Wind turbine cooling process and system

Abstract

The invention relates to a cooling process of a wind turbine, in which heat from a component is transferred to a refrigerant in a cooling system, which consists of: at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol, optionally at least one organic mono- or dicarboxylic acid, preferably saturated mono- or dicarboxylic acid, optionally at least one inorganic salt selected from a group consisting solely of molybdates, borates, phosphates, silicates, nitrites and nitrates, at least one azole compound, water, optionally at least one ester of silicic acid, optionally at least one siliconophosphonate, if silicates are present, and optionally other inhibitors and typical refrigerant constituents, with the exclusion of combinations of alkylated acetylenic alcohol and imidazolin-structured corrosion inhibitors in the refrigerant, provided that at least one mono- or dicarboxylic acid dicarboxylic and / or at least one inorganic salt is present in the refrigerant,and provided otherwise that at least one dicarboxylic acid, preferably at least one saturated dicarboxylic acid, is present in the refrigerant if at least one inorganic salt is absent.

Description

[0001] New applications for coolants

[0002] Description

[0003] The present invention relates to preferred coolants in cooling systems of wind turbines.

[0004] Coolants for motor vehicles have been known for a long time and are used to dissipate heat, particularly from internal combustion engines. In wind turbines, heat is also released during operation and must be dissipated in order to protect mechanical or electrical systems such as generators, gearboxes, bearings, converters and actuation systems from overheating. Compared to motor vehicles, servicing and maintenance work on wind turbines is considerably more complicated and time-consuming, particularly for offshore wind turbines, so extending service intervals is particularly desirable. In addition, coolants in wind turbines have different requirements than those in motor vehicles, as different materials are used in their cooling systems and the operating conditions differ from those of a motor vehicle.For example, coolants in automotive combustion engines are exposed to higher wall temperatures and thus greater thermal stress, whereas wind turbines require high corrosion inhibition of the materials used and maintenance intervals of at least five years. A simple transfer of a coolant for automotive vehicles to the requirements of a wind turbine is therefore not possible.

[0005] EP 3828411 A1 describes a wind turbine and a method for its operation. A coolant is also mentioned, which is said to be water, glycol, or a mixture thereof.

[0006] However, this type of coolant does not meet the above-mentioned requirements for a coolant for wind turbines. EP 3828411 A1 contains no information on, for example, the corrosion resistance, viscosity, stability, temperature resistance, or electrical conductivity of the coolant.

[0007] According to the available machine translation, CN 109837071 B describes coolants for wind turbine generators consisting of ethylene glycol, aliphatic monocarboxylic acid, azole component, defoamer, and water, as well as a corrosion inhibitor mixture of alkoxylated acetylenic alcohol and imidazolines as corrosion inhibitor. The coolants described in this way have an electrical conductivity of less than 200 piS / cm.

[0008] A disadvantage of these coolants is that to achieve the required low electrical conductivity, the described corrosion inhibitor mixture must be used, which is not commercially available and consequently increases the cost of these coolants. Furthermore, only aliphatic monocarboxylic acids are described as other corrosion inhibitors. The object of the present invention was therefore to provide coolants that meet the specific requirements of wind turbines and the peculiarities of their operation.

[0009] The problem was solved by using a coolant containing

[0010] - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol,

[0011] - optionally at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid,

[0012] - optionally at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates,

[0013] - at least one azole compound,

[0014] - Water,

[0015] - optionally at least one silicic acid ester,

[0016] - optionally at least one silicophosphonate, if silicates are present, and

[0017] - optionally further inhibitors and coolant-typical components, with the proviso that at least one mono- or dicarboxylic acid and / or at least one inorganic salt is present in the coolant, in a cooling system of wind turbines, preferably in a cooling system for the thermal management of at least one component of a wind turbine selected from the group consisting of

[0018] - generator,

[0019] - Gearbox,

[0020] - warehouse,

[0021] - Inverters and

[0022] - Adjustment system.

[0023] These coolants, and particularly the embodiments listed below, meet the requirements and exhibit sufficient corrosion-inhibiting effect for the cooling systems used, as well as sufficient stability of the coolant components, thus increasing the coolant's durability and thus extending maintenance intervals. It has been found that the upper limit of 200 piS / cm for the coolant, as established by CN 109837071 B, is not mandatory but can be abandoned in favor of a higher content of corrosion inhibitors, which ensures a corrosion-inhibiting effect over the required long operating life in wind turbines.

[0024] In particular, the corrosion inhibitor composition of CN 109837071 B, consisting of alkoxylated acetylenic alcohol and imidazoline corrosion inhibitor, is omitted according to the invention, particularly propynol alkoxylate, butynediol alkoxylate, and octynol alkoxylate as alkoxylated acetylenic alcohols and carboxyethylimidazoline, heptadecenylamine ethylimidazoline, and heptadecenylamine ethylimidazoline quaternary ammonium salts. The presence of a combination of alkoxylated acetylenic alcohol and corrosion inhibitors with an imidazoline structure in the coolants according to the invention is excluded according to the present invention.

[0025] In particular, a high level of corrosion inhibition of aluminum is required, as aluminum is a widely used material in the cooling systems of wind turbines.

[0026] The components of the coolant are described below:

[0027] This component primarily causes freezing point depression in the coolants. These are monomeric to tetrameric 1,2-ethylene glycols, 1,2-propylene glycols, or, less frequently, 1,3-propylene glycols, preferably monomeric to trimeric 1,2-ethylene glycols or 1,2-propylene glycols, particularly preferably monomeric or dimeric 1,2-ethylene glycols, most particularly preferably monomeric 1,2-ethylene glycol (monoethylene glycol), and mixtures thereof.

[0028] The alkylene glycol monoalkyl ethers are the mono-Ci-C4-alkyl ethers of the above-mentioned alkylene glycols, preferably the monomethyl, ethyl or n-butyl ethers, particularly preferably the monomethyl or n-butyl ethers and very particularly preferably the monomethyl ethers.

[0029] Furthermore, glycerol or glycerol oligomers are possible freezing point lowering components.

[0030] Preferred alkylene glycol components or derivatives are in particular monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures thereof, but also monopropylene glycol, dipropylene glycol and mixtures thereof, polyglycols, glycol ethers, for example monoethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, monoethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, monoethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether and tetraethylene glycol mono-n-butyl ether, or glycerol, each used alone or as mixtures thereof.

[0031] Particularly preferably, monoethylene glycol alone or mixtures of monoethylene glycol are used as the main component, ie with a content in the mixture of more than 50 wt.%, in particular more than 80 wt.%, especially more than 95 wt.%, with other alkylene glycols or derivatives of alkylene glycols.

