Pyrolysis reactor

A non-fluidized bed pyrolysis reactor comprising an upper pressure vessel and a lower reaction chamber;

• wherein the reactor is configured to receive feedstock only prior to initiating pyrolysis such that there is no continuous supply of feedstock in the reactor;
• wherein the upper pressure vessel is configured to contain feedstock that is preheated;
• wherein the lower reaction chamber comprises:
• a gas-permeable distribution screen forming a centrally-disposed plenum and a laterally-disposed gas distribution space;
• and
• at least one process gas inlet in communication with the gas distribution space;
• wherein the plenum is configured to continuously receive the preheated feedstock falling from the upper pressure vessel by gravity;
• wherein the distribution screen is adapted to retain the feedstock within the plenum and the plenum is contiguous with the upper pressure vessel;
• and
• wherein the at least one process gas inlet is configured to:
• introduce, prior to initiation of the pyrolysis, a selected amount of an initial oxygen-containing gas into the lower reaction chamber for combustion of the feedstock, the combustion of the feedstock heating the feedstock to initiate the pyrolysis, the combustion of the feedstock being initiated via a high temperature of the initial oxygen-containing gas, microwave heating in the reactor, or a combination thereof, the combustion and the pyrolysis generating a heating gas;
• and
• introduce, during the pyrolysis, only the heating gas into the lower reaction chamber, wherein the heating gas exits from the upper pressure vessel and is heated prior to entering the at least one process gas inlet to reach a temperature for sustaining the pyrolysis.