Property determination

• US 5,712,797 A
• Filed: 06/06/1995
• Issued: 01/27/1998
• Est. Priority Date: 10/07/1994
• Status: Expired due to Term

• Current Assignee: Topnir Systems
• Original Assignee: BP Chemicals Ltd. (BP PLC), BP Oil International Limited (BP PLC)
• Inventors: Lambert, Didier, Llinas, Jean-Richard, Martens, Andre, Sanchez, Michel, Osta, Sebastien, Descales, Bernard
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): KEMPER, MELANIE A
• Application Number:
  US08/465,680
• Time in Patent Office: 966 Days
• Field of Search: 364/496, 364/497, 364/498, 364/499, 364/500, 364/501, 364/502, 364/554, 73/23.2, 73/25.01, 73/29.01, 73/30.01
• US Class Current: 702/30
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 33/2829 mixtures of fuels, e.g. determining the RON-number

Abstract

A method of determining or predicting a value P_x of a property (e.g. octane number) of a material X or a property of a product of a process from said material or yield of said process, which method comprises measuring the absorption D_ix of said material at more than one wavelength in the region 600-2600 nm, comparing the said absorptions or a derivative thereof with absorptions D_im or the derivatives thereof at the same wavelength for a number of standards S in a bank for which the said property or yield P is known, and choosing from the bank at least one standard S_m with property P_m said standard having the smallest average value of the absolute difference at each wavelength i between the absorption D_i x (or derivative thereof) for the material and the absorption D_i m (or derivative thereof) for the standard S_m to obtain the P_x, with averaging of said properties or yields P_m when more than one standard S_m is chosen.

Claims

1. A method of determining or predicting a value P_x which is a value of a property of a material X or a property of a product of a process from said material or yield of said process, which method comprises measuring the absorption D_ix of said material at more than one wavelength in the region 600-2600 nm, comparing the said absorptions or a derivative thereof with absorptions D_im or derivatives thereof at the same wavelength for a number of standards S in a bank for which the said property or yield P is known, and choosing from the bank at least one standard S_m with property P_m said standard having the smallest average value of the absolute difference at each wavelength I between the absorption D_i x (or derivative thereof) for the material and the absorption D_i m (or derivative thereof) for the standard S_m to obtain P_x, with averaging of said properties or yields P_m when more than one standard S_m is chosen and wherein the standard S_m chosen for the property or yield wanted is such that in relation to the unknown material X and each chosen standard S_m a function i_xm, which is a proximity index defined by i² (xm)=Σ

(D_ix D_im)², is less than a minimal index i_m which has been determined from preselected standards by (a) calculating for each pair of the standards a value of a corresponding proximity index to obtain a series of proximity indices with corresponding property differences, (b) relating values of the proximity indices to corresponding property differences, (c) calculating an average of the corresponding property differences for predetermined values L which are greater than a corresponding proximity index, and (d) calculating the minimal index based on the average property differences and a reproducibility standard for the property.

2. A method according to claim 1, wherein the properties of synthetic standards, which are mixtures, and their spectra for consideration for possible choice for S_m are estimated from existing standards in the bank for which, in respect of each existing standard for use in said mixture equation (4) and (5) are met,

3. A method according to claim 2 wherein at least one of (i) the estimated Standards and the corresponding spectra, and (ii) the property P_x of the unknown material and its spectrum, are added to the bank.

4. A method according to claim 1 wherein properties of standards and spectra for consideration for possible choice are estimated by interpolation from measured properties of standards and spectra for which the proximity index with respect to the unknown X is not more than 10 times the minimal Index.

5. A method according to claim 1 wherein the property is a physicochemical property of material X.

6. A method according to claim 1 wherein the property is a physicochemical property or yield of a product of a process to which at least one material X is a feed.

7. A method according to claim 1 wherein said process is a hydrocarbon conversion or separation process.

8. A method according to claim 7 wherein said process is a distillation to give at least 1 distillation product and a residue and the properties/yields are obtained in respect of said product and/or residue.

9. A method according to claim 7 wherein said process is a reforming or catalytic cracking or hydrotreatment, or distillation or blending.

10. A method according to claim 1 wherein said property is in respect of a motor fuel and is at least one of an Octane Number, vapour pressure, volatility percentage distilled at 70°

and at 100°

C., gum content in mg/100 ml and content of sulphur, benezene or methyl tert. butyl ether.

11. A method according to claim 10 wherein the property is in respect of a blend comprising gasoline, the spectra are measured on feeds to said blending, and by calculation the blend index obtained as a linear or non linear function.

12. A method according to claim 1 wherein said property is in respect of gas oil and is at least one of cetane index, cetane number, percentage of sulphur, density at 15°

C., clear point, cloud point, filtrability and viscosity at 40°

C.

13. A method according to claim 1 wherein said property is in respect of a crude oil and is at least one of density, percentage of sulphur, viscosity at 100°

C., content of paraffin and residual carbon percentage (Conradson Carbon).

14. A method according to claim 1 wherein said property is in respect of a feed to a reforming process and is at least one of percentages of saturated linear, isoparaffins, napthenes, and aromatics and density.

15. A method according to claim 1 wherein said property is in respect of a feed to a fluid catalytic cracking unit and is at least one of the density, the weight percentage of sulphur, the aniline point, viscosity at 100°

C., refractive index at 20°

C. or 60°

C., 50% distillation point, molecular weight, percentage of aromatic carbon and the KUOP, crackability or cokability of the feed or yield of gas, gasoline, gas oil or residue.

16. A method according to claim 1 wherein said percentage is in respect of the feed to a hydrogenation unit and is at least one of percentages of linear saturation, isoparaffins, naphthenes, linear olefins, cylic olefins, benzene, toluene xylene, alkylbenzene, density, or yield of light cut, heavy cut, or raffinate or benzene.

