Systematic optimization for the utilization of low-temperature industrial excess heat for district heating

Because of extensive heat shortage and serious air pollution, industrial excess heat (IEH) has attracted much attention in the district heating (DH) markets of Northern China, as it has great potential for recycling and satisfying the large demand. Most of the available IEH is released at low temperature by steel plants, chemical plants, etc., which are located far away from the heat users. The energy consumption and pipe investment for heat transportation should be optimized to improve the comprehensive efficiency. This study will use systematic models to make optimization to primary-network temperatures and corresponding connecting forms. Several suggestions will be proposed to help improving the energy efficiency. Furthermore, based on a real case study, two new schemes are proposed and compared with the existing scheme. The connecting form of the optimized scheme is different to conventional heat pump systems using sources such as sewage and ambient water. The rated COP is estimated to be 6.16, and the annual electricity consumption is 40.78 kWh/GJ. The system has significant advantages in terms of energy savings and reductions in pollution emissions in comparison to conventional source systems, implying that it can be worth exploiting IEH even at low temperatures and long distances.