Combustion of waste gas in a low-swirl burner under syngas and oxygen enrichment

Abstract

Abstract A biomethane production from biogas could result in an emission of waste gas to the atmosphere. As these gases consist of methane up to 15\xa0vol%, they should be utilized onsite to reduce the impact of climate change. However, due to low calorific value, the combustion process of these gases could be complicated or even impossible inconvenient gas burners. For this reason, this work focuses on an investigation to clarify a complex of measures affecting the flammability limits and effectiveness of burning waste gas in a designed low swirl burner with different swirlers. The swirlers were made with vanes angles of 37°, 45°, and 53°. Critical regions of the flame structure were experimentally examined by means of chemiluminescence to determine the intensity of OH* emissions under syngas and oxygen enrichment. It revealed that the most appropriate combustion conditions taking into account the stable flame and lowest CO emissions were achieved using the swirler with a vanes angle of 45°. Moreover, under the syngas enrichment (by the addition from 0 to 25\xa0vol% of syngas), it is possible to achieve more stable combustion conditions, taking into account the low CO and NOx emissions, when oxygen-enriched air is additionally supplied. However, the oxygen enrichment levels must be selected according to the lift-off height threshold to avoid flashbacks due to the declining trend in the velocity of the flow.