Carbon Dioxide Gas Hydrate Research Articles

Experimental investigation of carbon dioxide hydrate formation in a colloidal solution of H2O+ SDS + SiO2 at a constant SiO2 concentration of 300 ppm

The paper presents a experimental investigation of carbon dioxide hydrate formation in a colloidal solution of H2O+ SDS + SiO2 The influence of the kinetic promoter of sodium dodecyl sulfate (SDS) on the formation of carbon dioxide gas hydrate at various concentrations: 0, 100, 300, 500 ppm was assessed. The SiO2 concentration in the solution was constant and equal to 300 ppm. The change in solution temperature and pressure during the production of hydrate is shown for each SDS concentration. The values of convection of solution and gas into the gas hydrate state were determined.

Accurate description of gas hydrates of carbon dioxide and hydrogen for storage and transportation

This paper reports theoretical study of stability zones and composition of “H2 + CO2” clathrate hydrates of cubic structure I (sI) and II (sII) in dependence on pressure and temperature for different gas phase composition using extended van der Waals and Platteeuw statistical thermodynamic model. It was found that rising of CO2 content in H2 + CO2 gas mixture phase makes formation of sI hydrate more thermodynamically preferable rather than sII hydrate, and in the same time CO2 content increasing reduces formation pressure of the resulting hydrate. Observed difference between gas phase composition and gas molecules trapped in hydrate phase allows to consider these hydrates as a gas separation medium. We believe that presented results could be applicable for improvements of hydrate technology for CO2 utilization as a greenhouse gas, and hydrogen obtained from natural gas refinement transportation.

Gas Hydrates: Applications and Advantages

Gas hydrates are promising components for a wide range of industries and the national economy. This paper outlines the gas hydrate application areas with the greatest potential. Gas hydrates of methane, ethane, propane, carbon dioxide and freon were investigated. Double gas hydrates were found to be coming into use. Natural and artificial hydrates are now being exploited. The main properties and component composition of hydrates, as well as their extraction methods are described. The key aspects of using hydrates in the energy industry, gas chemistry and petrochemistry, heat exchange systems and fire safety management are highlighted. These specific aspects were identified by analyzing the known experimental findings, results of mathematical modeling, bench and field tests, as well as trial runs of industrial systems. The recent advances in science and technology in this field were analyzed. The range of tasks that need to be tackled to improve the efficiency of using gas hydrates are defined.

Kinetics of the Formation of Methane and Carbon Dioxide Gas Hydrates in the Presence of Tetrahydrofuran and Sodium Lauryl Sulfate Promoters

Kinetics of the Formation of Methane and Carbon Dioxide Gas Hydrates in the Presence of Tetrahydrofuran and Sodium Lauryl Sulfate Promoters

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

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.

Application of Gaussian Process Regression (GPR) in Gas Hydrate Mitigation

The production of oil and natural gas contributes to a significant amount of revenue generation in Malaysia thereby strengthening the country’s economy. The flow assurance industry is faced with impediments during smooth operation of the transmission pipeline in which gas hydrate formation is the most important. It affects the normal operation of the pipeline by plugging it. Under high pressure and low temperature conditions, gas hydrate is a crystalline structure consisting of a network of hydrogen bonds between host molecules of water and guest molecules of the incoming gases. Industry uses different types of chemical inhibitors in pipeline to suppress hydrate formation. To overcome this problem, machine learning algorithm has been introduced as part of risk management strategies. The objective of this paper is to utilize Machine Learning (ML) model which is Gaussian Process Regression (GPR). GPR is a new approach being applied to mitigate the growth of gas hydrate. The input parameters used are concentration and pressure of Carbon Dioxide (CO2) and Methane (CH4) gas hydrates whereas the output parameter is the Average Depression Temperature (ADT). The values for the parameter are taken from available data sets that enable GPR to predict the results accurately in terms of Coefficient of Determination, R2 and Mean Squared Error, MSE. The outcome from the research showed that GPR model provided with highest R2 value for training and testing data of 97.25% and 96.71%, respectively. MSE value for GPR was also found to be lowest for training and testing data of 0.019 and 0.023, respectively.

Kinetic analysis of CO2 hydrate formation by the use of different impellers

This study investigates the effects of types of impellers with the use of full baffle in carbon dioxide gas hydrate formation. In single impeller experiments initial hydrate formation rate is higher with the use of rushton turbine showing the better interaction between gas and liquid in radial flow due to better pumping capacity and good shear field among pitched blade turbine, triangle turbine and marine propeller, with value 298 × 10–8 mol/s. In dual impeller experiments mixed flow experiments and more specifically triangle turbine show higher values in rate of hydrate formation with maximum value 370 × 10–8 mol/s. In both single and dual impeller experiments, RT experiments formed gas hydrates for fewer periods than any other impeller type due to high amount of generated heat. Furthermore, in both single and dual impeller experiments the PBTD experiment consumes more energy compared to any other of the five experiments.

