Influence Of Coal Properties Research Articles

Coal Structure Characteristics of the 2# Coal Seam in the Jiaozuo Mining Area and Its Geological Dependence.

To clarify the coal structure, spatial distribution, and controlling factors of the 2# coal seam in Jiaozuo mining, the drilling coal samples were collected to observe the coal type and coal structure. The coal macerals were identified by a MPVSP microscope photometer, and the spatial characteristics of the coal structure were obtained through interpreting deep lateral resistivity logging, natural gamma ray logging, density logging, and acoustic logging curves. The influence of coal properties, burial depth, geological stress, and faults on the coal structure were discussed correspondingly. The results exhibit that granulitic-mylonite coal was most developed in the 2# coal seam, followed by primary coal and cataclastic coal; the coal type was dominated by semibright coal, followed by clarain and semidull coal. Granulitic-mylonite, cataclastic, and primary coals were the main components of clarain, semibright coal, and semidull coal, respectively. Higher vitrinite and organic matter contents were conducive to the development of granulitic-mylonite. The coal structure combinations were spatially varied, and the granulitic-mylonite combinations were the most common. Granulitic-mylonite coal was developed in the east and south parts of the study area, and the coal structure was fragmented with a greater burial depth and larger thickness. The geological stress is the fundamental cause of coal structure damage as well as the cutting of faults.

Biogeochemical Controls on Methane Generation: A Review on Indian Coal Resources

Coal bed methane (CBM) extraction has astounding effects on the global energy budget. Since the earliest discoveries of CBM, this natural gas form has witnessed ever-increasing demands from the core sectors of the economy. CBM is an unconventional source of energy occurring naturally within coal beds. The multiphase CBM generation during coal evolution commences with microbial diagenesis of the sedimentary organic matter during peatification, followed by early to mature thermogenic kerogen decomposition and post-coalification occurrences. Indeed, the origin of the CBM and, moreover, its economically valuable retention within coal seams is a function of various parameters. Several noticeable knowledge gaps include the controls of coal make-up and its physico-chemical position on the CBM generation and genetic link through fossil molecular and stable isotopic integration with the parent coal during its evolution. Therefore, this manuscript reviews the origin of CBM; the influences of coal properties and micropetrographic entities on CBM generation and storage; and its genetic molecular and stable isotope compositions in India and the world’s major coal reservoirs. Moreover, analyses of and outlooks on future development trends in the exploration, production, and application of coalbed methane are also addressed. Finally, as India has the fifth largest proven coal reserves, this brief review of the recent CBM discoveries and developments provides a plausible scope for microbially enhanced CBM production from these basins.

Influences of Coal Properties on the Principal Permeability Tensor during Primary Coalbed Methane Recovery: A Parametric Study

Coal permeability is intrinsically anisotropic because of the cleat structure of coal. Therefore, coal permeability can be denoted by a second-order tensor under three-dimensional conditions. Our previous paper proposed an analytical model of the principal permeability tensor of coal during primary coalbed methane (CBM) recovery. Based on this model, 18 modeling cases were considered in the present study to evaluate how the principal permeabilities were influenced by representative coal properties (the areal porosity, the internal swelling ratio, and the Young modulus) during primary CBM recovery. The modeling results show that with regard to the influences of the areal porosity on the principal permeabilities, an increase in cleat porosity reduces the sensitivity of each principal permeability to pore pressure change. The magnitudes of the principal permeabilities are positively proportional to the internal swelling ratio. The principal permeabilities thus tend to monotonically increase with a depletion in the pore pressure when the internal swelling ratio increases. Because the internal swelling ratio represents the extent of gas-sorption-induced matrix deformation, an increase in the internal swelling ratio increases desorption-induced matrix shrinkage and thus induces an increase in permeability. The principal permeabilities are positively proportional to the isotropic principal Young moduli and the synchronously changing anisotropic principal Young moduli. On the other hand, the principal Young modulus within the plane of isotropy influences the principal permeabilities within this plane in diverse patterns depending on both the dip angle of the coalbed and the pitch angle of the cleat sets. The principal permeability perpendicular to the plane of isotropy is positively proportional to this principal Young modulus, and this correlation pattern is independent of both the dip angle and pitch angle.

