Carbon Dioxide Hydrate Formation Research Articles

Methane and Carbon Dioxide Hydrate Formation in the Presence of Metal-Based Fluid

Hydrate-based technology has yet to find its way to commercial applications due to several issues, including formation conditions and slow kinetics. Several solid particles were introduced to speed up hydrate formation. However, these solid compounds have given contradictory results. This study investigated the effect of high thermal conductive metallic nanofluids of silver (Ag) and copper (Cu) on CH4 and CO2 hydrates. The solid particles were suspended in a 0.03 wt% SDS aqueous solution, and the results were compared with the 0.03 wt% SDS and deionized water samples. A stirred tank batch reactor was used to conduct the thermodynamic and kinetic experiments. The thermodynamic study revealed that 0.1 wt% of solid particles do not shift the equilibrium curve significantly. The kinetic evaluation, including induction time, the initial rate of gas consumption, half-completion time, t50 and semi-completion time, t95, gas uptake, and storage capacity, have been studied. The results show that the Ag and Cu promote CH4 hydrates while they inhibit or do not significantly influence the CO2 hydrates formation. A predictive correlation was introduced to get the apparent rate constant of hydrate formation in the presence of metal-based fluid at the concentrations range of 0.005-0.1 wt%.

Calorimetric study of carbon dioxide (CO2) hydrate formation and dissociation processes in porous media

Understanding the formation and dissociation mechanisms of gas hydrate in porous media is important for the development of new energy-efficient and environmentally friendly technologies related to cold storage as they provide significant latent heat and energy density at suitable phase change temperature. The challenge is to understand the interactions between gas hydrates and the chosen storage media in order to assess the operating conditions likely to optimize time and energy consumption in cold production and storage systems. In this work, CO2 hydrates formation and dissociation are investigated in two morphologically different porous materials: sand and silica gels. A calorimetric approach is applied to study both the CO2 hydrate formation kinetics, particularly the induction time, and the amount of hydrate formed for each of the two porous materials. The experiments are performed using a differential thermal analysis device with two identical measuring cells. The present work is focused on assessing the effect of key factors like water saturation, particle size and the morphology of porous media on CO2 hydrate formation and dissociation processes. Overall, the results do not show a statistically significant correlation between these factors and the induction time. Interestingly, the results obtained with dual porous silica gel showed a higher amount of hydrate formed compared to those with sand for similar initial pressure, temperature and water content conditions. This result may be due to the fact that silica gels provide higher surface area due to their smaller particle size (20–45 µm vs 80–450 µm for sand), and the presence of internal pore volume in silica gel particles.

Experimental investigation and modelling of synergistic thermodynamic inhibition of Diethylene Glycol and glycine mixture on CO2 gas hydrates

In this experimental and modelling study, Diethylene glycol (DEG) and Glycine (Gly) mixtures are introduced to hinder carbon dioxide hydrate formation by pushing the phase boundaries on the lower temperature side. The mixture of DEG and Gly with the ratio of 1:1 is experimented at 15, 10, and 5 wt% concentrations and the pressure vary from 2.5 to 4.0 MPa. The T-cycle method is employed to assess the effect of the studied blends on the CO2 hydrate by evaluating the hydrate dissociation temperature. Varied compositions of pure DEG and Gly as well as their mixtures are used to compute the synergistic effect. The studied system's thermodynamic hydrate inhibition (THI) influence is a concentration-driven phenomenon. Higher concentration can shift the hydrate liquid vapor equilibrium (HLVE) curve to lower temperatures and high-pressure regions. The outcomes depict that mixture of DEG and Gly at 15 wt%. Shows comparatively better results than the mixtures at 5 and 10 wt%, respectively. The obtained 10 wt% mixture results have also been compared with the conventional hydrate inhibitors and other THIs systems and provide a significant hydrate average suppression (ΔT) of 2.4 K. Furthermore, the freezing point-based Dickens and Quint Hunt model was also applied to predict the HLVE data of CO2 hydrates and satisfactory agreement found with maximum mean absolute error (MAE) of 0.498 K. A better inhibitory performance was seen when diethylene glycol and glycine were combined, demonstrating the potential of amino acids as synergistic inhibitors in the exploitation of hydrates, transportation of oil and gas, and flow assurance.

