The Study About Liquid-pipeline Specification Small Hole Leakage Law And Pressure Calculation Method After Leakage

Currently,with the development of China's economic,crude oil,refined oil consumption is increasing.As the most important oil transport mode,oil transport network is expanding.However,parts of the pipe network put into a longer life,affected by corrosion,running abrasion,quality flaw,irregular operation,damage and so on,pipeline leakage accident occur frequently.Considering the physical properties of oil,if leakage accident occurred and no one found,it easy lead to fires,explosions and other accidents,causing serious casualties and huge economic losses and negative social impact.Therefore,conducting pipeline risk assessment is extremely necessary for the safety of oil transport.As an important topic in the field of pipeline security,the calculation of leakage rate is the precondition and foundation of forecasting leakage consequences and assessing leakage risk.There a lot of liquid pipeline leakage models.Currently,liquid pipeline leakage model based on hydromechanics and mechanical energy conservation equation is very maturity.However,this models have some defects.For example,they don't consider the pressure change when leakage happened,neglect the influence of critical diameter of hole on leakage rate.In terms of leakage holes,they only take into account the regular leakage holes,not consider the irregular shape's impact on leakage rate.But in fact,the leakage holes are not regular usually.Therefore,classic leakage model has great limitations,can't use for calculation the leakage rate directly.In this paper,referenced exist research results,an experimental system for liquid hole-leaked was established to study pipeline flow and pressure effect on leakage rate and pipeline pressure through building different leakage scenarios,to summarize influence rules,and to obtain circular holes steady pressure calculation law,the law can be used to solve steady pressure calculation problem in classic formula;through changed initial pipeline pressure and flow,the leakage rate change law is studied,to obtain liquid leakage critical hole diameter under different conditions;based on actual leakage scenario,the typical irregular geometry and size of the leakage hole was determined,to study the stable leakage rate under different pipeline flow and pressure;combined the leakage experimental data of circular holesand irregular holes,the correspondence relationship between them was studies in same conditions,and the equivalent area coefficients was calculated;using oil pipeline as simulation objects,combining experimental data,same ratio similar experiment model of liquid pipeline was founded,to study the velocity distribution of leakage orifice interface and influence mechanism of pipeline flow and pressure under different conditions.According to the results,after leakage happened,basing on leakage hole shape and area,combining irregular holes area coefficient and leakage rate calculation formula,leakage rate can be obtain quickly and accurately.This can provide data support for leakage risk assessment and consequence prediction.