Influences of igneous intrusions on coal rank, coal quality and adsorption capacity in Hongyang, Handan and Huaibei coalfields, North China

Through the coal quality feature, five kinds of coal samples are determined as soft coal, and they are Pingdingshan coal, Yanzhou coal, Xuzhou coal, Zhungeer coal and Shenhua coal respectively according to the coal rank from high to low. With Alfred grain composition model, the municipal sludge with five kinds of coal samples and 95% moisture content (hereinafter referred to as sludge) is conducted the slurry property experiment, we can find that the sludge coal slurry belongs to the false body fluid featured with shear thinning, which is conducive to the pumping and atomization combustion of the sludge coal slurry. The higher the degree of coal metamorphism, the greater the limit concentration of sludge coal slurry, the better the rheological property, and the stability is better.

Download Full-text

Pore Fractal Dimensions of Bituminous Coal Reservoirs in North China and Their Impact on Gas Adsorption Capacity

Natural Resources Research ◽

10.1007/s11053-021-09958-7 ◽

2021 ◽

Author(s):

Xianfeng Liu ◽

Xiangguo Kong ◽

Baisheng Nie ◽

Dazhao Song ◽

Xueqiu He ◽

...

Keyword(s):

Adsorption Capacity ◽

Bituminous Coal ◽

North China ◽

Gas Adsorption ◽

Fractal Dimensions

Download Full-text

Univariate and Multivariate Analyses of Influencing Factors on Methane Adsorption Capacity of Semianthracite

Adsorption Science & Technology ◽

10.1155/2021/6654140 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Shihui Hou ◽

Xiaoming Wang ◽

Yudong Yuan ◽

Sidong Pan ◽

Zheng Dang ◽

...

Keyword(s):

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Influencing Factors ◽

Specific Surface Area ◽

Multivariate Analyses ◽

Methane Adsorption ◽

Coal Rank ◽

Strong Positive Correlation ◽

Quantification Theory

Methane adsorption isotherm experiments on semianthracite (2.00-2.33% R o , max ) collected from the Xin’an coal mine, Henan Province, China, were conducted to investigate the effects of pore structure, coal quality, coal maceral, and coal rank on methane adsorption capacity with applications of univariate and multivariate analyses. Methane adsorption capacity varies significantly from 12.03 to 28.40 cm3/g. In univariate analysis, methane adsorption capacity has a strong positive correlation with pore specific surface area, weak positive correlations with pore volume and ash content, and weak negative correlations with moisture content and inertinite content. No correlation is observed between methane adsorption capacity and coal rank. In multivariate analysis, the mathematical model of methane adsorption capacity affected by the combined individual variables is established based on quantification theory I. There are similarities and differences between the two analyses. The similarities are that pore specific surface area has the greatest contribution to methane adsorption capacity, while coal rank has the least contribution. The differences are reflected in two aspects. Firstly, the other influencing factors contribute differently to methane adsorption capacity. Secondly, the positive or negative correlations of some influencing factors present the opposite. The mathematic model synthetically covers the combined effects of the influencing factors, which is more representative in evaluating methane adsorption capacity.

Download Full-text

Application of a Modified Low-Field NMR Method on Methane Adsorption of Medium-Rank Coals

Geofluids ◽

10.1155/2021/6621819 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Xiaozhen Chen ◽

Taotao Yan ◽

Fangui Zeng ◽

Yanjun Meng ◽

Jinhua Liu

Keyword(s):

Adsorption Capacity ◽

Coalbed Methane ◽

Gas Adsorption ◽

Vitrinite Reflectance ◽

Methane Adsorption ◽

Coal Rank ◽

Nmr Method ◽

Low Field ◽

Low Field Nmr ◽

The Absolute

Methane adsorption capacity is an important parameter for coalbed methane (CBM) exploitation and development. Traditional examination methods are mostly time-consuming and could not detect the dynamic processes of adsorption. In this study, a modified low-field nuclear magnetic resonance (NMR) method that compensates for these shortcomings was used to quantitatively examine the methane adsorption capacity of seven medium-rank coals. Based on the typical T 2 amplitudes obtained from low-field NMR measurement, the volume of adsorbed methane was calculated. The results indicate that the Langmuir volume of seven samples is in a range of 18.9–31.85 m3/t which increases as the coal rank increases. The pore size in range 1-10 nm is the main contributor for gas adsorption in these medium-rank coal samples. Comparing the adsorption isotherms of these coal samples from the modified low-field NMR method and volumetric method, the absolute deviations between these two methods are less than 1.03 m3/t while the relative deviations fall within 4.76%. The absolute deviations and relative deviations decrease as vitrinite reflectance ( R o ) increases from 1.08% to 1.80%. These results show that the modified low-field NMR method is credible to measure the methane adsorption capacity and the precision of this method may be influenced by coal rank.

