A carbonaceous feed pyrolysis apparatus is provided including two or more hot particle fluidised beds, one of which contains a combustion zone, and one or more positive displacement apparatus for the transfer of hot particles beds. Also provided is a bio-oil production process including two or more fluidised beds, a first combustion zone carried out in one or more combustion fluidised beds in which a particulate material is fluidised and heated, and a second pyrolysis zone carried out in one or more pyrolysis fluidised beds in which hot particles heated in the combustion zone are used for pyrolysis of bio-mass, the combustion zone being operated at or about atmospheric pressure at a temperature of from 400° C. to 1100° C., and the pyrolysis zone being operated at a pressure of from atmospheric to 100 Barg at a temperature of from 400° C. to 900° C.