[0032] In a particularly preferred embodiment, the freezing-point-depressant component consists of monoethylene glycol, whereby the monoethylene glycol may contain up to 5 wt.% of other of the above-mentioned alkylene glycol components, preferably up to 3 wt.%, and particularly preferably up to 2 wt.%, depending on the manufacturing process. Monoethylene glycol contains minor amounts of the higher homologues, particularly diethylene glycol, triethylene glycol, and tetraethylene glycol, due to the manufacturing process. Their total content is generally up to 10 wt.%, preferably up to 7.5 wt.%, and very particularly preferably up to 5 wt.%. The proportion generally decreases with increasing molecular weight of the homologues.

[0033] In a preferred embodiment of the invention, monoethylene glycol is used in the coolants, which comes at least partially, preferably completely, from the processing of used aqueous coolants.

[0034] For this purpose, used aqueous coolants, preferably from motor vehicles and / or stationary engines or generators, are collected decentrally, preferably by workshops and / or maintenance companies,

[0035] - the used aqueous coolants thus collected are collected, combined and transported to a central location, where these used aqueous glycol-containing coolants are subjected to a purification process, preferably at least one distillation.

[0036] Preferably, the cleaning process described in the unpublished European patent application with the reference number 23214551.6 and the filing date of 6 December 2023 is used, in which the used, aqueous glycol-containing coolants are subjected to a cleaning process comprising at least the steps

[0037] (a) distillative separation of ingredients boiling lower than glycol,

[0038] (b) distillation of glycol, and furthermore at least one of the steps

[0039] (c) stripping a glycol-containing mixture with a gas, preferably an inert gas,

[0040] (d) treating a glycol-containing mixture with an acidic or basic, preferably basic, solid,

[0041] (e) treatment of a glycol-containing mixture with activated carbon, and / or

[0042] (f) Membrane filtration of a glycol-containing mixture.

[0043] The individual procedural steps are described in more detail in the European patent application with the reference number 23214551.6.

[0044] The processed monoethylene glycol is referred to as recycled monoethylene glycol in this document.

[0045] In a preferred embodiment, the monoethylene glycol used in the coolant for use according to the invention contains at least 33% by weight of recycled monoethylene glycol, more preferably at least 50%, most preferably at least 66%, in particular at least 75%, and especially at least 90% by weight. In a particular embodiment, the monoethylene glycol used is entirely recycled monoethylene glycol. In a further preferred embodiment according to the invention, monoethylene glycol is used in the coolant that originates at least partially, preferably entirely, from renewable raw materials.

[0046] The monoethylene glycol obtained from renewable raw materials can be characterized by the fact that the 14 C / 12C isotope ratio is determined, preferably according to ASTM D 6866 ("Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis").

[0047] According to this test method, the 14 C / 12 C isotope ratio of a sample measured and compared with the 14 C / 12 C isotope ratio in a standardized 100% bio-based material. The result is the bio-based content of the sample.

[0048] The application of ASTM-D6866 to derive the "biobased content" is based on the same concepts as radiocarbon dating, but without the use of age equations. The analysis is performed by determining a ratio of the amount of radiocarbon ( 14C) is determined in an unknown sample compared to that of a modern reference standard. This parameter is expressed as a percentage using the unit "pMC" (percent modern carbon). If the material being analyzed is a mixture of present-day radiocarbon and fossil carbon (with very low radiocarbon content), the resulting pMC value correlates directly with the amount of biomass material present in the sample.

[0049] The monoethylene glycol used in the coolants according to the invention preferably has a bio-based content, measured as 14 C: 12 C ratio ASTM-D6866 of more than 0%, preferably at least 1%, more preferably at least 5%, most preferably at least 10%, in particular at least 20% and especially at least 25%.

[0050] Advantageously, this bio-based proportion can be at least 30%, preferably at least 40%, particularly preferably at least 50%, most particularly preferably at least 66%, in particular at least 75% and especially at least 85%.

[0051] If the content is at least 90%, preferably at least 95%, particularly preferably at least 98% and even 100%, this can be described as predominantly or completely bio-based monoethylene glycol.

[0052] For example, this bio-based monoethylene glycol or monoethylene glycol obtained from renewable raw materials can be obtained by a process as described in the unpublished European patent application with the file number 23185804.4 and the filing date of 17 July 2023. This application describes processes by which bio-based monoethylene glycol can be obtained from various sources.

[0053] Through the at least partial use of bio-based monoethylene glycol, emissions from the use of coolants containing alkylene glycol, for example nitrogen oxide and sulfur oxide emissions and in particular carbon dioxide emissions, preferably determined as a carbon footprint, life cycle assessment or in accordance with DIN EN ISO 14021, DIN EN ISO 14067, in particular the 2019-02 edition, DIN EN ISO 14044, in particular the 2006 +A1:2018 edition and / or DIN EN ISO 14040, in particular the 2009-11 edition, can be reduced.

[0054] Organic mono- or dicarboxylic acid

[0055] Organic carboxylic acids are often used as corrosion inhibitors against the corrosion of ferrous materials. Examples of ferrous materials include steel, wrought iron, and cast iron.

[0056] The organic mono- and dicarboxylic acids can be aromatic or aliphatic carboxylic acids, with preference being given to aromatic monocarboxylic acids and aliphatic mono- and dicarboxylic acids; aliphatic mono- and dicarboxylic acids are particularly preferred.

[0057] Benzoic acid is preferred as aromatic monocarboxylic acid, which can be used as the free acid or particularly preferably in the form of its alkali metal salt, most preferably as sodium benzoate.

[0058] Preferred monocarboxylic acids are organic aliphatic alkane or alkenecarboxylic acids. These are often used in coolants as corrosion inhibitors against the corrosion of ferrous materials, provided they are sufficiently water-soluble.

[0059] Typical such monocarboxylic acids are pentanoic acid, 2,2-dimethylpropanoic acid, hexanoic acid, 2,2-dimethylbutanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, isononanoic acid, decanoic acid, undecanoic acid and dodecanoic acid, as well as their isomer mixtures, in particular 2-ethylhexanoic acid and isononanoic acid isomer mixtures.

[0060] Examples of branched aliphatic monocarboxylic acids are 2-ethylhexanoic acid, 2,2-dimethylhexanoic acid (neooctanoic acid, Versatic Acid 8), 2,2-dimethylheptanoic acid (neononanoic acid, Versatic Acid 9), isononanoic acid, 2-propylheptanoic acid, 2,2-dimethyloctanoic acid (neodecanoic acid, Versatic Acid 10), neoundecanoic acid (Versatic Acid 11), neododecanoic acid, and neotridecanoic acid (Versatic Acid 13).

