U.S. patent application number 16/950737 was filed with the patent office on 2021-03-11 for methods for removing overspray from air flow exiting painting booths.
The applicant listed for this patent is GEICO S.p.A.. Invention is credited to Alessandro DI LUCREZIA, Valerio IGLIO.
Application Number | 20210069743 16/950737 |
Document ID | / |
Family ID | 1000005225954 |
Filed Date | 2021-03-11 |
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United States Patent
Application |
20210069743 |
Kind Code |
A1 |
IGLIO; Valerio ; et
al. |
March 11, 2021 |
METHODS FOR REMOVING OVERSPRAY FROM AIR FLOW EXITING PAINTING
BOOTHS
Abstract
A method for removing overspray from air flow exiting a painting
booth may include passing the air flow through an incoherent mass
of cleaning elements, which are kept in a stirred condition, so as
to release the overspray onto the cleaning elements of the
incoherent mass.
Inventors: |
IGLIO; Valerio; (Monza (MB),
IT) ; DI LUCREZIA; Alessandro; (Cinisello Balsamo
(MI), IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GEICO S.p.A. |
Cinisello Balsamo (MI) |
|
IT |
|
|
Family ID: |
1000005225954 |
Appl. No.: |
16/950737 |
Filed: |
November 17, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15780058 |
May 30, 2018 |
10870125 |
|
|
PCT/IB2016/057150 |
Nov 28, 2016 |
|
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16950737 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B05B 14/468 20180201;
B05B 14/43 20180201; B05B 7/1454 20130101; B01D 2275/204 20130101;
Y10S 55/46 20130101; B05B 16/00 20180201; B09B 3/00 20130101; B01D
41/02 20130101; B01D 2258/0258 20130101; B05B 16/60 20180201; B01D
46/30 20130101; B01D 46/32 20130101 |
International
Class: |
B05B 14/468 20060101
B05B014/468; B01D 41/02 20060101 B01D041/02; B01D 46/32 20060101
B01D046/32; B05B 14/43 20060101 B05B014/43; B05B 7/14 20060101
B05B007/14; B09B 3/00 20060101 B09B003/00; B05B 16/00 20060101
B05B016/00; B01D 46/30 20060101 B01D046/30; B05B 16/60 20060101
B05B016/60 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 2, 2015 |
IT |
102015000079570 |
Claims
1-12. (canceled)
13. A method for removing overspray from air flow exiting a
painting booth, the method comprising: passing the air flow through
an incoherent mass of cleaning elements, which are kept in a
stirred condition, so as to release the overspray onto the cleaning
elements of the incoherent mass.
14. The method of claim 13, wherein the cleaning elements have a
size that is between 100 and 10,000 times greater than an average
size of paint droplets which form the overspray.
15. The method of claim 13, further comprising: producing the
cleaning elements from combustible material; using the cleaning
elements in the air flow in order to remove the overspray;
extracting the paint-soiled cleaning elements; and burning the
extracted cleaning elements, the paint on the extracted cleaning
elements, or the extracted cleaning elements and the paint on the
extracted cleaning elements.
16. The method of claim 15, wherein during the burning, thermal
energy is recovered, electricity is produced, or the thermal energy
is recovered and the electricity is produced.
17. The method of claim 13, wherein the overspray comprises liquid
paint.
18. The method of claim 13, wherein an average size of paint
droplets which form the overspray is greater than or equal to
7.times.10.sup.-6 meters and less than or equal to
1.5.times.10.sup.-5 meters.
19. The method of claim 14, wherein the paint droplets comprise
liquid paint.
20. The method of claim 13, wherein the cleaning elements have a
size that is between 500 and 5,000 times greater than an average
size of paint droplets which form the overspray.
21. The method of claim 13, wherein the cleaning elements have a
size that is about 1,000 times greater than an average size of
paint droplets which form the overspray.
22. The method of claim 13, wherein the cleaning elements comprise
pellets, chips, or pellets and chips.
23. The method of claim 13, wherein the cleaning elements comprise
plant material, inert material, or plant material and inert
material.
24. The method of claim 13, wherein each of the cleaning elements
has an individual shape, and wherein the individual shape has at
least one dimension greater than 1 millimeter (mm).
25. The method of claim 24, wherein the individual shape is
generally cylindrical, conical, spherical, cubic, or
tetrahedral.
26. The method of claim 24, wherein the individual shape is
irregular.
27. The method of claim 24, wherein the individual shape is
generally cylindrical.
28. The method of claim 24, wherein the individual shape is
generally cylindrical, with a diameter between 2 millimeters (mm)
and 10 mm, and a length between 3 mm and 40 mm.
