DE3214255A1 - Device for cleaning hollow filters for powder coating plants - Google Patents

Abstract

A device housing (1) is subdivided by partitions (2 + 3) into a jet chamber (4), a filter chamber (5) and a blower chamber (7). A hollow filter (12), rapidly exchangeable by means of a tensioning and holding apparatus, having a cylindrical, zigzag-folded filter element (16), is mounted in the filter chamber (5) on the partition (3) so as to be rotatable and advanceable by means of an advancing mechanism (43). A blowing nozzle head (34) is moved to and fro tight against the periphery of the filter element (16) in the direction of the casing by a compressed air cylinder (46). In the end positions, a pressure impulse nozzle (29) is also briefly operated by the advancing mechanism (43), which pressure impulse nozzle is fitted close to a compressed air vessel (30) and which blows through a trumpet-shaped inlet tube (26) into the clean gas interior (20) of the hollow filter. A blower (8) sucks air from the raw gas space (32) of the filter chamber through a post-filtering unit (51) and delivers exhaust air for the most part via the jet chamber (4) and inlet tube (26) into the clean gas space (20). A first fraction of the completely purified powder is collected true to colour in a collecting vessel (26), a further powder fraction in a collecting vessel (53) beneath the post-filtering unit (59). In place of the pressure impulse nozzle (29), if required, a movable blowing nozzle can alternatively be mounted on the clean gas side. <IMAGE>

Description

Device for cleaning hollow

filters for powder coating plants The invention relates to a Device for cleaning hollow filters for powder coating systems, in particular Filter candles made of thin surface filter material, with one on the wall of the Filter-directed blow nozzle and an adjustment arrangement for relative adjustment of Blowing nozzle and filter wall, the filter wall periodically from the clean gas side is cleaned by pressure changes.

Devices of this type are known from DE-OS 27 31 123. There are cylindrical filter candles with a zigzag-shaped folded cylinder jacket Made of thin-walled inexpensive material such as paper, which is only intended for a single Paint can be used and replaced when there is peeling off on the outside applied powder layer with a single pressure pulse device that acts from the inside is no longer possible. This is definitely due to the cost of the filter material justified if only a few shades are to be processed; especially there with one Use of one or two filters per system is expected.

In the newer coating lines, on the other hand, there are several one behind the other Recovery units are used, each with about ten such filter elements exhibit. In addition, will in some establishments with up to twenty or more shades worked. If you wanted each filter only for the specific one If you use the color, the storage costs for the filter elements would be huge considerable, quite apart from the fact that there is then a contamination of the individual Shades of color cannot be ruled out. In addition, the view has emerged that that the entire filter units are always replaced for a quick color change should, which is unusual for the investment in modern coating lines increases.

Although it is also known per se, filter bags made of textile fabric by To clean washing processes, but this cleaning process is also proportionate expensive and required in turn with the numerous filter elements required increased investment costs.

The invention is based on the device described above and pursues the task of developing this device in such a way that a practical complete cleaning of at least the thin-walled and inexpensive hollow filter elements made of paper or comparable material and thus the number of to be kept ready Filter elements and also filter units per coating system is reduced.

To solve this problem is according to the invention in a separate Cleaning housing a filter chamber with a holding and clamping device for sealing clamping of the open end of the hollow filter in the area of a chamber wall provided, and a blow nozzle arrangement is assigned to the raw gas side of the hollow filter, while the clean gas side of a separate, periodically acting pressure change device is exposed.

The set-up times for the change process are relatively short here and correspond to the times it takes to change a filter in a filter unit even needed. Of the separate handling is beneficial, that the filter elements are provided with edge reinforcements or in or on dimensionally stable Straps are attached and equipped with fasteners that allow a quick allow easy removal and reinsertion. The same fasteners can therefore also easily be used in the device according to the invention that are normally used for the same type of filter element, but also used for the use of differently designed filter elements can be.

There is not even a separate rush for the cleaning process itself because in almost all systems there are always a few colors very often and a larger number of color tones are only used periodically. So you can possibly Leave the * main colors permanently installed in the individual filter units for the Just keep one or two such filter units ready for special colors and then Design the work plan in such a way that the special colors can only be used with sufficient time Distance are used. * Filter for the Therefore, the surface part of the filter element repeatedly subjected to a very thorough cleaning process, which is with thin-walled filters can be achieved with the means available. While namely in the case of fabric filters, fleece filters, fabric filters, etc., powder particles deep penetrate into the layer material, they can occur in the case of surface filter material from paper, for example, practically only precipitate on the surface and not particularly there Develop adhesive forces. The vast majority of the powder is therefore only swept away by intense blowing, and only some of the powder particles that have established themselves a little more stubbornly, must then through the pressure changes be replaced from the clean gas side. So it is very well in this way possible, the whole filter element thoroughly and completely from the previous color to free and use for other shades.