[0061] The use of 2-ethylhexanoic acid may be less preferred for health reasons. Preferably, the content of 2-ethylhexanoic acid in the coolant is less than 3%, more preferably less than 0.3%, and most preferably, the coolants do not contain 2-ethylhexanoic acid.

[0062] To reduce or avoid the content of 2-ethylhexanoic acid in the coolant, in one embodiment it is completely or partially, preferably completely, replaced by at least one other of the above-mentioned aliphatic monocarboxylic acids other than 2-ethylhexanoic acid, particularly by isononanoic acid. In a preferred embodiment, 2-ethylhexanoic acid can also be partially replaced by a combination of 2-ethylhexanoic acid with benzoic acid.

[0063] In a preferred embodiment, 2-ethylhexanoic acid can also be completely or partially replaced by a combination of 2-ethylhexanoic acid with at least one of the above-mentioned aliphatic dicarboxylic acids, particularly preferably a combination of 2-ethylhexanoic acid with adipic acid or 2-ethylhexanoic acid with sebacic acid.

[0064] Particularly preferably, a mixture of at least two aliphatic dicarboxylic acids is used without 2-ethylhexanoic acid, for example a mixture of adipic acid and sebacic acid.

[0065] Thus, a preferred embodiment involves using at least one dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid, in the coolant in the absence of aliphatic monocarboxylic acids. This is particularly preferred in the simultaneous absence of the at least one inorganic salt. In the absence of the at least one inorganic salt, it is possible to use a combination of at least one dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid, with at least one monocarboxylic acid, preferably at least one aliphatic monocarboxylic acid. Particular preference is given here to using at least one dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid, in the simultaneous absence of aliphatic monocarboxylic acids.

[0066] Dicarboxylic acids, especially aliphatic ones, have the advantage over aliphatic monocarboxylic acids in that they can form chelate complexes with metal ions in corrosion tests on various materials, such as iron, steel, copper, brass, and aluminum. This allows them to stabilize metal ions in solution, preventing them from precipitating and forming deposits that reduce heat transfer in the cooling system or clog the lines in the coolant circuit. In the case of dicarboxylic acids, the presence of two carboxylic acid groups enables the formation of stronger chelate complexes with metal ions than monocarboxylic acids. The resulting chelate complexes are also effective in inhibiting further corrosion by preventing the metal ions from reacting with the environment and forming corrosion products.Furthermore, dicarboxylic acids are less volatile than monocarboxylic acids, so they remain in the coolant even at higher temperatures, for example, under the conditions in a cooling circuit. Furthermore, aliphatic monocarboxylic acids have a hydrophilic end with the carboxyl or carboxylate group and a hydrophobic end with the aliphatic alkyl radical. In the case of long alkyl radicals, the hydrophobic influence can limit the solubility of the aliphatic monocarboxylic acids in the coolant. In contrast, in dicarboxylic acids, especially aliphatic dicarboxylic acids and especially in the particularly preferred aliphatic α,ω-dicarboxylic acids, the ratio between hydrophilic carboxyl groups and hydrophobic connecting chain is such that the hydrophilic influence predominates.This is due, on the one hand, to the fact that the ratio of carbon atoms in the carboxyl groups to those in the aliphatic alkylene chain favors the hydrophilic properties and, on the other hand, to the fact that, unlike in aliphatic monocarboxylic acids, a hydrophilic and a hydrophobic end are not formed, but the hydrophobic chain is framed at the ends by the hydrophilic carboxyl groups.

[0067] Also particularly preferred is a mixture of 2-ethylhexanoic acid with at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates and nitrates, very particularly preferred is a mixture of 2-ethylhexanoic acid with at least one inorganic salt selected from the group consisting of molybdates, phosphates and silicates.

[0068] Neoalkanecarboxylic acids containing 8 to 13 carbon atoms can be mixtures of isomers and not necessarily pure isomers.

[0069] For example, neodecanoic acid is a mixture of carboxylic acids (CAS 26896-20-8) containing 2, 2,3,5-tetramethylhexanoic acid, 2,4-dimethyl-2-isopropylpentanoic acid, 2,5-dimethyl-2-ethylhexanoic acid, 2,2-dimethyloctanoic acid and / or 2,2-diethylhexanoic acid.

[0070] In a preferred embodiment, the aliphatic carboxylic acid is isononanoic acid. For the purposes of this document, this refers to one or more branched aliphatic carboxylic acids having 9 carbon atoms. Examples of isononanoic acid can include 7-methyloctanoic acid (e.g., CAS Nos. 693-19-6 and 26896-18-4), 6,6-dimethylheptanoic acid (e.g., CAS No. 15898-92-7), 3,5,5-trimethylhexanoic acid (e.g., CAS No. 3302-10-1), 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid (e.g., CAS No. 3302-12-3), and mixtures thereof. In a preferred embodiment, isononanoic acid contains as main components of more than 90% (in total) at least one carboxylic acid selected from the group consisting of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid and 2,2,4,4-tetramethylpentanoic acid.The 100% missing portion may include other carboxylic acids with 9 carbon atoms and a small amount of by-products. In a preferred embodiment, isononanoic acid contains at least 90%, preferably at least 95%, of 3,5,5-trimethylhexanoic acid as the main component.

[0071] The organic dicarboxylic acids having 4 to 20 carbon atoms are linear or branched alkanedicarboxylic acids, preferably linear alkane or alkenedicarboxylic acids, particularly preferably alkanedicarboxylic acids, particularly preferably having 5 to 14 and very particularly preferably having 6 to 12 carbon atoms.

[0072] Preferably, the aliphatic dicarboxylic acids are selected from the group consisting of succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid (heptanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid), undecanedioic acid, dodecanedioic acid, as well as alkyl and alkenyl succinic acids and glutaric acids such as 2-methylbutanedioic acid, 2-ethyl-3-methylbutanedioic acid, 2-ethylpentanedioic acid, 2-dodecylbutanedioic acid, 2-dodecenylbutanedioic acid, 2-phenylbutanedioic acid, 2-(p-methylphenyl)butanedioic acid, 2,2-dimethylbutanedioic acid, 2,3,4-trimethylpentanedioic acid, 2,2,3-trimethylpentanedioic acid, glutaconic acid (pent-2-enedioic acid), itaconic acid, Hex-2-enedioic acid, hex-3-enedioic acid, 5-methyl-hex-2-enedioic acid and 2,3-dimethyl-pent-2-enedioic acid.

[0073] Among these, preferred are the dicarboxylic acids having 6 to 12 carbon atoms, particularly preferred among these are the alkanedicarboxylic acids having 6 to 12 carbon atoms, very particularly preferred are the linear alkanedicarboxylic acids having 6 to 12 carbon atoms.

