US2658823A - Fuel oil composition - Google Patents

Description

Patented Nov. 10, 1953 FUEL OIL COMPOSITION Harry J. Andress, Jr., Pitman, N. 3., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application August 28, 1951,

Serial No. 244,095

4 Claims. 1

This invention relates to compositions comprising a mixture of combustible hydrocarbon oils with addition agents. It is more particularly concerned with No. 2 fuel oils containing additives adapted to inhibit the appearance of sediment during prolonged storage periods.

As is well known to those skilled in the art, most fuel oils, although free from sediment initially, have a tendency to form sludge or sediment during prolonged storage periods. Thus, when such fuel oils are stored in tanks or drums, awaiting distribution or use, insoluble matter, generically referred to as sediment, is formed. This sediment is extremely detrimental to the efiicient operation of burners and engines utilizing these fuel oils. Such well-known difiiculties as screenclogging and nozzle-clogging are encountered.

Although the exact cause of such sedimentation in fuel oils is not clearly established, it has been postulated that it is due to oxidation of the fuel oil.

Therefore, in order to produce satisfactory fuel oils, it is necessary to solve two problems. The first problem, of course, is to prevent the formation of the sediment. The second one is to prevent the agglomeration of the insoluble matter which is formed into relatively large masses and to maintain it so that it will pass through the burner system without clogging. Proposed solutions for these problems have involved the use of two or more additives; one to prevent sedimentation and the other to prevent screen and nozzle clogging. Amino compounds, phenols, and the like have been proposed as additives of the former type. Examples of the additives for the latter purpose are metal salts of fatty acids, metal sulfonates, and partial esters of polyhydric alcohols.

It has now been found that certain specific metal salts will inhibit sedimentation in fuel oils and also maintain in suspension any sediment or sludge which is formed. It has now been discovered that the lower alkaline-earth metal salts of the acids derived from the sulfate paper pulp process, when added to fuel oils in minor amounts, effectively inhibit the formation of sediment therein.

Accordingly, it is a broad object of the present invention to provide improved fuel oils. Another object is to provide distillate fuel oils which have a reduced tendency to form sediment or sludge during prolonged storage periods. A further object is to provide a method for inhibiting sedimentation in distillate fuel oils and for preventing screen and nozzle clogging. A specific object is to provide a distillate fuel oil containing minor amounts of specific metal salts of the acids derived from the sulfate paper pulp process, namely the lower molecular weight alkaline-earth metal salts.

The present invention provides a distillate fuel oil containing a minor amount, sufficient to inhibit sludging and sedimentation during storage, of a neutral metal salt of tall oil, wherein the metal component is an alkaline-earth metal having a molecular weight of less than 87.

The fuel oils which are improved in accordance with the present invention are hydrocarbon fractions having an initial boiling point of at least about 300 F. and an end point not higher than about 750 R, and boiling substantially continuously throughout their distillation range. Such fuel oils are generally known as distillate fuel oils. It must be strictly understood, however, that this term is not restricted to straightrun distillate fractions. As is well known to those skilled in the art, the distillate fuel oils can be straight-run distillate fuel oils, catalytically or thermally cracked distillate fuel oils, or mixtures of straight run distillates, fuel oils, naphthas and the like, with cracked distillate stocks. Moreover, such fuel oils can be treated in accordance with well known commercial methods, such as, acid or caustic treatment, solvent refining, clay treatment, etc.

The distillate fuel oils are characterized by their relatively low viscosities, pour points, and the like. The principal property which characterizes the contemplated hydrocarbon fractions, however, is the distillation range. As mentioned hereinbefore, this range will lie between about 300 F. and about 750 F. Obviously, the distillation range of each individual fuel oil will cover a narrower range falling, nevertheless, within the above-specified limits. Likewise, each fuel oil will boil substantially continuously throughout its distillation range.

Especially preferred among the fuel oils contemplated herein are Nos. 1, 2, and 3 fuel oils used in domestic heating and as diesel fuel oils. The domestic heating oils generally conform to the specifications set forth in ASTM Specifications 13396-481. Specifications for diesel fuels are defined in AS'I'M specifications 13975-481. Such fuel oils have a tendency to form sediment or sludge during storage.

The salts utilizable in accordance with the present invention are the neutral metal salts of tall oil, wherein the metal component thereof is an alkaline-earth metal (Group IIA of the periodic chart) having a molecular weight less than 87, i. e., beryllium, magnesium, and calcium. The calcium and/or magnesium salts are especially preferred. These acids are commonly known as tall oil acids, or even merely as tall oil. Accordingly, throughout the present specification and in the claims, the term, tall oil, is used to denote these acids. The salts are identified as tallates, e. g., magnesium tallate or calcium tallate.

