Effect of Gas Composition on sII Hydrate Growth Kinetics

Abay, Hailu K.; Svartaas, Thor M.; Ke, Wei

doi:10.1021/ef101698g

Cited by 20 publications

(16 citation statements)

References 28 publications

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“…The literature regarding this differs significantly. Abay et al 10 report that the growth kinetics of sII gas hydrates are dependent on the hydrate formed and not on the additives. This is in accordance with other authors who found the growth rate not to be or only slightly influenced by the addition of salt.…”

Section: Resultsmentioning

confidence: 99%

“…This is in accordance with the work of Moeini 9 et al who also found the overall gas uptake for CO 2 gas hydrates highly influenced by dissolved NaCl. On the other hand, Abay et al, 10 who studied the formation of different synthetic natural gases, state that the kinetics of hydrate formation are not influenced by additives but only depend on the gas species. This is consistent with the work of Farhang et al, 11 who found the growth rate of CO 2 gas hydrates with the addition of different sodium halides only slightly influenced.…”

Section: Introductionmentioning

confidence: 99%

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Raman Spectroscopic Study of the Effect of Aqueous Salt Solutions on the Inhibition of Carbon Dioxide Gas Hydrates

Holzammer

Braeuer

2019

J. Phys. Chem. B

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We present an experimental Raman study on the thermodynamic inhibition effect of different salts (NaCl, KCl, MgCl2, and CaCl2 from 2.5 to 11 wt %) on the formation of carbon dioxide gas hydrates. We performed the experiments in a high-pressure vessel with two phases: a water-rich phase and a CO2-rich phase. We investigated the changes the inhibitors induce in the water-rich phase before the onset of hydrate formation. This includes a study of the change in molar reaction enthalpy between strongly and weakly hydrogen-bonded water and the decrease in solubility of carbon dioxide in water. Additionally, the growth mechanisms of carbon dioxide hydrates were investigated by determining the amount of solid hydrates formed and the reaction constant. The results show that the molar reaction enthalpy, the solubility of CO2, and the amount of solid hydrates formed can be correlated with the effective mole fraction, whereas the reaction constant is not affected by the addition of salts. The decrease of the molar reaction enthalpy can be directly correlated with the equilibrium temperature of the gas hydrates.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Raman Spectroscopic Study of the Effect of Aqueous Salt Solutions on the Inhibition of Carbon Dioxide Gas Hydrates

Holzammer

Braeuer

2019

J. Phys. Chem. B

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“…Their comparison of the results for methane and natural gas seems to also suggest that, at constant subcooling, the gas composition has no effect on the hydrate growth rate. However, this needs to be further investigated, because work by Abay et al [99] with two different synthetic natural gas compositions showed that the composition had an effect on the hydrate growth rate, with the seven-component synthetic natural gas having a growth rate double that of the two-component synthetic natural gas. Figure 12.…”

Section: Effect Of Experimental Temperature and Subcoolingmentioning

confidence: 99%

Gas Hydrate Growth Kinetics: A Parametric Study

Meindinyo

Svartaas

2016

Energies

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Gas hydrate growth kinetics was studied at a pressure of 90 bars to investigate the effect of temperature, initial water content, stirring rate, and reactor size in stirred semi-batch autoclave reactors. The mixing energy during hydrate growth was estimated by logging the power consumed. The theoretical model by Garcia-Ochoa and Gomez for estimation of the mass transfer parameters in stirred tanks has been used to evaluate the dispersion parameters of the system. The mean bubble size, impeller power input per unit volume, and impeller Reynold's number/tip velocity were used for analyzing observed trends from the gas hydrate growth data. The growth behavior was analyzed based on the gas consumption and the growth rate per unit initial water content. The results showed that the growth rate strongly depended on the flow pattern in the cell, the gas-liquid mass transfer characteristics, and the mixing efficiency from stirring. Scale-up effects indicate that maintaining the growth rate per unit volume of reactants upon scale-up with geometric similarity does not depend only on gas dispersion in the liquid phase but may rather be a function of the specific thermal conductance, and heat and mass transfer limitations created by the limit to the degree of the liquid phase dispersion is batched and semi-batched stirred tank reactors.

