以固體吸附法去除沼氣中之硫化氫

Application of solid adsorption for the removal of hydrogen sulfide in biogas

李聖慧(Sheng -Hui Lee)

指導教授 ： 林龍富

崑山科技大學/工程學院/環境工程研究所/碩士(2010年)

https://doi.org/10.6828/KSU.2010.00004

摘要

畜牧業經常被指為造成全球暖化的頭號禍首，因它能排放比二氧化碳還強的溫室氣體。養豬廢水經厭氧處理後所產生之沼氣含大量甲烷，頗值得加以回收再利用，但因含有高濃度硫化氫，必須加以純化才能做後續利用。
目前國內以水洗法及生物脫硫法去除沼氣中之硫化氫，因佔用面積及投資成本過高，使得養豬戶投資意願不高。本研究於養豬場現地，以可資源回收之吸附材質鐵環，控制在不同氣體流量下進行沼氣中硫化氫之去除。當進氣流量控制為 1.02、0.76 及0.52 bed volumes (BV) /min時，每公斤鐵環於尾氣達到貫穿濃度時(300 ppm)，分別可以處理40、78及100 BV之沼氣，相當於每公斤鐵環分別可以去除0.20、0.37及0.28公克之硫化氫，每平方公尺鐵環表面積分別可去除1.05、1.91及1.43公克之硫化氫。結果顯示由於質傳限制，隨著進氣流量增加，鐵環對硫化氫之吸附能力隨之降低。
在硫化氫進氣濃度為6,093 ppm，進氣流量為0.52 BV/min之條件下，鐵環吸附硫化氫於完全貫穿時，每公斤鐵環可處理2,898 BV沼氣，相當於每公斤可去除6.2公克硫化氫，每平方公尺鐵環表面積可去除32.1公克之硫化氫。
另以吸附材料氧化鐵去除沼氣中之硫化氫，結果顯示其吸附能力明顯高於鐵環，每公斤氧化鐵之沼氣處理量高達3,467 BV時，仍可將沼氣中之硫化氫完全去除，但因受限於沼氣中水氣影響，反應器底部之吸附材料黏結在一起阻礙沼氣通過，必須加以克服。

關鍵字

沼氣 ； 硫化氫 ； 鐵環 ； 氧化鐵

並列摘要

Livestock raising is usually recognized as of first importance for the global warming because of its greenhouse gas emission. In Taiwan, pig farming dominates the livestock raising. Biogas rich in methane was produced after anaerobic treatment of piggery wastewater. But it suffers from high level of hydrogen sulfide for the application of biogas.
In Taiwan, hydrogen sulfide is removed from biogas by wet scrubbing or biological treatment, but both of them suffer from large space taken and high capital cost. In this study, a recycled material, iron ring, was taken as adsorbent for the removal of hydrogen sulfide from biogas. Under different flow rates, adsorption capacities were determined until the concentration of hydrogen sulfide in off gas build up to 300 ppm which is the maximum level allowed in natural gas. When the flow rates were controlled at 1.02, 0.76 and 0.52 bed volumes (BV)/min, the adsorption capacities were 40, 78 and 100 BVs per kilogram of iron ring, respectively; equivalent to 0.20, 0.37 and 0.28 g hydrogen sulfide per kilogram of iron ring, respectively; and equivalent to 1.05, 1.91 and 1.43 g hydrogen sulfide per square meter surface area of iron ring, respectively. Above results showed that adsorption capacity decreases with the increasing of flow rate because of mass transfer limitation.
In addition, adsorption capacity was determined when the iron rings were completely exhausted by hydrogen sulfide under the flow rate of 0.52 BV/min and an influent hydrogen sulfide concentration of 6,093 ppm. It is 2,898 BVs and 6.2 g hydrogen sulfide per kilogram and 32.1 g hydrogen sulfide per square meter surface area of iron ring.
In addition to iron ring, a commercial adsorbent, iron oxide, for the removal of hydrogen sulfide was tested also. Hydrogen sulfide can be removed completely until 3,467 BVs of biogas go through the column for each kilogram of iron oxide. It shows that the adsorption capacity of commercial iron oxide is greatly higher than that of recycled iron ring. But the gas flow was hindered seriously because of the moisture content of biogas makes the iron oxide granules bind together, this problem needs to be solved for a better application of iron oxide.

並列關鍵字

biogas ； hydrogen sulfide ； iron ring, iron oxide

參考文獻

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