A method for testing the water separation index of jet fuel

Abstract

This invention relates to a method for testing the water separation index of jet fuel, specifically relating to the field of testing and analysis technology. The method includes: taking samples from the jet fuel containing carmine and water, denoted as Sample 1 and Sample 2; testing the absorbance of Sample 1 under ultraviolet light at a wavelength of 216 nm to obtain a first test result X1; separating water from Sample 2, and then testing the absorbance of the separated sample under ultraviolet light at a wavelength of 216 nm to obtain a second test result X2; and calculating the water separation index W based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s =|X1-X2| / X1. This invention provides a testing method that improves the accuracy of the water separation index test in ultraviolet analysis by introducing a specific carmine into the detection system. This is because carmine is highly sensitive to ultraviolet absorbance in jet fuel systems, which is beneficial for improving detection results.

Description

Technical Field

[0001] This invention relates to the field of testing and analysis technology, and specifically to a method for testing the water separation index of jet fuel. Background Technology

[0002] The quality of jet fuel is crucial for flight safety and directly affects aircraft performance. Jet fuel quality control testing mainly includes parameters such as composition, cleanliness, distillation range, combustibility, and flowability. The most important indicator of cleanliness is the water separation index, which measures the ability of jet fuel to separate water when passing through a glass fiber filter medium. This index ranges from 50 to 100; a higher value indicates a cleaner and more transparent fuel.

[0003] Excessive surfactants in jet fuel, such as sulfonates and naphthenates, can lead to problems like oil-water separation failure and poor water settling, thus reducing the fuel's water separation index. A low water separation index in jet fuel will affect the aircraft's fuel system's dehydration performance, easily causing fuel icing in the low-temperature environment of high altitudes. In severe cases, this can lead to engine failure and flight accidents. Therefore, efficient and accurate measurement of the water separation index of jet fuel is particularly important in the aerospace field.

[0004] Currently, the following testing standards exist for detecting the water separation index in jet fuel:

[0005] The ASTM D8073 method uses a fluorescent detector, which is expensive and difficult to promote in the industry; the detection process is complex and takes a long time; it uses a fluorescent dye as an indicator, which is a consumable and expensive, and long-term use may have a certain impact on the health of laboratory personnel.

[0006] The ASTM D3948 and ASTM D7224 methods are based on visible light transmittance to test the water separation index of jet fuel. However, visible light has low energy and requires a high sample concentration to produce a significant change in absorbance, resulting in relatively low detection sensitivity.

[0007] Based on this, the existing technology CN115753661A describes a method and system for measuring the water separation index of jet fuel based on ultraviolet spectroscopy, belonging to the field of jet fuel detection technology. This invention determines the wavelength of the ultraviolet spectral band of the jet fuel to be tested, preprocesses the jet fuel, and then uses a stable amplified output voltage signal obtained after processing by an optical subsystem and a signal processing subsystem. Using a fitted water separation index model, the water separation index of the jet fuel to be tested is calculated. However, the disclosed detection process still suffers from poor measurement accuracy, which is not conducive to the detection of the water separation index of jet fuel. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for testing the water separation index of jet fuel, so as to solve the defect of low detection accuracy in the water separation index based on ultraviolet light testing.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] This invention provides a method for testing the water separation index of jet fuel, the method comprising:

[0011] Samples were taken from the jet fuel containing carmine and water to be tested, and labeled as Sample 1 and Sample 2.

[0012] Sample 1 was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm, and the first test result X1 was obtained;

[0013] Sample 2 was subjected to water separation. After water separation, the sample was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm to obtain the second test result X2.

[0014] The water separation index W was calculated based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s =|X1-X2| / X1.

[0015] The water separation index testing method provided by this invention improves the detection accuracy of water separation index testing in ultraviolet analysis by introducing a specific carmine into the detection system. This is because carmine is highly sensitive to ultraviolet absorbance in the jet fuel system targeted by this invention, which is beneficial to improving the detection effect.

[0016] As a preferred technical solution of the present invention, the jet fuel containing carmine and water is obtained by sequentially mixing carmine, water and jet fuel and ultrasonic emulsifying.

[0017] As a preferred embodiment of the present invention, the power of the ultrasonic emulsification is 1000-2000W.

[0018] Preferably, the ultrasonic emulsification time is 3-5 minutes.

[0019] As a preferred embodiment of the present invention, the concentration of carmine in the jet fuel containing carmine and water is 0.5-1 μg / L.

