Process for analysis of asphaltene content in hydrocarbon mixtures by middle infrared spectroscopy
First Claim
1. A process for determining asphaltene concentration in an asphaltene-containing hydrocarbon mixture using infrared spectroscopy and a multiple variable regression analysis to determine asphaltene concentration, comprising in combination:
- a. measuring at at least one frequency, the infrared absorption in the band of 3800-700 cm-1 ;
b. taking each of the absorbances measured, or a mathematical function thereof;
c. performing statistical treatment using the above absorbances or to functions as individual independent variables;
d. assigning and applying weighting constants or their equivalents to said independent variables;
e. applying the above steps using compositions of known asphaltenes concentration to calibrate the instrument and determine said weighting constants or equivalents;
f. repeating said steps with unknown compositions, and applying the weighting constants or equivalents determined during said calibration with compositions of known asphaltenes concentration to output a signal or signals indicative of asphaltenes concentration for the unknown compositions.
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Abstract
Asphaltene concentration of a hydrocarbon feed is measured by IR spectroscopy using mid-range IR frequencies between 3800 cm-1 and 650 cm-1 (corresponding to wavelengths between 2630 nanometers (nm) and 15,380 nm) together with mathematical techniques and statistical techniques in which measurements of absorption are made, and combines these with multiple regression analysis, or other statistical technique and modeling to determine asphaltene concentration. The output signal can be used to control refinery and chemical processes, e.g., atmospheric crude column, vacuum distillation column, solvent deasphalting and visbreaking.
56 Citations
19 Claims
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1. A process for determining asphaltene concentration in an asphaltene-containing hydrocarbon mixture using infrared spectroscopy and a multiple variable regression analysis to determine asphaltene concentration, comprising in combination:
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a. measuring at at least one frequency, the infrared absorption in the band of 3800-700 cm-1 ; b. taking each of the absorbances measured, or a mathematical function thereof; c. performing statistical treatment using the above absorbances or to functions as individual independent variables; d. assigning and applying weighting constants or their equivalents to said independent variables; e. applying the above steps using compositions of known asphaltenes concentration to calibrate the instrument and determine said weighting constants or equivalents; f. repeating said steps with unknown compositions, and applying the weighting constants or equivalents determined during said calibration with compositions of known asphaltenes concentration to output a signal or signals indicative of asphaltenes concentration for the unknown compositions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification