Research On Thermal Radiation Damage Effect Of Explosive Fireball From High-pressure Natural Gas Pipeline Leakage In Large Open Space

Study on the explosion accidents that casued by high-pressure natural gas pipeline leakage during the gathering and transmission process is an important task of safety science.The explosive fireball could form in short period of time when large natural gas pipeline leakage and explosion occur,the thermal radiation of fireball will cause damage effect to the human beings and environment within a certain scope.This paper made thorough researches on the thermal radiation damage effect of explosive fireball from high-pressure natural gas pipeline leakage in large open space,according to the thermal effect theory of natural gas explosive fireball,then presented applicable thermal radiation damage criterion,proposed theoretical modified model for calculating the explosive fireball parameters,designed a thermal radiation measurement system for large transient high temperature of explosive fireball based on the colorimetry pyrometry technique,and proposed measurement scheme of fireball temperature field for large high-pressure natural gas pipeline leakage explosion,carried out a full-scale experiment of high-pressure natural gas pipeline leakage rely on the first large natural gas pipelines blasting tests field,the full-scale experiment scenario was simulated,analyzed the accuracy of theoretical modified model and validity of full-scale experiment measurement scheme,improved the temperature field tomography algorithm,and constructed three dimensional temperature field model of high-pressure natural gas pipeline leakage explosive fireball.1)According to the characteristics of thermal radiation transfer for high-pressure natural gas pipeline leakage explosive fireball in large open space,the absorption effects from CO₂and H₂O were considered in the calculated process for the atmospheric transmission rate,which proposed the TNO modified model,then calculated thermal parameters of explosive fireball from high-pressure natural gas pipeline leakage in large open space,obtained the fitting changing curves of thermal radiation intensity,based on the selected thermal radiant flux damage criterion for assessing the explosive fireball thermal radiation damage level and range,it can be determined the thermal radiation damage theoretical range.2)In order to carry out the full-scale experiment,the testing scenario of the explosive fireball thermal radiation temperature field was designed and proposed based on the colorimetry pyrometry technique,in the full-scale experimental testing process,it was arranged six measurement points with different heights in the testing area for collecting the temperature field data inside the explosive fireball,the fitting changing curves of thermal radiation intensity from high-pressure natural gas pipeline leakage explosive fireball was obtained through the experimental testing,which was in agreement with the theoretical calculated result,in the meantime,the center height of explosive fireball can be deduced from the experimental result when the fireball diameter was maximum,the experimental fireball center height of 170 m was basically in agreement with the theoretical calculated height of161 m,which can be verified the calculation accuracy of TNO modified theoretical model.3)The full-scale experiment scenario was simulated by using risk assessment software PHAST,the leakage model,diffusion model and explosion model were selected in PHAST,and the original boundary conditions which included explosive material,leakage pattern,pipe paremeters,environmental parameters were set based on real experimental scenario,the thermal radiation intensity changing curves and damage range of explosive fireball can be obtained through the simulation,which were basically consistent with theoretically calculated result and experimental result,the comparison showed that the full-scale experimental method and testing scheme were valid,in the meantime,the boundary conditions in PHAST can be vertified by the experimental result as well.After comprehensive analysis,it can be determined that the death range from thermal radiation damage effect of this high-pressure natural gas leakage explosive fireball with the diameter of 250 m and the minimum safety range with diameter of 1 715 m.4)Based on the tomography algorithm of explosive and fire temperature field,this paper had tried to make improvement on the traditional tomography algebraic iterative algorithm,combined with the temperature experimental data of explosive fire by colorimetric temperature measurement system,the experimental data were discretized to obtain transient two-dimensional temperature testing plane of explosive fireball,then the three-dimensional temperature field model was established by using the modified temperature field tomography algorithm,along with graphical visualization of explosive fireball three-dimensional temperature field with software MATLAB,as compared with the MATLAB simulations and experimental results of the same mechanism,it was showed that the maximum relative error within the allowable range,it was demonstrated that the method for creating three-dimensional temperature field of large natural gas leakage explosive fireball was effective.