Patent Application
20170121632
In various example aspects, the invention relates to systems and methods for varnish abatement and removal from in-service lubricant in industrial lubricated systems e.g. turbines, compressors, injection moulding hydraulic systems. In certain aspects, the invention relates to removing degradation products (e.g., oxidation by-products) from in-service lubricating and hydraulic fluids and removing contaminant films from machine components. In yet further aspects, the invention relates to the addition of additives to the in-service lubricating and hydraulic fluids to restore various lubricant properties such as oxidation resistance and antifoaming characteristics.
A lubricant for a machine (e.g., motor oil) degrades over time. As the formation of degradation products (e.g., oxidation by-products) from the lubricants and machine components increases over time, due to, for example, machine usage and heat, the incidence of the formation of harmful varnish on critical machine components (e.g., bearings, seals, valves, and governor systems) increases.
Lubricating oils undergo thermal and mechanical stresses that cause their additives and basestock to degrade. This chemical process changes the original molecules that make up the lubricant into less stable and less soluble degradation by-products. These degradation by-products can exist in either a dissolved or suspended form depending upon the chemistry and temperature of the lubricant. When the by-products are in a suspended state, they are at risk of settling out of the lubricant and forming deposits in sensitive areas of critical lubrication or hydraulic systems. These deposits are also commonly referred to as sludge and varnish.
The varnish causing suspended materials can be removed to various extents via, for example, electrostatic separators, chemical and mechanical flushes or particle filters. The solubilized varnish causing materials can be removed by adsorption media such as ion exchange resins.
U.S. Patent Application Publication No. 2009/0001023 describes removing soluble degradation by-products in lubricating oils using a polystyrene resin. It was found however that the polystyrene resin could easily oxidize when stored at room temperature. In addition to creating a toxic amine gas, the oxidized resins created several performance and aesthetic problems.
U.S. Pat. No. 5,661,117, U.S. Pat. No. 6,358,895 and U.S. Patent Application Publication No. 2005/0077224 all discuss using an ion exchange resin process to remove degraded phosphate ester acids to prolong the life of phosphate ester fluids. It was found however that the polystyrene resin could easily oxidize when stored at room temperature. When oxidized resins were used to treat phosphate ester fluids, they had a negative impact on the fluid's resistivity. When the resistivity of the fluid drops below 5 GOhm-cm, the fluid is at risk of electrokinetic wear causing servo-valve malfunction.
U.S. Patent Application Publication No. 2011/0089114 discusses a process for absorbing and adsorbing oil degradation products from lubricating oils.
There exists a need in the art for a process for removing degradation by-products that does not have the limitations of the prior art.
In various example aspects, the invention is directed to methods of removing compounds from an in-service fluid and components in a lubricating system, comprising adding an amount of a solubility enhancer to the in-service fluid to form a mixture; and contacting the mixture with a medium having acrylamide or styrenic functionality to remove the compounds.
In other example aspects, the invention is directed to systems for removing compounds from an in-service fluid and components in a lubricating system, comprising: a medium circuit comprising a medium pump and a medium component, wherein the medium circuit recirculates the in-service fluid through a reservoir of the lubricating system; and a solubility enhancer reservoir arranged to dispense solubility enhancer to the reservoir.
The various aspects of the invention will be more readily understood from the detailed description presented below and in conjunction with the attached drawings, of which:
According to various example aspects, the invention is directed to systems and methods for varnish abatement and removal from in-service fluids and components in industrial lubricated systems. In the following description, numerous details are set forth. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without some or all of these specific details.
The systems and methods of the present invention provide numerous benefits as will become more apparent from the following description. Non-limiting examples of benefits include 1) cleaning working fluids and system components without having to stop or shut down operations; 2) reduction of maintenance and cost of particle filters; 3) removal of polar molecules than can further catalyze oxidation of the working fluid and removal of oxidative species that consume antioxidants thereby shortening the remaining useful life of the fluid; 4) reduction of the maintenance of a working fluid; and 5) significantly extending the life of a working lubricant e.g. by a factor>2×. Additional benefits and uses of the systems and methods of the invention will become apparent to those of ordinary skill in the art.