17. A method according to claim 1 wherein the said property or yield of said process is used to control and optimise said process.

18. A method according to claim 1 wherein selected steps are computer implemented.

19. A method according to claim 18 wherein the selected steps include assessing, comparing and choosing.

20. Apparatus suitable for use in the method of claim 1 which comprises an NIR spectrometer receiving at least one signal from a feed or product line in said process and being coupled to a computer to effect continuous measurement of the spectra of the feed and/or product and provide feed back control of the process.

21. A method according to claim 1 wherein the property is a physicochemcial property of material X and wherein said property is in respect of a motor fuel and is at least one of an Octane Number, vapour pressure, volatility percentage distilled at 70°

and at 100°

C., gum content in mg/100 ml and content of sulphur, benzene or methyl tert. butyl ether.

22. A method according to claim 21 wherein said property or yield of said process is used to control and optimise said process.

23. A method according to claim 1 wherein the property is a physicochemcial property of material X and wherein said property is in respect of gas oil and is at least one of cetane index, cetane number, percentage of sulphur, density at 15°

C., clear point, cloud point, filterability and viscosity at 40°

C.

24. A method according to claim 23 wherein said property or yield of said process is used to control and optimise said process.

25. A method according to claim 1 wherein the property is a physicochemcial property or yield of a product of a process to which at least one material X is a feed and wherein said property is in respect of a motor fuel and is at least one of an Octane Number, vapour pressure, volatility percentage distilled at 70°

and at 100°

C., gum content in mg/100 ml and content of sulphur, benzene or methyl tert. butyl ether.

26. A method according to claim 25 wherein said property or yield of said process is used to control and optimise said process.

27. A method according to claim 1 wherein the property is a physicochemcial property or yield of a product of a process to which at least one material X is a feed and wherein said property is in respect of gas oil and is at least one of cetane index, cetane number, percentage of sulphur, density at 15°

C., clear point, cloud point, filterability and viscosity at 40°

C.

28. A method according to claim 27 wherein said property or yield of said process is used to control and optimise said process.

29. A method for adding an extra synthetic standard to a bank of known standards, each of which relates at least one absorption in the 600-2600 mm region (or derivative thereof) of a known material to a known property related to that material, which property is of said material, or is of a product of a process from said material or yield of said process, which method comprises choosing from the bank at least 2 standards for which equations 4 and 5 are met,

30. A computer programmed to perform the method of determining or predicting a value P_x which is a value of a property of a material X or a property of a product of a process from said material or yield of said process, which method comprises measuring the absorption D_ix of said material at more than one wavelength in the region 600-2600 nm comparing the said absorptions or a derivative thereof with absorptions D_im or derivatives thereof at the same wavelength for a number of standards S in a bank for which the said property or yield P is known, and choosing from the bank at least one standard S_m with property P_m said standard having the smallest average value of the absolute difference at each wavelength I between the absorption D_i x (or derivative thereof) for the material and the absorption D_i m (or derivative thereof) for the standard S_m to obtain P_x, with averaging of said properties or yields P_m when more than one standard S_m is chosen and wherein the standard S_m chosen for the property or yield wanted is such that in relation to the unknown material X and each chosen standard S_m a function i_xm, which is a proximity index defined by i² (xm)=Σ

(D_ix D_im)², is less than a minimal index i_m which has been determined from preselected standards by (a) calculating for each pair of the standards a value of a corresponding proximity index to obtain a series of proximity indices with corresponding property differences, (b) relating values of the proximity indices to corresponding property differences, (c) calculating an average of the corresponding property differences for predetermined values L which are greater than a corresponding proximity index, and (d) calculating the minimal index based on the average property differences and a reproducibility standard for the property.

31. A computer programmed to perform the method of adding an extra synthetic standard to a bank of known standards, each of which relates at least one absorption in the 600-2600 nm region (or derivative thereof) of a known material to a known property related to that material, which property is of said material or is of a product of a process from said material or yield of said process, which method comprises choosing from the bank at least 2 standards for which equations 4 and 5 are met,

32. A computer implemented method for a system including a spectrometer linked to a process line containing a material X, which is a product of a process or feed to a process, a computer linked to the spectrometer, and a controller linked to the computer and the process line, the computer including databanks having stored therein absorptions of standard materials and corresponding properties of said materials, or of products of a process from said materials or yield of said process, the method comprises steps of:

measuring absorption at more than one wavelength in the region 600-2600 nm at the process line and producing absorption signals by the spectrometer in accordance therewith;

assessing the databanks of the computer in accordance with the absorption signals;

comparing, by the computer, the absorption signals to the absorptions of the standard materials stored in the databanks;

choosing at least one standard based on the comparing, said standard having the smallest average value of the absolute difference at each wavelength i between the absorption (or derivative thereof) for the material and the absorption (or derivative thereof) for the standards, with averaging of said properties or yields when more than one standard is chosen, and

controlling said process line in accordance with the outputted property/yield,

wherein the standard chosen for the property or yield wanted is such that in relation to the unknown material X and each chosen standard a function i_xm, which is a proximity index defined by i² (xm)=Σ

(D_ix D_im)², is less than a minimal index i_m which has been determined from preselected standards by (a) calculating for each pair of the standards a value of a corresponding proximity index to obtain a series of proximity indices with corresponding property differences, (b) relating values of the proximity indices to corresponding property differences, (c) calculating an average of the corresponding property differences for predetermined values L which are greater than a corresponding proximity index, and (d) calculating the minimal index based on the average property differences and a reproducibility standard for the property.