Condensate Return/ Pump Capacity/ Head 1

[w1999]

Hello All,
Please I need your help.

I have a LP-steam boiler discharge preesure 10 psig, located 600 feet from a building. The pressure entering the bldg. 5 psig. I allow 5 psig pressure drop for the run, and 5 psig to the bldg. The bldg. area 5312 sq.ft and the total steam load 480 #/hr for 3 UH, 1 HV, I used 1/2 psig/100' pressure drop.
I found the pump capacity:GPM=(480 #/hr)/(20*500)=48
I calculate and found 3" LPS pipe, and 2" CR pipe. How much head I should use if the bldg. roof 24 feet. And how much I should pitch the Supply/Condesate return, is 1/4" per 10' ok.Is these calculations are ok.
Best regards.

 

[TBP]

Even allowing for another 20#/hr for line loss on the steam run, I figure your pressure drop will be less than 1 PSI over the 600 feet of 3". These lines should slope about 1/2" in 10 feet, but the steam line should slope to the building, and the condensate line should slope back to the boiler area. The cond pump will need to handle about 1 GPM (500 #/hr steam will give you 1 USGPM). If the condensate has to discharge into a pressurized tank, like a DA, make sure that you factor this into the discharge head required for the pump.

Remember to allow for expansion on these lines.

 

[w1999]

Hello TBP,

1 GPM all I need, what about delta T.
1 GPM=(500#/hr)/500, (500=8.3lbs/gal*60 min/hr)

GPM=(500#/h)/(20 F*500)= 500*975 BTUH/10000=48.75 GPM

How about the lift, (600'+300')for fitting, elbows*0.04=36 feet.

Best regards.

 

[TBP]

Is there a steam to hot water HX in the building? If there is, then there will be two pumps - one for condensate return, and another one to circulate the water through the building loop.

 

[w1999]

No, there is no hot water HX. The bldg. is 80'x64'.
The total steam load to the bldg. 480 #/hr
for (3)48#/hr UH, (1)18#/hr UH and
(1)314 #/hr for HV unit. The HV unit has
5120 CFM,
face velocity=640 fpm,
Entering DBT=15 F
Leaving DBT=72 F
Steam Temp.=227 F

Thank you for your help.

 

[TBP]

You only need the one pump, and that's for the condensate. The only calc needed for the pump GPM is the steam load in #/hr, divided by 500. Forget the part of the calc that's giving you 48 GPM - that's for a pumped hot water system. Steam will move itself - no pump required.

I can tell that you're not a "steam guy". You should likely find somebody from Spirax Sarco, Armstrong, Bell & Gossett, etc in your area to walk you through this.

 

[w1999]

Thank you TBP for these info.
You the only one who got back to me.
I am still new in Engineering Field, "Steam", etc.

Thank you again.