Energy and exergy analyses of a novel cogeneration system coupled with absorption heat pump and organic Rankine cycle based on a direct air cooling coal-fired power plant. (15th August 2021) - Zhang, Hongsheng
Abstract: A novel cogeneration system in which the combination of an organic Rankine cycle (ORC) and an absorption heat pump (AHP) are applied to recover condensate waste heat of exhaust steam from steam turbine in a direct air cooling coal-fired power plant is put forward to further improve energy utilization efficiency in the paper. The novel cogeneration mode can achieve multiple purposes of increasing power generation, improving heating load, reducing irreversible heat exchange loss of heating network and preventing from freezing for air cooling system in winter. The energy and exergy analyses have been accomplished for a 600 MW direct air cooling coal-fired power plant based on the first and second laws of thermodynamics. The generated power and heating load increase by 16.2 MW and 78, 541.16 kW at 50% THA (Turbine heat acceptance) as heating flow rate is 100 kg/s in the novel cogeneration mode. The standard coal consumption rate and total exergy loss decrease by 48.98 g/kWh and 62.21 MW. The total energy and exergy efficiency respectively improve by 11.97% and 4.01%. Besides, the total exergy efficiency is increased with increasing load. The proposed scheme can provide a new method for energy conservation and icing protection of direct air cooling units in winter. Highlights: Presented a novel coupled method to improve power output and heating load. Established thermodynamic models based on first and second law of thermodynamic. Revealed performance advantages from qualitative and quantitative perspectives. Improved significantly both energy and exergy efficiencies of energy utilization.