METHOD FOR PRODUCING OIL-BASED COMPONENTS

Abstract

A method of producing oil-based components is disclosed which includes providing VGO and slack wax; combining the VGO as a major component and the slack wax as a minor component to provide a feedstock; subjecting the feedstock to hydrocracking to provide a first effluent; fractionating the first effluent to provide at least a bottom fraction and a middle distillate fraction; recovering the bottom fraction and the middle distillate fraction. A method for improving a viscosity index of base oil includes subjecting the bottom fraction to a dewaxing step to provide a second effluent; fractionating the second effluent to provide at least a middle distillate and base oil; and recovering the middle distillate and the base oil.

Claims

1. A method of producing oil-based components, comprising: providing VGO and slack wax; combining the VGO as a major component and the slack wax as a minor component to provide a feedstock; subjecting the feedstock to hydrocracking to provide a first effluent; fractionating the first effluent to provide at least a bottom fraction and a middle distillate fraction; and recovering the bottom fraction and the middle distillate fraction.

2. The method of claim 1, comprising: subjecting the bottom fraction to dewaxing to provide a second effluent; fractionating the second effluent to provide at least a middle distillate and base oil; and recovering the middle distillate and the base oil.

3. A method for improving a viscosity index of base oil, comprising: providing VGO and slack wax; combining the VGO as a major component and the slack wax as a minor component to provide a feedstock; subjecting the feedstock to a hydrocracking step to provide a first effluent; fractionating the first effluent to provide at least a bottom fraction and a middle distillate fraction; subjecting the bottom fraction to dewaxing to provide a second effluent; fractionating the second effluent to provide at least a middle distillate and base oil; and recovering the middle distillate and the base oil.

4. The method of claim 1, wherein the feedstock comprises: at most about 30 wt. % slack wax, including at most about 25 wt. %, more specifically at most about 20 wt. %, even more specifically 1-25 wt. %, still even more specifically 10-20 wt. %, a balance being the VGO.

5. The method of claim 1, comprising: providing the slack wax as unpurified slack wax obtained from solvent dewaxing of a waxy petroleum feed.

6. The method of claim 1, wherein the feedstock comprises: at most about 0.18 wt. % nitrogen, at most about 2 wt. % sulphur, and about 45 wt. % aromatic compounds.

7. The method of claim 1, comprising: subjecting the feedstock is subjected to hydrotreatment before the hydrocracking.

8. The method of claim 1, wherein a conversion level in the hydrocracking is in a range of about 55% to about 75%, specifically including about 56%.

9. The method of claim 1, wherein the bottom fraction has a boiling temperature above 370 C.

10. The method of claim 1, wherein a boiling range of the middle distillate fraction and the middle distillate is about 300 C. to about 370 C.

11. The method of claim 2, wherein a viscosity index of the base oil is increased by more than about 10 units compared to that of base oil prepared from VGO without wax.

12. An arrangement for producing oil-based components, the arrangement comprising: a hydrocracking reactor (A) for cracking a waxy feed to provide a first effluent, said hydrocracking reactor (A) having at least one inlet for supplying a feedstock to the hydrocracking reactor (A) and an outlet for discharging the first effluent from the hydrocracking reactor (A); a first distiller (B) in a flow connection with the hydrocracking reactor (A) for fractioning the first effluent to provide at least a bottom fraction (HCB) and a middle distillate fraction (MD), the first distiller (B) being arranged downstream of the hydrocracking reactor (A); a dewaxing unit (C) in a flow connection with the first distiller (B) for dewaxing the bottom fraction (HCB) to provide a second effluent, the dewaxing unit (C) being arranged downstream of the first distiller (B); and a second distiller (D) in a flow connection with the dewaxing unit (C) for fractioning the second effluent to provide at least a middle distillate (MD) and base oil, the second distiller (D) being arranged downstream of the dewaxing unit (C) and having at least one outlet for discharging the middle distillate (MD) and the base oil.

13. The arrangement of claim 12, wherein the hydrocracker reactor is a fixed bed hydrocracker.

14. The method of claim 3, wherein the feedstock comprises: at most about 30 wt. % slack wax, including at most about 25 wt. %, more specifically at most about 20 wt. %, even more specifically 1-25 wt. %, still even more specifically 10-20 wt. %, a balance being the VGO.

15. The method of claim 3, comprising: providing the slack wax as unpurified slack wax obtained from solvent dewaxing of a waxy petroleum feed.

16. The method of claim 3, wherein the feedstock comprises: at most about 0.18 wt. % nitrogen, at most about 2 wt. % sulphur, and about 45 wt. % aromatic compounds.

17. The method of claim 3, comprising: subjecting the feedstock to hydrotreatment before the hydrocracking.

18. The method of claim 3, wherein a conversion level in the hydrocracking is in a range of about 55% to about 75%, including about 56%.

