Study On Inner Flow Distribution Of Direct Air-cooled Condenser

The exhaust steam pressure is one of the criterions for determine the security and economy operation of direct air-cooled condenser (ACC).The different temperature of various condenser units reflect the uneven distribution of each unit of condenser from the running direct air-cooled units. Studying the flow rate of condensate distribution and calculating the exhaust steam pressure precisely makes great sense on the performance of direct air-cooled condenser. By developing mathematical model from steam turbine exhaust to steam condenser exhaust, obtaining the steam condensation of each unit from heat transfer computation model of condenser unit,then taking the impact of pressure loss of steam distribution ducts and local resistance of pipe, combined with site infrared thermal imagery experiment, it revealed the distribution discipline of air-cooled condenser in different heating load and ambient conditions by the whole computation model of air-cooled island. It also indicated that the exhaust steam distribution and exhaust steam pressure influenced by the variation of ambient winds which include ambient wind velocity and direction and can be used as theoretical bases to optimize operation of fan cluster. After known the variation of the air side heating load, the condensate distribution of each units were calculated by the way of coupling the numerical simulation and procedure iteration, the condensate of counterflow of ACC units are less than that parallel-flow for the coefficient of heat transfer was different. The condensate of the first parallel-flow ACC adjacent to the main exhaust steam pipeline is less than that of other ACCs. This is because the exhaust steam flow rate is relatively high near the bend area and form eddy along the flow direction which would add the resistance into tubes. Furthermore, the condensate of the last parallel-flow ACC is also less than that in the middles due to the increasing of pressure loss which caused decreasing of flow speed of steam. At the same ambient wind direction, the exhaust steam pressure increased with the increment of ambient wind velocity. And the exhaust steam pressure also various with the variation of wind direction and went to the peak at the wind direction angle of negative 90°which called the ambient wind behind stove.