Numerical Simulation And Field Research On The Flue Gas Bypass Between The Economizer And SCR

Nitrogen oxides(NO_x) are recognized as one of the major air pollutants,which will lead to a series of environmental problems such as acid rain and photochemical smog.With the rapid development of our country's economy,massive combustion of fossil fuels in power plants is one of the major reasons for increasing of nitrogen oxide emission.According to research,if effective measures can't be taken to reduce the emission of nitrogen oxides,by 2020 and 2030,China's total emission of nitrogen oxides will become 29 and 40 million tons respectively.Therefore,in order to realize sustainable development,China formulated the increasingly strict environmental standards.Compared with other denitration technologies,selective catalytic reduction denitration technology has became the most widely used method due to its early start,relatively mature technology and high denitration efficiency.Selective catalytic reduction denitration technology injects reducing agent such as ammonia and urea into system and makes them react with nitrogen oxides under the action of catalyst,generating pollution-free products such as nitrogen and water.But as a result of the fact that catalyst only has a good catalytic activity in certain temperature range,so the flue gas temperature often will not be appropriate when the power plants run at low load.In order to make sure the selective catalytic reduction system can work normally when the power plants run at low load,we often adopt the method of adding economizer bypass.Therefore,the study of economizer bypass flow field has important practical significance.In this paper,the SCR system research works mainly include the following two parts:First,to study the distribution of flow field in the SCR reactor bypass flue design after and access bypass flue design,setting up a 3d model from the economizer import to the SCR system export,by adjusting the bypass access position and section shape to find the best access uniform for gas distribution.Through calculating speed,pressure,temperature deviation found that SCR denitration tower internal flow field distribution is uniform,when the bypass section for 10mx3.2m rectangular,layout on the height of the horizontal flue is 3m.Second,through the simulation results and combining with the situation of the power plant to SCR renovation,after modification,compared with before modification find that speed deviation is increased but the whole denitration efficiency is improved.Through the above research to get the optimal way of flue gas bypass access,understanding after adding flue gas bypass flue gas flow state changes,for the practical application of economizer flue gas bypass provide effective reference...