EXPERIMENTAL STUDY ON COMBUSTION OF CH4/NH3 FUEL BLENDS IN AN INDUSTRIAL FURNACE OPERATED IN FLAMELESS CONDITIONS

Abstract

This paper presents the results of an experimental study on the combustion process of methane mixed with NH3 in flameless mode. At a time of striving for CO2-free power, NH3 became a potential energy storage carrier fuel from renewable sources. Flameless combustion features low emissions and is a very efficient technology used in the power sector, as well as steel production, ceramics, etc. Industrial furnaces were tested in the context of pure methane combustion with an addition of NH3, up to 5%. Flameless combustion conditions were achieved with a regenerative gas burner system (high regenerative system). The burner consists of four ceramic regenerators allowing for continuous preheating of air, even up to 50 K lower than the temperature of the combustion chamber wall. Constant power of the introduced fuel was kept at 150 kW and the fuel-air equivalence ratio ranged from 0.75 to 0.95. The results have shown a growth of molar fraction of NO in flue gases when NH3 content in the fuel rose. The increase is more significant for the tests with a higher amount of oxygen in the combustion chamber (a lower fuel-air equivalence ratio). An addition of 5% of NH3 into the fuel caused an emission of NO at the levels of 113 ppmv and 462 ppmv (calculated to O2 = 0%), respectively for low and high fuel-air equivalence ratios. The calculated conversion factor of NH3 to fuel NO has shown extremely low values, equal to 2% (ϕ = 0.95) and 8.4% (ϕ = 0.75), which indeed confirmed that NH3 can be burned with low emissions in flameless combustion technology.