分支進料對丙酸丁酯反應蒸餾系統的影響

Design and Control of Reactive Distillation for n-Butyl Propionate System with Split Feed

詹政訓(Cheng-Hsun Jan)

指導教授 ： 黃孝平

共同指導教授 ： 錢義隆(I-Lung Chien)

國立臺灣大學/工學院/化學工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.02222

摘要

結合反應與分離程序之反應蒸餾系統近來廣泛受到討論與研究，由於在設備成本及操作成本上較傳統製程大幅減省的優勢下，關於不同酯類的反應蒸餾系統之研究相繼於近年被提出。
本文承接林谷囿(2004)對丙酸丁酯反應蒸餾系統的設計與控制之研究，但將丙酸進料分為兩股，並由另一塔板進入蒸餾塔中。經過年總成本最適化的步驟後發現對於此系統，分支進料之後可使年總成本節省約10%，再沸器熱負載可節省約12%，且單位觸媒的效率有提高的效果。由此實驗可得一結論是將較重之反應物分成兩股並將其中較大之股流與另一較輕之反應物於同一板進料，另一股則在較高的板入料。將此結論應用到其他酯化反應蒸餾系統，如乙酸甲酯、乙酸丁酯和乙酸戊酯，卻發現乙酸甲酯和乙酸戊酯在進料分支後無法使年總成本減少，乙酸丁酯系統卻可獲得大幅的改善，年總成本節省約30%而再沸器熱負載量則可減少50%。
除靜態設計外，本文分別對此兩種不同進料狀況下之系統進行動態模擬，對於進料不分支統有兩種控制架構，而進料分支系統則討論系統中的第三個自由度之可用性。利用靈敏度分析、非方形相對矩陣(NRG)及奇異值分解(SVD)來判斷最靈敏的溫度控制板。之後便用相對增益矩陣來進行配對。ATV調諧控制器參數。對此兩種不同進料情況之系統作進料流量及進料純度擾動來測試其干擾承受及排除能力，但因此兩種系統在進料流量擾動時皆會在塔底產品產生丙酸濃度偏移的問題，所以加上前饋控制來使塔底產品濃度接近設定點也如預期可以得到不錯的表現。

關鍵字

分支進料 ； 丙酸丁酯 ； 反應蒸餾 ； 乙酸丁酯 ； 乙酸甲酯 ； 乙酸戊酯

並列摘要

A Reactive distillation column that combines reaction and distillation processes into one single unit is known to have significant advantages on reducing capital and operating costs of a process. Different esterification processes using RD columns have been studied and published in literature lately.
Subsequent to Lin’s previous work (2004), “design and control of reactive distillation system for n-butyl propionate”, it is the purpose of this research to study if splitting the feed inputs to the RD column can improve the economics and operation of the process. It is found that, after splitting, the TAC decreases for 10% and reboiler duty decreases for 20% in this particular case. By this splitting of the feed, the specific reaction rate is found to increase at the same time. The resulting optimal design shows that the heavier reactant feed is splitted into two portions. The bigger portion of feed goes along with the lighter reactant to the same tray, and the remaining portion is fed to some tray in above. It is found that, by applying this result to other esterification processes, significant reduction of TAC and reboiler duty may be procured. Three of esterification processes ( Metyl-acetate, butyl-acetate, amyl-acetate) were studied. It was found that the spilt of feed favors the RD processes where reaction equilibrium constant is larger. For example, for butyl-acetate process, TAC can decrease as much as to 30% and the reboiler duty to 50%.
The control strategies for optimal n-butyl propionate processes (single feed and split feed) are also studied. Two control strategies for either case that has single or split propionate acid feed are considered. For temperature control, the non-square relative gain (NRG) and singular value decomposition (SVD) together with sensitivity analysis are used to locate the right trays where temperatures are to be controlled. Relative gain array (RGA) is used to select pairing and characterize the interaction of the control loops, ATV is used to tune the controller parameters. Flow rate disturbance and feed purity disturbance are introduced to test the disturbance rejection abilities of these systems. Since offsets in product composition are found, a feed forward control strategy to keep the composition close to its set-point is also considered. It is found that the split of feed does not have essential effect on the control of such processes.

並列關鍵字

split feed ； butyl propionate ； reactive distillation ； buty acetate ； metyl acetate ； amyl acetate

參考文獻

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