Impact of the Multihole Wall Air Coupling with Air Staged on NOx Emission during Pulverized Coal Combustion

Air-staged combustion is one of the most sophisticated and effective technologies for reducing NOx emission during pulverized coal combustion. However, it may also result in problems of high-temperature corrosion, slagging, and high-imperfect/incomplete combustion loss. In order to prevent these problems, the multihole wall air coupling with air-staged technology (MH&AS) has been developed. The aim of this work is to investigate the impact of MH&AS on NOx emission by applying a laboratory scale of a MH&AS furnace. The results show that there existed an optimal multihole wall air ratio to significantly reduce the NOx emission. For example, with burner air ratios of 0.6, 0.7, 0.8, and 0.9, the corresponding optimal multihole wall air ratios were 0.100, 0.075, 0.050 and 0.025, respectively. The air distribution mode with a smaller burner air ratio and its optimal multihole wall air ratio were more conducive for NOx reduction. Furthermore, the influence of coal properties on NOx emission was also evaluated. T...

Influence of Coal Properties on the Gross Calorific Value and Moisture-Holding Capacity

Analysis of the composition, structure, and properties of 63 samples of Ukrainian, Russian, and United States coal clarifies their influence on the gross calorific value in the wet and dry ash-free states and the maximum moisture content. Quantitative formulas are obtained for the influence of the petrographic characteristics on the gross calorific value and moisture-holding capacity of coal from different sources. On that basis, those parameters may be calculated with high precision. The proposed formulas permit methodological recommendations in calculating the gross calorific value in the wet ash-free state. This is important in speeding the passage of imported coal through customs.

Influence of coal properties on the performance of fixed-bed coal-burning braziers

Informal fixed-bed coal-burning braziers are used extensively in low-income communities of South Africa for space-heating and cooking needs. An investigation was carried out on the effects of coal moisture content and coal quality on the thermal and emissions performance of domestic coal-burning braziers in three field-procured braziers (with three different air ventilation rates), using the bottom-lit updraft (BLUD) and top-lit updraft (TLUD) ignition methods. Results showed that an increase in coal moisture content (from 2.4 wt.% to 8.6 wt.%) led to 18% and 30% decreases in fire-power when using the TLUD and BLUD methods, respectively. The combustion efficiency increased by 25% with an increase in moisture content. Measured carbon monoxide (CO) emission factors increased with an increase in moisture content, while carbon dioxide (CO2) emission factors remained unchanged. The use of A-grade coal resulted in a 49% increase in PM emissions compared with D-grade coal at high ventilation rates, despite no statistically significant differences (p > 0.05) in CO and CO2 emission factors produced between coal grades.

MICROELEMENTS INFLUENCE ON COAL OXIDATION AND THE ENVIRONMENTAL POLLUTION IMPLICATIONS

The spontaneous combustion of coal or self-oxidation is a phenomenon encountered both in underground mines and coal deposits on the surface, which results from heating the carbonaceous materials by slow oxidation that may occur only through the passage of air (created by air depression). Coal oxidation process generates oxidation products which are also an environmental problem. If we consider the CO2 or CO, their composition depends on the coal properties and other factors from the process. This paper aims to highlight the influence of coal properties and the constituent elements over the oxidation and self-oxidation resulted products and also to highlight their implications for environmental pollution and for the occupational health and safety field.

Investigating the combustion characteristic temperature of 28 kinds of Chinese coal in oxy-fuel conditions

Oxy-fuel combustion is widely considered to be the most promising potential CO2 capture technology. In this study, the combustion characteristic temperatures of 28 kinds of Chinese coals were investigated under three O2 concentrations of oxy-fuel through the non-isothermal thermo-gravimetric analysis. Three characteristic temperatures (ignition temperature, temperature at the maximum reactivity rate, and burnout temperature) were obtained from the experimental curve. The pulverized coal was also described through proximate analysis and ultimate analyses. The relationship between coal properties and characteristic temperature was investigated with the linear fitting method. Furthermore, the influences of coal properties on oxy-coal combustion were studied according to the close link between two slopes under different O2 concentrations. Similarly, the influences of oxidation regimes can be inferred by comparing the trends of characteristic temperature under various O2 concentrations. The mechanisms were studied in detail by analysing the carbon crystal structure and the ash element. Finally, the coal easy to be affected by O2 concentration was identified, and the main control regimes under different conditions were distinguished. The research results show important significance in the industrial application of oxy-fuel combustion technology.

