A hydrogenation method for producing industrial white oil

Abstract

The invention discloses a hydrogenation method for producing industrial white oil. Paraffin-based, intermediate-based or cycloalkyl straight-run diesel is used as raw material, and firstly hydrofining / hydrodecondensation reaction is carried out; the effluent of the hydrofining / hydrodecondensation reaction is stripped with medium-pressure hydrogen to remove impurities such as H2S and NH3 that affect the precious metal catalyst, and then enters the supplementary refining reaction zone to reduce the pour point and aromatic content of the oil product and improve the color. The method of the invention can obtain high-quality Class II industrial white oil, while producing a small amount of light white oil as a by-product, and greatly reduces the energy consumption caused by the two-stage method of boosting-depressurization-boosting, heating-cooling-heating, and the process is simple and occupies less space.

Description

Technical Field

[0001] The present invention relates to a hydrogenation method for producing industrial white oil, specifically, a method for producing Class II industrial white oil that meets the NB / SH / T 0006-2017 standard by using paraffin-based, intermediate-based or naphthenic straight-run diesel as raw materials and adopting a medium-pressure two-stage hydrogenation process of hydrofining / hydrodecondensation-precious metal supplementary refining. Background Art

[0002] White oil is a colorless, tasteless, odorless and non-corrosive special mineral oil that has been ultra-deeply refined (removing impurities such as sulfur, nitrogen and aromatics). White oil is basically composed of saturated hydrocarbons and belongs to the lubricating oil fraction. It has good chemical inertness and excellent light and heat stability. White oil is widely used in daily chemical industry, pharmaceutical production, food processing, fiber and textile, polystyrene resin, petrochemical industry, plastic and rubber processing, leather processing, instrumentation and electricity, agriculture and other fields.

[0003] There are two main production processes for white oil: sulfonation and hydrogenation. At the end of the 19th century, foreign countries began to produce white oil using concentrated sulfuric acid or oleum sulfonation. The white oil produced by this method was unstable in quality, low in yield, large in raw material loss, large in acid consumption, and difficult to handle in large amounts of acid residue, causing serious environmental pollution. Later, the sulfur trioxide sulfonation process emerged, which greatly reduced acid consumption and increased white oil yield, but the environmental pollution problem was still not solved.

[0004] Since the 1960s, hydrogenation refining technology has been applied to the production process of white oil. Since hydrogenation can remove trace amounts of sulfur, nitrogen and oxygen in oil, and convert aromatics into cycloalkanes, making them white oil components, the yield of white oil products is high, thus improving the yield and eliminating the generation of three wastes. At present, white oil produced by hydrogenation at home and abroad accounts for more than 90% of the total white oil.

[0005] Depending on the different raw materials and product requirements, one-stage hydrogenation or multi-stage hydrogenation is used. Hydrocracked diesel or tail oil with low sulfur and nitrogen content, generally with an aromatic content of less than 5%, can be hydrogenated to obtain industrial grade white oil or even food and pharmaceutical grade white oil. Straight-run diesel with high sulfur and nitrogen content, with an aromatic content of up to 10% to 20%, generally requires two-stage hydrogenation to obtain Class II industrial white oil that meets the NB / SH / T 0006-2017 standard.

[0006] In recent years, diesel sales have been difficult. Considering the material balance of the whole plant, it is very difficult to simply reduce the diesel production. Using the existing medium-pressure diesel hydrogenation unit and using one or two-stage precious metal catalysts to produce industrial white oil is a good choice, but it is also affected by the existing layout of the unit and difficult to transform. At the same time, for most straight-run diesel, the production of industrial white oil through the existing process still has the problem of product pour point: for the No. 5 industrial white oil in the range of 270~350℃, the pour point is mostly above 0℃, and there is also a problem of pour point reduction.

