What is the boiler horsepower of a boiler generating 21,500 lbs of steam per hour at 155 psi?
The factor of evaporation is 1.08.
BHP = (LB/HR*fe)/34.5
                               BHP = (LB/HR*fe)/34.5
                               BHP = 21500 * 1.08 / 34.5
                               BHP = 673
Where,
                               BHP      boiler horsepower
                               Lb/Hr     pounds per hour
                               Fe          factor of evaporation (can be assumed to be equal to 1)