A method for screening additives to improve the comprehensive performance of phosphate ester fire-resistant oils

Abstract

The present invention provides a screening method for improving the comprehensive performance of phosphate ester fire-resistant oil additives, which belongs to the technical field of phosphate ester fire-resistant oil, and specifically comprises preliminary screening and screening for the influence on the stability of phosphate ester fire-resistant oil. The preliminary screening can exclude in advance the types of additives that are not suitable for phosphate ester fire-resistant oil; the screening test for the influence on the stability of phosphate ester fire-resistant oil can avoid the problem that the types of additives that can improve the performance of phosphate ester fire-resistant oil but cause the accelerated deterioration of certain key indicators after the operation of phosphate ester fire-resistant oil are added to the phosphate ester fire-resistant oil, thereby shortening the service life of the phosphate ester fire-resistant oil; the problem that the addition of improper additives in the prior art seriously affects some indicators of phosphate ester fire-resistant oil or causes the phosphate fire-resistant oil to deteriorate faster during operation, shortens the service life of the phosphate fire-resistant oil, and affects the safe operation of steam turbine units in power plants is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphate fire-resistant oil, and in particular to a method for screening additives for improving the comprehensive performance of phosphate fire-resistant oil. Background Art

[0002] Phosphate ester fire-resistant oil is a fully synthetic phosphate ester flame-retardant hydraulic fluid. It is widely used in the speed control system of steam turbines and gas turbines due to its excellent fire retardant and lubricating properties. Phosphate ester fire-resistant oil deteriorates quickly. During use, the acid value of phosphate ester fire-resistant oil often increases, the resistivity decreases quickly, and sludge is generated after a short operating time. These can lead to reduced flexibility of turbine parts and corrosion and jamming of the servo valve of the speed control system. In severe cases, it can cause abnormal shutdown accidents of the unit. At the same time, phosphate ester fire-resistant oil is expensive, and frequent replacement of phosphate ester fire-resistant oil will increase the economic cost of the power industry.

[0003] During the use of phosphate fire-resistant oil, it is required to have good anti-deterioration performance, antioxidant performance, hydrolysis resistance, dielectric performance, air release performance, anti-foaming performance, etc. The most economical and effective way to increase the stability of phosphate fire-resistant oil is to add suitable additives to improve the performance of phosphate fire-resistant oil. However, due to the poor compatibility of phosphate fire-resistant oil and additives, after the additives are added, when improving one of the properties, it may cause other properties of phosphate fire-resistant oil to deteriorate. Therefore, no additives have been added to the phosphate fire-resistant oil products currently used.

[0004] In order to improve the stability of phosphate ester fire-resistant oil, adding suitable additives is the best choice. Phosphate ester fire-resistant oil manufacturers try to add additives to improve the performance of phosphate ester fire-resistant oil. However, due to the poor compatibility of phosphate ester fire-resistant oil itself with additives, if inappropriate additives are added, it will have a serious impact on some indicators of phosphate ester fire-resistant oil or cause the phosphate ester fire-resistant oil to deteriorate faster during operation, shorten the service life of phosphate ester fire-resistant oil, and at the same time bury huge safety hazards for the safe operation of the unit. Therefore, establishing a screening method for additives that improve the comprehensive performance of phosphate ester fire-resistant oil products is of great significance to ensuring the quality of phosphate ester fire-resistant oil and the safe operation of power equipment. Summary of the invention

[0005] In order to solve the problem in the prior art that improper addition of additives has a serious impact on some indicators of phosphate fire-resistant oil, causes the phosphate fire-resistant oil to deteriorate faster during operation, shortens the service life of phosphate fire-resistant oil, and affects the safe operation of steam turbine units in power plants, the present invention provides a screening method for improving the comprehensive performance of phosphate fire-resistant oil additives, the method comprising determining the type of additives and the dosage of additives, comparing samples containing each type and dosage with the original phosphate fire-resistant oil, evaluating the improvement of the direct effect after the addition of the additives, the impact on other physical and chemical indicators of the phosphate fire-resistant oil, and the impact on the stability of key indicators of the phosphate fire-resistant oil during subsequent operation, thereby optimizing the type and dosage of the additives, ensuring that the additives added to the phosphate fire-resistant oil can not only improve the performance of the phosphate fire-resistant oil in a certain aspect, but also will not affect other properties of the phosphate fire-resistant oil and the stability of key indicators of the phosphate fire-resistant oil during subsequent operation, thereby providing a guarantee for the safe operation of the generator set.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for screening additives for improving the comprehensive performance of phosphate ester fire-resistant oils, the specific steps are as follows:

[0007] S1, according to the chemical reactions related to the deterioration process of phosphate ester fire-resistant oil, select the type of additive that can alleviate the deterioration of phosphate ester fire-resistant oil itself;

[0008] S2, calculating the amount of each additive added according to the mass of the phosphate ester fire-resistant oil, and adding each additive to the phosphate ester fire-resistant oil respectively, and mixing under a sealed condition to obtain a first phosphate ester fire-resistant oil sample to be tested;

[0009] S3, detecting the performance index to be improved of the first phosphate fire-resistant oil sample to be detected, and performing preliminary screening of additives. If the improvement is less than a first preset value, the corresponding additive is eliminated; if the improvement is greater than the first preset value, the corresponding additive is retained;

[0010] S4, using the additives retained in S3 and the phosphate ester fire-resistant oil to prepare a second phosphate ester fire-resistant oil sample to be tested according to S2, adjusting the water content of the second phosphate ester fire-resistant oil sample to be tested to 200 mg / L±50 mg / L, and then conducting a closed cup aging test on the second phosphate ester fire-resistant oil sample to be tested. If the test result of the closed cup aging test is worse than that of the original phosphate ester fire-resistant oil, the corresponding additive is removed; if the test result of the closed cup aging test is within the parallel range or better than that of the original phosphate ester fire-resistant oil, the corresponding additive is retained, and the additive finally retained is used as an additive for improving the comprehensive performance of the phosphate ester fire-resistant oil.

