CN109988613B

CN109988613B - Flexible diesel hydro-upgrading pour point depressing process

Info

Publication number: CN109988613B
Application number: CN201711468929.7A
Authority: CN
Inventors: 刘涛; 关明华; 李宝忠; 李扬; 张学辉; 王晶晶
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2017-12-29
Filing date: 2017-12-29
Publication date: 2021-05-04
Anticipated expiration: 2037-12-29
Also published as: CN109988613A

Abstract

The invention discloses a flexible diesel hydro-upgrading pour point depressing process. After being hydrofined, the diesel raw material enters a hydro-upgrading reactor, and the material passing through a first hydro-upgrading catalyst bed layer is divided into two parts; one strand of material is liquid obtained by separation through a gas-liquid separator, and the material is pumped out of the modification reactor and mixed with hydrogen to enter a hydrogenation pour point depression reactor for pour point depression reaction; the other material is a mixture of gas in the reactor and the liquid left after extraction, and the mixture continuously flows downwards through a second hydrogenation modification catalyst bed layer; and respectively carrying out gas-liquid separation and fractionation on the hydrogenation modified material and the hydrogenation pour point depression material to obtain diesel products with different specifications. The invention provides a hydro-upgrading process for simultaneously producing more than two diesel products with different specifications on one set of hydro-process device, which realizes the coupling operation of a hydro-dewaxing reactor and a hydro-upgrading reactor.

Description

Flexible diesel hydro-upgrading pour point depressing process

Technical Field

The invention belongs to the field of petroleum refining, and particularly relates to a diesel hydro-upgrading pour point depressing process for flexibly producing high-quality diesel products.

Background

Increasingly strict environmental regulations require higher and higher quality diesel products, mainly with greater and greater limits on sulfur content, cetane number, density and polycyclic aromatic hydrocarbon content. The inferior diesel oil hydrogenation modification technology can greatly reduce the sulfur content and the aromatic hydrocarbon content of the diesel oil product, reduce the density and improve the cetane number. In addition, in winter, diesel products in cold regions have different limits and requirements on condensation points, and diesel products in China can be divided into specifications of 5#, 0#, -10#, -20#, -35# and-50 # according to the condensation points. The pour point of the diesel can be effectively reduced by the hydrogenation pour point depressing technology.

The diesel oil fraction hydrogenation upgrading technology, such as CN1156752A and CN1289832A, is a hydrogenation process technology using a hydrofining catalyst and a Y-type molecular sieve hydrogenation upgrading catalyst. Such techniques can increase the cetane number of diesel products by more than 10 units, but the pour point of the diesel does not change much.

Diesel oil fraction hydrogenation pour point depression technology, such as CN102051232A and CN1257107A, uses hydrofining catalyst and hydrogenation pour point depression catalyst, adopts a series flow to produce low pour point diesel oil product, but the yield of the diesel oil product is lower. CN102453531A, CN103805258A, CN103805254A and the like all use hydrofining catalysts and hydrodewaxing catalysts alternately, the condensation point of the obtained diesel oil product is low, but the yield of the diesel oil is low, and only one diesel oil product can be produced.

CN1415705A which adopts a combined hydrogenation technology discloses a production method of high-quality diesel oil, raw oil is subjected to hydrorefining and hydrodewaxing and then subjected to gas-liquid separation, and a liquid product is subjected to hydrogenation dearomatization by using a noble metal catalyst.

In conclusion, the existing diesel oil hydro-upgrading technology can obtain higher diesel oil product yield, greatly improve the product quality such as cetane number, sulfur content, aromatic hydrocarbon content, density and the like, but the condensation point reduction amplitude is not large or reduced, and the requirement of low condensation point diesel oil cannot be met. The existing hydrogenation pour point depressing technology can greatly reduce the pour point of a diesel product and can meet the index requirement of low pour point diesel, but the diesel yield is lower and is usually less than 90wt%, the quality improvement range of the diesel product is not large, and the cetane number of the diesel product is reduced particularly when normal paraffin with high cetane number is cracked into gas or naphtha fraction. The combined hydrogenation technology has complex flow and single product. The diesel oil products produced by the process technology are only one, and the product flexibility is poor.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a flexible diesel hydro-upgrading pour point depressing process, namely, a part of reaction liquid material flow is extracted from a gas-liquid separator arranged in the middle of a hydro-upgrading reactor, and the high-quality hydro-upgrading diesel product and the high-quality hydro-upgrading pour point depressing diesel product are flexibly produced by the diesel raw oil through a hydro-upgrading and hydro-depressing combined method.

