Model Test on Underground Coal Gasification (UCG) with Low-pressure Fire Seepage Push-through. Part II: Oxygen-enriched Fire Seepage and Analysis

Abstract

The technology of a pushing-through gallery with oxygen-enriched fire-seepage combustion was studied during shaft-free UCG in this article, and the main experiment parameters were probed. The test results were analyzed in depth. The patterns of variation and development were pointed out for the fire source moving speed, temperature field, leakage rate, the expanding diameter for the gasification gallery, and blasting pressure. Test results showed that, with the increase in the wind-blasting volume, the moving velocity for the fire source speeded up, and the average temperature for the gallery continuously rose. Under the condition of oxygen-enriched air blasting, when O₂ contents stood at 90%, the moving speed for the fire source was 4–5 times that of air blasting. In the push-through process, the average leakage rate for the blasting was 82.23%, with the average discharge volume of 3.43 m³/h and average gallery diameter of 7.87 cm. With the proceeding of firepower seepage, the extent of dropping for the leakage rate increased rapidly, and the drop rate for the blasting pressure gradually heightened.

Keywords:

• expanding diameter
• low pressure
• moving speed fire source
• oxygen-enriched fire-seepage combustion
• shaft-free UCG
• temperature field

Acknowledgments

This work was supported by the National Natural Science Foundations of China (Ratification No.: 59906014, 50276066, 20207014, 50674084). The technical contributions of Professor Liu Shuqin and Dr. Sun Yajun are gratefully acknowledged by the author. The author also gratefully thanks Professors Zhang Weilian and Yue Fengtian for helpful discussion.