Waste heat and water recovery from boiler exhaust fluegas is significant for reducing coal and water consumption of coal-fired power plants. In this study, waste heat and water recovery systems were proposed with a 330MW air-cooling coal-fired power plant as the reference case. In these systems, boiler exhaust fluegas is cooled to approximately 95 °C in fluegas coolers before being fed to the electrostatic precipitator. Moreover, a fluegas cooler is installed after the desulfurizer to recover water from fluegas. The recovered waste heat is used to heat the condensation water of the regenerative system, boiler feeding air and reheat the fluegas after flue gas condenser. Then, thermodynamic analyses were carried out based on equivalent entropy drop method. Results show that the coal consumption rate can be reduced by about 2.7 g kW^-1^ h^-1^, and about 14.5 kg s^-1^ of water can be recovered when the fluegas moisture content is reduced to 8.5%. The unit area cost of heat exchangers, including the fluegas coolers before electrostatic precipitator, flue gas condenser after the desulfurizer and fluegas reheater, is different. Heat exchangers’ area is affected by heat load and heat transfer temperature difference. The cost of the systems may be decreased by optimizing the temperature parameters of system optimization. Therefore, the optimization models based on Genetic Algorithm were developed to obtain the optimal system configuration with best economic performance. At last, the impact of temperature parameters on the systems and the economic performance of the optimized systems was analyzed in detail.


Thermo-Economic Analysis on Waste Heat and Water Recovery Systems of Boiler Exhaust in Coal-Fired Power Plants

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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