Study On Simulation And Modification Of Propane And Propylene Recovery From Vent Gas In Butyloctanol Unit

The recovery of propylene and propane from vent gas in butyloctanol process is an important process in producing butyloctanol.In this thesis,the propylene and propane distillation unit in 200,000t/y butyloctanol process in shandong Hualu-Hengsheng Co.Ltd.Was simulated and modified.The main results and conclusion are as follows.1,The vent gas recovery process of butyloctanol was analyzed in detail and systematically.It was observed that the lower purity of propylene in tower top and the loss of propane in tower bottom are the major problems and the reasons were uncovered.The thermodynamic analyses in distillation process were performed.All these work set up the base for the following simulation and modification.2,Aspen was employed to simulate the propane and propylene distillation unit.The tower plate number,feed position and reflux ratio were determined,with 93 plates for each distillation tower.It was observed that the major reason for poor separation efficiency is the unsufficient plate number,which can be improved through improving tower plate effiency and modifying the reboiler.3,the heat exchangers were determined with HTRI,in which the type of heat exchanger was selected and the problems of the unsufficient heat load and large water cycling were fexed up.4,The current propylene and propane distillation unit was modified.The original plates were replaced by high-efficient plates,two plates were added for up-tower and down-tower,heat exchangers and heat medium were changed,and the equipment distribution and control were also modified.5,After the modification,the propylene content in tower top is up to 99.3%-99.6%and the propane content in tower bottom is lower to 0.37%-0.6%,with 2,456,470 RMB/y economic benefits.The modification goal is achieved.