BR102014016759A2 - method for improving the dispersion capacity of asphaltene in a trunk piston marine engine, and use of a detergent system - Google Patents

Abstract

method for improving the dispersion capacity of asphaltene in a trunk piston marine engine, and use of a detergent system. a detergent system comprising (i) a tbn-C hyperbasic alkyl-substituted ca-hydroxybenzoate salt of less than 250, and (ii) a c -14 hyperbasic alkyl-c-substituted ca-hydroxybenzoate salt of tbn less than 250, the 18 wt% ratio of (ii) to (i) being greater than one, is used in a stem piston marine engine lubricant to improve its asphaltene dispersibility when lubricating a medium-speed, compression-driven marine engine powered by heavy fuel oil.

Description

"METHOD TO IMPROVE ASPHALTENE DISPERSION CAPACITY IN A TRUNK PISTON MARINE ENGINE, AND USE OF A DETERGENT SYSTEM" FIELD OF THE INVENTION

[0001] This invention relates to a method for improving the dispersion capacity of asphaltene in a trunk piston marine engine.

[0002] This invention also relates to the use of a detergent system to improve asphaltene dispersibility in a trunk piston marine engine.

This invention also relates to the use of a detergent system comprising a combination of hydroxybenzoates in a trunk piston marine engine lubricant composition for a medium-speed, four-stroke, compression-driven marine (diesel) engine for improve the performance of the asphaltene dispersibility of the composition.

BACKGROUND OF THE INVENTION

[0004] Trunk piston marine engines generally use Heavy Fuel Oil ('OCP') for offshore operations. Heavy Fuel Oil is the heaviest fraction of petroleum distillate and comprises a complex mixture of molecules including up to 15% asphaltenes, defined as the petroleum distillate fraction that is insoluble in an excess of aliphatic hydrocarbons (eg heptane), but which is soluble in aromatic solvents (eg toluene). Asphaltenes may enter the engine lubricant as contaminants or via the cylinder or fuel pumps and injectors, and asphaltene precipitation may then occur, manifested as 'black ink' or 'black sludge' in the engine. The presence of such carbonaceous deposits on a piston surface may act as an insulating layer, which may result in the formation of cracks then propagating through the piston. If a crack goes through the piston, hot combustion gases may enter the crankcase, possibly resulting in a crankcase explosion. It is therefore highly desirable for stem piston engine oils (‘TPEO's) to prevent or inhibit asphaltene precipitation.

EP-B-1992 678 describes stem piston engine oils which contain combinations of calcium salts of hyperbaric alkyl salicylic acid to improve wear properties. No mention is made of the dispersibility of asphaltene.

It has now been found that by the use of certain combinations of hydroxybenzoate in a TPEO, it is possible to achieve improved asphaltene dispersion properties.

SUMMARY OF THE INVENTION

A first aspect of the invention is a method for improving the dispersion capacity of asphaltene in a trunk piston marine engine, the method comprising lubricating the engine with a lubricating oil composition comprising a detergent system comprising (i) a TBN hyperbasic alkyl-substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 20-28 carbon atoms, and (ii) a TBN hyperbasic alkyl-substituted calcium hydroxybenzoate salt of less than 250, alkyl group which has 14-18 carbon atoms; the weight% Ca ratio of (ii) to (i) being greater than one.

A second aspect of the invention is the use of a detergent system which includes (i) a TBN hyperbasic alkyl substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 20-28 carbon atoms, in a lubricating oil composition for trunk piston marine engines for a medium-speed, compression-driven marine engine during engine operation, wherein the detergent system further comprises (ii) a lower TBN hyperbaric alkyl substituted calcium hydroxybenzoate salt than 250, alkyl group having 14-18 carbon atoms, the weight% Ca ratio of (ii) to (i) being greater than one, said use being for improving the performance of asphaltene dispersibility of composition.

