RU2799121C1 - Method for identification of antiwear additive high-tech 580 in jet fuel - Google Patents

Abstract

FIELD: materials research using infrared light.

SUBSTANCE: invention relates to the field of quality control of fuels for jet engines using infrared spectroscopy to determine the presence of antiwear additive High-Tech 580 in fuel. The essence of the method lies in the fact that a sample is taken, the additive is accumulated in the fuel sample using an apparatus for evaporating with an air jet, then they are dissolved in an alcohol-toluene mixture taken in a ratio (1: 4) several times, sequentially transferring the solution in small portions to the crystal attachments of zinc selenide for the IR-Fourier spectrometer, evaporate the resulting solution until the solvent dries, scan the IR spectrum of the sample, determine the presence of the additive by the coincidence or difference of the spectra profiles with the test results of artificially prepared standard samples in the range from 1800 to 1600 cm^-1.

EFFECT: increased efficiency of control with a minimum sample volume for testing.

1 cl, 5 dwg, 2 tbl

Description

The invention relates to the field of quality control of fuels for jet engines (hereinafter referred to as turbojet engines) using IR spectroscopy based on the Fourier transform, mainly for determining additives, in particular the presence of antiwear additive "High-tech 580" and can be used in analytical laboratories, laboratories of oil supply enterprises.

The use of antiwear additives in the composition of fuels for jet engines (hereinafter referred to as fuels) makes it possible to reduce the wear of friction pairs of fuel control equipment (TRA). Given the importance of the antiwear properties of the fuel in ensuring the reliability of the TPA, there are methods for determining the concentration of the antiwear additive using RJ spectroscopy.

It is known that in the operation of jet engines, fuels containing antiwear additives are used, which make it possible to most effectively combat the wear of friction pairs of TPA. The main active components of additives are monomers and dimers of carboxylic acids (linoleic, linolenic, oleic, etc.). The most common additive for turbojet engines is Hi-Tech 580. Produced by Afton. This is a phosphorus-free anti-wear additive, it is a transparent amber oily liquid with a density of 0.92 g / mg and a pour point of -18 ° C (Internet site https://neftregion.ru/obyavleniya/nefteprodukty/protivoiznosnaya-prisadka-Afton- Hitec-580, 01/13/2023), is a multicomponent mixture, the main active ingredient of which is linoleic acid dimer. It is introduced into jet fuel in the amount of 0.002-0.004% (TU 38.01237-90)

In practice, it is not always necessary to determine the quantitative content of the additive in the turbojet engine, so in order to confirm the refueling of the aircraft with the necessary fuel declared in the instructions, it is necessary to establish its belonging to a particular brand, which is especially in demand in the process of investigating flight accidents, given the insufficiency of the sample of the turbojet engine. To do this, it is often necessary only to determine the presence or absence of antiwear additives, and the volume of the analyzed fuel does not always reach 1000 cm ³ .

Currently, the authors have not found methods to determine the presence of additives in the minimum amount of a fuel sample (the minimum allowable amount is 50 cm ³ ).

The authors were faced with the task of developing a reliable operational method for determining the presence of the Hi-Tech 580 antiwear additive in a turbojet engine, which could be implemented on the equipment available in the laboratory, would be low-cost, with short testing times and the need for a sample in an acceptable minimum size.

When conducting research on the quality of turbojet engines, it was found that by determining the actual resins (the method is necessary to assess the quality of turbojet engines), a resinous residue is obtained that is no longer used (waste of the experiment). After studying the resinous residue using available methods, traces of the antiwear additive "High Tech 580" were found even in small quantities, which became the preferred requirement for the development of a method for determining the antiwear additive "High Tech 580".

When analyzing patent information and scientific and technical literature, technical solutions were identified that partially solve the problem.

A known method for determining the content of antiwear additives based on fatty acids in diesel fuels, which is determined using IR spectroscopy, which consists in separating a sample using solid-phase extraction, ethanol as an eluent, and IR spectrometry at a wave number of 1710 cm ^-1 . Determination of the amount of antiwear additive based on fatty acids is carried out according to the calibration curve. (RU 2723974)

The proposed method requires a lot of time due to long-term complex analytical operations - the use of more than three types of solvents.

