EP2244834B1 - Electrostatic precipitator - Google Patents

Abstract

An electrostatic precipitator for removing solid and liquid components from an aerosol includes a precipitator housing having a raw gas inlet for an aerosol to be cleaned, a clean gas outlet for cleaned aerosol, and at least one aerosol supply channel flange-mounted to the raw gas inlet, a drain device for solid and liquid components that are separated from the aerosol, an ionization stage externally powered via a high-voltage bushing and including at least one metallic high-voltage rod that extends into a flow path of the aerosol and to which high voltage is applyable, and a collector stage disposed in the flow path downstream of the ionization stage.

Description

The invention relates to an electrostatic precipitator for removing the solid and liquid components from an aerosol.

Such a separator consists of a separator housing having an access, the raw gas inlet, for the aerosol to be cleaned and an outlet, the clean gas outlet, for the purified aerosol. At least one flow channel leading in the aerosol flanges to the raw gas inlet. The freed of the solid and liquid particles gas exits the separator as pure gas, either immediately into the environment or is passed on in a flanging channel on. Usually located in the collector region of the separator, a discharge device for the discharge of there excreted from the aerosol, accumulated, solid and liquid components. An electrical high-voltage bushing electrically supplies an ionization stage in the separator from the outside. The ionization stage consists of at least one protruding into the flow path of the aerosol metallic, acted upon by electrical high voltage rod, which is equipped with radially serrated electrode discs and in the corona discharges, the solid and liquid particles are electrically charged in the gas flowing past. In the separator, downstream of the ionizer, there is a collector device in which the solid and liquid particles of the gas stream are deposited.

Electrostatic precipitators are the most effective means of cleaning fine and ultrafine aerosols. Electrostatic precipitators have several advantages over gas purifiers of other technology: they require less energy than mechanical collector devices and have no moving parts; Maintenance costs are low and downtime is low.

The construction of a compact electrostatic precipitator of high efficiency for drop aerosols is described in US Pat US 6,221,136 described. The electrostatic precipitator has a high voltage electrode with multiple wire segments positioned within an electrically conductive porous medium and having a central axis, on which the electrode structure expands. The electrode assembly consists of a plurality of longitudinally positioned wires which propagate along the longitudinal axis of the porous medium. The wire segments are arranged to have a substantially longer overall length than the extension length along the longitudinal axis. The particles are passed through the porous medium and past the electrode and are charged via the high voltage. The porous medium has a substantially lower voltage than the high voltage electrode. The flow of the aerosol charged at the electrodes passes through the porous medium to the exit, whereby the charged particles are deposited in the porous medium. Electrostatic shields are mounted around the high voltage insulators to reduce the likelihood of insulator contamination causing leakage currents.

Despite this structure, the separator has several problems. First, during processing with sticky aerosols, the electrodes are covered with particles which reduce the efficiency of the separator. Second, the insulator is positioned inside the collector where the charged particles are and which form the space charge. Part of the charged droplets can settle on the insulator surface under the influence of the space charge, which then leads to contamination of the insulator surface. Third, the distance between the electrostatic shields and the housing of the separator is small. If the shields are covered with particles, this can lead to flashovers within the separator. The spark discharges reduce the efficiency of the collector. The porous medium as a collector plays the following two roles: first, it is used as a grounded electrode; second, it collects aerosol particles, which can be droplets and solid particles. Covering the filter surface with a dielectric fluid, such as lubricating oil, will weaken the electric field strength in the electrode assembly, thereby reducing the efficiency of the particle charge.

These problems are essentially due to those in the DE 102 44 051 or DE 10 2004 037 286 avoided. In the DE 102 44 051 an electrostatic precipitator is presented, the an ionizer with multiple needle or star electrodes installed downstream in a grounded nozzle plate. The charged particles are collected in a collector installed downstream of the ionizer ( DE 102 44 051 and DE 10 2004 037 286 ). Due to the small distance between the high voltage and the grounded electrode in the electrode assembly, there is a strong electric field in the particle charge zone. Compared with conventional electrostatic precipitators, this allows operation with relatively small high voltages, <20 kV, to the particle charge. The gas stream flows at high speed through the ionizer and at low speed through the collector, the actual filter. The high velocity of the gas stream in the ionizer stabilizes the operation of the electrostatic precipitator, reduces the influence of the space charge on the charged particles and reduces the suppression of the corona discharge. The low velocity in the collector improves its efficiency and reduces the pressure drop in it. The grounded electrode in the electrode assembly and the collector are spatially separated. This reduces the clogging of the collector. The grounded grid / mesh or nozzle allows the passage of charged aerosol particles. The electric wind can pass through the mesh electrode without pressure loss. The use of star-shaped electrodes and the high speed in the electrode zone reduces the deposition of sticky particles or droplets on the high voltage electrodes.

Despite these improvements in the efficiency of particle loading and deposition, the use of low operating high voltage, the stability of operation due to corona suppression and the avoidance of deposition on the electrode assembly, the separator is relatively bulky due to the spatial separation of the ionization stage from the collector. The high-voltage insulator is positioned in the raw gas or clean gas flow, which is why additional measures against contamination are necessary.

Therefore, the task arose to build a compact electrostatic precipitator with high operational reliability. The should High operating voltage of the separator also remain low. The efficiency of the collector as well as the long-term operational stability should be able to be granted. This object is based on the invention.

The object is solved by the features characterized in claim 1. Useful, advantageous features of the electrostatic precipitator are described in claims 2 and 3.

