US2007114A - Method of treating oils - Google Patents

Description

y 2,1935? R. K. SITRATFORD- 2,007,114

METHOD OF TREATING OILS Filed Marci 1 24, 1930 2 Sheets-Sheet 1 INVENTOR V a/cm v July 2, 1935.

R. K. STRATFORD Filed March 24. 1930 2 Sheets-Sheet 2 lww s W, m h\ p N 1 g k m Q QSRQ ERB m f \w Mw wi N KN NM, Jvh wh hn 1+ \h wake My. w g N I 433 N6 3 ...%N a w ATTORNEY tilt Patented Jul 2, 1935 UNITED STATES 2.007.114- METHOD- or 'rnmrnvc oms Reginald K. Stratford, Sarnia, Ontario, Canada,

assignor to Standard Oil Development Company, a corporation of Delaware Application March 24, 9 0, fl- 438,335

' 3 Claims. '(ci. 196-13) This invention relates to a method of treatingoils, and more particularly it relates to a metliod of treatingoil stocks with phenol prior to 'crackv ing in order to remove undesirable constituents 5 thereirom. I The invention will be fully understood from the following description read in conjunction with the drawings, in which Fig. 1 is a diagrammatic side elevation partly in dsection of the preferred form of apparatus,

Fig. 2 is a diagram showing the combination of treating cracking stock and treating kerosene.

Many cracking stocks contain a considerable percentage of sulfur which causes corrosion of the cracking equipment such as the heating coils, soaking drum, and bubble tower. Further, the distillate obtained from such stocks requires a thorough acid treat in order to remove sulfurcontaining constituents. I have discovered that by treating the cracking stock with a 'suificient amount of phenol, such a large percentage of sulfur compounds may be removed that not only the corrosion of the cracking equipment is greatly reduced but the necessity of acid treatment is also eliminated.

Although my invention is applicable to many cracking stocks, it shows especial advantageswith liquid phenol, diluted or undiluted with diluents such as water, alcohol, etc., separating the oil layer from the phenol layer, removing the a dissolved phenol from the oil layer preferably it by distillation, and subjecting the purified oil to cracking. The treating of the gas oil with phenol may be carried out in a batch treater but better results are obtained by using a countercurrent treater. The amount of phenol will vary according to the sulfur contentand to the stock, for instance, Californian gas oils require lilo-150% phenol when a countercurrent treater is used. while Sunburst gas oils usually do not require much more than of phenol. If a batch W treater is used instead of countercurrent treater the amount of phenol necessary for the required improvement is about double the amounts given above.

The treating temperature may vary within wide limits. Temperatures as low as Emay be employed if the diluted phenol is liquid at that temperature, and treating temperatures of 150 F. or higher maybe employed. Usually, in the case of strong (-100%) phenol the treating temperature should be from 90 to F. or 5 higher. In no case should the temperature be so high that the phenol'and the oil become completelymiscible.

"The process and the apparatus will now be Jointly described. The oil from tank 8 and the 10 phenol from tank 2 are charged to the countercurrent treater 3. In this treater, which may consist of several compartments, the oil and thetreating agent are passed through the compartments according to the principle of coun- 15 tercurrent treatment. Such a countercurrent treater has been described and illustrated in my prior application Serial No. 403,182 filed on October 29, 1929. The spent phenol is removed by line 4 and the oil containing some phenol is passed through the heat exchanger 5 and heating coil 6 into the fractionating tower l for the removal of the phenol. The phenol vapors are condensed in condenser 8 and returned to storage tank 2. p The spent phenol removed by line 4 may be separated into phenol and extract using a similar method. The oil freed from the phenol leaves the tower through line '9 and after lowing the mixer servefor the removal of organic acid constituents from the oil. The lye is recycled by means of pump it, the oil leaving through line it. The purified gas oil is then charged by means 01' pump IE to the cracking coil I8 in which it is heated up to cracking temperature, and then discharged into the soaking drum I! in which the desired degree of cracking takes place; A high pressure, such as 250-750 lbs. per square inch, is maintained on the coil and soaking drum and a temperature sufilcient for the so-called liquid phase cracking as well known in the art. The coil outlet temperature, for instance, may be 850 F. From the soaking drum-the combined liquid and vapors are dis- 7 charged through the release valve it into a separator it where tar isdrawn on the bottom, f the overhead going into the bubble tower it in which the cracked material is separated into gas oil, which is removed by line 2% as cycle stock which is returned by line M to the coil, and into an overhead product consisting of vapor and gas and leaving the bubble tower by line 22. The 55 overhead product may be then treated with finely divided clay in treater 2'3 and passed to the condenser 24, or may first be cooled, separated into liquid and gas and the liquid products subjected to clay treatment. An appropriate method of clay treating, which may very well be applied in the present case, is described in my U. S. application Serial No. 62,710 filed October 16, 1925. According to this method the cracked gasoline is passed mostly in vapor phase countercurrent to a stream of finely divided solid absorbent such as clay carried by a slurry of oil.

