Related Applications

[0001] This application claims the benefit of U.S. Provisional Application No. 62/206,610, filed on August 18, 2015, the content of which is hereby incorporated by reference in its entirety.

Field

[0002] The present disclosure relates generally to a system and method for extending the life of lubricating fluids for machine components, and, more particularly, to a system and method for extending the life of wind turbine gear box oil.

Background

[0003] Failure of wind turbine gear boxes is among the highest cost for operating and maintaining wind turbines. Among the root causes for the failure of the gearbox are lubricant degradation and/or lubricant suitability for wind gearbox applications. A primary degradation mechanism of the lubricating oil is the depletion of Extreme Pressure (EP) and Anti-wear (AW) additives over time. In order to maintain the gearboxes, wind turbine farm operators change the oil either on a pre-established time (e.g. every 4 to 5 years) or by periodically monitoring the condition of the oil. The oil change is time consuming and expensive (oil costs, labor for up-tower servicing, equipment rental, etc.) All the costs need to be multiplied by the number of turbines in a turbine farm. The costs multiply even further if the entire gearbox needs to be exchanged or brought down for maintenance or refurbishing. All of these costs can be exacerbated due to wind turbines commonly being located in inaccessible locations such as off-shore settings.

[0004] Used oils are currently not replenishable. For example, as EP and AW additives are depleted they cannot be replaced in situ. There exists a need in the art for a process for extending the life of wind turbine gear box oil that does not have the limitations of the prior art.

Summary

The disclosure presents a system and method that can recognize the fact that gear oil is approximately 90% or more base stock and approximately 10% or less EP and AW additives, and that a substantial percentage of the oil volume is still in good condition and only the additives deplete over time during the operations of a wind turbine. This is especially true if 1) the filtration system is working properly to remove particulates, 2) breathers are functioning properly to minimize water ingression, and 3) good oil management strategies are maintained.

Definitions

[0005] The term "Inductively Coupled Plasma (ICP) elemental analysis" refers to a method used for the determination of the concentration of elements in a solution (e.g., the concentration of elements in a lubricant). Inductively coupled plasma atomic emission spectroscopy (ICP-AES) uses inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element.

[0006] The term "pour point" refers to the lowest temperature at which an oil will flow by gravity alone. The test is conducted as per ASTM D97/IP 15.

[0007] The term "additive package" refers to the combination of EP and AW additives with a carrier fluid. The term "concentrate" may appear interchangeably in the application to describe an "additive package."

[0008] The term "EP and AW additives" refers to additives that deliver phosphorus. The term "lubricate additives" may appear interchangeably in the application to describe "EP and AW additives." [0009] The term "effective amount of an additive package" refers to the amount of additive package required to replenish the EP and AW additives depleted from the wind turbine during operation, such that the replenished gear box oil reservoir of the wind turbine will contain EP and AW additives level within 10% (measured based on phosphorus level in ppm) of the initial EP and AW additives level (i.e. the EP and AW additives level in the gear box oil reservoir prior to the start of operation of the wind turbine).

Detailed Description

[0010] Examples of the present disclosure are directed to a system and method for extending the life of a wind turbine gear box oil. 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.

[0011] In some embodiments, the invention is directed to an additive package suitable for pouring into a wind turbine gear box oil up-tower. The additive package comprises additives, such as EP and AW additives, and a carrier fluid. The additives alone (without a carrier fluid) may be in a solid phase or may have a high viscosity, rendering them difficult to handle and/or pour up-tower. Accordingly, the additives and carrier fluid have been selected in such a way that they can be blended together to form a concentrate (also referred to herein as additive package). The concentrate will be characterized with the appropriate viscosity and additive concentration, to allow for ease of handling, pouring up-tower, and in-situ addition into the nacelle of the turbine. [0012] New oils functioning as carrier fluids have now been formulated in such a manner that they are compatible with subsequent EP and AW additives. For example, the carrier fluids may be selected from the group consisting of mineral oil, polyalphaolefin (PAO), polyalkylmethaacrylate synthetic base, synthetic lubricants, and mixtures thereof. The typical phosphorous additives can be of the ashless type (organo-metallic free). The EP and AW additives can be selected from the group consisting of blends of alkyl phosphates, amine neutralized organophosphric acid, alkyl phosphonates, and combinations thereof. In some embodiments, the carrier fluid may be present in the additive package at a concentration ranging from about 50% to about 70% (v/v), and the additives may be present in the additive package at a concentration ranging from about 30% to about 50% (v/v). For example, in some embodiments, the additive package may comprise from about 4000 ppm to about 8000 ppm phosphorus.