[0020] As a preferred embodiment of the present invention, the water volume percentage in the jet fuel containing carmine and water is 0.03-0.05%.

[0021] As a preferred embodiment of the present invention, the water separation is performed using a coalescing filter.

[0022] As a preferred technical solution of the present invention, the water separation temperature is 18-29℃.

[0023] As a preferred embodiment of the present invention, the flow rate is controlled at 25-30 mL / min during water separation.

[0024] As a preferred technical solution of the present invention, the filter material used in the water separation includes filter materials that meet the requirements of API / EI 1581, 5th edition.

[0025] As a preferred embodiment of the present invention, the water separation time is 7-9 minutes.

[0026] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0027] (1) Compared with existing technical solutions, the addition of carmine can improve detection sensitivity and accuracy. Carmine is an azo compound, which contains a pyridine ring. This structure usually has electron-withdrawing function. Electron-withdrawing groups increase ultraviolet absorption intensity, thereby improving detection sensitivity and accuracy.

[0028] (2) Compared with the existing technical solutions, the present invention selects the 216nm wavelength corresponding to the strong absorption peak of carmine in the ultraviolet band as ultraviolet light, which has high energy and can reduce the detection limit of ultraviolet absorbance.

[0029] (3) Compared with the existing technical solutions, the detection principle and testing procedure of the present invention are simple, which can improve detection efficiency and reduce costs. Detailed Implementation

[0030] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0031] This embodiment provides a method for testing the water separation index of jet fuel, the method comprising:

[0032] Samples were taken from the jet fuel containing carmine and water to be tested, and labeled as Sample 1 and Sample 2.

[0033] Sample 1 was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm, and the first test result X1 was obtained;

[0034] Sample 2 was subjected to water separation. After water separation, the sample was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm to obtain the second test result X2.

[0035] The water separation index W was calculated based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s=|X1-X2| / X1.

[0036] In this invention, Sample 1 and Sample 2 are two samples separated from a jet fuel sample containing carmine and water to be tested.

[0037] The jet fuel containing carmine and water is obtained by sequentially mixing and ultrasonically emulsifying carmine, water, and jet fuel.

[0038] For example, the mixing process includes: mixing an aqueous solution of carmine with jet fuel, or mixing carmine with water-containing jet fuel, or mixing carmine, water and jet fuel.

[0039] The power of the ultrasonic emulsification is 1000-2000W, for example, it can be 1000W, 1200W, 1400W, 1600W, 1800W or 2000W, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0040] The ultrasonic emulsification time is 3-5 minutes, for example, it can be 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes or 5 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0041] The concentration of carmine in the jet fuel containing carmine and water is 0.5-1 μg / L, for example, it can be 0.5 μg / L, 0.6 μg / L, 0.7 μg / L, 0.8 μg / L, 0.9 μg / L or 1 μg / L, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0042] The water volume percentage in the jet fuel containing carmine and water is 0.03-0.05%, for example, it can be 0.03%, 0.032%, 0.034%, 0.036%, 0.038%, 0.04%, 0.042%, 0.044%, 0.046%, 0.048%, or 0.05%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0043] The water separation is performed using a coalescing filter.

[0044] The water separation temperature is 18-29℃, for example, it can be 18℃, 19℃, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃ or 29℃, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0045] In this invention, after selecting the operating temperature during water separation, the temperature variation is controlled to not exceed ±3℃.

[0046] The flow rate during water separation is controlled at 25-30 mL / min, for example, it can be 25 mL / min, 25.5 mL / min, 26 mL / min, 26.5 mL / min, 27 mL / min, 27.5 mL / min, 28 mL / min, 28.5 mL / min, 29 mL / min, 29.5 mL / min or 30 mL / min, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0047] The filter materials used in the water separation process include those that meet the requirements of API / EI 1581, 5th edition. Examples include Velcon's 644C5TB, 656C5TB, 633C5TB, and 638C5TB filter materials, which are commonly used filter materials for water separation index testing.

[0048] The water separation time is 7-9 minutes, for example, it can be 7 minutes, 7.2 minutes, 7.4 minutes, 7.6 minutes, 7.8 minutes, 8 minutes, 8.2 minutes, 8.4 minutes, 8.6 minutes, 8.8 minutes or 9 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0049] Furthermore, to illustrate the excellent testing results achievable by the water separation index testing method provided by this invention, the following practical example is used for illustrative purposes:

[0050] Example 1

[0051] This embodiment provides a method for testing the water separation index of jet fuel, the method comprising:

[0052] Samples were taken from the jet fuel containing carmine and water to be tested, and labeled as Sample 1 and Sample 2.

