Tar abatement for clean syngas production during biomass gasification in a dual fluidized bed

• Biomass syngas cleaning with catalytic filter candles was tested.
• The tests were carried out with biomass tar produced in situ.
• Fixed bed and catalytic layer configurations were compared.
• The catalytically active layer design was the most effective.
• Tar contents as low as 0.2 g/Nm3 (N2 free, d.b.) were reached.

Syngas obtained from biomass gasification needs to fulfil strong purity requirements before being used as raw material in power energy generation or chemicals manufacturing. The use of hot catalytic filter candles inside the freeboard of fluidized bed gasifiers allows obtaining clean syngas without dust and low tar content. The tar removal efficiency of four different catalytic filter designs was evaluated with real biomass tar produced in situ in a dual fluidized bed gasifier (DFBG). The tar conversion reached at the outlet of the fluidized bed gasifier was larger for the candles with catalytically active layer design. If a monolith is also incorporated, the tar conversion increases up to 95% which is one of the highest values obtained up to date. In this case, the tar content at the outlet of the catalytic filter was as low as 0.2 g/Nm3 (N2 free, d.b.).

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