Study On The Production Of The Butyric Anhydride Using Single Reactive Distillation Column With Internal Material Circulation

For reactive distillation(RD)processes,one of reactants needs to be excessive to promise the stability of discharge compositions,so traditional reactive distillation processes usually involve an additional distillation column to separate the excessive reactant with other products.In this thesis,we propose a novel single reactive distillation column(SRDC)process to remove the additional distillation column of the traditional RD process and reduce equipment cost of RD processes.To develop an SRDC process,the profile of boiling points of a reaction is analyzed first,then a proper excessive reactant is chosen.By carefully tuning heat load of the cooler or reboiler of the SRDC,the chosen excessive reactant can be separated from the reaction products in rectifying section or stripping section and recycles in the RD column.To validate the effectiveness of the proposed SRDC,a reaction of butyric acid and acetic anhydride for producing butyric anhydride is implemented with the SRDC.the optimum method is sensitivity optimization,the optimum reflux ratio is 1.5,and the optimum feed position of butyrate is 5th,the optimum feed position of acetic anhydride is 12 th and the optimum residence time is 0.1 hr.Three scenarios of the SRDC with different excessive reactant were simulated and evaluated,and the optimal scenario,namely,the butyric acid,overdose 10%,is selected.Comparing to the traditional RD processes from literature,the optimal SRDC process can reduce 24% of total annual cost.The effect of different excess degree of butyric acid on the purity of the product was studied.It is found that the excess degree of butyric acid had no effect on the purity of the product.Therefore,the SRDC with excess butyric acid of 10% was selected dynamically.To determine the control structure of the optimal SRDC,the sensitive trays were chosen by using a gain matrix analysis and singular value decomposition.Four control schemes,i.e.,CS-TTT,CS-TTC,CS-TCC and CS-CCC,were implemented with ASPEN Dynamics.Fluctuations of the feed rate of butyric acid were implemented to validate the anti-interference performance of the four control schemes,the results show that CS-TTC is the optimal scheme.The scheme can reach the stable value set before 4hours,the time is short,and there is no deviation,the product purity is strictly stabilized at the set value,and the scheme is economical and practical.