Method for producing transformer base oil by hydrocracking of mixed wax oil

Abstract

This invention discloses a method for producing transformer base oil through hydrocracking of mixed wax oil, belonging to the field of petrochemical technology. The method involves passing wax oil through a first-stage hydrorefining / cracking reactor and a second-stage cracking reactor. The reaction products are separated to obtain cold low-grade oil and hot low-grade oil, which are then desulfurized in a stripping tower. The bottom oil of the stripping tower is heated in a fractionation heater and then enters an atmospheric distillation tower. Through process optimization, the diesel side stream is extracted to produce 0°C transformer oil. After adding an anti-gelling agent, its pour point is reduced to -15°C, yielding transformer base oil. The flash point, breakdown voltage, pour point, and interfacial tension all meet the performance indicators for transformer oil, thus achieving the goal of converting diesel products into transformer base oil, eliminating diesel production, and improving the overall economic efficiency of the plant.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical technology, specifically relating to a method for producing transformer base oil by hydrocracking of mixed wax oil. Background Technology

[0002] The mixed wax oil hydrocracking unit uses wax oil from the second and third vacuum distillation units of the atmospheric and vacuum distillation unit, deasphalted oil from the solvent deasphalting unit, and vacuum wax oil from the residue hydrocracking unit as feedstock to produce high-quality products such as light and heavy naphtha, light fuels, diesel, and hydrotreated tail oil. Naphtha and tail oil are high-quality chemical and marine fuels, while light fuels and diesel are clean fuels. However, due to changes in oil consumption patterns, diesel consumption growth has slowed significantly, leading to decreased economic benefits. Therefore, producing high-value-added products to improve refining efficiency has become urgent. With the development of power infrastructure, the demand for electrical equipment has increased unprecedentedly, and the market demand for transformer oil is rising daily. No research has been reported on the production of transformer oil base oil based on the original design of producing diesel components in the fractionation system through process adjustments. Summary of the Invention

[0003] Therefore, the purpose of this invention is to provide a method for producing transformer base oil through hydrocracking of mixed wax oil. This invention starts with an analysis of the properties of diesel products, exploring suitable ways to upgrade diesel products into more economically efficient transformer oil products. Based on the original design of the fractionation system for producing diesel components, the process is adjusted to produce 10℃ transformer oil (general purpose) base oil. To ensure that the water content meets the standards, breaking with traditional thinking, the 1.0MPa stripping steam in the diesel stripping tower is replaced with 0.6MPa nitrogen stripping. The water content of the transformer oil decreases from approximately 100ppm to 12ppm. Performance indicators such as flash point, breakdown voltage, pour point, and interfacial tension all meet the transformer oil specifications, thereby achieving the goal of converting diesel products into transformer oil base oil, eliminating diesel production, and improving the overall economic efficiency of the plant.

[0004] The objective of this invention is achieved through the following means:

[0005] This invention provides a method for producing transformer base oil by hydrocracking mixed wax oil, comprising the following steps:

[0006] (1) The wax oil from the second and third reduction lines of the atmospheric and vacuum distillation unit, the wax oil from the residue hydrocracking unit, and the deasphalted oil from the solvent deasphalting unit are sequentially passed through a first-stage hydrorefining / cracking reactor and a second-stage cracking reactor. The reaction products are separated to obtain cold low-grade oil and hot low-grade oil.

[0007] (2) The cold low-temperature oil and hot low-temperature oil obtained in step (1) are respectively fed into the stripping tower from the 4th to 6th trays and the 8th to 10th trays of the stripping tower for desulfurization. 2.2 MPa stripping steam is introduced into the bottom of the stripping tower at a rate of 10.6 t / h. The bottom oil of the stripping tower is heated by a fractionation heater and then enters the atmospheric distillation tower. The top pressure of the atmospheric distillation tower is 0.08 MPa. 0.45 MPa stripping steam is introduced into the bottom of the atmospheric distillation tower at a rate of 12.5 t / h. Trays 25-27, 43-45, and 54-56 are connected to the kerosene side-stream tower, diesel side-stream tower, and vaporized oil side-stream tower via pipelines, respectively. Diesel flowing from trays 43-45 is pumped back to the atmospheric distillation tower at a cold return flow rate of 230-235 t / h. 0.45 MPa stripping steam is introduced to the bottom of the vaporized oil side-stream tower at a flow rate of 1.8 t / h. Nitrogen stripping gas is introduced to the bottom of the diesel side-stream tower at a flow rate of 2680 Nm³. 3 The bottom of the kerosene side-stream tower is heated by a heat exchanger. The top materials of the kerosene side-stream tower, diesel side-stream tower, and gasified oil side-stream tower are returned to the atmospheric tower through pipelines from the 22nd-24th, 40th-42nd, and 51st-53rd trays of the atmospheric tower, respectively. The reflux rate of the diesel side-stream tower is 185-190 t / h, and the kerosene heat reflux rate is 180-185 t / h. The bottom materials of the kerosene side-stream tower and diesel side-stream tower are sent out by external devices, and the diesel side-stream extraction temperature is controlled at 275-280℃.

