NUMERICAL MODELING OF 3-DIMENSIONAL FLY-ASH FLOW IN POWER UTILITY BOILERS

A two-fluid Eulerian model in combination with a particle-wall collisi on model and generalized Eulerian boundary conditions for the particul ate phase is employed to predict complex three-dimensional fly-ash flo ws which often cause severe erosion to boiler tubes located in power u tility boilers. Mean momentum and mass conservation equations are solv ed for each phase using a finite volume scheme with two-way coupling a nd a modified renormalization group (RNG)-based k-epsilon turbulence m odel. Comparison of predicted particle concentration with measured dat a is made and excellent agreement is obtained. The detailed character of the particulate velocity field and concentration just downstream of the 180 degrees bend shows a marked dependence on the Stokes number n ot previously reported. (C) 1997 by John Wiley & Sons, Ltd.