隔板塔共沸精馏分离二氯甲烷-乙腈-水-硅醚体系

以二氯甲烷-乙腈-水-硅醚为分离体系,采用自制隔板塔小试装置,研究了共沸剂回流比和液相分配比等操作参数对隔板塔分离效果的影响。实验结果表明,当气相分配比R_v为0.5,共沸剂回流比为3时,液相分配比R_l在0.12,0.2]范围内,隔板塔分离效果较好。在实验的基础上,采用Aspen Plus软件对隔板塔共沸精馏工艺进行模拟,考察了隔板塔共沸精馏工艺最佳操作区域及节能效果。模拟结果表明,特定分离要求下,隔板塔存在一个使再沸器热负荷最小的最佳操作区域,在此最佳操作区域内,R_l和R_v相互关联,呈一一对应关系;与三塔串联简单精馏工艺相比,完成相同的分离任务,隔板塔共沸精馏工艺再沸器节能32.74%,冷凝器热负荷减少33.70%,乙腈回收率由66.47%提高到96.01%,且大幅降低设备投资。

Separation of dichloromethane-acetonitrile-water-hexamethyl disiloxane with dividing wall column by azeotropic distillation

The separation of dichloromethane,acetonitrile,water,and hexamethyl disiloxane mixture with a self-made dividing wall column(DWC)was investigated experimentally.The effects of manipulative parameters,such as azeotropic agent reflux ratio and liquid split,on the separation were discussed.According to the experimental results,the process of azeotropic distillation with DWC was simulated with Aspen Plus.The experimental results demonstrate that the separation effect is better in the range of liquid split(R_l)0.12—0.2 at vapor split(R_v) of 0.5 and entrainer reflux ratio of 3.The simulation results illustrate the optimum operation region and energy saving effect.In the optimum operation region,the thermal load of DWC reboiler is the minimum under specific requirements of separation.In the best operation region,R_l and R_v interrelate with each other.The comparison of energy consumption with that of conventional distillation sequences shows that the reboiler duty is reduced by 32.74%,the condenser duty is reduced by 33.70%,the recovery rate of acetonitrile is increased from 66.47% to 96.01%,and the cost of equipment is decreased substantially.