Control analysis of batch reactive distillation column with intermittent fed

This work addresses control issues of a batch reactive distillation for the production of methyl lactate via esterification reaction. The particular challenge of this classic process intensification case lies on that reactant is lighter than product and is easier to be taken away from the reaction, in such a way the conversion of loaded reactant is shrunk; to overcome this drawback, excess of reactant is typically added in the reactive zone. In order to guarantee a high conversion, a practical control approach is proposed: maintaining the maximum allowed temperature of the reaction through reboiler duty, and intermittently feeding the reactant excess, which is driven by maintaining a fixed amount of reactant in reboiler. The controllers for this two-point control configuration are conventional PI linear. The results in a simulation framework show that a reactant conversion greater than 90 % is reached with ease. When the product is the lightest component in the mixture, the equilibrium reactions are favoured because the products are removed as the reaction proceeds; as a result, conversion is increased; however, when a reactant is the lightest component there are problems causing low conversion, and to overcome the problem, excess of such a reactant is fed in the reactive zone. Control strategy (one and two-point control) is proposed such a practical solution and novel conversion control is explored to ensure a 90% conversion. Also, the maximum temperature of the process is 393,15 K. The temperature in reboiler is satisfactorily controlled using the reboiler duty as the input control. The conversion set point (90 %) is reached with an intermittent fed of excess reactant, in this loop the control input is the feed.