Lateral mixing in trickle bed reactors

Abstract

Knowledge of lateral mixing is essential to understand heat and momentum transfer parameters in both single-phase liquid and two-phase gas-liquid co-current down flow through packed bed columns. The reactors through which gas and liquid concurrently flow downwards through a bed of catalytic packing are called trickle bed reactors. Experimental data on lateral mixing coefficients from both the heat transfer and radial liquid distribution studies are obtained over a wide range of flow rates of gas (0.01.0.898 kg/m 2 s) and liquid (3.16.71.05 kg/m 2 s) using glass spheres (4.05 and 6.75 mm), ceramic spheres (2.59 mm), and ceramic raschig rings (4 and 6.75 mm) as packing materials covering trickle flow, pulse flow, and dispersed bubble flow regimes. In the present work, an expression for estimation of lateral mixing coefficient ( ) L is derived using the data on radial liquid distribution studies. The agreement between the values of ( ) L obtained from heat transfer studies and from radial liquid distribution studies using the experimental data shows that there exists an analogy between the heat transfer and radial liquid distribution in packed beds. Since ( ) L is an important variable for estimation of various heat and mass transfer parameters, a correlation for ( ) L based on present heat transfer study is proposed. The agreement between the ( ) L values estimated from the proposed correlation and experimental values is satisfactory with a standard deviation (s.d.) of 0.119.

Influence of Gas Flow Rate on Liquid Distribution in Trickle-Beds Using Perforated Plates as Liquid Distributors

“…Those factors have been widely studied by numerous authors (e.g., see refs [1][2][3][4][5][6][7][8][9][10]. Many of their studies however, dealt mostly with small-sized columns and/or were performed using liquid collectors; so, in a very recent investigation, Babu et al 10 used a column with 50 mm i.d.. Note that these authors compared collector data with radial spreading data issued from a radial heat-transfer model.…”

“…Among the factors affecting liquid distribution in trickle beds one will find the initial liquid distribution (ensured by the use of a proper distributor), the packing and fluid characteristics, the prewetting conditions, and the flow rates. Those factors have been widely studied by numerous authors (e.g., see refs – ). Many of their studies however, dealt mostly with small-sized columns and/or were performed using liquid collectors; so, in a very recent investigation, Babu et al used a column with 50 mm i.d..…”

“…Those factors have been widely studied by numerous authors (e.g., see refs – ). Many of their studies however, dealt mostly with small-sized columns and/or were performed using liquid collectors; so, in a very recent investigation, Babu et al used a column with 50 mm i.d.. Note that these authors compared collector data with radial spreading data issued from a radial heat-transfer model.…”