Calculate the total head of a boiler feed water pump

Salvation,

Looks good to me. Just remember this is total differential head which is what a pump vendor needs, not a system head curve.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

LittleInch,.... This is totally incorrect.....

A boiler IS NOT ANOTHER TANK !

The TDH of a BOILER FEED PUMP MUST AT LEAST BE:

- The steam pressure of the boiler (expressed as ft of water) PLUS
- The piping, control valve and other losses between the BFW pump and the feedwater inlet to the boiler PLUS
- A reasonable margin - for off design conditions.

The pressure of 6.5 kg/cm2 is atmospheric pressure at the stack and has nothing to do BFW pump head calculations

See page #26 of this fine manual....

"The pressure of 6.5 kg/cm2 is atmospheric pressure at the stack.." Err since when was atmospheric pressure 6.5 bara??

The OPs calcualtion is
Steam pressure of the boiler in m absolute (65m),
plus his losses - 1m (prob a bit low but hey)
plus Pressure on the boiler feed water - 10m abs
plus Height difference between inlet tank and boiler level.

This would appear to be the same as yours and page 26 of what I agree is a fine looking manual - thanks for the link.

Sure, there is no margin in there and that is a reasonable point and the losses for the control valve are a little low, so given that I would probably add about 15m to the calcualtion to give a more reasonable figure and to make sure you don't run out of boiler feed water - this is based on having a control valve controlling level between the pump and the boiler.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

I agree with LittleInch, MJCronin, and the OP. All three arrived at the same conclusion...

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies