Experimental and numerical investigation of the novel low NOXCGRI burner

This paper reports on an experimental and numerical investigation of the near field and combustion zone of a burner that realizes a FODI (Fuel/Oxidant Direct Injection) strategy for furnace firing. FODI is an non-premixed method of reactants delivery and employs a direct discharge of fuel and oxidant jets into the furnace chamber. The jets entrain significant quantities of furnace gases that have been cooled by furnace heat transfer. The fuel and oxidant streams arrive at the reaction zone diluted by furnace gases, lowering the temperature of the reaction and reducing NOx emissions. FODI involves three-feed mixing processes linked with non-adiabatic reactions at unusually low temperatures and reactant concentrations. The burner investigated here consists of fourteen fuel and air ports arranged in a circle around a central pilot flame. The global performance characteristics of the burner demonstrate the effectiveness of FODI in NOx reduction and its visually flameless oxidation process. The mathematical modelling of the burner using a commercial CFD package was capable of adequately predicting jet trajectories and primary flow structures in the furnace. The predicted temperature and species concentrations depart from measured values thus raising a question of how to effectively model three-feed processes under severe non-adiabatic conditions.