scholarly journals Mechanisms, Growth Rates, and Morphologies of Gas Hydrates of Carbon Dioxide, Methane, and Their Mixtures

Methane ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 2-23
Author(s):  
Camilo Martinez ◽  
Juan F. Sandoval ◽  
Nathalia Ortiz ◽  
Sebastian Ovalle ◽  
Juan G. Beltran
Keyword(s):  
Carbon Dioxide ◽  
Crystal Growth ◽  
Growth Mechanism ◽  
Gas Hydrates ◽  
Growth Rates ◽  
Driving Forces ◽  
Interesting Phenomenon ◽  
Euhedral Crystal ◽  
Partial Dissociation ◽  
Methane Carbon

Mechanisms of growth and dissociation, growth rates, and morphology of gas hydrates of methane, carbon dioxide, and two CH4:CO2 mixtures (80:20 and 30:70 nominal concentration) were studied using using high resolution images and very precise temperature control. Subcooling and a recently proposed mass transfer-based driving force were used to analyze the results. When crystal growth rates did not exceed 0.01 mm/s, all systems showed faceted, euhedral crystal habits at low driving forces. At higher driving forces and growth rates, morphologies were different for all systems. These results solve apparent contradictions in literature about the morphology of hydrates of methane, carbon dioxide, and their mixtures. Differences in the growth mechanism of methane-rich and carbon dioxide-rich hydrates were elucidated. It was also shown that hydrate growth of methane, carbon dioxide, and their mixtures proceed via partial dissociation of the growing crystal. Temperature gradients were used to dissociate hydrates at specific locations, which revealed a most interesting phenomenon: On dissociation, carbon dioxide-rich hydrates propagated onto the bare substrate while drawing water from the opposite side of the sample. Furthermore, it was shown that an abrupt change in morphology common to all systems could be correlated to a change in the slope of growth rate data. This change in morphology was explained by a shift in the crystal growth mechanism.

scholarly journals Crystal growth of clathrate hydrates formed with methane + carbon dioxide mixed gas at the gas/liquid interface and in liquid water

2015 ◽  
Vol 39 (11) ◽  
pp. 8254-8262 ◽  
Author(s):  
Hiroki Ueno ◽  
Hotaka Akiba ◽  
Satoru Akatsu ◽  
Ryo Ohmura
Keyword(s):  
Carbon Dioxide ◽  
Crystal Growth ◽  
Liquid Water ◽  
Liquid Interface ◽  
Clathrate Hydrates ◽  
Mixed Gas ◽  
Hydrate Crystal ◽  
Methane Carbon

Observations of CH4 + CO2 hydrate crystal growth formed at the gas/liquid interface and in liquid water were made.

scholarly journals Mathematical modeling of the equilibrium complete replacement of methane by carbon dioxide in a gas hydrate reservoir at negative temperatures

2020 ◽  
Vol 6 (2) ◽  
pp. 63-80
Author(s):  
Stanislav L. Borodin ◽  
Denis S. Belskikh
Keyword(s):  
Carbon Dioxide ◽  
Mathematical Model ◽  
Gas Hydrates ◽  
Hydrate Formation ◽  
Complete Replacement ◽  
Hydrate Reservoir ◽  
Negative Temperatures ◽  
Gas Hydrate Reservoir ◽  
Promising Source ◽  
Methane Carbon

Gas hydrates, which contain the largest amount of methane on our planet, are a promising source of natural gas after the depletion of traditional gas fields, the reserves of which are estimated to last about 50 years. Therefore, it is necessary to study the methods for extracting gas from gas hydrates in order to select the best of them and make reasoned technological and engineering decisions in the future. One of these methods is the replacement of methane in its hydrate with carbon dioxide. This work studies the construction of a mathematical model to observe this method. The following process is considered in this article: on one side of a porous reservoir, initially saturated with methane and its hydrate, carbon dioxide is injected; on the opposite side of this reservoir, methane and/or carbon dioxide are extracted. In this case, both the decomposition of methane hydrate and the formation of carbon dioxide hydrate can occur. This problem is stated in a one-dimensional linear formulation for the case of negative temperatures and gaseous carbon dioxide, which means that methane, carbon dioxide, ice, methane, and carbon dioxide hydrates may be present in the reservoir. A mathematical model is built based on the following: the laws of conservation of masses of methane, carbon dioxide, and ice; Darcy’s law for the gas phase motion; equation of state of real gas; energy equation taking into account thermal conductivity, convection, adiabatic cooling, the Joule — Thomson effect, and the release or absorption of latent heat of hydrate formation. The modelling assumes that phase transitions occur in an equilibrium mode and that methane can be completely replaced by carbon dioxide. The results of numerical experiments are presented.

Effect of pressure on methane recovery from natural gas hydrates by methane-carbon dioxide replacement

2018 ◽  
Vol 217 ◽  
pp. 527-536 ◽  
Author(s):  
Chun-Gang Xu ◽  
Jing Cai ◽  
Yi-Song Yu ◽  
Ke-Feng Yan ◽  
Xiao-Sen Li
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Gas Hydrates ◽  
Methane Recovery ◽  
Effect Of Pressure ◽  
Natural Gas Hydrates ◽  
Methane Carbon

Montmorillonite Dendrites

1974 ◽  
Vol 32 ◽  
pp. 454-455
Author(s):  
Necip Güven ◽  
Rodney W. Pease
Keyword(s):  
Crystal Growth ◽  
Growth Mechanism ◽  
Growth Front ◽  
Morphological Features ◽  
Dendritic Crystal ◽  
Crystal Growth Mechanism

Morphological features of montmorillonite aggregates in a large number of samples suggest that they may be formed by a dendritic crystal growth mechanism (i.e., tree-like growth by branching of a growth front).

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