Method for producing anti-gassing component of transformer oil

Abstract

The invention relates to the technical field of petrochemical engineering, in particular to a method for producing an anti-gassing component of transformer oil. The method comprises the following steps: step 1, taking distillate oil solvent extract oil of the transformer oil as a raw material, performing extraction in a counter-current extraction tower by adopting a double-solvent double-tower extraction process to obtain solvent refined oil of the anti-gassing component of the transformer oil; and step 2, under the action of a hydrofining catalyst, hydrofining the solvent refined oil of the transformer oil anti-gassing component to obtain hydrofined oil, namely the transformer oil anti-gassing component. The anti-gassing component of the transformer oil prepared by the invention is low in basic nitrogen content, high in total content of monocyclic and bicyclic aromatic hydrocarbons, good in gassing property and excellent in oxidation stability.

Description

Technical Field:

[0001] The present invention relates to the technical field of petrochemical engineering, and particularly to a method for producing an anti-gassing component of transformer oil. Background Art:

[0002] Transformer oil, as an important insulating medium in power electrical equipment, plays roles such as heat dissipation, insulation, and arc extinction of transformers. With the development of the power industry and the improvement of the voltage level of power transmission and transformation equipment, the demand for transformer oil is increasing continuously, and at the same time, the quality requirements are also continuously improving. Its performance is of great significance to the safe operation of transformers.

[0003] Special transformer oil for extra-high voltage transformers has higher requirements for anti-gassing performance. Research shows that under the action of a high-voltage electric field in transformer oil, straight-chain alkanes in the oil will release more hydrogen, naphthenes will release less hydrogen, and aromatics will absorb the hydrogen released by straight-chain alkanes and naphthenes. This property of aromatics is called anti-gassing property, and substances with this property are called anti-gassing additives. Gassing property is an important index in high-voltage transformer oil. Aromatics have good anti-gassing performance, but excessive aromatics, especially polycyclic aromatics, affect the oxidation stability of the product.

[0004] To improve the gassing property of transformer oil, Chinese Patent CN102676215A uses the solvent-refined extract oil of transformer oil or a mixed oil of it and a naphthenic transformer oil fraction as raw materials, and through the processes of solvent refining - liquid-phase denitrification and clay refining, produces an anti-gassing additive, which has problems such as low aromatic content and poor anti-gassing property of the target product.

[0005] Chinese Patent CN 105087059B discloses an anti-gassing component of transformer oil and its preparation method. This method uses the solvent extract oil with a boiling range of 230 - 260 °C as raw material, and through complex denitrification with a denitrifying agent and adsorption with an adsorbent, obtains a refined oil, which is the anti-gassing component of transformer oil. The anti-gassing component produced by this method has a limited addition amount due to its low flash point. Summary of the Invention:

[0006] The technical problem to be solved by the present invention is to provide a method for producing an anti-gassing component of transformer oil. The anti-gassing component of transformer oil prepared by this method has a low basic nitrogen content, a high total content of single-ring and double-ring aromatics, good gassing property, and excellent oxidation stability.

[0007] The technical solution adopted by the present invention is: A method for producing an anti-gassing component of transformer oil, which method comprises the following steps:

[0008] Step 1: Using the solvent-extracted oil of transformer oil fraction as the raw material oil, conduct the process in a countercurrent extraction tower, adopting a double-solvent and double-tower extraction process. The solvents include the main solvent and the auxiliary solvent. After the raw material oil is mixed with the auxiliary solvent, it enters Extraction Tower I from the lower part of Extraction Tower I, and the main solvent enters Extraction Tower I from the upper part of Extraction Tower I. The extract obtained at the bottom of Extraction Tower I is recovered the main solvent to obtain the secondary extract. The raffinate at the top of Extraction Tower I enters Extraction Tower II from the lower part of Extraction Tower II as the raw material of Extraction Tower II, and the main solvent enters Extraction Tower II from the upper part of Extraction Tower II. The raffinate obtained at the top of Extraction Tower II can be recycled as the auxiliary solvent, and the extract obtained at the bottom of Extraction Tower II is recovered the main solvent to obtain the solvent-refined oil of the anti-gassing component of transformer oil;

[0009] Step 2: Under the action of a hydrofining catalyst, hydrofine the solvent-refined oil of the anti-gassing component of the transformer oil to obtain the hydrofined oil, which is the anti-gassing component of the transformer oil.

[0010] Further, the main solvent is furfural, and the auxiliary solvent is a base oil with a closed flash point of not less than 135 °C, a kinematic viscosity at 40 °C of not more than 12.0 mm 2 / s, a pour point of not higher than -35 °C, and a C A value of not more than 5%.

