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Steam Condensate Pump Cavitation

Tom Anderson_2
Tom Anderson_2 Member Posts: 9
in THE MAIN WALL
I have a pump curve for a project with a steam condensate receiver/pump set. Receiver is at atmospheric pressure, and condensate will be hot, probably close to 210F or a little less.

Looking at the condensate pump curve, at the design operating flow and head, the net positice suction head required (NPSHR) is about 14 feet. Since the receiver will only have a couple of feet of static head, seems to me the pump will cavitate.

Is it normal for a steam condensate return pump to operate on the curve where cavitation is certain to occur? Seems contrary to my years of regular hyrdonic pump selection... but perhaps condensate pumps are slightly different animals and this maybe is normal for such condensate pumps?

Or should the pump be selected with a lower NPSHR?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,039


    I don't claim to be a expert on this but cavitation will ruin the pump. More head on the pump or cooler condensate are the only answers. Thats why on hp steam the pumps are usually seperate from the tank and sit underneath with the tank up high to get more head due to the hotter condensate.

    I recall using "Domestic ITT" pumps on a job and it seems to me they had a line of "low npsh" pumps. I think you can get to them from the ITT or B& G website. Different pum design can get you closer than you are now but 210 at atmospheric I don't think you can do it. The pressure in the eye of a centrifigal drops when the pump starts. I think your to glose to the boiling point.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,611
    You can get

    a condensate pump with an axial-flow impeller for this service. It's sort of a propeller that's right at the eye of the impeller. The propeller boosts the pressure as the condensate enters the impeller and helps the pump avoid the agony of caviation.

    Your pump supplier will be able to get this for you if you mention it.
    Retired and loving it.
  • dusty roads
    dusty roads Member Posts: 2
    hot condensate

    i think you need to address the condensate temp, do you have traps blowing by? i agree that cooler temps (165 /180) would be better or if your process(is this a process or comfort heat) requires the higher temp than a DA tank would be a good applaction, check traps and sparge lines and get temp down
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