scholarly journals Synergy of Parameters Determining the Optimal Properties of Coal as a Natural Sorbent

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1967 ◽  
Author(s):  
Katarzyna Godyń ◽  
Barbara Dutka ◽  
Monika Chuchro ◽  
Mariusz Młynarczuk
Keyword(s):  
Multiple Regression ◽  
Sorption Capacity ◽  
Vitrinite Reflectance ◽  
Sorption Property ◽  
Effective Diffusion ◽  
Gravimetric Method ◽  
Low Rank ◽  
Petrographic Analysis ◽  
Natural Sorbent ◽  
Specific Pore Volume

Selection of the optimal properties of coal as a natural sorbent, both as a sample collected from a seam or of the coal seam itself, requires various parameters to be determined and may not be based on the knowledge of metamorphism degree only. In order to improve the predictions of sorption capacity and the kinetics, analyses of correlation and multiple regression based on the results of laboratory studies were performed for 15 coal samples with various coal rank. The maximum vitrinite reflectance (R0) for low-rank coals was 0.78%–0.85%, and 0.98%–1.15% and 1.85%–2.03% for medium- and high-rank coals, respectively. Coal samples were subjected to technical and petrographic analysis. The gravimetric method was used to perform sorption tests using methane, in order to determine the sorption capacity and the effective diffusion coefficient for each of the coals. Pycnometric methods were used to determine the textural parameters of coals, such as the percentage porosity and specific pore volume. The studies were further supplemented with an evaluation of the mechanical properties of the coals, Vickers micro-hardness, and elastic modulus. This work shows that the statistical multiple regression method enables a computational model including the selected petrophysical parameters displaying synergy with the specific sorption property—capacity or kinetics—to be created. The results showed the usefulness of this analysis in providing improved predictions of the optimal sorption properties of coal as a natural sorbent.

The Influences of the Rank of Coal on Methane Sorption Capacity in Coals/Wpływ Rzędu Węgla Na Pojemność Sorpcyjną Metanu W Węglach

2014 ◽  
Vol 59 (2) ◽  
pp. 509-516
Author(s):  
Andrzej Olajossy
Keyword(s):  
Sorption Capacity ◽  
Coalbed Methane ◽  
Vitrinite Reflectance ◽  
Sorption Isotherms ◽  
Volatile Matter ◽  
Low Rank ◽  
Hard Coal ◽  
Petrographic Composition ◽  
Methane Sorption ◽  
Indian Coals

Abstract Methane sorption capacity is of significance in the issues of coalbed methane (CBM) and depends on various parameters, including mainly, on rank of coal and the maceral content in coals. However, in some of the World coals basins the influences of those parameters on methane sorption capacity is various and sometimes complicated. Usually the rank of coal is expressed by its vitrinite reflectance Ro. Moreover, in coals for which there is a high correlation between vitrinite reflectance and volatile matter Vdaf the rank of coal may also be represented by Vdaf. The influence of the rank of coal on methane sorption capacity for Polish coals is not well understood, hence the examination in the presented paper was undertaken. For the purpose of analysis there were chosen fourteen samples of hard coal originating from the Upper Silesian Basin and Lower Silesian Basin. The scope of the sorption capacity is: 15-42 cm3/g and the scope of vitrinite reflectance: 0,6-2,2%. Majority of those coals were of low rank, high volatile matter (HV), some were of middle rank, middle volatile matter (MV) and among them there was a small number of high rank, low volatile matter (LV) coals. The analysis was conducted on the basis of available from the literature results of research of petrographic composition and methane sorption isotherms. Some of those samples were in the form (shape) of grains and others - as cut out plates of coal. The high pressure isotherms previously obtained in the cited studies were analyzed here for the purpose of establishing their sorption capacity on the basis of Langmuire equation. As a result of this paper, it turned out that for low rank, HV coals the Langmuire volume VL slightly decreases with the increase of rank, reaching its minimum for the middle rank (MV) coal and then increases with the rise of the rank (LV). From the graphic illustrations presented with respect to this relation follows the similarity to the Indian coals and partially to the Australian coals.