[0011] Furthermore, it also includes S5, designing a series of dosages of the additives screened out by S4, preparing a third phosphate ester fire-resistant oil sample to be tested with different designed dosages of additives according to step S2, adjusting the water content of the third phosphate ester fire-resistant oil sample to be tested to 200 mg / L±50 mg / L, conducting a closed cup aging test on the third phosphate ester fire-resistant oil sample to be tested, and selecting a dosage with a performance index change trend less than the performance index change trend of the original phosphate ester fire-resistant oil as the optimal additive dosage.

[0012] Furthermore, it also includes S6. If multiple additives are screened out in S4, the multiple additives screened out in S4 are mixed according to the optimal additive amount screened out in S5, and a fourth phosphate ester fire-resistant oil sample to be tested is prepared according to S2, and a full analysis test is performed on the fourth phosphate ester fire-resistant oil sample to be tested. If the test result is within the parallelism range or better than that of the original phosphate ester fire-resistant oil, a closed cup aging test is performed, and the test indicators of the fourth phosphate ester fire-resistant oil sample to be tested are compared with those of the third phosphate ester fire-resistant oil sample to be tested. Multiple additives with the slowest indicator change trend are used as composite additives for phosphate fire-resistant oil.

[0013] Furthermore, in S1, the additive is selected from one or more of an antioxidant, an anti-hydrolysis agent, a metal passivator, a defoaming agent, and an auxiliary agent.

[0014] Further, in S2, a sample bottle equipped with a sealed bottle stopper is taken, a certain amount of phosphate ester fire-resistant oil is weighed and placed in the sample bottle, and the sample bottles are numbered 1 to n; the additives are numbered 1 to n, and the mass of each additive is calculated according to the mass of the phosphate ester fire-resistant oil in the sample bottle with the corresponding number, and each additive is added to the phosphate ester fire-resistant oil in the sample bottle with the corresponding number, and the bottle cap is sealed; the sample bottle of the blank oil sample is numbered 0;

[0015] Among them, the addition amount of phosphate fire-resistant oil is accurate to 0.1g, and the addition amount of additives is accurate to 0.1mg;

[0016] The sealed sample bottles numbered 0 to n are rotated at 5 to 10 r / min at a temperature of 60°C ± 5°C to uniformly disperse the additives in the phosphate fire-resistant oil.

[0017] Further, in S3, the performance index to be improved and the index detection order of the first phosphate fire-resistant oil sample to be detected are determined according to the types of additives, and the types of additives include antioxidants, anti-hydrolysis agents, metal passivators, defoaming agents and auxiliary agents, wherein:

[0018] When adding antioxidants, the performance indicators and order to be tested are: acid value, resistivity, air release value, oxidation stability, and hydrolysis stability;

[0019] When adding anti-hydrolysis agent, the performance indicators and order to be tested are: acid value, resistivity, air release value, foam characteristics, oxidation stability, and hydrolysis stability;

[0020] The performance indicators and order of testing for adding metal passivators are: resistivity, acid value, air release value, oxidation stability, hydrolysis stability, and foam characteristics;

[0021] The performance indicators and order to be tested when adding auxiliary agents are: resistivity, acid value, air release value, oxidation stability, hydrolysis stability, and foam characteristics;

[0022] When adding a single defoamer, the performance indicators and order to be tested are: foam characteristics, resistivity, and air release value;

[0023] The performance indicators of a certain additive are tested in sequence. If the negative impact of the previous performance indicator on the performance of the phosphate ester fire-resistant oil is greater than the second preset value during the testing process, the subsequent performance indicators do not need to be tested.

[0024] Furthermore, the closed cup aging test is carried out using the closed method and temperature conditions in DL / T 1705-2017 "Closed Cup Aging Test Method for Phosphate Ester Fire-Resistant Oils", and samples are taken regularly during the aging test to detect the acid value, resistivity and sludge precipitation data of the phosphate ester fire-resistant oils.

[0025] Furthermore, in the closed cup aging test, one copper wire with a purity of not less than 99.9%, a diameter of 1.00 mm to 1.02 mm, and a length of 165 mm is added to every 100 g of sample.

[0026] Furthermore, the copper wire is subjected to surface oxide layer removal using a mixed acid, wherein the mixed acid is a mixture of phosphoric acid and nitric acid in a mixing ratio of 1:3.

[0027] Furthermore, full analysis and testing is carried out according to the DL / T 571-2014 "Guidelines for Operation and Maintenance of Phosphate Fire-Resistant Oils" standard requirements.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The present invention provides a method for screening additives for improving the comprehensive performance of phosphate ester fire-resistant oils. According to chemical reactions related to the deterioration process of phosphate ester fire-resistant oils, types of additives that can theoretically alleviate the deterioration of phosphate ester fire-resistant oils are selected, and preliminary screening of additives is performed according to performance indicators to be improved in phosphate ester fire-resistant oils. Further, under the condition of adjusting the moisture content of phosphate ester fire-resistant oils, a closed cup aging test is used to screen the effects of the additives that have passed the preliminary screening on the stability of phosphate ester fire-resistant oils. This can avoid adding additives that can improve the performance of phosphate ester fire-resistant oils after direct addition, but can cause accelerated deterioration of certain key indicators of phosphate ester fire-resistant oils during operation after being added to the fire-resistant oils, thereby shortening the service life of phosphate ester fire-resistant oils. This solves the problem in the prior art that improper addition of additives has a serious impact on some indicators of phosphate ester fire-resistant oils or causes the phosphate fire-resistant oils to deteriorate faster during operation, shortening the service life of phosphate fire-resistant oils, and affecting the safe operation of steam turbine units in power plants.

