METHOD AND APPARATUS FOR DETERMINATION OF SYSTEM PARAMETERS FOR REDUCING CRUDE UNIT CORROSION

• US 20120142113A1
• Filed: 12/01/2010
• Published: 06/07/2012
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: Ecolab USA Incorporated (Ecolab, Inc.)
• Original Assignee: Nalco Company LLC (Ecolab, Inc.)
• Inventors: Banks, Rodney H., Ciota, Steven R., Welz, Sascha J.
• Granted Patent: US 9,134,238 B2
• Time in Patent Office: Days
• US Class Current: 436/43
• CPC Class Codes: G01N 2021/6421 Measuring at two or more wavelengths
• CPC Class Codes: G01N 2021/6491 Measuring fluorescence and transmission; Correcting inner filter effect
• CPC Class Codes: G01N 2021/7786 Fluorescence
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/6428 Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" in vivo A61B5/00; immunoassay G01N33/53
• CPC Class Codes: G01N 21/643 non-biological material
• CPC Class Codes: G01N 21/77 by observing the effect on a chemical indicator
• CPC Class Codes: G01N 21/7703 using reagent-clad optical fibres or optical waveguides using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B
• CPC Class Codes: G01N 21/80 Indicating pH value
• CPC Class Codes: G01N 21/82 producing a precipitate or turbidity
• CPC Class Codes: G01N 31/22 using chemical indicators G01N31/02 takes precedence
• CPC Class Codes: G01N 31/221 for investigating pH value
• CPC Class Codes: G01N 33/1813 Specific cations in water, e.g. heavy metals
• CPC Class Codes: G01N 35/08 using a stream of discrete samples flowing along a tube system, e.g. flow injection analysis
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/193333 In aqueous solution
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials

Abstract

The invention provides a method and apparatus for determining the amount of various materials in a liquid sample. Because the apparatus is particularly resilient it can be used repeatedly with very harsh liquid samples such as boot water from an oil refinery. The apparatus uses at least one volume and/or concentration independent optical analysis method to determine at least one of: the pH, amount of chloride, and/or amount of iron in the sample. The optical property can be colorimetric, fluorescent or both and result from adding dyes, complexing agents, turbidity inducing compounds, and other optically effecting reagents to the sample. Because the measurements are concentration and volume independent they can be done continuously, quickly, and avoid the inconvenient start and stop procedures in prior art measurement regimens. The method further includes using a BDD cell to oxidize materials (such as sulfoxy compounds) that would otherwise interfere with the optical analysis and/or to sparge the sample with gas.

Claims

1. A method of measuring at least one property of a predominantly liquid sample, the method comprising the steps of:

adding at least one chemical reagent to the sample, the chemical reagent capable of inducing a measurable optical effect when added to the sample that is directly related to the property to be detected,

measuring the optical effect, and

deducing the value of the property by comparing the measured optical effect to predetermined values associated with the property to be determined,

wherein the relationship between the measured optical effect and the property to be determined is independent of the volume of the liquid sample and independent of the volume of the reagent added to the sample.

2. The method of claim 1 wherein the measured property is one item selected from the list consisting of:

pH, iron concentration, chloride concentration, and any combination thereof.

3. The method of claim 1 wherein the measured optical effect is a colorimetric effect, turbidity effect, or a fluorescent effect.

4. The method of claim 1 wherein the optical effect is measured by determining an absorbance level at a particular wavelength whose measurement is recognized as an isosbestic point for all values of the property, detecting at least one other absorbance level for one other wavelength, comparing the two absorbance levels with pre-determined data, and correlating the two absorbance levels to the known absorbance levels of a particular value of the property.

5. The method of claim 1 wherein the optical effect is measured by the reagents being at least two fluorescent dyes, one of the dyes'"'"' fluorescence at a first wavelength is affected by the value of the property and one of the other dyes'"'"' fluorescence at a second wavelength is unaffected by the value of the property, the method further comprising the steps of measuring the ratio of the fluorescence intensity of the first and second wavelengths in the sample, comparing that ratio to the ratio of the fluorescence of the first and second wavelengths in a control having a known value of that property, and correlating the proportional change in the two ratios to the property value.

6. The method of claim 1 wherein the optical effect is measured by the reagent'"'"'s absorbance and fluorescence where the absorbance is unaffected by the value of the property and the fluorescence is affected by the value of the property, by comparing the ratio of the fluorescence to absorbance to a control having a known value of the property, and correlating the proportional change in the two ratios to the property.

7. The method of claim 1 wherein the reagent forms a complex with a compound that causes the property, the absorbance of the complex at a pre-determined wavelength is directly related to the amount of that compound present and not to the amount of reagent added, and correction for color and turbidity of the sample is made by reading at a wavelength where the complex does not absorb.

8. The method of claim 1 wherein the sample is positioned within an apparatus, the apparatus comprises at least one reagent source constructed and arranged to feed the reagent into a chamber where it is mixed with the sample and the sample is moved past an optical sensor that measures the optical property.

9. The method of claim 8 further comprising a light source.

10. The method of claim 8 further comprising a light source positioned in line or perpendicular to the optical sensor.

11. The method of claim 8 further comprising a BDD cell through which the sample passes before the reagents are added, the BDD cell is constructed and arranged to oxidize sulfoxy compounds.

12. The method of claim 8 further comprising a vertically angled sensor flow path through which the sample flows, measured light passing to the optical sensor passes horizontally through the sample.

13. The method of claim 10 in which there are at least two light sources and corresponding optical sensors in line with the light sources, the in line path between the light sources and optical sensors being substantially perpendicular to the flow path of the sample, the sensors being constructed and arranged to measure an optical property of the same volume of the sample in the same region of the flow path.

14. The method in claim 13 wherein all the light sources are turned on and all sensor readings are taken simultaneously.

15. The method of claim 1 where temperature measurements are taken to correct for temperature effects.

16. The method of claim 8 further comprising a tube downstream from the sensor, at least a portion of the tube is higher than the sensor and is horizontally angled, the tube is constructed and arranged to facilitate the migration of gas bubbles away from the sensor, wherein the tube is in one shape selected from the list consisting of:

inverted U-shaped, bent, curved, and angled.

17. The method of claim 8 further comprising a gas source upstream from the sensor, the gas source constructed and arranged to sparge undesired materials away from the sample, wherein a pre-sparge material is added to the sample prior to its sparging the pre-sparge material being one item selected from the list consisting of:

acid, nitric acid, hydrogen peroxide, and any combination thereof, the pre-sparge material increasing the rate of expulsion of undesired materials from the sample.

18. The method of claim 8 in which the apparatus is interfaced with a control system governing at least some of the operations of a chemical process stream from which the sample was taken, the measured data resulting in the control system implementing a counter-measure in response to the property.

19. The method of claim 1 wherein the reagents are selected from the list consisting of:

bromcresol purple, fluorescein, PTSA, TPPTSA, calcein blue, Ferrozine, silver nitrate, thioglycolic acid, ammonia, pH buffer, ferric iron reductant, fluorescent dye, lucigenin, and any combination thereof.

20. The method of claim 1 further comprising the step of adding a foulant removing cleaner to at least one item used to measure a property of the sample, the cleaner being one item selected from the list consisting of:

ethanolamine, methoxy propylamine, ammonium hydroxide, hypochlorite, hydrogen peroxide, nitric acid, and any combination thereof.