In contrast to washing processes and the like, the a) can be cleaned Powder can in principle be recovered, for example by being at the bottom of the filter chamber Below the hollow filter to be cleaned, a particularly exchangeable collection vessel is arranged for the detached coating powder. This powder obtained in this way can then immediately or

used again for coating after a preparation process will.

According to a further proposal of the invention, the raw gas space becomes the filter chamber on the way over a particular one provided with its own cleaning device Filter unit connected to a vacuum source. The detached powder will So, as long as it does not fall into the collecting vessel, it is caught by the secondary filter unit, for example by a second collecting vessel arranged under the post-filter unit, the also from the underside of the filter chamber below the first collecting vessel Powder parts can be fed through a transfer element.

In principle it is of course possible to use all powder-carrying parts of the To clean the device completely when changing the color, so that one also the powder collected by the secondary filter unit in the second collecting vessel can introduce into the coating process. However, this effort would only be for one otherwise unusually low degree of recovery justified.

The vacuum source is expediently by a fan, in particular a circulating air fan is formed, the pressure side with the clean gas space of the filter chamber communicates. Even if you have the pressure outlet of the blower and the inlet of the clean gas room is only adjacent in the room, most of the emissions are emitted Amount of air circulated, possibly also sucked in through an upstream filter.

One attached to the clean gas side of the filter wall Pressure changing device is expediently designed as an impact-like pressure pulse device, the individual surface elements, because of the simpler execution, but also at the same time can cover the entire filter wall.

The holding and clamping device is preferably an introduction device assigned to the compressed air supplied to the inner clean gas side of the filter, whose smallest cross-section is several times smaller than the internal cross-section of the filter. As a result, the air expands out of this smallest cross section enters the interior of the hollow filter.

The holding and clamping device is advantageously a centric into the edge of the filter associated with a trumpet-like widened inlet pipe, in particular in the manner of a Venturi tube like a funnel towards its inlet end is expanded.

A pulse nozzle of the pressure pulse device can pass through it centrally the inlet device must be directed through into the clean gas space of the filter. In this way the trumpet reed acts like an injector that accelerates circulating air thus increasing the pressure. So it becomes the permanently maintained slight internal pressure briefly sharply increased throughout the interior, which practically affects the entire Effects filter wall under elastic back and forth deformation. Here is the The shorter the flow losses between the overpressure source, the greater the impact and nozzle are. It is therefore advisable to use the pulse nozzle of the pressure pulse device with a pulse control valve to be assigned to a separate compressed air tank in close proximity.

According to a further proposal of the invention, a nozzle part is in the longitudinal direction of the Iiohlfilters moving back and forth between its end positions automatically appropriate.

In this way, for example, when hiking up and down one entire circumference can be cleaned. Since this, however, relatively large amounts of air Would have to be circulated, is currently preferred, a blow nozzle head along a To arrange the surface line of the hollow body movable and the filter rotatable by means of a mounted washer of the holding and clamping device rotatable in the circumferential direction and drivable to lead. In this way the treatment time is extended, because you clean almost point by point.

However, this allows you to work on the limited areas with greater intensity of the filter element and achieves a through the lower air turbulence greater degree of recovery.

In principle, the filter can also be rotated uniformly. It has been shown, however, that cleaning is improved if the annular disk an indexing device designed in particular as a pawl switching mechanism is assigned. In this case, the effect remains during a stroke of the blow nozzle head constant on the entire surface line.

The indexing mechanism for the washer and / or the control valve of the Pulse nozzle can or can be connected to the end position control of the, preferably as a compressed air cylinder Connect trained movement drive for the blow nozzle head.

One can put an impulse in each or only one of the both stroke end positions.

