Cleaning concentrate for turbine jet engines, cleaning solution and use thereof

Abstract

The present invention relates to a concentrate for producing a cleaning solution for turbine jet engines of aircraft. The concentrate comprises an aqueous solution having the following ingredients: - from about 16 to about 20 wt.% of one or more glycol ethers, - from about 7 to about 9 wt.% of one or more fatty alcohol alkoxylates, - about 4 to about 6 wt.% of one or more tertiary alkylamine N-oxides, - about 8 to about 10 wt.% of 2-propylheptanol ethyl ether, - about 0.5 to about 1.0 wt.% of one or more alkyl glycosides, - about 0.5 to about 1.5 wt.% of triethanolamine, - about 0.1 to about 0.5 wt.% of one or more polycarboxylates, and - about 0.1 to about 0.5 wt.% of one or more corrosion inhibitors.

Description

[0001] Cleaning concentrate for turbine jet engines, cleaning solution and its use

[0002] The present invention relates to a concentrate for producing a cleaning solution for turbine jet engines of aircraft.

[0003] The invention further relates to a cleaning solution for turbine jet engines of aircraft, which is obtainable by diluting the concentrate.

[0004] Furthermore, the invention relates to the use of the cleaning solution for the interior cleaning of a turbine jet engine.

[0005] In commercial aviation today, the vast majority of aircraft are powered by turbine jet engines, mostly in the turbofan or turbojet versions. During operation, various engine components become contaminated, particularly deposits of inorganic and / or organic substances such as soot, salts, and hydrocarbons on the turbine blades. Over time, these deposits can lead to loss of performance, damage, and thus a compromised flight safety. Regular cleaning of jet engines is therefore essential.

[0006] To perform such effective cleaning, it has so far been necessary in most cases to at least partially disassemble the jet engine. Due to the considerable labor required for disassembly and assembly, which is required in addition to the actual engine cleaning, this leads to economic losses due to the long engine downtime. It is therefore highly desirable to perform the cleaning of turbine jet engines while they are fully assembled on the aircraft, which requires correspondingly effective cleaning agents.

[0007] The present invention is therefore based on the object of proposing a cleaning solution and a concentrate for its production which enables effective cleaning of turbine jet engines, in particular also in the assembled state.

[0008] This object is achieved according to the invention by a concentrate which comprises an aqueous solution with the following ingredients:

[0009] - approx. 16 to approx. 20 wt.% of one or more glycol ethers,

[0010] - approx. 7 to approx. 9 wt.% of one or more fatty alcohol alkoxylates,

[0011] - approx. 4 to approx. 6 wt.% of one or more tertiary alkylamine N-oxides,

[0012] - approx. 8 to approx. 10 wt.% 2-propylheptanol ethyl ether,

[0013] - approx. 0.5 to approx. 1.0 wt.% of one or more alkyl glycosides,

[0014] - approx. 0.5 to approx. 1.5 wt.% triethanolamine,

[0015] - approx. 0.1 to approx. 0.5 wt.% of one or more polycarboxylates, and

[0016] - approx. 0.1 to approx. 0.5 wt.% of one or more corrosion inhibitors.

[0017] It has surprisingly been found that a cleaning solution containing the aforementioned ingredients, obtainable by diluting the concentrate according to the invention with water, enables particularly effective cleaning of turbine jet engines, particularly with regard to the effective removal of deposits on the turbine blades. To achieve this good cleaning effect, it is sufficient to introduce the cleaning solution into the assembled jet engine, in particular by spraying it in, as explained in detail below.

[0018] The concentrate according to the invention comprises one or more glycol ethers as its main ingredient. It is preferred if the concentrate contains approximately 9 to approximately 11 wt.% dipropylene glycol monomethyl ether and approximately 7 to approximately 9 wt.% diethylene glycol monobutyl ether as the glycol ether.

[0019] As fatty alcohol alkoxylate, the concentrate according to the invention preferably contains about 7 to about 9 wt% of a C9 to Cn fatty alcohol ethoxylate.

[0020] Conveniently, the concentrate can also be used as an additional ingredient.

[0021] Contain 0.1 to 0.5 wt.% of another fatty alcohol alkoxylate, which acts as a defoamer.

[0022] The concentrate according to the invention further contains one or more tertiary alkylamine N-oxides, preferably about 4 to about 5 wt.% tetradecyldimethylamine N-oxide.

