Hydrocracking Process and System

Abstract

The invention relates to a hydrocracking process and system. The gas oil feedstock and hydrogen are mixed and reacted in a hydrotreating unit. The resulting reaction effluent is sent to a first hydrogenation cracking unit and reacted by contacting a hydrogenation cracking catalyst I to obtain light fraction I rich in paraffins and heavy fraction I rich in cyclic hydrocarbons. The heavy fraction I is mixed with hydrogen and reacted in a second hydrogenation cracking unit, thereby producing heavy fraction II rich in cyclic hydrocarbons. The present invention wholly realizes the high-selective directional conversion of gas oil feedstock according to the chain structure and the ring structure and can produce chemical raw materials rich in paraffins and naphthenic speciality oil rich in cyclic hydrocarbons.

Claims

1. A hydrocracking process, comprising: (1) in a hydrotreating unit, a mixture of gas oil feedstock and hydrogen gas is reacted by successively contacting a hydrogenation protection agent, an optional hydrodemetallization catalyst, and a hydrorefining catalyst, to produce a reaction effluent; (2) in a first hydrogenation cracking unit, the reaction effluent obtained from step (1) is sent to the first hydrogenation cracking unit, and reacted by contacting a hydrogenation cracking catalyst I in presence of hydrogen gas, the resulting reaction effluent is separated to at least produce light fraction I and heavy fraction I; the light fraction I is rich in paraffins, the mass fraction of paraffins in the light fraction I is at least 82%, the heavy fraction I is rich in naphthenes and aromatics, in hydrocarbon composition of the >350? C. fraction of the heavy fraction I, the sum of the mass fractions of naphthenes and aromatics is higher than 82%; (3) in a second hydrogenation cracking unit, the heavy fraction I obtained in step (2) is sent to the second hydrogenation cracking unit, and reacted by contacting a hydrogenation cracking catalyst II and/or a hydrotreating catalyst in presence of hydrogen gas, the resulting reaction effluent is separated to at least produce light fraction II and heavy fraction II.

2. The process according to claim 1, which is characterized in that the gas oil feedstock has an initial boiling point of 300-350? C. and is one or more of atmospheric gas oil, vacuum gas oil, hydrogenated gas oil, coker gas oil, catalytic cracking heavy cycle oil, and deasphalted oil.

3. The process according to claim 1, which is characterized in that in the hydrotreating unit, based on the whole catalyst of the hydrotreating unit, the loading volumetric fractions of the hydrogenation protection agent, the optional hydrodemetallization catalyst, and the hydrorefining catalyst are 3%-10%; 0%-20%; and 70%-90% respectively.

4. The process according to claim 1, which is characterized in that the hydrotreating unit has the following reaction conditions: hydrogen partial pressure: 3.0 MPa-20.0 MPa, e.g. 8.0 MPa-17.0 MPa, reaction temperature: 280? C.-400? C., e.g. 340-430? C., LHSV (based on the hydrorefining catalyst): 0.5 h.sup.?1-6 h.sup.1, e.g. 0.5 h.sup.?1-2.0 h.sup.1, H.sub.2/oil ratio by volume: 300-2000, e.g. 600-1000.

5. The process according to claim 1, which is characterized in that the hydrogenation protection agent contains a support and, loaded on the support, an active metal component, the support is one or more of alumina, silica, and titania, the active metal component is one or more of Group VIB metal(s), and Group VIII non-precious metal(s), based on the weight of the hydrogenation protection agent, as oxide, the active metal component comprises 0.1-15 wt %, the hydrogenation protection agent has a particle size of 0.5-50.0 mm, a bulk density of 0.3-1.2 g/cm.sup.3, and a specific surface area of 50-300 m.sup.2/g.

6. The process according to claim 1, which is characterized in that the hydrodemetallization catalyst contains a support and, loaded on the support, an active metal component, the support is one or more of alumina, silica, and titania, the active metal component is one or more of Group VIB metal(s), and Group VIII non-precious metal(s), based on the weight of the hydrodemetallization catalyst, as oxide, the active metal component comprises 3-30 wt %, the hydrodemetallization catalyst has a particle size of 0.2-2.0 mm, a bulk density of 0.3-0.8 g/cm.sup.3, and a specific surface area of 100-250 m.sup.2/g.

7. The process according to claim 1, which is characterized in that the hydrorefining catalyst is a supported catalyst, the support is alumina and/or silica-alumina, the active metal component is at least one selected from Group VIB metals and/or at least one selected from Group VIII metals; the Group VIII metal is Ni and/or Co, the Group VIB metal is Mo and/or W, based on the total weight of the hydrorefining catalyst, as oxide, the content of Group VIII metal(s) is 1-15 wt %, the content of Group VIB metal(s) is 5-40 wt %.

8. The process according to claim 7, which is characterized in that the active metal component of the hydrorefining catalyst is two or three of metals Ni, Mo and W.

9. The process according to claim 1, which is characterized in that in the hydrotreating unit, an aromatics saturation rate of feedstock is controlled to less than or equal to 58%; optionally, the aromatics saturation rate of feedstock=100%*(the content of aromatics in feedstock?the content of aromatics in reaction effluent of hydrotreating unit)/the content of aromatics in feedstock.

10. The process according to claim 1, which is characterized in that the first hydrogenation cracking unit has the following reaction conditions: hydrogen partial pressure: 3.0 MPa-20.0 MPa, e.g. 8.0 MPa-17.0 MPa, reaction temperature: 280? C.-430? C., e.g. 280? C.-400? C., or 340-430? C., LHSV: 0.5 h.sup.?1-6 h.sup.1, e.g.0.7 h.sup.?1-3.0 h.sup.1, H.sub.2/oil ratio by volume: 300-2000, e.g. 800-1500.

11. The process according to claim 1, which is characterized in that the conversion of >350? C. fraction in the first hydrogenation cracking unit is controlled to the following range: from 100*(A wt %/the mass fraction of >350? C. fraction in gas oil feedstock) to 100*(B wt %/the mass fraction of >350? C. fraction in gas oil feedstock), wherein, A is the mass fraction of paraffins in gas oil feedstock, B is the sum of mass fractions of paraffins, monocycloparaffins, and monocyclic aromatics in gas oil feedstock, wherein, the conversion of >350? C. fraction in the first hydrogenation cracking unit=100%*(the mass fraction of >350? C. fraction in gas oil feedstock?the mass fraction of >350? C. fraction in the reaction product of the first hydrogenation cracking unit)/the mass fraction of >350? C. fraction in gas oil feedstock.

12. The process according to claim 1, which is characterized in that the hydrogenation cracking catalyst I comprises a support and an active metal component, the support comprises heat-resistant inorganic oxides and molecular sieves, the heat-resistant inorganic oxide is one or more of silica and alumina, the active metal component is at least two metal components of Group VIB metals and Group VIII metals; based on the whole of hydrogenation cracking catalyst I, as oxide, Group VIB metal comprises 10 wt %-35 wt %, Group VIII metal comprises 2 wt %-8 wt %; based on the support, the molecular sieve comprises 10 wt %-75 wt %, preferably, 20 wt %-60 wt %, e.g. 35 wt %-45 wt %, the balance is the heat-resistant inorganic oxide; the molecular sieve has a silica/alumina molar ratio of 20-50, a pore size of 0.4 nm-0.58 nm, preferably, a specific surface area of 200 m.sup.2/g-400 m.sup.2/g.

13. The process according to claim 12, which is characterized in that the molecular sieve is one or more of molecular sieves ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-48, ZSM-50, IM-5, MCM-22, and EU-1, preferably ZSM-5.

14. The process according to claim 1, which is characterized in that the second hydrogenation cracking unit has the following reaction conditions: hydrogen partial pressure: 3.0 MPa-20.0 MPa, e.g. 8.0 MPa-17.0 MPa, reaction temperature: 280? C.-430? C., e.g., 280-400? C., LHSV: 0.5 h.sup.?1-6 h.sup.1, e.g. 0.7 h.sup.?1-3.0 h.sup.1, H.sub.2/oil ratio by volume: 300-2000, e.g. 800-1800.

15. The process according to any one of previous claims claim 1, which is characterized in that the conversion of >350? C. fraction in the second hydrogenation cracking unit is controlled to a range of 5%-80%, wherein, the conversion of >350? C. fraction in the second hydrogenation cracking unit=100%*(the mass fraction of >350? C. fraction of heavy fraction I?the mass fraction of >350? C. fraction of heavy fraction II)/the mass fraction of >350? C. fraction of heavy fraction I.

16. The process according to claim 1, which is characterized in that the hydrogenation cracking catalyst II comprises a support and an active metal component, said support comprises heat-resistant inorganic oxides and Y-type molecular sieves, the heat-resistant inorganic oxide is one or more of silica, alumina, and titania, the active metal component is at least two metal components of Group VIB metals and Group VIII metals; based on the whole of hydrogenation cracking catalyst II, as oxide, Group VIB metal comprises 10 wt %-35 wt %, Group VIII metal comprises 2 wt %-8 wt %; based on the support, the Y-type molecular sieve comprises 5 wt %-55 wt %, the balance is the heat-resistant inorganic oxide; optionally, in the case that the second hydrogenation cracking unit is loaded with the hydrogenation cracking catalyst, the reaction temperature of second hydrogenation cracking unit is 0-30? C. higher than the temperature of the first hydrogenation cracking unit.

