Methods and apparatus for determining hydrocarbon fuel properties

• US 5,225,679 A
• Filed: 01/24/1992
• Issued: 07/06/1993
• Est. Priority Date: 01/24/1992
• Status: Expired due to Term

• Current Assignee: Petroleum Analyzer Company LP (Roper Technologies, Inc.)
• Original Assignee: Boston Advanced Technologies, Inc. (Global Technovations, Inc.)
• Inventors: Tang, Deming, Clarke, Richard H.
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): Glick, Edward J.
• Application Number:
  US07/825,062
• Time in Patent Office: 529 Days
• Field of Search: 250/301, 250/339, 250/343, 250/340, 250/341
• US Class Current: 250/343
• CPC Class Codes: G01N 2021/3177 Use of spatially separated filters in simultaneous way
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 33/2829 Mixtures of fuels

Abstract

Method and apparatus for monitoring hydrocarbon-based fuel properties by measuring the presence and amount of fuel component molecules in the fuel solution. Detection is made of absorption related to signature vibrational modes associated with the fuel component molecules when excited in the mid-IR. In one embodiment, a mid-IR light source illuminates the fuel in-situ and a narrow bandwidth detector associated with a vibrational mode signature detects absorbance as an indication of the presence and quantity of the fuel component in solution. From the determined fuel component quantity and known characteristics, the fuel solution properties are predicted. In one embodiment, octane rating and vapor pressure for a fuel solution is determined in-situ and in real time.

Claims

1. Apparatus for determining the properties of a hydrocarbon-based fuel based on analysis of the components of the fuel, the apparatus comprising:

an examination vessel for receiving a hydrocarbon-based fuel sample;

a mid-IR light source which illuminates the fuel sample;

detection means for detecting a plurality of fuel components, each fuel component having known characteristics including at least one known absorbance value associated with a known quantity of that fuel component, the detection means comprising, for each one of the plurality of fuel components, at least one light absorption detector assigned to a narrow spectral band centered about a wavelength associated with a signature vibrational mode of the respective fuel component and selected from the group consisting of;

700 wavenumbers, for the measurement of aromatic-based fuel components,

1100 wavenumbers, for the measurement of ethanol fuel components,

1200 wavenumbers, for the measurement of MTBE fuel components, and

3300 wavenumbers, for the measurement of alcohol-based fuel components;

each detector output expressing a detected absorbance value indicative of the quantity of the detected fuel component; and

correlation means for predicting the properties of the fuel based upon correlation of the known characteristics of the fuel components with the output of the detectors.

2. The apparatus of claim 1 wherein the correlation means performs a correlation between the amount of the detected absorbance value with the volume percent in solution of the fuel component.

3. The apparatus of claim 2 wherein the correlation means further performs a correlation between the amount of the detected absorbance value to octane rating and vapor pressure of the fuel.

4. The apparatus of claim 1 wherein the examination vessel is a shunt tube for sampling a flowing portion of the fuel for in-situ determination of the fuel properties.

5. The apparatus of claim 1 wherein the mid-IR light source comprises a heated element acting as a block body radiator, having a bandwidth of 4000-500 wavenumbers.

6. The apparatus of claim 1 wherein the correlation means comprises a microprocessor.

7. The apparatus of claim 1 wherein each respective light absorption detector comprises a narrow band filter for limiting the bandwidth of the detector to a narrow range in the mid-IR spectrum centered about the frequency of the signature vibrational mode of the respective one of the plurality of components.

8. Method for determining the properties of a hydrocarbon-based fuel based on analysis of the components of the fuel, comprising the steps of:

illuminating a stream of hydrocarbon-based fuel with mid-IR light;

obtaining an absorbance value associated with a quantity of fuel component for each of a plurality of fuel components by evaluating the illuminated stream with a respective light absorption detector assigned to a narrow spectral band centered about a wavelength associated with a signature vibrational mode of the respective fuel component and selected from the group consisting of;

700 wavenumbers, for the measurement of aromatic-based fuel components,

1100 wavenumbers, for the measurement of ethanol fuel components,

1200 wavenumbers, for the measurement of MTBE fuel components, and

3300 wavenumbers, for the measurement of alcohol-based fuel components;

each detector output expressing a detected absorbance value indicative of the quantity of the detected fuel component; and

predicting the properties of the fuel based upon correlation of the known characteristics of the fuel components with the detected absorbance values outputted by the detectors.

9. The method of claim 8 wherein the predicting further comprises correlating the detected absorbance value with the volume percent in solution of the fuel component.

10. The method of claim 9 wherein the predicting further comprises correlating the absorbance value to octane rating and vapor pressure of the fuel.