US2650898A - Process for removing asphaltenes from crude oil - Google Patents

Description

p 1, 1953 E. N. CASE 2,650,898

PROCESS FOR REMOVING ASPHALTENES FROM CRUDE OIL Filed Oct. 27, 1951 TOPPING STILL o O Ill -S .J 5 Q; m (23 cu 58 w n-m f g m U n INVENTOR. ii a Everet'? N. Case i' BY dafm mmmzzzw IQTTORNEYS Patented Sept. 1, 1953 ,7 2,650,898 UNITED STATES PATENT OFFICE PROCESS FOR REMOVING. ASPHALTENES- FROM" CRUDE. OIL

corporationof Maine Application October 27, 1951;. SerlalNb. 253,509 2 Claims.. (01. 1963-39) My invention relates to improvements in therefining of crude oil. More particularly, it relates to a-method for: treating the crude oil. prior to conventional refining practices with. a. precipitating' agent whichselectively precipitates certain asphalticr constituents such asasphaltenes; metal. contaminants, salt and like: deleterious substances; invention provides a simpleand inexpensivermethod' for improving?- the efiiciency of conventional refining processes such as distillation and solvent extraction, ffllf improving the-effectiveness of catalytic cracking processes or: conversely for making available increased. supplies of suitable catalytic cracking. charge stock, and for increasing the not available recovery of marketable oil per barrel of crude processed.

, I have discovered that: certain asphaltic con stituents suchas asphaltenes can be: selectively precipitated from crudeoil by contacting the crude with gaseous hydrogen chloride. The asphal'tenes' precipitate usually immediately on contact with the precipitating agent an'd may be separated from the crude by gravity settling, filitration or centrituging.

Hydrogen chloride is soluble in crude oil. to the; extent: of about .2 weight percent. The per cent of asphaltenesprecipitated appearsto increase up. to'the pointof saturation of the oil with the gas. I have found, however; that it is particularly advantageousto employ superatmospheric: pressure, e'. g. from about to ab0ut I50--20'0-p. s. i. g'.. The per cent of asphaltenes precipitated then is great:- ly increased. The concentration of the-precipitating agent thus may be regulated by pressure for particular crude oils which vary in asphaltic: content or in content of metals and saltand which vary somewhat in solubility for hydrogen chloride. Ordinary temperatures should be employed.

For example, I have found that operations at ele-- vated temperature, e. g. 300 F.,' even with pres sures of 50 to. 150p. s. i'. g. result inreduced pre-- cipitation of asphaltenes'. The effectiveness otthe treatment is increased by mild agitation which as sists in: saturating the crude oil with the precipitating agent.

I have: found; that; invention is particularly applicable to crude: oils which. have. not. been subjected to desaltingoperation: or which have not. beentopped by removal-(of light. boiling distillate fractions. The desaltingprocess seems. to reducethe. efiectiveness oi the: agent in. precipitating. asphaltenes. Although treatment ofi'topped. crudes is technically feasible, the higher viscosity of the topped crude interferes with intimacy of contacting and eifective saturation of the crude oil with the. precipitating agent. Also, application of. the treatment to topped crudes is disadvantageous in the sense that the heat put into the crude in the topping operation should be removed by cooling for effective asphaltenes: precipitation, where?- as. thermal. economics within. the: usual: refinery require conservation of heat by running the hot topped crude directly to succeeding distillation or is introduced at the bottom of tank. H through line I 2. Tank l l is equipped with hydrogen chloride ventline l3 which runs into hydrogen chloriderecycle line l4 and associated compressor l5 for. recycling to tank H. Aft'er saturation of the crude in tank I l with hydrogen chloride gas under appropriate conditions of temperature and pressure, the treated crude is permitted to settle for a period of about 3v to 10 or 12v hours. Thetreated crude then is withdrawn from tank II. bymeans. of swing line I6 and connection H and. charged to topping still l8.

Heat for thedistillation process is provided. by circulating oil from the bottom of still I8 through line l9 and heater 20 with return to the still i8 by'means of connection 21-; Hydrogen chloride'is removed overheadi from still- I 8 through line 22 and knockout drum 22a for return to the treating system by means of line M. A- slipstream of gas may be purged from the system through connection 23* if build up of fixed hydrocarbon gases tends to occur. Distillate fractions are removed as side streams atvarious levels of" still is in the usual manner as indicated by connections 2-4, 25 and Z6. Treated residual. oil may be removed as: bottoms through line 2?.