17. The process according to claim 1, which is characterized in that the hydrotreating catalyst is a supported catalyst, the support is alumina or silica-alumina, the active metal component is at least one selected from Group VIB metals and/or at least one selected from Group VIII metals, the Group VIII metal is Ni and/or Co, the Group VIB metal is Mo and/or W, based on the total weight of the hydrotreating catalyst, as oxide, the content of Group VIII metal(s) is 1-15 wt %, the content of Group VIB metal(s) is 5-40 wt %; optionally, in the case that the second hydrogenation cracking unit is loaded with the hydrotreating catalyst, the reaction temperature of second hydrogenation cracking unit is 0-35? C. lower than the temperature of the first hydrogenation cracking unit.

18. The process according to claim 1, which is characterized in that the resulting reaction effluent of the first hydrogenation cracking unit is separated to produce light fraction I and heavy fraction I, light fraction I has an initial boiling point of 20? C.-30? C., light fraction I and heavy fraction I have a cutting point of 65? C.-120? C., preferably 65-105? C.; the mass fraction of paraffins in the light fraction I is at least 85%.

19. The process according to claim 1, which is characterized in that the resulting reaction effluent of the first hydrogenation cracking unit is separated to produce light fraction I and heavy fraction I, light fraction I has an initial boiling point of 20? C.-30? C., light fraction I and middle fraction I have a cutting point of 65? C.-120? C., preferably 65-105? C., middle fraction I and heavy fraction I have a cutting point of 160-180? C., the light fraction I is rich in paraffins, preferably the mass fraction of paraffins in the light fraction I is at least 85%.

20. The process according to claim 1, which is characterized in that light fraction II has an initial boiling point of 65? C.-100? C., light fraction II and heavy fraction II have a cutting point of 155-180? C.; the light fraction II has a total mass fraction of naphthenes and aromatics of at least 58%, the mass fraction of naphthenes in the >350? C. fraction of heavy fraction II is at least 50%.

21. The process according to claim 1, which is characterized in that the mass content of aromatics+naphthenes in the hydrocarbons of the gas oil feedstock is greater than 70%, e.g. 70%-90%, 75%-90%, 80%-90%, 85-90%, 75%-85%, 80%-85%.

22. The process according to claim 1, which is characterized in that the process condition parameters of reaction temperature, LHSV, H.sub.2/oil ratio and reaction pressure of the first hydrogenation cracking unit are adjusted and controlled so that the conversion of paraffins in the feedstock is 56%-95%, the total conversion of naphthenes and aromatics is 10%-65%.

23. The process according to claim 1, which is characterized in that a stream that is sent to the first hydrogenation cracking unit for treatment has an aromatics mass content of 10 wt %-40 wt %, and on the basis that the content of aromatics is 100 wt %, the content of monocyclic aromatics is 60 wt %-85 wt %.

24. The process according to claim 1, which is characterized in that a stream that is sent to the second hydrogenation cracking unit for treatment has a total mass content of naphthenes and aromatics of 75 wt %-90 wt %.

25. The process according to claim 1, which is characterized in that in the first hydrogenation cracking unit, the hydrogenation cracking catalyst I comprises a support and an active metal component, the support comprises heat-resistant inorganic oxides and molecular sieves, based on the support, the molecular sieve comprises 10 wt %-75 wt %, preferably, 20 wt %-60 wt %, e.g. 35 wt %-45 wt %, the balance is the heat-resistant inorganic oxide; the molecular sieve has a silica/alumina molar ratio of 20-50, a pore size of 0.4 nm-0.58 nm, preferably, a specific surface area of 200 m.sup.2/g-400 m.sup.2/g.

26. The process according to claim 1, which is characterized in that in the first hydrogenation cracking unit, a fraction cutting is performed at 65? C.-120? C., preferably 65-105? C., and optionally a fraction cutting is performed at 160? C.-180? C.

27. The process according to claim 1, which is characterized in that the gas oil feedstock has an initial boiling point of 300-350? C., a final boiling point of 520-650? C., and a density at 20? C. of 0.890 g/cm.sup.3-0.940 g/cm.sup.3; the mass content of aromatics+naphthenes in the hydrocarbons of the gas oil feedstock is greater than 70%, e.g. 70%-90%, 75%-90%, 80%-90%, 85-90%, 75%-85%, 80%-85%; and the gas oil feedstock is one or more of atmospheric gas oil, vacuum gas oil, hydrogenated gas oil, coker gas oil, catalytic cracking heavy cycle oil, and deasphalted oil.

28. The process according to claim 1, which is characterized in that in the first hydrogenation cracking unit, one or more process condition parameters of reaction temperature, LHSV, H.sub.2/oil ratio and reaction pressure, preferably reaction temperature and LHSV, of the first hydrogenation cracking unit are adjusted and controlled so that the conversion of paraffins in the feedstock is 56%-95%, the total conversion of naphthenes and aromatics is 10%-65%, wherein the conversion of paraffins=(the content of paraffins in the feedstock?the content of paraffins in the >350? C. fraction of the product of the first hydrogenation cracking unit*the mass fraction of the >350? C. fraction in the product of the first hydrogenation cracking unit)/the content of paraffins in the feedstock; the total conversion of naphthenes and aromatics=(the total content of naphthenes and aromatics in the feedstock?the total content of naphthenes and aromatics in >350? C. fraction of the product of the first hydrogenation cracking unit*the mass fraction of the >350? C. fraction in the product of the first hydrogenation cracking unit)/the total content of naphthenes and aromatics in the feedstock.

29. A system for performing the process according to claim 1, comprising a hydrotreating unit, a first hydrogenation cracking unit, and a second hydrogenation cracking unit; the hydrotreating unit is provided with a gas oil feedstock inlet, a hydrogen gas inlet, and a reaction effluent outlet, in the hydrotreating unit are successively loaded a hydrogenation protection agent, optionally a hydrodemetallization catalyst, and a hydrorefining catalyst; the first hydrogenation cracking unit is provided with a first hydrogenation cracking system and a first separation system, in the first hydrogenation cracking system is loaded a hydrogenation cracking catalyst I, the first hydrogenation cracking system is provided with an inlet for the reaction effluent of the hydrotreating unit, which is communicated with the reaction effluent outlet of the hydrotreating unit, a reaction effluent outlet of the first hydrogenation cracking system is communicated with an inlet of the first separation system, the first separation system is at least provided with a first hydrogen-rich gas outlet, a light fraction I outlet and a heavy fraction I outlet; the second hydrogenation cracking unit is provided with a second hydrogenation cracking system and a second separation system, in the second hydrogenation cracking system are loaded a hydrogenation cracking catalyst II and/or a hydrotreating catalyst, the second hydrogenation cracking system is provided with an inlet for heavy fraction I, which is communicated with the heavy fraction I outlet of the first separation system, a reaction effluent outlet of the second hydrogenation cracking system is communicated with an inlet for the second separation system, the second separation system is at least provided with a second hydrogen-rich gas outlet, a light fraction II outlet, and a heavy fraction II outlet.

30. The apparatus according to claim 1, wherein in the first hydrogenation cracking unit, the hydrogenation cracking catalyst I comprises a support and an active metal component, the support comprises heat-resistant inorganic oxides and molecular sieves, based on the support, the molecular sieve comprises 10 wt %-75 wt %, preferably, 20 wt %-60 wt %, e.g. 35 wt %-45 wt %, the balance is the heat-resistant inorganic oxide; the molecular sieve has a silica/alumina molar ratio of 20-50, and a pore size of 0.4 nm-0.58 nm; in the first hydrogenation cracking unit, a control device is provided to control a fraction cutting to be performed at 65? C.-120? C., preferably 65-105? C., and optionally a control device is provided to control a fraction cutting to be performed at 160-180? C.

Description

DESCRIPTION OF THE DRAWINGS

[0075] FIG. 1 is a schematic diagram of one embodiment of the hydrocracking process provided by the present invention.

DETAILED DESCRIPTION

[0076] The present invention will be further described below in conjunction with the accompanying drawings, but the invention is not limited thereby.

[0077] FIG. 1 is a schematic diagram of one embodiment of the hydrocracking process provided by the present invention. As shown in FIG. 1, gas oil feedstock 1 and hydrogen gas 2 are reacted in a hydrotreating unit by successively contacting a hydrogenation protection agent, an optional hydrodemetallization catalyst, and a hydrorefining catalyst. The resulting reaction effluent 3 is sent to a first hydrogenation cracking unit, and reacted by contacting a hydrogenation cracking catalyst I in presence of hydrogen gas. The resulting reaction effluent 4 is separated in a separator I to produce a hydrogen-rich gas 5, a first liquid phase stream 6 and a heavy fraction I 10. The resulting first liquid phase stream 6 is sent to a fractionation unit I for fractionating to produce a low carbon light hydrocarbon 7, a light fraction I 8, a bottom oil 9 (middle fraction I). The obtained bottom oil 9 can be sent to a fractionation unit II for further fractionating. The obtained heavy fraction I 10 and hydrogen gas 11 are reacted in a second hydrogenation cracking unit by contacting a hydrogenation cracking catalyst II and/or a hydrotreating catalyst. The resulting reaction effluent 12 is separated in a separator II to produce a hydrogen-rich gas 13 and a second liquid phase stream 14. The obtained second liquid phase stream 14 is sent to the fractionation unit II for fractionating to produce a top oil 15, a light fraction II 16 and a heavy fraction II 17. The obtained top oil 15 can be sent to the fractionation unit I for further fractionating.

