Influence of Primary and Secondary Air Supply on Gaseous Emissions from a Small-Scale Staged Solid Biomass Fuel Combustor

The emissions from traditional biomass combustion systems for cooking and heating are, globally, the main cause for premature mortality as a result of air pollution. A staged combustion process that separates the thermochemical conversion of the solid fuel and the combustion of the released products offers potential to reduce harmful emissions for solid fuel combustion and could, therefore, help mitigate the issue. In the present study, the fundamental combustion behavior of a small-scale staged combustor was investigated, with a focus on an independent systematic analysis of relevant parameters. Natural and forced draft conditions as well as a combination of both were tested. The relative location of primary to secondary air was also varied. When lighting the fuel, higher air flows lead to faster ignition and lower emissions. A steady-state combustion phase is achieved when gasification products are burned with secondary air, which occurs mainly while the solid fuel is being pyrolyzed. After the steady-s...