Method of operating a boiler

• US 6,289,266 B1
• Filed: 05/14/1999
• Issued: 09/11/2001
• Est. Priority Date: 05/14/1999
• Status: Active Grant

• Current Assignee: Allegheny Power Service Corp. (Firstenergy Corporation)
• Original Assignee: Allegheny Power Service Corp. (Firstenergy Corporation)
• Inventors: Payson, Edward P., Sendro, Daniel V.
• Primary Examiner(s): Gordon, Paul P.
• Application Number:
  US09/312,363
• Time in Patent Office: 851 Days
• Field of Search: 700/82, 700/274, 700/29-31, 700/50, 700/282, 110/345, 110/347, 110/261, 110/234, 110/191, 702/24, 702/136
• US Class Current: 700/274
• CPC Class Codes: F23N 1/02 conjointly with air supply
• CPC Class Codes: F23N 2223/08 Microprocessor; Microcomputer
• CPC Class Codes: F23N 2223/40 Simulation
• CPC Class Codes: F23N 2237/02 two or more burners
• CPC Class Codes: F23N 2237/16 secondary air
• CPC Class Codes: F23N 2239/02 Solid fuels

Abstract

A method of controlling operation of a particulate fuel burning boiler, such as a coal fired boiler, having a plurality of burners each receiving pulverized coal, primary air and secondary air. The flow rate of the pulverized coal, primary air and secondary air is determined independently for each burner and is compared with a model. In the event that the comparison results in a determination that one or more of the flow rates depart from the desired rate by a predetermined amount, a control signal is emitted to adjust the air to flow ratio entering the specific burner. The control signal which alters the air to fuel ratio may result in alteration of the air or fuel flow rates. The method may be employed to reduce NO_x emissions, loss on ignition and to optimize heat rate.

Claims

1. A method of controlling operation of a boiler comprising

providing a boiler having a plurality of burners each receiving particulate solid fuel primary air and secondary air,

determining as to each of a plurality of said burners the flow of said fuel, the flow of said primary air and the flow of said secondary air,

comparing said flow determinations with respect to each said burner with a model of desired flow, and

if a predetermined difference exists between said flow determinations and said model altering at least one of said flow rates to achieve a desired air to fuel ratio in said burner.

2. The method of claim 1 including

employing pulverized coal as said particulate solid fuel.

3. The method of claim 2 including

employing said method on each said burner individually.

4. The method of claim 3 including

achieving the desired air to fuel ratio by altering said secondary air flow.

5. The method of claim 4 including

employing a microprocessor to effect said comparisons and emit a responsive control signal when said flow alteration is to be effected.

6. The method of claim 5 including

employing said method to minimize NO_x emission.

7. The method of claim 5 including

employing said method to minimize loss on ignition.

8. The method of claim 5 including

employing said method to optimize boiler heat rate.

9. The method of claim 3 including

determining said coal flow and said primary air flow in conduits delivering said coal and said primary air to each said burner.

10. The method of claim 9 including

effecting said determination of said primary air flow by calculations based on said coal flow and said secondary air flow.

11. The method of claim 3 including

after effecting a change in the air to fuel ratio on a said burner updating said model.

12. The method of claim 10 including

repeating said method at a predetermined frequency.

13. The method of claim 10 including

employing a single said model for said model, and

effecting a change in said model after each change in the air to fuel ratio of a said burner.

14. The method of claim 3 including

achieving the desired air to fuel ratio by altering said fuel flow.

15. The method of claim 2 further including the step of combining said pulverized coal and said primary air in a single conduit prior to determining said coal flow rate.

16. A method of controlling operation of a particulate solid fuel fired boiler having a plurality of burners comprising monitoring as to each said burner fuel flow, primary air flow, and secondary air flow, and employing a microprocessor to compare said monitored flows with a model and in the event the flow rates depart from said model by a predetermined amount altering said air to fuel ratio for said burners.

17. The method of claim 16 including employing pulverized coal as said particulate solid fuel.

18. The method of claim 17 including

periodically updating said model based upon said monitored flow rates.

19. The method of claim 18 including

employing said method with varying boiler load ranges.

20. The method of claim 19 including

employing said method with a boiler having at least 9 said burners.

21. The method of claim 18 including

employing a single said model for said model, and

effecting a change in said model after each change in the air to fuel ratio of a said burner.

22. The method of claim 16 including

achieving the desired air to fuel ratio by altering said secondary air flow.

23. The method of claim 22 including

employing said method to minimize NO_x emissions.

24. The method of claim 22 including employing said method to minimize loss on ignition.

25. The method of claim 22 including employing said method to optimize boiler heat rate.

26. The method of claim 16 including employing real time measurement of said flow rates.

27. The method of claim 16 including determining said coal flow and said primary air flow in conduits delivering said coal and said primary air to each said burner.

28. The method of claim 27 including

effecting said determination of said primary air flow by calculations based on said coal flow and said secondary air flow.

29. The method of claim 16 including

achieving the desired air to fuel ratio by altering said fuel flow.