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Show - 2 - 2.2 Methodology and test structure Tests were performed on a test cell at the Gaz de France research centre. This made it possible to closely simulate industrial conditions and also to dissociate the operating parameters of the equipment undergoing tests to a great extent. The test cell is equipped with numerous features to configure operating conditions (furnace temperature, furnace pressure, burner pressure, etc.). One of the main features is a variable heating load using water-cooled tubes, which are inserted into the heat chamber in line with test requirements. This makes it possible to control the temperature of the furnace independently of other burner operating parameters. Figure 2 shows a photograph of the test cell and its heating load. Measurements are taken at each point of operation when a balance is achieved between the heating load and the operating conditions of the burner. This approach provides good overall correlation between parameters (gas flowrate, fluid pressure, fluid temperature, analysis of combustion products, etc.). A measurement acquisition and processing system is used to sort and analyze results. 2.3 Main results During the test campaign, we analyzed the influence exercised by different operating parameters of the 881-1 burner (with or without staged combustion) on NOx emissions: * temperature of combustion air, *furnace temperature, * burner power, * air-fuel ratio. A single parameter was modified each time. The others retained a constant value corresponding to normal burner adjustment. All tests were performed in a cell with slight overpressure (1 to 2 mmWG) and used natural gas. Over and above the excellent coherence of results, a certain number of conclusions can be drawn from tests. When combustion air is preheated to 600oG, emissions are approximately four times higher than with cold air, whatever the furnace temperature. With a cell temperature of 1,370oG, emissions are approximately 1.4 times higher than with a cell temperature of 1,1 OooG, whatever the temperature of the combustion air. NOx emissions vary as a function of the excess air ratio to form a bell-shaped curve. With the 881-1 burner, the highest NOx emissions were obtained for an excess air of 100/0. . . .1 .. |