Thermal-fluid system integration of a LiBr absorption heat pump for advanced waste heat recovery in Coal-Fired power plants

To address the issues of high thermal energy consumption in heating supply and insufficient energy cascade utilization in coal-fired units, this study proposes an integrated heat recovery system that integrates a low-temperature economizer with a lithium bromide (LiBr) absorption heat pump. A 350 MW supercritical unit is used as the case study, where a cascaded heating system is constructed using turbine extraction steam as the driving heat source, while recovering waste heat from both the pre-desulfurization flue gas and the condenser circulating water. This study presents a simulation-based investigation into an integrated system for waste heat recovery and efficiency enhancement in coal-fired power plants. The results demonstrate that the system recovers 8.026 MW of flue gas waste heat, achieves a heat pump coefficient of performance (COP) of 1.718, and reduces the heating extraction steam consumption by 32.5% compared to conventional methods. Therefore, this research offers a practical and efficient strategy. It is particularly relevant for areas with substantial heating demands, aiming at the energy-saving retrofit and improved operational flexibility of existing coal-fired power units.