RU2221833C1 - Antiicing fluid for ground treatment of aircrafts - Google Patents

Abstract

FIELD: special- destination fluids. SUBSTANCE: fluid contains, wt %: ethylene glycol 6-20, glycerol 1.5-3.0, corrosion inhibitor 1.3-4.1, surfactant 0.002-0.04, thickener 0.40-0.85, and potassium acetate aqueous solution with density 1.12-1.3 g/cu.cm and pH 9-11 - the balance. Corrosion inhibitor utilized can be phosphoric acid salts, sodium nitrite, sodium benzoate, liquid glass, or triethanolamine. EFFECT: improved environmental safety and enhanced efficiency in removing ice deposits and protecting against corrosion. 3 cl, 5 tbl

Description

 The invention relates to techniques for ground de-icing protection of aircraft in the presence of ground icing conditions.

 It is known from the prior art that icing of an airplane while it is on the ground is different from icing in flight. If in flight ice is formed, as a rule, only on the frontal parts of the aircraft, then on the ground ice usually covers most of its surface: the entire upper part of the wings and plumage, as well as the surface of the fuselage. The main danger associated with ground-based icing of the aircraft lies in the development of premature disruption phenomena (at lower angles of attack) on the icy surfaces of the wing and the tail of the aircraft, which threatens at the stage of take-off and climb with a violation of the stability and controllability characteristics of the aircraft, as well as aircraft stall (see OK Trunov, Safety of take-off under icing conditions, Moscow: GNIIGAR, 1995, p.17).

The main tools used in world practice to protect aircraft from ground icing are anti-icing liquids (VAC), which provide both the removal of ice, snow, hoar frost, hoarfrost, and the prevention of their formation on the aircraft surface for some time. The following basic requirements are presented to the life support system:
- high efficiency removal of all types of ground icing: hoarfrost, hard (crystalline) plaque, hoarfrost, ice;
- the ability to protect the surface of the aircraft from ice formation in conditions of freezing precipitation (supercooled rain, wet snow, drizzle) for some time;
- the ability to completely discharge (blow off, drain) liquid from the wing surface during take-off (at speeds greater than 160 km / h);
- low energy consumption when pumping at low temperatures;
- safety when handling it (non-toxicity);
- have a minimal negative impact on the environment (since only 20-25% of the liquid is directly involved in the de-icing process), since most of the liquid flows to the ground during processing of the aircraft or is blown off its surface by the wind. The liquid remaining on the surface of the aircraft is necessarily discharged during take-off and spreads along the runway and further in flight.

 De-icing fluids are divided into two types: type I and type II. Type I RLF does not require long-term protection of the aircraft from re-icing after the plane is flooded - it must rise into the air in a matter of minutes, and when lifted, release the RLP together with melted ice (snow, hoarfrost, etc.) to the ground. Type I LSS is an ordinary Newtonian flow.

 Type II RLP requires longer-term aircraft protection, long-term resistance to supercooled rain, lower temperatures, etc. For this, highly thickened compositions with toxotropic properties and a non-Newtonian course are used.

 The present invention relates to type I.

 The most widespread are POG based on ethylene glycol and diethylene glycol. Glycols serve to lower the temperature of the onset of crystallization of the fatty acid and represent, along with water, its main components in a concentration of from 40 to 95 wt.%.

 In the table. Figure 1 shows the current basic technical specifications of type I-LAV.

 Known anti-icing liquid for ground handling of aircraft (PCT / W 093 / 24543,1998) is a mixture of glycol, water and a thickener, the second one uses an alkali-swellable polymer thickener in the following ratio of components in wt.%: Glycol, for example ethylene glycol 50-95 ; thickener 1-5; the rest is water.

 The patent (RU-C1-2100398, 1997) describes an anti-icing liquid for ground processing of aircrafts based on glycol and water, which as a surfactant contains benzenesulfonate methyl diethyl aminomethyl derivatives of diethylene glycol fatty acid esters, as well as dibasic alkali metal phosphate and stearic acid.

 Patent RU-C1-2141990, 1999 describes anti-icing liquid for ground processing of an aircraft based on glycol and water, which does not contain a thickener. The required viscosity parameters of the liquid were achieved due to the use of one nonionic surfactant from the group of fatty alcohols and alkoxylated with low molecular weight alkoxide of fatty alcohols and one surfactant from the group of alkaryl alkylaryl sulfonates as a surface-active component.

