Comparative analysis of combustion characteristics and economy between air assisted combustion and oxy-fuel combustion in glass furnaces

Abstract

The oxy-fuel combustion is an effective means to improve the high energy consumption, pollution, and economic cost of glass furnaces. In this paper, the combustion characteristics in the flame spaces of traditional natural gas/air assisted combustion glass furnace (GF-NAC) and reformed natural gas/oxy-fuel combustion glass furnace (GF-NOC) are analyzed and compared by means of numerical calculation. More importantly, a systematic quantitative comparative analysis is conducted on the economic performance of the two glass furnaces from the perspectives of fixed and operating costs. The results show that enhanced combustion performance of GF-NOC over GF-NAC is found with flames being extended across the entire width of the furnace in GF-NOC. A more uniform temperature distribution within the furnace is consequently accomplished in GF-NOC. The flame center temperature, the average furnace temperature, and the average glass surface temperature in GF-NOC are increased by 7.42 %, 1.17 %, and 7.96 %, respectively, compared to GF-NAC. Furthermore, a reduction in gas velocity by 50 % at the arch in GF-NOC is observed to mitigate the erosive effects of high-temperature gas flows on the furnace crown. According to the service life of glass furnace of 15 years, the GF-NOC can save 420 M (million yuan) (12.8 %) compared to the GF-NAC. Although the fixed cost of GF-NOC is 9.82 M (5.43 %) higher than that of GF-NAC due to the expenditure on oxygen production equipment, the difference is offset by operating costs. Compared to GF-NAC, GF-NOC can save operating costs of 28.7 M (15.87 %) per year.