[0074] Particularly preferred aliphatic dicarboxylic acids are adipic acid, sebacic acid, azelaic acid and dodecanedicarboxylic acid, especially adipic acid, sebacic acid and dodecanedioic acid, and most preferred are adipic acid and sebacic acid.

[0075] Inorganic salt

[0076] The inorganic salts are often used as corrosion inhibitors against the corrosion of iron and / or aluminum-containing materials as well as solder.

[0077] The at least one inorganic salt is selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates, preferably selected from the group consisting of borates, phosphates, silicates, nitrites and nitrates, particularly preferably selected from the group consisting of phosphates, silicates and nitrates.

[0078] The inorganic inhibitors are phosphates, silicates, borates, nitrites, nitrates, or molybdates, or mixtures thereof in the form of their free acids or their salts, especially their alkali metal salts, particularly preferably their sodium or potassium salts. The form (protonated or salt) in which they are present in the compositions, superconcentrates, concentrates, or coolants depends on the respective pK. s -value of the compound and the composition as well as the pH of the respective environment, which is adjusted by the amount of base.

[0079] The molybdates are used as free acid (H2MOO4), as hydrogen molybdate, or preferably as molybdate, particularly as alkali metal salts, particularly preferably as sodium or potassium salts, and most preferably as sodium salts. The acidic protons in the molybdates can be partially or completely replaced by alkali metal salts. Sodium molybdate is preferred, usually in the form of the dihydrate.

[0080] The borates are preferably used as sodium tetraborate (borax) or potassium tetraborate, particularly preferably as sodium tetraborate. The phosphates are used as free acid (H3PO4), as hydrogen phosphate, dihydrogen phosphate, or phosphate, particularly as alkali metal salts, particularly preferably as sodium or potassium salts. The acidic protons in the phosphates can be partially or completely replaced by alkali metal salts.

[0081] The use of the corresponding diphosphates, triphosphates or oligophosphates is also conceivable, even in mixtures with monophosphates, but they are preferably used as monomeric phosphates.

[0082] It is preferred to use it as free acid (H3PO4), disodium hydrogen phosphate or trisodium phosphate.

[0083] The inorganic silicates mainly act as corrosion inhibitors of aluminum and aluminum-containing materials as well as solder and are mostly used as alkali metal salts or, less frequently, as magnesium, calcium or aluminum salts, preferably as sodium or potassium salts.

[0084] The silicates are preferably selected from the group consisting of orthosilicates (SiO4 4- ), metasilicates (SIOs 2- ), and pyrosilicates (Si20z 6- ), particularly preferred are metasilicates (SIOs 2-), very particularly preferably sodium metasilicate (Na2SIO3) or potassium metasilicate (K2SIO3), in particular sodium metasilicate (Na2SIO3).

[0085] Nitrites include all inorganic salts of the nitrite anion (NO2) and nitric acid (HNO2). Nitrite is typically used in coolants in the form of sodium nitrite or potassium nitrite or is converted into these by inorganic bases, preferably sodium hydroxide or potassium hydroxide.

[0086] In a preferred embodiment, the coolants do not contain nitrite for health reasons.

[0087] The nitrates are used as alkali or alkaline earth metal nitrates, preferably as sodium nitrate, potassium nitrate or magnesium nitrate, preferably as sodium nitrate or potassium nitrate, particularly preferably as sodium nitrate.

[0088] Preferred inorganic salts are selected from the group consisting of molybdates, borates, phosphates, silicates and nitrates, particularly preferably selected from the group consisting of molybdates, borates, phosphates and silicates, very particularly preferably selected from the group consisting of molybdates, phosphates and silicates.

[0089] Azole compound

[0090] Azole compounds act particularly as corrosion inhibitors against the corrosion of non-ferrous metals, such as brass or copper. For the purposes of this document, azole compounds or azole derivatives are five-membered heterocyclic compounds with two or three heteroatoms from the group consisting of nitrogen and sulfur, which contain no or a maximum of one sulfur atom incorporated into the ring and which can optionally bear an aromatic or saturated six-membered anellant.

[0091] These five-membered heterocyclic compounds (azole derivatives) usually contain two N atoms and no S atom, three N atoms and no S atom, or one N atom and one S atom as heteroatoms.

[0092] Preferred groups of the azole derivatives mentioned are fused imidazoles and fused 1,2,3-triazoles of the general formula or (IV) in which the variable

[0093] R represents hydrogen or a Ci- to Cw-alkyl radical, in particular methyl or ethyl, and the variable X represents a nitrogen atom or the group CH.

[0094] Typical and preferred examples of azole derivatives of the general formula (III) are benzimidazole (X = CH, R = H), benzotriazole (X = N, R = H), and tolutriazole (tolyltriazole) (X = N, R = CH3). A typical example of an azole derivative of the general formula (IV) is hydrogenated 1,2,3-tolutriazole (tolyltriazole) (X = N, R = CH3).

[0095] Another preferred group of the azole derivatives mentioned are benzothiazoles of the general formula (V) in which the variable R has the meaning given above and the variable R' denotes hydrogen, a Ci- to Cw-alkyl radical, in particular methyl or ethyl, or in particular a mercapto group (-SH). Conceivably, although less preferably, R' can also be a carboxyalkyl radical of the formula -(C m H2 m)-COOR", where m is a number from 1 to 4 and R" is hydrogen or C1- to C12-alkyl, in particular methyl or ethyl, or C1- to C12-aryl. Examples thereof are (2-benzothiazylthio)acetic acid, (2-benzothiazylthio)acetic acid ester, 3-(2-benzothiazylthio)propionic acid or 3-(2-benzothiazylthio)propionic acid ester. In the event that these compounds are used as acid, they are not among the carboxylic acids excluded according to the invention. A typical example of an azole derivative of the general formula (V) is 2-mercaptobenzothiazole.

[0096] Furthermore, non-fused azole derivatives of the general formula (VI) in which the variables

[0097] X and Y together denote two nitrogen atoms or one nitrogen atom and a group CH, for example 1 H-1,2,4-triazole (X = Y = N) or preferably imidazole (X = N, Y = CH).

[0098] Benzimidazole, benzotriazole, tolutriazole, hydrogenated tolutriazole or mixtures thereof, in particular benzotriazole or tolutriazole, especially tolutriazole, are very particularly preferred as azole derivatives for the present invention.

[0099] The azole derivatives mentioned are commercially available or can be prepared using conventional methods. Hydrogenated benzotriazoles such as hydrogenated tolutriazole are also accessible according to DE-A 1 948 794 and are also commercially available.