A third aspect of the invention is the use of a detergent system including (i) a TBN hyperbasic alkyl substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 20-28 carbon atoms, in a lubricating oil composition for trunk piston marine engines for a medium-speed compression-driven marine engine during engine operation, fueled by heavy fuel oil, and its lubrication by composition, where the detergent system further comprises (ii) a TBN hyperbasic alkyl-substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 14-18 carbon atoms, the weight% Ca ratio of (ii) to (i) being greater than one, said use being to improve the performance of the asphaltene dispersion capacity of the composition compared to that of the analogous operation using a detergent system whose weight% Ca ratio is one or more. least and / or where (ii) has a TBN of 250 or greater.

[00011] In this report, the words and expressions, if and when used, have the meanings described below: “active ingredients” or “(i.a.)” refers to an additive material that is not diluent or solvent; "Understanding" or any cognate word specifies the presence of reported aspects, steps, or integers or components, but does not introduce the presence or addition of one or more other aspects, steps, integers, components or groups thereof; the terms "consists of" or "essentially consists of" or cognates may be enclosed within "comprises" or cognates, where "essentially consists of" allows the inclusion of substances that do not materially affect the characteristics of the composition to which it is applied ; "Larger amount" means 50 mass% or more of a composition, preferably 40 mass% or more of a composition, more preferably 30 mass% or more of a composition; "Smaller amount" means less than 50 mass% of a composition, preferably less than 40 mass% of a composition, more preferably less than 30 mass% of a composition;

“TBN” means total base number as measured by ASTM D2896.

Also, in this report, if and when used: “calcium content” is as measured by ASTM 4951; “Phosphorus content” is as measured by ASTM D5185; “Sulphated ash content” is as measured by ASTM D874; “Sulfur content” is as measured by ASTM D2622; "KV100" means kinematic viscosity at 100 ° C as measured by ASTM D445.

Thus, it will be understood that various components used, essential as well as ideal and common, may react under conditions of formulation, storage or use and that the invention also provides the product obtainable or obtained as a result of any such reaction.

In addition, it is understood that any higher or lower quantity, range limit or ratio reported herein may be independently combined.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the invention will now be discussed in more detail below.

OIL LUBRICANT VISCOSITY

The trunk piston marine engine lubricating oil composition of the invention comprises a larger amount of a lubricating viscosity oil. Which may be in the viscosity range of light distilled mineral oils to heavy lubricating oils. Such oil may be referred to as a base oil. Generally, the viscosity of the oil is in the range of 2 to 40 mm2 / s as measured at 100 ° C. The oil may be a natural or a synthetic oil.

Natural oils include animal and vegetable oils (eg castor oil, lard oil); liquid petroleum and hydrorefined oils, solvent-treated or acid-treated mineral oils of the paraffinic, naphthenic and mixed paraffinic types. Coal or shale-derived lubricating viscosity oils may also be used.

Synthetic lubricating oils include hydrocarbon oils and halo substituted hydrocarbon oils, such as polymerized and interpolymerized olefins (e.g. polybutylenes, polypropylenes, propylene isobutylene copolymers, chlorinated polybutylenes, poly (1-hexenes), poly ( 1-octenes), poly (1-decenes)); alkylbenzenes (e.g. dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di (2-ethyl) benzenes); polyphenyls (e.g. biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and derivatives, analogs and homologues thereof.

Alkylene oxide polymers and interpolymers and derivatives thereof where terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic lubricating oils. These may be exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and alkyl and aryl ethers of polyoxyalkylene polymers (e.g. methyl polyisopropylene glycol ether having a molecular weight of 1000 or diphenyl polyethylene glycol ether having a molecular weight from 1000 to 1500); and mono- and polycarboxylic esters thereof, for example acetic acid esters, C3 -C8 fatty acid esters and tetraethylene glycol oxo acid diester.

