Research On The De-whitening Technology Of Smoke Plumes In 600MW Coal-fired Units

Wet flue gas desulfurization(WFGD)is widely used in coal-fired units,which leads to the problem of “Wet plume”.Along with the country to the environmental question unceasing attention,to the wet smoke plume’s governance also receives the more and more attention.At the same time,many provinces and cities have included wet plume in environmental control policies.At present,the treatment of wet plume is mainly aimed at reducing the temperature and humidity of flue gas,and there are three technical routes: condensation methods,reheat method and condensation reheat method.Among them,MGGH is the most widely used technology in the flue gas reheat methods,and flue gas spray condensation is the more widely used technology in the condensation method.If conditions permit,the two can be combined.In this paper,for a 600 MW coal-fired unit,spray condensation technology is used for flue gas bleaching because of its proximity to water source.To the measured data of flue gas flow,flue gas temperature and the actual size of spray tower,using the ANSYS software to carry on the numercal simulation.First of all,the empty spray tower and adding a layer of spray are simulated.By changing the angle of flue gas inlet,the flow field,pressure field and velocity field of flue gas in the tower are analyzed.The results show that 15°is the best angle of flue gas inlet.According to this results,the flow field,pressure field and velocity field of smoke were calculated and analyzed by changing the number of spray layers.It is found that when the number of spray layers is changed,the influence on the velocity change along the height direction of the tower is very small and can be ignored,and the pressure drop decreases slightly with the increase of spray layer number.When the top two spray layers are used,the rectification effect on the flue gas is most significant.When the inlet angle and the number of spray layers are determined,the temperature field analysis is added.By changing the spacing between the two spray layers,the spray angle and the spray direction,it is found that when the above working conditions change,t he influence on the smoke velocity is very small and is ignored here.While the pressure drop decreases with the increaes of spray layers spacing and the decrease of the spray angle,and the change value is not large.Therefore,the temperature of flue gas outlet is taken as the criterion of spray structure parameter,and the spray layer spacing is 1.9m and the spray direction is 120°as the final spray parameter.Based on these parameter,the upper layer spray is changed to spray upward along the tower height,and the smoke temperature at the exit is obtained to be 315.6K,which is compared with the measured smoke temperature at the exit of the power plant at 320.15 K.The rationality of the methods used in this study is verified within the error allowable range,which can provide some theoretical guidance for the spray condensation de-whitening method.