In claims 4 to 6, 7 and 8, 9 to 12, 13 and 14 and 15 and 16 of claim 1 derivable embodiments of the electrostatic precipitator are characterized and described.

The compact electrostatic precipitator consists, as is known, of the two housed in a separator housing assemblies: ionization and downstream gas collector following collector.

The electrostatic precipitator has at least one metallic high-voltage rod which, clamped in an insulator at the end face, protrudes into the gas flow path via this isolator, which is seated away from the gas flow path of the aerosol. The high-voltage insulator is in a pot-like, not traversed by the aerosol, to an electrical reference potential, usually ground potential, connected housing, the insulator housing, positioned and exposed therein.

The high-voltage rod is equipped with a disc-shaped electrode, the high-voltage electrode, at least at its free end portion and another disc-shaped electrode, the guard electrode, outside the insulator housing at a distance d to the opening in the bottom plate. The guard electrode sits on the edge or outside the gas flow. The high voltage electrode and guard electrode have radially directed circumferentially equally spaced tips adjacent to the surrounding hollow cylindrical sleeve of perforated sheet metal or wire mesh, the grid or wire mesh electrode, having the smallest pitch H. The high-voltage rod protrudes coaxially into the grid or wire mesh electrode, which sits with its first end face positively in the opening to the insulator housing and to the reference potential, usually ground potential, is connected. To the extent of High voltage electrode / n and the guard electrode are equally distributed cleavage of the smallest width H to the surrounding grid or wire mesh electrode.

The grid or wire mesh electrode is seated with its second end portion in a nozzle in the lying on electrical reference potential plate, the nozzle plate, or abuts with its second end on a gas-impermeable plate, the face plate. Thereby, the grid or wire mesh electrode (s) are positioned in the gas flow path of the aerosol.

The grid or wire mesh electrode (s) is / are completely surrounded by a porous collector located at electrical reference potential highest over its length. As a result, the entire aerosol stream must in any case flow through the porous collector.

In the insulator housing sits according to claim 2, a high-voltage bushing, through which the high-voltage rod or the high-voltage rods are connected from the outside to a high voltage electrical potential. Depending on the design of the separator, see below, the high-voltage feedthrough go directly or through the separator housing through to the outside. According to claim 3 sits in the insulator housing further a pipe socket through which a clean gas can be flowed into the interior of the insulator housing under pressure that in the insulator housing overpressure, at least a slight overpressure, compared to the pressure in the housing of the separator. This would also avoid an inflow of process to be processed aerosol. The inflow of clean gas or pure air through this pipe socket can also be done with a predetermined temperature, preferably with a higher temperature than in the space of the high voltage rod with electrodes and the grid or wire mesh electrode. The then existing temperature gradient from insulator housing to separator housing, the influx of aerosol would be additionally suppressed.

From this, the embodiment of the electrostatic precipitator described in claim 4 can be developed. The insulator housing for the High voltage insulator sits concentrically on the over the clear cross section of the separator housing reaching bottom plate. In the insulator housing sits the high-voltage insulator with a freely exposed forehead. The high-voltage rod is stuck with a frontal area in the exposed forehead of the high-voltage insulator. The grid or mesh electrode sets with its one end portion in the central passage of the bottom plate. With its other end region, the mesh or mesh electrode inserted through the nozzle in the seated on the clear cross-section of the separator housing nozzle plate. According to claim 5, the bottom plate between the insulator housing and the wall of the separator housing for the gas flow is continuous. In this embodiment, the separator housing covers the bottom plate with insulator housing centrally seated thereon.

Upstream of the nozzle plate of the electrostatic precipitator according to claim 6, a prefilter over the clear cross-section of the housing inclined to the axis of the separator with its deepest portion next to a drain pipe in the separator housing, preferably to direct the outflow of liquid there. On the same side of the prefilter opposite the discharge pipe sits gas upstream in the wall of the separator front wall or shell wall side, a flange for the raw gas inlet to which the supply channel for the aerosol, the raw gas docks. In the insulator housing and the bottom plate covering the wall of the separator sitting front or shell wall side another flange for the clean gas outlet.

A modified, from the claims 1 to 3 or the claim 4 further developable embodiment is described in claim 7. The bottom plate is not continuous between the insulator housing and the wall of the separator housing. The bottom plate and the central insulator housing cover the separator.

According to claim 8 sits upstream gas upstream of the free end of the mesh or mesh electrode and the nozzle plate, the prefilter on the clear cross-section of the housing inclined to the axis of the rod.

Forehead or preferably shell wall side because of the drain cock in the local front side separator wall is in the wall of the separator housing the flange for the raw gas inlet. The flange for The clean gas outlet is now in the separator wall in the area between the bottom plate and the nozzle plate.

In claim 9, a further modified embodiment of the electrostatic precipitator is described according to claim 3. Now, the insulator housing is also located on an over the clear cross section of the separator housing reaching bottom plate, only now is the high voltage insulator with its one forehead positioned centrally on the bottom plate. On the protruding into the insulator housing end of the high voltage insulator, a high voltage grid is attached to which the high voltage bars are distributed evenly around the axis of the separator and at the same radial distance thereto and each project coaxially into the associated grid or mesh electrode. According to claim 10, the bottom plate between the insulator housing and the wall of the separator housing is continuous. Again, according to claim 11 upstream of the grid or mesh electrodes upstream of the grid plate and in front of the nozzle plate a prefilter over the clear cross-section of the housing inclined to the axis of the separator.

