# Study of the Applicability of Thermochemical Processes for Solid Recovered Fuel
## 3 Results
### SRF Gasification Trials
#### 3.1.2 Gas Composition  
Table 3 displays the gasification gas composition for each of the conducted tests. In previous studies, the primary gases generated by gasification processes applied to biomass are H\({}_{2}\), CO, CO\({}_{2}\), and CH\({}_{4}\)[44]. However, for this SRF, the H\({}_{2}\) concentration detected accounted for only 7.9 vol% (Test #1) and 6.8 vol% (Test #2). Although a higher H\({}_{2}\) concen  
\begin{table}
\begin{tabular}{c c c} \hline
**Test Number** & **1** & **2** \\ \hline Experiment code & T800\_S/CO\_ER29.6 & T800\_S/C1\_ER37.7 \\ Mass balance (\%) & 90.7 & 96.3 \\ Moisture of the input SRF stream to & 0 & 33.7 \\ gasification (wt\%) & & \\ \hline \multicolumn{3}{c}{Product distribution (wt\%)} \\ \hline Solid yield & 21.9 & 12.2 \\ Liquid yield & 21.6 & 75 \\ Tar yield & 3.6 & 1.4 \\ Gas yield (N\({}_{2}\)-free basis) & 130.4 & 100.7 \\ \hline \multicolumn{3}{c}{Gas composition (vol\%, dry basis)} \\ \hline H\({}_{2}\) & 7.9 & 6.8 \\ CO & 9.0 & 4.1 \\ CO\({}_{2}\) & 13.3 & 17.8 \\ CH\({}_{4}\) & 3.1 & 2.0 \\ C\({}_{2}\)H\({}_{6}\) & 0.2 & 0.1 \\ C\({}_{2}\)H\({}_{4}\) & 2.0 & 1.5 \\ H\({}_{2}\)S & 0.02 & 0.11 \\ N\({}_{2}\) & 6 tration in the gas could be expected with increasing presence of steam in the gasification medium (primary water-gas reaction, secondary water-gas reaction, WGS reaction), the parallel increase in ER could be the cause of this lower production by promoting combustion reactions (including H\({}_{2}\) combustion) as well as the dilution of the gas components due to the higher presence of N\({}_{2}\). These H\({}_{2}\) content values were very similar to those obtained by previous studies of gasification of SRF obtained from municipal solid waste. Specifically, for a temperature of 800 \({}^{\circ}\)C and an S/C ratio of 0.85, a range of H\({}_{2}\) concentrations between 5.8 and 11.2 vol\(\%\) were achieved by [PERSON] [30].  
CO presented significant differences in both tests, with values ranging from 4.1 vol\(\%\) (test #2) to 9.0 vol\(\%\) (test #1). Other studies previously conducted under similar conditions [30; 32; 45] are consistent with the value of 9.0 vol\(\%\); however, the value of 4.1 vol\(\%\) is substantially lower than the lowest value found in literature of 6.8 vol\(\%\)[46].  
Finally, the CO\({}_{2}\) content was the highest among all gases in the two tests (with the exception of N\({}_{2}\)), reaching 17.8 vol\(\%\) for Test #2 and 13.3 vol\(\%\) (test #1), which shows a clear improvement in the combustion reactions. Unlike CO, in the case of CO\({}_{2}\), values similar to those compiled in the literature (11.66 and 15.69 vol\(\%\)) were obtained during Test #2 [46]. The CH\({}_{4}\) concentration decreased from 3.1 vol\(\%\) in Test #1 to 2.0 vol\(\%\) in Test #2, obtaining in both cases values similar to those reported in the literature [32; 41]. Due to the use of steam in test #2, the H\({}_{2}\)/CO ratio presented a higher value (1.66), close to the value of 2, which is optimal for its use as syngas. However, the tar concentration was very high for any synthesis application or even for the combustion of this gas stream in a gas turbine or an engine, with direct combustion in a boiler being the most suitable application, avoiding in this way the condensation of the tar compounds.