[0023] The concentrate according to the invention contains about 0.5 to about 1.0 wt.% of one or more alkyl glycosides, preferably about 0.5 to about 1.0 wt.% of pentyl-D-xyloside.

[0024] The concentrate according to the invention further contains one or more corrosion inhibitors. The concentrate preferably contains a reaction product of maleic anhydride, 2-ethylhexylamine, and triethanolamine as the corrosion inhibitor.

[0025] According to a particularly advantageous embodiment of the invention, the concentrate comprises an aqueous solution with the following ingredients:

[0026] - approx. 10% by weight of dipropylene glycol monomethyl ether,

[0027] - approx. 8% by weight of diethylene glycol monobutyl ether,

[0028] - approx. 8 wt.% of a C9 to Cn fatty alcohol ethoxylate,

[0029] - approx. 5% by weight of tetradecyl-dimethylamine-N-oxide,

[0030] - approx. 0.6% by weight of pentyl-D-xyloside,

[0031] - approx. 1 wt.% triethanolamine,

[0032] - approx. 0.4 wt.% of one or more polycarboxylates, - approx. 0.1 wt.% of a fatty alcohol alkoxylate acting as a defoamer, and

[0033] - approx. 0.2 wt.% of a corrosion inhibitor, in particular a reaction product of maleic anhydride, 2-ethylhexylamine and triethanolamine.

[0034] Ingredients dissolved in water other than those mentioned in the above description are not required for the good cleaning performance of a cleaning solution prepared from the concentrate according to the invention, but are fundamentally not excluded either. According to an advantageous embodiment of the invention, however, the concentrate contains, in addition to the mentioned ingredients and water, less than approximately 1% by weight of other components, preferably less than approximately 0.5% by weight, more preferably less than approximately 0.1% by weight.

[0035] In a particularly advantageous embodiment of the invention, the concentrate contains no further components apart from the aforementioned ingredients and water.

[0036] To prepare a ready-to-use cleaning solution, the concentrate according to the invention is diluted with water. Providing it in concentrate form reduces transport and storage costs, as dilution can be carried out directly on-site.

[0037] The present invention thus also provides a cleaning solution for aircraft turbine jet engines, which is obtainable by diluting the concentrate according to the invention with water in a ratio of approximately 5:95 to approximately 30:70. A ratio of approximately 10:90 to approximately 20:80 is particularly preferred, especially since the concentrate according to the invention already exhibits very good cleaning performance at such a 10 to 20% dilution.

[0038] The invention further relates to the use of the cleaning solution according to the invention for the interior cleaning of a turbine jet engine, in particular a turbofan engine or a turbojet. As already stated, the cleaning solution according to the invention is preferably applied when the jet engine is fully assembled, which can significantly reduce its downtime.

[0039] Within the scope of the inventive use, the cleaning solution is preferably introduced into the jet engine from the upstream side of the compressor and extracted from the jet engine at the downstream side of the turbine. Advantageously, the cleaning solution can also be circulated, i.e., the cleaning solution extracted at the downstream side of the turbine is reintroduced into the jet engine from the upstream side of the compressor.

[0040] The cleaning solution is advantageously introduced into the jet engine using a spray lance, preferably at a pressure of 5 bar or less. Higher pressures are not required for the effectiveness of the cleaning solution according to the invention and should also be avoided to prevent any damage. In principle, a conventional high-pressure cleaner can also be used to introduce the cleaning solution into the jet engine. Depending on the pressure setting and spray distance, a gentle yet effective cleaning is also possible.

[0041] When the cleaning solution is sprayed into the jet engine, it is advantageously nebulized and flows through the engine components, whereby the cleaning solution comes into effective contact with the turbine blades in particular in order to remove deposits of salts, soot, etc.

[0042] The suction of the cleaning solution on the downstream side of the turbine is conveniently carried out by means of a hood that is placed on the downstream side of the jet engine.

[0043] It is particularly preferred if the cleaning solution is introduced into the jet engine at a temperature of approximately 40 to approximately 60 °C. It has been found that the cleaning performance is particularly good in this temperature range.

[0044] For effective cleaning, the cleaning solution is preferably introduced into and extracted from the jet engine over a period of approximately 5 to 10 minutes, preferably in a circuit as described above. The jet engine is then advantageously rinsed with water for a comparable period.

