Numerical Simulation And Optimization For Dry Environment Of Tunnel Kiln

Since the reform and opening on, the brick-tile industry has got a rapid development in China. Tunnel kiln also gradually becomes the preferred brick-tile roasting and brick-tile drying equipment, but in our country, restricted by technological capability, it was always built shoddily. The tunnel drying kiln is a kind of continuous working equipment for brick drying, which can directly influence the brick production. To ensure reasonable drying system, control energy consumption, reduce brick defect and reduce production cost, it is necessary to study the dry environment of tunnel drying kiln and thermodynamic process of brick drying.Porous media theory and computational fluid dynamics was introduced to model and analysis internal environment of tunnel drying kiln. Field measurement and numerical simulation were combined to research drying regime of brick in tunnel drying kiln. The main conclusions are as follow:(1)Energy consumption of tunnel drying kiln was analyzed by systematic heat balance testing, and moisture content of dried brick and other relevant data were collected. The test results show that thermal efficiency of tunnel drying kiln was only27.04%, and moisture content of dried brick was5.6%, which indicate the kiln had a bad drying result and the energy was wasted. The main reasons are the low send-hot-air temperature, poor sealing and unreasonable tuyere design.(2)Evaporation rate of brick moisture was major affected by temperature, humidity, wind speed of drying medium and moisture content of the brick. To build an evaporation rate model of brick moisture, all impact factors were coupled together and simplified. Evaporation rate of brick moisture was compiled by User Defined Function of Fluent, and CFD model of operational tunnel drying kiln was built.(3)Temperature field, humidity field and velocity field of operational tunnel drving kiln were simulated by Fluent software. The results show that numerical simulation results for dry environment of drying kiln are basically matched with thereality. According to the simulation results, the moisture content of dried (?)ef after drying was7.3%, which is close to test value, indicating the established CFD model has a high accuracy.(4)According to drying defects of the tunnel drying kiln, three kinds of optimization method, the tunnel drying kiln sealing optimization, hot flue gas temperature optimization and tuyere layout optimization, are put forward, and the drying conditions of the tunnel drying kiln after optimization was forecasted using the established CFD model and numerical simulation method. The optimization results show that the air leakage in the tunnel drying kiln has a greater influence on adobe, the reduce of the leakage air volume can greatly improve the effect of adobe dry, and in the serious air leakage case, increasing sending hot air temperature has a very small effect on the tile drying. In addition, it is conducive to drying brick when hot air inlet port and tidal air outlet port are placed in both ends of tunnel drying kiln.