关键词: CO₂扩散, 管线泄漏, 小尺度实验, 安全距离

Abstract: There are many safety issues in the process of CO₂ exploitation and utilization.As a heavy gas，CO₂ 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 CO₂ is 18000 mg·m^-3，which is equal to about 1%（volume）.In order to study the dispersion of CO₂ leaked from pipelines，a series of scaled field tests were conducted.Several infrared CO₂ 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 CO₂ is released with the initial flow rate 950 m³·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 m³·h^-1.The minimum deviation between experimental and theoretical prediction results is -3.0%，while the maximum is 28.1%.The conclusion is that CO₂ 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.

Key words: CO₂ dispersion, pipeline leakage, scaled field test, safety distance