Enhanced design for oxy -fuel fired batch tanks using CFD methods

Oxy-fuel firing is more energy efficient and environment friendly than conventional air-fuel firing and its application for glass melting has begun since 1990. This technology has been advanced for continuous glass melting furnaces based on continued research and application experiences accumulation, while its application in batch tanks is experiencing a transition period. Batch tanks are commonly used by the hand and art glass companies. Compared to continuous furnaces, a batch tank has smaller size and higher operation temperature. The four primary concerns in the application of oxy-fuel firing in batch tanks are (1) The high flame temperature of oxy-fuel firing may overheat the batch tank refractory; because of batch tank\u27s size, both flame length and width are critical factors for batch tank design. (2) Flame length and width as well as flame temperature depend on burner design, therefore, research on oxy-fuel burner performances is indispensable for enhanced batch tank design. (3) Proper burner placement in batch tank makes better heat transfer to glass while avoiding overheating refractory. (4) NO x formation in an oxy-fuel fired batch tank is sensitive to the nitrogen content in both fuel and oxygen supply, and to oxygen fuel mixing pattern as well as tank geometry. The NOx emissions need to be predicted for enhancement of burner design, burner placement, and tank geometry design as well as settings of operation parameters.;This research focused on the above four primary concerns of oxy-fuel firing and specified the primary aspects of an oxy-fuel batch tank design. The physical and chemical processes of the combustion and heat transfer were analyzed and modeled using computational fluid dynamics (CFD) methods. Based on the modeling of the geometry, the turbulence, the chemical reaction, the radiation, the NOx formation, and the soot formation, these specified aspects of most concern in batch tank design were simulated using commercial CFD software FLUENT.;Oxy-fuel flame features and the burner-tank compatibility as well as the NOx emissions were simulated. First, the commonly used traditional coaxial burners with a wide range of jet velocities were systematically studied and fuel-oxygen velocities were optimized, which provides a guidance of burner selection and operating condition setting for small and medium batch tanks. Second, flat flame burners were studied for medium and large batch tanks. It is found that flat flame has better flame coverage over glass surface and better overall temperature distribution, which enhances heat transfer to glass while lessens superstructure refractory corrosion and reduces NOx emissions. The effect of buoyancy on flame propagation can be counteracted by calculated direction setting of the flat flame burner. Third, burner placement in batch tank was investigated to ensure an appropriate match between the oxy-fuel burner(s) and a batch tank. The results of this research provide an overall understanding of the batch tank design and operation, and will help in dissemination of oxy-fuel firing technology in the hand glass industry