US2091624A - Method of treating hydrocarbon oils - Google Patents

Description

Aug. 31, 1937. J; c. BLACK E1' AL METHOD 0F TREATING HYDROCARBON OILS Filed April 24, 1933 NW www .mi WW INVENTORS Patented Aug. 31, 19.37

2,091,624 METHOD 0F TREQTNSG`-HYDROCARBON John C. Black, Beverly Hills, and Marvin L. Chappell, Watson, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application April 24, 1933, Serial No. 667,526

6 Claims.

'Ihis invention relates to the treatment of hydrocarbon oils, such as petroleum oil residua, or distillates derived from crude petroleum oil, shale oil, or similar sources, and more specically refers to the treatment of petroleum oil residua, lubricating oil stocks or distillates derived by distillation of crude petroleum oils, preferably under vacuum or partial vacuum, topurify the same by removing unstable hydrocarbons, sulphur bearing hydrocarbons and amorphous or crystalline parafiln wax.

This invention may also be employed in the manufacture of white oil stocks to produce liquid petrolatum, or white oil stocks which are suitable for use in the manufacture of orchard spray oils, which require the substantial removal of all unsaturated hydrocarbons toxic to foliage.

Our preferred method of treating residua, lubricating oil stocks, or distillates derived from naphthenic base, mixed base, or paraiiin base crude oils, consists in dissolving the oil under treatment in liqueed hydrocarbon gases, and while in solution subjecting the mixture to an acid treatment with sulphurlc acid at a temperature suitable for the removal of the undesired hydrocarbons and waxes.

The treating temperature may vary through a wide range, depending upon the quality or characteristics of the oil under treatment, a higher temperature being usually used if the oils are derived from a naphthenic base crude petroleum oil, and a lower temperature may be used if the oils are derived from a mixed base or paraiiln base crude oil when it is desired to remove amorphous or crystalline'wax.

In the removal of waxes from petroleum oils,

or those hydrocarbons which cause gelatinizaltion of lubricating oil stocks, the temperature may be 'varied in our process so as to remove iirst the waxes congealing at relatively high temperatures, and thereafter further cooling and removing the lower melting or amorphous waxes to the required degree necessary to obtain an oil stock having a desired cold test. By our process a parain base oil may be treated so as to yield a lubricating oil having va pour test of 0 F. or lower. To obtain these latter `results it is necessary to chill or cool the oil, dissolved in the liquefied hydrocarbon gas, to a temperature considerably below the cold test desired, which in some cases may be as low at -30 to 40 F., to obtain a finished oil having a cold test of zero or lower.

These low temperatures are obtained in our process by a series of cooling operations, in which the oil to be treated, dissolved in the liquefied hydrocarbon gases, is subjected to heat exchange with the cold outgoing oil mixture in two stages, and may be thereafter further cooled by Vaporizing a portion of the liqueiied gases contained in the oil under treatment. Also, the liquefied hydrocarbon gases used maybe pre-cooled before mixing with the oil by maintaining a reduced pressure on the storage tanks holding the liqueiied gases.

The operation of our invention may be also carried out solely for the removal of parain wax' from oils without acid treatment, in which case the method employed is similar to the methy,

ing temperature of water, settling and removing the major portion of acid reaction products, together with a portion of the parailin wax content, centrifuging or filtering and removing the remaining portion of the acid reaction products and paraflin wax, and finally separating the liquefied hydrocarbon gas from the treated oil; or the parailin wax constituents may be removed from the oil without treatment with sulphuric acid.

'Ihe liquefied hydrocarbon gases Vemployed serve as a refrigerating agent as well as a solvent for the oil being treated, and may be any of those gases or mixtures thereof which can be extracted from oil well gases, or the gases sepa- -rated from natural gasoline stocks in stabilizing operations, such as propane, butane. trimethylene, tetramethylene, and isomers thereof which are hydrocarbons having a vapor pressure greater than atmospheric at ordinary atmospheric temperature, and which may also contain small percentages of ethane dissolved therein.

Processes for the treatment of petroleum oil with sulphuric acid or fuming sulphuric acid at low temperatures, employing low boiling temperature liquids as a solvent for the oil and as a refrigerating agent, are known in the art, such as described in our issued United States PatentsI #1,710,143, #1,710,200, #1,710,201, and #1,810,- 068, which disclose methodsfor the treatment of various petroleum oils or distillates thereof at low temperatures, employing liquid sulphur dioxide and liquefied hydrocarbon gases.