In order to stabilize the position, in particular in the case of gas flow, a plate, the fixing plate, is attached centrally to the bottom plate and outside of the insulator housing according to claim 12, through which the grid or mesh electrodes pass in a form-fitting manner.

Another extension of the separator according to claim 3 describes claim 13. Accordingly, the insulator housing sits concentrically on a reaching over the clear cross-section of the separator housing bottom plate. In the insulator housing, the high-voltage insulator sits centrally on the frontal ground. The high voltage rod is stuck with a forehead areas in the high voltage insulator. The grid or mesh electrode sets with a frontal area in a central passage of the bottom plate and abuts with its other forehead on the centrally mounted, non-gas permeable plate and is completely covered. The nozzle plate is located between the bottom plate and the end plate. The collector sits between the nozzle plate and the end plate and completely surrounds the sleeve.

According to claim 14, the raw gas is in the bottom plate or in the wall region of the separator between the carrier and nozzle plate. The clean gas outlet is located in the wall area of the separator, which covers the collector.

Yet another extension of the electrostatic precipitator according to claim 3 is described in claim 15. The insulator housing sits concentrically on the over the clear cross-section of the separator housing reaching bottom plate. In the insulator housing, the high-voltage insulator is mounted centrally on the frontal floor. On the protruding into the insulator housing end of the high-voltage insulator, a high-voltage grid is attached to which the rods are distributed evenly around the axis of the separator at the same radial distance from this axis and each project coaxially into the associated grid or mesh electrode. The mesh or mesh electrodes sitting in the bottom plate push with their other forehead on the covering face plate. The grid or mesh electrodes form-fit pass through the nozzle plate between the bottom plate and the end plate. The arrangement of the grid or mesh electrodes between the nozzle plate and the face plate is completely surrounded by the porous collector.

According to claim 16, the raw gas inlet in the bottom plate or in the jacket wall of the separator between the bottom and nozzle plate. The clean gas outlet is in the wall area of the separator housing, in which the porous collector is exposed.

• Aerosole mit Partikelkonzentrationen > 1g/Nm³ können technisch effizient, auch in wirtschaftlicher Hinsicht effizient prozessiert werden*;
• er hat eine raumsparende, kompakte Bauweise;
• er zeichnet sich durch eine lange Betriebsdauer aus;
• geringe Wartungskosten wegen geringer Hochspannungsisolatorverschmutzung;
• verbesserte Partikelladung aufgrund der geerdeten Gitter- oder Maschendrahtelektrode;
• erhöhte Partikelablagerung aufgrund der Raumladungseffekte zwischen Gitter- oder Maschendrahtelektrode und porösem Kollektor;
• Erhöhung der Betriebsdauer des Kollektors zwischen zwei Reinigungspausen;
• robuste Hochspannungselektroden;
• Modulbauweise, ein- oder mehrdüsig;
• Verwendung einer Gitter- oder Maschendrahtelektrode als Vorfilter.

(*Anmerkung: mit g/Nm³ ist Gramm pro Normkubikmeter gemeint, und zwar bedeutet N als Norm hier: bei 0°C und 1 at.)The advantages of the electrostatic precipitator are:

• Aerosols with particle concentrations> 1g / Nm ³ can be processed efficiently and economically even in economic terms *;
• he has a space-saving, compact design;
• it is characterized by a long service life;
• low maintenance costs due to low high voltage insulator contamination;
• improved particle charge due to the grounded grid or wire mesh electrode;
• increased particle deposition due to the space charge effects between grid wire or wire mesh electrode and porous collector;
• Increasing the operating time of the collector between two cleaning pauses;
• robust high-voltage electrodes;
• Modular construction, single or multi-nozzle;
• Using a grid or wire mesh electrode as a pre-filter.

(* Note: g / Nm ^{3 means} grams per standard cubic meter, and N means here as standard: at 0 ° C and 1 at.)

• Figur 1a Längsschnitt durch einen ersten elektrostatischen Abscheider;
• Figur 1b mehrere Hochspannungselektroden am Hochspannungsstab;
• Figur 2a Längsschnitt durch einen zweiten elektrostatischen Abscheider;
• Figur 2b Anbau der Fixierplatte;
• Figur 2c Abstand der zur Bodenplatte nächsten Hochspannungselektrode;
• Figur 3 Längsschnitt durch einen dritten elektrostatischen Abscheider;
• Figur 4 Längsschnitt durch einen vierten elektrostatischen Abscheider;
• Figur 5a Längsschnitt durch einen fünften elektrostatischen Abscheider;
• Figur 5b Vorfilter zu den Abscheidern gemäß Figuren 4 und 5;
• Figur 5c Kollektormodifikation zu den Figuren 4 und 5a;
• Figur 5d Düsenmodifikation zu den Figuren 4 und 5a;
• Figur 5e Flüssigkeitsablass von der Düsenplatte;
• Figuren 6a bis d Ausführungsformen der Gitter- oder Maschendrahtelektrode;
• Figuren 7a bis d Einbau der Gitter- oder Maschendrahtelektrode in die Düsenplatte;
• Figuren 8a bis d Einbau der Gitter- oder Maschendrahtelektrode in die Bodenplatte;
• Figuren 9a bis d Abschluss der Gitter- oder Maschendrahtelektrode an der Düsenplatte.

