Process Development Of Continuous Reactive Distillation Production Butyric Anhydride

The existing butyric anhydride is produced batchwise, it has disadvantages of theheavy raw material consumption, high energy consumption, heavy equipmentsinvestment, long production period and difficult operation etc. The reactive distillationmethod is introduced on the basis of analysis each reagent characteristics in the butyricanhydride production system, reaction combine with distillation at the same oneequipment, the equipments investment is reduced, the production is carrie outcontinuously. Because of the introduction of chemical reaction, the variables havingthe highly coupling, reactive distillation design and operation became complicated.The continuous reactive distillation production butyric anhydride is studiedsystematically by the use of the software ASPEN PLUS and the method ofcombination of experiment and computer simulation.The mechanism in which butyric acid reaction with acetic anhydride to producethe butyric anhydride is series reaction. The effect of the molar ratio of butyric acid to aceticanhydride, reaction temperature, reaction time on the reaction rate is investigatedsystematically, the reaction kinetics expression is attained on the basis of non-linearregressing the experimental data, the reaction kinetics expression is follow as: r₁=dx_A／dt=k₁C_AO(1-x_A)·(M-x_A) k₁=1.087×10⁷exp(5.64×10⁴／RT) r₂=dC_C／dt=k₂(C_C²C_A-C_DC_E／K_T) k₂=1.15×10³exp(3.3×10⁴／RT)The kinetics is shown that the first step reaction rate is very fast, conversion can beattained 99% above, the second step reaction rate is slower, the reaction is reversibleand refers the step reaction as control step.The continuous production process of butyric anhydride in the pilot plant inwhich take advantage of continuous feeding on the bottom, the fitable reflux ratio,withdrawing the acetic acid on the top and recovering the mixture of the butyricanhydride on the bottom is studied on the basis of experiment. The simulation to thisprocess is carried out by use of the ASPEN PLUS software, simulation results fit withthe experimental, It is shown that the software can be used to the process which butyricanhydride is produced by the means of reactive distillation.The process of continuous reactive distillation production butyric anhydride ispreliminarily designed, equipments parameter and process condition are designed andoptimized by use of the computer, the optimum process conditions and equipmentsparameter are determined, they are that operation pressure is 0.2atm, refux ratio is 1.3,feed ratio of acid to anhydride is 2.06:1, theoretical plates number is 16, the feedinglocation of butyric acid and acetic acid is fifth and twelfth respectively. It provides thecredible design data and operation conditions for the implement of the technology.