Process and apparatus for clay contacting in the refining of lubricating oil

Mineral lubricating oils, vegetable oils, fatty acids and petroleum waxes in the liquid phase, or other liquids, are purified by contact with a comminuted solid refining agent which flows uniformly to the contact zone by gas pressure, uniform flow being ensured by establishing a column of the refining agent of uniform height, introducing a gas into the column to fluidize the refining agent therein, discharging refining agent from a lower part of the column into a transfer line and discharging refining agent from the transfer line into the contact zone by injecting gas into the transfer line. The refining agent may be aluminum chloride a catalytic agent, a filtering agent or a clay such as Fuller's earth, bauxite, the treated montmorillonite known under the Registered Trade Mark "Filtrol." or a hydrous aluminium silicate. Inert gas, steam or air may be employed for transporting the refining agent. In the Figure, which shows apparatus for the decolorization of mineral lubricating oil by clay-contacting, clay entering discharge leg 26 from storage bin 34 is fluidized by gas from line 32 and constantly discharged through line 28 into head tank 30. Return line 44 takes the clay overflow from head tank 30 back to storage bin 24 thereby establishing a constant head of clay in leg 36. Gas introduced into the bottom of leg 36 at 38 discharges the clay through transfer line 40 into contact tank 10. Lubricating oil from reservoir 50 is fed by pump 51, through heat exchanger 52 and fired heater 53, and then via line 12 into contact tank 10. The mixture of oil and clay leaves contact 10 and passes through line 74 to continuous filter 76. Oil from filter 76 passes to tank 78 and then through sweetening tower 80, to which steam is admitted at 81, and through dry vacuum brightening tower 82. Thence the oil passes through polishing filter 84 to storage 86. Spent clay is discharged from the filter 76 at 77. Filter 76 operates under a blanket of gas, and both the gas for the filter and for the clay transfer comes from gas holder 100, to which it is returned after purification.