19. The method of claim 3, wherein the bottom fraction has a boiling temperature above 370 C.

20. The method of claim 3, wherein a boiling range of the middle distillate fraction and the middle distillate is about 300 C. to about 370 C.

21. The method of claim 3, wherein a viscosity index of the base oil is increased by more than about 10 units compared to that of base oil prepared from VGO without wax.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows schematically an embodiment of the method of the invention.

[0037] FIG. 2 shows an effect of slack wax to the viscosity Index (VI) of base oil as a function of kinematic viscosity (KV).

DETAILED DESCRIPTION OF THE INVENTION

[0038] In an aspect, the present invention provides a method of producing oil-based components, comprising the steps of: [0039] providing VGO and slack wax; [0040] combining the VGO as a major component and the slack wax as a minor component to provide a feedstock; [0041] subjecting the feedstock to a hydrocracking step to provide a first effluent; [0042] fractionating the first effluent to provide at least a bottom fraction and a middle distillate fraction; [0043] recovering the bottom fraction and the middle distillate fraction.

[0044] In the present invention, [0045] the term slack wax means a crude wax produced by chilling and solvent fiber-pressing wax distillate: [0046] the term vacuum gas oil (VGO) means a hydrocarbon product obtained from crude oil vacuum distillation; [0047] the term Group III Base oil means paraffinic base stock which contains sulphur 0.03 wt. %, saturates 90 wt.% and has a viscosity index of 120.

[0048] Viscosity index (VI) is typically calculated from kinematic viscosities at 40 C. and at 100 C. according to standard ASTM D 2270. A high VI means that base oil has similar viscosity properties at 40 C. and at 100 C. which is a highly desired property. Low VI is not desired; it means that base oil has high viscosity at 40 C. but low at 100 C.

[0049] The feedstock suitable for use in the method of the invention typically comprises at most about 0.18 wt. % nitrogen, at most about 2 wt. % sulphur, and about 45 wt. % aromatic compounds.

[0050] The boiling range of the feedstock comprising VGO and slack wax can vary and is determined by the desired final base oil. In an embodiment, the boiling range of the feedstock is substantially in the same range as that of VGO.

[0051] Typically, slack wax contains quantities of aromatics, nitrogen and sulphur as impurities. In an embodiment of the invention, slack wax is provided as unpurified slack wax obtained from solvent dewaxing of a waxy petroleum feed.

[0052] Slack wax is combined with VGO to provide a feedstock comprising the VGO a major component and the slack wax as a minor component. Besides slack wax, the feedstock can contain minor amounts of additional wax(es). The additional wax(es) can be any kind of waxes, including synthetic wax, such as Fischer-Tropsch wax.

[0053] In an embodiment, the feedstock comprises at most about 30 wt. % slack wax. In another embodiment, the feedstock comprises at most about 25 wt. % slack wax. In still another embodiment, the feedstock comprises at most about 20 wt. % slack wax. In an embodiment, the feedstock comprises 1-25 wt. % slack wax. In another embodiment, the feedstock comprises 10-20 wt. % slack wax. In an embodiment, in each of the above separate embodiments the balance is VGO.

[0054] The feedstock comprising slack wax is subjected to a hydrocracking step. In the hydrocracking step, heteroatoms such as N and S are removed, larger long-chain hydrocarbons are cleaved into smaller short-chain hydrocarbons and/or some cyclic hydrocarbons are ring-opened to form linear and/or branched hydrocarbons. Also, dearomatization of the aromatic compounds and isomerization of the hydrocracked molecules may also occur to some extent in the process. However, the cleavage of the hydrocarbons of the wax in the hydrocracking step is not as extensive as that of VGO.

[0055] The hydrocracking is typically performed in the presence of a hydrocracking catalyst. Hydrocracking catalysts suitable for use in this step are well known to a skilled person in the arts. The hydrocracking catalyst may be arranged in one or more layers in a fixed bed. The catalyst may also be arranged in graded catalyst bed. Alternatives for suitable arrangement of the catalyst are well known to a skilled person in the art.

[0056] In an embodiment, the feedstock is first subjected to a hydrotreatment step before the hydrocracking step to remove impurities. The hydrotreatment step is carried out under conditions where any heteroatoms, such as oxygen, sulphur and/or nitrogen present in the feedstock are removed. Also aromatic compounds are typically saturated in this step. No substantial cracking of the hydrocarbons in the feedstock takes place in this step. The hydrotreatment step before hydrocracking ensures good hydrocracking performance and improves the yield of the products produced in the subsequent hydrocracking. The hydrotreatment is typically performed in the presence of a catalyst. Catalysts suitable for use in this step are well known to a skilled person in the art. The catalyst may be arranged in one or more layers in a fixed bed. The catalyst may also be arranged in graded catalyst bed. Alternatives for suitable arrangement of the catalyst are well known to a skilled person in the art.

