RMT, Inc., a subsidiary company of Alliant Energy Corporation, and the University of North Dakota Energy and Environmental Research Center (EERC) have developed an ash behavior prediction tool, called AshPro(SM), to assess slagging and fouling in coal-fired boilers. This tool integrates boiler computational fluid dynamic (CFD) simulations with ash behavior models including ash formation, transport and deposition, as well as deposit growth and strength development. AshPro(SM) was applied to a 512-MW tangentially-fired boiler at Wisconsin Power & Light's Columbia Energy Center to evaluate the localized slagging on furnace walls and fouling in convective pass. The predicted boiler ash deposition pattern is reasonably consistent with that observed on the furnace walls and super heater division panels. The prediction of slag state transition (solid/liquid) through deposit viscosity was verified by the observation in the plant. (C) 2007 Elsevier B.V. All rights reserved.