Research On Influencing Factors Of The Torch Venting Of Natural Gas Pipeline

The specific gas venting operation should be carried out to the long-distance natural gas transmission pipeline when accidents occur or the pipeline needs to be transformed.Because of its own flammable and explosive characteristics,different venting methods of natural gas have different risks.At present,many venting accidents have occurred due to improper venting mode or the existence of obstacles.According to the diffusion process of natural gas and the thermal radiation model of ignition and venting,the influence factors are determined,and the assumptions and possible errors of the model are put forward.CFD numerical simulation was used to analyze the influence of wind speed,mass flow rate and obstacles on gas flow inclination angle and gas diffusion range during natural gas cold venting.The influence of wind speed,mass flow rate,torch height and obstacles on flame temperature field and thermal radiation field distribution is analyzed by numerical simulation during natural gas ignition and venting,and the safe distance of thermal radiation is derived.The torch of a station of west-to-east gas pipeline project is selected for analyzing,which is divided into two cases: no obstacle and obstacle.The safety and economical efficiency of the two venting modes are compared respectively,and the corresponding risk control measures are put forward according to the simulation results.Finally,for the presence or absence of obstacles,the effectiveness of the heat radiation calculation model is verified.The results show that even in extreme weather,the gas from the cold venting of natural gas will not diffuse to the near-surface in the absence of obstacles,which verifies the safety of the cold venting.During ignition and emptying,the safety near the ground is greatly influenced by many factors,such as wind speed and so on.In the presence of obstacles,cold venting gas will gather in front of the obstacles into a high concentration of gas,and increase the risk of uncertainty.Obstacles will hinder the propagation of heat radiation and reduce the safe distance of heat radiation during ignition and emptying.The research results of this paper can be referenced for the selection of gas venting modes in engineering practice,and have certain guiding significance for risk control and consequence prediction in venting operation.