Influence of pressure on the heterogeneous formation and destruction of nitrogen oxides during char combustion

Changes in total active centres on particle surfaces during coal pyrolysis, gasification and combustion

“…In records of heterogeneous coal combustion reactions, many authors (Croiset et al, 1996;Croiset et al, 1998;De Soete, 1990;Johnson, 1987;Krammer and Sarofim, 1994;Stanmore, 1991) use the term 'active centres' (e.g. [C], [CO], [CN], [CNO]) on a carbon matrix.…”

“…[C], [CO], [CN], [CNO]) on a carbon matrix. However, they do not determine initial total active centers and their changes during the combustion process and only use active centre fractions (Croiset et al, 1998;De Soete, 1990;Krammer and Sarofim, 1994). A part of a coal char combustion model has been presented as four heterogeneous reactions with active centres:…”

Fuel-N Conversion to NO, N2O and N2 During Coal Combustion

“…as well as demonstrated reduction of conversion into N 2 O, which is contradictory to the findings of Weiszrock et al (1997), while Lu et al (1992) did not find any effects of the combustion pressure on nitrogen conversion into N 2 O. Croiset et al (1996Croiset et al ( , 1998 (1999) complemented the model with the efficiency of particle volume application in the reaction of [CO] and {CNO] active centre formation. They also compared kinetic coefficients of individual reactions published by Croiset et al (1996Croiset et al ( , 1998 for "Westerholt" coal (at 0.2 MPa) and by de Soete (1990) for "Prosper" coal (at 0.1 MPa), but they did not make any comments on kinetic coefficients for higher pressures presented by Croiset et al (1998).…”

“…Croiset et al (1996Croiset et al ( , 1998 (1999) complemented the model with the efficiency of particle volume application in the reaction of [CO] and {CNO] active centre formation. They also compared kinetic coefficients of individual reactions published by Croiset et al (1996Croiset et al ( , 1998 for "Westerholt" coal (at 0.2 MPa) and by de Soete (1990) for "Prosper" coal (at 0.1 MPa), but they did not make any comments on kinetic coefficients for higher pressures presented by Croiset et al (1998). Gil (2000, 2001) as well as Gil (2000) proposed their model of NO and N 2 O formation and reduction in pressurised char combustion based on chemical reactions presented by de Soete (1990) and Croiset et al (1998).…”

“…They also compared kinetic coefficients of individual reactions published by Croiset et al (1996Croiset et al ( , 1998 for "Westerholt" coal (at 0.2 MPa) and by de Soete (1990) for "Prosper" coal (at 0.1 MPa), but they did not make any comments on kinetic coefficients for higher pressures presented by Croiset et al (1998). Gil (2000, 2001) as well as Gil (2000) proposed their model of NO and N 2 O formation and reduction in pressurised char combustion based on chemical reactions presented by de Soete (1990) and Croiset et al (1998). They determined their own kinetic coefficient of NO reduction over char where the activation energy of char was 79 kJ/mol within the pressure range of 0.2 MPa to 1.0 MPa.…”