Air preheater is mainly followed the principle of energy saving. It is one of the boiler supporters. It helps to increase the boiler efficiency and improvement in boiler efficiency of 1% is done only by increasing in combustion air temperature for every 220 0C.
There are two types of combustion air preheater.
1) Recuperative Air Preheaters – designs include tubular, plate and heat pipe.
2) Regenerative- designs include the rotating matrix.
Recuperative Air Preheaters
Tubular air heaters are aimed at maintaining performance within the limits and minimizing corrosion and leakage. So the maintenance is done by regular monitoring of the system, cleaning equipment, temperature control equipment, steam preheat coils. The cold end temperature control equipment is should maintain in a good working condition. Installing sleeves inside the cold end tubes for repairing process. The sleeves will increase draft losses and lowering tube metal temperature.
Regenerative Air Preheaters
Regenerative design is used in the regenerative air preheaters. The highest using design is rotating matrix. The major portion of the rotary regenerative air preheater is a cylindrical rotor structure. This rotor is made up of rotor post and radial plates. The rotor is rotated by using of a pin rack mounted on the outside side of the rotor shell. The main advantage of using the regenerative design air preheater is the simple and more flexible.