Design and Operation Optimization of Industrial Waste Heat Recovery for District Heating and Cooling

Abstract

The recovery of industrial waste heat has drawn a lot of attentions, and integrating it into district heating and cooling (DHC) systems is a very attractive option for low-grade waste heat recovery. Most of the related studies used Pinch Technology to design the waste heat recovery networks for heating or refrigeration. However, district heating and cooling is a multi-period problem, and few of studies can provide specific operation plans in each different periods. In this study, a multi-period mathematical model has been established for the waste heat recovery, in which hot water is the intermediate fluid, and waste heat can be utilized in the entire year by integrating with DHC systems. The minimisation of total annual cost (TAC) of the system is regarded as the object function in the model. Operation parameters in each period including the mass flow rate and the temperature of hot water can be obtained by mathematical programming method. A case study has been conducted, and the optimal integration schemes were obtained by solving the mixed integer nonlinear programming (MINLP) model. The results show the significant potential economic benefits of the integration.