天然气放空管地面爆燃点火装置点火特性研究

Ignition characteristics of ground deflagration ignition device for vent flares

关键词:  地面爆燃点火装置  点火性能  可燃气体体积分数  可燃气体充装率  传火管长度

Key words:  ground deflagration igniting device  ignition performance  volumn fraction of combustible gas  filling ratio of combustible gas  length of flash tube

摘要:

针对目前对天然气放空管地面爆燃点火装置点火机理认识的不足,导致其一次点火成功率较低的问题,采用FLACS分析了典型地面爆燃点火装置传火管传火动态过程,探讨了传火管内可燃气体体积分数、可燃气体充装率以及传火管长度对其点火性能的影响。结果 表明:传火管内的平均火焰传播速度为155 m/s,为爆燃过程；传火过程中传火管内的最大超压峰值高达2.5×10⁵ Pa,须确保传火管具有足够的承压能力,且应固定牢靠；地面爆燃点火装置应在可燃气体和压缩空气进口管路分别增设流量计量仪表,使传火管内充装体积分数接近于9.5%的可燃气体,并确保充装率在40%以上；传火管的点火性能随其长度的增大而变差,尤其在传火管长度大于35 m后将快速变差。研究成果为天然气放空管地面爆燃点火装置的优化设计、安装固定与点火操作提供了理论支撑。 

Abstract:

Currently, the limited understanding for the ignition characteristics of ground deflagration devices in the flare system results in a very poor ignition performance. In this study, the dynamic process of flame propagation in the flash tube is analyzed by FLACS for a typical ground deflagration igniting device numerically. The effects of relevant parameters on the ignition performance are investigated, including the volume fraction and the filling proportion of combustible gas in the flash tube, as well as the length of flash tube. The results show that the average flame propagation speed in the flash tube can reach up to 155 m/s. The maximum peak overpressure in the flash tube is up to 2.5×10⁵ Pa, and thus the flash tube should have a sufficient pressure capacity. The inlet pipes of fuel gas and compressed air should be equipped with appropriate gas flow meters, respectively. The flash tube should be filled with a combustible gas with a volumn fraction of 9.5% to improve its ignition performance. Furthermore, the ignition performance decreases with the increase of the length of flash tube, especially when its length is longer than 35 m. The achievements can provide theoretical guidelines for the optimal design, the installation and the operation of the ground deflagration ignition devices.