Numerical Investigation and Improvement of Coke Oven Gas-Fired W-Shaped Radiant Tubes for NO_X Reduction

摘要

In this study, to solve the problem of excessive NOx emission of W-shaped radiant tube (WRT) burning coke oven gas (COG), the numerical calculation method was adopted to investigate the effects of N-2 and CO2 as diluent gases in the air, CH4 as a diluent gas in the fuel, and blast furnace gas as a diluent gas for COG on NOx emissions of WRT. Besides, a novel WRT (N-WRT) with a flue gas circulation structure was developed to reduce NOx emissions. Moreover, the effects of the nozzle diameter and nozzle location on the gas flow, temperature distribution, and NOx emission were analyzed and discussed in detail. The results shows that CO2 as a diluent can inhibit the production of NOx more than N-2. The high NOx emission of the COG-fired WRT is caused by a higher proportion of H-2 and CO in COG. The NOx production of the WRT is about 6 times that of the N-WRT, indicating the effect of circulating flue gas on reducing NOx emission is quite remarkable.