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BACKGROUND: Economic optimization and dynamic control of the separation process for recovering the ternary mixture of butanone (MEK)/n‐heptane/isopropanol (IPA) from industrial wastewater is a significant topic. In this work, the optimal pressure‐swing distillation (PSD) sequence, heat integration and dynamic control for separating MEK/n‐heptane/IPA were investigated systematically. The optimal separation sequence was determined by combining the minimum total annual cost (TAC) with the residual curves map (RCM). Pressure‐swing distillation with non‐heat integration, partial heat integration or full heat integration was compared in terms of TAC. Dynamic control schemes were designed for optimal processes of two separation sequences with and without heat integration. RESULTS: The results demonstrate that the TAC of optimal PSD with non‐heat integration process can be reduced by 31.11%, whereas the TAC of optimal partial heat integration and full heat integration schemes can be reduced by 39.73% and 40.96%, respectively. The dynamic performance of all control schemes that can resist ±20% feed flow disturbances and composition disturbances are compared with the integral of squared error. CONCLUSION: It is demonstrated that PSD with full integration process (FHIPSD) for separating MEK/n‐heptane/IPA has optimal economic performance, whereas PSD with non‐heat integration process (NTIPSD) has the optimal dynamic performance and robust stability. This work provides a significant reference for industrial separation of MEK/n‐heptane/IPA. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

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]

The effect of data preprocessing on a calibration model based on attenuated total reflectance‐Fourier transform infrared spectroscopy was investigated for in situ measurements of the solution concentration during cooling crystallization. L‐Glutamic acid cooling crystallization was taken as a case study. It was found that smoothing and derivative is a superior preprocessing method for model calibration, which can effectively remove spectral nonlinearity, improve the prediction accuracy of the calibration model, and enhance model robustness in detecting faults. Verification experiments demonstrated the effectiveness of the established calibration models. These models also show better performance in detecting the generation of crystal nuclei in the probe window, which is of great significance to eliminate the fatal probe fouling. [ABSTRACT FROM AUTHOR]

BACKGROUND Controlling the behavior of processes for the recovery of ethyl acetate and isopropanol from industrial wastewater is a hot topic. In this work, dynamic control structures of the extractive distillation process and heat pump combined with feeding preheating extractive distillation process are researched. The control performance of the proposed control structures is tested by adding feed flow and composition disturbance. In these two processes, two‐point temperature control structure is first used. RESULTS: The results show that this structure can maintain product purity within a reasonable range under disturbance. Furthermore, the composition controller is used to improve control performance. CONCLUSION: The improved structure can effectively meet the requirements of product purity. The heat pump combined with feeding preheating extractive distillation process can use the same control structure as the extraction process and show good controllability. This study has a certain guiding value for the research of chemical dynamic control. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]