US1976177A - Process for treating hydrocarbon oils - Google Patents

Description

@et 9, 31934. A..LAzAR PROCESS FOR TREATING HYDROCARBON OILS Filed May 9, 1931 @Smm Patented @et 9, iie

iwal?? PRCESS EUR HYDREUN Arthur Lazar, Associated, Caif., assigner to Associated @il Company, San Francisco, Calif., a corporation of California Application May 0, 1933i, Serial No. 536,220 9 Claims. (ci. ist) This invention relates to a process of treating oils and refers particularly to mineral oils heavier than kerosene, especially those oils comprising the range from transformer oils to lubricat-I ing oils.

It is the object of this invention to improve the stability of such mineral oils`by increasing their resistance to the effects of heat and oxygen.

J It is found that a properly applied and controlled oxidation step in the treatment of mineral oils greatly improves such stability and this process may be carried out with air in the presence of an adsorbent material, such as clay, in such a manner that all undesirable reaction products formed by the oxidation are removed at the same time or thereafter. This is quite contrary to ordinary rening methods, which have always emphasized the fact that air should be excluded Ias much as possible from all contact with theL 'inineral oils during treatment.

More specically, the literature and patents on clay treatment emphasize the necessity of eliminating the presence of air during' a decolorizing process, because it is stated that the presence of air produced oils of inferior color and outertone. Therefore, it has been proposed that such treatment be carried on in a closed system, or in an atmosphere of inert gas, especially when elevated temperatures are used.

Contrary to this conception and to the various methods known for the treating of hydrocarbon oils heretofore mentioned, the following described process has for its essential feature the deliberate oxidation of such oils under certain conditions for the production of finished oils of high stability,A for use where resistance to heat and oxidation is required.

Briefly, this process consists in oxidizing an oil with air, or other oxidizing agents, at elevated temperatures either in the presence of an adsorbent clay or thereafter treating with an adsorbent clay.

When hydrocarbon oils are blown with air in the presence of an adsorbent material, such as clay, the oxidation products which are formed are partially volatilized with the discharged air and partially adsorbed by the clay. In order to get the desired adsorption effect from the clay,

'it is necessary to maintain a temperature above 212 F., for an optimum time period since it is well known that most natural clays contain varying amounts of chemically combined water and that the adsorption reaction of the clay on the oil under treatment takes place during the heating process while the chemically combined water is split off.

It stands to reason that for oils of comparatively high volatility, as for example, transformer oils, it would be too costly to use very high temperatures during air blowing in the presence of an adsorbent, because this would cause high evaporation losses. A temperature of about 250 F. is found most suitable for this type of oil, but for oils of higher viscosity ranges and lower volatility it is possible to usemuch higher temperatures. lWhen using higher temperatures, for example temperatures up to 800 F., quantities of hydro-carbon vapors and vapors of oxidized products may be liberated which would be suflicient to form an explosive mixture with the air. For this reason it appears necessary to use a certain amount of steam together with 'the air in order to dilute the vapors and to remove them from the system more rapidly. By treating a hydrocarbon oil in this way, that is with the air, or with air and steam, in presence of an adsorbent, such as clay, the volatile products of oxidation together with a certain amount of light hydrocarbons distill over while the nonvolatile products of oxidation which are of more or less asphaltic or resinous nature are taken up by the adsorbent.

More specifically the hydrocarbon oil to be treated by this process may have been pretreated by any other well known `refining process. Itv might be mentioned at this time that besides the ordinary chemical treating method with sulphuric acid and sludge removal, physical treatment with selective solvents is in use. A treatment with liquid sulphur'dioxide is the method preferred at this time as it has been found that oils so treated possess certain properties of stability not found in acid treated oils. Liquid sulphur dioxide removes the bulk of the undesirable constituents in the form of a so-called extract while the portion of the oil which remains undissolved in the SO2 treatment and which is the so-called raflinate represents the desirable constituents. Such an SO2 raiiinate represents a particularly suitable mate- 100 rial for the process described in this specification, in so far as the greater part of the unstable compounds will have already been eliminated by the SO2 treatment. An oilwhich has been treated with liquid sulphur dioxide yields products of extraordinary high stability when finished according to the method described in the following paragraphs and as illustrated in the accompanying ow sheet of drawing.

The oil, which has previously been treated with 110 sulphuric acid, or preferably with liquid sulphur dioxide, and separated from the acid sludge or extract, is passed through a pipe 10 into a mixer 11 and agitated therein in any well known manner with the desired quantity of adsorbent material, such as clay, introduced through the funnel 12. The mixture of oil and clay is then forced by pump 12 through a set of heating coils 13 set in a furnace 14 wherein the temperature of the mixture is raised, varying from 250 F. to 800 F. depending on the stock being treated, and the mixture is then passed into a surge tank 15 equipped with a steam spray line 16 and an air spray line 17.

In surge tank 15, the heated mixture is subjected to the injection of air, or other equivalent oxidizing agent, through spray 17 for a period of time suilicient to obtain the desired oxidation effect on the undesired constituents of the oil and concurrently or thereafter steam is injected through the spray 16 to carry off undesired vaporized oxidation products, which pass through a line 18 and condenser 19 to a separator 20 wherein a separation of air, water and/or light reaction products takes place.

'I'he volume of throughput as well as the size of surge tank 15 permits the contacting time to be varied from a few minutes to several hours, and the contacting time and regulation of temperature during air, or steam, injection may also be controlled by means of a by-pass'line 21 and pump 22 whereby part, or all, of the mixture in surge tank 15 may be circulated through coils 13 and surge tank 15.

