Oil regeneration device, method for producing regenerated oil, additive, and adsorbent set

Abstract

Provided is an oil regeneration device comprising: an addition unit that adds an additive to an oil containing copper and an organic acid; and an adsorbent contact unit that brings the oil containing the additive into contact with an adsorbent, wherein the additive has, in a molecule, a polar group and a functional group having an acid dissociation constant pKa of 5 or more, the functional group of the additive is bonded to copper contained in the oil, and the adsorbent adsorbs the additive bonded to copper and the organic acid contained in the oil. Due to said feature, the organic acid and copper contained in a degraded oil can be efficiently removed by simple constituent elements.

Description

Oil regeneration equipment, regenerated oil production method, additives and adsorbent set

[0001] The present disclosure relates to an oil reclamation device, a method for producing reclaimed oil, and a set of additives and adsorbents.

[0002] Oils such as insulating oil and lubricating oil are subject to oxidation and deterioration during use, resulting in a decrease in their insulating performance, lubricating performance, and the like.

[0003] To ensure the reliability of equipment, oil is changed periodically. The used oil is sometimes used as fuel or, after filtering, reused as industrial lubricant.

[0004] As a method other than such oil replacement, there is a method of regenerating the oil by connecting a regeneration device to the oil tank and removing deteriorated components contained in the oil.

[0005] Patent Document 1 discloses a method for regenerating turbine oil, which includes a contacting step of contacting used turbine oil with an adsorbent and an adding step of adding an additive to the used turbine oil after the contacting step. Examples of the adsorbent include silica gel, zeolite, activated alumina, activated clay, and kaolin, and examples of the additive include antioxidants, rust inhibitors, antifoaming agents, antifriction agents, extreme pressure agents, metal deactivators, and demulsifiers.

[0006] Patent Document 2 discloses a configuration in which an oil-filled electrical device is provided with an oil circulation flow path, a storage container is provided in the oil circulation flow path for storing a substance that reacts with copper ions in the oil to produce an oil-insoluble solid product, and a means for collecting the solid product produced by the reaction is provided on the oil discharge side of the storage container. Patent Document 2 discloses substances that react with copper ions, such as benzotriazole, α-benzoin oxime, salicylaldoxime, cupperone, oxine, quinaldic acid, and α-nitroso-β-naphthol. Patent Document 2 also discloses that the storage container stores a material in which benzotriazole is adsorbed onto a cellulose-based material.

[0007] JP 2024-8326 A JP 61-168218 A

[0008] During the oil degradation process, the base oil undergoes oxidative degradation, producing organic acids. As the amount of organic acids increases, copper dissolution into the oil is promoted. Copper dissolution is particularly likely to occur when the base oil itself is polar, such as synthetic ester oil or natural ester oil.

[0009] In Patent Document 1, a commonly used adsorbent is used.

[0010] In Patent Document 2, a material is used in which benzotriazole or the like, a substance that reacts with copper ions, is adsorbed onto a cellulosic material. In the case of Patent Document 2, a solid product that reacts with copper ions and is insoluble in oil flows downstream, so an oil filtration tank is provided to collect this solid product. In such a configuration, since the benzotriazole or the like is consumed in the material in which benzotriazole or the like is adsorbed onto a cellulosic material, it is considered that the cellulosic material needs to be replaced.

[0011] An object of the present disclosure is to efficiently remove organic acids and copper contained in deteriorated oil using simple components.

[0012] The oil regeneration device of the present disclosure comprises an addition section that adds an additive to oil containing copper and an organic acid, and an adsorbent contact section that brings the oil containing the additive into contact with an adsorbent, the additive having a functional group with an acid dissociation constant pKa of 5 or more and a polar group in its molecule, the functional group of the additive binding to the copper contained in the oil, and the adsorbent adsorbing the additive bound to the copper and the organic acid contained in the oil.

[0013] According to the present disclosure, organic acids and copper contained in deteriorated oil can be efficiently removed using simple components.

[0014] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0015] 1 is a schematic diagram showing an example of an insulating oil regeneration device according to an embodiment. FIG. 2 is a flow chart showing an example of a method for producing regenerated oil according to an embodiment.

