Vitrinite Coal Research Articles

Influence of elevated temperature and gas atmosphere on coke abrasion resistance. Part one: Pilot oven cokes

A novel approach was developed to examine coke abrasion resistance in-situ at temperatures of up to 950 °C and in a controlled gas atmosphere using rotational tribological testing. The originality of this approach lay in the ability to apply tribological testing to the porous coke surface at elevated temperatures under a controlled inert or CO2 reactive atmosphere. Coke wear characteristics were quantified via (i) the application of advanced microscopy and image analysis techniques, and (ii) analysis of the coefficient of friction (COF) during tribological testing.Two pilot oven cokes were examined in this study, which were generated from single coking coals of similar rank but different petrographic composition. The cokes tested showed a deterioration in abrasion resistance even at 400 °C, and this was accentuated at 950 °C.The COF and the severity of the wear as a function of temperature and gas atmosphere were markedly different between the two cokes. Coke C396 from a mid-to-low vol, medium vitrinite coal showed no statistically significant differences between the wear severity results recorded following room temperature testing and high temperature testing in a CO2 environment. Conversely, the more reactive coke C426 with a higher parent coal inertinite content showed clear differences in the extent of abrasive wear at room temperature and at high temperature in both inert and reactive gas atmospheres.This suggests that the reduction in abrasion resistance at elevated temperatures is accentuated in the coke with the highest coke reactivity index (CRI) and the highest content of inertinite maceral derived components (IMDC). Our research has shown that at room temperature, the IMDC show greater resistance to abrasion than the reactive maceral derived components (RMDC). This has implications for understanding the relevance of room temperature testing to the abrasion resistance of coke under practical blast furnace operation conditions. For example, a coke from a coal or blend with a comparatively high inertinite content may show lower resistance to abrasion in the blast furnace than would be expected from tumble drum indices. Larger sample numbers and cokes from a variety of single coals need to be tested in further work to verify these assertions.Finally, a novel method using micro-CT image analysis was developed to examine the wear path generated at the coke surface during tribological testing. The purpose of this was to assess the extent of the abrasive wear by comparing the rendered micro-CT images before and after tribological testing. A colour gradient scale was used to facilitate the quantitative assessment, whereby the colour of each voxel was based on the distance from the nearest voxel that is associated with solid phase.As expected, the specific surface area (SSA) calculated for the upper 1 mm of each sample decreased following tribological testing due to the generation of a wear track which is smoother than the initially rough, porous coke surface. In the C426 coke type examined, the SSA decreased the most for the sample tested in an argon atmosphere at 950 °C, matching the COF and quantified wear severity results, which showed there was a notable increase in abrasive wear to this coke as the temperature was raised from room to elevated temperature.Coupling this method of analysis with 3D visualisation techniques in further work would provide a powerful approach to examine and quantify mechanisms of coke surface breakage and the microstructural and/or microtextural features responsible for the breakage.

Kinetic characteristics and reactive behaviors of HSW vitrinite coal pyrolysis: A comprehensive analysis based on TG-MS experiments, kinetics models and ReaxFF MD simulations

Currently it is highly desired to study coal pyrolysis based on weight loss behavior, mathematical model of pyrolysis kinetics and advanced multi-scale molecular simulations to realize clean utilization of coal. This work presents a comprehensive analysis of HSW vitrinite coal pyrolysis based on thermogravimetric mass spectrometry (TG-MS) experiments, kinetics models and reactive force field molecular dynamics (ReaxFF MD) simulations. The weight loss and gas release behavior of HSW vitrinite coal at different heating rates was investigated by TG-MS. The kinetic parameters of coal pyrolysis were analyzed by Coats-Redfern model and distributed activation energy model (DAEM). The pyrolysis reactive behaviors and thermal decomposition process of HSW vitrinite coal was observed and analysis with ReaxFF MD simulations at atomic scale. The results show that the weight loss rate of pyrolysis decreased with increased heating rate. The trend of higher heating rate delayed the release of pyrolysis gas was consistent with TG results. The pyrolysis activation energy increases from 12.30 to 25.83 kJ/mol with further pyrolysis stage by Coats-Redfern model, and from 59.85 to 328.24 kJ/mol with higher carbon conversion hate by DAEM model. The results of ReaxFF MD simulations give complex initial chemical process of coal pyrolysis process, which agrees with the actual and expected coal pyrolysis process. Also the secondary reaction of tar in later stage of pyrolysis is observed clearly via ReaxFF MD simulations.

Acid demineralization effect on the sonication-assisted solvent extraction of vitrinite coal of the Powder River Basin

Solvent-extraction of economic low-grade coals has gained recent interest as a way to produce new feedstocks for the synthesis of advanced carbon materials including polymers. Herein, we report the effect of coal demineralization by hydrochloric acid treatment on the sonication-assisted extraction of subbituminous coal from the Powder River Basin in Wyoming, USA at room temperature and the analysis of the initial and residual coals by FT-IR and solid-state 13C NMR. The applied demineralization reduced ash content from 9.9% to 7% without any notable change in the coal composition or structure. Despite leaving the mineral matter in the coal, the demineralization significantly increased the extraction yield for all applied solvents, for ethylenediamine from 8.1% to 15.2%, for pyridine from 4.9% to 12.4%, and acetone from 1.1% to 4.5%.