Effects of silica gel nanopores and surfactants on CO2 hydrate formation kinetics—An experimental and modeling study

The carbon dioxide (CO2) hydrate formation kinetics in silica gel (SG) nanopores with the addition of surfactants are studied both experimentally and numerically. SGs with pore sizes of 50 and 100 nm are used as frameworks for hydrate formation in pores. Sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTAC) are used as kinetics promoters which can greatly enhance gas–water mass transfer. An advanced shrinking core model considering CO2 solubility, pore size, surfactants, and capillary effect is established. The results reveal that the reaction rate constant is increased in large pores or in the presence of surfactants, saving up to 49.3 % time to achieve the same amount of gas uptake in 100-nm SG with 500-ppm SDS. The effective diffusion coefficient controlled by a reduction factor drops dramatically due to the enlargement of the reduction factor in small pores and more surfactants, thus hindering the gas diffusion through the formed hydrate shell. The initial water consumed by capillary effect is more prominent in smaller pores and with the addition of surfactants. The initial proportion of water consumed by capillary effect to the total water consumption is only 1%–26.6% without surfactants, but can be up to 74.9% in 50-nm SGs with 500-ppm SDS. This proportion is overall higher in SDS systems than that in studied DTAC systems, but it is not obviously affected by surfactant concentrations. The higher proportion of water consumed by capillaries is speculated to be due to the more capillary tubes with larger radii formed initially in the presence of surfactants. The modeling strategies in this work can be applied to hydrate formation mechanisms in other porous materials.

Intensified Carbon Dioxide Hydrate Formation Kinetics in a Simulated Subsea Sediment: Application in Carbon Capture and Sequestration

Intensified Carbon Dioxide Hydrate Formation Kinetics in a Simulated Subsea Sediment: Application in Carbon Capture and Sequestration

Development of dual functional methodology for seawater desalination and salt manufacture by carbon dioxide hydrate formation

Clathrate-hydrate-based seawater desalination is a novel technology that is performed by reaction between seawater and guest compounds to obtain fresh water. This study proposed a dual functional methodology for seawater desalination and salt manufacture by using carbon dioxide clathrate hydrate. In this methodology, the clathrate hydrate formation continues until the concentration of electrolytes in unreacted brine reaches the saturated solubility for the salt precipitation. The visual observation of the clathrate hydrate formation and the salt precipitation coupled with the analysis utilizing the powder X-ray diffraction (PXRD) technique was implemented to demonstrate the methodology. The carbon dioxide clathrate hydrate formation was first performed with sodium chloride aqueous solution. The carbon dioxide clathrate hydrate crystals floated on high salinity water. This experiment was followed by the occurrence of the sodium chloride dihydrate precipitation upon the carbon dioxide clathrate hydrate formation. The formed compounds, carbon dioxide clathrate hydrate and sodium chloride dihydrate, were identified by PXRD analysis. The mass fraction of the compounds was also determined by PXRD.

Dimethyl sulfoxide as a novel thermodynamic inhibitor of carbon dioxide hydrate formation

• Dimethyl sulfoxide decreases the thermodynamic stability of carbon dioxide hydrate. • Obtained CO 2 hydrate dissociation data are reliable and thermodynamically coherent. • Phases of sI hydrate, crystalline ice I h , and solid CO 2 were identified by PXRD. • DMSO avoids inclusion into the CO 2 hydrate framework. • DMSO is an effective thermodynamic inhibitor of CO 2 hydrate formation. The paper investigates dimethyl sulfoxide (DMSO) as a promising inhibitor of gas hydrates. The equilibrium conditions of the CO 2 hydrate were measured over a broad range of temperatures (from 243 K to 283 K) and DMSO concentrations (up to 50 mass%). DMSO decreases the thermodynamic stability of the CO 2 hydrate. Thermodynamic coherence of new hydrate equilibria data was demonstrated. The sI hydrate, crystalline ice I h , and solid CO 2 phases were identified using PXRD at 143 K. Measured unit cell parameter for sI hydrate (11.86 Å) coincided with the pure sI CO 2 hydrate literature value. The DMSO inhibition activity grows much faster in water solution in comparison to lower alcohols. We explain this behavior by the more pronounced non-ideality of DMSO water solutions. Thus, DMSO can be considered an effective thermodynamic inhibitor of the formation of CO 2 hydrate, superior in anti-hydrate activity to alcohol THIs within a specific range.

