Optimisation of Support Fuel Consumption Burning Low Heat Value Gas Using Controlled Combustion Oscillations

The purpose of this work is to develop a new combustion technology to reduce the operation costs of thermal systems that burn low heat value gases. Landfill methane emission is a greenhouse gas source which can be defined and reduced. Landfill managing companies in Austria have adapted the latest regulations on methane emissions primarily by collecting and flaring off landfill gas, sometimes with energy recovery. Their concern is related to long-term landfills where the methane concentration by volume falls well below 20%. The costs to flare-off these gases are mostly driven by the use of support fuel to ensure combustion. A technical solution using the programme MethaNull (to approach zero methane emissions) is proposed to extend the combustion domain of gases with low heat value so that the amount of support fuel can be significantly reduced. This solution should fit a large range of LHV gases, for combustion at ambient conditions as well as under pressure at elevated inlet temperature conditions. The process has similarities with pulse combustion, where the combustion process benefits from a higher energy density and better heat transfer rates. As the forced pulsation is generated by a separate module, the methodology can be easily adapted or retrofitted for existing facilities. This paper covers the MethaNull programme, the burner design, the flow pulsation technology and its operation. A systematic comparison between steady state and oscillating combustion is presented.