Experimental Evaluation of a Radiant Tube Combustion System Fired With Oxygen Enriched Combustion Air

This paper discusses the results of testing a gas fired radiant tube combustion system fired with oxygen enriched combustion air. The thermal efficiency of a radiant tube combustion system depends on furnace temperature, the geometry of the radiant tube, the firing rate of the burner and the combust ion air oxygen concentration. Because of the large quantity of parameters involved, an experimental approach was selected for determining the effect of oxygen enrichment on radiant tube thermal efficiency. The experiments were performed with a standard radiant tube combustion system as normally used with standard air. The range of furnace temperatures tested was 700°C to 1315°C and the combustion air oxygen concentration varied from 21 to 80 percent. Radiant tube diameters tested were 0.102, 0.181 and 0.254 m. Various thermal loading conditions were tested to simulate actual firing practices experienced in the field. The results indicated that increasing the oxygen concentration of the combustion air substantially increases the thermal efficiency of the combustion system. Additionally, the increase in flame temperature due to the increase in combustion air oxygen concentration had little effect on the radiant tube or burner materials. The radiant tube temperature is primarily a function of furnace temperature and firing rate.