Cast Iron Economizer Air To Air Heat Exchanger Flue Gas Heating Elements

Cast iron economizer for boiler raise efficiency of a boiler flue gas heat exchanger

Boiler flue gas heat exchanger working principle

1. As the name implies the tri-sector pre-heater design has three sections. Use for flue gas. One for primary air (used for drying and transport of coal through mill to the burner) another for secondary air (additional air for combustion around the burners). These helps in avoiding wastage of heat pick up by air due to primary air flow and also help in selecting different temperatures for primary air and secondary air.

2. Thousands of these high efficiency elements are spaced compactly arranged with in 12 sectors shaped compartments for heater size from 24.2 to 27 inches, and 24 sector shaped compartments for heater size from 28 to 33 of radially divided cylindrical shell called the rotor. 

3. The housing surrounding the rotor is provided with duct connections at both ends and is adequately sealed by radial and axial sealing members forming an air passage through one half of the pre-heater and a gas passage through the other.

4. As the rotor slowly revolves the mass of the elements alternatively through the air and gas passage, heat is absorbed by the element surfaces passing through the hot gas stream. These are the same surfaces are carried through the air stream. They released the stored up heat thus increasing the temperature of the incoming combustion or process air.

Boiler auxiliary air preheater Introduction

1. Air pre-heater is a heat transfer surface in which air temperature is raised by transferring heat from other media such as flue gas .Hot air is necessary for rapid combustion in the furnace and also for drying coal in milling plants. So an essential boiler accessory which serves this purpose is air pre-heater.

2. The air pre-heater are not essential for operation of steam generator, but they are used where a study of cost indicates that money can be saved or efficient combustion can be obtained by their use. The decision for its adoption can be made when the financial advantages is weighed against the capital cost of heater in the present paper we have taken up the operation and performance and also air heater leakage, corrected gas outlet temperature and finally gas efficiency has been calculated

Tubular type Air Preheater

1. Tubular preheaters consist of straight tube bundles which pass through the outlet ducting of the boiler and open at each end outside of the ducting.

2. Inside the ducting, the hot furnace gases pass around the preheater tubes, transferring heat from the exhaust gas to the air inside the preheater.

3. Ambient air is forced by a fan through ducting at one end of the preheater tubes and at other end the heated air from inside of the tubes emerges into another set of ducting, which carries it to the boiler furnace for combustion.

Details