It is mainly composed of double seal sleeve for fixing the spiral blades,  material-feeding and air-exhaust device, water intake and drainage device, transmission device and a base. When the sleeve is driven by a transmission device, the high temperature slag discharged from the boiler moves forward guided by the spiral blades, the cooling water evenly pass through the seal clearance of the sleeves, and the natural cooling air also passes through the sleeves constantly, thus making the hot slag cooled gradually.