EXPERIMENTAL STUDY ON SLUDGE DRYING WITH HEAT-PUMP DEHUMIDIFIER

The sludge drying with heat pump test dryer was experimental studied in this paper. Through the tendency of Moisture Content (MC), air temperature and relative humidity changing, the drying rate, dewatering efficiency of heat-pump, and energy recycling rate were analyzed for the minitype heat-pump dryer system. The results showed that it was evident of the energy saving in heat pump sludge drying. The average energy recycling rate was 36.3% with MC from 46.8 % to 5.4 %. The energy recycling rate is 45.3%, 28.8% and 14.75% in initial stage (MC 46.8%~19%), medium stage (MC 19%~11%) and later stage (MC 11%~5.4%) correspondingly. The fastest drying stage is in constant drying period with MC between 30.4% to 18.7%, It is 56.5%, 12.8% and 23.4% faster than the preheating period (MC 46.8%~42.8%), accelerating period (MC 42.8%~30.4%) and decelerating period, respectively. Average drying rate rises with the temperature increasing and Relative Humidity decreasing in drying chamber.