Balance of CO2/CH4 exchange sorption in a coal briquette

The article presents findings of a study on CO2/CH4 exchange sorption taking place in a coal briquette, initiated by the injection of a CO2 into a briquette that was previously saturated with CH4. The briquette was subjected to multiple cycles consisting of vacuum outgassing, CH4 saturation under 10 bar pressure, and an exchange sorption process. In each experiment input CO2 pressure and output gas mixture pressure were stabilized. The chosen pressure levels were 12, 13 and 11 bar at the input and 10 bar at the output of the briquette. Flow rate of gas streams flowing to and flowing out of the briquette, as well as gas concentration at the output of the briquette, was measured. During the process of exchange sorption, the flow rate of gas streams at the input and output of the briquette varied, even though the input and output pressures were constant. In all the experiments, the entire CH4 was displaced from the briquette after injecting about twice the rate of the CO2 mass in relation to the previously sorptive bonded CH4. The results thus obtained were confronted with results obtained by other researchers, available in relevant sources, for the purpose of their comparison.