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Research Article
Dissecting of Atomic Morphology of Superfine Pulverized Coal Based on X-ray Pair Distribution Function
Issue:
Volume 13, Issue 2, June 2024
Pages:
50-58
Received:
25 March 2024
Accepted:
29 April 2024
Published:
13 June 2024
Abstract: Resolving the atomic structure information of the aromatic layers in coal plays a crucial role in understanding the generation mechanisms of NOx during coal combustion and further reducing the formation of NOx from the source. This study reveals the distribution of X-ray diffraction bands of superfine pulverized coal using a high-resolution synchrotron radiation X-ray Diffraction (HRXRD) facility, discussing the distribution of atomic distances and atomic density in aromatic layers through pair distribution function (PDF) methods. Furthermore, the influences of mechanochemistry on the evolution of atomic morphology are focused on. The results show that the PDF of coal gradually stabilizes when r > 8 Å, showing the short-range order of graphite-like structure. Additionally, due to the limitations of scanning angle and X-ray energy, atomic distances in aromatic layers for coal are significantly greater than that of pure graphene. Enhanced mechanochemical effects make the peaks 1, 2, and 3 of coal PDF more similar to graphene's by condensing alkyl side chains into smaller, regular aromatic layers when the particle size decreases. With the enhancement of mechanochemical effects, coals with different metamorphic degrees exhibit different aromatic evolution patterns. The aromaticity of NMG coal first decreases and then increases, while the aromaticity of YQ coal shows the opposite trend. The results can provide deeper insights into the atomic structure of coal macromolecular, which can facilitate the advancement of novel ultra-low NOx combustion methods and support the construction of precise coal macromolecular models.
Abstract: Resolving the atomic structure information of the aromatic layers in coal plays a crucial role in understanding the generation mechanisms of NOx during coal combustion and further reducing the formation of NOx from the source. This study reveals the distribution of X-ray diffraction bands of superfine pulverized coal using a high-resolution synchro...
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Research Article
Revealing the Mechanism of O2 and Pressure Effects on the Corrosion of X80 Carbon Steel Under Supercritical CO2 Conditions
Issue:
Volume 13, Issue 2, June 2024
Pages:
59-68
Received:
24 April 2024
Accepted:
4 June 2024
Published:
13 June 2024
Abstract: Pipeline transportation is widely used due to its ability to improve the efficiency of CO2 transportation in Carbon Capture, Utilization, and Storage (CCUS). Within the transport pipelines, CO2 fluid exists in a supercritical state and often contains various impurity gases such as O2 and H2O, which can easily cause steel corrosion, affecting the safety of pipeline operations. In this investigation, we examine the corrosion behavior of X80 carbon steel within a water-saturated supercritical CO2 environment utilizing weight loss experiments, electrochemical tests, and surface analysis techniques. Furthermore, we explore the impact of pressure and oxygen on the corrosion process of X80 steel. The results indicated that X80 steel underwent severe corrosion under the experimental conditions, with FeCO3 as the primary corrosion product. Both the introduction of oxygen and an increase in pressure accelerated the steel's corrosion, and the addition of oxygen led to the formation of a new corrosion product, Fe2O3. Electrochemical test results showed that changes in pressure did not significantly alter the electrochemical corrosion characteristics of the steel, but the introduction of oxygen decreased the electrochemical reaction resistance of X80 steel. Combined with surface analysis, the following conclusions were drawn: In a 50°C supercritical CO2 environment, the anode reaction of X80 steel corrosion is the active dissolution of iron, while the cathode reaction involves the dissolution and ionization of CO2. Changes in pressure do not alter the corrosion mechanism, but the introduction of oxygen leads to oxygen corrosion reactions in the system, accelerating the anode reaction rate and thus increasing the degree of corrosion.
Abstract: Pipeline transportation is widely used due to its ability to improve the efficiency of CO2 transportation in Carbon Capture, Utilization, and Storage (CCUS). Within the transport pipelines, CO2 fluid exists in a supercritical state and often contains various impurity gases such as O2 and H2O, which can easily cause steel corrosion, affecting the sa...
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Research Article
Impedance Characteristics of Berea Sandstone Cores in the Process of CO2 Injection Displacement with Saturated Brine
Issue:
Volume 13, Issue 2, June 2024
Pages:
69-80
Received:
24 April 2024
Accepted:
4 June 2024
Published:
13 June 2024
Abstract: As an important means of CO2 geological storage leakage monitoring, resistivity monitoring technology is of great significance to the safety and stability of CCUS project. In order to study the electrical signal response rule of the evolution of CO2 saturation in the reservoir, a joint core displacement experiment system of electrochemical impedance analysis and microfocus X-ray CT was designed and constructed to simulate the process of CO2 displacement of brine in Berea sandstone cores under stratigraphic temperature and pressure conditions. The electrochemical impedance characteristics of the core-fluid system are analyzed by electrochemical impedance spectroscopy. The experimental results show that at lower temperature and pressure, it is more difficult for CO2 to invade the pore space occupied by the brine in situ, resulting in drastic changes in CO2 plane saturation along the displacement direction. With the increase of temperature and pressure, the CO2 saturation curve becomes smoother and the migration and displacement front becomes even. The Cole equivalent circuit model is used to describe the conduction mode of AC electrical signals inside the core, and the electrochemical impedance characteristic analysis focusing on the high frequency region shows that the system impedance increases with the increase of CO2 saturation, and decreases with the increase of scanning frequency. In addition, the changes of impedance characteristics in the electrochemical impedance spectroscopy not only reflect the pore structure characteristics of the core, but also reveal the evolution law of CO2 saturation in the porous medium. With the increase of CO2 saturation, the low pore space is gradually occupied by CO2, and the residual brine connectivity of the pore space as a conductive component decreases. The decrease of the internal conductive circuit leads to the rapid increase of the impedance, which is consistent with the change of resistance and capacitance when fitting the Cole equivalent circuit model.
