Influence of Mine Environmental Factors on the Liquid CO₂ Pipeline Transport System with Great Altitude Difference

To prevent coal spontaneous combustion and store CO₂ in the coal mine, it is necessary to establish a fire-prevention pipeline transport system which continuously injects a large amount of liquid CO₂ from the ground to the underground area directly. At present, few studies are focused on the law of liquid CO₂ transport with great altitude difference. Moreover, the complex transport environment in the coal mine affects the design and application of the pipeline transport system for ground direct injection of liquid CO₂. This study explores the influence of environmental factors at different depths in the coal mine on the liquid CO₂ transport. Excessive altitude difference, ambient temperature and airflow velocity may lead to the boiling of liquid CO₂ during pipeline transport and a sudden drop in CO₂ temperature and pressure, which may cause danger in the pipeline transport system. The critical insulation thickness is determined based on the occurrence of the boiling of CO₂. In addition, the influence law of adding an insulating layer of different thicknesses to the CO₂ pipeline system is obtained. This study is of great significance to the establishment of a pipeline system that safely transports liquid CO₂ from the ground to the underground mine.