Keywords: coal mining, methane separation, memory effect, thermodynamics, kinetics, hydrate formation, methane–in–water systems, gas hydrate nucleation
Memory effect on hydrate formation and influential factors of its sustainability in new hydrate–based coal mine methane separation method
This paper describes an experimental study on the memory effect in a methane–in–water system in which a hydrate was once formed and then dissociated. The 'memory effect' is found to be associated with gas hydrate nucleation. This study aims to investigate how memory effect in the hydrate nucleation process depends on the thermal and kinetic history (i.e., the nucleation pressure and temperature, induction time). The preceding hydrate dissociation proceeds after hydrate formation for every run, and thereby testing the nature of the 'memory effect'. In this study, the memory effect on the thermodynamics and induction time was evaluated. Additionally, the influences of the dissociation temperature, agitation type, and depressurisation on the memory effect sustainability are discussed. We may deduce that the memory effect leads to the reduction in induction time for repetitive hydrate formations from solutions. It also allows easier hydrate re–formation in terms of higher nucleation temperature. The present study provides references for the application of memory effect in hydrate–based technology and sustainability conditions of memory effect. This will contribute to CMM utilisation and to benefit for local and global environment.