Analysis of oil content in drying petroleum sludge of tank bottom

In this paper, the oil content and corresponding components were analyzed in the samples of drying tank bottom petroleum sludges from Sinochem Xingzhong Oil Staging (Zhoushan) Co. Ltd. The composition of the oily sludge was determined by using organic solvent extraction gravimetric method (organic solvent is selected as petroleum ether, benzene, and toluene, respectively) and calcining-gravimetric method. It was found that measurement errors by using petroleum ether extraction gravimetric method and direct weight-loss method were bigger than those errors by using benzene or toluene extraction gravimetric method. During the measurement, it was also found that toluene should be recommended instead of benzene due to its lower toxicity. The measurement results show that water content, oil content and solid content by mass in the sludge were 9.8%, 25.8% (the asphaltene is accounted for 22.7% of the oil content in the sludge) and 64.4%, respectively. Also, chemical composition of the solids in the sludge was analyzed by using organic solvent extraction gravimetric method and XRD structure analysis method, then it was shown that Fe(OH)O·H2O is the main solid component in the sludge.