Sensible Heat Addition
Feed Water Pump.
The first step is to get a constant supply of water at high pressure into the boiler. Since the boiler is always at a high pressure. ‘Boiler feed water pump’ pumps the water at high pressure into the boiler from the ‘feed water tank’. The pump is akin to the heart in the human body.
Pre-Heating
'Feed water heaters’, using extracted steam from the turbine, adds a part of the sensible heat even before the water enters the boiler.
Economiser.
Most of the sensible heat is absorbed in the Economiser. These are a set of coils made from steel tubes located in the tail end of a boiler. The hot gases leaving the boiler furnace heat the water in the coils. The water temperature is slightly less than the saturation temperature. From the economiser the water is fed to the 'drum'.
Pre-Heating & Economiser