29. The method of claim 13, wherein a mechanical stirrer for
keeping the cleaning elements in the stirred condition comprises a
rotating stirring device comprising vanes, arms, or surfaces which
have varied inclinations.
30. The method of claim 13, wherein a mechanical stirrer for
keeping the cleaning elements in the stirred condition comprises a
rotating stirring device comprising vanes, arms, or surfaces which
are configured to rotate inside the mass of the cleaning
elements.
31. The method of claim 13, wherein a mechanical stirrer for
keeping the cleaning elements in the stirred condition comprises a
rotating stirring device comprising vanes, arms, or surfaces which
have varied inclinations and which are configured to rotate inside
the mass of the cleaning elements.
32. The method of claim 13, wherein a mechanical stirrer for
keeping the cleaning elements in the stirred condition comprises a
screw feeder or an Archimedes' screw system.
Description
[0001] The present invention relates to a booth of the type used
for performing painting using spray paint, provided with an
innovative system for removal of the overspray. The invention also
relates to a method for eliminating the overspray and to a
plant.
[0002] In the art of spray-painting the problem of so-called
"overspray", namely the sprayed paint which is not deposited on the
part to be painted and which must therefore be removed from the
painting booth, is well-known. The removal of the overspray is
usually performed by means of a suitable air flow which crosses the
booth.
[0003] The air flow evacuated from the booth must therefore be
purified of the paint before it can be released into the
environment or introduced again into the booth.
[0004] For this purpose, various separation systems, for example of
the type using water, electrostatic type or with integrated filters
suitable for filtering the liquid particles, have been proposed.
These systems are generally complex and require a high degree of
maintenance owing to the adhesive nature of the paint.
[0005] Powder inerting systems have been proposed where the air
flow is conveyed through a filter system composed of a chamber
inside which a suitable inerting product in powder form (for
example calcium carbonate) is blown, said powder absorbing the
particles of paint and being then intercepted by normal dust
filters.
[0006] This system requires, however, a relatively large quantity
of powder which must then disposed of, with high disposal costs.
The procurement of the powders is not always easy and may be
costly. Moreover, relatively complex techniques are necessary for
moving the powder, blowing it in a uniform manner inside the
chamber, intercepting it and evacuating it in an efficient manner
from the air flow after absorption of the paint.
[0007] The said filters are costly and require relatively frequent
maintenance in order to prevent them from becoming completely
blocked up.
[0008] Moreover, the substantially random distribution of the
powder inside the chamber may not be sufficient to prevent the
paint from adhering to the walls of the chamber and to eliminate
securely all the overspray. Also attempts to provide a greater
concentration of powder along the path of the air flow have proved
to be not entirely satisfactory.
[0009] The general object of the present invention is to provide a
method for removing the overspray, a painting booth with an
overspray removal system and a plant which is able to achieve
effective removal of the overspray. Further objects are those of
ensuring less maintenance, lower management and consumable material
costs and fewer disposal problems.
[0010] In view of these objects, the idea which has occurred is to
provide, according to the invention, a painting booth comprising a
painting chamber in which paint is sprayed and which is crossed by
an air flow for evacuation of overspray from the chamber, the air
flow exiting the chamber passing through an overspray removal unit
for removing the overspray from the air flow, characterized in that
the removal unit comprises an incoherent mass of cleaning elements
kept in a stirred condition, through which the air flow containing
the overspray passes so as to release the overspray onto the
cleaning elements.
[0011] The idea which has also occurred is to provide a plant
comprising the booth and also a system for evacuating the cleaning
elements from the overspray removal unit and, if desired, a unit
for combustion of the cleaning elements, supplied by the evacuation
system.
[0012] Another idea which has occurred is to provide a method for
the removal of overspray from the air flow exiting a painting booth
and comprising the step of passing the air flow through an
incoherent mass of cleaning elements which are kept stirred, in
order to release the overspray onto the cleaning elements.
[0013] In order to illustrate more clearly the innovative
principles of the present invention and its advantages compared to
the prior art, an example of embodiment applying these principles
will be described below with the aid of the accompanying drawings.
In the drawings:
[0014] FIG. 1 shows a schematic front view of a painting booth
applying the principles of the invention;
[0015] FIG. 2 shows a plan view of a part of the booth according to
FIG. 1;
[0016] FIG. 3 shows a schematic front view of a second embodiment
of a painting booth applying the principles of the invention;
[0017] FIG. 4 shows a schematic view of a plant constructed in
accordance with the principles of the present invention.
[0018] With reference to the figures, FIG. 1 shows a painting booth
according to the invention, denoted generally by 10.
