Dynamic vapor recompression in a reactive batch rectifier: Analysis and nonlinear control

This work proposes a dynamic vapor recompressed batch reactive rectifier (VRBRR) for the butyl acetate system that operates with a dynamic compression ratio (CR). In this configuration, along with the CR, we manipulate either the overhead vapor inflow rate to the compressor or the external heat input to the reboiler for the purpose of coupling the thermal arrangement with the existing batch tower. To improve the product purity and the amount of distillate collection of the dynamic VRBRR, we further formulate a nonlinear extended generic model controller (EGMC) that requires state information for its simulation. For this, we develop a closed-loop high gain observer (HGO) for estimating a limited number of states, exclusively required for the EGMC. This results in a significant structural mismatch that is taken care of by the hybrid EGMC-HGO system. For the representative butyl acetate system, it is investigated that the proposed nonlinear controller outperforms a traditional PI controller in regulating the dynamic VRBRR.