Char reduction and producer gas quality enrichment of rice husk by co-gasifying tyre waste in downdraft gasifier

Energy conversion systems efficiently utilize vast amounts of energy, but also generate significant waste, necessitating waste minimization to reduce processing costs, improve efficiency, and promote resource conservation. This study aims to decrease char waste generated during rice husk (RH) gasification by using tyre rubber (TR) in co-gasification and to improve gasification quality. Investigations are conducted using various blending ratios (BR) of TR to RH (BR: 0–50 %) and gasifier equivalence ratios (ER) (ER: 0.2–0.4) to examine the impact of TR content on gasifier performance and char yield. The gasification temperature rises from 953 °C to 1129 °C for the addition of TR with RH and provides a better gasification result than an increase in ER. The increase in TR content reduces fuel consumption whereas it is found to increase with the increase in ER. The producer gas (PG) yield increases with an increase in TR content, reaching a maximum of 47.1 Nm³/h for BR50 at 0.4 ER whereas it is 37.9 Nm³/h for RH (BR0). The concentration of the combustible gases H₂ and CH₄ rises when TR is added, but the CH₄ gas exhibits a downward trend after 30 % of TR content. Since there is an optimal concentration of combustible gas for each component at about 0.3 ER, 0.3 ER is determined to be appropriate for co-gasifying TR with RH. The increase in TR reduces the char yield however at the optimum ER of 0.3, 30.6 % of char reduction is observed. More char reduction is discovered in the least ER, though, and this is unsuitable when additional performance parameters are taken into account at lower ER. It is found that the TR content in the feedstock increases the efficiency of carbon and hydrogen conversion. Therefore, adding TR to the gasifier to co-gasify rice husk improves environmental sustainability by increasing performance and reducing char. This also lowers the generation of waste tyres.