以低溫室效應氣體作為示蹤氣體之研究

A Study of Using Low Greenhouse Effect Gases as Tracer Gases

陳意雯(Yi-Wen Chen)

指導教授 ： 張振平

長榮大學/健康科學學院/職業安全與衛生學系(所)/碩士(2015年)

https://doi.org/10.6833/CJCU.2015.00087

摘要

無論是測試整體換氣或者局部排氣性能的標準方法，最常選用六氟化硫為示蹤氣體，雖然六氟化硫本身化學性質穩定、不具毒性、爆炸性及可燃性且環境中無背景值干擾的問題，相當符合示蹤氣體所具備的條件，看似完美的氣體，其全球暖化潛勢值卻是二氧化碳的22,800倍，反而帶給環境極大的隱憂，近幾年來地球暖化的現象日益嚴重，各界不得不從中找尋其他氣體來替代六氟化硫。
　 本研究由文獻提及以前研究有使用過氧化亞氮、四氟乙烷、七氟丙烷、醋酸、乙烯、二氧化碳等氣體，及參考政府間氣候變化專門委員會第四次評估報告的全球暖化潛勢值較低的物質和化學物質的毒性、容許濃度、爆炸界線等使用上安全性為準則，決定選用四氟乙烷、氧化亞氮、丙酮、異丙醇、丁烷，以上五種為本次研究的示蹤氣體。
　　分別使用五種不同的氣體做為示蹤氣體，利用傅立葉轉換紅外線光譜儀、六氟化硫氣體分析儀、可攜式有機溶劑連續偵測儀等儀器偵測其濃度，參考EN 14175-3:2003測試規範的示蹤氣體靜態測試分別進行測試。做為測試對象的化學排煙櫃，將設定每組氣體的釋放流量及排煙櫃高風量(16.55m3/min)、低風量(11m3/min)條件，每組風量測試條件在櫃面所指定的六個測定位置重複三次。
完成高低風量共三十六次的實驗，最後比對每種氣體與六氟化硫的相關係數(R)、全球暖化潛勢值、材料和儀器成本及儀器使用上的便利性。綜合比較後，最佳的結果是丙酮與六氟化硫濃度進行迴歸後比較的R大於0.8佔三十六次實驗中的58%、丙酮的全球暖化潛勢只有0.25，可減少地表對紅外光的吸收，能有效減緩溫室效應對環境的影響、價格便宜且取得容易，所使用的可攜式有機溶劑連續偵測儀的價格相對便宜，且操作方法簡易及攜帶方便，且在排煙櫃下層的氣體行為與SF6呈現一致性，本研究結果顯示丙酮最適合被選為取代六氟化硫的示蹤氣體。

關鍵字

示蹤氣體 ； 低溫室效應 ； 局部排氣 ； 六氟化硫 ； EN 14175

並列摘要

Sulfur hexafluoride (SF6) is often used as the tracer gas to determine the performance of general ventilation or local exhaust ventilation, although SF6 is stable, non-toxic, incombustibly and non-existing substance in nature. It looks perfect to meet the requirement of being a tracer gas, but it has high global warming potential (GWP) 22,800 and great potential hazard to the environment. The global warming situation became more serious in recent years. We have to find other gases to replace SF6 as the tracer gas.
Recent researches discussed the possible chemicals to replace SF6 as the tracer gases, which included nitrous oxide, tetrafluoroethane, FM-200, acetic acid, ethylene, carbon dioxide etc. Based on the recent researches, and under the consideration of the lower GWP of Intergovernmental Panel on Climate Change (IPCC), lower permission exposure limit (PEL), and lower explosive limit (LEL), we decided to choose tetrafluoroethane, nitrous oxide, acetone, isopropyl alcohol, butane for this study.
In this study, we used the chemical fume hood as the testing target, which was set to 2 different flowrates, then followed the static sash test method of EN 14175-3:2003 and used different instruments to measure the concentrations of the challenge gases in triplicate.
Finally, the comparison of each gas and SF6 was made on R, GWP, cost, and convenience of instruments. The conclusion of all the experimental data, indicated that the best correlation with SF6 was acetone. The GWP of acetone is 0.25, it can reduce surface absorption of infrared light, and mitigate the effects of global warming on the environment. The cost of acetone is cheap. Photo ionization detector (PID) can be used to measure acetone and has the characteristics of easy operation and carry. Also, acetone had similar gas behaviors of SF6 at beneath layer of the hood. The results of this study indicated that acetone was the most suitable tracer gas as the replacement of SF6.

並列關鍵字

tracer gas ； low greenhouse effect ； local exhaust ； sulfur hexafluoride ； EN 14175

參考文獻

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