[0007] CN201310540349.X discloses a method for producing special lubricating base oil. After the wax oil raw material is mixed with hydrogen, it passes through at least two serially connected hydrogenation reaction zones in sequence. According to the material flow direction, each hydrogenation reaction zone includes a hydrodecondensation catalyst bed and a refined decondensation catalyst composite bed filled with a hydrodecondensation catalyst and a hydrorefining catalyst. The reaction effluent obtained from the last hydrogenation reaction zone is separated and fractionated to obtain lubricating base oil, white oil and other products. The inventive method reasonably combines and utilizes the temperature drop in the hydrodecondensation process and the temperature rise in the hydrogenation process. While producing low-condensation-point lubricating base oil, it reduces the hot spot temperature of the device and prolongs the operation cycle. However, there are also problems such as high operating pressure, high energy consumption, and inability to use existing devices for transformation. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a hydrogenation method for producing industrial white oil. Specifically, a method for producing Class II industrial white oil that meets the NB / SH / T 0006-2017 standard by using paraffin-based, intermediate-based or cycloalkyl straight-run diesel as raw materials and adopting a medium-pressure two-stage hydrogenation process of hydrofining / hydrodecondensation-precious metal supplementary refining.

[0009] A hydrogenation method for producing industrial white oil of the present invention comprises the following contents:

[0010] (1) Paraffin-based, intermediate-based or cycloalkyl straight-run diesel is mixed with hydrogen and enters the hydrotreating / hydrodecondensation reaction zone, where it is sequentially contacted with the hydrotreating catalyst, the hydrotreating catalyst and the hydrodecondensation catalyst for reaction. The hydrotreating catalyst removes impurities such as sulfur, nitrogen and oxygen from the feedstock and saturates some aromatics. The hydrodecondensation catalyst selectively cracks the straight-chain alkanes that have the greatest impact on the pour point of the product.

[0011] (2) The hydrotreating / hydrodecondensing effluent obtained in step (1) enters a medium-pressure stripping tower from the top, hydrogen is injected into the bottom of the tower as a stripping medium, and bottom oil from which H2S and NH3 are removed is obtained at the bottom of the tower, and a gas effluent containing H2S, NH3, hydrogen and part of light oil is obtained at the top of the tower;

[0012] (3) The effluent obtained from the top of step (2) containing H2S, NH3, hydrogen and part of the light oil enters a cold high-pressure separator for gas-liquid separation after heat exchange, and the obtained cold high-fraction oil containing H2S and NH3 enters a cold low-fraction separator to separate the low-fraction gas, and the cold low-fraction oil enters a H2S removal stripping tower to remove H2S and NH3, and enters a supplementary refining reactor after pressure increase and heat exchange;

[0013] (4) the medium-pressure stripping tower bottom oil obtained in step (2) is mixed with hydrogen and then enters the supplementary refining reactor together with the cold low-fraction oil from which H2S and NH3 are removed in step (3) to contact with the reduced supplementary refining catalyst;

[0014] (5) The reaction effluent obtained in step (4) enters a fractionation system to obtain Class II industrial white oil that meets the NB / SH / T 0006-2017 standard and a small amount of a series of light white oils that meet the technical index requirements of light white oil (II) in NB / SH / T 0913-2015.

[0015] Furthermore, the straight-run diesel can be at least one of a paraffin-based, intermediate-based or naphthenic diesel fraction, a coal tar diesel fraction or a catalytic cracking diesel fraction. The aromatic content of straight-run diesel is generally 1 to 99 wt%, and the density at 20°C is generally 0.825 to 0.915 g / cm 3 The distillation range of the straight-run diesel can be any range consisting of any two values ​​within the range of 140 to 400°C. Preferably, the initial distillation point of the straight-run diesel is 160 to 200°C, and the final distillation point is 300 to 400°C.

[0016] Furthermore, the hydrorefining catalyst described in step (1) is a conventional hydrorefining catalyst in the art, such as a diesel hydrorefining catalyst or a hydrocracking pretreatment catalyst. Hydrorefining catalysts generally use Group VIB and / or Group VIII metals as active components and use alumina or silicon-containing alumina as a carrier. Group VIB metals are generally Mo and / or W, and Group VIII metals are generally Co and / or Ni. Based on the weight of the catalyst, the content of Group VIB metals as oxides is 10wt% to 50wt%, and the content of Group VIII metals as oxides is 3 to 15wt%; its properties are as follows: specific surface area is 100 to 350m 2 / g, pore volume is 0.15~0.6mL / g. Commercial hydrotreating catalysts that can be selected include 3FF-26, FF-36, FF-46, FF-56, FF-66, FHUDS-2, FHUDS-5 and other hydrotreating catalysts developed by Fushun Petrochemical Research Institute of Sinopec. It can also be a catalyst with similar functions developed by foreign catalyst companies, such as HC-K and HC-P catalysts of UOP, TK-555 and TK-565 catalysts of Topsoe, and KF-847 and KF-848 of AKZO.

