Interaction between Supercritical CO2 and Coal Petrography

2012 ◽  
Vol 616-618 ◽  
pp. 306-309 ◽  
Author(s):  
Run Chen
Keyword(s):  
Pore Structure ◽  
Supercritical Fluid ◽  
Gas Adsorption ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Organic Matters ◽  
Coal Swelling ◽  
Coal Petrography

CO2enhanced CBM recovery(CO2-ECBM) is an important way for reducing CO2emission into atmosphere and enhancing coal-bed methane (CBM) recovery. The interaction between supercritical CO2and coal petrography has been investigated since the 1990s. Advances in the interaction between supercritical CO2and coal petrography are reviewed in light of certain aspects, such as the competitive multi-component gas adsorption, sorption-induced coal swelling/shrinkage and the fluid-solid coupling between fluids(such as gas, liquid and supercritical fluid) and coal petrography. It is suggested that a comprehensive feasibility demonstration is necessary for a successful application of the technology for CO2-ECBM. At the same time, it also indicated that there are some questions must be discussed in future, such as the influences on pore structure, coal adsorptivity and permeability of the reaction of ScCO2-H2O and rock and small organic matters are extracted by supercritical CO2.

scholarly journals Changes in Pore Structure of Coal Caused by CS2 Treatment and Its Methane Adsorption Response

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Run Chen ◽  
Yong Qin ◽  
Pengfei Zhang ◽  
Youyang Wang
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Gas Adsorption ◽  
Recovery Process ◽  
Micropore Volume ◽  
Methane Adsorption ◽  
Coal Bed ◽  
Methane Recovery ◽  
Before And After ◽  
Key Issues

The pore structure and gas adsorption are two key issues that affect the coal bed methane recovery process significantly. To change pore structure and gas adsorption, 5 coals with different ranks were treated by CS2 for 3 h using a Soxhlet extractor under ultrasonic oscillation conditions; the evolutions of pore structure and methane adsorption were examined using a high-pressure mercury intrusion porosimeter (MIP) with an AutoPore IV 9310 series mercury instrument. The results show that the cumulative pore volume and specific surface area (SSA) were increased after CS2 treatment, and the incremental micropore volume and SSA were increased and decreased before and after Ro,max=1.3%, respectively; the incremental big pore (greater than 10 nm in diameter) volumes were increased and SSA was decreased for all coals, and pore connectivity was improved. Methane adsorption capacity on coal before and after Ro,max=1.3% also was increased and decreased, respectively. There is a positive correlation between the changes in the micropore SSA and the Langmuir volume. It confirms that the changes in pore structure and methane adsorption capacity due to CS2 treatment are controlled by the rank, and the change in methane adsorption is impacted by the change of micropore SSA and suggests that the changes in pore structure are better for gas migration; the alteration in methane adsorption capacity is worse and better for methane recovery before and after Ro,max=1.3%. A conceptual mechanism of pore structure is proposed to explain methane adsorption capacity on CS2 treated coal around the Ro,max=1.3%.

scholarly journals Experimental Analysis of Pore Structure and Fractal Characteristics of Soft and Hard Coals With Same Coalification

2021 ◽  
Author(s):  
Barkat Ullah ◽  
Yuanping Cheng ◽  
Liang Wang ◽  
Weihua Yang ◽  
Izhar Mithal Jiskani ◽  
...  
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Gas Adsorption ◽  
Hysteresis Loops ◽  
Control Measures ◽  
Practical Significance ◽  
Coal Bed ◽  
Hard Coal ◽  
Pore Surface ◽  
Soft Coal

Abstract Accurate and quantitative investigation of the physical structure and fractal geometry of coal has important theoretical and practical significance for coal bed methane and the prevention of dynamic disasters such as coal and gas outbursts. This study investigates the pore structure and fractural characteristics of soft and hard coals using nitrogen and carbon dioxide (N2/CO2) adsorption. Coal samples from Pingdingshan Mine in Henan province of China were collected and pulverized to the required size (0.2-0.25mm). N2/CO2 adsorption tests were performed to evaluate the pore size distribution (PSD), specific surface area (SSA), and pore volume (PV). The pore structure was characterized based on fractural theory. The results unveiled that the strength of coal has a significant influence on pore structure and fracture dimensions. The obvious N2-adsorption isotherms of the coals were verified as Type IV (A) and Type II. The shape of the hysteresis loops indicates the presence of slit-shaped pores. There are significant differences in SSA and PV between both coals. The soft coal showed larger SSA and PV than hard coal that shows consistency with adsorption capacity. The fractal dimensions of soft coal are respectively larger than that of hard coal. The greater the value of D1 (complexity of pore surface) of soft coal is, the larger the pore surface roughness and gas adsorption capacity is. The results enable us to conclude that the characterization of pores and fractures of soft and hard coals is different, tending to different adsorption/desorption characteristics and outburst sensitivity. In this regard, results provide a reference for formulating corresponding coal and gas outburst prevention and control measures.

scholarly journals Effects of micropore structure of activated carbons on the CH4/N2 adsorption separation and the enrichment of coal-bed methane

