Trade-off between energy and distance related costs for different connection patterns in heat integration across plants

• Different connection patterns are first defined in total site heat integration.
• A graphical method to determine the flow rate of intermediate fluid is proposed.
• Energy targets for different connection patterns can be determined.
• Site pinch is found in series connection pattern.

Recent research efforts on total site heat integration have mainly focused on determining the energy target without considering the following two factors. The first factor is distances between separate plants. The required pipelines between plants in total site heat integration is much longer than heat integration within one plant, so more attentions must be paid on this distance factor as it incurs more expense. The other factor is the type of heat transfer medium. In most studies, steam is used as the heat transfer medium between plants but it cannot be applied in low temperature range. In this work, three connection patterns for individual plants within one site are presented. Both the locations of the plants and the use of water as the heat transfer medium are considered. A graphical methodology for determining the energy target for the three connection patterns in total site integration is proposed. The utility of the proposed methodology is illustrated using a case study based on three plants.