US2231168A - Steam cylinder oil and process of preparing the same - Google Patents

Description

Patented Feb. 11, 1941 STEAM CYLINDER OIL AND PROCESS OF PREPARING THE SAME Arthur Lazar, Berkeley, and Joseph V. Crenna,

Concord, Calif., assignors to Tide Water Associated Oil Company, San Francisco, Calif., a corporation of Delaware No Drawing. Original application June 11, 1937,

Serial No. 147,784. Divided and this application February 2,1939, Serial No. 254,310

3 Claims.

This invention relates to the treatment of lubricating oil to insure stability under conditions of high temperatures and pressures in the presence of steam and has for a particular ob ject the preparation of a lubricating oil especially adapted to function in the cylinders of steam engines.

In the manufacture of steam cylinder oils certain specifications must be strictly adhered to because of operating conditions peculiar to the use of such oils.

Steam cylinderoils may not be supplied to the walls of the pistons and cylinders of the engine in many of the well-known forms of lubrication, but are introduced to the cylinder with the steam in such fashion that they are finely divided by atomization, whereby they are spread evenly over the moving parts.

In the modern steam engine practice the temperature of the steam in the cylinder of the en gine when closed by the piston goes as high as 500 F., under its corresponding pressure, and under such conditions it is highly important not only that a proper distribution of the oil is assured,-but also that the stability of the oil is such as to resist decomposition, whereby undesirable deposits, such as coke, and the like, are eliminated. v

Oils which have a tendency to emulsify with steam are best suited for steam cylinder oils and heretofore it has been common practice to compound with a mineral oil a certain percentage of a fatty oil, such as tallow, which causes emulsification. Such fatty oil, or oils, usually represent up to 8% to 10% of the mineral oil, but in addition to being costly, are decomposed at high temperatures which do not affect the mineral oil hydrocarbons, thus forming free fatty acids which attack metals under such temperature conditions.

Although high viscosity oils are generally applicable to steam cylinder'lubrication, this factor is not necessarily limiting as the invention involves the preparation of an oil which will provide adequate lubrication while possessing an inherent quality of stability under severe conditions of high temperature and in the presence of steam.

This invention provides a way of insuring the stability of steam cylinder oils while emulsifying the same under operating conditions, which is preferably accomplished in the following manher.

As a base stock for steam cylinder oils it is preferred to select a lubricating oil which is composed mainly of saturated hydrocarbons, such oil, for example, being an asphaltic base, or mixed base, oil, which is highly refined by treatment with liquid sulphur dioxide, as in the Welllmown Edeleanu process, to remove unsaturated hydrocarbons, aromatics, etc. Such lubricating oil, thus treated, shows the greatest stability under high heat conditions, but, of course, a body of saturated hydrocarbons may also be prepared by extensive sulphuric acid treatment, or even distilled from certain stocks, such as Pennsylvania crudes.

It has been found, however, that certain oils of less saturated character can be stabilized by the processing method herein described. Such oils may include distillates from asphaltic or mixed base crudes, as well as lubricating oils obtained from such distillates by comparatively mild refining operations, such as the conventional acid treatment.

To the base lubricating oil is added a polyvalent metal soap, as lime or magnesium soap, of an organic acid, such for example as oleic acid, stearic acid, palmitic acid, naphthenic acids, or sulphonic acid, the proportion of such added soap ranging from very small percentages of the oil, e. g., .01% to .1% up to the limit of solubility of said soap in said oil.

The alkaline earth metals, calcium, strontium, barium, and magnesium, yield soaps with organic acids which exhibit suitable stabilizing qualifications. When such soaps of a stable nature are added to oils, the resistance of the lubricant to decomposition, particularly under the high temperatures encountered in steam cylinder lubrication and other services, is greatly improved, and as a feature necessary for steam cylinder lubrication we again emphasize the necessity of a stable compounded lubricant as heretofore outlined.

We have found that the alkaline earth metal soaps do not form incrustations in service and of these calcium and magnesium soaps are preferred for economical reasons. However, the soaps of cadmium, aluminum, zinc, lead, copper, chromium, manganese, iron, cobalt, nickel, tin and mercury, may also be used.

