Gasification of high moisture rubber woodchip with rubber waste in a bubbling fluidized bed

This study investigated co-gasification of high moisture rubber woodchip (RW) with shredded rubber waste (SR) as an alternative to pre-drying of woodchip and effective utilisation of wastes. The shredded rubber waste was added into the rubber woodchip having originally 27% moisture content at 10 and 20 wt.% based on the dry weight of rubber woodchip. The mixtures were gasified with air in the 100 kWth bubbling fluidized bed gasifier at various equivalence ratios (ER). Operated at the same ER, the SR addition was found to raise the gasification temperature, e.g. an increase from 700 degrees C without SR addition by similar to 70 degrees C with 20% SR addition. The heating value of synthesis gas generally increased with increasing % SR addition and with decreasing ER. Due to the resulting higher gasification temperature obtained from gasification with SR addition, it is possible to operate gasification at lower ER compared to the case without SR addition leading to the higher CO/CO2 production ratio. Both ER and SR addition gave a positive effect on the carbon conversion efficiency: while the gasification efficiency was more influenced by the fuel chemistry. The amount and heating value of fly ash were slightly decreased in all mixtures with increasing ER, while increasing the SR addition ratio resulted in the higher fly ash due to the high ash originally present in the rubber waste. Overall, the performance and products from co-gasification were significantly improved compared to those from gasification using the high moisture woodchip alone and almost as good as that obtained when using low moisture woodchip. This implies the direct usability of high moisture rubber woodchip by adding shredded rubber waste without the need of pre-drying and moreover an improvement of the gasification performance and products. (C) 2010 Elsevier B.V. All rights reserved.