Oxidation of a coal particle in flow of a supercritical aqueous fluid

Abstract

A study was made of the conversion of single spherical coal particles of diameter 1-5 mm in a supercritical H 2 O/O 2 fluid with an oxygen mass fraction of 0-6.6% in a semibatch reactor at a pressure of 30 MPa and a temperature of 673-1023 K. A decrease in the particle mass was observed in two parallel processes: gasification of coal with water and oxidation of coal with oxygen. An activation energy 19 ± 7 kJ/mole and a pre-exponential factor 10 −2±0.4 sec −1 were obtained under the assumption of zero order for the concentration H 2 O and an Arrhenius dependence for the rate of gasification with water. The oxidation with oxygen at a temperature above 780 K was found to be limited by the rate of O 2 diffusion to the coal organic matter. Below 780 K, the rate of heterogeneous oxidation with oxygen is described by a first-order reaction for the concentration of O 2 and a zero-order reaction for the concentration of H 2 O with an activation energy of 150 ± 27 kJ/mole and a pre-exponential factor of 10 7.6±1.9 cm 3 /(g · sec).

Mathematical Modeling for Coal Gasification Kinetics in Supercritical Water

“…Various type of coal could be processed in SCW according to previous research. ,,− Kinetic data were evaluated with Zhundong coal as feedstock in the present study. The applicability of current kinetic model to other type of coal also needs to be explored.…”