Development of combustion data to utilize low-Btu gases as industrial process fuels. Project 61004 special report No. 6: high-excess-air burner. [From natural gas to low Btu gas

Abstract

Data were collected to evaluate the performance of a high-excess-air type burner when retrofit with low-Btu gases. The burner, a North American Model 4422-7 XSA, was fired on the IGT pilot-scale test furnace with a load simulating a section or zone of a refractory kiln. The low-Btu gases simulated for these commbustion trials were Koppers--Totzek oxygen (KTO), Wellman--Galusha air (WGA), and Winkler air (WA) fuel gases. KTO exhibited no flame stability problems at a 3 million Btu/hr firing rate with excess air levels from 10% to 77% - the maximum air flow our blower could attain. KTO did not require a burner pilot for stability. WGA fired at 3 million Btu/hr was stable with a pilot flame at excess air levels from 10% to the blower maximum, which was 65% excess air for WGA. With no pilot flame, WGA blew off in all cases. With the pilot, WA, at 3 million Btu/hr, did not have a stable flame, even with only 10% excess air; however, at 2.5 million Btu/hr WA had a stable flame at excess air levels from 10% to the maximum, 97%, with the pilot on. Blowoff occurred when the pilot was extinguished. KTO, with 50% excess air,more » gave a higher thermal efficiency and peak flame temperature than natural gas with the same excess air level. WGA fired at 10% excess air performed as well as the natural gas with 50% excess air in terms of thermal efficiency and exceeded natural gas in radiant flux. WGA, however, had a flame length about 3 times that of natural gas. WA at 2.5 million Btu/hr, 10% excess air had the same thermal efficiency (25%) as natural gas exhibited at 3.0 million Btu/hr with 50% excess air, but had lower gas temperatures and radiant flux.« less