Design And Optimization For Heat Exchanger Network Of Batch Process

The proportion of intermittent production processes in the chemical production process is increasing.With its high degree of flexibility,it plays an increasingly important role in highly knowledge-intensive,technical fine chemicals and biochemical chemicals.However,compared with the continuous production process,which has been extensively studied,the research on the batch process starts later.Compared with the integration of continuous process heat exchanger networks,the current comprehensive research on the batch process heat exchanger networks is still very limited.In this study,considering only direct heat transfer,a T-t heuristics method and a mathematical programming method are used to integrate and optimize the batch process heat exchanger network.Based on the TSM,the initial heat exchange network is obtained by two methods.According to the disconnection rule of the heat load circuit,the excess heat exchanger is removed,and the common heat exchanger is combined together.The structure of the total heat exchanger network was optimized to reduce the number of heat exchanger units.The total cost,i.e.the investment and operating costs of the final heat exchanger network,was calculated.The T-t graph method is a heuristic method.According to the similar heat capacity flow matching rules,stream split heat transfer rules and other simple rules proposed in this paper,the initial heat exchanger network can be obtained intuitively and conveniently in a graphical manner.T-t graph heuristic method is suitable for the simple process with little streams,and the initial heat exchanger network can be quickly obtained according to the relevant rules.The verified example proved that it is simpler than the pinch method,and requires less calculation.The mathematical programming method builds a nonlinear mathematical model based on the parallel matching principle proposed in this thesis,which takes the minimum annual cost as the objective function,and solves the nonlinear constrained optimization problem through the fmincon function in the MATLAB optimization toolbox,thereby obtaining the initial heat exchanger network.The mathematical programming methods are suitable for complex processes with large numbers of streams.The simplified mathematical model quickly calculates and solves the initial heat exchanger network.Based on the principle of stream split matching,it is simpler than the traditional mathematical model,the heat exchanger network structure is better,and the cost is lower.The investment cost and total cost of the heat exchanger network after the structure optimization are greatly reduced,the energy saving potential is large,and the scope of application is wide.The methods developed in this study would be helpful for the optimization of the batch process heat exchanger networks.