Control of crude refining by a method to predict lubricant base stock's ultimate lubricant preformance

• US 6,317,654 B1
• Filed: 01/29/1999
• Issued: 11/13/2001
• Est. Priority Date: 01/29/1999
• Status: Expired due to Term

• Current Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Gleeson, James William, Heaney, William Francis, Sanchez, Eugenio, Visweswaran, Viswanathan
• Primary Examiner(s): Grant, William
• Assistant Examiner(s): Bahta, Kidest
• Application Number:
  US09/240,027
• Time in Patent Office: 1,019 Days
• Field of Search: 700/29, 700/30, 700/44, 700/266, 700/207-272, 208/60, 208/58, 208/50, 208/131, 208/1-8, 525/1, 702/22, 702/30, 702/23, 702/27
• US Class Current: 700/272
• CPC Class Codes: C10M 101/02 Petroleum fractions

Abstract

A model to predict the quality of a lubricant base stock for use in a plurality of products having a plurality of viscosities. The compositional model is based on a quantitative analysis of key compositional parameters and performance criteria for the plurality of products representing the plurality of viscosities. The compositional model provides a method for making a lubricant base stock to be used in manufacturing a lubricant for a particular application from a refinery stream wherein the lubricant base stock and the refinery stream are characterizable according to a plurality of compositional components common to the base stock and to the refinery stream. This method begins with determining the acceptable region and adjusting for viscosity variations. Next, the amounts of the identified compositional components are identified for a lubricant base stock that, in combination, are required for acceptable lubricant performance and the amounts of identified components, in combination, in the refinery stream are determined to be outside of the acceptable range for such identified components. The refinery stream is then refined to produce a lubricant base stock having a combination of identified components within the acceptable range as determined by the model.

Claims

1. A method for making a lubricant base stock to be used in manufacturing a lubricant for a particular application from a petroleum refinery stream, the lubricant base stock and the refinery stream being characterizable according to a plurality of compositional components common to the base stock and to the refinery stream, each compositional component varying in amount with respect to different lubricant base stocks and to different refinery streams, the method comprising the steps of:

identifying particular ones of the plurality of compositional components in a base stock that, in combination, are probative of lubricant performance for the particular application;

determining an acceptable range for a combination of the identified compositional components at at least two viscosities from a plurality of performance tests on a plurality of lubricant products, each lubricant product having a viscosity, the plurality of lubricant products having a plurality of different viscosities, thereby defining a compositional model at each of the at least two viscosities;

adjusting for viscosity variations for lubricant base stocks whose viscosities differ from that of the at least two viscosities by adjustment of the compositional model'"'"'s parameters from at least two compositional models at values of viscosity differing from those of a candidate lubricant base stock to derive an acceptable range of compositional components, in combination, at the viscosity of the candidate lubricant base stock;

determining the amounts of the identified components which are required in the base stock for acceptable performance in the particular application;

determining the amounts of the identified components in the refinery stream, in combination, are not within the acceptable range for such identified components; and

refining the refinery stream to produce the lubricant base stock having the identified components in combination in the compositional ranges for acceptable performance of the lubricant base stock in the particular application.

2. The method of claim 1 wherein the determined acceptable range for each identified component is selected from the group consisting of an acceptable range that is independent of any other identified component and an acceptable range that is inter-related to an acceptable range of another identified component.

3. The method of claim 1 wherein the identifying step comprises selecting compositional components from the group consisting of basic nitrogen, sulfur, aliphatic sulfur, aromatics, and a combination thereof.

4. A method according to claim 1 in which the refinery stream is refined in accordance with the composition of the stream of the composition required of the lubricant base stock and a refining processing model which correlates stream composition with the composition of the lubricant base stock according to the identified components of the refinery stream and the base stock.

5. A method according to claim 4 in which the refinery stream is refined in accordance with the composition of the stream and of the composition required of the lubricant base stock and a refining processing model which correlates stream composition with the composition of the lubricant base stock according to the identified components and with acceptable refining conditions.

6. A method according to claim 4 in which the refinery stream is selected to have a composition in which the identified components are present in greater amounts that in the base stock, the excess amounts of the identified components being removed by subtractive refining to produce the lubricant base stock having a composition in which the identified components are present in combination in the amounts required for acceptable lubricant performance in the particular application.

7. A method according to claim 1 in which the refinery streams are crude oils.

8. A method according to claim 7 in which the crude oil is subjected to a refining process model comprised of unit subtractive refining operations including distillation, solvent extraction and dewaxing, wherein the refining process model accounts for compositional changes that depend on changes in the unit subtractive refining operations.

9. A method according to claim 8 in which the refining process model includes unit process models for distillation, solvent extraction and dewaxing.

