US2700637A - Process for the removal of asphaltic constituents from residual oils - Google Patents

Description

Jan. 25, 1955` w. T. KNox, JR 2,790,637

PROCESS FOR THE REMOVAL OF' ASPHALTIC coNsTITUENTs FROM RESIDUAL oILs IFiled Nov. so, 1951 Guss LT; NAPHTHA 5c A' 155 i5 l Hw NAPHTHA :FEED 5 GAS ou. l

55 PQop/.ws 53 'mixture 'is removed overhead from United States Patent() PROCESS FOR THE REMOVAL OF ASPHALTIC CONSTITUENTS FROM RESIDUAL OILS Application November 30, 1951, Serial No. 259,141 3 Claims. (Cl. 196-14.11)

The present invention is concerned with an improved process for the removal of asphaltic constituents from residual oils whereby higher quality lubricating oils and fuel oils are obtained. The present invention is particularly concerned with an improved process for the preparation of satisfactory feed stocks for uid cracking operations, whereby higher quality hydrocarbon products boiling in the gasoline and heating oil boiling ranges are obtained by an efficient operation. In accordance with the present invention, a residual oil is combinedv with a high boiling cycle oil secured from a catalytic cracking operation. Asphaltic constituents are then removed from the mixture and the resulting deasphalted product utilized as a high quality lube oil, as a high quality fuel, or utilized in a catalytic cracking operation.

It is well known in the art to treat mineral oils by various processes in order to remove undesirable high boiling and asphaltic constituents from these oils. For example, it is known to employ light hydrocarbon solvents, as for example, hydrocarbons such as propane and butane, in order to remove undesirable constituents, such as, asphaltic constituents therefrom. In these operations various temperatures and pressures are employed, as well as various solvent to oil ratios. It is also known in the art to use various other processes for the removal of carbon, and ash-forming constituents therefrom in order to prepare high quality lube and fuel oils. Other processes have also generally been directed toward the preparation of satisfactory high boiling feed stocks for a uid catalytic cracking operation.

It has now been discovered that undesirable high boiling constituents may be eliiciently removed from feed stocks boiling in the reduced crude boiling range, providing the reduced crude or residual oil is mixed with a cycle oil product segregated from a fluid catalytic cracking operation and treated with a deasphalting solvent, as for example, propane. The process of the present invention may be readily understood by reference to the drawing illustrating one embodiment of the same.

Referring specically to the drawing, a feed oil,'as for example, a West Texas crude, is introduced into distillation zone 1 by means of feed line 2. Temperature and pressure conditions in zone 1 are adjusted to secure the desired fractionation of the crude oil. drocarbon gases are removed overhead from zone 1 by means of line 3; a hydrocarbon fraction boiling,7V in the light naphtha range is removed by means of line 4, a hydrocarbon fraction boiling in the heavy naphtha range is removed by means of line 5, while a gas oil fraction is removed by means of line 6. A fraction boiling in the reduced crude boiling range, as for example, in the range above about 600 to 700 F., preferably boiling in the range above 750 F., is segregated as a bottoms fraction by means of line 7. It is to be understood that zone 1 may comprise any suitable number and arrangement of distillation zones or stages.

In accordance with the present invention, the high boiling reduced crude is mixed with a cycle oil product introduced by means of line which is produced as hereinafter described. The mixture is introduced into a deasphalting zone 8 wherein it is countercurrently contacted with a deasphalting solvent, as for example, propane which is introduced into deasphalting zone 8 by means 'of line 9, Temperature and pressure conditions in zone 8 `are adjusted to secure thedesired removal of asphaltic constituents from the residual oil. A residual oil-propane zone 8 by means of line 13 and introduced into a distillation zone 15.

