The flue gas of steel, coking, chemical industry and boiler is mostly sprayed or wet removed before discharge, and the temperature drops to 45~80 ° C. At this time, the flue gas is saturated wet flue gas, which contains a large amount of water vapor, and the water vapor contains ablative salt, SO, gel dust, micro dust, etc. (all important components of haze).

Assuming that the condition point of the wet flue gas at the chimney outlet is A and the condition point of the ambient air is E. During the process of mixing the wet flue gas with the ambient air, the wet flue gas becomes saturated at point B, and then the condition point changes along the saturation curve BCD. As the temperature of the wet flue gas decreases, the supersaturated water vapor in the wet flue gas condenses into liquid small water droplets, which refract and scatter light, As a result, the smoke plumes at the exit of the smoke chart appear white or gray, forming wet smoke plumes.

Smoke whitening scheme

Smoke whitening refers to the removal of some moisture from the smoke before it is discharged into the atmosphere, in order to prevent the smoke from emitting white smoke and reduce its impact on the environment. Normally, smoke whitening involves first cooling and condensing the smoke, followed by heating it. The main component of the air flue gas whitening unit is the BXB plate heat exchanger. In the plate heat exchanger, ambient air is used to cool the flue gas, thereby precipitating water from the flue gas. Afterwards, the flue gas is reheated to increase its temperature, so that there will be no "white smoke" when the flue gas is discharged into the atmospheric environment