[0008] (3) The transformer oil extracted from the diesel side line is 0℃ transformer oil. After adding an anti-condensing agent, its pour point reaches -15℃, thus obtaining transformer base oil.

[0009] Based on the above technical solution, further, the mass ratio of wax oil from the atmospheric and vacuum distillation unit's second and third vacuum distillation units, wax oil from the residue hydrocracking unit, and deasphalted oil from the solvent deasphalting unit in step (1) is 40-44%: 30-34%: 23-25%.

[0010] Based on the above technical solution, further, the first-stage hydrorefining / cracking reactor in step (1) is composed of a hydrorefining bed and two cracking beds connected in series, and the second-stage cracking reactor is composed of three cracking beds connected in series.

[0011] Based on the above technical solution, in step (2), the cold low-temperature oil and the hot low-temperature oil enter the stripping tower from the 5th and 9th trays of the stripping tower, respectively, for desulfurization. The stripping tower has a total of 33 trays.

[0012] Based on the above technical solution, further, in step (2), the atmospheric pressure tower has a total of 56 tower plates.

[0013] Based on the above technical solution, further, in step (2), crude naphtha is separated from the first layer of the atmospheric pressure tower.

[0014] Based on the above technical solution, further, in step (2), the 26th, 44th and 55th trays of the atmospheric pressure tower are connected to the kerosene side line tower, the diesel side line tower and the gasified oil side line tower through pipelines, respectively.

[0015] Based on the above technical solution, further, in step (2), the top materials of the kerosene side-line tower, diesel side-line tower, and gasified oil side-line tower are returned to the atmospheric pressure tower from the 23rd, 41st, and 52nd tower plates of the atmospheric pressure tower through pipelines.

[0016] Based on the above technical solution, further, in step (2), the gasified oil in the gasified oil side tower and the unconverted oil at the bottom of the tower are returned to the second-stage cracking reactor.

[0017] Based on the above technical solution, further, the initial boiling point of the 0℃ transformer oil mentioned in step (3) is 260-265℃, the flash point is 135-140℃, and the final boiling point is 365-370℃.

[0018] Based on the above technical solution, further, the main component of the anticoagulant mentioned in step (3) is ethylene-vinyl acetate copolymer.

[0019] The advantages of this invention over the prior art are as follows:

[0020] This invention adjusts the relevant parameters of the fractionation tower to re-cut the reaction products, transforming the original diesel fuel components into transformer oil base oil. The added value of transformer oil is 1,000 yuan / ton higher than that of diesel fuel. In the context of diesel overproduction, a significant slowdown in diesel consumption growth, and declining economic benefits, this invention explores a way to produce high-value-added transformer oil, which can increase the company's revenue by 350 million yuan / year and greatly improve the overall economic benefits of the plant. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0022] Figure 1 This is a schematic diagram of the fractionation process of the reaction products after hydrocracking of the mixed wax oil in Comparative Example 1.

[0023] Figure 2 This is a schematic diagram of the fractionation process of the reaction products after hydrocracking of mixed wax oil in Example 1. Detailed Implementation

[0024] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0025] Comparative Example 1

