Material Preheating Tower Design And Numerical Simulation Analysis Of The Preheating Process

Material preheating tower is the key equipment for production of new technology of waste heat recovery system of fused magnesia and an important part of the waste heat recovery. However, not much research has been done to investigate or analyze its thermal process. As a result, the operations on this equipment were mainly based on experience for a long time and lack of appropriate theoretical guidance. Hence, there is an increasing importance for developing proper physical and mathematical models by the method of numerical simulation and obtaining optimum operation parameters based on the essential understanding of the thermodynamic process of material preheating tower.In this dissertation, the design and calculation of the material preheating tower and the size of the equipment were determined. According to the characteristics of heat transfer in the preheating tower, two-dimensional simulation models Including the physical model and mathematical model and the theory of porous media model for heat transfer calculation were established using computational fluid dynamics software FLUENT6.3. Meanwhile, structured grid was used to discrete the computational zone. Standard κ-ε model was used to describe the air flow in the preheating tower, and the temperature field was simulated by two-equation energy model based on non-equilibrium thermodynamics in porous media built up by user-define-functions. To explore the factors affecting the preheating process, four parameters influencing heat transfer process of material preheating tower were optimized and analyzed, and the optimal operation parameters was proved by orthogonal experimental method.1. The temperature distribution of material preheating tower was obtained:As the time increases, the temperature difference between the material and the air is getting smaller and smaller, and the rate of material average temperature increasing with time is smaller.2. Four main parameters that influence the preheating process of material preheating tower were studied. Conclusions indicate that the range of6-8m/s, reducing the air velocity in inlet, however, the material average temperature is reduced, and the amount of waste heat utilization is down. Porosity within the range of0.37to0.45, reducing porosity, although the material average temperature of preheating is slightly lower, it can still increase the amount of waste heat utilization. To meet the process requirements of the material, reducing the material layer height can enhance preheating and the preheating period can be shortened. Material diameter within the range of0.08m-0.1m, reducing the diameter of the material is conducive to enhancing the heat transfer and improving the average material preheating temperature, and increasing the amount of waste heat utilization.3. By using orthogonal experimental method, air velocity in inlet, porosity, material layer height, material particle diameter were analyzed. These4parameters can be listed as follows in the order of their effects on experimental results:material layer height, porosity, air velocity in inlet, material particle diameter. Material preheating tower optimal working conditions are as follows:air velocity in inlet8m/s, porosity0.37, height of material layer7.5m, diameter of material particle0.08m.