Self-preservation Effect of Gas Hydrates

2021 ◽  
Vol 23 ◽  
pp. 346-355
Author(s):  
Anatoliy Pavlenko
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Experimental Studies ◽  
Interphase Surface ◽  
Quantitative Characteristics ◽  
Nonequilibrium Conditions ◽  
Water Simulation ◽  
Gas Loss ◽  
Physical And Mathematical Models ◽  
And Storage

This work was performed to improve the storage and transportation technology of gas hydrates in nonequilibrium conditions. At atmospheric pressure and positive ambient temperature, they gradually dissociate into gas and water. Simulation of the gas hydrate dissociation will determine optimal conditions for their transportation and storage, as well as minimize gas loss. Thermodynamic parameters of adiabatic processes of forced preservation of pre-cooled gas hydrate blocks with ice layer were determined theoretically and experimentally. Physical and mathematical models of these processes were proposed. The scientific novelty is in establishing quantitative characteristics that describe the gas hydrates thermophysical parameters thermophysical characteristics influence on the heat transfer processes intensity on the interphase surface under conditions of gas hydrates dissociation. Based on the results of experimental studies, approximation dependences for determining the temperature in the depths of a dissociating gas hydrate array have been obtained. Gas hydrates dissociation mathematical model is presented.

scholarly journals Rapid Gas Hydrate Formation—Evaluation of Three Reactor Concepts and Feasibility Study

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3615
Author(s):  
Florian Filarsky ◽  
Julian Wieser ◽  
Heyko Juergen Schultz
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Hydrate Formation ◽  
Synthetic Natural Gas ◽  
Operation Conditions ◽  
Gas Hydrate Formation ◽  
Gas Conditioning ◽  
And Storage ◽  
Economic Considerations ◽  
High Storage

Gas hydrates show great potential with regard to various technical applications, such as gas conditioning, separation and storage. Hence, there has been an increased interest in applied gas hydrate research worldwide in recent years. This paper describes the development of an energetically promising, highly attractive rapid gas hydrate production process that enables the instantaneous conditioning and storage of gases in the form of solid hydrates, as an alternative to costly established processes, such as, for example, cryogenic demethanization. In the first step of the investigations, three different reactor concepts for rapid hydrate formation were evaluated. It could be shown that coupled spraying with stirring provided the fastest hydrate formation and highest gas uptakes in the hydrate phase. In the second step, extensive experimental series were executed, using various different gas compositions on the example of synthetic natural gas mixtures containing methane, ethane and propane. Methane is eliminated from the gas phase and stored in gas hydrates. The experiments were conducted under moderate conditions (8 bar(g), 9–14 °C), using tetrahydrofuran as a thermodynamic promoter in a stoichiometric concentration of 5.56 mole%. High storage capacities, formation rates and separation efficiencies were achieved at moderate operation conditions supported by rough economic considerations, successfully showing the feasibility of this innovative concept. An adapted McCabe-Thiele diagram was created to approximately determine the necessary theoretical separation stage numbers for high purity gas separation requirements.

scholarly journals Method for determining the starting moment of hydrate formation on the basis of optical effects

2021 ◽  
Vol 230 ◽  
pp. 01003
Author(s):  
Nazar Pedchenko ◽  
Yuriy Vynnykov ◽  
Larysa Pedchenko ◽  
Mykhailo Pedchenko
Keyword(s):  
Gas Hydrates ◽  
Oil And Gas ◽  
Experimental Studies ◽  
Hydrate Formation ◽  
Light Sources ◽  
Interphase Surface ◽  
Laboratory Observation ◽  
Industrial Facilities ◽  
Optical Effects ◽  
Reservoir Systems

The problem is analyzed of hydrate formation in the systems of gathering and treating of oil and gas products. The methods are studied for prevention of complications associated with the gas hydrates accumulation in the pipelines and process lines. Attention is focused on the significant material costs to prevent the hydrate formation and ways to reduce them. The necessity of constant laboratory monitoring for reservoir systems at industrial facilities to determine the hydrate formation parameters has been substantiated. The need to improve the method for determining the hydrate formation parameters for complex reservoir systems based on a mixture of hydrate-forming gases has also been proved. The purpose of the work is to improve the research method of reservoir systems immediately at the facilities of products mining and treatment. The peculiarities are analyzed of the method of visual laboratory observation in the study of gas hydrates. During experimental studies, optical effects of image distortion are observed due to the formation of a gas hydrate layer in the form of a film on the interphase surface. The mechanism of their formation, as well as the processes determining them have been substantiated. Based on this effect, a method of fixing the hydrate formation initial stage (beginning of crystal growth – mass crystallization) is proposed. For increasing the informative ability of the obtained images of hydrate formation processes, it is proposed to “paint” them with the help of colored light sources, as well as to regulate the intensity and direction of illumination. A number of photos are presented, which clearly illustrate the processes described in the paper.

