CO2 Hydrate Formation Rate Research Articles

Optimizing CO2 Hydrate Sequestration in Subsea Sediments through Cold Seawater Pre-Injection

Carbon sequestration technology offers a solution to mitigate excessive carbon dioxide emissions and sustainable development in the future. This study proposes a method for subsea carbon sequestration through the injection of cold seawater to promote CO2 hydrate formation. Using a self-developed simulator, we modeled and calculated the long-term sequestration process. The study focuses on analyzing the thermal regulation of the seabed following cold seawater injection, the multiphysical field evolution during CO2 injection and long-term sequestration, and the impact of seawater injection volumes on sequestration outcomes. The feasibility and leakage risks of this method were evaluated on a 100,000-year timescale. Results indicate that the injection of cold seawater significantly improves the pressure–temperature conditions of subsea sediments, facilitating early hydrate formation and markedly increasing the initial CO2 hydrate formation rate. Consequently, the distribution pattern of hydrate saturation changes, forming a double-layer hydrate shell. Over the long term, while cold seawater injection does not significantly reduce CO2 leakage, it does increase the safety margin between the hydrate layer and the seabed, enhancing the safety coefficient for long-term CO2 hydrate sequestration. Through detailed analysis of the behavior of CO2 components during sequestration, this study provides new theoretical insights into subsea CO2 hydrate storage.

Spatial evolution of CO2 storage in depleted natural gas hydrate reservoirs and its synergistic efficiency analysis

Carbon neutrality is now a common strategic target worldwide, with geological storage seen as the mainstream scheme to address CO2 emissions and the greenhouse effect. Depleted natural gas hydrate reservoirs (DNHR), with their high-pressure, low-temperature environment, could capture CO2 in the form of hydrates, being an innovative way for carbon storage. A lab-scale reactor was used in this work to simulate CO2 injection into the reservoir after gas hydrate exploitation. As expected, it was found that the low-temperature environment of the depleted reservoir at the end of gas production provided a high driving force and accelerated the rate of CO2 hydrate formation. Consequently, the maximum gas storage capacity was increased by 66% by optimizing the injection timing and reducing the gas injection flow rate to enable enough hydrate formation. Besides, the formation of CO2 hydrate in the DNHR could also help stabilize the reservoir to achieve a more efficient CH4 production and CO2 storage. This study provides a novel strategy for gas hydrate exploitation as well as subsequent geological storage of CO2 in depleted natural gas hydrate reservoirs by making full use of their favorable conditions.

Heterogeneous nucleation of CO2 hydrate: A thermodynamics analysis considering effects of wall characteristics and solution activity

The massive emission of greenhouse gas CO2 has significant effects on global climate and environment, causing worldwide concern. It has been proposed to store CO2 in clathrate hydrates as a possible strategy for reducing atmospheric CO2 emission. Nevertheless, the CO2 hydrate formation rate is slow and its associated heterogeneous nucleation mechanisms are not well understood, which limit commercial applications of this technology. This study developed a thermodynamic model based on the change in availability function approach, considering effects of surface characteristics (including surface topography, roughness, curvature radius, and wettability), and CO2 dissolution on the solution's activity. The critical nucleation radius and energy barrier of CO2 hydrate nucleation are determined. Effects of pressure, temperature, wall characteristics and solution activity on the nucleation radius of CO2 hydrate are discussed. The results of this paper contribute to advancing carbon capture and storage technology based on hydrate methods.