Experimental and numerical analysis of CO2 and CH4 hydrate formation kinetics in microparticles: A comparative study based on shrinking core model

The promotion of gas hydrate formation kinetics through mass transfer enhancement has been an important research topic, for which microparticles have been considered an effective method. In this work, carbon dioxide (CO2) and methane (CH4) hydrate formation kinetics in microparticles are investigated using “dry water” particles made of 3, 5 and 8-wt% silica. A modified shrinking-core model is established to study the CO2 and CH4 hydrates formation kinetics. It is the first model that integrates the effects of dissolved gas, the capillary effect of porous hydrate shell, and the volume change from water to hydrate. The experimental results reveal that “dry water” particles with 8-wt% silica has the highest normalized gas uptake due to their small particle size. The simulation results show an initial effective diffusion coefficient of 6.41–6.50×10–14 m2s−1 for CO2 and a slightly higher 6.83×10–14 m2s−1 for CH4 hydrate formation. The average effective diffusion coefficient of gas is higher in smaller particles. The water consumed through capillaries is more prominent in smaller particles, but it only accounts for less than 10% of water consumed at the hydrate–water interface. Furthermore, a decoupled heat transfer model was developed to quantify the effect of heat transfer in gas hydrate formation. The instantaneous temperature gradient in the hydrate shell is of a small magnitude of 10–2 K m−1, indicating that the impact of the heat transfer on hydrate formation kinetics is negligible. This work provides comprehensive insights into gas hydrate formation in microparticles and contributes as a theoretical basis for the improvement of gas hydrate kinetics through mass transfer enhancement.

Effect of liquid alkane on carbon dioxide hydrate formation

Hydrophobic surface affects gas hydrate formation. It is an effective method to promote hydrate formation by adding hydrophobic materials into hydrate formation system. However, it is little known about the interaction between hydrate formation and macroalkane. n-Dodecane and n-tetradecane are selected as additives to investigate their effect on CO2 hydrate formation in this work. The addition of liquid alkanes effectively improves hydrate nucleation, shortens the induction time of CO2 hydrate formation, and improves the hydrate growth rate. In addition, the total CO2 uptake at the end of the experiments was increased in the presence of liquid alkanes. Compared with the addition of n-dodecane, n-tetradecane has a weaker effect on CO2 hydrate formation. Increasing the stirring rate can effectively reduce the induction time of hydrate formation and improve hydrate growth rate, but has little effect on gas storage capacity in hydrates. The experimental results also show that the increase of experimental pressure or the decrease of temperature is conducive to hydrate formation.

Effects of Composite Accelerators on the Formation of Carbon Dioxide Hydrates.

To improve the rate of formation of carbon dioxide hydrates, tetra-n-butylammonium bromide (TBAB) was compounded with different concentrations of sodium dodecyl sulfate (SDS) and nanographite, and the effects of these mixtures on carbon dioxide hydrate formation were studied. The addition of TBAB alone, as well as mixtures of TBAB and SDS or nanographite, shortened the induced nucleation time, and the induction times of the TBAB–2.5 g/L nanographite and TBAB–0.24 g/L SDS systems were the shortest and longest, respectively. Further, on mixing TBAB and SDS, the induced nucleation time first increased and then decreased with the increase in the SDS concentration. When TBAB and nanographite were mixed together, the induced nucleation time first decreased, then increased, and again decreased with the increase in the nanographite concentration. In addition, the hydrate formation rate and conversion were highest for the TBAB–0.48 g/L SDS system and lowest for the TBAB–0.06 g/L SDS system; in the first 35 min, from the end of gas charging, the TBAB–10 g/L nanographite and TBAB–5 g/L nanographite systems yielded the highest and lowest hydrate formation rates and conversions, respectively. For the composite systems, obvious effects were observed in the initial stages of reaction, but the effects varied over the course of the reaction. Overall, the use of different accelerators resulted in little differences in the total production, conversion, and formation rate of carbon dioxide hydrates over the course of the reaction.