[0030] Furthermore, the present invention also screens the dosage of preferred additives. After adjusting the moisture content of phosphate fire-resistant oil, the closed cup aging test is used to test the performance indicators of phosphate fire-resistant oil with different dosages of additives, so as to obtain the optimal dosage of additives suitable for adding to phosphate fire-resistant oil.

[0031] Furthermore, the present invention also carries out compound screening of multiple additives, clarifies the method for verifying the effects of the initial addition amount and stability of the compound additives, and through the effect verification test of the compound additives, a composite additive with coordinated and improved additive effects can be obtained, which can improve multiple properties of phosphate fire-resistant oils, or improve one property better than the effect of a single additive.

[0032] Furthermore, in the preliminary screening of the additives of the present invention, according to the set item detection order, the additive categories that are not suitable for phosphate fire-resistant oils can be excluded in advance with the minimum workload, thereby improving the screening efficiency.

[0033] In summary, the method of the present invention can screen out additives that can improve certain aspects of the performance of phosphate ester fire-resistant oil, while improving certain aspects of the performance of phosphate ester fire-resistant oil, without affecting other physical and chemical properties of phosphate ester fire-resistant oil, and can also ensure that the stability of key indicators of phosphate ester fire-resistant oil is not affected during the subsequent operation of phosphate ester fire-resistant oil. This evaluation method can ensure the safety of additives added to phosphate ester fire-resistant oil, and achieve the purpose of improving the performance of phosphate ester fire-resistant oil by adding appropriate types of additives and appropriate dosages. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Appearance of base oil before and after adding antioxidants;

[0035] Figure 2 Comparison of the appearance of the initially selected antioxidants before and after aging after adding them to the base oil;

[0036] Figure 3 Comparison of the appearance of the initially selected antioxidants after adding them to the base oil and aging for 5 days;

[0037] Figure 4 Comparison of the appearance of the initially selected antioxidants after adding them to the base oil and aging for 19 days;

[0038] Figure 5 Comparison of the appearance of the initially selected antioxidants after adding them to the base oil and aging for 39 days;

[0039] Figure 6 Comparison of the appearance of the initially selected antioxidants after adding them to the base oil after aging for 55 days;

[0040] Figure 7 The trend of acid value during closed cup aging test of base oil with different additives;

[0041] Figure 8 Resistivity trends during closed cup aging tests of base oils containing different additives. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, which are explanations of the present invention rather than limitations.

[0043] The present invention provides a method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oils, and the specific steps are as follows:

[0044] Step 1: Additive selection:

[0045] According to the chemical reactions related to the deterioration process of phosphate ester fire-resistant oil, the types of additives that can theoretically alleviate the deterioration of phosphate ester fire-resistant oil itself are selected. The additives can be antioxidants, anti-hydrolysis agents, metal passivators, defoaming agents, and auxiliary agents.

[0046] Step 2: Sample preparation steps:

[0047] Step 2.1. Take a glass bottle equipped with a sealed bottle stopper, weigh a certain amount of phosphate ester fire-resistant oil and put it in the glass bottle, and number the sample bottles 1 to n; number the additives 1 to n, calculate the mass of each additive according to the mass of the phosphate ester fire-resistant oil in the corresponding numbered sample bottle, weigh it with an analytical balance and add it to the corresponding numbered sample bottle, cover the bottle cap and seal it; the sample bottle of the blank oil sample is numbered 0.

[0048] Among them, the addition amount of phosphate fire-resistant oil is accurate to 0.1g, and the addition amount of additives is accurate to 0.1mg.

[0049] Step 2.2, place the sealed sample bottles numbered 0 to n on a mixing device respectively, the mixing device comprising a vertically arranged triangular bracket, the bottom of the triangular bracket being fixed in a constant temperature box, a motor being arranged on the top of the triangular bracket, the motor shaft being detachably connected to the sample bottle fixing plate, when the motor shaft is connected to the sample bottle fixing plate, the sample bottle fixing plate is driven by the motor to realize continuous rotation in the vertical direction, and a plurality of sample bottle fixing clamps are arranged along the circumference of the sample bottle fixing plate for fixing the bottle mouths of the plurality of sample bottles toward the center of the sample bottle fixing plate.

[0050] Preferably, the sample bottle fixing clamp comprises a bottle bottom fixing clamp, a bottle body fixing clamp and a bottle top fixing clamp, wherein the bottle top fixing clamp is a movable fixing clamp, which can prevent the sample bottle from falling off during rotation after being tightened.

[0051] The sample bottle fixing plate with the sample bottles is connected to the motor shaft. The temperature of the thermostat is a fixed temperature of 60℃±5℃. The motor controls the rotation of the sample bottle fixing plate. The sample bottles rotate at 5r / min~10r / min for 1h to evenly disperse the additives in the phosphate fire-resistant oil to obtain the first phosphate fire-resistant oil sample to be tested.