[0078] The present invention provides the following technical solutions and any combination thereof:

[0079] 1. A hydrocracking process, comprising: [0080] (1) in a hydrotreating unit, a mixture of gas oil feedstock and hydrogen gas is reacted by successively contacting a hydrogenation protection agent, an optional hydrodemetallization catalyst, and a hydrorefining catalyst, to produce a reaction effluent; [0081] (2) in a first hydrogenation cracking unit, the reaction effluent obtained from step (1) is sent to the first hydrogenation cracking unit, and reacted by contacting a hydrogenation cracking catalyst I in presence of hydrogen gas, the resulting reaction effluent is separated to at least produce light fraction I and heavy fraction I; the light fraction I is rich in paraffins. the mass fraction of paraffins in the light fraction I is at least 82%, the heavy fraction I is rich in naphthenes and aromatics, in hydrocarbon composition of the >350? C. fraction of the heavy fraction I, the sum of the mass fractions of naphthenes and aromatics is higher than 82%; [0082] (3) in a second hydrogenation cracking unit, the heavy fraction I obtained in step (2) is sent to the second hydrogenation cracking unit, and reacted by contacting a hydrogenation cracking catalyst II and/or a hydrotreating catalyst in presence of hydrogen gas, the resulting reaction effluent is separated to at least produce light fraction II and heavy fraction II.

[0083] 2. The process according to any one of previous technical solutions, which is characterized in that the gas oil feedstock has an initial boiling point of 300-350? C. and is one or more of atmospheric gas oil, vacuum gas oil, hydrogenated gas oil, coker gas oil, catalytic cracking heavy cycle oil, and deasphalted oil.

[0084] 3. The process according to any one of previous technical solutions, which is characterized in that in the hydrotreating unit, based on the whole catalyst of the hydrotreating unit, the loading volumetric fractions of the hydrogenation protection agent, the optional hydrodemetallization catalyst, and the hydrorefining catalyst are 3%-10%; 0%-20%; and 70%-90% respectively.

[0085] 4. The process according to any one of previous technical solutions, which is characterized in that the hydrotreating unit has the following reaction conditions: hydrogen partial pressure: 3.0 MPa-20.0 MPa, e.g. 8.0 MPa-17.0 MPa, reaction temperature: 280? C.-400? C., e.g. 340-430? C., LHSV (based on the hydrorefining catalyst): 0.5 h.sup.?1-6 h.sup.?1, e.g. 0.5 h.sup.?1-2.0 h.sup.?1, H.sub.2/oil ratio by volume: 300-2000, e.g. 600-1000.

[0086] 5. The process according to any one of previous technical solutions, which is characterized in that the hydrogenation protection agent contains a support and, loaded on the support, an active metal component, the support is one or more of alumina, silica, and titania, the active metal component is one or more of Group VIB metal(s), and Group VIII non-precious metal(s), based on the weight of the hydrogenation protection agent, as oxide, the active metal component comprises 0.1-15 wt %, the hydrogenation protection agent has a particle size of 0.5-50.0 mm, a bulk density of 0.3-1.2 g/cm.sup.3, and a specific surface area of 50-300 m.sup.2/g.

[0087] 6. The process according to any one of previous technical solutions, which is characterized in that the hydrodemetallization catalyst contains a support and, loaded on the support, an active metal component, the support is one or more of alumina, silica, and titania, the active metal component is one or more of Group VIB metal(s), and Group VIII non-precious metal(s), based on the weight of the hydrodemetallization catalyst, as oxide, the active metal component comprises 3-30 wt %, the hydrodemetallization catalyst has a particle size of 0.2-2.0 mm, a bulk density of 0.3-0.8 g/cm.sup.3, and a specific surface area of 100-250 m.sup.2/g.

[0088] 7. The process according to any one of previous technical solutions, which is characterized in that the hydrorefining catalyst is a supported catalyst, the support is alumina and/or silica-alumina, the active metal component is at least one selected from Group VIB metals and/or at least one selected from Group VIII metals; the Group VIII metal is Ni and/or Co, the Group VIB metal is Mo and/or W, based on the total weight of the hydrorefining catalyst, as oxide, the content of Group VIII metal(s) is 1-15 wt %, the content of Group VIB metal(s) is 5-40 wt %.

[0089] 8. The process according to technical solution 7, which is characterized in that the active metal component of the hydrorefining catalyst is two or three of metals Ni, Mo and W.

[0090] 9. The process according to any one of previous technical solutions, which is characterized in that in the hydrotreating unit, an aromatics saturation rate of feedstock is controlled to less than or equal to 58%; optionally, the aromatics saturation rate of feedstock=100%*(the content of aromatics in feedstock?the content of aromatics in reaction effluent of hydrotreating unit)/the content of aromatics in feedstock.

[0091] 10. The process according to any one of previous technical solutions, which is characterized in that the first hydrogenation cracking unit has the following reaction conditions: hydrogen partial pressure: 3.0 MPa-20.0 MPa, e.g. 8.0 MPa-17.0 MPa, reaction temperature: 280? C.-430? C., e.g. 280? C.-400? C., or 340-430? C., LHSV: 0.5 h.sup.?1-6 h.sup.?1, e.g. 0.7 h.sup.?1-3.0 h.sup.?1, H.sub.2/oil ratio by volume: 300-2000, e.g. 800-1500.

[0092] 11. The process according to any one of previous technical solutions, which is characterized in that the conversion of >350? C. fraction in the first hydrogenation cracking unit is controlled to the following range: [0093] from 100*(Awt %/the mass fraction of >350? C. fraction in gas oil feedstock) to 100*(Bwt %/the mass fraction of >350? C. fraction in gas oil feedstock), [0094] wherein, A is the mass fraction of paraffins in gas oil feedstock, B is the sum of mass fractions of paraffins, monocycloparaffins, and monocyclic aromatics in gas oil feedstock, [0095] wherein, the conversion of >350? C. fraction in the first hydrogenation cracking unit=100%*(the mass fraction of >350? C. fraction in gas oil feedstock?the mass fraction of >350? C. fraction in the reaction product of the first hydrogenation cracking unit)/the mass fraction of >350? C. fraction in gas oil feedstock.

[0096] 12. The process according to any one of previous technical solutions, which is characterized in that the hydrogenation cracking catalyst I comprises a support and an active metal component, the support comprises heat-resistant inorganic oxides and molecular sieves, the heat-resistant inorganic oxide is one or more of silica and alumina, the active metal component is at least two metal components of Group VIB metals and Group VIII metals; based on the whole of hydrogenation cracking catalyst I, as oxide, Group VIB metal comprises 10 wt %-35 wt %, Group VIII metal comprises 2 wt %-8 wt %; [0097] based on the support, the molecular sieve comprises 10 wt %-75 wt %, preferably, 20 wt %-60 wt %, e.g. 35 wt %-45 wt %, the balance is the heat-resistant inorganic oxide: [0098] the molecular sieve has a silica/alumina molar ratio of 20-50, a pore size of 0.4 nm-0.58 nm, preferably, a specific surface area of 200 m.sup.2/g-400 m.sup.2/g.

[0099] 13. The process according to technical solution 12, which is characterized in that the molecular sieve is one or more of molecular sieves ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-48, ZSM-50, IM-5, MCM-22, and EU-1, preferably ZSM-5.

[0100] 14. The process according to any one of previous technical solutions, which is characterized in that the second hydrogenation cracking unit has the following reaction conditions: [0101] hydrogen partial pressure: 3.0 MPa-20.0 MPa, e.g. 8.0 MPa-17.0 MPa, reaction temperature: 280? C.-430? C., e.g., 280-400? C., LHSV: 0.5 h.sup.?1-6 h.sup.?1, e.g. 0.7 h.sup.?1-3.0 h.sup.?1, H.sub.2/oil ratio by volume: 300-2000, e.g. 800-1800.

[0102] 15. The process according to any one of previous technical solutions, which is characterized in that the conversion of >350? C. fraction in the second hydrogenation cracking unit is controlled to a range of 5%-80%, [0103] wherein, the conversion of >350? C. fraction in the second hydrogenation cracking unit=100%*(the mass fraction of >350? C. fraction of heavy fraction I?the mass fraction of >350? C. fraction of heavy fraction II)/the mass fraction of >350? C. fraction of heavy fraction I.

[0104] 16. The process according to any one of previous technical solutions, which is characterized in that the hydrogenation cracking catalyst II comprises a support and an active metal component, said support comprises heat-resistant inorganic oxides and Y-type molecular sieves, the heat-resistant inorganic oxide is one or more of silica, alumina, and titania, the active metal component is at least two metal components of Group VIB metals and Group VIII metals; based on the whole of hydrogenation cracking catalyst II, as oxide, Group VIB metal comprises 10 wt %-35 wt %, Group VIII metal comprises 2wt %-8wt %; [0105] based on the support, the Y-type molecular sieve comprises 5wt %-55wt %, the balance is the heat-resistant inorganic oxide; [0106] optionally, in the case that the second hydrogenation cracking unit is loaded with the hydrogenation cracking catalyst, the reaction temperature of second hydrogenation cracking unit is 0-30?? C. higher than the temperature of the first hydrogenation cracking unit.

[0107] 17. The process according to any one of previous technical solutions, which is characterized in that the hydrotreating catalyst is a supported catalyst, the support is alumina or silica-alumina, the active metal component is at least one selected from Group VIB metals and/or at least one selected from Group VIII metals, the Group VIII metal is Ni and/or Co, the Group VIB metal is Mo and/or W, based on the total weight of the hydrotreating catalyst, as oxide, the content of Group VIII metal(s) is 1-15 wt %, the content of Group VIB metal(s) is 5-40 wt %; [0108] optionally, in the case that the second hydrogenation cracking unit is loaded with the hydrotreating catalyst, the reaction temperature of second hydrogenation cracking unit is 0-35? C. lower than the temperature of the first hydrogenation cracking unit.

