Controlled release of additives in gas turbine lubricating compositions
A gas turbine lubricating composition comprises a first lubricating composition and a delivery system for delivering at least one additive to said first lubricating composition in a controlled, time-release manner, thereby converting said first lubricating composition to a second lubricating composition, different from said first lubricating composition. In one embodiment, the delivery system comprises a controlled release gel. A method of lubricating a gas turbine using such lubricating composition is also disclosed.
The disclosure relates to lubricating compositions for gas turbines and, more particularly to a delivery system for providing or replenishing one or more desired additives to such lubricating compositions.
A gas turbine is a device that uses a flow of hot combustion gas in a stream of compressed air to generate energy in the form of thrust, shaft power, and compressed air, in any combination. Air flowing into the gas turbine is compressed in an air compressor and fed, usually at very high speeds, into the combustion chamber where it is mixed with fuel and ignited. The gases from the combustion chamber are fed to the blades in the turbine, spinning the turbine shaft.
The main functions of a lubricating composition in a gas turbine are to cool and lubricate the metal surfaces. A good quality lubricating composition for a gas turbine will substantially prevent metal-to-metal contact and enable the turbine to operate at high efficiency over extended periods of time. As gas turbines become smaller and more efficient, the requirements of the lubricating composition become more demanding. Stability and efficiency at higher sheer forces, higher pressures, and higher temperatures are just some of the requirements of a gas turbine lubricating composition.
In addition, the gas turbines are often operated in extreme environments and exposed to changes in atmospheric pressure, changes in temperature, water, sea water, dust, and a host of other liquid and solid contaminants. Accordingly, there is an increasing need for gas turbine lubricants that provide improved oxidative and thermal stability, corrosion resistance, resistance to sludge and varnish formation, an ability of rapid separation of water and entrained air, resistance to foaming and good wear performance. These demanding needs continue to present a challenge. For example, it has been reported in the literature that a large percentage of oil systems in gas turbines show evidence of degradation, loss of oxidative stability and formation of sludge and/or varnish, even when in service for less than two years.
As the design of the gas turbine becomes more complex, it may be advantageous to tailor the properties of the lubricating composition to specific components of the turbine. Each of these components may require the lubricating composition to perform different functions and thus have an additive composition that is different from the lubricating composition used in other portion of the turbine. Being able to tailor the composition of the lubricant within the system would thus be advantageous.
SUMMARY OF THE DISCLOSUREThe disclosure provides a delivery system capable of incorporating or replenishing additives in lubricating oil and method of using such a system in a gas turbine.
In an exemplary embodiment, a method for lubricating metal to metal interfaces within a gas turbine comprises: (a) contacting a first lubricating composition with a delivery system, wherein the delivery system comprises at least one desired additive; (b) releasing the desired additives from the delivery system into the first lubricating composition resulting in the first lubricating composition changing into a second lubricating composition, wherein the second lubricating composition is different from the first lubricating composition; and (c) circulating the second lubricating composition within a gas turbine having metal to metal interfaces.
In another embodiment, the delivery system or systems comprises at least one additive selected from the group of detergents, dispersants, acids, bases, over based detergent, succinated polyolefins, viscosity modifiers, friction modifiers, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, antioxidants, antifoam agents, corrosion inhibitors, rust inhibitors, extreme pressure agents, anti-wear agents, seal swell agents, lubricity aids, anti-misting agents, and mixtures thereto.
In another embodiment, the delivery system comprises an additized controlled release gel.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the present disclosure, as claimed.
DETAILED DESCRIPTIONThe delivery system comprises at least one of liquids, solids, a controlled release additive gel, capsules (for example melamine or urea formaldehyde microencapsulation polymers), polymer bags (e.g. linear low density polyethylene), perforated sheets, baffles, injectors, polymers which are oil-permeable at elevated temperatures (as defined in U.S. Pat. No. 4,066,559), particles which are oil-insoluble but oil wettable (as defined in U.S. Pat. No. 5,478,463), oil-soluble solid polymers capable of functioning as viscosity improvers (as defined in U.S. Pat. No. 4,014,794), or mixtures thereof. In one embodiment the additive delivery system dissolves into the lubricating composition by bringing the additive delivery system into contact with the lubricating composition. The additives may be delivered to the lubricating composition by any method or process, such as by dissolving into the lubricating composition.
In general, additives in gas turbine lubricating compositions can become diminished and depleted over time. In one exemplary embodiment, the additive delivery system is specifically formulated to meet the desired performance requirements of a gas turbine application, or even for specific components of a gas turbine. In one preferred embodiment, the additive delivery system is used to increase the performance of a gas turbine lubricant composition by replenishing the depleted desired additive(s) or introducing new desired additive(s) to the composition. Thus the gas turbine lubricant composition can add and/or maintain consistent performance and/or prolong the useful life of the composition, as well as the useful life and reliability of the turbine utilizing the composition.