Enhanced CO2 hydrate formation using hydrogen-rich stones, L-Methionine and SDS: Insights from kinetic and morphological studies

One promising proposal for CO2 capture and storage is based on hydrate technology, which grapples with challenges related to stringent formation conditions and slow formation rates. In this study, the induction time, gas uptake and the rate of CO2 hydrate formation were measured with varying concentrations (ranging from 0.05 wt% to 0.2 wt%) of L-Methionine (L-Met) and sodium dodecyl sulfate (SDS). Remarkably, the novel additive hydrogen-rich stone significantly reduced the induction time by 89.74 % and 85.16 %, even under static conditions. The morphology analysis reveals that L-Met foster the creeping growth of hydrates, resulting in an approximate 41.89 % increase in the initial 1 h gas uptake. The efficient heat diffusion further enables the rapid formation of hydrates, resulting in a high gas uptake in a short period. L-Met outperforms SDS in terms of induction time and gas uptake, with the optimal choice for CO2 hydrate formation being 0.1 wt% L-Met. This study briefly describes the mechanisms of three different kinetic promoters for hydrate formation, which provides new ideas for subsequent studies on CO2 capture and storage via hydrate technology.

Hydrothermally engineered enhanced hydrate formation for potential CO2 capture applications

Gas hydrate formation is regarded as the emerging technology to mitigate the effect of greenhouse gases. Now a day, the alarming situation of increased CO2 concentration of about 450 ppm is associated with elevation of earth temperature up to 2°Ϲ. Where the CO2 hydrate (CO2.6H2O) formation is of environmental and scientific interest due to carbon capture and storage (CCS) in order to condense environmental CO2 concentration. The present study is experimentally addressing the four different sample preparation procedures (method 1, 2, 3 and 4) of stirring for the CO2 hydrate (CO2.6H2O) formation correlated with the integrated gasification combine cycle (IGCC) conditions. A high-pressure volumetric analyzer (HPVA) is used to explore the rate of CO2 hydrate formation that is critically investigated using pressure-time (P-t) curves for all the prepared samples. The highest stirring (method 4) speed with 37000 rpm, had the highest moisture content of 14.8 wt% as well as at 275 K and 36 bar. By using method 4 hydrate conversion of 40.5 mol% was observed. The high stirring method (method 4) show gas uptake of about 3.9 mmol of carbon dioxide per gram of H2O and the highest rate for formation of hydrate as 0.05 mmol of carbon dioxide per gram of H2O per min. Further, comparison of promoter’s combination relative to long experiment duration resulted in the increment of 13.82 mol% of water to hydrate conversion in 2600 min at 283 K and 58 bar for T1–5 (having 5.6 mol% of THF and 0.01 mol% of SDS) as compared to the experiment that was performed in 1200 min.

In-situ measurement of interfacial tension: Further insights into effect of interfacial tension on the kinetics of CO2 hydrate formation

Hydrate-based CO2 capture and sequestration has been viewed as one of the most attractive technologies due to its environmental friendliness and relatively moderate temperature and pressure conditions. In current work, the kinetics of CO2 hydrate formation was investigated at pressures of 2.5–3.5 MPa and temperatures of 274.15–279.15 K and the effect of interfacial tension on CO2 hydrate formation rate was discussed. The interfacial tension between CO2 and aqueous solution during the hydrate formation was in-situ measured via an axisymmetric drop shape analysis method. Under the experimental conditions of this study, the interfacial tension decreased significantly with increasing pressure, while it did not vary obviously with temperature. As to SDS aqueous solutions, the interfacial tension at the gas-liquid interface decreased approximately 12% and 42% when the SDS concentration was 100 ppm and 500 ppm, respectively. In addition, CO2 hydrate formation rate ascended by 59% and 102% when the SDS concentration is 100 ppm and 500 ppm, respectively. Furthermore, a good linear relationship was observed between hydrate formation rate and ratio of driving force to interfacial tension (R2 = 0.9211). This work provides a new idea for rapid estimation of hydrate formation rate.

