Boiler working principles

Boiler working principles: Distilled water is fed into the water drum under pressure by the boiler feed water pump. Burner will fire fuel oil to heat up the water through smoke tubes. Water upon boiling will evaporate into steam which will flow through the main steam stop valve to various uses. For a composite boiler , at sea, the main engine exhaust will be channeled through the boiler smoke tubes instead of the burner flame exhaust. Hence the water in the drum is heated up by the main engine exhaust heat to save fuel consumption.