Dynamic Modeling of Slurry Bubble Column Reactors

Abstract

The multicomponent, one-dimensional, and compartment-based dynamic model developed by Rados et al. (Catal. Today 2003, 79−80, 211−218) has been used to study the performance of slurry bubble columns operated with two chemical reaction systems. One reaction causes contraction in the gas-phase volume, and the other causes expansion. The change in the gas flow rate (expansion or contraction) along the reactor as a result of the chemical reaction kinetics is accounted for by the overall mass balance of the gas phase represented by large and small bubbles. The importance of properly accounting for the change in the gas flow rate has been demonstrated. The backmixing in the three compartments of the model (small bubbles, large bubbles, and slurry) is accounted for by the axial dispersion model. The effects of operating conditions and reactor dimensions on the slurry bubble column performance have been evaluated. A detailed analysis of the role of backmixing on the performance of the Fischer−Tropsch synthesis (contraction of the gas phase) has been conducted by varying the axial dispersion coefficient (E) of the three phases between ideal plug flow (E = 0) and completely mixed flow (E = ∞).

Fischer–Tropsch Synthesis in Slurry Bubble Column Reactors: Experimental Investigations and Modeling – A Review

“…The solid (catalyst) concentration in the reactor is often assumed constant, and in several models, the Sedimentation-Dispersion Model (SDM) is used to estimate the catalyst concentration profile. Also, the syngas consumption is not always considered or is estimated using a linear relationship between the gas consumption and the syngas conversion; and in several models, an overall mass balance on the gas-phase is formulated in order to simulate the effect of syngas consumption [169,195,236,[367][368][369][370][371].…”

“…This latter assumption is inappropriate for simulating small-scale reactors, however, it could be viable for large-scale ones since the liquid-phase backmixing and the dispersion coefficients were reported to increase with reactor diameter [347]. Recent models have introduced the dispersion coefficients in the mass balance equations when using the ADM for the gas and slurry phases [31,192,369]. Rados et al [369] showed that utilizing the ADM to model backmixing in the F-T SBCR is more versatile than the combination of ideal reactor models, such as plug-flow and perfectly-mixed.…”

“…Recent models have introduced the dispersion coefficients in the mass balance equations when using the ADM for the gas and slurry phases [31,192,369]. Rados et al [369] showed that utilizing the ADM to model backmixing in the F-T SBCR is more versatile than the combination of ideal reactor models, such as plug-flow and perfectly-mixed. Nonetheless, for large-scale F-T reactors, considering the gas-phase moves in a plug-flow and the slurry-phase moves as perfectly-mixed appeared to give the closest results to those obtained from the ADM [369].…”

One‐Dimensional Modeling and Simulation of Bubble Column Reactors

“…To enable a description of transient processes with one-dimensional models, Dudukovic et al [20,21] connect a two-class bubble model with the axial dispersion model. Frequently, however, a less detailed model of the bubble column is sufficient, and because of the high level of backmixing, the reactor can be depicted as a stirrer tank [6].…”

Improved Fischer-Tropsch Slurry Reactors

“…The model they developed correlated their data within ±10%. Rados et al [12][13] developed and tested a multicomponent, one dimensional, compartment-based dynamic model to evaluate slurry bubble column reactors with systems consisting of both contraction and expansion in the gas phase during reaction. An axial dispersion component of the model accounts for backmixing of small bubbles, large bubbles, and slurry.…”