CFD deposition modeling of fly ash particles on biomass fired boilers

Detecting and preventing ash deposits in boilers is critical for improving their availability in terms of working hours and for avoiding outages and related costs. To accomplish this goal, a useful, accurate and reliable computational tool for predicting and preventing fouling problems in boilers that fire troublesome biofuels is presented. Our model uses inertial particle deposition in a fully developed turbulent boundary layer using the Lagrangian stochastic particle tracking method of quadrant analysis. The model considers the condensation of alkali salt vapors as well as the impact mechanism of coarse sticking particles in fluegas. A reference viscosity based on kinetic energy is used in order to settle proper sticky limits. Finally, the deposition modeling is compared to deposit probe measurements in existing boilers where the deposition wall temperature has been controlled.