scholarly journals Influence of Coal Particle Size on Coal Adsorption and Desorption Characteristics

2014 ◽  
Vol 59 (3) ◽  
pp. 807-820 ◽  
Author(s):  
Lei Zhang ◽  
Naj Aziz ◽  
Ting Ren ◽  
Jan Nemcik ◽  
Shihao Tu
Keyword(s):  
Particle Size ◽  
Sorption Capacity ◽  
Coalbed Methane ◽  
Coal Particle ◽  
Sorption Isotherms ◽  
Ash Content ◽  
Methane Recovery ◽  
Adsorption And Desorption ◽  
Coal Particles ◽  
Desorption Hysteresis

Abstract Accurate testing coal isotherm can play a significant role in the areas of coal seam gas drainage, outburst control, CO2 geo-sequestration, coalbed methane (CBM) and enhanced coalbed methane recovery (ECBM) etc. The effect of particle size on the CO2 and CH4 sorption capacity of bituminous coal from Illawarra, Australia was investigated at 35°C and at pressure up to 4 MPa. A unique indirect gravimetric apparatus was used to measure the gas adsorption and desorption isotherms of coal of different particle sizes ranging from around 150 urn to 16 mm. Langmuir model was used to analysis the experimental results of all gases. Coal particle size was found to have an apparent effect on the coal ash content and helium density results. Coal with larger particle size had higher ash content and higher helium density. The sorption isotherm was found to be highly sensitive with helium density of coal which was determined in the procedure of testing the void volume of sample cell. Hence, coal particle size had a significant influence on the coal sorption characteristics including sorption capacity and desorption hysteresis for CO2 and CH4, especially calculated with dry basis of coal. In this study, the 150-212 um (150 um) coal samples achieved higher sorption capacity and followed by 2.36-3.35 mm (2.4 mm), 8-9.5 mm (8 mm) and 16-19 mm (16 mm) particle size samples. However, the differences between different coal particles were getting smaller when the sorption isotherms are calculated with dry ash free basis. Test with 150 um coal samples were also found to have relatively smaller desorption hysteresis compared with the other larger particle size samples. The different results including adsorption/desorption isotherm, Langmuir parameters and coal hysteresis were all analysed with the CO2 and CH4 gases.

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 Effects of temperature gradient and particle size on self-ignition temperature of low-rank coal excavated from inner Mongolia, China

2019 ◽  
Vol 6 (9) ◽  
pp. 190374 ◽  
Author(s):  
Yongjun Wang ◽  
Xiaoming Zhang ◽  
Hemeng Zhang ◽  
Kyuro Sasaki
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Temperature Gradient ◽  
Ignition Temperature ◽  
Coal Particle ◽  
Critical Value ◽  
Low Rank ◽  
Low Rank Coal ◽  
Coal Particles ◽  
Effects Of Temperature

This study investigates the effects of temperature gradient and coal particle size on the critical self-ignition temperature T CSIT of a coal pile packed with low-rank coal using the wire-mesh basket test to estimate T CSIT based on the Frank–Kamenetskii equation. The values of T CSIT , the temperature gradient and the apparent activation energy of different coal pile volumes packed with coal particles of different sizes are measured. The supercriticality or subcriticality of the coal is assessed using a non-dimensional index I HR based on the temperature gradient at the temperature cross-point between coal and ambient temperatures for coal piles with various volumes and particle sizes. The critical value I HRC at the boundary between supercriticality and subcriticality is determined as a function of pile volume. The coal status of supercritical or subcritical can be separated by critical value of I HR as a function of pile volume. Quantitative effects of coal particle size on T CSIT of coal piles are measured for constant pile volume. It can be concluded that a pile packed with smaller coal particles is more likely to undergo spontaneous combustion, while the chemical activation energy is not sensitive to coal particle size. Finally, the effect of coal particle size on T CSIT is represented by the inclusion of an extra term in the equation giving T CSIT for a coal pile.

scholarly journals An Experimental Study on Preparation of Reconstituted Tectonic Coal Samples: Optimization of Preparation Conditions

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2846
Author(s):  
Jishi Geng ◽  
Liwen Cao ◽  
Congyu Zhong ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Moisture Content ◽  
Coalbed Methane ◽  
P Wave ◽  
Preparation Conditions ◽  
P Wave Velocity ◽  
Coal Particles ◽  
Mining Safety ◽  
Tectonic Coal

The uniquely soft and fragile nature of tectonic coal makes it difficult to obtain core samples suitable for laboratory experimentation. Preparation of reconstituted tectonic coal (RTC) samples generally adopts the secondary forming method. Reliable coal samples are needed to obtain credible permeability and mechanical parameters that can guide Coalbed Methane (CBM) extraction and improve mining safety. In this study, the compaction mechanism of coal particles is analyzed based on the Kawakita model, and optimal sample preparation conditions are systemically investigated, particularly particle size and particle size distribution, forming pressure, and moisture content. The density and P-wave velocity of coal samples were used to test whether the RTC samples were realistic. Finally, the mechanical properties and deformation characteristics of the RTC samples were determined. The results indicate that RTC samples prepared for laboratory testing of mechanical properties require (1) the original particle size of the tectonic coal to be retained as much as possible; (2) a forming pressure that compacts the sample similar to the original tectonic coal; and (3) an optimum moisture content.

