Combustion of coal-char

Modeling of Fluidized Bed Combustion of Coal Char Containing Sulfur... 

Rehmat, A. Saxena, S. C. Land, R. H. Application of Non-catalytic Gas-Solid Reactoins for a Single Pellet of Changing Size to the Modeling of Fluidized-Bed Combustion of Coal Char Containing Sulfur Argonne National Laboratory Report, ANL/ CEN/FE-80-13, September 1980, 86 pp. 

A quantitative understanding of the process of coal combustion in a turbulent fluidized bed is essential for optimum use of this process. Elaborate research work by Basu and Subbarao [1] and Haider et al [2] describe the process of combustion of coal char in turbulent fluidized beds. 

Properties. The properties of char products from two possible coal feeds, a low sulfur Western coal, and a high sulfur Midwestern coal, are shown in Table 11. The char derived from the low sulfur Western coal may be direcdy suitable as plant fuel, with only minor addition of clean process gas to stabilize its combustion. Elue gas desulfurization may not be required. Elue gas from the combustion of the char derived from the high sulfur Illinois coal, however, requires desulfurization before it may be discharged into the atmosphere. 

The high temperatures of coal char oxidation lead to a partial vaporization of the mineral or ash inclusions. Compounds of the alkali metals, the alkaline earth metals, silicon, and iron are volatilized during char combustion. The volatilization of silicon, magnesium, calcium, and iron can be greatly enhanced by reduction of their refractory oxides to more volatile forms (e.g., metal suboxides or elemental metals) in the locally reducing environment of the coal particle. The volatilized suboxides and elemental metals are then reoxidized in the boundary layer around the burning particle, where they subsequently nucleate to form a submicron aerosol. 

Laurendeau N.M., Heterogeneous Kinetics of Coal Char Gasification and Combustion , Prog. Energy Combust. Sci. 4, 221-270(1978). 

Solum, M.S., Pugmire, R.J., Grant, D.M., Fletcher, T.H., and Solomon, P.R., Solid State C NMR Studies of Coal Char Structure Evolution. Western States Section/The Combustion Institute, Pullman, WA (3/89). 

To study and examine the effects of oxidation at 373 K and weathering upon the subsequent combustion of the char using an Entrained Flow Reactor at 1273 K and possible relationships between the structure of the parent coal and the characteristics of the associated char. 

Biagini, E., Tognotti, L., Malloggi, S. Pasini, S. 2002. Co-combustion of coal and tire residue in a pilot plant a simplified modelling approach for scale-up predictions of char oxidation. Combustion Science and Technology, 174, 129-150. 

Fu. W. B., and Zhang, B. L. A simple and general method for calculating the burning rate of coal char/carbon particle in air, Proceedings of 2nd International Symposium on Coal Combustion Science and Technology, China Machine Press, Beijing (1991). 

Fletcher, T.H. Swelling properties of coal chars during rapid pyrolysis and combustion. Fuel, 1993, 72, 1485. 

Influence of Mineral Matter on the Rate of Coal Char Combustion... 

Other uncertainties account for less than a factor of four in the estimated intrinsic rate of coal char combustion. 

This paper assesses one of the major uncertainties in estimating intrinsic rate constants, the influence of catalysis of the combustion rate of coal char. 

Pohl, J. H. Richter, R. W. Heap, M. P. Folsom, B. A., "Influence of Coal Char Combustion Rate on Power Plant Performance, Special Report Prepared Under EPRI Contract EPRI RP 2256-1, 1983. 

Combustion of coal particles included volatile evolution and char combustion to simulate pulverized coal combustion. 

The liquid products are filtered to remove particulate matter and then hydrotreated (370°C-425°C [700°F-800°F] 1750-2500 psi hydrogen) to produce a synthetic crude oil (Table 19.1) from whieh the majority (90%) of the nitrogen, oxygen, and sulfur have been removed. As already noted for the Lurgi-Ruhrgas process, the majority of the sulfur originally in the coal occurs in the char and, therefore, combustion of the char may be an environmental problem unless there is some effort made to install stack gas cleaning equipment. 

Garijo EG, Jensen AD, Glarborg P. Reactivity of coal char in reducing NO. Combust Flame 2004 136(l) 2249-53. 

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