design should be for Max capacity. Its function of Impeller size and rotational speed

for Centrifugal pump Q = V * A : V = ω * r

Page 6: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 6

Centrifugal Pump Design Problem

Inability to deliver the desired flow & head Seal problems (leakages, loss of flushing, cooling,

quenching system, etc) Pump & Motor bearings related problems (loss of

lubrication, cooling, contamination of oil, abnormal noise, etc) Leakages from pump casing, very high noise &

vibration levels.

Benefits of Centrifugal Pumps – low cost, easy maintenance, wide selection,& simple design.

Page 7: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 7

Head of Pump

Total Head = P discharge – P suction Normal head test by vendor was done

for water at 20°C. Advantages of using Head--

Page 8: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 8

Physical Properties Consideration

Specific Gravity 1) Increases Power consumed directly. 2) Max suction lift inversely.

Viscosity Pump efficiency decrease directly so Power required directly

Open or semi open impeller are better for highly viscose liquid.

Volatile liquid at boiling points require high NPSH. Abrasive property of liquid or solid entrainment

causes erosion and need specific MOC. Corrosive liquid require specific MOC.

Page 9: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 9

Solid content Centrifugal pump operation is most difficult

when liquid handled contains solid particles. Special attention required for selecting a

centrifugal pump a) Open Impeller for solids > 2%b) Large cross section in Impeller & Volutec) Min No. of Vanesd) Inspection holes in tha casing & suction passagee) Abrasion resistant MOCf) Smooth corners & edges in linesg) Stuffing boxes sealed with clear fluid

Page 10: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 10

Fig – Types of Impeller

Page 11: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 11

Temperature of liquid Direct Impact on physical properties of liquid & Vapor Pressure and MOC.

Page 12: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 12

Site Conditions

Altitude – P atm decreases with altitude & P atm has direct effect on NPSHa

Gas Dust Hazard – if the surrounding atmosphere is hazardous/inflammable Flame proof & Dust proof MOC of Motor.

Stand by unit for vital application.

Page 13: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 13

Selection of Pump – Capacity & Head

Type Capacity Head Viscosity

Solid % Gas

Centrifugal Upto 7500 m3/h

Upto 105 m

< 200 cSt

Upto 20%

< 2%

Rotary < 350 m3/h

1050 m

Max < 5% > 2%

Positive Displacement

< 300 m3/h

10500 m

< 600 cSt

< 25% > 2%

Peristaltic Upto 1 m3/h

< 25 m < 200 cSt

Page 14: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 14

Flow Rate DesignMargins for rated/maximum capacity

Service MarginContinuous process pumps

10%

Reflux pumps 20-25%Intermittent pumps 0%Transfer pumps 0-5%Large cooling water pump

3-5%

Recirculation pump 0%Boiler Feed water pump 25%Waste Heat Boiler pump 30%

PFD indicates normal flow rate without any margin & the Maximum flow is Considered for sizing of the pump with margin

Page 15: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 15

Minimum flow rate ????

Under development………….

Page 16: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 16

Static Head

Pump centre line as datum for Hydraulic calculation

Pump centre Line from ground (estimated)

Minimum level in Suction & Maximum level in Discharge tank.

Flow Rate (m3/h)

Pump centre line above

ground0 – 100 0.7

100 – 200 0.9Above 200 1.0

Page 17: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 17

Line Pressure Drop ?

Under development

Page 18: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 18

Pressure Drop for Control Valve

The following criteria can be used for sizing the control valve

15~25% of the variable system drop is typically allowed.

On recycle and reflux pumps allow 1/3 of the variable system pressure with minimum of 0.7 bar.

For liquid system 0.7 bar For system with large variable pressure drop

( >10 bar) ~15% of the variable pressure drop exclusive of control valve

Page 19: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 19

Pressure Drop for DevicesDevices in Flow Line Press Drop (in bar)

Shell & Tube type Heat Exchanger

0.7 bar per pass in tube side0.35 – 0.5 bar per shell

Air cooler 1.0 barY, T or Bucket type Strainer 0.07 bar (continuous

strainer)Orifice Flow meter 0.25Venturi Flow Meter 0.02 – 0.05Vortex 0.2 – 0.4Corilolis Flow Meter 0.2 – 0.4Ultrasonic & electromagnetic Flow Meter

0

Page 20: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 20

NPSH

NPSHA = Suction Pressure – Vapor Pressure NPSHA should be 2 – 3 ft more than NPSHR. It is the pressure enough to prevent formation

of vapor bubbles due to vaporization or release of dissolved gases in the Impeller.

Pressure increases along the impeller on collapse of vapors – Cavitation.

Cavitation – Noise, Vibration, Drop in performance curve, high wear & tear loss.

Page 21: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 21

NPSHA optimization NPSHA can be increased by – 1) Raise the liquid level2) Lower the pump3) Reduce the friction losses in the suction line4) Use a booster pump5) Sub cool the liquid

NPSHR can be reduced by – 1) Slower speed2) Double-suction impeller3) Large impeller area4) Oversize pump5) Inducers ahead of conventional pump at suction side6) Several smaller pumps

NPSHR Rotary < NPSHR Centrifuge < NPSHR Reciprocating

Creative
change slide heading if got a better line. ranjeet
Page 22: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 22

Efficiency

Efficiency = WHP/BHPOverall efficiency reflects hydraulic, leakage &

mechanical losses of pump.

ηcentrifugal < ηreciprocating < ηrotary

(50 – 80%) (50 – 90%) (70 – 90%)

Page 23: Pumps for Process Industries

08-Jun-08 Ranjeet Kumar 23

Seals, pumps curvesUnder Development……..