EP2452757A1 - Device and method for separating overspray and assembly with same - Google Patents

Abstract

The method involves collecting overspray of air flow and guiding the overspray of the air flow to an electrostatic separator (38). A large portion of solids from the overspray is separated at a separation surface. A fresh ice layer produced as a separating agent is applied on the separation surface. Cooling medium heated for removal of the ice layer with the separated solids on the separation surface is guided via a separation plate (40) for heating the plate such that ice on the separation surface is melted on a side of the ice layer turned towards the separation surface. Independent claims are also included for the following: (1) a device for separating overspray from cabin exhaust air of a coating system (2) a system for painting objects i.e. vehicle bodies.

Description

The invention relates to a method for separating overspray from the overspray-laden car exhaust air of coating systems, in particular paint systems, in which the overspray is taken up by an air stream and passed to an electrostatic working separation device where a majority of at least the solids from the overspray at least a separation surface is deposited, on which a release agent is applied.

1. a) wenigstens einer Abscheidefläche, an welcher die Kabinenabluft entlang führbar ist und welche mit einem Pol einer Hochspannungsquelle verbunden ist;
2. b) einer im Luftstrom angeordneten Elektrodeneinrichtung, welche der Abscheidefläche zugeordnet und mit dem anderen Pol der Hochspannungsquelle verbunden ist.

In addition, the invention relates to a device for separating overspray from the overspray-laden cabin exhaust air from paint shops

1. a) at least one separation surface, on which the cabin exhaust air is guided along and which is connected to a pole of a high voltage source;
2. b) a arranged in the air flow electrode means which is associated with the Abscheidefläche and connected to the other pole of the high voltage source.

1. a) einer Beschichtungskabine, in welcher die Gegenstände mit Beschichtungsmaterial beaufschlagbar sind und durch welche ein Luftstrom geleitet werden kann, der entstehende Overspraypartikel des Beschichtungsmaterials aufnimmt und abführt;
2. b) einer elektrostatisch arbeitenden Abscheidevorrichtung.

Furthermore, the invention is concerned with a system for coating, in particular for painting objects, in particular vehicle bodies, with

1. a) a coating booth in which the articles can be exposed to coating material and through which an air stream can be passed, which receives and removes resulting overspray particles of the coating material;
2. b) an electrostatic working separation device.

In the case of manual or automatic application of lacquers to objects, a partial flow of the lacquer, which generally contains both solids and / or binders and solvents, is not applied to the article. This partial flow is called "overspray" in the professional world. In addition, the terms overspray, overspray particles or overspray solids are always understood to mean a disperse system, such as an emulsion or suspension or a combination thereof. The overspray is detected by the air flow in the paint booth and fed to a separation, so that the air can be optionally returned to the coating booth after a suitable conditioning.

Especially in systems with greater paint consumption, for example in systems for painting vehicle bodies, preferably wet separation systems are used. In the case of wet separators known from the market, water flows together with the exhaust air from the cabin to an air flow accelerating nozzle. In this nozzle there is a turbulence of the flowing cabin exhaust air with the water. During this process, the overspray particles largely pass into the water, so that the air leaves the wet scrubber substantially cleaned and the overspray paint particles are de-adhesive in the water. From this they can then be recovered or disposed of.

In known wet scrubbers relatively much energy is required to circulate the required quite large amounts of water. The treatment of the rinse water is costly due to the high use of paint-binding and detackifying chemicals and the Lackschlammentsorgung. Furthermore, the air absorbs a lot of moisture due to the intensive contact with the rinse water, which in turn results in a high energy consumption for the air treatment in the recirculation mode.

In known from the market devices of the type mentioned in contrast is deposited dry way by ionized by the passing cabin exhaust air entrained paint Overspraypartikel by the electrode means and migrate due to the built-up between the Abscheidefläche and the electrode device electric field to Abscheidefläche, at which they separate. The adhering to the separation surface paint Overspraypartikel can then, for example, mechanically stripped and transported away from this.

The cleaning effect of such separators is very high. For continuous operation, however, it must always be ensured that a sufficiently strong electric field can form between the deposition surface and the electrode device, which is possible only up to a certain layer thickness of paint overspray on the deposition surface, since such a layer has an insulating effect , However, the required continuous removal of the paint overspray from the separation surface is associated with structurally quite complex measures and can be prone to failure. It may also happen that overspray on the Abscheidefläche so reacts, hardens or dries, so that it can not be removed by simply stripping the Abscheidefläche.

Object of the present invention is therefore to provide a method, a separation device and a system of the type mentioned, which take into account these problems.

This object is achieved in the method of the type mentioned in that
As a release agent on the at least one Abscheidefläche an ice sheet is generated.

According to the invention, therefore, ice is used as the separating layer between the separation surface and the overspray so that it can not come into direct contact with the separation surface. The use of ice as such a separation layer is based on the recognition that an ice layer on the separation surface does not disturb the electric field and can be removed from the separation surface with relatively simple means together with overspray particles, if necessary.

It is advantageous if, after a working period, an ice layer with deposited solids present on the at least one separation surface is removed and a fresh layer of ice is produced on the at least one separation surface. In this way, it is possible to dispense with continuous stripping of the overspray. The working period may be about 2 hours, about 4 hours, about 6 hours, about 8 hours, about 10 hours, or about 12 hours. With lower loading of the release agent with overspray and a longer work period of up to several days is possible, as long as the insulation effect of the overspray does not affect the formation of the field lines so that proper operation of the separator is no longer possible.