Tall oils are mixtures of fatty acids, rosin acids, and unsaponifiable matter derived from the sulfate process for pulping wood. During the process of pulping wood by the sulfate method (as distinguished from the sulfite method), the pulping liquor soon becomes contaminated with a soap. This soap can be removed by acidifying the liquors and skimming the water-insoluble organic material from the surface of the liquor. The skimmings are known to the art as crude tall oil, sometimes spelled talloel or talloil. The crude tall oil can be refined to various degrees, as by solvent-refining or by distillation. Crude tall oil and refined, or semi-refined, tall oil are available commercially from a number of sources. Tall oil is derived chiefly from domestic sources and from European sources, particularly from the Scandinavian countries. However, for the purposes of this invention, the preferred tall oils are the domestic tall'oils, particularly those derived from the pulping of Southern Pine.

As is well known to those skilled in the art, from the standpoint of chemical consti ution, tall oil contains a mixture of saturated and unsaturated fatty acids, rosin acids, and unsaponifiable matter. The fatty acids include stearic acid, oleic acid, linoleic acid, linolenic acid, and the like. Although other fatty acids are undoubtedly present, the fatty acid content is usually calculated in terms of oleic acid which is the predominant fatty acid component. The rosin acids are those acids which have the empirical formula, 0201-1300:. As is well known, they occur in many isomeric forms. However, abietic acid is the rosin acid most commonly found in tall oils. The relative acid content of tall oils will vary over a relatively wide range. This is due, in part, to

the particular source of the tall oil, i. e., the kind of wood from which it is derived. In addition,

by suitable blending and/or refining operations,

the manufacturers of tall oil can supply it in a wide range of acidic proportions. Regardless of the relative amounts of acids contained therein, any commercial tall oil is utilizable for the purposes of this invention. Typical chemical and physical properties of tall oils are set forth in Table I. It must be strictly understood, however, that such properties in and of themselves do not completely define tall oil. As is demonstrated hereinafter, salts of mixtures of fatty acids and rosin acids, which mixtures met the specifications of Table I, were entirely unsatisfactory for the purposes of the present invention. Accordingly, it is inaccurate to define tall oil by any means other than as a mixture of fatty acids, rosin acids, and unsaponifiable matter derived from the sulfate process of wood pulping. As those skilled in the art will readily appreciate, such a definition is embraced within the simple term, tall oil. I

TABLE I Specific gravity 25 C 0.9-1.1 Viscosity, S. S. U. 210 F 40-220 Color, Lovibond:

Yellow 25-60 Red 1-35 Moisture, per cent 0.1-3.0

4 TABLE 1 Continued Ash, per cent 0.03-1.0 Acid number -200 Saponification number 100-200 Fatty acids, per cent 30-70 Rosin acids, per cent 30-70 Unsaponifiables, per cent 1-12 Iodine value, Wijs -210 The alkaline-earth metal tallates can be made by any of the well-known methods for salt formation. Accordingly, the salt can be made by a double decomposition reaction between an alkalimetal tallate, e. g., sodium tallate, and a Watersoluble salt of beryllium; calcium or magnesium, such as calcium hydroxide, calcium chloride, calcium nitrate, magnesium chloride, magnesium sulfate, beryllium chloride, beryllium nitrate, and the like. A similar double decomposition reaction can be achieved by starting with an amine or, an ammonium salt of tall oil. Since crude tall oil is obtainable in the form of the sodium salt, i. e., unacidified, this crude salt can be used as the starting material to form the desired alkaline-earth metal. salt. As ha been mentioned hereinbefore, a mixture of calcium and ma nesium tallates can be used. This mixed salt can be prepared by reacting a mixture of watersoluble calcium and magnesium salts, e. g., calcium chloride and magnesium chloride, with the alkali-metal tallate. On the other hand, the mixture can be achieved by merely adding equivalent amounts of calcium tallate and magnesium tallate to the fuel oil, thus achieving the mixture, in situ. It is to be strictly understood, however, that other means of salt formation can be used, such as, for example, heating tall oil with a basic oxide like calcium oxide, with the elimination of water. This invention is not restricted to any particular method whereby the salt is formed.

