The effects of pressure on coal chars porous structure development

The porous structure of chars determine their physical, mechanical and sorption properties, affecting the heat and mass transport in thermochemical processing and sorption capacity when the post-process residues are concerned. The available data on the pressure related porous structure development is limited, and the results may be often considered contradictory, unless complex interactions between various operating parameters are examined simultaneously. In the study the effects of pyrolysis pressure from 1 to 4 MPa on bituminous coal chars surface characteristics are presented. The enhanced porous structure development was observed with the increasing pyrolysis pressure up to 3 MPa, indicating a major role of pressure related swelling behavior of a parent coal in modeling the surface characteristics of chars under the operating parameters applied. The process parameters selected in order to better represent the conditions of the underground coal gasification differentiate the research from the previous literature, where high heating rates and short residence times are applicable. Therefore, the results complement the limited data available in the field concerned. They are also of both cognitive and practical importance in the considerations related to the thermochemical processing of coal as well as the sorption phenomena in the vicinity of the underground coal gasification.