[0100] Preferably, the azoles are selected from the group consisting of benzotriazole, tolutriazole, (2-benzothiazylthio)acetic acid, 3-(2-benzothiazylthio)propionic acid and 2-mercaptobenzothiazole.

[0101] Water: The water used in the present invention should be neutral with a pH value of around 7. This can be demineralized or distilled water, although this is not mandatory. To enable the use of hard water, at least one hard water stabilizer can be added to the coolant composition.

[0102] The water used may contain alkaline earth metal ions, for example magnesium, calcium, strontium, or barium ions, the latter usually being present only in traces. Preferably, the water contains essentially only magnesium and / or calcium ions as hardness-forming agents.

[0103] The water used is preferably soft water with a water hardness of not more than 8.4 °dH, particularly preferably not more than 10 and most preferably not more than 12 °dH.

[0104] When using water with a water hardness of up to 14 °dH, preferably up to 17, particularly preferably up to 20 and even up to 25 °dH, a hard water stabilizer is generally required.

[0105] The water used in the coolant is the usual source of any carbonate and / or sulfate that may be contained in the coolant via the hardness-forming agents.

[0106] Silicic acid esters

[0107] Instead of or in addition to the inorganic silicates mentioned, the coolants may also contain organic ortho-silicic acid esters of the general formula Si(OR)4, in which each R independently of one another is Ci-C4-alkyl, preferably methyl, ethyl or n-butyl, particularly preferably methyl or ethyl or mixtures of methyl and ethyl.

[0108] The ortho-silicic acid esters mainly act as corrosion inhibitors of aluminum or aluminum-containing materials as well as solder.

[0109] Silicophosphonate

[0110] If the composition contains at least one inorganic silicate, in a preferred embodiment at least one silicophosphonate is added in addition to the silicate, as described in European patent application EP 4015596.

[0111] Preferably, the silicophosphonate is a compound of the general formula wherein

[0112] R 5 is a divalent organic radical, preferably a 1,oo-alkylene group having 1 to 6, preferably 1 to 4 carbon atoms, particularly preferably methylene, 1,2-ethylene, 1,2-propylene, 1,3-propylene or 1,4-butylene, very particularly preferably 1,2-ethylene or 1,3-propylene and in particular 1,2-ethylene,

[0113] R 6independently of one another are hydrogen, Ci- to C alkyl or hydroxy-O 2 - to C alkyl, preferably hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl, 2-hydroxyethyl or 2-hydroxypropyl, particularly preferably hydrogen, methyl, ethyl or propyl, and R 7 is Ci- to C alkyl, preferably methyl, ethyl, n-propyl or n-butyl, particularly preferably methyl, ethyl or n-butyl, very particularly preferably methyl or ethyl and in particular methyl.

[0114] The silicophosphonates can be used as free acid or as alkali metal salt, preferably as sodium or potassium salt and particularly preferably as sodium salt.

[0115] Other inhibitors and coolant-typical components

[0116] As further common additives, the coolants may optionally contain defoamers in small quantities (usually in amounts of 0.003 to 0.008% by weight in the finished diluted coolant) as well as bittering agents (e.g. of the denatonium benzoate type) and dyes for reasons of hygiene and safety in case of ingestion.

[0117] The composition may also contain one or more hard water stabilizers based on polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymers, polyvinylpyrrolidone, polyvinylimidazole, vinylpyrrolidone-vinylimidazole copolymers, and / or copolymers of unsaturated carboxylic acids and olefins. The proportion in the composition is selected such that, after appropriate dilution, the amount in the final diluted coolant is up to 1 wt.%.

[0118] In a preferred embodiment, it is a hard water stabilizer as described in WO 2022 / 200155. One advantage of using hard water stabilizers is that the use of demineralized or distilled water is not required to reduce or prevent the precipitation of alkaline earth metal compounds.

[0119] Composition of coolants

[0120] The coolants ready for use in wind turbines are preferably produced by diluting concentrates (see below) with water and are composed, for example, as follows:

[0121] - 40 to 75 wt% water, preferably 45 to 70, particularly preferably 50 to 70, most particularly preferably 55 to

[0122] 67.5 and in particular 60 to 65% by weight,

[0123] - 20 to 55% by weight of alkylene glycol, alkylene glycol monoalkyl ether and glycerol, preferably 25 to 50, particularly preferably 25 to 45, very particularly preferably 30 to 50 and in particular at least 32.5 to 35% by weight,

[0124] - in total 0.1 to 5 wt%, preferably 0.25 to 4.5, very particularly preferably 0.5 to 4 and in particular 1 to 4

[0125] Wt% of the following components:

[0126] - optionally at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid,

[0127] - optionally at least one inorganic salt selected from the group consisting of molybdates, borates,

[0128] Phosphates, silicates, nitrites and nitrates,

[0129] - at least one azole compound

[0130] - optionally at least one silicic acid ester,

[0131] - optionally at least one silicophosphonate, if silicates are present, and

[0132] - optionally 0 to 1 wt%, preferably 0 to 0.75, particularly preferably 0.05 to 0.5, very particularly preferably

[0133] 0.1 to 0.4 and in particular 0.2 to 0.3 wt% of further inhibitors and coolant-typical components, with the proviso that at least one mono- or dicarboxylic acid and / or at least one inorganic salt is present in the coolant, with the proviso that the sum of all components always amounts to 100 wt%.

[0134] In a preferred embodiment, the coolant contains

[0135] - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol

[0136] - at least one aromatic organic monocarboxylic acid,

[0137] - at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates,

[0138] silicates, nitrites and nitrates,

[0139] - at least one azole compound

[0140] - Water

[0141] - optionally at least one silicophosphonate if silicates are present, preferably at least one silicophosphonate if silicates are present, and - optionally hard water stabilizer, bittering agent, defoamer and / or colorant.

[0142] In an equally preferred embodiment, the coolant contains

[0143] - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol

[0144] - at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid, particularly preferably at least one aliphatic monocarboxylic acid and at least one aliphatic dicarboxylic acid or particularly preferably at least two aliphatic dicarboxylic acids, in particular at least two aliphatic dicarboxylic acids without 2-ethylhexanoic acid, and especially at least two aliphatic dicarboxylic acids without monocarboxylic acids,

[0145] - at least one azole compound

[0146] - Water

[0147] - optionally hard water stabilizer, bittering agent, defoamer and / or colorant, with the proviso that no inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates is present in the coolant.

[0148] In an equally preferred embodiment, the coolant contains

[0149] - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol

[0150] - at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid, particularly preferably at least one aliphatic monocarboxylic acid and at least one aliphatic dicarboxylic acid,

[0151] - at least one inorganic salt selected from the group consisting of borates, phosphates, silicates, nitrites and nitrates,

[0152] - at least one azole compound

[0153] - Water

[0154] - optional hard water stabilizer, bittering agent, defoamer and / or colorant.