It is advantageous if a surface area of a deposition plate is used as the deposition surface.

Advantageously, the surface of the deposition plate can be effectively cooled using a deposition plate comprising one or more Peltier elements. Peltier elements are known from the prior art. The cooling side of the Peltier element (s) may themselves form the surface of the deposition plate. Alternatively, the one or more Peltier elements may be connected to the deposition plate such that their surface cools.

Alternatively or in addition to the use of Peltier elements, it is also advantageous if a cooling medium is passed through the separation plate.

In this case, it has proved to be particularly advantageous if, for producing the ice layer on the at least one separation surface cooled cooling medium is passed through the Abscheideplatte to cool the Abscheideplatte such that water from the deposition of the surrounding the atmosphere as an ice layer on the at least one Precipitation surface precipitates.

To remove an ice layer with separated solids from the at least one separation surface then advantageously heated cooling medium can be passed through the separation plate to heat the separation plate such that ice melts on the at least one separation surface at least on the separation surface facing side of the ice layer. Thus, a largely contiguous and overspray-loaded layer of ice on a film of water from the separation surface slip down. If one or more Peltier elements are present, they can either be deactivated or reversed by reversing the current direction, so that their previously cooling side is heated.

A compression cooling circuit can be conveniently established be when the cooling medium is passed in generating the ice layer in a circuit with a compressor device and an evaporator device.

In such a compressor unit, cooling medium is compressed, whereby it heats up. At least part of the heat energy stored in the cooling medium can be used to advantage when it is passed between the compressor device and the evaporator device through the heat exchanger coil of a heat exchanger.

For example, when the solids exhausted cabin air is passed through this heat exchanger, the heat energy of the cooling medium can be used to dry that cabin air. The dried cabin air can then, if appropriate after further conditioning, be recirculated to a corresponding paint booth.

In a development, the separation surface can be freed of ice in a favorable manner, by passing the cooling medium for heating the at least one deposition surface coming from the compressor device past the evaporator device to the separation plate. This is possible for example by a simple bypass line.

It is also advantageous if the cooling medium is also guided past the heat exchanger.

• c) eine Eisschicht als Trennmittel auf der wenigstens einen Abscheidefläche erzeugt ist.

In a device of the type mentioned above, the above object is achieved in that

• c) an ice layer is produced as a release agent on the at least one separation surface.

With regard to the ice sheet and explained below Further developments, the above said to the procedure applies mutatis mutandis accordingly.

The device advantageously comprises a device by means of which a fresh layer of ice can be produced on the at least one separation surface and / or an ice layer with precipitated solids present on the at least one deposition surface can be removed.

It is favorable if the at least one separation surface is a surface region of a deposition plate. This can advantageously comprise one or more Peltier elements.

Alternatively or additionally, a cooling line, through which a cooling medium can be passed, preferably runs in the interior of the separation plate.

As explained above, a compression cooling circuit can be conveniently established when the cooling medium is at least temporarily conductible in a circuit with a compressor device and an evaporator device, which is connected to the cooling line.

It is also advantageous if a heat exchanger with a heat exchanger coil is arranged between the compressor device and the evaporator device, through which coolant coming from the compressor device can be conducted.

Preferably, then a flow path of the freed of solids cabin air through the heat exchanger.

Moreover, it is advantageous if a switchable via valves bypass line is present, via which the cooling medium at least temporarily coming from the compressor device to the evaporator device over to the cooling line the deposition plate is leitbar.

Here, it may be favorable if the bypass line runs in such a way that the cooling medium can also be conducted past the heat exchanger to the cooling line of the separation plate.

• c) die elektrostatische Abscheidevorrichtung nach einem der Ansprüche 13 bis 22 ausgebildet ist.

In the above-mentioned system, the above-mentioned object is achieved in that

• c) the electrostatic precipitation device according to one of claims 13 to 22 is formed.

The plant according to the invention thus comprises a separation device with one or more of the features mentioned above for the device. The advantages that can be achieved correspond to the advantages explained above for the method and the device.

Figur 1

eine Lackierkabine einer Oberflächenbehandlungsanlage mit einer Overspray-Abscheidevorrichtung in einer Vorderansicht;

Figur 2

eine perspektivische Ansicht von vier Abscheideeinheiten sowie von vier Elektrodeneinrichtungen der Abscheidevorrichtung von Figur 1;

Figur 3

eine schematische Veranschaulichung einer mäanderförmigen Kühlleitung in einer Abscheideplatte einer Abscheideeinheit;

Figur 4

eine schematische Darstellung der Lackierkabine, die mit drei Abscheideplatten gezeigt ist, eines Umwälzsystems für ein Kühlmedium sowie eines Luftkreislaufs der Kabinenluft;

Figur 5

eine der Figur 4 entsprechende Darstellung, bei der ein erster Kreislauf des Umwälzsystems zum Kühlen der Abscheidplatten hervorgehoben gezeigt ist;

Figur 6

eine weitere der Figur 4 entsprechende Darstellung, bei der jedoch ein zweiter Kreislauf des Umwälzsystems zum Erwärmen der Abscheidplatten hervorgehoben gezeigt ist;

Figur 7

nochmals eine der Figur 4 entsprechende Darstellung, bei der jedoch der Luftkreislauf der Kabinenluft hervorgehoben gezeigt ist;

Figur 8

eine der Figur 2 entsprechende Ansicht von vier Abscheideeinheiten, wobei die Abscheideeinheiten Abscheideplatten aufweisen, die Peltierelemente umfassen;

Figur 9

schematisch einen Schnitt durch Abscheideeinheiten mit Peltierelementen, wobei der jeweilige Schnitt durch eine Abscheideplatte einem Schnitt entlang der Schnittlinie IX-IX in Figur 3 entspricht und zwei Abscheideplatten an den Enden der Abscheidevorrichtung und dazwischen angeordnete Abscheideplatten gezeigt sind.

