EP2437895A1

EP2437895A1 - Recirculating-air spray booth

Info

Publication number: EP2437895A1
Application number: EP11719560A
Authority: EP
Inventors: Gerd Wurster
Original assignee: Individual
Current assignee: Duerr Systems AG
Priority date: 2010-05-17
Filing date: 2011-05-13
Publication date: 2012-04-11
Anticipated expiration: 2031-05-13
Also published as: ES2445766T5; WO2011144527A1; PL2437895T5; EP2437895B1; DE102010021540A1; PL2437895T3; ES2445766T3; PT2437895E; EP2437895B2

Abstract

A recirculating-air spray booth with a working region (14) for coating workpieces (16) is specified, with an extraction zone from which solvent-containing exhaust air is extracted, and with a fan (22) for circulating the air, wherein at least part of the exhaust air can be resupplied as recycled air to the spray booth (10a) via at least one filter unit (24) in the recirculating-air mode, wherein the spray booth (10a) can be switched over into a rapid venting mode, in which the supply of recycled air is interrupted or reduced and additional air, which is preferably filtered and at least part of which is not recycled, can be supplied in the working region (14) (Figure 2).

Description

Recirculated air spray booth

The invention relates to a recirculation spray booth with a work area for coating workpieces, with a suction zone, is sucked from the polluted, in particular solvent-containing exhaust air, and with a fan for air circulation, wherein the exhaust air of the spray booth in recirculation mode in the work area over at least a filter unit is at least partially fed back as recycled air.

Such spray booths are known as Umluftkabinen. The term "coating" is understood in the context of this application preferably a spray painting. While it is possible to remove dust and foreign particles highly efficiently in the recycling of exhaust air via high-quality separation systems or filter devices, the solvent concentration (measured in g / m ³ ) increases over time. However, the concentration of solvents should not rise above 5 g / m ³ due to the explosion safety.

As far as the spray booth is operated automatically, the increase of the solvent concentration by the recirculation mode plays no special role, as long as the allowable limits are not exceeded. However, if the spray booth has to be entered by a worker, the maximum permissible solvent concentration of 5 g / m ³ for exhaust air is too high, especially if it concerns large spray booths, such as those used in the automotive industry. If the spraying operation is interrupted, however, the concentration reduction of the solvent concentration takes place only very slowly. Thus, it usually takes about 30 to 60 minutes to lower the solvent concentration from, for example, a maximum permissible value of 5.0 g / m ³ to an acceptable value of, for example, 0.01 g / m ³ .

For this reason, spray booths that work in recirculation mode, so far have been able to prevail only in special cases. In particular, when it comes to large spray booths, as are common, for example, in the automotive industry, there are virtually no air conditioning spray booths.

Against this background, the present invention seeks to provide a recirculation spray booth, which allows for a break in the spray operation, a rapid reduction of the solvent concentration to a permissible value for inspecting the spray booth.

This object is achieved in a circulating air spray booth according to the type mentioned above in that the spray booth can be switched over into a rapid venting operation in which the supply of recycled air is interrupted or is reduced and in the work area at least partially non-recycled, preferably filtered, supply air can be supplied.

The object of the invention is completely solved in this way.

Namely, since the spray booth is switchable to a quick-release operation and in the working area at least partially non-recycled, preferably filtered supply air is supplied, there is a quick replacement of existing in the work area solvent-containing air and thus a faster concentration reduction of the solvent concentration to allowable Values. Thus, a safe solvent concentration is reached after a short time after switching to the quick exhaust mode, so that a worker can enter the spray booth without additional protective measures such as breathing masks.

According to a further embodiment of the invention, a part of the exhaust air of the spray booth via a filter unit as recycled supply air is fed back and discharged part of the exhaust air through the roof or an exhaust air purification system to the environment in recirculation mode.

In this way, there is a constant solvent release of the recycled supply air and a constant supply of a certain proportion of non-recycled supply air.

According to a further embodiment of the invention, the exhaust air discharged to the environment is treated in advance, preferably washed, filtered and / or thermally treated or air-conditioned.

In this way, the prescribed limits are respected or can be achieved by means of thermal aftertreatment (thermal afterburning) even further reduction of the pollutant concentration. According to a further embodiment of the invention, the spray booth is gradually reversible between a recirculation mode and a quick exhaust mode or vice versa.

