Sludge is a solid precipitate produced by water and sewage treatment processes. Its main characteristics include high moisture content, high organic matter content, easy decomposition and odor, and fine particles with small specific gravity, presenting as a colloidal liquid. According to the source, sludge is mainly divided into: domestic sewage sludge, industrial wastewater sludge, and water supply sludge. The disposal and treatment of various types of sludge has become a persistent problem that restricts urban development and sanitation.

　　A small sludge dryer is an indirect heating low-speed stirring type dryer, which has two or four hollow rotating shafts inside the equipment. The hollow shafts are densely parallel arranged with fan-shaped wedge-shaped hollow blades, and the structural design is special and ingenious. The relative rotation of the shaft body cleverly achieves the self-cleaning effect of the sludge on the shaft body using the principle and structure of the same angular velocity but different linear velocities, greatly preventing the phenomenon of holding the shaft during the sludge drying process.

　　Below, we will introduce the characteristics of small sludge dryers:

　　1. Due to the fact that the heat required for equipment drying relies on indirect heating through heat conduction, the drying process does not require or only requires a small amount of gas to remove moisture. It reduces the heat loss carried away by the airflow and improves the heat utilization rate, making it an energy-saving drying equipment.

　　2. Stirring and mixing make the materials turn violently, thus obtaining a very high heat transfer coefficient, so the floor area and space are very small, saving the plant infrastructure costs. During the drying process, the amount of gas used is low, the flow rate is low, and the amount of dust carried away by the gas is small. Therefore, the recovery of gas dust after drying is convenient, and the volume of the recovery equipment is small, which can save equipment investment. For drying processes that require solvent recovery, the solvent concentration can be greatly increased. Due to the unique structure of the blade, the material undergoes alternating squeezing and relaxation during the drying process, strengthening the drying process. The material filling rate in the drying room is very high, which can reach 80% -90%. The residence time of the material can be adjusted by adjusting parameters such as feeding speed, mixing shaft speed, and material filling degree, from a few minutes to a few hours.

　　3. It can be used for sludge drying in various fields such as municipal sludge, printing and dyeing sludge, papermaking sludge, electroplating sludge, etc. It has high thermal efficiency, wide application range, low operating cost, and can also achieve continuous production.