[0017] Further, the hydrodegassing catalyst can be selected from the commonly used lubricating oil hydrodegassing catalyst in the art, which can be a commercial hydrodegassing catalyst, such as 3881 and FDW-3 catalysts developed by Sinopec Fushun Petrochemical Research Institute, or can be prepared according to general knowledge in the art. The hydrodegassing catalyst contains ZSM-5 molecular sieve. Based on the weight of the hydrodegassing catalyst, the content of ZSM-5 molecular sieve is 50wt%~85wt%, NiO and / or CoO is 1.0 wt%~8.0 wt%, and the rest is a binder.

[0018] Furthermore, in step (2), the medium-pressure stripping tower is filled with fillers, such as rolled hole θ ring fillers, and the selection of the fillers is common knowledge for those skilled in the art. Preferably, a ZnO bed is also provided at the lower part of the filler zone, and the ZnO bed can be used to remove a small amount of H2S that is not stripped cleanly due to operation fluctuations. The operating conditions of the medium-pressure stripping tower are well known to those skilled in the art. For example, the stripping conditions include: a stripping temperature of 150 to 400°C, preferably the outlet temperature of the hydrofining reaction zone, a stripping pressure that is the same as the pressure of the hydrofining reaction zone, and a hydrogen consumption that is higher than the chemical hydrogen consumption of the hydrofining reaction zone, preferably equivalent to the sum of the chemical hydrogen consumption of the hydrofining and the dissolved hydrogen of the hydrofining system.

[0019] Furthermore, the cooled high-pressure separated gas phase in step (2) is selectively desulfurized and then re-enters the hydrotreating reactor as circulating hydrogen.

[0020] Furthermore, the supplementary refining catalyst is a conventional reduced hydrogenation refining catalyst, and its active metal is one or both of Pt and Pd, or the active metal is reduced nickel. The weight content of the active metal in the precious metal catalyst is generally 0.05% to 1%; the weight content of the active metal in the reduced nickel catalyst is 30% to 80% in terms of oxide. The catalyst carrier is generally Al2O3 or Al2O3-SiO2, and may also contain one or more of P, Ti, B, Zr, etc. as an additive. The supplementary refining catalyst usually needs to be conventionally reduced before use to ensure that the hydrogenation active metal is in a reduced state during the reaction. The supplementary refining catalyst can be selected from ordinary commercial catalysts in this field, or prepared according to ordinary methods in this field.

[0021] Furthermore, the operating conditions of the hydrofining / hydrodecondensation reaction zone are: hydrogen partial pressure 5.0-18.0 MPa, preferably 5.0-10.0 MPa; reaction temperature 230-430°C, preferably 300-410°C; hydrogen-to-oil volume ratio 200-1500, preferably 500:1-1000:1; volume space velocity 0.1-10.0 h -1 , preferably 0.3 h -1 ~1.0h -1 In the hydrofining / hydrodecondensation reaction zone, the loading ratio of the hydrofining catalyst to the hydrodecondensation catalyst is generally 1:9 to 9:1, preferably 2:8 to 8:2.

[0022] Furthermore, the reaction conditions of the supplementary refining reaction zone are: reaction temperature is 100°C to 300°C, preferably 150°C to 250°C, hydrogen partial pressure is 3.0MPa to 18.0MPa, preferably 5.0 to 8.0MPa, volume space velocity is 0.2h -1 ~3.0h -1 , preferably 0.3h -1 ~0.8h -1 , the volume ratio of hydrogen to oil is 400:1 to 1500:1, preferably 400:1 to 600:1.

