US2582883A - Modified double solvent treatment - Google Patents

Description

Patented Jan. 15, 1 952 UNITED STATES PATENT OFFICE f ass'bisfia' MODIFIED DOUBLE SOLVENT]? TREATMENT Harold C. Myers, Woodbury, assignorto Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application August 27,1947,

. Serial No. 770,951

The present invention relates to the separation of mixtures of hydrocarbons into aparaffinic portion and a non-Vparaffinic portion and, more particularly, to the refining of petroleum oil and the like to a raifinate of higher parafinicity than the charge stock.

- The so-called double solvent processes of solvent treating petroleum oil employs 'two solvents of relatively low mutual solubilities, one of which has a high preferential solubility for the undesirable constituents of the oil, usually classified as non-paraffinic or naphthenic and aromatic hydrocarbons, and the other a high preferential solubility for the desirable constituents of the oil, usually classified as parafiinic hydrocarbons. The first solvent is usually referred to as the naphthenic' solvent while the other solvent is usually referred to as the paraffinic solvent. The raffinate phase in the double-solvent treatment is a solution of the more paraffinic portion of the charge oil in the paraflinic solvent'while the'extract phase is a solution of undesirable constituents or non-paraffinic constituents in the naphth'enic solvent.

A brief but adequate description of one modi- 1'.

fication of the double solvent method of treating petroleum oil is given in the Process Handbook section of Petroleum Refiner (April 1947) pages l3'8and 139. The double solvent process is also described in U. S. Patents Nos. 1,912,348: 1,912,349 and, 2,041,308.

The double solvent refining process which is most widely used in the petroleum industry for refining residual oils is known as the Duo-Sol process. The process is capable of simultaneously deasphalting and solvent refining asphaltic residua by employing a. two-solvent system composed of a naphthenic solvent, selecto, and a parafiinic solvent, liquid propane. Selecto is a mixture of phenol and cre'sylic acids usually containing 40 to 60 per cent phenol. In a Duo- Sol system, the liquid propane acts as an asphalt precipitant and diluent while selecto functions both as a solvent for the asphalt and an oil treating agent. A typical installation consists essentially of a three to seven stage countercurrent extraction system in which a propane-oil mixture' is contacted with sel'ecto plus a two stage system in which the selecto, containing ex extracted material. is countercurrently washed 2 with fresh liquid propane. In a seven stage propane would be added to the first, charge stock in the third, and selectof inthe seventh stage;

, The spent solvent containing extracted material and asphalt would bed-rawn from the first and of synthesis, likewise are amenable to this treat-;

ment, 7

lI-t hasnow been discovered that the useot amodifier in conjunction with the parafii-nic and, naphthenic solventsin atypical double solvent treatingprocess results in an increased recovery of the refined oil from the non-paraffinic materials .in the charge stock. The refined oil soobtained is of a quality comparable to that produced inthe conventional double solvent treating. process although of somewhat higher viscosity. The rejected: material, i e. the solute of the extract phase, or tar is of higher gravity,

than tar from normal or conventional double solvent operations.

In general, the paraffinic solvents employed in I the; double solventtreatment of mixtures ofparaf finic, naphthenic andaromatic hydrocarbons with or withoutadmixedasphaltic materials are lique-' fied normally gaseous hydrocarbons such as the saturated and unsaturated hydrocarbons havingi 3 to 5 carbon atoms, lighter hydrocarbonszsuch as methane, ethane, ethylene, acetylene, etc. mixed with hydrocarbons of 3 to 5 carbon atoms and-heavier aliphatic and olefinic hydrocarbons having up to 10 or 12' carbonatoms per molecule.-

Other para-ifii-lic solvents are methyl Cellosolve, Carbitol and-other oxygenated compounds such asac'etone, methyl, ethyl and isopropyl alco'= hols, etc: v

The naphthenic solvents employed in the" double solvent treatment of mixtures of past-'- finic, naphthenic and aromatic hydrocarbons with or without admixed asphaltic materials are aqueous or non-aqueous liquid S02, liquid SO2- benzol, furfural, dichloroethyl ether, aniline, quinoline, pyridine, nitrobenzene, benzyl alcohol, phenol, cresylic acid, ethylene diamine, diand triethanolamines, crotonaldehyde, sulfolanes, dimethyl formamide, formic acid and acetic anhydride, etc.

