Detailed experimental investigation and characterisation of oxy-fuel biomass burners via laser-optical methods

The scope of project B4 is to gain a deeper understanding of fluid-mechanical, particle-dynamical and chemical processes underlying pulverised solid fuel combustion under Oxy-Fuel conditions in the near-nozzle region. These mutually coupled processes determine volatilisation, mixing, ignition and flame stabilisation. For these investigations, advanced laser diagnostics are applied to an optically accessible combustor. The comprehensive set of data is also used in the CRC/TRR 129 to improve mathematical modelling and supports validation of numerical simulation tools developed in project C2. In line with C1 project B4 contributes to a sequence of validation data spanning the range of scales: B4 less than or equal 60 kWth; C1 less than or equal 120 kWth.

For this purpose, laser-optical methods such as particle image velocimetry (PIV), particle tracking velocimetry (PTV), laser induced fluorescence (LIF), coherent anti-Stokes Raman spectroscopy (CARS), two-colour pyrometry, phosphor thermometry and laser-induced incandescence (LII) are applied and adapted to the Oxy-Fuel combustion process. The combustor investigated in B4 is equipped with a geometrically identical nozzle as in projects C1. In contrast to C1 the focus is on gas-assisted solid fuel flames in the power range up to 60 kWth, filling the gap between unconfined laboratory systems and pilot-scale combustors. Its unique characteristic is the full optical access to the diffuser and the entire combustion chamber, and its well-controlled boundary conditions. The investigations are evolving from single-phase non-reacting to two-phase reacting studies.