Abstract: As an important means of CO2 geological storage leakage monitoring, resistivity monitoring technology is of great significance to the safety and stability of CCUS project. In order to study the electrical signal response rule of the evolution of CO2 saturation in the reservoir, a joint core displacement experiment system of electrochemical impedanc...
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Research Article
Application of Distributed Acoustic Sensing Technology in Pipeline Leakage Monitoring
Issue:
Volume 13, Issue 2, June 2024
Pages:
81-89
Received:
24 April 2024
Accepted:
4 June 2024
Published:
13 June 2024
Abstract: Pipeline leak monitoring is an important industrial safety measure designed to ensure the safety of liquids or gases during transportation. Distributed acoustic sensing (DAS) technology is based on the reverse Rayleigh scattering inside the fiber to reflect the change of the measured physical quantity, and has great advantages in monitoring range, environmental adaptability, transmission loss control and system stability. In this paper, the pipeline leakage monitoring technology based on distributed acoustic sensing fiber is used to study the leakage signal of small leak aperture. In order to improve the sensitivity of leakage monitoring, the optical fiber is spiral wound on the pipe section. The identification method of pipeline leakage signal based on fast Fourier transform is proposed. By analyzing the vibration of the optical fiber in the time domain and the frequency domain, the leakage signal can be accurately monitored. Pipeline leakage tests with different leak apertures were carried out, and the leakage locations were studied by energy attenuation and cross-correlation techniques. The experimental results show that the time-domain signal fluctuates obviously and the full-band energy of the frequency-domain signal increases after pipeline leakage. The increase of leakage diameter will gradually increase the signal energy, and the leakage energy will gradually move from high frequency to low frequency. The energy attenuation positioning technique can locate the leakage within the range of a single sensing unit, and determine the leakage location through cross-correlation analysis with an error of less than 3 m.
Abstract: Pipeline leak monitoring is an important industrial safety measure designed to ensure the safety of liquids or gases during transportation. Distributed acoustic sensing (DAS) technology is based on the reverse Rayleigh scattering inside the fiber to reflect the change of the measured physical quantity, and has great advantages in monitoring range, ...
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Research Article
Natural Hydrogen in the Northern Perth Basin, WA Australia: Geospatial Analysis and Detection in Soil Gas for Early Exploration
Vitaly Vidavskiy*
,
Reza Rezaee,
Nikolay Larin,
Rance Dorrington,
Martin Spivey,
Vladimir Vidavskiy
Issue:
Volume 13, Issue 2, June 2024
Pages:
90-113
Received:
21 May 2024
Accepted:
11 June 2024
Published:
25 June 2024
Abstract: The scope of this work is to empirically check and prove the practical applicability of the Primordially Hydridic Earth (PHE) concept for early exploration of the resources of naturally occurring hydrogen. With the PHE concept postulates interpreted within the local geological, tectonic, petrological and geophysical context, the reconnaissance plan, as well as the field exploration and data acquisition programs, were put together and implemented in the field. The results obtained from the surface (<1m deep) soil gas survey performed in Western Australia (WA) resulted in values of hundreds of ppm H2, including three samples with a concentration of hydrogen exceeding the gas sensor detection limit of 2,000 parts per million (ppm) (the all-Australia record). Similarly, several of the shallow soil samples used for obtaining headspace gas extracts yielded dozens % H2, which was established utilizing Gas Chromatography (GC) technology. The latter tests established the all-Australia record of 58.3% (norm.) H2 concentration from 15 m depth, being the highest reading from the area of research. At one location, a concentration of He exceeding 8,000ppm was detected in a 1m surface soil gas sample analyzed by the independent lab. The most important outcome was finding natural hydrogen where it was expected and predicted. On the other hand, H2 concentrations exceeding the natural background of 1-3ppm were not detected in the soil gas readings outside of the areas identified using the PHE concept as a theoretical foundation. It may be stated that overall, the practical application of the PHE concept along with the thoroughly planned utilization of carefully selected exploration techniques brings satisfactory results.
Abstract: The scope of this work is to empirically check and prove the practical applicability of the Primordially Hydridic Earth (PHE) concept for early exploration of the resources of naturally occurring hydrogen. With the PHE concept postulates interpreted within the local geological, tectonic, petrological and geophysical context, the reconnaissance plan...
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