Study the kinetics and thermodynamics conditions for CO2 hydrate formation in orange juice concentration

Abstract In this study, for concentration of orange juice, two laboratory systems were used; one for CO2 hydrate formation at high-pressure system, another for formation of THF hydrate at atmospheric pressure system. In the high-pressure system, the kinetic parameters of CO2 hydrate formation in orange juice were investigated in comparison with pure water, in constant temperature and volume. Also the effect of the initial pressure (20, 30 and 35 bar), temperature (2, 3 and 4 °C) and brix (10, 13 and 16) were investigated on hydrate formation conditions. The results showed that, with increasing the pressure and lowering temperature, the initial rate of formation CO2 hydrate is increased and the relaxation time is decreased. With increasing the brix, the initial rate of CO2 hydrate formation is decreased and the relaxation time is increased. The maximum relaxation time of 1230 s was reached at 20 bar, 4 °C and 16 brix. It was determined that the content of orange juice plays as an inhibitor in hydrate formation. In the atmospheric system, the effect of brix (7, 10, 13, 16 and 20) on kinetics of THF hydrate formation was investigated in orange juice. After the separation of the formed crystals, the secondary brix was measured; the highest concentration in the initial brix of 7 was obtained about 200%., with increasing the brix, the induction time was increased, while it had no effect on the relaxation time.

Experimental and theoretical investigations regarding the effect of chromium oxide nanoparticles on the CO2 gas capture through gas hydrate process in petroleum industry

Effects of chromium oxide (Cr2O3) nanoparticles on the rate of CO2 hydrate formation have investigated in this work. It is found that there is an optimum Cr2O3 nanoparticle concentration of 60 ppm for which the maximum overall rate of CO2 hydrate formation is obtained. A new kinetic model is also presented for description of early stage of CO2 capture process. The proposed technique is a potential alternative for enhancing the rate of CO2 sequestration via gas hydrate formation regarding CO2 emission control in oil and gas industries.

Investigating the effect of silver nanoparticles on carbon dioxide hydrates formation

Gas hydrates have been considered as a promising approach for gas separation, storage, and transportation. Low hydrates formation rate has been identified as a major weakness of this technology. However, introducing hydrate promoter could accelerate the hydrates formation process. In this paper, silver nanofluids are investigated as kinetic CO2 hydrates promoter by measuring the induction time, the initial rate of CO2 hydrate formation, and the amount of CO2 gas consumed at a pressure of 2.7MPa and temperature of 277.15 K. Silver nanofluids are prepared at a concentration range of 0.01 to 0.1 wt% of silver nanoparticles mixed with 0.08 SDS wt%. The experiments are conducted through high pressure reactor hydrate cell. The results show that nanoparticles enhance the initial hydrate formation rate and amount of gas consumption. However, no significant effect is observed on the induction time compared to SDS solution.

The combination of 1-octyl-3-methylimidazolium tetrafluorborate with TBAB or THF on CO2 hydrate formation and CH4 separation from biogas

Abstract [C8min] BF4 was used in this work to combine with TBAB or THF for the investigation about thermodynamic and kinetic additives on CO2 and CH4/CO2 hydrates. The results show that [C8min] BF4 has the inhibition effect on the equilibrium of hydrate formation. About the kinetic study, [C8min] BF4 could improve the rate of CO2 hydrate formation and increase the gas uptake in hydrate phase. At the same time, the combination of TBAB and [C8min] BF4 could increase the mole friction of CH4 in residual gas comparing with the data in THF solution. CH4 separation efficiency was strongly enhanced. Since that the size of CO2 and CH4 molecules are similar, CH4 and CO2 could form the similar hydrate, so the recovery of CH4 from biogas decreases lightly. The CH4 content in biogas can purified from 67 mol% to 77 mol% after one-stage hydrate formation. In addition, the combination of THF and [C8min] BF4 do not have obvious promoting effect on CH4 separation comparing with the gas separation results in pure THF solution.