For further, detailed description of the invention, the following figures are used. They show in detail:

• FIG. 1a Longitudinal section through a first electrostatic precipitator;
• FIG. 1b several high voltage electrodes on the high voltage rod;
• FIG. 2a Longitudinal section through a second electrostatic precipitator;
• FIG. 2b Attachment of the fixing plate;
• Figure 2c Distance of the next high voltage electrode to the bottom plate;
• FIG. 3 Longitudinal section through a third electrostatic precipitator;
• FIG. 4 Longitudinal section through a fourth electrostatic precipitator;
• FIG. 5a Longitudinal section through a fifth electrostatic precipitator;
• FIG. 5b Prefilter to the separators according to FIGS. 4 and 5 ;
• FIG. 5c Collector modification to the FIGS. 4 and 5a ;
• FIG. 5d Nozzle modification to the FIGS. 4 and 5a ;
• FIG. 5e Liquid discharge from the nozzle plate;
• FIGS. 6a to d Embodiments of the mesh or wire mesh electrode;
• FIGS. 7a to d Installation of the grid or wire mesh electrode in the nozzle plate;
• FIGS. 8a to d Installation of the grid or wire mesh electrode in the bottom plate;
• FIGS. 9a to d Completing the grid or wire mesh electrode on the nozzle plate.

The Indian FIG. 1 proposed electrostatic precipitator has the raw gas inlet 18 below in the jacket wall of the separator housing 1. In the Abscheidergehäues the grounded nozzle plate 2 is installed, in which a nozzle 3 is centrally located here. A grounded grid electrode 8 is seated positively in the nozzle and is slightly upstream of the nozzle plate 2 upstream of the gas. At the free end of the high voltage rod 5, a disk-shaped high voltage electrode 4 is attached with radially directed tips. The high voltage electrode 4 may be configured differently, such as from DE 10 2005 023 521 is apparent. It is a needle-shaped electrode, has disc shape or is star-shaped. The high voltage electrode 4 is positioned within the grid electrode 8 such that the peaks / pips around it form the smallest distance H to the grid electrode 8.

To collect the solid and liquid particles of the aerosol, the porous collector 11, the porous filter 11, is used. The grid electrode 8 and the collector are installed here between the bottom plate 9 and the nozzle plate 2 in the separator housing 1. The high voltage rod 5 is clamped with an end face in the high voltage insulator 6, which is centrally attached to the bottom of the insulator housing 7 and exposed to the interior. The high-voltage insulator 6 is exposed in the interior of the insulator housing 7 and is therefore not in the raw gas stream. Through the high-voltage bushing 13 through the high-voltage rod 5 is located at the high voltage terminal of a not shown here high voltage power supply unit.

In addition, the high voltage electrode 12 is fixed to the high voltage rod 5 just before the opening in the insulator housing 7. It has a similar or the same shape as the high voltage electrode 4 at the free end of the high voltage rod 5. The arrangement of high voltage electrodes 4, 12 and high voltage rod 5 is coaxial with the grid electrode 8.

The bottom plate 9 has passages 10, through which the gas flow flows unhindered, at best insignificantly prevented. The porous collector 11 surrounds the grid electrode 8 completely and concentrically at a distance. The entire gas flow must forcibly pass through the porous collector through this structure.

The electrostatic precipitator has the flange-like raw gas inlet 18, through which the gas flow 16 introduced via a channel (not shown) enters. Downstream of the gas, the purified gas stream, after penetration of the porous collector 11, exits via the clean gas outlet opening 19 or is led further in a flanged channel (not shown). The arrows 16 in the figures indicate the flow path through the separator.

The electrostatic precipitator further has a pipe 15 through the wall 1 of the separator and the wall of the insulator housing 7, through which clean air or clean gas can be flowed into the insulator housing 7 to protect the high voltage insulator 6 from contamination by deposits. The connected clean air or clean gas reservoir is not shown. Optionally, the clean air or the clean gas can also be introduced heated.

The electrostatic precipitator has a pre-filter 14, which is installed in the separator housing 1 upstream of the nozzle plate 2 here in an oblique position. With him larger particles in the raw gas stream already be intercepted, namely particles of at least the size, which certainly can not pass through the perforations / mesh of the grid or wire mesh electrode 8 due to their diameter.

Further, the separator has away from the nozzle plate 2, a pipe 17 through the Abscheiderwand 1 to the outside, through which accumulated on the nozzle plate 2, discharged from the porous collector 11, contaminated liquid can be discharged. Next, the separator has a tube 20 which is installed at the bottom of the separator housing 1 to drain contaminated, dripping from the pre-filter 14, collected liquid also can.

The insulator housing 7 may be installed inside the separator on the clean gas side, as in FIG FIG. 1 shown. Or it can be located outside the separator, then the bottom plate 9 would have no openings 10 for the clean gas passage, as in FIG. 2 will be shown.

In an electrostatic precipitator 5, a plurality of high voltage electrodes 4 may be mounted on the high voltage rod 5. The geometry and size of the high voltage electrodes 4, their position, the width H of the electrode gap will be determined by the conditions under which the trap has to operate.

In order to guarantee mechanical stability and defined position, the fixing plate 21 is installed between the bottom plate 9 and the nozzle plate 2 (see FIG. 2b ). The distance between the bottom plate 9 and the fixing plate 21 is 2d (see FIG Figure 2c where d is the distance between the additional high voltage electrode 12 and the bottom plate 9, where d = 0.5 ... 1.5H and H is the gap width between the gap forming electrodes. The fixing plate 9 has an opening or opening through which the grid electrode passes positively. The fixing plate 21 is attached to the bottom plate via fixing elements or spacer elements 22. There is a gap between the fixing plate 21 and the porous collector 11, the collector filter 11.

