Energetic and environmental assessment of oil sludge use in a gasifier/gas microturbine system

Abstract

An energetic and environmental assessment of producer gas production from oil sludge (OS) gasification and an analysis of its potential use for electricity generation has been performed. A computational model of OS gasification was developed and two gasification agent (oxygen and air/steam mixture) cases were analyzed. To determine the energy recovery potential of OS, a computational model involving a gas microturbine powered with the producer gas from OS gasification was developed. Results showed that oxygen gasification produced a gas LHV (11.1–7.2 MJ/Nm3) higher than air/steam gasification (9.9–3.8 MJ/Nm3). These differences influenced the microturbine electricity generation index values, which ranged from 0.423 to 0.407 kWh/kg-OS with oxygen, and from 0.42 to 0.393 kWh/kg-OS, using air/steam mixtures. For environmental impacts estimation of gasification/gas-microturbine integration, eight environmental impact categories were assessed by using the Life Cycle Assessment methodology. Among these, oxygen gasification showed higher reductions in comparison to air/steam gasification, in the non-renewable energy (77%), respiratory organics (85%), and carcinogens (85%) categories. When energy recovery from syngas was considered, both cases have a lower carbon footprint (379–569 kg CO2-eq/ton OS) than incineration process (1045 kg CO2-eq/ton OS), which indicates that gasification system is an environmentally attractive option for OS treatment.