[0057] The hydrotreatment and hydrocracking steps can be conducted in a single reactor or separate reactors. When the two steps are conducted in separate reactors, the hydrotreatment reactor is arranged upstream of the hydrocracking reactor.

[0058] The feed rate of hydrogen per feedstock in the hydrocracking step, optionally including a hydrotreatment step, is about more than 1000 L/L.

[0059] The hydrocracking is typically carried out at a pressure in the range from about 120 to about 170 bar. In an embodiment, the pressure is about 150 bar. In another embodiment, the pressure is about 132 bar.

[0060] The temperature in the hydrocracking is in the range of about 350 C. to about 450C. In an embodiment, the temperature is 400 C.

[0061] The conversion level in the hydrocracking step is in the range of about 50% to about 80%. In an embodiment the conversion level is about 56%. The conversion level is calculated as follows:

Conversion %=100[100*(product boiling>343 C./a fraction in the feed, boiling>343 C.)]

[0062] The feedstock comprising VGO and slack wax can be fed to the hydrocracking reactor as separate streams or combined into a single stream which is fed to the reactor.

[0063] The first effluent obtained from the hydrocracking step fractionated by distillation whereby at least a bottom fraction and a middle distillate fraction are obtained. Adequate fuel oil quality for the middle distillate fraction boiling in the range of about 300 C. to about 370+ C. is achieved and it is suitable for use as a component in diesel fuel. The bottom fraction is mainly composed of linear paraffins and naphtenes and boils above 370 C. Fractionation of the first effluent also produces a quantity of light gaseous hydrocarbons.

[0064] In an embodiment, for further refining, the bottom fraction is subjected to a dewaxing step. In the dewaxing step, waxy n-paraffins are isomerized to provide branched iso-paraffins. Isomerization of hydrocarbons is desired and generally improves the cold flow properties of a base oil. The dewaxing is typically performed in the presence of a dewaxing catalyst. Dewaxing catalysts suitable for use in this step are well known to a skilled person in the art.

[0065] The dewaxing step provides a second effluent which is fractionated in a distiller to high quality muddle distillate and base oil. Also lighter gaseous hydrocarbons are obtained. Group III Base oil having desirably a high viscosity index of >130 and middle distillate boiling in the range of about 300 C. to about 370 C. with high cetane number and improved cold flow properties are achieved. The middle distillate obtained from the dewaxing step can be used as diesel fuel as such or as a blending component.

[0066] The present invention can be a batch process or a continuous process.

[0067] In another aspect, the invention provides a method for improving the viscosity index of base oil, comprising the steps of: [0068] providing VGO and slack wax; [0069] combining the VGO as a major component and the slack wax as a minor component to provide a feedstock; [0070] subjecting the feedstock to a hydrocracking step to provide a first effluent; [0071] fractionating the first effluent to provide at least a bottom fraction and a middle distillate fraction; [0072] subjecting the bottom fraction to a dewaxing step to provide a second effluent; [0073] fractionating the second effluent to provide at least a middle distillate and base oil; [0074] recovering the middle distillate and the base oil.

[0075] All the information relating to the feedstock, process conditions etc. described above also apply in the latter method.

[0076] An example of an arrangement which can be used for conducting the method of the invention is shown in FIG. 1. Referring to the figure, the arrangement for producing oil-based components comprises a hydrocracking reactor A for cracking a waxy feed to provide a first effluent 4, a first distiller B, a dewaxing unit C and a second distiller D. The hydrocracking reactor A comprises at least one inlet for supplying a feedstock into the hydrocracking reactor A and an outlet for discharging the first effluent 4 from the hydrocracking reactor A. In an embodiment of the invention, the hydrocracking reactor A comprises at least two inlets, one for slack wax 2 and one for combined hydrogen 1 and VGO 3. In the figure, the hydrocracking reactor A comprises a catalytic hydrotreatment zone HT and a catalytic hydrocracking zone HC, the hydrotreatment zone lying upstream of the hydrocracking zone. The catalysts in each of the two zones can be arranged in one or more beds. Further, the beds can be graded in respect to the amount of the catalyst employed. A suitable arrangement and grading of the catalyst are well known to a skilled person in the art. Alternatively, the hydrotreatment zone and the hydrocracking zone can be arranged in individual reactors, the hydrotreatment reactor lying upstream of the hydrocracking reactor (not shown in FIG. 1).

