Real-time combustion controller

• US 5,599,179 A
• Filed: 08/01/1994
• Issued: 02/04/1997
• Est. Priority Date: 08/01/1994
• Status: Expired due to Fees

• Current Assignee: Mississippi State University
• Original Assignee: Mississippi State University
• Inventors: Etheridge, John A., Shepard, W. Steve, Gresham, Lawrence L., Jang, Ping-Rey, Lindner, Jeffrey S.
• Primary Examiner(s): Price, Carl D.
• Application Number:
  US08/283,795
• Time in Patent Office: 918 Days
• Field of Search: 431/76, 431/79, 431/75, 431/12, 356/318, 436/143, 250/339
• US Class Current: 431/12
• CPC Class Codes: F23N 1/02 conjointly with air supply
• CPC Class Codes: F23N 5/003 using detectors sensitive to combustion gas properties F23N5/02, F23N5/18 - F23N5/26 take precedence
• CPC Class Codes: F23N 5/082 using electronic means
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A method and system of regulating the air to fuel ratio supplied to a burner to maximize the combustion efficiency. Optical means are provided in close proximity to the burner for directing a beam of radiation from hot gases produced by the burner to a plurality of detectors. Detectors are provided for sensing the concentration of, inter alia, CO, CO₂, and H₂ O. The differences between the ratios of CO to CO₂ and H₂ O to CO are compared with a known control curve based on those ratios for air to fuel ratios ranging from 0.85 to 1.30. The fuel flow is adjusted until the difference between the ratios of CO to CO₂ and H₂ O to CO fall on a desired set point on the control curve.

Claims

1. A method of regulating the air to fuel ratio supplied to a burner to maximize combustion efficiency comprising the steps of:

(a) placing optical means in close proximity to the burner but downstream thereof for directing a beam of radiation from hot gases produced by said burner toward a plurality of detectors;

(b) sensing with a first detector the intensity of the infrared radiation emitted from said hot gases in a first wavelength band to determine the concentration of a first constitutent in said hot gases;

(c) sensing with a second detector the intensity of the infrared radiation emitted from said hot gases in a second wavelength band to determine the concentration of a second constituent in said hot gases;

(d) sensing with a third detector the intensity of the infrared radiation emitted from said hot gases in a third wavelength band to determine the concentration of a third constituent in said hot gases;

(e) computing as a first ratio the intensity of the first constituent to the intensity of the second constituent and computing as a second ratio the intensity of the third constituent with respect to the first constituent;

(f) subtracting the second ratio from the first ratio;

(g) comparing the result of step (e) with a known control curve representing the differences between said first and second ratios for stoichiometry values ranging from a fuel rich value of 0.85 to a fuel lean ratio of 1.30; and

(h) adjusting the fuel flow to said burner until the difference between said ratios falls on a desired set point on said control curve.

2. A system for regulating the air to fuel ratio supplied to a burner to maximize combustion efficiency comprising:

(a) optical means located in close proximity to said burner but downstream thereof for directing a beam of radiation from hot gases produced by said burner toward a plurality of detectors;

(b) a first detector for sensing the intensity of infrared radiation emitted from said hot gases in the wavelengths between 4720 nm and 5100 nm adapted to determine the concentration of CO in said hot gases;

(c) a second detector for sensing the intensity of infrared radiation emitted from said hot gases in the wavelengths of 4381 nm±

180 nm adapted to determine the concentration of CO₂ in said hot gases;

(d) a third detector for sensing the intensity of infrared radiation emitted from said hot gases in the wavelengths of 2690 nm±

50 nm adapted to determine the concentration of H₂ O in said hot gases;

(e) means for computing the ratio of CO to CO₂ and the ratio of H₂ O to CO;

(f) means for subtracting the ratio of H₂ O to CO from a ratio of CO to CO₂ ;

(g) means for comparing the results obtained from the means for subtracting with a known control curve representing the difference between the ratio of CO to CO₂ and H₂ O to CO for stoichiometry values ranging from a fuel rich value of 0.85 to a fuel less value of 1.30; and

(h) means for adjusting the fuel flow to said burner on the basis of the result obtained from said means for comparing until the difference between the ratio of CO to CO₂ and H₂ O to CO falls on a desired set point on said control curve.