Temperature and pressure conditions in zone 15 are ad- Low boiling hy- 2,700,637 Patented Jan. 25, 195,5`

justed to remove overhead by means of line 50 propane which is preferably recycled to zone 8. A residual fraction is removed from the bottom of distillation zone 15 by means of line 51 and preferably combined with a portion of the gas oil stream withdrawn from zone 1 which is introduced into line 51 by means of line 52. This gas may be removed from the system by means of The asphaltic constituents are removed from zone 8 by means ot' line 53 and passed to a distillation zone 54, wherein a separation is made between the propane and the asphaltic constituents. The propane is removed overhead by means of line 55 and preferably recycled to zone 8 while the asphaltic constituents are removed as a bottoms by means of line 56 and further refined or handled as desired. It is to be understood that zones 8, 15 and 54 may comprise any suitable number and arrangement of stages.

The present invention is broadly concerned with an improved process for the removal of undesirable high boiling constituents and asphaltic constituents from residual oils. The invention comprises utilizing in conjunction with conventional solvents, a cycle oil segregated from a catalytic cracking operation, preferably a uid catalytic cracking process. The resultant deasphalted product, as pointed out heretofore, is suitable tor the production of high quality lube oils, high quality fuel oils, and is particularly adapted as a feed stock to a uid catalytic cracking operation.

The deasphalting solvent may comprise low boiling hydrocarbons, as for example those containing from 2 to 5 carbon atoms in the molecule, or mixtures thereof. Particularly desirable solvents comprise propane and butane, 'Ihe amount of solvent used per volume of oil may vary from 4 to 10, preferably in the range from 6 to 8 volumes of solvent per volume of oil. The mixture is generally heated to a temperature in the range from about F. to 160 F., in the range from 110 to 140 F. The deasphalting op.- erat1on may comprise a batch operation or a countercurrent treating operation wherein the oil is introduced into the top of the tower, the propane is introduced into the bottom of the tower, and wherein deasphalted oil is removed from the top of the tower and asphaltic constituents from the bottom of the tower. ln conducting an operation of this character, a temperature gradient is .preferably maintained throughout the tower.

.cracking reaction takesplace continuously in one reactor,

the spent catalyst being removed continuously for regeneration in-a separate vassel, from which it is returned to the cracking vessel. Continuity of llow of catalyst as well as of oil is thus accomplished, and the characteristic ,features of xed-bed designs involving the intermittent shifting of reactors through cracking, generation cycles are eliminated.

Regenerated catalyst is withdrawn from the regenerator and hows by gravity down a standpipe, wherein a suciently high pressure head is built up on the catalyst to allow its injection into the fresh liquid oil stream. The resulting mixture of oil and catalyst ilows into the reaction vessel, in Vwhich gas velocity is intentionally low, so that a high concentration of catalyst will result. The cracking that takes place results in carbon deposition on the catalyst, requiring-regeneration of the catalyst. Thecrackedproduct oil vapors are withdrawn from the top of the reactor after passing through cyclone separators to free them ofany entrained catalyst particles,

purging, and re- .while the spent catalyst is withdrawn from'the bottom preferably to a temperature 3 is Withdrawn from the bottom of the its cycle;

Again referring speciiically to the drawing, in accordance with a specific preferred adaptation of the present invention, the".v treated. oil! removed by means of line 51 is4 introduced into` a` catalytic cracking zone. 22.

Temperature and pressure conditions in cracking. zone 2.2 are adjustedy to secure the desired conversion of the feed' oil. Crackedy products are removed overhead from zone 22 by means of. line 23 and` passed into' a fractionation zone 24; Temperature and pressure conditions. in fractionation zone 24 are adjusted to remove overhead by means of line 25l` hydrocarbon constituents boiling ini the: gasoline and lower` boiling ranges. This stream ispassedv to a`- stab'il-i'z'ing'- unit where av gasoline fraction of. the desired volatility is segregated.. A heating oil fraction is. removed by means of line 26 while a fraction Boiling in= the lighty cycle oil boiling range is removed by meansof line 27'. A bottoms fraction or heavy cycle oil@ is remoyednby means of line 28 and handled as desired.A Spent catalyst is removed from the bottom of zone 22 by means of line 29 and passed into a regeneration.I zone by means of line 21. Sufficient air is introduced into the system by means of line 32. Regenerated catalyst is removed from the bottom of zone 30 by means of line 3-3 and passed to the reactor along withy the feed by means of line 17.

