Experimental Evaluation of Distributor Technologies for Trickle-Bed Reactors

Abstract

In this paper, different technologies of distributors for trickle bed reactors were compared, in terms of intrinsic performance of distribution and resistance to tray unlevelness. γ-ray tomography has first been used, in a large column unit, to visualize gas–liquid distribution just below several tray technologies. Results obtained show a better distribution performance under multiaperture chimney trays, in comparison with gas-lift and bubble cap systems. Then, a specific cold mock-up was designed in order to mimic tray tilt between two tray elements. Sensitivities to tray unlevelness of both gas-lift and multiaperture systems are comparable, far better than the one for the bubble cap system. Multiaperture chimneys have indeed excellent behavior at nominal conditions, while gas-lift technology is interesting for its ability to behave similarly over a large flow range. Considering those results, some guidelines are finally given for the choice of the distribution technology.

Use of Computational Fluid Dynamics for Absorption Packed Column Design

“…In some high-performance designs corresponding to operation with a high turndown ratio, the distributors can be enhanced by using perforated drip tubes with orifices at different levels on the tubes. Such a solution must be carefully engineered to ensure a good distribution quality (Bazer-Bachi et al, 2013). For this case, the design rules have to take into account several parameters, such as the liquid height at nominal and turndown flow conditions, the distance between the gas-liquid interface and the drip tube orifice(s), the number and the area of orifices, the friction coefficient at the orifice, the resistance to the tray unlevelness, etc.…”

CFD Applied to Process Development in the Oil and Gas Industry – A Review

“…However, in the industrial reactors of several meters in diameter, trays are often not perfectly levelled (Maiti and Nigam, 2007;Alvarez et al, 2007;Bazer-Bachi et al, 2013) because of their weight or because of column deviation from verticality. In this case, the horizontality default of the distributor tray becomes an important factor that must be carefully considered.…”

“…Many distributors consist of a large number of chimneys or tubes through which vapour and liquid phases flow to further contact the catalyst below the distributor (Maiti and Nigam, 2007;Bazer-Bachi et al, 2013). For a long period of time, distributors were developed with no special attention to the vapour phase, considering that the main issue was to distribute the liquid phase.…”

Applications of tomography in bubble column and trickle bed reactors

“…Thus, the application of MRI to reactors with metallic internals has been challenging. X-ray and g-ray CT are potentially advantageous in this regard (Bazer-Bachi, Haroun, Augier, & Boyer, 2013;Bieberle et al, 2013;Boyer & Fanget, 2002;Schubert et al, 2011). CT techniques have also been used in an analogous manner to the MRI techniques discussed above to characterize the distribution of gas and liquid in structured packing materials such as Katapak-SP 12 (Aferka, Crine, Saroha, Toye, & Marchot, 2007) and Mellapak 752Y (Roy et al, 2005).…”

“…CT techniques have also been used to explore the distribution of liquid at the entrance of packed bed columns and catalytic beds (see e.g. Bazer-Bachi et al, 2013;Fourati, Roig, & Raynal, 2012;Kalaga et al, 2009;Merwe, Nicol, & Beer, 2007;Roy et al, 2005 and references therein). For example, Figure 18.8 illustrates the distribution of liquid in a trickle bed reactor of diameter 0.6 m with two types of distributors: a chimney tray with deflectors and a gas-lift distributor.…”