Embodiments of the invention are explained below with reference to the drawings. In these show:

FIG. 1

a spray booth of a surface treatment plant with an overspray separator in a front view;

FIG. 2

a perspective view of four deposition units and four electrode devices of the separator of FIG. 1 ;

FIG. 3

a schematic illustration of a meandering cooling line in a separation plate of a separation unit;

FIG. 4

a schematic representation of the paint booth, which is shown with three separation plates, one Circulation system for a cooling medium and an air circulation of the cabin air;

FIG. 5

one of the FIG. 4 corresponding representation in which a first circuit of the circulation system for cooling the Abscheidplatten is shown highlighted;

FIG. 6

another one FIG. 4 corresponding representation in which, however, a second circuit of the circulation system for heating the Abscheidplatten is shown highlighted;

FIG. 7

again one of the FIG. 4 corresponding representation in which, however, the air circulation of the cabin air is shown highlighted;

FIG. 8

one of the FIG. 2 corresponding view of four separation units, wherein the separation units have separating plates which comprise Peltier elements;

FIG. 9

schematically a section through Abscheideeinheiten with Peltier elements, wherein the respective section through a Abscheideplatte a section along the section line IX-IX in FIG. 3 and two separation plates are shown at the ends of the separator and interposed separator plates.

First, on the FIGS. 1 and 2 Referenced. There is a total of 2 a spray booth a surface treatment system referred to, in which vehicle bodies 4 are painted after they were in the paint booth 2 upstream, not specifically shown pretreatment stations, for example, cleaned and degreased. The paint booth 2 rests on a steel structure 6, as it is known in and of itself.

The spray booth 2 comprises an overhead painting tunnel 8, which is bounded by vertical side walls 10 and a horizontal cabin ceiling 12, but open at the ends and downwards in such a way that over-laden cabin exhaust air can flow down. The cabin ceiling 12 is formed in the usual way as the lower boundary of an air supply space (not shown) with filter cover.

Above a lower opening 14 of the painting tunnel 8, a steel structure 16 is arranged, which carries a known per se conveyor system 18, which will not be discussed here. With this vehicle body 4 to be painted can be transported from the input side of the painting tunnel 8 to its output side. Inside the painting tunnel 8 are not specifically shown application devices, by means of which the vehicle bodies 4 can be coated in a manner known per se with paint. The lower opening 14 of the painting tunnel 8 is covered by a walk-in grate not specifically shown.

Below the paint booth 2 there is a plant area 20, in which the overspray particles carried by the cabin air are separated from the cabin air. The plant area 20 is bounded by a housing not specifically provided with a reference numeral, which in FIG. 1 only indicated as a dashed line.

The plant area 20 comprises a flow area 22, which is open towards the top of the paint booth 2 and is defined by two air baffles 24 and 26, between the upper ends of which the cabin opening 14 extends. The baffles 24, 26 diverge down to a separating space 28 arranged below the flow area 22, through which the cabin air flows in a direction from top to bottom.

The lower cabin opening 14 is also flanked by Abscheideblechen 30, which moderately slope downwards in the outward direction and are externally formed into a collecting channel 32. The Abscheideblechen 30, a Abscheideflüssigkeit be supplied from Verteilerrinnen 34, which are arranged adjacent to the air guide plates 24 and 26, so that the Abscheideflüssigkeit flows in a substantially continuous layer on the Abscheideblechen 30 to the collecting grooves 32. The separating liquid takes up a part of the over-air carried by the cabin air, while the cabin air flows from the painting booth 2 down through the booth opening 14 into the separating room 28.

From the collecting channels 32, the separating liquid can be supplied to a cleaning and conditioning process, in which it is released in a manner known per se from the paint overspray. Then, the separation liquid can be supplied to the distribution channels 34 again in a cycle.

In the separation chamber 28, a separation unit 36 of an electrostatically operating separation device 38 is arranged. The separation unit 36 comprises a multiplicity of rectangular separation plates 40 arranged one behind the other in the longitudinal direction of the separation space 28, of which four are in FIG FIG. 2 are shown. The respective opposite outer surfaces of the deposition plates 40 form Abscheideflächen 42, of which in FIG. 2 only each to be recognized Abscheidefläche 42 each Abscheideplatte 40 is provided with a reference numeral. The separation plates 40 are in one Support frame stored, which is not shown separately.

In the separation unit 36, the separation plates 40 are arranged parallel to each other in such a way that between them in each case a distance remains sufficient that two adjacent deposition plates 40 can each receive an electrode device 44 between them. Of these, only the one in FIG. 2 rightmost electrode device provided with reference numerals.

Each electrode device 44 is connected to a pole of a high-voltage source 46 assigned to it, of which in FIG. 1 only a single is indicated schematically. The deposition plates 40 are connected to ground potential via the other pole of the high voltage source. The connection of the electrode device 44 and the deposition plate 40 with the high voltage source 46 is in FIG. 1 indicated by dashed lines.