[0011] Further, the solvent-extracted oil of the transformer oil fraction is the solvent-extracted oil of naphthenic transformer oil, and the pour point is less than -40 °C.

[0012] Further, in Step 1, the temperature at the top of Extraction Tower I is 60 °C - 70 °C, the temperature at the bottom of Extraction Tower I is 40 °C - 50 °C, the mass ratio of the auxiliary solvent entering Extraction Tower I to the raw material oil is 0.3 - 1.0:1, and the mass ratio of the main solvent entering Extraction Tower I to the raw material oil is 2.5 - 6.0:1; the temperature at the top of Extraction Tower II is 80 °C - 85 °C, the temperature at the bottom of Extraction Tower II is 50 °C - 55 °C, and the mass ratio of the main solvent entering Extraction Tower II to the raw material oil is 2.5 - 6.0:1.

[0013] Further, the hydrofining catalyst in Step 2 is selected from one of the following catalysts: molybdenum-nickel type, tungsten-nickel type, molybdenum-cobalt type, and molybdenum-tungsten-nickel type hydrofining catalysts.

[0014] Further, the hydrofining catalyst in Step 2 is selected from one of the following catalysts: H-20 catalyst, LH-23 catalyst, LH-24 catalyst, LH-26 catalyst, LF-18 catalyst, LF-19 catalyst, CH-4 catalyst, FV-5 catalyst, FV-10 catalyst.

[0015] Further, in the second step, the temperature of hydrofining is 250°C to 300°C, the volume ratio of hydrogen to the solvent-refined oil is (500 to 1000):1, the volume space velocity of hydrofining is 0.30 h -1 ~1.0 h -1 , and the hydrogen partial pressure of hydrofining is 5.0 MPa to 8.0 MPa.

[0016] The beneficial effects of the present invention are as follows: The transformer oil prepared by the present invention has a low basic nitrogen content in the anti-gassing components, a high total content of single-ring and double-ring aromatic hydrocarbons, good gassing properties, and excellent oxidation stability. Description of the drawings:

[0017] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0018] Figure 1 It is the process flow diagram of the present invention.

[0019] The labels therein are respectively represented as: 1, extraction tower I; 2, extraction tower II; 3, auxiliary solvent; 4, main solvent of extraction tower I; 5, raw oil; 6, raffinate at the top of extraction tower I; 7, extract at the bottom of extraction tower I; 8, raffinate at the top of extraction tower II; 9, main solvent of extraction tower II; 10, extract at the bottom of extraction tower II. Specific embodiments:

[0020] The process flow of the present invention is as Figure 1 shown. Using the solvent-extracted oil of transformer oil fraction as the raw material, it is carried out in a countercurrent extraction tower, adopting a double-solvent double-tower extraction process, that is, the main solvent and the auxiliary solvent. The raw oil 5 is mixed with the auxiliary solvent 3 and then enters the extraction tower I 1 from the lower part of the extraction tower I 1. The main solvent 4 of the extraction tower I enters the extraction tower I 1 from the upper part of the extraction tower I 1. The extract at the bottom of the extraction tower I 7 is recovered the main solvent to obtain the secondary extract. The raffinate at the top of the extraction tower I 6 enters the extraction tower II 2 from the lower part of the extraction tower II 2 as the raw material of the extraction tower II 2. The main solvent 9 of the extraction tower II enters the extraction tower II 2 from the upper part of the extraction tower II 2. The raffinate at the top of the extraction tower II 2 obtained at the top of the extraction tower II 2 can be recycled as the auxiliary solvent. The extract at the bottom of the extraction tower II 2 obtained at the bottom of the extraction tower II 2 is recovered the main solvent to obtain the solvent-refined oil of the anti-gassing components of the transformer oil;

[0021] Under the action of a hydrofining catalyst, the solvent-refined oil of the anti-gassing components of the transformer oil is hydrofined to obtain a hydrofined oil, which is the anti-gassing components of the transformer oil.

[0022] Example 1

[0023] The solvent extraction separation process is carried out with the naphthenic normal second-line extract oil as the feedstock. The refining conditions of extraction column I1 are as follows: the top temperature of the column is 60 °C, the bottom temperature is 40 °C, the mass ratio of the secondary solvent to the feedstock is 0.3:1, and the mass ratio of the main solvent furfural to the feedstock is 2.5:1. The raffinate obtained at the top of extraction column I1 is used as the feedstock for extraction column II2. The refining conditions of extraction column II2 are as follows: the top temperature of the column is 85 °C, the bottom temperature is 55 °C, the mass ratio of the main solvent furfural to the feedstock is 2.5:1. The raffinate obtained at the top of extraction column II2 can be recycled as the secondary solvent. The extract obtained at the bottom of extraction column II2 is evaporated to remove the solvent, and the furfural-refined oil of the anti-gassing component of transformer oil is obtained.