Another suitable class of synthetic lubricating oils comprises dicarboxylic acid esters (eg, phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, zelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids) with a variety of alcohols (eg butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether propylene glycol). Specific examples of such esters include dibutyl adipate, di (2-ethylhexyl sebacate), di-n-hexyl fumarate, dioctyl sebacate, diisococtyl azelate, diisodecyl azelate, dioctyl phthalate , didecyl phthalate, dieicosyl sebacate, linoleic acid dimer 2-ethylhexyl diester, and the complex ester formed by the reaction of one mol of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethyl acid -hexanoic. Esters usable as synthetic oils include those made of C5 to C12 monocarboxylic acids and polyols such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.

Silicon based oils such as polyalkyl, polyaryl, polyalkoxy or polyaryloxy silicon oils and silicate oils comprise another class of usable synthetic oils; such oils include tetraethyl silicate, tetraisopropyl silicate, tetra- (2-ethylhexyl) silicate, tetra- (4-methyl-2-ethylhexyl) silicate, tetra- (p-tert-butyl-silicate) phenyl), hexa- (4-methyl-2-ethylhexyl) disiloxane, poly (methyl) siloxanes and poly (methylphenyl) siloxanes. Other synthetic lubricating oils include phosphorus-containing acid liquid esters (e.g., tricresyl phosphate, trioctyl phosphate, decyl phosphonic acid diethyl ester) and polymeric tetrahydrofurans.

Unrefined, refined and refined oils may be used in the lubricant of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retort operations; petroleum oil obtained directly from distillation; or ester oil obtained directly from esterification and used without further treatment, are unrefined oils. Refined oils are similar to unrefined oils except that the oil is further treated in one or more purification steps to improve one or more properties. Such many purification techniques, such as distillation, solvent extraction, acid or base extraction, filtration and percolation, are known to those skilled in the art. Refined oils are obtained by processes similar to those used to provide refined oils, but start with an oil that has already been used in service. Such refined oils are also known as reclaimed oils and are often subjected to further processing using techniques to remove used additives and oil degradation products.

[00024] The American Petroleum Institute (API) publication, Engine Oil Licensing and Certification System, Department of Industry Services, Fourteenth Edition, December 1996, Addendum 1, December 1998 categorizes base loads as follows: ) Group I base loads contain less than 90 percent saturated and / or more than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the methods specified in table El. (b) Group II base loads contain more than or equal to 90 per cent saturated and less than or equal to 0,03 per cent sulfur and have a viscosity index greater than or equal to 80 and less than than 120 using the test methods specified in Table El. c) Group III base loads contain more than or equal to 90 percent saturated and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120 using the methods specified in Table El. d) Group IV base charges are polyalphaolefins (PAO). e) Group V base loads include all other base loads not included in Groups I, II, III, or IV.

Analytical Methods for Base Charge are classified below (Table El): As an example, the present invention embodies Group II, Group III and Group IV base charges as well as base charges derived from synthesized hydrocarbons. by the Fischer-Tropsch process. In the Fischer-Tropsch process, synthesis gas containing carbon monoxide and hydrogen (or "singas") is first generated and then converted to hydrocarbons using a Fischer-Tropsch catalyst. These hydrocarbons typically require further processing in order to be usable as a base oil. For example, they may be by methods known in the art, hydroisomerized; hydrocracked and hydroisomerized; dewaxed; or hydroisomerized and dewaxed. Singas may be, for example, produced from a gas such as natural gas or other gaseous hydrocarbons by steam reforming, when the resulting base charge may be referred to as gas-to-liquid base oil ("GTL"); or from biomass gasification, where the resulting base charge may be referred to as biomass to liquid base oil ("BTL" or "BMTL"); or from coal gasification, where the resulting base charge may be referred to as coal-to-liquid base oil ("CTL").