[0077] The first distiller B is in a flow connection with the hydrocracking reactor A for fractioning the first effluent 4 to provide at least a bottom fraction HCB and a middle distillate fraction MD. The first distiller B comprises an inlet for supplying the first effluent 4 into the first distiller B and at least one outlet for discharging the bottom fraction HCB and a middle distillate fraction MD. The flow connection between the hydrocracking reactor A and the first distiller B is arranged through a pipe connection between the outlet of the hydrocracking reactor A and the inlet of the first distiller B. The first distiller B is arranged downstream of the hydrocracking reactor A. The dewaxing unit C is in a flow connection with the first distiller B for dewaxing the bottom fraction HCB to provide a second effluent 6. In an embodiment, unit C is a solvent dewaxing reactor. The dewaxing arm C comprises an inlet for supplying the bottom fraction HCB into the dewaxing unit C and an outlet for discharging the second effluent 6. The flow connection between the first distiller B and the dewaxing unit C is arranged through a pipe connection between the outlet of the first distiller B discharging the bottom fraction HCB and the inlet of the dewaxing unit C. The dewaxing unit C is arranged downstream of the first distiller B. The second distiller D is in a flow connection with the dewaxing unit C for fractioning the second effluent 6 to provide at least a middle distillate fraction MD and base oil. The second distiller D comprises an inlet for supplying second effluent 6 into the second distiller D and at least one outlet, but preferably two outlets, for discharging the middle distillate MD and base oil. The flow connection between the dewaxing unit C and the second distiller D is arranged through a pipe connection between the outlet of dewaxing unit C and the inlet of the second distiller D. The second distiller D is arranged downstream of the dewaxing unit C and comprises at least one outlet for discharging the middle distillate MD and base oil.

[0078] In a further aspect, the invention provides an arrangement for producing oil-based components, the apparatus comprising: [0079] a hydrocracking reactor A for cracking a waxy feed to provide a first effluent 4, said hydrocracking reactor A comprising at least one inlet for supplying a feed-stock to the hydrocracking reactor A and an outlet for discharging the first effluent 4 from the hydrocracking reactor A; [0080] a first distiller B in a flow connection with the hydrocracking reactor A for fractioning the first effluent 4 to provide at least a bottom fraction HCB and a middle distillate fraction MD, the first distiller B being arranged downstream of the hydrocracking reactor A; [0081] a dewaxing unit C in a flow connection with the first distiller B for dewaxing the bottom fraction HCB to provide a second effluent 6, the dewaxing unit C being arranged downstream of the first distiller B; and [0082] a second distiller D in a flow connection with the dewaxing unit C for fractioning the second effluent 6 to provide at least a middle distillate MD and base oil, the second distiller D being arranged downstream of the dewaxing unit C and comprises at least one outlet for discharging the middle distillate MD and the base oil.

[0083] The following examples are given for further illustration of the invention without limiting the invention thereto.

EXAMPLE

[0084] Feedstock comprising 20 wt. % slack wax and a balance of VGO was introduced to a hydrocracking reactor comprising a hydrotreatment zone and a hydrocracking zone. The content of sulphur and nitrogen of the feedstock was 1.3 wt. % and 0.079 wt. %, respectively. The viscosity index of the feedstock was 106. The conversion level was about 56%.

[0085] The feedstock was introduced to the hydrocracking reactor at a temperature of about 400 C. and at a pressure of about 132 bar. The feed of hydrogen per feedstock was 1.1 L/L.

[0086] As a reference, 100% VGO feedstock was introduced to the hydrocracking reactor under the same conditions.

[0087] The effluent from the hydrocracking reactor was fed to a distiller. A bottom fraction (HCB) boiling above 370 C., and a middle distillate fraction boiling in the range of about 300 C. to about 370 C. were obtained. The yield of the bottom fraction with 20 wt. % slack wax addition to VGO was surprisingly increased, at low conversion level of about 56%, from 31% to 35% as compared to a VGO feed without slack wax. The cetane number of a middle distillate fraction was increased from 60 (100% VGO) to 64 (80% VGO/20% slack wax).

[0088] The bottom fraction was solvent dewaxed (SDW) to provide base oil with a viscosity index of >130 and additional middle distillate having a cetane number of 64. Catalytic dewaxing processes are especially developed to improve the cold properties of the base oil products without sacrificing the viscosity index. Therefore, SDW can be used as an indicator of the viscosity index also of the catalytically dewaxed product. SDW is also a generally accepted and used method in the field and correlates well with catalytic dewaxing.

[0089] FIG. 2 shows that the viscosity index of base oil at a conversion level of about 56% was remarkable higher with 20 wt. % slack wax addition than that of pure VGO feed. Base oil obtained from the solvent dewaxing, having a viscosity index of at least 130 was achieved even with 4 cSt product. FIG. 2 further shows that the viscosity index of the base oil is increased by more than about 10 units compared to that of base of which is prepared front VGO without wax.

[0090] It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.