Abstract:

A practical multi-period heat exchanger network (HEN) design is required to satisfy not only the operating requirements in several discrete sub-periods, but also the flexibility requirements in all sub-periods that help to compensate the potential fluctuations of the parameters in each sub-period. However, the problem of overdesign arise in most cases where the heat transfer areas are determined by increasing the margin or using the maximum area concept during the multi-period HEN design. These factors will lead to a waste of resource and capital. To address these problems, a method of multi-period HEN design considering overdesign control is proposed by taking both the requirements of multi-period operation and single period flexibility into account. In the proposed method, an initial multi-period HEN is first obtained by the single period HEN optimization. A HEN modification model, on the basis of stage-wise superstructure model and flexibility index model, is then developed and solved to determine the optimal modifications of the initial multi-period HEN in each sub-period. The final multi-period HEN is thus finished by combing the initial multi-period HEN and the corresponding modifications. The application and effectiveness of the proposed method are finally verified through a comparison of the results in this work and those in literature.

Key words: multi-period heat exchanger network, overdesign, process system, integration, optimization

摘要：

实际多周期换热网络的设计不但要满足多个离散周期的操作条件要求，还应该满足单个周期下的柔性要求，以补偿实际操作中单周期下可能出现的参数波动。而根据工程经验增加换热面积裕量和采用文献中的最大面积思想进行设计，都会造成多周期换热网络中换热面积的过度冗余，导致资源的浪费和投资成本的增加。针对以上问题，在综合考虑多周期操作条件要求和单周期柔性要求的基础上，提出了一种控制面积冗余的多周期换热网络设计方法。该方法首先在单周期换热网络集成的基础上获取一个初始的多周期换热网络设计方案。然后以此方案为基础，构建一个基于单周期换热网络模型和柔性分析模型的换热网络修正模型，并通过求解该模型获得初始多周期换热网络在各周期下的最优修正方案。通过综合初始多周期换热网络设计和修正方案，即可完成最终的多周期换热网络设计。最后，通过将所得多周期换热网络与文献中所得结果进行对比，验证了方法的有效性。

关键词: 多周期换热网络, 设计冗余, 过程系统, 集成, 优化