From theoritical and experimental aspects

a study of residual carbon sedimentation features in residuum oil has been carried out. The result of study shows that the features of residual carbon sedimentation have relation both with: （1） the particle size and density distribution of the residual carbon proper; and （2） the temperature

viscosity and density of the residuum oil. The sedimentation of residual carbon can be retarded by decreasing storage temperature of the residuum oil. When the density of residual carbon and the density of residuum oil are almost identical

the sedimentation of residual carbon can not occur. Hence

the storing and heating temperature of non-stable residuum oil should appropriately be controlled.