Centrifugal pumps flow limitation

[johnthebest]

Hello everyone
In our project specification we required API 610 centrifugal pumps for condensate.
having these parameters:
Flow 0.7-0.8(m3/h)
Suction pressure: 2.2 bar
Discharge pressure: 35.8 bar

The contractor claimed that there is no centrifugal pumps available on the market that can operate in these parameters, hence he proposed double diaphragm pumps.

what are your thoughts?

 

[Valvecrazy]

The only centrifugal I can find that will do that is a submersible. A Grundfos 5S30-48, 3HP will do that. You can install it in a wet well, or it can even be put in a can and used as an inline booster.

 

[johnthebest]

Thank you Valvecrazy for your response. however the condensate pumps is going to be installed after a pressure vessel "where the condensate will be stored" so the submersible pump is not an option.

 

[Valvecrazy]

A submersible in a can can take some inlet pressure. How much I don't know. Good luck!

 

[LittleInch]

That's a pretty small flowrate at quite a large differential pressure, so you're getting into the realms of small PD pumps of some sort.

If this is after a separator and your "condensate" is volatile, your issue is going to be NPSH or the lack of it...

A can pump might be your only solution.


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

 

[Artisi]

API 610 is out of the question, therefore you need to get the specification reviewed and rewritten by the authority who wrote the spec.
Rotojet pump could be an alternate selection, or as valvecrazy has pointed out a can mounted submersible unit or even mounted directly thru' the wall condensate storage vessel.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[johnthebest]

the fluid is Natural-gas condensate, also called natural gas liquids and not water condensate

 

[LittleInch]

Then your issue is NPSH.

Condensate is basically at its vapour pressure at 2.2 bar so if you need to pump this then your only way to get NPSH is with gravity. Unless your separator is mounted 5m in the sky, then you need to dig a hole and drop a can unit in or a bigger hole and mount a pump down inside the big pit.

Your issue here is the flow rate. Is it really only 0.8 cubic metres an hour?? That's peanuts.

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

 

[Artisi]

Any more surprises?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[johnthebest]

Thx for your responses. @ Littleinch Yes, the rated flow is 0.9 m3/H and it will operate in the range of 0.6-0.7 m3/h. As I understood, the solution is to raise the height of the vessel and use a can pump or use the positive displacement pump.

 

[Artisi]

Or look at Rotojet or similar?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[johnthebest]

thank you for all for your responses.
can you show me a drawing of where to place the can pumps and how it will be isolated and removed in case of maintenance.

 

[LittleInch]

Can pumps are simply a vertical turbine pump which is fitted inside a long tube or "can" which is normally just buried in the ground. The pump can be lifted out of the can by simply unbolting the top flange.

You usually need to make sure the outside of the can is well protected and in some locations they insist on a double skin to the tank the same as buried tanks to ensure no leakage.

Just google "Can pumps" for more info.
The dimension Z below is the lowering of the inlet for NPSH purposes from the visible above ground section.

This is still a very small pump. You may need to get a bigger pump and operate it on an on/off basis by storing fluid inside the separator until it needs to be pumped out.

PD pumps generally have a lower NPSH, but still have some and also they can suffer from acceleration head requirements, so they aren't always a good choice for low NPSHA fluids.

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

 

[johnthebest]

Thx you LittleInch for your clarifications. God bless you

 

[Valvecrazy]

You can also use a submersible is a can similar to that. The submersible I referenced will work at 3 GPM. I don't think you can get a canned turbine to go that low of a flow rate.

 

[johnthebest]

@ Valvecrazy
I don't think the referrenced pump will do the work. the differential head we have is 537m

 

[Artisi]

head was 35.8 bar - now its 537 metres ??????????????????????????????

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

That's about right. This is pretty light HC, probably about SG of 0.6.

Still a very small amount of flow so I would batch flow it myself.

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

 

[Valvecrazy]

NO won't work at 537M, but would work at 35.8 bar.

 

[Artisi]

LI, correct, I'm only haff watching this one and old age got the better of me - forgot the low SG, my excuse anyway.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)