[0155] In an equally preferred embodiment, the coolant contains

[0156] - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol

[0157] - at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid, particularly preferably at least one aliphatic monocarboxylic acid and at least one aliphatic dicarboxylic acid or particularly preferably at least two aliphatic dicarboxylic acids,

[0158] - at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates and nitrates, preferably selected from the group consisting of phosphates and silicates,

[0159] - at least one azole compound

[0160] - Water

[0161] - optionally at least one silicophosphonate if silicates are present, preferably at least one silicophosphonate if silicates are present, and - optionally hard water stabilizer, bittering agent, defoamer and / or colorant.

[0162] In the last two embodiments, the inorganic salt preferably comprises at least one silicate; more preferably, no further inorganic salts are present apart from silicate.

[0163] In these embodiments, the azole compounds are preferably benzotriazole or tolutriazole.

[0164] The non-aliphatic organic monocarboxylic acids are preferably benzoic acid.

[0165] The aliphatic monocarboxylic acids are preferably selected from the group consisting of 2-ethylhexanoic acid and isononanoic acid, particularly preferably isononanoic acid.

[0166] The aliphatic dicarboxylic acids are preferably selected from the group consisting of adipic acid, sebacic acid and dodecanedioic acid.

[0167] The inorganic salts are preferably selected from the group consisting of molybdates, borates, phosphates and silicates, particularly preferably selected from the group consisting of molybdates, phosphates and silicates, very particularly preferably selected from the group consisting of phosphates and silicates.

[0168] The coolant should have a kinematic viscosity according to ASTM D445 of 3 mm at a temperature of 20 °C 2 / s, preferably not more than 2.5, particularly preferably not more than 2 mm 2 / s, most preferably not more than 1.5 and especially not more than 1 mm 2 / s.

[0169] At a temperature of 0 °C, the coolant should have a kinematic viscosity according to ASTM D445 of 7.5 mm 2 / s, preferably not more than 7, particularly preferably not more than 6 mm 2 / s, most preferably not more than 5.5 and especially not more than 5 mm2 / s.

[0170] At a temperature of 80 °C, the coolant should have a kinematic viscosity according to ASTM D445 of 1 mm 2 / s, preferably not more than 0.9, particularly preferably not more than 0.8 mm 2 / s, most preferably not more than 0.7 and especially not more than 0.6 mm 2 / s.

[0171] To reduce the volumes to be transported, concentrates are usually sold in which the water content is omitted or significantly reduced. The coolants are then produced from the concentrates by adding water before filling the wind turbine. These concentrates are usually diluted with water in a volume ratio of 1:1 to 1:3 (vol / vol), preferably 1:1 to 1:2, depending on the prevailing temperature on site and the requirements for freeze protection. The concentrates are composed accordingly like the coolants listed above, but with a reduced water content depending on the dilution ratio. As a rule, the water content in the concentrate is no more than 15, preferably no more than 10, and particularly preferably no more than 5 wt%.

[0172] For example, the concentrates are composed as follows:

[0173] - 0.1 to 15 wt% water

[0174] - 50 to 95 wt% alkylene glycol, alkylene glycol monoalkyl ether and glycerol,

[0175] - in total 0.5 to 15 wt% of the following components:

[0176] - optionally at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid,

[0177] - optionally at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates,

[0178] - at least one azole compound

[0179] - optionally at least one silicic acid ester,

[0180] - optionally at least one silicophosphonate, if silicates are present, and

[0181] - optionally 0 up to 3 wt% of further inhibitors and coolant-typical components, excluding a combination of alkoxylated acetylenic alcohol and corrosion inhibitors with imidazoline structure in the coolant, with the proviso that at least one mono- or dicarboxylic acid and / or at least one inorganic salt is present in the coolant, and with the further proviso that in the absence of the at least one inorganic salt, at least one dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid is present in the coolant, with the proviso that the sum of all components always amounts to 100 wt%.

[0182] The pH value of the coolants at the end user is usually in the range of 4 to 11.5, preferably 5 to 10, in particular 6 to 9.

[0183] To adjust this pH value, at least one inorganic base is added at any stage during the production process for coolants from a concentrated precursor. The at least one inorganic base can be contained in the coolant or in the concentrate, or it can be added during the production of the coolant from the concentrate by mixing it with water.

[0184] Preferred inorganic bases are alkali metal hydroxides, particularly preferably solid lithium, sodium or potassium hydroxide, optionally also in the form of aqueous lithium, sodium or potassium hydroxide solution.

[0185] Less preferred are carbonates or bicarbonates of lithium, sodium or potassium.

[0186] Preferred alkali metals are sodium and potassium. The electrical conductivity of the coolants plays a minor role according to the invention and can be up to 3000 piS / cm (measured according to ASTM D 1125 at 25 °C), preferably up to 2500, particularly preferably up to 2000, most particularly preferably up to 1500, and especially up to 1000 piS / cm.

[0187] It is conceivable to produce the coolant by diluting the concentrate with water in the desired dilution ratio directly when refueling the wind turbine. However, this has the disadvantage that both water and concentrate have to be transported to the wind turbine and mixed there in the correct ratio, for example using pumps or static mixers. The concentrate is usually mixed with water by introducing energy through shear energy. This can be done, for example, in dynamic mixing devices, i.e. by mixing using a stirrer or by pumping (natural circulation or forced circulation) or pumping with static mixing devices such as static mixers or nozzles in the pumping circuit, by static mixing devices such as static mixers, nozzles, orifices, Y-pieces or T-pieces in the inlet of the preparation tank, or by dynamic mixing devices such as mixing pumps or stirred tanks.

[0188] Therefore, the coolants are usually produced at a first location, e.g. at a formulator, by mixing the concentrates with water in the desired dilution ratio. The coolant diluted with water is then transported to the wind turbine at a second location, where the cooling system of the wind turbine is filled with the ready-mixed coolant.

[0189] For newly constructed wind turbines, this second location is usually the assembly site for the nacelle.

[0190] For existing wind turbines, the second location is the site of the wind turbine, i.e. at sea for offshore turbines or on land for onshore turbines.