By thus oxidizing and removing oxidizable hydrocarbons at the temperatures employed, the stability of the treated oils at similar temperatures is greatly enhanced inasmuch as hydrocarbons which normally would become oxidized at such temperatures have been removed.

As a further precaution in removing all oxidized reaction products, the mixture of treated oil and clay may be passed in part, or in whole, from surge tank 15 through line 23 to a steam stripper 24 wherein the last trace of volatile. matter may be removed as overhead while the stripped mixture is passed through a cooler 25, and filter 26 ready for use.

While the process herein described is substantially a continuous process with, or without, the use of the recirculating line 21 and pump 22, the steps of oxidation, adsorption, reductionand cooling in the presence of clay may be carried out separately without affecting the desirable properties of the finished oil. 4

In a typical run with a lubricating oil distillate, a predetermined quantity of a mixture of oil and clay was circulated through coils 13 and surge tank 15 until a temperature of about 700 F. was reached and during the time of raising the temperature to this point air was continually injected through spray 17. As soon as the maximum desired temperature was reached, the air was cut oif as well as the heat applied to coils 13 and the circulation continued with injection of steam through spray 16 until the viscosity and flash is increased to the desired value by slow cooling, or to approximately 275 F., and thereafter the mixture is passed out through the stripper 24 without further steam treatment, cooler 25 and filter 26.

As a continuous process, oxidation, or oxidation and partial reduction may take place at the same time in surge tank 15 while circulating part of the mixture as described, or not, while final reduction and cooling in the presence of the clay may take place in the stripper 24.

Table Edeleanu process and herein described trentment Acid treatment and clay only Gravity Flash Fire Viscosity S. U. et F.. Viscosity S. U. at 210 F 49 Sulphur Color by reflected light (outertone).-.- Color by transmitted light Color stability 0. 35% Green. Cherry Red. Good.

One of the outstanding characteristics of oils treated by this process is exceedingly high stability under conditions of use. The lighter grade oils which have been treated by this process show an exceptionally long life as insulating oils. This is indicated as well by the standard testing methods as by their performance in actual service. While it was heretofore considered a very good result, i. e., if atransformer oil could meet a Snyder life test of 25 to 30 days, it is now possible with the procedure described above to manufacture transformer oils with a life test as high as 60 days. l

With regard to the heavier grade oils processed by the method described it can be said that they show an exceptionally good performance as 1ubricating oils for internal combustion engines, inasmuch as all the detrimental constituents are removed which otherwise are responsible for gummy deposits in the engine and the formation of excessive carbon.

I claim as my invention:

1. The process of treating a hydrocarbon oil which comprises: subjecting said oil to the action of air and introduced steam at a temperature between 350 and 800 F. but below the temperature of spontaneous combustion in the presence of an adsorbent clay.

2. The process of treating a hydrocarbon oil which comprises: subjecting said oil to the action of air and introduced steam at a temperature between 350 and 800 F. but below the temperature of spontaneous combustion in the presence of an adsorbent clay, cooling the mixture of oil and clay, and removing the adsorbent clay with its adsorbed matter.

3. The process ofv producing an improved lubricating oil which comprises: subjecting a treated lubricating distillate to the action of oxygen while being heated slowly to a temperature between 350 and 800 F. but below the temperature of spontaneous combustion sucient to Vaporize undesired products in the presence of adsorbent clay, cutting off applied heat Iand oxygen, introducing steam to remove undesired vaporized products, and removing the clay together with unvaporized undesired products.

4. The process of producing an improved luf4; bricating oil which comprises: subjecting a treated lubricating distillate to the action of oxygen while being heated to a temperature above 350 F. sufcient to oxidize part of the distillate and to vaporize undesired products in the presence of adsorbent clay, cutting oi applied heat and oxygen, introducing steam to slowly reduce being heated to a temperature above 350 F. sum- `cient to oxidize part of the distillate and to vaporize undesired products in the presence of adsorbent clay, cutting oi applied heat and oxy` gen, introducing steam to remove undesired vaporized products, and removing the clay together with unvaporized undesired products.

6. The process of producing an improved lubricating oil which comprises: subjecting a treated lubricating distillate to the action of oxygen while being heated to a temperature above 350 F. sumcient to oxidize part of the distillate and to vaporize undesired products Ain the presence of adsorbent clay, cutting oi applied heat and oxygen, introducing steam to reduce the temperature to approximately 275 F. and to remove undesired vaporized products, and removing the clay together with unvaporized undesired products.

7. A process for producing an improved lubricating oil which comprises: treating lubricating fractions with liquid sulphur dioxide, separating the undissolved portion from the dissolved portion, agitating the undissolved portion with air and steam at temperatures between 350 and 800 F. but below the temperature of spontaneous combustion in the presence of adsorbent clay, continuing the steam after the air has been cut oi until suicient hydrocarbons have been distilled overhead to bring the bottoms to a desired vis- .cosity, and removing the adsorbent material with its containedmatter from the oil.

8. The process of producing an improved insulating oil which comprises: subjecting a treated insulating oil, or distillate, to the action of oxygen while being heated to a temperature above 350 F. sumcient to oxidize part of the distillate and to vaporize undesirable products in the presence of adsorbent clay, and removing the clay together with unvaporized undesirable products.

.9. A process for producing an improved insulating oil which comprises: treating insulating oil fractions with liquid sulphur dioxide, separating the undissolved portion from the dissolved portion, agitating the undissolved portion with air at a temperature above 212 F. in the presence of adsorbent clay to eiect substantial oxidation of the oil, and removing the adsorbent material with its contained matter from the oil.

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