The dual-functional roles of N2 gas for the exploitation of natural gas hydrates: An inhibitor for dissociation and an external guest for replacement

Mok, Junghoon; Choi, Wonjung; Seo, Yongwon

doi:10.1016/j.energy.2021.121054

Cited by 23 publications

(4 citation statements)

References 57 publications

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“…It was discovered that the addition of small gas molecules can improve CH 4 recovery and H 2 or N 2 did not occupy the hydrate cages according to the measured Raman spectra. The addition of H 2 molecules could optimize the replacement, which is in accordance with the three-dimensional experimental results, 92−94 and H 2 does not enter the hydrate cages, as reported by Ding et al 95 However, Mok et al 96 observed that the Raman peak at 2323 cm −1 corresponding to the N 2 hydrate appeared during the experiment. Besides the above method, by comparison of the change rate of the hydrate Raman peak intensity and the reduced rate of the A L /A S value versus time, Xie et al 97 reported a novel method for optimizing the CO 2 −CH 4 exchange process, which involved creating a porous CO 2 hydrate film using the multi-defective ice produced by dissociating CH 4 hydrate in the anomalous self-preservation area.…”

Section: Investigation Of Hydrate Formation or Decompositionsupporting

confidence: 86%

Mini Review on Application and Outlook of In Situ Raman Spectrometry in Gas Hydrate Research

et al. 2022

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Natural gas hydrates have drawn much attention as a result of their considerable reserves, clean energy, and global distribution. Some new technologies, such as energy storage and transportation, gas separation, and desalination, have been developed via forming hydrates. The structure, composition, and cage occupancy of gas hydrates and kinetics of hydrate formation and dissociation are crucial in flow assurance and the applications mentioned above. In view of its dependable, efficient, and non-destructive features, in situ Raman spectroscopy is a typical and popular measuring technique in gas hydrates. In this mini review, the application and microscopic characterization using in situ Raman spectroscopy in the gas hydrate field were reviewed, including how to use Raman spectroscopy to identify the structure and molar composition of hydrate and how to offer in situ information on the kinetics of formation, decomposition, replacement, and molecular diffusion at the molecular level. The challenges and perspectives on future studies of in situ Raman spectrometry have been proposed.

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Section: Investigation Of Hydrate Formation or Decompositionsupporting

confidence: 86%

Mini Review on Application and Outlook of In Situ Raman Spectrometry in Gas Hydrate Research

et al. 2022

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“…Panter et al also investigated the NGH dissociation behavior inside a blocked pipeline during N 2 gas injection and they found that the continuous injection of gaseous N 2 as a thermodynamic inhibitor into structure I/structure II hydrates resulted in NGH crush through channel formation, unlike the radial dissociation observed in the depressurization method (Panter et al, 2011). The experimental results indicated the synthesis effects of N 2 as both an inhibitor to dissociate the NGHs and an external medium to replace the CH 4 molecules in the NGH cages (Mok et al, 2021). The above discussion, thus, shows that the thermochemical reaction system in this study is also feasible in the exploitation of the NGHs from the perspective of nitrogen inhibition and replacement.…”

Section: Discussionmentioning

confidence: 99%

A Thermal Chemical Reaction System for Natural Gas Hydrates Exploitation

Wang

Sun

et al. 2022

Front. Energy Res.

