Velocity and Particle Mixing in a New Stack at the 222-S Analytical Lab

摘要

Air velocities in the newly planned exhaust system at building 222-S are calculated for several operating scenarios. The exhaust system consists of 4 rectangular ducts, a 66-in diameter stack about 9 meters tall, and a transition volume between the ducts and the stack. Air flowing through the exhaust system is filtered by multiple stages of HEPA filters. However, if there were a failure of each and every stage of filters, which is very unlikely and not part of this analysis, some particles may get into the stack. Air from the stack is sampled periodically for particles to determine the level of particle concentrations in the stack. Since the particles may come from just one inlet duct, the horizontal distribution of the particles in the stack may not be uniform. The particle concentration profiles at various locations in the stack and transition volume are calculated using a CFD (Computational Fluid Dynamics) code. Particle concentrations are calculated for solid respirable particles with a unit density and a diameter of 5 microns. The modeling approach and model are described.