ZA201100997B

ZA201100997B - Filter device and method for separating wet paint overspray

Info

Publication number: ZA201100997B
Application number: ZA2011/00997A
Authority: ZA
Inventors: Jens Holzheimer; Dietmar Wieland
Original assignee: Durr System Gmbh
Priority date: 2007-08-24
Filing date: 2011-02-08
Publication date: 2011-10-26
Also published as: ATE508780T1; EP2180935A1; CA2697442C; KR101708624B1; AU2008291387A1; EP2180935B1; PL2335800T3; WO2009026984A1; BRPI0815903B1; MX2010002107A; ES2410982T3; PT2335800E; AU2008291387B2; PL2505255T3; CN103084019A; BRPI0815903A2; EP2581126B1; EP2581126A1; ES2503620T3; CN103084018A

Abstract

A filter element separates off an over-spray from a flow of raw/crude gas. A tank for holding auxiliary material holds a filtering auxiliary material. A filtering device (132) has an inlet, through which the flow of raw/crude gas is directed into the tank for holding auxiliary material so as to run into the filtering device. Independent claims are also included for the following: (1) A device for separating off wet-paint over-spray from a flow of raw/crude gas containing over-spray particles; (2) Equipment for painting objects like vehicle bodywork; (3) A method for separating off wet-paint over-spray from a flow of raw/crude gas containing over-spray particles.

Description

a R

JIN il 1 1

The present invention relates to a filter device for separating wet paint overspray from a stream of crude gas : containing overspray particles, wherein the device comprises at least one filter element for separating the overspray from the stream of crude gas and at least one auxiliary material reservoir for accommodating an auxiliary filter material.

Such a device is known from DE 10 2005 048 579 Al for example.

In the case of this known device, a dry process for separating the wet paint overspray from the stream of crude gas in a spray booth is effected in the filter device after a fluidic particle-like auxiliary filter material referred to as a "precoat" material has been injected into the stream of crude gas using a nozzle assembly.

This auxiliary material serves as a barrier layer that is deposited on the surfaces of the filter element in order to prevent these surfaces from clogging due to overspray particles adhering thereto. By periodically cleaning the filter elements in the filter device, the mixture consisting of auxiliary material and wet paint overspray from the filter elements ends up in an auxiliary material reservoir from which it can be sucked out and supplied to the nozzle assembly in order to be reused as an auxiliary material. Furthermore, the mixture of auxiliary material and wet paint overspray located in the auxiliary material reservoir can be whirled-up by means of bursts of compressed air issuing from a compressed air lance so as to cause 1t to raise up out of the auxiliary material reservoir towards the filter elements where it is then deposited.

In the case of this known device, provision is made for closure devices by means of which the flow path for the flow of crude gas from the application area to the filter devices is periodically blocked in order to prevent auxiliary material from reaching the application area of the paint shop during the process of injecting auxiliary material into the stream of crude gas from the nozzle assembly. The auxiliary material that is being whirled up out of the auxiliary material reservoirs is not sufficient to produce an adequate protective layer on the filter elements. Moreover, fresh auxiliary material can only be introduced into the stream of crude gas via the nozzle assembly.

One object of the present invention is to provide a filter device of the type mentioned hereinabove which will enable the at least one filter element to be supplied with the auxiliary material in a simple and efficient manner but without allowing the auxiliary material to enter the application area in which the stream of crude gas picks up the wet paint overspray.

In accordance with the invention, this object is achieved in the case of a filter device incorporating the features mentioned in the first part of Claim 1 in that the filter device comprises at least one inlet opening through which the stream of crude gas enters the filter device and at least one device for mixing the material present in the the at least one auxiliary material reservoir.

Other features of the filter device according to the invention are discussed below and are set forth in the accompanying claims.

Due to the fact that the stream of crude gas is guided directly into the auxiliary material reservoir, the effect is achieved that an adequate quantity of auxiliary material is added to the stream of crude gas.

Furthermore, because the stream of crude gas through the } inlet opening enters a filter device which is otherwise closed with respect to that part of the flow path for the stream of crude gas that is located prior to the inlet opening and also with respect to the application area of the paint shop, it is ensured that auxiliary material from the auxiliary material reservoir will not enter that part of the flow path for the stream of crude gas which is located prior to the inlet opening nor will it enter the application area since this auxiliary material would have to move through the inlet opening against the direction of flow of the stream of crude gas for this to happen.

By making use of the filter device in accordance with the invention, one can dispense with an additional nozzle assembly for introducing auxiliary material into the stream of crude gas.

Furthermore, by using the filter device in accordance with the invention, 1t 1s not necessary to temporally close parts of the flow path of the stream of crude gas from the application area to the filter device during the process of adding auxiliary material to the stream of crude gas.

Preferably, the auxiliary material is introduced into the stream of crude gas only within the filter device after the stream of crude gas has passed the inlet opening of the filter device.

In order to enable the direction of flow of the stream of crude gas to be oriented as precisely as possible, provision is preferably made for the inlet opening to be in the form of an inlet channel extending in the direction of flow of the stream of crude gas.

In order to increase the maximum flow rate of the stream of crude gas in the inlet channel, provision may be made for the through-flow cross section of the inlet channel to narrow in the direction of flow of the stream of crude gas towards a narrow section therein.

In order to reduce the flow rate of the stream of crude gas again after it has passed a narrow section in which the stream of crude gas experiences its maximum flow rate and thus prevent the stream of crude gas from impinging the auxiliary material in the auxiliary material reservoir at too high a flow rate, provision may be made for the through-flow cross section of the inlet channel to widen out in the direction of flow of the stream of crude gas away from a narrow section therein.

The inlet opening may be delimited downwardly by a lower guide surface.

For the purposes of guiding the stream of crude gas into the auxiliary material reservoir in the desired manner, it 1s expedient for the lower guide surface to be inclined to the horizontal at least in sections thereof, and in particular then, for the lower guide surface to be inclined downwardly as seen in the direction of flow of the stream of crude gas.

It has proved to be particularly expedient, if, at least in sections thereof, the lower guide surface is inclined to the horizontal at an angle of at least approximately 30°, preferably at an angle of at least approximately 40°.

Furthermore, it has proved to be expedient, if, at least in sections thereof, the lower guide surface 1s inclined to the horizontal at an angle of at most approximately 75°, preferably of at most approximately 65°.

In order to prevent the stream of crude gas from breaking- away from the lower guide surface and thus ensure that the stream 1s directed into the auxiliary material reservoir, it 1s of advantage for the lower guide surface to comprise an upper section and a lower section which follows onto the upper section in the direction of flow of the stream of crude gas, wherein the lower section is inclined to the horizontal to a greater extent than the upper section.

Furthermore, it is expedient for the guidance of the stream of crude gas, if the inlet opening is delimited upwardly by an upper guide surface.

The upper guide surface is also preferably inclined to the horizontal at least in sections thereof, and in particular then, in such a way that the upper guide surface is inclined downwardly as seen in the direction of flow of the stream of crude gas.

Hereby, 1t has proved to be expedient, if, at least in sections thereof, the upper guide surface is inclined to the horizontal at an angle of at least approximately 30°, preferably at an angle of at least approximately 40°.

Moreover, it has proved to be expedient, if, at least in sections thereof, the upper guide surface is inclined to the horizontal at an angle of at most approximately 75°, preferably at an angle of at most approximately 65°.

The average flow rate of the stream of crude gas when passing the narrowest part of the inlet opening should be sufficiently high as to prevent auxiliary material or wet paint overspray that has been cleansed by the at least one filter element from leaking out through the inlet opening.

Preferably, the average flow rate of the stream of crude gas when passing the narrowest part of the inlet opening amounts to at least approximately 2 m/s, in particular at least 3 m/s.

Furthermore, it has proved to be expedient if the average flow rate of the stream of crude gas when passing the narrowest part of the inlet opening amounts to at most approximately 8 m/s, preferably at most approximately 5 m/s.

In order to achieve a properly directed flow of the crude gas into the auxiliary material reservoir, the inlet opening is preferably formed in such a way that the stream of crude gas does not break-away in the vicinity of the inlet opening.

In order to achieve the effect that the overspray-loaded stream of crude gas will come into as little contact as possible with components cof the filter device on which the overspray could be deposited prior to it reaching the at least one filter element, it is of advantage if the auxiliary material reservoir is formed in such a way and is arranged relative to the inlet opening in such a way that the stream of crude gas emerging from the inlet opening is deflected, within the auxiliary material reservoir, towards the at least one filter element.

In order to achieve the effect that as little of the auxiliary material as possible reaches the vicinity of the inlet opening of the filter device, it is expedient for the filter device to comprise at least one retaining element which keeps auxiliary material in the auxiliary material reservoir away from the inlet opening.

Such a retaining element 1s particularly effective, if it projects into the interior of the filter device and/or into the interior of the auxiliary material reservoir.

