Research On The Operation Optimization Of The Fans Of 600MW Direct Air-cooled Units

A mathematical model under variable condition for the cold end system was established taking the 600MW direct air-cooled unit as a research object, respectively researching for the effect on the condenser pressure of exhaust steam heat load, inlet air temperature of the condenser, windward air velocity,tube inside fouling resistance and tube outside fouling resistance.And the characteristic curve under variable condition for the air-cooled condenser was drew. The effect of ambient horizontal wind velocity on the condenser pressure was revealed according to the variable condition characteristic of the condenser. The temperature field distribution and flow field distribution of the air-cooled platform in prevailing wind direction was studied by means of the three-dimensional physical model of air-cooled island, finding that regional differences of the output for the fans in different parts of the air-cooled island were existed because of the effect of ambient horizontal wind. The output of fans in the first row and the first column of the windward side was poorer than any other regions. Aiming at the feature that the heat-exchanging capacity of air-cooled units in these areas was poorer than any other parts, the fan cluster which was divided into three regions were operated step-by-step, finding the optimal operation speed of fans in every area. The optimal operation speeds of fans in three areas with the changes of environmental wind speed, environment temperature and the unit load were found and the fan cluster optimization operation scheme was put forward in the situation of the variation of wind velocity, wind temperature and the unit load. During the period that wind velocity rised form 3m/s to 10m/s, the optimal operation speed of fans in the first row of the windward side was between 78r/min and 86r/min, the optimal operation speed of fans in the first column of the windward side was between 68r/min and 84r/min, the optimal operation speed of the rest fans was between 42r/min and 48r/min. During the period that wind temperature rised form 18℃to 34℃, the optimal operation speed of fans in the first row of the windward side was between 70r/min and 76r/min, the optimal operation speed of fans in the first column of the windward side was between 62r/min and 66r/min, the optimal operation speed of the rest fans was between 36r/min and 40r/min. During the period that the unit load rised form 60% to 100%, the optimal operation speed of fans in the first row of the windward side was between 56r/min and 78r/min, the optimal operation speed of fans in the first column of the windward side was between 54r/min and 68r/min, the optimal operation speed of the rest fans was between 26r/min and 42r/min. Which provided theoretical reference for the economic operation and control regulation of fan cluster of direct air-cooled unit under different environment parameters and unit load and reference for the layout and parameter design of fan cluster.