Process change analysis of heat exchanger networks with heat pumps

The minimum hot and cold utilities of heat exchanger networks can be obtained based on the principle of pinch theory. Moreover, reasonable process changes can further reduce hot and cold utilities. Meanwhile, adding heat pumps correctly in a heat exchanger network can reuse the waste heat below the pinch, which reduces both hot and cold utilities and enhances energy utilization. The influence of process changes on hot and cold utilities of heat exchanger networks with heat pumps was analyzed by a graphical method based on the pinch technology. The results show that a process change that originally cannot reduce hot and cold utilities can be transformed into one that can save utilities with the help of heat pumps. Therefore, for heat exchanger networks with heat pumps, whether a process change is profitable also depends on the influence of heat pumps. This work extends the research scope of process change and the acquired results provide theoretical criteria for reasonable process changes.