ABE發酵生物丁醇高能效純化程序之設計

Abstract

丁醇普遍做溶劑、有機合成等用途，甚至有潛力作為交通運輸燃料使用，能量密度比乙醇高，更接近天然氣，此外，丁醇不親水特性能大幅減少對車輛的腐蝕性。在現今社會中，生質能源開始受到重視，因此生物丁醇有取代石油丁醇的高度潛力。生物丁醇的生產主要來自由微生物與小分子葡萄糖進行ABE發酵，此一程序會同時產出大量的乙醇和丙酮，但是酒精對於微生物有害，故需要操作在非常稀釋環境下發酵，因此丁醇純度相對非常低，必需耗費相當多的能源用於分離高純度的丁醇，本研究根據Patraşcu 等人文獻進行改良，透過製程改善，有效降低能耗。又為了讓副產品乙醇純度高於99.5 wt% (高於乙醇/水沸點組成)，安裝商業化薄膜－PERVAP○R2201打破共沸點使殘餘水分離。後續一系列的熱整合探討，並且進階探討塔堆積(column stacking)策略，最終結果，比起Patraşcu文獻設計，能耗減少達57%，每年費用則減少將近52%，不僅提升了產物純度，也大幅下降能源浪費問題。另外此研究也進行動態模擬，共分為無熱整合、有熱整合、有用塔堆積程序等三部分，皆以溫控方式取代組成控制，並且添加一些經驗公式改變控制器的設定點來改善操控結果，模擬擾動±10%進料和進料組成情況，結果得出以上三種純度偏差皆能小於0.05%，即使為較複雜的熱整合，溫度控制皆相當理想。

Butanol is generally used as a solvent, organic synthesis, etc., and even has the potential as a transportation fuel. Butanol is more energy density than ethanol and close to gasoline. However, biobutanol gradually replaces petro butanol since biobutanol can cut down energy crisis and environmental pollution problems. Acetone-Butanol-Ethanol fermentation is the main product of biobutanol method and also produces ethanol and acetone. Fermentation is essential to be operated in diluted surroundings since products are toxic to microorganisms. Thus, high product purity is required enormous energy consumption. This paper aim is to propose a modified process design that uses distillations, the decanter, a membrane and also applies heat integration to intensify efficiency usage. Besides, the column stacking strategy is considered in this process. According to Patraşcu et al. reference, this work not only makes energy consumption decrease by 57% and TAC decreases by 52%, but also can obtain high purity all butanol, acetone and ethanol 99.5 wt%. Besides, this study carries on dynamic simulations for the processes with/without heat integration and with column stacking. Throughput change and feed composition are changed by ±10%. The results that all products can return to the desired points. Temperature control is suitable for these two cases.