Effect of type-III Anti-Freeze Proteins (AFPs) on CO2 hydrate formation rate

CO2 hydrate slurry is a favourable direct coolant of fresh products due to its large latent heat and phase change temperature around 7°C. Continuous production of this slurry is, however, difficult to realise due to the high rate of hydrate formation. The use of additives is proposed with the purpose of decreasing the formation rate so that the controllability of the process is improved. Type-III Antifreeze Proteins (AFPs) are non-poisonous additives which, at low dosage, have proven to be efficient limiters of gas hydrate formation. The effect of these additives on the CO2 hydrate formation rate is experimentally investigated in this study.The concentration of the AFPs investigated in this research is 10ppm. Experimental results show that the supercooling degree of the solution is only slightly affected by the addition of AFPs. Results also show that the addition of AFPs slows down the dissolution rate of CO2 gas into the aqueous solution which is the first step of gas hydrate formation. A hydrate growth equation has been used, from which the experimental mass transfer coefficient of CO2 through the solution has been derived. Results show that the decrease of hydrate growth rate with the addition of AFPs can be related to a decrease of the CO2 mass transfer coefficient which gives a lower mass transport rate from bulk liquid phase to the crystal interface.

Inhibition properties of new amino acids for prevention of hydrate formation in carbon dioxide–water system: Experimental and modeling investigations

In the present work, the effect of new structures of amino acids is studied for prevention of hydrate formation in the carbon dioxide–water system. These amino acids consist of L-proline (as amino acid with nonpolar side chain), L-serine and L-glutamine (as amino acids with polar side chain), and L-histidine (as amino acid with charged side chain). The inhibition effects of these amino acids were compared with glycine, L-threonine, and poly-N-vinylpyrrolidone (PVP). Experiments were performed in the concentration range of 0.5–2wt.%. Investigation on the experimental results shows that inhibition properties of amino acids in an aqueous solution was due to hydrophobicity, the net charge of amino acid, and electrically charge of the side chain. Based on the experimental results, the ranking of amino acids (to decrease the hydrate growth rate) is as follows: L-histidine>glycine>L-proline≈L-serine≈L-threonine>L-glutamine, although the inhibition effect of some amino acids is not significant. In addition, the inhibition effects of these amino acids are quantitatively described by the chemical affinity model. The predicted results confirm that some of the applied amino acids decrease CO2 hydrate formation rate.

Experimental correlation for the formation rate of CO2 hydrate with THF (tetrahydrofuran) for cooling application

The CO2 hydrate formation experiments with THF (tetrahydrofuran) are performed in a stirred semi-bath reactor. The experimental data on CO2 hydrate formation are obtained at constant pressure and temperature with the low driving force conditions. The experimental temperature is above 279 K, which is high enough to prevent the formation of only THF hydrate. The Gibbs free energy difference by the pressure variation is chosen as the driving force. The experimental results confirm that the THF drastically reduces the required CO2 hydrate formation pressure. A two-parameter kinetic model based on the Chen-Guo model is developed to predict the CO2 hydrate formation rate and to correlate the experimental data. It is found that the experimental correlation based on the present estimation model fits well with the experimental results and can predict the CO2 hydrate formation rate satisfyingly for cooling application.

Impact of the fluid flow conditions on the formation rate of carbon dioxide hydrates in a semi‐batch stirred tank reactor

CO2 hydrate formation experiments are performed in a 20 L semi‐batch stirred tank reactor using three different impellers (a down‐pumping pitched blade turbine, a Maxblend™, and a Dispersimax™) at various rotational speeds to examine the impact of the flow conditions on the CO2 hydrate formation rate. An original mathematical model of the CO2 hydrate formation process that assigns a resistance to each of its constitutive steps is established. For each experimental condition, the formation rate is measured and the rate‐limiting step is determined on the basis of the respective values of the resistances. The efficiencies of the three considered impellers are compared and, for each impeller, the influence of the rotational speed on the rate‐limiting step is discussed. For instance, it is shown that a formation rate limitation due to heat transfer can occur at the relatively small scale used to perform our experiments. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4387–4401, 2015

Experimental study of concentration of tomato juice by CO2 hydrate formation

A new tomato juice concentration technology was presented by CO2 hydrate formation. The CO2 hydrate equilibrium conditions were measured by isochoric pressure search method and tomato juice concentration experiments were carried out in a high-pressure stirred reactor. Moreover, dehydration ratio was defined and CO2 hydrate formation rate constants were calculated with different feed pressure. The effects of feed pressure, temperature, and juice volume on dehydration ratio were investigated. The results show that the tomato juice used in this work nearly has no effect on CO2 hydrate phase equilibrium conditions, but can accelerate CO2 hydrate formation. And the dehydration ratio increased with increasing the feed pressure from 1.81 to 3.95 MPa, the maximum dehydration ratio can reach 63.2% with feed pressure of 3.95 MPa, and the optimum tomato juice volume is 80 mL. These results demonstrated that removal of water with the help of CO2 hydrate is an efficient technology for tomato juice concentration.

