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• Main Authors: Tien-Li Lin, 林天立
• Other Authors: Jia-Lin Wang
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/qrdu5z

碩士 === 國立中央大學 === 化學學系 === 107 === A new method to analyze ambient total non-methane hydrocarbons (tNMHC) were developed. Modified from the continuous flow catalyst method commonly used today, a unique method of flow injection was successfully designed aiming at achieving a lower detection limit than the continuous flow type when monitoring ambient air. The experiment is divided into three parts. The first part is to develop methods for tNMHC measurement at the perimeter of industrial zones, which can be divided into two types of chromatography based versus catalytic based. The first type mainly uses chromatographic columns to separated methane from NMHC in isothermal condition, and the total hydrocarbon (THC) and methane signals are individually obtained by splitting the sample flow into two, with one going to an empty column and the other going to a chromatographic column. The value of tNMHC is obtained by the THC value subtracting the methane value. The second type uses catalyst to oxidize NMHC without oxidizing methane. The sample flow alternatively going through the catalyst vs. not going through the catalyst yields the signals of methane vs. THC. Subsequently, the tNMHC value is obtained by subtracting the methane value from that of THC. While the second type is more of a conventional design where the sample flow is continuous, a modified method was derived based on the concept of flow injection. A sample loop and a switching value were used to inject sample in a fill-and-flush manner. This so-called flow injection mode would produce signals that mimic chromatographic peaks, which in theory not only can decrease the detection limit, but also greatly prolong the life spend of the catalyst. The second part is the development of an aluminum block injector to replace the commercial 10-port switching valve. Precision machining technology was adopted to make multiple flow paths inside the aluminum block, and 8 solenoid valves were used to control the flow directions of the sample to achieve the same effect as the switching valve. In comparison, the aluminum block injector has a small volume and the production cost is relatively low. Relative standard deviation (RSD) is better than 5%. This self-developed manifold is expected to be applicable in many areas of trace gas analysis. The third part of this thesis is to use the self-built THC analyzer to trigger canister samples to capture pollution plumes for detailed chemical composition. For testing, the analyzer was deployed at the perimeter of a refinery plant. The continuous monitoring last one month with minute resolution with preset trigger levels to capture pollution event samples. This field test resulted in capturing 13 event samples, which were analyzed by in-lab GC/MS/FID for 108 compounds.