The method for the flexible diesel hydro-upgrading pour point depressing process comprises the following steps:

a. firstly, passing diesel raw oil through a hydrofining catalyst bed under the hydrofining condition to obtain a hydrofining material flow;

b. b, passing the hydrofined material flow obtained in the step a through a first hydro-upgrading catalyst bed under hydro-upgrading conditions to obtain a first hydro-upgrading material flow, dividing the part of the reactant material flow into two parts, passing one part of the reactant material flow through a gas-liquid separator to obtain a liquid material flow, and pumping the obtained liquid material flow out of the hydrogenation reactor;

c. b, continuously allowing the rest part of the first hydro-upgrading material flow in the step b to pass through a second hydro-upgrading catalyst bed under the hydro-upgrading condition, and separating and fractionating the hydro-upgrading material flow to obtain a hydro-upgrading high-pressure hydrogen-rich gas, a hydro-upgrading gas product, a hydro-upgrading naphtha product and a hydro-upgrading diesel product;

d. and b, mixing the first hydrogenated modified liquid material flow obtained in the step b with hydrogen, passing the mixture through a hydrogenation pour point depression catalyst bed layer of a hydrogenation pour point depression reactor under a hydrogenation pour point depression condition, and separating and fractionating the hydrogenation pour point depression material flow to obtain hydrogenation pour point depression high-pressure hydrogen-rich gas, hydrogenation pour point depression naphtha and hydrogenation pour point depression diesel oil products.

The hydro-upgrading pour point depressing process according to the invention can further comprise the following steps of e: and d, mixing the hydro-upgrading high-pressure hydrogen-rich gas obtained in the step c with the hydro-pour point depressing high-pressure hydrogen-rich gas obtained in the step d for recycling.

S, N, O and other impurities in the raw diesel oil are effectively removed through a hydrofining catalyst, aromatic hydrocarbon is subjected to hydrogenation saturation to a certain extent, partial ring opening reaction of annular hydrocarbon occurs when hydrofining material flow continuously passes through a hydrofining catalyst bed layer, a component with a low cetane number is changed into a component with a high cetane number, and a part of hydrofining material flow is continuously subjected to hydrogenation modification, so that the cetane number of the diesel oil can be improved to the maximum extent, and a diesel oil product with a relatively high condensation point and a high cetane number is obtained; and mixing a part of the extracted first hydro-upgrading liquid material flow with hydrogen, and then passing through a hydro-dewaxing catalyst to reduce the freezing point of diesel oil, so as to obtain a diesel oil product with cetane number meeting the requirement but low freezing point.

In the invention, the hydrofining catalyst bed, the first hydro-upgrading catalyst bed and the second hydro-upgrading catalyst bed can be arranged in one hydrogenation reactor, for example, three catalyst beds can be arranged in one hydro-upgrading reactor in sequence; or the hydrofining catalyst bed layer is arranged in a single hydrogenation reactor, and the first hydro-upgrading catalyst bed layer and the second hydro-upgrading catalyst bed layer are arranged in one hydro-upgrading reactor; or the hydrorefining catalyst bed layer and the first hydroupgrading catalyst bed layer are arranged in one hydroupgrading reactor, and the second hydroupgrading catalyst bed layer is arranged in the other hydroupgrading reactor.

Compared with the prior art, the flexible diesel hydro-upgrading pour point depressing process has the advantages that:

1. in the invention, the hydro-upgrading reactor comprises at least two hydro-upgrading catalyst beds. The effective distribution of the hydrogenation modified material strand can be realized by the step of extracting a part of the modified liquid material through a gas-liquid separator arranged in the middle of the bed layer of the hydrogenation modified reactor, and the obtained material is subjected to different hydrogenation processes, so that target diesel oil products with different specifications can be flexibly produced. At the same time, it is technically easy to extract the reactant stream in the middle of the reactor bed. In the prior art, a set of hydrogenation devices can only obtain diesel products with one specification; if diesel oil products with different specifications are required, more than two sets of hydrogenation devices are required. Therefore, the invention provides a hydro-conversion process for producing more than two diesel oil products with different specifications on one set of hydrogenation process device for the first time.

