Pulse generating system for electrostatic precipitator

• US 7,547,353 B2
• Filed: 10/25/2005
• Issued: 06/16/2009
• Est. Priority Date: 10/26/2004
• Status: Active Grant

• Current Assignee: Flsmidth A/S (Flsmidth & Company A/S)
• Original Assignee: FL Smidth Airtech A/S
• Inventors: Reyes, Victor, Taarning, Claus
• Primary Examiner(s): Chiesa; Richard L
• Application Number:
  US11/666,338
• Publication Number:
  US 20080190295A1
• Time in Patent Office: 1,330 Days
• Field of Search: 96/20, 96/21, 96/80, 96/82, 95/5, 95/80, 95/81, 323/247, 323/903, 361225-235, 363/44
• US Class Current: 96/80
• 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

The invention relates to a pulse generating system for generating high voltage pulses to energize an electrostatic precipitator (10), the system including: a first power supply (1) and a second power supply (2), where said second power supply (2) is arranged to pre-charge said electrostatic precipitator (10) to a DC voltage; a storage capacitor (7) and a series inductance; a switching device (5) coupled in parallel with an anti-parallel rectifier device (6); and wherein the system is arranged to be coupled to the electrostatic precipitator. The invention relates to provide such a pulse generating system with enhanced efficiency compared to present pulse generating systems and with enhanced protection of the components of the system in case of sparks in the electrostatic precipitator (10). This is achieved, when the switching device (5) of the system has turn-off capability and when the system includes a clamping circuit (11-13; 60-67).

Claims

1. A pulse generating system for generating high voltage pulses to energize an electrostatic precipitator (10), said system comprising:

A first power supply (1) and a second power supply (2), where said second power supply (2) is arranged to pre-charge said electrostatic precipitator (10) to a DC voltage;

A storage capacitor (7) and a series inductance;

A clamping circuit;

A switching device (5) coupled in parallel with an anti-parallel rectifier device (6); and

wherein said system is arranged to be coupled to said electrostatic precipitator (10);

characterized in that said switching device (5) has a gate electrode and that said switching device (5) has controllable turn-off capability, being controllable by a gate signal supplied to said gate electrode.

2. A system according to claim 1, characterized in further comprising a transformer (9) with a primary and a secondary winding, and in that

said first power supply (1), said storage capacitor (7), said switching device (5) and said parallel-coupled anti-parallel rectifier device (6), are coupled to said primary winding of said transformer;

said second power supply (2) and a coupling capacitor (8) are coupled to said secondary winding of said transformer (9); and

said system is arranged to be coupled to said electrostatic precipitator (10) via said coupling capacitor (8).

3. A pulse generating system according to claim 1, characterized in that:

said first power supply (1) is connected to one terminal of said storage capacitor (7), where the other terminal of said storage capacitor (7) is connected to one terminal of a primary winding of a transformer (9), and wherein the other terminal of said primary winding of said transformer (9) is connected to a common terminal,

said switching device (5) and said anti-parallel rectifier device (6) are connected in parallel, whereof one terminal of said switching device (5) is connected between said first power supply (1) and said storage capacitor (7) and the other terminal of said switching device (5) is connected to said common terminal,

one terminal of a secondary winding of said transformer (9) is connected to the common terminal and the other terminal of the secondary winding of said transformer (9) is connected to said electrostatic precipitator (10) via a coupling capacitor (8), and

said second power supply (2) is connected to the junction between said coupling capacitor (8) and said electrostatic precipitator (10).

4. A system according to claim 1, characterized in that said switching device (5) is arranged to be turned off before the instant in time of the natural zero-crossing of the pulse current (i_pulse) applied to the electrostatic precipitator.

5. A system according to claim 1, characterized in that said a clamping circuit (11, 12, 13) connected to the junction between the storage capacitor (7) and the first power supply (1).

6. A system according to claim 5, characterized in that said clamping circuit comprises a diode (11) in series with a capacitor (12) and a resistor (13) in parallel with the diode (11).

7. A system according to claim 1, characterized in that said a clamping circuit (60, 61, 62) is connected to the junction between the storage capacitor (7) and a primary winding of a transformer (9), said clamping circuit comprising a series connection of a damping resistor (60), a clamping diode (61) and a capacitor bank (62).

8. A system according to claim 7, characterized in that said clamping circuit moreover comprises a DC power supply (63), a charging resistor (64), a transistor (66), a discharging resistor (65) and a reference diode (67).

9. A system according to claim 1, characterized in that a snubber circuit (14) is connected in parallel to said switching device (5) and said anti-parallel rectifier device (6).

10. A system according to claim 1, characterized in further comprising a bias network connected to a primary winding of a transformer (9), wherein said bias network comprises a voltage source (15), a limiting resistor (16) and a bias choke (17).