Provision may be made for the retaining element, which can be in the form of a retaining plate for example, to form a lower boundary of the inlet opening.

In this case, provision can be made, in particular, for the retaining element to comprise a section of a guide surface for the stream of crude gas which is inclined to the horizontal to a greater extent than a further section of the guide surface which is arranged, in the direction of flow of the stream of crude gas, before the section of the guide surface that is arranged on the retaining element.

The stream of crude gas is thereby effectively prevented from breaking~away from the guide surface.

In order to achieve the effect that the stream of crude gas entering the filter device will initially be guided in its entirety directly into the auxiliary material reservoir and only then, when it has been loaded with auxiliary material, allowed to reach the at least one filter element, it is of advantage for the filter device to comprise at least one filter shielding element which is formed and arranged in such a way as to prevent the crude gas entering the filter device from flowing directly from the inlet opening to the at least one filter element.

In particular, such a filter shielding element can be in the form of a screening plate.

In order to prevent insofar as possible the material (auxiliary material and wet paint overspray) that has been removed from the at least one filter element from reaching the vicinity of the inlet opening of the filter device, it is of advantage for the filter device to comprise at least one deflecting element which keeps the material that has been removed from the at least one filter element away from the inlet opening for the crude gas.

Preferably, the at least one deflecting element guides the material that has been removed from the at least one filter element into the auxiliary material reservoir.

Such a deflecting element can be formed, in particular, as a deflecting plate.

In order to prevent the auxiliary material and/or the overspray from settling in the vicinity of the inlet opening, it is of advantage for the filter device to comprise at least one cover element which covers a corner area of the inlet opening so that auxiliary material and/or overspray are kept away from this corner area of the inlet opening.

Furthermore, such a cover element can comprise, in particular, a substantially triangular covering surface.

In particular, such a cover element can be formed as a cover plate.

As an alternative or in addition to the provision of such a cover element, the inlet opening could comprise a corner surface in at least one corner area, sald surface being oriented at an angle to the vertical and at an angle to the horizontal so that auxiliary material and/or overspray can slide downwardly on the corner surface due to the inclination of the corner surface.

Such a corner surface may be provided, in particular, on a cover element provided in the corner area of the inlet opening.

In order to increase the quantity of auxiliary material that is absorbed by the stream of crude gas when it flows through the auxiliary material reservoir, the filter device can comprise at least one whirling device for whirling up the auxiliary material located in the auxiliary material reservoir.

The filter device summarised above is suitable, in particular, for use in an arrangement for separating wet paint overspray from a stream of crude gas containing overspray particles which comprises at least one filter device as summarised above and a flow chamber through which the stream of crude gas flows from an application area of a paint shop to the inlet opening of the at least one filter device.

Preferably thereby, the cross section of the flow chamber through which the stream of crude gas is adapted to flow decreases in the direction of flow of the stream of crude gas up to the at least one inlet opening of the at least one filter device. Hereby, the flow rate of the stream of crude gas when flowing through the flow chamber increases up to the inlet opening of the at least one least filter device, this thus preventing the auxiliary material and/or the overspray from the filter device from reaching the application area of the paint shop against the direction of flow of the stream of crude gas.

In particular, provision may be made for the flow chamber to be delimited by at least one substantially horizontal boundary wall, this then causing the cross section of the flow chamber through which the stream of crude gas is flowing to suddenly decrease.

In order to prevent wet paint or fire-extinguishing water resulting from burst hoses in the application area for example from entering the flow path of the stream of crude gas and from there, reaching the filter device, it is of advantage for the arrangement to comprise at least one flow guide plate which is arranged above at least one filter device and is inclined to the horizontal at an angle of at most approximately 10°, preferably at an angle of at most approximately 3°, so that any liquid reaching the flow guide plate cannot then enter the flow path of the stream of crude gas.

If the arrangement comprises at least one walkway which is accessible to service personnel, then its upper surface is preferably inclined to the horizontal at least in sections thereof at an angle of at most approximately 10°, preferably at an angle of at most approximately 3°, so that fluid reaching the walkway will not enter the flow path of the stream of crude gas. This also serves to keep leaking wet paint or fire-—extinguishing water resulting from burst

! hoses in the application area for example out of the flow path of the stream of crude gas through the flow chamber.

The arrangement summarised above is suitable, in particular, for use in a plant for painting articles and in particular, vehicle bodies, wherein said plant comprises at least one application area for the application of wet paint to the articles requiring painting and at least one arrangement as summarised above for separating wet paint overspray.

It has proved to be expedient hereby, for the vertical spacing between the application area and the inlet opening of the filter device to amount to at least approximately 1.0 m and preferably, to at least approximately 1.5 m.

Furthermore, the present invention relates to a method for separating wet paint overspray from a stream of crude gas containing overspray particles, which comprises the following method steps: = introducing the stream of crude gas into a filter device; - separating the overspray from the stream of crude gas by means of at least one filter element arranged in the filter device; - accommodating an auxiliary filter material in an auxiliary material reservoir; and - mixing the material present in the auxiliary material reservoir by means of a device for mixing the material present in the auxiliary material reservoir.

Other features of the method are discussed below and are set forth in the appended claims.

The present invention offers the advantage that as little overspray as possible remains sticking to the walls of the flow chamber or to the walls of the filter device on its way to the at least one filter element.

The at least one filter element is accommodated in a box which is closed insofar as possible so that no auxiliary material or overspray cleansed from the filter element reaches the application area, but, without the need to temporarily block parts of the flow path of the stream of crude gas for this purpose.

The air flow within the filter device is arranged in such a way that the auxiliary material will be distributed over the filter element or the filter elements as homogeneously as possible.

The capacity of the filter device in accordance with the invention can be matched to the quantity of crude gas passing through the application area.

The present invention 1s suitable, 1in particular, for use in dry-process, wet-paint overspray-removal systems for paint booths in the automobile industry or in a general industrial painting field.

The present invention enables the stream of crude gas to be exposed to auxiliary material and the filter elements to be subjected to a cleansing process during an on-going painting process.

Further features and advantages of the invention form the subject matter of the following description and the pictorial illustration of exemplary embodiments.

In the drawings:

Fig. 1 shows a schematic perspective illustration of a painting booth wherein an arrangement for separating wet paint overspray from a stream of crude gas containing overspray particles is arranged below said booth and comprises a flow chamber that is arranged under the painting booth and incorporates three filter modules located on each of the two sides of the flow chamber;

Fig. 2 a schematic vertical cross section through the plant depicted in Fig. 1;

Fig. 3 a schematic vertical cross section corresponding to Fig. 2 through the plant depicted in Fig. 1 wherein, in addition, the respective directions of fiow of the crude gas, the exhaust air emerging from the filter modules and the air supply fed into the flow chamber for the production of transverse air curtains are indicated by arrows;

Fig. 4 a schematic plan view from above of the plant depicted in Figs. 1 to 3;

x : )

Fig. 5 a schematic side view of the plant depicted in

Figs. 1 to 4; i

Fig. 6 a schematic perspective illustration of the arrangement for separating wet paint overspray \ from a stream of crude gas containing overspray i particles which is arranged under the paint booth of the plant depicted in Figs. 1 to 5 and which comprises transverse partitioning walls i subdividing the flow chamber into sections that succeed one another in the longitudinal direction of the flow chamber; !

Fig. 7 a schematic perspective illustration of an individual filter module which is intended to be arranged between two further filter modules bordering thereon (central module);

Fig. 8 a schematic perspective illustration of an individual filter module which is intended to be arranged adjacent to a further filter module such as to form one end of a series of filter modules at the opposite side thereof (corner module);

Fig. 9 a schematic vertical cross section through a filter module;

Fig. 10 a schematic vertical cross section through a filter module and the adjacent region of the flow chamber within which the respective local

! ! . , i direction of flow of the stream of crude gas is indicated by arrows;

Fig. 11 a schematic perspective illustration of a boundary region of an inlet opening of a filter module;

Fig. 12 a schematic front view of a filter module;

Fig. 13 a schematic vertical section through an auxiliary material reservoir having a level sensor and a whirling device arranged in the interior of the container;

Fig. 14 a schematic side view of an inspection door of the auxiliary material reservoir depicted in Fig. 13 with a level sensor and a whirling device held : on the inspection door;

Fig. 15 a schematic plan view of the exterior of the inspection door depicted in Fig. 14;

Fig. 16 a schematic plan view from above of a collecting grating arranged in the auxiliary material reservoir depicted in Fig. 13;

Fig. 17 a schematic illustration of an arrangement for supplying fresh auxiliary material from a storage tank to auxiliary material reservoirs of the type illustrated in Fig. 13 which are in their working positions;

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Fig. 18 a schematic illustration of a removal arrangement ! for conveying auxiliary material that is mixed with overspray from the auxiliary material reservoirs to a collecting tank; i

Fig. 19 a schematic illustration of a filter module and an exhaust air duct incorporating fans which is ; arranged downstream of the filter module and also i of various devices for monitoring the operative state of the fans and an arrangement for supplying compressed air to the filter elements, to a whirling device and also to a fluid base of the filter module;

Fig. 20 a schematic vertical cross section through a second embodiment of an arrangement for separating wet paint overspray from a stream of exhaust gas containing overspray particles which comprises inclined flow guide plates for controlling the flow of a transverse air stream and a walkway having an inclined upper surface between the filter modules;

Fig. 21 a schematic vertical cross section through an alternative embodiment of an auxiliary material reservoir which is provided with a pneumatically operated agitating device for mixing the material in the auxiliary material reservoir and for evening-out the result;

: .

