scholarly journals The Dynamic Change of Pore Structure for the Low-Rank Coal with Various Pretreatment Temperatures: A Case Study from Southwestern Ordos Basin

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Teng Li
Keyword(s):  
Coal Sample ◽  
Dynamic Change ◽  
Ordos Basin ◽  
Hysteresis Loops ◽  
Low Rank ◽  
Low Rank Coal ◽  
Mesopore Volume ◽  
Pore Characteristics ◽  
Pattern Distribution ◽  
The Right

The pore characteristics of the low-rank coal are different from medium- and high-rank coals. The low-temperature N2 adsorption (LP-N2A) measurements with a single low-rank coal were launched, and the dynamic change of pore structures under various pretreatment temperatures from 120°C to 300°C was studied. The isothermal curves of the DFS coal sample feature IV type, the hysteresis loops convert from H4 type to H2 type, and the hysteresis loops tend to be closed with the increased pretreatment temperatures. The mesopores are dominant in the DFS coal. The dynamic of pore volume (PV) and pore specific surface area (SSA) features the three-step-style change with the cut-off temperature points at 150°C and 240°C, and this has a relationship with the loss of the moisture and volatiles in the DFS coal sample. The pores with an aperture below 10 nm are the dominant mesopores in the DFS coal, and the mesopore volume features bimodal pattern distribution with a higher left peak of approximately 1.7 nm and a lower right peak of approximately 3-5 nm, and the right peak continuously right shift with the increase pretreatment temperatures. The total mesopore volume decreases with the upgrading temperatures, while the ratio of pores greater than 5 nm increases. Finally, the mesopore evolution model with the increased pretreatment temperatures was summarized.

scholarly journals Multi-fractal characteristics of pore structure for coal during the refined upgrading degassing temperatures

2021 ◽  
Author(s):  
Jianjun Wang ◽  
Lingli Liu ◽  
Zehong Cui ◽  
Hongjun Wang ◽  
Teng Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Pore Structure ◽  
Fractal Theory ◽  
Dynamic Change ◽  
Ordos Basin ◽  
Nitrogen Adsorption ◽  
Low Rank ◽  
Low Rank Coal ◽  
Adsorption Measurement ◽  
Fractal Spectrum

AbstractThe low-temperature nitrogen adsorption measurement is commonly used to describe the pore structure of porous medium, while the role of degassing temperature in the low-temperature nitrogen adsorption measurement does not attract enough attention, various degassing temperatures may lead to the different pore structure characterization for the same coal. In this study, the low-rank coal collected from Binchang mining area, southwest of Ordos Basin was launched the low-temperature nitrogen adsorption measurement under seven various degassing temperatures (120 °C, 150 °C, 180 °C, 210 °C, 240 °C, 270 °C and 300 °C), respectively, the dynamic change of the pore structure under refined upgrading degassing temperatures are studied, and it was also quantitative evaluated with the multi-fractal theory. The results show that the pore specific surface area and pore volume decrease linearly with the increased degassing temperatures, ranges from 12.53 to 2.16 m2/g and 0.01539 to 0.00535 cm3/g, respectively. While the average pore aperture features the contrary characteristics (various from 4.9151 to 9.9159 nm), indicating the pore structure has been changed during the refined upgrading degassing temperatures. With the upgrading degassing temperatures, the sizes of hysteresis loop decrease, and the connectivity of pore structure enhanced. The multi-fractal dimension and multi-fractal spectrum could better present the partial abnormal of pore structure during the refined upgrading degassing temperatures, and the quality index, Dq spectrum, D−10–D10 and multi-fractal spectrum could describe the homogeneity and connectivity of the pores finely. The degassing temperatures of 150 °C, 180 °C and 270 °C are selected as three knee points, which can reflect the partial abnormal of the pore structure during the refined upgrading degassing temperatures. Under the lower degassing temperature (< 150 °C), the homogeneity and connectivity of the pore feature a certain increase, following that it presents stable when the degassing temperatures various from 150 to 180 °C. The homogeneity and connectivity of the pore would further enhanced until the degassing temperature reaches to 270 °C. Because of the melting of the pore when the degassing temperature exceeds 270 °C, the complexity of pore structure increased. In this study, we advise the degassing temperature for low-temperature nitrogen adsorption measurement of low-rank coal should not exceed 120 °C.