When the effects of the foregoing combinations of parafilnic solvent and naphthenic solvent are modified by the use of a third component, hereinafter termed a modifier, the oily constituents of high viscosity present in the charge stock are retained in the raflinate phase instead of being rejected in extract phase as in conventional double solvent treatment. As a result the process yield is higher and the raifinate is of higher viscosity. By modification of other variables a much higher yield of oil of-comparable quality is obtained using the modified solvent combinations than is obtained withconventional solvent combinations.

The solvent combinations are advantageously modified by the use of a. modifier selected from the group consisting of carbonates of aliphatic, cycloaliphatic, and aromatic hydrocarbons and heterocyclic compounds, of which group diethyl carbonate is preferred.

-While the use of one of the afore-enumerated modifiers in conjunction with one of the conventional combinations of paraffinic solvent and naphthenic solvent brings about the advantages enumerated hereinbefore, a more selective action in the presence of smaller amounts of modifier can be obtained by incorporating small amounts of water, say up to 25 weight per cent in the naphthenic solvent.

The modified double solvent refining operation with or without aqueous naphthenic solvent is conducted in about the same manner as conventional double solvent refining operations withprovision for adding modifier or modifier andwater at any point or points in the unit. However, improved results are obtained by washing the extract phase with fresh parafiinic solvent-modifier mixture. Thus, for example, in a nine stage system paraifinic solvent and modifier are added in the first stage, charge oil in the third stage, and aqueous or non-aqueous naphthenic solvent in the ninth stage while the treated mixture of hydrocarbons, i. e. mixture of hydrocarbons of increased parafiinicity, is withdrawn from the ninth and the rejected extract from the first stage of the unit. The rafiinate and extract are separately treated in any suitable manner, say by distillation, to remove the paraflinic solvent and the naphthenic solvent respectively. The ratio of paraflim'c solvent and naphthenic solvent to charge stock may be varied from 1:1 to 7:1, while the modifier ratio (based on the charge stock) may vary from 0.15 to 15:1. The temperatures employed may vary from '75 to 206 degrees Fahrenheit.

. Those skilled in the art will understand that although the use of modifiers in conjunction with the solvents in a double solvent treatment of a mixture of parafiinic and non-parafilnic hydrocarbons has been discussed hereinbefore and will be described hereinafter in conjunction with treatment in isolated zones known as stages, nevertheless the treatment can be carried out in a tower or towers or in equipment employing centrifugal force to accelerate the separation of the raflinate phase from theextract phase. Furthermore, the solvent treatment of charge stock with a naphthenic solvent and particularly with aqueous naphthenic solvents in the absence of a parafiinic solvent is improved by the use of the novel modifiers enumerated hereinbefore.

Thus, for example, a mixture of parafiinic and non-paraffinic hydrocarbons can be treated in the manner described in the Process Handbook section of Petroleum Refiner (April 1947) pages 122 and 123, using dichloroethyl ether, phenol or, in general, any naphthenic solvent containing up to 10 per cent of water (aqueous naphthenic solvent) together with one or more of the modifiers enumerated hereinbefore.

Typical of the treatment of charge stocks containing parafiinic and non-parafiinic hydrocarbons are the following non-limiting examples.

EXAMPLE 1 EXAMPLE II In order to provide a standard whereby the effect of the modifiers can be evaluated, a portion of the same stock was treated at the same temperature with about 300 weight per cent of naphthenic solvent of 50 percent phenol content (selecto) and about 500 weight per cent of propane.

EXAMPLE III In order to show the efiect produced by using a naphthenic solvent containing water in conjunction with a parafiinic solvent and a modifier, diethyl carbonate, a charge stock of 458 seconds Saybolt Universal viscosity at 210 degrees Fahrenheit was processed in the same equipment employing about 350 weight per cent "naphthenic solvent of 50 per cent phenol content (selecto) containing about 1.5 per cent of water, about 450 weight per cent of propane and about 25 weight per cent of diethyl modifier at a temperature of about degrees Fahrenheit.

EXAMPLE IV To provide a standard of comparison for the results obtained in Example III, a portion of the same charge stock was treated with the same amounts of the same naphthenic and paraffinic solvents in the absence of a modifier.

EXAMPLE V tent and about 450 weight per cent of propane at a temperature of about 120 degrees Fahrenheit.

