Experimental modelling of tar destruction with addition of CO2 for application in the biomass gasification system

• The tar destruction with CO2 addition over activated waste tyre char was examined.
• Different reaction factors affecting activity of tar destruction were evaluated.
• The study revealed inhibition of tar conversion with an increased CO2 supply.
• At 900 °C, tar conversion was equal to 96.2%.

This paper extends prior analysis of biomass tar destruction over a bed of activated waste tyre char using different thermal processes (steam reforming, partial oxidation and thermal cracking) with special attention on the addition of carbon dioxide to the tar destruction process and to the composition of the producer gas. The effects of the reaction temperature, the initial concentration of CO2 in producer gas and the time of the run on char bed activity were evaluated. The investigation revealed that the addition of carbon dioxide demonstrates the least influence on tar destruction in comparison with the other thermochemical processes. At 900 °C, tar conversion was obtained at a rate of 96.2%. Increasing the CO2 from 10.8 vol. % to approximately 29 vol. % led to an increase in the CO yield while a steady CO2 conversion rate of approximately 50% was maintained. From an energetic point of view, the addition of carbon dioxide is valuable and led to an increase in calorific value; however, for tar treatment, it is desirable to use a more reactive oxidiser as the steam.