Biomass Torrefaction Reactor

Feedstock

Reactor Conditions

Temperature 250 °C

Residence time 20 min

Product Quality

Light torrefaction

Solid mass yield

–

Energy yield

–

Product HHV

–

Densification

–

How it works

Torrefaction is mild, oxygen-free "roasting" of biomass at 200–320 °C: too cool to pyrolyse the wood, but hot enough to break down its most reactive component — hemicellulose — while cellulose and lignin stay largely intact. The result is a drier, darker, more brittle solid with a higher energy density than the raw feedstock: a coal-like drop-in biofuel.

This simulator uses a two-component parallel first-order kinetic model, the standard simplification in torrefaction literature (Prins et al. 2006; Bates & Ghoniem 2012). Remaining solid mass fraction:

M(t) = w_H · e^(−k_H t)  +  w_C · e^(−k_C t)

k_i = A_i · e^(−E_i / R T)      (Arrhenius, R = 8.314 J/mol·K)

w_H is the reactive hemicellulose fraction (higher for straw than for wood chips), w_C the near-inert cellulose+lignin fraction. Because volatiles carry away proportionally less energy than mass, the retained energy fraction falls slower than the mass fraction:

Energy yield  Y_e ≈ M(t)^0.75
Product HHV   = HHV₀ · M(t)^(−0.25)

Temperature — raises both rate constants; below ~230 °C almost nothing reacts (drying-only regime), above ~280 °C hemicellulose is consumed within minutes.
Residence time — how long the charge stays in the heated zone; scrub it directly, or press Run to animate it.
Feedstock — straw/herbaceous biomass carries more hemicellulose and a lower activation energy, so it torrefies faster and to a lower ceiling HHV than woody chips.
Smoke leaving the drum is drawn proportional to the instantaneous decomposition rate |dM/dt| — the real off-gas stream (acetic acid, furfural, CO, CO₂) that a torrefaction plant burns to help heat the reactor.

Heater coil (temperature) Volatile off-gas

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