Reactor runaway due to statistically driven axial activity variations in graded catalyst beds: Loading from pre-measured single tube aliquots

Calverley, Edward M.; Witt, Paul M.; Sweeney, Jeff

doi:10.1016/j.ces.2012.12.017

Cited by 10 publications

(3 citation statements)

References 15 publications

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“…In this context, the tube diameter for exothermic reactions is generally between two and 5 cm [5], and the tube-to-particle diameter is about eight depending on the application [1]. Smaller particles tend to decrease the bed's radial thermal conductivity, causing an excessive pressure drop; however, larger particles cause high intraparticle mass transfer resistances, reducing the heat removal from the catalyst to the fluid.…”

Section: Introductionmentioning

confidence: 99%

Thermochemical Analysis of a Packed-Bed Reactor Using Finite Elements with FlexPDE and COMSOL Multiphysics

et al. 2022

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This work presents the thermochemical analysis of a packed-bed reactor via multi-dimensional CFD modeling using FlexPDE and COMSOL Multiphysics. The temperature, concentration, and reaction rate profiles for methane production following the Fischer–Tropsch (F-T) synthesis were studied. To this end, stationary and dynamic differential equations for mass and heat transfer were solved via the finite element technique. The transport equations for 1-D and 2-D models using FlexPDE consider dispersion models, where the fluid and the catalyst can be treated as either homogeneous or heterogenous systems depending on the gradient extents. On the other hand, the 3-D model obtained in COMSOL deems the transport equations incorporated in the Porous Media module. The aim was to compare the FlexPDE and COMSOL models, and to validate them with experimental data from literature. As a result, all models were in good agreement with experimental data, especially for the 2-D and 3-D dynamic models. In terms of kinetics, the predicted reaction rate profiles from the COMSOL model and the 2-D dynamic model followed the temperature trend, thus reflecting the temperature dependence of the reaction. Based on these findings, it was demonstrated that applying different approaches for the CFD modeling of F-T processes conducts reliable results.

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Section: Introductionmentioning

confidence: 99%

Thermochemical Analysis of a Packed-Bed Reactor Using Finite Elements with FlexPDE and COMSOL Multiphysics

et al. 2022

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“…In the published literature on coal tar hydrogenation, catalysts are usually used alone. ,,− However, this is rarely the case in industrial production. − The most common method is to load various catalysts by stages, but there are few reports on it. Coal tar hydrogenation technology has been realized industrially, and the research results are best to provide a reliable basis for industrial design or technical improvement directly.…”

Section: Introductionmentioning

confidence: 99%

Hydrofining Process of Coal Tar Based on Four Kinds of Catalyst Grading

Niu

Fan

et al. 2020

Energy Fuels

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Although the mechanism of coal tar hydrogenation technology has not been fully revealed, many enterprises have realized the industrialization of this technology through the reference of crude oil hydrogenation technology. Therefore, it will be very helpful for the development of this technology to present a research result close to industry. Based on four kinds of catalyst gradations, the hydrogenation experiments of different processes and a series of 1200 h long-term experiments were carried out in a four-tube fixed bed reactor with coal tar distillate (IBP ≈ 360 °C) as the raw material. First, based on the product composition of different reactor outlets, the composition changes and main reaction process of coal tar in four reactors were summarized. It was found that the reactions in the four reactions are different and related. The hydrogenation of olefins mainly takes place in the first reaction (230 °C, hydrofining guard catalyst and hydrodemetallization catalyst). Most of the oxygenated compounds were transformed in the second reactor (320 °C, hydrogenation catalyst I) but not completely. The hydrogenation of aromatics is mainly concentrated in the third and fourth reactors, but there are already signs of this reaction in the second reactor. Second, the influence of different process conditions on the product properties and the material balance under different process conditions were summarized. Finally, the stability of the grading system is verified by the long-term experiments.

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“…) , the wall heat transfer (ℎ ) and the pressure drop (ΔP) are keys for the design of catalytic reactors (Eisfeld and Schnitzlein, 2001;Bhattacharyya and Pei, 1975;Bey and Eigenberger, 2001). These parameters depend on the composition, size, shape of the particles, the bed porosity, experimental conditions, etc… (Dixon et al, 2008;Smirnov et al, 2004;Chueh et al, 2014) In the case of an exothermic reaction, temperature gradients and hot spots are established in the fixed bed (Zhu et al, 2014;Calverley et al, 2013;Philippe et al, 2009). Beyond the runaway risks, the poor control of the bed temperature induces thermal deactivation, sintering phenomena, and decreases the production yield (Bartholomew, 2001;Forzatti and Lietti, 1999).…”

Section: Introductionmentioning

confidence: 99%