Synthesis of multipass heat exchanger network with the optimal number of shells and tubes based on pinch technology

摘要

Many methods have been proposed for the synthesis of multipass heat exchanger network (HEN). Considering that both parallel and countercurrent flows are involved in the multipass HEN, temperature difference correction factor F-T is commonly used. However, the correction factor F-T is always obtained by trial and error iterations, which are difficult to compute. On the other hand, the threshold value for multipass heat exchanger design and multipass HEN synthesis may change with the operating conditions although a rule of thumb for correction factor F-T is given to avoid temperature cross. This paper introduces a new approach for optimal heat exchanger network synthesis based on pinch technology considering multipass heat exchangers. For this purpose, the relationships between the number of passes for shells and tubes, and pinch character are analyzed by using modified composite curves. Then, the minimum temperature difference (Delta T-mm) and the number of shells and tubes are optimized based on pinch technology. The proposed methodology allows for proper handling of the trade-offs involving energy consumption, number of units and passes for shells and tubes, and network area to provide a network with the minimum total annual cost. To show the reliability of this approach it is used to synthesis two heat exchanger network problems taken from open literature and results are compared to that predicted from published methods. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.