NOx Development in Gas Fired Research Furnace

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TF-0- 3 N O x development in gas-fired research furnace Prof. Dr. A. Biro University of Miskolc (Hungary) Institute of Thermal energy Introduction The calculation of NOx emission in the industrial furnaces hasn't been solved yet There are two main causes of it: l.The reaction-kinetic processes haven't been clarified yet. The use of the traditional Zeldovits equations doesn't give an exact result The calculation methods have been successfully corrected by many research workers, among them Fenimore, [6], DeSoete, [7] Bowmann, [8], etc., but today w e can obtain approximate results only by "supposing" the maximum values of flame-temperatures and by "accelerating" certain reactions even in case of simple flames.The maximum flame-temperatures measured in the experimental furnaces by the leading research workers reach only 1400-1500CC, and by this only a minimum quantity of Thermo-NO can develope within the available very short time. According to the experiments carried out in an electric furnace by the author, the quantity of N O developing in the air does not exceed 1 ppmv at these temperatures [5]. Owing to this fact further researches are necessary in order to clarify the origin of the missing N O concentration. 2 Though the research workers dealing with the science of furnaces agree upon, that the N O x emmission is a burner-specific phenomenon, and it can be known and approximated by calculations only in case, if w e know exactly the effect of burners. Relatively few researches can be found in the references (see e.g. [11, 12, 13, 14, 15], where the NOx-development have been investigated by means of the systematic comparison of the properties of burners. The method accepted for systemizing the burners is also missing at present, though it is the first step for developing the calculation system of burner-specific N O x emmission. We try to work out a system for the burners and their effects in order to facilitate the development of a computer program. The present paper is the continuation of the paper read on the IFRF Conference held in Holland (May 1988). 1.0 The parameters of industrial burners A uniform system and parameters would be necessary for describing the operation of industrial burners, by which the difficulties of identification of the burners coming from their sizes, and capacity as well as from the different fuels could be eliminated. If w e want to extend the new system only to the burners of the industrial furnaces, the following data will be necessary for characterizing the burners: 17 Classification of burners 2 / Impulse-characteristics of a burner, 37 Rotation-characteristic of a burner 1.1 Classification of burners It was proposed by the author even in 1974 [1] to range the burners of industrial furnaces into 7 groups. The classification method can be seen in Fig. 1: 1.2 Impulse-characteristics of burner The use of impulse-power is accepted for characterizing the impulse of burner: I = A.p.w2, N (D However its value cannot be generally accepted from the point of view of the qualification of the burner's work, because its greatness depends on the capacity of burner. The impulse-power is increased by increasing the volume-flow of the mix, so the calculated impulse-power of a burner with 10 m3/hour capacity operating with high-speed air (200 m/s) can be