[0052] Step 3: Perform preliminary screening of additives to select additives with good compatibility with phosphate ester fire-resistant oils. The specific steps are as follows:

[0053] Detect the performance indicators to be improved of the phosphate fire-resistant oil in the sample bottles numbered 0 to n, and compare the performance indicators of the phosphate fire-resistant oil in the sample bottles numbered 1 to n with those in the sample bottle numbered 0. If the improvement is less than 10% of the first preset value, remove the additive; if the improvement is greater than 10% of the first preset value, proceed to step S2.4;

[0054] Specifically: When adding antioxidants, the performance indicators and order that need to be tested are: acid value, resistivity, air release value, oxidation stability, and hydrolysis stability;

[0055] When adding anti-hydrolysis agent, the performance indicators and order to be tested are: acid value, resistivity, air release value, foam characteristics, oxidation stability, and hydrolysis stability;

[0056] When adding metal passivators, the performance indicators and order to be tested are: resistivity, acid value, air release value, oxidation stability, hydrolysis stability, and foam characteristics;

[0057] The performance indicators and order to be tested when adding auxiliary agents are: resistivity, acid value, air release value, oxidation stability, hydrolysis stability, and foam characteristics;

[0058] When adding a single defoamer, the performance indicators and order to be tested are: foam characteristics, resistivity, and air release value;

[0059] The performance indicators of the phosphate ester fire-resistant oil after adding a certain additive are tested in sequence. If the negative impact of the previous performance indicator on the performance of the phosphate ester fire-resistant oil during the test is greater than the second preset value of 20%, it is proved that the additive is not suitable for addition to the phosphate ester fire-resistant oil, and the subsequent performance indicators do not need to be tested.

[0060] Preferably, during the preliminary screening, among the antioxidants, the added amount of phenolic antioxidants is 0.3%, the added amount of amine antioxidants is 0.1%, the added amount of ester antioxidants is 0.3%, the added amount of benzofuranone derivatives is 0.005%, the added amount of anti-hydrolysis agents is 1%, the added amount of metal passivators is 0.005%, the added amount of auxiliary agents is 0.1%, and the added amount of defoaming agents is 0.001%.

[0061] Among them, the detection methods of various performance indicators are based on the following standards:

[0062] Acid value: GB / T 264-1983 (1991) "Determination of acid value of petroleum products", resistivity: DL / T 421-2009 "Determination of volume resistivity of power oil", oxidation stability: DL / T 1654-2016 "Test method for oxidation stability and corrosion of phosphate ester fire-resistant oil", hydrolysis stability: DL / T 1420-2015 "Determination of hydrolysis stability of phosphate ester fire-resistant oil", air release value: SH / T 0308-1992 "Determination of air release value of lubricating oil", foam characteristics: GB / T 12579-2002 "Determination of foam characteristics of lubricating oil", sludge precipitation: DL / T 429.7-2017 "Determination method of sludge precipitation of power oil".

[0063] Step 4: Conduct a closed cup aging test:

[0064] Select the additives preliminarily screened in step 3 and prepare the second phosphate ester fire-resistant oil sample to be tested according to step 2, and adjust the moisture content of the second phosphate ester fire-resistant oil sample to be tested to 200mg / L±50mg / L. Except for the moisture content and aging time, the other conditions are consistent with the standard requirements of DL / T 1705-2017 "Closed Cup Aging Test Method for Phosphate Ester Fire-Resistant Oil". During the aging test, samples are taken regularly to test the acid value, resistivity and sludge precipitation of the phosphate ester fire-resistant oil; the test results of the above performance indicators are compared with the original phosphate ester fire-resistant oil. If the performance indicators deteriorate, terminate the test; if the test results are within the parallelism range or better than the original phosphate ester fire-resistant oil, proceed to the next step of dosage screening.

[0065] Furthermore, during the closed cup aging test, the temperature of the thermostat was controlled at 115°C ± 2°C.

[0066] Furthermore, a 200 mL ground-mouth conical flask was used during the aging process, and the second phosphate ester fire-resistant oil sample to be tested in the flask was 100 g.

[0067] Furthermore, one copper wire with a purity of not less than 99.9%, a diameter of 1.00 mm to 1.02 mm, and a length of 165 mm is added to 100 g of the second phosphate ester fire-resistant oil sample to be tested.

[0068] Furthermore, after the copper wire was treated with mixed acid to remove the surface oxide layer, the acid attached to the surface was washed away with running tap water and distilled water in turn, and then placed in beakers containing ethanol and acetone for 10 seconds in turn, and placed at room temperature for 5 minutes to dry the solvent.

[0069] Furthermore, the mixed acid for cleaning the copper wire is a mixture of phosphoric acid and nitric acid, and the mixing ratio is 1:3.

[0070] Furthermore, the moisture content of the second phosphate ester fire-resistant oil sample to be tested in parallel during the aging process was consistent, ranging from 250 mg / L ± 20 mg / L.

[0071] Furthermore, the second phosphate fire-resistant oil samples to be tested for longitudinal and transverse comparison are prepared at the same time. The longitudinal comparison is that the same second phosphate fire-resistant oil sample to be tested is sampled at different aging times; the transverse comparison is that multiple second phosphate fire-resistant oil samples to be tested are sampled at the same aging time.

[0072] Furthermore, when a single second phosphate ester fire-resistant oil sample to be tested (different aging times of the same second phosphate ester fire-resistant oil sample to be tested) is compared longitudinally, the number of points is 7 to 10.

[0073] Step 5: Screening the dosage of a single additive:

[0074] In step 4, a series of dosages of the preferred additives are screened out, and step 2 is used to prepare the third phosphate fire-resistant oil sample to be tested with different designed dosages of the additives.

[0075] Step 4 is used to carry out a closed cup aging test to screen out the dosage of additives that improves the performance of the phosphate ester fire-resistant oil sample. Specifically: the stability of the third phosphate ester fire-resistant oil sample to be tested is analyzed, and the change trends of the test results of the acid value, resistivity, and sludge precipitation of each third phosphate ester fire-resistant oil sample to be tested are compared with the blank oil sample without additives. The smaller the change trend, the better the stability of the phosphate fire-resistant oil. If any of the above performance indicators has a faster change trend than the original phosphate fire-resistant oil, it means that the dosage of the additive is not suitable for addition to the phosphate fire-resistant oil, and the test is terminated; finally, the type and dosage of additives that do not affect or can slow down the change trend of the above performance indicators of the phosphate fire-resistant oil are optimized.

