Boiler loads, or the capacity of steam boilers, are often rated in boiler horsepowers, lbs of steam delivered per hour, or BTU.
Large boiler capacities are often given in lbs of steam evaporated per hour under specified steam conditions.
Since the amount of steam delivered varies with temperature and pressure, a common expression of the boiler capacity is the heat transferred over time expressed as British Thermal Units per hour. A boilers capacity is usually expressed as kBtu/hour (1000 Btu/hour) and can be calculated as
W = (hg - hf) m (1)
W = boiler capacity (Btu/h)
hg = enthalpy steam (Btu/lb)
hf = enthalpy condensate (Btu/lb)
m = steam evaporated (lb/h)
The Boiler Horsepower (BHP) is
A BHP is equivalent to 33,475 BTU/Hr or 8430 Kcal/Hr and it should be noted that a boiler horsepower is 13.1547 times a normal horsepower.
Horsepower (hp) can be converted into lbs of steam by multiplying hp with 34.5.
200 hp x 34.5 = 6900 lbs of steam per hour
Lbs of steam can be converted to hp by dividing lbs steam per hour by 34.5
5000 lbs of steam / 34.5 = 145 hp boiler
Boiler Horse Power