There is also known a method for determining the presence of depressant additives in diesel fuels, including the introduction of a catalyst - an aqueous ammonia solution of Cu(II) into a sample of diesel fuel in the specified ratio, mixing and keeping at a temperature of 40÷60°C for 50±10 s, cooling to room temperature and evaluating the result by the turbidity of the solution. (RU 2199738)

However, this method has a limitation. It is applicable only to the determination of pour point depressants.

The closest in technical essence and taken as a prototype is a method for determining the amount of additives "Hitek-580" and "Agidol-1" in jet fuels, including sampling, measuring optical density and subsequent calculation of the concentration of the additive, which is divided into two equal parts , one of which is evaporated before spectrophotometry under a vacuum of 0.5 MPa, gradually heating to 214 ± 0.5 ° C and measuring the current value of the sample volume, after reaching which 5-10 cm ³ the optical density of the sample residue is measured on the absorption band 1711.32 cm ^-1 and fix its value equal to the length of the segment from the peak of the spectrum to the point of intersection with the base line drawn between the minimum values of the optical density of the sample residue in the absorption bands 1761.68 cm ^-1 and 1699.0 cm ^-1 , after which the amount is calculated additives Hitech-580 according to mathematical dependence using optical density and experimentally obtained coefficients; and the other part of the fuel sample is subjected to extraction and the total content of two additives is determined in it by the calculation formula using the extraction coefficient and empirical coefficients; and the amount of Agidol-1 additive is estimated by the difference between two calculated values of two concentrations. (RU 2593767 - prototype)

The disadvantage of this method - the prototype is a large number of preparatory operations, a significant duration of the test (more than three hours), the use of a large sample volume (at least 1000 cm ³ ), which is not always possible in practice. In special cases, the amount of fuel to be analyzed is less than 100 cm ³ .

The technical result of the invention is the expansion of the range of methods for determining the presence of antiwear additive "High-tech 580" in the turbojet engine with a simultaneous increase in efficiency with a minimum amount of sample for testing.

The specified technical result is achieved by the fact that in the known method for determining the presence of antiwear additive "High-Tech 580" in jet fuel, including sampling and removal of the RJ spectrum in the range from 1800 to 1600 cm ^-1 , according to the invention, the RJ spectrum is taken with obtained during the test of the analyzed fuel on the apparatus for evaporating the sample in an air stream of the tarry residue, which is preliminarily washed in portions until the moment of visual control of the cleanliness of the glass with an alcohol-toluene mixture taken in a ratio of 1: 4, transferring the wash products to the crystal of the attachment of the RJ-spectrophotometer, removing solvent until a total tarry residue is obtained, and the presence of an additive is judged by the coincidence or difference in the spectrum profiles in a given range with the test results of artificially prepared standard fuel samples with an antiwear additive "High-tech 580".

In FIG. 1 shows a fragment of the RJ spectrum of resinous residues of standard samples of turbojet engines without antiwear additive Hitech 580 from the RJ-Fourier Nicolet 6700 database;

fig. 2 - a fragment of the RJ spectrum of resinous residues of standard samples of turbojet engines containing the antiwear additive Hitech 580 from the RJ-Fourier Nicolet 6700 database;

fig. 3 - a fragment of the RJ spectra of resinous residues of the turbojet engine containing the additive Hi-Tech 580 and the additive Hi-Tech 580 from the database of the RJ-Fourier spectrometer Nicolet 6700;

fig. 4 - a fragment of the IR spectra of standard samples of the turbojet engine and the Nicolet 6700 IR-Fourier spectrometer received for testing from the database;

fig. 5 - A fragment of the RJ spectrum of standard samples of the TRD and the Nicolet 6700 RJ-Fourier spectrometer received for testing from the database of the RJ-Fourier spectrometer.

