Multi-plant indirect heat integration via an intermediate fluid loop is an effective and energy-saving method of heat recovery. It is most suitable in practical applications because it requires fewer inter-plant pipelines and has the advantages of a simple heat exchanger network. A well-designed heat exchanger network will significantly increase economic efficiency and reduce energy consumption in plants. In this paper, a multi-plant indirect heat exchanger network model is developed for recycling heat using intermediate fluid. This model aims to minimize the total annual cost, including utility cost, number of units and heat transfer area cost. An Alopex-based evolutionary algorithm is used to optimize the model and obtain the heat capacity flow rate of intermediate fluids, the temperature of the heat transfer medium and the configuration of the superstructure simultaneously. Results from three examples demonstrate that the proposed model can perform well in multi-plant heat exchanger network synthesis. (C) 2018 Elsevier Ltd. All rights reserved.