Chemicals property determination

• US 5,763,883 A
• Filed: 06/06/1995
• Issued: 06/09/1998
• Est. Priority Date: 10/07/1994
• Status: Expired due to Term

• Current Assignee: Eutech Engineering Solutions Ltd. (ABB Limited)
• Original Assignee: BP Chemicals Ltd. (BP PLC), BP Oil International Limited (BP PLC)
• Inventors: Lambert, Didier, Llinas, Jean-Richard, Martens, Andre, Descales, Bernard
• Primary Examiner(s): Porta, David P.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US08/467,179
• Time in Patent Office: 1,099 Days
• Field of Search: 250/339.09, 250/339.12, 250/340, 250/341.1, 250/341.5, 364/498
• US Class Current: 250/339.09
• 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 of a material X, which is a feed to a process or a property of a product of a process from said material or yield of said process, which method comprises measuring the absorption D_i x 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_i m 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 standards 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 said process is at least one of polymerization, an oligomerization or an organic reaction in which at least one of the reactant and a product is a functionalized compound.

Claims

1. A method of determining or predicting a value P_x of a property of a material which is a product of a process or is a feed to a process or a property of a product of a process from said material or yield of any of said processes, which method comprises measuring absorption D_i x of said material at more than one wavelength in the region 600-2600 nm, comparing said absorptions or a derivative thereof with absorptions D_i m or derivatives thereof at the same wavelengths for a number of standards S in a bank, for which said property or yield P is known, and choosing from the bank at least one standard S_m with property P_m 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 value P_x and, when more than one standard S_m is chosen, averaging said properties or yields P_m and wherein said process is at least one of a polymerization, an oligomerization or an organic reaction in which at least one of the reactant and a product is a functionalized compound.

2. A method according to claim 1 wherein a proximity index is defined by i² (_xm)=Σ

(D_ix -D_im)², the proximity index being 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, (d) calculating the minimal index based on the average property differences and a reproducibility standard for the property.

3. A method according to claim 1, wherein properties of synthetic standards, which are mixtures, and their spectra for consideration for possible choice for Sm 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,

4. A method according to claim 2 wherein the properties of the standards and spectra for consideration for possible choice are estimated by interpolation from measured properties of the standards and the spectra for which the proximity index with respect to an unknown is not more than 10 times the minimal index.

5. A method according to claim 3 wherein at least one of a) the estimated standards and the corresponding spectra, and b) the property P_x of the unknown material and its spectrum, are added to the bank.

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

7. 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.

8. A method according to claim 1 wherein said process is a polymerization.

9. A method according to claim 8 which is an addition polymerization of at least one unsaturated hydrocarbon, and the property to at least one of number and weight average molecular weight, molecular weight distribution, viscosity, viscosity index, fluidity index, density, chemical composition such as percentage of at least one monomer, or unsaturation of side chain group, crystallinity, rigidity, a flow property, draw strength at the flow threshold, cracking resistance and shock resistance.

10. A method according to claim 9, wherein the process is a polymerization of at least one alpha olefin of 2 8 carbons and the property is of the product and is at least one of the density, fluidity index, degree of conversion, content of volatiles and, in the case of copolymerization percentage of comonomer.

11. A method according to claim 9 wherein the process is a polymerization of isobutene and the property is of the product and is at least one of the viscosity, number average molecular weight, distribution of molecular weights, inflammability point, content of butene 1 unsaturation and maleinization index, and percentage of light and heavy fractions from distillation of the direct/product of the process.

12. A method according to claim 8 wherein the process is the polymerization reaction of an expoxide in the presence of an organic compound containing at least one hydroxy group and the property is at least one of the degree of conversion, and of the product, hydroxyl index, viscosity and molecular weight.

13. A method according to claim 1 wherein the process is a reaction in which at least one of a reactant and product is a functionalized compound, and is a hydration, dehydration, etherification, esterification, oxidation, ammonidation or carbonylation.

14. A method according to claim 1 which is computer implemented.

16. An 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.

15. 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, which is a product of a process or is a feed to a process or a property of a product of a process from said material or is a yield of any of said processes, which method comprises measuring the absorption D_ix of said material at more than one wavelength in the region 600-2600 nm, comparing 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 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, and, when more than one standard S_m is chosen, averaging said properties or yields P_m, wherein said process is at least one of a polymerization, an oligomerization or an organic reaction in which at least one of the reactant and a product is a functionalized compound.

17. 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 a 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 or derivatives thereof by the spectrometer in accordance therewith;

assessing the databanks of the computer in accordance with the absorption signals or derivatives thereof;

comparing, by the computer, the absorption signals or derivatives thereof 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 said process is at least one of a polymerisation, an oligomerisation or an organic reaction in which at least one of the reactant and a product is a functionalized compound.