[0019] The booth comprises a chamber 11 for painting objects 12
(for example motor vehicle bodies). The objects to be painted are
advantageously transported into the chamber 11 by means of a known
conveyor system 13, for example an intermittent or continuous
conveying line.
[0020] The chamber 11 is provided with painting devices or operator
units 14 which, when activated, spray liquid paint onto the
surfaces of the object to be painted. Advantageously, the painting
devices may be realized by means of known robot arms which are
provided with spray guns or cups at their ends.
[0021] An air flow is passed through the chamber 11 in order to
remove the overspray from it. Advantageously, this is obtained by
means of a floor 15 of the chamber 11 composed of grilles through
which the chamber air is drawn in order to evacuate the overspray
from the chamber. The ceiling of the chamber is therefore provided
with air inlets 16 which are also advantageously provided with
grilles and filters so as to have a continuous air flow which
passes vertically through the chamber from the top downwards during
the painting operations. The air flow exiting the chamber with the
overspray is conveyed to an overspray removal unit 17 from which
the cleaned air exits through ducts 18. Suitable aspirators or fans
19, which are present along the air path, suitably move the air
flow.
[0022] The unit 17 may be situated directly underneath the grilled
floor of the booth or may be connected to the air outlet of the
booth by means of suitable conveyors. For example, funnel conveyors
20 may be provided underneath the floor of the booth. Where
necessary the inner wall of the conveyors may be lined with a known
anti-adhesive material or removable film to prevent adhesion of the
overspray.
[0023] For reasons which will become clear below, the outlet of the
unit 17 may also be provided with known dust filters 21.
[0024] The air flow, after passing the overspray removal unit 17
and being purified, may be evacuated externally via a duct 22
and/or be conveyed back into the chamber via ducts 23.
[0025] A known air supply system 24, which may have associated
known treatment systems, may also be provided with the possibility
of recirculating or entirely changing the air to be conveyed to the
chamber.
[0026] According to the principles of the invention, the removal
unit 17 comprises an incoherent mass of cleaning elements 25 kept
in a stirred condition, through which the air flow containing the
overspray is passed so as to release the overspray onto the
elements of the mass before the air flow leaves the ducts 18.
Advantageously, the cleaning elements are heaped together in the
mass, in contact with each other, apart from the interstices, which
are naturally created between them and through which the air
crossing the mass passes, also owing to the stirring movement.
[0027] In addition to exposing all the parts of the elements to the
paint, the stirring movement also prevents the cleaning elements
from stably adhering to each other and the interstices from being
closed up by the paint.
[0028] Advantageously, the dimensions of the cleaning elements are
greater by at least a factor of 100, and preferably 100 and 10,000
times greater, than the size of an average droplet of overspray.
Preferably, the cleaning elements have at least a greater size that
is between 500 and 5000 (advantageously, around 1000) times the
average size of the droplets of overspray. For example, usually the
droplets of overspray are atomized with an average size of 7-15
microns.
[0029] Preferably, the elements 25 of the mass may have a size of
around 1 mm or more.
[0030] For example, the elements 25 may have a generally defined
(cylindrical, conical, spherical, cube-like, tetrahedral, etc.) or
irregular shape. For example, in the case of a generally
cylindrical shape, the elements 25 may have a diameter between 3
and 10 mm (preferably around 6 mm) and length between 5 and 50 mm
(preferably between 10 and 30 mm).
[0031] The irregular shape may be a shape which is directly
produced by the method used to obtain the cleaning elements or may
be obtained by means of subsequent processing. For example, these
elements may consist of chips, namely produced from wood or similar
material reduced into irregular flakes or scales.
[0032] Inert material elements may also be used. In particular,
clay (for example, balls of expanded clay) may be used. Expanded
clay is light, relatively inexpensive, has good paint-absorbing
properties and may also be cleaned of the paint by means of
combustion of the paint, so that it can be used again or disposed
of differently.
[0033] The layer of cleaning elements which the air must pass
through will be regulated so as to obtain the desired removal of
overspray, keeping the pressure drop within acceptable limits so as
not to cause excessive obstruction of the air flow passage. This
will also depend on the shape and size of the elements in the mass,
which will leave more or less space free between one element and
the next one in the incoherent mass.
[0034] The cleaning elements may be made of a material which does
not absorb the paint, but which remains coated by it (for example
plastic, glass or metal). In this case, a useful shape may be a
generally spherical shape, even though other shapes may be used.
Once these elements are sufficiently coated with paint they may be
replaced with other elements which have not been coated yet, and
may be destroyed or suitably cleaned and if necessary used
again.
