Does Local Structure Bias How a Crystal Nucleus Evolves?

2018 ◽  
Author(s):  
Kyle Hall ◽  
Zhengcai Zhang ◽  
Christian Burnham ◽  
Guang-Jun Guo ◽  
Sheelagh Carpendale ◽  
...  
Keyword(s):  
Local Structure ◽  
Molecular Level ◽  
Hydrate Formation ◽  
Mixed Gas ◽  
Local Structures ◽  
Surrounding Environment ◽  
Gas Hydrate Formation ◽  
Significant Research ◽  
Crystal Phases ◽  
Recent Experimental Work

<p>The broad scientific and technological importance of crystallization has led to significant research probing and rationalizing crystallization processes, particularly how nascent</p> <p>crystal phases appear. Previous work has generally neglected the possibility of the molecular-level dynamics of individual nuclei coupling to local structures (e.g., that of the nucleus and its</p> <p>surrounding environment). However, recent experimental work has conjectured that this can occur. Therefore, to address a deficiency in scientific understanding of crystallization, we have</p> <p>probed the nucleation of prototypical single and multi-component crystals (specifically, ice and mixed gas hydrates). Here, we establish that local structures can bias the evolution of nascent</p> <p>crystal phases on a nanosecond timescale by, for example, promoting the appearance or disappearance of specific crystal motifs, and thus reveal a new facet of crystallization behaviour.</p> <p>Analysis of the crystallization literature confirms that structural biases are likely present during crystallization processes beyond ice and gas hydrate formation. Moreover, we demonstrate that</p> <p>structurally-biased dynamics are a lens for understanding existing computational and experimental results while pointing to future opportunities.</p>

Does Local Structure Bias How a Crystal Nucleus Evolves?

2018 ◽  
Author(s):  
Kyle Hall ◽  
Zhengcai Zhang ◽  
Christian Burnham ◽  
Guang-Jun Guo ◽  
Sheelagh Carpendale ◽  
...  
Keyword(s):  
Local Structure ◽  
Molecular Level ◽  
Hydrate Formation ◽  
Mixed Gas ◽  
Local Structures ◽  
Surrounding Environment ◽  
Gas Hydrate Formation ◽  
Significant Research ◽  
Crystal Phases ◽  
Recent Experimental Work

<p>The broad scientific and technological importance of crystallization has led to significant research probing and rationalizing crystallization processes, particularly how nascent</p> <p>crystal phases appear. Previous work has generally neglected the possibility of the molecular-level dynamics of individual nuclei coupling to local structures (e.g., that of the nucleus and its</p> <p>surrounding environment). However, recent experimental work has conjectured that this can occur. Therefore, to address a deficiency in scientific understanding of crystallization, we have</p> <p>probed the nucleation of prototypical single and multi-component crystals (specifically, ice and mixed gas hydrates). Here, we establish that local structures can bias the evolution of nascent</p> <p>crystal phases on a nanosecond timescale by, for example, promoting the appearance or disappearance of specific crystal motifs, and thus reveal a new facet of crystallization behaviour.</p> <p>Analysis of the crystallization literature confirms that structural biases are likely present during crystallization processes beyond ice and gas hydrate formation. Moreover, we demonstrate that</p> <p>structurally-biased dynamics are a lens for understanding existing computational and experimental results while pointing to future opportunities.</p>

Incipient Hydrate Formation Pressure-Temperature and Equilibrium Composition for CH4-N2-O2-THF-H2O System

2011 ◽  
Vol 84-85 ◽  
pp. 219-223
Author(s):  
Xia Gao ◽  
Qiang Wu ◽  
Bao Yong Zhang
Keyword(s):  
Hydrate Formation ◽  
Equilibrium Composition ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Formation Pressure ◽  
Mixed Gas ◽  
Gas Hydrate Formation ◽  
Three Phase ◽  
Hydrate Phase ◽  
Hydrate Formation Process

The new method for separating drained coal bed methane (CBM) is based on gas hydrate formation. The thermodynamic parameters of incipient hydrate formation for the CH4-N2-O2-THF-H2O system were carefully determined. After establishing equilibrium state of three-phase coexistence, CH4 concentrations of vapor phase and that of hydrate phase were determined by GC. The results show that the higher the THF concentration, the larger the CH4 concentration in hydrate phase and the partition coefficient. It can provide the reference for seeking the optimal promoters in the hydrate formation process for the mixed gas.

