Munson, CL
1993
Use of Equilibrium Calculations to Predict the Behavior of Coal Ash in Combustion Systems
Harb, J.N.; Richards, G.H. and Munson, C.L.
Energy & Fuels, 7:20-214, 1993. Funded by ACERC.
This paper examines the use of computer calculations to estimate the phase and species composition of silica-based systems that are important in slagging and high-temperature fouling deposits that form in pc-fired utility boilers. Advanced numerical techniques were used to minimize the free energy of the system in order to determine the equilibrium composition and phase distribution while avoiding the numerical problems often associated with such calculations. The equilibrium model, which assumed ideal solutions of complex species, adequately approximated the behavior of a variety of systems for which experimental phase diagrams were available. The model, however, performed poorly for certain silica-rich systems due to an inadequate representation of the silica activity. Comparison of calculated results for actual coal ashes with the experimentally observed behavior showed good agreement for systems that did not have SiO2(1) in the calculated results. Calculations for ashes with high silica content predicted excessive amounts of liquid that were inconsistent with the experimental observations. The addition to the calculations of an empirical constraint on SiO2-(1), based on eutectic temperatures from ternary phase diagrams, yielded good agreement between the calculated results and the observed slagging behavior.
1990
Theoretical Investigation of Ash Transport in a Laminar Drop-Tube Furnace Including Temperature and Compositional Effects
Harb, J.N.; Richards, G.H. and Munson, C.L.
Proceedings of the ASME Ash Deposit and Corrosion Research Committee Seminar on Fireside Fouling Problems, Brigham Young University, Provo, UT, 1990. Funded by ACERC.
A mathematical model was developed to investigate particle deposition in a laminar drop-tube furnace. Specifically, simulations were performed to examine the effects of geometry, transport, plate temperature, and particle composition on deposition. Because of the geometry of the deposition region, the diameter of the inlet particle stream was narrowed and particle impaction rates were significantly enhanced near the center of the plate. The location of particle impact and the temperature of the particle upon impaction were both strongly dependent on particle size. The particle temperature at impaction was relatively insensitive to the plate temperature for particles greater than 15 to 20 µm in diameter at plate temperatures of 750K and 1400K. Calculation of composition effects indicated that particles of different sizes with similar compositions might exhibit significantly different sticking behavior owing to the formation of liquid phases.
Munson, CL
1993
Use of Equilibrium Calculations to Predict the Behavior of Coal Ash in Combustion Systems
Harb, J.N.; Richards, G.H. and Munson, C.L.
Energy & Fuels, 7:20-214, 1993. Funded by ACERC.
This paper examines the use of computer calculations to estimate the phase and species composition of silica-based systems that are important in slagging and high-temperature fouling deposits that form in pc-fired utility boilers. Advanced numerical techniques were used to minimize the free energy of the system in order to determine the equilibrium composition and phase distribution while avoiding the numerical problems often associated with such calculations. The equilibrium model, which assumed ideal solutions of complex species, adequately approximated the behavior of a variety of systems for which experimental phase diagrams were available. The model, however, performed poorly for certain silica-rich systems due to an inadequate representation of the silica activity. Comparison of calculated results for actual coal ashes with the experimentally observed behavior showed good agreement for systems that did not have SiO2(1) in the calculated results. Calculations for ashes with high silica content predicted excessive amounts of liquid that were inconsistent with the experimental observations. The addition to the calculations of an empirical constraint on SiO2-(1), based on eutectic temperatures from ternary phase diagrams, yielded good agreement between the calculated results and the observed slagging behavior.
1990
Theoretical Investigation of Ash Transport in a Laminar Drop-Tube Furnace Including Temperature and Compositional Effects
Harb, J.N.; Richards, G.H. and Munson, C.L.
Proceedings of the ASME Ash Deposit and Corrosion Research Committee Seminar on Fireside Fouling Problems, Brigham Young University, Provo, UT, 1990. Funded by ACERC.
A mathematical model was developed to investigate particle deposition in a laminar drop-tube furnace. Specifically, simulations were performed to examine the effects of geometry, transport, plate temperature, and particle composition on deposition. Because of the geometry of the deposition region, the diameter of the inlet particle stream was narrowed and particle impaction rates were significantly enhanced near the center of the plate. The location of particle impact and the temperature of the particle upon impaction were both strongly dependent on particle size. The particle temperature at impaction was relatively insensitive to the plate temperature for particles greater than 15 to 20 µm in diameter at plate temperatures of 750K and 1400K. Calculation of composition effects indicated that particles of different sizes with similar compositions might exhibit significantly different sticking behavior owing to the formation of liquid phases.