Prediction and optimization of hydrogen-rich gas production from sewage sludge via a combined process of hydrothermal carbonization, pyrolysis, and reforming

Aiming at the sustainable management of sewage sludge (SS), an alternative process combining with hydro-thermal carbonization (HTC), pyrolysis, and steam reforming was proposed in this study for SS to energy/fuels. Models were developed by multiple linear regression, Merrick correlations and kinetics for assessing its potential of hydrogen-rich gas production. A good agreement was found between the simulation results by these proposed models and experimental data. The sensitivity analysis shows that HTC could improve the H2 fraction and decreased the tar concentration in the gas significantly. The integration of steam reforming facilitated the pro-duction of H2 and CO along with the significant decrement of tar concentration. The optimal H2 fraction of 61.16 vol%, lower heating value (LHV) of 14.34 MJ/Nm3, gas yield of 1.42 Nm3/kg and tar concentration of 0.28 g/ Nm3 in the gas could be achieved by the proposed process, respectively. This work provides an alternative way for SS to energy/fuels.