[0013] In some embodiments, the additive package may have a phosphorus level that is sufficient to replenish the level of phosphorus in the wind turbine gear box oil to the phosphorus level present in the wind turbine gear box oil prior to start of operations or within about 10% of the phosphorus level (calculated based on ppm of phosphorus) present in the wind turbine gear box oil prior to start of operations. In yet other embodiments, the additive package may have a phosphorus level that is sufficient to replenish the level of phosphorus in the wind turbine gear box oil to the phosphorus level present in the wind turbine gear box oil prior to start of operations or within about 10% of the phosphorus level (calculated based on ppm of phosphorus) present in the wind turbine gear box oil prior to start of operations for a period of at least five years through a plurality of remote injections. [0014] In some embodiments, the additive package may form a liquid blend of a mixture of additives and carrier fluid. The additive package may have a viscosity ranging from about 260 cSt to about 360 cSt at 40 °C. In comparison, the viscosity of the working fluid present in the gearbox oil reservoir of the wind turbine may be about 320 cSt at 40 °C. Thus, upon small additions of the additive package into the gearbox oil reservoir of the wind turbine (e.g., gallons or partial gallons), the viscosity of the working fluid present in the gearbox oil reservoir of the wind turbine remains within a tolerated viscosity range. For example, for a working fluid having a viscosity of 320 cSt at 40 °C, the tolerated viscosity range may be from about 288 cSt to about 352 cSt.

[0015] In some embodiments, the additive package (concentrate) may not have pour points below 30 °C, enabling injecting or pouring of the additive package into the gearbox oil reservoir.

[0016] Referring to Figure 1, in block 110, EP and AW additives may be selected in such a way that they can be blended with the carrier fluid up-tower to form a blended liquid mixture (i.e. an additive packages). In some embodiments, the EP and AW additives can be premixed into a carrier fluid with similar, equivalent, or identical composition as the wind turbine gear oil (e.g., group V base oil) to make a concentrate that can be blended up-tower at ambient conditions in the gearbox oil reservoir. In some embodiments, the EP and AW additives can be premixed into a carrier fluid at a composition that is different or more concentrated with additives as compared to the composition of the wind turbine gear oil so that a small volume of the additive package may be added to the wind turbine working oil to replenish to the depleted additives in the wind turbine gear oil reservoir without significantly impacting the physical or chemical characteristics of the working oil in the wind turbine gear oil reservoir (e.g. without modifying the viscosity of the working oil beyond tolerable fluctuations). The blending or mixing of the EP and AW additives with the carrier fluid may occur at a temperature greater than -10 °C for ease of handling.

[0017] In some embodiments, in accordance with block 120, the invention is directed to determining an effective amount of an additive package to add to existing working fluid (e.g., working oil) in a wind turbine. The amount and frequency of adding the additive package to the existing gear box oil is based on a predictive analytics model described in more detail with respect to Figure 2. The predictive analytics model accounts for one or more of oil condition monitoring tests, levels of phosphorus, oil formulation, initial concentration of additives used, additive consumption rate (also referred to as additive depletion rate), operational parameters, such as stops and starts, hours of operation, wind velocity, gearbox type, energy generation, or combinations thereof.

[0018] The predictive analytics model may be based on a plurality of data points collected through 1) periodic working oil analysis of the additive level which may be performed manually, for example every six or twelve months, as depicted in block 210, and/or 2) analytics software estimating the severity of the conditions determined by "big data" streams obtained continuously from sensors attached to the wind turbines, as depicted in block 220. In some embodiments, the predictive analytics model of oil degradation in a wind turbine tracks at least one of a phosphorous content or a non-carbon element found in the oil in the wind turbine and monitors operation data of the wind turbine. The actual EP and AW additive levels can be monitored by tracking the phosphorous (P) content or other non-carbon elements (such as molybdenum (Mo), magnesium (Mg), calcium (Ca), Sulfur (S) etc) found in the additive package. [0019] The plurality of data points may be combined to construct a predictive correlation equation correlating between the operational parameters obtained from continuous "Big Stream" data and additive depletion rate calculated from manual working oil sample analysis. The predictive correlation equation constructed according to block 230 may be utilized as a predictive analytics model for determining the effective amount of additive package to add to the existing working fluid, in accordance with block 240. The predictive correlation equation is constructed based on a plurality of data points collected at a plurality of time intervals. The plurality of data points include one or more phosphorus content, non-carbon element content, and operation data.