[0053] Sample 1 was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm, and the first test result X1 was obtained;

[0054] Sample 2 was subjected to water separation. After water separation, the sample was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm to obtain the second test result X2.

[0055] The water separation index W was calculated based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s =|X1-X2| / X1;

[0056] The jet fuel containing carmine and water is obtained by sequentially mixing carmine, water, and jet fuel and then ultrasonically emulsifying them; wherein the ultrasonic emulsification power is 2000W and the ultrasonic emulsification time is 5min;

[0057] The concentration of carmine in the jet fuel containing carmine and water is 1 μg / L; the volume percentage of water in the jet fuel containing carmine and water is 0.05%.

[0058] The water separation was carried out using a coalescing filter at a temperature of 23°C and a flow rate of 25 mL / min. The filter material (Velcon 644C5TB filter material) conforming to API / EI 1581 5th edition was used for separation, and the separation time was 9 min.

[0059] Example 2

[0060] This embodiment provides a method for testing the water separation index of jet fuel, the method comprising:

[0061] Samples were taken from the jet fuel containing carmine and water to be tested, and labeled as Sample 1 and Sample 2.

[0062] Sample 1 was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm, and the first test result X1 was obtained;

[0063] Sample 2 was subjected to water separation. After water separation, the sample was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm to obtain the second test result X2.

[0064] The water separation index W was calculated based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s =|X1-X2| / X1;

[0065] The jet fuel containing carmine and water is obtained by sequentially mixing carmine, water, and jet fuel and then ultrasonically emulsifying them; wherein the ultrasonic emulsification power is 1000W and the ultrasonic emulsification time is 3 minutes.

[0066] The concentration of carmine in the jet fuel containing carmine and water is 1 μg / L; the volume percentage of water in the jet fuel containing carmine and water is 0.05%.

[0067] The water separation was carried out using a coalescing filter at a temperature of 23°C and a flow rate of 25 mL / min. The filter material (Velcon 656C5TB filter material) conforming to API / EI 1581 5th edition was used for separation, and the separation time was 9 min.

[0068] Example 3

[0069] This embodiment provides a method for testing the water separation index of jet fuel, the method comprising:

[0070] Samples were taken from the jet fuel containing carmine and water to be tested, and labeled as Sample 1 and Sample 2.

[0071] Sample 1 was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm, and the first test result X1 was obtained;

[0072] Sample 2 was subjected to water separation. After water separation, the sample was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm to obtain the second test result X2.

[0073] The water separation index W was calculated based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s =|X1-X2| / X1;

[0074] The jet fuel containing carmine and water is obtained by sequentially mixing carmine, water, and jet fuel and then ultrasonically emulsifying them; wherein the ultrasonic emulsification power is 2000W and the ultrasonic emulsification time is 5min;

[0075] The concentration of carmine in the jet fuel containing carmine and water is 1 μg / L; the volume percentage of water in the jet fuel containing carmine and water is 0.05%.

[0076] The water separation was carried out using a coalescing filter at a temperature of 29°C and a flow rate of 30 mL / min. The filter material (Velcon 633C5TB filter material) conforming to API / EI 1581 5th edition was used for separation, and the separation time was 7 min.

[0077] Example 4

[0078] This embodiment provides a method for testing the water separation index of jet fuel, the method comprising:

[0079] Samples were taken from the jet fuel containing carmine and water to be tested, and labeled as Sample 1 and Sample 2.

[0080] Sample 1 was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm, and the first test result X1 was obtained;

[0081] Sample 2 was subjected to water separation. After water separation, the sample was subjected to ultraviolet absorbance test under ultraviolet light at a wavelength of 216nm to obtain the second test result X2.

[0082] The water separation index W was calculated based on the first test result X1 and the second test result X2. s The calculation formula is as follows: W s =|X1-X2| / X1;

[0083] The jet fuel containing carmine and water is obtained by sequentially mixing carmine, water, and jet fuel and then ultrasonically emulsifying them; wherein the ultrasonic emulsification power is 2000W and the ultrasonic emulsification time is 5min;

[0084] The concentration of carmine in the jet fuel containing carmine and water is 0.5 μg / L; the volume percentage of water in the jet fuel containing carmine and water is 0.03%.

[0085] The water separation was carried out using a coalescing filter at a temperature of 23°C and a flow rate of 25 mL / min. The filter material (Velcon 638C5TB filter material) conforming to API / EI 1581 5th edition was used for separation, and the separation time was 9 min.

