Scaled field test for CO ₂ leakage and dispersion from pipelines

There are many safety issues in the process of CO ₂ exploitation and utilization. As a heavy gas, CO ₂ exhibits different dispersion behavior compared with the neutral gases. It will fall down to the floor and then disperse along the ground and do harm to people, such as asphyxia and frostbite. According to the national standard, the maximum allowance limit of CO ₂ is 18000 mg·m ^-3, which is equal to about 1% (volume). In order to study the dispersion of CO ₂ leaked from pipelines, a series of scaled field tests were conducted. Several infrared CO ₂ sensors were arranged on the downwind ground to detect the concentration. The concentration distributions were analyzed. Peak concentration curves of the test points were fitted to determine safety distances of the scenes. The scenes were also predicted by the non-normal emission model of dangerous gas and compared with the experiment results. When CO ₂ is released with the initial flow rate 950 m ³·h ^-1 for 20 min under light wind, the safety distance is 46 m, while the distance is 160 m with the initial flow rate 6300 of m ³·h ^-1. The minimum deviation between experimental and theoretical prediction results is -3.0%, while the maximum is 28.1%. The conclusion is that CO ₂ spreads mainly by the jet kinetic energy within a certain distance near the release source while its dispersion is driven mainly by the concentration gradient far from the source. The spread situation near the source can be predicted accurately by the non-normal emission model of dangerous gas. It can be proved that safety distance and discharge flow are exponentially related.