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Show - 1 - 1. Introduction Natural gas is a fossil fuel that serves the cause of environmental protection. It contains no sulphur and generates no dust or unburned products during combustion. Significant progress has been made in controlfing emissions of carbon monoxide (CO) and today, as a general rule, natural gas plants emit no CO. The main concern now raised by natural gas is the production of nitrogen oxides. Anxious to strengthen the position of natural gas as a clean energy source, Gaz de France is seeking to reduce nitrogen oxide (NOx) emissions from industrial burners. Industrial burners operating at high temperatures with preheated air are the main focus of ongoing Gaz de France studies. With standards becoming increasingly stringent, the techniques normally implemented to reduce NOx emissions are frequently inadequate when the temperature levels of the industrial processes and preheated combustion air are too high. Gaz de France and the company Stein Heurtey are engaged in joint studies to define and implement a method to analyze, predict and reduce NOx emissions. The approach adopted draws partly upon modelling studies and partly upon test measurements performed on an industrial burner using preheated air. This paper sets out the first results of work performed to date. The first part of the document concerns characterization tests and describes the burner and the preliminary studies performed on NOx reductions. The second part concerns the numerical simulation of non-reactive flows and validation tests. The third and last part of the document sets out the results of the detailed studies performed on the flame and the numerical simulation of reactive flows. It also makes a number of initial comparisons. 2. Characterization tests 2.1 Introduction The first stage involved tests to characterize the burner used in this study: the BSI-1 burner by the company Stein-Heurtey. With a view to reducing NOx emissions from the burner, Stein-Heurtey has implemented an empirical approach based on its wide experience and in-depth knowledge of the burner. The method involves air staged combustion . • The burner functions with preheated combustion air and is generally used by SteinHeurtey to reheat thin slabs. A diagram is provided in Figure 1. Catalogue data are as follows : * BSI-1-type semi-intensive burner, * rated power : 200 kW, * functions with preheated air up to 400°C, * pilot-burner ignition, * pilot-flame detection by ionization, * control : stage-modulated or on/off. . .. 1 .. |
