To recover fuel oil from oily sludge, experimental studies were performed using a fluidized sand bed pyrolyzer. The heat energy for the pyrolysis of sludge was supplied from the heat of a partial combustion of sludge. It was revealed that the yield of recovered oil decreased with increasing bed temperature within the range of from 500 to 600°C. The viscosity of recovered oil decreased with the increase of the oxygen concentration in fluidized gas. The properties of the recovered oil ranked with those of the fuel oil. Moreover, the sulfur content in recovered oil was reduced to 70%, as compared with that in sludge. When lime-Stone or natural zeolite were used as the fluidized particles, relatively low viscous oil could be produced, but its yield value was small compared with the use of silica sand. The estimated value of heat con-sumption for pyrolysis was ranged from 390 to 530 kcal/kg.