Fig. 22 a schematic plan view from above of the auxiliary material reservolr with a pneumatically operated agitator as depicted in Fig. 21;

Fig. 23 a schematic vertical section through a further alternative embodiment of an auxiliary material reservoir which is provided with an electrically operated shaft and paddles for mixing the material in the auxiliary material reservoir and for evening-out the result; and

Fig. 24 a schematic plan view from above of the auxiliary material reservoir including the electrically operated shaft depicted in Fig. 23.

Similar or functionally equivalent elements are designated by the same reference symbols in each of the Figures.

A plant for spraying paint on vehicle bodies 102 which bears the general reference 100 and is illustrated in Figs. 1 to 19 comprises a purely schematically illustrated conveyor arrangement 104 by means of which the vehicle bodies 102 can be moved along in the direction of the conveyor 106 through an application area 108 of a painting booth bearing the general reference 110.

The application area 108 is the interior of the painting booth 110 which is bounded, in a horizontal transverse . direction 112 running perpendicularly to the direction of the conveyor 106 that corresponds to the longitudinal direction of the painting booth 110, on both sides of the conveyor arrangement 104 by a respective booth wall 114.

Spraying devices 116, which are in the form of painting robots for example, are arranged on both sides of the conveyor arrangement 104 in the painting booth 110.

An air flow 1s produced by means of the air circulating in an (only partially illustrated) continuous loop, and this passes downwardly through the application area 108 in a substantially vertically direction from above, as is indicated in Fig. 3 by the arrows 118.

This air flow picks up paint overspray in the form of overspray particles in the application area 108. Herein, the term "particle" comprises both solid and liquid particles and in particular, droplets.

When using a wet painting process, the wet paint overspray consists of paint droplets. The largest dimension of most of the overspray particles lies within a range of approximately 1 um to approximately 100 um

The exhaust air stream loaded with the overspray particles from the application area 108 is referred to hereinafter as the stream of crude gas. The direction of flow of the stream of crude gas is illustrated in Figs. 3 and 10 by the arrows 120.

The stream of crude gas leaves the painting booth 110 in the downward direction and enters an arrangement bearing the general reference 126 which is used for separating wet paint overspray from the stream of crude gas and 1s arranged below the application area 108.

The arrangement 126 comprises a substantially parallelepipedal flow chamber 128 which extends over the entire length of the painting booth 110 in the conveyor direction 106 and is bounded in the transverse direction 112 by vertical side walls 130 which are substantially flush with the lateral booth walls 114 of the painting booth 110 so that the flow chamber 128 is of substantially the same horizontal cross-sectional area as the painting booth 110 and is arranged substantially entirely within the vertical projection of the surface area of the painting booth 110.

As can best be perceived from Fig. 6, several, three for example, filter modules 132 are arranged on each of the two sides of the flow chamber 128, these forming two rows of modules 136 which extend in the longitudinal direction 134 (which coincides with the conveyor direction 106) of the arrangement 126 for separating wet paint overspray.

Each of the rows of modules 136 comprises two corner modules 138 which respectively form one end of a row of modules 136, and at least one central module 140 which is arranged between two neighbouring filter modules 132.

In order to prevent longitudinal currents of the stream of crude gas in the longitudinal direction 134 of the flow chamber 128 and also to prevent the crude gas from flowing between the individual filter modules 132, provision may be made for vertical transverse partitioning walls 142 which extend in the transverse direction 112 and which are respectively arranged between two filter modules 132 that succeed one another in the longitudinal direction 134 and subdivide the flow chamber 128 into flow chamber sections 144 that succeed one another in the longitudinal direction 134.

Due to these transverse partitioning walls 142, it is possible to establish an adjustment of the stream of crude gas flowing through each individual filter module 132 independently of that for the stream of crude gas flowing through the other filter modules 132.

As can best be perceived from Fig. 2, a walkway 146 which is accessible to a service operator is provided between the two rows of modules 136.

In order to enable the sections of the walkway 146, which are arranged successively in the flow chamber sections 144, to be continuously accessible, passage doors 148 are provided in the transverse partitioning walls 142 (Fig. 6).

The end walls 150 of the flow chamber 128 which respectively close the flow chamber 128 at the front end and the rear end thereof are provided with access doors 152 through which a service operator can enter the flow chamber 128 from the exterior.

Each of the filter modules 132 is in the form of a pre- assembled unit 154 which is manufactured at a point remote from the position in the paint shop where it will be mounted and 1s transported as a unitary item to its mounting position in the paint shop. At the mounting position thereof, the pre-assembled unit 154 is arranged in its envisaged working position and connected to one or more neighbouring pre-assembled units 154 or to the transverse partiticning walls 142 arranged therebetween and also to a supporting structure for the application area 108.

In the following description, the construction of a filter module 132 will be described with reference to Figs. 7 and 9 to 16 using the example of a central module 140:

The module comprises a supporting structure 156 consisting of two vertical rear supports 158 and two vertical front supports 160 which are respectively connected at their upper ends by horizontal tie bars 162 to a respective one of the rear supports 158 (Fig. 7).

Furthermore, the front supports 160 are connected together at their upper ends by means of a further (not shown) tie bar.

In addition, the rear supports 158 are connected together by means of (not shown) tie bars or by means of a (not shown) connecting framework.

The tie bars at the upper end of the support structure 156 carry a horizontal covering wall 164.

A vertical front wall 166 of the filter module 132 is held on the front faces of the front supports 160.

The covering wall 164 and the front wall 166 form partition walls 168 of the filter module 132 which separate a filter element accommodating chamber 170 that is arranged within the filter module 132 from the region of the flow chamber 128 located outside the filter module 132.

In the filter element accommodating chamber 170 of the filter module 132, a plurality of, for example ten, filter elements 172 are arranged one above the other in two rows which project in the horizontal direction from a common base body 174 that is held on the rear surfaces of the rear supports 158.

The filter elements 172 can, for example, be formed from plates consisting of sintered polyethylene which are provided on their outer surfaces with a membrane of polytetrafluorethylene (PTFE).

The coating of PTFE serves to increase the filter grade of the filter elements 172 (i.e. to reduce their permeability) and furthermore, to prevent permanent adherence of the wet paint overspray that has been separated from the stream of crude gas.

Both the base material of the filter elements 172 and the

PTFE coating thereon exhibit porosity so that the crude gas can enter into the interior of the respective filter element 172 through the pores.

Furthermore, in order to prevent the filter surfaces from clogging, they are provided with a barrier layer consisting of an auxiliary material that is delivered in the stream of crude gas. This preferably particle-like auxiliary material is also usually referred to as a "precoat" material.

When the arrangement 126 is operative, the barrier layer is formed by the deposition of the auxiliary material being delivered by the stream of crude gas 120 onto the filter surfaces, and it prevents the filter surfaces from clogging as a result of the wet paint overspray adhering thereto. :

Aiding material from the stream of crude gas 120 is also deposited on the inner surfaces of the covering wall 164 and the front wall 166 of the filter module 132 where it likewise prevents the wet paint overspray from adhering thereto.

In principle, any medium which is capable of being absorbed as a fluidic component of the wet paint overspray can be used as the auxiliary material.

In particular for example, lime, rock meal, aluminium silicates, aluminium oxides, silicon oxides, coating powder or the like come into consideration as auxiliary materials.

As an alternative or in addition thereto, particles having a cavity-like structure and having a large internal surface area relative to their external dimensions, such as zeolites or other hollow, for example, spherical bodies consisting of polymers, glass or aluminium silicate and/or natural or synthetically produced fibres for example can also be used as auxiliary materials for absorption of and/or bonding with the overspray.

As an alternative or in addition thereto, particles which are chemically reactive with the overspray such as chemically reactive particles from the amine-, epoxide-, carboxyl-, hydroxyl- or isocyanate groups, chemically . reactive particles consisting of aluminium oxide post- treated with octyl silane or solid or liquid monomers, oligomers or polymers, silanes, silanols or siloxanes .for example can also be used as auxiliary materials for absorption of and/or bonding with the overspray.

The auxiliary material preferably consists of a plurality of particulate auxiliary materials having an average diameter within a range of approximately 10 um to approximately 100 um for example.