Preferably, the lubricating viscosity oil in this invention contains 50 wt% or more of a base filler containing 50 wt% or more of a base filler containing more than or equal to 90% saturated and less than which is equal to or equal to 0,03% sulfur or a mixture thereof. Preferably, it contains 60, such as 70, 80 or 90 mass% or more of the defined base load or a mixture thereof. The lubricating viscosity oil may be substantially the entire defined base load or a mixture thereof.

More preferably, the lubricating viscosity oil in this invention contains 50 mass% or more of a base filler containing 50 mass% or more of a base filler containing less than 90% saturated and more than 0%. , 03% sulfur or a mixture thereof. Preferably, it contains 60, such as 70, 80 or 90 mass% or more of the defined base load or a mixture thereof. The lubricating viscosity oil may be substantially any defined base load or a mixture thereof.

The composition may have a TBN in the range of 20-60, preferably 25-55.

DETERGENT SYSTEM

A metal detergent is an additive based on so-called metal soaps, which are metal salts of acidic organic compounds, sometimes referred to as surfactants. They generally comprise a polar head with a long hydrophobic tail. Hyperbaric metal detergents, which comprise neutralized metal detergents such as the outer layer of a metal base micelle (e.g. carbonate), may be provided by including large amounts of metal base by reacting an excess of a base metal base such as as an oxide or hydroxide, with an acid gas such as carbon dioxide.

In the present invention, the detergents (i) and (ii) of the invention are hyperbaric alkyl substituted calcium hydroxybenzoate salts, preferably alkyl substituted calcium salicylate salts.

A salicylate detergent of such a system typically has the structure shown: wherein R is a linear alkyl group. There may be more than one R group attached to the benzene ring. The COO- group may be in the ortho, meta or para position relative to the hydroxyl group; The ortho position is preferred. The R group may be in the ortho, meta or para position relative to the hydroxyl group.

In (i), R has 20-28, preferably 20-24, carbon atoms. In (ii), R has 14-18 carbon atoms. Each of (i) and (ii) may be a mixture.

Salicylic acids are typically prepared by carboxylation by the Kolbe-Schmitt process of phenoxides, in which case they will generally be obtained (usually in a diluent) in a mixture with non-carboxylated phenol. Salicylic acids may be unsulfurized or sulfurized, and may be chemically modified and / or contain additional substituents. Processes for sulfurization of an alkyl salicylic acid are well known to those skilled in the art and are described, for example, in US 2007/0027057.

The term "hyperbase" is generally used to describe metal detergents wherein the ratio of the number of equivalents of the metal portion to the number of equivalents of the acid portion is greater than one. The term "low base content" is used to describe metal detergents wherein the equivalent metal to acid portion ratio is greater than 1 to about 2.

The basicity of detergents may be expressed as a total base number (TBN). A total base number is the amount of acid required to neutralize all basicity of hyperbaric material. TBN can be measured using standard ASTM D2896 or an equivalent procedure. Each of the detergents, as specified, has a TBN below 250; for example, TBN is in the range of 60 to 250, preferably 150 to 250.

The weight% Ca ratio of (ii) to (i) is as specified greater than one, for example in the range 1 to 50, preferably 1 to 3.

The treatment rate of the detergent system contained in the lubricating oil composition may, for example, be in the range of 1 to 25, preferably 2 to 20, more preferably 5 to 18% by weight. COADITIVES

The lubricating oil composition of the invention may comprise other additives other than and additional to the detergent system. Such additional additives may, for example, include ashless dispersants, other metal detergents, anti-wear agents such as zinc dihydrocarbic dithiophosphates, antioxidants and demulsifiers. In some cases an ashless dispersant need not be provided.

It may be desirable, but not essential, to prepare one or more additive packages or concentrates comprising the additives, whereby the detergent system may be simultaneously added to the base oil to form the lubricating oil composition. Dissolving the additive package (s) in a lubricating oil may be facilitated by solvents and by mixing accompanied by gentle heating, but this is not essential. The additive package (s) will typically be formulated to contain the additive (s) in appropriate quantities to provide the desired concentration, and / or to perform the intended function in the final formulation when ) additive package (s) is / are combined with a predetermined amount of base oil. Accordingly, the detergent system according to the present invention may be mixed with small amounts of base oil or other compatible solvents together with other desirable additives to form additive packages containing active ingredients in an amount based on the package. of additives, for example from 2.5 to 90, preferably from 5 to 75, more preferably from 8 to 60% by weight of additives in appropriate proportions, the remainder being base oil.

