液态乙烯是气体乙烯经加压液化至温度为-104℃的液体，乙烯在液化、储存、运输的过程中可能发生泄漏，由于乙烯温度很低，与周围环境存在很大温差，液态乙烯泄漏到地面上之后会迅速蔓延、蒸发形成易燃易爆的蒸汽云，遇到点火源可能发生火灾、爆炸等事故，对周围环境造成严重的威胁。为了降低事故发生的概率，必须了解乙烯泄漏、蔓延、蒸发及蒸汽扩散的规律，以上研究对估计低温乙烯储罐泄漏产生的后果和采取事故预防措施具有很大意义。论文首先对低温乙烯储罐泄漏的形式进行了分析，利用ALOHA软件对对低温乙烯储罐泄漏源强进行了计算。利用FDS软件对大型储罐区内乙烯储罐泄漏扩散的过程进行数值模拟，研究分析了乙烯储罐区的围堰对乙烯蒸汽扩散过程的影响。研究结果表明，无围堰时乙烯蒸汽扩散范围较大，高浓度区域主要集中在乙烯罐区西侧的乙醇灌区附近，且相邻灌区罐壁的乙烯蒸汽浓度值较高。有围堰时乙烯蒸汽高浓度区域主要集中在乙烯灌区的围堰内，由于围堰的阻挡作用，乙烯蒸汽扩散影响区域较小，浓度峰值相比无围堰时较低。乙烯泄漏初期泄漏速率较小，少量乙烯蒸汽会越过围堰到达附近储罐区导致相邻储罐区罐壁的乙烯蒸汽浓度增大。随着泄漏后期泄漏速率增大至峰值，泄漏出来的乙烯会喷射至围堰内壁，乙烯蒸汽沿围堰内壁扩散，大部分乙烯蒸汽蓄积在围堰内部。论文其次利用ALOHA软件模拟分析了低温乙烯瞬时泄漏后危险性的后果，并利用ALOHA模拟分析了低温乙烯到不同地面类型时，不同地面类型对乙烯蒸汽扩散的影响。结果表明，在相同的气象条件和泄漏参数下，等量的低温乙烯泄漏到干的沙层、湿的沙层、混凝土地面危险性依次增大。论文最后利用ALOHA对软件对乙烯泄漏扩散中毒、闪火、蒸汽云爆炸以及形成的池火灾危险区域进行划分，得出低温乙烯泄漏后发生中毒、蒸汽云爆炸危险后果较大，并为采取事故应急救援措施提供指导意见。
Liquefied ethylene is a kind of liquid that ethylene was pressurized to temperature -104.2 ℃, In the process of liquefaction, storage and transportation, Liquefied ethylene may occur leakage. The temperature between Liquefied ethylene with the surrounding environment has a big difference, When Liquefied ethylene leaked on the ground, Liquefied ethylene pool spread, evaporated, which would produce flammable and combustible cloud. If the cloud was ignited, it may occur fire and explosion, posing a serious threat to the environment. In order to reduce the probability of accidents, research on Liquefied ethylene leakage, spreading, evaporation rate and vapor diffusion has a big significance to estimate the consequence of Liquefied ethylene leakage and take accident prevention measures.The form of Liquefied ethylene leakage is analyzed firstly in paper, Liquefied ethylene leakage rate was calculated by ALOHA. Large ethylene storage tank leakage diffusion process was simulated by using FDS software, the influence of cofferdam on the ethylene steam diffusion process were analyzed. The results showed that ethylene steam diffusion scope is bigger when no cofferdam around Liquefied ethylene tank. High concentration area mainly concentrated in the west side of ethylene tank near ethanol irrigation area, and adjacent to the tank wall of ethylene steam density is higher. High concentration area mainly concentrated in the cofferdam when having a cofferdam around the tank, due to the effect of blocking of the cofferdam, ethylene steam diffusion effect area is smaller. A small amount of ethylene steam would come across the cofferdam tank area, which lead to near the tank wall ethylene steam concentration increased. As the late leak leakage rate increases to the peak, ethylene will jet to the inner wall of the cofferdam, Ethylene steam along the cofferdam internal diffusion, Most of the ethylene steam accumulated within the cofferdam.Secondly, dangerous consequences of the instantaneous leakage was analyzed by ALOHA, And effects different types of ground on ethylene steam diffusion was analyzed by using ALOHA. The results showed under the same weather conditions and leakage parameters, the risk of ethylene leak the wet sand, dry sand concrete ground increased in same amount ethylene.Finally, poisoning, flash, vapor cloud explosion and the pool fire danger zone division of ethylene leakage diffusion were calculated by using ALOHA, concluding that poisoning, and vapor cloud explosion dangerous consequences were serious, providing guidance for taking accident emergency measures.