scholarly journals Pore Characteristics of Vitrain and Durain in Low Rank Coal Area

2017 ◽  
Vol 05 (11) ◽  
pp. 10-20 ◽  
Author(s):  
Dongmin Ma ◽  
Qian Li ◽  
Qian He ◽  
Chuantao Wang
Keyword(s):  
Low Rank ◽  
Low Rank Coal ◽  
Pore Characteristics

scholarly journals Improving Coal Flotation by Gaseous Collector Pretreatment Method and its Potential Application in Preparing Coal Water Slurry

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 500 ◽  
Author(s):  
Shen ◽  
Min ◽  
Liu ◽  
Xue ◽  
Zhu
Keyword(s):  
Contact Angle ◽  
Coal Sample ◽  
Ash Content ◽  
Low Rank ◽  
Distribution Analysis ◽  
Low Rank Coal ◽  
Clean Coal ◽  
Pretreatment Method ◽  
Water Slurry ◽  
Coal Water Slurry

Low-rank coal is difficult to upgrade using conventional flotation methods due to its high hydrophilic properties. Thus, it is necessary to explore new methods for upgrading and utilizing low-rank coal. In this investigation, a gaseous dodecane pretreatment method was used to enhance the flotation performance of low-rank coal. Pore distribution analysis, FTIR (Fourier Transform Infrared Spectroscopy), and contact angle measurements were used to study the surface properties of the coal sample. Size distribution and float-sink test results indicated that the coal sample contained a lot of clean coal with low ash content, which could be used as a high quality raw material for making coal water slurry. FTIR, pore distribution analysis, and contact angle results showed that the coal was very hydrophilic due to the high concentration of -OH group and the large number of pores and cracks on the coal surface. The hydrophobicity of the coal sample was significantly improved by the gaseous dodecane pretreatment method. Clean coal with 67.2% combustible matter recovery and 10.5% ash content was obtained by gaseous dodecane pretreatment flotation method. Coal water slurry with 60% concentration was prepared using the flotation clean coal.

scholarly journals Experimental and simulation studies on gasification characteristics of a low-rank coal by rapid heating under CO2-rich condition

2018 ◽  
Vol 16 (4) ◽  
Author(s):  
Wang Cong ◽  
Olalekan S. Alade ◽  
Kyuro Sasaki ◽  
Yuichi Sugai
Keyword(s):  
Coal Sample ◽  
Pressure Range ◽  
Bituminous Coal ◽  
Rapid Heating ◽  
Co2 Concentration ◽  
Environmentally Benign ◽  
Low Rank ◽  
Simulation Studies ◽  
Low Rank Coal ◽  
Rich Condition

In this investigation, an environmentally benign and efficient way for gasification of low-rank coal under CO2 rich condition, rapid heating, and high pressure was investigated. Series of experimental and simulation studies were carried out to compare the combustion characteristics of the Shandong (SD) low rank coal and Datong (DT) bituminous coal. It was found that the gasification potential of the SD coal sample was higher than that of the DT coal sample under the conditions investigated. A gasification model was developed and validated to predict the gasification characteristics of the low rank coal based on the experimental and the gasification kinetic parameters. It was found that the gasification conditions resulting in effective gasification of the low rank coal (in terms of CH4, CO and H2 gases production) are 100% CO2 concentration, 37.5 J/s heating rate, and 0.5 – 1 MPa pressure range.

scholarly journals The dynamic change of pore structure for low-rank coal under refined upgrading pretreatment temperatures

