International Journal of Waste Resources

Abstract

High Quality Oil Recovery from Oil Sludge Employing a Pyrolysis Process with Oil Sludge Ash Catalyst

Shuo Cheng, Aimin Li and Kunio Yoshikawa

In this study, pyrolysis experiments of two kinds of oil sludge were conducted using a bench-scale fixed bed reactor, which is mainly consisted of a pyrolyzer and a reformer reactor. The effects of the pyrolysis method and the catalysts on the yield and quality of oil products obtained from pyrolysis of oil sludge were investigated. Characterization of the oil products was preliminary judged by comparing their distillation results with the diesel standard and the oil product without catalyst usage. Then, the chemical characterization of a part of the pyrolytic oil was conducted by FT-IR and NMR analysis. In the last step of these experiments, the oil products obtained from pyrolysis of oil sludge with the use of oil field sludge ash and oil tank sludge ash as catalysts were mixed with diesel oil by the volume ratio of one-to-five and one-to-ten. The fuel characteristic of the oil mixtures was identified from the point of the viscosity, the density, the cetane index, the carbon number distribution and the higher heating value (HHV). The results of experiment show that the highest oil product yield was obtained at the one-stage pyrolysis of the oil field sludge and also the oil tank sludge with the oil field sludge ash as the catalyst. According to the results of NMR analysis, the main part of the carbon in the oil product from pyrolysis of the oil sludge with the oil sludge ash was aliphatic carbon. The total ring number of oil products decreased owing to the hydrogenation and ring-open of naphthenic hydrocarbon during the catalytic pyrolysis process. The highest HHV and the cetane index could be obtained when the oil product from the one-stage pyrolysis process of the oil field sludge with the oil field sludge ash was mixed with diesel by the mixing ratio of 1: 10. The results of this study are of practical interest and will help to lead the researchers to more thinking about the oil recovery from oil sludge.