Effect of partial wetting on liquid/solid mass transfer in trickle bed reactors

Abstract

The wetting efficiency of liquid trickle flow over a fixed bed reactor has been measured for a wide range of parameters including operating conditions, bed structure and physico-chemistry of liquid/solid phases. This data bank has been used to develop a new correlation for averaged wetting efficiency based on five different non-dimensional numbers. Finally liquid/solid mass transfer has been determined in partial wetting conditions to analyse what are the respective effects of wetting and liquid/gas flow turbulence. These effects appear to be separated: wetting being acting on liquid/solid interfacial area while the liquid/solid mass transfer coefficient is mainly connected to flow turbulence through the interstitial liquid velocity. A correlation has been proposed for liquid/solid mass transfer coefficient at very low liquid flow rate.

Measurements and Modeling of Wetting Efficiency in Trickle-Bed Reactors: Liquid Viscosity and Bed Packing Effects

“…Existing Correlations. Several correlations have been proposed in the past to calculate the global wetting efficiency in TBR, 3,4,[16][17][18][19][20] but they give very dispersed results over the same range of operating conditions. Those discrepancies can be explained by the various measuring techniques, whose precision was not fully examined, and also by the operating conditions, especially the bed prewetting procedure as pointed out by van Houwelingen et al 10 Recently Lappalainen et al 21 have evaluated different models based on dimensional similitude and optimized their parameters using about 250 experimental points from literature, distinguishing the prewetting procedure and reconciliating some of the data.…”

Liquid holdup and wetting efficiency in a rotating trickle‐bed reactor

“…The correlation has been established within the following validation domain: 0.23 ≤ Re L ≤ 22.43, 0.00 ≤ Re G ≤ 45.38, 6.18 × 10 4 ≤ Ga ≤ 5.28 × 10, and 1.57 × 10 −11 ≤ Ka ≤ 1.69 × 10 −5 . The exponents of Re L and Re G were lower than those in correlations of TBRs . The reason is that the RTBR possesses significant capability to wet the packing, and its wetting efficiency varies little even within wide ranges of operating parameters.…”

Axial Variation of Wetting Efficiency and Liquid–Solid Mass Transfer in Long Trickle Bed Columns

“…The prediction of the actual mass transfer coefficient at the solid surface in contact with the liquid subsequently requires the use of models for the 2 quantification of the wetting efficiency (ϕ) of the solid. These models predict a wide range of wetting efficiencies for the same operating conditions and it is very difficult to choose the most accurate one for a specific system 3 . This observation, in addition to the fact that the dependence of k ls and wetting efficiency on the hydrodynamic and physico-chemical parameters in the column may not necessarily be the same, makes this approach undesirable and an overall volumetric LSMT is often rather reported.…”