Study of Fuel Composition, Burner Material, and Tip Temperature Effects on Flashback of Enclosed Jet Flame

Abstract

Flashback is a key challenge for low NOx premixed combustion of high hydrogen content fuels. Previous work on jet burner configurations has systematically investigated the impact of fuel composition on flashback propensity, and noted that burner tip temperature played an important role on flashback, yet did not quantify any specific effect (Shaffer, B., Duan, Z., and McDonell, V., 2013, “Study of Fuel Composition Effects on Flashback Using a Confined Jet Flame Burner,â€‌ ASME J. Eng. Gas Turb. Power, 135(1), p. 011502). The present work further investigates the coupling of flashback with burner tip temperature and leads to models for flashback propensity as a function of parameters studied. To achieve this, a jet burner configuration with interchangeable burner materials was developed along with automated flashback detection and rim temperature monitoring. An inline heater provides preheated air up to 810 K. Key observations include that for a given condition, tip temperature of a quartz burner at flashback is higher than that of a stainless burner. As a result, the flashback propensity of a quartz tube is about double of that of a stainless tube. A polynomial model based on analysis of variance is presented and shows that, if the tip temperature is introduced as a parameter, better correlations result. A physical model is developed and illustrates that the critical velocity gradient is proportional to the laminar flame speed computed using the measured tip temperature. The addition of multiple parameters further refined the prediction of the flashback propensity, and the effects of materials are discussed qualitatively using a simple heat transfer analysis.