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“…The growth rate of CO 2 hydrate first increased toward a maximum value after hydrate onset and then decreased toward zero at the end of experiment. This consistency in growth pattern is compatible with the fact mentioned by Abay et al (2011) that the overall pattern of hydrate growth is a fingerprint of the effect of gas hydrate former rather than additives. In the system with pure water, the amount of hydrate formed is very small.…”

Section: Induction Timesupporting

confidence: 88%

Kinetics of the formation of CO2 hydrates in the presence of sodium halides and hydrophobic fumed silica nanoparticles

Farhang¹

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CO 2 capture by trapping the greenhouse gas in clathrates hydrates is proving to be one of the promising options for long term carbon storage. This technology is desirable as it can be deposited in the deep ocean where the suitable pressure and temperature is ready without any extra cost. To date, this method has mostly been of academic interest because the formation of gas hydrates is very slow and requires lots of energy and resources. It is important therefore to develop an efficient and economical process to be able to apply this method at an industrial scale. Scientists and researchers have been looking for suitable additives to accelerate the formation of CO 2 hydrate. To meet these objectives numerous additives have previously been tested and several were found to be suitable hydrate promoters. The mechanism for the formation of gas hydrates in the presence of additives is not clear yet. Understanding this mechanism would help us to select and synthesise the most suitable and cost effective additive.In this thesis, two groups of chemicals i.e. salt and hydrophobic particles were added to the hydrate formation reactor and examined. Initially sodium halides were tested for their effect on the kinetics of the formation of CO 2 hydrates in an isochoric system. The effect of different anion types and concentrations was investigated by directly measuring pressure and temperature changes in the reactor and evaluating maximum CO 2 uptake, conversion, storage capacity, induction time, and hydrate growth rate. The results indicated that sodium halides at a concentration of 50 mM (mmol/L) increase CO 2 consumption and conversion to hydrates. In addition, sodium iodide and sodium bromide in a range of concentrations between 50 and 250 mM significantly increased the hydrate formation kinetics. Measurements of the surface potential of CO 2 hydrates formed in the presence of sodium halides showed negative charge on hydrates with the highest zeta potential observed at the concentration of 50 mM. The findings of this part of the research led us to propose a mechanism for the formation of CO 2 hydrates in the presence of sodium halides.The second group of additives extensively investigated in the current research were hydrophobic nano-particles. Two types of hydrophobic fumed silica were studied.iii They produced two types of particle stabilised systems when mixed with water (i.e. silica foam and dry water). The influence of particle hydrophobicity and concentration on hydrate formation kinetics was established by monitoring gas consumption, CO 2 conversion and induction time. The morphology, microstructure, and pore characteristics were elucidated by cryogenic scanning electron microscopy (cryo-SEM), and the elemental distribution and composition were determined by X-ray energy dispersive spectroscopy (EDS). The results indicated that the promoting effect of hydrophobic fumed silica was dependent on the particle hydrophobicity and on the weight ratio of silica to water. The kinetics of CO 2 hydrate formation were ...

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Effect of Gas Composition on sII Hydrate Growth Kinetics

Cited by 20 publications

References 28 publications

Raman Spectroscopic Study of the Effect of Aqueous Salt Solutions on the Inhibition of Carbon Dioxide Gas Hydrates

Raman Spectroscopic Study of the Effect of Aqueous Salt Solutions on the Inhibition of Carbon Dioxide Gas Hydrates

Gas Hydrate Growth Kinetics: A Parametric Study

Kinetics of the formation of CO2 hydrates in the presence of sodium halides and hydrophobic fumed silica nanoparticles

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