臺灣博碩士論文加值系統

摘要
火力發電廠所排放出含有硫、氮、碳多成分氣體混合物是造成酸雨與溫室效應的主要原因。使用變壓吸附法濃縮及回收煙道氣中二氧化硫、二氧化氮與二氧化碳，使之再利用，為解決問題方法之一。近年來這方面的研究已成為處理火力發電廠廢氣之首要。

本研究主要利用模擬方式，採用雙塔四步驟與三塔六步驟兩階段真空變壓吸附程序，處理進料為0.5﹪SO2、0.13% NO2與18﹪CO2，其餘為N2之煙道氣，吸附劑分別採用Dowex MWA-1(weak-base resin)與13X zeolite。模擬時所用的氣體分離機構為平衡模式，假設吸附塔內的同一截面積上固、氣兩相瞬間達成平衡，且為非恆溫之變壓吸附模式，因吸附劑顆粒大，故可忽略吸附塔內壓力降。

此程序可將濃度為0.5﹪SO2濃縮至6.04%，回收率達83%；18﹪CO2濃縮至75%，回收率達62%；探討各製程操作變數(諸如：沖洗比、進料壓力與各個步驟操作時間等等)對程序效能的影響。

關鍵字：二氧化硫、二氧化氮、二氧化碳、氣體混合物、模擬、真空變壓吸附

ABSTRACT

The major cause for acid-rain and greenhouse-effect phenomena is the emission which carries gas mixture containing components sulfur，nitrogen and carbon from power plants that burn fossil fuel. The concentration and recovery of SO2，NO2 and CO2 from flue gas is important in solving such pollution problem. Vacuum swing adsorption (VSA) is a feasible technology for such purpose.
This study employes a two-stage VSA to concentrate and recover SO2，NO2 and CO2 from flue gas. The first SO2-VSA is a dual-bed four-step process using Dowex MWA-1 resin as adsorbent, and the second CO2-VSA is a three-bed six-step process using 13X zeolite as adsorbent. Non-isothermal simulation is performed for separation of SO2/NO2/CO2/N2 (0.5/0.13/18/81.37 vol %) system. This study uses the equilibrium model and the pressure drop can be neglected.
The SO2/CO2 (0.5/18 vol %) in the feed could be concentrated to (6.04/75 vol %) in product stream, having a recovery of (83/62 vol %) in this study. The effects of operating variables such as P/F ratio, adsorption pressure, steps time were investigated on the performance of this study.



Key words: sulfur dioxide, nitrogen dioxide, carbon dioxide,
gas mixture, simulation, vacuum swing adsorption

目 錄
目錄 Ⅰ
表目錄 Ⅲ
圖目錄 Ⅴ


第一章 緒論 1

第二章 簡介與文獻回顧 3
2.1 變壓吸附法之簡介 3
2.1.1 變壓吸附基本原理 3
2.1.2 吸附劑及其選擇性 5
2.1.3 基本的變壓吸附程序 6
2.2 文獻回顧 8
2.2.1 理論之回顧 8
2.2.2 PSA程序的發展與改進 10
2.2.3 PSA製程在回收氣體污染物的應用 13

第三章 理論 16
3.1 基本假設 17
3.2 統制方程式 18
3.3 吸附平衡關係式 22
3.4 參數推導 29
3.4.1 軸向擴散係數 29
3.4.2 管壁的熱傳係數 30
3.5 起始條件與邊界條件 31
3.6 求解的方法 32
3.6.1 閥公式 32
3.6.2 求解步驟 33

第四章 製程描述 35
4.1 程式驗證 37
4.1.1 第一程序SO2-VSA(四步驟製程) 38
4.1.2 第二程序CO2-VSA(六步驟製程)…………….. 40
4.2 常數與操作條件 44

第五章 結果與討論 51
5.1 模擬結果與驗證 51
5.2 沖洗比的影響….…………………………..…………56
5.3 進料壓力的影響….…………………………..………62
5.4 步驟時間的影響….…………………………..………68
5.5 結論………………….………………………..……... 81

