Slow pyrolysis is mainly for production of charcoal. Biomass typically is heated to around 500 ºC with vapour
residence of 5 min to 30 min. The heating rate in slow pyrolysis is much slower than that used in fast pyrolysis.
Vapours in slow pyrolysis do not escape rapidly. Thus, the components in the vapour phase continue to react with
each other, as the solid char and any liquid are being formed. Slow pyrolysis processes normally produce
18-30 mf wt% of liquid bio-oil, 20-35 mf wt% of solid char, and 30-40 mf wt% of gases, depending on the
feedstock used