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Devolatilization and heterogeneous combustion of wood fast pyrolysis oils
No full textWeight loss curves of wood fast pyrolysis oils in air have been measured, under controlled thermal
conditions, carrying out two separate sets of experiments. The first, which has a final temperature
of 600 K, concerns evaporation/cracking of the oil and secondary char formation, processes
associated with sample swelling and solidification. After collection and milling, in the second
set of experiments, heterogeneous combustion of the secondary char is carried out to temperatures
of 873 K. Although the details of the rate curves appear to be dependent on the commercial
process (BTG, Dynamotive, Ensyn, Pyrovac) applied to produce the oil, the same qualitative
features are observed in all cases. Secondary char formation and sample modification begin for
temperatures of about 460-490 K. Moreover, a conceptual reaction mechanism, consisting of
six main zones, can always explain the low-temperature (e600 K) devolatilization characteristics.
Similar to primary char produced from wood pyrolysis, secondary char exhibits weight loss curves
that present a devolatilization stage and a combustion stage, but with a significantly lower
reactivity, as a consequence of a physical structure completely lacking micropore networks
[Fogging effect in the ischemic cerebral infarction to computerized tomography (author's transl)]
No full textL'indagine radiologica nelle spondilodisciti conseguenti ad intervento per ernia del disco lombare
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