Resumo

ZIPFEL, T.  e  KROGER, D.G.. A design method for single-finned-tube-row air-cooled steam condenser to avoid back flow of steam into any finned tube. R&D j. (Matieland, Online) [online]. 1997, vol.13, pp.68-75. ISSN 2309-8988.

In an air-cooled condenser (ACC) exhaust steam from the turbine is distributed via a distribution pipe or dividing header into numerous finned tubes or laterals in which most of it is condensed. The excess steam which is condensed in a later stage (dephlegmator) and the condensate is collected in a combining header. The steam flow rate entering the finned tubes is, amongst others, a function of the difference in pressure between the dividing to the combining header over the finned tube. As the pressure in the dividing and the combining header varies, the pressure difference over the finned tubes also varies. This variation can cause the flow distribution to be significantly non-uniform. In the design of an ACC, the flow distribution into the finned tubes has to be quantified to ensure that sufficient steam flows into each finned tube in order to avoid non-condensable gases from being trapped at the finned tube outlet causing so-called dead zones. In this paper, a simplified design method is presented with which an ACC can be designed such that the formation of dead zones is avoided. This method employs the pressure changes along both headers and the pressure differences over the first upstream and the last downstream lateral. A numerical example to demonstrate the application of the method is also presented.

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