2. According to the invention, the gas-liquid separator is arranged in the middle of the catalyst bed layer of the hydrogenation modification reactor, the first hydrogenation modification liquid material obtained by hydrofining and hydrogenation modification of the diesel raw material is extracted out of the reactor through the gas-liquid separator and is sent into the hydrogenation pour point depression reactor which is arranged independently for hydrogenation pour point depression reaction, so that the pour point of the hydrogenation modified material is further reduced, and therefore, the method disclosed by the invention can be used for flexibly producing diesel products with different pour points and different cetane numbers.

3. In the invention, the diesel oil product obtained after hydrogenation modification has high cetane number; the diesel oil product obtained after partial hydrogenation modification and hydrogenation pour point depression has low pour point and relatively high cetane number; can respectively meet the requirements of producing high-quality diesel products with different specifications.

4. In the invention, the impurities such as S, N in the raw oil are converted into H after hydrofining and partial hydro-upgrading₂S and NH₃Most of H is separated by a gas-liquid separator₂S and NH₃Present in the gas phase, and H in the liquid phase₂S and NH₃The content of the catalyst is less, so that the inhibiting effect on the molecular sieve of the hydrogenation pour point depressing catalyst is reduced, the activity of the hydrogenation pour point depressing catalyst is improved, namely the reaction temperature required when the same pour point depressing effect is achieved is reduced, the liquid obtained in the middle of the modified catalyst bed layer of the hydrogenation modified reactor has very high temperature and pressure, although the temperature of the liquid mixed with the circulating hydrogen is slightly reduced, the liquid can still directly enter the newly-arranged hydrogenation pour point depressing reactor for reaction and achieve the pour point depressing effect, and therefore the heat carried by the part of modified materials is fully utilized, and the coupling operation of the hydrogenation pour point depressing reactor and the hydrogenation modified reactor is achieved.

Drawings

Fig. 1 is a schematic flow chart of the principle of the present invention. The configuration of a hydrorefining reactor, a hydroupgrading reactor and a hydrodewaxing reactor will be described as an example.

Wherein: 1-raw oil, 2-hydrofining reactor, 3-hydrofining material flow, 4-hydroupgrading reactor, 5-hydrodewaxing liquid raw material flow, 6-hydroupgrading material flow, 7-hydrodewaxing reactor, 8-hydroupgrading high-pressure separator, 9-hydrodewaxing high-pressure separator, 10-hydroupgrading fractionating tower, 11-hydrodewaxing fractionating tower, 12-hydroupgrading gas product, 13-hydroupgrading naphtha product, 14-hydroupgrading diesel oil product, 15-hydrodewaxing gas product, 16-hydrodewaxing naphtha product, 7-hydrodewaxing diesel oil product, 18-hydroupgrading high-pressure separator gas product, 19-hydrodewaxing high-pressure separator gas product, 20-make-up hydrogen, 21-hydrogenation upgrading recycle hydrogen, 22-hydrogenation pour point depressing recycle hydrogen and 23-gas-liquid separator.

Detailed Description

The initial boiling point of the diesel raw material in the step a is 100-260 ℃, and the final boiling point is 300-450 ℃. The diesel raw oil can be one of straight-run diesel oil, coking diesel oil, catalytic diesel oil, hydrotreated diesel oil and the like obtained by petroleum processing, one of coal tar, coal direct liquefaction oil, coal indirect liquefaction oil, shale oil and the like obtained from coal, and can also be mixed oil of a plurality of the coal tar, the coal direct liquefaction oil, the coal indirect liquefaction oil and the shale oil.