The invention is broadly concerned with the removal of undesirable materials from petroleum oils, particular-ly' from petroleum oils boiling in the reduced crude boilingr-ange. Petroleum oils treated in accordance with the present invention are particularly adapted as feed stocks for a catalytic cracking reaction. Although the invention may be adapted for the treatment of mineral oilsboiling. over wide ranges as pointed ont above, it is particularly adapted for the treatment of oils boiling lcyeFabout 750 F., preferably boiling above about As discussed above, the invention is particularly concerned with an improved operation which comprises the treatment of a reduced crude by combining it with a cycle oil product and' deas'pha-lting the mixture, followed by the segregationof a deasphalted residuum which is fed to' a catalytic cracking unit. It is well known in the art to produceI cracked naphthas by aA uidized solids catalytic operation wherein the4 cracked product comprises constituents boilingI in* themotor fuel/boiling range, as" for example, below about 430 F. The cracked product also comprises normally gaseous constituents, as for example, those containing three carbon atoms and less in the molecule. They uidized solids' technique for processing feed fractions. as'for example, gas oils. heavy residuums and other feed stocks for the production' of hydrocarbon fractions boiling in the motor fuel boiling range is a conventional one. As` pointedI out heretofore, the system of af fluidized solids technio'ue comprises a4 reaction zone and a regeneration zone. employed in cr'n'iiunc't-ionv with' a fractionation zone. The reactor and the catalyst regenerator are arranged at approximately an even level; The operation of the reaction zone and the reueneration zone is conventional, which preferably is* as follows:

An overow pan is'proyided in the regeneration zone at thek desired catalyst .level` The catalyst overflows into a` withdrawal lineA which preferably has the form of a U-shaped seal leg connecting the regeneration zone with the reaction` zone'. The feed stream introduced is usually preheated to a temperature in the rance from about 500"vv to- 6in" F. in4 exchangers in heat exchange with recenerator flue ,gases which are removed overhead from the regeneration zone, or with cracked products. 'The heatedl feed stream is withdrawn from the exchangers am! introduced into the reactor; The: seal les is usually sutifiently below the point of feed oil iniection to prevent` oil vapors from backingk into the renenerator in case of normal surges. Since there isno restrictionN in the overflow linev from the regenerator. satisfactory catalyst iiovvY will occur as lonrzl as the catalyst level in the reactor-'is slightly below th'ercatalyst'level in the regenerator when vessels are' carried at.' about the same pressure. Spent" catalyst from the reactor flowsk through a second lli-shaped seal leg from the bottorn of the reactor into the bottom ot. the recenerator; The rate of catalyst new' iscontrolled" by iniectinc'sorneu of the air. into catalyst transfer liney toL the regenerator.

vessel to complete given. a fluidized bed is The pressure in the regenerator may be controlled at the desiredlevelbyl a` throttle valve inn the overhead line from the regenerator. Thus, the pressure in the regenerator may be controlled at any desired level by a throttle valve which may be operated, if desired, by a diiferential pressure controller. If the. pressure differential between the two vessels is maintained at aminimum, the seal legs will prevent gases from passing. from oneyessel into the other in the event tli'a't the catalyst flow in the legs should cease..

The reactor and theregeneratoi: may be designed for high velocity operation involving linear superficial gas velocities of from about 2.5 to. 4 feet per second. However, tle supercial velocity of the upowing gasesl may vary from aboutv .-5V and. higher.. Catalyst losses are minimized and substantially prevented in the reactor by the use of mult-iple stages. of cyclone separators.. The regenerationI zone is provided with cyclone separators. These cyclone separators are usually from 2 to 3 and morestages.