[0024] The furfural-refined oil of the anti-gassing component of transformer oil is subjected to a hydrogenation test in a hydrogenation pilot plant (produced by Shenyang Shiboda Instrument Co., Ltd., with two reactors in series, the maximum catalyst loading in a single reactor being 200 ml, and the fresh hydrogen passing through once). In the first reactor, a hydrotreating catalyst (LF-19) is loaded. Only one reactor is used. After the hydrorefined oil is stripped to remove H2S and NH3, the anti-gassing component of transformer oil is obtained. The detailed operating parameters and properties are shown in Table 3.

[0025] The prepared anti-gassing component of transformer oil has a basic nitrogen content of less than 1 μg / g, a total content of single-ring and double-ring aromatics of 65.6%, a gassing property of less than -40 μL / min, a pour point below -55 °C, a polycyclic aromatic hydrocarbon content of less than 1.0%, and excellent oxidation stability.

[0026] Comparative Example 1

[0027] Using the naphthenic normal second-line extract oil as the feedstock, a conventional solvent extraction separation process is carried out. The refining conditions of the extraction column are as follows: the top temperature of the column is 60 °C, the bottom temperature is 40 °C, the mass ratio of the solvent furfural to the feedstock is 2.5:1. The feedstock enters the extraction column from the lower part, and the solvent furfural enters the extraction column from the upper part. The raffinate obtained at the top of the column is recovered to remove the solvent, and the furfural-refined oil of the anti-gassing component of transformer oil is obtained. The extract obtained at the bottom is evaporated to remove the solvent, and the extract oil is obtained.

[0028] The furfural-refined oil of the anti-gassing component of transformer oil uses the same hydrogenation experimental device, the same catalyst, and operating conditions as in Example 1. The detailed operating parameters and properties are shown in Table 3.

[0029] The prepared anti-gassing component of transformer oil has a basic nitrogen content of less than 1 μg / g, a total content of single-ring and double-ring aromatics greater than 42.9%, a gassing property of less than -22 μL / min, a pour point below -48 °C, a polycyclic aromatic hydrocarbon content of less than 1.0%, and excellent oxidation stability. Compared with Example 1, the total content of single-ring and double-ring aromatics decreases, and the gassing property deteriorates.

[0030] Comparative Example 2

[0031] Using the naphthenic heavy neutral oil as raw material, with the same hydrotreating experimental device and the same catalyst as in Example 1, the operating pressure of hydrofining is 8.0 MPa. The detailed operating parameters and properties are shown in Table 3.

[0032] The whole fraction oil after hydrofining is distilled, and the fraction greater than 280 °C is used as the gas evolution resistance component of transformer oil. The total content of single-ring and double-ring aromatic hydrocarbons in the prepared gas evolution resistance component of transformer oil is 55.5%, the gas evolution property is less than -40 μL / min, and the oxidation stability is poor. However, the basic nitrogen content is 89 μg / g, which is much higher than that in Example 1. Especially for the oxidation stability measured by the SH / T0811 method, the total acid value is 6.5 mgKOH / g, and the sludge is 4.8%, indicating that the oxidation stability of the prepared gas evolution resistance component of transformer oil is very poor.

[0033] Comparative Example 3

[0034] Using the naphthenic heavy neutral oil as raw material, with the same hydrotreating experimental device, the same catalyst, and the same operating pressure as in Comparative Example 2, the reaction temperature is increased. The detailed operating parameters and properties are shown in Table 3.

[0035] The whole fraction oil after hydrofining is distilled, and the fraction greater than 280 °C is used as the gas evolution resistance component of transformer oil. It can be seen from Table 3 that the total content of single-ring and double-ring aromatic hydrocarbons in the prepared gas evolution resistance component of transformer oil is 30.5%, the gas evolution property is less than -11 μL / min, and the basic nitrogen content is less than 1.0 μg / g. Especially for the oxidation stability measured by the SH / T0811 method, the total acid value is 0.3 mgKOH / g, and the sludge is 0.12%, indicating that the oxidation stability of the prepared gas evolution resistance component of transformer oil is excellent. Compared with Comparative Example 2, the oxidation stability of the product is improved but the gas evolution performance decreases.

