The effect of screens on air-cooled steam condenser performance under windy conditions

The effect of porous wind screens, installed in a cross-type arrangement below the fan platform, on the performance of El Dorado Power Plant’s 6 × 5 fan air-cooled steam condenser (ACC) under windy conditions is investigated using computational fluid dynamics. The existing wind screen configuration is found to increase ACC performance under windy conditions relative to the no screens case. The ACC performance enhancement can be attributed to an increase in the performance of the fans upstream of the wind screens brought about by the stagnation effect of the screens on the flow below the fan platform. The potential for further ACC performance enhancement at El Dorado is identified since the existing screen configuration is found to reduce the performance of the fans downstream of its location. An improved screen configuration consisting of screens with a loss coefficient of Ksc = 10 installed to half the fan platform height, with the remaining space below the fan platform left open, is identified for El Dorado. This configuration provides the favorable stagnation effect upstream of its location while having less of a detrimental effect on the downstream fans. It is further found that additional performance benefits could be gained under the prevailing wind conditions at El Dorado by relocating the N–S orientated screens by one fan row, thus increasing the number of fans operating in the beneficial upstream stagnation region.

Research highlights
► Wind screens installed below the ACC fan platform are found to be beneficial to ACC performance under windy conditions.
► The location and configuration of the screens has a measurable effect on the ACC performance enhancement associated with their installation.
► Fans located upstream of the wind screen location experience improved performance under windy conditions while those downstream of the screen typically experience a slight performance reduction. It is therefore desirable to maximise the number of fans upstream of the screen location under the prevailing wind direction at a specific location.
► In this case, medium loss coefficient screens installed to half the fan platform height (with the remaining space below the fan platform left open) provided the best performance.
► Each ACC installation should be evaluated on its own merits since factors such as the prevailing wind direction, the surrounding topography, the ACC configuration and the nature of the fans will influence the nature of the optimum wind screen location and configuration.