| The environment pollution and energy utilizaiton has been two important issues threaten human survival and development in the worldwide, thus controlling NOx emissions becomes an important problem that restricts the development of power generation industries. The coal fired units can operate with high efficiency and low NOx emission by retrofitting low NOx burner and optimizing operation. Therefore, it is of great significance for examining the mechanism of NOx production in coal combustion and the control method. Taking a 330 MW tangentially fired boiler before and after low NOx modification as an object, the combustion characteristics before and after the transformation of the entire furnace are investigated with numerical simulation and experimental methods, in order to provide the reference for industrial applications.Firstly, the existing problems in actual operation of boiler and the various models used in the numerical simulation are reviewed in this paper. Secondly, renovation of the burner is carried out with low nitrogen transformation program design, and a reasonable mathematical model and calculation method are selected for examining the characteristics of the boiler. Numerical simulation of the boiler before and after low NOx burner modification is conducted. The effects of coal types, coal concentration ratio and overfire air(OFA) change on furnace temperature field, the concentration of NOx emission characteristics and components are discussed. The numerical simulation results are comparatively analyzed with the results of performance test. Finally, a comprehensive evaluation on modification of burner of low nitrogen is presented, and some effective measures to reduce the emission of NOx are suggested for the actual operation of the boiler. |
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