[0036] Example 2

[0037] A solvent extraction separation process is carried out using the naphthenic heavy neutral oil as the raw material oil. The refining conditions of Extraction Tower I1 are: the top temperature is 65 °C, the bottom temperature is 40 °C, the mass ratio of the secondary solvent to the raw material oil is 0.5:1, and the mass ratio of the main solvent furfural to the raw material oil is 3.5:1. The raffinate obtained at the top of Extraction Tower I1 is used as the raw material of Extraction Tower II2. The refining conditions of Extraction Tower II2 are: the top temperature is 80 °C, the bottom temperature is 50 °C, and the mass ratio of the main solvent furfural to the raw material is 3.0:1. The raffinate obtained at the top of Extraction Tower II2 can be recycled as the secondary solvent. After the extract obtained at the bottom of Extraction Tower II2 is evaporated of the solvent, the furfural-refined oil of the gas evolution resistance component of transformer oil is obtained.

[0038] The furfural-refined oil of the gas evolution resistance component of transformer oil is processed using the same hydrotreating experimental device and the same catalyst as in Example 1. The detailed operating parameters and properties are shown in Table 3.

[0039] The basic nitrogen content of the gas separation resistance component of the prepared transformer oil is less than 1 μg / g, the total content of single-ring and double-ring aromatic hydrocarbons is greater than 64.0%, the gas separation property is less than -40 μL / min, the pour point is lower than -55 °C, the polycyclic aromatic hydrocarbon content is less than 1.0%, and the oxidation stability is excellent.

[0040] Example 3

[0041] Using the naphthenic intermediate second-line extract oil as the raw material oil, a solvent extraction separation process is carried out. The refining conditions of extraction tower I1 are: the top temperature is 70 °C, the bottom temperature is 40 °C, the mass ratio of the secondary solvent to the raw material oil is 1:1, and the mass ratio of the main solvent furfural to the raw material oil is 6:1. The raffinate obtained at the top of extraction tower I1 is used as the raw material of extraction tower II2. The refining conditions of extraction tower II2 are: the top temperature is 80 °C, the bottom temperature is 50 °C, and the mass ratio of the main solvent furfural to the raw material is 5.0:1. The raffinate obtained at the top of extraction tower II2 can be recycled as the secondary solvent, and the extract obtained at the bottom of extraction tower II2 is evaporated to obtain the furfural refined oil of the gas separation resistance component of the transformer oil.

[0042] For the furfural refined oil of the gas separation resistance component of the transformer oil, the same hydrogenation experimental device and the same catalyst as in Example 1 are used, and the detailed operating parameters and properties are shown in Table 3.

[0043] The basic nitrogen content of the gas separation resistance component of the prepared transformer oil is less than 1 μg / g, the total content of single-ring and double-ring aromatic hydrocarbons is greater than 60.6%, the gas separation property is less than -40 μL / min, the pour point is lower than -48 °C, the polycyclic aromatic hydrocarbon content is less than 1.0%, and the oxidation stability is excellent.

[0044] Table 1 Properties of raw material oil

[0045]

[0046] Table 2 Properties of secondary solvent

[0047]

[0048] Table 3 Process conditions of examples and comparative examples

[0049]

[0050] From Examples 1-3 and Comparative Examples 1-3, it can be seen that using the furfural extract oil of naphthenic normal secondary deacidified oil as the raw material and adopting the method of the present invention to obtain the furfural refined oil, after hydrorefining, the total content of single-ring and double-ring aromatic hydrocarbons in the product is greater than 60%, the gas evolution property is less than -40 uL / min, the pour point is lower than -50 °C, the content of polycyclic aromatic hydrocarbons is less than 1.0%, and the oxidation stability is excellent, which can be used as a blending component for improving the gas evolution property of transformer oil; it can be seen from Comparative Example 1 that using conventional furfural refining to obtain the furfural refined oil, after hydrorefining, the total content of single-ring and double-ring aromatic hydrocarbons in the product is 42.9%, and the gas evolution property is -22 uL / min, and the gas evolution property and aromatic hydrocarbon content of the product are greatly reduced; it can be seen from Comparative Example 2 that using the furfural extract oil of naphthenic normal secondary deacidified oil as the raw material, the basic nitrogen content of the gas evolution-resistant component of the transformer oil produced by the single hydrorefining method is high, and the oxidation stability of the product is poor and cannot meet the requirements; it can be seen from Comparative Example 3 that after increasing the reaction temperature, the total content of single-ring and double-ring aromatic hydrocarbons in the gas evolution-resistant component of the transformer oil obtained is 30.5%, the gas evolution property is less than -11 uL / min, the pour point is -48 °C, the content of polycyclic aromatic hydrocarbons is less than 1.0%, and the oxidation stability is excellent, but the gas evolution property and aromatic hydrocarbon content of the product are greatly reduced. The gas evolution-resistant component with high aromatic hydrocarbon content, good gas evolution property and good oxidation stability at the same time cannot be produced by using the hydrorefining method alone; the gas evolution-resistant component with high aromatic hydrocarbon content, good gas evolution property and oxidation stability at the same time of the present invention cannot be produced by using the conventional solvent refining-hydrorefining combined process either.

