A Study on the Spontaneous Ignition of Some Ligneous Pellets

A preliminary non-exhaustive study was conducted on the ignition of some ligneous biomass pellets inside a laboratory scale traveling bed furnace. The experiments consisted in the measurement of the ignition time of volatiles released by six different types of pellets, obtained from wood species found in the Portuguese forest, namely Pinus pinaster, Acacia dealbata, Cytisus scoparius, Cistus ladanifer, Paulownia cotevisa and Eucalyptus globulus. The experiments were carried out at corrected furnace temperatures of 359, 381, 403, 424 and 443 °C, using two different pellet sizes and with batches of 6 and 8 g of pellets. The ignition time was determined measuring the time elapsed between placing the batch of pellets on the traveling grate and the volatiles’ ignition moment. Its dependency was linear, and an increase in ignition time with the furnace temperature was verified. Pinus pinaster was the species that presented a higher ignition time and Cytisus scoparius the shortest. For the same pellets size, an increase in the mass of batches led to shorter ignition times.