Characteristics and prediction model of hydrogen production of oily sludge by supercritical water gasification

Harmless treatment and resource utilization of oily sludge are urgent and related to the sustainable green, and low-carbon development of the petroleum industry. Aiming to the supercritical water gasification (SCWG) of oily sludge for hydrogen production, this paper investigated the effects of critical factors, including reaction temperature, initial pressure, retention time, and feed concentration, on the mole fraction, the gas yield, the gasification efficiency, and the hydrogen yield potential. The interaction mechanisms among these four factors were discussed and revealed with a reasonable prediction model of hydrogen production. Results showed that the longer retention time, higher temperature, and lower feed concentration could accelerate hydrogen production from oily sludge by SCWG. The synthetic promotion of the hydrogen yield exists between the temperature and the retention time, while the temperature predominates. A 2.63-fold increase in the H₂ yield was obtained when the condition changed from 135 min to 380 °C to 10 min and 555 °C. The hydrogen production of oily sludge by SCWG, at lower temperature and higher pressure was worse than that at higher temperature and lower pressure.