不同示蹤氣體對化學排煙櫃性能評估的影響

The study of Chemical hood performance with different tracer gas

張宥恩(Yu-En Chang)

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(2013年)

https://doi.org/10.6833/CJCU.2013.00072

摘要

排煙櫃的功能是將櫃外乾淨的空氣導入，並且把櫃內的污染物限制住，再經排煙櫃之排氣導管釋出。而測試排煙櫃的方法如:ASHRAE110、EN14175-3:2003中的示蹤氣體測試，測試用的示蹤氣體為SF6(六氟化硫)，但近年來溫室效應問題趨於嚴重，環保署針對6種溫室氣體做管制，慣用之SF6也列入管制，其全球暖化潛勢(GWP)高達二氧化碳的22,800倍，有鑑於此尋找替代的示蹤氣體刻不容緩。本研究的目的是1.使用不同比重的示蹤氣體，依照歐洲排煙櫃測試標準，評估化學排煙櫃內污染物洩漏情形。2.觀察不同示蹤氣體之行為模式，是否有可能取代六氟化硫。3.比較傳統排煙櫃與氣廉式排煙櫃洩漏的差異性。而替代氣體的選擇是針對六氟化硫其物理化學性質，其比重與六氟化硫相似，全球溫暖化潛勢(GWP)低於六氟化硫且低毒性、不可燃等特性做為考量。
依據上述原則挑選出環保冷媒R-134a做為替代氣體，比較替代氣體與六氟化硫之間的濃度差異性。實驗使用的方法為EN14175-3:2003中的面速度測試(Face Velocity Measurement)、示蹤氣體測試(Tracer Gas Measurement )中的靜態濃度測試，此方法是先測量排煙櫃面各點的風速，再以不同比例的混合氣體以2 l/min等速率釋放，並將網格狀的採樣探頭依不同位置放置在排煙櫃開口面上，觀察其濃度分布。而儀器的部分是使用攜帶式紅外光譜儀，抽氣後通過密閉腔(Close Cell)進行濃度分析。針對傳統式排煙櫃、氣簾式排煙櫃，依照前述的方法，分別以相同濃度之SF6及R134a作為示蹤氣體，各測試3次。測試所得結果顯示，R134a在測試傳統排煙櫃的效果更為顯著，在氣簾式氣櫃也有足夠能力顯示出洩漏位置。
而在環保及成本方面，檢測10萬台排煙櫃造成一年六氟化硫的碳排放相當於砍掉1.7億棵樹木，所需費用為一億三千萬;如使用R134a作為替代品約七千五百萬棵，費用為八百七十五萬元。從上述均結果顯示出環保冷媒R-134a適合替代六氟化硫做為測試氣體，其低毒性、不可燃等特性相當適合使用在測試排煙櫃上。

關鍵字

示蹤氣體 ； 環保冷媒 ； 化學排煙櫃 ； EN14175 ； 溫室效應

並列摘要

The effort of fume hood is that induce the clean air into the hood, hold the containment air in the hood and exhaust the containment air by the pipe. The test method ASHRAE110 and EN14175-3:2003 use the SF6 as the trace gas to test the performance of the fume hood, but the greenhouse effort is more and more serious in recent years, and the SF6 is one of the 6 gases of EPA’s plan to reduce emissions of greenhouse effect gas, its global warming potential is 22,800 times greater than that of CO2.The study aimed to follow the test method EN14175-3:2003 is using different specific gravity tracer gas to evaluate contaminant leakage for fume cupboard. Observed behavior patterns of different tracer gas, it’s possible replaced sulfur hexafluoride. Compared with different leakage pattern for conventional fume cupboard and Air-Curtain Fume upboard. The choice of alternative gas should have the same physical and chemical properties of sulfur hexafluoride, Global warming potential (GWP) is lower, low toxicity and non-flammable for safety consideration. According to principal of selections above, the environmentally friendly refrigerant R-134a is an ideal alternative gas, which will compare with the sulfur hexafluoride as a trace gas and follow the test method EN14175-3:2003. There are 3 major parts of this method, first, measured the velocity in each points of the fume cupboard, and then release a mixed gas of 2 l/min flow rate and the sampling probe grid shall be positioned a specific location in the sash opening of the fume cupboard, observed concentration distribution. A close-cell portable infrared spectrometer is used to analysis the concentration of trace gases. For the same fume hood, according to EN-14175 method, there are three times of each test with the same concentration of SF6 and R134a. The result showed that the R134a is more singnificance. For the environmental protection and cost, testing one hundred thousand fume cupboard is equal to cut one hundred seventy million tree for carbon emissions per sulfur hexafluoride. The cost is needed one hundred thirty million dollars; if using R134a as a substitute about seventy-five million tree, the cost is eight point seven five million dollars. The results showed that the R-134a is suitable to alternative sulfur hexafluoride as a trace gas, its low toxicity, non-flammable characteristic in quite suitable for the test method.

並列關鍵字

Tracer gas ； Environmentally friendly refrigerant ； fume cupboard ； EN14175 ； Greenhouse Effort

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