Research On Adsorption And Desorption Thermodynamics Of Carbon Monoxide In The Seam Of Coal Mine

According to the fact that although CO longterm excess-standard appeared in low-to-medium metamorpic grade coal seams, coal spontaneous ignition has not occurred. Eight typical coal samples were collected from four coal mines. In each coal mine two coal samples were collected from different places in the same coal seams. The coal and rock of typical coal samples are separated. Then adsorption test of typical coal samples with different maceral compositions on CO is made at different temperature and pressure. The adsorption volume measured from experiment is corrected so that the deviation of comprehension to the adsorption characteristics is not caused.Comprehensive thermodynamic studies on the adsorption capacity are conducted with the knowledge of physical chemistry, interface chemistry, coal petrology, coal chemical engineering and corrected adsorption data. Several classical adsorption models are evaluated and the optimal one is selected out to describe adsorption process of the CO gas on coal. The model of Langmuir is selected out to describe adsorption process of the CO gas on coal under t≤50℃. Adsorptivity is evaluated from three aspects, including specific surface area, adsorption capacity on per surface area and interaction between CO molecule and coal surface. Further studies of adsorption mechanism of CO on coal are made from the adsorption characteristic curve based on potential theory, a formula for adsorption capacity, pressure and temperature is obtained. On the base of this method put forward in this paper, the adsorption capacity under other equilibrium conditions can be obtained as long as we have the adsorption capacity at any temperature. The research results have important significance to studies of adsorption mechanism of CO on coal.With a view of microscopic, the main factors impacting the diffusion of CO on coal seams are the mean free path of CO and the distribution of micropore of coal in different sizes. According to the molecular-kinetic theory, mechanism on diffusion of CO gas in the coal seam has been discussed microscopically with the increasedpressure and temperature. According to coal seams with different porosity distribution, the suitable condition of various diffusion patterns has been discussed with measured porosity distribution datas of coal samples obtained form partial coal mines in Hebei Province.