Integration of heat storage in batch processes considering additional approach temperature difference for indirect heat transfer

There are two modes of heat transfer in batch processes: direct and indirect. To achieve indirect heat transfer through a heat-transfer medium, an additional approach temperature difference is required. However, the current pinch analysis considering additional approach temperature difference can lead to uneconomical or infeasible design. A methodology for the integration of heat storage considering additional approach temperature difference for indirect heat transfer based on pinch analysis was proposed in this paper. Different minimum approach temperature differences were first used for direct and indirect heat transfer to obtain the utility target and to determine the configuration and the capacity of the heat storage units in the time-dependent heat cascade analysis. The time slice profiles were constructed based on the heat cascade analysis to determine the operating temperature of the heat storage units. Then the heat storage units were represented as hot and cold streams in the time periods with a heat surplus and deficit respectively, and an optimal network was obtained using the pinch design method. Finally, the applicability and effectiveness of the proposed methodology were demonstrated through two benchmark examples. © 2020, Chemical Industry Press. All right reserved.