Adsorption Behavior of CO2in Coal and Coal Char

Recent interest in sequestration of carbon dioxide (CO2) in gasified coal seam (i.e., post-underground coal gasification sites) has created a need to understand the coal properties, specifically, the adsorption behavior of CO2 on gasified coal. In the present study, the CO2 excess adsorption isotherms were determined for four coal samples of different characteristics based on the volumetric method. Further, coal chars from a coking coal and a non-coking coal (within the studied samples) were investigated for their CO2 adsorption capacity. The coal samples of size 22–32 mm were pyrolyzed in a drop-tube furnace at 800 and 1000 °C with a heating rate of approximately 2.5 °C s–1 under an inert atmosphere. Measurements were performed up to a pressure of 65 bar for all of the studied samples. Experiments were carried out at an isothermal temperature of 45.5 °C. The influence of coal properties on adsorption was also studied and compared to the literature data. Behavior of adsorption capacities was analyzed as a...

Influence of coal properties on the co-combustion characteristics of low-grade coal and city mud

<div> <p>In this paper, the effects of the mixing ratio and particle size of coal were investigated using a thermogravimetric analysis (TGA). A method of Achar-Brindley-Sharp-Wendworth (ABSW) was applied to a simultaneous calculation of the kinetic parameters (including the apparent activation energy, the reaction order and the frequency factor). Meanwhile, this study also revealed that both the burning performance and the characteristic parameters improved when sludge mixing ratio was smaller (10 wt.%). The ignition temperature advanced with an increase of the sludge proportion, while the combustion characteristic index dropped. As the sludge mixture ratio rose to 70 wt.%, the DTG curve reached three peaks at 293 °C, 580 °C and 748 °C Decreasing the coal particle size led to the advancement of the devolatilization, fixed carbon burning stage and maximum weight loss rate, and the reduction of the corresponding temperature. Additionally, the apparent activation energy and frequency factor of the mixture reduced when the proportion of the sludge mixing ratio went up. Also, the experiment results indicated that with the decline of the particle size distribution of coal, the apparent activation energy followed a downward trend, while the frequency factor increased.</p> </div> <p> </p>

Slag Behavior in Gasifiers. Part I: Influence of Coal Properties and Gasification Conditions

In the entrained-flow gasifiers used in integrated gasification combined cycle (IGCC) plants, the majority of mineral matter transforms to liquid slag on the wall of the gasifier and flows out the bottom. However, a small fraction of the mineral matter is entrained (as fly ash) with the raw syngas out of the gasifier to downstream processing. This molten/sticky fly ash could cause fouling of the syngas cooler. To improve gasification availability through better design and operation of the gasification process, a better understanding of slag behavior and the characteristics of the slagging process is needed. Char/ash properties, gas compositions in the gasifier, the gasifier wall structure, fluid dynamics, and plant operating conditions (mainly temperature and oxygen/carbon ratio) all affect slagging behavior. Because coal has varying ash content and composition, different operating conditions are required to maintain the slag flow and limit problems downstream. In Part I, we review the main types and the operating conditions of entrained-flow gasifiers and coal properties used in IGCC plants; we identify and discuss the key coal ash properties and the operating conditions impacting slag behavior; finally, we summarize the coal quality criteria and the operating conditions in entrained-flow gasifiers. In Part II, we discuss the constitutive modeling related to the rheological studies of slag flow.

Influence of Combustion Conditions and Coal Properties on Physical Properties of Fly Ash Generated from Pulverized Coal Combustion†

To develop combustion technology for upgrading the quality of fly ash, the influences of the coal properties, such as the size of pulverized coal particles and the two-stage combustion ratio during the combustion, on the fly ash properties were investigated using our test furnace. The particle size, density, specific surface area (obtained by the Blaine method), and shape of fly ash particles of seven types of coal were measured. It was confirmed that the size of pulverized coal particles affects the size of the ash particles. Regarding the coal properties, the fuel ratio affected the ash particle size distribution. The density and shape of the ash particles strongly depended on their ash size. Our results indicated that the shape of the ash particles and the concentration of unburned carbon affected the specific surface area. The influence of the two-stage combustion ratio was limited.

