Page 223 - Boiler plant and distribution system optimization manual

208 Boiler Plant and Distribution System Optimization Manual

Figure 11-2
Figure 11-4

4. What is the temperature of the steam and
water at 100 psig?
(Ans.: above 338 F)

5. Condensate is returning to the boiler plant at
120F [80C] instead of 185 F [85C], how many
Btu’s are being lost in each pound of water?

185 F water [85C] 153 Btu/lb
120 F water [49C] 88 Btu/lb
Difference 65 Btu/lb

Comment: Starting at 32F, adding 1 Btu raises the
temperature of water 1F. (185F-32F = 153 Btus). More
exact tables exist .

6. If the boiler’s efficiency is 80% how much
fuel energy (Btus) will it take to replace the
65 Btu/lb in the example above?

65 Btu/lb
———— = 81.25 Btu/lb
Figure 11-3 80%