Research On Influence On Adjacent Gas/Oil Pipeline By Fire Resulted From Natural Gas Pipeline Failure

As “West-East Natural Gas Transmission Project” processed, natural gas pipelinenetwork construction evolves to be perfect gradually. As the important transmissionmedia, long-distance pipelines have been used in many ways. Moreover, the failure ofnatural gas pipelines leads to fire and explosion at times, which not only causes largecasualties, immense economic losses, but also severe environmental pollutionresulting from leakage gas. Taking terrain conditions into account, long-distancenatural gas pipelines are mostly buried underground so that it is relatively hard forworkers to check and fix the pipelines. Therefore, if the leakage or breakage ofpipelines happened, it is uneasy to be realized. As the research on the security ofpipelines goes on, more and more researchers focus their topic core on long-distanceparalleled pipelines.This paper illustrates such a condition: one of the two paralleled pipelines isbroken for some reason, leakage or breakage. It comes into jet fire to makeradioactive heat harm to the adjacent pipeline to make it become failure. The paperdistributes the whole process into three sub-processes, combustion process of jet fire,heat and mass transfer between two paralleled pipelines and the material failureprocess of adjacent pipeline. In order to calculate the morphology of jet fire, thispaper uses solid flame model to describe the jet fire, including fire length, fire heightand angle of fire slope. As for heat transfer process between two paralleled pipelines,this paper discusses the process in two aspects, direct fire flushing and indirect fireflushing to the adjacent pipeline, whose difference is whether to consider convectiveheat transfer. With regard to material failure process, mechanical stress and thermalstress are both to be considered. The mechanical stress resulting from pipeline internalpressure can be calculated according to stress analysis. Thermal stress is to becalculated by the means of thermal network method. Whether the adjacent pipelinebecomes failure or not decides on the comparative result between coupling calculativeresults and material yield limit.After theoretical analysis, this paper uses MATLAB to do programming to makethe theoretical model come into effect. Then in order to verify the accuracy oftheoretical model, this paper uses FLUENT to do numerical simulation for combustion and heat transfer process, in the meanwhile, ANSYS to do numericalsimulation for material failure process. Finally, this paper makes comparison betweenthe calculative results and simulative results. The error is within10%, which satisfiesthe requirements. According to the datas that acquire from the former operatingcondition, this paper discusses the influence of different leakage diameters, leakagevelocity, air velocity, natural gas transportation pressure, environment temperatureand barriers on the whole process by FLUENT.