Wood Combustion in an Overfeed Packed Bed, Including Detailed Measurements within the Bed

Measurements of local gas and tar concentrations, temperatures, and properties of samples of bed solids are reported for wood combustion in an overfeed packed bed. A novel probe is introduced for the measurement of tar concentrations in situ, which collects tar samples on small filter elements. It is shown to give credible values of local tar concentrations at different locations in the bed. Particle sizes and properties are measured by analysis of samples from the bed materials taken after shut-down. A previously developed detailed numerical model of packed bed char combustion is extended by the addition of a one-step pyrolysis reaction and compared with experimental measurements. The model is shown to give good agreement with measured quantities using physically reasonable values of the pyrolysis reaction rate parameters.