SciELO - Scientific Electronic Library Online

 
vol.110 issue5The effect of feed-coal particle size on the separating characteristics of a gas-solid fluidized bedThe manufacturing of nanoparticles with a plasma process author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Journal of the Southern African Institute of Mining and Metallurgy

On-line version ISSN 2411-9717

J. S. Afr. Inst. Min. Metall. vol.110 n.5 Johannesburg May. 2010

 

TRANSACTION PAPERS

 

Fluidized bed gasification of selected South African coals

 

 

A.D. EngelbrechtI; R.C. EversonII; H.W.P.J. NeomagusII; B.C. NorthIII

ICouncil for Scientific and Industrial Research, Pretoria
IISchool of Chemical and Minerals Engineering, North-West University, Potchefstroom Campus
IIICSIR

 

 


SYNOPSIS

An investigation was undertaken to ascertain the suitability of four selected low grade, South African coals for gasification in a bubbling fluidized bed for production of synthesis gas and for the development of integrated gasification combined cycles (IGCC). This study consisted of the characterization of the coals, laboratory evaluation of intrinsic reactivity, and experimentation with a pilotplant fluidized bed gasifier. Results of the characterization experiments show that the selected coals are high in ash, rich in inertinites, very dense (low porosity), with low caking indices and high ash fusion temperatures. Reactivity measurements with a thermogravimetric analyser (TGA), under reaction rate controlling conditions with carbon dioxide, showed that the reactivity of the coal chars decreases with increase in rank of the coal, as expressed by the vitrinite random reflectance and carbon content of the parent coals. The fixed carbon conversion achieved in the fluidized bed gasifier also correlates well with the rank parameter of the coal, with higher conversions being obtained with the lower rank coals. Thermal shattering and attrition of the coal particles produce significant amounts of fines, which correlate with the grindability indices, and no agglomeration (non-caking) was observed. It is concluded that fluidized bed gasifiers are able to utilize typical low grade, high ash South African coals for synthesis gas production and for inclusion in integrated gasification combined cycles for power generation.


 

 

“Full text available only in PDF format”

 

 

References

1. RUSSELL, N.V., BEELEY, T.J., MAN, C-K., GIBBONS, J.R., and WILLIAMSON, J. Development of TG measurements of intrinsic combustion reactivity for industrial and research purposes. Fuel Processing Technology, vol. 57, 1998, pp. 113-130.         [ Links ]

2. EVERSON, R.C., NEOMAGUS, H.W.J.P. KAITANO, R., FALCON, R., AND DU CANN, V.M. Properties of high ash coal-char particles derive from inertinite-rich coal: II. Gasification kinetics with carbon dioxide. Fuel, vol. 87, 2008, pp. 3403-3408.         [ Links ]

3. EVERSON, R.C., NEOMAGUS, H.W.J.P. KAITANO, R., FALCON, R., AND DU CANN, V.M. Properties of high ash coal-char particles derived from inertinite-rich coal: I. Chemical, structural and petrographic characteristics. Fuel, vol. 87, 2008, pp. 3082-3090.         [ Links ]

4. CLOKELO, M. and LESTER, E. Characterization of coals for combustion using pertographic analysis: a review. Fuel, vol. 73, 1994, pp. 315-320.         [ Links ]

5. ZHANG, L., HUANG, J., FANG, Y., and WANG, Y. Gasification reactivity and kinetics of typical Chinese anthracite chars with steam and CO2, Energy & Fuels, vol. 20, 2006, pp. 1201-1210.         [ Links ]

6. YE, D.P., AGNEW, J.B., and ZHANG, D.K. Gasification of South Australian low-rank coal with carbon dioxide and steam: Kinetics and reactivity studies, Fuel, vol. 77, 1997, pp. 1209-1219.         [ Links ]

7. JING, B., ZHONG, Z., HUANG, Y., and XIAO, R. Air and steam coal partial gasification in an atmospheric fluidized bed, Energy & Fuels, vol. 19, 2005, pp. 1619-1623.         [ Links ]

8. GURURANJAN, V.S. and ARGARWAL, P.K. Mathematical model of fluidized bed coal gasifiers, Chem. Engng Res. De. Trans., vol. 70A, 1992, pp. 211-237.         [ Links ]

9. RHINEHART, R.R., FELDER, R.M., and FERREL, J.K. Coal gasification in a pilotscale fluidized bed reactor. 3. Gasification of Texas lignite. Ind. Eng Chem. Res., vol. 26, 1987, pp. 2048-2057.         [ Links ]

10. ROSS, D.P., YAN, H-M., ZHONG, Z., and ZHANG, D.-K. A non- isothermal model of a bubbling fluidized bed coal gasifier. Fuel, vol. 84, 2005, pp. 1469-1481.         [ Links ]

11. CIESIELCZYK, E. and GAWDZIK, A. Non-isothermal fluidized bed gasifier model for char gasification taking into account bubble growth. Fuel, vol. 73, 1994, pp. 105-111.         [ Links ]

12. GUTIEREZ, L.A. and WATKINSON, A.P. Fluidized bed gasification of some Western Canadian coals. Fuel, vol. 61, 1982, pp. 133-138.         [ Links ]

13. ENGELBRECHT, A.D. Characterization and fluidized bed gasification of selected high-ash South African coals. Master's dissertation. North-West University, Sept. 2008.         [ Links ]

 

 

Paper received Nov. 2008
Revised paper received Nov. 2009

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License