scholarly journals Sorption and Micro-Scale Strength Properties of Coals Susceptible to Outburst Caused by Changes in Degree of Coalification

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5807
Author(s):  
Katarzyna Godyń ◽  
Barbara Dutka
Keyword(s):  
Sorption Capacity ◽  
Effective Diffusion ◽  
Gravimetric Method ◽  
Strength Properties ◽  
Methane Content ◽  
Warning Sign ◽  
Micro Scale ◽  
Effective Diffusion Coefficients ◽  
Upper Silesian Coal Basin ◽  
Methane Sorption

Coals from the south-western part of the Upper Silesian Coal Basin have a strong outburst susceptibility. The objective of this study was to identify the influence of coalification degree on methane sorption and micro scale strength properties of 24 coals from Jastrzębie Zdrój. Coal samples showed a reflectance Ro between 0.98 and 1.25%. Sorption measurements were carried out by gravimetric method. Sorption capacities were determined at mean deposit temperature of 35 °C. Using the unipore model and solution of Fick’s second law, the effective diffusion coefficients of methane in the studied coals were obtained. The Vickers method was used to study the microhardness and the modulus of elasticity. It has been shown that the increase in the coalification degree reduces the sorption capacity of coal and also reduces the rate of methane emission. Coals the most susceptible to outbursts, were the most brittle. With the increase in Ro, the methane seam pressure p increased as well as desorbable methane content DMC, both due to the reduction in the sorption capacity of coal. The increased dp index is a warning sign indicating an increased total methane content of coal seam, an increased seam pressure or an alternation of coal structure.

scholarly journals Estimation of Coal’s Sorption Parameters Using Artificial Neural Networks

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5422
Author(s):  
Marta Skiba ◽  
Mariusz Młynarczuk
Keyword(s):  
Diffusion Coefficient ◽  
Sorption Capacity ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Gravimetric Method ◽  
Neural Models ◽  
Petrographic Composition ◽  
Artificial Neural ◽  
Sorption Parameters ◽  
Maximal Sorption Capacity

This article presents research results into the application of an artificial neural network (ANN) to determine coal’s sorption parameters, such as the maximal sorption capacity and effective diffusion coefficient. Determining these parameters is currently time-consuming, and requires specialized and expensive equipment. The work was conducted with the use of feed-forward back-propagation networks (FNNs); it was aimed at estimating the values of the aforementioned parameters from information obtained through technical and densitometric analyses, as well as knowledge of the petrographic composition of the examined coal samples. Analyses showed significant compatibility between the values of the analyzed sorption parameters obtained with regressive neural models and the values of parameters determined with the gravimetric method using a sorption analyzer (prediction error for the best match was 6.1% and 0.2% for the effective diffusion coefficient and maximal sorption capacity, respectively). The established determination coefficients (0.982, 0.999) and the values of standard deviation ratios (below 0.1 in each case) confirmed very high prediction capacities of the adopted neural models. The research showed the great potential of the proposed method to describe the sorption properties of coal as a material that is a natural sorbent for methane and carbon dioxide.

scholarly journals Variation of Petrophysical Properties and Adsorption Capacity in Different Rank Coals: An Experimental Study of Coals from the Junggar, Ordos and Qinshui Basins in China

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 986 ◽  
Author(s):  
Yingjin Wang ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Xiawei Li
Keyword(s):  
Adsorption Capacity ◽  
Vitrinite Reflectance ◽  
Inhibitory Effect ◽  
Proximate Analysis ◽  
Methane Adsorption ◽  
Low Rank ◽  
Petrophysical Properties ◽  
Isothermal Adsorption ◽  
Variation Rule ◽  
Moisture Absorbent

