Intraparticle gas sampling during biomass non-oxidant thermal treatment for kinetic behavior study
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Literature shows contradictive data respect to energy change happening inside a biomass sample during thermal treatment. To better understand whether exothermic or endothermic reactions take place inside of the pyrolyzed material, heat of reaction and temperature calculations were made based on in-particle gas composition. To our knowledge, this is the first intraparticle gas sampling measurement performed during non-oxidant thermal treatment. Spherical wooden particles of different sizes (19.0 mm and 31.8 mm diameter) have been subjected to a pyrolysis process at operating temperatures of 500°C, in a tubular reactor under non-oxidant (340 cm3/min of Helium) controlled conditions. Gas chromatography analysis of the evolved gas has been performed, sampling them from the center of the particle. Simultaneously, temperature measurements were monitored on the surface and in the center of the wooden sphere. The GC detected CO2, CO, CH4, C2H 6, C2H4 and H2 gas components, their distribution being presented as a function of temperature and time. The temperature data showed a peak of temperature at the center of the particle, with differences of about 20°C to 50°C between the temperatures in the center and on the surface of the particle. The presence of He, used as a sweep gas, in significant concentrations in the center of the sample, starting on the first minute of experiment reveals high porosity of the material, which increases along with devolatilisation rate.