[0076] Step 6: Screening of the dosage of compound additives:

[0077] The multiple single additives selected in step 5 are compounded and added to the same blank oil sample respectively, with the same preparation method as step 2, to obtain a fourth phosphate ester fire-resistant oil sample to be tested, and the fourth phosphate ester fire-resistant oil sample to be tested is subjected to full analysis and testing in accordance with the standard requirements of DL / T571-2014 "Guidelines for Operation and Maintenance of Phosphate Ester Fire-Resistant Oils". If the performance index deteriorates compared with the original phosphate ester fire-resistant oil, the test is terminated; a closed cup aging test is performed if the test result is within the parallelism range or better than the blank oil sample, and the change trends of the sample acid value, resistivity, and sludge of the composite additive are compared with the closed cup aging test results of the third phosphate ester fire-resistant oil sample to be tested containing a single additive, and the multiple additives with the slowest change trend of the above performance indicators are used as the most suitable composite additives for the phosphate ester fire-resistant oil.

[0078] Example:

[0079] The present invention provides a method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oils, and the specific steps are as follows:

[0080] Step 1: The deterioration of phosphate fire-resistant oil is mainly caused by oxidation and hydrolysis. In addition, the deterioration or contamination of phosphate fire-resistant oil during operation will lead to increased foam. Metals have a catalytic effect on the deterioration of phosphate fire-resistant oil. Adding additives needs to promote the dispersion effect of each additive in the fire-resistant oil. Therefore, the selected additives include antioxidants, anti-hydrolysis agents, metal passivators and auxiliary agents, and defoaming agents, as shown in Table 1 below:

[0081] Table 1 Different categories of additives screened out

[0082]

[0083] Step 2: Preliminarily select the type of additives suitable for the base oil through a single additive effect verification test, and preliminarily screen each additive based on the test results, where the base oil is a new phosphate ester fire-resistant oil. Specifically:

[0084] The method of adding each additive is as follows: the dosage of the additive is determined according to the properties of the additive itself and the experience of use. Each additive is weighed accurately to 0.1 mg, and then added to the base oil. In a sealed state, the sample is rotated for 1 hour in a constant temperature box at 60℃±5℃ to ensure that the additive is dissolved in the base oil and mixed evenly with it to obtain the base oil containing additives.

[0085] Step 2.1, test the change data of the acid value, resistivity, oxidation stability, hydrolysis stability and air release value of the base oil before and after adding a single antioxidant, and conduct preliminary screening of antioxidants. The test results are shown in Tables 2 to 3:

[0086] Table 2 Oxidation stability, acid value and resistivity test results of base oil before and after adding a single antioxidant

[0087]

[0088] Table 3 Test results of hydrolysis stability and air release value of base oil before and after adding single antioxidant

[0089]

[0090] like Figure 1 The following table shows the appearance of each base oil after adding the above antioxidants. The results in Tables 2 and 3 show that compared with the base oil, the oxidation stability of the base oil deteriorates and the acid value increases after adding 4,4'-methylenebis(2,6-di-tert-butylphenol); the resistivity of the base oil decreases after adding alkylated phenyl-α-naphthylamine; the color of the base oil becomes darker after adding N,N'-xylyl-p-phenylenediamine; the air release value of the base oil increases after adding dipentaerythritol octyl decanoate. Therefore, the above additives are not suitable as base oil additives.

[0091] 2.2. The acid value, resistivity, air release value, foam characteristics, oxidation stability and hydrolysis stability of the base oil before and after adding a single anti-hydrolysis agent were tested to conduct a preliminary screening of the anti-hydrolysis agent. The test results are shown in Tables 4 to 5:

[0092] Table 4 Oxidation stability, acid value and resistivity test results of base oil before and after adding a single anti-hydrolysis agent

[0093]

[0094] Table 5 Test results of hydrolysis stability, air release value and foam characteristics of base oil before and after adding a single anti-hydrolysis agent

[0095]

[0096] The results of Tables 4 and 5 show that, compared with the base oil, after adding polymeric carbodiimide and 2-methyl-2-oxazoline, the resistivity of the base oil decreases, and it is not suitable as a base oil additive; after adding monomeric carbodiimide, the foaming properties of the base oil deteriorate, and the monomeric carbodiimide additive fails to improve the hydrolysis resistance of the base oil, and is not suitable as a base oil additive.

[0097] 2.3. Detect the change data of resistivity of base oil before and after adding single metal passivator and auxiliary agent, and conduct preliminary screening of passivator. The test results are shown in Table 6:

[0098] Table 6 Resistivity test results of base oil before and after adding single metal passivator and auxiliary agent

[0099]

[0100] The results in Table 6 show that compared with the base oil, the volume resistivity of the base oil is significantly reduced after adding thiophosphate butyl octyl zinc salt, T551 and T101, so thiophosphate butyl octyl zinc salt, T551 and T101 cannot be used as additives for the base oil.

[0101] 2.4. Detect the change data of the foam characteristics of the phosphate ester fire-resistant oil in the power plant before and after adding a single defoamer, and conduct a preliminary screening of the defoamers. The test results are shown in Table 7:

[0102] Table 7 Test results of phosphate fire-resistant oil in power plant before and after adding single dose of defoamer

[0103]

[0104] Note: The base oil is a new phosphate fire-resistant oil. The main components of the phosphate fire-resistant oil in power plant operation and the base oil are both trixyl phosphate ester. Since the foaming characteristics of the base oil are relatively small, it cannot reflect the effect of the defoamer. The effect of the defoamer needs to be verified with the phosphate fire-resistant oil in power plant operation with large foam. Therefore, the samples tested for foaming characteristics in Table 7 are the phosphate fire-resistant oil in power plant operation with seriously exceeded foaming characteristics, and the samples tested for resistivity and air release values ​​are the base oil.

