Method and apparatus for improved process control in combustion applications

• US 20040191712A1
• Filed: 04/07/2004
• Published: 09/30/2004
• Est. Priority Date: 06/26/2000
• Status: Active Grant

• Current Assignee: Jason J. Nikkari, Murray J. Thomson
• Original Assignee: Jason J. Nikkari, Murray J. Thomson
• Inventors: Nikkari, Jason J., Thomson, Murray J.
• Granted Patent: US 7,217,121 B2
• Time in Patent Office: Days
• US Class Current: 431/12
• CPC Class Codes: B08B 7/00 Cleaning by methods not provided for in a single other subclass or a single group in this subclass
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 1/008 Soldering within a furnace B23K1/012 takes precedence
• CPC Class Codes: B23K 1/012 Soldering with the use of hot gas
• CPC Class Codes: B23K 1/206 Cleaning
• CPC Class Codes: C21C 2005/5288 Measuring or sampling devices
• CPC Class Codes: C21C 5/4673 Measuring and sampling devices
• CPC Class Codes: C21C 5/5217 equipped with burners or devices for injecting gas, i.e. oxygen, or pulverulent materials into the furnace
• CPC Class Codes: F23G 2900/55003 Sensing for exhaust gas properties, e.g. O2 content
• CPC Class Codes: F23J 2215/40 Carbon monoxide
• CPC Class Codes: F23N 5/003 using detectors sensitive to combustion gas properties F23N5/02, F23N5/18 - F23N5/26 take precedence
• CPC Class Codes: F27B 3/085 Arc furnaces
• CPC Class Codes: F27B 3/225 Oxygen blowing
• CPC Class Codes: F27B 3/28 Arrangement of controlling, monitoring, alarm or the like devices
• CPC Class Codes: G01N 2021/536 Measurement device mounted at stack
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/85 Investigating moving fluids or granular solids
• CPC Class Codes: G01N 2201/127 Calibration; base line adjustment; drift compensation
• CPC Class Codes: H05K 2203/095 : Plasma, e.g. for treating a substrate to improve adhesion with a conductor or for cleaning holes
• CPC Class Codes: H05K 3/3489 : Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces
• CPC Class Codes: Y02P 10/20 : Recycling

Abstract

This invention relates to a method and apparatus for improved process control in combustion applications, and particularly those relating to the steelmaking industry. An apparatus is provided for process control in a combustion application comprising a laser to transmit a near-infrared laser beam through off-gas produced by the combustion application, a detector to detect the transmitted laser beam and convert the detected laser beam to an electrical signal, and a control system for providing adjustment of select inputs to the combustion application in response to the electrical signal from the detector. The method of this invention comprises transmitting a near-infrared laser beam through off-gas produced by the combustion application, detecting the transmitted laser beam, and adjusting select inputs of the combustion application in response to the detected transmitted laser beam.

Claims

1. A method for process control in a combustion application, comprising:

a) transmitting a frequency modulated near-infrared laser beam through off-gas produced by the combustion application to target CO and H2O;

b) detecting the transmitted laser beam;

c) analyzing the detected laser beam for select CO and H2O absorption lines;

d) determining the CO concentration from the CO and H2O absorption lines;

e) adjusting select inputs of the combustion application in response to the CO concentration.

2. A method according to claim 1 wherein CO concentration is determined using predetermined calibration curves.

3. A method according to claim 2 wherein the calibration curve is CO concentration as a function of CO absorption lines and temperature.

4. A method according to claim 3 wherein the H2O absorption lines are used to determine the temperature of the off-gas

5. A method according to claim 4 wherein the targeted H2O has absorption lines that respond differentially to changes in temperature.

6. A method according to claim 4 wherein the temperature of the off-gas is determined from the ratio of two H2O absorption lines;

7. A method according to claim 1 wherein the targeted CO has a profile of strong absorption lines as compared to H2O.

8. A method according to claim 1 wherein the CO absorption line is located at 1577.96 nm, and the H2O absorption lines are located at 1577.8 nm and 1578.1 nm.

9. A method according to claim 1 wherein the wavelength of the laser beam is in the range of about 0.7 μ

m to about 3.0 μ

m.

10. A method according to claim 1 wherein the near-infrared laser beam is transmitted by a tunable diode laser.

11. A method according to claim 10 wherein the wavelength of the laser beam is in the range of about 1.5 μ

m to about 1.7 μ

m.

12. A method according to claim 1 wherein the near-infrared laser beam is transmitted by a distributed feedback laser.

13. A method according to claim 12 wherein the wavelength of the laser beam is in the range of about 1.57 μ

m to about 1.59 μ

m.

14. A method according to claim 1 wherein the select inputs to the combustion application comprise oxygen.

15. A method according to claim 1 wherein the select inputs to the combustion application comprise fuel.

16. A method according to claim 1 wherein the select inputs to the combustion application comprise electric power.

17. A method according to claim 14 wherein the select inputs to the combustion application comprise fuel.

18. A method according to claim 14 wherein the select inputs to the combustion application comprise electric power.

19. A method according to claim 15 wherein the select inputs to the combustion application comprise electric power.

20. A method according to claim 17 wherein the select inputs to the combustion application comprise electric power.