CO2和细水雾对地下变电站变压器火灾抑制作用研究

Research on Suppression Effect of CO2 and Water Mist on Transformer Fire in Underground Substation

摘要:

为了研究CO2和细水雾对地下变电站变压器油火灾爆炸的抑制作用及其化学动力学机理，利用实验和Chemkin软件数值模拟研究了不同体积分数的细水雾和CO2对化学当量比条件下20% H2-CH4-air混合物爆炸的影响。实验和模拟结果表明：细水雾对H2-CH4-air混合物的火焰结构和爆炸压力的抑制作用随着细水雾体积分数的增加而愈发明显；细水雾蒸发产生的水蒸气分子和CO2在反应体系中主要起稳定的第三体作用，从而减缓了爆炸链式反应的发展。另外，CO2是CH4氧化反应的主要产物，加入CO2会削弱甲烷氧化的基元反应；反应体系中加入细水雾会通过降低基元反应温度敏感性来抑制反应体系升温，并且加入CO2会促进消耗·H自由基的基元反应发生。这也是CO2和细水雾共同作用抑制效果优于细水雾单独作用的原因。以上研究结果可为地下变电站变压器油火灾爆炸防治技术的发展提供理论依据。

Abstract:

In order to study the suppression effect of CO2 and water mist on fire and explosion of transformer oil in underground substation and its chemical kinetic mechanism, the influence of water mist and CO2 with different volume fractions on the explosion of 20% H2-CH4-air mixture at stoichiometric ratio is studied by using experiments and Chemkin numerical simulations. Experimental and simulation results show that: the suppression effect on flame structure and expolosion pressure of H2-CH4-air mixture is more obvious with the increase of volume fraction of water mist. Water vapor molecules produced by evaporation of water mist and CO2 in the reaction system mainly play a stable role as a third body, thus slowing down the development of explosion chain reaction. In addition, since CO2 is the main product of methane oxidation reactions, the addition of CO2 will weaken the elementary reaction of methane oxidation. The addition of water mist to reaction system will inhibit the heating of reaction system through reducing the temperature sensitivity of elementary reaction, and the addition of CO2 will promote the generation of elementary reaction to consume ·H radicals. This is the reason why the combined suppression effect of CO2 and water mist is better than that of water mist alone. The above results can provide a theoretical basis for the development of prevention technologies for fire and explosion of transformer oil in underground substations.