[0105] The results in Table 7 show that compared with the phosphate fire-resistant oil with large foam in power plants, the foam characteristics of the phosphate fire-resistant oil in power plants are not significantly improved after adding tributyl phosphate and polyether, and these two defoamers are not suitable as defoamers for base oils; after adding silicones, the foam characteristics of the phosphate fire-resistant oil in power plants are significantly improved, and there is no adverse effect on the resistivity and air release value of the base oil; after adding polyether modified type 1, polyether modified type 2 and silicone oil, the air release value of the base oil is significantly deteriorated, so silicones can be used as anti-foaming additives for base oils.

[0106] In summary, through the single additive effect verification test, the additives that can be used for base oil are preliminarily screened out, including 2,6-di-tert-butyl-p-cresol, 2,4-dicumylphenol, tert-butylhydroquinone, dodecylphenol, benzofuranone derivatives (lactone) and silicones. The above additives are subjected to closed cup aging tests to determine the effects of the above additives on the stability of the base oil after addition.

[0107] Step 3: Effect of additives on the stability of key items of phosphate fire-resistant oils:

[0108] 3.1. The influence of antioxidants on the stability of key items of phosphate fire-resistant oils:

[0109] In order to study the effect of a single additive on the stability of key items of phosphate fire-resistant oils, base oil and base oil containing additives were selected. After adjusting their moisture content to the same level, closed cup aging tests were carried out. During the aging test, key items were sampled and tested regularly to analyze the changing trends and determine the impact of the additives.

[0110] Since the moisture content of phosphate ester fire-resistant oil is mostly stable at around 200mg / L during actual operation, the moisture content in the closed cup aging test conditions here is designed to be 200mg / L±50mg / L. The remaining conditions are consistent with the requirements of DL / T 1705-2017 "Closed Cup Aging Test Method for Phosphate Ester Fire-Resistant Oil". During the aging test, the key items of phosphate ester fire-resistant oil are regularly sampled and tested, including acid value, resistivity, and sludge precipitation (qualitative).

[0111] The specifications of the copper wire catalyst used in the test are: T1 copper, purity not less than 99.95%, diameter 1.03mm, length 330mm, twisted into a spiral with an outer diameter of 19mm and a length of 38mm.

[0112] like Figure 2 to Figure 6 As shown in the figure, after adding 5 kinds of antioxidants, during the closed cup aging test, the base oil containing additives is lighter in color than the base oil at the end of aging, and the color of the sample after adding dodecylphenol is the lightest; the test results of acid value, resistivity, and sludge precipitation are shown in Tables 8 to 10:

[0113] Table 8 Acid value test results of base oils containing different additives during the 115℃ closed cup aging test

[0114]

[0115] Table 8 shows the acid value changes of base oils with different additives during aging. Figure 7 , Figure 7 It shows that during the aging process, the acid value of the base oil changes slowly. The base oil that is closest to the base oil is the base oil after adding 2,6-di-tert-butyl-p-cresol and benzofuranone derivatives (lactone). The base oil containing other additives has a significantly higher acid value than the base oil in the later stage of aging.

[0116] Table 9 Resistivity test results of base oils containing different additives during the 115℃ closed cup aging test

[0117]

[0118] According to Table 9, the relationship between resistivity and aging time during the aging process is shown in Figure 8 , among which the resistivity of the base oil after adding 2,6-di-tert-butyl-p-cresol and benzofuranone derivatives (lactone) is higher than the resistivity of the base oil.

[0119] Table 10 Results of sludge precipitation test of base oils containing different additives during the 115℃ closed cup aging test

[0120]

[0121] Table 10 shows that, during the aging process, the best improvement in base oil sludge precipitation after adding the selected antioxidants is 2,6-di-tert-butyl-p-cresol and benzofuranone derivatives (lactone) additives.

[0122] Comprehensive analysis shows that adding 2,6-di-tert-butyl-p-cresol and benzofuranone derivatives (lactone) to antioxidant additives can significantly improve the sludge precipitation tendency of the base oil and keep other properties of the base oil stable, so further additive dosage confirmation tests can be carried out.

[0123] 3.2. The influence of defoaming agent on the stability of key items of base oil:

[0124] The test process is the same as 3.1, and the results are shown in Tables 11 to 13:

[0125] Table 11 Acid value test results of base oil containing silicone additives during 115℃ closed cup aging test

[0126]

[0127] Table 12 Resistivity test results of base oil containing silicone additives during 115℃ closed cup aging test

[0128]

[0129] Table 13 Results of sludge precipitation test of base oil containing silicone additives during 115℃ closed cup aging test

[0130]

[0131] Tables 11 to 13 show the changes in acid value, resistivity and sludge precipitation of the base oil after adding 30 ppm of silicone defoamer during aging. The results show that adding 30 ppm of silicone defoamer has no effect on the stability of the base oil.

[0132] Step 4: Study on the effect of different additive dosages on base oil stability:

[0133] 4.1. Study on the effect of different contents of 2,6-di-tert-butyl-p-cresol antioxidant on base oil stability:

[0134] In order to study the effect of different doses of 2,6-di-tert-butyl-p-cresol on the stability of key items of base oil, base oil, base oil containing different doses of 2,6-di-tert-butyl-p-cresol additives, and base oil containing different doses of benzofuranone derivatives (lactone) additives were selected, and the water content of the base oil, base oil containing different doses of 2,6-di-tert-butyl-p-cresol additives, and base oil containing different doses of benzofuranone derivatives (lactone) additives was adjusted to 200mg / L±50mg / L, and closed cup aging test was carried out. During the aging test, key items were sampled regularly to analyze the change trend and judge the influence of additives. The key items include acid value, resistivity, and sludge precipitation (qualitative).

