Bubble assemblage model

A frequently used phenomenological description of the two-phase flow phenomena in fluidized bed reactors is based on the bubble assemblage model, originally proposed by Kato and Wen. " ... 

Kato, K., Wen, C. Y. (1969). Bubble assemblage model for fluidized bed catalytic reactors. Chemical Engineering Science, 24, 1351 — 1369. 

Bubble Assemblage Model Bubble Size Growth... 

In the following subsections, the general two-phase models are briefly reviewed, and then we give a more detailed description of two of the more popular two-phase models, namely the bubbling bed model proposed by Kunii and Levenspiel (1969) and the bubble assemblage model proposed by Kato and Wen (1969). 

Calculation Procedure Based on Bubble Assemblage Model... 

Figure 3 Main features of bubble assemblage model. (From Kato and Wen, 1969.)... 

The computation using the bubble assemblage model indicates that for most of the experimental conditions... 

The Kato and Wen (1969) bubble assemblage model, though better suited to represent complex hydrodynamics due to allowance for variable bubble properties, fails to account for observed end eflects in the reactor. While this model was found to give the best fit for the bubble phase profile, dense phase profiles and outlet reactant concentrations were seriously overpredicted. 

Mori S, Wen CY. Simulation of fluidized bed reactor performance by modified bubble assemblage model. In Keairns DL, ed. Fluidization Technology, Vol 1. Washington DC Hemisphere, 1976, pp 179-203. 

Model discrimination was done comparing simulated and 41 experimental data sets. The measure of model accuracy was defined as the sum of squares of relative errors of prediction for Sc2+ and XcH4- The bubble assemblage model assuming plug flow (PF) in the horizontally distributor zone (BAM+PF) was best (for details see [49]). A comparison between results of simulations obtained with the BAM + PF model and experimental data is shown in Figures 25 and 26. C2+ selectivity is very well predicted the conversion of methane is also predicted quite well, however, a tendency to underestimate the conversion was observed. The standard deviations for the prediction of Sc2+ and Xch4 amount to 7 and 8 % respectively. It should be emphasized that the simulations were done without any tuned parameters. 

Horio et al. (102) developed a general mathematical model for the FBC, employing the modified version of the bubble assemblage model (103 10 ). Predictions of combustion efficiency, axial temperature profile and sialfur retention efficiency in the bed were compared with experimental data obtained from the National Coal Board and Exxon Miniplant. Fig. 12 presents typical profiles of carbon concentration and temperature in the bed. Fig. 13 indicates the SO2 retention by limestone additives as a fumction of bed temperatTjre. 

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