The additive delivery system is positioned at any location where the delivery system will be in direct or indirect contact with the lubricating composition. For example, if oil-soluble solid polymers are used as a delivery system, they may be delivered from within an oil filter. In another embodiment, it may be desired to place the delivery system in contact with the lubricating composition such as in a reservoir, or within a fluid by-pass loop. One or more locations in a line, loop and/or the lubricating system can contain the additive delivery system. Further, if more than one additive delivery system for the gas turbine lubricating composition is used the additive delivery system can be identical, similar and/or a different additive delivery system composition. It is advantageous to place the delivery system at a location where it can be readily accessed and replaced or replenished, if desired.
In one embodiment the properties imparted by the desired additives include one or more of dispersancy, antioxidancy, corrosion inhibition, wear prevention, scuffing prevention, pitting prevention including micro and macro pitting, friction modifying properties including increased and/or decreased friction coefficients, detergency, viscosity control using viscosity modifiers, foam control or mixtures thereof.
In one embodiment the first lubricating composition is changed into the second lubricating composition different from the first lubricating composition. Changing the first lubricating composition into the second lubricating composition may be attained by releasing the desired additives from a delivery system in an amount sufficient to provide a different ratio of additives. Modifying the ratio of additives by the addition the desired additives is obtained in one embodiment by adding or contacting the first lubricating composition with a delivery system composition of the desired additives and releasing those additives into the first lubricating composition. In this manner, different lubricating compositions containing different additives can be delivered to specific components of a gas turbine and tailored to the particular needs of that particular component.
In another embodiment the line, loop and/or the lubricating composition system contains two or more different additive delivery systems located at two or more locations. The different compositions of the additive delivery systems provide the first lubricating composition with desired additives to be control released to change to a second lubricating composition. In one embodiment, one first lubricating composition contacts multiple delivery systems resulting in changing the first lubricating composition into multiple second lubricating compositions. In another embodiment multiple first lubricating compositions contact multiple delivery systems resulting in changing the first lubricating compositions into multiple second lubricating compositions. Furthermore, if multiple delivery systems are employed, each can be configured to deliver one or more additives and can the other delivery systems being employed deliver the same or different additive(s).
In one embodiment, the delivery system(s) may be positioned within a container. For example, in one embodiment it may be desirable to provide a container to hold the additive delivery system, such as a housing, a canister or a structural mesh positioned where it will be in contact with the gas turbine lubricating composition, for example, a canister within a bypass loop. The necessary design feature for the container is that at least a portion of the additive delivery system is in contact with the gas turbine lubricating composition.
In one embodiment the delivery system is a controlled release gel. The gel comprises at least two components which, when combined, will form a gel. The gel forming components are selected from the group of detergents, dispersants, acids, bases, over based detergent, succinated polyolefins or mixtures thereof. The gel optionally, but preferably, contains at least one additive selected from the group of viscosity modifiers, friction modifiers, detergents, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, dispersants, antioxidants, antifoams, corrosion/rust inhibitors, extreme pressure/antiwear agents, seal swell agents, lubricity aids, antimisting agents, or mixtures thereof.
The controlled release gel needs to be in contact with the lubricating composition. In one embodiment the controlled release gel is in direct contact with the lubricating composition in the range of about 100% to about 1% of the lubricating composition in the system, and all ranges therebetween. In another embodiment the controlled release gel is in direct or indirect contact with the lubricating composition in the range of about 75% to about 25% of the lubricating composition in the system and in another embodiment the controlled release gel is in contact with the lubricating composition in the range of about 50% of the lubricating composition in the system. The controlled release gel may be added to the system by any known method depending on the total amount of gel that is desired to be released over time, the desired form of the controlled release gel (e.g. stiffness, consistency, homogeneity and the like), the desired overall dissolution of the gel, the desired release rates of a specific component, the desired mode of operation and/or any combinations of the above.
The release rate of the controlled release gel is determined primarily by the controlled release gel formulation. The release rate is also dependent on the mode of addition of the controlled release gel, the location of controlled release gel, flow rate of the lubricating composition, the form of the controlled release gel and the like. The controlled release gel is positioned in a location desirable for the specified and desirable dissolution rate of the controlled release gel components.
The formulation of the controlled release gel may be comprised of components that dissolve at different rates in the lubricating composition. Thus the gel would contain components that dissolve rapidly in the lubricating composition, or not at all. Those that do not dissolve would remain for the useful life of the lubricating composition while others would be consumed over time. The gel may be formulated to prove the desired dissolution characteristics under specified conditions, such as flow rate over the surface of the gel or temperature, for example. For example, the gel may in one embodiment be formulated to dissolve all components of the gel slowly in heated lubricating composition, to provide slow and selective release of the desired additives into the lubricating composition. These release rates can be optimized so that the desired gel component(s) are released over a substantial portion to all of the lubricating composition's useful life.
The gel can be used as is, without an inert carrier or a non additive matrix, such as a polymeric membrane or complicated mechanical systems needed in the prior art for achieving controlled release of additives over time.
