Data Base for the Analysis of Compositional Characteristics of Coal Seams and Macerals. Final Report, Part 9. Interaction of Gases, Vapors and Liquids with Coals and Macerals at Ambient Temperatures: Their Use to Characterize Poro

摘要

The interaction of Hg, He, CO sub 2 , water, and methanol at room temperature with a wide variety of -20 mesh American coals and 45 maceral concentrates has been studied. This interaction has been used to characterize porosities in these coals and macerals. Displacement of Hg and He, from which densities of coals and macerals in these fluids were calculated, has been measured. Exposure of coals and macerals to these fluids results in little change in their structure. Hence, pore volumes calculated to be accessible to He from density data, are taken as true values. Pore volumes accessible to CO sub 2 , water, and methanol frequently exceed those accessible to He, despite its being a smaller molecule. This is attributed to the swelling of coals in the presence of CO sub 2 , water, and methanol due to a combination of adsorption on the walls of micropores and imbibition into the solid structure. Swelling in water and methanol was confirmed on many coals and macerals using a combination of fluid densities, as measured by use of a pycnometer, and fluid uptake, as measured gravimetrically. Swelling of coals and macerals in water and methanol increases significantly with decreasing rank. Expansion of beds of coal and maceral particles was measured in CO sub 2 and methanol using a dilatometer. Expansion in CO sub 2 increases sharply as CO sub 2 partial pressure (activity) is increased from 0.016 to 0.76. For coals of higher rank, expansion in CO sub 2 and methanol, at equivalent relative pressures, are similar. On the other hand, for coals of high volatile bituminous and lower ranks, expansion in methanol is considerably higher than that in CO sub 2 . The swelling of coals in different fluids is expected to have a profound influence on the rheology of the fluids. This has implications when coal-liquid slurries are used in combustion and gasification processes. 33 references, 16 figures, 19 tables. (ERA citation 09:032545)