To provide a thermal cracking pipe capable of preventing the excessive high temperature heating of a raw material hydrocarbon gas, preventing the generation of free carbon causing coking, inhibiting the excessive lightening of the thermal crack ing products and polycondensation reactions, and increasing the yield of the ethylene.
This thermal cracking pipe for producing ethylene is used for passing a raw material hydrocarbon gas through the pipe heated from an outer heat source at a high speed and simultaneously heating the hydrocarbon gas in the pipe to thermally crack the hydrocarbon into the ethylene. Therein, its characteristics comprise spirally having projections 12 each having a semi-spherical or semi-oval cross-sectional shape and the same or smaller height as or than 1/10 of the inner diameter of the pipe and having a sharp cross angle of 15-75 degree in a cut and developed flat surface containing the axis of the pipe. The sharp cross angle is formed between the spiral projection and the cut surface of the pipe wall. Thus, a part of the raw material hydrocarbon gas flowing through routes near to the pipe wall is revolved on the back sides of the spiral projections and is simultaneously passed through the pipe, thereby inhibiting the generation of the stagnation of the raw material hydrocarbon gas in the back side regions of the spiral projections.
MAE KENICHI
HAMADA KAORU
Next Patent: RELEASING AGENT FOR CASTING MOLD