Gasification of Waste Tyres: Thermodynamic Attainable Region Approach

Abstract:

The innovative G-H graphical technique, a plot of Enthalpy vs Gibbs free energy was utilized to obtain a thermodynamically attainable region (AR) for the gasification of waste tyres. The AR is used to examine the interaction between the competing reactions in a gasifier and used to identify optimal targets for the conversion of waste tyres. The objective is to investigate the effect of temperature on the product selectivity. a temperature range of 25-1500°C at 1 bar was used for the analysis. The results show that at temperatures from 200°C to 600°C methane and carbon dioxide are dominant products at minimum Gibbs free energy. However, as the temperature increases, methane production decreases and hydrogen production become more favourable. Between 600°C and 700°C, carbon dioxide and hydrogen are dominant products. The AR results show that the products of gasification (CO and H₂) are preferred products at minimum Gibbs free energy only at temperatures from 800°C to 1500°C, when both water and oxygen are used as oxidants. Therefore, syngas production from tyres is only feasible at high temperatures. Temperatures above 1000°C are recommended to prevent the formation of intermediate radicals.

• Periodical: Materials Science Forum (Volume 1045)
• Pages: 179-185
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1045.179
• Online since: September 2021
• Authors: Athi Enkosi Mavukwana*, Celestin Sempuga
• Keywords: Attainable Region, Gasification, Gibbs Free Energy, Syngas, Thermodynamics, Waste Tyres

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