Final formulations as a stem piston motor oil may typically contain 30, preferably 10 to 28, more preferably 12 to 24% by weight of additive package (s), the remainder being base oil.

The present invention is illustrated, but in no way limited to the following examples.

EXAMPLES

COMPONENTS

The following components were used: Detergent (ii): A: A TBN 225 alkyl salicylate calcium detergent whose alkyl group has 14-18 carbon atoms. B: a calcium alkyl salicylate detergent of TBN 350 and whose alkyl group has 14-18 carbon atoms. C: a TBN 64 calcium alkyl salicylate detergent whose alkyl group has 14-18 carbon atoms.

Detergent (i): A TBN 223 calcium alkyl salicylate detergent whose alkyl group has 20-24 carbon atoms [00046] Base oil I: solvent extracted API Group I base oil [00047] HFO : a heavy fuel oil (ISO-F-RMK 380) LUBRICANTS

Selections from the above components have been mixed to give a range of trunk piston marine engine lubricants. Some of the lubricants are examples of the invention; others are reference examples for comparison purposes. The tested lubricant compositions are shown in the tables below under the heading "Results." Each lubricant had a TBN of about 40. Each lubricant also contained the same amount of HFO.

TEST

Light Diffusion [00049] Test lubricants were evaluated for asphaltene dispersion capacity using light scattering according to the Focused Beam Reflectance Method (“FBRM”), which predicts asphaltene agglomeration and consequently sludge formation. black '.

[00050] The FBRM test method was described at the Ί- International Marine Engineering Symposium, Tokyo, 24 - 28 October 2005, and was published in 'The Benefits of Salicylate Detergents in TPEO Applications with a Variety of Base Stocks', Conference Procedures. Further details were described at the CIMAC Congress, Vienna, 21-24 May 2007 and published in the “Meeting of the Challenge of New Base Fluids for the Lubrication of Medium Speed Marine Engines - An Additive Approach” in the Congress Proceedings. In the latter it is described that by using the FBRM method it is possible to obtain quantitative results for asphaltene dispersion capacity which predicts the performance of base load based lubricant systems containing more than or less than 90% of saturated, and more than which is less than 0.03% sulfur. The prediction of relative performance obtained from the FBRM was confirmed by engine tests on marine diesel engines.

The FBRM probe contains fiber optic cables through which the laser light travels to reach the tip of the probe. At the tip, an optical device focuses the laser light at a small point. The optical device is rotated so that the focused beam sweeps a circular path between the probe window and the sample. As particles flow past the window, they intersect the sweeping path, giving back light scattered from individual particles.

[00052] The scanning laser beam travels much faster than particles; This means that the particles are effectively stationary. As the focused beam reaches an edge of the particle, the amount of back scattered light increases; the amount will decrease when the focused beam reaches the other edge of the particle.

[00053] The instrument measures the time of increased backscatter. The backscatter time period of a particle is multiplied by the sweep speed and the result is a distance or length of the string. A string length is a straight line between any two points on the edge of a particle. This is represented as a chord length distribution, a graph of the chord length numbers (particles) measured as a function of chord length dimensions in microns. As measurements are taken in real time, statistics for a distribution can be calculated and tracked. FBRM typically measures tens of thousands of strings per second, resulting in a robust distribution of number by string length. The method gives an absolute measure of the particle size distribution of asphaltene particles.

