Flame sensor integrity monitoring

• US 8,993,966 B2
• Filed: 09/26/2012
• Issued: 03/31/2015
• Est. Priority Date: 09/26/2012
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Cole, Barrett E.
• Primary Examiner(s): Kim, Kiho
• Application Number:
  US13/627,718
• Publication Number:
  US 20140084166A1
• Time in Patent Office: 916 Days
• Field of Search: 250/342
• US Class Current: 250/342
• CPC Class Codes: G01J 1/0228 Control of working procedures; Failure detection; Spectral bandwidth calculation
• CPC Class Codes: G01J 1/08 Arrangements of light sources specially adapted for photometry standard sources, also using luminescent or radioactive material
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/026 Control of working procedures of a pyrometer, other than calibration; Bandwidth calculation; Gain control
• CPC Class Codes: G01J 5/60 using determination of colour temperature
• CPC Class Codes: G01J 5/80 Calibration using comparison with reference sources G01J5/52

Abstract

A flame detector includes a medium wavelength infrared bolometer having an array of pixel elements disposed within a housing. Optics supported by the housing and disposed with respect to the bolometer direct infrared radiation from a flame to the pixel elements of the array and direct radiation from a separate background object to the pixel elements of the array. Electronics are coupled to receive signals from the bolometer and programmed to track an intensity of radiation from the background object to monitor transmission of radiation through the optics.

Claims

1. A flame detector comprising:

a medium wavelength infrared bolometer having an array of pixel elements disposed within a housing;

optics supported by the housing and disposed with respect to the bolometer to direct infrared radiation from a flame to the pixel elements of the array and to direct radiation from a separate background object to the pixel elements of the array; and

electronics coupled to receive signals from the bolometer and programmed to track an intensity of radiation from the background object to monitor transmission of radiation through the optics.

2. The flame detector of claim 1 wherein the bolometer detects radiation from the background object comprising the sun at a selected part of a day.

3. The flame detector of claim 1 wherein the bolometer detects radiation from the background object comprising a non-flame object of known brightness in a set of pixel elements separate from pixel elements receiving radiation from the flame.

4. The flame detector of claim 1 wherein the bolometer detects radiation from the background object comprising medium wavelength infrared radiation from a background environment within a field of view of the bolometer.

5. The flame detector of claim 4 wherein pixel elements receiving radiation from the ground are used to monitor transmission of radiation through the optics.

6. The flame detector of claim 1 and further comprising a temperature sensor coupled to provide a sensed ambient temperature proximate the housing to the electronics.

7. The flame detector of claim 6 wherein the electronics is adapted to compensate for temperature while monitoring transmission of radiation through the optics, and wherein the temperature sensor is proximate the background object and provides a visual indication of the temperature proximate the background object, and wherein the electronics is adapted to obtain an image of the visual indication to obtain the temperature.

8. The flame detector of claim 1 wherein the electronics uses the tracked intensity of radiation from the background object to scale a threshold for flame detection.

9. The flame detector of claim 1 wherein the electronics is adapted to provide an indication regarding optics maintenance when the intensity of transmission through the optics is below a specified threshold.

10. A method comprising:

sensing radiation received through optics using a mid-wavelength infrared bolometer array of pixels with a portion of a field of view of the bolometer to sense a flame;

sensing background radiation via the bolometer within the field of view of the bolometer; and

detecting a change of intensity of the sensed background radiation.

11. The method of claim 10 and further comprising providing an indication when maintenance should be performed the optics associated with the bolometer due to a decrease in radiation transmission through the optics.

12. The method of claim 10 and further comprising adjusting a threshold for identifying a flame based on the detected change of intensity.

13. The method of claim 10 and further comprising:

sensing an ambient temperature; and

using the sensed ambient temperature to adjust the detected change of intensity of the sensed background radiation.

14. The method of claim 10 wherein the sensed background radiation comprises radiation from the Sun at a selected time of day.

15. The method of claim 14 wherein the change of intensity is detected over many days.

16. The method of claim 10 wherein the sensed background radiation comprises mid wavelength infrared radiation from the ground.

17. A non-transitory computer readable storage device having instructions for causing a computer to execute a method, the method comprising:

receiving data representing sensed radiation received through optics using a mid-wavelength infrared bolometer array of pixels with a portion of a field of view of the bolometer to sense a flame;

receiving data representative of sensed background radiation via the bolometer within the field of view of the bolometer; and

calculating a change of intensity of the sensed background radiation.

18. The non-transitory computer readable storage device of claim 17 wherein the method further comprises providing an indication when maintenance should be performed the optics associated with the bolometer due to a decrease in radiation transmission through the optics.

19. The non-transitory computer readable storage device of claim 17 wherein the method further comprises adjusting a threshold for identifying a flame based on the detected change of intensity.

20. The non-transitory computer readable storage device of claim 17 wherein the method further comprises:

receiving data representative of sensed ambient temperature;

using the sensed ambient temperature to adjust the detected change of intensity of the sensed background radiation; and

using the change of intensity of sensed background radiation to scale a threshold for flame detection.