| The NOx emission of China has been the highest in the word.And it has brought more and more serious damages.So it is necessary to research on the formation mechanism and control technology of NOx.In this paper, Ceramic kilns fueled with gaseous fuels has been studied.We measured the NOx emissions of roller kiln, tunnel kiln and shuttle kiln respectively. Then we learn the status of NOx generating within the kilns through simulation.At last, Correspond measures has been put forward to reduce NOx emissions for these Influence factors.It is generally believed that nitrogen oxides include three kinds, such as thermal-NOx, prompt NOx and fuel-NOx.But by measuring we found another type of NOx decomposed while heating the nitrogen-containing compound in the material is heated. We call this type NOx for material NOx.The temperature we measured in the ceramic kilns are generally less than 1200?. In this case, there is only a small amount of thermal-NOx generated, Prompt NOx become the most important product in the kiln.Furthermore this paper also analyzed the influencing factors to the ceramic kiln NOx generating by modeling and calculation, including temperature, gas residence time, excess air coefficient, the type of fuel, material and furnaces and so on. Thermal NOx is mainly affected by temperature, gas residence time, excess air coefficient and the type of kiln. Prompt NOx is mainly influenced by the type of fuel and excess air coefficient. The formation of fuel NOx depends on the nitrogen content of the fuel.The type of material determines whether there is material NOx generated in the exhaust gas.At last, this article made several low NOx improvement programs against the favorable and unfavorable factors caused NOx generation in current situation, including to optimize the operating conditions, increase the flue gas recirculation system of the roller kiln and tunnel kiln,and use premix burner instead of diffusion burner in furnaces fueled with natural gas. |
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