The grid or wire mesh electrode 8 may be provided with open ( FIG. 6a ) or shielded forehead 110, 111. By open here is meant that the forehead has sharp or pointed spots, ie freestanding cut wire ends. In this way, corona discharges opposite thereto can occur whose polarity is opposite to that of the intended corona discharge between the electrodes 11 and 4 or 12. With shielded forehead 110, 111 it is meant that the forehead is smooth, ie peaks or sharp edges are avoided so that no counter corona discharge can occur. For this, the front edges are after Figure 6b, 6d covered with a dielectric or metallic ring 110, 111.

The grid or wire mesh electrode 8 may be incorporated in the nozzle 3 such that the entrance through the open, exposed Front of the grid or wire mesh electrode 8 gas upstream of the nozzle plate 2 sits ( Figure 7a ) or the shielded end edge 110 upstream ( FIG. 7b ) or the open end edge in the nozzle 3 (FIG. FIG. 7c ) or the open end edge on a fixing ring 112 downstream of the nozzle 3 ends ( FIG. 7d ). The flow direction of the gas stream to be cleaned is in FIGS. 7a to d indicated each time by the arrow 16.

In the compact electrostatic precipitator, the grid or wire mesh electrode 8 is installed in the passages of the carrier pacts 9 in the region of the insulator housing 7 such that the local free end edge of the grid or wire mesh electrode 8 is at the height of the bottom plate 9 (FIG. FIG. 8a, b ) or protrudes into the insulator housing 7 ( FIGS. 8c to f ). To FIG. 8a ends the free end of the grid or wire mesh electrode 8 in the passage in the bottom plate, according to Figure 8b sits a ring 101 on the bottom plate 9 and surrounds the grid or wire mesh electrode 8. Nach FIG. 8c ends the free edge of the front of the grid or wire mesh electrode 8 in the insulator housing, after FIG. 8d this is completed with a ring. To FIG. 8e is the front edge of the grid or wire mesh electrode 8 completed with a projecting into the insulator housing dielectric ring 110, after FIG. 8f additionally with a ring placed on top.

The gas flow into the grid or wire mesh electrode 8 may be covered like a sieve, as in the FIGS. 9a to d is exemplified, namely by a flat flat grid gemaß FIG. 9a , a flat, to the entrance end of the grid or wire mesh electrode 8 inclined grid ( FIG. 9b ), to FIG. 9c a conical grid and after FIG. 9d a hemispherical grid. It can thus be ensured that particles of a certain particle size corresponding to the mesh size can no longer flow into the interior of the mesh or wire mesh electrode 8 and impair them.

A compact electrostatic precipitator with more than one grid or wire mesh electrode 8 is shown FIG. 3 , with two Grid or wire mesh electrodes 8. The separator also consists of the housing 1 and the nozzle plate 2 with two nozzles 3. The two grid or wire mesh electrodes 8 extend from the nozzle plate 2 to the bottom plate 9 and stuck in the respective nozzle 3 and Opening in the bottom plate 9 positively. The high voltage insulator 6 is also now off the gas stream but now mounted on the bottom plate 9 and exposed in the insulator housing. On the exposed forehead of the high-voltage insulator 6, a high-voltage grid 23 is centrally mounted, on which here the two high-voltage rods 5 respectively project coaxially into the grid or wire mesh electrode 8. The high voltage grid 23 is connected to the high voltage feedthrough 13. About the tube 15, the interior of the insulator housing 7 is tempered with clean gas, clean air and flushed with pressure. as in FIG. 1 shows FIG. 3 Also, the installation of the porous collector 11 around the two grid or wire mesh electrodes 8 and between the bottom and nozzle plate, so that only a gas flow path in the two grid or wire mesh electrodes 8, through them and the porous collector 11 therethrough, as the arrows 16 indicate. Gas upstream sits in front of the nozzle plate 2 and installed at an angle to her, also the pre-filter 14 to catch coarse particles. Collected on the nozzle plate 2, with particles offset from the porous collector effluent liquid can be discharged through the outlet 17. The two high-voltage rods 5 are also inside the grid or wire mesh electrodes 8 with high voltage electrodes 4, 12 coaxially equipped. To stabilize the position of the two grid or wire mesh electrodes 8, the fixing plate 21 is mounted on spacer elements 22 from below to the bottom plate 9. The two grid or wire mesh electrodes 8 are positively passed through them. The raw gas stream enters the front of the bottom of the separator, as the arrow 16 indicates.

The construction in FIG. 3 is exemplary. The installation variant for raw gas inlet, Hochspannungsisolatoreinbau according to FIG. 1 would be feasible without special effort. It is essential that the forced Gastromweg, as indicated by the arrows 16, is set up, even if it divides in through the section of the ionization stage in two.