The purpose of the clay treating is to polymerize some highly unsaturated products which tend to form gum, and to remove coloring bodies which would give the gasoline a dark color. In the present practice such undesirable products are removed from the cracked distillate by means of acid treating and redistillation, and it is seen that these steps become unnecessary according to the present invention. Another advantage of my process is that corrosion of the cracking equipment is greatly reduced, and it will be realized that this also results in considerable saving in the combined cracking and treating process.

The extract removed with the spent phenol by line 4 may be separated from the phenol by distillation, similarly to the process described above, for the separation of absorbed phenol from the treated oil. This extract is somewhat heavier in gravity and higher in sulfur content than the original gas oil but it may be very well used as fuel oil. a

It is often advantageous to combine the gas oil treatment with refined oil (kerosene) treating, the spent phenol from the gas oil stock treat being employed to treat refined oil. This method is based on the observation that it is possible to replace a heavier extract with a lighter oil in the spent phenol. This method and its use for the recovery of phenol from the spent phenol obtained in treating kerosene has been described in my prior U. S. application Serial No. 279,602,

filed May 21, 1928. In the combined gas oil and kerosene treating the spent phenol of the gas oil treat is contacted with kerosene part of which becomes dissolved in the phenol and the other part forms a separate oil layer in which the gas oil extract is dissolved with some phenol. The kerosene and the gas oil may be separated by distillation and rectification, while the phenolkerosene layer may be further treated with naphtha. The last treatment again yields two layers, the one consisting of phenol and naphtha and the other one consisting of kerosene and naphtha. Both layers may be separated into their constituents by distillation and rectification or by some other method.

An advantageous combination of gas oil and refined oil (kerosene) treatment will be described in conjunction with the apparatus used therefor which is shown in Fig. 2.

The gas oil is first treated with phenol and then subjected to cracking as described above in conjunction with Fig. 1. The spent phenol leaving by line 4 is then used to treat refined oil pumped through line 25 from a. storage tank (not shown). The treating is carried out in counter-current treater 25 as a result of which two products are obtained: (a) a refined oil extract in phenol leaving through line 21 and (b) a mixture of treated refined oil, gas oil extract and some phenol leaving through line 28. The latter is first treated in countercurrent treater 29 with an aqueous solution of alkyl phenolate pumped from storage tank 30 in order to remove the small amount of phenol which it contains.

The process of removing phenol from oils by treatment with alkyl phenolate forms the subject matter of U. S. application Serial No. 338,420, filed on February 8, 1929, in the name of Reginald K. Stratford and Herbert H. Moor.

The mixture of refined oil and a gas oil extract leaving the treater 29 is then mixed in mixer 3| with lye and allowed to settle in settling drum 32. The lye after settling down is recirculated through the mixer and settling drum by means of pump 33. The oil mixture is then given a water wash in tower 34 and removed by line 35 to rerun stills for the purpose of separating the refined oil from the gas oil. The water to tower 34 is supplied by means of pump 36 from a Water reservoir which is not shown.

The phenol leaving'treater 26 through line 21 which contains the refined oil extract is brought in contact in treater 31 with an appropriate amount of naphtha, pumped through line 38 from the naphtha storage tank 39. A mixture of naphtha, refined oil and small amounts of phenol leaving through line 40 is passed through heat exchanger 4| into still 42 in which it is rerun to obtain naphtha as overhead product after passing through the condenser 43. This naphtha may be removed from the system for use as motor fuel, etc., or returned to the storage tank 39 if so desired. The phenol containing naphtha extract is passed from treater 31, through heat exchanger 44, into still 45 from which the naphtha distills over, is condensed in condenser 46 and removed through line 41 from the system. It may be used for special purposes such as solvent, etc.