[0035] The cleaning elements may also be preferably made of plant
material, being obtained also from agricultural plant waste (for
example hay chaff), sawdust, etc.
[0036] The cleaning elements may be, for example, made by means of
conversion of the chosen material into pellet form. Advantageously,
they may consist for example of pellets obtained from wood
shavings. Plant-derived pellets may be inexpensive, light and
easily transportable. With low-cost materials it becomes
advantageous to eliminate the cleaning elements once they have been
coated or become impregnated with paint in an amount such that they
can no longer adequately perform their function of retaining the
overspray. Depending on the chosen material, elimination may be
performed in various ways. For example, the elements may be burned,
used to form part of construction materials, etc.
[0037] In the case where the cleaning elements have a structure
(for example sawdust pellets) such as to produce dust, the optional
filters 21 prevent this dust from being carried away by the air
flow and expelled or introduced into the booth.
[0038] In order to stir the mass, so as to allow the air to pass
through the mass and expose all the cleaning elements to the
overspray, various systems may be used.
[0039] In particular, it is advantageous to use a mechanical
stirrer, per se of the known type (for example with a motor-driven
component rotating inside the mass, a vibrating surface, etc.), in
order to keep the mass of cleaning elements stirred in a manner
suitable for allowing circulation of the air inside it and at the
same time widespread exposure of the surface of the elements to the
overspray conveyed by the air mass, such that the overspray is
suitably removed from the air flow; moreover, stirring of the
cleaning elements causes them to rub both against the containing
surface and against the stirring devices, preventing the cumulative
soiling thereof.
[0040] FIG. 1 shows an example of a stirring system formed by a
tank or chamber 28 inside which a suitable stirring device rotates.
The stirring device may, for example, comprise vanes, arms or
surfaces which are varyingly inclined and which rotate inside the
mass of cleaning elements.
[0041] In particular, the tank or chamber 28 may be shaped and have
motor-driven mixing devices 26 rotating at suitable speeds about a
shaft 27. The devices may also be two in number, for example also
counter-rotating with respect to one another.
[0042] Among the stirring systems the rotating systems may be of
various types; for example it has been found to be advantageous to
use a screw feeder or Archimedes screw system for the function of
replacing the cleaning elements. The system rotated at a suitable
speed keeps the mass of cleaning elements stirred and, if desired,
allows easy loading and unloading (also automatically) of the
cleaning elements even during operation of the plant. In
particular, a controlled inlet (for example with suitable gate
valves) may be provided for clean elements at one end and an outlet
may be provided for soiled elements at the other end. These inlets
and outlets may be for example activated at intervals dependent on
the speed at which the elements of the mass are soiled.
[0043] If desired, the stirring system and the loading system may
also have two separate devices, for example with arms or other
stirring elements and with a screw feeder for conveying the
cleaning elements from and towards the stirring system, as may be
now easily imagined by the person skilled in the art.
[0044] FIG. 2 shows the plan view of a possible embodiment of the
unit 17 with two stirrers or two feeder screws 26 arranged
alongside each other and with motor-driven shafts 27 arranged
horizontal and parallel. The two stirrers occupy the same rotation
tank and the same mass of elements being stirred.
[0045] As can be seen also in FIG. 1, the air outlets are arranged
advantageously to prevent the cleaning elements from spilling out
along the air ducts. The air outlet may also be provided with
grilles for retaining the elements of the mass inside the rotation
tank. For example, the air outlets may be arranged in the top half
of the rotating parts. The ducts may be arranged advantageously
inclined upwards.
[0046] Other stirring devices arranged along the axis of rotation
27, such as suitably shaped vanes, radial mixing rods, etc., may
also be used instead of the Archimedes screw.
[0047] Different systems, such as a vibrating system, may also be
used.
[0048] The vibrating system may for example be in the form of a
vibrating grating which has openings with a diameter smaller than
that of the cleaning elements and on which the mass of elements
rests so that it can be crossed by the air while it vibrates.
[0049] The feeder screws or the rotating devices may also consist
of a number different from that shown. For example, a single feeder
screw or more than two feeder screws arranged alongside each other
may also be used.
[0050] The rotating devices may extend with their axis of rotation
along the entire length of the booth floor or be shorter. In the
latter case several units 17 aligned along the length of the floor
may also be provided.
[0051] FIG. 3 shows a constructional variant of the booth of FIG.
1, in which the bottom of the booth conveys air with overspray to
several units 17 for removing the overspray. In this way, the units
17 may for example be arranged closer to the floor of the booth
and/or be smaller, depending on the length of the floor. This may
be useful also in the case of particularly long booths. The
closeness of the unit 17 to the booth reduces the surfaces exposed
to the overspray before it reaches the mass of cleaning
elements.