Experimental study on carbon dioxide hydrate formation in the presence of static magnetic field

The formation kinetic parameters, phase equilibrium and dissociation enthalpy of carbon dioxide hydrate in the presence of static magnetic field were investigated in this work. The experiments were carried out in pure water and (0.029, 0.056 and 0.110, mass fraction) sodium chloride (NaCl) aqueous solution with a magnetic field of 0.39 T. The experimental results showed that the induction time of carbon dioxide hydrate nucleation was shortened, the consumption amount and rate of carbon dioxide were significantly increased with the magnetic field. This phenomenon is mainly attributed to the fact that the magnetic effect decreases the contact angle between water and solid surface to reduce the critical size and critical free energy of hydrate nucleation. Moreover, the phase equilibrium of carbon dioxide hydrate in both pure water and NaCl aqueous solution shifted to lower pressure or higher temperature with the magnetic field, and the equilibrium temperature in pure water decreased by 3.0 K, which is due to the change of the hydrogen bond in small clusters and ions mobility by magnetic effect. In addition, the dissociation enthalpies of carbon dioxide hydrate in pure water and (0.029, 0.056 and 0.110) NaCl solution calculated by Clausius-Clapeyron equation were 91.5, 91.4, 62.8 and 52.0 kJ·mol−1, respectively, in the magnetic field, which is related to the movements of ions caused by magnetic effect and heat absorption.

Effect of different salts on the kinetic parameters of the carbon dioxide hydrate formation

In this study, the effects of sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl2), and calcium chloride (CaCl2) on the kinetic parameters of carbon dioxide (CO2) hydrate formation including induction time, amount of gas consumption, rate of gas consumption and storage capacity were experimentally studied. Aqueous solutions with the ion concentration same as the Persian Gulf Seawater were prepared and all the experiments were conducted at a temperature of 274.15 K and pressure of 3.5 MPa. The results showed that salts have an inhibitory effect on the kinetic parameters of CO2 hydrate formation by reducing CO2 solubility in water and electrostatic interaction between water molecules and ions. The intensity of ion inhibition depends on the ion size, ion charge, ion concentration, and the kosmotropic and chaotropic properties of ions. Examination of the kinetic parameters of CO2 hydrate formation in saline solutions with a constant concentration of 1000 mg/L of each ion showed that the Mg2+ has the greatest inhibitory effect on the kinetic parameters by increasing the induction time by 110.71% and reducing gas consumption, rate of gas consumption, and storage capacity by 48.21%, 82.14%, and 68.75%, respectively compared to pure water. The results showed that the inhibition effect of salt ions on the CO2 hydrate formation is in the following order: Mg2+> Ca2+>Na+>K+.

Insights into carbon dioxide hydrate formation, fluid type, and agglomeration in the system with or without tween-80

In this work, the flow of carbon dioxide (CO2) hydrate slurry is systematically investigated by analyzing its rheological behavior, apparent viscosity, and crystal shape. The results show that blocking is easy to occur in the pure water system, while no blockage is observed from the system containing Tween-80. Besides, we confirm that the hydrate slurry formed in the pure water system is a dilatant fluid with shear-thickening behavior. However, that obtained from the system containing Tween-80 are pseudoplastic fluids with shear-thinning behavior. The time development of hydrate slurry flow in the system with or without Tween-80 showed that the shear-thinning behavior is a key factor in preventing the hydrate slurry from blockage. In addition, in the presence of Tween-80, hydrates will form on the surface of the bubble. These hydrates are easily dispersed on top of the liquid phase and will not adhere to the top wall of the pipeline. However, in pure water, a dense adhesive layer is observed on the top of the pipeline, which will reduce the flow area in the pipeline, increasing the flow resistance. Overall, the main role of Tween-80 in preventing hydrates from aggregation includes two aspects, (1) changing the type of fluid from dilatant to pseudoplastic; (2) providing bubbles for hydrate formation. The addition of defoamer(BK601) will reduce the Tween-80′s effects in preventing hydrates by reducing shear-thinning behavior and the amount of bubbles.

