Simplified model of the CO2/CH4 exchange sorption process

• We design a numerical model describing the process of the CO2/CH4 exchange sorption on coal briquette.
• The model is based on a number of hypotheses and simplifications.
• We compare the results of the simulation with the experimental results.
• Results obtained from the model-based simulation and from the experiment are convergent.

The necessity to reduce the increasing amounts of carbon dioxide (CO2) in the atmosphere entails searching for some effective methods that enable safe storage of the gas in question. A method known as enhanced coal bed methane recovery (ECBM), involving injection of CO2 into unexploited coal beds, makes it possible to obtain CH4, too. The ECBM method is based on the exchange sorption phenomenon. The present paper provides a numerical model describing the process of the CO2/CH4 exchange sorption on coal briquette. The model is based on a number of hypotheses. It was assumed that the exchange sorption occurs on the surface, between the sides of grain and the sorbent macropores. Certain hypotheses were formed as to the kinetics of the exchange sorption process, as well as the impact of its consecutive stages on the filtrational transport of a gas mixture through the network of macropores. The presented model of exchange sorption is a system of equations, solved numerically. Simulations carried out by means of the thus constructed model were compared with the results obtained in the course of laboratory experiments into the CO2/CH4 exchange sorption on coal briquette.