The disc dryer uses the double-sided heat transfer of each disc to provide a large heat exchange area in a small space, which makes the disc dryer compact. The rotating frequency of the disc is adjustable, and the rotating speed is about 5R / min, so the wear is very small. The disk surface is perpendicular to the shaft, so its rotation does not affect the flow direction of sludge. There are some small blades at the edge of the disk of the disk dryer, which have a certain inclination angle, which not only helps the directional flow of sludge, but also plays the role of mixing. The shell is immovable. It contains sludge and water vapor generated by sludge evaporation. There is a fixed scraper on the inner wall of the shell. The scraper is very long and extends into the gap between the discs to prevent large pieces of sludge from solidifying on the discs. Similar to the blades on the disc, the fixed scraper also plays the role of stirring.