Hydrodynamics and liquid phase axial mixing in orifice pipe reactor

Abstract

AbstractTwo phase flow in a horizontal pipe, with orifice plates placed at regular intervals as obstructions, was studied for the effect of phase velocities on flow patterns, fractional phase hold‐ups, pressure drop and liquid phase axial dispersion. Radioactive technetium‐99m (as an aqueous solution of sodium pertechnatate) was used as tracer. A pulse injection technique with two point measurements was employed. Three different orifice diameters were used (8 mm, 16 mm, and 20 mm) in a pipe diameter of 32 mm. The orifice spacing was 500 mm in all cases. Superficial gas (air) velocity was varied over a range from 0.02 m/s to 1.0 m/s and superficial liquid (water) velocity from 0.03 m/s to 0.85 m/s.Different flow patterns under different flow conditions were identified and a generalised flow map is presented. Variations in hold‐ups and pressure drop with flow patterns have been explained. Rational correlations have been developed for fractional phase hold‐ups and pressure drop. A preliminary comparison of two phase gas‐liquid flow in a horizontal pipe with orifice obstructions (to be called orifice pipe reactor), as a gas‐liquid contacting device, is made with a conventional bubble column reactor. Recommendations have been made for future work.