液态 CO2具有惰化和相变吸热的优良特性，可以对煤自燃进行预防与治理。根据现场情况，一般采用地面固定式或井下移动式液态 CO2型储液罐进行防灭火。考虑到安全性，液态 CO2一般为低温低压存储。受现场环境和井下空间尺度影响，液态 CO2罐车通常不会立即使用，充装完毕后多存储于现场通风避光处。由于液态 CO2的沸点较低，受环境影响，在储运过程中无法避免汽化损失。该过程会造成 CO2浪费，增加成本，可能造成人员伤亡。在灭火过程中，根据火区熄灭程度，注 CO2量需及时调整。由于安全阀的泄压，储罐使用时液态 CO2的余量可能不足，会影响灭火工作的开展。

为解决上述问题，搭建了液态 CO2低温存储测试实验台，进行液态 CO2储罐液压实验，以保证储罐气密性和可靠性；进行 CO2饱和蒸汽压曲线测定，为实验提供数据基础。

其次，以外界温度、初始充装率、传热效率为自变量，对不同条件下储罐内液态CO2自增压过程研究，结果为液态 CO2温压增长率先升高后降低，最后趋于稳定。在其余条件不变时，环境温度影响温压上升速率差值在 10min~20min 时最大；初始充装率影响储罐内液态 CO2温度上升快慢的主要阶段为存储前期，温压上升速率差值最大位置在10min 处；提高传热效率，单位时间内液态 CO2温压上升速率越快。在实验开始时温压上升速率差值最大，无保温层条件下差值约为 1.5~1.8 倍；液相区温度以轴心线向外， 沿径向递增分布，轴向基本相同；气相区以轴心线向外，沿径向递增分布，轴向由气-液两相界面至气相空间顶部逐渐增加；气相区 CO2温度始终大于液相区 CO2温度，直至储罐状态稳定后，两相温度趋于相等；气相和液相区 CO2压力以相同速率竞争交替上升。 最后，研究了回座压力、整定压力对液态 CO2储罐的泄放规律。至储罐内液态 CO2剩余量为 10%时，不改变其余条件，回座压力为 4.5MPa 比 4.2MPa 时多泄压 5 次，用时 约为的 1.3 倍；整定压力为 5MPa 和 2.4MPa 时，两者都经过相近次数泄压后，用时约为的 4.4~4.8 倍；初始充装率从 30%每增加 20%，泄压次数增加 2 次，用时增加 30%~35%。即充装率和整定压力一定时，适当提高安全阀的回座压力，虽然使安全阀启动次数增加，但可以延长储罐内液态 CO2的存储时间；充装率一定时，安全阀的整定压力越高，储罐内液态 CO2的存储时间越长；充装率越高，安全阀的启动次数越多，启动间隔时间和存储时间越长，但单位时间内 CO2浪费量少。储罐单次的泄放量和回座压力与整定压力的比值有关，两压力的差值与储罐泄放量呈正相关，其中，阀门首次启动排放的液态CO2量最大。研究结果可对矿井灭火工作的开展提供一定参考。

L-CO2 has the excellent characteristics of inerting and phase change heat absorption,which can prevent and control spontaneous coal combustion. According to the site conditions, ground fixed or underground mobile L-CO2 type storage tanks are generally used for fire prevention. Considering the safety, L-CO2 is generally stored at low temperature and low pressure. Affected by the site environment and underground space scale, L-CO2 tanker is usually not used immediately, and after filling, it is mostly stored in the ventilated and light-avoiding place on site. Due to the low boiling point of L-CO2 and the influence of the environment, it is impossible to avoid vaporization loss during storage and transportation. This process will cause CO2 waste, increase costs, and may cause casualties. During the fire extinguishing process, the amount of CO2 injection needs to be adjusted in time according to the degree of extinguishment of the fire zone. Due to the pressure relief of the safety valve, the residual amount of L-CO2 may be insufficient when the storage tank is in use, which will affect the fire extinguishing work. In order to solve the above problems, a L-CO2 low-temperature storage test bench was built to carry out hydraulic experiments on L-CO2 storage tanks to ensure the airtightness and reliability of the tanks; and to carry out the determination of CO2 saturated vapor pressure curves to provide a data basis for the experiments.

Secondly, with the external temperature, initial filling rate and heat transfer efficiency as independent variables, the self-pressurization process of L-CO2 in the storage tank under different conditions was studied, and the result was that the growth rate of temperature and pressure of L-CO2 firstly increased and then decreased, and finally stabilized. In the rest of the conditions remain unchanged, the ambient temperature affects the temperature and pressure rise rate difference in 10min~20min when the maximum; the initial filling rate affects the L-CO2 temperature rise in the storage tank for the main stage of the storage of the pre-storage period, the temperature and pressure rise rate difference in the maximum position in the 10min; to improve the efficiency of the heat transfer, the faster the rate of rise of the temperature and pressure of the L-CO2 in the unit of time. At the beginning of the experiment, the temperature and pressure rise rate difference is the largest, without insulation conditions, the difference is about 1.5~1.8 times; liquid phase temperature to the axis outward, along the radial incremental distribution, the axial direction is basically the same; gas-phase area to the axis outward, along the radial incremental distribution, the axial direction of gas-liquid two-phase interface to the top of the gas-phase space is gradually increasing; gas-phase CO2 temperature is always greater than the liquid-phase area CO2 temperature, until the tank The temperature of CO2 in the gas-phase region is always higher than that in the liquid-phase region until the tank is stabilized, and the temperatures of the two phases tend to be equal; the CO2 pressures in the gas-phase and liquid-phase regions rise alternately at the same rate.

Finally, the discharge law of L-CO2 storage tank by return pressure and calibration pressure was studied. To the tank L-CO2 residual amount of 10%, do not change the rest of the conditions, back to the seat pressure of 4.5MPa than 4.2MPa more than 5 times pressure relief, time is about 1.3 times; set pressure of 5MPa and 2.4MPa, both after a similar number of times after the pressure relief, the time is about 4.4 ~ 4.8 times; the initial filling rate of 30% from 20% every increase in the number of times the number of times the pressure relief increased by 2 times, the time increased by 30%~35%. The initial filling rate increases from 30% every 20%, the number of times of pressure relief increases by 2 times, and the time used increases by 30%~35%. That is, when the filling rate and setting pressure is certain, the appropriate increase in the safety valve return pressure, although the number of times the safety valve starts to increase, but it can extend the storage time of L-CO2 in the tank; filling rate is certain, the higher the setting pressure of the safety valve, the longer the storage time of L-CO2 in the tank; the higher the filling rate, the higher the number of times the safety valve starts to start the start-up interval and storage time is longer, but the unit of time within the The amount of CO2 wasted is less. The amount of discharge and return seat pressure of the storage tank at a single time are related to the ratio of the set pressure, and the difference between the two pressures is positively correlated with the amount of discharge from the storage tank, in which the amount of L-CO2 discharged from the first activation of the valve is the largest. The results of the study can provide a certain reference for the development of mine fire suppression