In one embodiment, the gel is a mixture of two or more gel forming components and optionally at least one functional additive from the group mentioned above. The gel exists in a semi-solid state more like a solid than a liquid, see Parker, Dictionary of Scientific and Technical Terms, Fifth Edition, McGraw Hill, (1994); see, also, Larson, “The Structure and Rheology of Complex Fluids”, Chapter 5, Oxford University Press, New York, N.Y., (1999), each which is incorporated herein by reference. The rheological properties of a gel can be measured by small amplitude oscillatory shear testing. This technique measures the structural character of the gel and produces a term called the storage modulus, which represents storage of elastic energy, and the loss modulus, which represents the viscous dissipation of that energy. The ratio of the loss modulus/storage modulus, which is called the loss tangent, or “tan delta”, is >1 for materials that are liquid-like and <1 for materials that are solid-like. The controlled release gels have tan delta values in one embodiment of about ≦0.75, in another embodiment of about ≦0.5 and in another embodiment of about ≦0.3.
In one embodiment, the additive gel comprises: (i) at least two additives selected from the group of detergents, dispersants, acids, bases, over based detergent, succinated polyolefins or mixtures thereof wherein the selected additives when combined form a gel; and (ii) optionally at least one additive selected from the group of viscosity modifiers, friction modifiers, detergents, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, dispersants, antioxidants, antifoams, corrosion/rust inhibitors, extreme pressure/antiwear agents, seal swell agents, lubricity aids, antimisting agents, or mixtures thereof. In one embodiment, components from group (i) comprise about 0.01% to about 95% of the total weight of the gel. In another embodiment, components from group (i) comprise about 0.1% to 80% of the total weight of the gel and in another embodiment they comprise 1% to about 50% of the total weight of the gel.
If present, the optional components from group (ii) are used in the appropriate percentages needed to supply the desired amount of additives to the lubricating composition, such as from about 0.1% to about 95%, or about 0.1% to 90%, or about 0.1% to about 80%, or about 0.5% to about 50% of the total weight of the gel.
The additive gel can in one embodiment comprise at least two additives selected from the group including detergents, dispersants, acids, bases, over based detergent, succinated polyolefins or mixtures thereof wherein such selected additives, when combined, form a gel. Any delivery system formed from the combination of two or more additives comprising detergents, dispersants, acids, bases, over based detergents, succinated polyolefins, and the like can be used to make the additive gel. Further in one embodiment the additive gel includes combining dispersants, or combining a dispersant and an acid, or combining a dispersant and a base, or a dispersant and an over based detergent, and the like.
In one embodiment, a category of gel which finds particular use are those in which gellation occurs through the combination of an overbased detergent and an ashless succinimide dispersant. In one embodiment, the ratio of the detergent to the dispersant is from about 10:1 to about 1:10, in another embodiment from about 5:1 to about 1:5, form about 4:1 to about 1:1 and in another embodiment from about 4:1 to about 2:1. In addition, the TBN of the overbased detergent, which participates in the gel-forming matrix, is normally at least 200, more typically at 300-1,000 and most typically 350 to 650. Where mixtures of overbased detergents are used, at least one should have a TBN value within these ranges. However, the average TBN of these mixtures may also correspond to these values.
The dispersant includes dispersants; ashless type dispersants such as Mannich dispersants; polymeric dispersants; carboxylic dispersants; amine dispersants, high molecular weight (i.e., at least 12 carbon atoms) esters and the like; esterfied maleic anhydride styrene copolymers; maleated ethylene diene monomer copolymers; surfactants; emulsifiers; functionalized derivatives of each component listed herein and the like; and combinations and mixtures thereof. The dispersant may be used alone or in combination. In one embodiment the preferred dispersant is polyisobutenyl succinimide dispersant. The polyisobutenyl substitution on the succinimide can also be derived from so-called high reactive polyisobutene having greater than 70% terminal vinylidene groups.
The dispersant includes but is not limited to an ashless dispersant such as a polyisobutenyl succinimide and the like. Polyisobutenyl succinimide ashless dispersants are commercially-available products which are typically made by reacting together polyisobutylene having a number average molecular weight (“Mn”) of about 300 to 10,000 with maleic anhydride to form polyisobutenyl succinic anhydride (“PIBSA”), and then reacting the product so obtained with a polyamine typically containing 1 to 10 ethylene amino groups per molecule.
Ashless type dispersants are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical ashless dispersants include N-substituted long chain alkenyl succinimides. Succinimide dispersants are more fully described in U.S. Pat. No. 4,234,435, which is incorporated herein by reference.
The Mannich dispersant are the reaction products of alkyl phenols in which the alkyl group contains at least about 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines).
Another class of dispersants is carboxylic dispersants. Examples of these “carboxylic dispersants” are described in U.S. Pat. No. 3,219,666.
Amine dispersants are reaction products of relatively high molecular weight aliphatic halides and amines, preferably polyalkylene polyamines. Examples thereof are described in U.S. Pat. No. 3,565,804.
Polymeric dispersants are interpolymers of oil-solubilizing monomers such as decyl methacrylate, vinyl decyl ether and high molecular weight olefins with monomers containing polar substituents, e.g., amino alkyl acrylates or acrylamides and poly-(oxyethylene)-substituted acrylates. Examples of polymer dispersants thereof are disclosed in the following U.S. Pat. Nos. 3,329,658, and 3,702,300.
Dispersants can also be post-treated by reaction with any of a variety of agents. Among these are urea, thiourea, dimercaptothiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds, and phosphorus compounds.