10. A method according to claim 1 in which the refinery streams are gas oils.

11. A method according to claim 10 in which the gas oils are subjected to a refining process model comprised of unit subtractive processes including solvent extraction and dewaxing processes, wherein the refining process model accounts for compositional changes that depend on changes in the solvent extraction and dewaxing processes.

12. A method according to claim 11 in which the refining process model includes unit process models for solvent extraction and dewaxing of the gas oils.

13. A method according to claim 1 in which the refinery streams are raffinates produced by solvent extraction of a vacuum distillate.

14. A method according to claim 13 in which the raffinates are subjected to a refining process model comprised of a dewaxing process, wherein the refining process model accounts for compositional changes that depend on changes in the dewaxing process.

15. A method according to claim 14 in which the refining process model includes unit process models for dewaxing of the raffinate.

16. The method according to claim 1 wherein the refining step is a solvent extraction process.

17. The method according to claim 16 further comprising the step of, prior to the solvent extraction process, determining an amount of solvent required to refine the candidate base stock to remove at least some of the compositional components such that candidate base stock is in the acceptable range for each of the identified compositional components.

18. The method of claim 16 further comprising the step of separating the solvent from the candidate base stock.

19. The method of claim 16 wherein the solvent is furfural.

20. The method of claim 16 wherein the solvent extraction process is a continuous flow process.

21. The method of claim 1 wherein the refining step includes a hydroprocessing step.

22. A method according to claim 21 in which the hydroprocessing step is subjected to a refining process model, wherein the refining process model accounts for compositional changes that depend on changes in the hydroprocessing step.

23. A method according to claim 22 in which the refining process model includes a unit process hydroprocessing.

24. The method of claim 17 further comprising the step of, prior to the hydroprocessing step, determining an amount of hydrogen required to refine the candidate base stock to remove at least some of the compositional components such that candidate base stock is in the acceptable range for each of the identified compositional components.

25. A method according to claim 1 wherein the adjustment for viscosity variations is made by interpolation of compositional model parameters between the compositional model parameters for the compositional model at the viscosity next higher than the viscosity of the candidate lubricant base stock and the compositional model parameters at the viscosity next below the viscosity of the candidate lubricant base stock.

26. A method according to claim 1 wherein the adjustment for viscosity variations is made by extrapolation of compositional model parameters from compositional model parameters at viscosities differing from the viscosity of the candidate lubricant base stock.

27. A method according to claim 1 in which the adjustment for viscosity variations is made by interpolation of compositional model parameters between compositional model parameters for a compositional model at a viscosity nearest above the viscosity of the candidate lubricant base stock and the compositional model parameters at the viscosity nearest below the viscosity of the candidate lubricant base stock.

28. A method according to claim 27 in which the compositional models for at least one of the compositional models at the next higher viscosity value and the next lower viscosity value are generated with variations about a viscosity grade with adjustments for viscosity variations within the viscosity grade made by scaling compositional variations with viscosity.

29. In connection with a method of selecting a base stock from among a plurality of base stocks, the selected base stock being used in manufacturing a lubricant for a particular application, each base stock being characterize-able according to a plurality of compositional components common to all of the base stocks, each compositional component varying in amount with respect to each base stock, a computer-readable medium having computer-implementable instructions thereon for performing the steps of:

identifying particular ones of the plurality of compositional components in a base stock that are probative of lubricant performance for a plurality of applications;

determining an acceptable range for a combination of the identified compositional components at at least two viscosities from a plurality of performance tests on a plurality of lubricant products, each lubricant product having a viscosity, the plurality of lubricant products having a plurality of different viscosities, thereby defining a compositional model at each of the at least two viscosities;

adjusting for viscosity variations for lubricant base stocks whose viscosities differ from that of the at least two viscosities by adjustment of the compositional model'"'"'s parameters from at least two compositional models at values of viscosity differing from those of a candidate lubricant base stock to derive an acceptable range of compositional components, in combination, at the viscosity of the candidate lubricant base stock;

determining the amounts of the identified compositional components in a candidate base stock;

determining whether the amount of each identified component in the candidate base stock is within the acceptable range for such identified component; and

determining whether a particular refining process will refine the candidate base stock to remove at least some of the compositional components such that candidate base stock is in the acceptable range for each of the identified compositional components, in combination.

30. The computer-readable medium of claim 29 having computer-implementable instructions thereon for performing the further steps of:

selecting one of the base stocks as a candidate base stock;

determining the amounts of the identified composition components in a candidate base stock;

determining whether the amount of each identified component in candidate stock is within the acceptable range for such identified component; and

determining whether a particular refining process will refine the candidate base stock to remove at least some of the compositional components such that candidate base stock is in the acceptable range for each of the identified compositional components, in combination.