Now we have discovered additional improvements thereto which are more specifically adapted for the treatment of lubricating .oil stocks containing paramn wax either in the crystalline or amorphous form, which result in the removal of the wax constituents, together with the simultaneous removal or the acid reaction products if acid has been used in the treatment, by a new system of iirst settling the acid treated oil dissolved in the solvent, at a temperature sufficiently low to maintain the wax content in a congealed form, by a continuous separating method, thereby removing the larger portion of 'the acid reaction products, together with a portion of the paramn wax, then removing the remaining portion of the acid reaction products4 and wax by filtration or centrifugal action.

An object oi' the invention is to provide a con'- tinuous system for the separation and removaL` of parailin wax from mineral oils.

Another object of the invention is to provide a continuous method for the production of lubricating oil stock by the extraction of paraiiln wax constituents, sulphur bearing hydrocarbons and unstable hydrocarbons from mineral oils.

Another object of the invention is to provide a direct cooling system whereby the agent used to reduce the viscosity of the oil under treatment 40 drawing in which there is illustrated a form of apparatus in which the invention may be performed.

In the drawing, 3 represents generally a tank for holding a supply of the oil to be treated,

such as a lubricating oil stock containing paraffin wax. Pipe I, controlled by valve 2, connects tank 3 to a source of supply, by means oi' which tank 3 may be maintained at any desired level. From tank 3 the oil is caused to flow through pipe 4 and into the inlet side of pump 6, the rate of flow being governed by operation of valve 5.

As the oil passes through pipe 4 it is continuously mixed with and is dissolved in a sumcient amount of liquefied hydrocarbon gases coming from liqueiied hydrocarbon gas tank I2 through pipe I3, pump I5, pipe IB and branch pipe I8, the rate or flow being governed by operation of valves I4, I1, I3 and pump I5. Pipe I3 is connected to pipe 4 near the inlet side of pump 6.

'Ihe quantity of liqueiled hydrocarbon gases which are introduced into the oil stream flowing through pipe 4 depends upon the composition and the viscosity of the oil under treatment; for low viscosity oils as little as one volume of the liquefied gases to ilve volumes of the oil may be used, and for high viscosity oil as much as five volumes of the liquefied gases to one volume of the oil may be used.

Pump 6 discharges the oil, dissolved inthe required quantity of liqueiled gases, through pipe 1, heat exchanger 3, pipe 3, and then through cooling coil I0. Cooling coil I0 is stationed in tank I I, which is provided with a safety valve 30. As the oil mixture passes through heat exchanger 8 it undergoes a heat exchange with the outgoing cooled, treated oil mixture, and is thereby cooled to a temperature of approximately 40 F. or lower, and is further cooled in cooling coil I0 to substantially the required treating temperature, which may be 0 F. or lower, depending upon the composition of the oil under treatment and the product desired. For certain oils carrying low paraffin wax content, or when it is desired to extract only the high temperature melting wax from the oil, the treatment may be carried out at any temperature ranging from 0 to 32 F.

The cooling of the. oil mixture passing through coil I0 is effected by heat exchange with the outgoing treated oil mixture, which may be cooled to any desired temperature, either above or below 0 F., by evaporation o! a portion of the liquefied gaseous content thereof, produced by maintaining a regulated vacuum on tank I I through vapor outlet pipe 33, and spraying the treated oil mixture through spray pipe 20 over coil I0. Vapor outlet pipe 33, controlled by valve 41, is connected to the inlet of compressor 33 through pipe 34. Spray pipe 20 is stationed in the upper section of tank II and is connected to pipe 2i, -which conveys the treated oil mixture from centrifuge 22 after ilnal separation of the paramn wax, or the paraiiin wax and acid reaction products.

The cooled oil mixture, at the required treating temperature, which may range from 32 to 0 F. or lower, passes from coil I0 through pipe 23 and into jet mixer 24. In jet mixer 24 the cooled oil mixtureis commingled with the required quantity of sulphuric acid or fuming sulphuric acid necessary to reilne the oil to the required degree, suoli` quantities depending upon the percentage of impurities inthe oil and the product desired. For lubricating oil stocks the quantity of acid may range from as low as four pounds to as high as seventy pounds per barrel of oil under treatment, and for white oil stocks as much as pounds or more may be required. Inthe treatment of oils requiring large amounts of sulphuric acid, two or -more treating operations may be employed.