[0023] Compared with the prior art, the method of the present invention has the following advantages:

[0024] 1. The present invention adopts a medium-pressure two-stage hydrogenation process of hydrofining / hydrodecondensation-medium-pressure hydrogen stripping-supplementary refining to produce industrial white oil, which avoids the need to set up two sets of fractionation systems in the traditional two-stage hydrogenation process to avoid the influence of H2S and NH3 on the precious metal catalyst. At the same time, most of the reaction feed (~80w%) of the hydrogenation method of the present invention is a one-time pressure-increasing process, which avoids the process of pressure-increasing, pressure-reducing, and re-pressurizing of all raw oil between the two reaction zones of the traditional two-stage process device, reducing power consumption; at the same time, the stripping hydrogen injected at the bottom of the medium-pressure stripping tower enters the circulating hydrogen system of the hydrofining device as part of the supplementary hydrogen. By adjusting the operating temperature of the medium-pressure hydrogen stripping tower, the bottom effluent of the stripping tower can be directly used as a raw material to enter the supplementary refining reactor without the need to set up a supplementary refining feed heating furnace, and also avoids the energy loss in the process of heating, cooling, and re-heating of all reaction products in the traditional two-stage process, saving power consumption and fuel gas consumption, while saving land.

[0025] 2. The top effluent of the medium-pressure stripping tower enters the cold high-pressure separator after heat exchange. After separating the gas phase circulating hydrogen, the cold high-fraction oil containing H2S and NH3 is depressurized and enters the cold low-pressure separator to separate the low-fraction gas. The cold low-fraction oil enters the conventional H2S removal stripping tower to further remove H2S and NH3, and then enters the supplementary refining reactor after heat exchange, thereby solving the problem of the cold high-fraction oil directly entering the distillation system and affecting the product color, aromatic content and stability, or directly leaving the device with nowhere to go. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow diagram of the method of the present invention. DETAILED DESCRIPTION

[0027] The method of the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments.

[0028] Combination Figure 1The hydrogenation method for producing industrial white oil of the present invention is as follows: straight-run diesel passes through pipeline 1, is mixed with circulating hydrogen from pipeline 2, and enters hydrofining / hydrodecondensation reaction zone 3 to undergo desulfurization, denitrogenation, catalytic dewaxing and aromatic saturation reactions; subsequently, the hydrofining / hydrodecondensation product 4 enters a medium-pressure hydrogen stripping tower 5, stripping hydrogen 6 is blown into the bottom of the tower to obtain a tower bottom oil 7 from which H2S and NH3 are removed, and the top of the medium-pressure stripping tower enters a separation system 8 of the hydrofining section, wherein the separation system 8 generally includes a high-pressure separator and a low-pressure separator; the separated gas phase is returned to the hydrofining reaction system as circulating hydrogen through pipeline 2, and the liquid phase product enters a conventional H2S removal stripping tower 10 through pipeline 9 to remove The bottom oil 11 from which H2S and NH3 have been removed is pressurized and heat exchanged, and is mixed with new hydrogen 12 and second-stage circulating hydrogen 13 to enter the supplementary refining reactor 14. The bottom oil 7 from the high-pressure stripping tower is mixed with the logistics 11 after heat exchange and directly enters the supplementary refining reactor 14 to undergo deep dearomatization reaction to reduce the aromatic content and improve the color. The supplementary refined product 15 enters the separation system 16, which generally includes a high-pressure separator and a low-pressure separator. The low-pressure oil enters the fractionation system 17, which includes a normal-pressure fractionation tower and a vacuum fractionation tower to obtain light naphtha 18, light white oil 19 that meets the requirements of NB / SH / T0913-2015, and industrial white oil product 20 that meets the requirements of NB / SH / T 0006-2017.

[0029] The following examples will further illustrate the method provided by the present invention, but the scope of the present invention is not limited thereby. The properties of the raw materials treated by the present invention are shown in Table 1, and the physical and chemical properties of the catalyst used are shown in Table 2.

[0030] Table 1 Raw material properties

[0031]

[0032] Table 2 Catalyst

[0033]

[0034] Example 1

[0035] use Figure 1 The process is shown. The raw material is the straight-run diesel 1 listed in Table 1, and the physicochemical properties of the catalyst are shown in Table 2. The hydrotreating / hydrodecondensation reaction zone is filled with a hydrogenation protective agent, a hydrotreating catalyst, and a hydrodecondensation catalyst, and the filling ratio is a hydrogenation protective agent: a hydrogenation main agent = 1:9 (volume). The process conditions and test results are shown in Tables 3~4.

[0036] Example 2

[0037] use Figure 1The process is shown. The raw material is the straight-run diesel 2 listed in Table 1, and the physicochemical properties of the catalyst are shown in Table 2. The hydrotreating / hydrodecondensation reaction zone is filled with a hydrogenation protective agent, a hydrotreating catalyst, and a hydrodecondensation catalyst, and the filling ratio is a hydrogenation protective agent: a hydrogenation main agent = 1:9 (volume). The process conditions and test results are shown in Tables 3~4.

