Synergistic Effects of the Co-gasification of Solid Recovered Fuel and Coal Blend Using Entrained Flow Technology

Co-gasification of solid recovered fuel (SRF) with coal can be used as a potential mitigation strategy for the increasing landfilling of these wastes. However, the varying composition and proportions of SRF can hinder gasification performance by reducing energy content, introducing contaminants, and inconsistent feedstock. Hence, the gasification of this feedstock mixture requires detailed evaluation to obtain enhanced operation. Here, two levels of modeling are pursued for the gasification of coal and SRF mixture, the plug flow equilibrium-based model (EM) and the continuous high-fidelity reactive flow model (RFM). Using EM, different coal-SRF mixtures are considered assuming the gasification is conducted in entrained-flow-gasifier technology. The result shows that the maximum attained gasification efficiency is 82.54% at 1250 °C for 80% coal + 20% SRF mixture. Moreover, the syngas molar fractions were X_CO = 0.57 and X_H2 = 0.39. Owing to the higher volatility of the considered SRF composition, the coal-waste gasification performance metrics surpass that of standalone coal gasification (76.4% at 1150 °C and X_CO = 0.63 and X_H2 = 0.30). Furthermore, the high-fidelity model considers the reactor shape and the inferred devolatilization kinetics from TGA data. The numerical model shows that gasification reactions are not instantaneous as the low-fidelity models suggest. The high-fidelity model results demonstrate that the maximum gasification efficiency (GE) is obtained when all of the solid carbon is transformed into carbon monoxide and nearly all of the hydrogen contained in the feedstock is turned into hydrogen gas. At 1,200 °C, the maximum conversion was achieved using SRF and Coal in the proportion of 30% SRF-Coal mixture. The obtained mole fractions of the syngas species are X_H2 = 0.159 and X_CO = 0.545. Furthermore, the CGE for coal only is 73.6% for the H₂ and CO syngas species and 70.3% for the 30% SRF. At temperatures above 950 °C, the gasification of SRF and coal at 30:70 is economically viable. Around midway of the drop tube reactor, asymptotic and constant species formation with an increasing temperature trend toward the center were evident. Low (≤ 1,000 °C) and high (1,550 °C) temperatures result in low metrics due to small syngas yield, and excess heat & oxidizer, respectively. Overall, the co-gasification of Coal and SRF mixtures could provide a viable energy source and a potential solution for the growing landfill footprint.