Low NPSH pump

[hemvig]

the project is looking to buy a steam condensate pump, the flow is 120 gpm and the head is 235 ft, (Continuous flow)
the problem is with the NPSHA < 0.5ft, I am trying to find a pump which meets this requirement. They dont want to have a Vertical canned pump
Please let me know any other vendor or pump that can meet this requirement.

I have found a Vertical in-line Roth pump (Regenerative turbine type) the NPSHR is 1 foot.

The pump will be pumping the steam condensate from existing Condensate pot (which is already below grade)


Please let me know if there is any pump other than vertical can and what is the long term consequences with less NPSH margin?

 

[1gibson]

VERY high Nss, which can cause instability at operation off BEP.

 

[NGLENGR]

Any particular reason why a vertical can pump is out? Most people that have bad feelings about vertical pumps usually were around ones that were mis-applied or poorly engineered.

The best I can suggest is a low-speed multi-stage pump, but even then you're hard-pressed to find something that isn't a canned solution.

 

[vesselguy]

I have a similar low NPSHA water pump application and Operations keep saying they don't want vertical canned pump but can't give me any good reason other than "bad maintenance". Typical operator response without any good technical input on the source of the problem.

I too would like to know why there is such resistance to a vertical canned pump. Can anyone share information on this?

BTW, the solution to my pump problem, that is acceptable to Operations, is to use a high Nss pump, low rpm and raise the tank height by 4 ft.

 

[hemvig]

The pump is pumping from a existing Condensate pot (already below grade), and the Client is not wanting to dig a deep hole for the vertical canned pump $$$.....

When I inquired from couple of vendors the can length they gave me was 12' and 9' respectively


Earlier i forgot to mention about the steam condensate temperature, it is 360 F

I believe this temperature requires a Plan 21 or 23 arrangement.

Please let me know if there is any other thing to be taken into consideration when selecting the mechanical seal and flush plan?

 

[ione]

What about a pressure powered pump?
Spirax manufacture such an item

http://www.spiraxsarco.com/products...energy-recovery/pressure-powered-pumps.asp#ti

http://www.spiraxsarco.com/pdfs/TI/p135_04.pdf