Indirect method for determining oxygenate content using near-infrared absorption spectra
First Claim
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1. A method for controlling total oxygenate content of a composition that comprises at least 1% by volume of oxygenate content, comprising in combination the steps:
- a. measuring the value of at least one absorbance in at least one wavelength between about 1,300 to1,350 nanometers; and
b. substituting said value into an equation to obtain a prediction of oxygenate content of said composition, whereby the effect of temperature on said prediction is reduced; and
c. controlling said composition in response to said prediction.
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Abstract
Method for determining oxygenate content and/or octane of hydrocarbon fuels suitable for automotive vehicles. Selecting nanometer frequencies in the range 1,300 to 1,350 reduces the temperature dependence of calibration equations that predict values representative of both oxygenate content and octane. This can be further improved by using only derivatives of selected temperature-dependent frequencies in addition to those in the 1,300 to 1,350 nanometer range. The selected frequencies preferably primarily correspond to C-H vibrational modes.
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Citations
22 Claims
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1. A method for controlling total oxygenate content of a composition that comprises at least 1% by volume of oxygenate content, comprising in combination the steps:
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a. measuring the value of at least one absorbance in at least one wavelength between about 1,300 to1,350 nanometers; and b. substituting said value into an equation to obtain a prediction of oxygenate content of said composition, whereby the effect of temperature on said prediction is reduced; and c. controlling said composition in response to said prediction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An improved method for controlling octane of a composition that contains at least 1% by volume of an alcohol, comprising in combination:
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a. measuring the absorbance of said composition in at least one band in the infrared spectrum; b. transforming said absorbance by a mathematical transformation comprising taking its derivative of first or higher order c. substituting said derivative into an equation which provides a prediction to predict octane of said composition and d. controlling blending of components, including said alcohol, which affect the octane of said composition, in response to said prediction. - View Dependent Claims (10, 11, 12, 13)
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14. An improved method for controlling alcohol content of an at least 1% by volume oxygenate-containing composition comprising:
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a. measuring absorbance in an infrared band in the range 1576 to 1596 nm; b. transforming said absorbance by a mathematical transformation; c. substituting said absorbance so changed into an equation which defines a prediction of values representative of alcohol content of said composition; and d. controlling blending of said composition in response to said prediction. - View Dependent Claims (15, 16, 17, 18)
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19. An improved method for controlling alcohol content of an at least 1% by volume oxygenate-containing composition comprising:
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a. measuring absorbance in an infrared band in the range 1310 to 1340 nm; b. transforming said absorbance by a mathematical transformation; c. substituting said absorbance so changed into an equation which defines a prediction of values representative of alcohol content of said composition; and d. controlling blending of said composition in response to said prediction. - View Dependent Claims (20, 21, 22)
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Specification