[0051] It can be understood that the above specific description of the present invention is only for explaining the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced to achieve the same technical effects; as long as the use requirements are met, they are all within the protection scope of the present invention.

Claims

1. A method for producing an anti-gassing component of transformer oil, characterized in that: The method comprises the following steps: Step 1: Using the solvent-extracted oil of transformer oil fraction as the raw material oil, which is carried out in a countercurrent extraction tower and adopts a double-solvent double-tower extraction process. The solvents include a main solvent and a secondary solvent. After the raw material oil is mixed with the secondary solvent, it enters Extraction Tower I from the lower part of Extraction Tower I, and the main solvent enters Extraction Tower I from the upper part of Extraction Tower I. The extract obtained at the bottom of Extraction Tower I is recovered of the main solvent to obtain a secondary extract. The raffinate at the top of Extraction Tower I enters Extraction Tower II from the lower part of Extraction Tower II as the raw material of Extraction Tower II, and the main solvent enters Extraction Tower II from the upper part of Extraction Tower II. The raffinate obtained at the top of Extraction Tower II can be recycled as the secondary solvent. The extract obtained at the bottom of Extraction Tower II is recovered of the main solvent to obtain a solvent-refined oil of the anti-gassing component of transformer oil; Step 2: Under the action of a hydrofining catalyst, the solvent-refined oil of the anti-gassing component of the transformer oil is hydrofined to obtain a hydrofined oil, which is the anti-gassing component of the transformer oil.

2. The method for producing the anti-gassing component of transformer oil according to claim 1, characterized in that: The main solvent is furfural, and the secondary solvent is a base oil with a closed-cup flash point of not less than 135°C, a kinematic viscosity at 40°C of not more than 12.0 mm 2 / s, a pour point of not higher than -35°C, and a C A value of not more than 5%.

3. The method for producing the anti-gassing components of transformer oil according to claim 1, characterized in that: The solvent-extracted oil of the transformer oil fraction is the solvent-extracted oil of naphthenic transformer oil, and the pour point is less than -40°C.

4. The method for producing the anti-gassing component of transformer oil according to claim 1, characterized in that: In Step 1, the temperature at the top of Extraction Tower I is 60°C - 70°C, the temperature at the bottom of Extraction Tower I is 40°C - 50°C, the mass ratio of the secondary solvent entering Extraction Tower I to the raw material oil is 0.3 - 1.0:1, and the mass ratio of the main solvent entering Extraction Tower I to the raw material oil is 2.5 - 6.0:1; the temperature at the top of Extraction Tower II is 80°C - 85°C, the temperature at the bottom of Extraction Tower II is 50°C - 55°C, and the mass ratio of the main solvent entering Extraction Tower II to the raw material oil is 2.5 - 6.0:

1.

5. The method for producing the anti-gassing component of transformer oil according to claim 1, characterized in that: The hydrofining catalyst in Step 2 is selected from one of the following catalysts: molybdenum-nickel type, tungsten-nickel type, molybdenum-cobalt type, and molybdenum-tungsten-nickel type hydrofining catalysts.

6. The method for producing the anti-gassing component of transformer oil according to claim 5, characterized in that: The hydrofining catalyst in Step 2 is selected from one of the following catalysts: H-20 catalyst, LH-23 catalyst, LH-24 catalyst, LH-26 catalyst, LF-18 catalyst, LF-19 catalyst, CH-4 catalyst, FV-5 catalyst, FV-10 catalyst.

7. The method for producing the anti-gassing component of transformer oil according to claim 1 or 2, characterized in that: In the second step, the temperature of hydrofining is 250°C to 300°C, the volume ratio of hydrogen to the solvent-refined oil is (500 to 1000):1, the volume space velocity of the hydrofining is 0.30 h -1 ~1.0 h -1 , and the hydrogen partial pressure of the hydrofining is 5.0 MPa to 8.0 MPa.

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