Lean Biogas-Air Mixture Combustion on Porous Burner with a Flamethrower Ignition System

Abstract

ABSTRACT Combustion in a porous medium burner is an effective technology that deals with low heat capacity fuels, producing low emissions of pollutant gases. Experimental investigations of filtration combustion were carried out on a laboratory-scale prototype developed by our research group. This prototype is outfitted with a novel spark ignition system attached in the middle of the reactor, which does not change the porous medium properties because it works as a flamethrower. The ignition system produces a flame front into the porous matrix that quickly reaches the operational combustion temperature of 1200 K. By applying pure methane and biogas with different CO2 contents (15% − 40%) for combustion processes, the influence of equivalence ratio, gas flow velocity, energy extraction efficiency and NOx emissions was evaluated. Experimental results such as temperature profiles, reaction stability and flammability limits also have been evaluated. According to the operational parameters tested in this study, this prototype setup presented a low time-consuming process to reach the temperature of combustion, almost ten times faster than those with electrical resistance. Furthermore, the prototype was capable of operating at an equivalence ratio of 0.4 and gas flow velocity of 0.2 m/s, maintaining high CO2 content in the fuel, to reach NOx emission values lower than 1.0 ppm.