Patent GB-794350-A (GB)
Title: Drying of adsorbent solids
IPC: B01D15/02
Filed: 1955-04-13
Abstract: <PICT:0794350/III/1> In a process for treating mineral oils with a granular adsorbent solid to remove impurities therefrom, the spent adsorbent is dried to remove vaporizable constituents and then regenerated by burning off the carbonaceous contaminants at elevated temperature.  The adsorbent is transferred from the drying to the regeneration zone without escape of vapours from the drying zone with the adsorbent, by passing the dried adsorbent downwardly from the drying zone into a chamber, withdrawing adsorbent from this chamber at a rate above the rate of flow into the chamber and conveying it upwardly to a supply zone, from where a portion of the adsorbent passes to the regeneration zone and the remainder is recycled to the chamber.  Details of the drying zone are given (see Group XIII). Adsorbents referred to are fuller's earth, bauxite, bentonite, bone char, charcoal, magnesium silicate, heat and acid activated kaolin and activated carbon.  The size of the adsorbent particles should be 4-100 mesh (Tyler).  The treatment of fuel oil and of lubricating oil is referred to.  In Fig. 1, absorbent passes from hopper 14 through distributer 15 and via conduits 17 into and through treating zone 12. Oil passes to heater 10 via conduti 11 and thence to the lower section of zone 12 and upwardly through the adsorbent and is removed by conduit 66.  Used adsorbent passes through conduits 18 to collector 19 and then into washing zone 21 in which any oil is removed from the adsorbent by countercurrent contacting with a solvent, such as petroleum naphtha of boiling range 100-400 DEG  F., carbon tetrachloride, n-heptane, N-octane and carbon disulphide, introduced through line 22.  Used solvent containing dissolved oil is passed to fractionator 24 by line 23 and regenerated solvent returned to the washing zone by line 25.  The adsorbent is passed by line 31 to draining zone 30 from which solvent is recycled via solvent accumulator 33 to washing zone 21.  Adsorbent is then passed via line 37 to drying zone 38 wherein it is freed from vaporizable constituents by heating; inert gas, e.g. steam or flue gas, is admitted to the lower section of the drier to fluidize and strip the adsorbent.  Gas and solvent pass through condenser 44 and separator 43 and solvent passes to accumulator 33.  Dried adsorbent passes from drying zone 38 through conduits 46 and 47 to combining chamber 48 and passes from the lower section of the chambar by passage 49 at a rate greater than the rate of entry through line 47, to an elevating means 50 by which adsorbent is elevated to supply hopper 52.  One stream of adsorbent is passed to regeneration zone 57 wherein non-vaporizable carbonaceous impurities are burnt with an oxygen-containing gas, e.g. air, admitted through line 58; the remainder is recycled via passage 53, surge pot 54 and line 55 to combining zone 48 to make up the difference in flow through passages 49 and 47.  Regenerated adsorbent is cooled by cooler 62 and passed by elevator 64 to hopper 14 and hence to treating zone 12.  Details of the sealing system for the drier, to prevent gaseous material being transferred from the combining chamber 48 to the elevator 50 through line 49, are given. Specification 711,487 is referred to.