Optimization and feasibility analysis of waste heat recovery procedures in copper plant based on the collaborative analysis of T-Q-C diagram

This paper addresses the critical challenge of reducing energy consumption and CO2 emissions in China's space heating sector by exploring industrial waste heat recovery in a copper smelter in Chifeng City. Traditional heating systems rely heavily on fossil fuels, contributing to 4 % of national energy consumption. The research proposes a novel T-Q-C diagram model, integrating temperature, heat, and carbon emission indices, to optimize waste heat utilization. Three innovative schemes are compared with the existing process: Scheme B (absorption heat pump-based full recovery), Scheme C (terminal large-temperature-difference recovery), and Scheme D (integrated recovery). The waste heat potential (369 MW) of copper plant is analyzed, with current recovery at 212 MW (57.46 % efficiency) and CO2 emissions of 60.6 tons/MW·a. Scheme B achieves full recovery (369 MW) but lowers supply water temperature (53.4 °C) and reduces emissions to 49.2 tons/MW·a. Scheme C increases supply water temperature (69.9 °C) but recovers 93 % waste heat (344 MW) with emissions of 50.2 tons/MW·a. Scheme D combines the advantages of B and C, achieving full recovery (369 MW), higher supply water temperature (73.5 °C), and the lowest emissions (49.2 tons/MW·a). Economic analysis reveals Scheme D has the highest initial cost but optimal performance in heat recovery, temperature, and CO2 emissions. The T-Q-C model proves effective in balancing technical, economic, and environmental factors, highlighting the potential of integrated technologies to advance sustainable urban heating under China's carbon neutrality goals.