Treatment of oily waste using a scaled-up carbonization kiln

Treatment of oily wastes generated in production and refining processes is one of the major environmental issues facing the petroleum industry in oil producing countries. In this study, carbonization treatment (pyrolysis) using superheated steam, without any catalyst, was investigated to remove oil from waste. A carbonization kiln was scaled up by a factor of 100 and used to treat oily waste while utilizing off-gas combustion. Initial oil concentration in waste material ranged from 57,700 to 881,000 mg/kg-dry, and oil removal rates exceeded 99.97% by carbonization at 600 °C with superheated steam. Weight reduction rate of the oily waste was 8.9-95.0%, with higher ratios of initial water and organic matter resulting in higher weight reduction rates. Oil recovery rate increased with higher oil load, whereas heating time and fuel consumption per unit oil load decreased. However, excessive oil load relative to the scale of the kiln caused decreased oil recovery rate and increased off-gas generation, resulting in difficult control of off-gas combustion. The scaled-up kiln achieved oil removal performance equal to or superior to smaller experiments. The oil load of the waste material was a key parameter for both oil recovery and processing efficiencies related to heating time and fuel. Appropriate oil loads should be identified based on prioritization of such operational factors.