In this way, the associated fan can be gradually brought into the other position.

For this purpose, at least one controllable fan and / or a continuously variable air valve is preferably provided. In this context, "air valve" is understood to mean any kind of valve for controlling air. In the simplest case, this is a variable flap with servomotor.

The controllable fan usually has a frequency converter for low-loss control.

According to a further embodiment of the invention, the spray booth comprises a conveyor for conveying workpieces through the spray booth via an entrance through the work area and an exit, wherein at least one separated area is provided at the entrance and preferably at the exit of the spray booth from the work area has separate connections for supply and exhaust air, each separated area can be acted upon with respect to the environment with an overpressure.

In this way, an entry of dusty air in the spray booth is prevented in any case.

In this case, preferably at least one fan for the work area and at least one fan for each separated area is provided, wherein the working area in the quick exhaust operation is not recycled, filtered air can be supplied. In this way, in the case of a switchover to the quick exhaust operation, the working area is additionally freed of solvent agents by supplying unrecycled, filtered air. This is particularly important for long spray booths in order to ensure a sufficiently fast venting.

In this case, the air supplied to the working area in the rapid ventilation mode can be diverted from at least one separated area.

Runs in the quick exhaust operation, the air supply for at least one separated area, so can be ensured in this way with simple means a quick ventilation of the work area.

Preferably, at least in the separated area at the entrance only unrecycled, filtered air is supplied.

However, it is also conceivable that in the separated area, in particular at the output, partially recycled, filtered air and partially non-recycled air is supplied.

According to a further embodiment of the invention, the blower for the working area is preferably operated at reduced power in quick exhaust operation.

In this case, in the quick exhaust operation extracted from the work area preferably air is not recycled, but discharged as exhaust air.

By these measures start-up problems, such as vibrations and shocks are avoided when starting large blowers and an associated risk of contamination. In a further embodiment of the invention, at least one wet scrubber or a suction is provided, is sucked through the bottom, for example, exhaust air. The spray booth is in principle constructed in a known manner according to the prior art, wherein the spray booth can also have several wasserbeflu- tete trickle walls, which eventually open into a common receptacle, can be sucked through the bottom exhaust air, which is, for example, a Venturi scrubber or the like can act. Preferably, such wet scrubbers or suction are present at each portion of the spray booth.

According to a further advantageous embodiment of the invention, the fan is operated for the work area in the quick exhaust operation with such reduced power that an overpressure in the area of the filter cover (plenum) is maintained.

In this way, dust detachments and detachment of foreign substances from the filters are largely avoided.

Preferably, in the switching between recirculation mode and quick exhaust operation, the fan speed of the work area is gradually reduced and gradually fed from a separate area unrecycled, filtered air.

In this way, in particular start-up problems that exist in large blowers and usually lead to shaking, vibration and other disturbances can be largely avoided.

Conversely, when switching between quick exhaust operation and recirculation mode, the fan power of the working area is preferably gradually increased and fed from a separate area, non-recycled, filtered air gradually redirected back into the separated area. Overall, these measures largely avoid start-up problems in the case of large blowers, so that it is possible to significantly reduce the blower output in the work area for the quick-venting operation, while the blower output in the separated areas can be maintained further.

Preferably, the work area is constantly supplied via a filter unit with supply air, so both during the recirculation mode as well as during the Sehn hurry tlüf operation operation.

In this way, the filter cover (the plenum) is constantly under a certain pressure, so that no dust detachments and the like occur.

It is understood that the above-mentioned and the features of the invention to be explained below not only in the combination, but also in other combinations or alone, without departing from the scope of the present invention.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. Show it:

1 shows a greatly simplified illustration of a first embodiment of a circulating air spray booth according to the invention;

FIG. 2 shows a modified embodiment of the circulating air spray booth according to FIG. 1; FIG.

3 shows a partial area of a further embodiment of a spray booth according to the invention; and Fig. 4 shows a recirculation spray booth according to the invention, which is used in particular in extensive, particularly high-quality finishes, such as in the automotive industry.

In all Figures 1 to 4 blower outputs are given, which are given here by way of example in m ³ / h. In parentheses, some other values are given below. The values without brackets are for the air flow in the recirculation mode, while the values in brackets for the air flow are in the quick exhaust mode.