[0038] Comparative Example 1

[0039] The traditional two-stage hydrogenation process is adopted. The process flow is as follows: the hydrorefining-hydrogenation condensation product first enters the hot high-pressure separator, and then enters the cold high-pressure separator after gas phase heat exchange. The cold high-fraction gas phase enters the circulating hydrogen system, and the cold high-fraction oil enters the cold low-fraction after decompression, and the top of the separator is the low-fraction gas; the hot high-fraction oil enters the hot low-fraction after decompression, and the top is the low-fraction gas; the hot low-fraction oil (most of the product) and the cold low-fraction oil are mixed and then all enter the dehydrogen sulfide stripping tower (pressure is about 1MPa), and a small amount of hydrogen sulfide gasoline is discharged from the top of the tower and all the bottom liquid (sulfur content <10µg.g -1 , nitrogen content <2µg.g -1 ) After being heated and pressurized, it enters the second supplementary refining section; the supplementary refined products are subjected to gas-liquid separation and fractionation to obtain various products.

[0040] Comparative Example 1 uses the same raw materials and the same catalyst as Example 1. The process conditions and test results are shown in Table 3-4.

[0041] Comparative Example 2

[0042] The conventional two-stage process was adopted, and the process flow was the same as that of Comparative Example 1. Comparative Example 2 used the same raw materials and the same catalyst as those in Example 2. The process conditions and test results are shown in Table 3-4.

[0043] Table 3 Process conditions

[0044]

[0045] *, for fresh feed.

[0046] Table 4 Test results

[0047]

[0048] **, for fresh feed.

[0049] From the data in Table 3-4, it can be seen that with straight-run diesel as raw material, the two-stage process of hydrofining / hydrodecondensation-medium-pressure hydrogen stripping-supplementary refining can produce products of the same quality as the conventional two-stage process of hydrofining-hydrodecondensation / supplementary refining, while avoiding the energy consumption of the conventional two-stage process of all feed pressure-boosting-pressure-lowering-pressure-boosting, temperature-lowering-temperature-highering, reducing the footprint of the device and reducing the energy consumption of the device by about 10%. In addition, since only the cold high-fraction oil enters the supplementary refining reactor after conventional stripping, the loss of light oil at the top of the tower caused by the entire hydrofining liquid phase entering the H2S removal stripping tower in the conventional two-stage process is greatly reduced, and the total liquid yield and the yield of the target product are improved. At the same time, the process of the present invention is also conducive to the transformation of refineries using existing equipment, and at least two medium-pressure hydrogenation reactors are required, with one bed layer in each reactor.

Claims

1. A hydrogenation method for producing industrial white oil, comprising the following contents: (1) Paraffin-based, intermediate-based or cycloalkyl straight-run diesel is mixed with hydrogen and enters the hydrotreating / hydrodecondensation reaction zone, where it sequentially contacts with the hydroprotection catalyst, the hydrotreating catalyst and the hydrodecondensation catalyst for reaction; (2) The reaction effluent obtained in step (1) enters a medium-pressure stripping tower from the top, hydrogen is injected into the bottom of the tower as a stripping medium, and bottom oil from which H2S and NH3 are removed is obtained at the bottom of the tower, and a gas effluent containing H2S, NH3, hydrogen and part of light oil is obtained at the top of the tower; (3) The effluent from the top of step (2) containing H2S, NH3, hydrogen and part of the light oil enters a cold high-pressure separator for gas-liquid separation after heat exchange, and the obtained cold high-fraction oil containing H2S and NH3 enters a cold low-fraction to separate the low-fraction gas, and then the cold low-fraction oil enters a H2S removal stripping tower to remove H2S and NH3, and enters a supplementary refining reactor after pressure increase and heat exchange; (4) the medium-pressure stripping tower bottom oil obtained in step (2) is mixed with hydrogen and then enters the supplementary refining reactor together with the cold low-fraction oil from which H2S and NH3 are removed in step (3) to contact with the reduced supplementary refining catalyst; (5) The reaction effluent obtained in step (4) enters a fractionation system to obtain Class II industrial white oil that meets the NB / SH / T 0006-2017 standard and a small amount of a series of light white oils that meet the technical index requirements of light white oil (II) in NB / SH / T 0913-2015; in, The stripping pressure of the medium-pressure stripping tower is the same as the pressure of the hydrofining / hydrodecondensation reaction zone. The reaction pressure of the hydrofining / hydrodecondensation reaction zone is 5.0-18.0 MPa in terms of hydrogen partial pressure.

