Numerical simulation on NOx reduction in the float glass furnace with gradient oxygen-enhanced combustion

To reveal the influence of using gradient oxygen-enhanced combustion on the gas-flow, combustion status, heat transfer and NOx emission in glass furnace, numerical simulation on the flame space of an actual float glass furnace with air combustion was conducted. The streamline of combustion-supporting gas and flue gas was displayed, the temperature distribution and heat transfer performance in the flame space were analyzed, and the mechanism of NOx emission reduction by gradient oxygen-enhanced combustion was explored. The comparative study between air combustion and gradient oxygen-enhanced combustion showed that there is not much difference in the streamline and temperature distribution in flame space, which ensures the stability of working state in furnace. Compared with air combustion, the temperature of the batch zone was increased by using gradient oxygen-enhanced combustion, and the high temperature combustion zone was closer to the glass surface, which increases the radiant heat flux to the glass surface. In addition, the NOx emission concentration in flue gas at the outlets was reduced by 17.1%. The results obtained in this study not only provide important theoretical guidance for gradient oxygen-enhanced combustion in glass furnace, but also lay a foundation for further research about advanced combustion mode to save energy and reduce emissions.