In Fig. 1, a recirculation spray booth is shown in simplified form and designated overall by the numeral 10. The recirculation spray booth 10 has a closed housing 12, in which a work area 14 for spray painting of workpieces 16 is located. Below a bottom 13, a wet scrubber 18 is provided, is exhausted via the bottom side exhaust air. In recirculation mode, air is supplied via a blower 22 with 90,000 m ³ / h of air via one or more filters 24 and fed via a filter cover 20 (also known as plenum) from above into the working area 14. About a further blower 28, a portion of the extracted via the wet scrubber 18 exhaust air is sucked and discharged to the outside to the environment, for example on the roof. This is 10,000 m ³ / h. These 10,000 m ³ / h are additionally sucked in the work area 14 from the installation room or outside the spray booth as fresh air, as indicated by the arrow 15. Consequently, 90% of the extracted exhaust air are recycled in recirculation mode and recycled as recycled, filtered air, while 10% are sucked in as fresh air and 10% are discharged as exhaust air. If now a switch to a quick exhaust operation to reduce the solvent concentration in the spray booth quickly to unproblematic values, so the fan 22 is turned off and an air valve 26, via which this is coupled to the wet scrubber 18, closed. Thus, circulating air is no longer circulated in the quick exhaust operation, while the exhaust fan 28 is operated further, so that the working area 14 is quickly flooded with 10,000 m ³ / h of fresh air. 2, a slightly modified embodiment of the spray booth according to FIG. 1 is shown and designated overall by numeral 10a. Here, too, the working area 14 is supplied with circulating air via a blower 22 in recirculation mode via a filter 24 and a valve 32. The blower 22 in this case has a capacity of 100,000 m ³ / h in recirculation mode. While 90,000 m ³ / h are conducted into the working area 14 as recycled, filtered air, 10,000 m ³ / h are passed through a valve 32 to a thermal afterburning 34, thereafter thermally burned and finally released into the open air. The thermal afterburning may preferably also be a regenerative thermal afterburning RNV. In recirculation mode, therefore, 100,000 m ³ / h are extracted from the working area 14 via the wet scrubber 18, while only 90,000 m ³ / h are recycled as recycled, filtered air via the plenum 20. The remaining 10,000 m ³ / h are additionally sucked into the working area 14 via a filter 36 or via the plenum 20, as shown by the arrow 15. If the spray booth 10a now be vented quickly, the fan 22 is reduced in its power to 10,000 m ³ / h and the air valve 32 is closed. Thus, no recycled exhaust air is more supplied to the work area 14. Thus, only exhaust air is discharged via the thermal afterburning 34 to the outside and introduced as fresh air through the filter 36 further 10,000 m ³ / h.

In this way, a quick exhaust is guaranteed. At the same time, the blower 22 is not completely shut down, but continues to run at 10% of its power. This has the consequence that when switching between recirculation mode and quick exhaust operation, a start-up of the blower 22 is not necessary. In this way, strong shaking, beats, etc. that occur when starting up blowers are avoided. In this way, foreign particles, dust, dirt, etc., which could otherwise occur in the work area 14 when starting reinforced, largely avoided.

In Fig. 3, another embodiment of a Umluftspritzkabine invention is shown and designated in total with numeral 10b. This is a larger spray booth, such as those used in automotive paint finishes in the automotive industry. mobile industry is used. The spray booth 10b has an elongate working area 14, which is shown here only in part, to which an entrance area 38 (separated area at the entrance) is connected upstream. A conveyor 50 runs through the spray booth 10b, by means of which workpieces 16 are moved continuously or intermittently over the entrance area 38 through the working area 14.

