Case study on combined heat and water system for district heating in Beijing through recovery of industrial waste heat in Tangshan

Abstract

With the proposal of China's dual-carbon goal, the recovery of industrial waste heat (IWH) for district heating has gained increasing attention. Recently, some scholars have proposed that combined heat and water (CHW) systems are more economical compared with separate heat and water supplies. Beijing lacks desalinated water (DW) and clean low-carbon heat, whereas Tangshan in Hebei Province is rich in IWH. By combining CHW with seasonal thermal energy storage, a case of long-distance transport of hot DW from Tangshan to Beijing was planned, and the costs, energy consumption, and feasibility were analyzed. As a result, under the optimal heat source temperature and effect number of 70 °C and 10 for seawater desalination, the heat from various IWH sources of the three costal steel plants is recovered maximally to produce about 35000 t/h of 95 °C DW. Then, the hot DW is transported to Beijing with a long-distance heat loss ratio controlled below 3 %. Annually, 271.2 million tons of DW and 91.5 million GJ of heat is supplied. The introduction of IWH can save 2.68 billion Nm3 of natural gas per year and the discounted payback period is about 10 years, which has obvious energy-saving, environmental, and economic benefits.