本研究利用COMSOL Multiphysics®商用套裝軟體，進行數值模擬探討管狀吸附助效甲烷蒸汽重組反應之產氫狀況。使用Ni/ Al2O3為觸媒、CaO為吸附劑，在固定床中，分析吸附劑的添加、反應器管徑、入口進料空間速度等操作條件對反應結果的影響。氧化鈣吸附劑的添加量為40 g，探討的反應器管徑為10 mm、30 mm及60 mm，入口進料WHSV (Weight hourly space velocity) 為0.67 h-1及4.03 h-1。
透過數值模擬的結果，可以發現甲烷蒸汽重組所產生氫氣的莫耳分率約71%。加入氧化鈣吸附劑可以減少產品氣中CH4、CO及CO2濃度並提高甲烷轉化率，同時使氫氣莫耳分率大幅上升至96%左右。吸附劑的添加對於甲烷蒸汽重組反應確實會有正向的影響。
觸媒床前段的二氧化碳生成率最快，越往下游越慢，二氧化碳吸附率則是先上升後下降。到了觸媒床中後段，二氧化碳生成率與吸附率相當。化學反應在觸媒床入口附近造成吸熱，其餘位置皆造成放熱，導致不均勻的溫度分布，進而影響反應器性能。
在二氧化碳破出前，隨著管徑變大，WHSV=0.67 h-1時，甲烷轉化率及氫氣莫耳分率皆略為上升，WHSV=4.03 h-1時甲烷轉化率及氫氣莫耳分率皆略為下降。在不同的空間速度下，管徑對吸附助效甲烷蒸汽重組反應器性能的影響在定性上是不同的。

The purpose of this study is to investigate the performances of sorption-enhanced methane steam reforming in a tubular reactor for hydrogen production by running numerical simulations with COMSOL Multiphysics® software. In this study, we used Ni/ Al2O3 as catalysts and CaO as sorbents which were packed into the reactor to setup the fixed bed reactor. We analyzed the performances of the system with sorbents added, with different tube diameters of reactor and with different space velocity. The amount of sorbents added was 40 g. The tube diameters of reactor were 10 mm, 30 mm and 60 mm, the WHSV were 0.67 h-1 and 4.03 h-1.
For a small WHSV of 0.67 h-1 before the CO2 breakthrough, there exist simultaneously a low temperature region and a high temperature region inside the catalyst/sorbent bed. They are located in the central region near the inlet and the rear of the catalyst/sorbent bed, respectively. The temperature distribution is more non-uniform for larger tube diameter (D). The range of high temperature region is significantly enlarged for a larger tube diameter. This will enhance the reactor performance. Both the CH4 conversion and the H2 molar fraction are slightly increased with the increase of D. This shows a significant improvement of reactor performance, as compared to conventional SMR at the same operation conditions.
For a small WHSV of 0.67 h-1 after CO2 breakthrough, the endothermic reaction of SMR totally dominates. The high temperature region disappears. The range of low temperature region enlarges quickly with the increase of D. Both the CH4 conversion and the H2 molar fraction are remarkably reduced, while the CO molar fraction are significantly increased.
For a higher WHSV of 4.03 h-1 before CO2 breakthrough, both the reaction time for steam reforming and CO2 sorption become much shorter. Thus the range of low temperature region becomes larger. No more existence of high temperature region inside the catalyst/sorbent bed for D=30 mm. The CH4 conversion is low due to low temperatures. Both the CH4 conversion and H2 molar fraction are slightly decreased with the increase of D. The CH4 conversion and H2 molar fraction are remarkably lower than those for WHSV of 0.67 h-1 before CO2 breakthrough.
The effect of tube size on the reactor performance before breakthrough is qualitatively different for small WHSV and large WHSV. In the industry application, a reactor with a large tube diameter is favoured, and the effect of non-uniform temperature distribution has to be considered in the design of SE-SMR reactor.

第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 3
1.3 研究目的 10
第二章 數值方法 11
2.1 反應器 11
2.2 基本假設 13
2.3 邊界條件 14
2.4 統御方程式 15
2.4.1 質量守恆方程式 15
2.4.2 動量方程式 15
2.4.3 能量方程式 16
2.4.4 成分方程式 16
2.5 化學反應 18
2.5.1 甲烷蒸汽重組反應模式 18
2.5.2 氧化鈣吸附反應模式 19
第三章 結果與討論 21
第四章 結論與未來建議 37
4.1 結論 37
4.2 未來建議 39
參考文獻 40

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