[0191] Existing wind turbines are filled at ambient temperature, preferably between 15 and 35 °C. The temperature should not fall below -10 °C. Since the coolant must generally be pumped to the height of the wind turbine nacelle, where the cooling system is located, and this nacelle is located at a height of 50 to 150 m, with plans even extending to 200 m, the temperature of the coolant when filling the wind turbine's cooling system should be such that the viscosity of the coolant at the pumping temperature is 3 mm. 2 / s, preferably not more than 2.5, particularly preferably not more than 2 mm 2 / s, most preferably not more than 1.5 and especially not more than 1 mm 2 / s, as otherwise the coolant will be difficult to pump to this height. A low viscosity is desirable as this requires lower pump power and can lead to cavitation, for example, in high-speed pumps. If the viscosity of the coolant is too high for pumping, it may be advisable to heat the coolant slightly to reduce the viscosity and then transport the heated coolant to the wind turbine in an insulated or thermostatted container. As a rule, a coolant temperature of up to 25 °C above the ambient temperature is sufficient for this purpose, preferably up to 20, more preferably up to 15 and most preferably up to 10 °C.

[0192] Alternatively, the coolant can be transported in a suitable container by crane or elevator to the level of the wind turbine's coolant tank and replaced there. This is particularly preferred if the coolant is too viscous to be pumped or if a suitable pump is unavailable.

[0193] The used coolant is collected after replacement and can be disposed of via sewage treatment plants or recycled.

[0194] wind turbine

[0195] The components of wind turbines to be cooled usually include at least one selected from the group consisting of generator, gearbox, bearings, converter and control system.

[0196] The gearbox converts the low rotor speed into a high generator speed, allowing the use of smaller generators. However, it is also possible to operate a wind turbine without a gearbox. In this case, the generator is directly coupled to the rotor and rotates at the same speed as the rotor. This is structurally simpler, as the gearbox is omitted; however, the generators in gearless wind turbines must be significantly larger.

[0197] Therefore, the gearbox is not necessarily present in every wind turbine.

[0198] With the mostly hydraulic control system, the rotor is usually automatically turned into the wind by the wind turbine's control system to optimize power generation (yaw). This includes both the alignment of the hub to the wind direction and the angle of attack of the rotor blades to the wind. In excessively strong winds, the rotor can also be turned out of the wind, or the rotor blades can be turned into a so-called feathering position, to protect the turbine.

[0199] A preferred embodiment involves cooling the wind turbine's gearbox (if present) and / or actuator system and dissipating the heat generated there via the coolant. In a particularly preferred embodiment, the gearbox and actuator system are cooled in a common cooling circuit.

[0200] The rotor is set in rotation by the kinetic energy of the wind, driving a generator inside the nacelle, which in turn converts the mechanical energy into electrical energy. The electricity generated by the generator can then be fed into the power grid. In most systems, a converter ensures that the electricity fed in has the frequency required for the national or regional power grid, usually 50 to 60 hertz.

[0201] A preferred embodiment involves cooling the generator and / or converter of the wind turbine and dissipating the heat generated there via the coolant. In a particularly preferred embodiment, the generator and converter are cooled in a common cooling circuit.

[0202] A further subject of the present invention is a method for the heat management of components of wind turbines, in which heat from at least one component of a wind turbine selected from the group consisting of

[0203] - generator,

[0204] - Gearbox,

[0205] - warehouse,

[0206] - Inverters and

[0207] - control system at a higher temperature via at least one first heat exchanger to a coolant as described above, this coolant is guided in a cooling circuit to at least one second heat exchanger and there at a lower temperature heat is removed from the coolant in which

[0208] - a composition as described above is used as coolant,

[0209] - the higher temperature is from 20 to 100 °C, preferably from 25 to 80, particularly preferably from 30 to 60 °C,

[0210] - the lower temperature is between minus 50 and 40 °C, preferably between minus 40 and 40 °C, particularly preferably between minus 30 and 35 °C and

[0211] - the lower temperature is at least 5 °C, preferably at least 10, particularly preferably at least 15 and most particularly preferably at least 20 °C lower than the higher temperature.

[0212] The higher temperature is preferably the wall temperature of the respective component of the wind turbine during normal operation of the wind turbine.

[0213] The lower temperature is preferably the ambient temperature with which the heated coolant is brought into contact in the second heat exchanger.

[0214] It is possible, although less preferred, for offshore wind turbines to have the lower temperature be that of seawater at the wind turbine site. In this case, the lower temperature is 0 to 30 °C, preferably 1 to 25 °C, more preferably 2 to 20 °C, and most preferably 3 to 15 °C.

[0215] One advantage of the coolants described in this document is that wind turbines can generally be operated with these coolants for at least 5, preferably at least 7, particularly preferably at least 8, and most particularly preferably at least 10 years without the need to replace the coolant. It is even conceivable that the coolant may not need to be replaced during the entire operating life of the wind turbine, i.e., up to 25, preferably up to 30 years.

[0216] All heat exchangers can be components that are known per se and are familiar to the expert for these purposes.

[0217] Percent, ppm or parts in this document refer to wt%, wt.ppm or parts by weight unless otherwise stated.

[0218] Viscosity data in this publication refer to ASTM D445 at 20 °C unless otherwise stated.

[0219] Examples

[0220] A coolant 1 according to the invention based on ethylene glycol with a mixture of adipic acid, sebacic acid, and tolutriazole as inhibitor components, as described in the examples of WO 02 / 90462 A1, was subjected to a corrosion test according to ASTM D 1384 (Glassware Corrosion Test, 336 hours at 88 °C, 33% solutions). Negative values ​​indicate an increase in the weight of the test specimen.

[0221] Furthermore, a coolant 2 based on ethylene glycol with a mixture of molybdate, 2-ethylhexanoic acids, and tolutriazole was subjected to a corrosion test according to ASTM D 1384. In this investigation, three metal plates of each sample were used in the test, and the weight loss results were rounded to one significant figure without decimal places.

[0222] A commercially available product advertised as offering 6 years of protection in stationary systems was used as the less preferred coolant (0). Wind turbines are not mentioned. According to the safety data sheet, this product contains 2-ethylhexanoic acid as an inhibitor component and, according to the accompanying product information, is free of nitrite, amines, phosphate, borate, and silicate. Furthermore, this coolant likely also contains sebacic acid.

[0223] Coolant 3 is based on ethylene glycol with a mixture of sodium benzoate, nitrite, borate, silicate and benzotriazole and was subjected to a corrosion test according to ASTM D 1384.

[0224] Coolant 4 is based on ethylene glycol with a mixture of silicate, borate, organic acids (sebacic acid and 2-ethylhexanoic acid) and benzotriazole and was subjected to a corrosion test according to ASTM D 1384.

[0225] Coolant 5 is based on ethylene glycol with a mixture of silicate, organic acids (sebacic acid, adipic acid and dodecanedioic acid) and tolutriazole and was subjected to a corrosion test according to ASTM D 1384.

