Numerical Simulation And Transformation Study On The Flow Field In Denitration Reactor Of A 600MW Unit

Nitrogen oxides(referred NOx) is recognized as one of the major air pollutants, which is not only capable of forming nitric acid rain, but also the formation of photochemical smog and one of the main cause of the ozone hole. With the increasing of NOx emission standards for coal-fired power plants in China, how to ensure continuously high denitration efficiency of the denitrification system has become critical. Selective catalytic reduction method with its high denitration efficiency and mature technology become the main choice for coal-fired power plant denitration. However, due to the technology started late in China, there are some problems in the design and actual operation. Taking the SCR denitration system of a 600 MW power plant boiler as the research object, this paper proposes several improvement program for the structure of the SCR reactor, then determines the optimum model through comparison of numerical simulation and verify optimization results of the SCR system which combined with structural of field SCR reactor.In this paper, the SCR system research work mainly include the following two parts: one is for the problem of the ammonia and flue gas mixing unevenly in the SCR reactor. Through the simulation optimization adjustment for the SCR reactor inlet, the uniformity of velocity field for the flue gas into the ammonia injection position is improved, and then the goal of optimization of ammonia and flue gas mixing degree is achieved. Result shows that the nonunitormity of smoke flow in focused primarily on the bending section of the inside corner, in which area can effectively reduce the guide plate spacing to improve the uniformity of flue gas velocity after the bend. At the same time,on both sides of guide plate with straight guide plate can further enhance the flow conductivity, and good mixing of the flue gas velocity distribution is advantageous to the ammonia gas and flue gas, as well as it could increase the SCR system performance. Two is for the problem of the inlet flue gas velocity distribution in the SCR reactor catalyst layer. Increasing or decreasing the guide platein catalyst layer inlet position is used to optimize the distribution of flow field in the flue gas in the reactor, and the detailed numerical simulation for the different layout of the velocity distribution and the pressure distribution in the reactor has carried on through ANSYS 14.0 numerical simulation software. Result shows that Catalyst layer above the guide surface play the decisive role in the flow field of the reactor. By comparing several optimization scheme, the optimal arrangement scheme is achieved. Use the optimum solution for structural transformation of SCR reactor in plant, and analyze the results of it.This provide the reference for revealing the distribution of flow field in the SCR reactor and optimizing the design of guiding device.