氢气-空气混合气体燃烧特性试验分析

为了保证严重事故下安全壳的完整性,氢气点火器燃烧缓解措施被广泛应用于核电站内。本文在1个20m3立式圆柱罐体内进行9.28%浓度下的氢气燃烧试验,结合GASFLOW数值模拟和其他试验数据,对本次试验结果进行了综合分析。试验和模拟结果均表明:9.28%浓度下氢气完全燃烧,罐体内温度和压力快速增加;燃烧过程中罐体内高温气体通过辐射传热、对流换热和相变传热3种方式向罐体结构散热,使得罐体内温度和压力随时间逐渐降低,达到泄压和冷却的作用;燃烧过程有明显的方向性,即点燃后火焰在浮力作用下沿罐体中心线向上传播,到达顶部后转而沿罐体四周向下燃烧,燃烧初期火焰速度为11.15m/s;试验中由于内部构件的影响,火焰传播更为复杂。

Test Analysis of Combustion Mechanism for Hydrogen-air Mixture

The hydrogen igniter combustion mitigation system is widely used in nuclear power plant for the purpose of ensuring the integrity of containment under severe accident. Combined with the numerical simulation using GASFLOW and other test data, the results obtained from the hydrogen combustion test carried out in a 20 m³ cylinder with 9.28% hydrogen were analyzed. The results show that the hydrogen is completely consumed, leading to a rapid increase in temperature and pressure inside the tank. The heat could be transferred from the gas to the cylinder by three means: radiation, convection and phase change. This heat transfer process could largely reduce the temperature and pressure in the cylinder, resulting in cooling of the gas and depressurization of the tank. At the beginning of the combustion, the flame will propagate upward along the centerline of the cylinder as a result of buoyancy; once reaching the roof of the tank, it turns around and spreads downwards. The flame propagation speed is around 11.15 m/s. Under the influence of different internal structures in the test, the propagation of the flame is more complex.