Computational modeling of a utility boiler tangentially-fired furnace retrofitted with swirl burners

The paper presents 3D numerical investigation of OP-380 boiler tangentially-fired furnace utilizing bituminous coal. The boiler was retrofitted by replacing traditional jet burners with RI-JET2 (Rapid Ignition — JET) swirl burners. This kind of solution is unique in power generation systems. The purpose of this work is to show how the flow, combustion performance and heat exchange in the furnace are affected by introducing rapid ignition phenomena in RI-JET2 burners instead of delayed ignition associated with the traditional jet burners. Results were compared to simulations of similarly designed boiler equipped with traditional jet burners. Furnace simulation was preceded with a single RI-JET2 burner simulation at the inlet to a virtual combustion chamber. The results have shown that pulverized coal (PC) concentrator separates the PC into two streams: concentric with fine particles and axial with coarse particles. Stable flame operation was noticed even without secondary and tertiary air swirl. 3D simulations of combustion chamber have shown that in a burner zone a visibly isolated, concentrated flame exists in the furnace axis. This kind of flame shape reduces corrosion risk and furnace walls slagging as a result of RI-JET2 burner's long range.