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The methodology of using CO2 to replace CH4 to recover the natural gas hydrates (NGHs) is supposed to avoid geological disasters. However, the reaction path of the CH4–CO2 replacement method is too complex to give satisfactory replacement efficiency. Therefore, this study proposed a thermochemical reaction system that used the heat and the nitrogen released by the thermochemical reactions to recover NGHs. The performance of the thermochemical reaction system (NaNO2 and NH4Cl) regarding heat generation and gas production under low temperature (4°C) conditions was evaluated, and the feasibility of exploiting NGHs with an optimized formula of the thermochemical reaction system was also evaluated in this study. First, the effects of three catalysts (HCl, H₃PO₄, and NH2SO3H) were investigated at the same reactant concentration and catalyst concentration. It was confirmed that HCl as a catalyst can obtain better heat generation and gas production. Second, the effect of HCl concentration on the reaction was investigated under the same reactant concentration. The results showed that the higher the HCl concentration, the faster is the reaction rate. When the concentration of HCl was greater than 14 wt%, side reactions would occur to produce toxic gas; hence, 14 wt% was the optimal catalyst concentration for the reaction of NaNO2 and NH4Cl at low temperatures. Third, the heat generation and gas production of the thermochemical reaction systems were evaluated at different reactant concentrations (1, 2, 3, 4, 5, and 6 mol/L) at 14 wt% HCl concentration. It was found that the best reactant concentration was 5 mol/L. Finally, the feasibility of exploiting NGHs with the optimal system was analyzed from the perspectives of thermal decomposition and nitrogen replacement. The thermochemical reaction system provided by this study is possible to be applied to explore NGHs’ offshore.

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“…Methane hydrate is an ice-like solid crystalline compound formed by methane gas and water at extreme conditions of low temperatures and high pressures. − Many countries and regions have directly observed or indirectly inferred the existence of hydrate resources in permafrost and marine settings. , Because of the advantages of large reserves, high energy density, and clean combustion, methane hydrate is expected to alleviate the tight energy demand worldwide. − Methane hydrate exploitation refers to the process of decomposing solid hydrate into methane and water by destroying hydrate phase equilibrium conditions . Based on this, several common basic methods including depressurization, − thermal stimulation, inhibitor injection, gas replacement, , physical methods, , and a combination of the above methods have been proposed.…”

Section: Introductionmentioning

confidence: 99%

“…6−8 Methane hydrate exploitation refers to the process of decomposing solid hydrate into methane and water by destroying hydrate phase equilibrium conditions. 9 Based on this, several common basic methods including depressurization, 10−12 thermal stimulation, 13 inhibitor injection, 14 gas replacement, 15,16 physical methods, 17,18 and a combination of the above methods 19 have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Decomposition Characteristics of Methane Hydrate for the Pressure Regulation of Production Processes

et al. 2023

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Methane hydrate is a promising energy source to alleviate the tight energy demand worldwide. The pressure regulation during the production process of hydrate deposits by the economical depressurization method still lacks experimental simulations. In this study, four targeted production pressures (2.3, 2.5, 2.7, and 2.9 MPa) with three rated gas production fluxes (0.18, 0.30, and 0.58 L s /min) were employed to investigate the methane hydrate decomposition during the pressure regulation process. The increase in gas flux is positive for both the depressurization and hydrate decomposition rates. A stationary state in non-equilibrium thermodynamics is obviously and universally observed in all cases when the deposit pressure−temperature is in a synergistic relationship and the decomposition rate of hydrates is time-invariant. Before the stationary state, a dynamic competition between pressure drop and hydrate decomposition under a rated gas flux is found. During the stationary state, the decomposition rate is linearly related to the corresponding depressurization rate under different rated gas fluxes, revealing the improvement of pressure drop (rather than pressure itself) on hydrate decomposition by enlarging the driving force. Hence, the optimal production process of hydrates should be based on dynamic depressurization considering the rated gas flux of production pipelines. The findings provide direct guidance for the pressure regulation method of hydrate production.

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The dual-functional roles of N2 gas for the exploitation of natural gas hydrates: An inhibitor for dissociation and an external guest for replacement

Cited by 23 publications

References 57 publications

Mini Review on Application and Outlook of In Situ Raman Spectrometry in Gas Hydrate Research

Mini Review on Application and Outlook of In Situ Raman Spectrometry in Gas Hydrate Research

A Thermal Chemical Reaction System for Natural Gas Hydrates Exploitation

Experimental Study on the Decomposition Characteristics of Methane Hydrate for the Pressure Regulation of Production Processes

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