Alternatively, all electrode means 44 may be powered by a single common high voltage source.

Each electrode device 44 comprises two straight, parallel to each other extending electrode strips 48. These hold in a field portion 50 of the electrode device 44, a grid electrode 52, whose extending between the electrode strips 48 edges are perpendicular to this. In a corona section 54 of the electrode device 44, the electrode strips 48 hold a plurality of corona wires 56 acting as a spray electrode. The corona wires 56 extend perpendicular to them in a plane predetermined by the electrode strips 48 and are arranged at equal distances from one another.

The number of corona wires 56 of the electrode device 44 and their distance from each other may vary depending on the deposition behavior of the overspray particles. In the present embodiment, four corona wires 56 are provided per electrode device 44.

As in the FIGS. 1 and 2 can be seen, the electrode means 44 have an overall extension which corresponds approximately to the extension of the separation plates 40 of the separation unit 36.

Below the separation plates 40, a circulating endless conveyor belt 58 is arranged, which extends in the longitudinal direction of the painting booth 2 and transversely to the separation plates 40 and to a in the FIGS. 4 to 7 with 60 designated collection area leads. In the FIGS. 4 to 7 is shown as a modification of one of several conveyor belts 58 which extend transversely to the longitudinal direction of the car 2 and parallel to the separation plates 40. Instead of the conveyor belt or conveyors 58, for example, a channel inclined downwards towards the collecting area 60 or a horizontally extending channel may also be present, wherein in the latter then, for example, a scratch will cause the material to be conveyed to the collecting area 60.

On both separation surfaces 42 of each deposition plate 40 is an ice layer 62 (see FIG. 2 ), which acts as a release agent and prevents deposited overspray directly attaches to the Abscheideflächen 42 of the deposition plates 40. The ice sheets 62 are each between 0.2 mm and 2 mm thick. In practice, a thickness of the ice sheets 58 of 1 mm has been found to be useful.

The ice sheets 62 are formed on the separation surfaces 42 by cooling the deposition plates 40 to a temperature below 0 ° C. If subsequently spoken of For example, if an ice sheet 62 is generated, this implies that an already existing ice sheet 62 will be maintained.

For this purpose, the separation plates 40 are double-walled, wherein in the interior of each deposition plate 40 in each case a meander-shaped cooling line 64 extends between an inlet connection 66 and an outlet connection 68, which are provided in the present exemplary embodiment on a vertical narrow side of a respective deposition plate 40. These are in the FIGS. 1 to 3 to recognize. In FIG. 3 the meandering course of the cooling line 64 is illustrated schematically.

The inlet stubs 66 of the separating plates 40 are connected via supply lines 70 to a distributor block 72, via which each cooling line 64 of a certain separator plate 40 a cooling medium is supplied. The outlet ports 68 of the separation plates 40 are connected via discharge lines 74 with a collecting block 76, is discharged through the cooling medium after it has flowed through a certain separation plate 40. As a cooling medium so-called refrigerant come into consideration, as they are known in and of themselves; for example, the refrigerant commonly referred to as R134a is tetrafluoroethane. In principle, all non-flammable and non-paint-damaging refrigerants are suitable which do not cause any surface coating defects if they should come into contact with the vehicle body 4 in the event of a leak.

The separation device 38 comprises in addition to the separation unit 36, a circulation system 78 which is connected to the manifold block 72 and the collecting block 76 and in detail in the FIGS. 4 to 7 is shown. There, the paint booth 2 with the paint tunnel 8 and the separation area 22 are very much shown schematically. Only three consecutive separation plates 40 connected to the manifold block 72 and collector block 76 in the manner described above are illustrated by the separator 38.

The recirculation system 78 includes a first fluid line 80 leading from the collector block 76 to the inlet of a compressor 82. On the output side, the compressor 82 is connected via a second fluid line 84 to a first end of a heat exchanger coil 86 of a heat exchanger 88, which is connected at the opposite end via a third fluid line 90 to the inlet of an evaporator 92.

The output of the evaporator 92 leads via a fourth fluid line 94 to the manifold block 72nd

The second fluid line 84 is connected to the fourth fluid line 94 via a first bypass fluid line 96, wherein a respective valve 98 or 100 is present at the outlet points.

The first fluid line 80 is connected via a second bypass fluid line 102 to the third fluid line 90 which extends between the heat exchanger 88 and the evaporator 92. At each discharge point in each case a valve 104 or 106 is present.

In addition, the first fluid line 80 is connected via a third bypass fluid line 108 to the second fluid line 84, which extends between the compressor 82 and the heat exchanger 88, wherein in each case a valve 110 or 112 is present at each discharge point.

Furthermore, the third fluid line 90, which is between the Heat exchanger 88 and the evaporator 92 is connected via a fourth bypass fluid line 114 to the fourth fluid line 94. At each discharge point there is again a valve; these bear the reference numerals 116 and 118, respectively.

Through the valves 104 and 110, the first fluid line 80 is in a first portion 80a between the manifold block 76 and the valve 104, a second portion 80b between the valve 104 and the valve 110 and a third portion 80c between the valve 110 and the compressor 82nd divided.

Accordingly, the valves 98 and 112 divide the second fluid conduit 84 into a first portion 84a between the compressor 82 and the valve 98, a second portion 84b between the valve 98 and the valve 112, and a third portion 84c between the valve 112 and the heat exchanger coil 88 ,

The third fluid conduit 90 is similarly divided by the valves 106 and 116 into a first portion 90a between the evaporator 92 and the valve 106, a second portion 90b between the valve 106 and the valve 116, and a third portion 90c between the valve 116 and the heat exchanger coil 86.

