Research on an Energy-Efficient Drying Process. Final Report

摘要

Objective was to investigate the feasibility of using a membrane-based process for the recovery of energy from dryer-exhaust streams. The membrane allows the separation of a hot, moist, dryer-exhaust stream into a low-moisture air stream and a low-pressure stream of high-purity water vapor. Conventional vapor recompression can then be used to compress the water vapor to a usable quality, allowing the latent heat to be recovered using a condenser. The recovered heat can then be returned to the dryer or used elsewhere in the plant. In many cases, this scheme allows the recovery of eight to ten times as much energy as is required to operate the compressor. Laboratory experiments indicate that the process is feasible. The successful completion of a long-term field test at a Crown Zellerbach paper mill suggests that the membranes are robust enough to withstand operation on actual industrial dryer-exhaust streams. Design and economic optimization studies indicate that the process is only marginally economical. (ERA citation 11:040841)