Dispersants can be used alone or in combination. The dispersant is present in the range from about 0 wt % or 0.01 wt % to about 95 wt % gel, in another embodiment in the range from about 1 wt % to about 70 wt % gel, and preferably in another embodiment in the range from about 5 wt % to about 50 wt % of the gel.
The detergents include overbased sulfonates, phenates, salicylates, carboxylates, overbased calcium sulfonate detergents which are commercially-available, overbased detergents containing metals such as Mg, Ba, Sr, Na, Ca and K and mixtures thereof and the like. Detergents are described, for example, in U.S. Pat. No. 5,484,542 the disclosure of which is incorporated herein by reference. The detergents may be used alone or in combination. The detergents are present in the range from about 0.05 wt % to about 25 wt % of the gel, in one embodiment in the range from about 0.1 wt % to about 15 wt % of the gel and in another embodiment in the range from about 1.0 wt % to about 5.0 wt % of the gel.
Typically the controlled release gel further contains at least one desired additive for controlled release into the lubricating composition. The additive gel desired components include viscosity modifier(s), friction modifier(s), detergent(s), cloud point depressant(s), pour point depressant(s), demulsifier(s), flow improver(s), anti static agent(s), dispersant(s), antioxidant(s), antifoam(s), corrosion/rust inhibitor(s), extreme pressure/antiwear agent(s), seal swell agent(s), lubricity aid(s), antimisting agent(s), and mixtures thereof; resulting in a controlled release gel that over time releases the desired additive(s) into a lubricating composition when the gel is contacted with the lubricating composition. The desired additive component is further determined by the lubricating composition formulation, performance characteristics, function and the like and what additive is desired to be added for depleted additives and/or added new depending on the desired functions.
Antioxidants include alkyl-substituted phenols such as 2,6-di-tertiary butyl-4-methyl phenol, phenate sulfides, phosphosulfurized terpenes, sulfurized esters, aromatic amines, diphenyl amines, alkylated diphenyl amines and hindered phenols, bis-nonylated diphenylamine, nonyl diphenylamine, octyl diphenylamine, bis-octylated diphenylamine, bis-decylated diphenylamine, decyl diphenylamine and mixtures thereof.
The antioxidant function includes sterically hindered phenols and includes but is not limited to 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol, 4-butyl-2,6-di-tert-butylphenol 2,6-di-tert-butylphenol, 4-pentyl-2-6-di-tert-butylphenol, 4-hexyl-2,6-di-tert-butylphenol, 4-heptyl-2,6-di-tert-butylphenol, 4-(2-ethylhexyl)-2,6-di-tert-butylphenol, 4-octyl-2,6-di-tert-butylphenol, 4-nonyl-2,6-di-tert-butylphenol, 4-decyl-2,6-di-tert-butylphenol, 4-undecyl-2,6-di-tert-butylphenol, 4-dodecyl-2,6-di-tert-butylphenol, 4-tridecyl-2,6-di-tert-butylphenol, 4-tetradecyl-2,6-di-tert-butylphenol, methylene-bridged sterically hindered phenols include but are not limited to 4,4-methylenebis(6-tert-butyl-o-cresol), 4,4-methylenebis(2-tert-amyl-o-cresol), 2,2-methylenebis(4-methyl-6-tert-butylphenol), 4,4-methylene-bis(2,6-di-tertbutylphenol) and mixtures thereof. Another example of an antioxidant is a hindered, ester-substituted phenol, which can be prepared by heating a 2,6-dialkylphenol with an acrylate ester under based conditions, such as aqueous KOH.
Antioxidants may be used alone or in combination. The antioxidants are typically present in the range of about 0 wt % or to about 30 wt %, in one embodiment in the range from about 0.05 wt % to 25 wt %, and in another embodiment in the range from about 0.1 wt % to about 15 wt % and in another embodiment in the range from about 1.0 wt % to about 5.0 wt % total weight of the additives.
The extreme pressure (“EP”)/anti-wear agents include a sulfur or chlorosulphur EP agent, a chlorinated hydrocarbon EP agent, or a phosphorus EP agent, or mixtures thereof. Examples of such EP agents are amine salts of phosphorus acid, chlorinated wax, organic sulfides and polysulfides, such as benzyldisulfide, bis-(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized sperm oil, sulfurized methyl ester of oleic acid sulfurized alkylphenol, sulfurized dipentene, sulfurized terpene, and sulfurized Diels-Alder adducts; phosphosulfurized hydrocarbons, such as the reaction product of phosphorus sulfide with turpentine or methyl oleate, phosphorus esters such as the dihydrocarbon and trihydrocarbon phosphate, i.e., dibutyl phosphate, diheptyl phosphate, dicyclohexyl phosphate, pentylphenyl phosphate; dipentylphenyl phosphate, tridecyl phosphate, distearyl phosphate and polypropylene substituted phenol phosphate, metal thiocarbamates, such as zinc dioctyldithiocarbamate and barium heptylphenol diacid, such as zinc dicyclohexyl phosphorodithioate and the zinc salts of a phosphorodithioic acid combination may be used and mixtures thereof. A particularly useful EP agent is dimethyloctylphosphonate.