The hydrofining catalyst in the step a is a conventional diesel hydrofining catalyst. Generally, metals in a VIB group and/or a VIII group are used as active components, alumina or silicon-containing alumina is used as a carrier, the metals in the VIB group are generally Mo and/or W, and the metals in the VIII group are generally Co and/or Ni. Based on the weight of the catalyst, the content of the VIB group metal is 10-35 wt% calculated by oxide, the content of the VIII group metal is 3-15 wt% calculated by oxide, and the properties are as follows: the specific surface area is 100 to 650m²The pore volume is 0.15 to 0.6 mL/g. The main catalysts comprise hydrofining catalysts such as FH-5, FH-98, 3936 and 3996, FHUDS series and the like developed by the petrochemical research institute, and can also be similar catalysts with functions developed by foreign catalyst companies, such as HC-K, HC-P of UOP company, TK-555 and TK-565 of Topsoe company, KF-847 and KF-848 of Akzo company and the like. The operation conditions can adopt the conventional operation conditions, generally the reaction pressure is 3.0MPa to 15.0MPa, the reaction temperature is 300 ℃ to 430 ℃, and the liquid hourly volume space velocity is 0.2h^-1～6.0h^-1The volume ratio of the hydrogen to the oil is 100: 1-2000: 1.

The hydro-upgrading catalyst in the steps B and c is a conventional diesel hydro-upgrading catalyst, generally, metals in a VIB group and/or a VIII group are used as active components, the metals in the VIB group are generally Mo and/or W, and the metals in the VIII group are generally Co and/or Ni. The carrier of the catalyst is one or more of alumina, siliceous alumina and molecular sieve, preferablyThe molecular sieve is Y-type molecular sieve. Based on the weight of the catalyst, the content of the VIB group metal is 10 to 35 weight percent calculated by oxide, the content of the VIII group metal is 3 to 15 weight percent calculated by oxide, the content of the molecular sieve is 5 to 40 weight percent, the content of the alumina is 10 to 80 weight percent, and the specific surface area is 100m²/g～650m²The pore volume is 0.15mL/g to 0.50 mL/g. The main catalysts comprise 3963, FC-18, FC-32 catalysts and the like which are developed by the petrochemical research institute. For the hydrogenation modification catalyst, certain hydrogenation activity and certain cracking activity are required, and both hydrogenation saturation of olefin and aromatic hydrocarbon in diesel oil fraction and ring-opening reaction of saturated aromatic hydrocarbon are required. The operating conditions for the hydro-upgrading can be conventional and are generally: the reaction pressure is 3.0MPa to 15.0MPa, the reaction temperature is 300 ℃ to 430 ℃, and the liquid hourly volume space velocity is 0.3h^-1～15.0h^-1The volume ratio of the hydrogen to the oil is 100: 1-2000: 1.

According to a preferred embodiment of the present invention, the catalyst used in the first hydrogenation upgrading catalyst bed is hydrogenation catalyst a, and the catalyst used in the second hydrogenation upgrading catalyst bed is hydrogenation catalyst B. The content percentage x of the molecular sieve in the hydrogenation catalyst A₁Less than the percentage content x of the molecular sieve in the hydrogenation catalyst B₂Preferably x₁Ratio x₂1-6 percentage points lower, more preferably x₁Ratio x₂2-5 percentage points lower. According to the preferred embodiment, the hydro-upgrading reaction can achieve a better ring-opening effect, thereby contributing to further improvement in the cetane number of the resulting product. The reason is that after the raw oil passes through the first hydrogenation modified catalyst bed layer, one ring at the outermost layer of the polycyclic aromatic hydrocarbon is subjected to ring opening reaction after the partial polycyclic aromatic hydrocarbon is subjected to hydrofining saturation and hydrogenation modified reaction, the volume of the hydrocarbon molecules subjected to ring opening is increased, the steric hindrance is increased, and the difficulty of continuing the modification reaction is correspondingly increased, so that the content of the molecular sieve in the second hydrogenation modified catalyst (namely the catalyst B) is properly increased to improve the reaction activity of the catalyst, the subsequent ring opening reaction of the second ring can be better completed, and the cetane number of the obtained diesel oil can be increased.

And in the step b, the gas-liquid separator is a hydro-upgrading reactor or a hydro-upgrading catalyst bed or equipment arranged at the inlet of the catalyst bed. The gas-liquid separator at least comprises a reactant stream inlet, a liquid phase conduit, a gas phase conduit and the like, wherein the liquid phase obtained by separation is pumped out of the hydro-upgrading reactor through the liquid phase conduit, and the gas phase obtained by separation is introduced into the second hydro-upgrading catalyst bed layer through the gas phase conduit.

