DE102009030803A1 - Electrostatic separator for flue gas cleaning with an electric blocking field - Google Patents

Abstract

The present invention relates to an electrostatic precipitator for cleaning flue gases such as those that occur in combustion chambers, wood stoves or other wood burning plants. Electrostatic precipitators include a high voltage supply and a high voltage insulator that is contaminated with soot and ash particle buildup. To reduce pollution, an electrostatic separator is proposed in which the high-voltage insulator is shielded from the flue gas to be cleaned by an electrical blocking field. In this blocking field, the particles contained in the flue gas are electrically charged and deposited on the surface at reference potential and electrically neutralized. As a result, soot and ash particle deposits on the insulator are greatly reduced and the cleaning intervals to avoid voltage flashovers due to these deposits are increased.

Description

The The invention relates to an electrostatic precipitator for cleaning of flue gases, such as in combustion chambers, wood stoves or incurred by other wood burning plants.

electrostatic Separators are generally used to clean flue gas Particle deposition used. The flue gas to be cleaned is introduced into the electrostatic precipitator, which has an ionization stage, for the electric charge of the particles, and a collector stage, for Depositing the charged particles, includes. In the ionization stage the gas to be purified flows through the electric field between a high voltage electrode and one at a reference potential, mostly ground potential, lying electrode in which the flue gas contained particles via corona discharge at the high voltage electrode electrically getting charged. During the subsequent flow through the collector stage, the particles are there on the reference potential lying surface and electrically neutralized.

The mechanism of deposition via space charge is off: " JR Melcher, KS Sachar, EP Warren, Overview of Electrostatic Devices for Control of Submicrometric Particles, Proceedings of the IEEE, vol. 65, no. 12, 1977, p. 1659-1669 " known. The development and application of the space charge separator for the collection of particles from combustion gases is in the CH 649 645 presented. A disadvantage of the electrostatic precipitator described therein is the design-related need for complex assembly and disassembly steps to clean up the system of residues.

A Series of writings describing electrostatic precipitators, which are intended for installation in flue gas pipes.

The DE 10 2008 005 096 describes a separator in a flue pipe, such. B. chimney pipe, can be installed and in which the particles are located in the flue gas when passing the separator initially charged and then deposited on a arranged in the flow direction of the flue gas deposition electrode. Another electrostatic precipitator for installation in flue gas ducts is the EP 1974822 refer to. Also in this device, the electrostatic precipitator flows through in the flow direction of the flue gas. This arrangement has the disadvantage that the efficiency of the particle separation is reduced because already separated particles can be entrained by the gas flow again and thus can increase the emission values.

One Another disadvantage of the known electrostatic precipitator is the pollution of the high voltage insulator, which is in the of the Gas-permeated chamber protrudes, with particles of z. B. Fly ash or soot contained in the flue gas to be cleaned are. This leads to voltage flashovers, reduce the efficiency of the electrostatic precipitator.

outgoing It is the object of the invention to avoid the disadvantages mentioned and to provide an electrostatic precipitator that is efficient Flue gas cleaning ensures a longer service life. Another object of the invention is to shorten the Downtime for cleaning work.

Solved This object is achieved by a device with the features Claim 1. The dependent claims give advantageous embodiments of Device on.

to The solution to the problem becomes an electrostatic precipitator proposed in which the high-voltage insulator of the flue gas to be cleaned is shielded by an electric blocking field. This will be Soot and ash particle deposits on the insulator hard reduced and the cleaning intervals to avoid flashovers due to these deposits are increased.

To shield the high-voltage insulator, a shielding electrode is arranged axially radially to a means for electrically charging particles. These means preferably consist of an element that can be acted upon by a high voltage, which is also referred to as a high-voltage electrode. The shielding electrode is preferably designed tubular, wherein the shape of the cross section can be adapted to the design of the surrounding elements. Upon application of high voltage to the high voltage electrode, an electric field is formed between the high voltage electrode and the shield electrode. Decisive for the strength of the electric field is the size of the gap between the high voltage electrode and the shielding electrode. By radial thickening on the high voltage electrode, the gap, which preferably has the shape of an annular gap can be reduced and the electric field strength in this area is increased. The electric field with increased field strength acts as an additional barrier for the particle-laden flue gas. A portion of the flue gas flows into this area, wherein the particles located in the flue gas are electrically charged and the further passage of the flue gas through the electric field, there is a force on the particles contained in the flue gas (electric Charge carriers), wherein the electrical charge carriers are deposited on the inner wall of the shielding electrode.

By a suitable choice of the outer diameter of radial thickening, which is called a blocking field electrode, at the high voltage electrode in interaction with the inner diameter the shielding electrode is generated a field strength, the an increased deposition of charged particles the shielding electrode lying at reference potential results in but no corona discharge.

In an embodiment of the electrostatic precipitator is next the blocking field electrode at least one further radial thickening at the end of the high voltage electrode protruding from the shield electrode appropriate. The diameter of the Sperrfeldelektrode can thereby from the Distinguish diameter of the other radial thickening. In In this case, when the high-voltage electrode is acted upon, in addition to the electric field between the Sperrfeldelektrode and the shielding electrode, another electric field between the radial thickening outside the shielding electrode and the wall of the electrostatic precipitator formed as these Wall on a reference potential, usually ground potential, is located.