[0109] 18. The process according to any one of previous technical solutions, which is characterized in that the resulting reaction effluent of the first hydrogenation cracking unit is separated to produce light fraction I and heavy fraction I, light fraction I has an initial boiling point of 20? C.-30? C., light fraction I and heavy fraction I have a cutting point of 65? C.-120? C., preferably 65-105? C.; the mass fraction of paraffins in the light fraction I is at least 85%.

[0110] 19. The process according to any one of previous technical solutions, which is characterized in that the resulting reaction effluent of the first hydrogenation cracking unit is separated to produce light fraction I and heavy fraction I, light fraction I has an initial boiling point of 20? C.-30? C., light fraction I and middle fraction I have a cutting point of 65? C.-120? C., preferably 65-105? C., middle fraction I and heavy fraction I have a cutting point of 160-180? C., the light fraction I is rich in paraffins, preferably the mass fraction of paraffins in the light fraction I is at least 85%.

[0111] 20. The process according to any one of previous technical solutions, which is characterized in that light fraction II has an initial boiling point of 65? C.-100? C., light fraction II and heavy fraction II have a cutting point of 155-180? C.; [0112] the light fraction II has a total mass fraction of naphthenes and aromatics of at least 58%, the mass fraction of naphthenes in the >350? C. fraction of heavy fraction II is at least 50%.

[0113] 21. The process according to any one of previous technical solutions, which is characterized in that the mass content of aromatics+naphthenes in the hydrocarbons of the gas oil feedstock is greater than 70%, e.g. 70%-90%, 75%-90%, 80%-90%, 85-90%, 75%-85%, 80%-85%.

[0114] 22. The process according to any one of previous technical solutions, which is characterized in that [0115] the process condition parameters of reaction temperature, LHSV, H.sub.2/oil ratio and reaction pressure of the first hydrogenation cracking unit are adjusted and controlled so that the conversion of paraffins in the feedstock is 56%-95%, the total conversion of naphthenes and aromatics is 10%-65%.

[0116] 23. The process according to any one of previous technical solutions, which is characterized in that a stream that is sent to the first hydrogenation cracking unit for treatment has an aromatics mass content of 10 wt %-40 wt %, and on the basis that the content of aromatics is 100 wt %, the content of monocyclic aromatics is 60 wt %-85 wt %.

[0117] 24. The process according to any one of previous technical solutions, which is characterized in that a stream that is sent to the second hydrogenation cracking unit for treatment has a total mass content of naphthenes and aromatics of 75 wt %-90 wt %.

[0118] 25. The process according to any one of previous technical solutions, which is characterized in that in the first hydrogenation cracking unit, the hydrogenation cracking catalyst I comprises a support and an active metal component, the support comprises heat-resistant inorganic oxides and molecular sieves, based on the support, the molecular sieve comprises 10 wt %-75 wt %, preferably, 20 wt %-60 wt %, e.g. 35 wt %-45 wt %, the balance is the heat-resistant inorganic oxide; the molecular sieve has a silica/alumina molar ratio of 20-50, a pore size of 0.4 nm-0.58 nm, preferably, a specific surface area of 200 m.sup.2/g-400 m.sup.2/g.

[0119] 26. The process according to any one of previous technical solutions, which is characterized in that in the first hydrogenation cracking unit, a fraction cutting is performed at 65? C.-120? C., preferably 65-105? C., and optionally a fraction cutting is performed at 160? C.-180? C.

[0120] 27. The process according to any one of previous technical solutions, which is characterized in that the gas oil feedstock has an initial boiling point of 300-350? C., a final boiling point of 520-650? C., and a density at 20? C. of 0.890 g/cm.sup.3-0.940 g/cm.sup.3; the mass content of aromatics+naphthenes in the hydrocarbons of the gas oil feedstock is greater than 70%, e.g. 70%-90%, 75%-90%, 80%-90%, 85-90%, 75%-85%, 80%-85%; and the gas oil feedstock is one or more of atmospheric gas oil, vacuum gas oil, hydrogenated gas oil, coker gas oil, catalytic cracking heavy cycle oil, and deasphalted oil.

[0121] 28. The process according to any one of previous technical solutions, which is characterized in that [0122] in the first hydrogenation cracking unit, one or more process condition parameters of reaction temperature, LHSV, H.sub.2/oil ratio and reaction pressure, preferably reaction temperature and LHSV, of the first hydrogenation cracking unit are adjusted and controlled so that the conversion of paraffins in the feedstock is 56%-95%, the total conversion of naphthenes and aromatics is 10%-65%, [0123] wherein

the conversion of paraffins=(the content of paraffins in the feedstock?the content of paraffins in the >350? C. fraction of the product of the first hydrogenation cracking unit * the mass fraction of the >350? C. fraction in the product of the first hydrogenation cracking unit )/the content of paraffins in the feedstock;

the total conversion of naphthenes and aromatics=(the total content of naphthenes and aromatics in the feedstock?the total content of naphthenes and aromatics in >350? C. fraction of the product of the first hydrogenation cracking unit * the mass fraction of the >350? C. fraction in the product of the first hydrogenation cracking unit )/the total content of naphthenes and aromatics in the feedstock.

[0124] 29. The process according to any one of previous technical solutions, which is characterized in that for the aromatics saturation rate of feedstock, and for the conversion of >350? C. fraction, the conversion of paraffins, and the conversion of naphthenes+aromatic in the first hydrogenation cracking unit, operation parameters are determined as follows, to control the saturation rate/conversion: [0125] (1) setting a target difference between the actual saturation rate/conversion and the target saturation rate/conversion, such as 20%, [0126] (2) pre-determining a group of operation parameters, including hydrogen partial pressure or reaction pressure, reaction temperature, LHSV, and H.sub.2/oil ratio by volume, and determining an actual saturation rate/conversion under the pre-determined operation parameters, [0127] (3) when the absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion is greater than the target difference, using a certain step size as the initial step size and increasing or decreasing the operation temperature until the absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion is less than the target difference; [0128] reducing the step size if the operation temperature is increased or decreased with this step size and the absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion being less than the target difference can never be achieved within the operation temperature range, and starting from the predetermined temperature, increasing or decreasing the operation temperature until the absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion is less than the target difference; [0129] (4) using the temperature determined in step (3) as the predetermined temperature in step (4), using a step size smaller than the initial step size in step (3) as the initial step size in step (4), and using a target difference smaller than the target difference in step (3) as the target difference in step (4), repeating step (3); [0130] (5) performing step (3) or (4), or repeating step (4) until the desired absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion is reached, thereby determining the operation temperature and achieving the control of the saturation rate/conversion; [0131] re-determining the operation parameters of step (2) if the absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion being less than the target difference can never be achieved, or if the desired absolute value of the difference between the actual saturation rate/conversion and the target saturation rate/conversion can never be achieved, [0132] for example, increasing or decreasing one or more of hydrogen partial pressure or reaction pressure, LHSV, and H.sub.2/oil ratio by volume by a factor of 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or a higher or lower value, and repeating step (2).

[0133] 30. The process according to any one of previous technical solutions, which is characterized in that for the conversion of >350? C. fraction, the conversion of paraffins, and the conversion of naphthenes+aromatic in the first hydrogenation cracking unit, operation parameters are determined as follows, to control the conversions: [0134] a linear relationship between the reaction temperature of the first hydrogenation cracking unit and the conversion of >350? C. fraction, the conversion of paraffins, and the conversion of naphthenes+aromatic in the first hydrogenation cracking unit is determined, which satisfies:

y.sub.conversion=a*reaction temperature value?B, [0135] wherein the range of a is 0.10-4.0, and the range of B is 30-300; [0136] for the conversion of >350? C. fraction in the first hydrogenation cracking unit in the linear relationship formula, the range of parameter a is 0.3-3.0, and the range of parameter B is 100-300; [0137] for the conversion of paraffins, in the linear relationship formula, the range of parameter a is 0.2-2.0, and the range of parameter B is 40-150; [0138] for the conversion of naphthenes+aromatic, in the linear relationship formula, the range of parameter a is 0.25-2.5, and the range of parameter B is 60-250; [0139] the operation temperature is determined with the above conversion linear relationship formula.

[0140] 31. A system for performing the process according to any one of the preceding technical solutions, comprising a hydrotreating unit, a first hydrogenation cracking unit, and a second hydrogenation cracking unit; [0141] the hydrotreating unit is provided with a gas oil feedstock inlet, a hydrogen gas inlet, and a reaction effluent outlet, in the hydrotreating unit are successively loaded a hydrogenation protection agent, optionally a hydrodemetallization catalyst, and a hydrorefining catalyst; [0142] the first hydrogenation cracking unit is provided with a first hydrogenation cracking system and a first separation system, in the first hydrogenation cracking system is loaded a hydrogenation cracking catalyst I, the first hydrogenation cracking system is provided with an inlet for the reaction effluent of the hydrotreating unit, which is communicated with the reaction effluent outlet of the hydrotreating unit, a reaction effluent outlet of the first hydrogenation cracking system is communicated with an inlet of the first separation system, the first separation system is at least provided with a first hydrogen-rich gas outlet, a light fraction I outlet and a heavy fraction I outlet; [0143] the second hydrogenation cracking unit is provided with a second hydrogenation cracking system and a second separation system, in the second hydrogenation cracking system are loaded a hydrogenation cracking catalyst II and/or a hydrotreating catalyst, the second hydrogenation cracking system is provided with an inlet for heavy fraction I, which is communicated with the heavy fraction I outlet of the first separation system, a reaction effluent outlet of the second hydrogenation cracking system is communicated with an inlet for the second separation system, the second separation system is at least provided with a second hydrogen-rich gas outlet, a light fraction II outlet, and a heavy fraction II outlet.