In order to enable the auxiliary material to be supplied to the stream of crude gas without any danger of the auxiliary material reaching the application area 108 of the paint shop 100, provision is made for each filter module 132 to have an auxiliary material reservoir 176 which is held on the support structure 156 and has a funnel-like shape in the form of an inverted frustum of a pyramid for example (Fig. 13).

The four trapezoidal side walls 178 of the auxiliary material reservoir 176 are inclined at an angle of at least approximately 60° to the vertical.

The height of the auxiliary material reservoir 176 amounts to approximately 1.1 m for example.

The upper edges of the side walls 178 surround an entrance opening i180 of the auxiliary material reservoir 176 through which the stream of crude gas 120 loaded with the overspray i ' : i 26 can enter the auxiliary material reservoir 176 and then escape therefrom. }

The substantially horizontally aligned base 182 is in the form of a porous fluid base 184 through which a gaseous medium, and in particular, compressed air is arranged to be flushed in order to fluidise the auxiliary material arranged in the interior 186 of the auxiliary material reservoir 176 and to equalize locally differing levels of the auxiliary material within the auxiliary material reservoir 176.

When the plant 100 is operative, the fluid base is put into service on an intermittent basis, for example, three times per minute for approximately two seconds on each occasion.

In order to prevent the fluid base 184 from being damaged by larger falling objects, a collecting or retention grating 187 is arranged above the fluid base 184 at a distance of 20 cm therefrom for example, wherein said grating extends in the horizontal direction over the entire cross section of the interior 186 of the auxiliary material reservoir 176 and comprises a multiplicity of rows of honeycomb or rectangular through openings 189 for allowing the auxiliary material to pass through the retention grating 187. The through openings are arranged such as to be mutually displaced from row to row and the dimensions thereof are approximately 30 mm x 30 mm for example (Fig. 16).

In order to enable access to be made to the interior 186 of the auxiliary material reservoir 176 for maintenance purposes, one of the side walls 178 is provided with an inspection opening which is closed in operation of the filter module 132 by an inspection door 188 having a handle 190 (see Figs. 13 to 15).

As can be perceived from Fig. 15, the inspection door 188 is held in releasable manner by means of clamps 192 with wing nuts 194 on the associated side wall 178 of the auxiliary material reservoir 176. ' A compressed air pipeline 196 which is held on the inspection door 188 leads to a whirling device 198 (Fig. 14).

The whirling device 198 serves to inject compressed air in pulsating manner into the auxiliary material located therebelow in order to whirl up this auxiliary material and thereby introduce it into the stream of crude gas that is passing through the auxiliary material reservoir 176.

Moreover, due to this process of whirling up the auxiliary material by means of the whirling device 198, the effect 1s achieved that the mixture of auxiliary material and the overspray that is bound thereto which is present in the auxiliary material reservoir 176 is homogenized.

When the plant 100 is operative, the whirling device 198 1s put 1nto service intermittently, for example, four times per minute for approximately 5 seconds on each occasion.

The whirling device 198 comprises several, two for example, cutlet nozzles 200 for supplying compressed air which are in the form of cone jets each of which can produce a downwardly directed cone of compressed air that widens out towards the base 182 of the auxiliary material reservoir 176.

Preferably, the outlet nozzles 200 are formed and arranged in such a way that, taken together, the compressed air cones produced by the outlet nozzles 200 completely cover the floor area of the auxiliary material reservoir 176.

Furthermore, a mounting means 202 for a level sensor 204 is arranged on the compressed air pipeline 196, said sensor comprising a rod-shaped sensor element 206 and a sensor housing 208 having the sensor electronics accommodated therein (Fig. 14).

The level sensor 204 is in the form of an analogue, in particular capacitive, sensor and serves to produce a signal which corresponds in each case to a value obtained from a multiplicity of discrete fill height levels or from a continuum of fill height levels in order to enable the level of the auxiliary material in the auxiliary material reservoir 176 to be determined as accurately as possible.

The rod-shaped sensor element 206 of the level sensor 204 is directed substantially vertically and is arranged in the proximity of the centre of the interior 186 of the auxiliary material reservoir 176 as far away as possible from the side walls 178 of the auxiliary material reservoir 176 in order to ensure that the result of the measurement of the level sensor 204 is impaired as little as possible by edge effects (Fig. 13).

. i

The rod-shaped sensor element 206 of the level sensor 204 is oriented substantially perpendicularly to the horizontal base 182 of the auxiliary material reservoir 176.

The signal produced by the level sensor 204 is conveyed via a (not shown) signal line to an electrical connection box 209 of the filter module 132 which is arranged on the base body 174 of the filter elements 172 (see Fig. 7), and from there, it is conveyed to a control unit of the plant 100 which is schematically illustrated in Fig. 19 and designated by 210 therein.

Furthermore, in order to properly direct the stream of crude gas entering the filter module 132 into the interior 186 of the auxiliary material reservoir 176 and so as to prevent the stream of crude gas coming from the flow chamber 128 having direct access to the filter elements 172, each filter module 132 is provided with a slit-like inlet opening 212 which is in the form of an inlet channel 214 the through-flow cross section of which narrows in the direction of flow of the stream of crude gas towards a narrow section 240 such as can be perceived particularly in

Fig. 9 for example.

As an alternative or in addition thereto, provision may also be made for the inlet channel 214 to comprise a through-flow cross section which widens out in the direction of flow of the stream of crude gas away from a narrow section 240.

The inlet channel 214 is bounded downwardly by a sloping intake member 216 which extends in an upwardly sloping direction from the front supports 160 of the support structure 156 and is inclined at an angle of approximately 40° to approximately 65° with respect to the horizontal for : example, and by a lower guide plate 218 which is adjacent to the lower end of the sloping intake member 216 but is inclined by a greater amount to the horizontal than the : slopping intake member 216, at an angle of from approximately 55° to approximately 70° for example, said lower guide plate protruding beyond an upper, substantially i vertically directed section 220 of a side wall 178 of the auxiliary material reservoir 176 and projecting into the interior 186 of the auxiliary material reservoir 176.

In this way, the lower guide plate 218 functions as a retention element 222 which keeps the auxiliary material from the auxiliary material reservoir 176 away from the inlet opening 212 and prevents whirled-up auxiliary material from escaping from the auxiliary material reservoir 176 along the side wall 178 to the side of the inlet opening 212.

Moreover, the lower guide plate 218 prevents the stream of crude gas from breaking-away after passing the sloping intake member 216 and ensures that the stream of crude gas is directed properly into the auxiliary material reservoir 176.

The lower guide plate 218 has a depth (i.e. its extent in the direction of flow of the stream of crude gas) of approximately 100 mm for example.

The sloping intake member 216 and the lower guide plate 218 extend in the longitudinal direction 134 of the flow chamber 128 over substantially the entire length of the inlet opening 212 of approximately 1 m to approximately 2 m for example, this virtually corresponding to the extent of the entire filter module 132 in the longitudinal direction 134.

The upper surface of the sloping intake member 216 and the upper surface of the lower guide plate 218 together form a lower guide surface 224 for the inlet opening 212 which delimits the inlet opening 212 in the downward direction and its upper section 226, which is formed by the sloping intake member 216, has an inclination of approximately 40° to approximately 65° with respect to the horizontal whilst its lower section 228, which is formed by the lower guide plate 218, has a greater inclination to the horizontal of from approximately 55° to approximately 70°.

In the upward direction, the inlet opening 212 is delimited by the lower edge of the front wall 166 and by an upper guide plate 230 which protrudes from the lower edge of the front wall 166 and slopes downwardly into the interior of the filter module 132.

In like manner to the lower guide plate 218, the upper guide plate 230 is inclined to the horizontal at an angle of approximately 55° to approximately 70° for example, and it extends in the longitudinal direction 134 over substantially the entire width of the inlet opening 212 of 1 mor 2 m for example.

The upper guide plate 230 has a depth (i.e. an extent in the direction of flow of the stream of crude gas) of approximately 150 mm for example.

The lower side of the upper guide plate 230 forms an upper guide surface 232 which delimits the inlet opening 212 in the upward direction and is inclined to the horizontal at an angle of approximately 55° to approximately 70° for example. .

Due to this upper guide surface 232 for the stream of crude gas, the effect 1s achieved that the stream of crude gas does not break away at the front wall 166 of the filter : module 132, but rather, it is guided directly into the auxiliary material reservoir 176.

Furthermore, the upper guide plate 230 serves as a filter shielding element 234, since it is arranged at the inlet opening 212 and is formed in such a way that it prevents the crude gas entering the filter module 132 from flowing directly to the filter elements 172.

Furthermore, the upper guide plate 230 serves as a deflecting element 236 which keeps the material cleansed off the filter elements 172 away from the inlet opening 212, said material consisting of auxiliary material and overspray particles that are bound to the auxiliary material.

