Desulfurization mainly removes sulfur dioxide in flue gas, and denitrification primarily reduces nitrogen oxides. Desulfurization generally uses the limestone-lime-gypsum method, and denitration generally uses catalyst oxygen reduction to convert nitrogen oxides into nitrogen for emission. The desulfurization and denitrification fan is a forced ventilation system when the desulfurization and denitration system is working. Its compact structure, high operating efficiency, and high pressure match the current desulfurization and denitration system for gas sealing.