Sequestration and Storage of Carbon Dioxide Using Hydrate Formation Method in the Presence of Copper Oxide Nanoparticles

The nanofluid-based gas hydrate formation process employing copper oxide (CuO) nanoparticles have been experimentally investigated in this work. Different concentrations of nanofluids are injected into the reactor at the operating condition of 29 bar, 274.15 K, and impeller speed of 100 rpm. It was observed that the kinetics of the carbon dioxide hydrate formation process was greatly affected by the nanoparticles. The remarkable point was that at a very low concentration of 20 ppm, a considerable improvement on the carbon dioxide hydrate formation kinetic without using any surfactant was obtained. At the concentration of 20 ppm, the values of the initial rate of hydrate formation, growth time, and induction time were 0.0495, 194.5, and 4.4 min, respectively, which these results can be of great importance for the use of carbon dioxide hydrate in various industries. The results indicated that the kinetics of gas hydrate formation was also severely influenced by the impeller speed and initial gas pressure. The rate of CO2 captured in the hydrate crystalline lattice is also modeled by the first-order kinetic model. It was seen that this model can be used to predict the rate of hydrate formation with considerable accuracy.

Effect of sodium tripolyphosphate (STPP) and tetrasodium pyrophosphate (TSPP) on the formation kinetics of CO2 hydrate in bulk and porous media in the presence of pure water and seawater relevant for CO2 sequestration

Enhanced kinetics of carbon dioxide (CO2) hydrate formation will assist in developing technologies for CO2 gas storage, carbon capture and sequestration (CCS), and potentially for methane production from natural gas hydrates. The present work is focused on understanding the kinetics of CO2 hydrate formation in both bulk and porous media with pure water and seawater under the influence of non-toxic and low-cost inorganic emulsifiers or builders. Sodium tripolyphosphate (STPP) and tetrasodium pyrophosphate (TSPP) was used in a very low concentration of 0.2 wt.% to promote its economic viability. The experiments were carried out in a 300 mL stirred tank reactor and 100 mL porous bed reactor with an initial pressure of 3.5 MPa and 274.65 K with pure water and seawater, respectively. The porous bed was made with 0.15 mm silica sand with 70% water saturation. Both STPP and TSPP showed significant improvement in induction time for CO2 hydrate formation. Moreover, STPP showed reasonable enhancement in CO2 gas uptake compared to TSPP in both bulk and porous bed with both pure water and seawater. The average rate of hydrate formation was also better for STPP with multiple growth peaks. The results obtained will enhance hydrate-based technologies for efficient CO2 sequestration in shallow subsea sediments.

Experimental determination of dissociation temperatures and enthalpies of methane, ethane and carbon dioxide hydrates up to 90 MPa by using a multicycle calorimetric procedure

This work presents the application of a multicycle procedure to determine the dissociation temperature and enthalpy of gas hydrates using high-pressure microcalorimetry (HP-µDSC). In the multicycle procedure, a sample of water in contact with the gas undergoes successive cooling and warming cycles below hydrate dissociation temperature, increasing the conversion of water into hydrate. This technique has been previously used in literature to increase water conversion during carbon dioxide hydrate formation up to 2.0 MPa, but its applicability has not been assessed for higher pressures and with different guest molecules. New experimental equilibrium data for methane, ethane, and carbon dioxide hydrates were obtained through HP-µDSC up to 90 MPa using the multicycle procedure. The advantages and limitations of the method are discussed. Dissociation temperatures are in good agreement with data previously obtained from a HP-µDSC standard method, which confirms the reliability to determine this property by both methods. Nevertheless, the enthalpy of hydrate dissociation obtained by the direct integration of thermograms provided by the HP-µDSC standard method is not accurate. Thus, it is usually calculated by using the Clapeyron equation from equilibrium temperature and pressure data obtained by the HP-µDSC standard method, as presented in previous work. The new dissociation enthalpies presented in this work were obtained experimentally by direct integration of thermograms using the multicycle procedure, which provides accurate data as the conversion is very high (above 97% of water converts into hydrate), the baselines are clearly established, and no exothermic peak related to metastable phases is observed.

