Method of operating an electrostatic precipitator

• US 20010011499A1
• Filed: 03/19/2001
• Published: 08/09/2001
• Est. Priority Date: 09/18/1998
• Status: Active Grant

• Current Assignee: Flsmidth A/S (Flsmidth & Company A/S)
• Original Assignee: FL Smidth Airtech A/S
• Inventors: Reyes, Victor
• Granted Patent: US 6,461,405 B2
• Time in Patent Office: Days
• US Class Current: 95/7
• CPC Class Codes: B03C 3/68 Control systems therefor electricity supply or control systems for cleaning the electrodes B03C3/746, B03C3/763
• CPC Class Codes: Y10S 323/903 Precipitators

Abstract

A method of operating an electrostatic precipitator (7) comprises feeding the precipitator with electric power generated by a power supply (10) according to a regime adapted to impart between the precipitator electrodes a voltage having a DC components and an AC component. A control unit (8) measures the electrode voltage, establishes a voltage peak value and a voltage mean value, and computes the product of peak value by mean value to arrive at an index of expected performance (IEP) . Operating set points are tuned so as to maximize this index of expected performance.

Claims

1. A method of operating an electrostatic precipitator, comprising the steps of

intermittently feeding the precipitator with electric power according to a cycle comprising a controlled preset ON-time interval and a preset OFF-time interval in order to apply to the precipitator electrodes a cyclic time-varying voltage,

monitoring the electrode voltage and establishing a voltage peak value and a voltage mean value,

multiplying the established peak value with the established mean value to compute an index of expected performance (IEP),

effecting successive incremental time variations of said ON-time interval and repeating the steps of monitoring and multiplying so as to establish a correlation of said index to said time variations,

establishing a time value of said ON-time interval corresponding to a maximum of said index, and

selecting said established time value as a new set point for said ON-time interval.

2. The method according to

claim 1

, wherein the step of effecting successive incremental variations comprises effecting successive incremental time variations of said OFF-time intervals simultaneously with the effecting successive incremental variations of said ON-time interval.

3. The method according to

claim 2

, wherein the step of effecting successive incremental variations comprises effecting a simultaneous variation of the ON-time interval and the OFF-time interval in such way as to keep the voltage mean value substantially constant.

4. The method according to

claim 2

, wherein the step of effecting successive incremental variations comprises effecting a simultaneous variation of the ON-time interval and the OFF-time interval in such way as to keep the voltage peak value substantially constant.

5. The method according to

claim 1

, wherein power is delivered to the electrostatic precipitator as bursts of current pulses providing a power input sufficient to raise the precipitator voltage at a rate of at least 30 kV/ms.

6. The method according to

claim 5

, wherein the current bursts comprise current pulses pulsating at a frequency of at least 20 kHz.

7. The method according to

claim 1

, wherein power is delivered to the electrostatic precipitator as bursts of current pulses, each burst of current pulses providing a power input sufficient to raise the precipitator voltage from the corona on-set voltage to the maximum rated voltage.

8. The method according to

claim 1

, wherein power is fed to the electrostatic precipitator in surges adapted to raise the precipitator voltage by a rate of at least 10 kV/ms.

9. A method of operating an electrostatic precipitator, comprising the steps of

intermittently feeding the precipitator with electric power according to a cycle comprising a controlled preset ON-time interval and a preset OFF-time interval in order to apply to the precipitator electrodes a cyclic time-varying voltage,

monitoring the electrode voltage and establishing a voltage peak value and a voltage mean value,

multiplying the established peak value with the established mean value to compute an index of expected performance (IEP),

effecting successive incremental time variations of said OFF-time interval and repeating the steps of monitoring and multiplying so as to establish a correlation of said index to said time variations,

establishing a time value of said OFF-time interval corresponding to a maximum of said index, and

selecting said established time value as a new set point for said OFF-time interval.

10. The method according to

claim 9

, wherein the step of effecting successive incremental variations comprises effecting successive incremental time variations of said ON-time intervals simultaneously with the effecting successive incremental variations of said OFF-time interval.

11. The method according to

claim 10

, wherein the step of effecting successive incremental variations comprises effecting a simultaneous variation of the OFF-time interval and the ON-time interval in such way as to keep the voltage mean value substantially constant.

