Condensate Ejectors

[brainstorming]

I would like to know the better from experience the selection between ejectors or pumps in condensate service.
The service is steam condensate generated by reboiler.
I got feedback from one expert engineer that he doesn't recommend having ejectors since they are having frequent problems due to two phase flow and not reliable as centrifugal pumps.

Any help or thoughts about this subject are really appreciated.

Cheers

 

[checman]

Brainstorming, I am not sure I understand your question. Centrifugal pumps do not do well on two phase fluid applications. They will trap vapor at the impeller eye reducing capacity or worse yet vapor lock. To move two phase fluids I have used ejectors in a condensate system. It is a two part system with the ejectors mounted in one vented tank circulating water with the ejector inlet pulling a vacuum on the condensate tank. Level control on the condensate tank turns pumps on to pump the condensate to a holding tank or the DA. A wet vacuum pump could do the same but would cost more and be more of a maintenance pain. I have also used liquid movers to push condensate to a holding tank. They are just a gravity accumulator tank that when the condensate level gets to a certain point it trips a valve that opens a steam valve and the steam pushes the condensate to its destination.

Regards Checman

 

[brainstorming]

Thank you checman for your explanation
Actually my question or concern of using ejectors instead of centrifugal pumps in pumping condensate from distillation column reboilers.
From my experience, centrifugal pumps are usually used in such services but I have not seen ejectors that would be not reliable due to two phase flow if occur.

Cheers

 

[25362]

Steam ejectors used to pump water are called "siphons". The principle is similar to that as for other types of eductors but the steam must totally condense in the pumped water i/o to achieve efficiency, and the motive nozzle differs from conventional jet nozzles.

Karassik's et al. Pump Handbook (McGraw-Hill) brings a detailed presentation in Chapter 4: Jet Pumps, as well as plenty of information provided by Schutte & Koerting.