[0020] A feedback loop may be implemented in the predictive analytics model such that blocks 210, 220, 230, and 240 may be repeated and the data obtained may be used to adjust and/or validate the predictive correlation equation as needed.

[0021] Returning to Figure 1, after determining the effective amount of additive package to be added to the existing working fluid, the invention may further comprise adding, in situ, the effective amount of the additive package to the working fluid (e.g., working oil) in the wind turbine, in accordance with block 130. It is to be understood that the various steps of Figures 1 and 2 may be performed by the same or by different entities.

[0022] The addition can be prescribed in several ways, including, but not limited to: 1) manual additions once or twice a year during existing oil sampling procedures. This may include manually carrying the additive package up-tower and manually pouring the additive package into the existing oil. The additions would be prescribed based on a predictive data analytics model with the objective to bring additive levels to the original level or within about 10% (measured based on phosphorus level in ppm) of the original level; and/or 2) automatic additions with an up-tower automatic injector that can be actuated remotely with the necessary frequency in order to maintain the additive level within 10% of the initial phosphorous levels at all times (measured based on the weight of the additives and their relationship to phosphorus content in ppm). The injector can be actuated with a remote signal from a remote monitoring station in order to deliver the needed volume.

[0023] When the addition is manual, the additive package may have a volume of about 5 gallons or less, about 4 gallons or less, about 3 gallons or less, about 2 gallons or less, about 1 gallon or less, or another volume that may be reasonably carried to the up-tower of the wind turbine by an individual sampling the working oil and pouring the additive package into the working oil.

[0024] When the addition is automatic the additive package (concentrate) would be available in a reservoir of less than about 5 gallons or a volume that could last for at least about 5 years of operations (assuming the additive package is stable for that duration). In some embodiments, the amount sufficient for at least about 5 years of operation may be determined based on historical data of EP and AW additive depletion for a particular wind turbine. In other embodiments, the amount sufficient for at least 5 years of operation may be determined based on historical data of EP and AW additive depletion in gear oil reservoirs of about 75 to about 400 gallons generally. In yet other embodiments, the amount sufficient for at least 5 years of operation may be determined based on a correlation between the operational parameters of the wind turbine and the additive depletion rate constructed at the step of determining an effective amount of an additive package to add to existing working fluid (e.g., working oil) in a wind turbine (i.e. based on the predictive analytics model). [0025] In some embodiments, the additive package would be available in a volume that could last for a time period that may be longer or shorter than 5 years so long as the additive package is stable within that time period. A stable additive packaging is one which has about 10% or less, about 8% or less, about 6% or less, about 4% or less, about 2% or less, about 1% or less, about 0.5 % or less, about 0.2% or less, or about 0.1% or less impurities wherein the percentage is calculated on a (v/v) basis.

[0026] An illustrative process of the method of extending the life of a wind turbine gear box oil, in accordance with embodiments of the invention, is depicted below. First, the initial EP and AW additive levels can be determined via elemental analysis (e.g. using Inductively Coupled Plasma also known as ICP). Once the turbines are put into operation after the oil change the operation data of the turbines can be monitored and captured (hours of operation, type of gearbox, wind speed, power generation, and the like). Then a second measurement of the EP and AW additive levels can be made after a time interval (e.g. 6 months) and a predictive correlation equation can be constructed based on many operation parameters (e.g. hours of operation, power generation, gearbox type, EP and AW additive levels etc.) of a fleet of turbines, each operating under their own conditions. The correlation equation may be individualized for each wind turbine or generalized for a plurality of wind turbines. The less severe set of conditions can be expected to result in smaller EP and AW consumption while the more severe conditions (e.g., higher number of hours of operations, higher number of stop-starts, higher wind speeds, and the like) can be expected to result in higher EP and AW consumption and depletion rates. Once the predictive correlation equation is established, additions of the additive package can be made to restore the system to its initial values or within 10% of its initial values (based on the phosphorus level in ppm). In the next time period (e.g., six months) new data can be made available. Each time new data becomes available, the new data can be fed to a predictive analytics model to further fine tune the predictive correlation equation calculation for future replenishment (either manually or automatically) of additives in the working oil. This predictive calculation can be validated and further optimized via a feedback loop that uses oil condition monitoring data as well as other data (such as hours of operation, type of gearbox, wind speed, power generation, and the like) obtained in batch format periodically (e.g., every 6 months or every 12 months).

