Calculation method of energy balance during biomass torrefaction was established based on the analysis of biomass torrefaction process. According to the results of polar branch (PB) torrefaction in a fixed bed reactor, the effect of torrefaction temperature and holding time on characteristics of torrefied products (PB biochar, liquid product and gaseous product), heat requirement and energy distribution during torrefaction were studied. The energy balance of PB torrefaction was also discussed. The results indicated that torrefaction temperature was a key influence factor on biochar mass yield, heating value and energy distribution. The mass yield of PB biochar decreased significantly and mass yields of liquid and gaseous products increased gradually with increasing torrefaction temperature. At the same time, the heating values of PB biochar and gaseous product increased, and the heating value of liquid product had no remarkable change correspondingly. The energy of PB biochar was significant higher than that of liquid and gaseous products. The energy balance ratio of PB torrefaction showed a tendency of increase first and then to be stable with increasing torrefaction temperature. 64.0% of biochar mass yield can be obtained through PB torrefaction at the temperature of 225℃ and the holding time of 30 min, and the relevant energy balance ratio was 2.5. At this condition, the heat produced from combustion of gaseous and liquid products could completely meet the requirement of energy self-supported during PB torrefaction.
Yangtian YE Honghong CHEN Ping LU
. Analysis of Energy Balance during Biomass Torrefaction[J]. The Chinese Journal of Process Engineering, 2018
, 18(3)
: 575
-581
.
DOI: 10.12034/j.issn.1009-606X.217337
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