[0135] Here, the closed cup aging test method is as in step 3, and the test results are shown in Tables 14 to 16:

[0136] Table 14 Acid value test results of base oil with 2,6-di-tert-butyl-p-cresol antioxidant added during 115℃ closed cup aging test

[0137]

[0138] Table 15 Resistivity test results of base oil with 2,6-di-tert-butyl-p-cresol antioxidant added during closed cup aging test at 115℃

[0139]

[0140] Table 16 Results of sludge precipitation test of base oil with 2,6-di-tert-butyl-p-cresol antioxidant added during closed cup aging test at 115℃

[0141]

[0142] The results of Tables 14 to 16 show that when the addition amount of 2,6-di-tert-butyl-p-cresol additive is 0.03% to 0.08%, the stability of each key performance index during the aging process of the base oil is significantly improved, which is the optimal addition amount of the additive.

[0143] 4.2. Study on the effect of different contents of benzofuranone derivatives (lactone) antioxidants on base oil stability:

[0144] The test process is the same as 4.1. The test results are shown in Tables 17 to 19.

[0145] Table 17 Acid value test results of base oils with added benzofuranone derivatives (lactone) antioxidants during the 115℃ closed cup aging test

[0146]

[0147] Table 18 Resistivity test results of base oils with added benzofuranone derivatives (lactone) antioxidants during the 115℃ closed cup aging test

[0148]

[0149] Table 19 Results of sludge precipitation test of base oils with added benzofuranone derivative (lactone) antioxidants during the 115℃ closed cup aging test

[0150]

[0151] The results of Tables 17 to 19 show that the addition amount of benzofuranone derivative (lactone) additives in the range of 50ppm~100ppm has a significant effect on improving the stability of various key performance indicators during the aging process of the base oil, which is the optimal addition amount of the additive.

[0152] 4.3. Study on the influence of different defoamer contents on base oil stability:

[0153] 30ppm of silicone defoaming agent has been proved to have no effect on the stability of base oil in stability test 3.2. The dosage of defoaming agent should follow the principle of small dosage. The preliminary screening test table 7 shows that the addition of 10ppm of silicone can make the base oil with seriously exceeded foaming properties reach the qualified level, indicating that the addition dosage of 10ppm and 30ppm does not affect the stability of base oil, which can prove that the addition of 10ppm will not affect the stability of base oil.

[0154] Step 5: Effect test after adding composite additives:

[0155] The above research shows that the additives suitable for base oil are antioxidant 2,6-di-tert-butyl-p-cresol and benzofuranone derivatives (lactone) and silicone defoamers, and the suitable additive dosage ranges are 0.03% to 0.08%, 50ppm to 100ppm and 10ppm respectively. In order to further improve the stability of the base oil, the above two antioxidants and defoamers are added at a dosage of 0.05 % , 50ppm and 10ppm were compounded with the base oil, and the compounded oil samples were subjected to full analysis and closed cup aging test. During the aging test, the key performance indicators of phosphate fire-resistant oil were tested, and the key items included acid value, resistivity and sludge precipitation (qualitative).

[0156] The oil sample compounding process is the same as step 2.

[0157] The closed cup aging test method is as in step 3, and the test results are shown in Tables 20 to 22.

[0158] The full analysis test results are shown in Table 23.

[0159] Table 20 Acid value test results of base oil after adding composite additives during closed cup aging test at 115℃

[0160]

[0161] Table 21 Resistivity test results of base oil after adding composite additives during 115℃ closed cup aging test

[0162]

[0163] Table 22 Results of sludge precipitation test of base oil after adding composite additives during closed cup aging test at 115℃

[0164]

[0165] From Tables 20 to 22, it can be seen that after the 2,6-di-tert-butyl-p-cresol antioxidant, benzofuranone derivative (lactone) antioxidant and silicone defoamer were compounded with the base oil at dosages of 0.05%, 50ppm (wt) and 10ppm (wt), respectively, the stability of the base oil was further improved. The fire-resistant oil sample obtained after compounding the base oil and additives was analyzed and tested in accordance with the requirements of DL / T 571-2014 "Guidelines for Operation and Maintenance of Phosphate Fire-resistant Oils", and the test results are shown in Table 23:

[0166] Table 23 Full analysis results of domestic fire-resistant oil samples

[0167]

[0168] It can be seen from Table 23 that after the base oil is compounded with 2,6-di-tert-butyl-p-cresol, benzofuranone derivatives (lactone) and silicone defoamers, the air release value, foam characteristics, flash point and auto-ignition point of the oil sample are not affected, and the test results fully meet the requirements for new oil in the DL / T 571-2014 "Guidelines for Operation and Maintenance of Phosphate Ester Fire-Resistant Oils" standard.

[0169] In summary, through the study of additive types and dosages, the antioxidant 2,6-di-tert-butyl-p-cresol, benzofuranone derivatives and silicone defoaming agents have obvious effects on improving the stability of various key performance indicators of base oil during the aging process, and can be compounded with the base oil. The additive dosage ranges are 0.03%~0.08%, 50ppm~100ppm and 10ppm, respectively. The performance indicators of phosphate fire-resistant oil obtained after compounding fully meet the requirements of new oil in the standard DL / T 571-2014 "Guidelines for Operation and Maintenance of Phosphate Fire-Resistant Oils".

