5. Oily sludge disposal methodsIn addition to oil recovery, a number of technologies areavailable for the disposal of oily sludge, including incineration, stabilization/solidification,oxidation, and biodegradation.5.1. IncinerationIncineration is a process of complete combustion of oily wastesin the presence of excess air and auxiliary fuels, and it is widelyadopted in large refineries for sludge treatment. Rotary kiln and fluidizedbed incinerator are the most commonly used incinerators. Inrotary kiln incinerator, the combustion temperature is in the rangeof 980–1200 ◦C and the residence time is around 30 min. In fluidizedbed incinerator, the combustion temperature can be in therange of 730–760 ◦C, and the residence time can be in order of days[163]. Fluidizedbedincinerator is especially effective whentreatinglow-quality sludge due to its fuel flexibility, high mixing efficiency,high combustion efficiency and relatively low pollutant emissions[164]. The incineration performance can be affected by a variety offactors, including combustion condition, residence time, temperature,feedstock quality, presence of auxiliary fuels, and waste feedrates. Liu et al. [165] investigated the incineration of oily sludgeby the addition of an auxiliary fuel consisting of coal–water slurry(CSW) in a fluidized bed boiler, and they found that the temperatureof combustion could be stabilized by controlling the CSWfeeding rate, with a combustion efficiency of 92.6% being reached.
They also found that the gaseous emission from incineration and
heavy metals in ash residues could meet the corresponding environmental
regulations.Wang et al.[166] examined the incineration
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