 The disadvantages of the above anti-icing fluids for ground handling of aircraft are high toxicity due to the use of ethylene glycol and diethylene glycol with a high glycol content of 40-95 wt.%, As well as the high cost due to the same reason. In addition, the corrosion inhibitors used in the patent RU-C1-2141990 based on ethylene glycol (taken as a prototype) do not provide a high rate of corrosion inhibition of metals, in particular aluminum alloys.

Existing, the most widely used fluids on the glycol antifreeze component also have technological disadvantages. ARCTIC, when used, cannot be diluted with water (see OK Trunov. Take-off safety under icing conditions, M .: GNIIGAR, 1995), which makes it not economical for this reason: it is believed that the working fluid should have a crystallization temperature of only 10 ^o C below atmospheric air. At the same time, 80% of icy situations occur in the region of 0 ^o C. POZH with the name "OKTOFLO" can be diluted with water, but distilled (Recommendations for use). The latter makes this RLP not technologically advanced due to the absence of hundreds of tons of distilled water at aerodromes.

 The present invention is aimed at solving a technical problem, which consists in providing a significant increase in environmental safety, while increasing the efficiency of removing ice deposits on the machined surfaces and the rate of inhibition of metals (steel, aluminum, cadmium, zinc alloys), as well as reducing its cost, in particular , through the use of a cheaper antifreeze component, which is potassium acetate. It should be borne in mind that propylene glycol is the only glycol that is not toxic. Its use in conjunction with potassium acetate makes the pancreas completely environmentally friendly. The use of propylene glycol in small amounts comparatively thickens the fatty acid in comparison with ethylene glycol, but within acceptable limits: Type I fatty acid should have a viscosity not much more than water. However, the use of propylene glycol alone as an antifreeze component is not possible due to the high viscosity and cost of propylene glycol.

 The advantage of the proposed anti-icing liquid for ground handling of aircraft over the known (taken as a prototype) is that thanks to the use of an aqueous solution of potassium acetate and a significant (almost an order of magnitude) decrease in the glycol content in it, not only a sufficiently high environmental safety is provided (hazard class IV according to GOST 12.1.005-88 due to a significant reduction in the content and type of glycols) and lower corrosion activity.

The task of increasing the environmental friendliness and cheapening of type I ROD by using an aqueous solution of potassium acetate (a 50% aqueous solution has a crystallization onset temperature of -60 ^o C) could be solved only after a technical solution was found that would guarantee the impossibility of the appearance of a surface treated aircraft saline composition, “efflorescence” during drying, blowing, temperature change, etc., since the presence of various roughnesses on the aircraft streamlined by air structures reduces its aerodynamic skie characteristics.

To solve this problem, liquid organic components should be introduced into the RLP formulation, which could:
1. To have greater solubility and completely absorb (dissolve in itself) inorganic salt content of antifreeze and inhibitory part of the prostate cancer;
2. Due to low volatility, they are not only non-drying, but also hygroscopic;
3. By their nature, additionally have structural or inhibitory properties.

 As a result of the studies, requirements 1-3 vary in varying degrees with the following substances: glycols, glycerin, triethanolamine, which are included in the formulation of the prostate.

 The guarantee excluding the appearance of the so-called "efflorescences" was provided by the following two series of experiments.

 1. The above liquid substances were taken, wt.%: Glycols 6-20, glycerol 1.5-3.0, triethanolamine 0.14-0.5 and without it, where (in dry form) components that could be antifreeze were introduced , metal inhibitors and existing in dry form, wt.%: potassium acetate up to 50, disodium phosphate 0.7-1.54, trisodium phosphate 0.1-0.4, sodium nitrite 0.01-0.06, sodium benzoate 0, 25-0.7, thickener 0.4-0.85, liquid glass 0.1-0.9.

 With the introduction of a complex of dry components in the above liquid compositions in all cases (without water, which is usually about 50 wt.% In the LSS), liquid opaque rolling compositions were formed. When applied to a solid surface with a thin layer, they quickly increased mobility due to the absorption of water from air due, first of all, to hygroscopic potassium acetate, which is also a powerful inhibitor of aluminum corrosion.

 When only 10 wt.% Water is introduced into liquid opaque compositions, which corresponds to almost unrealistic (low) air humidity (in the region of 10%), liquids turn into transparent rolling compositions that are easily blown off from solid surfaces.

