Gas to gas heat exchangers are basically used for the purpose of heat recovery of hot outgoing exhaust air, and ingoing cold fresh air or process gas. They are used to prevent heat loss by the fuel gas, cause, if the gas looses too much of heat , by the time it reaches the stack it does not have enough energy to disperse properly. Gas-to-Gas Heat Exchangers possess same kind of designs as air pre-heaters. These exchangers consists of numerous pieces of equipment that are specifically designed to clean up the gas before it exits the power plant through the stack.
The Gas to Gas heaters are normally shallow, since, the amount of heat transferred is small. They operate in low temperatures. A high quality air to air Heat Exchangers are designed with the consideration that there will be a huge amount of sulfuric acid condensation. They also possess enameled element and flake glass lining in order to prevent the equipment from corroding away.
Gas to Gas Heat Exchangers are located just before the stack. The working of the exchanger involves salvaging of heat from the gas prior to its moving into the scrubber in order to remove sulfurs and then puts it back into the cleaned flue gas. The process results in a cleaned flue gas with enough heat to rise out of the stack and disperse.
They consist of closed insulated piping systems through which a heat transfer fluid (often glycol) is pumped. This fluid picks up heat in coils or finned tubes installed in the hot exhaust air stream and rejects heat by way of coils into the cold incoming air stream.