Gasification of leached orujillo (olive oil waste) in a pilot plant circulating fluidised bed reactor. Preliminary results

Nearly a quarter of the worldʹs olive oil production takes place in Spain, where energy companies are starting to exploit the potential of the residues from this industry as biomass fuel for energy production. Approximately, 2 million t/yr of orujillo (a residual by-product of the olive oil production industry) are generated in Spain. Fluidised bed gasification is considered to be the most advanced method for thermochemical conversion of various biomass fuels to energy. Ash-related problems such as sintering, agglomeration, deposition, erosion and corrosion, which are due to the low melting point of ash in the agroresidues, are the main obstacles for economical and viable application of this conversion method for energy exploitation of the specific residues. The leaching (washing) of inorganic constituents from biomass leads to changes in inorganic composition and substantial improvements in ash thermal behaviour under gasification conditions. Leached orujillo has been tested in a 300 kWth atmospheric circulating fluidised-bed (CFB) gasification facility using air as a fluidisation agent. In this paper, the effect of experimental conditions on gasification process with the aim of enhancing the gas production and improving its composition and energetic content was analysed. The first tests have demonstrated that the CFB test rig operates adequately and makes it possible to carry out gasification experiments with orujillo as a fuel. The lower heating value of the producer gas obtained is 3.8 MJ/Nm3 at the lowest temperature (780°C). The carbon conversion in orujillo gasification at the 800°C set points was in the range of 81.0–86.9%. The increase in equivalence ratio did not improve carbon conversion significantly. The gas yield increases when equivalence ratio increases.