12. The method according to

claim 10

, wherein the step of effecting successive incremental variations comprises effecting a simultaneous variation of the OFF-time interval and the ON-time interval in such way as to keep the voltage peak value substantially constant.

13. The method according to

claim 9

, wherein power is delivered to the electrostatic precipitator as bursts of current pulses providing a power input sufficient to raise the precipitator voltage at a rate of at least 30 kV/ms.

14. The method according to

claim 13

, wherein the current bursts comprise current pulses pulsating at a frequency of at least 20 kHz.

15. The method according to

claim 9

, wherein power is delivered to the electrostatic precipitator as bursts of current pulses, each burst of current pulses providing a power input sufficient to raise the precipitator voltage from the corona on-set voltage to the maximum rated voltage.

16. The method according to

claim 9

, wherein power is fed to the electrostatic precipitator in surges adapted to raise the precipitator voltage by a rate of at least 10 kV/ms.

17. A method of operating an electrostatic precipitator, comprising the steps of

intermittently feeding the precipitator with electric power according to a cycle comprising a controlled preset ON-time interval and a preset OFF-time interval in order to apply to the precipitator electrodes a cyclic time-varying voltage,

monitoring the electrode voltage and establishing a voltage peak value and a voltage mean value,

multiplying the established peak value with the established mean value to compute an index of expected performance (IEP),

effecting successive incremental time variations of said ON-time interval simultaneously with effecting successive incremental time variations of said OFF-time intervals and repeating the steps of monitoring and multiplying so as to establish a correlation of said index to said time variations,

establishing a time value of said ON-time interval and a time value of said OFF-time interval corresponding to a maximum of said index, and

Selecting said respective established time values as new set points for said ON-time interval and said OFF-time interval.

18. The method according to

claim 17

, wherein the step of effecting successive incremental variations comprises effecting a simultaneous variation of the ON-time interval and the OFF-time interval in such way as to keep the voltage mean value substantially constant.

19. The method according to

claim 17

, wherein the step of effecting successive incremental variations comprises effecting a simultaneous variation of the ON-time interval and the OFF-time interval in such way as to keep the voltage peak value substantially constant.

20. The method according to

claim 17

, wherein power is delivered to the electrostatic precipitator as bursts of current pulses providing a power input sufficient to raise the precipitator voltage at a rate of at least 30 kV/ms.

21. The method according to

claim 20

, wherein the current bursts comprise current pulses pulsating at a frequency of at least 20 kHz.

22. The method according to

claim 17

, wherein power is delivered to the electrostatic precipitator as bursts of current pulses, each burst of current pulses providing a power input sufficient to raise the precipitator voltage from the corona on-set voltage to the maximum rated voltage.

23. The method according to

claim 17

, wherein power is fed to the electrostatic precipitator in surges adapted to raise the precipitator voltage by a rate of at least 10 kV/ms.

24. A method of operating an electrostatic precipitator, comprising the steps of

intermittently feeding the precipitator with electric power according to a cycle comprising during a controlled preset ON-time interval a burst of current pulses, pulsating at a frequency of at least 20 kHz and providing to the precipitator a power input sufficient to raise the precipitator voltage at a rate of at least 30 kV/ms, and during a preset OFF-time interval a pause in the feeding in order to apply to the precipitator electrodes a cyclic time-varying voltage,

monitoring the electrode voltage and establishing a voltage peak value and a voltage mean value,

multiplying the established peak value with the established mean value to compute an index of expected performance (IEP),

effecting successive incremental time variations of said ON-time interval simultaneously with effecting successive incremental time variations of said OFF-time intervals and repeating the steps of monitoring and multiplying so as to establish a correlation of said index to said time variations,

establishing a time value of said ON-time interval and a time value of said OFF-time interval corresponding to a maximum of said index, and

selecting said respective established time values as new set points for said ON-time interval and said OFF-time interval.

25. The method according to

claim 24

, wherein power is fed to the electrostatic precipitator in surges adapted to raise the precipitator voltage by a rate of at least 20 kV/ms.

26. The method according to

claim 24

, wherein power is fed to the electrostatic precipitator in surges adapted to raise the precipitator voltage by a rate of at least 30 kV/ms.