[0016] Hereinafter, embodiments of the present disclosure will be described using text and drawings. However, the structures, materials, and other specific values ​​shown in the present disclosure are not limited to the embodiments discussed here, and can be appropriately combined or improved within the scope that does not change the gist of the present disclosure. Furthermore, elements not directly related to the present disclosure are omitted from the illustrations.

[0017] First, in the following embodiment, insulating oil used in transformers will be described as one of the oils that can be regenerated using the oil regeneration device according to the present disclosure. The following description does not limit the type of oil that can be regenerated using the present disclosure, but merely provides an example to illustrate a specific configuration. Oils other than insulating oil include lubricating oils for steam turbines, gas turbines, motors, etc. Furthermore, copper dissolved in oil is considered to be in the form of copper ions, but will be referred to simply as "copper" in the following description. The base oil of the oil may be polyol ester or vegetable oil.

[0018] FIG. 1 is a schematic diagram showing an example of an insulating oil regeneration device according to an embodiment.

[0019] In this figure, the insulating oil regeneration device 100 comprises an insulating oil tank 1 installed in a transformer or the like, a column 3 (adsorbent contact section) filled with adsorbent 2, a line 4 (piping) connecting the insulating oil tank 1 and the column 3, a pump 5 installed in the line 4, an addition section 6 for adding an additive to the insulating oil flowing in the line 4, and a line 7 (piping) connecting the column 3 and the insulating oil tank 1.

[0020] A line 7 may connect the column 3 with a conservator attached to the transformer.

[0021] A stirring tank 8 and a stirring operation unit 9 for mixing the insulating oil and the additive may be provided downstream of the adding unit 6 provided in the line 4. The stirring tank 8 and the stirring operation unit 9 may be substituted with a guide vane, a baffle plate, or the like. The stirring tank 8 and the stirring operation unit 9 may be collectively referred to as the "stirring unit."

[0022] The line 4 may be provided with a heater (not shown) for heating the oil to a predetermined temperature.

[0023] Furthermore, a sensor 10 for detecting the deterioration state of the insulating oil may be provided upstream of the adding unit 6 on the line 4, and a sensor 11 for detecting the regeneration state of the insulating oil may be provided on the line 7. The sensors 10 and 11 may be, for example, an infrared spectroscopic sensor for detecting polar groups contained in the insulating oil or a fluorescent X-ray sensor for detecting copper. These sensors can detect the deterioration state and regeneration state of the insulating oil. The values ​​detected by the sensors 10 and 11 serve as indicators of the deterioration state and regeneration state of the insulating oil. The amount of additive added by the adding unit 6 may be adjusted based on the amount of copper detected by the sensor 10. The line 7 may be provided with a mechanism for adding an antioxidant to the insulating oil (antioxidant adding unit). The sensor 11 may also be a sensor for measuring the amount of organic acid.

[0024] In summary, an organic acid sensor that measures the content of organic acids may be installed downstream of the adsorbent contact section. Furthermore, a copper sensor that measures the content of copper in the insulating oil may be installed upstream of the adding section. Furthermore, a control unit that controls the amount of additive added based on data from the copper sensor may be installed.

[0025] In this diagram, when pump 5 is started, oil in insulating oil tank 1 flows out into line 4, a predetermined amount of additive is injected from addition section 6, and the oil flows into stirring tank 8 where it is stirred. The oil is then purified in column 3 and returned to insulating oil tank 1 through line 7.

[0026] In this figure, a column 3 filled with adsorbent 2 is installed, but the adsorbent 2 may be built into the column 3 in a flowable state. This configuration can reduce the flow resistance of the oil. Furthermore, this configuration can reduce the thickness of the boundary layer near the surface of the adsorbent 2 due to the flow of the adsorbent 2, making it easier for copper compounds formed by the combination of the additive and copper to come into contact with the adsorbent 2 and be easily adsorbed and removed. In this configuration, a stirring unit may be provided in the column 3 to forcibly flow the adsorbent 2.