Clean Energy ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 329-338
Author(s):  
Jinhua Zhang ◽  
Lanting Li ◽  
Qiang Qin
Keyword(s):  
Pore Structure ◽  
Adsorption Process ◽  
Activated Carbons ◽  
Chemical Properties ◽  
Dynamic Effect ◽  
Decisive Role ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Separation Coefficient ◽  
Separation Performance

Abstract In the process of enriching CH4 from coal-bed methane, the separation of CH4/N2 is very difficult to accomplish by an adsorption process due to the similar physico-chemical properties of the two molecules. A series of coconut-shell-based granular activated carbons (GACs) with different pore structures were prepared, which were characterized by different methods. The influence of the pore structure on the separation properties was investigated in detail. The results show that one of the carbons prepared (GAC-3) has high CH4 equilibrium adsorption capacity (3.28 mol·kg–1) at 298 K and equilibrium separation coefficient (3.95). The CH4/N2 separation on the GACs is controlled by adsorption equilibrium as compared with the dynamic effect. Taking the specific surface area, for example, the common characterization index of the pore structure is not enough to judge the separation performance of the GACs. However, the microstructure of carbon materials plays a decisive role for CH4/N2 separation. According to the pore-structure analysis, the effective pore size for the CH4/N2 separation is from 0.4 to 0.9 nm, with the optimum effect occurring in the range of 0.6–0.7 nm, followed by the range of 0.7~0.9 nm. Also, a four-bed vacuum pressure swing adsorption process was adopted to evaluate the performance of GACs for the separation of CH4 from nitrogen.

Fractal classification and natural classification of coal pore structure based on migration of coal bed methane

2005 ◽  
Vol 50 (S1) ◽  
pp. 66-71 ◽  
Author(s):  
Xuehai Fu ◽  
Yong Qin ◽  
Wanhong Zhang ◽  
Chongtao Wei ◽  
Rongfu Zhou
Keyword(s):  
Pore Structure ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Natural Classification

The modification of activated carbons and the pore structure effect on enrichment of coal-bed methane

2008 ◽  
Vol 3 (3) ◽  
pp. 284-291 ◽  
Author(s):  
Guo-Feng Zhao ◽  
Peng Bai ◽  
Hong-Mei Zhu ◽  
Ri-Xiong Yan ◽  
Xin-Mei Liu ◽  
...  
Keyword(s):  
Pore Structure ◽  
Activated Carbons ◽  
Structure Effect ◽  
Coal Bed ◽  
Coal Bed Methane

scholarly journals Adsorption Factors in Enhanced Coal Bed Methane Recovery: A Review

Gases ◽  
2022 ◽  
Vol 2 (1) ◽  
pp. 1-21
Author(s):  
Theodora Noely Tambaria ◽  
Yuichi Sugai ◽  
Ronald Nguele
Keyword(s):  
Density Functional ◽  
Gas Adsorption ◽  
Experimental Studies ◽  
Analytical Techniques ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Resonance Spectroscopy ◽  
Methane Recovery ◽  
13C Nuclear Magnetic Resonance ◽  
Adsorption Of Co2

Enhanced coal bed methane recovery using gas injection can provide increased methane extraction depending on the characteristics of the coal and the gas that is used. Accurate prediction of the extent of gas adsorption by coal are therefore important. Both experimental methods and modeling have been used to assess gas adsorption and its effects, including volumetric and gravimetric techniques, as well as the Ono–Kondo model and other numerical simulations. Thermodynamic parameters may be used to model adsorption on coal surfaces while adsorption isotherms can be used to predict adsorption on coal pores. In addition, density functional theory and grand canonical Monte Carlo methods may be employed. Complementary analytical techniques include Fourier transform infrared, Raman spectroscopy, XR diffraction, and 13C nuclear magnetic resonance spectroscopy. This review summarizes the cutting-edge research concerning the adsorption of CO2, N2, or mixture gas onto coal surfaces and into coal pores based on both experimental studies and simulations.

scholarly journals A theoretical model for coal swelling induced by gas adsorption in the full pressure range

2020 ◽  
Vol 38 (3-4) ◽  
pp. 94-112
Author(s):  
Ping Guo
Keyword(s):  
Theoretical Model ◽  
Pressure Range ◽  
Gas Adsorption ◽  
Coal Bed ◽  
Model Parameters ◽  
Model Errors ◽  
Mixed Gas ◽  
Methane Recovery ◽  
Coal Swelling ◽  
Full Pressure

The phenomenon of coal swelling caused by gas adsorption is well known. For Enhanced Coal Bed Methane Recovery and carbon storage, coal swelling induced by gases adsorption may cause significant reservoir permeability change. In this paper, based on the assumption that the surface energy change caused by adsorption is equal to the change in elastic energy of the coal matrix, a theoretical model is derived to describe coal swelling induced by gas adsorption in the full pressure range. The Langmuir constant, coal density, solid elastic modulus, and Poisson’s ratio are required in this model. These model parameters are easily obtained through laboratory testing. The developed model is verified by available experimental data. The results show that the presented model shows good agreement with the experimental observations of swelling. The model errors are within 14% for pure gas, and within 20% for mixed gas. It is shown that this model is able to describe coal swelling phenomena for full pressure range and different gas type including pure gas and mixed. In addition, it is also shown that the errors of the presented model and the Pan’s model are almost the same, but the presented model is solved more easily.

Sign in / Sign up

Export Citation Format

Share Document