Development of a pilot-scale flameless oxidation burner for ultra-low NOx combustion of pulverised coal

This project aims to develop new flameless oxidation (FLOX) burners for lignite and bituminous coals combustion. Development of the coal FLOX burners is supported by experimental investigation and by CFD modelling. Based on the results obtained, the most promising design will be scaled up to pilot-scale and tested. The burner has to meet the following challenging measurable objectives: - NOx emissions inferior 200 mg/Nm3 (at 6 % 02), - CO emissions inferior 100 mg/Nm3 (at 6 % 02), - C in ash inferior 5 %. The project evaluated the necessary aspects of coal FLOX burner development and up-scaling: Coal FLOX burner design: It became apparent from experimental data obtained from different burner designs and different coal types that a single FLOX burner design would be capable of firing the full range of coals specified. Experimental investigation: Testing on bench and pilot-scale was successfully completed. Experiments showed an overall NOx reduction capability with the current burner design of about 20-50 % depending on coal type and burner excess air ratio. Coal FLOX burner up-scaling: Designs for a 2 MWt and a 40 MWt coal-fired FLOX burner were developed. The impact of FLOX combustion with the 40 MWt design burners installed on wall-fired and tangentially-fired plant was investigated using engineering performance models and CFD; in all cases the impact on furnace performance was moderate. The full-scale testing of a 40 MWt coal FLOX burner was shown to be feasible.