乳酸甲酯双隔板反应隔壁塔的设计与控制

Design and control of methyl lactate dividing-wall reactive distillation columns with double dividing-walls

常规蒸馏塔分离具有最不利相对挥发度排序的四元可逆反应物系,反应物会在塔顶和塔底聚集,对反应塔侧线采出浓度要求较高。为解决这一问题,将反应塔和分离塔耦合到一个塔中,形成新的双隔板反应隔壁塔结构。基于乳酸和甲醇的酯化反应,采用反应物过量技术,在Aspen Plus中分别设计并优化2种反应物过量下的双隔板反应隔壁塔结构。与常规反应分离结构对比表明:甲醇过量的外部环流双隔板反应隔壁塔的年总投资节省约28.4%。针对甲醇过量的结构,采用4点温度控制策略,在进料流量和组成发生扰动的情况下,产物浓度能在较快时间内恢复到误差允许范围内的稳定值。因此双隔板结构的隔壁塔能有效降低能耗和投资并且具有较好的可控性。

Adopting the conventional reactive distillation column to separate the quaternary reacting mixtures with the most unfavorable ranking of relative volatilities,some reactants would accumulate at the top or bottom of the column and the product of the reactive distillation column must be kept at a high concentration.In order to solve this problem,two columns were coupled into one shell,thereby leading to a novel double dividing-wall reactive distillation column structure.Based on the esterification reaction of lactic acid and methanol,the structure of a double dividing-wall reactive partition distillation column with excess reactants was designed and optimized in Aspen Plus.Compared with the conventional reaction separation structure,the results show that the annual total investment(TAC)of the double dividing-wall with methanol excess is reduced about 28.4%.For the double dividing-wall reactive distillation column(R-DWDC)with excess methanol,a four-point temperature control strategy is adopted.Under the condition of step disturbance of feed flow rate and feed composition,the product concentration can recover to a stable value within the allowable error range in a short period time.