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BACKGROUND: The triple‐column extractive distillation (TCED) process for the ternary multi‐azeotropic mixture of N‐hexane/acetone/chloroform is a significant step in waste recovery and purification. Given the common occurrence of feed disturbances in practical industrial production, a feasible dynamic control scheme should effectively resist feed disturbances and ensure product quality, enabling the process to run steadily and safely with a high efficiency. However, it is challenging to design a robust control scheme for separation processes accompanied by side‐stream capability. In this work, dynamic control schemes were designed for four separation processes: conventional and double side‐stream TCED processes with single and double entrainers. A multipoint temperature control scheme, composition‐temperature cascade control scheme and variable ratio control were combined to improve the dynamic performance of the control schemes. RESULTS: The results showed that the control schemes designed for the four extractive distillation processes are highly robust, resisting ±20% feed flow and composition disturbances. A variable ratio control combined with composition‐temperature cascade was found to be vital for double side‐stream TCED schemes. CONCLUSION: The conventional TCED with a single entrainer (CS‐TCED) is an optimal process for N‐hexane/acetone/chloroform separation both from control and economic perspectives. The designed control scheme is simple, low‐cost and easy‐to‐implement with a superior dynamic performance over other separation schemes. This study has a certain theoretical guidance for N‐hexane/acetone/chloroform separation in terms of economic benefits and practical production. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

• Control scheme design of the benzene/isopropanol/water separation. • Open loop steady-state gain analysis to determine temperature sensitive plates. • Robust control of sensitive plate temperature by the steam separation ratio (β V). • Dynamic performance comparison of CED and DWED. The effective separation of the ternary azeotrope benzene/isopropanol/water has high economic benefits in industry. It is of great significance to study the dynamic controllability of this ternary azeotropic system. In this paper, dynamic control schemes of the conventional extractive distillation (CED) and the dividing wall extractive distillation (DWED) for benzene / isopropanol / water separation with ethylene glycol (EG) as extractant were studied. The open loop steady-state gain analysis is used to guide the control structure improvement, a multi-point temperature control strategy based on the sensitive stage temperatures is proposed to improve the control scheme. In the CED process, the improved control scheme can resist ±20% feed flow and composition disturbances. In addition, it is demonstrated that using the steam separation ratio (β V) to control the sensitive stage temperature shows better dynamic performance compared with using the ratio of the steam side flowrate and the reboiler heat duty (V/R) to control the sensitive stage temperature in the DWED process. Finally, by comparing the integral of squared error (ISE) values, it is found that improved control schemes (CS2 and CS4) have better robustness and dynamic performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Dynamic control structure of triple column pressure-swing distillation is investigated. • ISE is used to evaluate the performance of dynamic control structure. • The control strategy of full thermal integration process has good economy and controllability. When evaluating the distillation process, it is necessary to consider its economic performance and its controllability. In this study, a strategy was developed to realize the stable control of pressure swing distillation without thermal integration in the face of 20% flow and composition disturbances. Through an exploration of the heat integration between different distillation columns, three partial and one full thermal integration processes were developed. The robust control of these processes was realized by adding reboiler heat duty and feed ratio (Q/F) control structures. Finally, the three processes were compared in terms of control and economy, and it was found that the controllability of the full thermal integration process was slightly inferior to that of the pressure swing distillation without thermal integration. However, the full thermal integration process consumed 29.48% less energy compared to process without thermal integration and resisted ±20% flow and composition disturbances. This research has a certain reference and guiding significance for the process design and control strategy design of triple column swing pressure distillation in industry. [ABSTRACT FROM AUTHOR]

• Heat integration and dynamic control of reactive pressure-swing distillation for separating tetrahydrofuran/ethanol/water were investigated. • Three generalized and robust control strategies that can resist ±20% feed disturbances were proposed for RPSD. • The TAC and exhaust emission (CO 2 , SO 2, and NO) were greatly reduced while the dynamic control performance was improved. In this paper, heat integration and dynamic control of reactive pressure-swing distillation (RPSD) for separating tetrahydrofuran/ethanol/water was investigated from the aspects of energy consumption, environmental protection and practical applications. By exploring the heat exchange between separating tetrahydrofuran and ethanol distillation columns, the full heat integration process (FHI) was designed. Robust control of heat and non-heat integrated processes was realized based on the dual temperature control structure. All processes were resistant to ±20% feed flow and composition disturbances. Finally, these processes were compared from three aspects: economy, environment and dynamic performance. The results show that compared with the non-heat integration process, the FHI process can reduce the total annual cost by 24.14%, the CO 2 emission by 20.21% and the SO 2 and NO emission by 34.38%, meanwhile, having the best dynamic performance. This study is valuable and instructive in promoting the integrated optimal and control design of the RPSD process. [Display omitted] [ABSTRACT FROM AUTHOR]