基于高倍数泡沫的LNG泄漏扩散抑制研究

发布时间：2018-11-24 08:06

【摘要】：近几年,随着我国液化天然气(Liquefied Natural Gas,LNG)生产、运输和储存项目的不断投用,LNG产业得以飞速发展。LNG产业的快速发展一定程度上填补了国内能源需求的缺口,改善了我国能源短缺和环境污染的现状;但是快速增多的LNG站场也带来了安全隐患和事故风险。大量的研究结果表明:由于液化天然气具有极低温和易燃易爆的特性,LNG泄漏后的液体和蒸气对人员和设备都会造成伤害,特别是泄漏后形成的蒸气云一旦遇到点火源极有可能发生严重的火灾、爆炸事故。因而,非常有必要对LNG泄漏后的扩散行为和扩散抑制技术开展研究,选择合适的抑制技术以减小LNG泄漏扩散范围,最大限度的避免灾害性事故的发生。高倍数泡沫是一种抑制LNG扩散的有效方法,但是目前对其抑制机理还不明确,一些关键应用参数需要通过实验进一步确定。鉴于此,本文主要开展了以下研究工作:(1)通过分析储液池蒸发过程中的热量、动量和质量转换以及蒸气云在大气中的扩散原理,找出影响LNG蒸发扩散的主要因素是热量输入和气体流动程度,并提出高倍数泡沫对LNG蒸发扩散的抑制机理:高倍数泡沫覆盖着LNG储液面上方后由于带入了大量热源,上层泡沫对LNG蒸气进行加热,使得LNG蒸气密度降低,LNG蒸气上浮,进而降低了地面处可燃气云浓度和体积,以减小发生火灾爆炸事故的概率。(2)从流体动力学的角度出发,利用基于CFD理论的KFX软件,对国外大型LNG泄漏扩散实验进行模拟计算。模拟计算结果表明:KFX软件可以有效地模拟LNG蒸发扩散过程。模拟计算中监测点的浓度变化、储液池温度变化、蒸气云范围及高倍数泡沫抑制效果等结果都与实验结果非常相似。模拟结果验证了前面提出的抑制机理。(3)通过实验前的模拟计算,预测LNG实验结果。模拟结果表明:模拟结果给出了一定风速作用下的可燃气云范围,和关键设施处的可燃气云浓度,并为LNG现场实验的监测点布置等工作提供参考。(4)根据预测模拟计算结果,开展LNG泄漏扩散实验,实验结果表明:LNG储液池下风向浓度、温度、高倍数泡沫的抑制效果等数据与国外现有实验结果相似。实验结果中的储液池温度、气云、质量蒸发速率等数据变化反映出高倍数泡沫对LNG储液池的蒸发扩散的抑制作用,验证了高倍数泡沫抑制机理和有效性。
[Abstract]:In recent years, with the continuous use of (Liquefied Natural Gas,LNG production, transportation and storage projects in China, the LNG industry has developed rapidly. The rapid development of LNG industry has filled the gap of domestic energy demand to a certain extent. It improves the current situation of energy shortage and environmental pollution in China. But the rapid increase of LNG yard also brought safety risks and accident risks. A large number of research results show that because LNG has the characteristics of extremely low temperature and flammable and explosive, the liquid and steam after LNG leakage will cause harm to people and equipment. Especially, serious fire and explosion may occur once the steam cloud is exposed to the ignition source. Therefore, it is very necessary to study the diffusion behavior and diffusion suppression technology after LNG leakage, select appropriate suppression technology to reduce the diffusion scope of LNG leakage, and avoid the occurrence of catastrophic accidents to the maximum extent. High expansion foam is an effective method to inhibit the diffusion of LNG, but the mechanism of its inhibition is not clear at present. Some key application parameters need to be further determined by experiments. In view of this, this paper has mainly carried out the following research work: (1) by analyzing the heat, momentum and mass transfer in the evaporation process of the liquid storage tank and the diffusion principle of the vapor cloud in the atmosphere, The main factors affecting the evaporation diffusion of LNG are heat input and gas flow degree, and the mechanism of high expansion foam inhibiting the evaporation diffusion of LNG is put forward. The high expansion foam covers the top of the LNG storage level and brings in a large number of heat sources. The upper foam heats the LNG vapor, which reduces the density of LNG vapor and floats LNG vapor, thus reducing the concentration and volume of gas cloud on the ground to reduce the probability of fire and explosion accident. (2) from the point of view of hydrodynamics, By using KFX software based on CFD theory, the large scale LNG leakage diffusion experiments abroad are simulated and calculated. The simulation results show that the KFX software can effectively simulate the evaporation diffusion process of LNG. The experimental results are very similar to the experimental results, such as the concentration change of the monitoring point, the temperature change of the liquid storage tank, the range of vapor cloud and the effect of high multiple foam suppression in the simulation calculation. The simulation results verify the inhibition mechanism proposed above. (3) the LNG experimental results are predicted by the simulation calculation before the experiment. The simulation results show that the range of gas cloud under certain wind speed and the concentration of gas cloud at key facilities are given. It also provides a reference for the arrangement of monitoring points in the LNG field experiment. (4) according to the predicted simulation results, the LNG leakage diffusion experiment is carried out. The experimental results show that the concentration of wind direction and temperature under the LNG liquid storage tank, The data of the inhibition effect of high-expansion foam are similar to the existing experimental results abroad. The change of temperature, gas cloud and mass evaporation rate in the liquid storage tank reflects the inhibition effect of high expansion foam on the evaporation diffusion of LNG tank, and verifies the mechanism and effectiveness of high expansion foam suppression.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE88

【相似文献】