a waste gas separation part having an inlet opening through which a waste gas enters from a preliminary process, a direction-change valve for changing the direction of flow depending on whether the waste gas entering through the inlet opening is corrosive or non-corrosive, and a first flow pipe and a second flow pipe through which the waste gas flows by means of the direction-change valve;

a heating tank part including a plurality of heating modules for thermally decomposing the waste gas passed through the first and second flow pipes and a chamber housing the first and second flow pipes;

a scraper unit installed on the heating tank part, for scraping powder fixed to an inside surface of the chamber;

a wet cleaning part that communicates with the heating tank part and has a plurality of spray nozzles inside through which a cleaning solution for the wet cleaning of the waste gas passed through the heating tank part is sprayed; and

wherein a heat transfer pipe is provided between the second flow pipe and each of the heating modules and allows a processing gas fed from the preliminary process to be heated through the heating modules and move into the second flow pipe.