[0226] *) The values ​​according to the corrosion test according to ASTM D1384 are taken from the product information. It can be seen that coolants 1 and especially 2 show better corrosion results than coolant 0, especially with regard to aluminum corrosion, and are therefore more suitable for cooling systems with aluminum components.

[0227] Furthermore, it can be seen that coolants 3, 4, and 5 exhibit better corrosion results than coolant 0, particularly with regard to non-ferrous metal (copper and brass) corrosion, but also aluminum corrosion, and are therefore more suitable for cooling systems with aluminum components. Furthermore, coolants 3, 4, and 5 demonstrate a clear advantage in non-ferrous metal corrosion compared to coolants 1 and 2. Since seals and fittings are often made of such non-ferrous metals, reduced corrosion results in increased safety against leaks in the cooling system.

Claims

Patent claims 1 . Use of a coolant containing - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol, - optionally at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid, - optionally at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates, - at least one azole compound, - Water, - optionally at least one silicic acid ester, - optionally at least one silicophosphonate, if silicates are present, and - optionally further inhibitors and coolant-typical components, excluding a combination of alkoxylated acetylenic alcohol and corrosion inhibitors with imidazoline structure in the coolant, with the proviso that at least one mono- or dicarboxylic acid and / or at least one inorganic salt is present in the coolant, and with the further proviso that in the absence of the at least one inorganic salt, at least one dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid is present in the coolant, in a cooling system of wind turbines, preferably in a cooling system for the heat management of at least one component of a wind turbine selected from the group consisting of - generator, - Gearbox, - warehouse, - Inverters and - Adjustment system.

2. Use according to claim 1, characterized in that the coolant - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol - at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates, - at least one azole compound - Water - optionally at least one silicophosphonate, if silicates are present, preferably at least one silicophosphonate, if silicates are present, and - optional hard water stabilizer, bittering agent, defoamer and / or colorant provided that no mono- or dicarboxylic acids are present in the coolant.

3. Use according to claim 1, characterized in that the coolant - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol - at least one organic dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid, particularly preferably at least one aliphatic dicarboxylic acid, without monocarboxylic acids, - at least one azole compound - Water - optionally contains a hard water stabilizer, bittering agent, defoamer, and / or colorant, provided that no inorganic salts selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites, and nitrates are present in the coolant.

4. Use according to claim 3, characterized in that the coolant contains at least one aliphatic Dicarboxylic acid and at the same time no aliphatic monocarboxylic acids are present.

5. Use according to claim 1, characterized in that the coolant - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol - at least one aromatic organic monocarboxylic acid, - at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates, - at least one azole compound - Water - optionally at least one silicophosphonate, if silicates are present, preferably at least one silicophosphonate, if silicates are present, and - optionally contains hard water stabilizer, bittering agent, defoamer and / or colorant.

6. Use according to claim 1, characterized in that the coolant - at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol, preferably monoethylene glycol - at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid, - at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates and nitrates, preferably selected from the group consisting of phosphates and silicates, particularly preferably a silicate, - at least one azole compound - Water - optionally at least one silicophosphonate, if silicates are present, preferably at least one silicophosphonate, if silicates are present, and - optionally contains hard water stabilizer, bittering agent, defoamer and / or colorant.

7. Use according to one of the preceding claims, characterized in that the coolant has a Viscosity at 20 °C according to ASTM D445 of not more than 3 mm 2 / s.

8. Use according to any one of the preceding claims, characterized in that the azole compound is selected from the group consisting of benzotriazole and tolutriazole.

9. Use according to one of the preceding claims, characterized in that the at least one alkylene glycol, alkylene glycol monoalkyl ether or glycerol is monoethylene glycol, preferably that it consists of monoethylene glycol.

10. Use according to claim 5, characterized in that the organic monocarboxylic acid comprises benzoic acid.

11. Use according to one of claims 1, 3 or 6 to 9, characterized in that the organic Monocarboxylic acid, unless excluded, comprises 2-ethylhexanoic acid or isononanoic acid, particularly preferably isononanoic acid.

12. Use according to one of claims 1 or 3 to 9, characterized in that the organic dicarboxylic acid is selected from the group consisting of adipic acid, sebacic acid and dodecanedioic acid, preferably from the group consisting of adipic acid and sebacic acid.

13. Use according to one of the preceding claims, characterized in that the coolant is used for Thermal management of generator and / or converter is used.

14. Use according to one of claims 1 to 12, characterized in that the coolant is used for the thermal management of the transmission and / or actuating system.

15. A method for filling the cooling system of a wind turbine with a coolant, in which a concentrate containing - 0.1 to 15 wt% water - 50 to 95 wt% alkylene glycol, alkylene glycol monoalkyl ether and glycerol, - in total 0.5 to 15 wt% of the following components: - optionally at least one organic mono- or dicarboxylic acid, preferably aliphatic mono- or dicarboxylic acid, - optionally at least one inorganic salt selected from the group consisting of molybdates, borates, phosphates, silicates, nitrites and nitrates, - at least one azole compound - optionally at least one silicic acid ester, - optionally at least one silicophosphonate, if silicates are present, and - optionally 0 up to 3 wt% of further inhibitors and coolant-typical components, excluding a combination of alkoxylated acetylenic alcohol and corrosion inhibitors with imidazoline structure in the coolant, with the proviso that the sum of all components always amounts to 100 wt%, with the proviso that at least one mono- or dicarboxylic acid and / or at least one inorganic salt is present in the coolant, and with the further proviso that in the absence of the at least one inorganic salt, at least one dicarboxylic acid, preferably at least one aliphatic dicarboxylic acid is present in the coolant, mixed with water in a volume ratio of 1:1 to 1:3, transported to the wind turbine at a second location and filled there the cooling system of the wind turbine.

16. Method according to claim 15, characterized in that the filling of the wind turbine at a temperature at which the coolant has a viscosity according to ASTM D445 of not more than 3 mm 2 / s.

17. A method for the thermal management of components of wind turbines, in which heat from at least one component of a wind turbine selected from the group consisting of - generator, - Gearbox, - warehouse, - Inverters and - control system at a higher temperature is transferred to a coolant via at least one first heat exchanger, this coolant is fed in a cooling circuit to at least one second heat exchanger and there, at a lower temperature, heat is removed from the coolant by - a composition as claimed in any one of claims 1 to 12 is used as coolant, - the higher temperature is from 20 to 100 °C, preferably from 25 to 80, particularly preferably from 30 to 60 °C, - the lower temperature is between minus 50 and 40 °C, preferably between minus 40 and 40 °C, particularly preferably between minus 30 and 35 °C and - the lower temperature is at least 5 °C, preferably at least 10, particularly preferably at least 15 and most preferably at least 20 °C lower than the higher temperature.