Distributing grids. may be employed. inv the reaction and regeneration zones.v Operating temperatures. and pressures may vary appreciably depending upon the feed stocks being processed and upon. the products desired. Operating temperatures are, for example, in the range from about 800 to 1000 F., preferably about 850-9.50 F., in the reaction zone. Elevated pressures may be employed, but in general pressures below lbs. per sq. in. gauge are utilized. Pressures generally in the range from 1. to 30 lbs. per so. in. gauge are preferred.. A catalyst holdup corresponding to ay space velocity of 1 to 20- weights per hour of feed per weight of catalyst is utilized.. A preferred ratio is 2 to 4.. Catalyst to oil ratios of about 3 to 10, preferably about 6 to 8 by weicht. are used.

The catalytic materials used. in the fluidized catalyst cracking operation, in accordance with the present inyention, are conventional cracking catalysts. These catalysts are oxides of metals of groups TL. TV and V of the periodic table. A. preferred catalyst comprises silica-alurnina wherein the weightl per cent of the alumina is in the range from about 5 to` 20%. Another preferred' catalysty comprises silica-magnesium where the weicht per centr of the magnesia. is about 5% to 20%. These catalysts may also contain a third constituent. as for example, T1109.. WOs. MOO. l2e0. Pi-03- CdO. U03, B601. Snor.. FeOa V905. MnO. CrnOat CaO. Tlvnr, MgO and CeeQa present in the concentration from 0,0 'to 0.5%. The si-ze of the catalyst particles is usually below about 200 microns; Usually at least 50% of the catalyst has a micron size in the-range from about 'Z0-80. Under these conditions with the superficial velocities as maintained wherein the lower section of the reactor. a dense catalyst phase exists while in the, uriner area of the reactor a. dispensed phase exists.

The, above described operation. as pointed ontl han not been entirely satisfactory for cracking heavy oils such. as a reduced crude due to excessive formation nii cai-hon and ash on the catalyst. However. by combining the cycle oil' with the reduced crude and deasohalt-ing the same, unexpected desirable results are secured.

The present invention may be more fully understood by the following example illustrating the same:

EXAMPLE A West Texas crude was distilled to 16% bottoms. A heavy cycle oil (catalyst slurry oil) was segregated from the crackedproduct of a. Huid catalyticy cracking operation. A. two to one blend of the West Texas reduced crude and the slurry oil. was prepared. The inspections ofthe respective feeds were as follows:

centr.

These various feed stocks were deasphalted using propane and butane solvent with the following results:

Deasphalting of 16% West Texas resduum Operating Conditions:

Solvent Butane Butane Butane Propane 400 600 840 420 values are reduced.

the advantages of the present process are apparent.

From the above it is evident that as the yield increases the per cent of carbon in the treated stock also increases. Since the amount of carbon deposited on a iluid catalyst in a iluid catalytic cracking operation is directly proportional to the amount of carbon in the feed stock, it is apparent that the present deasphaltng operation produces a feed stock particularly desirable for a iluid catalytic cracking operation.

Also, from the above it is evident that for a 2% carbon value, it would be expected that the blend yield would be about 46%, whereas the actual blend yield was 62%. The same striking results were apparent when deasphalting to the same gravity, expected 70% blend yield, an actual blend yield of 84% was secured. The amount of material insoluble in 86 API naphtha was .1, whereas it was to be expected that Deasphaltng of slurry oil and blends of W. T. residuum and slurry oz'l 2i Blend-16% w'r R-slurry ou S1315 Y O eratin Conditions:

p Solveit Propane Butane Propane Butane Butane Percent Solvent Treat, Vol.

