| In recent years,direct air cooling technology has been widely used in northern China,characterized as abundance in coal but lacking in water.Due to the distinct superiority in water conservation,direct air cooling system is benefit to economic operation.Because of the special configuration and cooling mechanism of direct aircooling island,phenomena like air blocking and air flow field turbulence are ubiquitous,which lead to air vortexes,serious condensing efficiency deterioration and additional energy assumption.The environment conditions deterioration and low operation load will be serious influence on safety and economic behavior of unit operation.The distribution of air flow field and temperature field were studied with numerical simulation method to reveal the formation of flow dead zone.The flow guiding devices were arranged inside the air-cooling condensers to optimize the air flow configuration,improve the air-cooling condenser performance and operation efficiency.The effect of flow guiding devices was analyzed and verified with field test on the operation of power unit.Moreover,thermal plant capacity increases rapidly in China but industrial electricity consumption drops sharply due to the slow economic growth rate,which results in the load reduction of thermal plant.Many plants have to stop half units.Besides,for air-cooling island,under summer high temperature condition,the decline of ambient air coolant capacity leads to the lack of heat exchange area and the increase of back pressure,which deteriorates performance and operating safety of units.The interconnection of adjacent steam conducts in direct air cooling condenser was proposed.Heat exchange area could be increased by connecting the steam conducts of stopped air-cooled condensers.The feasibility of different modification schemes for actual direct air cooling units was compared by field tests. |
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