And c, allowing a part of the hydro-upgrading reactant flow in the step b to enter a gas-liquid separator through an inlet of the gas-liquid separator, wherein the extracted part of the liquid phase material flow accounts for 5-95 wt% of the raw oil in terms of liquid phase, and preferably 10-80 wt%.

The separation described in step c typically comprises a hydro-upgrading high pressure separator and a low pressure separator separating the two parts. Wherein the high-pressure separator separates to obtain hydro-upgrading high-pressure hydrogen-rich gas and liquid, and the liquid separated by the high-pressure separator enters the low-pressure separator. The low pressure separator separates the high pressure liquid product to yield a hydrocarbon-rich gas and a low pressure liquid product. Separating the hydrocarbon-rich gas to obtain the required hydrogenation modified gas product.

The fractionation described in step c is carried out in a hydro-upgrading fractionator system. And fractionating the low-pressure liquid product in a fractionating tower to obtain a hydrogenation modified naphtha product and a hydrogenation modified diesel product.

The hydrogenation pour point depression catalyst in the step d is a conventional hydrogenation pour point depression catalyst, generally, metals in a VIB group and/or a VIII group are used as active components, the metals in the VIB group are generally Mo and/or W, and the metals in the VIII group are generally Co and/or Ni. The catalyst has carrier of one or more of alumina, silica-containing alumina and molecular sieve, preferably molecular sieve, which may be ZSM-5, ZSM-11, ZSM-22 or ZSM-35 type, preferably ZSM-5 molecular sieve. Based on the weight of the catalyst, the total metal content is 1wt% -20 wt% calculated by oxide, the molecular sieve content is 40wt% -85 wt%, and the adhesive content is 10wt% -40 wt%. The main catalysts comprise 3881 and FDW-1 catalysts which are developed by the petrochemical research institute. The hydrodewaxing conditions may be conventional, and are generally: the reaction pressure is 3.0 MPa-15 MPa0MPa, the reaction temperature is 200-440 ℃, and the liquid hourly space velocity is 0.3h^-1～12.0h^-1The volume ratio of the hydrogen to the oil is 100: 1-1500: 1.

The separation in step d is carried out in a hydrodewaxing high pressure separator and a low pressure separator. The hydrogenation pour point depression high-pressure separator obtains hydrogenation pour point depression high-pressure hydrogen-rich gas and liquid, and the liquid obtained by the separation of the high-pressure separator enters the low-pressure separator. The low pressure separator separates the high pressure liquid product to yield a hydrocarbon-rich gas and a low pressure liquid product. Separating the hydrocarbon-rich gas to obtain the required hydrogenation pour point depression gas product.

And d, fractionating in the step d to obtain a fractionating tower system, and fractionating the low-pressure liquid product in the fractionating tower to obtain a hydrodewaxing naphtha product and a hydrodewaxing diesel product.

The hydro-upgrading gas product and the hydro-pour point depressing gas product in the step c and the step d can be used as products independently or can be mixed into a mixed gas product.

The hydro-upgrading naphtha product and the hydro-dewaxing naphtha product in the step c and the step d can be used as products independently or can be mixed into a mixed naphtha product.

And e, mixing the high-pressure hydrogen-rich gas in the step e, and then directly using the mixed gas as recycle hydrogen, or recycling the mixed gas after hydrogen sulfide is removed by a recycle hydrogen desulfurization system.

