Numerical Simulation And Optimization Of The Cooling Process Of The Sinter Cooler

Sinter cooler is an important equipment in sinter process in steel industry. However, not much research has been done to investigate or analyze its thermal process. As a result, the operation and improvement on this equipment were mainly based on experience for a long time. Hence, there is an increasing importance for developing proper physical and mathematical models and obtaining optimum operation parameters based on the essential understanding of the thermodynamic process of the sinter cooler.In this dissertation, a sinter cooler of an ironworks in China was studied. Focusing on the characteristics of heat transfer in the sinter cooler, mathematical models for heat transfer calculation were established using computational fluid dynamic software FLUENT6.3. Meanwhile, structured grid was used to discrete the computational zone. Standard k-εmodel was used to describe the air flow in the sinter cooler, and heat transfer between the air and sinters was simulated by two-equation energy model based on non-equilibrium thermodynamics in porous media built up by user-define-functions. To improve the utilization of waste heat recovery in the sinter cooler, five parameters influencing heat transfer process in the sinter cooler were optimized, and the optimal combination of these parameters was approved by orthogonal experimental method.The main conclusions in this investigation are as follows:1) The sinters and air temperature distributions in the sinter cooler were obtained:as the height increasing, the air and sinters temperatures increase gradually, and the temperature difference on the cross-section is small.2) The results obtained through numerical solution were compared with data measured from the sinter. Conclusions show the maximum error of the predicted air temperature in outlet of the sinter cooler is less than 10% compared to that from the measurement. This verifies the correctness of the present model.3) Interactions among the five main parameters that affect the cooling process of the sinter cooler were investigated. Conclusions indicate that in the range of 5～7.65m·s-1, increasing air velocity in inlet improves the waste heat usage, however, reduces the air temperature in the outlet of waste heat area. Increasing height of sinter layer in the range of 1.4～1.8m, reducing sinter particle size in the range of 0.025～0.04m and reducing porosity in the range of 0.35～0.5, all can increase the amount of the waste heat utilization and the air temperature in the waste heat area. In the range of 404-434K, with the increase of air temperature in inlet of waste heat area, the air temperature in outlet of waste heat area increases, but the amount of waste heat utilization will be reduced.4) By using orthogonal experimental method, sinter particle size, air velocity in inlet, height of sinter layer, porosity, air temperature in inlet of waste heat utilization area were analyzed. These parameters can be listed as follows in the order of their effects on experimental results:sinter particle size, air velocity in inlet, height of sinter layer, porosity, air temperature in inlet of waste heat utilization area. The optimum running conditions of the sinter cooler are as follows:sinter particle size 0.025m, air velocity in inlet 7.65m·S-1, height of sinter layer 1.8m, porosity 0.35, the air temperature in inlet of waste heat utilization area 404K.