The Application of Dehumidification Process in Sludge Drying

摘要

According to the govemment data, there was more than 3 million tons sludge cake produced each year in Taiwan. Most of them were dumped without any treatment. As the available landfill sites decreased, the disposal fee increased dramatically. Therefore the minimization and treatment of sludge cake became a very important issue. Drying is an effective process to reduce weight and/or volume of de-water sludge cake. Usually sludge drying was carried out with high-temperature air stream. Since most of the local enterprises produced only a small amount (less than 2 tons per day) of sludge cake, hot air drying was not well accepted due to the high capital cost. Dehumidification is a sophisticated process in ambient air treatment. ITRI/CESH developed a sludge drying system that uses dehumidifier to condense water content evaporated from sludge cake. The drying air is re-circulated and therefore no flue gas emitted. A special design rotary drum dryer was used to enhance air-sludge contact and therefore increase drying efficiency. The system was used to dry sludge cakes produced from two petrochemical plants. The design and operation results are reported in this paper.