Attrition-free pyrolysis to produce bio-oil and char

Experiments are performed on a laboratory scale setup where beech wood chips are heated by gas convection and walls radiation. This study shows that it is possible to obtain high bio-oil and char yields with relatively low external heat transfer coefficients. The main advantage of this convection/radiation heat transfer mode compared to solid–solid collisions, applied in fluidized bed or twin screw reactors, is the reduction of solid attrition (char and sand). Thus tricky gas–solid separation through hot cyclones and/or hot filters could be avoided or reduced. It should be possible to recover directly bio-oil with less char particles and char free of sand dust. These qualities would allow easier use of these bio-products in different applications.