Sewage sludge drying based on heat pump

Abstract

A suit of low temperature test dryer for sewage sludge drying based on heat pump was put forward in this paper. Principle and characteristic of this equipment was introduced. Sewage sludge drying mechanism were briefly summaried from literatures. Factors such as drying air temperature and flow speed that effect sewage sludge drying process were discussed. Drying temperature and flow speed both contribute positively to drying speed in initial drying section while contributing little in the evening section of drying process. Change of superficial morphology during the drying process was analyzed. Economy of this low temperature dryer based on heat pump was discussed. Results show that the operation cost is equal to the operation cost of the dryer with coal as heat source, while is less than half of the dryer with electricity or natural gas as heat source.