Claims

1. A method for screening additives for improving the comprehensive performance of phosphate ester fire-resistant oils, characterized in that: The specific steps are as follows: S1, according to the chemical reactions related to the deterioration process of phosphate ester fire-resistant oil, select the type of additive that can alleviate the deterioration of phosphate ester fire-resistant oil itself; S2, calculating the amount of each additive added according to the mass of the phosphate ester fire-resistant oil, and adding each additive to the phosphate ester fire-resistant oil respectively, and mixing under a sealed condition to obtain a first phosphate ester fire-resistant oil sample to be tested; S3, detecting the performance index to be improved of the first phosphate fire-resistant oil sample to be detected, and performing preliminary screening of additives. If the improvement is less than a first preset value, the corresponding additive is eliminated; if the improvement is greater than the first preset value, the corresponding additive is retained; S4, using the additive retained in S3 and the phosphate ester fire-resistant oil to prepare a second phosphate ester fire-resistant oil sample to be tested according to S2, adjusting the water content of the second phosphate ester fire-resistant oil sample to be tested to 200 mg / L±50 mg / L, and then conducting a closed cup aging test on the second phosphate ester fire-resistant oil sample to be tested. If the test result of the closed cup aging test is worse than that of the original phosphate ester fire-resistant oil, the corresponding additive is removed; if the test result of the closed cup aging test is within the parallel range or better than that of the original phosphate ester fire-resistant oil, the corresponding additive is retained, and the additive finally retained is used as an additive for improving the comprehensive performance of the phosphate ester fire-resistant oil; S5, designing a series of dosages of the additives screened out in S4, preparing a third phosphate ester fire-resistant oil sample to be tested containing different designed dosages of the additives according to step S2, adjusting the water content of the third phosphate ester fire-resistant oil sample to be tested to 200 mg / L±50 mg / L, performing a closed cup aging test on the third phosphate ester fire-resistant oil sample to be tested, and selecting a dosage with a performance index change trend less than the performance index change trend of the original phosphate ester fire-resistant oil as the optimal additive dosage; In S3, the performance index to be improved and the index detection order of the first phosphate fire-resistant oil sample to be detected are determined according to the types of additives, and the types of additives include antioxidants, anti-hydrolysis agents, metal passivators and defoaming agents, wherein: When adding antioxidants, the performance indicators and order to be tested are: acid value, resistivity, air release value, oxidation stability, and hydrolysis stability; When adding anti-hydrolysis agent, the performance indicators and order to be tested are: acid value, resistivity, air release value, foam characteristics, oxidation stability, and hydrolysis stability; The performance indicators and order of testing for adding metal passivators are: resistivity, acid value, air release value, oxidation stability, hydrolysis stability, and foam characteristics; When adding a single defoamer, the performance indicators and order to be tested are: foam characteristics, resistivity, and air release value. The power plant phosphate ester fire-resistant oil is used to test the foam characteristics, and the base oil is used to test the resistivity and air release value. Testing the performance indicators of the phosphate ester fire-resistant oil after adding a certain additive in sequence, if the negative impact of the previous performance indicator on the performance of the phosphate ester fire-resistant oil during the testing process is greater than the second preset value, then the subsequent performance indicators do not need to be tested; In S4, the closed cup aging test is carried out using the closed method and temperature conditions in DL / T 1705-2017 "Closed Cup Aging Test Method for Phosphate Ester Fire-Resistant Oils", and samples are taken regularly during the aging test to detect the acid value, resistivity and sludge precipitation data of the phosphate ester fire-resistant oils.

2. The method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oil according to claim 1, characterized in that: It also includes S6. If multiple additives are screened out in S4, the multiple additives screened out in S4 are mixed according to the optimal additive amount screened out in S5, and a fourth phosphate ester fire-resistant oil sample to be tested is prepared according to S2, and a full analysis test is performed on the fourth phosphate ester fire-resistant oil sample to be tested. If the test result is within the parallelism range or better than that of the original phosphate ester fire-resistant oil, a closed cup aging test is performed, and the test indicators of the fourth phosphate ester fire-resistant oil sample to be tested are compared with those of the third phosphate ester fire-resistant oil sample to be tested. Multiple additives with the slowest indicator change trend are used as composite additives for phosphate fire-resistant oil.

3. The method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oil according to claim 1, characterized in that: In S2, a sample bottle equipped with a sealed bottle stopper is taken, a certain amount of phosphate ester fire-resistant oil is weighed and placed in the sample bottle, and the sample bottles are numbered 1 to n; the additives are numbered 1 to n, and the mass of each additive is calculated according to the mass of the phosphate ester fire-resistant oil in the sample bottle with the corresponding number, and each additive is added to the phosphate ester fire-resistant oil in the sample bottle with the corresponding number, and the bottle cap is sealed; the sample bottle of the blank oil sample is numbered 0; Among them, the addition amount of phosphate fire-resistant oil is accurate to 0.1g, and the addition amount of additives is accurate to 0.1mg; The sealed sample bottles numbered 0 to n are rotated at 5 to 10 r / min at a temperature of 60°C ± 5°C to uniformly disperse the additives in the phosphate fire-resistant oil.

4. The method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oil according to claim 1, characterized in that: In the closed cup aging test, a copper wire with a purity of not less than 99.9%, a diameter of 1.00 mm to 1.02 mm, and a length of 165 mm is added to every 100 g of sample.

5. A method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oil according to claim 4, characterized in that: The copper wire is treated with a mixed acid to remove the surface oxide layer, wherein the mixed acid is a mixture of phosphoric acid and nitric acid in a mixing ratio of 1:

3.

6. The method for screening an additive for improving the comprehensive performance of phosphate ester fire-resistant oil according to claim 2, characterized in that: The full analysis and testing is carried out according to the DL / T 571-2014 "Guidelines for Operation and Maintenance of Phosphate Ester Fire-Resistant Oils" standard requirements.

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