Analysis of Coal Combustion in Oxy-fuel Conditions through Pulsed Feeding Experiments in an Entrained Flow Reactor

Coal combustion is investigated in both air and oxy-fuel conditions by feeding pulses of coal particles in an entrained flow reactor able to provide high residence times. The radiant energy emitted in the range from UV to IR was collected by several photodiodes operating with high acquisition rate. The signal analysis showed the capability of the technique to capture the passage of coal streams and to identify different phenomena (e.g., volatiles ignition, char oxidation). The spatial arrangement of the photodiodes was planned in order to allow also deriving quantitative information, such as particle velocity, ignition delay, and devolatilization time, from the correlation of more signals. The ignition delay was found to be higher in oxy-fuel conditions than in air, mainly because the larger specific heat of the oxy-fuel environment. The proposed diagnostics may help the qualification of advanced experimental apparatus as entrained flow reactors, with the purpose to make them suited for heterogeneous kinetics studies in oxy-fuel conditions.