Adsorption decolorization process of natural ester insulating oil

Abstract

The invention relates to the technical field of transformer insulating oil, and discloses an adsorption decolorization process of natural ester insulating oil. According to the adsorption decolorization process, activated carbon, calcium oxide and water are firstly adopted to prepare a calcium-based alkaline adsorbent, and then the calcium-based alkaline adsorbent is mixed with natural ester insulating oil for adsorption decolorization; and filtering the natural ester insulating oil after adsorption and decoloration to obtain the base oil after adsorption and decoloration. According to the method, the calcium-based alkaline adsorbent with activated carbon and calcium oxide as components is used for adsorbing and decolorizing the natural ester insulating oil, so that common pigments in the vegetable oil can be preliminarily removed, and impurities, trace metals and some odor substances in the vegetable oil can be removed. According to the adsorption decolorization process, the acid value and the dielectric loss factor in the vegetable oil can be reduced, so that the natural ester insulating oil reaches a relatively excellent level, and subsequent refining procedures and operations are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of transformer insulating oil, and in particular to an adsorption decolorization process of natural ester insulating oil. Background Art

[0002] Natural ester insulating oil, made from natural oils and primarily composed of triglycerides of fatty acids, has attracted increasing attention due to its safety, environmental friendliness, oral non-toxicity, renewable nature, and low carbon emissions compared to traditional mineral insulating oils. This has led to widespread adoption in Western countries. Research on natural ester insulating oil began early abroad, establishing relevant technologies and standards. This has led to successful application in power transformers operating at high voltages of 220 kV and above, with even greater application in distribution transformers. Currently, the global total of natural ester insulating oil produced abroad in transformers exceeds 1.2 million units.

[0003] Over the past decade, natural ester insulating oil has been widely used in 10kV, 35kV, and 110kV distribution transformers, operating successfully. Decolorization methods are categorized into physical and chemical methods. Physical methods primarily include adsorption, extraction, and ion exchange, while chemical methods primarily include oxidation, reduction, and hydrogenation. Currently, adsorption decolorization is the most widely used method in the preparation of natural ester insulating oil. The pigments in natural ester insulating oil are primarily chlorophyll and carotenoids. Decolorization not only improves the clarity of the oil, but also removes colloids and some metal ions, effectively facilitating further refining. However, physical adsorption decolorization can lead to varying quality of the decolorized insulating oil depending on the process, particularly in terms of dielectric loss factor at 90°C, which often determines the lifespan and performance stability of the transformer. Therefore, a new decolorization process for natural ester insulating oil is needed. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide an adsorption decolorization process for natural ester insulating oil, so that the natural ester insulating oil treated by the adsorption decolorization process has better performance, mainly manifested in better 90°C dielectric loss factor and acid value.

[0005] In order to solve the above technical problems / achieve the above objectives or at least partially solve the above technical problems / achieve the above objectives, as a first aspect of the present application, a process for adsorption decolorization of natural ester insulating oil is provided, comprising:

[0006] S1. A calcium-based alkaline adsorbent is prepared using activated carbon, calcium oxide, and water;

[0007] S2 the calcium-based alkaline adsorbent and natural ester insulating oil mixed adsorption decolorization;

[0008] S3. Filter the natural ester insulating oil after adsorption and decolorization to obtain the base oil after adsorption and decolorization.

[0009] Optionally, the S1 includes:

[0010] The activated carbon, calcium oxide and water are mixed evenly, baked, then washed, dried and crushed to obtain a powdered calcium-based alkaline adsorbent.

[0011] Further optionally, the mass ratio of the activated carbon to calcium oxide is (2-4):(1-3); further optionally, the mass ratio of the activated carbon to calcium oxide is 3:2.

[0012] Further optionally, the baking comprises baking at 85-95° C. for 4-6 hours.

[0013] Optionally, the temperature of the adsorption decolorization is 40-50° C., and the vacuum degree is 20-50 mmHg.

[0014] Optionally, the filtration is performed using a filter device with a pore size of 0.5-2 μm.

[0015] Optionally, the natural ester insulating oil includes one or more of rapeseed oil-based natural ester insulating oil, soybean oil-based natural ester insulating oil, sunflower oil-based natural ester insulating oil, and palm oil-based natural ester insulating oil.

[0016] Optionally, the adsorption decolorization process of the present application further comprises refining the base oil. Further optionally, the refining comprises one or more operations of dehydration, degassing, removal of oxidation products, and deep purification.

[0017] This application utilizes a calcium-based alkaline adsorbent composed of activated carbon and calcium oxide to perform adsorption decolorization on natural ester insulating oil. This not only preliminarily removes common pigments from vegetable oils, but also impurities, trace metals, and certain odorous substances. This adsorption decolorization process can reduce the acid value and dielectric loss factor of vegetable oils, achieving superior quality for natural ester insulating oils and reducing subsequent refining steps and operations. DETAILED DESCRIPTION

[0018] The present application discloses an adsorption decolorization process for natural ester insulating oil. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all deemed to be included in this application. The products, processes and applications described in this application have been described through preferred embodiments. It is obvious that relevant personnel can modify or appropriately change and combine the processes and applications described herein without departing from the content, spirit and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0019] It should be noted that, in this document, if relational terms such as "first" and "second", "step 1" and "step 2", and "(1)" and "(2)" appear, they are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. At the same time, the embodiments in this application and the features in the embodiments can be combined with each other in the absence of conflict.

