Spillback Line Return to Tank or Suction of Pump

• Jul 29, 2024

• #2

bimr

Civil/Environmental

Feb 25, 2003

9,327

Don't believe anyone can submit an appropriate answer without knowing the details of what chemical that you are injecting, whether this project is indoors or outdoors, whether the substances are flammable, what effect will the spillback purity have on the system, etc. It would help to have a simple flow diagram.

 

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• Jul 29, 2024

• #3

LittleInch

Petroleum

Mar 27, 2013

21,545

Only if the temperature increases in the pump suction.

Too many unknowns.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

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• Jul 29, 2024

• #4

Heaviside1925

Mechanical

Jun 7, 2024

431

Yes, it can matter. P&IDs or sketch? pump specifics / information? process description and conditions? spillback type? injection type?

 

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• Jul 30, 2024

• #5

1503-44

Petroleum

Jul 15, 2019

6,654

One of these types,

https://www.williamspumps.com/en-us/

or similar low power low volume pumps? can usually be routed to either place.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

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• Jul 30, 2024

• #6

mk3223

Mechanical

Feb 4, 2006

1,486

IMO, the spillback of the injection pump is typically routed back to the tank without any concern. The return line of the 25ft head shouldn’t be the issue for the pump discharge.

 

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• Aug 1, 2024

• #7

georgeverghese

Chemical

Mar 19, 2015

4,852

Since total injection rate will often be less than pump throughput capacity, pressure spillback should be to source tank, not into pump suction.

 

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• Aug 1, 2024

• #8

1503-44

Petroleum

Jul 15, 2019

6,654

If it was full throughput, then it's OK?

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

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• Aug 1, 2024

• #9

georgeverghese

Chemical

Mar 19, 2015

4,852

@1503,
If sum total injection rate always matches pump capacity, the pressure spillback line wont be operational at any time, so it wouldnt matter if there were to be a spillback or not, or where it is connected to.
Suspect this is a fixed speed pd pump ?

 

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• Aug 1, 2024

• #10

1503-44

Petroleum

Jul 15, 2019

6,654

Only operational when pipeline pressure is greater than max discharge P of pump. Probably not going to occur, unless discharge line is closed while running.

Typical installation is

From

https://www.spxflow.com/assets/pdf/bran-luebbe-1649-us-chemical-injection-for-oil-and-gas.pdf

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

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• Aug 1, 2024

• #11

georgeverghese

Chemical

Mar 19, 2015

4,852

If it is going to involve considerable effort to connect this pressure recycle to source tank, it may be possible to return this to pump suction provided :
a)fluid saturated vapor pressure (or bubble point pressure) is much less than minimum suction pressure at say 10degC higher than source tank temp
b)pump is stopped on auto sequence when there is no net forward flow to consumers.

If you dont know bubble point pressure info for the chemical being injected, route pressure recycle to source tank.

 

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