Steam gasification kinetics and burn-off behaviour for a bituminous coal derived char in the presence of H2

Gasification inhibition in chemical-looping combustion with solid fuels

“…Thus, under the experimental conditions in the fluidized-bed reactor the observed hydrogen inhibition can be attributed predominantly to the formation of C(H) surface complexes. This finding is in line with findings by Weeda et al [23], who observed the same hydrogen inhibition mechanism for the gasification of a high volatile bituminous coal char. It is also in line with Giberson and Walker [19], who investigated the oxidation of graphite by water vapor in the presence of hydrogen.…”

“…This means that an increase of the rate of conversion with increasing burn-off as predicted by the Random Pore Model [20], which is frequently used to describe reactivity changes during gasification, could not be observed. This finding is in line with gasification experiments conducted with a bituminous coal derived char, where the Random Pore Model could also not be applied to gasification in H 2 O/H 2 mixtures [23].…”

“…For this gasification either steam or CO 2 can be used. Steam and CO 2 gasification is a well examined field and there is vast selection of literature that covers most aspects, for example [17][18][19][20][21][22][23][24][25].…”

Steam Gasification of Wood Char and the Effect of Hydrogen Inhibition on the Chemical Kinetics

“…For the traditional hydrogen inhibition model, the formation of the C(H) 2 complex is the reason for inhibition. Finally, the second version of the hydrogen inhibition model involves a dissociative chemisorption of hydrogen on the active sites 27,28 , blocking them for the oxygen transfer reaction with steam. The reaction rate for the models presented is similar, with the exception of dependency on hydrogen partial pressure:…”

Effect of fuel particle size on reaction rate in chemical looping combustion

“…One way of doing this is to introduce the coal directly to the fuel reactor where the gasification of the coal and subsequent reactions with the metal oxide particles will occur simultaneously (Lyon and Cole, 2000;Dennis et al, 2006;Scott et al, 2006;Gao et al, 2008;Leion et al, 2008b;Rubel et al, 2009). A few circulating CLC units operating with this principle have recently been erected (Andrus et al, 2005;Lyngfelt, 2008a, 2008b;Shen et al, 2009) and there is plenty of gasification literature for example (Wen and Lee, 1979;Weeda et al, 1993;Walker et al, 1959;Su and Perlmutter, 1985).…”