Download Full-text

Characteristics of the coal quality and elemental geochemistry in Permian coals from the Xinjier mine in the Huainan Coalfield, north China: Influence of terrigenous inputs

Journal of Geochemical Exploration ◽

10.1016/j.gexplo.2017.12.002 ◽

2018 ◽

Vol 186 ◽

pp. 50-60 ◽

Cited By ~ 8

Author(s):

Ding Dianshi ◽

Liu Guijian ◽

Fu Biao ◽

Qi Cuicui

Keyword(s):

North China ◽

Coal Quality ◽

Elemental Geochemistry ◽

Huainan Coalfield

Download Full-text

Nanopore Structure of Different Rank Coals and Its Quantitative Characterization

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.18728 ◽

2021 ◽

Vol 21 (1) ◽

pp. 22-42

Author(s):

Xiangchun Li ◽

Zhongbei Li ◽

Fan Zhang ◽

Qi Zhang ◽

Baisheng Nie ◽

...

Keyword(s):

Pore Structure ◽

Adsorption Capacity ◽

Pore Volume ◽

Coal Sample ◽

Gas Adsorption ◽

Low Rank ◽

Small Range ◽

Coal Rank ◽

Scattering Intensity ◽

The Difference

Based on gas adsorption theory, high-pressure mercury intrusion (HPMI), low-temperature liquid nitrogen gas adsorption (LT-N2GA), CO2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and small-angle X-ray scattering (SAXS) techniques were used to analyze the pore structures of six coal samples with different metamorphisms in terms of pore volume, specific surface area (SSA), pore size distribution (PSD) and pore shape. Combined with the gas adsorption constant a, the influence and mechanism of the pore structure of different coal ranks on gas adsorption capacity were analyzed. The results show that there are obvious differences in the pore structure of coals with different ranks, which leads to different adsorption capacities. To a large extent, the pore shapes observed by SEM are consistent with the LT-N2GA isotherm analysis. The pore morphology of coal samples with different ranks is very different, indicating the heterogeneity among the coal surfaces. Adsorption analysis revealed that mesopore size distributions are multimodal and that the pore volume is mainly composed of mesopores of 2–15 nm. The adsorption capacity of the coal body micropores depends on the 0.6–0.9 nm and 1.5–2.0 nm aperture sections. The influence of coal rank on gas desorption and diffusion is mainly related to the difference in pore structure. The medium metamorphic coal sample spectra show that the number of peaks in the high-wavenumber segment is small and that it is greater in the high metamorphic coal. The absorption intensity of the C–H stretching vibration peak of naphthenic or aliphatic hydrocarbons varies significantly among the coal samples. Over a small range of angles, as the scattering angle increases, the scattering intensity of each coal sample gradually decreases, and as the degree of metamorphism increases, the scattering intensity gradually increases. That is, the degree of metamorphism of coal samples is directly proportional to the scattering intensity. The influence of coal rank on gas adsorption capacity is mainly related to the difference in pore structure. The gas adsorption capacity shows an asymmetric U-shaped relationship with coal rank. For higher rank coals (Vdaf < 15%), the gas adsorption consistently decreases significantly with increasing Vdaf. In the middle and low rank coal stages (Vdaf > 15%), it increases slowly with the increase of Vdaf. We believe that the results of this study will provide a theoretical basis and practical reference value for effectively evaluating coal-rock gas storage capacity, revealing the law of CBM enrichment and the development and utilization of CBM resources.

Download Full-text

Methane adsorption characteristics and its influencing factors of the medium-to-high rank coals in the Anyang-Hebi coalfield, northern China

Energy Exploration & Exploitation ◽

10.1177/0144598718779212 ◽

2018 ◽

Vol 37 (1) ◽

pp. 60-82 ◽

Cited By ~ 1

Author(s):

Sheng Zhao ◽

Longyi Shao ◽

Haihai Hou ◽

Yue Tang ◽

Zhen Li ◽

...

