Feasible heat recovery of interplant heat integration between two plants via an intermediate medium analyzed by Interplant Shifted Composite Curves

• A new strategy to select streams for interplant heat integration is proposed.
• Maximum feasible heat recovery can be obtained.
• The existing heat exchanger networks remain unchanged within integration.
• Energy targets and the minimum heat capacity flowrate of a single-circuit intermediate medium are determined.

Interplant heat integration brings more opportunity to utilize the surplus/waste heat in individual plants. In most previous studies on interplant heat integration, either Grand Composite Curves (GCCs) or waste heat source/sink in the existing heat exchanger networks (HENs) were used for analysis. However, for these two methods, the former may generate intricate HENs, while the latter may miss some possible heat recovery potential. This paper investigates a way to achieve almost maximum possible heat recovery for indirect heat integration between two plants without basically changing the existing HENs. The selection of appropriate hot/cold streams participated in integration is investigated. A novel concept named Interplant Shifted Composite Curve (ISCC) is proposed to determine the maximum feasible heat recovery potential via indirect interplant heat integration and the minimum flowrate of a single-circuit intermediate medium used. Compared to the waste heat source/sink in the existing HENs being used directly for integration, a case study shows 43.1% of energy saving with minimum flowrate of a single-circuit intermediate medium, which can be easily obtained in the ISCC. Meanwhile, compared to the GCCs being used for integration, a scheme relatively easy and practical to implement can be achieved with the proposed method.