Moreover, material falling from the filter elements 172 onto the upper surface of the upper guide plate 230 1s diverted into the auxiliary material reservoir 176 due to the inclined positioning of the upper guide plate 230. :

In operation of the filter module 132, both the upper guide surface 232 and the upper surface of the upper guide plate 230 are provided with a coating of the auxiliary material so that these surfaces of the upper guide plate 230 are easy to clean and overspray cannot adhere directly to the upper guide plate 230.

Furthermore, as can best be perceived from Fig. 12, the filter module 132 comprises two cover elements 238 which are approximately in the form of triangular covering plates and which cover the left and the right lower corner regions of the inlet opening 212 in such a way that auxiliary material and overspray from the stream of crude gas are kept away from these corner regions of the inlet opening 212 so that depositions of auxiliary material and of overspray particles in these corner regions and also outside the filter module 132 on the sloping intake member 216 are prevented.

The upper surfaces of the cover elements 238 are oriented such as to be inclined to the vertical and also inclined to the horizontal and they each exhibit a surface-normal which is directed upwardly into the space outside the filter module 132.

Due to the previously described design for the geometry of the inlet opening 212, the effect is achieved that the inlet opening 212 comprises a narrow section 240 at which the through-flow cross section of the inlet opening 212 is at its smallest and the speed of the crude gas is therefore at 1ts greatest.

Preferably, the speed of the crude gas in the narrow section amounts to from approximately 2 m/s to approximately 8 m/s, and in particular, from approximately 3 m/s to approximately 5 m/s.

In this way, auxiliary material from the interior of the filter module 132, which forms a closed box, is effectively prevented from entering the flow chamber 128 and from there, entering the application area 108. In consequence, the process of whirling up the auxiliary material in the auxiliary material reservoir 176 and the cleansing of the filter elements 172 can take place at any desired point in time without having to interrupt the supply of crude gas to the filter module 132 or even the operation of the paint spraying devices 116 in the application area 108.

Furthermore, due to the fact that the stream of crude gas emerges from the inlet opening 212 such that it is directed into the auxiliary material reservoir 176, it is thereby ensured that deflection of the stream of crude gas in the interior 186 of the auxiliary material reservoir 176 will take place. In consequence, an adequate quantity otf auxiliary material, which is produced by the process of whirling up the product in the auxiliary material reservoir 176, is carried along by the stream of crude gas.

The stream of crude gas from the flow chamber 128 through the inlet opening 212 into the interior of the filter module 132 1s illustrated in Fig. 10 as the result of a i

CL

£.9041/00997 flow simulation. From this, it can clearly be seen that a rolling flow, the horizontally extending axis of which lies somewhat lower than the upper edge of the auxiliary material reservoir 176, is formed in the interior of the filter module 132. :

At the side of the auxiliary material reservoir 176 opposite the inlet opening 212, the stream of crude gas, which is now loaded with auxiliary material, flows out of the auxiliary material reservoir 176 and is then distributed through the entire volume of the filter element accommodating chamber 170 so that turbulence occurs around the filter elements 172 and, due to the high energy which the stream of crude gas has received in the narrow section . 240, a homogeneous distribution of the auxiliary material on the individual filter elements 172 is ensured.

Since there are hardly any components of the filter module 132 in the flow path of the incoming stream of crude gas, contamination of such components due to the adherence of paint 1s prevented but nevertheless there is a flow through the filter elements 172 which is advantageous to the filtration process.

Due to the fact that the average direction of flow of the stream of crude gas entering the filter module 132 through the narrow section 240 1s inclined to the horizontal at an angle of more than 40°, an air lock, which would lead to material that has been removed from the filter elements 172 being immediately sent back again to these filter elements 172 and which could alsc lead to the formation of mutually opposed air vortices within the filter module 132, is prevented from forming in the lower region of the filter element accommodating chamber 170.

In order to enable two filter modules 132 that are arranged next to each other in a row of modules 136 to be connected together in a simple and stable manner or to enable a filter module 132 to be connected to an adjacent transverse partitioning wall 142, the support structure 156 of each filter module 132 includes at least one rear support 158 which comprises a vertical, substantially flat contact surface 242 that is oriented in the transverse direction 112 and can be placed against a corresponding contact surface 242 of a neighbouring filter module 132 or on a neighbouring transverse partitioning wall 142 (Fig. 7).

Furthermore, through openings 244 are provided in the contact surface 242 for the passage of fixing means with the aid of which the rear support 158 serving as a connecting element 246 is connectable to a connecting element 246 of a neighbouring filter module 132 or to a neighbouring transverse partitioning wall 142.

The rear support 158 serving as a connecting element 246 preferably has an approximately U-shaped profile.

As can be perceived from Fig. 7, each central module 140 comprises two rear supports 158 having U-shaped profiles which serve as connecting elements 246 and the open sides thereof face each other so that the central module 140 is connectable on both sides to an adjacent further filter module 132 or to a transverse partitioning wall 142.

! i . : i 37

As can be perceived from Fig. 8, each corner module 138 comprises only one rear support 158 having a U-shaped profile which is in the form of a connecting element 246; the opposite rear support 158a, which is to be connected to neither a neighbouring filter module 132 nor to a neighbouring transverse partitioning wall 142, can, for example, have a T-shaped profile instead of a U-shaped profile for the purposes of increasing its mechanical rigidity.

In all other respects, the corner module 138 agrees in regard to the construction and functioning thereof with the central modules 140 that have been described in detail hereinabove.

In the operative state of each filter module 132, the stream of crude gas 120 sweeps over the filter surfaces of the filter elements 172, whereby both the auxiliary material and the wet paint overspray being carried along thereby are deposited on the filter surfaces, and the filtered crude gas enters the interiors of the filter elements 172 through the porous filter surfaces in the form of a stream of exhaust air, these interiors being connected to a cavity within the base body 174 from which the filter elements 172 project. From this cavity, the stream of cleansed exhaust air enters a respective exhaust air pipe 248 which leads from the base body 174 of the filter elements 172 of each filter module 132 to an exhaust air duct 250 that is arranged approximately centrally under the flow chamber 128 and runs parallel to the longitudinal direction 134 of the flow chamber 128 (see in particular,

Figs. 2 and 3).

As can be perceived from the schematic 1llustration of Fig. 19, the exhaust air that has been cleansed of wet paint overspray passes from the exhaust air duct 250 tc an exhaust air fan 252, and from there, the cleansed exhaust air 1s supplied via a (not shown) cooling stack and a (not shown) supply line of a (not shown) air chamber, the so- called plenum, which is arranged above the application area 108. , From this air chamber, the cleansed exhaust air re-enters the application area 108 via a filter cover.

A (not shown) exhaust air duct, through which a portion of the cleansed exhaust air stream is conveyed to the environment (through a chimney for example), branches off from the supply line.

That part of the exhaust air stream that has been conveyed away to the environment is replaced by fresh air which is fed into the flow chamber 128 via two air curtain producing devices 254 that are connected via a respective supply line 256 to a (not shown) air supply system (Figs. 1 to 3).

Each of the air curtain producing devices 254 comprises a respective alr supply chamber which extends in the longitudinal direction 134 of the flow chamber 128 and is fed with a supply of air via the supply line 256, said chamber opening out through a gap 258, which extends in the longitudinal direction 134 whilst the extent thereof in the vertical direction lies in a range of approximately 15 cm to approximately 50 cm for example, into an upper section

E-2011/009097 260 of the flow chamber 128 which is delimited in the upward direction by the application area 108 and by the covering walls 164 of the filter modules 132 in the downward direction.

The gap 258 of each air supply chamber is arranged just above the covering walls 164 of the filter modules 132 so that an air curtain will be formed on the upper surface of the filter modules 132 by the inflow of air, which is being supplied from the air supply chambers, into the flow chamber 128 in a substantially horizontal direction along the upper surfaces of the covering walls 164 of the filter modules 132, said air curtain being directed away from the respective air curtain producing arrangement 254 associated therewith towards a narrow section 262 between the upper edges of the mutually opposed rows of modules 136 and this thereby preventing the stream of crude gas 120, which is loaded with wet paint overspray and is coming from the application area 108, from reaching the upper surface of the filter modules 132 and hence preventing the wet paint overspray from settling out of the stream of crude gas 120 onto the upper surface of the filter modules 132.

The horizontal cross section of the flow chamber 128 through which the stream of crude gas 1s adapted to flow decreases suddenly in the narrow section 262 of the flow chamber 128 so that the flow rate of the stream of crude gas is significantly higher in the lower section 263 of the flow chamber 128 located underneath the narrow section 262 than it is in the upper section 260 of the flow chamber 128 located above the narrow section 262. !

J l

The average direction of flow of the air in the transverse air curtains on the upper surface of the filter modules 132 which are produced by the air curtain producing devices 254 1s illustrated in Fig. 3 by means of the arrows 264.