Any organic acid which will yield a polyvalent metal soap with suitable stabilizing properties, is applicable to the process; Fatty acids, for example, oleic, stearic, palmitic, and derivatives of the same, have been successfully employed.- 0f the fatty acids we prefer to use those of fourteen or more carbon atoms. Normally the more saturated acids, as stearic and palmitic, yield soaps which are less soluble in oil than the unsaturated acids, e. g., oleic, but a saturated acid of excellent solubility may be obtained through the hydrogenation of unsaturated acids of certain types.

To illustrate; unsaturated acids from. flsh oil when hydrogenated, yield acids which can be made into polyvalent metal soaps having superior oil solubility properties. The acids from fish oils may be obtained in large quantities by splitting the esters normally present therein.

Polyvalent metal soaps of the hydrogenated acids derived as above described are soluble in 011 up to 5 per cent by weight, and are very efllcient stabilizing agents.

Sulphonic acid soaps are yery soluble in oil.

Acids of this type which have been found particularly suitable, may be derived from the sulphonation of 80 to 200 seconds, Saybolt Universal 100 oils of asphaltic origin, or raflinates derived therefrom by the well known Edeleanu treatment with liquid sulphur dioxide. Also from the extracted portion of the Edeleanu treatment aromatic type 'sulphonic acids may be prepared, from which suitable polyvalent alkaline earth or other metal aromatic sulphonic acid soaps can be made for the described purpose.

Polyvalent metal soaps of the naphthenic acids are normally more oil soluble than those of the fatty acids, and are excellent stabilizing and emulsifying agents. of the naphthenates those of calcium, magnesium, tin, and aluminum are preferred.

Depending largely on the dgeree of emulsiilcation and the stabilizing influence desired, the content of soaps dissolved in the oil may vary from a minute amount up to the limit of oil solubility. The following table is illustrative of the solubilities of the calcium soaps in the oil.

Turn I Solubility in Solubility in oils of aspbaltic paraiilne oils origin Calcium sulphonate, 50% or more 50% or more. Calcium naphthenatc Calcium oleatc Calcium stearate.. Calcium palmitatm"; 0.1 0 max"... 0.3% max The above soaps are listed in the order of: Decreasing solubility in oil, Increasing qualifications as lubricant stabilizers, Decreasing emulsifying properties.

A table similar to the above can be prepared quite as stable.

Aluminum soaps of organic acids show excellent solubility in mineral oils of all types. However, when added in percentages in excess of about 2%, the compounded oils possess a stringy structure, which for our purposes is undesirable. The preferred range for aluminum soaps is between 0.01% up to 1.0% by weightof the oil.

In the preparation of lubricants we have also found that the solubility of the less soluble polyvalent metal soaps can be increased by the mixing therewith of a more soluble soap of polyvalent metals. For example, the solubility of calcium oleate can be tremendously increased by the simultaneous incorporation in the lubricant of a comparatively small percentage of a more soluble calcium or other polyvalent metal soap, such as calcium naphthenate or calcium sulphonate.

This is a particularly important feature when it is desired to permanently incorporate in the oil soaps of relatively low solubility. The following table ,clearly illustrates this feature, and it should be noted that the solubility of calcium oleate in the same oil.v and imder the same conditions has been increased 'manyfold by the addition of a small percentage of a more soluble soap.

TABLIII Solubility of calcium oleate in California lubricatina oil Per cent Calcium olea 1.0 .Calcium oleate+10% calcium naphthenate 2.5 Calcium oleate+20% calcium naphthenate..- 4.0 Calcium oleate+30% calcium naphthenate 7.0 Although in the above example calcium naphthenate has been shown because of its well known oil solubility feature, this in no way should be indicated. as a limitation on this feature, and a similar result is obtained by the use of other more soluble soaps, such as the polyvalent metal soap of sulphonic acid. I

In describing this invenion which is particlarly directed towards the manufacture of a steam cylinder oil of stable oil and soap characteristics,

-. advantageous to utilize stable soaps made from a mixture of acids. I

In order to provide the maximum stability to resist the high temperature conditions encountered, and still provide enough soap for proper lubrication in conjunction with steam or otherwise, such emulsiflable oil should contain a maximum quantity of the preferred soaps described herein.

The novel feature of mixing two or more soaps is utilized when it is desired toincrease the solubility of the more insoluble polyvalent metal soaps in oil over the maximum noted in Table I.