To explain the implementation of the method and confirm the technical result, the following symbols are adopted:

1 - RJ spectrum of a standard sample of a turbojet engine without antiwear additive Hitech 580

2 - RJ spectrum of a standard sample of a turbojet engine without antiwear additive Hitech 580

3 - RJ spectrum of a standard sample of a turbojet engine without antiwear additive Hitech 580

4 - RJ spectrum of a standard sample of a turbojet engine with a content of antiwear additive Hitech 580 0.0031%

5 - RJ-spectrum of a standard sample of a turbojet engine with the content of the antiwear additive Hitech 580 0.0035%

6 - RJ-spectrum of a standard sample with the content of antiwear additive Hitech 580 0.0028%

7 - RJ spectrum of antiwear additive Hitech 580

8 - RJ spectrum of the image (example 1)

9 - RJ spectrum of the image (example 2)

a - absorption intensity value (example 1)

b - absorption intensity value (example 2)

The obtained standard samples were used to confirm the technical result, developed a new method for determining the presence of antiwear additive "High-Tech 580" in jet fuel. The composition of the samples presented above are summarized in table 1. The prepared samples were tested for use in the claimed method and were entered into the database of the RJ spectrophotometer (Fig 1, 2). Determination of the presence of antiwear additive "High-Tech 580" was achieved by fixing the areas of absorption characteristic of functional groups (COO-) (Fig. 3 spectrum 7). In FIG. 1 and 2, there are clearly differences in the height of the peak in the region of 1711 cm ^-1 , which indicates the possibility of determining the presence of antiwear additive "High-tech 580" in the range as in the prototype.

The use of the residue obtained during the test of the analyzed fuel on an apparatus for evaporating the sample in an air stream in combination with the selected solvent made it possible to partially achieve the technical result. The well-known spirto-toluene mixture was used as a solvent, however, it was necessary to conduct research on the selection of the ratio of these two components (table 2). The mixture for dissolving the resinous residue on the walls of the glass cup should dissolve both aliphatic and aromatic hydrocarbons. Based on these requirements, a mixture of alcohol and toluene was used. Research on the selection of a solvent was carried out using artificially prepared samples of turbojet engines (table 1) with a known content or absence of antiwear additive Hitech 580. Mixtures of solvents with different ratios were prepared (table 2).

As can be seen from the results of table 2, the most effective ratio of the alcohol-toluene mixture is 1:4, which dissolves the resulting resinous residue.

A necessary and sufficient feature of this method is the application of washout on the attachment crystal, which was tested on standard samples prepared in the laboratory (table 1). To do this, the washout products were applied in minimal portions to the crystal of the attachment, controlling the uniform distribution over the entire area of the crystal, the solvent was removed by blowing air at room temperature. The volume of portions taken for evaporation on the attachment was chosen based on the requirements of applying a controlled volume to the crystal in the form of a thin layer over the entire surface of this crystal. After visual control of the evaporated solvent (a resinous residue remains on the crystal), the next portion was applied from the resulting wash product, and so on until the wash products were completely consumed.

The method is implemented as follows:

The sample, which has been tested in accordance with GOST 32404 on an apparatus for evaporating with an air jet, is removed from the beaker, cooled to room temperature, the resulting resinous residue is washed off in portions with an alcohol-toluene mixture prepared in a ratio of 1: 4, sequentially quantitatively transferred to the surface of the attachment crystal, removing the solvent, removed IR spectrum of resinous residue. During this operation, the attachment and the sample are at ambient temperature. The profile of the obtained IR spectrum is compared with the profiles of the spectra in the absorption ranges of the functional groups included in the group and individual composition of the additive (from 1800 to 1600 cm ^-1 ) with an absorption maximum of approximately 1711 cm ^-1 . The profile of the obtained RJ spectrum is compared with the spectra profiles entered into the database of the measuring instrument (FIGS. 1 and 2). Significant test results of fuel samples for the presence or absence of the antiwear additive "High-tech 580" are recognized as results that coincide or differ in the absorption ranges of functional groups responsible for the group and individual composition of the additive (from 1800 to 1600 cm ^-1 ) with an absorption maximum of about 1711 cm ^{- 1} (Fig. 3), which are part of the fuel and manifested in the spectra of tarry residues, correlated with the composition and brand of the fuel under study.

