A kind of transformer oil production process

Abstract

The invention discloses a transformer oil production process, comprising the following steps: (1) a hydrorefining process: using hydrocracked diesel as a raw material, sending the hydrocracked diesel to a hydrogenation reaction unit, mixing it with circulating hydrogen after heat exchange and heating, sending it to a heating furnace, heating it in the heating furnace and sending it to a hydrogenation reactor for hydrorefining to obtain hydrogenated oil; (2) a fractionation and stripping process: sending the hydrogenated oil to a fractionation unit, entering a fractionation tower for vacuum fractionation after heat exchange and heating, and producing transformer oil base oil at the bottom of the tower. After adding an antioxidant, a qualified transformer oil product is produced. The invention uses hydrocracked diesel as a raw material, obtains qualified transformer oil base oil through hydrorefining and vacuum fractionation, has a simple process route, and has low requirements on the operating conditions of the hydrogenation reaction. It can extend the processing depth of the traditional hydrocracking unit, optimize the product structure of the traditional refinery, and improve the refining efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of transformer oil preparation, and in particular to a transformer oil production process. Background Art

[0002] Transformer oil is a necessary medium for transformer operation, and it mainly plays the role of insulation and heat dissipation. Its quality is directly related to the safe operation of the transformer. The production process of transformer oil has developed with the development of oil refining technology. Existing transformer oil is mainly made of cycloalkane crude oil or paraffin-based crude oil, and is prepared by a combination of vacuum distillation, hydrorefining, solvent extraction, and clay supplementary refining. For example, US5167847 relates to a method for producing transformer oil using paraffin-based oil as raw material, and the method produces transformer oil components through hydrocracking, solvent dewaxing, and hydrorefining processes; CN1990833A discloses a method for producing ultra-high voltage transformer oil, and the method produces ultra-high voltage transformer oil by subjecting cycloalkane distillate oil to a two-stage hydrogenation pretreatment process. CN102311785A discloses a method for producing lubricating oil base oil by hydrogenating cycloalkyl distillate oil, wherein the method uses cycloalkyl distillate oil as a raw material to produce lubricating oil base oil by hydrogenation treatment, hydrogenation decondensation and hydrogenation refining processes under high pressure (10-20MPa); CN106833740A discloses a method for preparing transformer oil base oil, wherein cycloalkyl distillate oil is subjected to hydrogenation refining, hydrogenation isomerization and hydrogenation supplementary refining under the action of a catalyst to obtain a three-stage hydrogenation product oil, and then atmospheric and vacuum distillation is performed to obtain transformer oil base oil.

[0003] The above patented methods can prepare qualified transformer oil, but the preparation process is complicated, and the bromine index of the prepared transformer oil is high. After being stored for a period of time, it will oxidize and turn yellow, and the electrical properties will deteriorate. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a transformer oil production process.

[0005] The technical solution adopted by the present invention is:

[0006] A transformer oil production process comprises the following steps:

[0007] (1) Hydrorefining process:

[0008] The hydrocracking diesel is used as raw material, and is sent to the hydrogenation reaction unit. After heat exchange and temperature increase, it is mixed with circulating hydrogen and sent to the heating furnace. After heating in the heating furnace, it is sent to the hydrogenation reactor for hydrogenation refining to obtain hydrogenated oil.

[0009] (2) Fractional distillation and stripping process:

[0010] The hydrogenated oil is sent to the distillation unit, and after heat exchange and temperature increase, it enters the distillation tower for vacuum distillation. Transformer oil base oil is produced at the bottom of the tower. After adding antioxidants, qualified transformer oil products are produced.

[0011] The present application uses hydrocracking diesel as raw material, firstly removes olefins, sulfides, aromatics, etc. in the raw oil through hydrofining reaction; the reaction product after hydrofining is fractionated and stripped to produce transformer oil base oil, and after adding antioxidant, a qualified transformer oil product is obtained. In addition, according to market demand, by optimizing the operating parameters of the hydrogenation reaction system, the aromatic content of the product is controlled to be ≯5%, and a qualified 7# industrial white oil product can be produced.

[0012] More preferably, the hydrocracked diesel is diesel produced by hydrocracking of atmospheric and vacuum wax oil as a raw material.

[0013] More preferably, the bromine index of the hydrocracked diesel is 480-900 mgBr / 100 g, the initial distillation point is 280-290°C, the dry point is 360-370°C, and the flash point is greater than 141°C.

[0014] Further preferably, the inlet temperature of the hydrogenation reactor is 150-280°C, the total temperature rise of the bed is ≯50°C, the reaction pressure is 2.3-3.1 MPa, and the hydrogen-to-oil ratio is 284-426.