[0027] The additives may be primary amines, secondary amines, or tertiary amines, or compounds in which a polar group such as a carboxy group has been added to a heterocyclic compound. Examples of heterocyclic compounds include benzotriazole, pyrrole, pyrazole, pyridine, and triazole. Primary amines, secondary amines, tertiary amines, and heterocyclic compounds are electron donating and tend to bond easily with copper in the insulating oil. Furthermore, if the heterocyclic compound has a polar group containing a carboxy group, it is more likely to be adsorbed by an adsorbent. These additives may also be dissolved in the insulating oil in advance.

[0028] The adsorbent may be activated clay, activated alumina, synthetic silica magnesia, synthetic silica alumina, zeolite, etc. Among these, synthetic silica magnesia is particularly desirable.

[0029] The median diameter of the adsorbent is preferably 0.1 mm or more and 3 mm or less on a volume basis. If it is smaller than 0.1 mm, the resistance when passing the insulating oil increases, and efficient treatment is not possible. On the other hand, if it is larger than 3 mm, the apparent specific surface area becomes small, so the frequency with which the insulating oil comes into contact with the adsorbent becomes relatively low, and the deterioration components cannot be sufficiently adsorbed. In addition, the specific surface area of ​​the adsorbent is 200 m or more. ２ / g or more. ２ / g or more, the deteriorated components in the insulating oil can be efficiently adsorbed. The larger the specific surface area of ​​the adsorbent, the higher the adsorption capacity. ２ It is desirable that the solubility is 1 / g or less.

[0030] The temperature when mixing the insulating oil and the additive is preferably 20 to 100°C. If the temperature is lower than 20°C, the solubility of the additive in the insulating oil is low, and the additive's effect is not fully achieved. On the other hand, if the temperature is higher than 100°C, the molecular structure of the additive is easily changed, and the additive's effect is not fully achieved.

[0031] The temperature at the contact point between the insulating oil and the adsorbent is preferably 20 to 100°C. If the temperature is lower than 20°C, the efficiency of removing the deteriorated components in the insulating oil decreases. On the other hand, if the temperature is higher than 100°C, the structure of the copper compound formed by bonding with the additive may change, and the copper compound may no longer be adsorbed by the adsorbent.

[0032] The combination of the additive and adsorbent (additive and adsorbent set) is one of the features of the present disclosure as an oil reclaiming device.

[0033] As the antioxidant, a phenol-based antioxidant, an amine-based antioxidant, etc., can be used. An example of the phenol-based antioxidant is 2,6-di-t-butyl-p-cresol (DBPC), and an example of the amine-based antioxidant is diphenylamine and its derivatives.

[0034] Next, the results of numerical calculations of the additive properties will be explained.

[0035] To evaluate the ease of bonding between copper and additives in insulating oil, the complex stabilization energy was calculated by first-principles calculation. The software used was Gaussian 09. For functionals, the copper ion basis function LANL2DZ and the additive molecular basis function 6-31+G(d) were used. Toluene was used in IEF-PCM to evaluate the solvent effect. The stabilization energy E during complex formation ｓｔａｂ is defined by the following formula:

[0036] E ｓｔａｂ = E ｃｏｍｐｌｅｘ - (E Ｃｕ +E ｍｏｌ ) where E ｃｏｍｐｌｅｘ is the energy of the complex structure, E Ｃｕ is the energy of the copper ion, E ｍｏｌ is the molecular energy. Stabilization energy E ｓｔａｂ is negative and the larger the absolute value, the more stable it is.

[0037] The additive molecules used in the calculations were methylamine, ethylamine, dimethylamine, pyridine, benzotriazole, triazole, pyrazole, pyrrole, acetic acid, and dimethyl ester. Of these, dimethyl ester simulated ester-based base oils such as polyol ester. Acetic acid simulated organic acids produced by base oil degradation. Acetic acid and dimethyl ester were used as reference substances.

[0038] Table 1 shows the calculated stabilization energies E ｓｔａｂ This shows the following.

