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Ablative Pyrolyser
Scientists at Aston University have developed a thermolysis reactor for the conversion of solid biomass into bio-oil, for use in power and heat generation, as a precursor for biofuels, and as a raw material for chemicals and other speciality products.
  • Bio-oil output that is comparable to the best fast pyrolysis reactors
  • Higher specific throughputs
  • Lower reactor and system volume
  • Lower capital and running costs
  • Much larger particles of biomass
Background
Fast pyrolysis is the only technology that directly produces a liquid fuel through the high temperature processing of renewable solid biomass such as wood or agricultural waste. The process is typically performed in fluid beds at around 500°C, but is limited by particle size, heat transfer and scaling problems. Most pyrolysis processes utilise heat transfer from a hot gas and/or solid, such as sand, to the biomass. To achieve rapid heating of the biomass, small-sized (1-3mm) feedstock particles are required.
The Technology
Aston’s ablative pyrolysis reactor offers the potential for very high specific throughputs with reduced equipment size, lower energy usage, and a corresponding drop in reactor, liquid collection and char removal costs. This technique involves the ‘melting’ or ‘thermal erosion’ of biomass that comes into contact with a hot surface (above 430°C) by applying high mechanical pressure (>1×105 Pa) to the particles as they traverse the surface. Over 85wt% of the biomass “melts” initially, then vaporises off the hot surface. Vapours are then cooled and collected to form a liquid bio-oil product.
This process has several other advantages over existing fast pyrolysis techniques:
  • Transfer of heat through a reacting liquid film on the solid surface leads to higher specific throughputs and lower operating costs
  • Significantly lower reactor volume and capital costs due to lesser requirement for inert gas and no requirement for recycle gas
  • Much larger biomass particles can be fed, such as whole tree chips of up to 50mm, rather than the small-sized particles of typically 3mm required by other fast pyrolysis techniques, thus reducing feed preparation costs
  • Novel process applications for synthesis of renewable products, such as slow release nitrogenous fertiliser, resins, and adhesives