The work area 14 has its own air duct, which is not shown here in Fig. 3. For the input area 38, a blower 40 is provided, by means of which fresh air is sucked from the outside and is supplied via a filter 42 and a valve 44 via the plenum 20 from above into the input area 38. This is, for example, 50,000 m ³ / h. A part, namely 20,000 m ³ / h, passes through a suction area 52 of the input area 38 and is finally delivered via a line 48 to the environment. 25,000 m ³ / h are diverted into the work area 14. The remaining 5,000 m ³ / h are released as "overpressure" to the environment. Thus, the spray booth 10b is completely under pressure, so that at the entrance area 38 no dust, foreign particles, etc. can penetrate. Not shown is the air duct in the working area 14, to which a fan with a high volume of circulating air belongs, by means of which recirculated air recirculated air is supplied again. If the spray booth 10b is now to be switched over from the recirculation mode to the fast vent mode, then the blower 40 continues to run unchanged with the same output of 50,000 ^m3 / h. Via the air valve 44, a reduced volume of air of 25,000 m ³ / h is passed into the inlet area 38, of which 20,000 m ³ / h in the suction area 52 and from there into the environment via the line 48. Another 5,000 m ³ / h escape as "overpressure" to the outside. From the supplied by the fan 40 air flow of 50,000 m ³ / h, the second part of 25,000 m ³ / h is fed via a further air valve 46 in the work area 14. With the help of this air flow effective ventilation of the working area 14 is ensured, so that even with very long work areas 14 an effective ventilation takes place. In rapid exhaust operation, there is no further diversion of air from the entrance area 38 to the work area 14. In FIG. 4, starting from the embodiment previously described with reference to FIG. 3, a complete embodiment of a spray booth 10c for automotive paint finishes in the automotive sector is shown. The spray booth 10c in this case has an elongate housing 12, with a working area 14, an entrance area 38 and an exit area 66. Again, workpieces 16 are passed by means of a conveyor 50 through the entrance area 38, the work area 14 and exit area 66 of the spray booth 10c. Both the working area 14, as well as the entrance area 38 and the exit area 36 are provided with wet scrubbers or suction devices 18, 52 and 54, respectively. About the plenum 20 is fed from above filtered supply air.

First, the recirculation mode is explained. Via a fan 22 to 300,000 m ³ / h 250,000 m ³ / h are supplied via a valve 32 as recycled, filtered air across the plenum 20 from above in the work area fourteenth By means of a wet scrubber 18, a total of 300,000 m ³ / h are sucked off by means of the blower 22, the remaining 50,000 m ³ / h are discharged via a valve 30 to the outside or fed to a thermal afterburning. At the entrance area 38, a fan 40 is provided, are sucked by means of which in the recirculation mode 80,000 m ³ / h and fed via a valve 44 via the plenum 20 from above into the input area 38. 50,000 m ³ / h pass through the suction 52 and another fan 28 as exhaust air to the outside. Another 25,000 m ³ / h are diverted into the working area 14. The remaining 5,000 m ³ / h escape as overpressure at the entrance to the outside. In the exit area 66, a further blower 56 is provided at 80,000 m ³ / h. These 80,000 m ³ / h are passed via a valve 60 from above via the plenum 20 in the output area 66. Of this reach 50,000 m ³ / h via the suction 54 and a valve 64 back to the blower 56. Another 30,000 m ³ / h are sucked as fresh air via a valve 62 from the outside via the blower 56. From the supplied via the valve 60 air flow of 80,000 m ³ / h, a further proportion of 25,000 m ³ / h is deflected into the working area 14. The remaining portion of 5,000 m ³ / h escapes from the exit area 66 to the outside, so that even here no penetration of dust and the like is possible. If the spray booth 10c now switched to quick exhaust operation, the two fans 40, 56 continue to run with the same power of 80,000 m ³ / h. In contrast, the blower 22 is reduced to a capacity of 50,000 m ³ / h. These 50,000 m ³ / h are still discharged via the valve 30 to the outside or led to the thermal afterburning. The valve 32 is closed, so that no recycled air reaches the working area 14 more. At the entrance area 38, the valve position of the valve 44 is changed in such a way that only 55,000 m ³ / h pass into the input area 38 via this valve 44. The remaining portion of 25,000 m ³ / h is supplied via a valve 46 in the working area 14 via the plenum 20. The air flow of 55,000 m ³ / h in the entrance area 38 passes with 50,000 m ³ / h via the exhaust 52 and the blower 28 as exhaust air to the outside, while 5,000 m ³ / h escape at the entrance as overpressure. In the working area 14, air supplied from the valve 44 is no longer deflected into the working area 14. At the outlet area 66, a part of the air flow of 80,000 m ³ / h, namely 25,000 m ³ / h, is deflected via a valve 58 from above into the working area 14. The remaining portion of 55,000 m ³ / h is passed through the exit area 66, with no redirection in the work area 14 takes place. 50,000 m ³ / h pass through the suction 54 and the valve 64 back to the blower 56, while the remaining 5,000 m ³ / h escape as pressure at the exit.