In one embodiment the antiwear agent/extreme pressure agent comprises an amine salt of a phosphorus ester acid. The amine salt of a phosphorus ester acid includes phosphoric acid esters and salts thereof; dialkyldithiophosphoric acid esters and salts thereof; phosphites; and phosphorus-containing carboxylic esters, ethers, and amides; and mixtures thereof.
In one embodiment the phosphorus compound further comprises a sulfur atom in the molecule. In one embodiment the amine salt of the phosphorus compound is ashless, i.e., metal-free (prior to being mixed with other components).
The amines which may be suitable for use as the amine salt include primary amines, secondary amines, tertiary amines, and mixtures thereof. The amines include those with at least one hydrocarbyl group, or, in certain embodiments, two or three hydrocarbyl groups. The hydrocarbyl groups may contain about 2 to about 30 carbon atoms, or in other embodiments about 8 to about 26 or about 10 to about 20 or about 13 to about 19 carbon atoms.
Primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as such fatty amines as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine and oleylamine. Other useful fatty amines include commercially available fatty amines such as Armeen® amines (products available from Akzo Chemicals, Chicago, Ill.), such as Armeen® C, Armeen® O, Arneen® OL, Armeen® T, Armeen® HT, Armeen® S and Armeen® SD, wherein the letter designation relates to the fatty group, such as coco, oleyl, tallow, or stearyl groups.
Examples of suitable secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine and ethylamylamine. The secondary amines may be cyclic amines such as piperidine, piperazine and morpholine.
The amine may also be a tertiary-aliphatic primary amine. The aliphatic group in this case may be an alkyl group containing about 2 to about 30, or about 6 to about 26, or about 8 to about 24 carbon atoms. Tertiary alkyl amines include monoamines such as tert-butylamine, tert-hexylamine, 1-methyl-1-amino-cyclohexane, tert-octylamine, tert-decylamine, tert-dodecylamine, tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine, tert-tetracosanylamine, and tert-octacosanylamine.
Mixtures of amines may also be used in the embodiments. In one embodiment a useful mixture of amines is “Primene® 81R” and “Primene® JMT”81R (both produced and sold by Rohm & Haas), which are mixtures of C11 to C14 tertiary alkyl primary amines and C18 to C22 tertiary alkyl primary amines respectively.
Suitable hydrocarbyl amine salts of alkylphosphoric acid of the invention may be represented by the following formula (R4O)(R3O)PO2.(R5)(R6)(R7)NH+ wherein R3 and R4 are independently hydrogen or hydrocarbyl groups such as alkyl groups; for the phosphorus ester acid, at least one of R3 and R4 will be hydrocarbyl. R3 and R4 may contain about 4 to about 30, or about 8 to about 25, or about 10 to about 20, or about 13 to about 19 carbon atoms. R5, R6 and R7 may be independently hydrogen or hydrocarbyl groups, such as alkyl branched or linear alkyl chains with 1 to about 30, or about 4 to about 24, or about 6 to about 20, or about 10 to about 16 carbon atoms. These R5, R6 and R7 groups may be branched or linear groups, and in certain embodiments at least one, or alternatively two of R5, R6 and R7 are hydrogen. Examples of alkyl groups suitable for R5, R6 and R7 include butyl, sec-butyl, isobutyl, tert-butyl, pentyl, n-hexyl, sec-hexyl, n-octyl, 2-ethylhexyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, octadecenyl, nonadecyl, eicosyl groups and mixtures thereof.
In one embodiment the hydrocarbyl amine salt of an alkylphosphoric acid ester is the reaction product of a C14 to C18 alkylated phosphoric acid with Primene® 81R.
Similarly, hydrocarbyl amine salts of dialkyldithiophosphoric acid esters of the invention used in the rust inhibitor package may be represented by the formula (R4O)(R3O)PS2.(R5)(R6)(R7)NH+ wherein the various R groups are as defined above, although typically both R groups are hydrocarbyl or alkyl. Examples of hydrocarbyl amine salts of dialkyldithiophosphoric acid esters include the reaction product(s) of hexyl, heptyl or octyl or nonyl, 4-methyl-2-pentyl or 2-ethylhexyl, isopropyl dithiophosphoric acids with ethylene diamine, morpholine, or Primene® 81, and mixtures thereof.
In one embodiment the dithiophosphoric acid may be reacted with an epoxide or a glycol. This reaction product is further reacted with a phosphorus acid, anhydride, or lower ester. The epoxide includes an aliphatic epoxide or a styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octene oxide, dodecenyl oxide, styrene oxide and the like. In one embodiment the epoxide is propylene oxide. The glycols may be aliphatic glycols having from 1 to about 12, or from about 2 to about 6, or about 2 to about 3 carbon atoms. The dithiophosphoric acids, glycols, epoxides, inorganic phosphorus reagents and methods of reacting the same are described in U.S. Pat. Nos. 3,197,405 and 3,544,465. The resulting acids may then be salted with amines. An example of suitable dithiophosphoric acid is prepared by adding phosphorus pentoxide (about 64 grams) at about 58° C. over a period of about 45 minutes to about 514 grams of hydroxypropyl O,O-di(4-methyl-2-pentyl)phosphorodithioate (prepared by reacting di(4-methyl-2-pentyl)-phosphorodithioic acid with about 1.3 moles of propylene oxide at about 25° C.). The mixture is heated at about 75° C. for about 2.5 hours, mixed with a diatomaceous earth and filtered at about 70° C. The filtrate contains about 11.8% by weight phosphorus, about 15.2% by weight sulfur, and an acid number of 87 (bromophenol blue).
