Catalyst attrition in fluidized‐bed systems

Werther, Joachim; Reppenhagen, Jens

doi:10.1002/aic.690450916

Cited by 103 publications

(61 citation statements)

References 10 publications

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“…For operating parameters, see Table 1 a bubbling bed 18,19 . Matsen 20 reported that laboratory-and pilot-scale equipment usually show slug-flow behaviour, whereas large fluidized beds are generally not in slug flow.…”

Section: Resultsmentioning

confidence: 99%

99/01439 Comparison of large- and small-scale circulating fluidized bed combustors with respect to pollutant formation and reduction for different fuels

1999

Fuel and Energy Abstracts

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To investigate the scale-up problem of circulating fluidized bed combustors with particular respect to emissions, comparative combustion experiments have been performed in an industrial-size combustor (12 MW th , height 14 m, cross-sectional area 1.6 m ϫ 1.6 m) and in a lab-scale facility (height 16 m, inner diameter 100 mm). A comparison of the axial concentration profiles of oxygen, carbon monoxide, nitric oxide, nitrous oxide and ammonia along the riser height, obtained during the combustion of wood, peat and coal under conditions of equal fuel bed material, solid holdup and gas residence time, shows a basic similarity. This indicates that suitably sized and operated lab-scale combustors may indeed be valuable tools for the investigation of combustion phenomena. However, some significant deviations of the profiles can be recognized, too. These deviations are caused by threedimensional effects in the large-scale combustor and indicate the limitations of small-scale experiments. ᭧ 1998

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Section: Resultsmentioning

confidence: 99%

99/01439 Comparison of large- and small-scale circulating fluidized bed combustors with respect to pollutant formation and reduction for different fuels

1999

Fuel and Energy Abstracts

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“…The reduction of coarse material would only be achieved through correct cyclone operations, but as the gas flow rate is actually decreasing during this stage (Fig 6), cyclone efficiencies should be dropping. The increase in fines would be due to attrition, with the products being lost from the system as they are formed [14,15]. As the FCCU was utilising e-cat during start up, which should be stronger than fresh catalyst, these excessive attrition rates can not be fully explained.…”

Section: Second Stagementioning

confidence: 98%

“…From the literature [14,15], it is commonly accepted that the fine fractions are generated through attrition of larger particles. This theory is supported in the initial sample, as a large amount of coarse material is accompanied by fine material, although there is little of this material in the e-cat.…”

Section: Initial Stagementioning

confidence: 99%

Study of Emission Rates from Fluidized Catalytic Crackers During Start Up Situations

Agranovski¹,

Whitcombe²

2002

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Étude des taux d'émission des unités de crackage catalytique pendant le démarrage -Les unités de crackage catalytique (FCCU) sont utilisées depuis de nombreuses années dans l'industrie de raffinage du pétrole. En conditions normales, il y a peu de soucis concernant l'émission dans l'atmosphère de poussière de catalyseur venant de ces procédés. Cependant, au démarrage de l'unité, les taux d'émission sont couramment plus élevés que la normale. Un échantillon d'une souche a été prélevé sur un FCCU durant le démarrage pour confirmer l'ampleur des émissions de particules. Cet article présente les résultats de l'échantillon d'une souche prélevé durant les 19 premiers jours après le démarrage de l'unité et discute les différents régimes de transmission de particules dans l'air, qui ont lieu durant cette période. Abstract -Study of Emission Rates from Fluidized Catalytic Crackers During Start Up Situations

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“…C j , K b * and C c are particle attrition constants for the jet region, bubbling attrition and cyclone attrition, respectively. The values for these constants were sourced from work by Werther and Reppenhagen [9], since the test material used in the development of their equation, Eq. (1), was also FCC catalyst.…”

Section: Development Of the Modelmentioning

confidence: 99%

“…The original model was expanded to take into account the feedback of collected catalyst from the cyclone into the bed, as well as the addition of an attrition term to more realistically predict emission rates. The attrition terms used in the model were developed by Werther and Rappenhagen [9], Eq. (1):…”

Section: Development Of the Modelmentioning

confidence: 99%

Modeling and Characterization of Air Emissions from Laboratory and Industrial Fluidized Beds

2008

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A fluidized bed model using several elutriation correlations was developed and tested against an operating fluidized bed used in a Fluidized Catalytic Cracker Unit (FCCU) and a 1:8.5 scale laboratory system. It was found that there was little variation between the emission rates predicted using different elutriation correlations, although the newly developed equations were slightly more accurate for the laboratory-scale system. Although total emission rates were predicted with reasonable accuracy, the actual volatility and fluctuations seen in real fluidized beds emissions were not predicted. When the model was used to predict particle emission from the industrial FCCU, they preformed poorly, grossly overestimating the actual levels. It was determined that the attrition terms used in emission modeling were inappropriate and that the model preformed better without them, but still overestimated the actual emissions. This overestimation was greater in the industrial system compared with the smaller laboratory system. It was also found that the older elutriation terms were better for predicting industrial emissions compared with those of the smaller scale units.

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Catalyst attrition in fluidized‐bed systems

Abstract: Catalyst attrition has often been a major obstacle in the de®elopment of new fluidized-bed processes and it is

Cited by 103 publications

References 10 publications

99/01439 Comparison of large- and small-scale circulating fluidized bed combustors with respect to pollutant formation and reduction for different fuels

99/01439 Comparison of large- and small-scale circulating fluidized bed combustors with respect to pollutant formation and reduction for different fuels

Study of Emission Rates from Fluidized Catalytic Crackers During Start Up Situations

Modeling and Characterization of Air Emissions from Laboratory and Industrial Fluidized Beds

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