Patent GB-449717-A (GB)
Title: Improvements relating to the treatment of hydrocarbon material with light hydrocarbons
IPC: C10G21/00
Filed: 1935-06-25
Abstract: <PICT:0449717/III/1> In a process of treating heavy hydrocarbon oils with selective solvents consisting of light hydrocarbons below the critical temperature and under pressure sufficient to maintain the solvent liquid, the layers formed are separated and a layer is treated with the light hydrocarbon at a different pressure whereby the density of the solvent is changed and two layers are formed and are separated.  Heavy oil is drawn from a tank 2 into a mixing device 177 to which liquefied propane is admitted from one of the tanks 1. The mixture is then pumped through a heater 17, maintained within 50 to 100 DEG  F. of the critical temperature of propane, to the first of a series of towers 3 . . . 6, maintained at progressively increasing or decreasing stages of pressure, e.g. between 200 and 900 lbs. per sq. in. and provided with heating or cooling coils 7 . . 10. In tower 3, asphalt is precipitated and is drawn off through a line 19.  The propane-oil mixture then passes through a reducing valve 200 to the tower 4 at a lower pressure, or through a byepass pump 22 if the tower 4 is at a p  higher pressure.  Two layers are formed and the upper layer is drawn off into the next tower 5.  The final upper layer from tower 6 passes to a separator 32 provided with a heating coil 33 maintained at the critical conditions of propane whereby propane separates from the oil and passes to the supply tanks under pressure.  The resulting oil containing a small amount of propane is removed through a line 34 and freed from solvent by distillation. The bottom layers withdrawn from the towers 4, 5 and 6 may be treated similarly at different pressures or recycled through the respective preceding towers.  In a modification, a single tower is used in which the changes of pressure are effected consecutively and the lower layer is withdrawn at each stage. Heavy oils specified are: gas oil, lubricating, gear, and transmission oils obtained as distillates or as residues from natural oils, or destructive distillation, cracking or hydrogenation products of coal, tar, pitch, resins, lignite, bitumen, shale or petroleum, polymerization or condensation hydrocarbons or voltolized oils.  Light hydrocarbon solvents specified are: aliphatic hydrocarbons containing 1 to 8 carbon atoms and ethylenic hydrocarbons containing 2 to 8 carbon atoms or mixtures thereof such as from the hydrogenation hydrocarbons or debutanisation of gasolines; or light naphtha, or gasoline either of natural or cracked origin.  These light hydrocarbons may be mixed with napthenic solvents such as phenol, cresol, cresylic acid, xylol, liquid sulphur dioxide, aniline, chlor-aniline, nitro phenols, nitro benzene, furfurol, croton aldehyde, dichlor ethyl ether, glycol diacetate, or phenolic substances containing small amounts of water, caustic soda or potash, alcohols, glycerine or ammonia.  The oils before or after treatment may be dewaxed or deasphaltized, and after treatment may also be treated with acid or clay or may be hydrogenated, cracked, polymerized or voltolized.  The Specification as open to inspection under Sect. 91 describes also the treatment at temperatures above the critical temperature of the solvent.  This subject-matter does not appear in the Specification as accepted.