How Does a Boiler Economizer Work?

How Does a Boiler Economizer Work?

A boiler economizer is a device that improves the thermal efficiency of a boiler by utilising the waste heat in the flue gas of the boiler and transferring it to the feed water or air of the boiler. Here is how a boiler coal economiser works:

Flue Gas Heat Recovery: In a boiler, when fuel is burned, the flue gas produced carries high temperature heat. These flue gases are usually discharged directly into the atmosphere. The main function of the boiler economiser is to capture the heat in these high temperature flue gases.

Heat exchange process: The interior of the economiser usually consists of a series of tubes or sheet-like surfaces. Flue gases flow through these pipes or surfaces inside the economiser and come into contact with the walls or surfaces. During this process, heat from the flue gas is transferred to the pipes or surfaces, resulting in a decrease in the temperature of the flue gas.

Preheating the feed water or air: At the same time, the feed water or air from the boiler flows through the other side of the economiser. On this side, the cold feedwater or air is warmed by the tubes or surfaces that have undergone heat exchange, thus preheating the feedwater or air. This allows the boiler to require less fuel to receive this preheated media, which has been pre-heated, so less fuel is required for the same energy output.

Reduced Flue Gas Emission Temperature: As the economiser recovers heat from the flue gas, the temperature of the flue gas drops. This not only helps to increase the thermal efficiency of the boiler, but also reduces the temperature of the flue gases when they are discharged into the atmosphere, reducing the impact on the environment.

In this way, the boiler economiser lowers the temperature of the flue gas and raises the temperature of the feed water or air, which achieves the recovery and reuse of heat energy, thus increasing the thermal efficiency of the boiler and reducing energy consumption.