四氯化硅泄漏迁移-转化过程数值模拟

Numerical simulation on migration and conversion of spilled silicon tetrachloride in the atmosphere

针对四氯化硅泄漏后形成的重气云的三维大气扩散与反应转化过程采用计算流体力学进行模拟,研究了四氯化硅气体与水蒸气反应过程中不同时刻四氯化硅、氯化氢等有毒物质的空间分布与转化情形。四氯化硅受重力作用下沉并向周围扩展,迎风面处的四氯化硅下沉触碰到地面后向上风侧移动,但主体向下风向迁移。反应主要发生在气团外层,生成的毒害性氯化氢覆盖范围较四氯化硅广泛,反应物和生成物在近地面的质量分数较大;水解反应消耗水分导致脱水效应和反应放热升温,会对该区域生态造成严重危害。研究了空气湿度和风速对四氯化硅迁移转化的影响。空气湿度对四氯化硅质量分数影响较小,主要影响生成物的质量分数变化,湿度越大氯化氢质量分数越高。风速主要影响反应物和生成物达到质量分数分布波峰的时间,风速越大,高质量分数氯化氢的存在时间越短。

While the polycrystalline silicon solar cells occupy a major position in the photovoltaic field, the volatile silicon tetrachloride is the main byproduct of the polysilicon industry. In the events of leakage during storage and transportation, silicon tetrachloride rapidly forms a dense gas cloud and reacts rapidly with water vapor in the atmosphere to finally form a gas cloud consists of the mixture of silicon tetrachloride, hydrochloric acid and silicic acid which cause serious environmental hazards and endanger the community and people. In the article, CFD methodology is applied to simulate the three-dimensional dispersion and transport processes with reaction of the dense gas cloud formed by the leakage of silicon tetrachloride. Silicon tetrachloride mainly sinks onto the ground and extends to the surrounding. After silicon tetrachloride at the windward side sink and touch the ground, it moves to windward side, but the main body of the dense cloud moves downwind. Reaction occurs mainly in the outer air masses. Hydrogen chloride is in a larger coverage. High concentrations of the reactants and products in the near-surface threaten the safety of the environment. The hydrolysis reaction near the ground consumes water results in the dehydration effect and the exothermic reaction, which have a serious threat to the ecosystem of the area. The influence of air humidity and wind speed to the migration and conversion of silicon tetrachloride were studied. The results show that air humidity has little influence on the concentrations of silicon tetrachloride; higher air humidity will cause greater formation of hydrogen chloride. In the greater wind speed, the time that the results reach the maximum concentration is shorter and the maximum concentration is smaller; the greater the wind speed is, the shorter time for the presence of high concentration hydrogen chloride. The present study provides a basis for the accident treatment of reactive hazardous chemicals.