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BURNER DESIGN CRITERIA FOR NOX CONTROL FROM LOW-BTU GAS COMBUSTION. VOLUME I. AMBIENT FUEL TEMPERATURE
Citation:
Shoffstall, D. BURNER DESIGN CRITERIA FOR NOX CONTROL FROM LOW-BTU GAS COMBUSTION. VOLUME I. AMBIENT FUEL TEMPERATURE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/7-77/094a.
Description:
The report gives results of a research program initiated to characterize problems associated with retrofitting existing utility boilers with low- and medium-Btu gases produced using commercially available coal conversion processes. All experimental results were gathered from a pilot-scale furnace fired with a movable-vane boiler burner at a heat input of 0.66 MW (2.25 million Btu/h). The synthetic gases tested, ranging in heating value from 3.7 to 11.2 MJ/cu m (100 to 300 Btu/SCF), were produced using a natural gas reformer system. Data were collected to permit a comparison between natural gas and the synthetic gases in the areas of flame stability, flame length, flame emissivity, furnace efficiency, and NOx emissions. Flame stability was found to be very sensitive to fuel jet velocity. An injection velocity of 30.5 m/s (100 ft/s) was found to be optimum. Flame length decreased with increasing movable-vane angle (swirl of the combustion air): flames of the synthetic gases tested generally were shorter than those of natural gas. Good agreement was obtained between measured and calculated flame emissivities. Some boiler modifications would be necessary to maintain rating when burning gases of less than 7.5 MJ/cu m (200 Btu/SCF) heating value. NO emissions were ordered by adiabatic flame temperature. The NO emissions data yielded an activation energy of 153 kcal/mole compared to kinetic model predictions of 135 kcal/mole.