Performance analysis of the coal-fired power plant with combined heat and power (CHP) based on absorption heat pumps

• Proposed adopting the absorption heat pump to recycle the waste heat for cogeneration.
• Established the analysis model of absorption heat pump for cogeneration to obtain the system performance.
• Combined theoretical analysis and actual data from the plant to ensure the reliability of the results.

A new waste heat recovery scheme based on absorption heat pumps (AHP) applied in CHP (Combined Heat and Power) system was proposed to decrease heating energy consumption of existing CHP systems by recovering waste heat of exhausted steam from a steam turbine of a coal-fired direct air cooling unit. This paper has built the mathematical models of the CHP system with absorption heat pump recovering waste heat focusing on the CZK135-13.24/0.245/535/535 units. Based on the first law of thermodynamics, the thermodynamic performance of the integrated system was evaluated under the changing operating condition aiming at different operating modes. Compared with conventional heating mode, it has been found that the coal consumption rate decrement of the integrated system decreases with the increase of the load when the heating load is fixed. In addition, when the thermoelectric ratio is 100%, the power output increases around 3.81 MW and coal consumption rate decreases 11.69 g/(kW h) under 100%THA load, while the unit and total thermal efficiency increase 1.89% and 2.27%, respectively. The results provide not only theory basis and scientific support for the design of the coal-fired power plants with absorption heat pump recovering waste heat, but also a new scheme of energy saving and optimization for the units.