The petrophysical properties of coal will vary during coalification, and thus affect the methane adsorption capacity. In order to clarify the variation rule and its controlling effect on methane adsorption, various petrophysical tests including proximate analysis, moisture measurement, methane isothermal adsorption, mercury injection, etc. were carried out on 60 coal samples collected from the Junggar, Ordos and Qinshui basins in China. In this work, the boundary values of maximum vitrinite reflectance (Ro,m) for dividing low rank, medium rank and high rank coals are set as 0.65% and 2.0%. The results show that vitrinite is the most abundant maceral, but the maceral contents are controlled by sedimentation without any relation to coal rank. Both the moisture content and porosity results show higher values in the low ranks and stabilized with Ro,m beyond 1%. Ro,m and VL (daf) show quadratic correlation with the peak located in Ro,m = 4.5–5%, with the coefficient (R2) reaching 0.86. PL decrease rapidly before Ro,m = 1.5%, then increase slowly. DAP is established to quantify the inhibitory effect of moisture on methane adsorption capacity, which shows periodic relationship with Ro,m: the inhibitory effect in lignite is the weakest and increases during coalification, then remains constant at Ro,m = 1.8% to 3.5%, and finally increases again. In the high metamorphic stage, clay minerals are more moisture-absorbent than coal, and the inherent moisture negatively correlates with the ratio of vitrinite to inertinite (V/I). During coalification, micro gas pores gradually become dominant, fractures tends to be well oriented and extended, and clay filling becomes more common. These findings can help us better understand the variation of petrophysical properties and adsorption capacity in different rank coals.

scholarly journals Comprehensive Fractal Model and Pore Structural Features of Medium- and Low-Rank Coal from the Zhunnan Coalfield of Xinjiang, China

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 7
Author(s):  
Haifei Lin ◽  
Yang Bai ◽  
Jingting Bu ◽  
Shugang Li ◽  
Min Yan ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Thermodynamic Model ◽  
Vitrinite Reflectance ◽  
Average Pore Size ◽  
Full Range ◽  
Complex Structure ◽  
Structural Features ◽  
Low Rank ◽  
Low Rank Coal ◽  
Average Pore

Medium and low-rank coal from the Zhunnan coalfield of Xinjiang in China was investigated for quantitatively characterizing its range of aperture structure. The pore parameters were determined by nitrogen adsorption at low temperature and mercury injection at high pressure, and the full aperture was determined. The FHH model, Menger model, Sierpinski model, and a thermodynamic model were used to calculate the comprehensive fractal dimension of the coal samples over the full range of aperture. The fractal characteristics of the pores of medium- and low-rank coal were quantitatively analyzed, which provided a reference for the overall characterization of pore structure heterogeneity in this coalfield. The results show that the FHH model and thermodynamic model more accurately calculate the fractal dimensions of less and greater than the joint pore position, respectively. The comprehensive fractal dimension of the low-rank coal pore is 2.8005–2.8811 and that of medium rank coal is 2.5710–2.6147. When compared with the medium-rank coal, pores of the low-rank coal are more developed and they exhibit a more complex structure with stronger heterogeneity. The comprehensive fractal dimension of the pores is a negative correlation with average pore size, vitrinite content, and maximum vitrinite reflectance, and positive correlation with pore volume, pore specific surface area, inertinite content, and exinite content.

SORPTION CAPACITY OF NATURAL FILTER EXISTING MATERIALS ON COPPER CATIONS

2013 ◽  
Vol 3 (4S) ◽  
pp. 39-41
Author(s):  
Eugenia N KALJUKOVA ◽  
Elena V PAVLOVA
Keyword(s):  
Sorption Capacity ◽  
Metal Cations ◽  
Sorption Properties ◽  
Natural Sorbent ◽  
Natural Sorbents ◽  
Filter Materials ◽  
Model Solutions ◽  
Degree Of Extraction ◽  
Copper Cations

Investigated the sorption properties of natural sorption materials (dolomite and shungit) towards cations copper.Defined by the degree of extraction of metal cations of model solutions with the use of original and modified natural sorbents. Studied natural filter materials higher degree stump extraction of copper cations from solution was obtained by natural sorbent-dolomite.