As further shown in
In accordance with various example aspects of methods of the invention, during operation, in-service lubricant may be passed through the medium 135 for a period of time (e.g., about 30 minutes to about 4 hours, more particularly, for about 2 hours) during a pre-conditioning. The in-service lubricant can be drawn from the lubricant reservoir 125 by pump 140 and continuously passed through the medium 135 where the fluid exits the medium 135 and flows back to the lubricant reservoir 125. The flow rate of the fluid through the medium 135 is selected so as not to exceed the crushing pressure of the medium 135. The crushing pressure of an ion exchange medium may be, for example, about 50 psi to about 200 psi. Operating system pressures for the medium 135 may be about 20 psi to about 80 psi depending on the medium. For example, if the crushing pressure of the medium is 60 psi, then the operating pressure may be about 20 psi. According to certain aspects of the invention, the flow rate through the medium 135 may be about 0.5 gallon per minute to about 10 gallons per minute. The flow rate through the medium 135 may depend on the amount and type of contaminants in the in-service fluid, the medium selected, and the volume of the fluid in the lubricant tank 125. During pre-conditioning, as the lubricant in the system 100 passes through the medium 135, contaminants such as agglomerates and other impurities are removed (e.g., adsorbed, absorbed, filtered) from the in-service lubricant. In certain example aspects of the invention, the pre-conditioning may take about 1 to about 2 weeks to fully turn the system over. During this time, the medium 135 may remove active species that may otherwise consume additives in the solubility enhancer, such as antioxidants, and may partially reduce the Membrane Patch Colorimetry (“MPC”) value of the fluid in the system 100 as will be discussed in more detail below.
After pre-conditioning, the solubility enhancer 130 may be added to the lubricant reservoir 145. While the solubility enhancer 130 is added, fluid in the system 100 continues to flow through the medium 135 so that the medium 135 can continue to remove contaminants because there is continuous generation of oxidation compounds due to stressing of the lubricant in the system 100. According to example aspects of the invention, the solubility enhancer 130 can be added at a pre-determined flow rate, for example, about 1 gallon per minute to about 10 gallons per minute (depending on the volume of lubricant in the reservoir 125 and the amount of contaminants in the oil) in order to achieve good dispersion of the solubility enhancer within the lubricant. The solubility enhancer 130 may be added in an amount of about 5% to about 20% by volume of the solution. For example, a system having about 6000 gallons can be charged with the solubility enhancer at a flow rate of about 10 gpm. Larger or smaller systems can be charged at proportionally higher or lower flow rates.
It should be noted that engine 105 may continue to operate during the pre-conditioning and while the solubility enhancer is added to the system. Engine 105 may operate at a flow rate of about 1500 gallons per minute to about 1800 gallons per minute so that lubricant returning from the engine 105 to the lubricant reservoir 125 generates turbulence which provides good mixing of the added solubility enhancer 130 with the in-service lubricant. A mechanical mixer (not shown) may also be used in the lubricant tank 125 to mix the solubility enhancer 130 with the in-service lubricant.
Following the addition of the solubility enhancer 130 to the pre-conditioned lubricant, the resulting solution is circulated through the system 100 for a period of time, for example, the lifetime of the solution (e.g., about 10 to about 50 years), that is, or until the system 100 is taken offline or must be flushed and replaced with new lubricant. The medium 135 may last for about 4 to about 12 months, more particularly, about six (6) months, depending on the oxidation byproduct generation of the system 100. The oxidation byproduct generation may differ between systems. To establish when the medium 135 (e.g., ion exchange materials, filters, etc.) needs to be the changed, a quarterly MPC measurement can be performed. When two (2) consecutive MPC increases are recorded, the medium 135 may be changed.
According to further example aspects of the methods of the invention, as the solution of solubility enhancer 130 and pre-conditioned lubricant circulates through the system, it dissolves agglomerates and/or other particulates that have formed in the working fluid of the system 100. Additionally, when the mixture comes into contact with the turbine or compressor 105 and system components (e.g., filters, valves, governor systems, bearings, pipes, gears, seals, etc.), it dissolves deposits (e.g., vanish) thereon. More particularly, the addition of the solubility enhancer helps solubilize polar compounds that are formed due to oxidation of the working fluid and its additives. This allows for 1) polar compounds to remain in solution rather than to agglomerate, 2) solubilization of already suspended macromolecules and submicron particles made of agglomerated polar oxidation byproducts and 3) solubilization of already deposited material resulting in the cleaning of filters, valves, governor systems, bearings, pipes, gears, and seals among other components.