In order to inhibit eifectively the formation of sediment or sludge in fuel oils, the alkaline-earth metal tallate is added thereto in concentrations varying between about 5 pounds per thousand barrels of oil and about 200 pounds per thousand barrels of oil. Preferably, the concentration varies between about 50 and about 200 pounds p-er thousand barrels. In terms of weight Per cent, based on the weight of the fuel oil, the concentrations vary, preferably, between about 0.01 per cent and about 0.1 per cent. These concentrations are also efiective to maintain in suspension any sludge or sediment which may be formed; thereby preventing screen and nozzle clogging.

The fuel oils of this invention can contain other additives for the purpose of achieving other results. Thus, for example, there can be present foam inhibitors, dyes or other coloring matter, color inhibitors, anti-rust agents, and ignition and burning quality improvers. Examples of such additives ar silicones, azo dyes, dinitropropane, amyl nitrate, metal sulfonates, and the like.

The following specific examples are for the purpose of illustrating the compositions of the present invention, and of exemplifying the specific nature thereof. It is to be strictly understood, however, that this invention is not to be limited to the particular tall oils and fuel oils, or to the operations and manipulations described therein. Other tall oils and fuel oils can be used, as set forth hereinbefore, as those skilled in the art will readily appreciate.

The four different commercial tall oils used to aesasca prepare the salts of the specific working examplesare identified herein as tall oil W, tall 011 X, tall oil Y, and tall oil Z. The pertinent characteristics of these tall oils are set forth in Table II.

TABLE II Tall oil Tall oil Tall oil Tall oil W X Y Z Specific gravity 0.98 0.99 0. 95-0. 97 0.976 Viscosity, S. S. U. at 210 F 116 165-205 50-70 119 Color, Lovibond:

Yellow 25-30 50 55 70 Red 10-15 25 30 20 Acid number 172 156-464 180-185 166 Saponification value 174 160-170 181-186 174 Rosin acids, percent 42. 2 4347 33-36 45. 4 Fatty acids, percent 49. 5 4650 5762 47. 8 Sterols, eta, percent 6-7 6- 5-7 6. 6 Iodine number, Wijs 159 150465 175-185 143 All of these tall oils were derived from domestic, wood pulping by the sulfate process. Tall oil W is a crude tall oil, Tall oil X is a refined tall oil. Tall oil Y is another refined tall oil which has been refined by a double distillation process. Tall oil Z is still another refined tall oil which has been refined by solvent extraction.

In all cases, the salts were prepared by reacting the tall oil acids with an aqueous solution of sodium hydroxide to form the sodium salt thereof. This salt was then reacted, by a double decomposition method, with an aqueous solution of a sulfate or halide of the desired metal, e. g., with calcium chloride or magnesium sulfate.

The tests used to determine the sedimentation characteristics of the fuel oils are the 212 F. storage test and the 110 F. storage test. In the 212 F. storage test, a 500-milli1iter sample of the fuel oil under test is placed in a convected oven maintained at 212 F., for a period of 24 hours. Then, the sample is removed from the oven and cooled for one hour. The cooled sample is filtered through a tared asbestos filter (Gooch crucible) "to remove the insoluble matter. The weight of such matter, in milligrams, is reported as the amount of sediment. The 110 F. storage test is conducted in a similar manner, with the exceptions that a temperature of 110 F. was used and that the test was run for 6-week and for 12-week periods.

Three different fuel oils have been used for the purpose of demonstrating the present invention. Fuel oil A is a blend of 70 per cent distillate stock derived from continuous catalytic cracking and 30 per cent air-caustic sweetened straight run TABLE 111 Fuel oil A Fuel oil B Fuel oil 0 Gravity, A. If. I 30.1 33. 4 33. 4 A S.T.M dlt F' I. B. P.-. 355 334 815 E. B. P 645 650 610 Sulfur, percent 0.87 0.73 0. 41 Carbon residue, percent 0. l5 0. 10 0. 16 Pour point, F +5 +5 0 Viscosity, centistokes at 100 MAGNESIUM SALTS Example 1 The magnesium salt of tall oil W was blended at various concentrations in portions of fuel oil A. The resultant blends were tested in the 212 F. and the 110 F. storage tests. Also, blends in fuel oil B were tested in the 212 F. and the 110 F, storage tests. Pertinent data for these tests are set forth in Table IV.

Example 2 Blends of various amounts of the magnesium salt of tall oil Y in fuel oils A and B were subjected to the 110 F. storage test. Test data are set forth in Table IV.

