Abstract: The effects of the number of mesh belt layers and the thickness of the mesh belt sludge spreading on the return air temperature, humidity, aqueous output capacity, and pressure drop were investigated. The optimum working conditions applicable to the mesh belt of a sludge low-temperature dryer for sludge particles were evaluated. The result indicated that in four-layer mesh（a condition of four-layer a）, the sludge particles in the 0.60 m/s mesh belt air velocity had the lowest water yield of 20.7 kg/h after drying. Compared with the maximum water yield (19.7 kg/h) of the sludge particles in the two-layer mesh belt after drying , it was still 5.1% higher. It could be shown that the water yield after drying of the four-layer mesh belt sludge particles was more, and the drying effect was superior. Under the influence of the number of layers of mesh belt, the water yield of the four-layer mesh belt could be improved by 60.1% when compared to the two-layer mesh belt. Under the impact of the thickness of the mesh belt sludge spreading, the maximum output capacity of the four-layer mesh belt could be increased by 11.3%. And the maximum output capacity of the two-layer mesh belt could be increased by 44.0% when compared to the minimum output capacity. The maximum increase of the water yield under 0.90 m/s mesh belt air velocity could be raised by 36.0% when compared to 0.60 m/s. The study founded that the number of mesh belt layers had the greatest influence on the dehumidification efficiency of sludge low-temperature dryer.

Key words: sludge drying, dehumidification efficiency, number of mesh belt layers, mesh belt thickness；mesh belt air velocity