[0144] 32. The apparatus according to any one of the preceding technical solutions, wherein [0145] in the first hydrogenation cracking unit, the hydrogenation cracking catalyst I comprises a support and an active metal component, the support comprises heat-resistant inorganic oxides and molecular sieves, based on the support, the molecular sieve comprises 10 wt %-75 wt %, preferably, 20 wt %-60 wt %, e.g. 35 wt %-45 wt %, the balance is the heat-resistant inorganic oxide; the molecular sieve has a silica/alumina molar ratio of 20-50, and a pore size of 0.4 nm-0.58 nm; [0146] in the first hydrogenation cracking unit, a control device is provided to control a fraction cutting to be performed at 65? C.-120? C., preferably 65-105? C., and optionally a control device is provided to control a fraction cutting to be performed at 160-180? C.

[0147] The present invention will be further described below with reference to the examples, but this does not limit the present invention in any way.

[0148] In the Examples and Comparative Examples, the hydrocarbon composition data of gas oil feedstock are obtained through SH/T 0659 Standard test method for hydrocarbon types analysis of gas-oil saturates fractions by high ionizing voltage mass spectrometry.

[0149] The hydrocarbon composition data of light fraction I and light fraction II are obtained through SH/T 0714 Standard test method for detailed analysis of petroleum naphthas through n-nonane by capillary gas chromatography.

[0150] The hydrocarbon composition data of >350? C. fraction of heavy fraction I, and >350? C. fraction of heavy fraction II are obtained through SH/T 0659 Standard test method for hydrocarbon types analysis of gas-oil saturates fractions by high ionizing voltage mass spectrometry.

[0151] Table 1 lists the properties of the gas oil feedstock used in the present invention.

[0152] Table 2 and Table 3 list the physical and chemical properties of each catalyst used in Examples and Comparative Examples of the present invention. The catalysts with trade names are all produced by the Sinopec Catalyst Branch, and the catalysts without trade names are all obtained with preparation methods for conventional supported hydrogenation catalysts used in fixed beds.

[0153] It can be seen from Table 1, the mass fraction (A) of paraffins in the gas oil feedstock used in the present invention is 20.4, [0154] the sum (B) of mass fractions of paraffins, monocycloparaffins, monocyclic aromatics in the gas oil feedstock is 49.3.

[0155] According to the present invention, the conversion of >350? C. fraction in the first hydrogenation cracking unit is controlled to the following range: [0156] from 100*(Awt %/the mass fraction of >350? C. fraction in gas oil feedstock) to 100*(Bwt %/the mass fraction of >350? C. fraction in gas oil feedstock), [0157] wherein, A is the mass fraction of paraffins in gas oil feedstock, B is the sum of mass fractions of paraffins, monocycloparaffins, and monocyclic aromatics in gas oil feedstock.

[0158] Then, the conversion of >350? C. fraction in the first hydrogenation cracking unit should be controlled in the range of 22.7-54.7%.

[0159] In Examples and Comparative Examples of the present invention, the yield of low-carbon light hydrocarbons, the yield of light fraction I, the yield of light fraction II, and the yield of heavy fraction II are all calculated based on the gas oil feedstock.

[0160] In Examples and Comparative Examples of the present invention, the mass fraction of >350? C. fraction of heavy fraction I was based on the mass of heavy fraction I; the mass fraction of (280-370? C.) fraction of heavy fraction II was based on the mass of heavy fraction II; the mass fraction of >350? C. fraction of heavy fraction IIwas based on the mass of heavy fraction II.

Example 1

[0161] A gas oil feedstock was reacted by successively contacting a hydrogenation protection agent (protection agent), a hydrodemetallization catalyst (demetallization agent), and a hydrorefining catalyst (refining catalyst) in a hydrotreating unit. The resulting reaction effluent was sent to the first hydrogenation cracking unit. and reacted by contacting a ZSM-5 molecular sieve-containing hydrogenation cracking catalyst I (cracking agent 1). The resulting reaction effluent was separated to produce light fraction I and heavy fraction I. The resulting heavy fraction I was sent to a second hydrogenation cracking unit, and reacted by contacting a hydrotreating catalyst (treating agent). The resulting reaction effluent was separated to produce light fraction II and heavy fraction II. The specific reaction conditions and product properties are shown in Table 4.

[0162] In the reaction process of this example, the aromatics saturation rate in the hydrotreating unit was controlled to 50%, the conversion of >350? C. fraction in the first hydrogenation cracking unit was controlled to 49.4%, and the conversion of >350? C. fraction in the second hydrogenation cracking unit was controlled to 20%.

[0163] It can be seen from Table 4 that the obtained light fraction I had a content of paraffins of 92.7 wt %, and could be used as a high-quality feedstock for producing ethylene by steam cracking; the obtained light fraction II had a content of naphthenes+aromatics of 62.0 wt %, and could be used as a high-quality reforming feedstock; the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 82.8 wt %; the (280-370? C.) fraction of the obtained heavy fraction II had a condensation point of <?50? C., a kinematic viscosity @40? C. of 6.944 mm.sup.2/s, and a polycyclic aromatics (PCA) content of less than 3.0%, and could be used as transformer oil; the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 77.8 wt %, and a condensation point of ?38? C., and could be used as a high-quality naphthenic speciality oil, such as refrigerator oil.

Comparative Example 1 and Comparative Example 2

[0164] Comparative Example 1 and Comparative Example 2 used the same process as Example 1 except that, in Comparative Example 1, the first hydrogenation cracking unit was loaded with a Y-type molecular sieve-containing hydrogenation cracking catalyst (cracking agent 2); in Comparative Example 2, the first hydrogenation cracking unit was loaded with ?-type molecular sieve-containing hydrogenation cracking catalyst (cracking agent 3). The reactions were carried out while controlling the aromatics saturation rate in the hydrotreating unit, the conversion of >350? C. fraction in the first hydrogenation cracking unit and the conversion of >350? C. fraction in the second hydrogenation cracking unit to the conditions similar to those in Example 1. The specific reaction conditions and product properties are shown in Table 4.

[0165] It can be seen from Table 4 that the light fraction I products of Comparative Example 1 and Comparative Example 2 had the contents of paraffins of 54.9 wt % and 47.9 wt % respectively; the light fraction II products had the contents of naphthenes+aromatics of 60.1 wt % and 58.6 wt % respectively, the >350? C. fractions of the heavy fraction I products had the contents of naphthenes+aromatics of 59.0 wt % and 72.4 wt % respectively, the >350? C. fractions of the heavy fraction II products had the contents of naphthenes+aromatics of 54.0 wt % and 68.2 wt % respectively, and the condensation points of +28? C. and +8? C. respectively.

[0166] The above results showed that by using traditional hydrocracking implementations with the Y-type or ?-type molecular sieve catalyst, it was difficult to achieve efficient and selective conversion of feedstocks into paraffins and naphthenes. However, using the process of the present invention can realize the directional conversion of gas oil feedstocks according to the chain structure and the ring structure, thereby achieving the production of high-quality chemical raw materials and high-value-added naphthenic speciality oil.

Example 2

[0167] A gas oil feedstock was reacted by successively contacting a hydrogenation protection agent (protection agent), a hydrodemetallization catalyst (demetallization agent), and a hydrorefining catalyst (refining catalyst) in a hydrotreating unit. The resulting reaction effluent was sent to the first hydrogenation cracking unit, and reacted by contacting a ZSM-5 molecular sieve-containing hydrogenation cracking catalyst I (cracking agent 1). The resulting reaction effluent was separated to produce light fraction I, middle fraction I and heavy fraction I. The resulting middle fraction I was sent to a fractionation column of a second hydrogenation cracking unit for fractionation. The resulting heavy fraction I was sent to the second hydrogenation cracking unit, and reacted by contacting a hydrotreating catalyst (treating agent). The resulting reaction effluent was separated to produce light fraction II and heavy fraction II. The specific reaction conditions and product properties are shown in Table 5.

[0168] In the reaction process of this example, the aromatics saturation rate in the hydrotreating unit was controlled to 38.6%, the conversion of >350? C. fraction in the first hydrogenation cracking unit was controlled to 47.1%, and the conversion of >350? C. fraction in the second hydrogenation cracking unit was controlled to 5%.

[0169] It can be seen from Table 5 that the obtained light fraction I had a content of paraffins of 91.74 wt %, and could be used as a high-quality feedstock for producing ethylene by steam cracking; the obtained light fraction II had a content of naphthenes+aromatics of 61.55 wt %, and could be used as a high-quality reforming feedstock; the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 84.7 wt %; the (280-370? C.) fraction of the obtained heavy fraction II had a condensation point of <?50? C., a kinematic viscosity@40? C. of 7.790 mm.sup.2/s, and a polycyclic aromatics (PCA) content of less than 3.0%, and could be used as transformer oil; the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 81.7 wt %, and a condensation point of ?38? C., and could be used as a high-quality naphthenic speciality oil, such as refrigerator oil.

Example 3

[0170] The same process as that of Example 2 was used. The specific reaction conditions and product properties are shown in Table 5.

[0171] In the reaction process of this example, the aromatics saturation rate in the hydrotreating unit was controlled to 56.4%, the conversion of >350? C. fraction in the first hydrogenation cracking unit was controlled to 44.4%, and the conversion of >350? C. fraction in the second hydrogenation cracking unit was controlled to 5%.

