Numerical Simulation Of NO_X Content And Fluid-Solid Coupling Heat Transfer In Tunnel Kiln Based On FLUENT

In this article,firing brick tunnel kiln in Zhejiang province was examined.The firing process parameter as a guideline,computational fluid dynamics and combustion science knowledge as a theoretical support,NO_X and gas distribution,the pressure field in firing zone,fluidsolid coupled heat generation mechanism in fired brick tunnel kiln cooling zone was used computer technology to simulation.This article adopts the method that the field test contrast with the result of numerical simulation.Research working mainly includes the following aspects:1.According to a tunnel kiln fired brick as prototype in Zhejiang province,firing zone model can be divided into three areas: the burner area,brick stack area and the fluid region.Cooling zone can be divided into two areas: brick stack area,the fluid region.This paper focuses on the parameter of thermodynamic set and established,such as the turbulence models,combustion model,radiation model,NO_X generation model,fluid-solid coupling radiation model.Finally using SIMPLE algorithm to discrete each of mathematical model and solves.2.Investigations of how the cooling air rate affects the NO_X content in the firing zone.NO in the kiln contain thermal type NO and rapid type NO.Through change wind speed in this paper analysis the content of thermal type NO and rapid type NO.Reasonable wind speed can reduce the NO emissions and reduce the production cost.3.Investigations of how the cooling air rate affects the brick kiln temperature and cooling temperature difference.Increases wind speed to changed gas flow rate and the state of gas flow in the kiln,decrease the brick temperature,this phenomenon influences the temperature difference,first decline then rising.The main of the gas generating turbulence phenomena impact the temperature and the temperature difference in the kiln.Select the appropriate wind speed can reduce the temperature difference between the bricks and improve the quality of bricks.4.Investigations of how the effects of different brick arrangement and different porosity on the brick cooling along the cooling zone.The studies have shown that when the bricks thin code the gas resistance is small in kiln,speed flower,temperature drop faster than brick yards dilute.Increase porosity can decrease the average temperature.The results show that: The results of numerical simulation close to test value,select the appropriate wind speed can effectively reduce the generation amount of NO_X in kiln,it also can reduce the temperature difference on the sections of bricks,it also evident when changes the stacked way of bricks and the porosity affect on the temperature and the temperature difference.It's also beneficial to improve the quality of bricks,lower production costs and reduce environmental pollution.