2. De-icing fluids of the following composition, wt.%:
- glycol 6-20
- glycerol 1.5-3.0
- Surfactant / neonol, shampoo, etc. / 0.002-0.04
- corrosion inhibitors (listed above) 1.3-4.1
- thickener / sulfocell, acrylic resin, etc. / 0.4-0.85
- an aqueous solution of potassium acetate with a density of 1.12-1.3 g / cm ³ and pH 9-11 - the rest,
were applied to the bottom of Petri dishes located at an angle of 45 ^o to the horizontal at t = 20 ^o C and -15 ^o C, while being blown off by air (simulating the movement of the aircraft) at a speed of 60 km / h. Under the influence of gravitational forces, the coolant flowed down, forming different film thicknesses in height, and during the hour of the experiment it was constantly flooded due to the hygroscopicity of the coolant, which was accompanied by thinning of the thickness of the liquid film. The process of processing the aircraft before it takes off when using type I RLF is measured in minutes.

 The experiments showed a practical solution to the technical problem - the guaranteed absence of salt "efflorescence" of the fatty acids, where the main antifreeze role is played by an environmentally friendly salt composition - an aqueous solution of potassium acetate.

 Potassium acetate does not possess (unlike nitrates) oxidizing properties, is less corrosive than chloride solutions, and unlike glycols, it is environmentally friendly.

 Potassium acetate is highly biodegradable. The period of complete decomposition in nature is 28 days. Potassium acetate does not adversely affect the biological environment of water bodies due to the fact that the decomposition of acetates takes place without the formation of ammonium and, as a result, is not toxic to fish. The first anti-icing reagent for runways in European airfields was awarded the Gold Medal.

 In the proposed liquid antifreeze component is (unlike the prototype) an aqueous solution of potassium acetate. The presence in the proposed liquid of additional organic components (propylene glycols, and / or monoethylene glycol, and / or diethylene glycol, and / or triethylene glycol) or other substances that are practically non-volatile at normal temperatures and absorbing the saline components of the RVF, allowed to obtain a technical result that is not follows from the prior art, namely: in the case of evaporation (hypothetically) of water on the treated surfaces, salt deposits ("efflorescences") do not form, the presence of which will inevitably lead to the aerodynamic parameters of the aircraft, especially when taking off.

 As regards the proposed content of glycols, surfactants, glycerin and corrosion inhibitors of ferrous and non-ferrous metals, thickener in the anti-icing liquid for ground processing of aircraft, the upper and lower limits of the contents of the above components were determined on the basis of statistical processing of a large number of experimental results, achieving the desired viscosity antifreeze and anticorrosive properties.

The problem in the field of ecology is solved by the fact that the anti-icing liquid for ground handling of aircraft, including at least one glycol and corrosion inhibitors, according to the invention further comprises an aqueous solution of potassium acetate with a density of 1.12-1.3 g / cm ³ and pH 9-11, glycerin, surfactant, thickener, while it contains either propylene glycol or monoethylene glycol or diethylene glycol or triethylene glycol or a mixture thereof in the following ratio, wt.%: glycol 6-20, glycerin 1, 5-3.0, inhibit ry corrosion 1,3-4,1, 0,002-0,04 surfactant, thickener 0,4-0,85, aqueous potassium acetate solution with a density of 1,12-1,3 g / cm ³ and a pH of 9.11 - Others . As corrosion inhibitors, the anti-icing fluid contains phosphoric acid salts: disodium phosphate 0.69-1.5, trisodium phosphate 0.2-0.64, sodium nitrite 0.01-0.06, sodium benzoate 0.2-1.0, liquid glass 0.2-0.9.

 In a preferred embodiment, the anti-icing fluid contains phosphoric acid salts as corrosion inhibitors: disodium phosphate 0.7-1.54, trisodium phosphate 0.1-0.4, sodium nitrite 0.01-0.06, sodium benzoate 0.25-0, 7, water glass 0.1-0.9, triethanolamine 0.14-0.5.

Due to the presence of propylene glycol and / or monoethylene glycol and / or diethylene glycol and / or triethylene glycol, glycerin, surfactant, thickener in the proposed anti-icing liquid for ground handling of aircraft, it was possible (with the above ratios of components) to provide such structure-viscosity and film-forming properties of liquids that on the one hand, provide (in the temperature range from 0 to -10 ^o C) on the treated surfaces of the protective film of liquid with a thickness of 50 to 15 microns in the range of 15-60 ^o tilt angles on the treated surface relative to the horizontal plane, and on the other hand, the complete removal of fluid from the treated surfaces during take-off, since the proposed type I RMP has a low viscosity (see Table 3) and the usual Newtonian flow, which guarantees its deflation during take-off. The liquid without a thickener has a viscosity at 20 ^o C of only 4.8 ... 5.1 centistokes and does not provide the required thickness of the liquid film / amount of reagent per 1 m ^{2 of the} treated surface / and, therefore, the melting of thick layers of frost or ice. Moreover, thickened reagents linger longer on inclined surfaces.