[0052] The units 17 may be arranged alongside each other in one or
both directions of the length of the floor.
[0053] With the systems according to the invention, the soiled
incoherent material, which may be easily transported using
advantageous known systems, may be burned with recovery of the
thermal energy from the overspray and/or of the material itself
should it be combustible.
[0054] In particular, if the cleaning elements are made of material
which is non-combustible at the combustion temperatures chosen for
the paint, only the paint may be burned and the cleaning elements
used again or the elements thus cleaned may be disposed of in a
different way. For example, in the case of expanded clay elements
it is possible for only the paint to be burned.
[0055] If, on the other hand, the chosen material for the cleaning
elements is a fuel, these elements may be burned together with the
paint once they have performed their overspray retaining
function.
[0056] In any case, energy may be advantageously recovered from
combustion in a special plant.
[0057] FIG. 4 shows in schematic form a possible cycle for use of
the elements 25.
[0058] The plant shown in FIG. 4 comprises a booth 10 of the type
realized according to the invention with a unit 17 for removal of
the overspray, from which the air, purified of the overspray by
means of the mass of cleaning elements 25 kept stirred, exits at
22. The elements of the mass may be introduced into the unit 17 by
means of an insertion system 30 known per se (manual,
semi-automatic or automatic) and the used elements (in the sense
that they no longer are able to perform removal of the overspray
with adequate efficiency) may be extracted from the unit 17 by
means of an evacuation system 31 known per se (manual,
semi-automatic or automatic) and conveyed away for combustion
(entirely or only the paint) inside a suitable combustion unit 32
which burns them at an appropriate temperature. A suitable known
system 33 for purification of the fumes may be provided.
[0059] The combustion unit 32 may be advantageously provided with
thermal energy recovery means 34 and/or means 35 for the production
of electrical energy from the thermal energy produced during
combustion.
[0060] For example, a liquid circulation heating system 34 for
heating spaces, water or other fluids and/or a thermoelectric
generator 35 (advantageously a turbine with alternator) for
powering an electric line 36 may be used.
[0061] The thermal production may be for example used to heat the
same spaces or other parts of the production process of the plant
or the factory which uses the booth.
[0062] The electrical energy produced may supplement the electric
power requirement of the plant or the factory which uses the
booth.
[0063] In the case of non-combustible cleaning elements, they may
be extracted after combustion of the paint for recycling where
necessary.
[0064] At this point it is clear how the predefined objects have
been achieved. The use of a mass of cleaning elements which are
kept stirred according to the invention ensures satisfactory
removal of the overspray, while keeping the complexity of the
removal plant to a minimum. Moreover, the cleaning elements may be
easily procured. For example, with the use of pellets obtained from
plant waste it is possible to obtain the production of cleaning
elements in large amounts and with the need for only limited,
low-pollution, production technology, thus solving the problem of
disposal of the agricultural waste or the like.
[0065] With the system according to the invention it is also
possible to obtain a booth without or with short maintenance
downtime, since the overspray removal system may operate
continuously, owing to the fact that it allows gradual replacement
of the elements in the mass.
[0066] The cleaning elements may moreover be easily recycled and
also allow, if desired, the production of thermal and/or electrical
energy, resulting in added value instead of a pure disposal
cost.
[0067] The essentially fluid behaviour of the mass of cleaning
elements enables easy transportation within the plant and said
transportation may also be easily automated by means of pipes, belt
conveyors and the like.
[0068] Inside the overspray removal unit, the surfaces coming into
contact with the overspray are subject to an effective paint
cleaning action owing to rubbing of the elements of the stirred
mass against these surfaces.
[0069] Moreover, the overspray removal efficiency is very high
since it is the air which is forced to pass through an incoherent
mass of cleaning elements which receive the overspray. For example,
in powder systems, where it is instead the absorbing material which
is blown into the air flow, it is very difficult to ensure a
uniform density of the powders, with the consequent high
probability that droplets of overspray may pass through intact
without making contact with powder particles.
[0070] Obviously the above description of an embodiment applying
the innovative principles of the present invention is provided by
way of example of these innovative principles and must therefore
not be regarded as limiting the scope of the rights claimed herein.
For example, the booth and the combustion unit may be situated in
two locations which are also distant and the conveyor system may
also comprise transportation vehicles. The booth and/or the plant
may also comprise other known parts, which are not shown here and
do not form the subject of the invention, and the operating methods
may comprise other operating steps.
* * * * *