| 摘要 |
PURPOSE:To obtain useful olefins such as ethylene, propylene, etc., to suppress coke deposit in pipe and to raise operation efficiency of entire device, by cutting part of rib in the inner face of a thermal cracking pipe to form a rib-free part and circulating a hydrocarbon through the pipe. CONSTITUTION:A metallic pipe 11 having a rib 13 in the inner face is used as a thermal cracking pipe, part of the rib 13 is cut off at a given cutting angle to form a rib-free part 15 and a hydrocarbon is circulated through the thermal cracking pipe. A metallic pipe having 40-60mm outer diameter, 25-45mm thread bottom diameter of rib, 13-35mm thread crest diameter of rib, 3-10mm thickness, 3-10mm rib height, 5-10 number of ribs, 300-500mm rib pitch, 100-350mm length of cut part, 8-30 deg. cutting angle and 4-8mm set interval of cutting part may be cited as the preferable example of the metallic pipe 11.
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