The influence of porosity and structural parameters on different kinds of gas hydrate dissociation

Abstract

Methane hydrate dissociation at negative temperatures was studied experimentally for different artificial and natural samples, differing by macro- and micro-structural parameters. Four characteristic dissociation types are discussed in the paper. The internal kinetics of artificial granule gas hydrates and clathrate hydrates in coal is dependent on the porosity, defectiveness and gas filtration rate. The density of pores distribution in the crust of formed ice decreases by the several orders of magnitude and this change significantly the rate of decay. Existing models for describing dissociation at negative temperatures do not take into account the structural parameters of samples. The dissociation is regulated by internal physical processes that must be considered in the simulation. Non-isothermal dissociation with constant external heat flux was simulated numerically. The dissociation is simulated with consideration of heat and mass transfer, kinetics of phase transformation and gas filtering through a porous medium of granules for the negative temperatures. It is shown that the gas hydrate dissociation in the presence of mainly microporous structures is fundamentally different from the disintegration of gas hydrates containing meso and macropores.

Methane Hydrate in Confined Spaces: An Alternative Storage System

“…When methane hydrate dissociation is simulated it is important to differentiate between the dimensions of a granule, a compressed pellet, a sedimentary rock or MH inside a porous media. In latter, microporous structures behave fundamentally different than meso‐ and macroporous structures . Heat transfer, the kinetics of phase transformation, gas filtering effects through the porous media, the pore size and the restricted molecular diffusion have to be taken into account.…”

Different Mechanism Effect between Gas-Solid and Liquid-Solid Interface on the Three-Phase Coexistence Hydrate System Dissociation in Seawater: A Molecular Dynamics Simulation Study

“…Energies 2018, 11,6 4 of 17 simulation work, the temperature range of 243 K-263 K is higher than the melting point of both Ice Ih and hydrate at 30 MPa. The total simulation process comprises of three steps: At the beginning, the initial model system was optimized by both steepest descent and conjugate gradient, and then a 100 ps MD simulation was used with immobilized hydrate slab to release the extra tension at the interface between hydrate and adjacent phases.…”

“…The availability of methane in hydrates makes hydrates a key future energetic resource, whose exploitation represents a technical challenge. Studies that were conducted earlier by other researchers aimed in establishing efficient ways for exploration of gas hydrates [1][2][3][4] with a broad range of laboratory experiments [5][6][7][8][9][10][11][12][13][14] and field scale simulations [15][16][17][18]. However, the microscopic mechanism study of hydrate dissociation and its production process faces a great limitation with the available conventional methods.…”

New hydrate formation methods in a liquid-gas medium

“…The most important of them are the studies of a gas-hydrate structure, its physicochemical, thermophysical, mechanical and other properties, the general conditions needed for their formation and their growth mechanisms202122232425262728. Great attention is paid to the methods of studying both natural and man-made gas hydrates293031323334353637. A lot of contributions are dedicated to the enhancement of the hydrate formation process.…”