THE EFFECT OF TEMPERATURE ON THE SORPTION PROPERTIES OF COAL FROM UPPER SILESIAN COAL BASIN, POLAND / WPŁYW ZMIAN TEMPERATURY NA WŁASNOŚCI SORPCYJNE NA PODSTAWIE BADAŃ WYBRANYCH WĘGLI Z GÓRNOŚLĄSKIEGO ZAGŁĘBIA WĘGLOWEGO

2013 ◽  
Vol 58 (4) ◽  
pp. 1163-1176 ◽  
Author(s):  
Mirosław Wierzbicki
Keyword(s):  
Coal Seam ◽  
Sorption Capacity ◽  
Gravimetric Method ◽  
Geothermal Gradient ◽  
Effect Of Temperature ◽  
Coal Basin ◽  
Equilibrium Pressure ◽  
Rock Temperature ◽  
Upper Silesian Coal Basin ◽  
Nonlinear Increase

Abstract This paper presents the results of studies on gas sorption performed by means of the gravimetric method. The tests were performed on two coal samples of different metamorphism degrees, came from two regions of Upper Silesian Coal Basin, Poland. The changes in sorption capacity of coals were measured in the pressure range from 0.1 MPa to 17 MPa and in temperatures ranging from 291K to 333K. Coal of a lower coalification degree was a better methane sorbent. Changes in sorption capacity of tested coals were linearly dependent on the temperature. The increase in temperature of 10K reduces the Langmuir sorption of about 0.7-0.8 [cm3/g]. Such increase of temperature causes a nonlinear increase of the Langmuir pressure (b-1). These results showed that the rise of rock temperature, caused by geothermal gradient, can induce a significant increase of equilibrium pressure of methane in coal seam. An increase of coal seam temperature may cause an increase of gas and coal outburst risk in a coal mine.

scholarly journals THE ZONATION OF COAL RANK IN MUARA ENIM FORMATION BASED ON THE REFLECTION STUDY

2021 ◽  
Vol 56 (4) ◽  
pp. 484-490
Author(s):  
Irfan Marwanza ◽  
Chairul Nas ◽  
Masagus Ahmad Azizi ◽  
Riskaviana Kurniawati ◽  
Ardiansyah
Keyword(s):  
Vitrinite Reflectance ◽  
Volatile Matter ◽  
Plant Residue ◽  
Petrographic Analysis ◽  
Coal Rank ◽  
Anthracite Coal ◽  
Reflectance Analysis ◽  
Southwest Region ◽  
Physical Changes ◽  
Descriptive Method

Coal is a sedimentary rock containing approximately 50% to 70% carbon derived from the accumulation of plant residue that had undergone chemical and physical changes. In this research, the petrographic analysis method of coal was conducted based on the following parameters, measuring vitrinite reflectance (Ro%), estimation of moisture, volatile matter, and carbon-hydrogen content. This study aims to determine the zonation of coal rank through the vitrinite reflectance analysis in Maura Enim Formation. The samples observed were obtained from the Muara Enim Formation, which had undergone certain geological events to form lignite and anthracite coal ranks, then analyzed using the descriptive method. The results showed that the reflectance value of vitrinite was between 0.20% - 0.44%, which was utilized in the sorting of coal from lignite - sub-bituminous, according to ASTM D2798-06 (2006). Furthermore, in the Southwest region, coal is formed through greater pressure than those in the Northeast. Generally, the level of difference is caused by pressure, temperature, and time factor. Therefore, this study is recommended as a guideline in determining coal rank through vitrinite reflectance analysis in different formations.

scholarly journals Sorption of CO2 and CH4 on Raw and Calcined Halloysite—Structural and Pore Characterization Study

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 917 ◽  
Author(s):  
Anna Pajdak ◽  
Norbert Skoczylas ◽  
Arkadiusz Szymanek ◽  
Marcin Lutyński ◽  
Piotr Sakiewicz
Keyword(s):  
Surface Area ◽  
Structural Parameters ◽  
Mercury Porosimetry ◽  
Effective Diffusion ◽  
Gravimetric Method ◽  
Sorption Isotherms ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
High Rate ◽  
Co2 Sorption

