高爐出鐵口處耐火磚在出鐵前後的熱傳與熱應力之數值分析

Abstract

本文主要是先以CAD繪圖軟體建立三維高爐出鐵口處實體模型，再利用CAE有限元素分析軟體COMSOL Multiphysics進行模擬計算，來分析高爐出鐵口處碳磚經過出鐵前鐵水累積受熱穩定狀態後，在出鐵水階段出鐵口處碳磚不同時間點的暫態熱傳與熱應力數值解。 利用循序漸進的方式，一開始先模擬彈性力學中二維圓盤平面應變問題，將理論解與數值解作比較。並由此延伸作三維圓柱模型與三維多層圓柱模型討論。建立完整三維高爐出鐵口處實體模型，匯入分析軟體當中進行模擬，並討論熱應力分佈情形的成因。並針對未確定材料參數做靈敏度分析，再來使用其它的真實碳磚材料來替換原先材料性質，來討論不同的材料造成熱應力的差異性。此外，由於高爐爐襯厚度隨時間而慢慢減少，因此必須針對不同爐襯厚度來做同樣的熱傳與熱應力分析，以便研判裂縫的產生是在什麼時候。期望藉由此模型的模擬計算來評估真實高爐出鐵口處的受力情形，並做為以後高爐碳磚選用的參考與安全改進之建議。

The objective of this thesis is to create a 3D model of the tap hole of a blast furnace by means of the CAD software and then import it into the Finite Element Method software ' COMSOL Multiphysics' to simulate the problem of transient heat transfer and thermal stresses of carbon bricks on the tap hole during the tapping process. First, numerical solutions for a 2D circular disk of a single-layer material will be simulated, which compare with analytic solutions obtained by the theory of elasticity. Second, geometry will be extruded from the 2D circular disk to a 3D cylinder. Moreover, the single-layer material is replaced to multi-layer materials in the 3D simulation. Then, the 3D geometry on the tap hole of a blast furnace followed by the physical model is constructed. Distribution of temperature and thermal stresses at carbon bricks on the tap hole of a blast furnace will be evaluated and further discussed. Next, sensitivity analysis is performed for undetermined material parameters. In order to investigate the variation of materials, different carbon bricks will be applied for comparison with the original material. As a matter of fact, with time passing by, the hearth carbon bricks of a blast furnace will be worn gradually. Hence, the thickness of hearth carbon bricks is reduced to a half and a quarter case contrasted with original thickness of them. This paper looks forward to evaluating the real stress state on a tap hole of a blast furnace by the results of simulation, and it can be the suggestion for choosing the carbon bricks of a blast furnace in the future.