冷凝法回收有机溶剂的优化设计

采用冷凝技术回收挥发性有机溶剂操作简单,回收成本低,工作原理为将废气冷却或加压到有机气体的露点温度以下,使其液化,而从废气中分离出来。根据其工作原理设计出一台有自动控制系统的管壳式换热器的样机(冷冻式干燥机),并利用该装置回收了乙酸乙酯、乙醇。通过试验测试了不同冷凝温度、换热时间对回收效率的影响,冷凝温度依次为-18,-15,-7℃,换热时间分别为5,10,20,25,30,40 min。试验结果表明:温度越低,回收率越高,-18℃时乙酸乙酯的最高回收率为70%,乙醇为96.77%;换热时间太长或太短回收效果均不理想,最佳换热时间为20—25 min。采取此种工艺回收溶剂效率得到提高,进一步研究工作压力、进气浓度等因素的影响,找到一个最佳条件可最大化回收有机溶剂。

Optimization design of organic solvent recovery with condensation process

The recovery of volatile organic solvents in condensation process is simple and at low cost.Its operating principle is that waste gas is cooled or pressurized to the temperature below the dew point of organic gas,and then the organic gas is liquefied and separated from the exhaust.According to the principle,a prototype of shell and tube heat exchanger with automatic control system was designed(called refrigeration drier),and the recovery process of ethyl acetate and ethanol was studied.The effects of condensing temperature and heat-exchange time on the recovery efficiency were researched,in which temperature was-18,-15,-7 ℃ respectively,and the time was 5,10,20,25,30,40 min.The results show that the lower the temperature is,the higher the recovery rate is,the highest recovery rate of ethyl acetate is 70%,the rate of ethanol is 96.77% at-18 ℃;the recovery effect is unsatisfactory when time is too long or too short,and the preferred heat-exchange time is 20-25 min.The recovery rate is improved with the condensation process,and higher recovery rate could be obtained when operation pressure,inlet concentration and other factors are further studied.