Although I have shown only-a single tank treating and separating uni-t the drawing, obviously the operations of my invention are facilitated by providing aplurality of tanks connected preferably to a common hydrogen chloride circulating system, in order to maintain continuous supply or treated cru'deto crude oildistillation units. Asnoted above, the treatingvessel advantageously is operated under superatmospheric pressure. I have found that pressures of about 15 to p; s; i. g; hydrogen chloride are very effective. Higher pressures do not appear to increase materially the amount of asphaltenes precipitated. The amount of precipitating agent required is subject to variation with the nature of the crude oil to be treated and the temperature and pressure of the treatment, but I have found that about 0.1 to 0.9 pound of hydrogen chloride per barrel of. crude oil is usually sufficient. In. any event, it..is.advisable toprovid'eat least enough ofQt-hev precipitating. agent tov saturate the crude with the agent.v

The principles of my invention will be, further,

3 illustrated in the following examples of treatments under various conditions:

Examples The crude oil was charged to a vessel equipped with a mechanical agitator or to a vessel which could be shaken by hand. To the crude was added the specified amount of gaseous hydrogen sive means for pretreating crude oil prior to conchloride followed by agitation. The asphaltenes precipitated immediately and either collected on the walls of the vessel or were present. as solid particles in the crude oil. The charge was removed from the vessel and centrifuged to remove the precipitate. The same end was attainable by about 12 hours gravity settling. The clean crude layer was decanted and the precipitate was washed with straight run gasoline to remove the trapped crude. The wash liquid may be centrifuged or settled if necessary. The asphaltenes precipitate was weighed to determine yield. 4

Where the precipitate adhered to the container walls, it was recovered by solution in benzene and the benzene was removed by distillation to give a residue of asphaltenes.

Using the above procedure the following tests were run on Mid-Continent crude which had been topped to 400 F. by removal of 31.5% overhead, increasing the density to 0.87:

Wt. Percent Asphaltenes Yield Charge Vol. 1101 Gas C1 50 p. s. i. g. H01 at 300 F. 150 p. s. i. g. 1101 at 300 F p. s. i. g. HCl

In a similar test, the crude was first desalted. A charge of 700 ml. of density 0.808 was saturated with hydrogen chloride gas at 50 p. s. i. g. The weight per cent yield of asphaltenes amounted only to 2.1% or 2.78% when corrected to the 68.5% bottoms basis of the foregoing runs.

In a similar example, 700 ml. of untreated Poza Rica (Venezuela) crude oil of density 0.878 was saturated with hydrogen chloride gas at 50 p. s. i. g. The weight per cent yield of asphaltenes amounted to 6.92% or 9.10% corrected to a 68.5% bottoms basis.

As Re- Precipi- Crude ceived tate Residue p. p. m. NiO 9. 5 300 3. 6 p. p. m. V205 18.8 l, 060 8 Hence the metals content of crude oil can be substantially reduced by application of my invention.

In another example, a topped Mid-Continent crude (69% bottoms) having a carbon residue of 3.0 weight per cent was treated by saturation ventional refinery processing. Removal of a substantial proportion of the asphaltic constituents of the crude before the oil is subjected to thermal processing such as cracking, vis-breaking or vacuum distillation increases significantly the yield of the more valuable oil fractions per barrel of crude processed. The net production of coke or asphalt is reduced and thereby reduces significantly the amount of low value residuum which must be disposed of in the form of heavy fuel oils or asphalt. About 40 to of the content of solid asphalt represents valuable heavy oil constituents which are normally lost. My invention thus increases potential oil recovery in proportion to the reduction in asphalt residuum. Also disposal of the heavy residuum as fuel oil requires expenditure of considerable amounts of distillate oil as cutter stock. Any decrease in the amount of residuum therefore conserves oil by reducing the requirements for cutter stock.

One of the limiting factors on utilization of heavy gas oil stocks as charge to catalytic cracking units is the carbon residue of the charge stock which deleteriously affects product distribution in the cracking reaction and reduces capacity of the unit by increasing the burden on the coke-burning capacity of the catalyst regeneration equipment. Application of my invention permits utilization of heavier gas oil stocks without deleteriously affecting product distribution and without overburdening the coke-burning capacity of the catalytic cracking unit. Application of my invention is of further value in promoting the economics of catalytic cracking by reducing substantially the metals content of the cracking charge stocks. The result is improved catalyst life and a substantial reduction in the rate at which catalyst must be discarded from the unit to maintain a desired equilibrium activity level.

In lubricating oil refining and production, application of my invention facilitates deasphalting and solvent extraction operations and results in improved raffinate yields.

I claim:

1. A method for removal of asphaltenes and metal contaminants from crude oil prior to desalting and conventional refining procedures which comprises saturating the crude at a pressure from 15 to 200 pounds per square inch gauge with a precipitating agent consisting of gaseous hydrogen chloride and separating the agent and precipitated matter from the treated crude.

2. A method of removal of asphaltenes and metal contaminants from crude oil prior to desalting and conventional refining procedures which comprises saturating the crude at a pressure from 15 to 200 pounds per square inch gauge with gaseous hydrogen chloride, separating precipitated matter from the treated crude and recovering hydrogen chloride from the treated crude by distillation.

EVERETT N. CASE.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A METHOD FOR REMOVAL OF ASPHALTENES AND METAL CONTAMINANTS FROM CRUDE OIL PRIOR TO DESALTING AND CONVENTIONAL REFINING PROCEDURES WHICH COMPRISES SATURATING THE CRUDE AT A PRESSURE FROM 15 TO 200 POUNDS PER SQUARE INCH GAUGE WITH A PRECIPITATING AGENT CONSISTING OF GASEOUS HYDROGEN CHLORIDE AND SEPARATING THE AGENT AND PRECIPITATED MATTER FROM THE TREATED CRUDE.

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