Note: Descriptions are shown in the official language in which they were submitted.
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1
Filter device and method for separating wet paint overspray
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
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compressed air issuing from a compressed air lance so as to
cause it to rise 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.
The 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 directed
into the auxiliary material reservoir.
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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, it is 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
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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.
In a preferred embodiment of the invention, the inlet
opening is 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
is expedient for the lower guide surface to be inclined to
the horizontal at least in sections thereof, and in
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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 is 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 is directed into the auxiliary material reservoir,
it is 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.
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Hereby, 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 least approximately 300,
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
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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 of 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 is particularly effective, if it
projects into the interior of the filter device and/or into
the interior of the auxiliary material reservoir.
In a preferred embodiment of the invention, provision is
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
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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.
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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, said 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.
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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 in accordance with the invention 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 in accordance with the invention 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
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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 100, 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 in accordance with the invention for
separating wet paint overspray 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 in
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accordance with the invention 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; and
- separating the overspray from the stream of crude gas by
means of at least one filter element arranged in the
filter device.
The object of the present invention is to provide a method
of this type wherein the at least one filter element is
impinged by auxiliary material in a simple and efficient
manner but without such auxiliary material reaching the
application area of a paint shop.
In accordance with the invention, this object is achieved
in the case of a method incorporating the features
mentioned in the first part of Claim 35 in that the stream
of crude gas is fed into the filter device through at least
one inlet opening in such a way that the stream of crude
gas enters the filter device directed into an auxiliary
material reservoir that is used for accommodating an
auxiliary filter material.
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Special embodiments of the method in accordance with the
invention form the subject matter of Claims 36 to 41, the
features and advantages thereof having already been
described in connection with the special embodiments of the
filter device in accordance with the invention or the
arrangement in accordance with the invention for separating
wet paint overspray from a stream of crude gas containing
overspray particles.
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.
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The present invention is suitable, in 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 flow of the crude gas, the exhaust air
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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;
Fig. 5 a schematic side view of the plant depicted in
Figs. 1 to 4;
Fig. 6 a schematic perspective illustration of the
arrangement for separating wet paint overspray
from a stream of crude gas containing overspray
particles which is arranged under the paint booth
of the plant depicted in Figs. 1 to 5 and which
comprises transverse partitioning walls
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);
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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
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;
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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;
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;
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
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
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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 reservoir 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
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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 is 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 m to approximately 100 m
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.
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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 is
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
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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.
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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 is 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
partitioning 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.
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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.
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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
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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 m to
approximately 100 m 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.
CA 02697442 2010-02-23
26
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 180 of the auxiliary material reservoir 176 through
which the stream of crude gas 120 loaded with the overspray
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
CA 02697442 2010-02-23
27
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 is
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.
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When the plant 100 is operative, the whirling device 198 is
put into service intermittently, for example, four times
per minute for approximately 5 seconds on each occasion.
The whirling device 198 comprises several, two for example,
outlet 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
CA 02697442 2010-02-23
29
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).
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.
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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
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
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
CA 02697442 2010-02-23
31
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.
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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 m or 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 is 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
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33
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 is
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
CA 02697442 2010-02-23
34
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 its 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 of
CA 02697442 2010-02-23
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 is illustrated in Fig. 10 as the result of a
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 is prevented but nevertheless there is a flow through
the filter elements 172 which is advantageous to the
filtration process.
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36
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 is inclined to the horizontal at an
angle of more than 400, 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 also 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.
CA 02697442 2010-02-23
37
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.
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
CA 02697442 2010-02-23
38
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 illustration of Fig.
19, the exhaust air that has been cleansed of wet paint
overspray passes from the exhaust air duct 250 to an
exhaust air fan 252, and from there, the cleansed exhaust
air is 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).
CA 02697442 2010-02-23
39
Each of the air curtain producing devices 254 comprises a
respective air 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
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.
CA 02697442 2010-02-23
The horizontal cross section of the flow chamber 128
through which the stream of crude gas is 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.
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
is illustrated in Fig. 3 by means of the arrows 264.
The greater part of the air being passed through the
application area 108 is 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
CA 02697442 2010-02-23
41
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 of the
flow chamber 128 through which the stream of crude gas is
adapted to flow is 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 is 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
CA 02697442 2010-02-23
42
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
CA 02697442 2010-02-23
43
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 is 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.
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44
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.
CA 02697442 2010-02-23
The control unit 210 blocks the supply of compressed air
from the compressor 272 to the abovementioned compressed
air 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.
CA 02697442 2010-02-23
46
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 in 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
CA 02697442 2010-02-23
47
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-
CA 02697442 2010-02-23
48
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 B1, 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 is
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,
it 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
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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.
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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
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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 314a,
314b, and into a collection tank 316 arranged below the
extractor fan 310.
Each 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
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
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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.
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
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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
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54
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 0 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.
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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.
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
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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.
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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.
20 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.
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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 1800 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 is ensured.
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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 is 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.
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Subsequently, a filter module 132 is arranged in the
working position that has been exposed in this manner and
it is 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.
