Size- and temperature-dependent oxidative pyrolysis and auto-ignition of spherical beech and spruce wood

Abstract Opposed to piloted ignition, where a substance is ignited by an external flame or spark, the term auto-ignition describes onset of combustion spontaneous ignition without source. In this study, influence size spherical wood samples and temperature surrounding was investigated performing experiments in muffle furnace with beech spruce wood. On specially constructed rig, spheres four different diameters (8 mm, 12 18 25 mm) were put into preheated at five isothermal temperatures (240 °C, 270 300 330 360 °C). For every temperature, diameter, species, repeated eight times, positions on rig changed for measurement. Temperatures inside recorded thermocouples (TC) positioned holes drilled middle spheres. With rising more prone glowing mode, due larger, highly reactive pyrolyzed surface internal overheating. During heating oxidative pyrolysis, phases present approximately °C curves. The comparison simultaneous thermal analysis (STA) measurements shows decomposition hemicelluloses, cellulose highest around °C. It concluded that pyrolysis disintegration main constituents use up all arising energy. Due differences composition polymers, already ignite lower compared same diameter. can be critical factor used temperatures. Larger will produce volatile compounds during have larger pyrolyzed, porous area heterogenous oxidation reactions happen. millimetre scale.