The solubility enhancer may include alkylated naphthalene, polyolesters, polyalphaolefin or alternatively polyalkylene glycol all of which may be soluble in mineral group I, II, III, IV and V oils. As varnish deposits in the system are solubilized, they release insoluble particles that are imbedded in the organic matrix that can be removed by particle filters. More particularly, not only material that is solubilized by the solvency enhancer is removed, but also solid particles (soot, wear particles, other particulate) are removed from the system.
The solubility enhancer may be formulated with antioxidants in order to restore the antioxidant properties of the working fluid. This addition further extends the life of the working fluid by replenishing its antioxidant properties. The antioxidants may include, for example, phenol and/or amine antioxidant compounds compatible with the working fluid being treated. The addition of antioxidants also minimizes the potential for accelerated consumption of antioxidants in the working fluid which may occur due to solubilization of active oxidative species. The solubilized active oxidative species may consume the antioxidants of the fluid and therefore, the replenishment of antioxidants from the solubility enhancer extends the usable life of the working fluid. In addition, the solubility enhancer can also be formulated with other functional additives to extend the useful life of the in-service fluid. For example, defoamers can be added to improve the foaming characteristics of the in-service fluid.
The selection of the medium 135 or media 210, 215, 220 may be customized based on the oxidation byproducts found in the in-service fluid. Selection of the medium may take into consideration the medium's contaminant removal performance (e.g., reduction of contaminants as measured by FT-IR and MPC), compatibility with the solubility enhancer (e.g., no reduction of media effectiveness due to the solubility enhancer), hydraulic performance (e.g., a low pressure drop across the media is preferred), and crushing pressure limitations (e.g., a high crushing pressure rating is preferred).
Additionally, passing the solubility enhanced fluid through the medium 135 or media 210, 215, 220 may be carried out in order to maintain the solubility capacity of the solvent and to remove the polar molecules and macromolecules from the system preventing the formation of deposits 1) when the working fluid in the system cools down and/or 2) the working fluid becomes saturated with degradation byproducts. The flow rates of the working fluid going through the medium 135 or media 210, 215, 220 may vary from about 0.5 gpm to about 10 gpm depending on, for example, the volume and type of medium or media being used and the viscosity of the fluid. In addition, different media can have different adsorption efficiencies as a function of flow rate, hence, the flow rate may be optimized for each medium 135 or media 210, 215, 220. The amount of material in the medium 135 or media 210, 215, 220 (e.g., ion exchange material) depends on the size of the total volume of working fluid being treated. For example, higher medium 135 or media 210, 215, 220 volumes can be accomplished by placing canisters containing the medium 135 or media 210, 215, 220, for example, in a parallel configuration (see
In various example aspects of methods according to the invention, the solubility enhancer can be used alone, that is, without a medium (or media). While addition of the solubility enhancer alone dissolves agglomerates and depositions in the working fluid, the use of the medium (or media) in the methods and systems can further extend the lifetime of the working fluid. According to various example aspects of the invention, the medium may be a selective adsorption medium, for example, an ion exchange medium that is styrenic or acrylic based, and weakly or strongly basic, and macroreticular or gel.
As shown in
In addition to the MPC value, another measure of oil condition is the Remaining Useful Life Evaluation Routine (RULER, ASTM D6971). RULER is a system and a process that utilizes linear sweep voltammetry that can determine the remaining useful life of the fluid, based on the percentage of remaining antioxidant package from the initial levels in the fresh oil.
The MPC and RULER values may be evaluated together to determine the condition of a working fluid and how much solubility enhancer may be needed for a system. For example, higher treatments levels of about 7 vol % to about 20 vol % of solubility enhancer per volume of solution are designed for particularly degraded working fluids as established by MPC values larger than dE=40 and/or a reduction in antioxidant levels to below about 25% (as per the RULER peak area, amperage as function of voltage as is measured in Linear Sweep Voltametry) as measured by RULER. Intermediate levels of treatment from about 4 vol % to about 6 vol % of solvent enhancer per volume of solution may be used for fluids with M PC values of dE=20-40 and/or RULER values of about 25% to about 50% of initial signal of antioxidants. Low treatment levels of about 2 vol % to about 4 vol % of solubility enhancer per volume of solution may be used for fluids with MPC values of dE=0-20 and/or RULER values in excess of about 75% of initial RULER signal.