A Another embodiment comprises a blocking field electrode, the protrudes from the shielding electrode. In this case will be on admission the high voltage electrode with a high voltage, in addition to the electrical Field between the Sperrfeldelektrode and the shield, a another electric field between the same Sperrfeldelektrode and the wall of the electrostatic precipitator is formed.

In a particularly preferred embodiment comprises the high voltage electrode at its far end a corona electrode, in addition is arranged to the blocking field electrode. Part of the flue gas flows around this corona electrode and those contained in the flue gas Particles become corona discharge at this corona electrode electrically charged at the high voltage electrode and on the Reference potential lying surface deposited and electrically neutralized. The purified gas flows through the clean gas outlet from the electrostatic precipitator.

The invention is with an embodiment with reference to the 1 explained in more detail. 1 shows a schematic view of the electrostatic precipitator with a Sperrfeldelektrode and a concentrically arranged around this tubular shielding electrode.

The electrostatic precipitator comprises a tubular deposition chamber 1 with a laterally arranged inlet opening 2 for the flue gas and a laterally disposed opening 3 for the exit of the clean gas. The deposition chamber 1 has a lid 13 and a floor 14 , A high voltage insulator 4 is below the lid 13 and above the inlet opening 2 arranged, wherein an annular element 5 serves as a support. On the annular element 5 is also the tubular shielding electrode 11 attached axially into the deposition chamber 1 protrudes. The deposition chamber 1 , the annular element 5 and the tubular shielding electrode 11 are electrically connected to each other and have the same reference potential, preferably ground potential.

A high voltage electrode 6 is in the deposition chamber 1 within the tubular shielding electrode 11 arranged axially and is on the high voltage insulator 4 attached and via a cable 7 in that through an opening channel 8th is guided, connected to a, not shown in the figure, high voltage source. The high voltage electrode 6 has a radial thickening, the Sperrfeldelektrode 12 in the embodiment shown completely in the tubular shielding electrode 11 protrudes.

In the in 1 illustrated embodiment, the high voltage electrode 6 another radial thickening 9 on that in the deposition chamber 1 of the electrostatic precipitator and protrudes from the tubular shielding electrode 11 protrudes. Below the second radial thickening 9 is a corona electrode 10 at the high voltage electrode 6 appropriate.

The shielding electrode 11 causes the direct flow of soot and fly ash particles from the flue gas to the high voltage insulator 4 is prevented. The blocking field electrode 12 at the high voltage electrode 6 causes the formation of an electric field between the blocking field electrode 12 and the shielding electrode located at a reference potential 11 , If charged particles enter this field, they divide on the inner wall of the shielding electrode under the influence of the electric field 11 from. Another electric field forms between the second radial thickening 9 and the reference potential wall of the deposition chamber 1 out. The corona electrode 10 interacts with the surface at reference potential to cause corona discharge, deposition and electrical neutralization of the particles in the flue gas.

LIST OF REFERENCE NUMBERS

1

deposition

2

inlet port for smoke gas inlet

3

opening for clean gaso-ride

4

High-voltage insulator

5

annular Element, support

6

High-voltage electrode

7

electric wire

8th

opening channel

9

radial thickening

10

corona electrode

11

shield

12

Blocking field electrode

13

cover

14

ground

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - CH 649645 [0003]
• - DE 102008005096 [0005]
• EP 1974822 [0005]

Cited non-patent literature

• - JR Melcher, KS Sachar, EP Warren, Overview of Electrostatic Devices for Control of Submicrometric Particles, Proceedings of the IEEE, vol. 65, no. 12, 1977, p. 1659-1669 [0003]

Claims (7)

Electrostatic separator for cleaning particle-laden flue gas comprising, a) a flue gas inlet ( 2 b) means for electrically charging particles ( 6 ) with a high-voltage connection c) separation surfaces ( 1 . 11 ) with a reference potential to the potential of the high voltage terminal for the electrically charged particles d) a high voltage insulator ( 4 ) between high-voltage connection and separation surfaces ( 1 . 11 ) e) a shielding electrode ( 11 ) is arranged around the means for electrically charging particles, characterized in that the means for electrically charging particles comprises a blocking field electrode ( 12 ) for generating an electric reverse field in a gap between the means ( 6 ) and the shielding electrode ( 11 ), wherein the blocking field between flue gas inlet ( 3 ) and high voltage insulator ( 4 ) is arranged. Electrostatic separator according to claim 1, characterized in that the shielding electrode ( 11 ) concentrically around the field electrode ( 12 ) is arranged and the gap is an annular gap. Electrostatic separator according to claim 1 or 2, characterized in that at least one separation surface ( 1 . 11 ) concentrically around the means ( 6 ) is arranged for loading particles. Electrostatic precipitator according to one of Claims 1 to 3, characterized in that the means ( 6 ) for electrically charging particles radial thickening ( 9 ) outside the shielding electrode, wherein annular gaps between the radial thickenings ( 9 ) and the wall of the electrostatic precipitator ( 1 ) consist. Electrostatic separator according to claim 4, characterized in that the radial thickening ( 9 ) and the blocking field electrode ( 12 ) form a coherent electrode. Electrostatic precipitator according to one of Claims 1 to 5, characterized in that the means ( 6 ) for electrically charging particles at their far end a corona electrode ( 10 ). Electrostatic separator according to claim 1, characterized in that the high-voltage insulator ( 4 ) is arranged above the blocking field.

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