The fry-drying method was used to dry oily sludge from Liaohe oilfield

and spent lubricating oil of vehicle(SLOV)was used as frying medium.The permeation process of SLOV in the oily sludge sample during the fry-drying process was studied.The effects of oil temperature

size and initial moisture content of oily sludge sample on the change of its oil and water contents were also investigated.At the initial stage of the fry-drying process

SLOV entered the interface with oily sludge sample

and then permeated into oily sludge sample gradually.During the whole fry-drying process

the oil content change of oily sludge could be divided into three periods

i.e.decreasing period

increasing period and essentially constant period.Most of the oil uptake was sucked by oily sludge sample during the increasing period.The temperature of frying SLOV and size of sample affected the oil content of oily sludge sample during the fry-drying process

but the effect on final oil content of oily sludge sample was not obvious.The final oil content of oily sludge sample was affected greatly by initial moisture content of the sample.Therefore

pre-drying would be a useful method to reduce the amount of oil uptake by oily sludge.