[0045] These and other advantages of the invention are explained in more detail with reference to the following examples.

[0046] Examples

[0047] 1. Preparation of a concentrate according to the invention and a purification solution according to the invention

[0048] In the following Table 1, the components used with the respective weight proportions are given for a concrete embodiment of a concentrate according to the invention.

[0049] Table 1: Composition of a concentrate according to the invention To prepare the concentrate, all components were dissolved in water. A clear solution was obtained.

[0050] To prepare cleaning solutions according to the invention for the experiments described below, the concentrate was diluted with water in a ratio of 5:95, 10:90 or 20:80, as indicated.

[0051] 2. Testing the cleaning performance in the Gardener test

[0052] For a quantitative comparison of the cleaning performance of different cleaning solutions in the Gardener test, a test dirt with a defined composition is applied to a white painted steel sheet and then cleaned with the cleaning solution to be tested using a wipe test machine.

[0053] The test soil used for this test has the following composition according to DIN ISO 11379-1-B.4: approx. 88 wt.% finest quartz approx. 9 wt.% kaolin approx. 1 wt.% lamp black approx. 2 wt.% paraffin oil

[0054] Two parts of this test protection were mixed with three parts of 0W40 engine oil to achieve a consistency suitable for the wipe test. This mixture was evenly applied to the white-painted test panels using a paint roller.

[0055] The cleaning performance of the respective cleaning solution is determined from the spectroscopically determined whiteness of the uncontaminated sheet (WO), the contaminated sheet (Wl) and the cleaned sheet (W2) according to the following formula:

[0056] Cleaning performance = 100% * (W2 - Wl) / (W0 - Wl)

[0057] The cleaning performance of the cleaning solution according to the invention according to Example 1 at dilutions of 5%, 10%, and 20% was compared with the cleaning performance of a commercially available jet engine cleaning solution at the same dilutions. The comparison cleaner was the product "ZOK MX Gold Standard" from the manufacturer ZOK International Group Ltd. The results are presented in Table 2 below.

[0058] Table 2: Cleaning performance in the Gardener test

[0059] The results show that the cleaning solution according to the invention is significantly superior to the comparison product at all dilutions tested. In particular, the cleaning solution according to the invention demonstrates better cleaning performance even at a 10% dilution than the comparison product at a 20% dilution, which is standard practice.

[0060] The ability to use significantly smaller amounts of the concentrate according to the invention while achieving improved cleaning performance leads to cost savings and reduced environmental impact compared to the comparison product. 3. Testing of cleaning performance based on surface roughness

[0061] Deposits on the turbine blades of jet engines (particularly salts, soot and / or hydrocarbons) that occur during operation lead to an increase in the surface roughness of the blade surfaces, which can impair the performance of the engine.

[0062] The determination of surface roughness according to DIN EN ISO 25178 or the comparison of roughness before and after cleaning is therefore a very meaningful parameter for the effectiveness of cleaning solutions for jet engines.

[0063] In this regard, the cleaning performance of the cleaning solution according to the invention according to Example 1 and the comparative product "ZOK MX Gold Standard" were compared using an immersion test, each at a dilution of 20:80. For this purpose, original contaminated turbine blades were immersed in the respective cleaning solution for 4 or 10 minutes and then rinsed with water. The test was carried out at different temperatures of the cleaning solutions (20, 30, 40, 50, and 80 °C).

[0064] The surface roughness of the turbine blades was measured before and after cleaning according to DIN EN ISO 25178 as roughness value S a The result is the percentage reduction of the roughness value due to cleaning (AS a ) is given in Table 3 below. Table 3: Reduction of surface roughness (AS a ) in the diving test

[0065] Despite the relatively high scatter of the individual results in the repeated tests, the trend clearly shows the higher effectiveness of the cleaning solution according to the invention compared to the comparison product in reducing the surface roughness of contaminated turbine blades.

[0066] The reduction in surface roughness was also investigated using a spray test. In this test, the contaminated turbine blades were sprayed with the respective cleaning solution (dilution 20:80) at 20 °C or 40 °C at a pressure of 5 bar and then rinsed with water. The determination of AS a was carried out as in the immersion test. The results are shown in Table 4 below. Table 4: Reduction of surface roughness (AS a ) in the spray test

[0067] Here, too, the significantly improved cleaning performance of the cleaning solution according to the invention compared to the comparison product is evident, particularly at an elevated temperature of 40 °C.