scholarly journals Advances in the Study of Gas Hydrates by Dielectric Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4459
Author(s):  
Ivan Lunev ◽  
Bulat Kamaliev ◽  
Valery Shtyrlin ◽  
Yuri Gusev ◽  
Airat Kiiamov ◽  
...  
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Dielectric Spectroscopy ◽  
Relaxation Times ◽  
Hydrate Formation ◽  
Water Molecules ◽  
Natural Gas Hydrate ◽  
Real Component ◽  
Local Structures ◽  
Gas Hydrate Formation

The influence of kinetic hydrate inhibitors on the process of natural gas hydrate nucleation was studied using the method of dielectric spectroscopy. The processes of gas hydrate formation and decomposition were monitored using the temperature dependence of the real component of the dielectric constant ε′(T). Analysis of the relaxation times τ and activation energy ΔE of the dielectric relaxation process revealed the inhibitor was involved in hydrogen bonding and the disruption of the local structures of water molecules.

scholarly journals Thermodynamic Modeling Of Electrolytic Solutions of Ionic Liquids for Gas Hydrates Inhibition Applications

2021 ◽  
Vol 81 (2) ◽  
pp. 110-123
Author(s):  
Ali Qasim ◽  
Jeremy Heurtas ◽  
Muhammad Saad Khan ◽  
Bhajan Lal ◽  
Azmi Mohammad Shariff ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Gas Hydrates ◽  
Oil And Gas ◽  
Binary Solution ◽  
Hydrate Formation ◽  
Absolute Error ◽  
Economic Loss ◽  
Average Absolute Error ◽  
Mixed Gas ◽  
Gas Hydrate Formation

The formation of hydrates in oil and gas transmission pipelines can cause blockage inside them and disrupt the normal flow. It may cause safety problems along with economic loss. To avoid these problems, it is necessary to have knowledge about gas hydrate formation. In this regard, hydrate liquid vapor equilibrium (HLVE) modeling can prove to be of significance as it predicts the phenomenon accurately. Dickens and Quinby-Hunt model is used to predict HLVE points. The experimental data has been obtained from open literature concerning inhibition of gas hydrates. The electrolytic binary solution mixtures of ionic liquids and quaternary ammonium salts (QAS) with commercial hydrate inhibitors have been taken into consideration. Methanol and mono ethylene glycol (MEG) are commercially used inhibitors. The gases forming hydrates include CO2, CH4 and mixed gas (CO2/CH4/N2). The experimental results are compared with the results obtained through modeling. The results show the applicability of the model as in case of QAS+MEG solution mixture hydrates with CO2, it shows a good fit. The HLVE findings by model for CH4 hydrates with EMIM-Cl+MEG solution mixture showed an average absolute error of less than 1% which is acceptable. The binary solution mixtures of NaCl+MEG, NaCl+MeOH and CaCl2+MeOH with tertiary gas mixture rich in CO2 were also modeled to find and compare the HLVE points from literature. It is found that the selected model is more suitable to be used in low pressure conditions and at high pressure, average absolute error (AAE) between experimental and modeling values is also high. It shows the suitability of the model and it can be further used in case of ionic compounds to predict hydrate inhibition behavior.

scholarly journals Phase behavior study on gas hydrates formation in gas dominant multiphase pipelines with crude oil and high CO2 mixed gas

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jai Krishna Sahith Sayani ◽  
Srinivasa Rao Pedapati ◽  
Bhajan Lal
Keyword(s):  
Crude Oil ◽  
Phase Behavior ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Multiphase System ◽  
Statistical Regression ◽  
Mixed Gas ◽  
Experimental Conditions ◽  
Temperature Variance ◽  
Gas Hydrate Formation

Abstract This research is focused on understanding the phase behavior of gas hydrate formation in the gas dominant multiphase pipelines containing mixed gas with high CO2, crude oil, and deionized water. The experimental conditions are in the pressure range of 3–7 MPa with water cut as 20% of the volume. Initially, the effect of high CO2 content in natural gas on the phase boundary conditions of hydrates is studied through simulation (CSMGEM software) and experiments. Later, an additional phase of crude oil was introduced, with 15% of the volume to study the multiphase system. From the experimental analysis, thermodynamic equilibrium conditions were found, and the hydrate-liquid–vapor-equilibrium (HLVE) curves were drawn. The phase behavior is comprehended by comparing the HLVE curves of pure and multiphase systems. It is found that the high CO2 content tends to promote the gas hydrate formation. Based on the results, temperature variance and enthalpy of formation were calculated for the multiphase system. With a difference of 1.32 average temperature variance, the multiphase system exhibits inhibition. A basic statistical regression model was made to predict the gas hydrate formation in multiphase transmission pipelines. This work helps in understanding the effect of a new phase on gas hydrate formation.

