毫米尺寸流體系統應用於生質柴油之分離與純化

Separation and Purification of Biodiesel by a Millifluidic System

陳奕綸(I-Lun Chen)

指導教授 ： 楊鏡堂

國立臺灣大學/工學院/機械工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602196

摘要

本研究應用微流體系統之高表面積體積比特性，進行生質柴油之分離與純化，並與前段之轉酯化反應整合於同一晶片中，成為一完整的高通量生質柴油產製晶片。轉酯化反應生成之生質柴油通常含有過量甲醇，無法直接進行使用，需進行額外之分離與純化反應改善生質柴油品質。本研究設計水洗流道晶片及分離流道晶片以減少生質柴油中的甲醇含量，並利用重力靜置 (gravity settling) 之方式，使晶片出口處為高純度之生質柴油，即可直接進行使用。
實驗分析首先以轉酯化反應產物之上層生質柴油與純水分別注入水洗晶片中以進行水洗。尚未經過水洗之生質柴油甲醇含量經核磁共振儀測得平均值約為6 %，通入長度為500 mm之單注水口流道晶片，且純水流率設定為0.6 ml/min時可達到0.153 %之甲醇含量，達生質柴油之國家使用標準。若於流道中加入鯡魚骨狀結構，於純水流率0.6 ml/min時，甚至可達到0.091 %之甲醇含量。
分離晶片之設計理念為液珠流譜因重力作用將於流道內逐漸轉變為層流流譜。將生質柴油與甘油以1:1之比例混合均勻後立即通入此晶片中，於晶片上層出口可收集到純生質柴油而不含甘油，下層出口則含少量生質柴油，可藉由調整晶片之上下層流道高度以達生質柴油層與甘油層之完全分離目標。
本研究後續設計之整合晶片中，皆因轉酯化反應之中間產物產生水解現象迫使逆反應發生，使得轉化率大幅下降，因此本研究測試兩種方式減少中間產物含量分別為延長反應時間及提高環境溫度。在反應溫度55度且靜置時間1小時，則轉化率可達93 %，幾乎與未進行純化作業前之轉化率相差無異，證實加熱與靜置在連續式生質柴油產製晶片中為連結轉酯化反應和分離與純化系統的關鍵要素。

關鍵字

毫米尺寸 ； 生質柴油 ； 分離與純化

並列摘要

In this research, we applied the characteristic of high surface area to volume ratio in microfluidics, conducting separation and purification procedures in biodiesel production, and attempt to integrate transesterification onto one chip to realize a high-throughput completed biodiesel production chip. Fatty acid methyl ester (FAME) is not available immediately after transesterification as a result of containing excessive methanol. Methanol can be washed out from FAME by water-washing process, which is needed to be carried out to reduce the methanol content. In this research, we designed washing chip to decrease methanol content in biodiesel and separation chip to collect high purity biodiesel from upper outlet by gravity settling.
Methanol content was reduced from 6% before washing to less than 0.2% after washing by injecting biodiesel and water into 500 mm washing chip at 0.6 ml/min water flow rate, meeting FAME standard. Washing chips with staggered-herringbone structure can obtain even better results. We use passive structure of flow channels to separate the biodiesel and its by-product. Due to the effect of gravity, flow pattern in the channel changed from slug flow to somewhat like laminar flow gradually. Therefore, fluids from upper outlet of the chip are pure FAME, confirmed by no glycerol peaks in the NMR chart of upper-outlet fluids.
Hydrolysis of intermediates in transesterification caused reverse reaction during washing procedures, decaying conversion largely. In this research, we tried two different methods to reduce intermediates: longer residence time and higher environment temperature. Decent conversion of 93 % can be attainable at 55 ℃ and 1 h residence time. We proved heating and settlements are essential factor to connect transesterification with separation and purification in continuous biodiesel production.

並列關鍵字

millifluidic ； biodiesel ； separation and purification

參考文獻

陳國祥，2014，液珠式微流體晶片之生質柴油產製，國立臺灣大學機械工程學系碩士論文。

Amini, H., Lee, W., and Carlo, D. D., "Inertial microfluidic physics," Lab on a Chip, 2014, Vol. 14, pp. 2739-2761.

Atadashi, I. M., Aroua, M. K., and Aziz, A. A., "Biodiesel separation and purification: A review," Renewable Energy, 2011, Vol. 36, pp. 437-443.

Baroud, C. N., Gallaire, F., and Dangla, R., "Dynamics of microfluidic droplets," Lab on a Chip, 2010, Vol. 10, pp. 2032-2045.

Bhagat, A. A., Kuntaegowdanahalli, S. S., and Papautsky, I., "Continuous particle separation in spiral microchannels using dean flows and differential migration," Lab on a Chip, 2008, Vol. 8, pp. 1906-1914.