Cracking hydrocarbon materials in presence of steam heated with pipes having helical inner ribs promoting uniform temperature in pipe wall

摘要

In a process to crack crude oil in the presence steam, super-heated gases pass through pipes with helical inner ribs which twist the rising gases, progressively forming a core zone with a primarily axial flow. The helical ribs impart a twist action at their outer margins. The gas speed is faster at the tub roots than at the rib tips. The ribs are set at an angle of 22.5-32.5 degrees w.r.t the pipe axis. The temperature varies within the pipe wall by less than 12degreesC. The notional isothermal lines in the core are circular. The flow of twisting gases advances in the pipe at a speed of 1.8-2 m/s, representing 7-8% of the free cross sectional area. The ribs and their separation are symmetrical.