| abstract |
Apparatus and method for initiating pyrolysis of a feedstock by establishing a continuous, standing shock wave. Several embodiments of a shock wave reactor (10, 100, 150) are disclosed; each is connected to receive an ethane feedstock and a carrier fluid comprising superheated steam. The feedstock and the carrier fluid are pressurized so that they expand into parallel supersonic streams that mix due to turbulence within a mixing section (36) of a longitudinally extending channel (12) of the shock wave reactor. The carrier fluid heats the ethane feedstock as it mixes with it, producing a mixture that flows at supersonic velocity longitudinally down the channel. A gate valve (44) disposed downstream of the channel provides a controlled back pressure that affects the position of the shock wave and the residence time for the reaction. The shock wave rapidly heats the mixture above a pyrolysis temperature, producing a desired product by cracking the feedstock. Rapid heating of the mixture enables a residence time in the pyrolysis section of only 5 to 50 milliseconds. By varying the position of the shock wave, the residence time is controlled as required to obtain maximum yield from different feedstocks. Downstream of the pyrolysis section, the mixture is quenched, cooling and terminating the pyrolysis reaction. The relatively short residence time and the control of its duration with a resolution in the microsecond range are substantial advantages of the shock wave reactor. |