Carbon dioxide hydrate in a microfluidic device: Phase boundary and crystallization kinetics measurements with micro-Raman spectroscopy.

Various emerging carbon capture technologies depend on being able to reliably and consistently grow carbon dioxide hydrate, particularly in packed media. However, there are limited kinetic data for carbon dioxide hydrates at this length scale. In this work, carbon dioxide hydrate propagation rates and conversion were evaluated in a high pressure silicon microfluidic device. The carbon dioxide phase boundary was first measured in the microfluidic device, which showed little deviation from bulk predictions. Additionally, measuring the phase boundary takes on the order of hours compared to weeks or longer for larger scale experimental setups. Next, propagation rates of carbon dioxide hydrate were measured in the channels at low subcoolings (<2 K from phase boundary) and moderate pressures (200-500 psi). Growth was dominated by mass transfer limitations until a critical pressure was reached, and reaction kinetics limited growth upon further increases in pressure. Additionally, hydrate conversion was estimated from Raman spectroscopy in the microfluidics channels. A maximum value of 47% conversion was reached within 1 h of a constant flow experiment, nearly 4% of the time required for similar results in a large scale system. The rapid reaction times and high throughput allowed by high pressure microfluidics provide a new way for carbon dioxide gas hydrate to be characterized.

Influence of the Model Stratum Water Mineralization on the Process of Carbon Dioxide and Natural Gas Hydrates Formation

The paper presents the results of an experimental study of the natural gas and carbon dioxide hydrates formation in a calcium chloride solution. It was found that the gas saturation of hydrates formed from natural gas and carbon dioxide in 15 mass. % calcium chloride solution, 3 and 4 times less, respectively, of the gas saturation of hydrates obtained in distilled water. The rate of gas hydrates formation in a calcium chloride solution is slightly higher than this one in distilled water.

A new hybrid desalination method based on the CO2 gas hydrate and capacitive deionization processes

In this study, a hybrid desalination process based on carbon dioxide gas hydrate and capacitive deionization (CDI) is proposed to improve desalination performance. In this method, the formed gas hydrate crystals are dissociated and the produced water is conducted to the CDI process. To overcome the separation problem of the residual brine between hydrate crystals, a reactor that can be capable of compressing crystals was designed. Also, to improve the efficiency of the CDI process, electrodes were synthesized based on the activated carbon and their chemical properties modified using nitric acid. The performance of the gas hydrate, CDI, and hybrid desalination method examined for single and multi-salt aqueous solutions containing sodium, potassium, calcium, and magnesium with different concentrations. Also, the effects of the hydrate formation temperature, applied voltage, ion type and concentration on the ions removal efficiency have been investigated. The results showed that the compression of hydrate crystals in the hydrate desalination process, and using the modified activated carbon electrode in the CDI process could significantly improve the ions removal efficiency. The results showed that the proposed method could remove around 82% of Na+ and 100% of K+, Ca2+ and Mg2+ from saltwater with similar concentrations to seawater, respectively.

Assessing the Alkyl Chain Effect of Ammonium Hydroxides Ionic Liquids on the Kinetics of Pure Methane and Carbon Dioxide Hydrates

In this study, four ammonium hydroxide ionic liquids (AHILs) with varying alkyl chains were evaluated for their kinetic hydrate inhibition (KHI) impact on pure carbon dioxide (CO2) and methane (CH4) gas hydrate systems. The constant cooling technique was used to determine the induction time, the initial rate of hydrate formation, and the amount of gas uptake for CH4-AHILs and CO2-AHILs systems at 8.0 and 3.50 MPa, respectively, at 1 wt.% aqueous AHILs solutions. In addition, the effect of hydrate formation sub-cooling temperature on the performance of the AHILs was conducted at experimental temperatures 274.0 and 277.0 K. The tested AHILs kinetically inhibited both CH4 and CO2 hydrates at the studied sub-cooling temperatures by delaying the hydrate induction time and reducing the initial rate of hydrate formation and gas uptake. The hydrate inhibition performance of AHILs increases with increasing alkyl chain length, due to the better surface adsorption on the hydrate crystal surface with alkyl chain length enhancement. TPrAOH efficiently inhibited the induction time of both CH4 and CO2 hydrate with an average inhibition percentage of 50% and 84%, respectively. Tetramethylammonium Hydroxide (TMAOH) and Tetrabutylammonium Hydroxide (TBAOH) best reduced CH4 and CO2 total uptake on average, with TMAOH and Tetraethylammonium Hydroxide (TEAOH) suitably reducing the average initial rate of CH4 and CO2 hydrate formation, respectively. The findings in this study could provide a roadmap for the potential use of AHILs as KHI inhibitors, especially in offshore environs.

