Why should the heating surface of power plant boiler be cleaned?

In the process of boiler operation, a large amount of ash will be produced after fuel combustion. Part of the ash is left in the furnace and discharged in the form of slag discharge, and the other part enters the tail flue with the high temperature airflow. When the airflow with ash smoke flows through each heat exchange surface of the tail flue, some ash particles will be deposited on the heating surface to form ash accumulation.

For the heat exchange surface inside the boiler, the most direct harm of ash deposition is to reduce the heat exchange efficiency, because the thermal conductivity of ash deposition is small, so once it is deposited on the convection heat exchange surface, the thermal resistance of the heating surface will increase and the heat transfer will become worse. Reduce boiler efficiency. To put it simply, dust accumulation will hinder the efficient transfer of heat from flue gas to steam, which will lead to the failure of steam temperature (low main steam temperature will affect the normal and safe production of steam turbines) and flue gas temperature (high exhaust temperature will increase exhaust loss and affect the safe operation of heating surfaces behind). Secondly, for the convection heating surface with small channel surface, dust accumulation will reduce the channel and increase the flow resistance, resulting in insufficient output of induced draft fan and reduced output of boiler.

Generally speaking, boiler ash deposition is harmful to boiler operation, and it is not only the boiler with low main steam temperature or high exhaust gas temperature that needs ash removal. Good ash removal effect can certainly improve the heat exchange efficiency, thus increasing the main steam temperature and reducing the exhaust temperature to a certain extent under the same conditions, and its benefits are far greater than the investment of the ash remover, but it is not a panacea to ensure the normal operation of the boiler.