**5.4 Ablative pyrolysis reactor**

Ablative pyrolysis reactor is basically different in concept compared to the other methods of fast pyrolysis. In ablative pyrolysis, biomass is pressed against a heated surface and rapidly moved during which the biomass melts at the heated surface and leaves an oil film behind which evaporates. In the other reactors mentioned above, the rate of reaction is limited by the rate of heat transfer through a biomass particle, that is why fine particles are required. This ablative process uses larger biomass particles and is typically limited by the heat supply rate to the reactor. The rate of reaction is strongly affected by pressure, the relative velocity of biomass on the heat exchange surface, and the reactor surface temperature [41, 42].
