Synthesis Of Water Allocation Network In Chemical Processes

With the increasingly scarcity of water and energy resource and ever-tightening environmental regulations on industrial effluent, the research on synthesis and optimization of water network and heat exchanger network for improving the utilization efficiency of water and energy resource has been becoming more focused, and motivated than ever before. However, such as multiple category operations, uncertainty, multiple heat recoveries model etc. for the synthesis problems are so complex that the currently available methods demonstrate still some major limitations. With the consideration of the above issues, we have performed the following research.1. A strategy for fresh water minimization is developed for continuous water utilization systems with both fixed flowrate (non-mass-transfer-based) and fixed contaiminent (mass-ransfer -based) operations.Through introducing the concept of improved ficitious operation units, the problem of water losing and/or generating for the fixed flowrate operations in continuous water utilization system can be handled easily without tedious graphical or iterative procedure, the pinch point can also be located simultaneously.2. Based on the knowledge of concentration interval analysis technique, a heuristic-based approach is presented to generate water utilization networks.The proposed method has the advantage of capability of considering fixed flowrate operations, the necessity of identifying and breaking loops and the limitation of flow distributing or mixing can be avoided.3. Based on the improved concentration interval analysis technique for continuous process water using system, a time-dependent concentration interval analysis (CIA) method to solve the problems of synthesis of single and repeated batch water-using systems is presented. The proposed method can effectively minimize the freshwater consumption for single or repeated batch operations and can determine a preferable storage tank capacity.4. An improved symmetric fuzzy linear programming (SFLP)model and a multi-objective mixed-integer SFLP model are developed for fresh water minimization of single-component water utilization networks with mass load uncertainty. A main criterion limiting (MCL) solution strategy is further developed for the multi-objective problem. The solution results of the example problems demonstrate that the proposed modeling and solution procedures have a good suitability, and then provide an optimum design for the networks.5. Aiming at the nonlinear programming problem (NLP) and the mixed-integer nonlinear programming problem (MINLP) with equality constraints, an improve particle swarm optimization (PSO) algorithm, i.e. reduced space optimization(R-PSO) algorithm is developed. The advantage of proposed algorithm in applicability and efficiency is demonstrated by several test problems.6. Based on a superstructure representation, a nonlinear programming (NLP) model as well as a mixed-integer nonlinear programming (MINLP) model was proposed for the optimal design of distributed wastewater treatment network system. Furthermore, to overcome the solving difficulty of the corresponding non-convexity problem, a newly proposed random search based optimization method– particle swarm optimization (PSO) is introduced and applied to develop a global optimization method for the wastewater treatment network design.7. By considering of the direct heat recovery that special existing in water using network, a net-heat integration approach for the simultaneous heat and water network integration. And combination with R-PSO algorithms, proposed an evolutionary approach to solve the simultaneous heat and water network optimization problem. By fully taking into account the possibility of the heat recoverie, the proposed approach can realize the optimum energy consumption target and heat exchange network in water using system. Furthermore, as an evolutionary-based approach, the proposed approach can deal with both single and multi-contaminant water-using systems, and can realize the economic trade-off between water network and heat exchanger network.