[0086] Comparative Example 1

[0087] The only difference from Example 1 is that carmine is not added to the jet fuel.

[0088] Comparative Example 2

[0089] The only difference from Example 1 is that the carmine in the jet fuel is replaced with an equal amount of amaranth.

[0090] Comparative Example 3

[0091] The only difference from Example 1 is that the carmine in the jet fuel is replaced with an equal amount of indigo.

[0092] Comparative Example 4

[0093] The only difference from Example 1 is that the ultraviolet detection wavelength is 350nm.

[0094] Example 5

[0095] The only difference from Example 1 is that the concentration of carmine in the jet fuel containing carmine and water is 0.2 μg / L.

[0096] Test Evaluation:

[0097] 1. Accuracy test

[0098] The accuracy of the detection methods provided in the examples and comparative examples was evaluated by comparing the measured values ​​and certified values ​​of standard samples A and B (and comparing the permissible difference and calculated deviation of the standard samples). The results are as follows.

[0099] 2. Precision test

[0100] The detection methods provided in the examples and comparative examples were evaluated by precision tests. Unknown sample 1 and unknown sample 2 were tested five times each, and the average value, standard deviation and relative standard deviation were calculated. The results are as follows.

[0101] As can be seen from the results of the examples and comparative examples, the solution provided by the present invention improves the detection sensitivity and accuracy by adding carmine. Carmine is an azo compound, and azo compounds contain a pyridine ring. This structure usually has electron-withdrawing functionality, and electron-withdrawing groups increase ultraviolet absorption intensity.

[0102] (1) In Comparative Example 1, the absence of carmine does not improve the detection sensitivity and accuracy;

[0103] (2) In Comparative Example 2, carmine in the jet fuel was replaced with an equal amount of amaranth. Amaranth is an isomer of carmine. The absorption peak of amaranth is close to that of carmine, with an absorption peak near 216 nm, but the peak intensity is lower than that of carmine. Amaranth is weaker than carmine in improving detection sensitivity and accuracy.

[0104] (3) In Comparative Example 3, carmine in the jet fuel was replaced with an equal amount of indigo. Indigo is a non-azo compound and does not have the effect of improving detection sensitivity and accuracy.

[0105] In summary, the solution provided by this invention selects the 216nm wavelength, corresponding to the strong absorption peak of carmine in the ultraviolet band, as the ultraviolet light. At this wavelength, the energy is high and the ultraviolet absorbance detection limit is low. In Comparative Example 4, the ultraviolet wavelength was changed from 216nm to 350nm. Since this wavelength is not the absorption peak of carmine, the detection accuracy decreased. According to the results of Example 5, reducing the concentration leads to a decrease in detection sensitivity.

[0106] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0107] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0108] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for testing the water separation index of a jet fuel, characterized in that, The water separation index test method comprises: sampling samples from a jet fuel containing carmine and water to be tested, denoted as sample 1 and sample 2; the concentration of carmine in the jet fuel containing carmine and water is 0.5-1 μg / L; carrying out ultraviolet absorbance test on sample 1 under ultraviolet light with a wave band of 216 nm to obtain a first test result X1; carrying out water separation on sample 2, and carrying out ultraviolet absorbance test on the sample after water separation under ultraviolet light with a wave band of 216 nm to obtain a second test result X2; The water separation index W is calculated from the first test result X1 and the second test result X2 s , according to the following formula: W s = |X1-X2| / X1.

2. The water separation index test method according to claim 1, characterized in that, the jet fuel containing carmine and water is obtained by sequentially mixing and ultrasonic emulsifying carmine, water and jet fuel.

3. The water separation index test method according to claim 2, characterized in that, The power of the ultrasonic emulsification is 1000-2000 W.

4. The water separation index test method according to claim 2, characterized in that, The time of the ultrasonic emulsification is 3-5 min.

5. The water separation index test method according to claim 1, wherein, The volume percentage of water in the jet fuel containing carmine and water is 0.03-0.05%.

6. The water separation index test method according to claim 1, wherein, The water separation is carried out by using a coalescence filter.

7. The water separation index test method according to claim 1, wherein, The temperature of the water separation is 18-29℃.

8. The water separation index test method according to claim 1, wherein, The control flow rate in the water separation is 25-30 mL / min.

9. The water separation index test method according to claim 1, wherein, The filter material used in the water separation comprises a filter material meeting the requirements of API / EI 1581 version 5.

10. The water separation index test method according to claim 1, wherein, The time of the water separation is 7-9 min.