A summary of the results obtained in each of the Examples I to V is provided in the following table;

COMPARATIVE Duo-sot REFINiNG DATA ON RESIDUAL STOCKS EMPLOYI'NG AS THE SELEOIO, SELECTO-WATER WITH LIQUID PROPANE DIE'IHYL CARBONATE Diethyl Carbonate Ratio Based on Oil Phenol Content of Selecto, Per Cent Wt Water Content of Selecto, Per Cent Wt Run Number Percolation, Oil/Clay Ratio by Wt 0. 8:1 1. 4:1 Yields, Per Cent Vol;

11 Process Extraction 84. 1 78. 9 Dewaxing, Ultimate 75. 8 75. 2

Overall- On Residuum 58. 9 54. 8 On Crude 23.4 13. 8 12.8

Raw Waxy Dewaxed Finished Waxy Dewaxed Finished Resid Rafi. Rafi. Oil Rafi. Rafi. Oil

Processing Step:

Inspections- Crravity, A. P. I Gravity, Specific 60 F. (Pyc 77 F.) Pour Point, F Flash Point, F. (GOO). Fire Point, F. (COC) K. V. 100 F. (Centistokes).

210 F. (Centistokes) S. U. V. 100 F., Seconds 210 F., Seconds. Viscosity Index Viscosity Gravity Constant 210 F- Color, Lovibond, 34 Cell Carbon Residue, Per Cent Wt. Sulfur, Per Cent Wt '0 o @F (P @77F) peci c r. yc S. U. V. 210 F., Seconds Processing Conditions:

Duo.ol Refining Oil-Selecto-Propane Ratio by Wt Temperature, T

Diethyl Carbonate Ratio Based on Oilfle Phenol Content oiSelecto. Per Cent Wt" Water Content of Selecto, Per Cent Wt Run Number Percolation, Oil/Clay Ratio by Wt Yields, Per Cent Vol.:

On Process- Extraction Dewaxing, Ultimate Overall On Residuum On Crude Waxy Raff.

Finished Oil Finished Oil Processing Step:

lnspections Gravity, A. P. I Gravity. Specific 60 F. (Pyc 77 F.). Pour Point, F Flash. Point. F. (COG) Fire Point, F. (00C) K. V. 100 F. (Centistokes) 210 F. (Centistolres) S. U. V. 100 F., Seconds 210 F., Seconds Viscosity Index Viscosity Gravity Constant 210 F Color, Lovibond, 34 Cell a- Carbon Residue, Per Cent Wt r Sulfur, Per Cent Wt -r ar Specific Gr. 60 F. (Pyc 77 F.) S. U. V. 210 F.. Seconds The solvent refined oils obtained as described hereinbefore, particularly when liquid S02 or liquid SOz-benzol or selecto are used as naphthenic solvents, can be dewaxed merely by removing a portion of the propane to chill the oil and-adjust the propane concentration to that desirable for dewaxing. In other words, the concentration of propane and organic carbonate in the rafiinate is adjusted, preferably by vaporization of the propane, to provide a ratio of propane to organic carbonate from about 3:1 to about 1 :3 by Volume. The vaporization of the propane serves to chill the raflinate to dewaxing temperatures although the raflinate can be chilled by other suitable means. When adjusting the ratio of propane to organic carbonate in the raflinate to provide a dewaxing mixture, it is also preferred to adjust the ratio of solvent refined oil to dewaxing mixture in the raflinate to 110.2 to 1:8 with a ratio of 1 to 3 preferred.

I claim:

1. In the treatment, of a mixture of paraflinic and non-paraffinic hydrocarbons contaminated with asphaltic materials which comprises contacting' a charge stock containing parafinic hydrocarbons, non-parafiinic hydrocarbons and asphaltic material with two substantially mutually immiscible solvents comprising a solvent for paraflinic hydrocarbons and a solvent for nonparaflinic hydrocarbons and separating a raflinate fraction more paraffinic than said charge stock from an extract fraction more non-paraffinic than said charge stock, the improvement which comprises employing a solvent for non-parafiinic hydrocarbons consisting essentially of phenol and cresols and at least 1.5 weight per cent added water and a solvent for paraffinic hydrocarbons consisting essentially of propane and about 1 to about 20 per cent of an organic carbonate.