With reference to fig. 1, the method of the present invention is as follows: raw oil 1 is firstly mixed with recycle hydrogen 21 and enters a hydrofining reactor 2, a hydrofining material flow 3 enters a hydro-upgrading reactor 4, a reaction material flow passing through a first hydro-upgrading catalyst bed layer is pumped out a hydro-dewaxing liquid raw material flow 5 through a gas-liquid separator 23, the material flow after the hydro-dewaxing raw material flow 5 is pumped out continues to enter a subsequent hydro-upgrading catalyst bed layer, a hydro-upgrading product flow 6 enters a hydro-upgrading high-pressure separator 8 for gas-liquid separation, the liquid obtained by separation enters a fractionating tower 10 for fractionation to obtain a hydro-upgrading gas product 12, a hydro-upgrading naphtha product 13 and a hydro-upgrading diesel product 14, the hydro-dewaxing liquid raw material flow 5 is mixed with recycle hydrogen 22 and enters a hydro-dewaxing reactor 7, the product material flow passing through the hydro-dewaxing catalyst bed layer enters a hydro-dewaxing high-pressure separator 9 for gas-liquid separation, the liquid obtained by separation enters the fractionating tower 11 for fractionation to obtain a hydro-dewaxing gas, The hydrogenation and pour point depression naphtha product 16 and the hydrogenation and pour point depression diesel product 17, the hydrogenation modified gas product 12 and the hydrogenation and pour point depression gas product 15 can be used as products independently or mixed to obtain a mixed gas product, the hydrogenation modified naphtha product 13 and the hydrogenation and pour point depression naphtha product 16 can be used as products independently or mixed to obtain a mixed naphtha product, and the gas 18 obtained by the separation of the hydrogenation modified high-pressure separator 8 and the gas 19 obtained by the separation of the hydrogenation and pour point depression high-pressure separator 9 are mixed and then are pressurized by a recycle hydrogen compressor and then are mixed with make-up hydrogen 20 to be used as recycle hydrogen.

The embodiments and effects of the present invention are described below by way of examples.

Examples 1 to 4

The protective agents FZC-100, FZC-105 and FZC106 are hydrogenation protective agents developed and produced by the smooth petrochemical research institute of the China petrochemical industry, Inc.; the catalyst FHUDS-5 is a hydrofining catalyst developed and produced by the smoothing petrochemical research institute of China petrochemical industry Limited company; the catalyst 3963 is a hydro-upgrading catalyst developed and produced by the research institute of the smooth petrochemical industry of the limited petrochemical company in China, and contains a Y-type molecular sieve; the content of the Y-type molecular sieve in the 3963B catalyst is 4 percent (number) higher than that of the Y-type molecular sieve in the 3963 catalyst, and the rest is unchanged; the catalyst 3881 is a hydrogenation pour point depressing catalyst which is developed and produced by China petrochemical company Limited and comforts petrochemical research institute and contains ZSM-5 type molecular sieve.

TABLE 1 Main Properties of Diesel feed stock

Table 2 examples process conditions and test results

Table 3 example process conditions and test results

It can be seen from the examples that, by adopting the hydro-upgrading process of the present invention, the purpose of producing diesel oil with different properties is realized by extracting a part of liquid reactant flow from the hydro-upgrading reactor and using the hydro-upgrading catalyst and the hydro-pour point depressing catalyst, and the production mode is flexible.

Claims

1. A flexible diesel hydro-upgrading pour point depressing process comprises the following steps:

b. b, passing the hydrofined material flow obtained in the step a through a first hydro-upgrading catalyst bed under hydro-upgrading conditions to obtain a first hydro-upgrading material flow, dividing the part of the reaction material flow into two parts, separating one part of the reaction material flow through a gas-liquid separator to obtain a liquid material flow, and pumping the obtained liquid out of the hydrogenation reactor;

2. The hydro-upgrading pour point depressing process according to claim 1, further comprising step e: and d, mixing the hydro-upgrading high-pressure hydrogen-rich gas obtained in the step c with the hydro-pour point depressing high-pressure hydrogen-rich gas obtained in the step d for recycling.

3. The hydro-upgrading pour point depressing process according to claim 1, wherein the initial boiling point of the diesel raw material is 100 to 260 ℃ and the final boiling point is 300 to 450 ℃.

4. The hydro-upgrading pour point depressing process according to claim 3, wherein the diesel raw oil is at least one selected from straight-run diesel, coker diesel, catalytic diesel, hydrotreated diesel, coal tar, coal direct liquefaction oil, coal indirect liquefaction oil and shale oil.

5. The hydro-upgrading pour point depressing process according to claim 1, wherein the hydrofining catalyst in step a takes VIB group and/or VIII group metals as active components, and takes alumina or siliceous alumina as a carrier; based on the weight of the catalyst, the content of the VIB group metal is 10-35 wt% calculated by oxide, and the content of the VIII group metal is 3-15 wt% calculated by oxide; the properties are as follows: the specific surface area is 100 to 650m²The pore volume is 0.15 to 0.6 mL/g.