[0026] The mixed wax oil hydrocracking unit uses wax oil from the second and third vacuum distillation units, wax oil from the residue hydrocracking unit, and deasphalted oil from the solvent deasphalting unit as feedstock. The designed processing ratio is 42.11%:32.29%:25.6%. The feedstock passes sequentially through a first-stage hydrorefining / cracking reactor and a second-stage cracking reactor. The first-stage hydrorefining / cracking reactor consists of one hydrorefining bed and two cracking beds connected in series, while the second-stage cracking reactor consists of three cracking beds connected in series. The reaction products are separated to obtain cold low-molecular-weight compounds. Oil and hot low-temperature fractionated oil, cold low-temperature fractionated oil and hot low-temperature fractionated oil enter the stripping tower (33 trays in total) for desulfurization from the 5th and 9th trays of the stripping tower, respectively. Stripping steam at 2.2 MPa is introduced to the bottom of the stripping tower at a rate of 12 t / h. The bottom oil of the stripping tower is heated by a fractionation heater and then enters the atmospheric distillation tower (56 trays in total). The top pressure of the atmospheric distillation tower is 0.10 MPa. Stripping steam at 0.45 MPa is introduced to the bottom of the atmospheric distillation tower at a rate of 16.3 t / h. Crude naphtha is separated from the top of the atmospheric distillation tower. The first tray), the 26th, 44th, and 55th trays of the atmospheric distillation tower are connected to the kerosene side-stream tower, diesel side-stream tower, and vaporized oil side-stream tower via pipelines, respectively. Diesel flowing out of the 44th tray is pumped back to the atmospheric distillation tower, with a cold return flow rate of 260-265 t / h. 0.45 MPa stripping steam is introduced to the bottom of the vaporized oil side-stream tower at a rate of 3.3 t / h, and 1 MPa stripping steam is introduced to the bottom of the diesel side-stream tower at a rate of 2.5 t / h. The kerosene side-stream tower... The bottom is heated by a heat exchanger. The top materials of the kerosene side-stream tower, diesel side-stream tower, and gasified oil side-stream tower are returned to the atmospheric tower through pipelines from the 23rd, 41st, and 52nd trays of the atmospheric tower, respectively. The reflux rate of the diesel side-stream tower is 220-225 t / h, and the kerosene heat reflux rate is 270-280 t / h. The diesel side-stream extraction temperature is 255-260℃. The bottom materials of the kerosene and diesel side-stream towers are sent out by an external device, and the gasified oil and unconverted oil at the bottom of the tower are returned to the second-stage cracking reactor.

[0027] Table 1. Properties of a Section of Feed Oil

[0028] project A section of raw oil <![CDATA[Density (20 °C) kg / m 3 > 932 Sulfur content % (m / m) 1.88 Nitrogen content (mg / kg) 2700 Residual carbon % (m / m) 1.74 C7 asphaltene mg / kg 300 <![CDATA[Kinematic viscosity (100 °C) mm 2 / s]]> 11.7 Initial boiling point ℃ 260 Final boiling point (°C) 710

[0029] Table 2. Reaction conditions for refining and cracking

[0030] project A refined A stage of cracking Two-stage cracking Reaction pressure (MPa) 18.3 17.5 17.0 Reaction temperature ℃ 400 401 375 Hydrogen-to-oil ratio 750 1300 1400 Feed rate t / h 490 490 290

[0031] Table 3. Performance of the prepared diesel products

[0032] project diesel fuel <![CDATA[Density (20 °C) kg / m 3 > 840 Initial boiling point ℃ 245 Final boiling point (°C) 350 Sulfur content (mg / kg) <3.2 Flash point (closed cup) ℃ 120 Copper sheet corrosion (50℃, 3h) 1a Water content mg / kg 103

[0033] Example 1

[0034] Based on the diesel fuel production process of Example 1, by optimizing the fractionation tower pressure, extraction temperature, hot and cold reflux flow rate, and stripping steam quantity, 0℃ transformer oil was produced. The pour point of the 0℃ transformer base oil produced by this invention can only reach 0℃. After adding an anti-condensing agent (model: CF20, whose main component is ethylene-vinyl acetate copolymer) in the tank area, the pour point can reach -15℃, which fully meets the requirements. The specific adjustments are as follows:

[0035] I. Adjustment procedures to reduce water content:

[0036] 1. The stripping steam flow rate of the 2.2MPa stripping tower was reduced from 12t / h to 10.6t / h.

[0037] 2. The stripping steam output of the atmospheric pressure tower at 0.45 MPa was reduced from 16.3 t / h to 12.5 t / h.

[0038] 3. The stripping steam at 0.45 MPa in the vaporized oil side-line tower was reduced from 3.3 t / h to 1.8 t / h.

[0039] 4. The diesel side-stream tower's 1.0MPa stripping steam capacity of 2.5t / h will be replaced with nitrogen stripping, with a nitrogen flow rate of 2680Nm³. 3 / h.

[0040] II. Adjustment Operations to Increase Flash Point

[0041] 1. The pressure at the top of the atmospheric pressure tower was reduced from 0.10 MPa to 0.08 MPa.

[0042] 2. The diesel side-stream tower reflux rate was reduced from 220-225 t / h to 185-190 t / h; the diesel cold reflux rate was reduced from 260-265 t / h to 230-235 t / h; the diesel side-stream extraction temperature was increased from 255-260℃ to 275-280℃; and the kerosene hot reflux rate was reduced from 270-280 t / h to 180-185 t / h. Through optimized operation, the initial boiling point of diesel was increased to a maximum of 260-265℃, the flash point (closed cup) was increased to 135-140℃, and the final boiling point was increased to 365-370℃, producing 0℃ transformer oil.

