Abstract:
Biomass is considered to be a promising renewable energy source and has attracted increasing attentions from researchers. Biomass pyrolysis is a promising thermochemical conversion technology, which can generate pyrolysis oil, bio-char and pyrolysis gas. In this paper, the effects of pyrolysis temperature on the yield and composition of low-grade tobacco pyrolysis products were investigated on the basis of a fixed-bed tubular reactor. The weight loss behavior of low-grade tobacco was studied by thermogravimetric analyzer at different heating rates. The kinetics mechanism function was determined by Coats-Redfern and FWO integral method combined with double extrapolation method. The results showed that the yield of pyrolysis oil underwent an initial increase with increasing the temperature, reaching the maximum value of 26.93% at 400 ℃. Further increase in temperature led to a decrease in the yield of pyrolysis, a increase in the yield of pyrolysis gas, and continuous decrease in the yield of bio-char. Pyrolysis oil is mainly composed of ketones, phenols, furans and nitrogen-containing heterocycles compounds. Pyrolysis gas is mainly composed of CO and CO
2. The pyrolysis process of low-grade tobacco can be divided into three stages: dehydration and drying stage; rapid pyrolysis stage; and carbonization stage. The main stage of pyrolysis can be divided into two sub-stages, the most probable mechanism function of the first sub-stage (
T0—
Tmax) is D3 (Jander equation), while the most probable mechanism function of the second sub-stage (
Tmax—
Tf) is D4 (G-B equation).