As in FIG. 2 shows FIG. 4 by way of example a compact electrostatic precipitator in which the insulator housing 7 is on and not in ( FIG. 1 ) is seated in the separator housing 1. The separator has an ionization stage of only one grid or wire mesh electrode 8 into which coaxial with the high voltage electrode 4, 12 equipped high voltage rod 5 protrudes, which protrudes from the mounted on the bottom of the insulator housing high voltage insulator. The interior of the insulator housing 7 is also flushable via the pipe 15 through the housing wall 7 with clean gas, air. The high voltage rod 5 is electrically connected to the high voltage feedthrough 13. The grid or wire mesh electrode 8 is seated with its one end positively in the opening of the bottom plate in the interior of the insulator housing 7 and abuts with the other end on the gas-impermeable end plate 24, whereby the grid or wire mesh electrode 8 is positioned defined. Again, the porous collector surrounds the grid or wire mesh electrode 8 completely but not over their entire length, but only partially. In the intermediate longitudinal region of the grid or wire mesh electrode 8 sits the nozzle plate 2, through which it goes positively. The raw gas inlet 18 is located in the bottom plate 9, the clean gas outlet 19 in the almond wall of the separator housing 1. Thus, one and only one gas flow path is forced, as indicated by the arrows 16 is displayed. The ionization stage of the coaxial electrode arrangement is now divided into two regions, namely a gas inlet region 81 above the collector region and a gas outlet region 82 in the collector region. From the collector dripping, contaminated with liquid now accumulates at the bottom of the separator housing 1, but can also be drained via the built-in housing wall cock 17. The exemplary installation of a prefilter 25 is not shown in this figure, but can be taken from the figure 13a.

Another example of a construction of the compact electrostatic precipitator is shown in FIG FIG. 5 shown. This separator has, as in FIG. 3 already executed, more than two nozzles, namely two. The insulator housing 7 sits like in FIG. 4 outside of the separator housing 1. The high voltage insulator 6 is at the bottom of the insulator housing, as to FIG. 3 indicated, mounted. The high voltage grid 28 is attached to the free end of the high voltage insulator and exposed inside the insulator housing. The two high-voltage bars 5 are suspended from the high voltage grid 28 and protrude through the bottom plate 9 coaxially in the two grid or wire mesh electrodes 8. The high voltage grid 28 is electrically connected to the high voltage bushing 13. The interior of the insulator housing is through the pipe 15 through the wall of the insulator housing with clean gas, air under pressure and / or tempered durchspülbar. Both high-voltage bars 5 are in the area of the two grid or wire mesh electrodes 8 similarly equipped with high voltage electrodes 4, 12. The two grid or wire mesh electrodes 8 abut the end face on the gas-impermeable end plate 24 and are fixed there. With their other forehead, the two grid or wire mesh electrodes 8 sit positively in the respective opening of the bottom plate 9 to the interior of the insulator housing 7. The nozzle plate 2 is now located in the longitudinal region of the two grid or wire mesh electrodes 8, through which they form fit through the respective nozzle. 3 pass. As a result, both are additionally fixed. Completely surrounded are both grid or wire mesh electrodes 8 in the region between the face plate 24 and the nozzle plate 2 of the porous collector 11, which is clamped between them. The raw gas inlet 18 is located in the bottom plate 9 outside, the clean gas outlet 19 in the jacket wall at the bottom of the separator housing 1. Here as in FIG. 4 Thereby, with respect to the gas flow, there are two regions for the two grid or wire mesh electrodes 8 of the ionization stage, namely the gas flow inlet region 81 into them and the gas flow outlet region 82 out of them. Again, the gas stream is divided by the ionizer into two branches. Further, the gas flow is forced through the separator and leads from the raw gas inlet 18 completely and solely through the ionizer and the collector to the clean gas outlet 19, as indicated by the arrows 16. The exemplary, possible installation of a prefilter 25 for the separation of large particles is like to FIG. 4 indicated in Figure 13a.

In the FIGS. 4 and 5 is indicated in each case that the porous collector 11 is clamped between the nozzle plate 2 and the end plate 24. This construction can be modified without violating the forced gas flow path in such a way that the grid or wire mesh electrode 8 ends flush with the face plate 24, but the porous collector 11 is clamped between the nozzle plate 2 and a collector plate 25 Gas outlet region 82 projects freely into the collector region, as shown in Figure 13 b for a grid or wire mesh electrode 8 in the cutout.

For the structure of the electrostatic precipitator according to the FIGS. 4 and 5 For example, the nozzle plate 2 at its nozzle 3 / its nozzles 3 may be surrounded upstream by a ring which allows the collection and collection of contaminated liquid from the gas stream without running down and contaminating the grid or wire mesh electrode 8 Perforations / meshes clogged. Via a pipe 27 through the nozzle plate 2, upstream or downstream of the porous gas collector 11, this contaminated liquid can run off in a targeted manner in the intended area of the separator. In FIG. 13c, this is sketched in the section upstream of the gas stream and in FIG. 13d even more in detail as a U-shaped tube 27. Advantageously, the entrance of this tube 27 is located downstream of a possibly installed prefilter 25.

The compact electrostatic precipitator with the forced gas flow path in it operates as follows:
The raw gas is introduced via a flanging at the separator channel and flows through the pre-filter to separate coarse particles, collect and discharge from the separator. The permeated through the prefilter gas stream with its now fine particles that can pass freely through the mesh of the grid or wire mesh electrode 8, enters the nozzle and passes through the electrode gap between the high voltage rod with its coaxial high voltage electrodes and coaxially surrounding grid or Wire mesh electrode 8. When a high voltage is applied to the high voltage rod, a corona discharge occurs at the sharp edges / tips of the high voltage electrodes. The entrained particles in the gas stream are charged there electrically and move to the grid or wire mesh electrode. The particle movement occurs under the influence of the gas-dynamic forces and the electric field in the electrode gap. Part of the particles are deposited in the grid or wire mesh electrode. The liquid taken there is electrically neutralized due to the reference / ground potential of the grid or wire mesh electrode, runs down it, drips into the separator and is discharged as needed. The other part passes through the mesh of the mesh or wire mesh electrode and forms a space charge zone between the mesh or mesh electrode and the porous collector. Under the influence of the space charge and the electrostatic forces between the charged particles and the grounded surface of the grid or wire mesh electrode, nozzle plate, bottom plate and porous collector, the charged particles accumulate on the grounded surfaces and are electrically neutralized. The mixed with the particles of liquid runs off, is collected in the separator in the intended area and discharged as needed.

