An Assessment of Coal-Ash Slagging Propensity Using an Entrained Flow Reactor
This paper describes the design and operation of an entrained flow reactor to assess the slagging propensity of a coal-ash. Temperatures and residence times have been chosen to closely simulate those experienced by pulverised fuel (pf) particles in a full-size utility boiler. Ash deposits have been collected on ceramic coupons at 1500°C and 1200°C and on an air-cooled metal probe at 830°C.
Ten UK coals and one US coal were selected to give a wide range of coal-ash compositions, a range similar to that found at many power stations. Deposits ranged from dense, highly fused material collected at 1500°C, to lightly sintered ash-particles collected at 830°C. A visual inspection of the deposits allowed a provisional ranking of the slagging propensity to be made. A computer-controlled scanning electron microscope (CCSEM) technique has been developed to provide a quantitative characterisation of each microstructure, thus providing the basis for a more rigorous assessment of the slagging propensity.
The technique described provides the basis for a reliable assessment of coal-ash slagging propensity to be made from a few kgs of coal. It removes many of the uncertainties associated with conventional indices and the previous subjectively based laboratory techniques.
KeywordsMild Steel Particle Residence Time Coal Research Deposition Probe Back Scatter Image
Unable to display preview. Download preview PDF.
- Couch, G. (1994) `Understanding Slagging and Fouling in pf Combustion“, IEA Coal Research, London, IEACR/72.Google Scholar
- Gibb, W.H., Jones, A.R. and Wigley, F. (1994). “The UK Collaborative Research Programme on Slagging in Pulverised Coal-Fired Furnaces: Results of Full-Scale Plant Trials”, in I’roccec/iN.,,s of the 1993 Engineering Foundation Conference on The Impact of Ash Deposition in Coal-lires! Plants, Williamson, J. and Wigley, F., (Eds), Taylor and Francis, Washington, pp 3–18.Google Scholar
- Gibb, W.H. (1995). “The UK Collaborative Research Programme on Slagging in Pulverised Coal-Fired Boilers: Summary of Findings”, This Conference.Google Scholar
- Jones, A.R. and Riley, G.S. (1987). “Deposition Characterisation ofa CEGB 660MWe Coal-Fired Boiler”, EP11 Conference ou the Effects of Coal Ouality on Power Plant, Atlanta, Georgia.Google Scholar
- Wain, S.E., Livingston, W.R., Sanyal, A. and Williamson, J. (1991) “Thermal and Mechanical Properties of Boiler Slags of Relevance to Sootblowing”, in Proceedings of the 1990 Engineering Foundation Conference on inorganic fransforrnations and Ash Deposition during (’onrbustion, Benson, S.A.(ed), Engineering Foundation, New York, pp 459–470.Google Scholar
- West, S.S., Williamson, J. and Laughlin, M.K. (1994). “Mineral Interactions During Fluidised Bed Gasiticiation of Coals”, in Proceedings of the 1993 Engineering Foundation (’ori/erence on The Impact of Ash Deposition in Coal-Fired Plants, Williamson, J. and Wigley, F., (Eds),Taylor and Francis, Washington, pp 89–100.Google Scholar
- Wigley, F. and Williamson, J. (1994). “The Characterisation of Fly-Ash Samples and their Relationship to the Coals and Deposits from UK Boiler Trials”, in Proceedings of the 1993 Engineering Foundation Conference on The Impact of Ash Deposition in Coal-Fired Plants, Williamson, J. and Wigley, F., Taylor and Francis, Washington, pp 385–398.Google Scholar
- Wigley, F. and Williamson, J. (1995). `Modelling Fly-Ash generation for UK Power Station Coals“, This Conference.Google Scholar