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Highlights: [•] A graphical integration method is developed for work exchange network. [•] Linearly approximated sink auxiliary lines are proposed. [•] Five matching rules are proposed for identifying the feasible match. [•] The proposed method can be applied to target the maximum energy recovery. [Copyright &y& Elsevier]

Abstract: In this paper, a novel systematic model-based methodology for performing integrated process design and controller design (IPDC) for chemical processes is presented. The methodology uses a decomposition method to solve the IPDC typically formulated as a mathematical programming (optimization with constraints) problem. Accordingly the optimization problem is decomposed into four sub-problems: (i) pre-analysis, (ii) design analysis, (iii) controller design analysis, and (iv) final selection and verification, which are relatively easier to solve. The methodology makes use of thermodynamic-process insights and the reverse design approach to arrive at the final process design–controller design decisions. The developed methodology is illustrated through the design of: (a) a single reactor, (b) a single separator, and (c) a reactor–separator-recycle system and shown to provide effective solutions that satisfy design, control and cost criteria. The advantage of the proposed methodology is that it is systematic, makes use of thermodynamic-process knowledge and provides valuable insights to the solution of IPDC problems in chemical engineering practice. [Copyright &y& Elsevier]

In this paper, graphical method is employed to optimize single-contaminant regeneration reuse water systems. On the concentration-mass load diagram, three categories of water-using systems with regeneration reuse are analyzed in terms of the geometric features of limiting composite curve. Total regeneration and partial regeneration are identified first. Then based on sequential optimization and at a specified post-regeneration concentration, the optimal water supply lines for regeneration reuse systems can be constructed. The optimal water supply line corresponds to minimum freshwater consumption, minimum regenerated water flowrate and minimum contaminant regeneration load. Formulas for calculating these targets are summarized and interactions of these parameters are discussed. The concepts of limiting points for regeneration reuse, which are the counterpart of pinch for direct reuse, are proposed to indicate the bottlenecks of a water system with regeneration reuse. Different locations of the limiting points for different systems underlie that the optimal regeneration concentration can be greater than, equal to or smaller than the pinch concentration of the system. [ABSTRACT FROM AUTHOR]

Water system integration with regeneration recycling can reduce freshwater consumption and wastewater discharge to the maximum extent. In this paper, by analyzing the limiting composite curve of a single-contaminant water system, a method is proposed to construct the optimal water supply line for regeneration recycling. Accordingly the targets for regeneration recycling water systems are obtained. The targets in sequence are the minimum freshwater consumption (the minimum wastewater discharge), the minimum regenerated water flowrate, and the optimal regeneration concentration. The post-regeneration concentration is taken to be fixed in the sequential targeting procedure. The interactions of these targets are analyzed, and formulas for calculating these targets are proposed. The results show that for a single-contaminant regeneration recycling water system, the minimum freshwater consumption is determined by the shape of the limiting composite curve below the post-regeneration concentration. The optimal regeneration concentration is defined as the minimum regeneration concentration at the minimum freshwater consumption and the corresponding minimum regenerated water flowrate. The minimum regenerated water flowrate and the optimal regeneration concentration are both related to the geometrical features of the limiting composite curve of the water-using system and to the post-regeneration concentration. The optimal regeneration concentration has no direct relationship with the pinch concentration. [Copyright &y& Elsevier]