In order to reduce the back pressure of direct air cooling unit and increase power output of steam turbine in summer, the cold end system of a power plant is optimized through adding evaporative condenser as peak cooling device. Through experiments, this artical compares the effect on back pressure in the case of inputting the peak cooling device and cutting off peak cooling device with different load and different temperature in summer, also the effect of ash deposition on exhaust pressure is

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... tudied. The results show that the unit in different load of 500WM, 400WM, 380WM, 300WM and different temperature of 29℃,33℃,30℃,27℃ respectively, when putting into the peak cooling device, back pressure reduces 22kPa,13.1kPa,10.8kPa ,6.7kPa respectively; when cutting off the peak cooling device, the back pressure increases 27kPa, 14kPa, 11.4kPa and 5.4kPa respectively. The ash deposition can increase the back pressure. The back pressure has been reduced about 9kPa after cleaning ash deposition when cutting off the peak cooling device.