Finally, the valves 100 and 118 still divide the fourth fluid line 94 into a first section 94a between the manifold block 72 and the valve 100, a second section 94b between the two valves 100 and 118, and a third section 94c between the valve 118 and the evaporator 92 ,

Viewed in the flow direction, the first fluid line 80 forms, together with the compressor 82, the second fluid line 84, the heat exchanger coil 86, the third fluid line 90, the evaporator 92, the fourth fluid line 94 and the manifold block 72, the cooling lines 64 in the Abscheidplatten 40 and the collection block 76, a first circuit 120 for cooling medium. This first circuit 120 is in FIG. 5 highlighted by the lines shown by solid lines.

The first circuit 120 is formed when the valves 98, 100, 104, 106, 110, 112, 116, and 118 are set to release the flow path through the first circuit 120.

By supplying cooling medium through the first circuit 120 to the separation plates 40, they can be cooled to temperatures below 0 ° C. Since the ice sheets 62 constantly lose heat, cooling must always be maintained as long as the ice sheets 62 are to remain formed on the separation plates 40.

A second circuit 122 for cooling medium is in FIG. 6 illustrated by the lines shown by solid lines. The second circuit 122 is viewed in the flow direction through the section 80a of the first fluid line 80, the second bypass fluid line 102, the section 90a of the third fluid line 90, the evaporator 92, the section 94c of the fourth fluid line 94, the fourth bypass fluid line 114 , the portion 90c of the third fluid conduit 90, the heat exchanger coil 86, the portion 84c of the second fluid conduit 84, the third bypass fluid conduit 108, the portion 80c of the first fluid conduit 80, the compressor 82, the portion 84a of the second fluid conduit 84, the bypass Fluid line 96 and the fluid line section 94a of the fourth fluid line 94 and the manifold block 72, the cooling lines 64 in the Abscheidplatten 40 and the collecting block 76 formed.

The second circuit 122 is formed when the valves 98, 100, 104, 106, 110, 112, 116, and 118 are set such that the flow path corresponding to the second circuit 122 is released.

By the cooling medium is supplied to the separation plates 40 through this second circuit 122, these can be heated again to temperatures above 0 ° C.

In the present embodiment, in each case three-way intersections are formed at all mouth points of the lines and each discharge point is associated with a corresponding valve. In a modification, all of the bypass fluid lines 96, 102, 108 and 114 leading to one of the first to fourth fluid lines 80, 84, 90 and 94 may also meet at a common point of discharge, where a corresponding four-way valve is then provided.

Overall, the circulation system 78, in conjunction with the cooling lines 64 of the separation plates 40, forms a device by means of which in each case a fresh ice layer 62 is produced on the separation surfaces 42 and / or an ice layer 62 with deposited solids can be removed on the separation surfaces 42.

Cabin air is supplied to the heat exchanger 88 from the separation chamber 28 via a flow channel 124, so that the cabin air flows around its heat exchanger coil 86. The heat exchanger 88 is located in a conditioning unit 1126 in which further facilities are provided to condition the cabin air. This is illustrated by way of example with reference to a sprinkler 128, by means of which the cabin air can be humidified.

For the formation of ice on the separation plates 40, a relative humidity of 60% to 70% of the conditioned cabin air is generally sufficient. This moisture can e.g. be effected by the sprinkler 128. The air can still be moistened by the same after cleaning the above-mentioned application facilities in the painting tunnel 8 by spraying water.

From the conditioning unit 126, the cabin air flows via a flow channel 130 on to the above-mentioned and not specifically shown air supply space, from where it flows in via the filter cover from above into the painting tunnel 8.

Thus, the flow channel 124, the conditioning unit 126 and the flow channel 130 form an air circuit 132 of the cabin air. This cycle is in FIG. 7 again clarified by the lines shown by solid lines.

Via a secondary passage 134, the cabin air flowing out of the separation chamber 28 can be supplied with fresh air in the flow passage 124. From the flow channel 130, a side channel 136 goes off, over which a portion of the air flowing through the flow channel 130 air can optionally be discharged through the roof.

• Die Ventile 98, 100, 104, 106, 110, 112, 116 und 118des Umwälzsystems 78 werden zunächst so eingestellt, dass das Kühlmedium in dem ersten Kreislauf 120 strömt, der in Figur 5 verdeutlicht ist. Dabei wird Kühlmedium in dem Kompressor 82 verdichtet, wobei es sich erwärmt.

The painting booth 2 explained above now works as follows:

• The valves 98, 100, 104, 106, 110, 112, 116 and 118 of the circulation system 78 are initially adjusted so that the cooling medium flows in the first circuit 120, which in FIG. 5 is clarified. In this case, cooling medium is compressed in the compressor 82, wherein it heats up.

Part of the heat is emitted in the heat exchanger 88 to the cabin air, which flows through the conditioning unit 126. Thereafter, the cooling medium in the evaporator 92 is brought into a gaseous state, whereby it cools. In the present embodiment, for example, the cooling medium has a temperature of about -6 ° C after it has left the evaporator 92 as a gas.

