Design alternatives and control performance in the pilot scale production of isoamyl acetate via reactive distillation

In the present work, two different reactive distillation (RD) designs for the pilot scale production of isoamyl acetate are studied by means of steady state simulations. In the first design near stoichiometric amounts of acetic acid and isoamyl alcohol are fed directly to the reactive and rectifying sections of the RD column. On the second design, acetic acid in excess and isoamyl alcohol are first fed to a continuously stirred tank reactor (CSTR) and its product stream is fed to the reactive section of the column. Among different optimization variables, the overhead vapor flowrate appears to be the most influencing variable in the energy requirements, and its value and composition are responsible for the two liquid phase formation in the condensate. This variable also determines the global performance of the process schemes yielding a >99% conversion and >99% isoamyl acetate mass purity of the bottoms product. Having a CSTR upstream to the RD column allows an operation with a lower overhead vapor flowrate, thus a lower energy consumption is achieved for this design. Indirect composition control of the bottoms product in both designs has been implemented by controlling the temperature of one of the reactive stages. For the design comprising a CSTR, a better dynamic response and process stabilization has been observed for a change in the production rate. This control strategy also showed a good disturbance rejection in the dynamic behavior of the main process variables. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.