Assessment of sewage sludge as a component for the tire char co-gasification process

Abstract

The work aimed to assess various sewage sludge (from coking, refinery, and fat-processing plants) as components for tire char co-gasification. The sewage sludge were analysed (basic characteristics, thermal stability, ash characteristics). Then, CO2 gasification and co-gasification measurements of individual materials and their blends (ratio: 70:30, 40:60) were made using the TGA, based on which the process and synergy effect were assessed. Moreover, a detailed analysis of char gasification formed during the pyrolysis was performed (reactivity assessment, kinetic parameters determined using the n-order Coats and Redfern model, and correlation between the individual elements in materials and their reactivity). Co-gasification measurements proved that the addition and increasing sewage sludge share in blends enhanced the process (TG curves were shifted towards lower temperatures, reactivity indicators, and final conversion degrees were improved compared to tire char). The greatest impact on the pyrolysis stage had the sludge from the refinery, while on the gasification stage sewage sludge from coking and fat-processing plants (where the synergy was observed). Moreover, the addition of sewage sludge to tire char reduces the activation energy and, in most cases, the pre-exponential factor. Finally, the correlation between reactivity and the Na, Mg, and P amount in the samples has been proved.