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Gasification of solid biomass and intermediate energy carriers to advanced biofuels
An important research component of BECOOL focused on the optimization and integration of thermochemical conversion processes for advanced biofuel and biorefineries. This work had multiple objectives including: • generating experimental gasification performance data for lignocellulosic biomasses at bench scale; • validating the pyrolysis of selected feedstocks at bench and pilot scale for subsequent gasification; • assessing the performance and scale up costs of advanced biofuel value chains using AspenPlus models; • conducting a regulatory framework analysis of the definition and standards for advanced biofuels from gasification. Fig 33 below shows the different steps of the integrated process that was studied and tested. The production of Fischer-Tropsch biofuel via direct entrained flow fluidized bed biomass gasification was the main processing pathway. In addition, both fast pyrolysis and slow pyrolysis were studied as ways to produce intermediate energy carriers for further gasification and production of FT
fuels (gasoline, diesel and kerosene). In the first case, the intermediate carrier was fast pyrolysis bio-oil (FPBO), and in the latter case the carrier was a slurry of char and bio-oil. Two main reasons justified the production of intermediate energy carriers before gasification. First, both slow and fast pyrolysis can provide advantages in solving logistical challenges, enabling a decentralized pretreament of the biomass in modular units, by producing the energy carriers (FBPO or slurry) at local level, before their final gasification and upgrading in a large-scale unit. Both solutions can also provide excess heat for the drying of the biomass, and in the case of slow pyrolysis, biochar is also produced, that can be used as a soil amendment and for soil carbon sequestration. The second advantage is at process level, as both fast and slow pyrolysis can separate the inorganic elements in the biomass that are responsible for ash melting behaviors during the gasification stage. Finally, the use of FBPO simplifies pressurized operation in the gasifiers, avoiding the need for further syngas compression.
Fig 33. Scheme of the integrated thermochemical pathways and activities studied in BECOOL.
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