[0015] The above process ensures, on the one hand, the effects of removing olefins and aromatics and reducing the bromine index of the hydrogenation reaction system, thereby preventing the transformer oil base oil from oxidative discoloration, and on the other hand, it also ensures the yield of the target product and a reasonable catalyst service life.

[0016] More preferably, the inlet temperature of the hydrogenation reactor is 170-280° C., the reaction pressure is 2.5-3.1 MPa, and the hydrogen-to-oil ratio is 325-980.

[0017] By adopting the above process, the aromatic content in the target product can be made ≯5%, thereby producing a qualified 7# industrial white oil product.

[0018] More preferably, the bottom of the distillation tower is heated by a heater to control the bottom temperature to be ≯320°C and the top pressure to be ≯0.1 MPa.

[0019] By adopting the above process, the light components (initial distillation point greater than 280°C) in the transformer oil can be effectively removed to ensure that the initial distillation point and flash point are qualified; it can also prevent excessive separation and excessive transformer oil loss, which will reduce the yield of the transformer oil base oil.

[0020] Further preferably, an inert gas is introduced into the bottom of the fractionation tower to strip the generated transformer oil base oil to remove light hydrocarbon components and water vapor in the transformer oil base oil, so as to ensure that the flash point is qualified.

[0021] More preferably, the inert gas is nitrogen.

[0022] Beneficial effects of the present invention: if transformer oil contains olefins or polycyclic aromatic hydrocarbons, the carbon-carbon unsaturated bonds therein will seriously affect the stability of transformer oil and easily change color. However, aromatic hydrocarbons can dissolve the sludge and gas in transformer oil and are a natural antioxidant. Appropriate aromatic hydrocarbon content and aromatic hydrocarbon type are important guarantees for qualified transformer oil. Hydrogenation treatment can effectively remove heterocyclic compounds, saturate polycyclic aromatic hydrocarbons, reduce chromaticity, and improve the oxidation stability of oil products, but it will also saturate some benzene and tea series aromatic hydrocarbons, causing the gasification of transformer oil to exceed the standard. Therefore, selecting suitable raw materials and ensuring the appropriate aromatic hydrocarbon content and high yield of the product according to the properties of the raw oil and the quality requirements of the product are the key to producing transformer oil. The present application uses hydrocracking diesel as raw material, obtains qualified transformer oil base oil through hydrorefining and vacuum fractionation, has a simple process route, and the operating conditions of the hydrogenation reaction are not high. It can extend the processing depth of traditional hydrocracking units, optimize the product structure of traditional refineries, and improve the efficiency of oil refining. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a schematic flow diagram of a transformer oil production process. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific examples to facilitate understanding of the present invention, but the present invention is not limited thereto.

[0025] See also Figure 1 , Figure 1 The process flow of the transformer oil production process of the present invention is illustrated, but the process flow of the transformer oil production process of the present invention is not limited thereto. The hydrogenation reactor of the hydrogenation reaction unit may be one or more, and the multiple hydrogenation reactors may be used in parallel or in series. When the multiple hydrogenation reactors are used in series or in parallel, as long as the inlet temperature of each hydrogenation reactor is controlled to be 150-280°C, the total temperature rise of the bed is ≯50°C, the reaction pressure is 2.3-3.1MPa, and the hydrogen-to-oil ratio is 284-980, the hydrorefining effect of the present invention can be achieved. Figure 1 In the process shown, the number of hydrogenation heat exchangers and fractionation heat exchangers and the heat exchange method are set to save energy and have nothing to do with the hydrogenation refining effect of the present invention.

[0026] The present invention provides a method for using Figure 1 The process flow shown in the figure is used to produce transformer oil in five specific embodiments, Embodiment 1 to Embodiment 5, and the process steps are as follows:

[0027] (1) Hydrorefining process:

[0028] The hydrocracking diesel 810 from the hydrocracking unit first enters the buffer tank 21, is sent to the heat exchanger 31 through the pump 11, is mixed with the circulating hydrogen 816, is sent to the heating furnace 01 and heated to the required reaction temperature, enters the hydrogenation reactor 41 for hydrofining, and the reaction oil is heat exchanged in the hydrogenation heat exchanger 31 before entering the separation tank 22. The liquid phase oil at the bottom of the separation tank is used as the feed of the fractionation tower 51, and the gas phase at the top of the separation tank discharges the waste hydrogen 815, and part of it passes through the separator tank 25, is pressurized by the circulation machine 61, and enters the separator tank 26. After the liquid is cut by the separator tank 26, it is mixed with the raw material and enters the heating furnace, wherein the new hydrogen 811 and the circulating hydrogen are mixed in the separator tank 26 and then replenished into the system.

