Study on Catalytic Combustion of Biomass Mixtures with Poor Coals

Abstract

The effect of catalyst addition on ignition and combustion characteristics of biomass fuels from the Mediterranean region, one lignite and lignite/biomass blends, were investigated. Transition metal oxides and alkali/alkaline earth compounds were used as catalysts. The experiments were conducted in a thermogravimetric analysis system. The performance of the process was evaluated in terms of combustion rate, ignition, and combustion indices. The results showed that metal oxides enhanced the ignition and combustion performance of lignite, showed no catalytic activity to burn off of biomass fuels, but influenced the temperature sensitivity of their reaction in air. The relative activity was in the following order: V₂O₅>Fe₂O₃>CaO>NaCl>MgO>CuO>TiO₂>LiCl. The combustion characteristics of the blends followed those of parent fuels in an additive manner. Blending lignite with biomass fuels increased its thermochemical reactivity. In terms of burnout, catalyzed combustion of blends was further improved.

Keywords:

• Biomass
• Blends
• Catalysts
• Combustion
• Lignite

ACKNOWLEDGMENT

The authors kindly thank the laboratories of Inorganic and Organic Geochemistry and Toxic and Hazardous Waste Management of the Technical University of Crete for the chemical analysis of the fuels.

Notes

HHV: higher heating value; OL: olive tree pruning; CAR: cardoon; SS: sewage sludge; MLIG: Mavropigi lignite.

OL: olive tree pruning; CAR: cardoon; SS: sewage sludge; MLIG: Mavropigi lignite.

Values in brackets show weighted average values. OL: olive tree pruning; CAR: cardoon; SS: sewage sludge; MLIG: Mavropigi lignite.

Maximum temperature obtained during second stage. MLIG: Mavropigi lignite.

MLIG: Mavropigi lignite.

OL: olive tree pruning; CAR: cardoon; SS: sewage sludge.

OL: olive tree pruning; CAR: cardoon; SS: sewage sludge; MLIG: Mavropigi lignite.

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