What is the heat loss in the operation of coal-fired boiler?

The heat transfer efficiency of coal-fired boiler is not ideal mainly because of its serious heat loss which mainly comes from five aspects. It is impossible to completely avoid the heat loss. However, it can be controlled via correct methods to reduce the heat loss and improve the heat transfer efficiency of coal-fired boiler.

The exhaust gas heat loss of coal-fired boiler is caused by the flue gas removed by final stage heat exchanger. The flue gas will take away a part of heat, mainly including the heat taken away by dry flue gas and the sensible heat with water vapor in the flue gas. What's more, if the combustible gas in the coal-fired boiler is not completely burned, there will be heat loss as well. Therefore, this kind of heat loss mainly depends on the content of incomplete combustion products in the exhaust smoke.

Now that incomplete combustion of combustible gas will cause heat loss, the incomplete combustion of solid in the coal-fired boiler will also cause a certain amount of heat loss. This kind of heat loss is mainly caused by the combustible ash and slag and pebble coal removed by medium speed coal mill.

In addition, there is also the heat dissipation loss involved in the coal-fired boiler because the furnace wall, metal structure, pipes and tubes will lose heat to the surrounding environment. Usually, the heat loss amount of coal-fired boiler is related to the heat load of boiler unit.

In addition to the above four kinds of heat loss, the physical heat loss of ash and slag is also a kind of heat loss of coal-fired boiler. It specifically refers to the percentage of sensible heat which is taken away when the slag, fly ash and settled ash are removed from the boiler equipment in the whole input heat. Therefore, the heat loss can be reduced if the fuel in the coal-fired boiler can realize sufficient combustion.