TROUBLE-SHOOTING A SORBENT INCINERATION SYSTEM USING COMPUTATIONAL FLUID DYNAMIC SIMULATIONS

摘要

US Army chemical agent disposal facilities generate considerable quantities of agentcontaminated charcoal sorbent. The system designed to process this charcoal involves micronization of the solid and injection of the resulting fine powder into a specially designed burner. The burner is retrofit into a kiln that is used in an earlier stage of the demilitarization process. The burner has encountered operational limitations as a result of refractory damage and slag buildup that have proven difficult to understand and address. Preliminary studies of the burner suggested design modifications and reduction in charcoal processing rate as potential means of decreasing the incidence of unscheduled outages. However, for a variety of reasons, these suggestions are not sufficient to achieve the Army's objectives of safely, reliably, quickly, and cost-effectively processing this waste stream. In an effort to improve the understanding of the problematic issues relating to the existing design and to identify and characterize promising means by which to address these challenges, a three dimensional, two-phase, reacting CFD model of the burner and near burner regions has been created. Simulation of the system, under design and off-design conditions, was performed to determine gas-phase properties, charcoal particle dynamics and reactions, wall heat flux and temperature patterns, and charcoal/ash deposition rates on burner and wall surfaces. Simulation results indicate that burner firing rate, charcoal size distribution, supplementary fuel injection, agent content, and ash/refractory composition should be carefully considered as a means of addressing the performance issues that have been identified.