Mass transfer process of desorption of CBM in Dafosi coal reservoir

Targeted at the particle migration process, energy source and transmission of CH₄ during its desorption process, the vitrain and durain in No.4 Mine of Dafosi are stripped to conduct a series of contrast experiments concerning industrial analysis, coal petrographical analysis, liquid nitrogen adsorption, mercury injection experiments, wetting testing, adsorption and desorption, and then the adsorption heats are calculated. It is discovered that (1) In terms of mass transfer function, coal pores are classified into semi-open pores and interconnected pores.With large adsorbing capacity, vitrain mainly has semi-open pores, and durain mainly has interconnected ones. (2) Depressurization turbulence leads to water vaporization.Heat release from the adsorption of H₂O leads to the desorption of CH₄.The nature of depressurization desorption is competitive adsorption, manifesting as replacement desorption. (3) The mass transfer process of CBM is a cavitation process of CH₄ gas nucleus with low solubility. The water adsorption of coal, equilibrium water experiments and the results of CT scanning all basically verify the understanding of the mass transfer process of CBM production.The research results supplement the issue of energy source of adsorption.