The greater part of the air being passed through the application area 108 1s thus re-circulated around a continuous air loop which comprises the application area 108, the flow chamber 128, the filter modules 132, the exhaust air pipes 248, the exhaust air duct 250, the exhaust air fans 252 as well as the supply line and the air chamber above the application area 108, this thereby preventing the air that is being fed around the continuous air loop from being constantly heated by the influx of fresh air via the air curtain producing devices 254.

Since the separation of the wet paint overspray from the stream of crude gas 120 by means of the filter elements 172 is effected by means of a dry process, i.e. it is not washed out with the aid of a cleaning fluid, the air being fed around the continuous air loop is not moistened during the process of separating out the wet paint overspray so that no devices whatsoever are required for dehumidifying the air being fed around the continuous air loop.

Furthermore, devices for the separation of wet paint overspray from a washing and cleaning fluid are also not necessary.

Due to the fact that the horizontal cross section cf the flow chamber 128 through which the stream of crude gas is adapted to flow 1s significantly smaller in the lower section 263 of the flow chamber 128 lying underneath the narrow section 262 due to the presence of the filter modules 132 than it is in the upper section 260 of the flow chamber 128 (for example, in the lower section 263, it amounts to only approximately 35 % to approximately 50 % of the horizontal cross-sectional area of the flow chamber 128 in the upper section 260 thereof), the flow rate of the stream of crude gas 1s continuously increased on its way from the application area 108 through the flow chamber 128 up to the inlet openings 212 of the filter modules 132 thereby resulting in the stream of crude gas having a rising speed profile.

This rising speed profile has the consequence that particles emerging from the filter modules 132 cannot reach the application area 108.

Hereby, the speed of the stream of crude gas within the application area 108 and in the upper section 260 of the flow chamber 128 amounts to up to approximately 0.6 m/s for example, whereas in the lower section 263 of the flow chamber for example it lies within a range of approximately 0.6 m/s to approximately 3 m/s and rises up to a maximum value within a range of approximately 3 m/s to approximately 5 m/s in the inlet openings 212 of the filter modules 132.

Due to the fact that the filter elements 172 are completely housed within the filter modules 132, it is possible for the filter elements 172 to be activated by the application of the auxiliary material and for the filter elements 172 to be cleansed at any time during the current painting process in the application area 108.

If the width of the painting booth 110, i.e. its extent in the transverse direction 112, changes, then equally large filter modules 132 are used nonetheless; the arrangement 126 for separating wet paint overspray is in this case adapted by merely increasing the distance of the two rows of modules 136 from each other and by widening the walkway 146.

The speed profile of the stream of crude gas in the event of such a widening of the painting booth 110 thus changes only in the area up to the walkway 146; from here, i.e. when passing the inlet openings 212 of the filter modules 132 in particular, the speed profile of the stream of crude gas is only dependent on the quantity of crude gas passing through per unit of time, but not however, on the geometry of the flow chamber 128.

The spacing of the (accessible) covering walls 164 of the filter modules 132 from the lower edge of the vehicle bodies 102 being conveyed through the painting booth 110 amounts to at least approximately 1.5 m for reasons of maintenance.

The filter elements 172 are cleansed by blasts of compressed air at certain time intervals when their loading with wet paint overspray and auxiliary material has reached a given value. !

This cleansing action can take place (in dependence on the rise in pressure loss at the filter elements 172) once to six times per 8-hour working shift, i.e. approximately every 1 to 8 hours for example.

The requisite blasts of compressed air are produced by means of a pulse-~emitting unit 266 which 1s arranged on the base body 174 of the filter elements 172 of each filter module 132, whereby the pulse-emitting unit 266 is capable of delivering blasts of compressed air to compressed air tubes which run within the respective base body 174 and lead from the pulse-emitting unit 266 into the interiors of the filter elements 172 (Fig. 19).

From the interiors of the filter elements 172, the blasts of compressed air pass through the porous filter surfaces into the filter element accommodating chamber 170, whereby the barrier layer of auxiliary material and the wet paint overspray deposited thereon which is formed on the filter surfaces is removed from the filter surfaces so that these filter surfaces revert to their cleansed original condition.

The pulse-emitting unit 266 comprises a pulse-emitting valve 268 via which compressed air from a compressed air supply line 270, which is fed by a compressor 272, is adapted to be supplied to the pulse-emitting unit 266, (see

Fig. 19).

The compressed air pipeline 196, which leads to the outlet nozzles 200 of the whirling device 198, is also attached via a compressed air valve 274 to this compressed air supply line 270.

Furthermore, the fluid base 184 of each auxiliary material reservoir 176 is also attached via an air supply line 278 provided with a compressed air valve 276 to the compressed air supply line 270.

By opening the pulse-~emitting valve 268, the compressed air valve 274 or the compressed air valve 276 in either alternating manner or at the same time, a cleansing process for the filter elements 172, whirling-up of the auxiliary material in the auxiliary material reservoirs 176 and fluidisation of the auxiliary material in the auxiliary material reservoir 176 by means of the fluid base 184, respectively, can thus be initiated.

A non-return valve 280, which is controllable by the control unit 210 in the local control position, is arranged in the compressed air supply line 270 between the abovementioned compressed air valves and the compressor 272.

The control unit 210 blocks the supply of compressed air from the compressor 272 to the abovementioned compressed alr consuming units of a filter module 132 or of all the filter modules 132 by closing the non-return valve 280 if it determines that there is an inadequate flow of crude gas through the filter elements 172.

In order to determine whether there is an adequate flow of crude gas through the filter elements 172, provision may be made for the control unit 210 to monitor the operative state of the exhaust air fans 252 for example.

This process of monitoring the operative state of the exhaust air fans 252 can be effected by means of a ) differential pressure gauge (PDIA) 282 which measures the drop in pressure between the pressure side and the suction side of the exhaust air fans 252 for example.

As an alternative or in addition thereto, the operative state of the exhaust air fans 252 could also be monitored by the control unit 210 by means of a current monitoring instrument (ESA) 284 and/or by means of a frequency converter (SC) 286.

Furthermore, provision may be made for the lack of an adequate flow of crude gas through the filter elements 172 to be determined by means of a volumetric flow meter (FIA) 288 which measures the flow of gas through the exhaust air duct 250 or through one or more of the exhaust air pipes 248.

Furthermore, it is possible to determine whether there is a lack of an adequate flow of crude gas through the filter elements 172 by measuring the drop in pressure across the filter elements 172 in one filter module 132 or in all of the filter modules 132.

If, due to the signals transmitted thereto by the differential pressure gauge 282, the current monitoring instrument 284, the frequency converter 286 and/or the volumetric flow meter 288, the control unit 210 determines that the flow of crude gas through the filter elements 172 lies below a given threshold value, then the supply of compressed air to at least one of the filter modules 132 is blocked by the closure of the non-return valve 280.

It is 1n this way that auxiliary material is prevented from entering the flow path of the crude gas and, in particular, : is prevented from entering the flow chamber 128 through the inlet opening 212 of a filter module 132 and from said chamber reaching the application area 108 as a result of a whirling process effected by means of the whirling device 198, or due to cleansing of the filter elements 172 or due ~ to the fluidising of the auxiliary material stored in the auxiliary material reservoir 176.

This blockage of the compressed air supply can be effected ! for all of the filter modules 132 together or separately for each of the individual filter modules 132. In the latter case, the process of determining lack of an adequate } flow of crude gas through the filter elements 172 is effected separately for each of the filter modules 132, and either each filter module 132 is provided with its own compressor 272 or the compressed air supply lines 270 to the individual filter modules 132 are adapted to be blocked or opened individually by means of non-return valves 280 which are controllable independently of one another.

In the previously described arrangement 126 for separating wet paint overspray, the auxiliary material is introduced into the stream of crude gas exclusively within the filter modules 132 by whirling up the auxiliary material in the respective auxiliary material reservoir 176.

In order to be able to supply fresh auxiliary material to the auxiliary material reservoirs 176 that are rigidly mounted in their working positions within the filter modules 132, the arrangement 126 for separating wet paint overspray comprises an auxiliary material supply arrangement 290 which is schematically illustrated in Fig. 17 and which comprises a storage tank 292 that may be constructed in the form of a blowpot or a simple fluidisation tank.

Blowpots themselves are known from JP 02123025 A or JP 06278868 A for example and until now they were used in coating plants for conveying coating powders to the application tanks located in the proximity of the atomizers. They are relatively small closable containers having an air-permeable base through which air is passed for the purposes of fluidising the powder and transporting it to the tank.

Whilst a blowpot can be emptied by the pressure of the fluidising air, a powder dosing pump 293 such as the so- called DDF pump described in WO 03/024612 Al for example is otherwise connected to the outlet side of the fluidisation container for the purposes of conveying the material (see

Fig. 1), or else use is made of some other form of dosing pump which produces a conveying action in accord with the dense flow principle using alternating suction/pressure such as is known from EP 1 427 536 Bl, WO 2004/087331 Al or the one depicted in Fig. 3 of DE 101 30 173 Al for example.