2. The hydrogenation method according to claim 1, characterized in that: The initial distillation point of the straight-run diesel is 160-200°C, and the final distillation point is 300-400°C.

3. The hydrogenation method according to claim 2, characterized in that: The straight-run diesel has an aromatic content of 1 to 99 wt% and a density of 0.825 to 0.915 g / cm2 at 20°C. 3 .

4. The hydrogenation method according to claim 1, characterized in that: The hydrotreating catalyst has Group VIB and / or Group VIII metals as active components and alumina or silicon-containing alumina as a carrier; based on the weight of the catalyst, the content of Group VIB metals as oxides is 10wt% to 50wt%, and the content of Group VIII metals as oxides is 3 to 15wt%.

5. The hydrogenation method according to claim 1, characterized in that: The hydrodegassing catalyst contains ZSM-5 molecular sieve; based on the weight of the hydrodegassing catalyst, the content of ZSM-5 molecular sieve is 50wt%~85wt%, NiO and / or CoO is 1.0wt%~8.0wt%, and the rest is a binder.

6. The hydrogenation method according to claim 1, characterized in that: The medium-pressure stripping tower described in step (2) is filled with fillers, and a ZnO bed layer is arranged at the lower part of the filler area.

7. The hydrogenation method according to claim 1 or 6, characterized in that: The stripping temperature of the medium-pressure stripping tower is 150-400° C., and the amount of hydrogen used is higher than the chemical hydrogen consumption in the hydrofining / hydrodecondensation reaction zone.

8. The hydrogenation method according to claim 7, characterized in that: The stripping temperature of the medium-pressure stripping tower is the outlet temperature of the hydrofining / hydrodecondensation reaction zone, and the hydrogen consumption is equivalent to the sum of the chemical hydrogen consumption of the hydrofining and the dissolved hydrogen of the hydrofining system.

9. The hydrogenation method according to claim 1, characterized in that: The supplementary refining catalyst is a reduced hydrorefining catalyst, the active metal is one or two of Pt and Pd, or reduced nickel, the catalyst carrier is Al2O3 or Al2O3-SiO2, and selectively contains one or more of P, Ti, B, and Zr as an auxiliary agent.

10. The hydrogenation method according to claim 9, characterized in that: The weight content of active metal in the noble metal catalyst is 0.05% to 1%; the weight content of active metal in the reduced nickel catalyst is 30% to 80% in terms of oxide.

11. The hydrogenation method according to claim 1, characterized in that: The operating conditions of the hydrotreating / hydrodecondensation reaction zone are: hydrogen partial pressure 5.0-18.0 MPa, reaction temperature 230-430°C, hydrogen-to-oil volume ratio 200-1500, volume space velocity 0.1-10.0 h -1 .

12. The hydrogenation method according to claim 11, characterized in that: The operating conditions of the hydrotreating / hydrodecondensation reaction zone are: hydrogen partial pressure 5.0-10.0 MPa, reaction temperature 300°C-410°C, hydrogen-oil volume ratio 500:1-1000:1, volume space velocity 0.3 h -1 ~1.0h -1 .

13. The hydrogenation method according to claim 1, characterized in that: The loading ratio of the hydrotreating catalyst to the hydrodecondensation catalyst is 1:9~9:

1.

14. The hydrogenation method according to claim 1, characterized in that: The reaction conditions of the supplementary refining reactor are: reaction temperature of 100℃~300℃, hydrogen partial pressure of 3.0MPa~18.0MPa, volume space velocity of 0.2h -1 ~3.0h -1 , the volume ratio of hydrogen to oil is 400:1~1500:

1.

15. The hydrogenation method according to claim 14, characterized in that: The reaction conditions of the supplementary refining reactor are: reaction temperature of 150℃~250℃, hydrogen partial pressure of 5.0~8.0MPa, volume space velocity of 0.3h -1 ~0.8h -1 , hydrogen-oil volume ratio 400:1~600:1.

Images