scholarly journals Effects of Particle Size on Diffusion Kinetics in Chinese Anthracites during CH4 Desorption

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 514
Author(s):  
Jie Zang ◽  
Kai Wang ◽  
Yanbin Yu
Keyword(s):  
Particle Size ◽  
Coalbed Methane ◽  
Gas Flow ◽  
Hard Coal ◽  
Diffusion Kinetics ◽  
Methane Recovery ◽  
Coal Matrix ◽  
Matrix Blocks ◽  
Reported Data ◽  
Coalbed Methane Production

Diffusion kinetics is widely acknowledged to dominate gas flow in coal matrix blocks. Knowledge of this topic is important for ongoing coalbed methane recovery and CO2-enhanced coalbed methane production. Because laboratory diffusivity measurements are normally conducted on powdered coals, it is unclear how representative the results are for coalbeds. Investigations into the effects of particle size on gas diffusivity can provide insights into the in situ diffusivity of the coal matrix. This paper presents measured CH4 desorption data in two Chinese anthracites (one brittle, one hard) having different particle sizes, to investigate the effects of particle size on diffusion kinetics. The experimental data were fitted by both the unipore (UP) and bidisperse (BD) models. The BD model agreed better with the measured data than the UP model, especially for the brittle coal. This indicated that the brittle coal was more abundant in macropores than the hard coal. Diffusivity in the hard coal decreased with increasing particle size but varied stochastically within a small value range in the brittle coal as the particle size increased. The diffusivity of the brittle coal, with its higher vitrinite content and lower inertinite content, was greater compared with the hard coal. This was inconsistent with reported data in which vitrinite had a smaller diffusivity than inertinite. This anomalous phenomenon may be caused by the generation of comparatively more macropores during grinding in the brittle coal. These results indicate that the effects of particle size on diffusivity may be coal-dependent, and further, the effects of particle size are influenced by other factors, including coal structure.

Uranium and vanadium sorption by chitosan and derivatives

1994 ◽  
Vol 30 (9) ◽  
pp. 183-190 ◽  
Author(s):  
E. Guibal ◽  
I. Saucedo ◽  
M. Jansson-Charrier ◽  
B. Delanghe ◽  
P. Le Cloirec
Keyword(s):  
Particle Size ◽  
Sorption Capacity ◽  
Glutaric Acid ◽  
Sorption Isotherms ◽  
Experimental Results ◽  
Sorption Mechanism ◽  
Freundlich Model ◽  
Surface Control ◽  
The Poor ◽  
Langmuir And Freundlich Models

The modification of chitosan, by grafting of oxo-2-glutaric acid, allows its sorption performance to be increased. This enhancement of uptake ability is observed in overall sorption capacity and specificity in sorbing particular metals. This work focuses on the sorption of uranium (VI) and vanadium (V). The sorption isotherms are studied. The experimental results are described according to the Langmuir and Freundlich models. It was shown that uranium sorption is best described by the Freundlich model, while vanadium sorption is difficult to model. The influence of the particle size, significant in the case of uranium, but not for vanadium, shows that the sorption mechanism is not the same for the two metals : surface control is predominant in the case of uranium, due to the poor porosity of the sorbents. The control of overall sorption capacity is related to the chemistry of the metal and polymer : the appearance of hydrolyzed species and protonation of the polymer.

scholarly journals Investigation of thermochemical process of coal particle packed bed reactions for the development of UCG

2020 ◽  
Author(s):  
Tata Sutardi ◽  
Linwei Wang ◽  
Nader Karimi ◽  
Manosh C Paul
Keyword(s):  
Particle Size ◽  
Coal Particle ◽  
Coal Gasification ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Underground Coal Gasification ◽  
Heater Temperature ◽  
Gasification Process ◽  
Coal Particles ◽  
Thermochemical Processes

Abstract In this study, a packed bed reactor is developed to investigate the gasification process of coal particles. The effects of coal particle size and heater temperature of reactor are examined to identify the thermochemical processes through the packed bed. Three different coal samples with varying size, named as A, B, and C, are used, and the experimental results show that the packed bed with smaller coal size has higher temperature, reaching 624oC, 582oC, and 569oC for coal A, B, and C respectively. In the case of CO formation, the smaller particle size has greater products in the unit of mole fraction over the area of generation. However, the variation in the porosity of the packed bed due to different coal particle sizes affects the reactions through the oxygen access. Consequently, the CO formation is least from the coal packed bed formed by the smallest particle size A. A second test with the temperature variations shows that the higher heater temperature promotes the chemical reactions, resulting in the increased gas products. The findings indicate the important role of coal seam porosity in UCG (underground coal gasification) application, as well as temperature to promote the syngas productions.