[0020] In a first aspect of the present application, a process for adsorption decolorization of natural ester insulating oil is provided, comprising:

[0021] S1. A calcium-based alkaline adsorbent is prepared using activated carbon, calcium oxide, and water;

[0022] S2 the calcium-based alkaline adsorbent and natural ester insulating oil mixed adsorption decolorization;

[0023] S3. Filter the natural ester insulating oil after adsorption and decolorization to obtain the base oil after adsorption and decolorization.

[0024] This application creatively screens and selects two suitable materials to form a physical adsorption decolorization material. The combined use of activated carbon and calcium oxide can maximize the reduction of the acid value and dielectric loss factor in vegetable oil, improve the performance of the base oil after preliminary treatment, and reduce the process and cost of subsequent insulating oil refining.

[0025] In certain embodiments of the present application, the S1 includes:

[0026] Activated carbon, calcium oxide, and water are mixed evenly, baked, then washed, dried, and crushed to obtain a powdered calcium-based alkaline adsorbent. The porous structure of the baked activated carbon absorbs some of the calcium oxide particles, forming a loose mixed solid that allows the two to better perform physical adsorption.

[0027] In some other embodiments of the present application, the mass ratio of the activated carbon to calcium oxide is (2-4):(1-3); for example, 4:3, 3:2, 2:1, etc. The baking comprises baking at 85-95°C for 4-6 hours, wherein the baking temperature can be selected from 85°C, 90°C, 95°C, etc., and the baking time can be selected from 4 hours, 5 hours, 6 hours, etc.

[0028] In certain embodiments of the present application, the added amount of the calcium-based alkaline adsorbent accounts for 4-5% by weight of the natural ester insulating oil.

[0029] To improve the efficiency of adsorption decolorization, in certain embodiments of the present application, the adsorption decolorization temperature is 40-50°C and the vacuum is 20-50 mmHg. Under these conditions, the physical adsorption process of the natural ester insulating oil is accelerated, shortening the treatment time, and the decolorization time is generally 2-4 hours. In other embodiments of the present application, the temperature can be 40°C, 45°C, 50°C, etc., the vacuum can be 20 mmHg, 35 mmHg, 50 mmHg, etc., and the decolorization time can be 2 hours, 3 hours, 4 hours, etc.

[0030] In certain embodiments of the present application, the filtration is performed using a filter device with a pore size of 0.5-2 μm, for example, a filter with a pore size of 1 μm is used to perform filtration while hot to remove impurities and calcium-based alkaline adsorbent.

[0031] In certain embodiments of the present application, the natural ester insulating oil includes one or more of rapeseed oil-based natural ester insulating oil, soybean oil-based natural ester insulating oil, sunflower oil-based natural ester insulating oil, and palm oil-based natural ester insulating oil.

[0032] In other embodiments of the present application, the adsorption decolorization process further comprises refining the base oil. Further optionally, the refining comprises one or more of dehydration, degassing, removal of oxidation products, and deep purification. Dehydration and degassing can be performed using vacuum dehydration and nitrogen bubbling; removal of oxidation products can be performed by dissolving and removing them using an organic solvent; and deep purification can be performed using ion exchange resins and electrostatic oil purification.

[0033] In certain embodiments of the present application, different physical adsorption materials are used for adsorption and decolorization treatment. The results show that the experimental group using activated carbon and calcium oxide exhibits better performance in dielectric loss factor and acid value at 90°C compared with the crude oil and other adsorbent treatment groups.

[0034] The following further describes the adsorption decolorization process of a natural ester insulating oil provided in this application.

[0035] Example 1:

[0036] 1) Preparation of calcium-based alkaline adsorbent: Activated carbon and calcium oxide were mixed in a mass ratio of 3:2, and a certain amount of pure water was added to mix them evenly. The mixture was placed in an oven and dried at 90°C for 5 hours. The mixture was washed with pure water, dried, and crushed to obtain a powder, i.e., the calcium-based alkaline adsorbent.

[0037] 2) A certain amount of soybean oil-based natural ester raw material oil is injected into a decolorization reaction vessel, and the temperature is raised to 45° C., and a calcium-based alkaline adsorbent is added at 4-5% by weight of the oil. The vacuum degree of the reaction vessel is maintained at about 35 mmHg, and the decolorization is carried out by stirring and adsorption for 3 hours.

[0038] 3) Filtering the oil while hot using a filter with a pore size of 1 μm to remove impurities and calcium-based alkaline adsorbent to obtain a preliminarily treated base oil.

[0039] Example 2:

[0040] 1) Preparation of calcium-based alkaline adsorbent: Activated carbon and calcium oxide were mixed in a mass ratio of 4:3, and a certain amount of pure water was added to mix them evenly. The mixture was placed in an oven and dried at 85°C for 6 hours. The mixture was washed with pure water, dried, and crushed to obtain a powder, i.e., the calcium-based alkaline adsorbent.