[0172] It can be seen from Table 5 that the obtained light fraction I had a content of paraffins of 90.18 wt %, and could be used as a high-quality feedstock for producing ethylene by steam cracking; the obtained light fraction II had a content of naphthenes+aromatics of 60.82 wt %, and could be used as a high-quality reforming feedstock; the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 83.5 wt %; the (280-370? C.) fraction of the obtained heavy fraction II had a condensation point of <?50? C., a kinematic viscosity@40? C. of 7.065 mm.sup.2/s, and a polycyclic aromatics (PCA) content of less than 3.0%, and could be used as transformer oil; the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 80.5 wt %, and a condensation point of ?38? C., and could be used as a high-quality naphthenic speciality oil, such as refrigerator oil.

Comparative Example 3

[0173] The same process as that of Example 2 was used, except that the aromatics saturation rate in the hydrotreating unit was controlled to 59.2%. The specific reaction conditions and product properties are shown in Table 5.

[0174] It can be seen from Table 5 that the obtained light fraction I had a content of paraffins of 86.08 wt %, the obtained light fraction II had a content of naphthenes+aromatics of 56.42 wt %; the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 81.3 wt %, the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 79.8 wt %, and a condensation point of ?38? C.

[0175] The above results showed that this Comparative Example did not adopt the preferred range of the present invention. Increasing the aromatics saturation rate in the hydrotreating unit would lead to an increase in the ring-opening cracking reaction of naphthenes in the first hydrogenation cracking unit, which would have an adverse influence on the reaction effect of the directional conversion of gas oil feedstock according to the chain structure and the ring structure.

Example 4

[0176] A gas oil feedstock was reacted by successively contacting a hydrogenation protection agent (protection agent), a hydrodemetallization catalyst (demetallization agent), and a hydrorefining catalyst (refining catalyst) in a hydrotreating unit. The resulting reaction effluent was sent to the first hydrogenation cracking unit, and reacted by contacting a ZSM-5 molecular sieve-containing hydrogenation cracking catalyst I (cracking agent 1). The resulting reaction effluent was separated to produce light fraction I and heavy fraction I. The resulting heavy fraction I was sent to a second hydrogenation cracking unit, and reacted by contacting a hydrogenation cracking catalyst II (cracking agent 4). The resulting reaction effluent was separated to produce light fraction II and heavy fraction II. The specific reaction conditions and product properties are shown in Table 6.

[0177] In the reaction process of this example, the aromatics saturation rate in the hydrotreating unit was controlled to 38.6%, the conversion of >350? C. fraction in the first hydrogenation cracking unit was controlled to 47.1%, and the conversion of >350? C. fraction in the second hydrogenation cracking unit was controlled to 56.25%.

[0178] It can be seen from Table 6 that the obtained light fraction I had a content of paraffins of 91.74 wt %, and could be used as a high-quality feedstock for producing ethylene by steam cracking; the obtained light fraction II had a content of naphthenes+aromatics of 64.37 wt %, and could be used as a high-quality reforming feedstock; the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 84.7 wt %; the (280-370? C.) fraction of the obtained heavy fraction II had a condensation point of <?50? C., a kinematic viscosity a 40? C. of 7.801 mm.sup.2/s, and a polycyclic aromatics (PCA) content of less than 3.0%, and could be used as transformer oil; the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 65.1 wt %, and a condensation point of ?38? C., and could be used as a high-quality naphthenic speciality oil, such as refrigerator oil.

Example 5

[0179] The same process as that of Example 4 was used. The specific reaction conditions and product properties are shown in Table 6.

[0180] In the reaction process of this example, the aromatics saturation rate in the hydrotreating unit was controlled to 38.6%, the conversion of >350? C. fraction in the first hydrogenation cracking unit was controlled to 47.1%, and the conversion of >350? C. fraction in the second hydrogenation cracking unit was controlled to 72.4%.

[0181] It can be seen from Table 6 that the obtained light fraction I had a content of paraffins of 91.74 wt %, and could be used as a high-quality feedstock for producing ethylene by steam cracking; the obtained light fraction II had a content of naphthenes+aromatics of 59.64 wt %, and could be used as a high-quality reforming feedstock; the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 84.7 wt %; the (280-370? C.) fraction of the obtained heavy fraction II had a condensation point of <?50? C., a kinematic viscosity (40? C. of 6.725 mm.sup.2/s, and a polycyclic aromatics (PCA) content of less than 3.0%, and could be used as transformer oil; the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 63.0 wt %, and a condensation point of ?35? C., and could be used as a high-quality naphthenic speciality oil, such as refrigerator oil.

Comparative Example 4

[0182] The same process as that of Example 4 was used, except that in the second hydrogenation cracking unit, a higher conversion of >350? C. fraction was used (88.5%). The specific reaction conditions and product properties are shown in Table 6.

[0183] It can be seen from Table 6 that with the process of this Comparative Example, the content of paraffins in the light fraction I product was also 91.74 wt %; but the content of naphthenes+aromatics in the light fraction II product was only 55.9 wt %, and the >350? C. fraction of the heavy fraction II product had the content of naphthenes+aromatics of 43.9 wt % and a condensation point of ?30.0? C. The properties of the product could not meet the quality requirements of high-quality naphthenic speciality oil.

[0184] The above results showed that controlling the second hydrogenation cracking unit to an excessively high conversion of >350? C. fraction would not only reduce the content of naphthenes and aromatics in the light fraction II, but also cause the quality index of the heavy fraction II product to fail to meet the quality requirements of naphthenic specialty oil.

Comparative Example 5

[0185] The same process as that of Example 4 was used, except that in the first hydrogenation cracking unit, a higher conversion of >350? C. fraction was used (65%). The specific reaction conditions and product properties are shown in Table 6.

[0186] It can be seen from Table 6 that with the process of this Comparative Example, the content of paraffins in the light fraction I product was 88.25 wt %; the content of naphthenes+aromatics in the light fraction II product was 61.36 wt %, the >350? C. fraction of the obtained heavy fraction I had a content of naphthenes+aromatics of 80.4 wt %, the >350? C. fraction of the obtained heavy fraction II had a content of naphthenes+aromatics of 59.9 wt % and a condensation point of ?45? C. It should be noted that although controlling a higher conversion in the first hydrogenation cracking unit could also obtain products with qualified properties, when the conversion in the first hydrogenation cracking unit was too high, the mass fraction of the low carbon light hydrocarbons (C3+C4) product was as high as 18.5 wt %, the chemical hydrogen consumption of the reaction was too high, and the target product distribution was unreasonable.

[0187] The above results showed that the reaction process was uneconomical when a too high conversion of >350? C. fraction was controlled in the first hydrogenation cracking unit.

Example 6, Comparative Examples 6-7

[0188] A gas oil feedstock was reacted by successively contacting a hydrogenation protection agent (protection agent), a hydrodemetallization catalyst (demetallization agent), and a hydrorefining catalyst (refining catalyst) in a hydrotreating unit, the resulting reaction effluent was sent to the first hydrogenation cracking unit, and reacted by contacting a ZSM-5 molecular sieve-containing hydrogenation cracking catalyst I (cracking agents 5-7). The resulting reaction effluent was separated to produce light fraction I and heavy fraction I. The resulting heavy fraction I was sent to a second hydrogenation cracking unit, and reacted by contacting a hydrotreating catalyst (treating agent). The resulting reaction effluent was separated to produce light fraction II and heavy fraction II. The specific reaction conditions and product properties are shown in Table 7.

[0189] If the molecular sieve content was too low, the conversion of paraffins would be insufficient. However, if the molecular sieve content was too low or too high, there would be problems with high ring-opening rates of naphthenes and aromatics. If the molecular sieve content was too high, there would also be a problem of high content of light hydrocarbons in the by-products.

Example 7

[0190] The same process as that of Example 6 was used, except that other molecular sieves such as IM-5 and ZSM-48 were used instead of ZSM-5 to obtain products with qualified properties.

[0191] Table 8 lists the product quality indicators of transformer oil and refrigerator oil.

TABLE-US-00001 TABLE 1 Intermediate-base Item VGO feedstock Density (20? C.)/(g/cm.sup.3) 0.9091 Sulfur/wt % 2.19 Nitrogen/?g .Math. g.sup.?1 703 Distillation range/? C. IBP/50%/95% 305/415/482 >350? C. fraction mass fraction, % 90.0 hydrocarbon composition/mass % paraffins 20.4 monocycloparaffins 7.0 dicycloparaffins 10.3 tricycloparaffins 7 tetracycloparaffins 3.9 pentacycloparaffins 1.3 hexacycloparaffins 0.1 total naphthenes 29.6 monocyclic aromatics 21.9 bicyclic aromatics 11.5 tricyclic aromatics 3.9 tetracyclic aromatics 1.8 pentacyclic aromatics 0.5 total thiophene + unidentified aromatics 9.4 total aromatics 50.0 total weight 100.0 A (mass fraction of paraffins in gas oil feedstock) 20.4 B (sum of mass fractions of paraffins, monocyclo- 49.3 paraffins and monocyclic aromatics in gas oil feedstock)

TABLE-US-00002 TABLE 2 protection demetallization refining Item agent agent catalyst treating agent Brand name RG-30A/B RAM-100 RJW-3 RN-32V Metal Ni/Mo Ni/Mo Ni/Mo/W Ni/Mo/W NiO, wt % 0.5-1.5 ?1 ?3 ?2.4 MoO.sub.3, wt % 2-6 ?6 ?1 ?2.3 WO.sub.3, wt % / / ?26 ?23.0 support alumina alumina alumina alumina and silica-alumina

TABLE-US-00003 TABLE 3 cracking cracking cracking cracking cracking cracking cracking Item agent 1 agent 2 agent 3 agent 4 agent 5 agent 6 agent 7 Metal NiW NiW NiW NiMo NiW NiW NiW NiO, wt % ?4 ?3 ?2.5 ?4.5 ?4 ?4 ?4 MoO.sub.3, wt % / / / ?15.5 / / / WO.sub.3, wt % ?18 ?23 ?25 / ?18 ?18 ?18 molecular ZSM-5 Y ? Y ZSM-5 ZSM-5 ZSM-5 sieve type molecular 35 15 15 30 45 5 80 sieve content, wt % pore size/nm 0.5 0.7 0.8 0.7 0.5 0.5 0.5