Percent 800 800 1, 600 800 800 Temperature, F 100 100 150 150 150 Yield: Vol. Percent Deasphalted Oil- 63. 8 83. 3 60. 3 83. 1 89. 3 Inspjctsions: h It) o toms sp a y Specific Gravity l. 082 1. 127 l. 072 1. 120 1. 185 softening Point 124-126 190-191 123-123 194-194 Penetration 34 1 33 0 Matter Ill-lisnl. Naphtha. 15. 97 63. 98 18. 36 60. 20 S1. 67 'lo Deasp a te pravity, API 20. 1 16. 1 20. 5 15. 9 15. 8 Viscosity SSU 100 1, 313 3,079. 2 858 3, 927 171 Viscosity SSU 130... 43 1, 002 300 1,021. 99 88. 4 Viscosity SSU 210 85.2 139. 6 71. 1 142. 3 42. 6 Insol. 86 Naphtha 03 01 00 0. 15 0. 73 Conradson Carbon 2. 27 5. 56 1. 70 5. 08 1. 84

The treated oils were tested with the results as follows:

West Texas Feed Slurry Oil Percent Percent Yield Carbon Yield Carbon Yield West Texas, Slurry Expect. Act. Residu- Oil Blend Blend Percet Pcrcen2 2 C rbon 25 89 6 177g; AZPI 60 89 70 84 Insol. in 86 Naphtha foi' 90% Yield 2.8 .7 2.1 .1

From these and similar data a comparison has been made between results of deasphalting-the components singly and in a blend. When it is considered that:

1. Carbon deposited on catalyst is a direct function of Conradson Carbon of feed. Carbon deposited on catalyst is a direct function of aromatic concentration (gravity). Contamination of catalyst is a direct function of in` solubility in 86 naphtha.

Lube quality demands low Conradson Carbon for engine cleanliness. I

Lube processing (solvent extraction) 1s facilitated by 5. reduction of insolubility in 86 naphtha materials.

the per cent by weight insoluble material would be 2.1% by weight.

The amount of cycle oil added to the reduced crude may vary appreciably and will to a large extent be a function of the heavy aromatic content of the cycle stock and the asphaltic content of the residual oil. Generally, the cycle stock contains from about l0 to 15% heavy aromatics and the residual oil from about 5 to 6% of asphaltic constituents. Thus, a preferred ratio is to blend the cycle oil with the residual oil in a manner to secure a ratio of cycle stock heavy aromatics to asphaltic content of residual oil of from 3 to l, to about 2 to l.

The cycle oil boils above about 700 F., preferably above about 850 F. and has an API gravity below about 16;, preferably a gravity in the range from about 6 to 4.

What is claimed is:

l. In a process for deasphalting a residual oil derived from a crude oil and boiling above about 860 F., the improvement which comprises contacting said residual oil with a C2 to C5 hydrocarbon deasphalting solvent and with a cycle oil boiling above about 850 F. comprising the bottoms product of the catalytic cracking of a gas oil and containing high boiling aromatic compounds whereby a residual oil of improved cracking characteristics is obtained.

2. The process defined by claim 1 in which the said residual oil and cycle oil are countercurrently contacted With the said deasphalting solvent.

The process defined by claim l in which the said deasphalting solvent constitutes propane.

References Cited in the iile of this patent UNITED STATES PATENTS that is, instead of securing an

Claims (1)

1. IN A PROCESS FOR DEASPHALTING A RESIDUAL OIL DERIVED FROM A CRUDE OIL AND BOILING ABOVE ABOUT 860* F., THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID RESIDUAL OIL WITH A C2 TO C5 HYDROCARBON DEASPHALTING SOLVENT AND WITH A CYCLE OIL BOILING ABOVE ABOUT 850* F. COMPRISING THE BOTTOMS PRODUCT OF THE CATALYTIC CRACKING OF A GAS OIL AND CONTAINING HIGH BOILING AROMATIC COMPOUNDS WHEREBY A RESIDUAL OIL OF IMPROVED CRACKING CHARACTERISTICS IS OBTAINED.

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