* Shell or Now does not necessarily have to be a pressure pulse device on the clean gas side, i.e. a pulsed pulse nozzle may be provided, but it may well be on opposite sides of the filter wall each have at least one nozzle part be movably guided in such a way that the paths of the two nozzle parts are sufficient Maintain an intermediate distance from one another, in particular at least in the circumferential direction from one another are offset. As a rule, blower nozzle heads that act on narrowly limited areas are used use, whereby on the clean gas side the main thing is to get one as possible huge Apply expulsion pressure from the inside to the outside while it is on the raw gas side is about sweeping away the deposited layer of powder particles. drive and switching can basically be the same inside and outside, independently of where the clean gas side and raw gas side are now.

In the case of filter candles folded in a zigzag shape, it is advisable the switching step of the switching device to the mean distance between matched adjacent filter folds. It can be so, for example, if the filter candle is sufficiently dimensionally stable, always in the same way in one fold be blown in.

According to a preferred embodiment of the invention, the blow nozzle head several, in particular differently oriented blow nozzles, for example may be ordered in rows and rows, each of several adjacent ones At least one row of nozzles is assigned to folds of the hollow filter. It will also the cleaning process improves when the air nozzles of the two outer rows are used The filter axis of the nozzle head used on the raw gas side is inclined in each case are employed to the outside, so always an air nozzle in the direction of movement at an angle blows forward. In the case of a blow nozzle head placed on the clean gas side, on the other hand, the nozzle jet hits the filter wall as perpendicularly as possible.

The drawing shows an embodiment of the invention schematically again. 1 shows a longitudinal section through a cleaning device according to the invention, FIG. 2 shows a section along the line II-II in FIG. 1, FIG. 3 shows an enlarged partial illustration from FIG. 1 with a changed height position of the blow nozzle head and FIG. 4 shows a section according to the line III-III in FIG. 2.

The device housing 1 is surrounded by a vertical partition 2 and a horizontal partition 3 divided into a nozzle chamber 4, a filter chamber 5, a post-filter chamber 6 and a blower chamber 7. Their blower 8 is at the rear In connection with the ambient air via an opening 10 provided in the chamber ceiling 9. However, since the nozzle chamber 4 has a * suction opening on the side just above the opening 10 11 possesses, the blower air is largely passed through as circulating air from the nozzle chamber 4 the filter chamber 5 and the post-filter chamber 6 are sucked in. *possibly. with a pre-filter occupied The hollow filter 12 to be cleaned is, as can be seen from FIGS. 1 and 3, formed by a substantially cylindrical filter candle, whose approximately fine-pored Paper or similar

Like. Material existing filter element 16 folded in a zigzag shape is, seen from the outside wedge ribs 13 with wedge gaps 14 under approximately the same Alternate the angular distance and supported on the inside by a cylindrical perforated plate 15 are.

At the lower end of the edge of the filter elements 16 is through a cup-shaped Sheet metal bottom 17 comprises and at the upper end of a pot rim 18 on an annular disc 19, which can be rotated about a vertical axis in an opening in the intermediate wall 3 is stored.

To attach the Iiohlfilters 12 to the annular disk 19 are used same means as for suspension in filter units, namely an axial one Threaded spindle 21 with crank 22 and nut 23 for support on a web of the annular disc 19. This firmly carries a ratchet toothed ring 24 and the edge of a trumpet tube 25, which forms a slightly conical widening 26 on the inlet side.

At a distance above this extension 26 is in the nozzle chamber 4 a Pressure pulse device 27 attached, which is closely assembled its own, approximately pressure vessel 30 connected to a compressed air line and a pneumatically controllable one Has pulse valve 28 with pulse nozzle 29. These develop- sends lengthways the filter axis 31 periodically controlled pressure impulses through the trumpet tube 25 through into the interior and thus the clean gas space 20 of the filter chamber 5. If Pressure impulses are applied in the axis of the trumpet tube, they tear like an injector Air in the edge areas and thus achieve a further sudden increase in pressure in the clean gas space 20, whereby according to the arrows 33 instantly more constant Overpressure is achieved on the entire filter wall 16 and thereby also powder particles to be detached on the outside, which is not easily distinguished from the same Rinse side down.

As can also be seen from FIG. 3, the raw gas space 32 is close to the circumference of the filter element 16, a blow nozzle head 34 is attached. In the front of this Nozzle head 34 are blowing nozzles in four vertical rows and three horizontal rows 35 mounted so that the nozzles of the individual rows in a wedge gap Blow in 14, i.e. the circumferential distance of the V-ribs 13 is approximately the same as the horizontal Distance between air nozzles 35.

