Experimental Study On Utilization Of Surfactants In Reducing Gas Emission

Due to the serious situation of frequent coal mine accidents which resulted in a huge threat and a severe impact, this dissertation explained the significance of the research, did a comprehensive analysis on current situation of gas control technologies and surfactant application in the prevention and treatment of gas, determined the ideas, contents and methods of the experimental studies, developed a "theory - equipment development - experimental determination– contrast and comparison- summarization" research program.In view of the achievements of previous studies, this dissertation starts with the study of the gap structures of coal and coal seam gas hosting law, focuses on the study of gas emission rules of particles of coal, clearly proposes that the emission of gas from the coal dust is a process of gas diffusion in porous media and the diffusion of coal particles follows the exponential distribution. Based on the systematic study of the property,features and structural performance of surfactant, the dissertation has done a deep research on the mechanism of surfactant solution blocking gas. For the first time it discussed that capillary driving forces and molecular attractive forces are significant during the process of wetting coal by solution so as to sealing gas, reducing gas emission. It also studied surfactant solution’s effects on the improvement of the capacity of gas adsorption and temperature’s effect on decreasing gas desorption. According to the experimental measurements, the changes in the capillary driving force were calculated. It was pointed that capillary driving force increased an average of 2.65 times, even 4.03 times at the maximum, after adding surfactant solutions .According to the performance of surfactants and selection principles, 6 suitable surfactants were selected and 58 kinds of compound combinations were made. In accordance with the experimental program, I determined surface tentions, contact angles and critical micellar concentration of surfactant monomer solution and compound combinations solution. After the analysis of the results of the study, the optimum reagent and its concentration were determined. In the experimental study of gas sealing part, on the basis of the experimental contents, purpose and requirements, a detailed experimental program was made. I designed the testing system of gas desorption. In terms of raw coal samples, water soaked coal samples, and surfactant-treated samples selected from 5 differdent high gas mines, we respectively determined the intensity of gas desorption in three different pressure conditions. The effects that the surfactant solutions have in blocking gas were investigated. Through comparison, analysis and calculation, gas desorption rate decreased an average of 64.72% when compared with raw coal samples, however, gas desorption rate decreased an average of 14.7% when compared with water-treated coal samples. Thus the conclusion was made that appropriate surfactant solution can improve the surface properties of coal particles, improve the solution’s ability of sealing gas, reducing gas emission intensity, which opens up new ideas and technical approaches for coal mine gas control.