[0027] In some embodiments, the invention is directed to a system comprising a wind turbine gear box oil and a reservoir comprising an additive package. The additive package may comprise a carrier fluid and additives in accordance with embodiments of the invention. The additives may comprise EP and AW additives. The reservoir may have a volume able to hold an additive package amount sufficient to replenish depleted additives in the wind turbine gear box oil multiple times over a duration of about 5 years. In some embodiments, the reservoir may have a volume of about 5 gallons or less, about 4 gallons or less, about 3 gallons or less, about 2 gallons or less, or about 1 gallon or less.

[0028] The gear box oil of the wind turbine may comprise a working oil and additives, such as EP and AW additives. The working oil may comprise about 90% or more (v/v) of the wind turbine gear box oil. The additives may comprise up to about 10% (v/v) of the wind turbine gear box oil. The gear box oil may have a viscosity of about 320 cSt at 40 °C.

Additional Benefits include:

[0029] Extending the lubricant fluid life to 20 years or more through in-situ additive package addition.

[0030] Extending the lubricant fluid life to the equivalent of the life of the turbine. [0031] Reduce costs, risks and environmental liability associated with oil changes.

[0032] Reduce overall maintenance costs.

[0033] Maintain oil with optimal levels of EP/AW agents to reduce risk of malfunction due to lubricant degradation.

[0034] Leverage the data and the costs already incurred in oil analysis to improve reliability.

[0035] Leverage the data and costs already incurred in mechanical and environmental system monitoring to improve reliability.

[0036] 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.

[0037] Example 1- Formulation to deliver sufficient phosphorus to replenish EP and AW additives depleted during one year of operation of a formula with an initial phosphorus level of400ppm

20ppm phosphorous

Additive package density (gm/ml) 0.892

Phosphorous concentration in EP/AW additive package (ppm) 6092

Weight of EP/AW additive package to deliver 0.47 grams of EP/AW additive 1.191

Volume of additive package in liter 1.336

Volume of additive package for 5 years (liters) 6.682

Volume of additive package for 5 years (gallons) 1.758

[0038] The above example is based on an estimated annual phosphorus depletion rate ranging from about 5% to about 15% (measured in ppm). This phosphorus depletion rate should not be construed as limited solely to this example and may be the basis for calculations directed to other systems in accordance with embodiments of the invention.

[0039] The table illustrates that a 1.8 gallons additive package may be utilized to replenish 20 ppm of phosphorous annually in a 600 liter (or about 160 gallon) wind turbine gear box oil reservoir for about 5 years. Such an additive package would have EP and AW concentrations of about 6000 ppm.

[0040] While the example illustrates the formulation to deliver sufficient phosphorus to replenish EP and AW additives depleted during one year of operation of a formula with an initial phosphorus level of 400 ppm, the initial level of phosphorus could vary among wind turbines and could range from about 400 ppm to about 2000 ppm. The system volume of wind turbine gear box reservoirs could also vary among wind turbines and range in size from about 70 gallons to about 200 gallons. [0041] The use of the terms "a," "an," "the," and similar referents in the context of describing the materials and methods discussed herein (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the materials and methods and does not pose a limitation on the scope unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

[0042] Reference throughout this specification to "one embodiment," "certain embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in some embodiments," "in one embodiment," or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. [0043] Although the embodiments disclosed herein have been described with reference to particular embodiments it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure include modifications and variations that are within the scope of the appended claims and their equivalents, and the above-described embodiments are presented for purposes of illustration and not of limitation.