Heat integration and dynamic control for separating the ternary azeotrope of butanone/isopropanol/n-heptane via pressure-swing distillation

In this paper, an economical and robust triple column pressure-swing distillation (TCPSD) process for the separation of butanone/isopropanol/n-heptane (MEK/IPA/n-heptane) ternary azeotrope is studied. The pressure sensibility of MEK/IPA/n-heptane is qualitatively analyzed by residue curve map (RCM), which demonstrated that the economical design for separating the ternary mixture via TCPSD is feasible. The TCPSD process was optimized by the minimum total annual cost (TAC) by using the sequential iterative algorithm, meanwhile, the heat integration is investigated to reduce the energy consumption. The results showed that the partial heat integration can reduce TAC by 11.89%, and the full heat integration can reduce TAC by 39.97% by parameter optimization. The dynamic control strategies that can resist 20% of feed disturbances were proposed for the conventional process, partial heat integration and full heat integration, respectively. The designed and optimized full heat integration scheme is found to be an optimal scheme with good anti-disturbance performance and the best economic performance. This study provides a new train of thought for the separation of MEK/IPA/n-heptane and has meaningful practical application value.

Automated summary

This study investigated an economical and robust triple column pressure-swing distillation (TCPSD) process for separating the butanone/isopropanol/n-heptane ternary azeotrope. By optimizing the process for minimum total annual cost (TAC) and investigating heat integration, it was shown that TCPSD is feasible for separating the ternary mixture. Heat integration can significantly reduce TAC, with the fully integrated scheme showing the best economic and anti-disturbance performance.