Acoustical burner control system and method

• US 5,120,214 A
• Filed: 01/31/1991
• Issued: 06/09/1992
• Est. Priority Date: 11/13/1989
• Status: Expired due to Fees

• Current Assignee: Control Techtronics Incorporated
• Original Assignee: Control Techtronics Incorporated
• Inventors: Carlyle, John M., West, John S., Shefet, David A.
• Primary Examiner(s): Price, Carl D.
• Application Number:
  US07/649,258
• Time in Patent Office: 495 Days
• Field of Search: 431/18, 431/12, 431/75, 431/76, 431/78, 236/1 A, 236/15 BA, 340/577
• US Class Current: 431/12
• CPC Class Codes: F23N 1/02 conjointly with air supply
• CPC Class Codes: F23N 2221/12 Recycling exhaust gases
• CPC Class Codes: F23N 2225/04 pressure
• CPC Class Codes: F23N 2227/20 Calibrating devices
• CPC Class Codes: F23N 2235/06 at the air intake
• CPC Class Codes: F23N 2235/10 power assisted, e.g. using electric motors
• CPC Class Codes: F23N 2235/12 Fuel valves
• CPC Class Codes: F23N 5/006 the detector being sensitive to oxygen
• CPC Class Codes: F23N 5/16 using noise-sensitive detectors

Abstract

An acoustically operated burner control system for optimally controlling a flow of air and fuel into a flame producing combustion burner throughout a range of firing rates is disclosed. The system includes separate valve assemblies for modulating the flow of air and fuel into a burner, a microphone for generating an electrical signal indicative of the intensity of all sounds generated by the combustion flame having a frequency in excess of about 10 Khz, and a controller including a programmable microprocessor electrically connected to both the air and fuel valve assemblies and the microphone. The system further includes a wave guide for remotely acoustically coupling the microphone to the combustion flame in order to isolate the microphone from both heat and corrosive combustion products. Prior to the operation of the system, empirically-derived sound intensities associated with optimum stoichiometric combustion and minimum pollution are entered into the memory of the microprocessor. During operation, the microprocessor equates the sound intensity sensed by the microphone with the optimum sound intensity in its memory by regulating the position of the air and fuel valve assemblies.

Claims

1. A method for optimally controlling a burner control system that includes an air valve assembly and a fuel valve assembly for modulating air and fuel to a flame producing combustion burner over a range of firing rates, comprising the steps of:

monitoring the level of sound intensity of all sounds produced by the combustion flame of the burner by a microphone means acoustically coupled to the flame by an acoustical waveguide having a distal end disposed within the envelope of said combustion flame, and

maintaining the level of the aggregate sound intensity of all sounds produced by the combustion flame of the burner that have an acoustical frequency above 10 Khz at a pre-selected level associated with optimality by adjusting said air and fuel valve assemblies.

2. A burner control method as defined in claim 1, further including the step of obtaining, for each point along said range of firing rates, the sound intensity level associated with optimality by measuring the level of the sound intensity of said sounds while simultaneously measuring the amount of oxygen present in the combustion products of said flame associated with different settings of said air and fuel valve assemblies.

3. A burner control method as defined in claim 2, wherein the amount of pollutants present in the combustion products of said flame is also measured.

4. A burner control method as defined in claim 1, wherein the level of the sounds equated have an acoustical frequency above 20 Khz.

5. A burner control method as defined in claim 1, wherein the level of sounds equated have an acoustical frequency above 30 Khz.

6. A burner control method as defined in claim 1, wherein the level of sound intensity of all sounds produced by the combustion flame of the burner is measured by a microphone means having a bandwidth that includes only those acoustical frequencies that are over 10 Khz.

7. An acoustically operated burner control system for optimally controlling a flow of air and fuel into a flame-producing combustion burner throughout a range of firing rates, comprising:

first and second valve assemblies for modulating the flow of air and fuel into the burner;

a microphone means for generating an electrical signal indicative of the aggregate intensity of all sounds generated by said combustion flame that are above 1 Khz in frequency,

an acoustical waveguide for acoustically coupling said microphone means to said flame and isolating the microphone means from the heat generated by the flame, and

a controller operatively connected to the first and second valve assemblies and electrically connected to said microphone means for maintaining the aggregate sound intensity of all sounds generated by said combustion flame that are above 1 Khz in frequency at a pre-selected level associated with optimality at each point within said range of burner firing rates.

8. An acoustically operated burner control system for optimally controlling a flow of air and fuel into a flame-producing combustion burner throughout a range of firing rates, comprising:

first and second valve assemblies for modulating the flow of air and fuel into the burner;

a microphone means for generating an electrical signal indicative of the aggregate intensity of all sounds generated by said combustion flame that are above 1 Khz in frequency;

an acoustical waveguide having a distal end disposed within the envelope of said combustion flame for acoustically coupling said microphone means to said flame and isolating the microphone means from the heat generated by the flame, and

a controller operatively connected to the first and second valve assemblies and electrically connected to said microphone means for maintaining the aggregate sound intensity of all sounds generated by said combustion flame that are above 1 Khz in frequency at a pre-selected level associated with optimality at each point within said range of burner firing rates.

9. An acoustically operated burner control system as defined in claim 8, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 5 Khz.

10. An acoustically operated burner control system as defined in claim 8, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 10 Khz.

11. An acoustically operated burner control system as defined in claim 8, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 20 Khz.

12. An acoustically operated burner control system as defined in claim 8, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 30 Khz.

13. An acoustically operated burner control system as defined in claim 8, wherein said valve means are each electrically controlled, and wherein said controller is electrically connected to each of said valves.