Example 3 Blends of fuel oil A containing 60 and 150 pounds, respectively, per thousand barrels of the magnesium salt of tall oil X were tested in the 212 F. and the 110 F. storage tests. Fuel oil B, containing the same salt at a concentration of 60 pounds per thousand barrels, was tested in the 110 F. storage test. Pertinent test data are set forth in Table IV.

Example 4 Blends of the magnesium salt of tall oil Z at different concentrations in fuel oils A, B, and C were tested in the 110 F. storage test. The results therefor are set forth in Table IV.

TABLE IV Weight of sediment, in milligrams Cone" Fuel oil A Fuel oil B Fuel oil 0 Salt lbs/1000 bblsnew. 110F. 110F.

6 wks. 12wks. 6 wks. 12 wks. 6 wks. 12 wks.

Blank 35 110 181 72 91 37 109 1. Mg salt oftall oilW 28 44 7 36 93 4 29 31 100 23 48 150 3 200 16 29 2. Mg salt of tall oil Y 25 31 50 11 19 28 42 6 14 150 24 44 3. Mg salt of tall oil X 60 v 7 43 24 5 23 5 4 2 Y 111 1s 1? 10 21 t tall i1 Z 4 Mg Sal of o 100 35 66 3 l8 6 1 13 200 '28 5 39 3 For purposes of comparison, blends of magnesium abietate and of magnesium oleate in fuel oils A and B were tested in the 212 F. and the 110 F. storage tests. The abietate approximates the salt of the rosin acid component of tall oil, and the oleate approximates the salt of the fatty acid component thereof. Additionally, blends containing a 50-50 weight per cent mixture of magnesium abietate and magnesium oleate were similarly tested. These latter blends approximate the accepted composition of the tall oil soap. Pertinent test data therefor are set forth in Table V.

TABLE V Weight of sediment, in milligrams Cone Fuel oil A Fuel oil B 1bs./ Salt 1000 bb1s 110 F. 110 F. 7

6 wks. fiwks.

Blank fuel oil 35 110 174 72 56 147 Mg abietatefln 60 26 78 160 33 80 105 150 31 98 173 Mg oleatcnnn 60 32 88 173 80 114 137 150 3 114 210 50-50 Mg oleate Mg abietate 60 30 76 176 59 87 112 150 27 98 169 It will be apparent from the foregoing that the magnesium salts of rosin acid and of fatty acids are ineffective for the purposes of the present invention. It will also be noted that a synthetic tallate produced by blending the magnesium salts of the component rosin and fatty acids is likewise ineffective. The magnesium tallates, on the other hand, effectively inhibit the formation of sediment.

CALCIUM SALTS Example 6 Blends of fuel oils A and B containing various amounts of the calcium salt of tall oil Y were tested in the 212 F. and the 110 F. storage tests. Pertinent test data therefor are set forth in Table A mixed salt comprising about 50 per cent by weight of the calcium salt of tall oil Y and about 50 per cent by weight ofthe magnesium salt of tall 011 Y was blended'in fuel oil A, at concentra- 8 tions M60 and 150 pounds per thousand barrels. These blends were subjected to the 212 F. and the 110 F. storage tests. A blend of the same mixed salt in fuel oil B, at a concentration of 60 pounds per thousand barrels was subjected to the same storage tests. for are set forth in Table VII.

TABLE VII Weight of sediment, in milligrams 1,6 7 Fuel oil A Fuel oil 13 Salt 1000 bb1s 110 F. 110 F.

6wks. Gwks. wks.

Blank fuel oil 35 110 174 72 56 147 Mixed Ca+Mg salt of tall oil Y 6O 10 113 3 l2 18 Example 8 For purposes of comparison, blends of calcium abietate and of calcium oleate in fuel oils A and B were tested in the 212 F. and the 110 F. storage tests. The abietate approximates the salt of the rosin acid component of tall oil, and the oleate approximates the salt of the fatty acid component thereof. In addition, blends containing a 50-50 Weight per cent mixture of calcium abietate and magnesium oleate were similarly tested. These latter blends approximate the accepted composition of the tall oil soap. Pertinent test data therefor are set forth in Table VIII.

TABLE VIII Weight of sediment, in milligrams Gone. Fuel oil A Fuel oil 13 a bb1s 110 F. 110 F.

