Patent GB-896294-A (GB)
Title: Treatment of hydrocarbons
Inventor: SLYNGSTAD CHARLES EDWARD
IPC: C10G47/00
Filed: 1960-09-14
Abstract: Dissimilar hydrocarbon feed materials of different A.P.I gravity are catalytically desulphurized in a reaction zone containing a plurality of catalyst beds by a process in which a relatively lower A.P.I. gravity material from a cracking process is mixed with a hydrogen-rich gas and passed through all the catalyst beds contained within the reaction zone, after which the purified lower A.P.I. gravity feed is recovered, and the flow of lower A.P.I. gravity material then discontinued after which a relatively higher A.P.I. gravity material is passed together with hydrogen-rich gas through only some of the catalyst beds while the hydrogen-rich gas <PICT:0896294/III/1> continues to pass through all the catalyst beds, and the purified higher A.P.I. gravity material then recovered.  In the preferred embodiment shown, a cycle oil feed (A.P.I. gravity 27) is supplied by line 2 to heat exchanger 6, where it is heated, and passes thence by line 8 to a second heat exchanger 10 before passing by line 12 to furnace 14 where it it heated to 740 DEG -800 DEG F. The heated feed then passes by line 16 (valve 104 being open and valve 108 in line 106 being closed) to reactor 18 together with hydrogen-rich gas at 600 DEG F. supplied by line 20, which has been introduced by line 100, heat exchanger 40, line 102, and heat exchanger 26.  Reactor 18 contains three catalyst beds, the upper two beds containing equal amounts of catalyst and the lowest bed containing an amount equal to the total amount contained in the other two.  On leaving reactor 18 by line 22, the mixture is split into two streams, one stream passing to separation drum 34 by line 24, heat exchanger 26, line 28, heat exchanger 30 and line 32, and the other stream reaching drum 34 by line 36, heat exchanger 10 line 38 and line 32.  Drum 34 is maintained under high pressure at about 450 DEG F. and a gaseous stream is withdrawn therefrom by line 39, heat exchanger 40, line 41, cooler 42 and line 44 to separation drum 46 which is also maintained under much the same pressure but at about 125 DEG F.  A gaseous stream leaves drum 46 by line 48 and is treated, e.g. in an amine scrubber (not shown), to remove H2S, the purified hydrogen-rich gas being then returned to the process. Liquid streams are withdrawn from drums 34 and 46 by lines 50 and 54; line 54 leads the liquid stream to heat exchanger 30, whence it passes by line 56, together with line 50 to steam stripper 52.  Steam at 450 DEG F. under pressure enters at 58 and unstabilized gasoline and gaseous material leaves by line 60, passes through cooler 62 to separating drum 66, whence gaseous product is removed by line 76 and a liquid stream leaves by line 68, some being refluxed to stripper 52 by line 72 and the rest withdrawn through 74.  A liquid stream leaves stripper 52 by line 80, and passes to heat exchanger 6 (which may be by-passed) and by line 82, and cooler 84, lines 86 and 90 to salt drier 94, whence the product may be drawn off through line 88; alternatively the salt drier 94 may be by-passed and product drawn off through line 92.  Following the treatment of cycle oil as just described, valve 104 in line 16 is closed and valve 108 in line 106 is opened, and stove oil (A.P.I. gravity 42) introduced through line 2.  This is treated in the same way as the cycle oil, except that on leaving furnace 14 it enters reactor 18 through line 106 and so passes through only the lowermost catalyst bed.  In general, suitable desulphurization conditions are temperatures of 550 DEG -1000 DEG F., pressures of 25-2,000 p.s.i.g. weight space velocities of 0,05-20 w/hr/w and a hydrogen feed of 300-20,000 S.C.F./Bbl.  Suitable desulphurization catalysts are chromia, molybdenum trioxide, nickel or cobalt molybdate on alumina, nickel tungstate on alumina, nickel-cobalt molybdate, platinum and/or palladium on alumina, and such heteropoly acids as phosphomolybdic and phosphotungstic acids, either alone or supported on, for example, silica-alumina.  Oils which may be treated include gasoline, naphtha, kerosene, gas oil, cycle oils from catalytic or thermal cracking, residual oils, thermal and coker distillates, stove oils, and diesel fuels, and the hydrocarbons may be treated in a liquid, vapour or mixed liquid-vapour state.  The hydrogen-rich gas is suitably that obtained in a reforming process, and reaction with the feed may be carried out either co-currently (as shown) or in counter-current.