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# Increasing Pump Pressure Discharge With Low Flowrate

centrifugal pump

4 replies to this topic
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### #1 fahima93

fahima93

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Posted 12 December 2018 - 12:41 AM

Dear all,

Is it possible to achieve high pressure discharge and low flow from centrifugal pump, by adjusting recirculation line (spillback)? Will the spillback affect the pressure discharge of the pump?

Pressure that I need in downstream the pump is around 21 kg/cm2, considering the pressure drop along the pipe around 4 kg/cm2 then I need the discharge pressure to be ~25 kg/cm2. Meanwhile, the flow that I need only ~1000 kg/h.

Is it possible to achieve that condition (Pressure discharge ~25 kg/cm2 and flow only 1000 kg/h), given the datasheet and performance curve attached?

Thank you

### #2 fallah

fallah

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Posted 12 December 2018 - 02:07 AM

Hi Fahima,

Around 25 kg/cm2 and 4,000 kg/hr is on the pump curve - but at the minimum flow point... minimum flow seems to be 7.5 m3/hr or around 4,000 kg/hr according to the S.G. of the fluid...

If you have a control valve along the spill back line, you can throttle the discharge valve till the minimum flow point is reached - where the control valve will start to open...

Then continue throttling the discharge valve till the point in which you would have 1,000 kg/hr in discharge line corresponding to have 3000 kg/hr in spill back line with considering the fact that the total of flow in minimum flow line and discharge line at minimum flow region should be around 4,000 kg/hr...

At minimum flow point the head is around 25 kg/cm2 hence you can have the desired H and Q by above mentioned procedure...but at minimum flow point which isn't a proper working point for long term operation...

### #3 breizh

breizh

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Posted 12 December 2018 - 05:05 AM

Pagi 'bu,

If the requierement is for continuous service, i will consider to purchase a new pump .

In any case you should consult EBARA for advice.

my view .

Breizh

### #4 shan

shan

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Posted 12 December 2018 - 02:01 PM

Maybe, it is more economical to change a set of pump impellers to reduce the required minimum flow for the power savings in the long run.

### #5 MF003

MF003

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Posted 16 December 2018 - 11:39 AM

dear,ff

just check that at 1000kg/hr what is you differential heat H1. and check that this differential head is higher than required differential head H2 at 1000 kg/hr by hydraulic calculation.

IF H1> OR = H2   THIS PUMP CAN WORK

IF H1< H2   U NEED A NEW PUMP

spill bak line will not help you in thatbecause if you are decreasing presure drop across spill back Cv by throtelling discharge line valve to gain in suction pressure , one the other hand you are killinh the pressure across discharge valve by throtelling it.  no i dont think it cal work. and one more thing please dont play with spill bak line, it is a pump protection