The Matching Principle Of Anti-freezing Heat Load Capacity And Its Applications For Air-Cooled Condenser In Extreme Cold Regions

China’s energy rich "Three North" has the cold winter weather, dry cooling system of power plants runs in the low temperature environment, so the fin tube bundles of air-cooled condenser will face severe anti-freezing protection.In this paper, the anti-freezing protection of air-cooled condenser cell in power plants at extremely cold regions is discussed by using CFD numerical simulation method. Using the heat exchanger models, the heat load capacity model of the exhaust steam inside the finned tube bundles of air-cooled condenser cell at various exhaust steam flow rate, steam quality, back pressure of turbine is developed. Based on the freezing point of water, the theoretical maximum allowed heat load of cooling air is determined by calculating the heat rejection of exhaust steam from the condensation heat of steam and the sensible heat to the freezing point. The anti-freezing heat load capacity matching principle is proposed by analyzing the freezing mechanism of exhaust steam, based on which the anti-freezing exhaust steam flow rate, back pressure of turbine and flow rate of fan are presented. The correlations among the ambient temperature, flow rate of fan, exhaust steam flow rate, back pressure of turbine and steam quality are discussed. The safe exhaust steam flow rate, protective exhaust steam flow rate by back pressure adjustment, safe ambient temperature at full rotational speed of fan are suggested, which are of benefit to the anti-freezing protection methods and measures of dry cooling system at extremely cold regions. On the basis of the theoretical and numerical results of the anti-freezing running parameters, the anti-freezing approaches are suggested from both the steam side and air side of air-cooled condenser.