臺灣博碩士論文加值系統

柴油的應用日益增加，然而燃燒柴油所伴隨的煙塵與煙灰嚴重影響環境與人類的生活，因此逐漸受到關注與管制。使用聚甲氧基二甲醚作為柴油添加劑可以顯著地減少煙塵排放，加上其與柴油絕佳的相容性，在未來將有很大的發展潛力。本研究針對其製程進行探討，先由上游的甲縮醛穩態、動態控制程序到下游的聚甲氧基二甲醚穩態程序，設計出可行的系統架構。

本研究前段提出以結合萃取蒸餾與反應蒸餾的程序，在室壓1 atm下製得高純度的甲縮醛(99.0 wt%)，並以年度總成本作為最適化函數，獲得最適化的系統設計變數包含回流比、精餾段、萃取段、反應段以及氣提段的板數。接著並深入探討其控制架構與消除干擾之策略，由閉環與開環溫度敏感度分析中提出三點溫度控制與雙點溫度控制架構，由實驗結果發現，以固定再沸器熱負載與甲醇進料流率比值的設計架構為最合適的選擇。

本研究後段探討下游的聚甲氧基二甲醚程序，先以再現文獻中實驗結果做為目標，製得純度達99.0 wt.%的OME 3-5，接著改變其設計、調整產品塔的塔壓，使其再沸器與高溫蒸氣溫差達20 K，再以最適化探討程序，決定包含三支蒸餾塔各別的總板數與進料位置。由最適化的結果中可以發現，第一支蒸餾塔存在再混合效應，使得分離效果不彰，因此遂提出以氣相回流的熱整合架構以消除再混合效應，而其結果顯示，再沸器總能量消耗可以降低，但降幅仍不敵額外加裝氣體壓縮器的購置成本，以及其昂貴的電力成本，因此證明此舉在經濟上並不可行。

The demand of diesel fuel is increasing in recent years in terms of transportation. However, the smog produced by burning diesel in the engine has been a major concern for the environment and human‘s health. One way to fix this is to add a promising diesel additive, Poly(oxymethylene) dimethyl ethers (OME 3-5), into diesel fuels to make it more well burned. In this thesis, two production processes will be the main focus including upstream methylal process and downstream OME process.

In the first half of this work, the upstream methylal process will be presented which is the integration of extractive and reactive distillation column and the production of high-purity methylal (99.0 wt.%) is guaranteed. The optimization in terms of total annual cost (TAC) will be implemented and the reflux ratio, rectifying, extractive, reactive and stripping stages will be determined. Furthermore, several control schemes will be introduced to see if the disturbances are rejected in the transient state. It is found that by fixing the ratio of reboiler duty to the feed rate of methanol is the most appropriate two-point temperature control strategy.

In the bottom half of this work, the downstream OME process will be presented. Results from the literature that 99.0 wt.% of OME 3-5 will be produced. Few improvements will be made to satisfy reasonable TAC optimization in terms of all feed stages and total stages. Results show that the remixing effect is occurred. A thermally-coupled design is then introduced to eliminate this effect. Though it reduces total reboiler duties in the process, it’s still not economically viable since it requires the installation of a compressor as well as its expensive electricity costs.

1. 緒論 1
1.1 前言 1
1.2 文獻回顧 9
1.2.1 甲縮醛系統 9
1.2.2 聚甲氧基二甲醚系統 11
1.3 研究動機 13
1.4 組織架構 14

2. 甲縮醛系統中之成分、熱力學及動力學模式 16
2.1 前言 16
2.2 成分的建立 17
2.3 熱力學模式參數建立與結果 18
2.3.1 選定熱力學模式與參數輸入 18
2.3.2 沸點排序、相圖(T-xy、P-xy)及相對揮發度 20
2.4 動力學模式建立與參數 26

3. 甲縮醛系統之程序模擬 31
3.1 前言 31
3.2 穩態架構設計：結合萃取蒸餾與反應蒸餾 32
3.2.1 設計理念 32
3.2.2 最適化設計 35
3.2.2.1 最適化過程 35
3.2.2.2 穩態結果與討論 42
3.3 動態架構設計：控制策略與干擾排除 48
3.3.1 基本控制概念 48
3.3.2 三點溫度控制架構 50
3.3.3 雙點溫度控制架構 58
3.3.3.1 固定回流比之雙點溫控 60
3.3.3.2 固定再沸器熱負載與甲醇進料流率比值之雙點溫控 67
3.3.4 控制結果與討論 74

4. 聚甲氧基二甲醚系統之成分、熱力學及動力學模式 76
4.1 前言 76
4.2 成分的建立 77
4.3 熱力學模式參數建立與結果 78
4.3.1 選定熱力學模式與參數輸入 78
4.3.2 沸點排序、相圖(T-xy、P-xy) 84
4.4 動力學模式建立與參數 92
4.4.1 化學反應總覽 92
4.4.2 主反應之反應機構 93
4.4.3 副反應之反應機構 95

5. 聚甲氧基二甲醚系統之程序模擬 97
5.1 前言 97
5.2 穩態架構設計：反應器與簡單蒸餾程序 98
5.2.1 設計理念 98
5.2.2 再現文獻結果與討論 100
5.2.3 最適化設計 105
5.2.3.1 最適化流程 105
5.2.3.2 結果與討論 110
5.3 穩態架構設計：反應器與熱整合蒸餾程序 116
5.3.1 設計理念 116
5.3.2 結果與討論 118

6. 結論 124

參考文獻 127
附錄 130
A. 年度總成本計算公式 130

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