The supply of sulphuric acid or fuming sulphuric acid used in the treating operation is maintained in acid tank 21, and is introduced into jet mixer 24 in a continuous stream iiow through pipe 25, controlled by valve 2G. Pipe 28, controlled by valve 29, connects acid tank 21 to a source of supply of sulphur-lc acid or ruining sulphuric acid not shown.

In order to eiect the acid treatment of the oil mixture in jet mixer 24 at a substantially uniform temperature, liquefied hydrocarbon gases, cooled to a temperature below that of the oil mixture, which may be as low as 20 F. or lower, are continuously introduced from tank 32 through pipe 30, controlled by valve 3|, into jet mixer 24, along with the acid, in quantities sutilcient to extract the heat of the chemical reaction of the acid on the oil. For this purpose a supply oi' liquefied hydrocarbon gases is maintained in tank 32, cooled to a temperature of approximately 20 F. or lower, by regulation of the vapor pressure in tank 32 through vapor outlet pipe 34, controlled by valve 35, and the operation of compressor 36 which is connected, on the inlet side to pipe 34. A pipe controlled by valve 9| is connected to tank 32 at the top for discharging non-condensible gases into the atmosphere.

The quantity of liquefied gases employed to extract the heat of the chemical reaction between the oil and acid may range from approximately tive to ten per cent by volume or higher, de-

pending upon the quantity of acid employed and the heat evolved by the treatment. In the treatment of certaingrades of oil this introduction of cool liquefied gases into the mixer may be eliminated, particularly when small amounts of acid are used, or when the treatment is conducted for the separation of parain wax without acid I treatment.

From jet mixer 24 the oil mixture and products of reaction pass through pipe 31 and into the inner compartment 39 of an insulated settling tank 38. A vapor pipe 40, controlled by valve 4I, connects inner compartment 39 at the top to pipe 42, controlled by valves 43 and 44. Pipe 42 connects settling tank 38 through pressure release Valve 98 to pipe 34, the vapor inlet to compressor 36, by means of which thel oil mixture entering the inner compartment may be further cooled by evaporation of a portion of the liquefied 20/ gaseous content of the oil mixture.

The pressure maintained in pipe 42 may be observed through pressure gauge 99.

The vaporized hydrocarbon gases evolved in the cooling and recovery operations, together with the 25 necessary supply of hydrocarbon gases employed for the treating operations, coming from a source not shown through pipe 63, controlled by valve 54, pass into pipe 34. l Pipe 34 is connected to the inlet side of compressor 36.v Compressor' 36 30 compresses the gases to the necessary degree for liquefaction, which may range from approximately 100 to 500 pounds, and discharges the compressed gases through pipe 52, controlled'by valve 5I, `and into condenser coil 55. In con- 35 denser coil 55 the heat of compression is extracted by a cooling fiuid, such as water, flowing through condenser box v56, and the hydrocarbon gases liquefied.

From condenser coil 55 the liquefied hydrocarbon gases pass through pipe 51, controlled by valve 58, and into tank I 2. The necessary quantity of liquefied hydrocarbon gases used for cooling the oil mixture during the acid treatment in jet mixer 24 is conveyed from tank I2 through pipe I6, controlled by valve I1, into tank 32, and cooled as heretofore described.

The acid treated oil mixture and products of reaction pass down through compartment 39 into the bottom section of settling tank 38, and then upward through the outer section of settling tank 38, whereby the major portions of the acid reaction products and paraiiin wax content settle to the bottom and collect in the lower section thereof, to which is attached a cylinder piston 55 pump 69. Pump 60 operates so as to discharge the acid reaction products and paraffin wax as they collect in the bottom of the settling tank through pressure regulating valve 6I, pipe 62 and into sludge storage tank 63. Storage tank 63 is provided with steam coil 68, by means of which the liquefied hydrocarbon gases retained by the separated reaction products 'are heated, vaporized and separated. The vaporized gases separated in sludge tank 63 pass ltherefrom through pipe 46, controlled by valve 45, into pipe 34, and are thereafter compressed, cooled and liquefied for reuse by compressor 36, as heretofore described.