Claims

Patent claims for a concentrate for the production of a cleaning solution for turbine jet engines of aircraft, wherein the concentrate comprises an aqueous solution with the following ingredients: - approx. 16 to approx. 20 wt.% of one or more glycol ethers, - approx. 7 to approx. 9 wt.% of one or more fatty alcohol alkoxylates, - approximately 4 to approximately 6 wt.% of one or more tertiary alkylamine N-oxides, - approx. 8 to approx. 10 wt.% 2-propylheptanol ethyl ether, - approx. 0.5 to approx. 1.0 wt.% of one or more alkyl glycosides, - approx. 0.5 to approx. 1.5 wt.% triethanolamine, - approximately 0.1 to approximately 0.5 wt.% of one or more polycarboxylates, and - approximately 0.1 to approximately 0.5 wt.% of one or more corrosion inhibitors. Concentrate according to claim 1, wherein the concentrate contains approximately 9 to approximately 11 wt.% dipropylene glycol monomethyl ether and approximately 7 to approximately 9 wt.% diethylene glycol monobutyl ether as glycol ethers. Concentrate according to claim 1 or 2, wherein the concentrate contains approximately 7 to approximately 9 wt.% of a C9 to Cn fatty alcohol ethoxylate as a fatty alcohol alkoxylate. Concentrate according to claim 3, wherein the concentrate contains approximately 0.1 to approximately 0.5 wt.% of a further fatty alcohol alkoxylate acting as an antifoaming agent. Concentrate according to any one of the preceding claims, wherein the concentrate contains approximately 4 to approximately 5 wt.% tetradecyldimethylamine N-oxide as a tertiary alkylamine N-oxide. A concentrate according to any one of the preceding claims, wherein the concentrate contains approximately 0.5 to approximately 1.0 wt.% pentyl-D-xyloside as an alkyl glycoside. A concentrate according to any one of the preceding claims, wherein the concentrate contains a reaction product of maleic anhydride, 2-ethylhexylamine, and triethanolamine as a corrosion inhibitor. A concentrate according to any one of the preceding claims, wherein the concentrate comprises an aqueous solution with the following ingredients: - approx. 10% by weight of dipropylene glycol monomethyl ether, - approx. 8% by weight of diethylene glycol monobutyl ether, - approx. 8 wt.% of a C9 to Cn fatty alcohol ethoxylate, - approx. 5% by weight of tetradecyl-dimethylamine-N-oxide, - approx. 0.6% by weight of pentyl-D-xyloside, - approx. 1 wt.% triethanolamine, - approx. 0.4 wt.% of one or more polycarboxylates, - approx. 0.1 wt.% of a fatty alcohol α-icoxylate acting as an antifoaming agent, and - Approximately 0.2 wt.% of a corrosion inhibitor, in particular a reaction product of maleic anhydride, 2-ethylhexylamine, and triethanolamine. Concentrate according to any of the preceding claims, wherein the concentrate contains, in addition to the aforementioned ingredients and water, less than approximately 1 wt.% of further ingredients, preferably less than approximately 0.5 wt.%, more preferably less than approximately 0.1 wt.%. Concentrate according to claim 9, wherein the concentrate contains no further ingredients in addition to the aforementioned ingredients and water. A cleaning solution for turbine jet engines of aircraft, obtainable by diluting the concentrate according to any one of the preceding claims with water in a ratio of approximately 5:95 to approximately 30:70, preferably from approximately 10:90 to approximately 20:

80. Use of a cleaning solution according to claim 11 for the internal cleaning of a turbine jet engine, in particular a turbofan engine or a turbojet. Use according to claim 12, wherein the cleaning solution is introduced into the jet engine from the upstream side of the compressor and is extracted from the jet engine at the downstream side of the turbine. Use according to claim 13, wherein the cleaning solution is introduced into the jet engine by means of a spray lance, preferably at a pressure of 5 bar or less. Use according to claim 13 or 14, wherein the cleaning solution is extracted by means of a hood that is placed on the jet engine at the downstream side of the turbine.Use according to any one of claims 13 to 15, wherein the cleaning solution is introduced into the jet engine at a temperature of approximately 40 to approximately 60 °C. Use according to any one of claims 13 to 16, wherein the cleaning solution is introduced into the jet engine and extracted from it over a period of approximately 5 to approximately 10 minutes. * * *

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