The EP/antiwear agent can be used alone or in combination. In one embodiment the EP/antiwear agents are present in the range of about 0.05 wt % to about 25 wt %, in one embodiment in the range from about 0.1 wt % to about 15 wt % and in another embodiment in the range from about 1.0 wt % to about 5.0 wt % total weight of the additives.
The antifoams include organic silicones such as poly dimethyl siloxane, poly ethyl siloxane, polydiethyl siloxane, polyacrylates and polymethacrylates, trimethyl-trifluoro-propylmethyl siloxane and the like. The antifoams additives may be used alone or in combination. The antifoams can be used in amounts necessary to provide the desired benefit and functionality, and specific concentrations for each additive is well within the skill of the ordinary artisan.
The viscosity modifier provides both viscosity improving properties and dispersant properties. Examples of dispersant-viscosity modifiers include vinyl pyridine, N-vinyl pyrrolidone and N,N′-dimethylaminoethyl methacrylate are examples of nitrogen-containing monomers and the like. Polyacrylates obtained from the polymerization or copolymerization of one or more alkyl acrylates also are useful as viscosity modifiers.
Functionalized polymers can also be used as viscosity modifiers. Among the common classes of such polymers are olefin copolymers and acrylate or methacrylate copolymers. Functionalized olefin copolymers can be, for instance, interpolymers of ethylene and propylene which are grafted with an active monomer such as maleic anhydride and then derivatized with an alcohol or an amine. Other such copolymers are copolymers of ethylene and propylene which are reacted or grafted with nitrogen compounds. Derivatives of polyacrylate esters are well known as dispersant viscosity index modifiers additives. Dispersant acrylate or polymethacrylate viscosity modifiers such as Acryloid™ 985 or Viscoplex™ 6-054, from RohMax, are particularly useful. Solid, oil-soluble polymers such as the PIB (polyisobutylene), methacrylate, polyalkystyrene, ethylene/propylene and ethylene/propylene/1,4-hexadiene polymers and maleic anhydride-styrene interpolymer and derivatives thereof, can also be used as viscosity index improvers. The viscosity modifiers are known and commercially available.
The viscosity modifiers may be used alone or in combination. The viscosity modifiers are present in the range of about 0.05 wt % to about 25 wt %, and in one embodiment in the range from about 0.1 wt % to about 15 wt % and in another embodiment in the range from about 1.0 wt % to about 5.0 wt % total weight of the additives.
The friction modifiers include organo-molybdenum compounds, including molybdenum dithiocarbamates, molybdenum carboxylates, molybdenum amides, tungsten esters and fatty acid based materials, including those based on linoleic acid, oleic acid, including glycerol mono oleate (GMO), those based on stearic acid, and the like.
In one embodiment, the friction modifier is a phosphate ester or salt including a monohydrocarbyl, dihydrocarbyl or a trihydrocarbyl phosphate, wherein each hydrocarbyl group is saturated. In several embodiments, each hydrocarbyl group contains from about 8 to about 30, or from about 12 up to about 28, or from about 14 up to about 24, or from about 14 up to about 18 carbons atoms. In another embodiment, the hydrocarbyl groups are alkyl groups. Examples of hydrocarbyl groups include tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl groups and mixtures thereof.
In one embodiment, the phosphate salts may be prepared by reacting an acidic phosphate ester with an amine compound or a metallic base to form an amine or a metal salt. The amines may be monoamines or polyamines. Useful amines include those amines disclosed in U.S. Pat. No. 4,234,435 at Col. 21, line 4 to Col. 27, line 50. Useful amines include primary ether amines, such as those represented by the formula, R″(OR′)x—NH2, wherein R′ is a divalent alkylene group having about 2 to about 6 carbon atoms; x is a number from one to about 150, or from about one to about five, or one; and R″ is a hydrocarbyl group of about 5 to about 150 carbon atoms.
The phosphate salt may be derived from a polyamine. The polyamines include alkoxylated diamines, fatty polyamine diamines, alkylenepolyamines, hydroxy containing polyamines, condensed polyamines, arylpolyamines, and heterocyclic polyamines.
The metal salts of the phosphorus acid esters are prepared by the reaction of a metal base with the acidic phosphorus ester. The metal base may be any metal compound capable of forming a metal salt. Examples of metal bases include metal oxides, hydroxides, carbonates, borates, or the like. Suitable metals include alkali metals, alkaline earth metals and transition metals. In one embodiment, the metal is a Group IIA metal, such as calcium or magnesium, Group IIB metal, such as zinc, or a Group VIIB metal, such as manganese. Examples of metal compounds which may be reacted with the phosphorus acid include zinc hydroxide, zinc oxide, copper hydroxide or copper oxide.
