Liquid Holdup in Catalyst‐Containing Pockets of a Modular Catalytic Structured Packing

Abstract

This paper introduces a simple, first principles-based model describing the liquid holdup in the catalyst-containing pockets of Katapak-SP, a modular catalytic structured packing developed to allow a certain degree of flexibility with respect to the variation in reaction-to-separation requirements in a single unit. The basic requirement for the catalyst-containing pockets in this respect is to be fully filled with flowing liquid which implies that the operating holdup is bound between the static holdup of the catalyst bed as the lower end, and that corresponding to the upper limit, the so-called catalytic load point. The latter is the liquid load corresponding to the bed saturation point, indicating that excessive liquid will be retained, i.e., will remain in the separation part of the packing element and mix with the liquid leaving the catalyst-filled pockets at the bottom of the element. Detailed knowledge of the liquid holdup as well as the pattern of the trickling flow is essential because it governs the performance of the reaction part and consequently the hybrid unit as a whole. Both glass and resin (an industrial catalyst) particles were used in conjunction with water and a binary water-methanol mixture as working fluids. The model predictions for static holdup and the catalytic load agree well with the experiments.

Determination of liquid hold-up and flow distribution inside modular catalytic structured packings

“…Liquid hold-up correlations proposed for corrugated structured packings and single-phase trickle beds have been adapted to the Katapak-SP geometry and used to relate the measured liquid hold-up with the liquid flowrates outside and inside the catalytic baskets, respectively. Similarly to previous studies on catalytic packings (Moritz and Hasse, 1999;Hoffmann et al, 2004;Ratheesh and Kannan, 2004;Behrens et al, 2006Behrens et al, , 2008, the present analysis has been differently approached for high and low liquid loads. The starting point of the analysis is to write the total liquid flowrate as the sum of two contributions:…”

“…It is also worth to note that in the used Reynolds interval, the friction factors calculated by Eq. (5) differ less than 1% from the values calculated by using the relation recently proposed by Behrens et al (2008). Once u CB max is known, the liquid flowrate flowing on the corrugated sheets can be determined by means of the material balance expressed by Eq.…”

“…The static hold-up contribution can be mainly attributed to the catalytic baskets. The drainage of single catalytic baskets taken from dismantled packings has been investigated (Viva and Brunazzi, 2007;Behrens et al, 2007Behrens et al, , 2008. These studies are complementary to the measurements of the static hold-up on packing elements of Katapak-SP 11 and Katapak-SP 12 (Viva and Brunazzi, 2007;Aferka et al, 2007).…”

Experiments and dynamic modeling of a reactive distillation column for the production of ethyl acetate by considering the heterogeneous catalyst pilot complexities

“…The performance of the KATAPAK-SP depends however on many parameters; the most important are dynamic liquid hold-up, pressure drop, residence time behavior, liquid physical properties and catalytic load point. Behrens et al (2008) experimentally determined the static and dynamic liquid holdup characteristics of the catalyst-filled pockets as encountered in KATAPAK-SP. The authors explained that the value for dynamic liquid holdup was between those for the static liquid holdup and for the catalytic load point.…”

Hydraulic performance of Winpak‐C modular catalytic structured packing

“…A hydrodynamic model that describes the counter‐current gas‐liquid flow for the entire gas loading range and considers the influence of the column diameter was implemented in a rate‐based column model. Behrens et al investigated the hydrodynamics of two types of the catalytic packing Katapak‐SP as well as the segmentation of its catalyst‐containing pockets. The geometry‐based Delft MCSP model, a parallel column model, was shown to be able to predict the performance of MCSP.…”