Evaluation and control of energy‐efficient processes for separating epichlorohydrin‐oriented quaternary system

Abstract

BACKGROUNDThe direct epoxidation of allyl chloride is a clean and efficient synthesis method for producing Epichlorohydrin (ECH), which is a crucial organic intermediate widely used in the fields of renewable energy and aerospace. However, the presence of multiple azeotropes in the synthesized product using this method complicates the separation process and results in high energy consumption. To efficiently separate high‐purity ECH, this paper investigates and analyzes three separation schemes based on the phase‐equilibrium analysis, including hybrid extractive distillation (HED), pressure swing distillation (PSD), and three‐column batch distillation (TCBD).RESULTSThe operating parameters of the three separation processes are optimized by the sequential iterative optimization method that the minimum total annual cost (TAC) can reach 493 491 $/y. The thermal integration method is used for process energy‐saving optimization, and the TAC can be further reduced by 6.9%. In addition, a comprehensive evaluation based on economic, energy, environmental, and exergy analysis is conducted, and reveals that TCBD process with thermal integration is optimal. A control structure is designed for the TCBD process to enhance its robustness that the purity of ECH remains above 99.9 mol% under ±10% disturbances in feed flowrate and composition.CONCLUSIONSCompared with HED and PSD processes, the TCBD process has better economic and environmental benefits, and its control structure can effectively resist disturbances. It is reasonable to believe that the TCBD process can be an excellent solution for the industrial production of ECH.This article is protected by copyright. All rights reserved.