The useful remaining life of the working fluid can be extended by adding antioxidant additive packages to the solubility enhancer.
In certain example aspects of the invention, a lubricant reservoir containing about 6,000 gallons of oil with a viscosity of ISO 32 may be treated with about 5% by volume of solubility enhancer (containing antioxidants) per volume of solution. The formula of the solubility enhancer may be, for example, 75-85 vol % alkylated naphthalene, 6-9 vol % oil soluble in high molecular weight phenolic antioxidant and 9-13 vol % of diphenyl amine. The adsorption media may be three disposable canisters with axial flow in a parallel flow arrangement (see FIG. 2). The canisters could contain about 0.4 cubic feet of ion exchange material each. The flow rates may be anywhere from about 1 to about 10 gpm depending on the hydraulic resistance characteristics of the media. The flow rate may be regulated to ensure that the pressure across the media (e.g., the pressure drop) is well below the crushing pressure. For example, an operating condition across a media canister of 7 inches in diameter and 36 inches in height containing 0.4 cubic feet of ion exchange material and having a crushing pressure of 70 psi would operate at about 30 psi and 2 gpm.
The synergy of using the solubility enhancer with the medium to remove varnish causing compounds from the oil is shown in
The solubility enhancers useful in the systems and methods of the invention may have, for example, aniline points of about −20° C. to about 50° C. Solubility enhancement treatments of about 3% to about 20% by volume per volume of solution may reduce the aniline point of a working fluid proportionally to the concentration of the solubility enhancer in the solution and neat aniline point. Target reductions of aniline points can be about 4° C. to about 15° C. The solubility enhancer should also be soluble in the in service fluid at ambient conditions. In other words, a solubility enhancer with a low aniline point may be too polar to be blended with an in-service oil without causing separation of the additive (e.g., antioxidants) from the in-service oil. This separation may cause additive extraction from the base stock that may result in early oxidation of the in-service fluid causing the opposite of the desired effect i.e. it may cause varnish formation. Solubility enhancers having viscosities in the range of in-service fluids may be selected in order to maintain the viscosity of the working fluid e.g. ISC)(40) 32 viscosity (cSt).
As discussed above, defoamers can be added to the solubility enhancer.
Varnish deposits were extracted from a particulate filter. These were dried and weighed and added to 1) oil treated and 2) not treated with solvency enhancer to achieve the same concentration. The resulting fluids were then treated with equal amounts of adsorption media. The material adsorbed (adsorbate) onto the adsorption media were in turn extracted and their relative concentration established via FT-IR spectroscopy. It was found that the resin that was treated with the solvency enhanced oil sample contained 53% more polar adsorbates than the oil sample without solvency enhancer. This indicates that the solvency enhanced fluid was better able to dissolve polar compounds found in the varnish which, in turn, made it available for the media to remove it. This demonstrates the primary claim that the combination of a solvency enhancement coupled with an adsorbate media can result in the greater removal of varnish forming compounds from a system that contains agglomerated varnish particles or varnish deposits.
The oils were heated for 48 hours at 60° C. to ensure a solubility steady state. The oil was then filtered with 10 and 5 micron filters to remove particulate matter that did not go into solution. The filtered oil was then circulated past a styrenic weak base macroreticular media. The medium was then extracted with a known methylene chloride volume. 400 microliter samples of the methylene chloride solutions were taken and allowed to air dry over a Fourier Transform Infrared Spectroscopy Attenuated Total Reflectance (FT-IR ATR) crystal. The intensity of the peak in the oxidation region of the spectra is dependent on the film thickness of the contaminants found in the methylene chloride solution. The results are summarized in the table in
This shows how the combination of a solubility enhancer with an adsorption medium can help clean critical equipment surfaces. This synergy can be achieved with the removal of the oxidation byproducts from the cleaning fluid by the adsorption media, thereby retaining the cleaning power of the solubility enhancer. In this particular experiment, an improvement in the removal of contaminants from the “system” of 53% by volume was achieved when comparing the solubility enhanced treated oil vs. the non-treated oil.
The foregoing description, for purposes of explanation, has been described with reference to specific examples. However, the illustrative discussions above are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The examples were chosen and described in order to best explain the principles of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various examples with various modifications as may be suited to the particular use contemplated.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US15/35383 | 6/11/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62010657 | Jun 2014 | US |