Investigating the effect of decompression rate on the synthesis of carbon dioxide gas hydrate by the method of explosive boiling of a liquefied hydrate gas

The article is part of a comprehensive study of the method by synthesis of gas hydrate based on the explosive boiling of liquefied hydrate-forming gas in a volume of water during decompression. Carbon dioxide is used as hydrate-forming gas. This article explores the effect of decompression rates on the amount of gas transferred to a gas hydrate at an initial gas temperature of 2 ° C.

Ways to improve the efficiency of carbon dioxide utilization and gas hydrate storage at low temperatures

The dissociation of gas hydrate in the form of pressed granules of different diameters has been investigated. Kinetic equations to describe dissociation of gas hydrates at negative temperatures have been obtained for the first time. The activation energy for CO2 hydrate is higher than for methane hydrate, and the intrinsic decomposition rate constant value, on the contrary, is almost 15 times lower for CO2 hydrate. The article proposes methods to improve the efficiency of gas hydrate storage and utilization of carbon dioxide. The pressed granules were obtained from gas hydrate particles of the same size (0.5 mm). The activation energy was found to be practically independent of the diameter of the pressed granules and the thickness of the powder layer, but to be determined by the minimum (“effective”) size of particles, forming the granules or a layer. The “effective” size refers to the diameter of uniform particles for which coalescence, pressing and any other packaging are excluded. It is shown for the first time that the value of the pre-exponential factor depends on the radius of the granule R (layer thickness h) if the radius (layer thickness h) exceeds the characteristic critical size Rcr (hcr). The Rcr value is determined by the thermal and diffusion resistance of the layer and is different for different gas hydrates.

ИНЖЕКЦИЯ ЖИДКОГО ДИОКСИДА УГЛЕРОДА В ПЛАСТ, НАСЫЩЕННЫЙ МЕТАНОМ И ЕГО ГАЗОГИДРАТОМ

Актуальность исследования связана с разработкой теоретических основ технологий добычи газа из газогидратных месторождений методом замещения. Рассматривается метод инжекции диоксида углерода, позволяющий значительно снизить энергетические затраты на разработку природных газогидратных залежей. Целью исследования является выяснение особенностей протекания процесса замещения метана диоксидом углерода в газогидрате при инжекции жидкого диоксида углерода в газогидратный пласт. Объект: пористый пласт конечной протяженности, насыщенный метаном и его газогидратом, исходные давление и температура которого соответствуют условиям стабильного существования газогидрата метана. Методы. На основе уравнений механики сплошной среды построена математическая модель тепломассопереноса в природном пласте, сопровождающаяся замещением метана на диоксид углерода в газогидрате. Принято, что в рассматриваемом случае в пласте возникают две характерные зоны, разделенные подвижной границей фазовых переходов. В первой (ближней) зоне поры насыщены жидкой двуокисью углерода и ее газогидратом, а во второй (дальней) зоне содержатся метан и его газогидрат. Результаты. Получены численные решения для полей давления и температуры при инжекции жидкого диоксида углерода в газогидратный пласт конечной протяженности. Построены зависимости температуры на границе замещения от давления инжекции и проницаемости пласта. Установлено, что при достаточно низких значениях давления инжекции и проницаемости величина температуры на границе замещения может подниматься выше равновесного значения температуры диссоциации газогидрата метана на газ и воду. Это соответствует возникновению второй подвижной межфазной границы, на которой происходит разложение газогидрата метана. Найдена зависимость предельной температуры закачиваемой жидкой двуокиси углерода, выше которой необходимо учитывать образование смеси метана и воды, от значений давления на правой и левой границах пласта и его проницаемости. Установлено, что режим с разложением газогидрата реализуется при высоких значениях давления на правой границе пласта и низких значениях проницаемости и давления, под которым закачивается двуокись углерода. Получены зависимости скорости границы замещения, а также времени полной замены газогидрата метана на газогидрат диоксида углерода во всем пласте от давления на правой и левой границах пласта, а также от его проницаемости.