The thus cooled and now gaseous cooling medium now flows into the manifold block 72 and is distributed by this to the individual separation plates 40, where it flows through the respective cooling lines 64. The cooling medium extracts heat from the separation plates 40, as a result of which they cool to a temperature at which water condenses out of the atmosphere prevailing in the separation chamber 28 and surrounds the deposition plates 40 at the deposition surfaces 42 and freezes there to the ice layer 62. Thus, this water is reflected as ice layer 62 on the Abscheideflächen 42. In a modification not specifically shown, a sprinkler may also be present with which the separation plates 40 can be sprayed with water. After the cooling medium has passed through a separation plate 40, in the present embodiment it has e.g. a temperature of about -2 ° C.

If now the vehicle bodies 4 are painted in the painting tunnel 8, the cabin air located there is loaded with paint Overspraypartikeln. These can still be liquid and / or sticky, but already more or less firm. The cabin exhaust air laden with paint overspray flows through the lower opening 14 of the painting tunnel 8 into the first flow area 22 of the lower installation area 20. There, this air is conducted through the air guide plates 24, 26 to the separation space 28. A part of the overspray is already absorbed by the Abscheidflüssigkeit flowing on the Abscheidblechen 30 to the collecting grooves 32. The cabin air flows downward in the direction of the separation unit 36 the separator 36 and continues to flow there between adjacent separator plates 40 therethrough.

At the corona wires 56 of the electrode devices 44, corona discharges occur in a manner known per se, by means of which the overspray particles in the passing exhaust air of the cabin are effectively ionized.

The ionized overspray particles pass the deposition plates 40 at ground potential and the grating electrodes 52 extending therebetween in the field portion 50 of the electrode means 44. Due to the electric field formed between grid electrode 52 and deposition plates 40, the ionized overspray particles deposit on the ice sheet 62 on the deposition plates 40 and remain largely attached to the ice layer 62.

Optionally dripping down from the separation plates 40 overspray is collected by the conveyor belt 58 and conveyed to the collection area 60.

The majority of the ionized overspray particles are already deposited in the corona section 54 of the electrode device 44 on the separation plates 40. However, the electric field present between the corona wires 56 and the respective deposition plate 40 of the deposition unit 36 is inhomogeneous than the electric field in the region of the grid electrode 52, which is why a more judicious deposition of the ionized overspray particles takes place at the corresponding deposition plate 40. As a result, the overspray particles which have passed through the corona section 54 are also effectively deposited in the field section 50.

The cabin air released from the overspray during the passage through the separation unit 36 and thus cleaned enters the air Flow channel 124, passes through the conditioning unit 126, in which it is conditioned accordingly, and passes through the flow channel 130 back into the painting tunnel eighth

For proper operation of the separation unit 36, it must be ensured that a sufficiently strong electric field can always be formed between the deposition plates 40 and the electrode devices 44. However, this is only possible up to a certain layer thickness of deposited paint overspray on the deposition surface 42 or the ice layer 62, since such a layer has an insulating effect. The strength of the insulating effect of the constructed overspray layer can be determined by the power requirement of the separation unit 36, which generates the corresponding corona current, which decreases over time.

Due to the insulating effect of adhering to the release agent overspray, the corona current decreases with increasing thickness of the overspray layer. The corona current is usually determined empirically and is usually a few milliamperes per high voltage electrode.

In addition, solid particles and also binder components from the deposited overspray migrate from the surface of the ice sheets 62 into the ice. After a certain period of operation, there is a risk that solid particles migrate to the separation surfaces 42 and settle there, which severely impair the functioning of the separation unit 36 and would require extensive cleaning and maintenance.

If the insulating effect of the deposited overspray is therefore too great and / or proper operation of the separation unit 36 can no longer be guaranteed, the ice layers 62 will now be adhering to overspray removed from the separation plates 40 and the Abscheideflächen 42 of the separation plates 40 provided with a fresh layer of ice 62.

For this purpose, the valves 98, 100, 104, 106, 110, 112, 116 and 118 of the circulation system 78 are adjusted so that the cooling medium flows in the second circuit 122, the in FIG. 6 is highlighted. In this case, the heat exchanger 88 and the evaporator 92 are bypassed by the cooling medium via the first bypass fluid line 96, thereby passing through the separation plates 40 of cooling medium previously compressed in the compressor 82 and thereby heated and now heated via the manifold block 72 reaches the individual separation plates 40. In the present embodiment, it is assumed that the cooling medium leaves the compressor 82 at a temperature of about 70 ° C and flows into the separation plates 40.

As a result, the deposition plates 40 are heated to a temperature at which the ice layer 62 melts on the respective deposition surfaces 42. The ice sheets 62 with overspray adhered thereto then slide downward from the separation plates 40 due to gravity and fall onto the conveyor belt 58 together with water as water / ice / overspray mixture. This then transports the material mixture to the collection area 60 from where it is a processing is supplied. For this purpose, the material mixture, for example, can be further heated, whereby any ice still present is completely liquefied. The water / overspray mixture thus obtained can be separated thereafter, for example by means of suitable filters. The filtered overspray can optionally be fed to a further treatment or its disposal, as it is known per se.

After the coolant has flowed through the separation plates 40, it is slightly cooled compared to its inlet temperature. Starting from the above assumed starting temperature of 70 ° C and the cooling medium finally reaches the collecting block 76 at a temperature of about 50 ° C. From there, the cooling medium flows to the evaporator 92, where it is cooled even further, for example to about 30 ° C. The cooling medium leaving the evaporator 92 is still at a temperature sufficient to utilize the cooling medium for conditioning the cabin air and to pass through the heat exchanger coil 86 of the heat exchanger 88 for this purpose. From there, the cooling medium finally flows again cooled by about 10 ° C, so in the present example with a temperature of about 20 ° C, back to the compressor 82, where it is again compressed and thereby heated.

