Study And Numerical Simulation On The Firing Zone Structure Of Three Layer Foaming Ceramic Tunnel Kiln

China is a country with a civilization history of 5,000 years.In the development process of Chinese civilization history,ceramics run through the whole history of civilization.In the process of ceramic development,the replacement of ceramic firing equipment has provided a strong technical support for the development of ceramic products.According to the firing characteristics of different ceramic products,the corresponding ceramic kiln was designed and built.Foamed ceramics is a product produced from industrial solid waste materials,and its production process is similar to that of ordinary ceramics.The main equipment for producing foaming ceramics is improved or newly designed tunnel kiln.Now,no matter it is single or double layer tunnel kiln,there will be problems such as high energy consumption,insufficient production capacity,common products and product fracture,and accidents are frequent.Based on the existing experience and technology,thermal workers have designed and built a three-layer foaming ceramic tunnel kiln with large cross section and large space so as to improve the productivity and reduce the energy consumption.This paper takes the two-section kiln body with three-layer foaming ceramic tunnel kiln as the prototype,establishes a mathematical model by simplifying the attached structure of the kiln body,simplifies the burner and a series of means,and USES ICEM software to grid the model.According to the parameters set in the actual operation of the enterprise,the required numerical simulation boundary conditions were determined.Fluent software was used to simulate the model of the firing zone of the three-layer foaming ceramic tunnel kiln.The heat transfer characteristics,flow characteristics and future adjustment direction of kiln design were studied by numerical simulation.Through the analysis of the cloud map of simulation results,the following main conclusions are obtained:(1)It can be seen from the simulation results of the firing speed of the three-layer foaming ceramic tunnel kiln that the smoke ejected from the nozzle and shot into the kiln had a small disturbance mixing effect on the mainstream smoke in the kiln,and the flame length is not enough.It is found from the cloud image that a low velocity zone will be generated near the burner,where the temperature is low and uneven.The velocity stratification is serious in the kiln,and there are many vortices in the velocity field.The temperature field in the kiln is affected by the velocity field,resulting in the unevendistribution of temperature field in the kiln.From the temperature simulation results,it can be seen that the temperature in the left and right sides of the kiln is relatively uniform and higher than that in the middle of the kiln.The maximum temperature difference can reach 15 K and the lowest is 9K.(2)Through the analysis of the velocity field and temperature field of each layer of product,it can be known that the temperature of the upper and lower surfaces of the same product is not uniform,resulting in many velocity layers.By observing the temperature field and velocity field cloud diagram of the same section of two adjacent burners in each layer of the same cross section,it can be seen that there will be a low-temperature zone and a low-flow zone between each two adjacent burners.Which is the flue gas backflow generated by the jet flows of the two burners,and the heat transfer rate of the flue gas convection generated by the back flow is slow.(3)There is flue gas flow in the gap between the kiln car and the products in the kiln car,as well as the gap between the products and the kiln walls on the left and right sides,and vortexes are easy to be generated in these areas,which can hinder the flow of flue gas and easily cause low-temperature areas.(4)The burner jet flow is affected by the distance between the bottom,products and the top of the kiln,that is,the combustion space of each row of burner is not the same,which affects the development of the burner jet flow,and the interaction between adjacent burners becomes more prominent.The combustion space of each row of burner should be appropriately increased.