The Focusing Beam Reflectance Probe (FBRM), Lasentec D600L model, was supplied by Mettler Toledo, Leicester, UK. The instrument was used in a configuration to give a particle size resolution of 1 pm to 1 mm. FBRM data can be presented in various ways. Studies have suggested that average counts per second can be used as a quantitative determination of asphaltene dispersibility. This value is a function of both particle size and cluster level. In this patent application, the average count rate (over the entire size range) was monitored using a measurement time of 1 second per sample.

The test lubricant formulations were heated to 60 ° C and stirred at 400 rpm; when the temperature reached 60 ° C the FBRM probe was inserted into the sample. An aliquot of heavy fuel oil (10 wt%) was introduced into the stirring lubricant formulation using a four-blade stirrer (at 400 rpm). A value for the average counts per second was taken when the count rate had reached an equilibrium value (typically after 30 minutes). RESULTS

Light Diffusion [00056] FBRM test results are summarized in TABLE 1 below, where a lower particle count indicates better performance.

Example 1 is an example of the invention and Examples A-F are comparison examples.

RESULTS

The numbers in parentheses after salicylate are TBN's.

As shown above, the lowest Lasentec count is achieved by using Example 1 which is in accordance with the invention. (Lower particle counts indicate better performance.) CLAIMS

Claims (9)

A method for improving the dispersion capacity of asphaltene in a stem piston marine engine, the method comprising lubricating the engine with a lubricating oil composition comprising a detergent system comprising (i) a hydroxybenzoate salt of TBN hyperbasic alkyl-substituted calcium of less than 250, alkyl group having 20-28 carbon atoms, and (ii) a TBN hyperbasic alkyl-substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 14-25 carbon atoms. 18 carbon atoms; the weight ratio of Ca% of (ii) to (i) being greater than one. Method according to claim 1, characterized in that each of the hydroxybenzoates, (i) and (ii), is salicylate. Method according to claim 1 or 2, characterized in that the alkyl group (s) of (i) have 20-24 carbon atoms. Method according to any one of claims 1 to 3, characterized in that the composition has a TBN in the range of 20-60, preferably 25-55. Method according to any one of claims 1-4, characterized in that the weight ratio of Ca is in the range from 1 to 50, preferably 1 to 3. A method according to any one of claims 1 to 5, characterized in that the composition comprises an oil of a lubricating viscosity in greater quantity containing 50% by weight or more than a base filler containing less than 90% saturated and / or more than 0,3% sulfur. A method according to any one of claims 1 to 5, characterized in that the composition comprises an oil of a lubricating viscosity in greater quantity containing 50% by weight or more than a base filler containing more than or equal to 90% saturated and less than or equal to 0.03% sulfur. Use of a detergent system including (i) a TBN hyperbasic alkyl-substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 20-28 carbon atoms, characterized in that it is in a lubricating oil composition for trunk piston marine engines for a medium-speed compression-driven marine engine during engine operation, where the detergent system further comprises (ii) a TBN hyperbasic alkyl-substituted calcium hydroxybenzoate salt of less than 250, alkyl group having 14-18 carbon atoms, the weight% Ca ratio of (ii) to (i) being greater than one, said use being for improving the asphaltene dispersibility performance of the composition. 9. Use of a detergent system including (i) a hyperbasic alkyl-substituted calcium hydroxybenzoate salt of TBN less than 250, alkyl group having 20-28 carbon atoms, characterized in that it is in an oil composition trunk piston marine engine lubricant for a medium-speed compression-driven marine engine during engine operation, fueled by heavy fuel oil, and its lubrication by composition, where the detergent system further comprises (ii) a salt of TBN hyperbasic alkyl-substituted calcium hydroxybenzoate of less than 250, alkyl group having 14-18 carbon atoms, the weight% Ca ratio of (ii) to (i) being greater than one, said use being to improve the performance of the asphaltene dispersion capacity of the composition compared to that of the analogous operation using a detergent system whose weight% Ca ratio is one or less. or and / or where (ii) has a TBN of 250 or greater.