半導體廠房防爆區劃設計探討

Abstract

有鑑於國內現有12吋半導體廠房多屬應用有限的土地建置精密複雜的設備，製程中廣泛使用可燃性、易燃性液體(例如：IPA、光阻液..)與特殊性氣體(例如：SiH4、H2..)，因此單位面積的火負載量與投資成本來的比較高。本論文主要探討防爆區劃範圍內依據國內外法令及標準進行各項安全設計並輔以電腦災後後果模擬分析軟體ALOHA (Areal Locations of Hazardous Atmospheres)嘗試進行火災爆炸影響範圍模擬。在不同季節產生不同的風速影響下進行ALOHA後果模擬分析發現，當風速愈大愈能增加空氣稀釋之速度，因此毒性氣體危害及爆炸危害會隨風速增加而降低，但熱輻射卻會隨風速提升而增加。模擬使用異丙醇(IPA) 12000L儲槽若不幸發生洩漏其可燃性蒸氣濃度尚無法達到爆炸範圍，若為池火燃燒則熱輻射的影響在10公尺範圍內不會有立即致死的危險。若發生沸騰液體蒸氣膨脹爆炸(Boiling Liquid Expansion Vapor Explosion，BLEVE)，將造成全廠區及鄰近廠房產生破壞性影響，影響範圍達101-107公尺。操作12 kg的矽甲烷(Silane)鋼瓶，發生瞬間完全洩漏或自氣體管線持續洩漏時，距離洩漏地點13-15公尺範圍內，會產生0.7 psi的過壓爆炸影響。因此在管制距離85-90公尺範圍內，必需嚴禁各種動火作業及有效選用防爆電氣設備。

In view of the fact that all of the current 12-inch semiconductor plants have exploited limited land space for the installing of precise and sophisticated equipments, and they have made extensively use of combustible and inflammable liquids (such as IPA, photo-resistant liquid, and others) and special gases (such as SiH4, H2, and so on). Therefore, the fire loading and investment cost per unit area is relatively high. This thesis mainly investigates various kinds of safety designs based on domestic legal provisions and standards within the scope of explosion-proof division, with the assistance of the software ALOHA (areal locations of hazardous atmospheres) for consequence simulation analysis for the influencing region due to fire explosion. During different seasons, it was found from the ALOHA consequence simulation analysis with different wind speeds that when the wind speed was greater, it could further help increase the speed for air dilution, and so hazard of toxic gas and explosion hazard was lowered. However, heat radiation was enhanced with increasing wind speed. The simulation assumed the scenario that 12000L storage tank for isopropyl alcohol (IPA) unfortunately leaked, the concentration of its inflammable vapor did not reach the explosion level. Nonetheless, if the tank fire continued to burn, the influence of heat radiation within 10m region won’t result in the hazard of immediate death. However, if boiling liquid expansion vapor explosion (BLEVE) occurred, it would create devastative influence on the entire plant and neighboring manufacturing plants, with its scope region reaching 101-107 m. For the operation of a 12kg steel-bottle of silane, if instantaneous and complete leakage occurred or continuous gas leakage was found from its pipeline, 0.7 psi of impact with overpressure explosion would occur within a region of 13-15 m to leakage source. Therefore, all kinds of fire operation must be prohibited and explore-proof electrical equipment must be effectively used within the control range of 85-90 m.