Combustion of Lignite Coal in a Bubbling Fluidized Bed Combustor under Oxyfuel Conditions

Oxyfuel combustion is one of the leading technologies considered for capturing CO2. The field of oxyfuel combustion in a bubbling fluidized bed is recently addressed only marginally, but it is more suitable for lower capacity loads. The paper presents some results from bubbling fluidized bed oxyfuel combustion of lignite coal from 25 kW experimental device and 250 kW pilot BFB boiler. The methodology of the results presentation is stated and confrontation of the experimental results with the mathematical model is presented. The experiments were focused on identification of the oxyfuel regime operation and determination of the different CO2/O2 ratio in fluidized medium. The CO2 flue gas concentration was for the majority of experiments kept in the range of 84 to 91% and the oxygen concentration in flue gas from 4 to 8% in case of smaller laboratory combustor. Pilot BFB combustor suffers more with air leakage but the results correspond to the reality of the real operation of these facilities in an industrial scale.