Study On Leakage Jet Hazard Of High-pressure Dense-phase CO₂ In Pipeline Transportation

CO₂-EOR is a highly efficient technology to enhance oil recovery.CO₂ storage combined with CO₂ flooding has wide application prospect.High-pressure dense-phase CO₂ conveying is the main CO₂ conveying way in our country.During the conveying process,CO₂ is in a state of High-pressure dense-phase.If CO₂leakage did occur which caused by the line equipment damage,the high speed jet at low temperature will be a serious threat to people's lives and property safety.Therefore,effectively evaluating the harm of high-pressure dense-phase CO₂leakage and studying the mechanism and consequences of the accident are important to guarantee the security of high-pressure dense-phase CO₂ conveying.In this paper,high-pressure dense-phase CO₂ conveying was chosen as the background and CO₂ pipeline as the research object.Facing the process of CO₂leakage,experiment system was designed for high-pressure dense-phase CO₂leakage simulation,the effect factors of jet power and the corresponding trend was studied,and the BLEVE phenomenon in the process of high-pressure dense-phase CO₂ leakage was validated.1)The experiment studies the effect of leak diameter,leak pressure and distance on leakage jet impact.Leak diameter is an important parameter of leakage jet impact.The larger leak diameter is,the greater the impact of the jet,the jet diameter,jet molding rate become.Impact under the influence of leak pressure trend is that as leakage pressure largen,the impact becomes bigger.But by the effect of BLEVE factors,the trend is not so stable and can't be a general rule.Distance is also important parameters influencing leakage jet impact.With the increase of distance,jet impact showed a trend of decrease,and the rate of the impact decrease changed sharply.2)In the process of high-pressure dense-phase CO₂ leakage,BLEVE phenomenon easily happened in small hole leakage and intensified extent of damage.In experimental condition,the best decompression diameter of BLEVE occurrence is 8¹5 mm,and the BLEVE phenomenon is more intense.The different leakage pressure has different BLEVE leak diameter range.The bigger leakage pressure can lead larger BLEVE leak diameter range.The effect of pressure on high-pressure dense-phase CO₂ BLEVE is roughly as leakage pressure gets bigger,the influence of BLEVE is increased.But the rule of best leak diameter is not so stable,and coincides with the irregular phenomenon caused by impact force which is affected by pressure leakage.3)According to the experimental results,it confirmed that the safe distance of high-pressure dense-phase CO₂ leakage is 5 m,and provided an important scientific basis to control high-pressure dense-phase CO₂ leakage accidents.Providing some advice about pipe design,production and accident emergency in high-pressure dense-phase CO₂ conveying.