[0029] (2) Fractional distillation and stripping process:

[0030] The liquid phase oil at the bottom of the separation tank 22 is heat exchanged in the heat exchanger 32 and then enters the fractionation tower 51. The bottom oil of the fractionation tower 51 is heated in the reboiler 02 and then returns to the fractionation tower 51. The light components with an initial boiling point of less than 280°C are removed from the top of the fractionation tower 51. After heat exchange and cooling in the fractionation heat exchanger 32, part of the bottom oil is used as a qualified transformer oil base oil 813 or 7# industrial white oil production device. The properties of the transformer oil base oil 813 are shown in Table 3, and the properties of the 7# industrial white oil are shown in Table 5. After adding antioxidant to the transformer oil base oil produced at the bottom of the tower, qualified transformer oil products are produced. The properties of the transformer oil are shown in Table 4. The light components at the top of the distillation tower 51 are cooled by the cooler 33 and enter the top reflux tank 23. The gas phase 814 separated by the reflux tank enters the flare system, and part of the liquid phase 812 is refluxed and part is sent out of the device; nitrogen 817 is introduced into the bottom of the distillation tower to strip the transformer oil base oil produced to remove light hydrocarbon components and water vapor in the transformer oil base oil.

[0031] The main properties of the raw materials of Example 1 to Example 5 are shown in Table 1, the process conditions are shown in Table 2, the properties of the transformer oil base oil are shown in Table 3, the properties of the finished transformer oil are shown in Table 4, and the properties of the finished product 7# industrial white oil are shown in Table 5.

[0032] Table 1 Main properties of raw materials of Examples 1 to 5

[0033] Analyze Project unit Example 1 Example 2 Example 3 Example 4 Example 5 Bromine Index mgBr / 100g 484 900 580 359 273 Initial distillation point ℃ 284 288 286 289 283 Do some work ℃ 362 368 365 364 368 Flash point ℃ ＞142 ＞142 ＞142 ＞142 ＞141

[0034] Table 2 Process operating conditions and target product yields of Examples 1 to 5

[0035]

[0036]

[0037] Table 3 Main properties of transformer oil base oil of Example 1 to Example 5

[0038] Analyze Project unit Example 1 Example 2 Example 3 Example 4 Example 5 Bromine Index mgBr / 100g 180 135 38 65 55 Initial distillation point ℃ 285 285 288 285 283 Do some work ℃ 362 363 364 364 367 Flash point ℃ 142 142 142 141 137

[0039] Table 4 Main properties of transformer oil of Example 1 to Example 3

[0040]

[0041]

[0042] Table 5 Main properties of 7# industrial white oil of Example 4 to Example 5

[0043]

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the protection scope of the present invention.

Claims

1. A transformer oil production process, characterized in that: The following steps are involved: (1) Hydrorefining process: Using hydrocracked diesel as raw material, the hydrocracked diesel is sent to the hydrogenation reaction unit, after heat exchange and temperature increase, it is mixed with circulating hydrogen and sent to the heating furnace, after heating in the heating furnace, it is sent to the hydrogenation reactor for hydrorefining to obtain hydrogenated oil; (2) Fractional distillation and stripping process: The hydrogenated oil is sent to the fractionation unit, and after heat exchange and temperature increase, it enters the fractionation tower for vacuum fractionation. The transformer oil base oil is produced at the bottom of the tower. After adding antioxidants, qualified transformer oil products are produced. Hydrocracked diesel is diesel produced by hydrocracking of atmospheric and vacuum wax oil as raw material. The bromine index of hydrocracked diesel is 480-900 mgBr / 100g, the initial distillation point is 280-290℃, the dry point is 360-370℃, and the flash point is greater than 141℃. The inlet temperature of the hydrogenation reactor is 170-280°C, the total temperature rise of the bed is ≯50°C, the reaction pressure is 2.3-3.1MPa, and the hydrogen-to-oil ratio is 284-426; The bottom of the distillation tower is heated by a heater to control the bottom temperature ≯320℃ and the top pressure ≯0.1MPa; Inert gas is introduced into the bottom of the distillation tower to strip the transformer oil base oil produced, thereby removing light hydrocarbon components and water vapor in the transformer oil base oil.

2. A transformer oil production process according to claim 1, characterized in that: The inert gas is nitrogen.

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