Study On Ethanol Dehydration With Methanol By Azeotropic Distillation

Ethanol, being an excellent organic solvent, is widely used in chemical,pharmaceutical and other fields. As one of the most effective ethanoldehydration methods, azeotropic distillation has a simple process, a highdegree of mechanization, and a high quality of product. This article is basedon solvent dehydration process for produced ethanol, methanol and water ina pharmaceutical companies, azeotropic distillation process for thedehydration of ethanol containing methanol is investigated.A two-tower and a four-tower ethanol dehydration azeotropic distillationprocess are proposed, combined with the general principles of entrainerselection, cyclohexane is selected as the entrainer. Aspen Plus is used tosimulate the process, and NRTL model is adopted to calibrate thenon-ideality of the liquid, the results can meet separation requirements..The two-tower azeotropic distillation process is simulated when feedcomposition of methanol is varied. The results show that the ethanoldehydration with methanol can be realized by the two-tower process. Whenfeed contains methanol, energy consumption in dehydration column andentrainer recovery column are both higher than that without methanol in thefeed. With the increase of methanol concentration in the feed, the yield ofethanol in the two-tower process is reduced, and the energy consumption ofethanol dehydration column and entrainer recovery column are increased.In order to improve the yield of ethanol, an improved process offour-tower process is provided, ie, a methanol separation column and anethanol recovery column is established on the basis of two-tower process.The four-tower process is simulated and the results show that it can not onlyrealize ethanol dehydration, the yield of ethanol can also reach99%. Withthe increase of mass concentration of methanol in the feed, the total energyconsumption of four-tower is increased.Based on the simulation results of four-tower process, an industrial scaledesign of ethanol dehydration azeotropic distillation containing methanol iscarried out. The height, diameter and feed location of each tower isdetermined, and the heat exchangers are calculated and selected.