Keyword(s):

Adsorption Capacity ◽

Influencing Factors ◽

Coalbed Methane ◽

Vitrinite Reflectance ◽

Negative Relationship ◽

Methane Adsorption ◽

High Rank ◽

Gas Content ◽

Coal Rank ◽

Adsorption Characteristics

The variation of coal rank in the Anyang-Hebi (Anhe) coalfield has the phenomenon of anti-Hilt law, which makes the coalfield distinctive for coalbed methane exploration research. The methane adsorption characteristics and influencing factors of the medium-to-high rank coal samples of the Shanxi Formation in this coalfield were analyzed. The results indicate that the Langmuir volume ( VL) of coals in the shallow western part of the Anhe coalfield is generally higher than that in the deep eastern part. The coal rank and the coal macerals are the dominant factors that influence the methane adsorption capacity of coals in this anti-Hilt law area. The methane adsorption capacity, represented by VL, first increases and then decreases with the coal rank, and the highest VL value corresponds to the maximum vitrinite reflectance of ∼2.1%. The adsorption capacity has a positive correlation with the vitrinite and the moisture content, a negative relationship with the inertinite content. In general, the adsorption capacity of coal samples shows a “V-shaped” change with the ash yield, and the lowest VL value corresponds to the ash yield of ∼9%. A prediction model of the gas content of the Anhe coalfield was proposed based on changes of the methane adsorption capacity and principal component analysis. Areas with a critical depth ranging from 400 m to 700 m are suggested to be methane enrichment regions for coalbed methane exploration in the Anhe coalfield.

Download Full-text

Analysis of Influence Factors and Degree for Bio-Methane Generation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.805-806.223 ◽

2013 ◽

Vol 805-806 ◽

pp. 223-227

Author(s):

Da Ping Xia ◽

Xiao Lei Liu

Keyword(s):

Trace Elements ◽

Methane Concentration ◽

Influence Factors ◽

Low Rank ◽

Formation Condition ◽

Coal Rank ◽

Coal Quality ◽

Methane Generation ◽

Biogenic Methane ◽

The Impact

Henan Yima low rank coal is used to simulate the formation condition of coal biogenic methane in this paper. This experimental study is the impact of temperature, salinity, pH, Eh, trace elements, coal quality and coal rank on bio-methane concentration. Then this paper use analytic hierarchy process (AHP) to study the impact of the size of different factors on biological methane concentration on quantitative, which shows pH is the most important influence factors and the influence degree of different factors is pH, trace elements, coal quality, coal rank, salinity, temperature and Eh.

Download Full-text

Pore structural characteristics and methane adsorption capacity of transitional shale of different depositional and burial processes: a case study of shale from Taiyuan formation of the Southern North China basin

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01359-z ◽

2021 ◽

Author(s):

Qiuchen Xu ◽

Haizhou Wang ◽

Ruiliang Guo ◽

Peng Liu ◽

Dishi Shi ◽

...

Keyword(s):

Pore Structure ◽

Adsorption Capacity ◽

North China ◽

Structural Characteristics ◽

Methane Adsorption ◽

Tectonic Uplift ◽

Taiyuan Formation ◽

Multi Stage ◽

North China Basin ◽

The Impact

AbstractPore structural characteristics and methane adsorption capacity are two significant aspects affecting shale gas potential, but the impact of deposition and burial processes on these two aspects is not clear. Hence, the shale samples of Taiyuan Formation deposited continuously and experienced multi-stage tectonic uplift in Fuyang-Bozhou area of Southern North China Basin were collected in this study. Based on the total organic carbon content analysis, mineral composition determination, low-pressure CO2 and N2 adsorption, high-pressure methane adsorption and argon ion polishing-field emission scanning electron microscope observation. The impact of depositional and burial processes variation on shale reservoir physical properties and adsorption performance is studied. The results display that the pore types of shale samples which were continues deposited and experienced multi-stage tectonic uplift have no obvious differences, while the pore volume as well as specific surface area (SSA) of micropores and mesopores of shale samples under multi-stage tectonic uplift are larger significantly. Meanwhile, the roughness of shale pores increases also. The decrease of loading pressure caused by multi-stage tectonic uplift may be the main factor for the pore structure changes of shale sample. Compared with the continuous deposited samples, the shale samples under multi-stage tectonic uplift have stronger methane adsorption capacity, which is relevant to the greater SSA of micropores as well as mesopores. This study provides an example and new revelation for the influence of depositional and burial processes on shale pore structure and methane adsorption capacity.

Download Full-text