 The above data on the thickness of the life-saving films at various angles of inclination, made at the All-Union Institute of Aviation Materials, indirectly confirm the assertion that the proposed solution provides protection against re-icing at the level (not lower) of the existing life-support materials. Standard data on the time to protect structures from re-icing (for a very short time, measured in minutes) in the modern world are obtained at a special installation in Toronto (Canada).

 Our claimed more effective removal of ice deposition is achieved due to the lower crystallization onset temperature and the exothermic effect of ice dissolution with an aqueous solution of potassium acetate.

Table 2 shows the comparative pro-melting ability of the claimed formulation and the currently used ALP ARCTIC. As can be seen from the table, the rate of penetration of ice by the proposed composition on average exceeds 2 times. The method for determining the melting ability of the RLP is that 30 ml of RLP is poured into ice in 100 ml of water. The resulting liquid is periodically drained and the amount of molten ice / ml / is determined. In these tests, a liquid was used with a density of γ = 1.28 g / cm ³ , pH 10.5, 0.4 wt.% Sulfacell, 0.006% neonol, 9% ethylene glycol, 2.5% glycerol and inhibitors according to claim 3 of the formula inventions.

Table 3 shows the physicochemical properties of the claimed POG, from which it follows that its temperature and other characteristics meet all the requirements, and the main operating temperatures are within the limits of dilution with ordinary fresh water 1: 1 and 1: 2, since the bulk of the ice situations is in the region 0 ^o C.

 The use of a salt composition in the antifreeze part of the VOL of PHL required a particularly careful selection of corrosion inhibitors, especially since the inhibitors also perform other functions (absorbers, structuring components, etc.).

 In the table. 4 shows the compositions of the accepted inhibitory compositions providing surfactants with sufficiently high anticorrosive properties (see Table 5). The choice of an inhibitor complex variant is dictated by both cost considerations and considerations of providing viscous and anticorrosive characteristics.

 Potassium acetate (as a component of the liquid for ground handling of airplanes) is obtained according to paragraph 1 of RF Patent 2142491 “Method for the preparation of anti-icing liquid composition” with a difference in the list of water-soluble additives introduced during production.

 The main component of the reagent by mass content - potassium acetate - has a large raw material base in the country and has been mastered in the large-scale production of anti-icing liquid for runways of airfields in Russia, the CIS and the Baltic States according to the aforementioned V. Orlov patent. and license agreement with registration 11553/2000. Based on three years of experience in the production and use of liquid acetate anti-icing agents, our proposed liquid for ground processing of aircraft by industry is applicable.

Claims (3)

1. An anti-icing liquid for ground handling of aircraft, including at least one type of glycol and corrosion inhibitors, characterized in that it additionally contains an aqueous solution of potassium acetate with a density of 1.12-1.3 g / cm ³ and pH 9- 11, glycerin, a surfactant, a thickener, while it contains propylene, mono-, di-, or triethylene glycol or a mixture thereof in the following ratio of components, wt.%: As glycol Glycol 6-20 Glycerin 1.5-3.0 Corrosion Inhibitor 1.3-4.1 Surface active substance 0.002-0.04 Thickener 0.40-0.85 Acetate aqueous solution potassium with a density 1.12-1.3 g / cm ³ and pH 9-11 2. The anti-icing liquid according to claim 1, characterized in that as corrosion inhibitors it contains salts of phosphoric acid, sodium nitrite, sodium benzoate and liquid glass in the following ratio, wt.%: Disodium phosphate 0.69-1.5 Trisodium phosphate 0.20-0.64 Sodium nitrite 0.01-0.06 Sodium benzoate 0.2-1.0 Liquid glass 0.2-0.9 3. The anti-icing fluid according to claim 1, characterized in that as corrosion inhibitors it contains salts of phosphoric acid, sodium nitrite, sodium benzoate, water glass, triethanolamine, in the following ratio, wt.%: Disodium phosphate 0.7-1.54 Trisodium phosphate 0.1-0.4 Sodium nitrite 0.01-0.06 Sodium benzoate 0.25-0.7 Liquid glass 0.1-0.9 Triethanolamine 0.14-0.5

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