A system and method for the pyrolysis of a pyrolysis feedstock utilizes a pyrolysis reactor having a pyrolysis conduit and a solids return conduit segment. Each segment is configured with an outlet and an inlet to receive and discharge solid materials that are circulated through the reactor through the different segments. A solids conveyor is disposed within the pyrolysis conduit segment to facilitate conveying solid materials from the solids inlet upward through the pyrolysis conduit segment toward the solids discharge outlet. A pyrolysis feedstock is introduced into the pyrolysis reactor and at least a portion of the feedstock is converted to pyrolysis gases within the pyrolysis conduit segment, which are discharged through a gas outlet. An eductor condenser unit with an eductor assembly having a venturi-restricted flow path for receives a pressurized coolant fluid. A second flow path for receiving the discharged pyrolysis gases intersects the venturi-restricted flow path so that the received pyrolysis gases are combined with the coolant fluid and are discharged together to a mixing chamber that is used to condense pyrolysis gases.