| 摘要: | 人造全氟化合物(perfluorocompounds, PFCs)是重要溫室效應氣體，被半導體與光電產業大量使用，這類產業通常以初級洗滌器(local scrubber)對PFCs進行移除以降低排放；然而，過去業界評估移除效率的方法是使用傅氏紅外光譜儀(Fourier Transform Infrared Spectrometry, FT-IR)搭配四極柱質譜(Quadrupole Mass Spectrometry, QMS)，但該技術存在著儀器造價昂貴及高技術門檻等缺點。有鑑於此，本研究因而嘗試開發一套以氣相層析儀作為核心的PFC量測技術，利用填充管柱與切換技術對PFC物質進行線上或採樣分析，改良後之系統用來量測半導體廠洗滌器移除效率上，採樣袋量測結果顯示燃燒式洗滌器DAS對C3F8移除效率高達90%以上，而電熱式洗滌器CDO及KT的移除效率分別約45%及15%。最後以氦氣作為追踪劑成功量測DAS機型的稀釋因子，修正後的移除效率仍然達90%以上。 本論文第二個主題是背景一氧化碳的量測與校正。利用高靈敏高線性表現之真空紫外共振螢光儀(Vacuum-UV Resonance Fluorescence, VUV-RF)，以四種不同濃度之一級標準品(介於64.9 ppbv 至 300 ppbv)校正五種濃度工作標準品 (介於 20 ppbv 至 250 ppbv)；校正後二級標準品運用在安置於鹿林山背景站用於校正測站內之還原氣體分析儀(Reduced Gas Analyzer, RGA)與非分散式紅外光譜儀(Non-Dispersive IR, NDIR)。再以VUV-RF與背景測站之NDIR及RGA進行為期48天之平行比對，比對結果VUV-RF與RGA及NDIR之相關性可達到0.968及0.966，NDIR與RGA之相關性為0.983。 Man-made perflurorcompounds (PFCs) are very potent green house gases, which have been used in large quantity by semiconductor and LCD industries in Taiwan. Usually these chemicals are to be removed by local scrubbers to prevent them from direct emission into the atmosphere. Conventionally, the assessment methods for various types of local scrubbers rely heavily on Fourier Transform Infrared Spectrometry (FT-IR) coupled with Quadruple Mass Spectrometry (QMS). Major drawbacks of these techniques stem from their high cost and high leaning barrier for the industry. In light of these obstacles, this research attempted to develop an assessment technique based on Gas Chromatography (GC), employing packed column, thermal conductivity detection, and heart-cut techniques. The developed system was deployed in a semiconductor fabrication plant to assess the destruction and removal efficiency (DRE) of 3 types of local scrubbers. Both in-situ on-site and flask sampling were adopted in the DRE assessment. It was found that the combustion type of local scrubber (DAS brand) exhibited over 90% DRE for C3F8, whereas the electric-thermal type had lower DRE of 45% and 15% for the CDO and KT brand, respectively. This research also developed a novel method to determine dilution factor by using helium as a tracer. The re-assessed DRE for DAS after adoption of He based dilution factor was still over 90%, consistent with the earlier value derived by flow rate calculation. The second topic of this research addresses the calibration and inter-comparison of carbon monoxide (CO) for background measurements. Five working standards in the range between 20 and 250 ppbv were accurately calibrated by 4 NOAA primary standards via a highly linear and sensitive instrument, i.e., vacuum-UV resonance fluorescence (VUV-RF). The 5 calibrated working standards were brought to the Lulin Atmospheric Baseline Station (LABS) for calibrating two CO instruments of reduced gas analyzer (RGA) and non-dispersive infrared (NDIR). Intercomparison between VUV-RF, RGA, and NDIR were carried out continuously for a period of 7 weeks. The correlation correlations (R2) for VUV-RF with RGA and NDIR are 0.968 and 0.966, respectively, whereas the R2 between NDIR and RGA is 0.983. |
