Iron Oxidation State and Its Effect on Ash Particle Stickiness
The oxidation state of iron in glassy particles dramatically affects the deposition of those particles in pulverized coal fired utility boilers. In this work, two synthetic ashes were fabricated and used to explore the effect of iron oxidation state on ash stickiness in a bench scale experimental study. The iron in these synthetic ashes, approximately 20 wt%, was initially 100% in the Fe(II) state. Experiments conducted with these ashes in an electrically heated entrained flow reactor were used to determine the stickiness of the synthetic ashes under different oxidizing environments and temperatures. Particulate samples were collected to measure the conversion of Fe(II) to Fe(III) under various conditions, and the results used to determine the rate of iron oxidation in glassy ash particles. This information was used to identify the rate limiting step for iron oxidation and to develop a simple preliminary model to predict the fraction of Fe(II) oxidized to Fe(III) as a function of time.
KeywordsParticle Temperature Collection Efficiency Oxygen Solubility Adhesion Efficiency Iron Oxidation State
Unable to display preview. Download preview PDF.
- Austin et al. (1980); “Study of the Mineral Matter Distribution in Pulverized Fuel Coals with Respect to Slag Deposit Formation on Boiler Tubes”, DOE Report Number DOE/ET/ 10560-T 1Google Scholar
- Cable, M., (1961), “Study of Refining: II”, Glass Technol., 2, 60–70Google Scholar
- Kalamanovitch, D.P., Sanyal, A., Williamson, J. (1986), “Slagging in Boiler Furnaces-a Prediction Technique Based on High Temperature Phase Equilibria”; J. Inst. Energy, 20, 20–23Google Scholar
- Raask, E. (1985), Mineral Impurities in Coal Combustion: Washington: Hemisphere Publishing Corporation.Google Scholar
- Senior, C.L., and Srinivasachar, S. (1995), “Viscosity of Ash Particles in Combustion Systems for Prediction of Particle Sticking”, Energy and Fuels (in press).Google Scholar
- Srinivasachar, S., Helble, J.J., Boni, A.A., (1990a), “An Experimental Study of the Inertial Deposition of Ash Under Coal Combusion Conditions”, Proc. of Twenty Third Symposium on Combustion, The Combustion Institute, Pittsburgh, 1305–1312Google Scholar
- Srinivasachar, S., Helble, J.J., Katz, C.B., and Boni, A.A. (1990h), “Transformations and Stickiness of Minerals During Pulverized Coal Combustion,” in Mineral Matter and Ash Deposition from Coal, R.W. Bryers and K.S. Vorres, ed., United Engineering Trustees, New York, 201–213.Google Scholar
- Srinivasachar, S., Senior, C.L., Helble, J.J., and Moore, J.W. (1992), “A Fundamental Approach to the Prediction of Coal Ash Deposit Formation in Combustion Systems,” Proc. of Twenty Fourth Symposium on Combustion, The Combustion Institute. Pittsburgh, 1 179–1 187.Google Scholar
- ten Brink, H.M., Eenkhoorn, S., and Hamburg, G. (1992), “Mineral Matter Behaviour in Low-NO, Combustion,” Proc. EPRI Conference on Coal Quality, the Electric Power Research Institute, Pal Alto CA.Google Scholar
- Turkdogan, E.T. (1983), Physicochemical Properties of Molten Slags and Glasses; London: The Metals SocietyGoogle 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 The Impact of Ash Deposition in Coal Fired Plants, J. Williamson and F. Wigley, eds., Taylor and Francis Publishers, London, 385–398.Google Scholar