[0041] 2) A certain amount of rapeseed oil-based natural ester raw oil is injected into a decolorization reaction vessel, and the temperature is raised to 50° C., and a calcium-based alkaline adsorbent is added at 4-5% by weight of the oil. The vacuum degree of the reaction vessel is maintained at about 50 mmHg, and the decolorization is carried out by stirring and adsorption for 2 hours.

[0042] 3) Filtering the oil while hot using a filter with a pore size of 0.5 μm to remove impurities and calcium-based alkaline adsorbent to obtain a preliminarily treated base oil.

[0043] Example 3:

[0044] 1) Preparation of calcium-based alkaline adsorbent: Activated carbon and calcium oxide were mixed in a mass ratio of 2:1, and a certain amount of pure water was added to mix them evenly. The mixture was placed in an oven and dried at 95°C for 4 hours. The mixture was washed with pure water, dried, and crushed to obtain a powder, i.e., the calcium-based alkaline adsorbent.

[0045] 2) A certain amount of sunflower oil-based natural ester raw material oil is injected into a decolorization reaction vessel, and the temperature is raised to 40° C., and a calcium-based alkaline adsorbent is added at 4-5% by weight of the oil. The vacuum degree of the reaction vessel is maintained at about 20 mmHg, and the decolorization is carried out by stirring and adsorption for 5 hours.

[0046] 3) Filtering while hot using a filter with a pore size of 2 μm to remove impurities and calcium-based alkaline adsorbent to obtain a preliminarily treated base oil.

[0047] Comparative Example 1:

[0048] The process was carried out in accordance with Example 1, except that activated carbon and activated clay were mixed in a mass ratio of 3:2 to prepare the adsorbent, and the rest remained the same as in Example 1.

[0049] Comparative Example 2:

[0050] The process was carried out in accordance with Example 1, except that diatomaceous earth and silicon dioxide were mixed in a mass ratio of 3:2 to prepare the adsorbent, and the rest remained the same as in Example 1.

[0051] Experimental example:

[0052] The untreated soybean oil-based natural ester raw oil (1#), as well as the treated base oils of Example 1 (2#), Comparative Example 1 (3#), and Comparative Example 2 (4#), were tested for acid value, conductivity, 90°C dielectric loss factor, and color index. The results are shown in Table 1 below.

[0053] Table 1

[0054] Technical indicators 1# 2# 3# 4# Test Method Conductivity / (pS / m) 29.0 3.5 3.6 3.4 ― Chroma, No. ＜1.0 ＜0.5 ＜0.5 ＜0.5 SH / T 0168 90℃ dielectric loss factor / % 2.17 0.55 0.81 0.93 GB / T 5654 Acid value / (mg KOH / g) 0.078 0.010 0.033 0.042 GB / T 264

[0055] The results in Table 1 clearly show that the base oil treated in Example 1 exhibits superior properties such as 90°C dielectric loss factor and acid value, demonstrating that the adsorbent's specific material combination can achieve superior physical adsorption decolorization. Furthermore, the base oil can be further refined as needed, such as through dehydration, degassing, oxidation product removal, and deep purification.

[0056] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A process for decolorizing natural ester insulating oil by adsorption, characterized in that: include: S1. A calcium-based alkaline adsorbent is prepared using activated carbon, calcium oxide, and water; S2 the calcium-based alkaline adsorbent and natural ester insulating oil mixed adsorption decolorization; S3. Filter the natural ester insulating oil after adsorption and decolorization to obtain the base oil after adsorption and decolorization.

2. The adsorption decolorization process according to claim 1, characterized in that Said S1 comprises: The activated carbon, calcium oxide and water are mixed evenly, baked, then washed, dried and crushed to obtain a powdered calcium-based alkaline adsorbent.

3. The adsorption decolorization process according to claim 1 or 2, characterized in that: The mass ratio of the activated carbon to calcium oxide is (2-4):(1-3).

4. The adsorption decolorization process according to claim 3, characterized in that The mass ratio of the activated carbon to calcium oxide is 3:

2.

5. The adsorption decolorization process according to claim 2, characterized in that: The baking comprises baking at 85-95° C. for 4-6 hours.

6. The adsorption decolorization process according to claim 1, characterized in that: The temperature of the adsorption decolorization is 40-50° C., and the vacuum degree is 20-50 mmHg.

7. The adsorption decolorization process according to claim 1, characterized in that: The filtration is carried out using a filter device with a pore size of 0.5-2 μm.

8. The adsorption decolorization process according to claim 1, characterized in that: The natural ester insulating oil includes one or more of rapeseed oil-based natural ester insulating oil, soybean oil-based natural ester insulating oil, sunflower oil-based natural ester insulating oil, and palm oil-based natural ester insulating oil.

9. The adsorption decolorization process according to claim 1, characterized in that: It also includes refining of base oils.

10. The adsorption decolorization process according to claim 9, characterized in that: The refining includes one or more operations of dehydration, degassing, removal of oxidation products, and deep purification.