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Show 4197299444 CORP. HQ 489 Pi1 MAR 17 '94 12:11 TESTS AND RESULTS The system has been tested extensively to investigate formation of NOx at the rich firing conditions in the ,first zone and in the reburning section over a wide range of temperatures in both sections. AS a part of these tests the burner has been tested to establish limits of its operation at the substoichiometric air fuel ratios without forming soot. The burner performance tests include operation of the burner at several firing rates, from 73kW to 293kW (0.25 to 1 million Btu/hr), and at air-fuel ratios varying from 4.8:1 to near stoichiometric condition without forming soot in the flue gases. Figure 6 shows typical operating range of the burner at different firing rates varying from 146.5kW to 293kW (0.5 to 1 million Btu/hr) The burner operatin9 limit in the rich ~ombustion region can be extended at higher firing rates and air preheat tempel."atures ., ! The NOx formation tests were carried out at firing rates of 73kW to 293kW (0.25 to 1 million Btu/hr) using air preheat of 427·C (800·~) to 699·C (1290·F). The burner is fired at rich air-fuel ratios in -the first zone which is maintained at the desired temperature. Temperature in the primary combustion section was adjusted by varying the preheated air temperature for a given air-fuel ratio and burner firing rate or by using a water cooled probe as thermal load. The combustion products of rich combustion of natural gas were cooled to approximately 782·C , \ (1400·F) prior to their reburning by injecting ambient air. The flame gases were cooled to the desired temperature by varying cooling air flow through the cooling coils. The reburninQ section temperature was controlled by adjusting combustion air flow, the amount of cooling of combustion products in the indirect cooling section and by using a water cooled probe. , \ Gas temperatures and samples were taken at several longitudinal and radial locations in the rich combustion (#1) and reburning (#3) zones for each test. The gas analysis inoluded measurements of CO, C02 I 02' H21 and nitrogen oxides (NO, N0 2 , and NOx) as percentages~f the dry gas sample. , \ |