CNG加气站加气柱(枪)卸载气放空安全研究

Safety research of discharge gas vent for fueling column(nozzle)of CNG station

压缩天然气(CNG)加气站加气柱(枪)采用就地放空卸载气。卸载气在加气罩棚的扩散行为和浓度分布研究对于保障加气站的安全具有重要意义。采用FLACS软件,模拟计算了静风条件下加气柱(枪)卸载气在两种加气罩棚阻碍情况下,加气罩棚下部天然气气云体积和浓度在时间和空间的分布。研究结果表明,对于加气柱一次卸载气放空,将在罩棚下部形成一定的可燃气云区域;对于加气枪卸载气放空,即使连续排放,在罩棚下部也不会形成可燃气云;罩棚采用网格式或平板式结构对CNG加气柱(枪)卸载气放空时可燃气云的扩散行为影响不大。对于CNG加气站卸载气放空,加气柱的放空气需要引入站内安全处进行放空,而加气枪的卸载气可采用就地向上放空方式。

In CNG gas station, the discharge gas in fueling column （nozzle） is vented locally. Therefore, it＇s important to study the gas diffusion behavior and concentration distribution under the canopy. Under calm condition, the time and spatial distribution of discharge gas volume and concentration under two types of canopy were simulated using commercial software FLACS. The results showed that flammable gas cloud formed under canopy for the discharge gas in fueling column. However, for the discharge gas in fueling nozzle, the flammable gas cloud did not form even the discharge gas continuous vented. In addition, the types of canopy （ grid or flat plate） had little effect on the flammable gas cloud diffusion behavior. Based on these findings, the discharge gas in fueling column should be vented at a safe area. For the discharge gas in fueling nozzle, it could be vented upward locally.