| 摘要: | 台灣因地理、交通及產業特性，化學品常須利用機動性高的槽車運輸，以灌裝方式補充製程所需化學品及清運。近年來國內槽車事故頻傳，事故型態主要為洩漏、火災、爆炸及形成氣雲等，在緊急應變及疏散管制的資訊建立與取得多直接採用緊急應變指南 (Emergency Response Guidebook, ERG) 之應變資訊。但在大當量、高活性或高毒性等情況下，實際危害範圍常會超出ERG所採用的固定經驗數值，可能誤判疏散距離而導致產生潛在危險。緊急應變無線資訊系統﹙Wireless Information System for Emergency Responders, WISER﹚是ERG的電子版。為方便使用，本研究選用WISER及ALOHA (Areal Locations of Hazardous Atmospheres)，以2017年6月25日台氯氯乙烯槽車 (約30公噸)事故為案例，探討兩者提供防護範圍的合宜性，以作為緊急應變規劃之參考。
WISER數據庫所提供氯乙烯化學品在洩漏後其無火隔離疏散範圍為800m，在有火狀況下(含爆炸)的隔離疏散範圍為1600m。另外經ALOHA模擬結果發現，氯乙烯ERPG-2 (5000ppm)為569m，小於WISER的800m範圍，但人體可感不適的濃度ERPG-1(500ppm)之影響範圍已達1600m，超出WISER的800m範圍。在夜間情境中，氯乙烯ERPG-2 (5000ppm) 之影響範圍為1100m，已超出WISER的800m範圍，為防止人員中毒，建議人員至少應疏散至1100m範圍之外。另外，10%LEL影響範圍為656m，小於WISER的800m範圍；但在夜間情境，10%LEL影響範圍為1300m，大於WISER的800m範圍。爆炸與爆轟的0.5psi過壓影響範圍分別為562m與1100m，熱輻射及BLEVE熱輻射的4.0 kW/m2影響範圍分別為65m及389m；在夜間情境，爆炸與爆轟的0.5psi過壓影響範圍分別為773m與1500m，熱輻射及BLEVE熱輻射的4.0 kW/m2影響範圍分別為68m及397m，皆小於WISER的1600m範圍。因此，對於燃燒性和爆炸性建議考慮Wiser 1600m的安全距離。經ALOHA模擬結果發現，經緯度、日期及時間僅影響大氣穩定度的選擇，對模擬結果的危害範圍並無明顯之影響。
Because of the geographical environment, transportation, and industrial characteristics in Taiwan, chemicals which are added to the process as reactants and cleared as wastes after the process are often transported by highly mobile tankers. In recent years, the main types of accidents of domestic tankers are leaks, fire, explosions and the formation of gas clouds. Establishment and acquisition of information on emergency response and evacuation control often uses the Emergency Response Guidebook (ERG) directly. However, in the case of massive equivalents, high activity or high toxicity, the actual hazard range often exceeds the fixed empirical value used by the ERG. This may erroneously determine the distance of evacuation, thus causing a potentially dangerous occurrence. Wireless Information System for Emergency Responders (WISER) is the e-edition of ERG. For ease of use, WISER and Areal Locations of Hazardous Atmospheres (ALOHA) were selected in this study to explore their suitability to provide the ranges of protection, which when used as a reference for emergency response planning, with the Vinyl Chloride tanker accident (about 30 metric tons) of Taiwan VCM Corporation on 25 June 2017.
The evacuation ranges that WISER database provided for vinyl chloride chemical leaks and for its chemical fire/explosion are 800 m and 1600 m, respectively. The results simulated by ALOHA have shown that: ERPG-2 (5000 ppm) of toxic threat zone caused by VCM is 568 m, which is less than the 800 m provided by WISER. But ERPG-1 (500ppm) of toxic threat zone, the concentration which the human body can feel the discomfort, has reached 1600, which surpasses the 800m provided by WISER. In the nighttime situation, ERPG-2 (5000 ppm) of toxic threat zone caused by VCM is 1100 m, which surpasses the 800 m provided by WISER. To prevent poisoning, it is advisable to evacuate at least 1100 m. The threat zone at a flammable concentration of 10% LEL is 655m, which is less than the 800 m provided by WISER. In the nighttime situation, the threat zone at a flammable concentration of 10% LEL is 1300 m, which surpasses the 800 m provided by WISER. The overpressure threat zone ignited by spark/flame and by detonation of 0.5 psi, respectively are 562 m and 1100m,and thermal radiation threat zone (4.0 kw/m2) or thermal radiation threat zone (4.0 kw/m2) of BLEVE respectively are 65 m and 389 m respectively. The above mentioned are less than the 1600m provided by WISER. In the nighttime situation, the overpressure threat zone ignited by spark/flame or by detonation of 0.5 psi, respectively are 773 m and 1500 m, and the thermal radiation threat zone (4.0 kw/m2) and thermal radiation threat zone (4.0 kw/m2) of BLEVE respectively are 68 m and 397 m respectively. The above are less than the 1600m provided by WISER. In summary, adoption of the safety distance provided by WISER is suggested for the evacuation range of vinyl chloride chemical fire or explosion. The results simulated by ALOHA have shown that: Latitude, longitude, date and time only affect the choice of atmospheric stability, and there is no significant impact on the hazard range of the simulation results. |
