水氣轉移於超重力場中與甲醇自熱重組反應產氫之特性

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題名:
水氣轉移於超重力場中與甲醇自熱重組反應產氫之特性
著者: 徐毓智; Syu, Yu-jhih
陳維新; Wei-hsin Chen; 綠色能源科技研究所碩士班
主題: 水氣轉移反應(WGSR); 旋轉填充床(RPB); 超重力(Higee); MDC-7; G值; 甲醇自熱重組反應; 產氫; MDC-3; Methanol autothermal reforming; G number; Hydrogen production; Water gas shift reaction (WGSR); Rotating packed bed (RPB); High gravity (Higee); MDC-7; MDC-3
描述: 本文主要分成兩個部分：一部分為探討超重力場中水氣轉移反應(WGSR)之產氫特性；另一部分為探討甲醇自熱重組反應的能耗與產氫之暫態特性。首先探討超重力場中水氣轉移反應產氫之特性。為了在超重力場中進行水氣轉移反應，本研究設計了一個可升溫的超重力旋轉填充床(RPB)，其內部填充床可嵌入銅-鋅為基底的低溫催化劑(Sud Chemie, MDC-7)，填充床轉速操作於0至1800 rpm，水氣轉移反應之反應溫度與Steam/CO ratio分別為250°C至350°C與2至8。研究中特別強調固定反應氣體於觸媒床之滯留時間條件下，轉速、反應溫度與Steam/CO ratio之參數改變對於CO轉化率及產氫的影響。本研究首先推導了一個無因次化參數“G值”，可用於計算離心力對於提高水氣轉移反應效率之效果，當轉速操作於1800rpm時，離心力平均作用於旋轉填充床中的反應物可高達234g(即234倍地球重力場)，實驗結果發現，與不旋轉條件相較，水氣轉移反應之CO轉化率最高可提升70%，很清楚明顯的表示離心力將有助於氫氣的生成，這乃因離心力對於在觸媒床間的反應物具有強化質傳效果與改變流動路徑所致，由勒沙特略原理可知，越高的反應溫度或越低的Steam/CO ratio將不利於CO轉化率，然而該條件於高重力場中將可得到大幅的改善。因此本研究建立了一個增強CO轉化率與G值間的關係式，整體而言，越高的反應溫度及越低的Steam/CO ratio，會有越高的G值函數指數。第二部分探討甲醇自熱重組反應對於產氫及能耗之暫態影響，本研究利用直立式管狀高溫爐加熱在反應管內部的蒸氣重組觸媒(Sud Chemie, MDC-3)，配合監測系統進行甲醇自熱重組反應並記錄其能耗。甲醇自熱重組反應之O2/C比為0至0.5，S/C比為1至2，反應溫度則為250°C與300°C，在固定滯留時間0.05秒條件下研究O2/C比、S/C比與溫度對於甲醇自熱重組反應之能耗與產氫暫態分佈情形。結果發現提升O2/C比確實可以減少能耗，以O2/C=0.5為最低，由於氧氣量增加有助於甲醇燃燒反應與部分氧化反應放熱，使得系統不需要頻繁的加熱，而功率輸出的頻率也因此下降，故較為省能。氫氣產量則隨O2/C比提高而遞減，S/C比對於功率及能耗的影響則較微弱，本研究中的甲醇轉化率皆可高達97%以上，且每莫耳甲醇產氫量在300°C下會趨近於理論值，氫氣產率達95%以上。
In this study, two topics of hydrogen production are explored. The first part focuses on the water gas shift reaction (WGSR) in an environment with high gravity; the second part is on the thermal characteristics of methanol autothermal reforming.In the first part, to perform the WGSR with high centrifugal force, a rotating packed bed (RPB), embedded by a Cu-Zn-based catalyst, with elevated temperatures is conducted where the rotor speed is in the range of 0-1800 rpm. Meanwhile, the reaction temperature and the steam/CO ratio range from 250 to 350°C and 2 to 8, respectively. A dimensionless parameter, the G number, is derived to account for the effect of centrifugal force on the enhancement of the WGSR. With the rotor speed of 1800 rpm, the induced centrifugal force in the RPB acting on the reactants is as high as 234g on average. As a result, the CO conversion from the WGSR is promoted up to 70% compared with that without rotation. This clearly reveals that the centrifugal force is conducive to hydrogen production, resulting from intensifying mass transfer and elongating residence time of the reactants in the catalyst bed. From Le Chatelier''s principle, a higher reaction temperature or a lower steam/CO ratio disfavors CO conversion; however, under such a situation the enhancement of the centrifugal force on hydrogen production from the WGSR tends to become more significant. Accordingly, a correlation between the enhancement of CO conversion and the G number is established. As a whole, the higher the reaction temperature and the lower the steam/CO ratio, the higher the exponent of the G number function.In the second part, a vertical heating oven is constructed to carry out the autothermal reforming of methanol where a reaction tube is embedded. A commercial catalyst (Sud Chemie, MDC-3) is used to trigger the reaction and energy consumption of the reaction system is recorded automatically. The important parameters of O2/C ratio, S/C ratio and reaction temperature are in the ranges of 0-0.5, 1-2 and 250-300°C, and the residence time of the reactants in the catalyst bed is fixed at 0.05s. The experiments clearly indicate that increasing O2/C ratio decreases the frequency of heat supply, implying that a higher O2/C ratio is able to decrease energy consumption. On the other hand, hydrogen yield decreases with increasing O2/C ratio, whereas varying S/C ratio merely has a slight effect on energy consumption. As a whole, the methanol conversion is always higher than 97% and the theoretical hydrogen yield is beyond 95% in this study.
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建立日期: 2010
格式: 121 bytes
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語言: 中文
識別號: http://nutnr.lib.nutn.edu.tw/handle/987654321/2244
資源來源: NUTN IR

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水氣轉移於超重力場中與甲醇自熱重組反應產氫之特性

徐毓智; Syu, Yu-jhih 陳維新; Wei-hsin Chen; 綠色能源科技研究所碩士班 2010

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