Experimental study of carbon dioxide gas hydrate formation in the presence of zwitterionic compounds

In this work, the effect of a series of zwitterionic compounds (ZIs) aqueous solutions on the thermodynamic equilibrium and kinetic conditions of carbon dioxide hydrate formation is investigated. The hydrate dissociation conditions for (CO2 + ZI + water) systems are studied at different concentrations of ZI, viz. (0.10; 0.20, 0.30) mass fraction. The experiment was performed over a temperature range of T = (272–282) K and pressures range of p = (1.27–4.31 MPa) using a high pressure equilibrium cell. In this work the following ZIs: 4-(triethylammonio)butane-1-sulfonate [N222C4S], 4-(tributylammonio)-butane-1-sulfonate [N444C4S] and 4-(tributylphosphonio) butane-1-sulfonate [P444C4S] were investigated, therefore it was possible to determine the influence of alkyl chain length and the structure of the core atom on the kinetic behaviour of carbon dioxide gas hydrate formation. The results show that the gas hydrate phase equilibrium in the presence of zwitterionic compounds is shifted to higher pressures and lower temperatures so that the ZIs act slightly as a thermodynamic inhibitor of hydrate formation.

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

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.

Phase equilibrium for clathrate hydrates formed in the (methane, carbon dioxide or ethane) + water + ammonium chloride system

Methane hydrates are one of unconventional energy resources. There are vast depositions of methane hydrates on the sea floor and under permafrost. The methane hydrates are stable under high pressure and low temperature conditions. Depressurization method is being developed for methane gas production from deep sea methane hydrate layers. In this method, the methane hydrates are depressurized by a pump, and dissociated to be methane gas and water. There is a risk of plugging in the production well by reformed methane hydrates such as at stagnation points and during an operation stop. To manage the plugging risk, inhibitors for methane hydrate formation are necessary. Among several chemical inhibitors, thermodynamic hydrate inhibitors (THIs) are a unique technique that can dissociate methane hydrates. Ammonium salts are one of THIs which naturally occur in oceans and vastly available in the deep sea area. In this study, inhibition effects of ammonium chloride on gas hydrates of methane, carbon dioxide and ethane are investigated. Three phase (gas–hydrate–aqueous) equilibrium conditions are measured by a temperature search method. The equilibrium data show that ammonium chloride suppresses equilibrium temperatures of these gas hydrates until it reaches solubility limit in water. The comparison with molecular inhibitors showed that ammonium chloride inhibits methane hydrate formation more than urea, but less than methanol. The present data clarified the inhibition effect of ammonium chloride on subsea natural gas hydrates and CO2 injection and sequestration techniques.

Formation of a Mixed Region of Carbon Dioxide and Methane Hydrates during the Injection of Liquid Carbon Dioxide to a Reservoir Saturated with Methane and Water

Based on the equations of continuous medium mechanics, a mathematical model is constructed for the injection of liquid carbon dioxide into the porous medium saturated with methane and water for the case when the injection is accompanied by the formation of gas hydrates of carbon dioxide and methane. Self-similar solutions to the one-dimensional problem describing the evolution of hydrodynamic and temperature fields are constructed. The dynamics of movement of frontal boundaries of phase transitions with respect to injection pressure and temperature, as well as with respect to permeability and initial pressure of the porous medium is investigated. It is shown that intensity of the formation of methane and carbon dioxide gas hydrates increases with an increase in injection pressure and reservoir permeability, and at rather high values of permeability, pressure drop in the reservoir and injection temperature, the frontal formation boundaries of methane and carbon dioxide gas hydrates may merge. The dependence of the limit values of injection pressure and temperature corresponding to the merger of the phase transition boundaries on the permeability and initial pressure is studied in this work.

Model of transient CO2 gas hydrate particle size distribution at its equilibrium condition

It is important to comprehend the relationship between temperature and pressure at which different sizes of hydrates with a particular distribution. When hydrate particles are formed at unsteady state condition, the moment and the spreadness of the distribution of the formation of the hydrate particles is changed with time. The change of distribution of hydrate particle is one of the important parameter for the secondary nucleation rate of gas hydrate. In this study, a model is developed and proposed to predict the particle size distribution of carbon dioxide gas hydrate at its equilibrium condition. The distribution model may be useful for further understanding of the nucleation mechanism and its rate of gas hydrate formation.

The formation of carbon dioxide hydrate from water sorbed by coals

Experiments on the formation and dissociation of carbon dioxide gas hydrate formed from water that was adsorbed in two sub-bituminous coals and anthracite were carried out. Preliminarily, the coal samples were studied using various physicochemical methods. It was demonstrated that the conditions of the hydrate decomposition in coal do not differ substantially from the equilibrium conditions of carbon dioxide hydrate. In all the cases, the conversion of water to hydrate increases with increasing the pressure of the hydrate former and the initial humidity of coal samples. At the same time, it turned out that the amount of unreacted water in the sample also increases with an increase in the initial humidity of coal sample. A phenomenological model explaining the observed features of the hydrate formation in coal was proposed on the basis of the data obtained. In this model, the hydrate formation in coal is considered as a two-stage process: (1) a partial displacement of coal-sorbed water from the pore space into macropores and on the coal surface due to competitive sorption of carbon dioxide, and (2) the formation of hydrate from water droplets formed in the first stage.