符號說明 82
參考文獻 84
附錄A 流速之估算方法 90
附錄B 環保法規 94

表目錄

表4.1 SO2-VSA吸附塔及吸附劑特性 45
表 4. 2 CO2-VSA吸附塔及吸附劑特性............…........................... 46
表4.3氣體分子擴散係數 47
表4.4 SO2-VSA進料組成與操作狀態 47
表4. 5 CO2-VSA 進料組成與操作狀態......…………………............48
表4.6氣體在Dowex MWA-1上的LRC吸附曲線參數……48
表4.7氣體在13X上的Langmuir吸附曲線參數 ……...…49
表4.8 SO2-VSA Skarstrom Cycle與CO2-VSA三塔六步驟程序之步驟時間………………………………………………………..49
表4.9 SO2-VSA吸附塔操作流程循環順序………………………..50
表4.10 CO2-VSA吸附塔操作流程循環順序……………..……….50
表5.1 Effect of purge/feed ratio on PSA performance for SO2 concentration(feed:SO2=0.5%) 52
表5.2 Effect of purge/feed ratio on PSA performance for NO2 concentration(feed:NO2=0.13%)……………………………...……..52
表5.3 Effect of purge/feed ratio on PSA performance for released waste (feed:SO2=0.5%) 53
表5.4 Effect of purge/feed ratio on PSA performance for released waste (feed:NO2=0.13%) 53


表5.5 沖洗比對SO2濃度與回收率之影響 56
表5.6 沖洗比對CO2濃度與回收率之影響 59
表5.7 進料壓力對SO2濃度與回收率之影響 62
表5.8 進料壓力對CO2濃度與回收率之影響 65
表5.9 T1時間對SO2濃度與回收率之影響 68
表5.10 T2時間對SO2濃度與回收率之影響 71
表5.11 T1時間對CO2濃度與回收率之影響...................................75

表5.12 T2時間對CO2濃度與回收率之影響..................................78


圖目錄

圖3.1 電腦程式之求解流程圖 34
圖4.1 程序示意圖..............………….............................................36

圖4.2 Skarstrom Cycle……………………………………..37

圖4.3三塔六步驟 42
圖4.3三塔六步驟(續) 43
圖5.1-1,2改變沖洗比之模擬與文獻之結果比較圖…………...54
圖5.2-1不同沖洗比下，SO2濃度與回收率的變化曲線圖…..... 57
圖5.2-2不同沖洗比下，沖洗步驟結束時塔內SO2濃度分佈.....………………………………….……...........58
圖5.2-3不同沖洗比下，CO2濃度與回收率的變化曲線圖. 60
圖5.2-4不同沖洗比下沖洗步驟結束時塔內CO2濃度分佈……………………………………………………61
圖5.3-1不同進料壓力下，SO2濃度與回收率變化曲線圖…….63
圖5.3-2 改變進料壓力，吸附步驟結束時塔內SO2濃度分佈.64
圖5.3-3 不同進料壓力下，CO2濃度與回收率變化曲線圖….66
圖5.3-4改變進料壓力，吸附步驟結束時塔內CO2濃度分佈..67
圖5.4-1 改變T1時間，SO2濃度與回收率之變化曲線圖.…......69
圖5.4-2改變T1時間，吸附步驟結束時塔內SO2濃度分佈……70
圖5.4-3 改變T2時間，SO2濃度與回收率之變化曲線圖…….72
圖5.4-4 改變T2時間，吸附步驟結束時塔內SO2濃度分佈……73
圖5.4-5改變T2時間，沖洗步驟結束時塔內SO2濃度分佈……..74
圖5.4-6改變T1時間，CO2濃度與回收率之變化曲線圖……..76

圖5.4-7改變T1時間，沖洗步驟(Ⅰ)結束時塔內流量分佈…….77

圖5.4-8改變T2時間，CO2濃度與回收率之變化曲線圖……...79

圖5.4-9改變T2時間，沖洗步驟(Ⅱ)結束時塔內流量分佈…..80

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