| According to research of the current CO2 in long distance pipeline,the cut-off valve can reduce the volume of CO2 leakage,reduce the pipe fluid leakage hazards on the surrounding population and environmental,and reduce the loss of personal property.At the same time,cut-off valve can reduce the pipeline maintenance workload.So cut-off valve is very important for ensuring CO2 pipeline safe operation.But the cut-off valve will increase the cost,and increase the workload of monitoring and maintenance.Besides,due to the safety performance of the cut-off valve is low,it is easy to be a weak point of the entire pipeline safety management,and may be struck by lightning.Therefore,the spacing of the cut-off valve for CO2 long pipeline safety management and economic management are essential.This paper on the basis of domestic and foreign research literature by the CO2 pipeline leakage and diffusion theory,selection and calculation of the model,according to the effect of CO2 on the human body recommended,suggested CO2 pipeline valve spacing for different parts of the level of area,the specific contents were as follows:(1)Dense gas leakage diffusion model can be used for modeling CO2 included Gaussian model,Fluidyn-PANACHE CFD model and PHAST model.Three models all could simulate CO2 leakage and diffusion,but modified Gaussian model did not consider the jet effect,the CFD model calculation amount was large and the two models were not considered CO2 leakage from the phase change.So PHAST model was better.(2)According to the experimental observation,the leakage of CO2 leaded to the formation of dry ice.So CO2 leakage would occur when the gas-solid phase changes,due to the traditional leakage only considering gas-liquid phase change,so the study on the influence on the diffusion range caused by the leakage of CO2 gas-solid phase change was necessary.The results showed that considering the changes in gas-solid phase calculation results were 5 times as not taken into account in the gas-solid state variable,so could not ignore the leakage of CO2 gas-solid phase change.(3)Analysis of different physical parameters(pressure,diameter,leak and leakage angle)influence on leakage and diffusion results would produce the maximum diffusion range of physical conditions and the most adverse physical conditions.Then the effects of different environmental conditions(wind speed,atmospheric stability and relative humidity)on the results of leakage and diffusion were analyzed,and the conditions of the maximum diffusion range were obtained,which were the most unfavorable conditions.(4)Used SLOT(the probability of death 1～5%)and SLOD(the probability of death is 50%)data as boundary conditions,the most adverse physical and environmental conditions as the initial conditions to calculate to meet the safety requirements of the level in different regions different population number under the condition of the valve interval.Refer to the domestic and foreign existing CO2 pipeline operating parameters and relevant standards,combined with the leakage and diffusion theory,put forward that first level area from the safe consideration did not require the construction of the valve chamber,but in order to facilitate pipeline maintenance could facilitate the maintenance of the site to establish cut-off valve.According to the corresponding number of regions the second area could select valve spacing of 6～50km.Third or forth level regions did not recommend the establishment of supercritical transport CO2 pipeline. |
PDF Full Text Request