Assessment of the energy recovery potential of oil sludge through gasification aiming electricity generation

Abstract

Thermochemical conversion of oil sludge (OS) residues from crude oil refinery was studied as an alternative for treatment and energy recovery before OS final disposal. A simulation model for OS gasification was developed and validated by using AspenPlus™ V 11.0. Three scenarios by considering different gasifying agents were evaluated, aiming the assessment of different gasification parameters and performance indexes such as gasification temperature, cold-gas efficiency, syngas yield, and LHV. To evaluate the potential use of syngas to generate electricity, three different prime movers such as steam Rankine cycle, gas microturbine, and gas-Internal Combustion Engine (ICE) were modeled. A hydrogen-rich syngas from OS gasification with air/steam mixture was reached (38.2 vol%) at ER 0.20. Syngas LHV and syngas yield ranged between 8.6 and 3.0 MJ/Nm3 and 0.6–1.3 Nm3/kg OS, when ER was increased from 0.25 to 0.45, respectively. The highest energy recovery potential (electricity generation) was obtained when using syngas to power a gas-ICE, with a generation index of about 0.47 kWh/kg-OS at ER ratio of 0.25. Therefore, OS thermochemical conversion into syngas and its subsequent use to generate electricity could be a technological alternative to oily residues management inside an oil refinery that could efficiently transform a dangerous residue into electricity.