Method and reactor for pyrolysis conversion of hydrocarbon gases

A method of converting light alkanes to pyrolysis products, the method comprising:

• providing a pyrolysis reactor comprising:
• a pyrolysis reactor vessel having a reactor wall that defines a pyrolysis reaction chamber;
• a burner assembly having a burner conduit with a circumferential wall that surrounds a central longitudinal axis and extends from opposite upstream and downstream ends of the burner conduit, the circumferential wall having an annular constricted neck portion located between the downstream and upstream ends of the burner conduit, the downstream end of the burner conduit being in fluid communication with the reaction chamber of the pyrolysis reactor, the upstream end of the burner conduit forming a burner assembly inlet;
• and
• a pyrolysis feed assembly having an annular alkane gas flow space and an annular oxygen gas flow space that discharge into a central mixing chamber that is in fluid communication with the burner assembly inlet;
• introducing an alkane-containing gas feed stream of a pyrolysis feed into the annular alkane gas flow space and an oxygen-containing gas feed stream of the pyrolysis feed into the annular oxygen gas flow space so that the alkane-containing gas feed stream and the oxygen-containing gas feed stream pass through said flow spaces perpendicularly to the central longitudinal axis of the burner conduit in an inwardly spiraling fluid flow pattern within said flow spaces that flows about the central longitudinal axis of the burner conduit, with the oxygen-containing gas feed stream from the oxygen gas flow space and alkane-containing gas feed stream from the alkane gas flow space being discharged into the mixing chamber so that the alkane-containing gas and oxygen-containing gas feed streams are mixed together and form a swirling gas mixture within the mixing chamber;
• allowing the swirling gas mixture to pass through the burner conduit, with at least a portion of the swirling gas mixture forming a thin, annular mixed gas flow layer immediately adjacent to the burner conduit, and wherein a portion of the swirling gas mixture is combusted as the swirling gas mixture passes through the burner conduit to provide conditions suitable for pyrolysis of the alkane gas from the alkane-containing gas feed stream within the pyrolysis reaction chamber of the reactor vessel, with a portion of the alkane gas being converted to pyrolysis products within the pyrolysis reaction chamber;
• and
• removing pyrolysis products from the reaction chamber of the reactor vessel;
• and
• wherein gas flow through the pyrolysis reactor is at subsonic flow velocities.