2020 ◽  
Author(s):  
Teng Li ◽  
Cai-Fang Wu ◽  
Zi-Wei Wang
Keyword(s):  
Pore Structure ◽  
Pore Volume ◽  
Dynamic Change ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Volatile Matter ◽  
Low Rank ◽  
Low Rank Coal ◽  
Pore Collapse ◽  
Pretreatment Temperature

AbstractPore structure characteristics are significant factor in the evaluation of the physical characteristics of low-rank coal. In this study, three low-rank coal samples were collected from the Xishanyao Formation, Santanghu Basin, and low-temperature liquid-nitrogen adsorption (LP-N2A) measurements were taken under various pretreatment temperatures. Owing to the continuous loss of water and volatile matter in low-rank coal, the total pore volume assumes a three-step profile with knee temperatures of 150 °C and 240 °C. However, the ash in the coal can protect the coal skeleton. Pore collapse mainly occurs for mesopores with aperture smaller than 20 nm. Mesopores with apertures smaller than 5 nm exhibit a continuous decrease in pore volume, whereas the pore volume of mesopores with apertures ranging from 5 to 10 nm increases at lower pretreatment temperatures (<150 °C) followed by a faint decrease. As for mesopores with apertures larger than 10 nm, the pore volume increases significantly when the pretreatment temperature reaches 300 °C. The pore structure of low-rank coal features a significant heating effect, the pretreatment temperature should not exceed 150 °C when the LP-N2A is used to evaluate the pore structure of low-rank coal to effectively evaluate the reservoir characteristics of low-rank coal.

INVESTIGATING A LINK BETWEEN LOW-RANK COAL BEARING CARRIZO-WILCOX AQUIFER WATER AND KIDNEY DISEASE IN EAST TEXAS

2018 ◽  
Author(s):  
Jayeeta Chakraborty ◽  
◽  
Robert B. Finkelman ◽  
William H. Orem ◽  
Matthew S. Varonka ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Low Rank ◽  
East Texas ◽  
Low Rank Coal

scholarly journals Surface Chemical Heterogeneity of Low Rank Coal Characterized by Micro-FTIR and Its Correlation with Hydrophobicity

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 239
Author(s):  
Wei Wang ◽  
Long Liang ◽  
Yaoli Peng ◽  
Maria Holuszko
Keyword(s):  
Surface Chemistry ◽  
Functional Group ◽  
Group Composition ◽  
Contact Angles ◽  
Low Rank ◽  
Surface Chemical ◽  
Carbonyl Groups ◽  
Low Rank Coal ◽  
Different Types ◽  
Aliphatic Carbon

Micro-Fourier transform infrared (micro-FTIR) spectroscopy was used to correlate the surface chemistry of low rank coal with hydrophobicity. Six square areas without mineral impurities on low rank coal surfaces were selected as testing areas. A specially-designed methodology was applied to conduct micro-FTIR measurements and contact angle tests on the same testing area. A series of semi-quantitative functional group ratios derived from micro-FTIR spectra were correlated with contact angles, and the determination coefficients of linear regression were calculated and compared in order to identify the structure of the functional group ratios. Finally, two semi-quantitative ratios composed of aliphatic carbon hydrogen, aromatic carbon hydrogen and two different types of carbonyl groups were proposed as indicators of low rank coal hydrophobicity. This work provided a rapid way to predict low rank coal hydrophobicity through its functional group composition and helped us understand the hydrophobicity heterogeneity of low rank coal from the perspective of its surface chemistry.

Transformation of low-rank coal to clean syngas and power via thermochemical route

Energy ◽  
2021 ◽  
pp. 121505
Author(s):  
Muflih A. Adnan ◽  
Arif Hidayat ◽  
Mohammad M. Hossain ◽  
Oki Muraza
Keyword(s):  
Low Rank ◽  
Low Rank Coal
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