Technological Solutions for the Realization of NGH-Technology for Gas Transportation and Storage in Gas Hydrate Form

2018 ◽  
Vol 277 ◽  
pp. 123-136 ◽  
Author(s):  
Mykhailo Pedchenko ◽  
Larysa Pedchenko ◽  
Tetiana Nesterenko ◽  
Artur Dyczko
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Atmospheric Pressure ◽  
High Stability ◽  
Hydrated Form ◽  
Hydrate Form ◽  
Capital Costs ◽  
Large Size ◽  
Long Time ◽  
And Storage

The technology of transportation and storage of gas in a gas-hydrated form under atmospheric pressure and slight cooling – the maximum cooled gas-hydrated blocks of a large size covered with a layer of ice are offered. Large blocks form from pre-cooled mixture of crushed and the granulated mass of gas hydrate. The technology of forced preservation gas hydrates with ice layer under atmospheric pressure has developed to increase it stability. The dependence in dimensionless magnitudes, which describes the correlation-regressive relationship between the temperature of the surface and the center gas hydrate block under its forced preservation, had proposed to facilitate the use of research results. Technology preservation of gas hydrate blocks with the ice layer under atmospheric pressure (at the expense of the gas hydrates energy) has designed to improve their stability. Gas hydrated blocks, thus formed, can are stored and transported during a long time in converted vehicles without further cooling. The high stability of gas hydrate blocks allows to distributed in time (and geographically) the most energy expenditure operations – production and dissociation of gas hydrate. The proposed technical and technological solutions significantly reduce the level of energy and capital costs and, as a result, increase the competitiveness of the stages NGH technology (production, transportation, storage, regasification).

scholarly journals Microscale Processes and Dynamics during CH4–CO2 GuestMolecule Exchange in Gas Hydrates

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1763
Author(s):  
Elke Kossel ◽  
Nikolaus K. Bigalke ◽  
Christian Deusner ◽  
Matthias Haeckel
Keyword(s):  
Diffusion Equation ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Guest Molecule ◽  
Experimental Studies ◽  
Additional Term ◽  
Hydrate Dissociation ◽  
Ch4 Production ◽  
Net Zero ◽  
Gas Balance

The exchange of CH4 by CO2 in gas hydrates is of interest for the production of natural gas from methane hydrate with net zero climate gas balance, and for managing risks that are related to sediment destabilization and mobilization after gas-hydrate dissociation. Several experimental studies on the dynamics and efficiency of the process exist, but the results seem to be partly inconsistent. We used confocal Raman spectroscopy to map an area of several tens to hundreds µm of a CH4 hydrate sample during its exposure to liquid and gaseous CO2. On this scale, we could identify and follow different processes in the sample that occur in parallel. Next to guest-molecule exchange, gas-hydrate dissociation also contributes to the release of CH4. During our examination period, about 50% of the CO2 was bound by exchange for CH4 molecules, while the other half was bound by new formation of CO2 hydrates. We evaluated single gas-hydrate grains with confirmed gas exchange and applied a diffusion equation to quantify the process. Obtained diffusion coefficients are in the range of 10−13–10−18 m2/s. We propose to use this analytical diffusion equation for a simple and robust modeling of CH4 production by guest-molecule exchange and to combine it with an additional term for gas-hydrate dissociation.

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

scholarly journals Bio-Templating: An Emerging Synthetic Technique for Catalysts. A Review

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1364
Author(s):  
M. Carmen Herrera-Beurnio ◽  
Jesús Hidalgo-Carrillo ◽  
Francisco J. López-Tenllado ◽  
Juan Martin-Gómez ◽  
Rafael C. Estévez ◽  
...  
Keyword(s):  
Active Sites ◽  
Experimental Studies ◽  
Functional Materials ◽  
Inorganic Materials ◽  
Hierarchical Organization ◽  
Materials Synthesis ◽  
Energy Capture ◽  
Wide Range ◽  
Mineralization Processes ◽  
And Storage

In the last few years, researchers have focused their attention on the synthesis of new catalyst structures based on or inspired by nature. Biotemplating involves the transfer of biological structures to inorganic materials through artificial mineralization processes. This approach offers the main advantage of allowing morphological control of the product, as a template with the desired morphology can be pre-determined, as long as it is found in nature. This way, natural evolution through millions of years can provide us with new synthetic pathways to develop some novel functional materials with advantageous properties, such as sophistication, miniaturization, hybridization, hierarchical organization, resistance, and adaptability to the required need. The field of application of these materials is very wide, covering nanomedicine, energy capture and storage, sensors, biocompatible materials, adsorbents, and catalysis. In the latter case, bio-inspired materials can be applied as catalysts requiring different types of active sites (i.e., redox, acidic, basic sites, or a combination of them) to a wide range of processes, including conventional thermal catalysis, photocatalysis, or electrocatalysis, among others. This review aims to cover current experimental studies in the field of biotemplating materials synthesis and their characterization, focusing on their application in heterogeneous catalysis.

scholarly journals MATHEMATICAL MODELING OF DESTRUCTION OF FIBERGLASS-BASED THERMAL-PROTECTION MATERIAL

2020 ◽  
pp. 71-78
Author(s):  
D.Ya. Barinov ◽  
◽  
P.S. Marakhovskij ◽  
A.V. Zuev ◽  
◽  
...  
Keyword(s):  
Thermal Protection ◽  
Experimental Studies ◽  
Thermophysical Characteristics ◽  
Capsule Type ◽  
Typical Trajectory ◽  
Material Sample ◽  
Heat Shielding ◽  
Physical And Mathematical Models ◽  
The Mathematical Model ◽  
Shielding Material

The paper proposes physical and mathematical models of heat and mass transfer in fiberglass used as a destructive heat-shielding material for capsule type descent vehicles. To provide the mathematical model with the initial data, experimental studies of the thermophysical characteristics of the material and the kinetic parameters of destruction have been carried out. There has been made a simulation of the destruction of a material sample during descent in the Earth's atmosphere along a typical trajectory for various areas of the heat shield; as a result, the dependences of temperatures on the flight time and the depth of the coked layer have been determined.

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