The article presents comparative characteristics of the pore structure and sorption properties of raw halloysite (R-HAL) and after calcination (C-HAL) at the temperature of 873 K. Structural parameters were determined by optical scanning and transmission electron microscopy methods as well as by mercury porosimetry (MIP, Hg) and low-pressure nitrogen adsorption (LPNA, N2, 77 K). The surface area parameter (LPNA) of halloysite mesopores before calcination was 54–61 m2/g. Calcining caused the pore surface to develop to 70–73 m2/g. The porosity (MIP) of halloysite after calcination increased from 29% to 46%, while the surface area within macropores increased from 43 m2/g to 54 m2/g. The total pore volume within mesopores and macropores increased almost twice after calcination. The course of CH4 and CO2 sorption on the halloysite was examined and sorption isotherms (0–1.5 MPa, 313 K) were determined by gravimetric method. The values of equilibrium sorption capacities increased at higher pressures. The sorption capacity of CH4 in R-HAL was 0.18 mmol/g, while in C-HAL 0.21 mmol/g. CO2 sorption capacities were 0.54 mmol/g and 0.63 mmol/g, respectively. Halloysite had a very high rate of sorption equilibrium. The values of the effective diffusion coefficient for methane on the tested halloysite were higher than De > 4.2 × 10−7 cm2/s while for carbon dioxide De > 3.1 × 10−7 cm2/s.

scholarly journals Evaluation of parameters to determine the degree of coal dust explosibility

2014 ◽  
pp. 42-54
Author(s):  
Elkin Casas Herrera ◽  
Astrid Blandón Montes ◽  
Jorge Martin Molina-Escobar
Keyword(s):  
Direct Relationship ◽  
Coal Dust ◽  
Vitrinite Reflectance ◽  
Carbon Particle ◽  
Calorific Value ◽  
Environmental Parameters ◽  
Volatile Matter ◽  
Low Rank ◽  
Fine Grain ◽  
Close Relationship

Coal dust is highly explosive and caused dozens of victims in Colombia. In this research the most important and direct influence on coal dust, especially those that cause combustion and explosion inside the mine factors were analyzed; is important to discuss the characteristics of each coal mined and processed, for actions that do not compromise the integrity of the staff or facilities. Four (4) channel samples of coal exploitation faces with High Volatile Bituminous C from Cerrejón Formation were collected and analyzed: Proximal (moisture, ash, volatile matter, fixed carbon, total sulfur and calorific value ); petrographic (maceral counting and vitrinite reflectance) and Hardgrove mill index. The samples were crushed to obtain fractions corresponding to meshes 200, 270 and 325 considering those sizes could give greater risks of explosion.The analysis showed that there is a direct relationship between the results of the Hardgrove mill index and the degree of explosiveness in the fraction corresponding to 200 mesh, meaning that a higher rate of milling the greater the degree of explosiveness; a direct relationship between calorific inertinite content range and also observed. The 325 mesh fraction for all samples showed the same degree of explosiveness, which indicates that the grain size and the type of coal maceral not influence the content and coal rank. The flash point decreased for finer grains for all samples. Thus, the size of carbon particle is very important as an indicator in the coal-dust explosion factor: finer particles have greater the likelihood of explosion. The percentage of inertinites has a close relationship with the explosivity index, the higher the content of this maceral, coupled with the fine grain, coal dust behaves like a highly explosive element and generate risks in mining operations.Coal rank is an important factor regard to self combustion and explosion of particles with grain sizes greater 200 mesh. If a low rank coal has susceptible and unstable at high temperature elements and this is combined with high volatile matter and some other influential environmental parameters, such as blow air, dust concentration, humidity, and pressure, among others, the ideal combustion and then a likely violent explosion may affect a large portion of mine.

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