TEG Pumps having high discharge temperature

[K. Adam]

Dear Gents,
Actually we are suffering from frequent failure in our Glycol pump discharge pulsation dampener. as part of investigation we noticed that the pump's NPSH is quite low due to suspected blockage in the upstream exchanger tube bundle. Can any one explain to me the possible root cause of high discharge temperature which is being pointed to be the main cause of bladder rupture.
In addition to the above, is there any relation between LOSS of NPSH and increase in the pump discharge temperature?

 

[georgeverghese]

So temp has increased further from pump suction to pump discharge ? Vapor in pump suction would have increased in temp at discharge, but heat of vapor compression would be easily absorbed into liquid TEG, resulting in very little net increase in temp.
One valid reason for further increase in pump discharge temp could be internal recycling of TEG within the pump, which is due to broken or worn out piston rings on plungers, or due to significant scouring of the liner or maybe leaking suction or discharge valves - check your pump strainer also for damage.

 

[K. Adam]

Thanks for your input and well appreciated...

 

[K. Adam]

Regarding the second possible reason you mentioned in your reply "Recycling of TEG due to broken/worn out piston", I just would like to inform you that we have steady flow with minor fluctuation but having knocking sound in pump skid.

 

[georgeverghese]

Knocking sound may well be due to vapor in pump, given the loss in NPSHa. C5plus dissolves in TEG, and there may be C8plus in reboiler exit lean TEG. See if you can find some way of skimming off this condensate in the reboiler. Skim off condensate in the rich TEG sump of the wet gas - lean TEG contactor column also if you can.
Check the NPSHa calcs for this pump - see what vapor pressure was used for lean TEG. Though you may have a suction pulsation dampener, you may not get the full credit for suction side acceleration head reduction due to pulsation attenuation as predicted by design calcs - this further aggravates the NPSH availability. For this reason, some OpCo standards require at least triplex (not duplex) pumps be used in this service.

 

[K. Adam]

Well noted. Thanks for your kind feed back.

 

[LittleInch]

Don't hijack another thread with something completer different. This has been discussed already in its own thread.

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