直接空冷火电机组乏汽余热利用技术

Direct Air-Cooled Thermal Power Unit Exhaust Steam Waste Heat Utilization Technology

火电厂汽轮机排汽(乏汽)需要冷凝成液态水用于系统循环,湿冷、干冷机组都需要消耗大量能量来冷凝乏汽。北方缺水地区采用直接空冷火电机组,大量乏汽通过空冷岛散热。从热力学第二定律来看,乏汽已无做功能力,但是汽化潜热与做功能力无关,在能够提供真空环境确保乏汽流动性和需要加热远低于乏汽温度的工质的情况下,乏汽中的汽化潜热仍具有很高的回收价值。尤其对于直接空冷火电机组,其汽轮机排汽压力和温度均高于湿冷机组,可以采用汽水换热器直接回收乏汽热量加热厂区生水,降低电厂辅助蒸汽的消耗量,提高电厂收益。

The exhaust steam of steam turbine in thermal power plant needs to be condensed into liquid water for system circulation,and both wet-cooled and dry-cooled units need to consume a lot of energy to condense steam.Direct air-cooled thermal power units are used in the water-scarce areas in the north,and a large amount of steam is dissipated through the aircooled island.From the second law of thermodynamics,the steam has no ability to do work,but the latent heat of vaporization has nothing to do with the ability to do work,in the case of providing a vacuum environment to ensure the flow of the steam and the need to heat the working medium far below the temperature of the steam,the latent heat of vaporization in the steam still has a high recovery value.Especially for the direct air-cooled thermal power unit,the steam turbine exhaust pressure and temperature are higher than that of the wet cooled unit,and the steam water exchanger can be used to directly recover the steam heat to heat the raw water in the plant,reduce the auxiliary steam consumption of the power plant and improve the power plant income.