煉焦爐爐牆、爐頂、以及昇騰管積碳在煉焦過程中會逐漸附著積碳。積碳累積至一定厚度後，將造成產氣通道部分堵塞，加料及煉焦過程中發生細煤粉與爐氣逸散汙染，推焦作業時將增大推焦阻力，嚴重時引發推焦困難，加速焦爐老化。此外，積碳層亦會影響由燃燒室傳遞至煉焦室之熱傳係數，降低熱傳效率，故清除積碳一直是焦爐維護的重點工作之ㄧ。
本研究的重點工作為建立三維煉焦爐積碳燒除暫態模型，用以模擬煉焦爐三維實際尺寸(包含加熱牆矽磚、爐頂磚、爐底磚)的積碳燒除作業。研究將進行自然對流、強制對流與插管強制對流之暫態積碳燒除模式模擬，協助現場製程選擇最佳的現場作業模式。
結果顯示積碳燒除效果隨強制空氣流量增加而越佳，可提升流量來提升燒除效果，但當流量過高時也可能造成爐壁溫度過低的情形。此外比較強制對流與插管強制對流，結果顯示質量流率約為強制對流的2/3時，其燒除速率已比直接強制對流高13%，且燒除位置接近較厚的積碳層區。因此，在有限時間內操作積碳燒除作業，以插管強制對流較為合適。
三個案例中，除了自然對流因流場不穩定，積碳燒除位置一直變化外，(插管)強制對流的積碳燒除區域很快達到穩定且變動小。因此，(插管)強制對流可用穩態模擬來評估其燒除效果，以縮短模擬所需時間。

Carbon accumulation occurs significantly on the walls of inside a coke oven and it may cause serious blocking problems during the coke-making operation. Therefore, the coke oven is scheduled regularly to burn the accumulated carbon under maintenance. Due to the slow combustion rate of deposited carbon, the maintenance time is often long and reduces the yield rate.
The study focused on a 3D unsteady coke oven burning model to simulate the real coke oven including heat blocking materials It simulated different convection conditions, which were natural convection, force convection by air blower and force convection by a nozzle pipe, to assist field personnel to select the best operating mode.
The burning rate of solid carbon is dominated by the oxygen diffusion, so a forced inflow is proposed to increase the carbon-burning rate. However, if the air inflow rate is too high, it will lower the oven wall temperature and consequently the carbon-burning rate may be slowed down, even terminated.
The results showed that more fresh air flow could increase coke burning rate. When flow rate was too high and cool down the oven wall temperature, it may be below the brick safety temperature and the wall brick was damaged. Comparing the simulation results of force convection by air blower and a nozzle pipe, it showed that when the mass flow rate of force convection by a nozzle pipe was 33% smaller than that by air blower, the coke burning rate was 13% higher than force convection by air blower and the burning location was closer to the thicker coke zone. Thus, the method using the forced convection by a nozzle is more time-efficient to coke burning operation.
In these three conditions natural convection resulted in an unstable flow field and the coke burning position will change a lot, while the flow field of force convection by air blower could quickly reach a relatively stable state. As a result, a steady state simulation of forced convection by air blower can be used to evaluate the coke burning rate and shorten the simulation time.

論文審定書 i
誌謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 vii
表目錄 x
第一章 序論 1
1.1研究背景 1
1.2文獻回顧 5
1.3研究目的 8
第二章 研究方法與數值模型 9
2.1研究方法 9
2.2理論模式 9
2.2.1紊流模型 10
2.2.2化學反應模型 11
2.2.3輻射模型 12
2.3幾何模型與邊界條件 13
2.4網格模型與收斂標準 18
第三章 結果與討論 20
3.1三維穩態模擬結果 20
3.2二維模型化學反應參數分析 29
3.3自然對流模型30分鐘燒除結果分析 33
3.4三維大風機強制對流模擬 37
3.4.1三維大風機強制對流模型30分鐘燒除結果分析 37
3.4.2大風機強制對流流量分析 41
3.4.3三維大風機第四加料口燒除測試 44
3.5三維插管強制對流模擬 46
3.5.1三維插管強制對流模型30分鐘燒除結果分析 46
3.5.2插管強制對流入口壓力測試 50
3.6三維燒除模型之燒除結果比較 53
第四章 結論 56
後續工作 57
第五章 參考文獻 58

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