In order to study the effect of cooling rate on the surface morphology and subsequent pyrolysis, cornstalks were torrefied at different temperatures （200, 230, 260 and 290 ℃）, and were cooled by two methods： fast cooling （TF） and slow cooling （TS）.Scanning electron microscopy （SEM） was used to observe the surface morphology of the raw and torrefied samples. It was found that the surface of TS samples was looser than that of TF and raw samples at the same torrefaction temperature. The samples were also put into thermogravimetric analyzer for pyrolysis experiments. The results showed that the maximum weight loss rates of all the torrefied samples decreased with the increasing torrefaction temperature. The maximum weight loss rate of TS samples and TF samples showed little difference at the same torrefaction temperature, and the lowest maximum weight loss rate of TS samples was 2.94%/℃ at 290 ℃. At the same time, the higher the torrefaction temperature, the higher the peak temperature corresponding to the maximum weight loss rate. The pyrolysis activation energy of TS samples at 200, 230 and 290 ℃ were lower than that of TF samples at the same temperature, respectively, but it was opposite for TS260 sample, which has the highest activation energy about 100.43 kJ/mol.
Key words
biomass /
torrefaction /
pyrolysis /
cooling rate /
activation energy /
cornstalks
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