SDS Effect on CH4/N2/O2 Hydrate Formation Rate for CMM Separation and Storage

2011 ◽  
Vol 201-203 ◽  
pp. 471-475 ◽  
Author(s):  
Qiang Wu ◽  
Xia Gao ◽  
Bao Yong Zhang
Keyword(s):  
Formation Rate ◽  
Hydrate Formation ◽  
Mixed Gas ◽  
High Pressure Cell ◽  
Hydration Rate ◽  
Coal Mine Methane ◽  
Experimental Systems ◽  
Gas Hydrate Formation ◽  
And Storage ◽  
Metal Wall

The new methods for separating, storing and transporting drained coal mine methane (CMM) is based on gas hydrate formation. The kinetic hydration process is studied experimentally in detail for two kinds of synthesized CMM with three concentratons of SDS solution. The hydration rates in six experimental systems are calculated using the self-established model to compare the effect of SDS. The results show that the establised model can precisely calculate the hydration rate; SDS decreases the gas hydration rate. This is due to the reason that SDS in the hydrate growth stage, can strengthen the hydrogen bond of water molecules, and be absorbed to the metal wall of the high pressure cell, the SDS membrane can react with mine gas and form crystal nucleus, thus, the hydrate formation rate is raised. It can provide the reference for seeking the optimal surfactants in the hydrate formation process for the mixed gas.

scholarly journals Infrared spectroscopy on the role of surfactants during methane hydrate formation

RSC Advances ◽  
2017 ◽  
Vol 7 (62) ◽  
pp. 39109-39117 ◽  
Author(s):  
Florian Rauh ◽  
Jens Pfeiffer ◽  
Boris Mizaikoff
Keyword(s):  
Infrared Spectroscopy ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Molecular Level ◽  
Hydrate Formation ◽  
Gas Hydrate Formation

Studies on the role of surfactants at a molecular level during gas hydrate formation via in situ fiberoptic infrared spectroscopy.

The Presence of Additive Mixtures (THF/SDS) on Carbon Dioxide Rich Gas Mixture Hydrate Formation and Dissociation Conditions

2016 ◽  
Vol 1133 ◽  
pp. 639-643
Author(s):  
Qazi Nasir ◽  
Bhajan Lal ◽  
Lau Kok Keong
Keyword(s):  
Graphical Method ◽  
Sodium Dodecyl ◽  
Hydrate Formation ◽  
Equilibrium Temperature ◽  
Formation Processes ◽  
Mixed Gas ◽  
Gas Hydrate Formation ◽  
Speed Up ◽  
Temperature And Pressure ◽  
And Storage

Besides other application of clathrate hydrates, hydrate-based CO2capture and storage are potentially important where additives are commonly used to speed up the hydrate formation processes in order to gain on scientific, technological and economic interest. In this work combination of additives such as tetrahydrofuran and sodium dodecyl sulphate (THF/SDS) on mixed gas hydrate formation and dissociation condition have been investigated using a graphical method. The measurements were carried out at temperature and pressure range of (265 to 300) K and (1 to 5) MPa. The presence of additive 3 mol % THF has drastically increased in the hydrate stability region while with the combination of SDS + THF lower the hydrate equilibrium temperature marginally.

Thermodynamic Modelling of Gas Hydrate Formation in the Presence of Inhibitors and the Consideration of their Effect

2014 ◽  
Vol 14 (1) ◽  
pp. 45
Author(s):  
Peyman Sabzi ◽  
Saheb Noroozi
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Low Temperatures ◽  
Hydrate Formation ◽  
Transportation Systems ◽  
Flow Lines ◽  
Main Approach ◽  
Efficient Inhibitor ◽  
System A ◽  
Gas Hydrate Formation

Gas hydrates formation is considered as one the greatest obstacles in gas transportation systems. Problems related to gas hydrate formation is more severe when dealing with transportation at low temperatures of deep water. In order to avoid formation of Gas hydrates, different inhibitors are used. Methanol is one of the most common and economically efficient inhibitor. Adding methanol to the flow lines, changes the thermodynamic equilibrium situation of the system. In order to predict these changes in thermodynamic behavior of the system, a series of modelings are performed using Matlab software in this paper. The main approach in this modeling is on the basis of Van der Waals and Plateau's thermodynamic approach. The obtained results of a system containing water, Methane and Methanol showed that hydrate formation pressure increases due to the increase of inhibitor amount in constant temperature and this increase is more in higher temperatures. Furthermore, these results were in harmony with the available empirical data.Keywords: Gas hydrates, thermodynamic inhibitor, modelling, pipeline blockage

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