In one embodiment, the friction modifier is a phosphite and may be a monohydrocarbyl, dihydrocarbyl or a trihydrocarbyl phosphite, wherein each hydrocarbyl group is saturated. In several embodiments each hydrocarbyl group independently contains from about 8 to about 30, or from about 12 up to about 28, or from about 14 up to about 24, or from about 14 up to about 18 carbons atoms. In one embodiment, the hydrocarbyl groups are alkyl groups. Examples of hydrocarbyl groups include tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl groups and mixtures thereof.
In one embodiment, the friction modifier is a fatty imidazoline comprising fatty substituents containing from 8 to about 30, or from about 12 to about 24 carbon atoms. The substituent may be saturated or unsaturated, preferably saturated. In one aspect, the fatty imidazoline may be prepared by reacting a fatty carboxylic acid with a polyalkylenepolyamine, such as those discussed above. A suitable fatty imidazoline includes those described in U.S. Pat. No. 6,482,777.
The friction modifiers can be used alone or in combination. The friction reducing agents can be used in amounts necessary to provide the desired benefit and functionality, and specific concentrations for each additive is well within the skill of the ordinary artisan.
The anti-misting agents include very high molecular weight (>100,000 Mn) polyolefins such as 1.5 Mn polyisobutylene (for example the material of the trades name Vistanex®), or polymers containing 2-(N-acrylamido), 2-methyl propane sulfonic acid (also known as AMPS), or derivatives thereof, and the like.
The anti-misting agents can be used alone or in combination. The anti-misting agents can be used in amounts necessary to provide the desired benefit and functionality, and specific concentrations for each additive is well within the skill of the ordinary artisan.
The corrosion inhibitors include alkylated succinic acids and anhydrides derivatives thereof, organo phosphonates and the like. The rust inhibitors may be used alone or in combination. The rust inhibitors are present in the range of about 0.05 wt % to about 25 wt %, and in one embodiment in the range from about 0.1 wt % to about 15 wt % and in another embodiment in the range from about 1.0 wt % to about 5.0 wt % total weight of the additives.
The metal deactivators include derivatives of benzotriazoles such as tolyltriazole, N,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(decyl)ar-methyl-1H-benzotriazole-1-methanamine, N,N-(undecyl)ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(dodecyl)ar-methyl-1H-benzotriazole-1-methanamine N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine and mixtures thereof. In one embodiment the metal deactivator is N,N-bis(1-ethylhexyl)ar-methyl-1H-benzotriazole-1-methanamine; 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles; 2-alkyldithiobenzothiazoles; 2-N,N-dialkyldithio-carbamoyl)benzothiazoles; 2,5-bis(alkyl-dithio)-1,3,4-thiadiazoles such as 2,5-bis(tert-octyldithio)-1,3,4-thiadiazole 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-decyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-undecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tetradecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-octadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole and mixtures thereof; 2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles; 2-alkydithio-5-mercapto thiadiazoles; and the like.
The metal deactivators may be used alone or in combination. The metal deactivators can be used in amounts necessary to provide the desired benefit and functionality, and specific concentrations for each additive is well within the skill of the ordinary artisan.
The demulsifiers include polyethylene and polypropylene oxide copolymers and the like. The demulsifiers may be used alone or in combination. The lubricity aids include glycerol mono oleate, sorbitan mono oleate and the like. The lubricity additives may be used alone or in combination. The flow improvers include ethylene vinyl acetate copolymers and the like. The flow improvers may be used alone or in combination. The cloud point depressants include alkylphenols and derivatives thereof, ethylene vinyl acetate copolymers and the like. The cloud point depressants may be used alone or in combination. The pour point depressants include alkylphenols and derivatives thereof, ethylene vinyl acetate copolymers and the like. The pour point depressant may be used alone or in combination. The seal swell agents include organo sulfur compounds such as thiophene, 3-(decyloxy)tetrahydro-1,1-dioxide, phthalates and the like. The seal swell agents may be used alone or in combination. These additives can be used in amounts necessary to provide the desired benefit and functionality, and specific concentrations for each additive is well within the skill of the ordinary artisan.
Optionally, other components can be added to the delivery system includes base stock oils, inert carriers, dyes, bacteriostatic agents, solid particulate additives, and the like so long as these components do not have a detrimental effect on the delivery system.
When the delivery system is a gel, typically the gel contains small amounts (about 5-40 wt %) of base stock oils, which include but are not limited to mineral-based, synthetic (including Fischer-Tropsch gas-to-liquid synthetic procedure as well as other gas-to-liquid oils) or mixtures thereof.
Optionally, an inert carrier can be used if desired. Furthermore, other active ingredients, which provide a beneficial and desired function, can also be included in the gel. In addition, solid, particulate additives such as the PTFE, MoS2 and graphite can also be included.
Optionally, dyes can be used and include halo-alkanes and the like. The dyes may be used alone or in combination. Optionally, bacteriostatic agents can be used and include formaldehyde, gluteraldehyde and derivatives, and the like. The bacteriostatic agents may be used alone or in combination. These additives can be used in amounts necessary to provide the desired benefit and functionality, and specific concentrations for each additive is well within the skill of the ordinary artisan.
