Visualization of the Flow in a New Injection Burner

The flow in a newly developed injection burner has been visualized seeding the air exiting the diffuser with smoke particles. The work intends to optimize the diffuser design. Two different geometries have been analyzed, with and without the inclusion of a finned swirler ring to generate rotation in the secondary air in the same direction as the primary one. With the swirler, the co-flow rotation is increased and this translates in an enhanced shearing with the flow exiting the nozzle, which looks more elongated and confined to the diffuser axis than in the absence of the swirler. The growing shortage of fossil fuels and the stricter regulations to avoid pollutant emissions are forcing to burn low quality oils as well as alternative fuels, among them a large variety of biomass, with the highest efficiency. From the different possible ways to achieve combustion, industrial applications that use burners in which pulverized solid or atomized liquid is injected inside the combustion chamber are the most commonly used to obtain high calorific powers. The main elements in this type of burners are the injector or the atomizing nozzle, depending on the use of solid or liquid fuels, and the air diffuser. In the past years, our group has worked in the development of new nozzles, specifically designed to atomize high viscosity oils. To complete the burner assembly, an improved diffuser is being studied. This element is responsible to supply the air required for combustion, to enhance the mixing and dispersion of the particles or droplets, to regulate their residence time in the reaction zone in order to ensure a complete combustion, and to confine the flame in a determinate volume. Thus, to optimize the combustion efficiency it is needed to design a diffuser capable of performing all these tasks in the best possible way. Materials and Methods