For the purposes of filling the storage tank 292, there is arranged above it a larger storage vessel (a packing drum or "big bag") 294 for the fresh auxiliary material from which, in the simplest case, the material can trickle into the storage tank (silo) 292 through an opening which 1s arranged to be closed by a flap. However, in order to continuously refill the storage tank 292 even during the process of conveying the material and to avoid time delays in operation, a mechanical conveyer system 296 such as a cellular-wheel sluice or a conveyer worm for example, is preferably arranged between the storage vessel 294 and the storage tank 292. When employing such a conveyer system, 1t can also be advantageous to specify a desirable amount for each charge, in the case of a cellular-wheel sluice, the previously determined amount by which each cell is filled.

The storage tank 292 is connected to each of the auxiliary material reservoirs 176 by a main line 300 which branches out into two branches 298a, 298b from which stub lines 302 extend to a respective one of the auxiliary material reservoirs 176. Each of the branches 298a, 298b of the main line 300 leads to the auxiliary material reservoirs 176 of a respective row of modules 136.

The main line 300 preferably consists of flexible hoses.

Hoses having an internal diameter of up to approximately 14 mm and in particular, from approximately 6 mm to approximately 12 mm can be used for this purpose.

The stub lines 302 can be tubular and are each provided with a mechanical pinch valve 304, whereby, in each case, a second pinch valve 306 is arranged, in the direction of : flow of the auxiliary material, beyond the point where the respective stub line 302 branches off.

Further pinch valves 309 are arranged at the junction between the two branches 298a, 298b and the main line 300 in order to enable these two branches 298a, 298b to be opened or closed as required.

In operation of the auxiliary material feeding arrangement 290, the main line 300 and each one of the stub lines 302 are initially empty. If a certain auxiliary material reservoir 176 is to be charged with fresh auxiliary material, the main line beyond the branching-point of the associated stub line 302 is blocked by closing the respectively associated pinch valve 306, the pertinent stub line 302 is opened by opening the associated pinch valve 304 and the auxiliary material is subsequently conveyed from the storage tank 292 to the pertinent auxiliary material reservoir 176.

Subsequently, the previously described transportation path to the pertinent auxiliary material reservoir 176 is emptied and flushed. This has the advantage that the size of the charge is always precisely determined and is capable of being dosed, and in addition, the transportation path cannot be blocked since a process of flushing it into the charged auxiliary material reservoir 176 is always effected.

Each of the stub lines 302 opens out into one of the side walls 178 of the respectively associated auxiliary material reservoir 176, preferably at a point near the upper edge of the auxiliary material reservoir 176 so that as large a quantity of the auxiliary material as possible can be supplied through the stub line 302.

That stub line 302 which leads to the last auxiliary material reservoir 176 of a row of modules 136 does not require a pinch valve arrangement since simply all of the pinch valves 306 and 309 arranged in the main line 300 upstream of this auxiliary material reservoir 176 must be opened for the purposes of charging this last auxiliary material reservoir 176.

Instead of the previously described pinch valve devices, mechanical pinch switch points or other forms of powder switch points known from the state of the art can also be provided at the junctions of the auxiliary material line system.

Furthermore, in order to enable the auxiliary material mixed with overspray that has accumulated in an auxiliary material reservoir 176 to be removed and fed off to a disposal or recycling facility before supplying fresh auxiliary material to said auxiliary material reservoir 176, the arrangement 126 for separating wet paint overspray comprises an auxiliary material removal arrangement 308 which is schematically illustrated in Fig. 18.

For its part, the auxiliary material removal arrangement 308 comprises an extractor fan 310, a vacuum cleaner fan for example, which forces spent auxiliary material out of a main line 312 that branches out into two branches 3143, 314b, and into a collection tank 316 arranged below the extractor fan 310.

Fach one of the branches 314a, 314b of the main line 312 leads to the auxiliary material reservoirs 176 of a row of modules 136 and is attached to each of the auxiliary material reservoirs 176 of the pertinent row of modules 136 via a respective stub line 318 which is adapted to be closed by means of a pinch valve 320.

At the end of each branch 314a, 314b of the main line 312, there is a respective ball tap 322 through which, when i needed, air pressure is adapted to be supplied to the main : line 312 in order to facilitate the suction of the auxiliary material from the main line 312 to the suction fan 310.

The stub lines 318 open out into the interior 186 of the respective auxiliary material reservoir 176 just above the fluid base 184, preferably, in a corner area of the auxiliary material reservoir 176 where two of the side walls 178 meet together.

It is particularly expedient for the efficient removal of the spent auxiliary material from an auxiliary material reservoir 176 and for this removal process to be effected as completely as possible, if the stub line 318 branches out into two return pipes of which each opens into the interior 186 of the auxiliary material reservoir 176 at a differing corner.

i

If a certain auxiliary material reservoir 176 is to be emptied of spent auxiliary material mixed with overspray, then, for this purpose, the pinch valve 320 of the respectively associated stub line 318 is opened and the material present in the auxiliary material reservoir 176 is sucked out through the stub line 318 and the main line 312 by means of the suction fan 310 and passed to the } collection tank 316.

The suction process is terminated by the closure of the respectively associated pinch valve 320.

During the suction process, the fluid base 184 of the pertinent auxiliary material reservoir 176 is kept continually in operation, i.e. compressed air is passed through it during the whole of the suction process in order to fluidise the material and enhance its fluidity.

Furthermore, the process of sucking out the used material from the auxiliary material reservoir 176 can be assisted by operating the whirling device 198 of the pertinent auxiliary material reservoir 176 continuously or periodically (6 x 5 seconds per minute for example) during the suction process because the material is loosened up and moved towards the access openings of the stub line 318 due to the material requiring extraction being subjected to a stream of compressed air from above through the outlet nozzles 200 of the whirling device 198.

In the event that the process of separating the spent auxiliary material from one of the auxiliary material reservoirs 176 does not function in the proper manner, something which can be detected by the fact that the associated level sensor 204 is no longer indicating that the level is dropping, the operation of the arrangement 126 for separating wet paint overspray does not have to be interrupted. Rathermore, auxiliary material from another of the auxiliary material reservoirs 176 which is attached to the same branch 314a or 314b of the main line 312 can be sucked out instead. Thereby, the blocking on the transportation of the material from the blocked auxiliary material reservoir 176 can, in many instances, be overcome so that the material can be sucked out of the previously blocked auxiliary material reservoir 176 at a later time.

The material containing auxiliary material as well as overspray particles which is sucked out of the auxiliary material reservoir 176 can either be disposed of or at least be partly reused - if necessary after being reprocessed - in the coating plant.

Furthermore, provision may be made for the substances making up the auxiliary material to be selected in such a way that they can be exploited for purposes other than the coating of work pieces after they have been used in the coating plant. For example, the spent auxiliary material can be used as a structural material or it may be thermally treated and used, for example, in the brick industry or the cement industry or the like, whereby the wet paint overspray bonded to the auxiliary material can likewise be used as a source of energy in a combustion process necessary to the production process.

After the spent auxiliary material has been sucked out of an auxiliary material reservoir 176, the latter is filled with fresh auxiliary material by means of the auxiliary material feeding arrangement 290 that has already been described hereinabove, namely, for example, up to a primary fill-level of approximately 50 % of the entire capacity of the auxiliary material reservoir 176.

Due to the accumulation of wet paint overspray, which has a lower density than that of the auxiliary material, in the mixture consisting of auxiliary material and overspray present in the auxiliary material reservoir 176, the density of this mixture continually decreases in the operative state of a filter module 132 so that the barrier layer building up on the filter elements 172 of the filter module 132 has an ever increasing volume.

In consequence, the level of the material in the auxiliary material reservoir 176 also decreases continually immediately before the action of cleansing the filter elements 172.

At a given residual level which corresponds to approximately 10 % of the capacity of the auxiliary material reservoir 176 for example, the auxiliary material mixed with overspray is sucked out of the auxiliary material reservoir 176 as has been previously described.

Due to this suction process prior to the process of cleansing the filter elements 172, the effect is achieved that it is mainly the now unusable material which has collected in the auxiliary material reservoir 176 and has not formed the barrier layer on the filter elements 172 that is removed from the auxiliary material reservoir 176. =v As an alternative to this manner of proceeding, provision may also be made for the level of the material in the auxiliary material reservoir 176 to be measured in each case after the process of cleansing the filter elements 172 of the filter module 132, and a suction process is then initiated if a given maximum level of e.g. 90 % of the maximum capacity of the auxiliary material reservoir 176 is reached.

In every case, the level of the material in the auxiliary material reservoir 176 that triggers off a suction process is determined by means of the level sensor 204 which is arranged in the respective auxiliary material reservoir 176, .