CO2 hydrate formation at atmospheric pressure using high efficiency absorbent and surfactants

CO2 hydrate slurry can be used in a lot of practical applications such as CO2 capture, CO2 storage-transportation and CO2 sequestration processes. However, CO2 hydrate slurry is generally formed at low temperature and high pressure. The objectives of this study are to develop new absorbents to form CO2 hydrate at atmospheric pressure, and to evaluate the effects of surfactants and additives on the formation rate and the induction time of CO2 hydrate. THF (Tetrahydrofuran) is used as a surfactant and SDS (Sodium dodecyl sulfate) and nano particles such as Al2O3 are used as the additives. It is found that the maximum CO2 hydrate formation rate is enhanced up to 3.74 times by adding 0.6 wt% of SDS and 0.2 wt% of Al2O3 nanoparticles compared to the formation rate without the surfactants. Finally, it is concluded that THF 10 wt% and SDS 0.6 wt% with Al2O3 0.2 wt% is the optimum condition for CO2 hydrate formation rate enhancement.

Concentrating orange juice through CO2 clathrate hydrate technology

A novel separation process was developed for orange juice concentration via CO2 hydrate formation. The CO2 hydrate equilibrium conditions were measured by an isochoric pressure search method. The effects of feed pressure, temperature, juice volume, and stirring speed on dehydration ratio were investigated. The dehydration ratio increased with increasing the feed pressure; the maximum dehydration ratio of 57.2% was reached at feed pressure of 4.10MPa; dehydration ratio maintained around 45.8% in the temperature range of 274.8–279.8K; the optimum orange juice volume is 80mL. The CO2 hydrate formation rate constants increased from 0.67×10−8 to 1.91×10−8mol2/(sJ) in relation to the feed pressure increasing from 1.96 to 4.10MPa. The results demonstrated that removal of water by formation of CO2 hydrate is an efficient technology for orange juice concentration.

The Prediction of Hydrate Formation Rate in the Presence of Inhibitors

The main objective of this study was to present a novel approach to access more accurate hydrate formation rate predicting models based on the combination of flow-loop experimental data with learning power of artificial neural networks. Therefore, more than 2,300 data of C1, C3, i-C4, and CO2 hydrate formation rate in the presence of two kinetic inhibitors (PVP and L-Tyrosine) and two inhibitor intensifying additives (PPO and PEO) was used. It was found that such models can be used as powerful tools, with total errors less than 2% for the developed models, in predicting hydrate formation rate in these cases.

STUDY OF CAPTURING EMITTED CO2 IN THE FORM OF HYDRATES IN A TUBULAR REACTOR

Stabilizing atmospheric CO2 concentration requires the development of novel methods for capturing it in the form of permanent reservoirs. Among the proposed methods is CO2 storage in the form of hydrate. In this study a method was established for CO2 conversion to hydrate. This method can be applied to bioethanol plants, which produce CO2 as a by-product of ethanol fermentation. In this regard, a tubular recirculating flow reactor was developed for the study of CO2 hydrate formation. The experiments were carried out at 279 K and 3.5–5 MPa to determine the rate of CO2 hydrate formation. Further, a model was developed for prediction of the rate of hydrate formation based on the mass transfer, crystallization, and thermodynamic concepts. The predicted hydrate formation rate was compared to the experimental data in order to validate the model prediction. The predicted results were in good agreement with the experimental data at different operating conditions.