電石乙炔製程在國內外氣體業界曾發生多起火災爆炸事故，造成人員傷亡及設備不同程度之損傷。國內電石乙炔廠計有八家，為避免重蹈覆轍，本研究利用危害與可操作分析（HAZOP）及失誤樹分析（FTA）風險分析技術，以國內某乙炔廠之電石乙炔製程為分析對象，系統化地找出潛在危害因子，並分析出其可能發生的原因與機率，提升電石乙炔廠設備運轉及人員操作上之安全性，並供緊急應變時救災參考。鑑於台灣電石乙炔廠事故統計數據不足，且製程設備與日本相近，因此本研究事故統計數據主要引用日本關東乙炔工業株式會社發行之「溶解乙炔之安全」，針對1946年至2002年間日本溶解乙炔製造工廠發生之事故之統計數據。失誤樹分析（FTA）採用國內核能所開發之故障樹分析套裝軟體INERFT。
結果發現，HAZOP分析後未發現有危害等級屬1或2的潛在危害，顯示製程相關安全措施於設計之初均已詳加考慮，危害控制建議改善計有九項。FTA結果顯示：1.重要之失效組合為氮氣噴熄火花故障與投入電石撞及金屬（5.240E-005）；2.人員未依安全作業標準程序定時測定純度與洗淨器W故障無法淨化（2.120E-005）。若於電石投入口鑲入橡膠襯片，且採耐撞擊之材質可將投入電石撞及金屬其發生頻率可由1.050E-001降為1.050E-002，計算改善後投入電石撞及與金屬與氮氣噴熄火花故障失誤組合，其發生失誤率頻率為5.240E-006。另外，若能提高洗淨器清洗頻率或減少洗淨器排水管阻塞即可將洗淨器W故障無法淨化之發生頻率由1.060E-002 降為1.060E-003，計算人員未依安全作業標準程序定時測定純度與洗淨器W故障無法淨化失誤組合，其發生失誤率頻率為2.120E-006。綜合上述改善結果，使之接近一般可接受之可靠度標準1.0E-006 (次/年)。
關鍵字： 乙炔，電石乙炔，危害與可操作分析（HAZOP），失誤樹分析（FTA） Acetylene is generated as a result of the chemical reaction between the calcium carbide and water. Acetylene plant is a plant in which acetylene is generated from calcium carbide and/or compressed into acetylene cylinders. Unfortunately, fire and explosion at acetylene gas processing factories are often reported.
There are eight such plants in Taiwan. To avoid following the same old disastrous road, we used Hazard and Operability Study ( HAZOP) and Fault tree analysis (FTA) to systematically identify hazards and assessed its risks, and to improve its safety of process and operator safety of an acetylene plant which acetylene is generated from calcium carbide. The assessed results will be used as a reference for their emergency and response training.
Since the data about the accidents in acetylene plant in Taiwan are insufficient for this FTA study, and the processing equipments of acetylene plant are similar to Japan, we used data which accidents happened from 1946 to 2002 of dissolved acetylene safety published by Acetylene Industry Co., Ltd. Kanto for this FTA study. A FTA program developed by Institute of Nuclear Energy Research Taiwan has been used to calculate the probability of accident.
Results show that no high hazard rating of 1 or 2 is found by HAZOP, indicating that related safety measures have been added while designing the process, total nine recommendations for correction have been suggested. FTA results show the failure combination of 5.240E-005 is the breakdown of the nitrogen spurt or calcium carbide hit the metal wall when it added in and of 2.120E-005 which people fail to follow the Standard Operation Procedure (SOP) to measure the purity of calcium carbide or the breakdown of scrubber. The fault frequency of 1.050E-001 can be reduced to 1.050E-002 when the rubber space on the added-in and/or use the anti-impact material is added and the failure combination will be reduced from 5.240E-005 to 5.240E-006. Also, the fault frequency of 1.060E-002 can be reduced to 1.060E-003 if the efficiency is improved or the blockage of the scrubber is decreased. Thus, the failure combination will be reduced from 2.120E-005 to 2.120E-006. Both corrections can approximately reach a standard liability of 1.0E-006 (times/year), which can reach an inherently safer state and possess acceptable risk in a traditional acetylene plant.
Key words: calcium carbide, Acetylene, Hazard and Operability Study ( HAZOP), Fault Tree Analysis ( FTA)
