Char combustion in the freeboard above a fluidized bed burning a high volatile bituminous coal

Walsh, PH; Dutta, Arunava; Béer, J.M.

doi:10.1016/s0082-0784(85)80642-1

Cited by 3 publications

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“…They have outlined that the Donsi et al correlation applies to a variety of coals and carbons (Arena et aI., 1983;Cammarota et al. 1985) with attrition rate constants varying in a relatively narrow range, between 0.8'10-7 and 8.4'10-7 • Other studies (Highley, 1984;Poersch, 1984;Walsh et al. 1984;Daw et al, 1989) have indicated that the attrition rates evaluated on the basis of such correlation must be embodied in the design of BFBC to predict carbon combustion efficiencies and rates of particulate emissions.…”

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confidence: 99%

Carbon Attrition During the Combustion of a Char in a Circulating Fluidized Bed

Arena

Cammarota

Massimilla

et al. 1990

Combustion Science and Technology

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Carbon attrition by abrasion significantly affects combustion efficiency and particulate emis-sions from bubbling fluidized bed combustors as shown by laboratory and pilot scale studies carried out at gas velocities up to 1.5 tnis: i.e. in the range of velocities typical of these units. The paper deals with the results of a work directed to extend gas velocities up to 6 m/s. i.e. to a range of interest to circulating fluidized bed combustors. Experiments have been carried out by means of a laboratory scale circulating fluidized bed combustor,whose riser is 41 mm ID and 6. I m high. Char has been charged to the combustor batchwise. Experimental conditions have been such that attrition by abrasion could be isolated from other comminution phenomena leading to the multiplication of carbon particles in the bed, namely. primary and secondary fragmentation and fragmentation by percolation. Both nitrogen and air have been used as fluidizing agents in order to establish the relative importance of purely mechanical attrition and combustion assisted attrition in generating carbon fines.For given gas velocities and rates of solids circulation in the combustor loop, carbon load and particle size distribution in the riser and carbon attrition rates have been determined as a function of reaction time. As a first approximation, these variables have been correlated according to the rate equation previously found for attrition by abrasion in a bubbling fluidized bed combustor. The comparison between the rate equation constants points out some peculiarities of attrition by abrasion in circulating fluidized bed combustors.

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confidence: 99%