The components are mixed together sequentially or all together to form a mixture. After mixing of the components of the gel, a cure may be required in order for gelation to occur. If a cure is required, it is typically done in the range of about 20° C. to about 165° C. for about 1 min to about 60 days, or about 50° C. to about 120° C. for about 1 to about 24 hours, or about 85° C. to about 115° C. for about 4 to about 12 hours.
EXAMPLESOne lubricant additive concentrate suited for use in gas turbine lubricating compositions herein provides diminished sludge and varnish formation without compromising oxidative stability and comprises a blended mixture of a phenolic antioxidant (preferably 2,6 di-tertiary butyl phenol), tolytriazole, dialkylaminomethylated tolytriazole and nonyl diphenyl amine. One or more of these preferred materials can be delivered herein from a gel for combination with other desired components in the gas turbine lubricating composition.
A gel is prepared from the following ingredients:
The gel is contacted with a lubricating compositions for a gas turbine having the following composition:
The example compositions are tested for varnish formation using the Nippon Oil Color (NOC) test for 1 week. The examples are also subjected to the Rotary Pressure Vessel Oxidation Test (RPVOT) in accordance with ASTM D2272. Results are reported in Table 1. The data in Table 1 indicates that the time release gel is effective in releasing sludge and varnish-reducing agents into the gas turbine lubricating composition.
Claims
1. A gas turbine lubricant composition comprising a first lubricating composition and a delivery system for delivering at least one additive to said first lubricating composition in a controlled, time-release manner, thereby converting said first lubricating composition to a second lubricating composition, wherein said second lubricating composition is different from said first lubricating composition.
2. The gas turbine lubricant composition of claim 1, wherein said delivery system comprises a gel.
3. The gas turbine lubricant composition of claim 2, wherein said gel comprises:
- (a) at least two additives selected from the group of detergents, dispersants, acids, bases, over based detergent, succinated polyolefins or mixtures thereof, wherein the selected additives when combined form a gel; and
- (b) optionally at least one additive selected from the group of viscosity modifiers, friction modifiers, detergents, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, dispersants, antioxidants, sludge reducing agents, varnish reducing agents, antifoams, corrosion/rust inhibitors, extreme pressure/antiwear agents, seal swell agents, lubricity aids, antimisting agents, or mixtures thereof.
4. The gas turbine lubricant composition of claim 3, wherein the gel comprises a combination of an overbased detergent and an ashless succinimide dispersant.
5. The gas turbine lubricant composition of claim 4, wherein the ratio of detergent to dispersant is within the range of 10:1 to 1:10.
6. The gas turbine lubricant composition of claim 3, wherein the gel comprises at least one additive selected from the group of viscosity modifiers, friction modifiers, detergents, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, dispersants, antioxidants, antifoams, corrosion/rust inhibitors, extreme pressure/antiwear agents, seal swell agents, lubricity aids, antimisting agents, or mixtures thereof.
7. The gas turbine lubricant composition of claim 6, wherein the components in the gel dissolve in the first lubricating composition at different rates.
8. A method comprising the step of lubricating a gas turbine with a lubricating composition, said lubricating composition comprising a first lubricating composition and a delivery system for delivering at least one additive to said first lubricating composition in a controlled, time-release manner, thereby converting said first lubricating composition to a second lubricating composition, wherein said second lubricating composition is different from said first lubricating composition.
9. The method of claim 8, wherein said delivery system comprises a gel.
10. The method of claim 9, wherein said gel comprises:
- (a) at least two additives selected from the group of detergents, dispersants, acids, bases, over based detergent, succinated polyolefins or mixtures thereof, wherein the selected additives when combined form a gel; and
- (b) optionally at least one additive selected from the group of viscosity modifiers, friction modifiers, detergents, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, dispersants, antioxidants, antifoams, corrosion/rust inhibitors, extreme pressure/antiwear agents, seal swell agents, lubricity aids, antimisting agents, or mixtures thereof.
11. The method of claim 10, wherein the gel comprises a combination of a overbased detergent and an ashless succinimide dispersant.
12. The method of claim 11, wherein the ratio of detergent to dispersant is within the range of 10:1 to 1:10.
13. The method of claim 10, wherein the gel comprises at least one additive selected from the group of viscosity modifiers, friction modifiers, detergents, cloud point depressants, pour point depressants, demulsifiers, flow improvers, anti static agents, dispersants, antioxidants, antifoams, corrosion/rust inhibitors, extreme pressure/antiwear agents, seal swell agents, lubricity aids, antimisting agents, or mixtures thereof.
14. The method of claim 13, wherein the components in the gel dissolve in the first lubricating composition at different rates.
15. A gas turbine lubricated with the lubricant composition of claim 1.
Type: Application
Filed: May 23, 2008
Publication Date: Nov 26, 2009
Inventors: Brent L. Brennan (Chesterfield, VA), Helen T. Ryan (London)
Application Number: 12/154,637
International Classification: C10M 169/04 (20060101); C10M 145/22 (20060101); C10M 133/44 (20060101);
