Measurements of methane hydrate heat of dissociation using high pressure differential scanning calorimetry

Gupta, Arvind; Lachance, Jason W.; Sloan, E. Dendy; Koh, Carolyn A.

doi:10.1016/j.ces.2008.09.002

Cited by 171 publications

(114 citation statements)

References 19 publications

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“…Consequently, the dissociation enthalpy of CH 4 -CO 2 mixed hydrate can be reasonably determined by using the Clausius-Clapeyron prediction method, because the PT data measured in this study during thermal dissociation are within a range of low pressure (less than 3.4 MPa). Moreover, it was recently found that the dissociation enthalpy of pure CH 4 hydrate, either predicted by using the Clapeyron equation (e.g., Anderson 19 ) or measured by using a differential scanning calorimeter (e.g., Gupta et al 24 ), remains constant over the three-phase co-existence region. Thus, the calculated results are presumed to be applicable over the conditions investigated here.…”

Section: 24mentioning

confidence: 99%

“…(1) was identified with these restrictions: (a) the gas composition and the fractional quantity of the guest molecules occupied in the hydrate cavities should not change appreciably, and (b) the condensed phase volume changes (solid to liquid in this case) should be negligible relative to the gas volume. In particular, Gupta et al 24 argues for limiting the use of the Clausius-Clapeyron equation under high pressure (e.g., higher than 4 MPa). The Clapeyron equation is also known to be limited in that it is difficult to apply to multicomponent gas hydrate systems.…”

Section: Dissociation Enthalpies Of Methane-carbon Dioxide Mixed Hydrmentioning

confidence: 99%

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Thermal Dissociation Behavior and Dissociation Enthalpies of Methane–Carbon Dioxide Mixed Hydrates

2011

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Replacement of methane with carbon dioxide in hydrate has been proposed as a strategy for geologic sequestration of carbon dioxide (CO 2 ) and/or production of methane (CH 4 ) from natural hydrate deposits. This replacement strategy requires a better understanding of the thermodynamic characteristics of binary mixtures of CH 4 and CO 2 hydrate (CH 4 -CO 2 mixed hydrates), as well as thermophysical property changes during gas exchange. This study explores the thermal dissociation behavior and dissociation enthalpies of CH 4 -CO 2 mixed hydrates. We prepared CH 4 -CO 2 mixed hydrate samples from two different, well-defined gas mixtures. During thermal dissociation of a CH 4 -CO 2 mixed hydrate sample, gas samples from the head space were periodically collected and analyzed using gas chromatography. The changes in CH 4 -CO 2 compositions in both the vapor phase and hydrate phase during dissociation were estimated based on the gas chromatography measurements. It was found that the CO 2 concentration in the vapor phase became richer during dissociation because the initial hydrate composition contained relatively more CO 2 than the vapor phase. The composition change in the vapor phase during hydrate dissociation affected the dissociation pressure and temperature-the richer CO 2 in the vapor phase led to lower dissociation pressure. Furthermore, the increase in CO 2 concentration in the vapor phase enriched the hydrate in CO 2 . The dissociation enthalpy of the CH 4 -CO 2 mixed hydrate was computed by fitting the Clausius-Clapeyron equation to the pressure-temperature (PT) trace of a dissociation test. It was observed that the dissociation enthalpy of the CH 4 -CO 2 mixed hydrate lay between the limiting values of pure CH 4 hydrate and CO 2 hydrate, increasing with the CO 2 fraction in the hydrate phase.3

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Section: 24mentioning

confidence: 99%

Section: Dissociation Enthalpies Of Methane-carbon Dioxide Mixed Hydrmentioning

confidence: 99%

Thermal Dissociation Behavior and Dissociation Enthalpies of Methane–Carbon Dioxide Mixed Hydrates

2011

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“…5͒ and 54.4Ϯ 1.4 kJ/ mol of gas ͑hydrate→ liquid+ gas͒ at 292 K over a range of pressures up to 20 MPa. 6 Macroscopic models of hydrate decomposition in reservoirs 3,4 often start with an assumption of intrinsic reaction kinetics. The intrinsic reaction kinetics mechanism [7][8][9][10] for methane hydrate decomposition assumes that, at constant temperature, the hydrate decomposition rate, −dn H / dt,i s proportional to the gradient in methane gas fugacity ͑concen-tration or pressure͒ between the solid methane hydrate phase, f hydrate , and the nonequilibrium water-methane mixture at the interface, f interface ,…”

Section: Introductionmentioning

confidence: 99%

Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition

Alavi

Ripmeester

2010

The Journal of Chemical Physics

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Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

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“…The values that we used for the different material properties [11,12] By turning the heater off, the temperature of the heater is maintained at a temperature below a selected maximum temperature (Tmax = 200 °C) in order to avoid temperatures that would vaporize the water produced from the MH dissociation. Thus the only gas produced is the methane.…”

Section: Temperature Distribution In the Mh Depositsmentioning

confidence: 99%

Energy Return on Energy Invested (EROI) for the Electrical Heating of Methane Hydrate Reservoirs

Callarotti

2011

Sustainability

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Abstract： We model the low frequency electrical heating of submarine methane hydrate deposits located at depths between 1000 and 1500 m, and determine the energy return on energy invested (EROI) for this process. By means of the enthalpy method, we calculate the time-dependent heating of these deposits under applied electrical power supplied to a cylindrical heater located at the center of the reservoir and at variable depths. The conversion of the produced water to steam is avoided by limiting the heater temperature. We calculate the volume of methane hydrate that will melt and the energy equivalent of the gas thus generated. The partial energy efficiency of this heating process is obtained as the ratio of the gas equivalent energy to the applied electrical energy. We obtain EROI values in the range of 4 to 5, depending on the location of the heater. If the methane gas is used to generate the electrical energy required in the heating (in processes with a 33% efficiency), the effective EROI of the process falls in the range of 4/3 to 5/3.

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Measurements of methane hydrate heat of dissociation using high pressure differential scanning calorimetry

Cited by 171 publications

References 19 publications

Thermal Dissociation Behavior and Dissociation Enthalpies of Methane–Carbon Dioxide Mixed Hydrates

Thermal Dissociation Behavior and Dissociation Enthalpies of Methane–Carbon Dioxide Mixed Hydrates

Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition

Energy Return on Energy Invested (EROI) for the Electrical Heating of Methane Hydrate Reservoirs

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