A non-isothermal experimental technique to study coal extraction with solvents in liquid and supercritical state

Abstract

A non-isothermal experimental technique is presented to study the mechanism of coal extraction with solvents at sub- and super-critical temperatures between 20 °C and 550 °C and pressures up to 15 MPa. With slowly rising temperature, the formation rates of extract and gaseous coal decomposition products are measured in a fixed bed of coal, which is percolated by a pressurized solvent. Since the extraction temperature rises above the solvent critical temperature, both sub- and super-critical extraction are covered in one experiment. The formation rate profiles exhibit characteristic differences depending on coal type, solvent and extraction conditions. An interpretation of these differences makes it possible to separate overlapping effects of chemical reactions, phase equilibria and mass transport during coal extraction.