天然气地面火炬尾气扩散浓度计算

Calculation for Diffusion Concentration of Natural Gas Ground Flare Exhaust Gas

油气田地面工程站场中火炬放空尾气中有害气体组分(如二氧化碳、氮氧化物和烃类气体)对环境有较大的影响,计算火炬尾气地面扩散浓度是评估火炬放空扩散的重要依据。结合某海外地面站场工程项目所在地地形、气候等环境要素以及污染源情况,采用Gaussian大气污染物扩散模型,确定地面封闭式火炬的水平和垂直方向扩散系数、有效高度和烟羽漂浮高度求值关系式,以空间连续长方体模型建立高架点源的烟羽大气扩散坐标系,计算地面火炬尾气污染物在扩散范围内下风向不同位置的扩散浓度。计算结果表明,地面火炬下风向30 m内出现峰值浓度后逐步衰减,满足大气排放限值要求。该方法在设计油气处理站场火炬系统大气排放时值得借鉴。

The harmful gas components(such as carbon dioxide,nitrogen oxide,and hydrocarbon gas) in the flare exhaust gas in the oil and gas field surface engineering stations have a great impact on the environment.The calculation of flare exhaust diffusion concentration is an important basis for the evaluation of flare exhaust diffusion.Combined with the topography,climate,and other environmental factors,and pollution sources of an overseas ground station project,the Gaussian atmospheric pollutant diffusion model is used to determine the evaluation equation of the horizontal and vertical diffusion coefficient,the effective height,and the plume floating height of the enclosed ground flare.Based on the continuous cuboid space model,the atmospheric diffusion coordinate system of the plume from the elevated point source is established to calculate the diffusion concentrations of the exhaust pollutants in different downwind positions within the diffusion range.The calculation results show that the peak concentration of ground flare exhaust appears within 30 m downwind and then gradually decreases,meeting the requirements of atmospheric emission limit value.This method can be used for reference in the design of atmospheric emissions from the flare system of oil and gas treatment stations.