CFD Modelling of Heat Supply in Fluidized Bed Fast Pyrolysis of Biomass

• This paper investigates the heat supply to the fast pyrolysis process, by addition of oxygen in the fluidizing gas. Since the technology will be further developed, a solution for the heat supply in a large-scale reactor must be conceived, which is one option to achieve the primary target: to operate with as little extra heat as possible.Corrections for the granular bed material and the biomass particles are implemented in the simulation. User Defined Functions (UDF) is extensively used to describe interactions of heat and momentum between the phases and a chemistry model is employed to describe the chemical reactions after pyrolysis.The results are preliminary; however, the oxygen clearly reacts to provide heat. Primarily the secondary tar reacts and a loss of about 30% organic liquid yield is the result in this simulation, at an equivalence ratio of 0.026.If heat only can be recovered from the bed zone, through the bed material, then a higher equivalence ratio than what was investigated in this paper would be needed.If heat can be recovered from the whole reactor then a slight injection of oxygen would result in an autothermal system; which means the necessary heat to generate and pre-heat steam would be available.Temperature instability in the freeboard prevented investigation of higher equivalence ratios, which should be pursued in further work.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik -- Kemiska processer (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering -- Chemical Process Engineering (hsv//eng)

Nyckelord

CFD

fast pyrolysis

pyrolysis oil

Energy Technology

Energiteknik

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