Coalbed methane adsorption and desorption characteristics related to coal particle size

• Published in: Chinese physics B Vol. 25; no. 6; pp. 542 - 551
• Main Author: 冯艳艳 杨文 储伟
• Format: Journal Article
• Language: English
• Published: 01.06.2016
• Subjects: Adsorption; Carbon dioxide; Coal; Desorption; Hysteresis; Particle size; Porosity; Surface chemistry; 动态吸附性能; 吸附能力; 比表面积; 气体吸附; 煤层气; 煤粉粒径; 解吸特性; 解吸等温线
• DOI: 10.1088/1674-1056/25/6/068102
• ISSN: 1674-1056

Effects of particle size on CH4 and CO2adsorption and desorption characteristics of coals are investigated at 308 K and pressures up to 5.0 MPa.The gas adsorption and desorption isotherms of coals with particle sizes ranging from 250 μm to 840 μm are measured via the volumetric method,and the Langmuir model is used to analyse the experimental results.Coal particle size is found to have an obvious effect on the coal pore structure.With the decrease of coal particle size in the process of grinding,the pore accessibility of the coal,including the specific surface area and pore volume,increases.Hence,coal with smaller particle size has higher specific surface area and higher pore volume.The ability of adsorption was highly related to the pore structure of coal,and coal particle size has a significant influence on coal adsorption/desorption characteristics,including adsorption capacity and desorption hysteresis for CH4 and CO2,i.e.,coal with a smaller particle size achieves higher adsorption capacity,while the sample with a larger particle size has lower adsorption capacity.Further,coal with larger particle size is also found to have relatively large desorption hysteresis.In addition,dynamic adsorption performances of the samples are carried out at 298 K and at pressures of 0.1 MPa and 0.5 MPa,respectively,and the results indicate that with the increase of particle size,the difference between CO2 and CH4adsorption capacities of the samples decreases.