Coal devolatilization in fluidized-bed combustors

LaNauze, R.D.

doi:10.1016/0016-2361(82)90255-1

Cited by 43 publications

(14 citation statements)

References 8 publications

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“…Therefore, it is important to understand where and how the volatiles are released from the coal. The importance of volatile matter in the fluidized bed combustion of coals has been discussed by La Nauze [60]. Stubington et al [17] noted that the combustion of volatiles in a fluidized bed combustor influences the design and operation via several ways.…”

Section: Implications Of Devolatilization In Fluidized Bed Pyrolysismentioning

confidence: 98%

“…The approach of LaNauze [60] is similar to that of Essenhigh [78], except in the treatment of the diffusion process. Gavalas [38] has studied the effect of mass transfer limitation on the pyrolysis of coal.…”

Section: Modeling Of Mass Transfermentioning

confidence: 99%

“…Because the bed offers resistance to flow, the drag force, as given by the pressure drop across the bed, is sufficient to support the weight of the bed. The bed has a pseudo-density and has many attributes of a liquid [60]. In combustion applications, fuel is continuously fed to the fluidized bed consisting of noncombustible particles.…”

Section: Implications Of Devolatilization In Fluidized Bed Pyrolysismentioning

confidence: 99%

“…La Nauze [60] has proposed a model for devolatilization assuming internal mass transfer as the ratecontrolling step. The total time for volatile evolution was shown to follow the equation,…”

Section: Modeling Of Mass Transfermentioning

confidence: 99%

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A review on devolatilization of coal in fluidized bed

Borah

Ghosh

Rao

2011

Int. J. Energy Res.

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SUMMARYDevolatilization is an important step in fluidized bed combustion and gasification of coal. 'Devolatilization' is a general term that signifies the removal of volatile matters from the coal matrix. It is an extremely important step because the combustion of volatile matter can account for 50% of the specific energy of fluidized bed combustion of a high-volatile coal. Significant insights into the complex physicochemical phenomena that occur during devolatilization have been obtained in the recent years. This review focuses on the devolatilization of coal in an inert gas, air, and oxygen-enriched air, with emphasis on the effects of the operating parameters (e.g. temperature, heating rate, pressure, and gas velocity) on the yield of volatile matter. Particle size, oxygen content of the fluidizing gas, volatile content of coal and specific heat are some of the other important parameters for the devolatilization of coal. This review also explains the development and application of structural and empirical models. The structural models (e.g. FG-DVC and CPD models) are fairly complex. However, they can accurately predict the yields of gas and tar. It is observed from the review of the literature that the mechanism of coal devolatilization needs further study. Although the shrinking-core model can describe the devolatilization in the beginning and toward the end of the process, major deviations are often observed. The economic studies reveal that the capital cost of fluidized bed combustion reduces upon doubling the capacity. Some problems associated with bubbling fluidized bed combustion (e.g. the increase in freeboard temperature) have been explained with the present knowledge of devolatilization.

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Section: Implications Of Devolatilization In Fluidized Bed Pyrolysismentioning

confidence: 98%

Section: Modeling Of Mass Transfermentioning

confidence: 99%

Section: Implications Of Devolatilization In Fluidized Bed Pyrolysismentioning

confidence: 99%

Section: Modeling Of Mass Transfermentioning

confidence: 99%

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A review on devolatilization of coal in fluidized bed

Borah

Ghosh

Rao

2011

Int. J. Energy Res.

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“…Knowledge of devolatilization and volatiles combustion rates as well as the location where the combustion takes place is, therefore, very important for the design and operation of the combustor. Experimental and theoretical studies on the devolatilization and combustion of coal volatiles in fluidized beds (FB) have been reported elsewhere (Atimtay, 1980;Stubington and Davidson, 1981;Pillai, 1981; La Nauze, 1982;Agarwal et al, 1984Agarwal et al, , 1987Prins et al, 1989). Recent studies on spouted bed (SB) and spout-fluid bed (SFB) combustion have been focused on char combustion (Zhao et al, 19876) and combustion efficiency (Lim et al, 1988), but the devolatilization and volatile combustion have received less attention.…”

Section: Introductionmentioning

confidence: 99%

Spouted and spout-fluid bed combustors 1: Devolatilization and combustion of coal volatiles

Tia

Bhattacharya

Wibulswas

1991

Int. J. Energy Res.

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The devolatilization and volatile combustion of a single coal particle in spouted and spout‐fluid beds have been studied. The results showed that the flame extinction time increases with the particle diameter, and decreases with the bed temperature. When the bed temperature and the air flow rate were fixed, the operation modes (spouted or spout‐fluid bed) showed less effect on the mean flame extinction time. A mathematical model of the spouted bed mode for preignition and postignition periods has also been developed assuming the devolatilization rate to be controlled by heat transfer and multireaction pyrolysis kinetics based on volatile products. Ignition, heat transfer back from the volatile flame to the particle surface, variation in flame temperature, and the hydrodynamics of SB are taken into account. The model predictions, with some adjusting parameters, were in good agreement with experimental results.

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Coal Combustion

Kosowska-Golachowska

2010

Handbook of Combustion

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This chapter provides an overview of coal combustion of a single coal particle. First, it outlines heating and drying, ignition of volatiles, devolatilization, char combustion and fragmentation of coal particle. The results of experimental research of combustion and fragmentation of two brown coals (lignites), seven hard coals mined in Poland and Russian anthracite are then presented. The combustion and fragmentation behavior of these coals was tested in an externally‐heated bench‐scale bubbling fluidized‐bed unit. Next, the mathematical model of primary fragmentation, including coal heating and volatile release is outlined. Finally, applications of coal combustion in industry and key clean coal technologies of the future are discussed.

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Coal devolatilization in fluidized-bed combustors

Cited by 43 publications

References 8 publications

A review on devolatilization of coal in fluidized bed

A review on devolatilization of coal in fluidized bed

Spouted and spout-fluid bed combustors 1: Devolatilization and combustion of coal volatiles

Coal Combustion

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