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Design Considerations For Cryogenic Submersible Pump

cryogenic submersible pump

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#1 heydari

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Posted 04 February 2024 - 08:16 AM

The problem is as follows...

A Cryogenic submerged pump from NIKKISO with flowrate 200m3/h used for propane circulation, which from the beginning has a noise like cavitation while there is no fluctuation in discharge pressure and electrical amp. It is necessary to mention this point that by limiting the suction valve the noise is solved.

 

Based on the pump document, the 3” nozzle on the top of the suction pot shall has permanent vent around 21 kg/min flowrate. This is while in reality, nozzle connected to flare system with normally closed valve.

So, if that noise is related to ventilation system, could anyone possibly tell us how should be the right network system and the destination of the vent.

 

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#2 shvet1

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Posted 04 February 2024 - 11:33 PM

could anyone possibly tell us how should be the right network system and the destination of the vent.

 

Vapor space above liquid level of a suction vessel



#3 heydari

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Posted 05 February 2024 - 12:43 AM

How do you do that?

While the pressure in vent nozzle is like suction pressure



#4 shvet1

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Posted 05 February 2024 - 11:24 PM

How do you do that?

How I do what?

We connect vent to vapor space of a chamber where the liquid is pumped from.

 

 

While the pressure in vent nozzle is like suction pressure

Correct. Pressure in vent nozzle is equal suction pressure.

 

Now C3 vapors backflows to suction chamber through suction line. Now you have 2 flows in suction line simultaneously - liquid goes downward, vapors go upward. This :

- drastically reduces NPSHA, or

- forces liquid level oscillating, or 

- reduces liquid level in suction pot and causes bubbles entrainment and cavitation

 

To avoid this you need to balance pressure and liquid level in pump suction pot and vessel suction chamber.



#5 breizh

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Posted 06 February 2024 - 01:26 AM

Hi,

Did you contact the vendor and ask about the recycling of the vent?

https://www.nikkiso..../submerged.html

Breizh



#6 heydari

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Posted 06 February 2024 - 04:55 AM

Hi MR. Breizh

because of some considerations NIKKISO doesn`t answer.

My solution is attached but I'm not sure!  

Attached Files



#7 breizh

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Posted 06 February 2024 - 06:13 AM

Hi,

Follow Shvet1's recommendation and route the vent to the sky of the storage tank. The driving force is the static head of liquid in the storage tank.

Why do you need the vent flow rate calibrated, it will be what it will be, based on pipe size and head loss?

I don't understand the part with ejector and compressor.

You need to keep your process simple; this is a vent line!

Breizh



#8 shvet1

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Posted 06 February 2024 - 09:06 AM

incorrect

Attached Files

  • Attached File  1.png   82.73KB   3 downloads





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