caa a22 4500 378927922 CHVBK 20180305123622.0 cr unu---uuuuu 161128e20040308xx s 000 0 eng 10.2202/1542-6580.1135 doi (NATIONALLICENCE)gruyter-10.2202/1542-6580.1135 A 3D Model of Combustion in Large-Scale Circulating Fluidized Bed Boilers [Elektronische Daten] [Karsten Luecke, Ernst-Ulrich Hartge, Joachim Werther] In a circulating fluidized bed (CFB) combustor the reacting solids are locally fed into the combustion chamber. These reactants have to be dispersed across the reactor's cross-sectional area. Since the rate of mixing is limited this leads to a mal-distribution of the reactants and to locally varying reaction conditions. In order to describe the influence of mixing a three-dimensional model of the combustion chamber is suggested. The model is divided into three sub-topics. First, the flow structure in terms of local gas and solids velocities and solids volume concentrations is described. Second, mixing of the solids and the gas phase is quantified by defining dispersion coefficients, and finally the combustion process itself, i.e. the reaction kinetics, is modelled. The model was validated against data from measurements in the large-scale combustor of Chalmers University of Technology in Göteborg/Sweden. Insufficient fuel mixing generated mal-distributions of locally released volatiles, which were the basis for the uneven reactants distribution at steady-state. In the case of two-stage operation, the injected secondary air did not reach immediately the reactor's center but was slowly mixed with the main gas flow. The concentration gradients hardly vanish before the exit of the combustion chamber. ©2011 Walter de Gruyter GmbH & Co. KG, Berlin/Boston circulating fluidized bed nationallicence CFB nationallicence combustion nationallicence gas mixing nationallicence solids mixing nationallicence model nationallicence Luecke Karsten E-mail: kkluecke@dow.com aut Hartge Ernst-Ulrich Technical University of Hamburg-Harburg, Hartge@tu-harburg.de aut Werther Joachim Technical University of Hamburg-Harburg, werther@tu-harburg.de aut International Journal of Chemical Reactor Engineering De Gruyter 2/1(2004-03-08) 2:1 2004 2 ijcre https://doi.org/10.2202/1542-6580.1135 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.2202/1542-6580.1135 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Luecke Karsten E-mail: kkluecke@dow.com aut NATIONALLICENCE 700 1- Hartge Ernst-Ulrich Technical University of Hamburg-Harburg, Hartge@tu-harburg.de aut NATIONALLICENCE 700 1- Werther Joachim Technical University of Hamburg-Harburg, werther@tu-harburg.de aut NATIONALLICENCE 773 0- International Journal of Chemical Reactor Engineering De Gruyter 2/1(2004-03-08) 2:1 2004 2 ijcre CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter