Abstract:

In order to study the effect of liquid CO₂ injection on coal spontaneous combustion heat production and gas release in the gob with high gas content and easy spontaneous combustion, the gas desorption test system was composed of a self-made variable temperature chamber and desorption instrument to simulate the influence of liquid CO₂ injected into a high-temperature point of gob on coal sample temperature and coal gas desorption amount and analyze the change of gas desorption energy of coal sample under corresponding coal body gas pressure and different temperature during the process of "falling to rising" temperature change. The results show that the temperature of the coal sample will stabilize at a lower level, and the gas will stop desorbing within 60 minutes to 100 minutes after the liquid CO₂ is injected. After 100 minutes, the cold energy gradually runs out, and the coal continues to oxidize and heat up, and the gas resumes desorbing with an increasing desorption rate. The cold energy released by the liquefied CO₂ gasification and the CO₂ gas has an excellent inhibitory effect on reducing coal temperature and gas desorption. When the coal sample temperature is between 10 and 30 ℃, the coal is in a low energy state. In this temperature range, the internal coal is more likely to cause the adsorption heat value to stabilize. The decrease in the surface free energy of the coal body will also present a stable trend.

Key words: goaf, high temperature point, liquid CO₂, gas desorption, heat of adsorption, surface free energy