6wks. wks' Gwks. lwka Blankfuel 0il 110 173 72 56 147 Ca abletate. 60 i8 66 97 150 154 220 Ca oleate 60 267 98 113 150 22 132 203 -50 Ca oleate v V +Mg abietate. 57 78 91 150 35 144 235 It will be apparent from the foregoing data that the calcium salts of rosin acid and of fatty acids are ineffective for the purposes of the present invention. It will also be noted that a synthetic tallate produced by blending the calcium salts of the component rosin and fatty acids is likewise ineffective. The calcium tallates and the mixed calcium and magnesium tallates, on the other hand, effectively inhibit the formation of sediment.

TALLATES COMPARED Example 9 The calcium, magnesium, barium and strontium salts, respectively, of tall 011 Y were blended in fuel oil B at various concentrations. The resultant blends were tested in the F. storage test. The pertinent results therefor are set forth -inTableIX.-- M

The test results there- TABLE IX Weight of sediment, milligrams Cone, Fuel oil B Salt lbs/1000 bbls.

6 weeks 12 weeks Blank fuel oil 45 91 Ca salt of tall oil Y 25 52 53 50 27 52 100 8 6 Mg salt of tall oil Y 25 31 65 50 ll 19 100 6 14 Blank fuel oil 56 67 Ba salt of tall oil Y 48 82 50 118 Blank fuel oil 42 Sr. salt of tall oil Y 25 65 50 65 100 61 It will be apparent from the foregoing data that, even within the relatively small group of the alkaline-earth metals, only those members lighter than strontium are useful as salt forming metals in the present invention. The barium and the strontium salts of tall oil, i. e., the heavier salts, are wholly ineffective. In fact, these salts tend to increase the amount of sludge and sediment formation, rather than to inhibit it, as the lighter metal salts do.

SLUDGE DISPERSION Example 10 Two test procedures were used to determine the screen clogging tendencies of fuel oils. In Test I, the fuel oil was circulated through a simulated domestic oil burner fuel delivery system comprising a 100-mesh external strainer, a fuel pump containing a 100-mesh basket-type screen, a one gallon per hour nozzle with a 100-mesh screen, and a fuel oil reservoir. The test oil was continuously cycled from the reservoir, through the system, and back to the reservoir. A sludge consisting, by weight, of 55 per cent water, 36 per cent fuel oil, 8 per cent organic matter, and one per cent rust and dirt Was added to the reservoir in daily portions of 50 cubic centimeters each, for the first five days of a ten-day test run. At the end of the test period, the weight of sludge deposited on the pump screen was determined.

Test II is identical to Test I, except that the test period was only of two days duration and the sludge was added, during the first day, in five 10-cubic centimeter portions directly in the fuel line a few inches before the pump suction. This test very closely simulates actual field conditions.

Blends of fuel oil A containing 50 pounds per TABLE X Ca salt of Mg salt of tall oil Z, g.

Blank an oil Z, g.

The foregoing specific working examples have demonstrated the specific effectiveness of tallate salts of the alkaline-earth metals heavier than strontium, for the inhibition of sedimentation and for the dispersion of sludge in distillate fuel oils. It will be apparent therefrom that the other alkaline-earth metal tallates and other calcium and magnesium salts are ineffective.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. A distillate fuel oil containing a minor amount, sufficient to inhibit sludging and sedimentation during storage, of a neutral metal salt of tall oil obtained from the sulfate process of wood pulping, wherein the metal component is an alkaline-earth metal having a molecular Weight less than 87.

2. A distillate fuel oil containing between about 25 pounds per thousand barrels and about 200 pounds per thousand barrels of a neutral magnesium salt of a tall oil obtained from the sulfate process of wood pulping.

3. A distillate fuel oil containing between about 25 pounds per thousand barrels and about 200 pounds per thousand barrels of a neutral ca1- cium salt of a tall oil obtained from the sulfate process of Wood pulping.

l. A distillate fuel oil containing between about 25 pounds per thousand barrels and about 200 pounds per thousand barrels of a neutral, mixed calcium and magnesium salt of a tail oil obtained from the sulfate process of wood pulping.

HARRY J. ANDRESS, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,733,620 Morrell Oct. 29, 1929 2,514,312 Christ July 4, 1950

Claims (1)

1. A DISTILLATE FUEL OIL CONTAINING A MINOR AMOUNT, SUFFICIENT TO INHIBIT SLUDGING AND SEDIMENTATION DURING STORAGE, OF A NEUTRAL METAL SALT OF TALL OIL OBTAINED FROM THE SULFATE PROCESS OF WOOD PULPING, WHEREIN THE METAL COMPONENT IS AN ALKALINE-EARTH METAL HAVING A MOLECLAR WEIGHT LESS THAN 87.