Characterization of the Devolatilization Rate of Solid Fuels in Fluidized Beds by Time-Resolved Pressure Measurements

The characterization of volatile matter (VM) release from solid fuel particles during fluidized-bed combustion/gasification is relevant to the assessment of the reactor performance, as devolatilization rate affects in-bed axial fuel segregation and VM distribution across the reactor. An experimental technique for the characterization of the devolatilization rate of solid fuels in fluidized beds is proposed. It is based on the analysis of the time series of pressure measured in a bench-scale fluidized-bed reactor as VM is released from a batch of fuel particles. A remarkable feature of the technique is the possibility to follow fast devolatilization with excellent time-resolution. A mathematical model of the experiment has been developed to determine the time-resolved devolatilization rate, the devolatilization time and the volume-based mean molecular weight of the emitted volatile compounds. Devolatilization kinetics has been characterized for different solid fuels over a broad range of particle sizes.