The heat applied to the reaction products in tank 63 liquefles and separates these products into a top layer of liquefied parain wax and a bottom layer of acid reaction vvproducts or sludge. As the paraii'in wax accumulates in tank 63 it overflows through pipe 64 and collects in tank 75 65, and may be thereafter transferred to other storage through pipe 66, controlled by valve 61. The acid sludge which accumulates in tank 63 may be transferred to a sludge disposal system through pipe 69, controlled by valve 10. Tank 65 is provided with steam heating coil 85' so as to maintain the wax which accumulates therein in a fluid condition.

The acid treated oil mixture, separated from the maior portion of the acid reaction products and parailln wax in settling tank 38, overflows into trough 59 which is stationed in the upper section of tank 39, and passes therefrom through pipe 1I controlled by valve 1I' into centrifuge 22, wherein the remaining portion of the acid sludge and paraffin wax are separated from the oil mixture by centrifugal action, the separated products `passing out through pipe 13 and into tank 12; or the oil mixture, separated from the major portionA of the acid reaction products and paraffin wax or paraflin Wax content,'may be passed from pipe 1I into pipe aby opening valve a.' and closing valve 1I. From pipe a the oil mixture passes through filter b, wherein the remaining portion of the acid sludge and paraffin wax or paraiiln wax content is separated by filtration, the separated product passing into tank 12 through pan d and pipe e.

By means of steam coil 11 the separated wax .products may be heated and liquefied and then conducted to a storage not shown through pipe 18, controlled by valve 19, and the liquefied gases contained, therein vaporized, separated and returned to compressor 36 through pipes 48, 42 and 34, controlled by valves 43 and 44, to be liquefied for reuse.

The treated oil mixture, substantially free from acid reaction products and paraffin wax, passes from centrifuge 22 or filter b through pipe 2| and into tank II, wherein it is employed as a. cooling agent for the incoming oil mixture to be treated, as heretofore described. From tank II the treated oil mixture passes through pipe 14, heat exchanger 8, pipe 15, and into the inlet side of pump 16. Pump 16 discharges the treated oil mixture through pipe 82 and into finished oil tank 83, wherein the mixture is heated by means of steam coil 8l, and the liquefied gases vaporized and separated from the oil.

The vaporized gases separated from the treated oil in tank 83 pass through pipe 50, controlled by valve 49, pipe 34, and then into the inlet side of compressor 36, where they are compressed, cooled, liquefied and returned to the system for reuse.

The temperature of the liquefied hydrocarbon gases which collect in tank I2 may be lowered to any desired degree by maintaining a regulated reduced pressure in tank I2 through pipe 81, controlled by valve 86, pipe 81 being connected to pipe 34, the inlet to compressor 36.

The finished treated oil which collects in tank 83 is transferred to other storage not shown through pipe 84, controlled by valve 89, and may be thereafter subjected to other treatments known in the art, such as neutralization with caustic soda solution and treatment with a decolorizing agent, to produce a finished oil.

We claim:

1. In the process of reiining petroleum oil containing paraii'in wax, the steps which comprise, mixing the oil with liquefied hydrocarbon gases having a vapor pressure greater than atmospheric at ordinary atmospheric temperature, cooling the mixture to a temperature sumcient to congeal the wax content, treating the cooled mixture with sulphuric acid, passing the cooled acid treated mixture through a settling tank to thereby separate acid reaction products and high melting wax i'rom the oil mixture by settling, passing the oil mixture from the settling tank .and separating the remaining portion of the wax from the oil mixture.

2. In the process of reilning petroleum oil con. taining parafiln wax, as in claim 1, in which the remaining portion of the wax content, after settling, is separated from the oil mixture by centrifugal action.

3. In the process of reilning petroleum oil containing parailln wax, as in claim 1 in which the remaining portion of the wax content, after settling, is separated from the oil mixture by fil-v tration. 1

4. In the process of refining petroleu\m oil containing crystalline and amorphous wax, the steps which comprise, mixing the oil with liqueed hydrocarbon gases containing propane and butane as principal constituents, cooling the mixfrom the oil mixture by settling, passing the oil mixture from the settling tank and separating the remaining portion of the wax content.

5. In the process of refining petroleum oil containing crystalline and amorphous wax, as in claim 4, in which the remaining portion of the wax content, after settling, is separated from the oil mixtureby centrifugal action.

6. In the process of refining petroleum oil containing crystalline and amorphous wax, as in claim 4, in which the remaining portion of the wax content, after settling, is separated from the oil mixture by filtration.

JOHN C. BLACK. MARVIN L. CHAPPEIL.

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