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The pressure-swing distillation (PSD) processes with varied-diameter columns (VDCs) for separating methanol–chloroform and n-heptane–isobutanol are studied. Furthermore, two heat-integrated PSD processes, partial integration and full heat integration, are discussed with ordinary and VDCs. The results show that whether it is heat integrated or non-heat integrated, the processes using VDC have an advantage in the economy. Based on the minimum total annual cost (TAC), the dynamic controllability without and with full heat integration for an azeotrope system methanol/chloroform is explored. The dynamic controllability without and with partial heat integration for the azeotrope system n-heptane/isobutanol is discussed. The results indicated that compared with the dynamic responses without heat integration process, the heat-integrated PSD with a VDC did not increase the control difficulty while maintaining its economy. More azeotropic systems should be studied to investigate their economics and control effects, which will benefit PSD design and industrial application. [ABSTRACT FROM AUTHOR]

• The separation of MEK/IPA/n-heptane by triple column pressure-swing distillation is studied. • The heat integration scheme and dynamic control strategy of triple column pressure-swing distillation are studied. • The full heat integration process has good ISE value and minimum TAC. 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. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel extractive distillation process with vapor recompression and feed preheating was designed to separate xylene isomers. • Process parameters were optimized by multi-objective genetic algorithm with superior economic and environmental benefits. • The TAC and E CO2 can be reduced by 14.2% and 30.2% respectively compared with the existing distillation process. The focus of the chemical industry on environmental protection and energy conservation has driven the development of green distillation technology. Xylene isomers are extensively utilized industrial raw materials, whose separation is challenging and energy-intensive due to their closely similar boiling points. Therefore, it is urgent to develop energy-saving and environmental protection technology. In this paper, an energy-saving and environmental protection process for separating the xylene isomers by extractive distillation was designed combing the vapor recompression process with feed preheating (VRAPFP). The parameters of extractive distillation processes were synthetically optimized by multi-objective genetic algorithm (MOGA) with total annual cost (TAC), CO 2 emission (E C O 2 ) and separation efficiency (E ext) as the objective evaluation indexes. The economical optimal process was used further for VRAPFP design through heat integration to reduce energy consumption, and all the designed candidate processes were synthetically analyzed, compared and evaluated with performance indexes. Results show that the VRAPFP process has superior economic efficiency and ecological sustainability compared with the existing distillation process, wherein the TAC and E C O 2 are reduced by 14.2 % and 30.2 %, respectively. This work provides a new reference and idea for separating xylene isomers with the economy and developing new processes for energy conservation and environmental protection. [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]