scholarly journals Characteristics of the Coal Fines Produced from Low-Rank Coal Reservoirs and Their Wettability and Settleability in the Binchang Area, South Ordos Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yue Chen ◽  
Zhuoyuan Ma ◽  
Dongmin Ma ◽  
Zhicang Zhang ◽  
Weibo Li ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Carbon Content ◽  
Size Distribution ◽  
Coalbed Methane ◽  
Ash Content ◽  
Settling Rate ◽  
Fixed Carbon ◽  
Fixed Carbon Content ◽  
Coal Fines

By using proximate analysis, X-ray diffraction mineral analysis, scanning electron microscope, contact angle measurement, and settlement simulation experiment, the coal fines produced from the coalbed methane wells of Binchang area were used to study the characteristics including particle size distribution, composition, morphology, wettability, and settleability. The results show that the particle size of coal fines produced from coalbed methane wells are mainly >20 mesh, ranging of 1-400 μm, and the particle size distribution curve is mainly dominated by the main-secondary bimodal type, with the main peak of 30-300 μm. The particle size from large to small is drill cutting coal fines, flowback coal fines, bailing coal fines, and pipeline filter coal fines. In terms of ash content, coal fines are higher than coal seam, and drilling cuttings are higher than bailing coal fines, while the fixed carbon content of the former is lower than that of the latter. The minerals of coal fines are mainly kaolinite, illite, quartz, and other 6 minerals, and the mineral types of drilling coal fines are the most abundant, while the bailing coal fines only contain illite and quartz. The roundness of coal fine particles ranges from excellent to poor in the order of bailing coal fines, pipeline filter coal fines, flowback coal fines, and drilling cuttings. However, the sorting of drilling cuttings is excellent, and the particle edges are straight, neat, and smooth, while the sorting of bailing coal fines is poor, and the particle edges are curved, uneven, and rough. The contact angles of coal fines are 40.25°-69.5°, indicating hydrophilous. The wettability of bailing coal fines is better than that of drilling cuttings. The particle size has a negative correlation with the wettability effect. The more obvious the modification effect of positive wetting agent is, the worse the modification effect of negative wetting agent is. The modification of surfactant has nothing to do with the particle size of the coal fines, but is closely related to organic components and minerals. The larger the coal particle size, the higher the settling rate, and the higher the ash content and the lower the fixed carbon content, the faster the settling rate. With the dividing point 150 mesh, the settling rate of large particles is mainly affected by particle size, while that of small particles is affected by the composition.

scholarly journals Comparative sorption and desorption of benzo[α]pyrene and 1,2,3-trichlorobenzene by biochar in the presence of dissolved organic matter  

2017 ◽  
Author(s):  
L. Cao ◽  
S. Kuang ◽  
J. Zhang ◽  
H. Wang ◽  
J. Wan
Keyword(s):  
Organic Matter ◽  
Citric Acid ◽  
Dissolved Organic Matter ◽  
Sorption Capacity ◽  
Sorption Isotherms ◽  
Aquatic Environments ◽  
Citric Acid Concentration ◽  
Halogenated Aromatic Hydrocarbons ◽  
Capacity Coefficient ◽  
Desorption Hysteresis

Sorption and desorption of benzo[α]pyrene (BaP) and 1,2,3-trichlorobenzene (TrCB) on biochar prepared from maple wood shavings heated at 500°C were studied in the presence of dissolved organic matter (DOM), including citric acid, l-phenylalanine (L-PH), and peptone. Compared to TrCB, BaP exhibited more nonlinear and stronger sorption on biochar. Nonlinearity of the sorption isotherms increased in the presence of DOM. The presence of citric acid enhanced the sorption capacity and desorption hysteresis of BaP and TrCB on biochar mainly due to the strong sorption of citric acid on the biochar surface. Moreover, there were positive relations between the concentration dependent sorption capacity coefficient (K<sub>d</sub>) values of BaP and TrCB and the citric acid concentration (P &lt; 0.01). In contrast, peptone reduced the sorption capacity and increased the sorption reversibility because of the partition of BaP and TrCB in the peptone solution. L-PH at 50–200 mg/l also leads to a decrease in the sorption capacity and irreversibility attributed to solubilization, although the sorbed L-PH on the biochar surface can slightly increase the BaP and TrCB sorption. At the same concentration, peptone leads to a higher decrease in the BaP and TrCB sorption than L-PH. Also, negative correlations were found between the K<sub>d</sub> values of BaP and TrCB, and the L-PH and peptone concentration (P &lt; 0.05). Our results may help understand the different impacts of DOM on the transport and fate of halogenated aromatic hydrocarbons in aquatic environments polluted with biochars.

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