The aim of the AiF-funded project “FLUFF” is to provide experimentally validated CFD models for the thermal conversion of substitute fuels.

Germany is currently a pioneer in the use of substitute/secondary fuels from waste (RDF). In the cement industry, RDF is typically used in co-combustion in addition to the standard fuel pulverised coal. Since secondary fuels contain a biogenic portion, this has a positive effect on the CO2 balance of the plants. In terms of mass, the largest share of high-calorific waste in cement plants (1.9 million tonnes, corresponding to approx. 36 million GJ) is represented by processed solid flyable fuels (FLUFF). FLUFF is a mixture of different fractions, e.g. paper and cardboard, wood, plastic films and 3D plastic particles. Typical for FLUFF is the complex composition and the different flight and combustion behaviour of the particles. Therefore, the aim of the project is to provide 3D combustion simulations with computer codes (CFD simulations) to describe the flight behaviour and burn-up of RDF, which is a cost-effective alternative to the experimental investigations in original scale for the replacement of regular fuels.

At IAI, new methods for determining the statistics of the three-dimensional trajectories and ignition times of reacting particles in the rotary kiln and in a “hot” drop shaft are being developed by means of camera technology and used to analyse the data from various measurement campaigns. A plenoptical high-speed camera system (light field camera) is used for this purpose.