After all separation plates 40 of the separation unit 36 are free of ice with overspray adhering to them, the valves 98, 100, 104, 106, 110, 112, 116 and 118 of the circulation system 78 are adjusted again so that the cooling medium flows in the first circulation 120 who in FIG. 5 is clarified, and water condenses out of the prevailing in the separation chamber 28 atmosphere at the Abscheideflächen 42 and freezes there to the ice layer 62.

As an alternative or in addition to the second circuit 122, in a modification, the deposition plates 40 may also be heated with external heating units, such as IR radiators.

The working periods over which a deposition plate 40 on which a fresh layer of ice 62 has been formed can be used and after which an existing ice layer 62 with solids deposited thereon is removed and a fresh layer of ice 62 is formed on the separation plate 40 depends, among other things, on the behavior of the overspray.

In the separation device 38 described above, all deposition plates 40 are cooled or heated at the same time, so that the overspray is removed from all deposition plates 40 in a single process step and a new ice layer 62 is formed on all deposition plates 40 at the same time.

In a modification, a plurality of circulation systems 78 may be provided, each feeding a group of separation plates 40 or even a single separation plate 40 with cooling medium. In this case, different areas of the separation unit 36 can be freed individually of ice / overspray and re-provided with a fresh layer of ice 62. In this case, if the deposition process is not to be interrupted, the relevant deposition plate 40 or the relevant group of deposition plates 40 must be removed from the separation chamber 28, since otherwise overspray could deposit on the exposed separation surfaces 42 when the ice layer 62 has just been removed ,

The entire refrigeration cycle includes means to remove excess heat, as is well known in the art.

In the FIGS. 8 and 9 is one of the FIG. 2 corresponding representation of a modified deposition device shown, the reference numeral 138 carries. All components that correspond to those of the separator 36 carry the same reference numerals.

In this separation device 138, each separation plate comprises 40 an outer matrix of Peltier elements 140, as known from the prior art and of which in the FIGS. 8 and 9 only a few are provided with a reference numeral. For clarity, the interconnection of the Peltier elements 140 is not shown, nor the ice layer 62. The Peltier elements 140 have an externally accessible layer 142 and an inner layer 144, each facing a wall 40.1 or 40.2 of the deposition plate 40, the corresponding Peltier element 140 carries.

In FIG. 9 the walls 40.1 and 40.2 of each separation plate 40 can be seen, between which the cooling line 64 extends. The outer surfaces of the Peltier elements 140 together form the separation surface 42 of the associated deposition plate 40.

The separation plates, which are arranged at the opposite ends of the separator 36, carry in FIG. 9 the reference numerals 40a and 40b. These separation plates 40a, 40b are equipped with Peltier elements 140 only on their outer surface of the wall 40.2 or 40.1 facing an electrode device 44. The separating plates 40 arranged between the terminal separating plates 40a, 40b, of which in FIG. 9 only one is shown, carry both on the outer surface of the wall 40.1 as well as on the outer surface of the wall 40.2 Peltier elements 140th

The three points between the deposition plate 40b and the in FIG. 9 right electrode means 44 indicate that there are more separation plates 40 and electrode means 44 between them.

In the embodiment shown here with Peltier elements 140, the circulation system 78 is still present, with the respective cooling line 64 of the separation plates 40 is connected. Thus, here the circulation system 78 in conjunction with the cooling lines 64 of the separation plates 40 and the Peltier elements 140, the means by which each generates a fresh layer of ice 62 on the Abscheideflächen 42 and / or removes any existing on the Abscheideflächen 42 ice layer 62 with deposited solids can be.

To produce an ice layer 62 on the Peltier elements 140, the valves 98, 100, 104, 106, 110, 112, 116 and 118 of the circulation system 78 are set on the one hand such that the cooling medium flows in the first circuit 120, which flows in FIG. 5 is clarified and as explained above. In addition, however, now the Peltier elements 140 are energized according to their arrangement on the deposition plates 40 so that cool their outer layers 142.

In this case, the respective inner layer 144 of the Peltier elements 140, which is adjacent to the walls 40. 1 or 40. 2 of the deposition plates 40, is heated. The walls 40.1 and 40.2 absorb this heat, which in turn is transferred to the cooling medium flowing through the cooling line 64 and discharged therefrom.

In due course, to remove the ice sheets 62 with overspray adhering thereto from the separator plates 40, the circulating system 78 is operated as discussed above in this context. The Peltier elements 140 are deactivated, however, so that they heat up. Alternatively, the Peltier elements 140 can also be reversed by reversing the current direction so that their outer layers 142 heat up and cause the ice to melt. The respective inner layers 144 of the Peltier elements 140, which are adjacent to the walls 40.1 or 40.2 of the separation plates 40, cool down accordingly, which also reduces the temperature of the respective walls 40.1 and 40.2 of the deposition plates 40. These in turn receive heat from the heated cooling medium which flows through the separation plates 40.

If the separation device 138 is used, in a further modification, the circulation system 78 can also be dispensed with and the required temperature of the separation surfaces 42 can be generated solely by means of the Peltier elements 140. In this case, the Peltier elements 140 are energized in accordance with the desired effect, namely the cooling or heating of their externally accessible outer layer 142. In this case, the Peltier elements 140 thus form per se the device by means of which in each case a fresh ice layer 62 is produced on the separation surfaces 42 and / or an ice layer 62 with deposited solids respectively present on the separation surfaces 42 can be removed.