Example 1

It is necessary to determine the presence of the Hi-Tech 580 additive in the TRD sample (Fig. 4, spectrum 8) submitted for testing, which cannot be determined by the known method, since the sample volume did not exceed 150 ^cm3 .

The test is carried out in accordance with GOST 32404 “Petroleum products. Method for determining the actual resin content by jet evaporation. To do this, take 50 cm ³ samples of the turbojet engine, transferred to a glass beaker, which is placed in an apparatus for evaporation with a jet of air for 30 minutes, removed, cooled to room temperature. The resulting resinous residue is washed off in portions with an alcohol-toluene solution, taken in the ratio according to table 2 line 4. The washing products are sequentially transferred in minimal portions to the surface of the attachment crystal, each portion is evaporated, removing the solvent, blowing with an air stream. The infrared spectrum of the obtained residue is scanned, according to the coincidence of the profiles or the mismatch of the obtained IR spectrum with the spectral profiles entered into the database of the measuring instrument (samples from table 1), the presence or absence of an additive in the region from 1800 to 1600 cm ^-1 with an absorption maximum is judged on the strip 1711 cm ^-1 (Fig. 4). As can be seen in Fig. 4, a significant difference in the spectrum of TRD 1 with spectra 8 and 4, in terms of peak height, absorption intensity (a), with an absorption maximum of 1711 cm ^-1 , which makes it possible to judge the presence of the antiwear additive "High-Tech 580" in the sample obtained during testing .

When comparing the IR spectra (Fig. 4) from the database of the device 1, 4 with the test sample 8 in the region from 1800 to 1600 cm ^-1 , the spectrum profile is close to the IR spectrum of the sample 4, which is evidence of the presence of the antiwear additive "High Tech 580" .

Example 2

It is necessary to prove the absence of the additive "High-tech 580" in the sample (Fig. 5 spectrum 9) received for testing, which cannot be determined by a known method, because the sample volume did not exceed 200 cm3.

The preparation and testing for the presence or absence of the Hi-Tech 580 additive is similar to example 1. The results of comparing the spectra are shown in Fig. 5. In FIG. 5, one can clearly see the difference in the profiles of spectra 9 and 1 with spectrum 4 (the absorption intensity of sample 9 in the 1711 cm ^-1 band is close to the intensity of sample 1 from the instrument database), which is evidence of the absence of the Hi-Tech 580 antiwear additive.

The claimed method was used to analyze samples of other fuels received to monitor the presence of antiwear additive "High-tech 580" in the turbojet engine. The volume of these samples did not exceed 400 cm3.

Thus, due to the combination of the essential features set forth in the formula, the claimed invention expands the range of methods for determining the presence of the antiwear additive "High-Tech 580". The time for determining the presence of the antiwear additive "High-tech 580" is no more than 1-1.5 hours, which confirms the efficiency of the proposed method with the minimum allowable sample volume (50 cm ³ ) of the analyzed fuel.

Claims (1)

A method for determining the presence of antiwear additive "High-Tech 580" in jet fuel, including sampling and taking an IR spectrum in the range from 1800 to 1600 cm ^-1 , characterized in that the IR spectrum is taken from the analyzed fuel obtained during the test on apparatus for evaporating the sample in an air stream of the resinous residue, which is preliminarily washed in portions until the visual control of the purity of the glass with an alcohol-toluene mixture taken in a ratio of 1: 4, transferring the washing products to the crystal of the attachment of the IR spectrophotometer, removing the solvent until a total resinous residue is obtained, and the presence of an additive is judged by the coincidence or difference in the profiles of the spectra of the total tarry residue and artificially prepared standard samples of fuel with the antiwear additive "High-tech 580".

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