At the exit region 66, a part is thus still returned as recycled air in fast-venting operation. However, it would be readily conceivable to provide the air guide at the exit area 66 identical to the entrance area 38 so that no recycled air is supplied.

Due to the illustrated measures results in a very fast ventilation of the spray booth 10c when switching to the quick exhaust operation. At the same time it is avoided that the fan 56 must be restarted from zero, so that resulting starting vibrations, etc. are avoided.

Claims

claims

1. circulating air spray booth with a work area (14) for coating workpieces (16), with a suction zone, is sucked from the polluted, especially solvent-containing exhaust air, and with a fan (22) for air circulation, wherein the exhaust air of the spray booth (10, 10a , b, c) in recirculation mode via at least one filter unit (20, 24) is at least partially fed back as recycled air, wherein the spray booth (10, 10a, b, c) is switchable into a quick exhaust operation in which the supply of re - Cycled air is interrupted or reduced and the work area (14) at least partially non-recycled, preferably filtered, supply air can be supplied.

2. spray booth according to claim 1, wherein in the recirculation mode part of the exhaust air of the spray booth (10, 10 a, b, c) via a filter unit (20, 24) is recycled as recycled supply air and a part of the exhaust air is discharged to the environment ,

3. spray booth according to claim 2, wherein the exhaust air discharged to the environment is previously treated, preferably washed, filtered, adsorbed and / or thermally treated.

4. Spray booth according to one of the preceding claims, which is gradually switchable between a recirculation mode and a quick exhaust operation.

5. Spray booth according to one of the preceding claims, the at least one controllable fan (22) and / or a continuously variable air valve (30, 32, 44, 46, 58, 60).

6. spray booth according to claim 5, wherein the controllable fan (22) comprises a frequency converter.

7. spray booth according to one of the preceding claims, comprising a conveyor (50) for conveying workpieces (16) through the spray booth (10 b, c) via an input through the working area (14) and an output, wherein at least one separated area (38 , 66) is provided at the inlet and preferably at the outlet of the spray booth (10b, c), which has separate connections for supply and exhaust air from the working area (14), wherein each separated area (38, 66) can be acted upon by a pressure which higher than the ambient pressure.

Spray booth according to claim 7, comprising at least one blower (22) for the work area (14) and at least one blower (40, 56) for each separated area (38, 66), the work area (14) not being recycled in the quick blow mode, filtered air can be supplied.

9. spray booth according to claim 8, wherein in the rapid ventilation operation, the working area (14) supplied air from at least one separated area (38, 66) is branched off.

10. spray booth according to claim 8 or 9, wherein at least the separated area (38) at the entrance only unrecycled, filtered air can be fed.

11. spray booth according to one of claims 8 to 10, wherein the separated area (66) at the output partially recycled, filtered air and partially unrecycled air can be fed.

12. Spray booth according to one of claims 8 to 11, wherein in the quick exhaust operation, the blower (22) for the working area (14) is operated with reduced power.

13. Spray booth according to one of claims 8 to 12, wherein in the quick exhaust operation from the work area (14) sucked air is not recycled, but is discharged as exhaust air.

14. Spray booth according to one of the preceding claims, with at least one wet scrubber (18, 52, 54) is sucked through the bottom side exhaust air.

15. Spray booth according to one of claims 8 to 14, wherein the working area and each separated area (38, 66) has a wet scrubber (52, 54), an exhaust or a dry separator is sucked through the bottom side and / or wall side exhaust air.

16. Spray booth according to one of claims 12 to 14, wherein the blower (22) for the working area (14) is operated in quick exhaust operation with such reduced power that an overpressure in the filter cover (20) is maintained.

17. spray booth according to one of claims 8 to 16, wherein when switching between recirculation mode and quick exhaust operation, the fan power of the working area (14) is gradually reduced and from a separated area (38) is gradually recycled non-filtered, filtered air.

18. spray booth according to one of claims 8 to 17, wherein when switching between quick exhaust operation and recirculation mode, the blower power of the work area (14) is gradually increased and from a separate rich (38) previously fed unrecycled, filtered air is gradually redirected to the separated area (38).

Spray booth according to one of the preceding claims, with a filter unit for the supply of supply air in the work area, via which the working area is supplied with supply air both during the recirculation mode and during the quick exhaust operation.