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Show NUMERICAL STUDY ON COMBUSTION CHARACTERISTICS AND NOx EMISSION IN HIGHLY PREHEATED AND DILUTED AIR COMBUSTION /. YUAN and I. NARUSE Department of Ecological Engineering, Toyohashi University of Technology Tempaku-cho, Toyohashi, 441-8580, Japan ABSTRACT The gas diffusion combustion in a regenerative furnace with highly preheated and diluted air has been numerically investigated in this paper. The highly preheated air combustion possesses high combustion intensity and high level temperature, but the N O x emission also has an unwanted high level. Decreasing the oxygen concentration in the highly preheated air could decrease the N O x emission and improve the uniformity of temperature distribution in the furnace. The combustion characteristics of highly preheated and diluted air combustion have been studied, including temperature distribution, soot formation, O H radical distribution, as well as N O x emission. The influence of the preheated air temperature, the oxygen concentration, and the air diluent has also been investigated. The optimal combinations of the preheated air temperature and the oxygen concentration have been predicted in the case of flue gas recirculation, which could provide the possible highest temperature in the furnace while keeping the N O x emission lower than the permitted value. KEY WORDS highly preheated air; air dilution, NOx emission; gas diffusion combustion; regenerative furnace 1. INTRODUCTION Since the high efficient heat regenerator has been developed, the highly preheated air combustion technique has become accessible for the design of the advanced industrial furnace. At present the relating investigations have been widely performed in many institutes, |