[0043] Table 4.1 Comparison of indicators of transformer oil base oil at 0℃ with those of transformer oil (general) in GB2536-2011

[0044] project 1 0℃ transformer oil Quality Indicators <![CDATA[Kinematic viscosity (40 °C) mm 2 / s]]> 6.1 ≤12 Pour point ℃ -15 ≤-10 Flash point (closed cup) ℃ 140 ≥135 Breakdown voltage kV 55 ≥30 Water content mg / kg 12 ≤30 Interfacial tension mN / m 49 ≥40

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing transformer base oil by hydrocracking of mixed wax oil, characterized in that, Includes the following steps: (1) The wax oil from the second and third stages of the atmospheric and vacuum distillation unit, the wax oil from the residue hydrocracking unit, and the deasphalted oil from the solvent deasphalting unit are passed sequentially through a first-stage hydrorefining / cracking reactor and a second-stage cracking reactor. The resulting reaction products are then separated to obtain cold low-grade oil and hot low-grade oil. (2) The cold low-grade oil and hot low-grade oil obtained in step (1) are respectively fed into the stripping tower from the 4th to 6th trays and the 8th to 10th trays of the stripping tower for desulfurization. 2.2 MPa stripping steam is introduced into the bottom of the stripping tower at a rate of 10.6 t / h. The bottom oil of the stripping tower is heated by a fractionation heater and then enters the atmospheric distillation tower. The top pressure of the atmospheric distillation tower is 0.08 MPa. 0.45 MPa stripping steam is introduced into the bottom of the atmospheric distillation tower at a rate of 12.5 t / h. The 25th tray of the atmospheric distillation tower... Trays 27-27, 43-45, and 54-56 are connected to the kerosene sidestream tower, diesel sidestream tower, and supervaporized oil sidestream tower via pipelines, respectively. Diesel flowing from trays 43-45 is pumped back to the atmospheric distillation tower, with a cold reflux flow rate of 230-235 t / h. 0.45 MPa stripping steam is introduced to the bottom of the supervaporized oil sidestream tower at a rate of 1.8 t / h, while nitrogen stripping is introduced to the bottom of the diesel sidestream tower at a flow rate of 2680 Nm³. 3 / h; the bottom of the kerosene side-stream tower is heated by a heat exchanger; the top materials of the kerosene side-stream tower, diesel side-stream tower, and supervaporized oil side-stream tower are returned to the atmospheric tower from the 22nd-24th, 40th-42nd, and 51st-53rd trays of the atmospheric tower through pipelines, respectively. The reflux flow rate of the diesel side-stream tower is 185-190t / h, and the kerosene heat reflux flow rate is 180-185t / h; the bottom materials of the kerosene side-stream tower and diesel side-stream tower are sent out by external devices, and the diesel side-stream extraction temperature is controlled at 275-280℃; (3) Extract transformer oil with a pour point of 0℃ from the diesel side line, add anti-condensing agent to make its pour point reach -15℃, and obtain transformer base oil; The mass ratio of wax oil from the atmospheric and vacuum distillation unit's second and third vacuum distillation lines, wax oil from the residue hydrocracking unit, and deasphalted oil from the solvent deasphalting unit in step (1) is 40-44%: 30-34%: 23-25%. The first-stage hydrorefining / cracking reactor described in step (1) consists of one hydrorefining bed and two cracking beds connected in series, while the second-stage cracking reactor consists of three cracking beds connected in series. The initial boiling point of the 0℃ transformer oil mentioned in step (3) is 260-265℃, the flash point is 135-140℃, and the final boiling point is 365-370℃; The main component of the anticoagulant mentioned in step (3) is ethylene-vinyl acetate copolymer.

2. The method according to claim 1, characterized in that, In step (2), the cold low-temperature oil and the hot low-temperature oil enter the stripping tower from the 5th and 9th trays of the stripping tower, respectively, for desulfurization. The stripping tower has a total of 33 trays.

3. The method according to claim 1, characterized in that, In step (2), the atmospheric tower has a total of 56 trays; crude naphtha is separated from the first tray at the top of the atmospheric tower.

4. The method according to claim 1, characterized in that, In step (2), the 26th, 44th, and 55th trays of the atmospheric pressure tower are connected to the kerosene side line tower, diesel side line tower, and vaporized oil side line tower through pipelines, respectively.

5. The method according to claim 1, characterized in that, In step (2), the top materials of the kerosene side-line tower, diesel side-line tower, and supervaporized oil side-line tower are returned to the atmospheric tower through pipelines from the 23rd, 41st, and 52nd trays of the atmospheric tower, respectively.

6. The method according to claim 1, characterized in that, In step (2), the supervaporized oil and unconverted oil at the bottom of the supervaporized oil side column are returned to the second-stage cracking reactor.

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