ALSTOM Power, Inc. is developing an enhanced combustion, low-NOx burner for tangentially-fired boilers. The objective is to optimize combustion via control of near-burner time, temperature, turbulence, and stoichiometry. Candidate low-NOx burner components being tested include enhanced coal nozzle tips and internal and external air and fuel separators. These components are being integrated into ALSTOM's latest generation of the TFS 2000 firing system. The enhanced low-NOx burner is designed to achieve an emission rate of less than 0.15 lb/MMBtu and have minimal balance-of-plant impacts while burning high-volatile bituminous coal. The project includes computational fluid dynamics (CFD) modeling and large pilot-scale testing (approximately 50 MMBtu/hr) to provide information for designing a full-scale version of the enhanced low-NOx burner. An illustration of ALSTOM's baseline low-NOx concentric firing system (LNCFS) P2 coal nozzle tip is shown to the right.

ALSTOM conducted pilot-scale testing of improved coal nozzle tips firing an Illinois No.6 high-volatile bituminous coal in November 2005. The figure below presents the NOx reduction achieved for each of the tested coal nozzle tips relative to the baseline LNCFS P2 tip. It is apparent that coal nozzle tip design can have a significant impact – some of the new tip designs resulted in NOx emissions 40% lower than those achieved with the baseline P2 tip. ALSTOM will test the new coal nozzle tip designs in a full-scale tangential-fired boiler to evaluate burner-to-burner interactions.