A portion of the particles penetrate into the space downstream of the high voltage electrode and are made into electrically charged particles under the influence of the electric field between the high voltage rod and the grid or wire mesh electrode. This electric field drives the charged particles onto the grid or wire mesh electrode, where they are partially collected, partially penetrate and penetrate into the space between the grid or wire mesh electrode and the porous collector. A small portion of the charged particles reaches the upper zone of the grid or wire mesh electrode where the additional high voltage electrode sits next to the bottom plate. When high voltage is applied to the high voltage bar, there is a high electric field between this additional high voltage electrode and the grid or wire mesh electrode. The corona discharge at the additional high voltage electrode generates an electrical wind directed toward the grid or wire mesh electrode. Now, the geometry of the electrode gap is chosen so that the speed of the electric wind is equal to or higher than the velocity of the gas flow in the upper part of the grid or wire mesh electrode. Under these conditions, the electric wind protects the high-voltage insulator in the insulator housing, as well as the clean gas introduced into the interior of the insulator housing or the clean air. So it can not penetrate charged particles in the interior of the insulator housing.

Particles are also deposited on the fixing plate 21 since they are likewise connected to the reference potential or earthed, thus reducing the number of particles that can fly to the insulator housing. The fixing plate is mounted at a distance 2d from the passage in the bottom plate, thereby allowing the electric wind to pass at maximum speed in the electrode gap through the grid wire mesh electrode produced by the bottom plate and the fixing plate, thereby blowing off the charged particles become. This situation applies in the two cases that the Gastromweg through the entire grid or wire mesh electrode in one direction only, FIGS. 1 . 2 and 3 , or regionally opposite, FIGS. 4 and 5 , go.

The porous collector may be made of porous materials of different thickness and density. It can be made of different porous materials, dielectric, electrically semiconductive or conductive. Also, the porous material or the mesh or wire mesh electrode may be provided with additional catalytic additives. The materials must be process-oriented, at least largely process-oriented.

The dimensions and operation of an existing, compact electrostatic pilot plant include:
The clear width of the nozzle is 50 mm; the outside diameter of the mesh or wire mesh electrode is D = 50/48 mm; the electrode gap is 13 mm, using two 7-pin disk-shaped high-voltage electrodes; the high voltage is a negative polarity DC voltage of 12 to 20 kV; the corona current is 0.5 to 1 mA; The gas flow rate is 30 m ³ / h; was processed oil-mist aerosol having a particle mass concentration of 100 to 1 500 mg / Nm ³ , a particle size <2 microns and average particle size of 0.3 to 0.4 microns.

The precipitation efficiency for a single-module, compact electrostatic precipitator is between 92 and 95%, for a two-modulus between 97 and 99%.

Claims (16)

1. An electrostatic precipitator for removing the solid and liquid components from an aerosol, comprising:

   a precipitator housing (1) having an inlet, the raw gas inlet (18), for the aerosol to be cleaned, and an outlet, the clean gas outlet (19), for the cleaned aerosol, with at least one flow duct that brings along the aerosol being flanged to the raw gas inlet (18),

   a drain device (17) for the solid and liquid and separated components removed from the aerosol, an ionization stage which is supplied from the exterior via an electrical high-voltage feedthrough (13) and which consists of at least one metal bar (5), the high-voltage bar (5), extending into the flow path of the aerosol and to which electrical high voltage can be applied, a collector stage located downstream of the ionization stage in the flow path,

   wherein:

   the at least one high-voltage bar (5) extends into the gas flow path over a high-voltage insulator (6) sitting beside the gas flow path, and the high-voltage insulator (6) sits in a bowl-like insulator housing (7) through which aerosol does not flow and which is connected to an electrical reference potential,

   the high-voltage bar (5) with an electrode (4), the high-voltage electrode (4), sits at least at the free end and [sic] of a last electrode (12), the protection electrode (12), at distance d from the opening to the insulator housing (7), and the electrodes (4, 12) are provided disc-like with radially aligned spikes uniformly distributed about the periphery,

   the high-voltage bar (5) extends coaxially into a hollow-cylindrical sleeve (8) of perforated sheet metal or wire mesh, the grid or mesh electrode (8), which is attached at one end to a baseplate (9) for the insulator housing (7) and connected to a reference potential, and in such a way as to create for each electrode (4, 12) a concentric gap of the smallest width H from the enclosing grid or mesh electrode (8),

   the grid or mesh electrode (8) abuts against or sticks in a perforated plate (2), the nozzle plate (2), lying on the electrical reference potential,

   the grid or mesh electrode(s) (8) is(are) enclosed at most over the length of the sleeve, but completely around their periphery, by a porous collector (11), and the entire aerosol stream flows through the porous collector.
2. An electrostatic precipitator according to claim 1 wherein a high-voltage feedthrough (13) leads from the surroundings through the insulator housing (7).
3. An electrostatic precipitator according to claim 2 wherein a tube (15) for admitting clean gas or clean air at a given temperature and given pressure leads from the surroundings through the insulator housing (7).
4. An electrostatic precipitator according to claim 3 wherein:

