Case study on industrial surplus heat of steel plants for district heating in Northern China

In China, district heating systems are facing a dilemma between rapid growth in demand owing to urbanization and environmental problems related to coal-fired boilers. The utilization of industrial surplus heat has great potential on improving the power of heating systems and reducing coal consumption of boilers. However, few industrial systems are constructed under the consideration of district heating. Some features of the surplus heat, such as the position, grade, and production schedule, are significantly different to traditional heat sources. To recover the surplus heat, retrofits of district heating systems are necessary. In this paper, according to the current situations and the future developments, a scheme is proposed to integrate the surplus heat of two steel plants into a large-scale district heating network. Three sources of surplus heat are involved: slag-flushing water, cooling water, and low-pressure steam. The scheme has been partly applied in a corresponding demonstration project. The actual performance proves the feasibility of the integrated system and implies significant benefits in terms of economic cost, CO2 emission and pollutant emissions. Furthermore, the potential to extend the scheme in Northern China is also evaluated.