A Study of the Sources and Control of the Odor of a Semiconductor Factory
|關鍵字:||洗滌塔;無機酸鹼;異味;packed tower scrubber;acid;odor|
|摘要:||本研究探討某半導體有限公司周界異味來源。本研究利用多孔金屬固氣分離器進行該半導體廠區周界與洗滌塔進、出口端無機酸鹼氣體及微粒的採樣，並進行化學分析以探討周界的異味來源，並評估洗滌塔的處理效率及提出降低異味的可行性改善方法。研究結果顯示A廠房周界空氣中酸鹼氣體以HF及NH3為主，酸鹼微粒則以F-、NO3-及SO42-為主。A廠房周界中總 F-濃度有高於本國“固定污染源空氣污染物排放標準”中周界濃度標準的情形。此外，A廠房周界中酸鹼微粒濃度明顯高於B廠房。因此，推測異味為A廠房中洗滌塔所排放。所以本研究進一歩針對A廠房中酸排洗滌塔及周界進行持續性的監測，以了解洗滌塔進、出口端廢氣的酸鹼氣體及微粒組成與濃度，並與周界中酸鹼氣體及微粒濃度做比較，探討異味主要為何種物種所造成。A廠房酸排洗滌塔進口端酸性氣體以 HF、HCl及HNO3為主，洗滌塔出口端酸性氣體以HF為主，平均排放濃度為276.59 ppb。此外，由採樣分析結果可知，A廠房酸排洗滌塔出口端酸鹼微粒濃度明顯高於進口端的濃度，洗滌塔出口端酸鹼微粒主要為F-、Cl-、NO3-及SO42-，其中以NO3-的排放濃度最高，其平均排放濃度為1352.22 µg/Nm3。洗滌塔循環水的分析結果中也是以F-、Cl-、NO3-及SO42-為主，其中NO3-的濃度甚至有高達2665.29 ppm的情形出現。在洗滌塔出口端的採樣的過程中曾發現水氣在採樣管中有累積的情形，顯示有洗滌水液滴被氣流被帶出的情形。比較A廠房周界、酸排P002洗滌塔進、出口端廢氣及洗滌水中酸鹼物種組成與濃度，可推測A廠房周界異味主要為高濃度的酸性液滴經由酸排放口逸散到廠房周界所造成。|
The purpose of the study is to find out the source of the odor in ambient air around some semiconductor factory. Porous metal denuders were used to sample the acid and base gas and aerosol at the inlet and outlet of the acid gas packed tower scrubber to find the composition of waste gas and to assess the treatment efficiency of the scrubber. We used porous metal denuders to sample the ambient air around the factory and found the composition of the ambient air. It shows that HF, NH3, F-, NO3- and SO42- are the main acid and base gas and aerosol species in ambient air around A-building in the factory. The total concentration of F- is higher than standard concentration from the “Emission Standard of Fixed Air Pollutant Source.” Besides, the acid and base gas and particle concentrations in ambient air of A-building is higher than those of B-building. So we presumed that the source of the odor is from the stacks in A-building and proceeded continuous monitors in A-building to realize the composition and concentration in ambient air around A-building and at the inlet and outlet of the scrubber in A-building. We compared the composition of the ambient air and the waste gas at the inlet and outlet of the scrubber to find the source of the odor. The study shows that the main acid gas at the inlet of the scrubber is HF, HCl and HNO3 and the main acid gas at the outlet is HF whose average emission concentration is 276.59 ppb. Besides, it also shows that he main acid particle at the outlet of the scrubber is F-, Cl-, NO3- and SO42- whose concentration is often higher than that at the inlet of the scrubbers. The average emission concentration of NO3- is 1352.22 µg/Nm3. It was found that F-, Cl-, NO3- and SO42- are the main anion in the circulating water of the scrubbers and the concentraion of NO3- is even high to 2665.29 ppm. In sampling process at the outlet of the scrubber, we found that water vapor is accumulated in the sampling tube. According to those mentioned above, we can infer the source of the odor is acid liquid particle which was emitted with gas flow from the stack.