The flue gas of steel, coking, chemical industry and boiler is mostly sprayed or wet desulfurized before discharge, and the temperature drops to 45~80 ℃. At this time, the flue gas is saturated wet flue gas, and the flue gas contains a large amount of water vapor, which contains ablative salt, sulfur trioxide, gel dust, micro dust, etc. (all important components of haze).
Smoke whitening is the process of removing some of the moisture from the smoke before it is released into the atmosphere, in order to prevent the chimney from emitting "white smoke" and reduce its impact on the environment. Normally, flue gas whitening is achieved by first cooling and condensing the flue gas, and then heating it. The main component of the flue gas desulfurization unit is the BXB plate heat exchanger, which uses ambient air to cool the flue gas and remove moisture from it. Afterwards, the flue gas is reheated to increase its temperature, so that it does not produce "white smoke" when discharged into the atmosphere.