14. An acoustically operated burner control system as defined in claim 8, wherein said burner is enclosed in a furnace housing, and said microphone means is located outside of said housing, and said acoustical waveguide further functions to isolate the microphone means from the combustion products generated by the flame.

15. An acoustically operated burner control system as defined in claim 8, wherein said controller includes a microprocessor having a memory, and wherein said preselected sound levels are entered into the memory of the microprocessor.

16. An acoustically operated burner control system as defined in claim 8, further comprising a probe means for determining the aggregate sound intensities associated with optimality by measuring the amount of oxygen present in the combustion products of said flame at different settings of said first and second valve means.

17. An acoustically operated burner control system for optimally controlling a flow of air and fuel into a flame producing combustion burner throughout a range of firing rates, comprising:

first and second electrically operated valve assemblies for modulating the flow of air and fuel into the burner;

a microphone means of generating an electrical signal indicative of the aggregate intensity of all sounds generated by said combustion flame having a frequency above 10 Khz;

a solid acoustical waveguide having a distal end disposed within the envelope of said combustion flame for acoustically coupling said microphone means directly to the envelope of said flame and isolating the microphone means from the heat generated by the flame;

a probe means for establishing the aggregate sound intensity associated with an optimal flow of air and fuel into the burner for each point throughout the firing range of the burner, and

a controller including a microprocessor having a memory for storing each of said sound levels associated with optimality, an output electrically connected to said first and second valve assemblies; and

an input electrically connected to said microphone means, wherein said controller maintains the aggregate sound intensity of all sounds having a frequency above 10 Khz that are associated with optimality at each point along said firing range of said burner by modulating said valve assemblies to equate the sound intensity sensed by said microphone means with the sound intensity entered into said microprocessor memory, and wherein each level of optimality is associated with an aggregate sound intensity which is less than the sound intensity associated with an excess air condition but greater than the sound intensity associated with an excess fuel condition.

18. An acoustically operated burner control system as defined in claim 17, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 20 Khz.

19. An acoustically operated burner control system as defined in claim 17, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 30 Khz.

20. An acoustically operated burner control system as defined in claim 17, wherein said burner is enclosed in a furnace housing, and said microphone means is located outside of said housing, and said acoustical waveguide further functions to isolate the microphone means from the combustion products generated by the flame.

21. An acoustically operated burner control system for optimally controlling a flow of air and fuel into a flame producing combustion burner, comprising:

a microphone means for generating an electrical signal indicative of the aggregate intensity of the sound generated by said combustion flame above 10 Khz in frequency;

a solid acoustical waveguide for acoustically coupling said microphone means to said flame and isolating the microphone means from the heat generated by the flame, and

a monitoring means electrically connected to the output of the microphone means for recording the aggregate sound intensity above 10 Khz generated by said combustion flame so that said aggregate sound intensity may be compared to a pre-selected sound intensity above 10 Khz in frequency associated with optimality.

22. An acoustically operated burner control system as defined in claim 21, further comprising a means for comparing the aggregate sound intensity detected by the microphone means, and the pre-selected sound intensity above 10 Khz in frequency, and for generating an alarm signal when said sound intensities are not substantially equal.

23. An acoustically operated burner control system as defined in claim 21, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 20 Khz.

24. An acoustically operated burner control system as defined in claim 21, wherein the bandwidth of the microphone means includes only acoustical frequencies greater than 30 Khz.

25. A method for optimally controlling a burner control system that includes an air valve assembly and a fuel valve assembly for modulating air and fuel to a flame producing combustion burner over a range of firing rates, comprising the steps of:

monitoring the level sound intensity of all sounds produced by the combustion flame of the burner by a microphone means acoustically coupled to the flame by a solid acoustical waveguide having a distal end disposed within the envelope of said combustion flame;

obtaining, for a plurality of points long said range of firing rates, the sound intensity level associated with stoichiometric optimality by measuring the level of intensity of all sounds having frequencies of over 10 Khz generated by said combustion flame when said burner is burning air and fuel at a stoichiometric ratio at said points along said firing rate;

interpolating and recording a sound level for each point along the firing range of said burner that is associated with optimality;

operating said burner at a selected point along said firing range, and

maintaining the sound intensity level of all sounds generated by the combustion flame having acoustical frequencies of over 10 Khz at the optimal sound level associated with said selected point along said firing range by adjusting said valve assemblies.

26. An acoustically operated burner monitoring system for optimally sensing optimal burning conditions in a flame producing combustion burner, comprising:

a microphone means for generating an electrical signal indicative of the aggregate intensity of the sound generated by said combustion flame above 10 Khz in frequency,

an acoustical waveguide having a distal end disposed within the envelope of said combustion flame for acoustically coupling said microphone means to said flame and isolating the microphone means from the heat generated by the flame, and

a monitoring means electrically connected to the output of the microphone means for recording the aggregate sound intensity above 10 Khz generated by said combustion flame so that said aggregate sound intensity may be compared to a pre-selected sound intensity above 10 Khz in frequency associated with the minimum generation of pollutants, and record the burner performance for pollutants, and alarm when pollutants are above a prescribed threshold.

27. An acoustically operated burner monitoring system as defined in claim 26, further comprising a means for comparing the aggregate sound intensity detected by the microphone means, and the pre-selected sound intensity above 10 Khz in frequency, and for generating an alarm signal when said sound intensities are not substantially equal.

28. An acoustically operated burner monitoring system as defined in claim 26, wherein the bandwidth of said microphone means includes only acoustical frequencies greater than 20 Khz.

29. An acoustically operated burner monitoring system as defined in claim 26, wherein the bandwidth of the microphone means includes only acoustical frequencies greater than 30 Khz.

30. An acoustically operated burner monitoring system as defined in claim 26, further comprising first and second manually operated valve assemblies for modulating the flow of air and fuel into the burner.