The following table is illustrative of the quantitles of polyvalent metal soaps normally added to the oil and the preferred range of soap content for the steam cylinder oils.

Tun: III

a Preferred Range mas Percent Percent Sulphonates Up to 5 0.01 to 2 N Upto5 0.01 to 1.0 UptolO, 0.0lto0.l Steal-ates Up to 0 8 0.01 to 0.1 Palmitates Up to 0 3-- 0.01 to 0.1

It is important in the application of the above ranges of soap content to lubricants to add just suilicient soap to give the desired stabilization properties. such as to give the desired emulsifying properties and prevent the formation of incrustations or deposits on the cylinder walls of the lubricated mechanism. In general the addition is so small that the amount of ash arising from its use as an emulsifier is too small to be determined analyti cally.

The use of soap results in a steam cylinder oil of unimpaired stability which emulsitles sumciently to get the desired distribution, the soaps being easily combined with the saturated hydrocarbons, due to their oil solubility.

Likewise, a steam cylinder oil having the required emulsifying properties may be prepared from oils which result from the distillation of a suitable crude stock and which may be naturally composed mainly of saturated hydrocarbons. For instance, residual oils of Pennsylvania origin when traces of oxides, or hydroxides, are added to the oil when heated, such oil develops the desired pronounced emulsifying properties. To such oils, an organic acid or acids not normally present in petroleum may be added, and the requisite amount of polyvalent metal oxide or hydroxide, to accomplish substantial neutralization of the oils, applied.

A preferred amount of polyvalent metal oxide or hydroxide, for example, magnesium oxide, or lime, or other alkaline earth oxide, or hydroxide, which may be added to such residual oil varies from 0.01% to 0.1%, and such is incorporated in the oil by intimate mixing at elevated temperatures, preferably about 300' E, and generally in excess of atmospheric temperatures. This oil may then be used as straight steam cylinder oil, or may be blended in amounts of from 10% to 20% with a body of a highly refined oil of high stability, such as the SO; treated oil previously described.

The soaps may be added directly to the oil, during agitation either mechanically or with air, and the oil heated to 200-300" F. The preferred method however, is to first dissolve the desired quantity of organic acid in the oil and slowly add a metallic oxide or hydroxide, of the polyvalent metals previously cited, heating preferably to about 300 F., and generally in excess of atmos- In steam cylinder oils the addition is pheric temperature, and agitating the mixture until neutralization of the free acid is substantially complete. In such manner the soap is more readily incorporated in the oil and excellent distribution and dispersion of the soap in the oil is accomplished. When prepared in this manner with excess quantities of acid and oxide the quantity of the soap which is retained in the oil represents the maximum of solubility. This oil may be used as is, or blended in amounts from 10% to 50% with additional quantities of suitable base oils.

vWhile it is unnecessary, the use of small amounts of an acidless fatty oil with the steam cylinder oils prepared as above described, has sometimes a beneficial eflect in lowering the surface tension, but the quantity used, from 0% to 3% is kept as low as possible and in any event is far less than the amount normally used in compounding steam cylinder oils.

This application is a division of our copendlng application Serial Number 147,784 flied June 11, 1937 which is a continuation in part of our copending applications, now Patents Nos.

2,084,531-2, dated June 22, 1937.

We claim:

1. A steam cylinder oil consisting mainly of saturated hydrocarbons substantially devoid of free organic acids, and containing a small percentage of a polyvalent metal soap of comparatively low solubility with a still smaller percentage of a more soluble polyvalent metal soap, the total percentage of the soaps being insuflicient to leave an appreciable deposit of ashwhen the mixture is injected into the cylinder of a steam engine.

2. The method of increasing the solubility of a relatively low soluble alkaline earth metal soap such as calcium oleate. in a steam cylinder lubricating oil, which consists in incorporating with the oil and soap a more soluble alkaline earth metal soap, such as calcium naphthenate, in amount less than the less soluble soap, the total amount of the two soaps together being between and 1% of the weight of the oil.

3. A lubricating oil containing up to one percent of a soap mixture consisting of calcium oleate and calcium naphthenate, the naphthenate being less than 40% of the weight of the oleate.

ARTHUR LAZ'AR. JOSEPH v. canmm