TABLE-US-00004 TABLE 4 Comparative Comparative Item Example 1 Example 1 Example 2 feedstock Intermediate-base VGO feedstock catalyst hydrotreating unit (catalyst loading volume VRG-30A/VRG-30B/VRAM-10/ ratio) VRJW-3 = 5:8:8:77 first hydrogenation cracking unit cracking cracking cracking agent 1 agent 2 agent 3 second hydrogenation cracking unit treating treating treating agent agent agent process condition parameters hydrogen partial pressure of hydrotreating 14.0 14.0 14.0 unit/MPa hydrogen partial pressure of first 14.0 14.0 14.0 hydrogenation cracking unit/MPa hydrogen partial pressure of second 14.0 14.0 14.0 hydrogenation cracking unit/MPa reaction temperature of hydrotreating unit/? C. 365 365 365 reaction temperature of first hydrogenation 375 370 370 cracking unit/? C. reaction temperature of second hydrogenation 375 375 375 cracking unit/? C. protection agent LHSV/h.sup.?1 12.7 12.7 12.7 demetallization agent LHSV/h.sup.?1 22.3 22.3 22.3 refining catalyst LHSV/h.sup.?1 1.0 1.0 1.0 LHSV of first hydrogenation cracking 1.4 1.4 1.4 unit/h.sup.?1 LHSV of second hydrogenation cracking 3.0 3.0 3.0 unit/h.sup.?1 H.sub.2/oil ratio by volume of hydrotreating unit 800 800 800 H.sub.2/oil ratio by volume of first hydrogenation 1200 1200 1200 cracking unit H.sub.2/oil ratio by volume of second 1200 1200 1200 hydrogenation cracking unit nitrogen content of liquid phase product in 7.2 10.0 9.0 hydrotreating unit/(?g/g) aromatics saturation rate of feedstock in 50 50 50 hydrotreating unit/% stream sent to first hydrogenation cracking unit for treatment aromatics mass content(wt %) 25.0 25.0 25.0 monocyclic aromatics content(wt %), 19.38 19.38 19.38 based on 100 wt % aromatics content stream sent to second hydrogenation cracking unit for treatment sum of naphthenes and aromatics 81.03 69.61 72.52 contents(wt %) conversion of >350? C. fraction in first 49.4 51.8 50.7 hydrogenation cracking unit/% conversion of paraffins in first hydrogenation 66.76 10.95 40.05 cracking unit/% conversion of naphthenes + aromatic in first 52.8 68.6 61.2 hydrogenation cracking unit/% conversion of >350? C. fraction in second 20 21 22 hydrogenation cracking unit/% product yield and properties low carbon light hydrocarbon 10.7 0.8 1.4 yield/weight %(C3 + C4) light fraction I yield/weight % 8.62 3.66 3.9 distillation range (IBP-FBP)/? C. 30-100 30-100 30-100 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 92.7 54.9 47.9 naphthenes + aromatics 7.3 45.1 52.1 heavy fraction I yield/weight % 80.68 95.54 94.70 mass fraction of >350? C. fraction in heavy 56.43 45.36 46.82 fraction I/% Hydrocarbon compoition of >350? C. fraction of heavy fraction I/% paraffins 17.2 41.0 27.6 naphthenes + aromatics 82.8 59.0 72.4 light fraction II yield/weight % 4.0 13.40 11.80 distillation range (IBP-FBP)/? C. 65-175 65-175 65-175 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 38.1 39.9 41.4 naphthenes + aromatics 62.0 60.1 58.6 heavy fraction II yield/weight % 76.68 82.14 82.90 mass fraction of (280-370? C.) fraction of 33.92 31.45 34.27 heavy fraction II/% condensation point/? C. <?50 ?18 ?36 kinematic viscosity@40? C./(mm.sup.2/s) 6.944 5.116 5.512 polycyclic aromatics (PCA) content/% <3.0 <3.0 <3.0 mass fraction of >350? C. fraction of heavy 47.60 41.64 41.62 fraction II/% condensation point of >350? C. fraction of ?38 +28 +8 heavy fraction II/? C. kinematic viscosity@100? C. of >350? C. 5.216 4.167 4.139 fraction of heavy fraction II/(mm.sup.2/s) hydrocarbon composition of >350? C. fraction of heavy fraction II/% paraffins 22.2 46.0 31.8 naphthenes 77.5 53.8 67.8 aromatics 0.3 0.2 0.4 polycyclic aromatics (PCA) content,% <3.0 <3.0 <3.0

TABLE-US-00005 TABLE 5 Comparative Item Example 2 Example 3 Example 3 feedstock Intermediate-base VGO feedstock catalyst hydrotreating unit (catalyst loading VRG-30A/VRG-30B/VRAM-10/ volume ratio) VRJW-3 = 5:8:8:77 first hydrogenation cracking unit cracking cracking cracking agent 1 agent 1 agent 1 second hydrogenation cracking unit treating treating treating agent agent agent process condition parameters hydrogen partial pressure of hydrotreating 11.0 14.0 14.0 unit/MPa hydrogen partial pressure of first hydrogenation 11.0 14.0 14.0 cracking unit/MPa hydrogen partial pressure of second 11.0 14.0 14.0 hydrogenation cracking unit/MPa reaction temperature of hydrotreating unit/? C. 365 365 365 reaction temperature of first hydrogenation 375 365 355 cracking unit/? C. reaction temperature of second hydrogenation 375 365 355 cracking unit/? C. protection agent LHSV/h.sup.?1 12.7 12.7 12.7 demetallization agent LHSV/h.sup.?1 22.3 22.3 22.3 refining catalyst LHSV/h.sup.?1 1.0 1.0 1.0 LHSV of first hydrogenation cracking unit/h.sup.?1 1.4 1.4 1.4 LHSV of second hydrogenation cracking unit/h.sup.?1 3.0 3.0 3.0 H.sub.2/oil ratio by volume of hydrotreating 800 800 800 H.sub.2/oil ratio by volume of first hydrogenation 1200 1200 1200 cracking unit H.sub.2/oil ratio by volume of second hydrogenation 1200 1200 1200 cracking unit nitrogen content of liquid phase product in 16.92 7.2 9.0 hydrotreating unit/(?g/g) aromatics saturation rate of feedstock in 38.6 56.4 59.2 hydrotreating unit/% stream sent to first hydrogenation cracking unit for treatment aromatics mass content(wt %) 30.7 21.8 20.4 monocyclic aromatics content(wt %), based 23.3 16.9 15.6 on 100 wt % aromatics content stream sent to second hydrogenation cracking unit for treatment sum of naphthenes and aromatics 84.47 80.03 77.72 contents(wt %) conversion of >350? C. fraction in first 47.1 44.4 39.8 hydrogenation cracking unit/% conversion of paraffins in first hydrogenation 66.8 60.97 54.7 cracking unit/% conversion of naphthenes + aromatic in first 52.85 49.38 49.53 hydrogenation cracking unit/% conversion of >350? C. fraction in second 5 5 5 hydrogenation cracking unit/% product yield and properties low carbon light hydrocarbon 13.26 7.26 7.24 yield/weight %(C3 + C4) light fraction I yield/weight % 6.41 5.25 3.61 distillation range (IBP-FBP)/? C. 30-100 30-100 30-100 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 91.74 90.18 86.08 naphthenes + aromatics 8.26 9.82 13.92 heavy fraction I yield/weight % 80.33 87.49 89.15 mass fraction of >350? C. fraction in heavy 59.29 57.21 60.79 fraction I/% Hydrocarbon compoition of >350? C. fraction of heavy fraction I/% paraffins 15.3 16.5 18.7 naphthenes + aromatics 84.7 83.5 81.3 light fraction II yield/weight % 2.61 3.63 3.06 distillation range (IBP-FBP)/? C. 65-175 65-175 65-175 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 38.45 39.18 43.58 naphthenes + aromatics 61.55 60.82 56.42 heavy fraction II yield/weight % 77.72 83.86 86.09 mass fraction of (280-370? C.) fraction of heavy 33.35 32.1 33.25 fraction II/% condensation point/? C. <?50 <?50 <?50 kinematic viscosity@40? C./(mm.sup.2/s) 7.790 7.065 6.254 polycyclic aromatics (PCA) content/% <3.0 <3.0 <3.0 mass fraction of >350? C. fraction of heavy 58.22 56.70 59.80 fraction II/% condensation point of >350? C. fraction of heavy ?38 ?38 ?38 fraction II/? C. kinematic viscosity@100? C. of >350? C. fraction 5.558 5.370 5.630 of heavy fraction II/(mm.sup.2/s) hydrocarbon composition of >350? C. fraction of heavy fraction II/% paraffins 18.3 19.5 20.2 naphthenes 76.4 79.1 75.4 aromatics 5.3 1.4 4.4 polycyclic aromatics (PCA) content, % <3.0 <3.0 <3.0

