Page 230 - Boiler plant and distribution system optimization manual

Boiler Plant Calculations 215

Energy lost with flash steam:
15% x 20,000 lb/hr x 970 Btu/lb = 2.91 million Btu/hr
Steam Energy loss = 2.91/22.1 = 13.2%
Fuel Energy Loss = 13.2%/80% = 16.5%

Note: The flash steam mingles with condensate in the piping and gives up heat to the
cooling condensate before it vents to atmosphere so the loss is less and depends on the
actual situation. This is a theoretical illustration.

2. Average trap leakage is 10% live steam in the system.
Energy loss = .1 x 20,000 PPH x 1105 Btu/lb = 2.2 Million Btu/Hr
2.2/22.1 = 10%

3. Because of steam and condensate leaks, 35% make-up feedwater at 60°F is re-
quired.

Energy loss = 35% x 20, 000 lb/hr x 60 Btu/lb = 0.42 Million Btu/hr
Steam Energy Loss 0.42/22.1 = 1.9%
Fuel Energy Loss 1.9%/80% = 2.4%

4. Condensate system losses. Condensate reaches the receiver at 120F, having cooled
from 212F losing 92 Btu/lb. (35% makeup water)

.65 x 20,000 lb/HR x 92 Btu/lb = 1.2 Million Btu/hr

Energy loss 1.2/22.1 = 5.40%
Fuel Energy Loss 5.4/.8 = 6.75%

Steam System Fuel Energy
Loss Loss
——————————————————————————————————
Flash steam loss 13.2% 16.5%
Trap losses 10.0% 12.5%
Makeup water heat loss 1.9% 2.4%
Cold condensate return 5,4% 6.15%
Total system losses 30.5% 38.15%
Efficiency 69.5% 62%
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