A second embodiment of a plant 100 for painting vehicle bodies 102 which is illustrated in Fig. 20 in the form of a schematic cross section differs from the previously described first embodiment in that separate transverse air curtain guide plates 324, which serve to guide the air that has been supplied by the air curtain production devices 254 towards the narrow section 262 between the upper section 260 and the lower section 263 of the flow chamber 128, are arranged above the filter modules 132.

These transverse air curtain guide plates 324 are inclined with respect to the respectively neighbouring side wall 130 of the flow chamber 128 at an angle of e.g. approximately 1° to approximately 3° to the horizontal so that liquids landing on the transverse air curtain guide plates 324 from above will not flow off into the narrow section 262, but rather, towards the side walls 130.

It is ensured in this way for example that paint leaking out from the application area 108 due to a burst hose or fire-extinguishing water will not enter the lower section ) 263 of the flow chamber 128 and from there, reach the filter modules 132, but rather it will be able to flow off to the sides of the flow chamber 128.

In this embodiment furthermore, the walkway 146 between the rows of modules 136 is subdivided into two halves 328a, 328b which are formed substantially mirror-symmetrically with respect to a vertical longitudinal centre plane 326 of the flow chamber 128 and are inclined at an angle of e.g. approximately 1° to e.g. approximately 3° to the respective horizontals to the longitudinal centre plane 326 so that liquids landing on the walkway 146 from above, such as paint or fire-extinguishing water for example, will not spill over the lateral edges 330 of the walkway 146 into the inlet openings 212 of the filter modules 132, but rather, will be retained in the centre of the walkway 146.

In addition, both the walkway 146 and the transverse air curtain guide plates 324 may be inclined to the horizontal in the longitudinal direction 134 of the flow chamber 128 so that the liquids present on these elements can flow off into a drainage opening due to the force of gravity.

In all other respects, the second embodiment of a plant 100 for painting vehicle bodies 102 that is illustrated in Fig.

coincides in regard to the construction and functioning thereof with the first embodiment illustrated in Figs. 1 to 19 so that to this extent, reference may be made to the previous description.

As an alternative or in addition to the fluid base 184 illustrated in Fig. 13, the auxiliary material reservoirs 176 of the filter modules 132 in the previously described plants 100 for painting vehicle bodies 102 could also comprise other types of device 332 for mixing the material present in the auxiliary material reservoir 176, for example, a pneumatically operated agitating device 334 which is illustrated schematically in Figs. 21 and 22.

The pneumatically operated agitating device 334 comprises an agitator 336 having at least two agitator paddles 340 which are arranged in mutually non-rotational manner on a substantially vertically aligned agitator shaft 338 and an agitator turbine 342 which is illustrated in a purely schematic manner in Figs. 21 and 22 and by means of which the agitator shaft 338 is adapted to be set in rotary motion about its vertical axis.

The agitator paddles 340 are arranged on the agitator shaft 338 such as to be mutually displaced in the axial direction of the agitator shaft 338 with an angular displacement of approximately 180° for example.

Compressed air is adapted to be supplied to the agitator turbine 342 by way of a compressed air supply line 344.

When compressed air is supplied to the agitator turbine 342 via the compressed air supply line 344, the compressed air being supplied thereto sets the agitator turbine 342 into rotary motion about its vertical axis, whereupon the agitator shaft 338 that is connected to the agitator turbine 342 in mutually non-rotational manner is likewise set in motion.

The material present in the auxiliary material reservoir 176 is thereby mixed by the rotating agitator paddles 340 and the surface of the material located in the auxiliary material reservoir 176 is smoothed. Material bridges that have been formed in the auxiliary material reservoir 176 by an undermining process are broken up.

In this way, thorough mixing of the material in the auxiliary material reservoir 176 and evening-out of the level of the material within the auxiliary material reservoir 176 is obtained.

Due to the pneumatic drive for the agitating device 334, formation of sparks within the auxiliary material reservoir 176 is prevented and adequate protection against the risk of explosion 1s ensured.

An alternative embodiment of an arrangement 332 for mixing the material present in the auxiliary material reservoir 176 that is illustrated in Figs. 23 and 24 comprises an electric motor 346 which is arranged laterally beside the auxiliary material reservoir 176 whilst its drive shaft 348 is passed through a side wall 178 of the auxiliary material reservoir 176 and 1s provided with several, four for example, paddles 350 which are fixed to the drive shaft 348 and are arranged thereon such as to be mutually displaced in the axial direction of the drive shaft 348 and to have an angular displacement of approximately 90°.

The paddles 350 are set into rotary motion about their substantially horizontally aligned axes as a result of the rotation of the drive shaft 348 by means of the electric motor 346, whereby the paddles 350 mix the material present in the auxiliary material reservoir 176 whilst smoothing its surface and breaking up material bridges that have developed in the auxiliary material reservoir 176.

The conversion of a currently existing arrangement 126 for separating wet paint overspray from a stream of crude gas containing overspray particles can be effected in the following manner by using the filter modules 132 of the previously described plants 100:

Firstly, part of the existing arrangement is dismantled so that the space that would be occupied by a filter module 132 in its working position is exposed.

Subsequently, a filter module 132 is arranged in the working position that has been exposed in this manner and it 1s connected to the support structure for the application area 108 and in particular, to the booth walls 114 of the painting booth 110.

Subsequently, these steps are repeated until all of the filter modules 132 have been arranged in their working position and connected to the support structure for the application area 108. - In this way for example, an existing arrangement for separating wet paint overspray using a wet process can be replaced by the previously described, modularly constructed arrangement 126 for separating wet paint overspray using a dry process without any need to dismantle the application area 108 of the plant 100 for painting vehicle bodies 102 for this purpose.

The invention is not limited to the embodiment/s llustrated in the drawings. Accordingly it should be understood that where features mentioned in the appended claims are followed by reference numerals, such numerals are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.

Claims

J Claims

1. A filter device for separating wet paint overspray from a stream of crude gas (120) containing overspray particles, comprising at least one filter element (172) for separating the overspray from the stream of crude gas (120) and at least one auxiliary material reservoir (176) for accommodating an auxiliary filter material, wherein the filter device (132) comprises at least one inlet opening (212) through which the stream of crude gas (120) enters the filter device and at least one device (332) for mixing the material present in the at least one auxiliary material reservoir (176).

2. A filter device in accordance with Claim 1, wherein the device (332) for mixing the material present in the auxiliary material reservoir (176) comprises an agitating device (334) having an agitator shaft (338) and at least two agitator paddles (340), wherein the material present in the auxiliary material reservoir (176) 1s mixed by the rotating agitator paddles (340) when the agitator shaft (338) is set into rotary motion.

3. A filter device in accordance with Claim 2, wherein the agitator shaft (338) is aligned substantially horizontally and passed through a side wall (178) of the auxiliary material reservoir (176).

4. A filter device in accordance with either one of claims 2 and 3, wherein the device (332) for mixing the material present in the auxiliary material Sd reservoir (176) comprises a motor for setting the agitator shaft (338) into rotary motion.

5. A filter device in accordance with claim 4, wherein the motor is an electric motor (346) or a turbine (342).

6. An arrangement for separating wet paint overspray from a stream of crude gas (120) containing overspray particles, comprising at least one filter device (132) in accordance with any of the Claims 1 to 5 and a flow chamber (128) through which the stream of crude gas (120) flows from an application area (108) of a paint shop (100) to the inlet opening (212) of the at least one filter device (132).

7. A plant for painting articles comprising at least one application area (108) for the application of wet paint to the articles requiring painting and at least one arrangement (126) for separating wet paint overspray in accordance with Claim 6.

8. A plant for painting vehicle bodies (102) comprising at least one application area (108) for the application of wet paint to the vehicle bodies requiring painting and at least one arrangement (126) for separating wet paint overspray in accordance with Claim 6.

9. A method for separating wet paint overspray from a stream of crude gas containing overspray particles, comprising the following method steps: - introducing the stream of crude gas (120) into a filter device (132); = separating the overspray from the stream of crude gas (120) by means of at least one filter element (172) which is arranged in the filter device (132); - accommodating an auxiliary filter material in an auxiliary material reservoir (176); and - mixing the material present in the auxiliary material reservoir (176) by means of a device (332) for mixing the material present in the auxiliary material reservoir (176).

10. A method in accordance with Claim 9, wherein the material present in the auxiliary material reservoir (176) is mixed by rotating agitator paddles (340) when an agitator shaft (338) of the device (332) for mixing the material present in the auxiliary material reservoir (176) is set into rotary motion.

11. A method in accordance with Claim 10, wherein the agitator shaft (338) is aligned substantially horizontally and passed through a side wall (178) of the auxiliary material reservoir (176).

12. A method in accordance with either one of Claims 10 or 11, wherein the agitator shaft (338) is set into rotary motion by means of a motor.

13. A method in accordance with Claim 12, wherein the motor is an electric motor (346) or a turbine (342). DATED THIS gth DAY OF FEBRUARY 2011 14 —————— SPOOR & APPLICANT'S PATENT ATTORNEYS