   the insulator housing (7) sits on the baseplate (9) which extends concentrically across the unobstructed cross-section of the precipitator housing (1),

   the high-voltage insulator (6) in which the high-voltage bar (5) is clamped by its end sits centrally in the insulator housing (7),

   the grid or mesh electrode (8) sits with its one end region in a passage in the baseplate (9) and

   with its other end region in a nozzle (3) in the nozzle plate (2) seated across the unobstructed cross-section of the precipitator housing (1).
5. An electrostatic precipitator according to claim 4 wherein the baseplate (9) is perforated between the insulator housing (7) and the wall of the precipitator housing (1) and the precipitator housing (1) covers the perforated baseplate (9) as well as the insulator housing (7).
6. An electrostatic precipitator according to claim 5 wherein upstream of the free end of the grid or mesh electrode (8) and of the nozzle plate (2) in the direction of the gas flow sits a pre-filter (14) across the unobstructed cross-section of the precipitator housing (1) at a angle to the centreline of the high-voltage bar (5), with the raw gas inlet (18) being located upstream of the pre-filter (14) in the direction of the gas flow in the jacket-wall-side wall of the precipitator housing (1) and the clean gas outlet (19) being located in the precipitator housing (1) which covers the baseplate (9) as well as the insulator housing (7).
7. An electrostatic precipitator according to claim 4 wherein the baseplate (9) is not perforated between the insulator housing (7) and the wall of the precipitator housing (1) and of which the end forms part of the wall of the precipitator housing (1).
8. An electrostatic precipitator according to claim 7 wherein upstream of the free end of the grid or wire mesh electrode (8) and of the nozzle plate (2) in the direction of the gas flow sits a pre-filter (14) across the unobstructed cross-section of the housing at an angle to the centreline of the bar (5), with the raw gas inlet (18) being located in the wall of the precipitator housing (1) at the jacket-wall end upstream of the pre-filter (14) in the direction of the gas flow and the clean gas outlet being located downstream in the direction of the gas flow between the baseplate (9) and the nozzle plate (2).
9. An electrostatic precipitator according to claim 3 wherein:

   the insulator housing (7) for the high-voltage insulator (6) sits on the baseplate (9) which reaches concentrically across the unobstructed cross-section of the precipitator housing (1), in the insulator housing (7) the high-voltage insulator (6) sits centrally on the baseplate (9) and extends into the insulator housing (7),

   on that end of the high-voltage insulator (6) which extends into the insulator housing (7) is fixed a high-voltage grid (23) on which the high-voltage bars (5) are attached uniformly distributed about the axis of the precipitator at the same radial distance from that axis and each coaxially extending into the associated grid or mesh electrode (8).
10. An electrostatic precipitator according to claim 9 wherein the baseplate (9) is perforated between the insulator housing (7) and the inner wall of the precipitator housing (1).
11. An electrostatic precipitator according to claim 10 wherein:

    upstream of the free arrangement of the grid or mesh electrode(s) (8) and of nozzle plate (2) in the direction of the gas flow sits a pre-filter (14) across the unobstructed cross-section of the precipitator housing (1) at an angle to the centreline of the precipitator.
12. An electrostatic precipitator according to claim 11 wherein a plate (21), the fixing plate (21), through which the grid or wire mesh electrodes (8) are guided is attached by fixing elements (22) to the baseplate (9) centrally and away from the insulator.
13. An electrostatic precipitator according to claim 3 wherein
    the insulator housing (7) for the high-voltage insulator (6) sits concentrically on the baseplate (9) which extends across the unobstructed cross-section of the precipitator housing (1), the high-voltage insulator (6) in which the high-voltage bar (5) sticks axially sits centrally on the end base in the insulator housing (7),
    the grid or mesh electrode (8) starts with its one end in a central passage of the baseplate (9) and with its other end abuts a centrally mounted plate (24), the end plate (24), which covers the grid or mesh electrode (8) beyond the cross-section, with the nozzle plate (2) being located between the end plate (24) and the baseplate (9) and the grid or mesh electrode (8) being completely enclosed by the porous collector (11) between the nozzle plate (2) and the end plate (24).
14. An electrostatic precipitator according to claim 13 wherein the raw gas inlet (18) sits in the nozzle plate (9) and the clean gas outlet is located in the wall of the precipitator housing (1) in the region of the porous collector (11).
15. An electrostatic precipitator according to claim 3 wherein
    the insulator housing (7) for the high-voltage insulator (6) sits concentrically on the baseplate (9) which extends across the unobstructed cross-section of the precipitator housing (1), the high-voltage insulator (6) is mounted centrally in the insulator housing (7) on the frontal base,
    on that end of the high-voltage insulator (6) which extends into the insulator housing (7) is fixed a high-voltage grid (23) on which the high-voltage bars (5) are attached uniformly distributed about the axis of the precipitator at the same radial distance from that axis and each coaxially extending into the associated grid or mesh electrode (8),
    the grid or wire mesh electrodes (8) that stick in the baseplate (9) abut the covering end plate (24) by their free ends,
    the grid or wire mesh electrodes between the baseplate (9) and the end plate (24) pass through the nozzle plate (2), the assembly of grid or wire mesh electrodes (8) between the nozzle plate (2) and the covering end plate (24) is complete enclosed by the porous collector (11).
16. An electrostatic precipitator according to claim 15 wherein the raw gas inlet (18) sits in the nozzle plate (9) and the clean gas outlet (19) is located in the wall of the precipitator housing (1) in the region of the porous collector (11).

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