TABLE-US-00006 TABLE 6 Comparative Comparative Item Example 4 Example 5 Example 4 Example 5 feedstock Intermediate-base VGO feedstock catalyst hydrotreating unit (catalyst loading VRG-30A/VRG-30B/VRAM-10/ volume ratio) VRJW-3 = 5:8:8:77 first hydrogenation cracking unit cracking cracking cracking cracking agent 1 agent 1 agent 1 agent 1 second hydrogenation cracking unit cracking cracking cracking cracking agent 4 agent 4 agent 4 agent 4 process condition parameters hydrogen partial pressure of 11.0 11.0 11.0 11.0 hydrotreating unit/MPa hydrogen partial pressure of first 11.0 11.0 11.0 11.0 hydrogenation cracking unit/MPa hydrogen partial pressure of second 11.0 11.0 11.0 11.0 hydrogenation cracking unit/MPa reaction temperature of hydrotreating 365 365 365 365 unit/? C. reaction temperature of first 375 375 375 400 hydrogenation cracking unit/? C. reaction temperature of second 353 380 380 353 hydrogenation cracking unit/? C. protection agent LHSV/h.sup.?1 12.7 12.7 12.7 12.7 demetallization agent LHSV/h.sup.?1 22.3 22.3 22.3 22.3 refining catalyst LHSV/h.sup.?1 1.0 1.0 1.0 1.0 LHSV of first hydrogenation 1.4 1.4 1.4 1.4 cracking unit/h.sup.?1 LHSV of second hydrogenation 2.0 3.0 2.5 2.0 cracking unit/h.sup.?1 H.sub.2/oil ratio by volume of 800 800 800 800 hydrotreating H.sub.2/oil ratio by volume of first 1200 1200 1200 1200 hydrogenation cracking unit H.sub.2/oil ratio by volume of second 1200 1200 1200 1200 hydrogenation cracking unit nitrogen content of liquid phase 16.92 16.92 16.92 16.92 product in hydrotreating unit/(?g/g) aromatics saturation rate of feedstock 38.6 38.6 38.6 38.6 in hydrotreating unit/% stream sent to first hydrogenation cracking unit for treatment aromatics mass content(wt %) 30.7 30.7 30.7 30.7 monocyclic aromatics 23.3 23.3 23.3 23.3 content(wt %), based on 100 wt % aromatics content stream sent to second hydrogenation cracking unit for treatment sum of naphthenes and 84.47 84.47 84.47 76.57 aromatics contents(wt %) conversion of >350? C. fraction in first 47.1 47.1 47.1 65 hydrogenation cracking unit/% conversion of paraffins in first 66.8 66.8 66.8 68.3 hydrogenation cracking unit/% conversion of naphthenes + aromatic 52.85 52.85 52.85 70.5 in first hydrogenation cracking unit/% conversion of >350? C. fraction in 56.25 72.40 88.50 56.25 second hydrogenation cracking unit/% product yield and properties low carbon light hydrocarbon 13.26 13.26 13.26 18.5 yield/weight %(C3 + C4) light fraction I yield/weight % 6.41 5.41 6.41 11.0 distillation range (IBP-FBP)/? C. 30-100 30-100 30-100 30-100 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 91.74 91.74 91.74 88.25 naphthenes + aromatics 8.26 8.26 8.26 11.75 heavy fraction I yield/weight % 80.33 80.33 80.33 70.50 mass fraction of >350? C. fraction in 59.29 59.29 59.29 44.68 heavy fraction I/% Hydrocarbon compoition of >350? C. fraction of heavy fraction I/% paraffins 15.3 15.3 15.3 19.6 naphthenes + aromatics 84.7 84.7 84.7 80.4 light fraction II yield/weight % 9.74 17.66 22.55 5.8 distillation range (IBP-FBP)/? C. 65-175 65-175 65-175 65-175 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 35.63 40.36 43.33 39.64 naphthenes + aromatics 64.37 59.64 55.9 61.36 heavy fraction II yield/weight % 70.59 62.67 57.78 64.70 mass fraction of (280-370? C.) fraction 32.24 35.25 37.11 33.24 of heavy fraction II/% condensation point/? C. <?50 <?50 <?50 <?50 kinematic viscosity@40? C./(mm.sup.2/s) 7.801 6.725 6.023 7.814 polycyclic aromatics (PCA) <3.0 <3.0 <3.0 <3.0 content/% mass fraction of >350? C. fraction of 29.52 20.97 9.48 21.33 heavy fraction II/% condensation point of >350? C. ?38 ?35 ?30 ?45 fraction of heavy fraction II/? C. kinematic viscosity@100? C. of >350? C. 5.561 4.721 4.326 5.732 fraction of heavy fraction II/(mm.sup.2/s) hydrocarbon composition of >350? C. fraction of heavy fraction II/% paraffins 34.9 37.0 56.1 40.1 naphthenes 63.4 60.6 41.8 57.5 aromatics 1.7 2.4 2.1 2.4 polycyclic aromatics (PCA) <3.0 <3.0 <3.0 <3.0 content, %

TABLE-US-00007 TABLE 7 Comparative Comparative Item Example 6 Example 6 Example 7 feedstock Intermediate-base VGO feedstock catalyst hydrotreating unit (catalyst loading volume ratio) VRG-30A/VRG-30B/VRAM-10/ VRJW-3 = 5 :8:8:77 first hydrogenation cracking unit cracking cracking cracking agent 5 agent 6 agent 7 second hydrogenation cracking unit treating treating treating agent agent agent process condition parameters hydrogen partial pressure of hydrotreating unit/MPa 14 14 14 hydrogen partial pressure of first hydrogenation 14 14 14 cracking unit/MPa hydrogen partial pressure of second hydrogenation 14 14 14 cracking unit/MPa reaction temperature of hydrotreating unit/? C. 365 365 365 reaction temperature of first hydrogenation cracking 370 400 350 unit/? C. reaction temperature of second hydrogenation 365 365 350 cracking unit/? C. protection agent LHSV/h.sup.?1 12.7 12.7 12.7 demetallization agent LHSV/h.sup.?1 22.3 22.3 22.3 refining catalyst LHSV/h.sup.?1 1.0 1.0 1.0 LHSV of first hydrogenation cracking unit/h.sup.?1 1.4 1.4 1.4 LHSV of second hydrogenation cracking unit/h.sup.?1 3.0 3.0 3.0 H.sub.2/oil ratio by volume of hydrotreating 800 800 800 H.sub.2/oil ratio by volume of first hydrogenation 1200 1200 1200 cracking unit H.sub.2/oil ratio by volume of second hydrogenation 1200 1200 1200 cracking unit nitrogen content of liquid phase product in 8.5 8.5 8.6 hydrotreating unit/(?g/g) aromatics saturation rate of feedstock in 50 50 50 hydrotreating unit/% stream sent to first hydrogenation cracking unit for treatment aromatics mass content(wt %) 25.0 25.0 25.0 monocyclic aromatics content(wt %), based on 19.38 19.38 19.38 100 wt % aromatics content stream sent to second hydrogenation cracking unit for treatment sum of naphthenes and aromatics 81.53 73.81 71.7 contents(wt %) conversion of >350? C. fraction in first hydrogenation 49.4 48.5 50.5 cracking unit/% conversion of paraffins in first hydrogenation 66.76 52.4 66.76 cracking unit/% conversion of naphthenes + aromatic in first 52.8 68.5 69.5 hydrogenation cracking unit/% conversion of >350? C. fraction in second 20 20 20 hydrogenation cracking unit/% product yield and properties low carbon light hydrocarbon 10.8 8.5 15.6 yield/weight %(C3 + C4) light fraction I yield/weight % 8.52 9.20 8.2 distillation range (IBP-FBP)/? C. 30-100 30-100 30-100 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 93.0 85.2 86.0 naphthenes + aromatics 7.0 14.8 14.0 heavy fraction I yield/weight % 80.68 82.30 76.2 mass fraction of >350? C. fraction in heavy fraction 56.43 56.31 58.46 I/% Hydrocarbon compoition of >350? C. fraction of heavy fraction I/% paraffins 17.0 24.0 26.0 naphthenes + aromatics 83.0 76.0 74.0 light fraction II yield/weight % 4.2 3.85 4.6 distillation range (IBP-FBP)/? C. 65-175 65-175 65-175 hydrocarbon composition (PONA)/% paraffins (n- + iso-paraffins) 37.1 42.0 40.0 naphthenes + aromatics 63 58.0 60.0 heavy fraction II yield/weight % 76.48 78.45 71.6 mass fraction of (280-370? C.) fraction of heavy 33.90 34.45 34.30 fraction II/% condensation point/? C. <?50 ?35 ?40 kinematic viscosity@40? C./(mm.sup.2/s) 6.964 6.716 6.810 polycyclic aromatics (PCA) content/% <3.0 <3.0 <3.0 mass fraction of >350? C. fraction of heavy fraction II 47.62 47.26 49.78 1% condensation point of >350? C. fraction of heavy ?40 ?28 ?38 fraction II/? C. kinematic viscosity@100? C. of >350? C. fraction of 5.226 5.167 5.250 heavy fraction II/(mm.sup.2/s) hydrocarbon composition of >350? C. fraction of heavy fraction II/% paraffins 21.2 27.0 26.0 naphthenes 78.5 72.8 73.7 aromatics 0.3 0.2 0.3 polycyclic aromatics (PCA) content, % <3.0 <3.0 <3.0

TABLE-US-00008 TABLE 8 naphthenic speciality oil I GB 2536-2011 Fluids for electrotechnical applications-unused mineral insulating oils for naphthenic speciality oil II transformers and switchgear GB/T 16630 refrigerator oil product brand product brand kinematic viscosity/ ?40? C. transformer kinematic viscosity/ (mm.sup.2/s) oil (mm.sup.2/s) 40? C. ?12 40? C. 6.12-500 0? C. 100? C. report flash point (closed)/? C. ?135 flash point (closed)/? C. ?130 pour point/? C. ?-40? C. pour point/? C. ?-18/?15/?10? C. polycyclic aromatics (PCA) <3.0 content/%