Impact of coal properties on coal combustion by-product quality: examples from a Kentucky power plant

Coal properties impact the quality of coal combustion by-products (CCBs). Tracking impacts can often be difficult, particularly in the eastern United States, because utilities use blended coal feeds to meet their quality specifications. To circumvent this problem, we made arrangements for a single seam/single mine coal to be burned at a 220-MW wall-fired boiler. The feed coal is a medium sulfur, high volatile A bituminous Dean (Fire Clay) seam from Knox County, eastern Kentucky. The coal was mined over a 2-week period in order to supply the utility with sufficient fuel for a 2-day run. The coal was sampled form one location (as a whole channel and benches at the mine), as the shipped coal at the power plant, and as a pulverized coal prior to injection into the boiler. The pulverizer reject, commonly called “pyrites” by utilities, was also sampled. Fly ash was sampled from the economizers, two rows of mechanical hoppers and four rows of electrostatic precipitator (ESP) hoppers. Bottom ash also was sampled. Analyses on the mine and plant samples include, as appropriate, proximate/ultimate/sulfur forms/heating value, major oxides, trace elements, X-ray diffraction, and petrographic composition. The influence of coal properties on fly ash properties in this isolated case will be discussed. While specially arranged burns, such as for this study, are not representative of the reality of coal purchasing and coal combustion in the eastern US, attempts to follow a single coal through the process can be instructive for the purposes of understanding the origin and fate of trace elements in combustion.

Impact of coal properties on coal combustion by-product quality: examples from a Kentucky power plant*1

Coal properties impact the quality of coal combustion by-products (CCBs). Tracking impacts can often be difficult, particularly in the eastern United States, because utilities use blended coal feeds to meet their quality specifications. To circumvent this problem, we made arrangements for a single seam/single mine coal to be burned at a 220-MW wall-fired boiler. The feed coal is a medium sulfur, high volatile A bituminous Dean (Fire Clay) seam from Knox County, eastern Kentucky. The coal was mined over a 2-week period in order to supply the utility with sufficient fuel for a 2-day run. The coal was sampled form one location (as a whole channel and benches at the mine), as the shipped coal at the power plant, and as a pulverized coal prior to injection into the boiler. The pulverizer reject, commonly called “pyrites” by utilities, was also sampled. Fly ash was sampled from the economizers, two rows of mechanical hoppers and four rows of electrostatic precipitator (ESP) hoppers. Bottom ash also was sampled. Analyses on the mine and plant samples include, as appropriate, proximate/ultimate/sulfur forms/heating value, major oxides, trace elements, X-ray diffraction, and petrographic composition. The influence of coal properties on fly ash properties in this isolated case will be discussed. While specially arranged burns, such as for this study, are not representative of the reality of coal purchasing and coal combustion in the eastern US, attempts to follow a single coal through the process can be instructive for the purposes of understanding the origin and fate of trace elements in combustion.

Influence of Coal Properties on Mercury Uptake from Aqueous Solution

The uptake of mercury (II) from aqueous solution by a range of coals has been studied and the results have been compared to those for a number of other sorbents, including commercial active carbons and cation-exchange resins. At pH 5 in a buffer medium, the capacities for mercury removal of the low-rank coals and the oxidized bituminous coals investigated are comparable to those of the other sorbents tested. For the lignites investigated, a high content of organic sulfur does not markedly affect the capacity for mercury uptake in relatively neutral and low chloride media, owing to redox reactions being the most likely mechanism involved. However, in highly acidic solutions, the capacities for mercury uptake are considerably greater for the high-sulfur coals investigated than for their low-sulfur counterparts due to chelation being the major sorption process involved.

98/03646 Influence of coal properties on coprocessing of coal/oil mixtures

98/03646 Influence of coal properties on coprocessing of coal/oil mixtures

98/02635 Influence of coal properties on co-processing of coal/oil mixtures: Cerny, J. et al. Acta Mont., Ser. B, 1996, 6, 5–12.

98/02635 Influence of coal properties on co-processing of coal/oil mixtures: Cerny, J. et al. Acta Mont., Ser. B, 1996, 6, 5–12.

97/00753 The influence of coal properties on surface-based separation processes

97/00753 The influence of coal properties on surface-based separation processes

Influence of coal properties on N2O generation during combustion in a circulating fluidized bed

Influence of coal properties on N2O generation during combustion in a circulating fluidized bed

95/00403 Rheological properties of coal oil mixtures: Influence of coal properties

95/00403 Rheological properties of coal oil mixtures: Influence of coal properties