2. In thetreatment of a mixture of parafiinic and non-paraffinic hydrocarbons contaminated with asphaltic material which comprises contacting a charge stock with propane and a mixture of phenol and cresols in the proportion of 1:1-3. 521-45 by weight, and separating a raflinate fraction more parafiinic than said charge stock from an extract fraction more non-paraffinic than said charge stock, the improvement which comprises employing a mixture of phenol and cresols to which about 1.5 to about 25 per cent water has been added and propane to which about 1 to about 20 per cent of an organic carbonate has been added.

3. The process as set forth and described in claim 1 wherein the organic carbonate is diethyl carbonate.

4. The process as set forth and described in claim 2 wherein the organic carbonate is diethyl carbonate.

5. In the treatment of a mixture of parafiinic and non-parafiinic hydrocarbons contaminated with asphaltic material which comprises contact-- ing a charge stock with propane and cresylic acids in the proportion by weight of 1:1-3.5:1-4.5, and separating a rafiinate fraction more paraifinic than said charge stock from an extract fraction more non-parafiinic than said charge stock the improvement which comprises carrying out the separation in the presence of 1.5 to about 25 per cent added water and about 1 to about 20 per cent of an organic carbonate.

6. The process described and set forth in claim 5 wherein the added organic carbonate is diethyl carbonate.

7. The method of treating a mixture of hydro carbons admixed. with asphaltic material and subsequently dewaxing said lmixture of hydro carbons which comprises contacting a waxy mix ture of paraifinic and non-parafiinic hydrocar: bons admixed with asphaltic material with liquid,- normally gaseous hydrocarbon, a mixture of phenol and cresols and an organic carbonate in the ratio of 1 part ofoil to 1-3 parts of propane to 1-3 parts of said mixture of phenol and cresols to 0.15 to 1.5 parts of organic carbonate all by weight, separating a raffinate phase comprising wax, parafinic hydrocarbons, propane and organic carbonate from an extract phase comprising non-paraflinic hydrocarbons, asphalt and mixture of phenol and cresols, adjusting the ratio of propane to organic carbonate in said rafiinate phase from 1 to 3:0.15 to 1.5 by weight to 3:15 to 1:5, chilling said rafilnate to dewaxing temper ature and separating high molecular weight paraffinic hydrocarbons from said raffinate phase to provide a solvent treated dewaxed oil.

8. The invention as set forth and described in claim 7 wherein the liquid, normally gaseous hydrocarbon is propane.

9. The invention as set forth and described in claim 7 wherein the organic carbonate is diethyl carbonate.

10. The invention as set forth and described in claim 7 wherein the liquid, normally gaseous hydrocarbon is propane and the organic carbonate is diethyl carbonate.

HAROLD C. MYERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,860,823 Stratford May 31, 1932 1,912,349 Tuttle May 30, 1933 1,917,910 Sullivan July 11, 1933 2,017,432 Bahlke Oct. 15, 1935 2,139,000 Cohen Dec. 6, 1938 2,142,525 Noll Jan. 3', 1939 FOREIGN PATENTS Number Country Date 413,307 Great Britain July 11, 1934

Claims (1)

1. IN THE TREATMENT OF A MIXTURE OF PARAFFINIC AND NON-PARAFFINIC HYDROCARBONS CONTAMINATED WITH ASPHALTIC MATERIALS WHICH COMPRISES CONTACTING A CHARGE STOCK CONTAINING PARAFFINIC HYDROCARBONS, NON-PARAFFINIC HYDROCARBONS AND ASPHALTIC MATERIAL WITH TWO SUBSTANTIALLY MUTUALLY IMMISCIBLE SOLVENTS COMPRISING A SOLVENT FOR PARAFFINIC HYDROCARBONS AND A SOLBENT FOR NONPARAFFINIC HYDROCARBONS AND SEPARATING A RAFFI NATE FRACTION MORE PARAFFINIC THAN SAID CHARGE STOCK FROM AN EXTRACT FRACTION MORE NON-PARAFFINIC THAN SAID CHARGE STOCK, THE IMPROVEMENT WHICH COMPRISES EMPLOYING A SOLVENT FOR NON-PARAFFINIC HYDROCARBONS CONSISTING ESSENTIALLY OF PHENOL AND CRESOLS AND AT LEAST 1.5 WEIGHT PER CENT ADDED WATER AND A SOLVENT FOR PARAFFINIC HYDROCARBONS CONSISTING ESSENTIALLY OF PROPANE AND ABOUT 1 TO ABOUT 20 PER CENT OF AN ORGANIC CARBONATE.