空冷凝汽器积灰干式吹扫系统现场实验研究

A Site Simulation Test on Compressed Air Blowers for Ash Fouling of Air Cooled Condensers

直冷系统以节水率达69%-84%而在燃煤电站得到广泛应用。但在风沙大的干旱地区,若清洗不及时,空冷凝汽器则因积灰而使排汽背压升高8kPa甚或以上,机组煤耗因而升高10-15g/（kW·h）,污染排放亦随之增大,而及时清洗所需的水资源又为环境所限。对此,该文设计了一种以压缩空气代替高压除盐水的干式吹扫系统,并在某600MW直冷机组单排翅片管空冷凝汽器上进行了两种清洗方式的比较实验。文中介绍了干式吹扫系统的构成、实验内容及结果,拟定了吹扫效果评价方法,建立了灰垢热阻与排汽背压的定量关联,并据以比较了干式吹扫与水洗在同一清洗周期内累计清洗效果。结果表明：干式吹扫年节水量为1.47kg/m^2,累计平均背压降低1.7kPa,机组发电煤耗降低约2.5g/（kW·h）,实现了节水、节能和减排共赢。

Direct air cooling （DAC） system has been widely applied in coal-fired power plants for its water-saving rate of 69%-84%. However, in arid regions with large sandstorm, the exhaust pressure of steam turbine will be raised by 8kPa or more because of the ash fouling of air cooled condenser （ACC）. If it is not timely cleaned, the coal consumption of unit would elevate above 10-15g/（kW·h） and the pollution emissions increases in the meantime. But the water consumption for timely cleaning is restricted by environmental conditions. To solve the incompatible contradiction, a novel compressed air blower （CAB） system was designed to clean the ash fouling for ACC in this paper, that is, the compressed air will entirely replace desalted water as cleaning medium for the new system. The main body of this paper includes the basic components of the CAB system, the content and results of a site simulation test （SST） for CAB under multi-operation conditions on an ACC of 600MW DAC unit, the blowing evaluation indexes proposed, and the quantitative correlation between the ash fouling resistance and exhaust pressure obtained by site simulation test data processing, the comparison of accumulated cleaning effects between compressed air blowing and water washing in the same cleaning period etc. The SST results of CAB system show that： the water-saving quantity per year is 1.47 kg/m^2; the accumulated average exhaust pressure of steam turbine is reduced by 1.7 kPa and the coal consumption has been reduced by 2.5 g/（kW·h） compared to water washing. That is, the CAB system can accomplish three goals at the same time： water-saving, energy-saving and emission reduction.