Method and apparatus for reducing a nitrogen oxide, and control thereof

• US 7,575,931 B2
• Filed: 06/18/2003
• Issued: 08/18/2009
• Est. Priority Date: 06/19/2002
• Status: Expired due to Fees

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Morris, Patricia A., Barnes, John James, Steichen, John Carl
• Primary Examiner(s): Gakh; Yelena G
• Application Number:
  US10/464,141
• Publication Number:
  US 20040063210A1
• Time in Patent Office: 2,253 Days
• Field of Search: None
• US Class Current: 436/118
• CPC Class Codes: B01D 53/346 Controlling the process
• CPC Class Codes: B01D 53/56 Nitrogen oxides B01D53/60 takes precedence
• CPC Class Codes: B01D 53/79 Injecting reactants
• CPC Class Codes: B01D 53/8625 Nitrogen oxides
• CPC Class Codes: B01D 53/8696 Controlling the catalytic process
• CPC Class Codes: B01D 53/90 Injecting reactants
• CPC Class Codes: F01N 2560/02 the means being an exhaust gas sensor
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: G01N 33/0037 NOx
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10T 436/100833 Simulative of a gaseous composition
• CPC Class Codes: Y10T 436/12 Condition responsive control
• CPC Class Codes: Y10T 436/17 Nitrogen containing
• CPC Class Codes: Y10T 436/177692 Oxides of nitrogen
• CPC Class Codes: Y10T 436/178459 Only nitrogen dioxide
• CPC Class Codes: Y10T 436/179228 Both nitrogen oxide and dioxide

Abstract

Disclosed herein is a method and apparatus for reducing a nitrogen oxide, and the control thereof.

Claims

1. In a multi-component gas mixture that is emitted by an emissions source and contains one or more nitrogen oxide gases, and in which one or more nitrogen oxide gases is reduced by reaction with a reducing agent that is injected into the gas mixture, a method of controlling the reaction of reduction, comprising

(a) determining information related to the compositional content of the gas mixture wherein the information comprises one or more of the following (i) the individual concentration within the gas mixture of a nitrogen oxide gas, (ii) the individual concentration within the gas mixture of a reducing agent, (iii) the individual concentration within the gas mixture of oxygen, and (iv) the collective concentration within the gas mixture of a group of two or more nitrogen oxide gases;

(b) determining from the information determined in step (a) a first operating characteristic of the reaction of reduction that is not in a desired relationship to a second operating characteristic thereof; and

(c) providing an adjustment to the relationship between the first and second operating characteristics, wherein providing the adjustment comprises (i) adjusting the amount or frequency of injection of reducing agent, (ii) employing a plurality of injectors to inject reducing agent and adjusting the timing of injection by injectors in different locations, (iii) heating or cooling the gas mixture, and/or (iv) employing a reduction catalyst and heating or cooling a reduction catalyst;

wherein the information determined in step (a) comprises an output of one or more gas analyzers that comprises an array of chemo/electro-active materials comprising Ni_aZn_bO_x,Sb_aSn_bO_x, and Ta_aTi_bO_x;

wherein a, b, and c are each independently in the range of about 0.0005 to about 1; and

wherein x is a number sufficient so that the oxygen present balances the charges of the other elements present in the chemo/elelctro-active material.

2. A method according to claim 1 wherein the gas mixture is contacted with one or more catalysts for the reduction of a nitrogen oxide, and information as to the compositional content of the gas mixture is determined before the gas mixture contacts any such catalyst.

3. A method according to claim 2 further comprising a step of determining information as to the compositional content of the gas mixture after the gas mixture contacts a catalyst for the reduction of nitrogen oxide.

4. A method according to claim 1 wherein the gas mixture is contacted with one or more catalysts for the reduction of a nitrogen oxide, and information as to the compositional content of the gas mixture is determined after the gas mixture contacts a catalyst.

5. A method according to claim 1 wherein the gas mixture is contacted with first and second catalysts for the reduction of a nitrogen oxide, and information as to the compositional content of the gas mixture is determined after the gas mixture contacts a first catalyst but before the gas mixture contacts a second catalyst.

6. A method according to claim 1 wherein the gas mixture is contacted with one or more catalysts for the reduction of a nitrogen oxide, and information as to the compositional content of the gas mixture is determined after the gas mixture contacts all catalysts.

7. A method according to claim 1, 2, 4 or 6 wherein the information as to the compositional content of the gas mixture is inputted to a map.

8. A method according to claim 1, 2, 4 or 6 wherein the information as to the compositional content of the gas mixture is related to the individual concentration within the gas mixture of an individual nitrogen oxide component therein.

9. A method according to claim 1, 2, 4 or 6 wherein the information as to the compositional content of the gas mixture is related to the collective concentration within the gas mixture of all nitrogen oxide components therein.

10. A method according to claim 1 wherein the gas mixture is transported downstream from the emissions source by an exhaust conduit, and a gas analyzer is located in the conduit.

11. A method according to claim 1, 2, 4 or 6 wherein the determination as to the relationship of operating characteristics is made by a computerized, algorithmic decision-making routine.

12. A method according to claim 1 wherein a gas analyzer outputs at least one signal that is related to the individual concentration within the gas mixture of an individual gas component therein.

13. A method according to claim 1 wherein a gas analyzer outputs at least one signal that is related to the collective concentration within the gas mixture of a subgroup of the component gases therein.

14. A method according to claim 1 wherein a gas analyzer outputs at least one signal that is related to the individual concentration within the gas mixture of an individual gas component therein, and at least one signal that is related to the collective concentration within the gas mixture of a subgroup of the component gases therein.

15. A method according to claim 1 wherein a gas analyzer outputs a signal to a computerized, algorithmic decision-making routine.

16. A method according to claim 1 wherein a gas analyzer outputs a signal to a map.

17. A method according to claim 1 wherein a gas analyzer outputs a signal to a computerized, algorithmic decision-making routine that calculates an amount of reducing agent to be injected.

18. A method according to claim 1 wherein a gas analyzer outputs at least one signal that is related to the individual concentration within the gas mixture of an individual nitrogen oxide component therein.

19. A method according to claim 1 wherein a gas analyzer outputs at least one signal that is related to the collective concentration within the gas mixture of all nitrogen oxide components therein.

20. A method according to claim 1 wherein a gas analyzer outputs at least one signal that is related to the individual concentration within the gas mixture of one or more or all of the nitrogen oxide component(s) therein, and the signal is outputted to a computerized, algorithmic decision-making routine that calculates an amount of reducing agent to be injected.

21. A method according to claim 1 2, 4, 6, or 20 wherein the emissions source is stationary.

22. A method according to claim 1 2, 4, 6, or 20 wherein the emissions source is a vehicle for transportation or recreation or a piece of equipment for construction, maintenance or industrial operations.

23. A method according to claim 1 wherein the gas mixture is contacted with one or more catalysts for the oxidation of a reducing agent, and information as to the compositional content of the gas mixture is determined before or after the gas mixture contacts such catalyst.

24. A method according to claim 1 wherein the information as to the compositional content of the gas mixture is related to the individual concentration within the gas mixture of unreacted reducing agent therein.