The middle line 36 blows approximately perpendicular to the filter axis 31, the upper line 37 is inclined upwards, the lower line 38 is inclined towards the top below. The blow nozzle head 34 is held on a carriage 39 which is within a Shield 40 guided on vertical guide rods 41 and on piston rod 42 a pneumatic cylinder 46 is attached, which is located under the control not shown Limit switch between the lower end position in FIG. 1 and that indicated by 341 upper end position moved. According to Fig. 2, the nozzle head 34 is slightly below its upper end position.

The tooth pitch of the ratchet toothed ring 24 is, as can be seen in FIG. 3 leaves, based on the circumferential division of the V-ribs 13. It is based on impulses by a ratchet mechanism 43 with compressed air cylinder 44 and spring pawl 45 each around the switching step a is switched on, which is the angular division between the V-ribs 13 corresponds.

The commands for the pulse nozzle 29 and the compressed air cylinder 44 are at the same time in one or both end positions of the compressed air cylinder 46 with the Reversal triggered.

So that each wedge gap 14 is at least twice in the upward direction and flushed twice in the downward direction through the four rows of air nozzles 35, wherein a pressure pulse is triggered during the switchover from one wedge gap to the other and the powder particles not only to be lifted off by blowing are detonated.

A significant proportion of the color powder detached in this way is in one first box-shaped or bowl-shaped, set up below the hollow filter 12 Collection vessel 47 collected.

This collecting vessel 47, like the hollow filter 12 itself, can pass through an opening closed by means of a door 48 in the outer wall of the filter chamber 5 can be replaced and can be used as a pure color powder immediately or after to a reprocessing process for reuse.

In the post-filter chamber 6 below the fan 8 there is a post-filter unit 49 attached with individual filter elements 51 in the form of rectangular pockets. The post-filter unit can by a vibrator 52 in a known manner at least can be cleaned up to a limited extent.

At a distance below the post-filter unit 49 is a second one box-shaped collecting vessel 53 removably attached. It becomes inward on all sides surmounted by baffles of a pyramid funnel 54, which is primarily one of the Bottom of the filter chamber 5 below the inclined wall 55 brought down from the immel vessel 47 having.

Deviating from the M # guiding shown, the from the pressure change process carried out on the clean gas side not simultaneously on the affect the entire inner surface, but you can use small surface elements in succession through a single nozzle placed close to the wall for a short time with local load even more pressure. For example, a blower nozzle head 34 can be opened along the inside or the clean gas side of the hollow filter, although the air nozzles less on a rinse, but on as large a local area as possible Deformation and an expulsion effect should be designed. So it is not necessary that nozzles of lines 37 and 38 are directed obliquely up and down you can use a single nozzle there, which makes you all the more powerful Pressure shock generated when changing from one wedge gap 14 to the following one. In this way, the two blow heads can also be permanently assigned to one another and on parallel Move tracks. However, it seems better to sweep the raw gas side To be maintained in the longitudinal direction according to the illustration, on the clean gas side, however to allow the rotary motion to predominate in order to increase the impact effect. Included The paths of the two blow nozzle heads can of course overlap, but this can also be avoided in terms of control.

A movable blow nozzle head or a movable pressure pulse nozzle can also be provided in addition to the stationary pressure pulse nozzle, such as Several cleaning nozzles were installed on both sides of the filter wall that appear the same or different. To an overlap of the tracks To prevent nozzles acting against one another, it may be appropriate, for example, a nozzle acting in a jolt-like manner on the inside in the longitudinal direction of the filter between two outside attached sweeping nozzles, with the inner nozzle additionally an increased Rotational movement around the filter axis is superimposed. If you then have all three groups of air nozzles Proceeding over the entire length of the filter results in avoidance of overlaps a particularly even and intensive cleaning.

Furthermore, cleaning is possible with at least similar devices of cylindrical, prismatic or star-shaped hollow filters possible, on their The coating powder has deposited on the inside. The filters themselves do not necessarily have to be closed at one end, but it is recommended that to make this conclusion to the cleaning process after removing it from the filter unit, to prevent the precipitation of individual particles on the clean gas side.

The features set out in the claims should also include the remaining descriptions are considered essential to the invention, in particular the statements at the end of the description of the figures.