[0039] As shown in this table, the E of all additives except acetic acid and dimethyl ester ｓｔａｂ is negative and has a large absolute value, indicating stability, compared with acetic acid and dimethyl ester. In particular, pyrazole and pyrrole show high stability. Furthermore, when comparing triazole and benzotriazole, benzotriazole shows high stability.

[0040] From the above, by adding an appropriate one of the additives described above to the insulating oil, the copper contained in the insulating oil bonds with the additive to form a stable complex structure.

[0041]

[0042] The more basic the ligand of the additive, i.e., the larger the acid dissociation constant pKa, the more stable the complex formed by bonding with copper. The additive preferably has, in its molecule, a functional group with an acid dissociation constant pKa of 5 or more and a polar group.

[0043] Benzotriazole (BTA) has a pKa of 8.2, while carboxylic acid, which is an example of a polar group, has a pKa of 3-5.

[0044] Next, a method for producing recycled oil using used insulating oil will be described as an example of a target for recycling treatment. The target for recycling treatment is not limited to used insulating oil, but can be any oil that contains degraded components, regardless of the cause.

[0045] FIG. 2 is a flow diagram showing an example of a method for producing recycled oil according to an embodiment.

[0046] In this figure, first, if necessary, the used insulating oil is heated to a predetermined temperature (step S201). Next, an additive is added to the used insulating oil (step S202). After that, the used insulating oil containing the additive is brought into contact with an adsorbent (step S203).

[0047] The method shown in this figure can remove components resulting from oil deterioration and copper dissolved in the oil.

[0048] Examples and comparative examples that demonstrate the effects of the present disclosure will be described below.

[0049] The experimental method and results are explained below.

[0050] The experiment was carried out in the following procedure.

[0051] First, the degraded oil is placed in a beaker and heated to 100°C. Next, the additive is mixed with the degraded oil and dissolved. Next, the adsorbent is added and stirred for 30 minutes. After that, the oil and the adsorbent are separated by suction filtration. The total acid number and the amount of dissolved copper of the separated oil are measured.

[0052] Here, the total acid number was measured in accordance with JIS C 2101. The amount of dissolved copper was measured by ICP atomic emission spectroscopy (inductively coupled plasma atomic emission spectroscopy).

[0053] The properties of the deteriorated oil are as follows:

[0054] Oil type: synthetic ester oil (MIDEL & MIVOLT Fluids, MIDEL7131) Total acid value: 25.35 mg-KOH / g Dissolved copper amount: 27 ppm The adsorbent is a silica-magnesia preparation (Mizuka Life (registered trademark) F-2GH, Mizusawa Industrial Chemicals).

[0055] The additives used in the examples and comparative example 1 are as follows.

[0056] Example: 5-benzotriazolecarboxylic acid (C-BTA) Comparative Example 1: benzotriazole (BTA) In Comparative Example 2, no additive was used.

[0057] The experimental conditions are as follows:

[0058] Amount of oil: 28.5 g Amount of adsorbent: 1.5 g The amount of additive was 4 mg for C-BTA and 2.9 mg for BTA, which was an amount that was 2 molar equivalents of each of the dissolved copper.

[0059] Table 2 shows the experimental results of the example and comparative examples 1 and 2. In the table, the value "<1" for the amount of dissolved copper is used. ＊ " indicates that the amount is below the detection limit.

[0060]

[0061] The following can be seen from this table:

[0062] The total acid number is reduced not only in the examples and comparative example 1 in which additives are used, but also in comparative example 2 in which no additives are used.

[0063] In contrast, the amount of dissolved copper was reduced in the example in which the additive was used and in Comparative Example 1. On the other hand, in Comparative Example 2, the amount of dissolved copper was hardly reduced.

[0064] Although this is a problem that is not reflected in the numerical values, in Comparative Example 1, insoluble matter was generated after the additive BTA was added to the deteriorated oil. In contrast, in the Examples, such a phenomenon of insoluble matter generation was not observed.

[0065] A separate process for removing the insoluble matter in Comparative Example 1 is required, because if oil containing insoluble matter is introduced into a column packed with an adsorbent, clogging of the column may occur.

[0066] The above results clearly show the superiority of the embodiment.

