2D dynamic mesh model for deposit shape prediction in boiler banks of recovery boilers with different tube spacing arrangements

Abstract

Abstract CFD tools are of great value in the design and operation of boilers. One particular aspect that can be modeled by CFD is the ash deposition and plugging of heat transfer surfaces of boilers. Fouling and slagging are the most typical causes of unscheduled boiler shutdowns. Consequently, appropriate predictions of deposit geometries and rates are of considerable interest. CFD multiphase flow simulations are capable of modeling particle-laden streams and constitute a suitable tool for study of material deposition. Fouling phenomena have a complicated and multidisciplinary nature involving thermo-fluid mechanics, sticking/rebounding of particles, sintering, etc. If the deposit growth rate has been accurately calculated by a multiphase model appropriate for particle-laden flows, CFD dynamic mesh techniques are able to move the interphase fluid-deposit according to the growth rate. This work develops and presents a CFD model for prediction of deposition shapes in a classical boiler bank of a Kraft Recovery Boiler by combining a multiphase and a dynamic mesh model. The effect of tube transversal spacing is also analyzed. The paper highlights the features and effects of the dynamic mesh model.