On the possibilities to apply indices of industrial coal-rank classification to determine hazardous characteristics of workable beds

Purpose is to identify behaviour of the graded indices as well as their correspondence to grades, groups, and subgroups of similar coal metamorphic degrees to determine hazardous characteristics of workable beds while mining. Methods. Rank scale and changes in the graded index values help define the coal grades, groups, and subgroups having comparable characteristics as well as ultimate composition of organic mass. Coal ranking involves the intensified metamorphism manifestation in the process of transition from lignite to black coal, and then to anthracite. Findings. Analysis of the total of the fusainized components has shown that coal grading is within less than 10 and more than 69% range. However, in the majority of cases its values are recommended as those being less than 39 or more than 40% which prevents from determination of reliable correlation relationships. Free heaving ratio is considered together with the plastic layer thickness making it possible to determine quantitively only LF, LS, LC, and L grades. In terms of vitrinite response index, being 0.8-1.4%, LS, LC, and L grades may be considered as coal in the central ranking series. The fact supports available changes in the internal structure. Originality. Behaviour of the graded indices of industrial coal-rank classification has been determined to identify hazardous characteristics of workable beds while mining. Practical implications are the possibilities to improve the regulatory system for safe mining of workable beds while determining differences in characteristics of vitrinite coal and fusainized coal.

Palynology, organic petrology and geochemistry of the Bell coal bed in Western Kentucky, Eastern Interior (Illinois) Basin, USA

The Bell coal bed is one of the stratigraphically oldest coals (Atokan, Duckmantian) in the Illinois Basin that has been commercially mined and occurs near the Morrowan-Atokan boundary, which was a time of significant lithologic change in the basin. The Bell coal occurs as a series of discontinuous pods, in contrast to younger (Asturian) coals in the basin that are thicker and more extensive in occurrence. Thirty-two samples of coal and carbonaceous shale, collected from surface mine, outcrop, and drill core locations were analyzed geochemically, petrographically and palynologically to ascertain the origin of the Bell coal bed in western Kentucky.The Bell coal exhibits a great deal of variability in thickness and composition, both temporally and spatially. Based on ash yields, the Bell coal consists of intercalated layers of coal (≤25% ash), impure coal (>25 to <50% ash) and carbonaceous shale (≥50% ash). Sulfur contents vary significantly, from 0.2% to 10.0%. Petrographically, the Bell coal is mainly a high vitrinite coal (>80%, mmf), with telovitrinite occurring more frequently than detrovitrinite and gelovitrinite. Certain layers, however, contain elevated amounts of liptinite and inertinite. Among the inertinite macerals, examples of both fire (e.g., fusinite) and degradation (e.g., macrinite) origin are evident. Samples with elevated amounts of inertinite are commonly, though not exclusively, high in ash, indicating that some of the inertinite may be of allochthonous origin.Palynologically, the Bell coal is dominated by arborescent lycopod spores (avg. >70%), occurring primarily as Lycospora, with some samples containing increased proportions of spores and pollen from other Pennsylvanian plant groups. Samples with more heterogenous palynofloras commonly have elevated ash yields, indicating that some portion of the assemblages may be also of allochthonous origin.Collectively, the Bell coal is interpreted to have formed from a series of small, disconnected paleomires that were planar and topogenous with paleotopography having an influence on peat development. A planar, topogenous origin helps to explain the highly variable ash yields and sulfur contents. Accumulating peat, principally from arborescent lycopod source material, was mainly well-preserved, but punctuated with intervals marked by sediment influx, the development of more heterogeneous palynofloras and degradation and oxidation of the surficial peat by both biologic (decay) and abiotic (fire) processes.

Study on microstructural changes of coal after methane adsorption

This study analyzes the microstructure and deformation rule after methane adsorption on coal by scanning electron microscopy (SEM) and computed tomography (CT) scanning of microscopic coal samples. Studies have shown that coal is a natural rock composed of vitrinite coal matrix and clay mineral. After methane adsorption, coal undergoes non-uniform expansion deformation. This occurrence prompts coal density to decrease and then increase, causing the density distribution of coal to become highly concentrated. During swelling after adsorption, the effects of deformation and expansion on coal structures become stronger than that of mutual squeezing. Under low adsorption pressure, coal expansion deformation is more likely to crack the pore structure of the original coal to acquire space for expansion. When the adsorption pressure increases, compression becomes mainly concentrated in the low-density region; as adsorption pressure continues to increase, expansion deformation occurs from high-density to low-density regions. The methane adsorption properties of coal are related to its pore structure. Adsorption and swelling mainly occur in the region where the pore structure is unfilled or filled with clay minerals. Expansion deformation conforms to the Langmuir equation; the region without pore structure development exhibits no swelling; the deformation degree and range of the pore structure and clay mineral mixing zone exhibit increase volatility. Overall, results reveal a microstructural change after methane adsorption.