In a further modification, the deposition plates 40 can also be heated by means of a heating device, such as by means of heating wires attached to the deposition plates 40. These may optionally be provided on the respective outer or inner surface of the respective deposition plate 40.

A heater may be provided in addition to the Peltier elements 140; in this case, the latter are preferably energized only for cooling the separation plates 40. In addition, the second circuit 122 of the recirculation system 78 may be dispensed with, thereby simplifying the overall piping design of the recirculation system 78.

By such a heater, a separate heating individual separation plates 40 is readily possible.

Claims (23)

A method for separating overspray from the overspray-laden cabin exhaust air from coating installations, in particular painting installations, in which the overspray is taken up by an air stream and led to an electrostatically operating separation device (38), where a majority of at least the solids from the overspray at least one Abscheidefläche (42) is deposited, on which a release agent is applied,
characterized in that
as a release agent on the at least one separation surface (42) an ice layer (62) is generated. A method according to claim 1, characterized in that after a working period on the at least one Abscheidefläche (42) existing ice layer (62) removed with deposited solids and a fresh layer of ice (62) on the at least one Abscheidefläche (42) is generated. A method according to claim 1 or 2, characterized in that at least one Abscheidefläche (42), a surface region of a Abscheideplatte (40) is used. A method according to claim 3, characterized in that a separation plate (40) is used which comprises one or more Peltier elements (140). Method according to claim 3 or 4, characterized that a cooling medium is passed through the collecting plate (40). A method according to claim 5, characterized in that for generating the ice layer (62) on the at least one separation surface (42) cooled cooling medium is passed through the separation plate (40) to cool the separation plate (40) such that water from the Abscheideplatte (40) ambient atmosphere as ice layer (62) on the at least one Abscheidefläche (42) precipitates. A method according to claim 5 or 6, characterized in that for removing a layer of ice (62) with deposited solids from the at least one Abscheidefläche (42) heated cooling medium is passed through the Abscheideplatte (40) to heat the Abscheideplatte (40) in such a way in that ice melts on the at least one separation surface (42) at least on the side of the ice layer facing the separation surface (42). Method according to one of claims 5 to 7, characterized in that the cooling medium in generating the ice layer (62) in a circuit (120) with a compressor device (82) and an evaporator device (92) is passed. A method according to claim 8, characterized in that the cooling medium between the compressor means (82) and the evaporator means (92) through the heat exchanger coil (86) of a heat exchanger (88) is guided. A method according to claim 9, characterized in that the freed of particulate cabin air is passed through the heat exchanger (88). Method according to one of claims 8 to 10, characterized in that the cooling medium for heating the at least one deposition surface (42) coming from the compressor device (82) on the evaporator means (92) over to the separation plate (40) is passed. A method according to claim 11, characterized in that the cooling medium is also guided past the heat exchanger (88). Device for separating overspray from overspray-laden cabin exhaust air from paint shops a) at least one separation surface (42) on which the cabin exhaust air can be guided along and which is connected to a pole of a high-voltage source (46); b) an electrode device (44) arranged in the airflow, which is assigned to the separation surface (42) and connected to the other pole of the high-voltage source (46),
characterized in that c) an ice layer (62) is produced as a release agent on the at least one separation surface (42). Device according to claim 13, characterized in that it comprises means (64, 78, 140; 64, 78 ', 140) comprising, by means of which a fresh layer of ice (62) on the at least one Abscheidefläche (42) can be generated and / or on the at least one Abscheidefläche (42) existing ice layer (62) with deposited solids is removable. Apparatus according to claim 13 or 14, characterized in that the at least one Abscheidefläche (42) is a surface region of a Abscheideplatte (40). Apparatus according to claim 15, characterized in that the deposition plate (40) comprises one or more Peltier elements (140). Apparatus according to claim 15 or 16, characterized in that in the interior of the separating plate (40) extends a cooling line (64) through which a cooling medium can be conducted. Apparatus according to claim 17, characterized in that the cooling medium is at least temporarily in a circuit (120) with a compressor device (82) and an evaporator device (92) is conductible, which is connected to the cooling line (64). Apparatus according to claim 18, characterized in that between the compressor means (82) and the evaporator means (92) a heat exchanger (88) with a heat exchanger coil (86) is arranged, through which of the compressor means (82) coming coolant is conductive. Apparatus according to claim 19, characterized in that a flow path (132) of the freed of solids cabin air through the heat exchanger (88) leads. Device according to one of claims 18 to 20, characterized in that via valves (98, 100) connectable by-pass line (96) is present, via which the cooling medium at least temporarily from the compressor device (82) coming to the evaporator device (92). over to the cooling line (64) of the separation plate (40) is conductive. Apparatus according to claim 21, characterized in that the bypass line (96) extends such that the cooling medium also on the heat exchanger (88) over to the cooling line (64) of the separation plate (40) is conductive. Plant for coating, in particular for painting objects, in particular vehicle bodies (4), with a) a coating booth (2), in which the articles (4) can be acted upon with coating material and through which an air stream can be passed, which receives and removes resulting overspray particles of the coating material; b) an electrostatically operating separation device (38),
characterized in that c) the electrostatic precipitation device (38) according to one of claims 13 to 22 is formed.

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