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Talk:Directory:Biomass
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Discussion page for Directory:Biomass
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Bubbling fluidized bed for pyrolysis oil production
Comments concerning limitiations to use of a bubbling fluidized bed for pyrolysis oil production.
A bubbling fluidized bed (BFB) system as Dynamotive uses requires very small particles in the size range of 1 to 2 mm as a feed stock since only very small char particles are small and light enough to leave the bubbling bed. Larger size particles would accumulate in the bed and absorb tars that are being formed lowering the yield of primary product.
As biomass is normally obtained with a high moisture content, it must be first dried and crushed first before being ground down to this size. This grinding consumes much more electricity than normal crushing and increases the operating costs for the plant.
A BFB system for pyrolysis liquid production normally has heat transferred into the bed by heat pipes which are heated with natural gas. The surfaces of these pipes must be very hot in order to get the bed temperature up to 500 C. These heat pipes will be so hot that the ash in the feed will deposit on the pipes forming an insulating layer. This will have to be periodically removed
These limitations cause the Dynamotve system to have high costs for fuel production.
--SeveriG 02:36, 6 October 2008 (PDT)
