PILOT STUDY ON CHARACTERISTICS OF DRUM DRYING FOR DEEP-DEHYDRATION DYEING SLUDGE

The characteristics of drum drying for deep-dehydration dyeing sludge was experimentally studied by utilizing gas from oil burning，which was used to simulate flue gas from thermal power plants． The effect of rotary speed of drum，gas flow rate and drum length on the sludge drying performance and thermal efficiency of dryer was investigated． Besides，the impact of inlet gas temperature on the pollutants emission from exhaust gas was also discussed in this paper． The results showed the rotary speed of drum played an important role in determining sludge retention time in the dryer． It was also the most important impact factor affecting the moisture content of final product，whereas the gas flow rate was the main factor determining the thermal efficiency of dryer． For deep-dehydration dyeing sludge，the volumetric heat transfer coefficient of the dryer was 0. 361 ～ 1. 168 kJ /( m3·s·℃) ． The gas flow rate would affect the volumetric heat transfer coefficient of the dryer to some extent， whereas the rotary speed of drum had little impact on it． All the pollutants emission concentrations met national emission standards with an exception that the NH3 and odor concentrations in drying exhaust were higher than that of Rank 3 in factory pollutants emission standard． For controlling the release of NH3 ，H2 S and BTEX during sludge drying，the drum drying temperature of deep-dehydration dyeing sludge should be lower than 190 ℃．