Design And Control Of Reactive Distillation Process To Produce Ethyl Methyl Carbonate

A process to produce ethyl methyl carbonate is presented by using reactive distillation.O-xylene is selected as a suitable entrainer by comparing infinite dilution relative volatilities.The process is improved to realize the recycling of excess reactant and extractant,and an effective way to produce the by-product diethyl carbonate is provided.The chemical simulation software Aspen Plus is used to simulate the process producing ethyl methyl carbonate in steady-state with appropriate thermodynamics method and dynamic model.The effects of feed ratio,feed locations and reflux ratio on product purity and reboiler duty are investigated,and then reaction conversion,selectivity and energy consumption are optimized.Total annual costs are 1.38 million dollars in final process.Under such process conditions,the yields of ethyl methyl carbonate and diethyl carbonate reach 20.1 million kg/year and 7.5 million kg/year with purities of 99.8%.Singular value decomposition analysis is used to choose temperature controlled plates.Four kinds of control structures are proposed.Aspen dynamics is used to test control performances when setting feed flow and composition disturbances.Control structure 1 take an independent control structure in each column,in which sensitive plate temperatures range largely and take a long time to restore setting points.Control structure 2 introduces a cascade control of the temperature controller with the reboiler duty which is in proportion to the corresponding feed flow rate,and reflux rate is feedforward controlled.Combining CS1 with CS2,interconnected CS3 is proposed,in which sensitive plate temperatures are controlled timely.But the product purities cannot be controlled effectively by using temperature control structures.CS4 is proposed using temperature different control to ensure product purity.The results indicate that CS4 can handle disturbances more effectively.