Study On The Separation Process Of Bytyl Alcohol+n-Butyl Acetate+Methyl Isobutyl Ketone System

Chemical separation process is an important part of chemical production,when the azeotropic mixtures exists in the separation system, separation difficulty will greatly increase, the simple distillation is difficult to complete.Extractive distillation、azeotropic distillation、pressure-swing distillation can effectively separate azeotrope. In this paper, the separation of butyl alcohol+n-Butyl acetate+methyl isobutyl ketone was studied. The feed was waste liquid from a pharmaceutical factory which contain methanol、acetonitrile and benzene, the mass fraction was 34%、38% and 28% separately.The residual curve in the triangle phase diagram is studied,analysis effect of different feed composition on the top and bottom product. Because the feed composition is three components mixtures,add the extraction agent or azeotropic agent can increase the difficulty of separation,so consider using the substances in the raw material as azeotropic agent.By analysis the residual curve of n-butyl alcohol- butyl acetate- MIBK, we can use the MIBK as azeotropic agent.Through the triangle phase diagram the optimal composition of the system is ascertained,so the top product can be butyl alcohol-MIBK and the bottom product is n-Butyl acetate, implementation the preliminary separation of mixtures.Azeotropic temperature and azeotropic composition of n-butyl alcohol- MIBK system both changed along with the change of pressure. After getting the proper pressure, n-butyl alcohol- MIBK azeotrope could be separated through pressure-swing distillation.The feasibility of the scheme was verified by taking rectifying column preliminary separation, and the reflux ratio on the preliminary separation column and the azeotropic agent ratio were optimized, that the optimal reflux ratio is 5, the best ratio of azeotropic agent of 1.6.Based on the whole process simulating by Aspen plus, the result indicated the operating conditions:1) The optimal operating condition for preliminary separation column was: the theoretical plate number was 55. The best feed position to the column was on the 32 ththeoretical plate. the best ratio of azeotropic agent was 1.6 and the best reflux ratio was 5.2)The optimal operating conditions for the low pressure tower: under the pressure operation of 30 kPa, the theoretical plate number was 40, and best feed position to the column was on the 25 th theoretical plate, with the reflux ratio of 4.3)The optimal operating conditions for the high pressure tower: under the pressure operation of 30 kPa, the theoretical plate number was 50, and best feed position to the column was on the 25 th theoretical plate, with the reflux ratio of 5.