Особливості та основні закономірності зміни петрографічного складу вугілля московського ярусу Лозовського вугленосного району Донбасу

There are Identified petrogenetic features of coal of Moscow stage, there are installed stratigraphic and lateral change of petrographic composition and degree of restored. The problem of providing the country's fuel and energy resources through the development of the coal industry Lozovsky Western Donbass coal district. The basic criteria that determine the direction of the use of coal in industry and determining their consumer value, are the degree of metamorphism, petrographic composition and the degree of recovery. Rational use of coal provides for the identification of regional or provincial "their features that require detailed, finer petrogenetic study of the characteristics and the degree of metamorphism of coal. Is established that the composition and quality of coal is mainly controlled by their petrogenetic features. In addition, summarizing all available data on gross petrographic composition of coals, which were obtained during exploration. Established that the content basic groups on certain packs of microcomponents and carbon layers varies within wide limits. Petrographic composition of coal seams highly variable. Thus, the content varies according to the group of vitrinite coal seam thickness from 53.0 to 95.5%. Key words: petrography composition, restored, carbonization, Vitrinite, Inertinit, Leiptinit.

Modification of vitrinite coals in a low-temperature oxygen plasma

Transformations in the organic matter of vitrinites in coals of various ranks as a result of their interaction with oxygen activated in an RF field were characterized using IR spectroscopy and solvent extraction.

The Shape of Pulverized Bituminous Vitrinite Coal Particles

The shape of pulverized bituminous coal particles (vitrinites) was determined by optical and laser light scattering. Vitrain samples were collected from obvious tree remains located in the ceilings of two Appalachian coal mines. Wet sieving produced narrow size cuts. The particles were determined to be oblong or blocky in shape, with average length-to-width ratio of 1.7 and sphericity of 0.78. They were analogous in shape to a square ended, rectangular “house brick”. The two bituminous coals and different size cuts of each coal had essentially the same shape parameters. Characteristic heating times and terminal velocities were higher by 22 and 20%, respectively compared to spherical particles.

GEOLOGICAL CONTROLS ON EXPLOITABLE COAL SEAM GAS DISTRIBUTION IN QUEENSLAND

Methane is present in all coals, but a number of geological factors influence the potential economic concentration of gas. The key factors are (1) depositional environment, (2) tectonic and structural setting, (3) rank and gas generation, (4) gas content, (5) permeability, and (6) hydrogeology. Commercial coal seam gas production in Queensland has been entirely from the Permian coals of the Bowen Basin, but the Jurassic coals of the Surat and Clarence-Moreton basins are poised to deliver commercial gas volumes.Depositional environments range from fluvial to delta plain to paralic and marginal marine—coals in the Bowen Basin are laterally more continuous than those in the Surat and Clarence-Moreton basins. The tectonic and structural settings are important as they control the coal characteristics both in terms of deposition and burial history. The important coal seam gas seams were deposited in a foreland setting in the Bowen Basin and an intracratonic setting in the Surat and Clarence-Moreton basins. Both of these settings resulted in widespread coal deposition. The complex burial history of the Bowen Basin has resulted in a wide range of coal ranks and properties. Rank in the Bowen Basin coal seam gas fields varies from vitrinite reflectance of 0.55% to &gt;1.1% Rv and from Rv 0.35-0.6% in the Surat and Clarence-Moreton basins in Queensland. High vitrinite coals provide optimal gas generation and cleat formation. The commercial gas fields and the prospective ones contain coals with &gt;60% vitrinite.Gas generation in the Queensland basins is complex with isotopic studies indicating that biogenic gas, thermogenic gas and mixed gases are present. Biogenic processes occur at depths of up to a kilometre. Gas content is important, but lower gas contents can be economic if deliverability is good. Free gas is also present. Drilling and production techniques play an important role in making lower gas content coals viable. Since the Bowen and Surat basins are in a compressive regime, permeability becomes a defining parameter. Areas where the compression is offset by tensional forces provide the best chances for commercial coal seam gas production. Tensional setting such as anticline or structural hinges are important plays. Hydrodynamics control the production rate though water quality varies between the fields.

Capillary viscometry of a New Zealand coal at high pressures and shear stresses

The practicality of using a capillary viscometer for measuring the flow properties of coal is established. Sources of error, particularly viscous heating effects and thermal lags, are discussed and precautions are outlined. Foaming is thought to have been prevented over much of the capillary. Some results obtained with a high vitrinite coal are presented for temperatures 679–683 K, and pressures up to 77 MPa. The coal viscosity is highly temperature dependent, and also apparently dependent on shear rate.