Patent ID: 8287697

Claim:
A pyrolysis method in connection with a boiler, comprising: receiving a carrier material from a fluidized bed combustion process in a furnace of the boiler, circulating said carrier material back to the fluidized bed combustion process via a pyrolysis process, mixing said carrier material in the pyrolysis process with solid fuel, forming condensable gaseous substances of said solid fuel by means of heat released by the hot carrier material and by fluidization, separating said gaseous substances from a gas flow coming from the pyrolysis process in liquid form as so-called pyrolysis oil, said method further comprising: allowing the carrier material to flow in the combustion process concurrent with flue gases, separating the carrier material after the combustion process from the flue gases with a separator, feeding the carrier material between the separator and the combustion process by gravity to the pyrolysis process, performing said pyrolysis process in a pyrolyzer chamber which is bordered by the furnace of the circulating fluidized bed boiler in such a manner that the carrier material and the fuel part from the middle of the pyrolyzer chamber into two different material flows towards both ends, and the carrier material, coke and other combustible materials mixed with the carrier material are returned from both ends of the pyrolyzer chamber via return outlets to the furnace, removing the condensable gaseous substances from above the mixture of carrier material and fuel in said pyrolyzer chamber, and forming gas locks between the separator and the combustion process by means of the carrier material that is fed by gravity by feeding the carrier material in a first gas lock before the pyrolyzer chamber through an inlet that is located in a lower position than an outlet succeeding the inlet, and in second gas locks in both ends of the pyrolyzer chamber through inlets that are located in lower positions than said return outlets succeeding the inlets.