Claims (21)

Device for cleaning hollow filters for powder coating systems Claims 1. Device for cleaning Elohl filters for powder coating systems, in particular filter candles made of thin surface filter material, with a the wall of the filter is erected blower nozzle and an adjustment arrangement for relative adjustment of air nozzle and filter wall, the filter wall from the clean gas side is cleaned periodically by pressure changes, characterized in that in a separate cleaning housing (1) a filter chamber (5) with a holding and Clamping device (19,21-23) for the sealing clamping of the or an open end of the hollow filter (12) in the region of a chamber wall (3) is provided and a blower nozzle arrangement (34) on the raw gas side of the Iiohlfilters (12) is assigned, while the clean gas side (20) is a separate, periodic acting pressure change device (27) is exposed. 2. Apparatus according to claim 1, characterized in that on the ground the filter chamber (5) below the hollow filter (12) to be cleaned, in particular exchangeable collecting vessel (47) arranged for the detached coating powder is. 3. Apparatus according to claim 2, characterized in that the raw gas space (32) the filter chamber by way of a cleaning device, in particular with its own (52) provided after-filter unit (44) connected to a vacuum source (8) is. 4. Apparatus according to claim 3, characterized in that below In addition to the post-filter unit (52), a second collecting vessel (53) for what is to be collected there Coating powder is arranged. 5. Apparatus according to claim 4, characterized by one of the underside the filter chamber (5) below the first collecting vessel (47) to above the second Collecting vessel (53) guided transfer element. 6. Apparatus according to claim 5, characterized in that the vacuum source is formed by a fan (8), in particular a circulating air fan, which is on the pressure side is in communication with the clean gas space (20) of the filter chamber (5). 7. Apparatus according to claim 1 or 6, characterized in that the holding and clamping device (19,21-23) an introduction device (25) for the the inner clean gas side of the filter (12) supplied air is assigned, the smallest cross-section is several times smaller than the internal cross-section of the filter (12). 8. Apparatus according to claim 7, characterized in that the Ilalte- and clamping device (19) centered in the edge of the filter (12) like a trumpet extended inlet pipe (25) is assigned. 9. Apparatus according to claim 8, characterized in that the inlet pipe (25) expanded like a funnel towards its inlet end in the manner of a Venturi tube is (26). 10. Device according to one of claims 1 to 9, characterized in that indicates that a pressure change device attached to the clean gas side (20) of the filter wall (16) is designed as an impact-like pressure pulse device (27). 11. The device according to claim 10, characterized in that a Pulse nozzle (29) of the pressure pulse device (27) centrically through the inlet device (25) is directed through into the clean gas space (20) of the filter (12). 12. Apparatus according to claim 1 or 11, characterized in that the pulse nozzle (29) of the pressure pulse device (27) with a pulse control valve (28) is assigned in close proximity to a separate compressed air tank (30). 13. Device according to one of claims 1 to 12, characterized in that that at least one nozzle part (34) in the longitudinal direction of the hollow filter (12) between is attached to its end positions so that it can move back and forth automatically. 14. Apparatus according to claim 13, characterized in that a The blow nozzle head (34) is arranged to be movable along a surface line of the hollow body (12) and the filter by means of a rotatably mounted washer (19) of the holding and Clamping device (19, 21-23) rotatable and drivable in the circumferential direction is. 15. The device according to claim 13, characterized in that the The annular disc (19) is designed in particular as a pawl switching mechanism (43) Switching device is assigned. 16. The device according to claim 12 or 13, characterized in that that the indexing mechanism (43) for the annular disc (19) and / or the control valve (28) the pulse nozzle (29) to the end position control of the preferably as a compressed air cylinder (46) trained movement drive for the blow nozzle head (34) is connected or are. 17. Device according to one of claims 13 to 16, characterized in that that on opposite sides of the filter wall (16) in each case at least one Blower nozzle part (34) is movably guided in such a way that the paths of the two blower nozzle parts Keep a sufficient distance between them, in particular at least in the circumferential direction are offset from one another. * Coat or 18. Apparatus according to claim 16 or 17, for filter candles (12) folded in a zigzag shape in the circumferential direction, characterized in that that the switching step of the indexing device (43) to the mean distance between adjacent filter folds (13,14) is matched. 19. Device according to one of claims 14 to 18, characterized in that that the blower nozzle head (34) has several, in particular differently oriented, blower nozzles (35). 20. The device according to claim 19, characterized in that the Blow nozzles (35) are arranged in rows and rows and each fold (13,14) of the hollow filter (12) is assigned at least one row of nozzles. 21. The device according to claim 20, characterized in that the Blowing nozzles (35) of the two outer rows of the blowing nozzle head used on the raw gas side (34) to the filter axis (31) are each made at an angle to the outside.