An insight on effects of activated carbon and a co-promoter on carbon dioxide hydrate formation and dissociation

The influence of activated carbon (AC) particle size on the formation and dissociation of CO2 hydrates was investigated. ACs with different particle sizes (250–420 µm; 420–841 µm; larger than 841 µm) were employed in the hydrate formation experiment at 276.2 K and 3.6 MPa in the quiescent condition. The result showed that the large AC particle size was more effective on promoting CO2 hydrate formation with shorter induction time, higher gas uptake, and higher formation rate. The study continued to investigate the effects of AC saturated with the solution of sodium dodecyl sulfate (SDS) on the CO2 hydrate formation. It was observed that the addition of 2 mM and 4 mM SDS increased the gas uptake compared with that of AC, while the addition of 6 mM SDS did not. The synergistic effect of SDS and AC was discussed. Moreover, the observed morphology during the hydrate formation and dissociation was provided.

Methane and Carbon Dioxide Hydrate Formation and Dissociation in Presence of a Pure Quartz Porous Framework Impregnated with CuSn12 Metallic Powder: An Experimental Report.

Hydrate formation and dissociation processes were carried out in the presence of a pure quartz porous medium impregnated with a metallic powder made with a CuSn12 alloy. Experiments were firstly made in the absence of that powder; then, different concentrations were added to the porous medium: 4.23 wt.%, 18.01 wt.%, and 30.66 wt.%. Then, the hydrate dissociation values were compared with those present in the literature. The porous medium was found to act as an inhibitor in the presence of carbon dioxide, while it did not alter methane hydrate, whose formation proceeded similarly to the ideal trend. The addition of CuSn12 promoted the process significantly. In particular, in concentrations of up to 18.01 wt.%, CO2 hydrate formed at milder conditions until it moved below the ideal equilibrium curve. For methane, the addition of 30.66 wt.% of powder significantly reduced the pressure required to form hydrate, but in every case, dissociation values remained below the ideal equilibrium curve.

Analyses on CH4 and CO2 hydrate formation to define the optimal pressure for CO2 injection to maximize the replacement efficiency into natural gas hydrate in presence of a silica-based natural porous medium, via depressurization techniques

To make natural gas hydrate an energy source available for large-scale applications, some issues must be solved; amongst them, the low kinetic characterizing the process and re-formation of methane hydrate are the most significant. In this paper methane and carbon dioxide hydrate formation was tested in presence of a natural silica-based porous sand, with the aim of define the most useful pressure value for carbon dioxide injection into reservoirs in order to apply replacement strategies via depressurization. A direct comparison between CO2 hydrate formation tests starting respectively from 30 bar and 40 bar, revealed that this latter solution represents the most effective solution. While moles of CO2 involved into hydrate and, more in general, moles of CO2 permanently stored, are similar in both typologies of tests, the time necessary to complete the formation process was drastically lower in tests started from 40 bar. Moreover, a lower pressure drop would be required. The more effective kinetic of the process and the negligible risk of methane hydrate re-formation verified during experiments, allowed to consider the CO2 injection into the reservoir at 40 bar the best solution to optimize methane recovery, carbon dioxide storage and seafloor deformations due to the reservoir exploitation.

The effect tetra butyl ammonium hydroxide and tween on the kinetics of carbon dioxide hydrate formation

In this research, the kinetics of CO2 hydrate formation in the presence and absence of TBAOH as a thermodynamic additive and tween as a kinetic additive is investigated. A high-pressure autoclave equipped with a rocking-cell mixer was applied to determine the effect of TBAOH and tween on the process of carbon dioxide hydrate formation. The findings of the experiments show that using TBAOH had a dual effect on the formation of carbon dioxide hydrate. Low concentrations of TBAOH presented a positive effect on the CO2 hydrate formation kinetics but using this component with a mass fraction of 8% inhibited the quantity of gas uptake and storage capacity (SC) at the feed pressure of 3 MPa. Using 10 and 300 ppm tween 80 promotes the formation of CO2 hydrate kinetics. Investigating the influence of simultaneous utilization of TBAOH and tween 80 on the quantity of the formation CO2 hydrate showed that this system decreased the quantity of CO2 uptake in comparison with aqueous solutions of tween and TBAOH.