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

摘要： CO₂气体综合开发和利用过程中涉及很多安全问题，为了研究CO₂作为典型重质气体从输送管线泄漏后的扩散规律，在综述重气扩散实验的基础上设计了CO₂管线泄漏扩散缩比例实验；通过幂函数拟合得到监测点峰值浓度曲线，并据此确定了生产现场的安全距离；根据危险气体非正常排放模型对实验进行了理论预测，结果与实验值进行了对比。结果表明小风条件下，当以950 m³·h^-1初始流量释放20 min左右的CO₂时，现场安全距离可设为46 m，而当初始流量为6300 m³·h^-1时，现场安全距离为160 m；实验值和理论预测值的偏差最小为-3.0%，最大为28.1%。经分析可知CO₂管线泄漏近源区一定距离内主要靠射流动能扩散，其后范围主要受浓度梯度的影响，危险气体非正常排放模型可较准确地预测近源区的扩散情况；安全距离与泄放流量基本呈指数关系。

关键词: CO₂扩散, 管线泄漏, 小尺度实验, 安全距离