The phenol leaving still 45 as distillation residue is pumped'back through line 48 to phenol storage tank 2 of Fig. l. The refined oil phenol residue of still 42 is pumped through line 49 into treater 50 in which it is freed from the phenol content by means of the mixture of phenolate solution and phenol which leave treater 50 by line 5|. Treater 5|) yields refined oil which is given a lye treatment in mixer 5| and settling drum 52. The lye may be again recirculated. The refined oil thus obtained is removed by line 53 and may be used as fuel oil or for similar purposes. The mixture of phenolate solution and phenol is passed from treater 50 into vacuum evaporator 54 in which the phenol is evaporated, condensed in condenser 55 and then passed back to the phenol storage tank 2 of Fig. 1. The phenolate solution obtained as distillation residue is returned through line 53 to the phenolate storage tank 30.

The following examples will serve to illustrate my invention.

A California gas oil having the following characteristics:

Gravity 30.5 A. P. I. Initial boiling point "364 F. Sulfur content "0.734%

is treated with 2-100% batch treats of phenol water mixture containing 95% of phenol, at a temperature of 90-95 F. 76% of the oil is recovered as rafilnate after the 4% of phenol which it contained is distilled off and the residue is treated with lye. The raflinate is then cracked to produce 37% of 415 end point gasoline which is passed through the treating tower described in my application above referred to. The colorless gasoline has a sulfur content of 0.134% and the cracked bottoms 0.35%. The 24% oil which is absorbed 3 by the phenol is separated from the latter by tention to claim all novelty inherent in the in? means of distillation and fractionation and vention.

shows the following characteristics: I claim:

Gravity 24.4 as. r. Sulfur content 1.2%

Itisusedasfuel oil.

As another example, Sunburst gas oil,

Gravity A. P. 1. 28.4 Initial boiling point; 422 Sulphur content l 1.26%

is treated with 1-100% of phenol water mixture containing 95% of phenol and 5% water at a temperature of 90-95. 83% of the oil isrecovered as raflinate after the 4% of phenol which it contained is distilled oil and the residue is treated with lye. The ramnate is then cracked to produce 33% of the 415 end point gasoline which is passed through a clay treating tower. The colorless gasoline has asulphur content of '1 0.092% and the cracked bottoms 1.56%. The

17% 011 which is absorbed by the phenol is separated from the latter by means of distillation and fractionation and shows the following:

Gravity a.1=.1. 19.2

- Sulphur content 1.8%

- above. The treatment gives a kerosene of greatly improved burning quality amounting to 70-80% of the original volume of the untreated kerosene.

Idonotwishtolimitmyinventionby any theory or example given by way of illustration but only by the following claims in which it is my in- 1. The method of producing low boiling hydrocarbon oils from a cracking stock of the class comprising sulfur-containing petroleum gas oil ahd reduced crude of paraffin base, which comprises the steps of treating the cracking stock withliquid phenol at a temperature below that at which the cracking stock and the phenol become completely miscible, separating the oil layer from the phenol layer, subjecting the oil layer to cracking, separating low boiling hydrocarbons, andtreating atleastpart ofthelowboiling hydrocarbons with finely divided clay to improve the color of the hydrocarbons.

'2. Method of producing low boiling hydrocarbon oils capable of use as motor fuel without acid treating from an oil of the class comprising sulphur-containing petroleum gas oil and reduced crude of'paraflin base, which comprises treating the oil with a phenolic solvent adapted to remove sulphur, separating the solvent from the oil, subjecting the oil .to cracking, and refining the resulting low sulphur gasoline by contacting it with a solid adsorptive catalyst of the clay type.

3, The process of producing refined low boiling hydrocarbon distillate suitable for use as motor fuel from an oil of the class comprising sulphurcontaining petroleum gas oil and reduced crude of paraiiin base, which comprises preliminarily treating the oil with an essentially sulphur-free uents.

REGINALD K. B'I'RA'I'FORD.

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