Computational Optimization of a Subsonic Compressible Gas Venturi’s Ejector

The paper deals with a 3-D numerical simulation and validation against industrial measurements of turbulent frozen reacting flow in a subsonic compressible gas Venturi’s ejector used as “fluid dynamic engine” for external flue gas recirculation in a state-of-the-art “annular shaft” lime kiln. Higher stagnation thermodynamics parameters of the ejector hot gas primary stream permit the avoidance of the condensing temperature window of compounds such as K₂O and Na₂O, and KCl and NaCl that produce sticky builds-up on the ejector’s internal wall. An improved gas dynamics effectiveness allows the maximization of the amount of secondary flue gas stream using much less primary stream mass flow rate. The commercial Fluent™ UNS/5 software was used to predict all flow behavior characteristics inside the original and new Venturi’s ejectors. A reasonable agreement has been found between the computed and experimental flow rate figures of the secondary flue gas stream of the actual functioning kiln.