Axial mixing of liquid in a turbulent‐bed contactor

Abstract

Abstract The axial dispersion of liquid in a 12‐in. turbulent‐bed contactor has been investigated for three packing sizes: ½‐in., 1‐in. and 1½‐in. The gas and liquid flow rates were varied from 500 to 2700 lb./(hr.)(sq. ft.) and from 1500 to 11,000 lb./(hr.)(sq. ft.) respectively. The transient response technique using KCl solution as the tracer was employed for this purpose. The experimentally determined residence‐time distribution curves were interpreted by means of a one‐dimensional dispersion model. The axial dispersion coefficient, D L , was found to increase with increasing gas flow rate, liquid flow rate, or packing size. In terms of Peclet number ( N Pe = ū d p /D L ), the present data showed that N Pe was dependent on Reynolds number ( N , = d p ū ρ/μ ), Gallileo number ( N Ga = d p 3 ρ 3 g/μ 2 ), and reduced gas mass velocity (Δ = ( G‐G mf )/ G mf ), but the ratio of the Peclet number for a turbulent contactor to the Peclet number for a fixed‐bed contactor, N Pe /N Peo , depended only on Δ, and the diameter ratio d p /d t . A correlation of N Pe /N Peθo with Δ and d p /d t is presented.