[0067] In the above examples, 5-benzotriazolecarboxylic acid (C6H3(N3H)COOH) is given as an example of an additive, but the structural formula is C6H3(N3H)(CH2) n COOH, C6H3(N3H)(CO(CH2) n )COOH or C6H3(N3H)(O(CH2) n)COOH (n=1 to 6) may also be used as additives. These can be collectively called "benzotriazole derivatives."

[0068] As described above, according to the present disclosure, the additive added to the used insulating oil causes the copper in the used insulating oil to react and become a compound with a polar group, and when the used insulating oil is passed through a column packed with an adsorbent placed in the downstream stage, the organic acids and copper compounds contained in the used insulating oil are adsorbed by the adsorbent, making it possible to efficiently remove degraded components from the used insulating oil.

[0069] Furthermore, according to the present disclosure, the additive dissolves in the oil, which can prevent clogging of the column.

[0070] According to the present disclosure, there is no need to install a filtration unit or the like other than a column containing an adsorbent.

[0071] According to the present disclosure, the additive can be supplied to the oil alone, so the configuration for supplying the additive can be simple piping only, eliminating the need to replace this component.

[0072] It should be noted that the above-described embodiments have been specifically described to aid in understanding the present disclosure, and the present disclosure is not limited to including all of the described configurations. For example, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete part of the configuration of each embodiment, replace it with another configuration, or add another configuration.

[0073] 1: insulating oil tank, 2: adsorbent, 3: column, 4, 7: line, 5: pump, 6: addition section, 8: stirring tank, 9: stirring operation section, 10, 11: sensor, 100: insulating oil regeneration device.

Claims

1. An oil regeneration device comprising: an addition section that adds an additive to oil containing copper and an organic acid; and an adsorbent contact section that brings the oil containing the additive into contact with an adsorbent, wherein the additive has, in its molecule, a functional group having an acid dissociation constant pKa of 5 or more and a polar group, the functional group of the additive bonds to the copper contained in the oil, and the adsorbent adsorbs the additive bonded to the copper and the organic acid contained in the oil.

2. The oil reclamation device of claim 1, wherein the additive is a benzotriazole derivative.

3. The oil reclamation device according to claim 1, wherein the base oil of the oil is a polyol ester or a vegetable oil.

4. The specific surface area of ​​the adsorbent is 200 m ２ / g or more 1000m ２ 2. The oil reclaiming device according to claim 1, wherein the oil reclaiming rate is 1 / g or less.

5. The oil reclamation device according to claim 1, further comprising an agitator for mixing the additive and the oil.

6. An oil regeneration device according to claim 1, wherein an organic acid sensor for measuring the content of the organic acid is installed downstream of the adsorbent contact section.

7. An oil regeneration device as described in claim 1, further comprising a copper sensor installed upstream of the addition section to measure the copper content in the oil, and a control section that controls the amount of additive added based on data from the copper sensor.

8. The oil reclaiming device according to claim 1, further comprising an antioxidant adding section for adding an antioxidant to the oil.

9. The oil reclamation device of claim 1, further comprising a heater for heating the oil to a predetermined temperature.

10. The oil reclamation apparatus of claim 1, wherein said adsorbent material is synthetic silica magnesia.

11. A method for producing reclaimed oil, comprising: a step of adding an additive to oil containing copper and an organic acid; and a step of contacting the oil containing the additive with an adsorbent, wherein the additive has, in its molecule, a functional group having an acid dissociation constant pKa of 5 or more and a polar group, the functional group of the additive binds to the copper contained in the oil, and the adsorbent adsorbs the additive bound to the copper and the organic acid contained in the oil.

12. The method for producing recycled oil according to claim 11, further comprising the step of heating the oil to a predetermined temperature.

13. A set of additive and adsorbent used in an oil regeneration device, wherein the oil contains copper and an organic acid, the additive is added to the oil and has a functional group with an acid dissociation constant pKa of 5 or more and a polar group in its molecule, the functional group of the additive bonds to the copper contained in the oil, and the adsorbent adsorbs the additive bound to the copper and the organic acid contained in the oil.

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