Abstract
Facing the current energy structure urgently needs to be transformed, heat exchanger network (HEN) can implement heat recovery and cost reduction by the arrangement for heat exchanges between cold and hot streams. The plenty of integer and continuous variables involved in HEN synthesis cause the results to be easily trapped in local optima. To avoid this situation, the mechanism of accepting imperfect solutions is added in a novel algorithm called Random Walk Algorithm with Compulsive Evolution. However, several potential solutions maybe abandoned by accepting imperfect solutions. To maintain the global searching ability, and at the same time, protecting the potential solutions during the optimization process, the limitations of accepting imperfect solutions are investigated in this work, then a back substitution strategy and elite optimization strategy based on algorithm are proposed. The former is to identify and adjust the inferior individuals in long-term stagnation while the latter is to keep and perform a fine search for the better solutions. Furthermore, a modified stage-wised superstructure is also developed to implement the flexible placement of utilities, which efficiently enlarges the solution domain. The validation of strategies and model is implemented by three cases, the results are lower, with 2219 $/year, 1280 $/year, and 2M $/year than the best published result, revealing the strong abilities of the proposed method in designing more economical HENs.
Highlights
Published: 17 November 2021Heat exchanger network (HEN) synthesis can effectively realize heat recovery, reduce external utility consumptions, and improve economic benefits, so it has attracted extensive attention from many academic researchers and engineering workers in the past four decades and is widely applied in various fields including chemical process and crude refining industries [1,2]
A novel stochastic method improved RWCE (IRWCE) consisting of random walk algorithm with compulsive evolution (RWCE), back substitution strategy, and elite optimization strategy is proposed to solve the HEN synthesis (HENS) problems based on a modified
The two novel strategies can maintain the positive effect of accepting imperfect solutions (AIS) and solve the limitations of AIS, making the IRWCE satisfy the needs of relatively strong global and local search ability
Summary
Published: 17 November 2021Heat exchanger network (HEN) synthesis can effectively realize heat recovery, reduce external utility consumptions, and improve economic benefits, so it has attracted extensive attention from many academic researchers and engineering workers in the past four decades and is widely applied in various fields including chemical process and crude refining industries [1,2]. HEN synthesis (HENS) is the heat integration between hot and cold process streams [3] with the aim of minimizing total annual cost (TAC) consisting of three sections i.e., utility consumption cost, fixed charge, and area cost of heat units. Pinch method [5] is a classical method used to evaluate optimal HEN using thermodynamics laws. In this method, the pinch point is first identified based on the given heat recovery approach temperature to predict maximal heat recovery, the original HEN is decomposed according to the pinch point to predict minimal heat units. The pinch-based methods are well developed and demonstrated excellent efficiency [8,9,10]
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