Boiler accessory with the chematic sketch of Air Pre-heater

Boiler accessories used as an integral part of a boiler.These are used to increase the efficiency of the boiler.some of the important boiler accessories are air pre-heater,feed pump,injector,economizer,superheater and steam trap.

Air Pre-heater : It is one of the important accessory of the steam boiler.It is mainly used to raise the temperature of air before it enters into the furnace.It is a waste heat recovery device which abstracts heat from the hot flue gases going to the chimney.This abstracted heat is transferred to the air before entering into the combusion chamber.It is located in the path of the hot flue gases going to chimney.

A simple Schematic diagram of a tubular type air preheater is shown in figure.It consists of a large number of vertical tubes through which the hot flue gases enter from the top of the shell and flow downwards through the tubes.The atmospheric air enters in to the shell from the bottom and flows upwards over the tubes.A fan is used to admit air in to the shell.The shell consists of baffles which allow the air to go through several passes to reduce frictional resistance.The atmospheric air flowing from bottom gets heated by hot flue gases flowing downwards.The hot air leaves the shell from is top.Thus,air gets initially heated before being supplied to the furnace or combustion chamber.

Tubular Type Air Preheater