Alternative fuels

    Alternative fuels or Refuse Derived Fuels (RDF) are the end product of material processing plants. Commercial and municipal waste passes through a multi-stage comminution and preparation process here. The final grain size of the RDF is determined by the shredder in the final processing stage.

    The fibrous-flaky particle shape of RDF has a negative effect on the flow properties if large forces, and therefore internal stresses, are acting on the material.

    The main material properties can be summarized as follows:
    Grain size » The coarser the particle, the poorer the flow
    Grain shape » The more irregular the particle, the poorer the flow
    Bulk density » The lighter the particle, the poorer the flow
    Moisture » The moister the particle, the poorer the flow
    Grease content » The greasier and stickier the particle, the poorer the flow

    Below is an example of a typical material specification for RDF:

    Bulk material: Waste, shredded
    Bulk density: 0.1–0.5 t/m³
    Grain size: 0–60 mm, partially 1–3% to 100 mm
    Fines: Max. 2–3% < 300 µm
    Grain shape: Two-dimensional, granular
    Ash content: Max. 15%
    Inert materials: Max. 5%
    Ferrous and NF metals: Max. 0.5%
    Grain size of metal parts: Max. 40 mm
    Moisture: Max. 20%
    Temperature: Max. 80°C
    Flow properties: Moderate to low viscosity, bridge-forming

    The following acronyms for alternative fuels are frequently used in specifications and other documents:

    BRAM Brennstoff aus Müll (waste-derived fuel)
    BPG Brennstoff aus produktionsspezifischen Gewerbeabfällen (fuels derived from production-specific industrial waste)
    CDR Combustibile Derivato dai Rifiuti (refuse-derived fuel)
    EBS Ersatzbrennstoff (substitute fuel)
    EWAB Energy from Waste and Biomass
    Fluff Fluffy alternative fuels
    Flock Paper industry waste, rejects
    OTS Organische Trockensubstanz (organic dry substance)
    RDF Refuse Derived Fuel
    RESH / ASR Residual shredder materials / Automotive Shredder Residue
    SBS Sekundärbrennstoff (secondary fuel)
    SLF Shredder Light Fraction