臺灣博碩士論文加值系統

矽甲烷(Silane)是半導體、光電、太陽能電池產業中最常用的特殊氣體，且具有自燃特性的高危害氣體，主要扮演多晶矽沉積或磊晶製程的矽來源材料。本研究由2005年11月台南科學園區內某高科技廠發生矽甲烷火災爆炸事故調查開始，確認矽甲烷是由瓶閥的固定座、上連桿、隔膜下連桿脫落後自瓶閥孔洩漏，此次矽甲烷外洩應先引發爆炸、而後才有燃燒，這顯示矽甲烷外洩有高度的爆炸潛在危害。
本研究於實場進行矽甲烷鋼瓶瓶閥外洩測試，從所有未立即引燃的外洩測試中發現，矽甲烷引燃的發生與流速或壓力降低有關，高壓下外洩的延遲引燃，可造成威力強大的侷限空間爆炸，這是自燃性矽甲烷所能產生的最危險狀況。在動態排放測試中，推論主導立即引燃的控制因素為足夠低的排放流速，不是排放壓力。在穩態排放測試，藉由電子四向閥的開關切換，使純矽甲烷以穩態的流速排至靜止的大氣中，並以雷射陰影與高速攝影記錄，測試的結果顯示矽甲烷有獨特的外洩行為，特別是引燃的行為與矽甲烷外洩流速、出口幾何、以及出口環境條件等密切相關。
綜合上述的測試結果，可發現當矽甲烷的流速低於某一臨界流速時，矽甲烷會立即引燃，高於此臨界流速則不會引燃，臨界流速隨排放管徑的增加而增加，且在臨界流速以下，矽甲烷引燃的距離與流速成正比，依據層流噴射的空氣挾帶理論可求得當矽甲烷濃度降至約75.6%時，具有最強的反應性，也是自燃的反應核心，故矽甲烷的自燃行為和一般燃料如氫、正庚烷相近，可推論矽甲烷在高速下外洩不會自燃是導因於高速流動所造成自燃反應核心的冷卻(quench)效應。此結果將能有助於發展更安全的矽甲烷操作系統，進一步預防矽甲烷爆炸的事故。

Silane is a specialty gas commonly used in semiconductor, flat panel display, and photovoltaic industries. It is a well known pyrophoric gas which normally ignites upon contact with air. This work initiated from an investigation of a silane explosion and fire incident occurred in November 2005 in a photovoltaic plant inside the Southern Taiwan Science Park. It is found that the explosion was caused by release from a silane cylinder valve with detached retainer. The retainer was loosened by unknown causes. The operator continued to turn the hand wheel which also linked to the loosened retainer causing the detachment of the retainer. It is not clear why the operator did not notice the leak, unless the leak did not ignite. This issue raised the interest in the release tests from cylinder valve.
First of all, field tests of release from cylinder valve were then performed. It was found that release from full-opened cylinder with 0.025 cm restricted flow orifice (RFO) and loosened DISS valve seal cap resulted in prompt ignition of silane. However, release from loosened retained thread did not resulted in prompt ignition but ignited with a pop at flow shutoff. In all tests without prompt ignition, ignition always occurred at flow or pressure decay. The delayed ignition may cause confined space vapor explosion as demonstrated in the cabinet explosion test which is the most devastating explosion from silane releases. In the dynamic release tests, the silane is released from a vessel with known pressure. It is found that the controlling factor governing the ignition behavior is flow velocity not the release pressure. Thus, a series of steady flow tests were performed with an electrically controlled four-way switching valve such that steady silane flow without acceleration to the vent tube can be established. All the results show that the peculiar silane ignition behavior is strongly related to flow velocity, vent size, ambient condition, and vent geometry.
If it found that above a critical exit velocity, silane can be released indefinitely into air without any ignition. The critical exit velocity increases with increasing vent diameter. With the aid of laminar boundary layer theory, mixture fraction at the ignition location is calculated for all prompt ignition cases. It is found that the ignition always occurs in a well-defined mixture fraction at around silane concentration of 75.6% which is called the most reactive mixture fraction. It is concluded that the autoignition behavior of silane is similar to other fuel such as hydrogen and n-heptane, namely the silane release without prompt ignition is most likely caused by quench of the reactive kernel from the large velocity difference between the release gas and the ambient air. The implications from these results are discussed with emphasis on the safety of silane supply systems and operation practices.

一、前言 1
1.1矽甲烷的危害特性 1
1.2矽甲烷的事故 2
1.3矽甲烷外洩危害文獻回顧 2
1.4論文架構 11
二、矽甲烷事故回顧與分析 13
2.1矽甲烷外洩爆炸事故歷程 13
2.2矽甲烷外洩爆炸後事故調查 24
2.2.1 火災現場勘查 24
2.2.2 氣體房現場勘查 26
2.3鋼瓶瓶閥的檢查 29
2.4瓶閥固定座的失誤原因分析 32
2.5結論 33
三、矽甲烷實場外洩測試 34　
3.1背景 34
3.2矽甲烷外洩實場測試的裝置與條件 34
3.3矽甲烷外洩實場測試結果 36
3.3.1 DISS 632瓶閥出口的外洩測試 36
3.3.2 DISS 632瓶閥出口裝上密封蓋的外洩測試 40
3.3.3鋼瓶瓶閥固定座鬆脫的外洩測試 41
3.4高壓外洩至單支鋼瓶的氣瓶櫃 44
3.5結論與建議 48
四、矽甲烷外洩引燃行為研究 51
4.1動態排放測試 51
4.2動態排放測試裝置 51
4.2.1動態排放測試裝置 51
4.2.2動態排放測試結果 52
4.3穩態排放測試 57
4.3.1穩態排放測試裝置 57
4.3.2穩態排放測試結果與討論 61
4.3.3最強反應的引燃核心分析 65
4.3.4延遲引燃的條件及機制 67
五、結論與建議 70
5.1結論與矽甲烷安全操作建議 70
5.2未來研究建議 71

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