6. The hydro-upgrading pour point depressing process according to claim 1, wherein the operating conditions of step a are: the reaction pressure is 3.0MPa to 15.0MPa, the reaction temperature is 300 ℃ to 430 ℃, and the liquid hourly volume space velocity is 0.2h^-1～6.0h^-1The volume ratio of the hydrogen to the oil is 100: 1-2000: 1.

7. The hydro-upgrading pour point depressing process according to claim 1, wherein the hydro-upgrading catalyst in the steps B and c takes metals in the VIB group and/or the VIII group as active components, and the carrier of the catalyst is one or more of alumina, siliceous alumina and molecular sieve.

8. The process of claim 7, wherein the carrier of the hydrogenation catalyst is alumina and molecularScreening; based on the weight of the catalyst, the content of the VIB group metal is 10 to 35 weight percent calculated by oxide, the content of the VIII group metal is 3 to 15 weight percent calculated by oxide, the content of the molecular sieve is 5 to 40 weight percent, the content of the alumina is 10 to 80 weight percent, and the specific surface area is 100m²/g～650m²The pore volume is 0.15mL/g to 0.50 mL/g.

9. The hydro-upgrading pour point depressing process according to claim 8, wherein the catalyst used in the first hydro-upgrading catalyst bed is hydrogenation catalyst A, the catalyst used in the second hydro-upgrading catalyst bed is hydrogenation catalyst B, and the content percentage x of the molecular sieve in the hydrogenation catalyst A is₁Less than the percentage content x of the molecular sieve in the hydrogenation catalyst B₂。

10. The hydro-upgrading pour point depressing process of claim 9, wherein x is₁Ratio x₂1-6 percentage points lower.

11. The hydro-upgrading pour point depressing process according to claim 1, wherein the hydro-upgrading conditions are: the reaction pressure is 3.0MPa to 15.0MPa, the reaction temperature is 300 ℃ to 430 ℃, and the liquid hourly volume space velocity is 0.3h^-1～15.0h^-1The volume ratio of the hydrogen to the oil is 100: 1-2000: 1.

12. The hydro-upgrading pour point depressing process according to claim 1, wherein the partial material flow extracted in the step b accounts for 5-95 wt% of the raw material oil in terms of liquid phase.

13. The hydro-upgrading pour point depressing process according to claim 1, wherein the partial material flow extracted in the step b accounts for 10-80 wt% of the raw material oil in terms of liquid phase.

14. The hydro-upgrading pour point depressing process according to claim 1, wherein the hydro-pour point depressing catalyst takes metals in a VIB group and/or a VIII group as active components, the carrier of the catalyst is alumina and/or siliceous alumina and a molecular sieve, and the molecular sieve is a ZSM-5, ZSM-11, ZSM-22 or ZSM-35 type molecular sieve.

15. The hydro-upgrading pour point depressing process according to claim 14, wherein the metal active component is present in an amount of 1 to 20wt% as oxide, the molecular sieve is present in an amount of 40 to 85wt%, and the binder is present in an amount of 10 to 40wt%, based on the weight of the catalyst.

16. The hydro-upgrading pour point depressing process according to claim 1, wherein the operating conditions for hydro-upgrading pour point depressing are as follows: the reaction pressure is 3.0MPa to 15.0MPa, the reaction temperature is 200 ℃ to 440 ℃, and the liquid hourly volume space velocity is 0.3h^-1～12.0h^-1The volume ratio of the hydrogen to the oil is 100: 1-1500: 1.

17. The hydro-upgrading pour point depressing process according to claim 1, wherein the hydrorefining catalyst bed, the first hydro-upgrading catalyst bed and the second hydro-upgrading catalyst bed are arranged in a hydrogenation reactor; or the hydrofining catalyst bed layer is arranged in a single hydrogenation reactor, and the first hydro-upgrading catalyst bed layer and the second hydro-upgrading catalyst bed layer are arranged in one hydro-upgrading reactor; or the hydrorefining catalyst bed layer and the first hydroupgrading catalyst bed layer are arranged in one hydroupgrading reactor, and the second hydroupgrading catalyst bed layer is arranged in the other hydroupgrading reactor.