EP0135200B1 - Spraybooth with an evaporation and forced air circulation installation - Google Patents

Abstract

Apparatus for applying of coating material on target objects (11), consisting of at least one painting cabin (10). A conveyor is passing the objects (11) step wise through the cabin (10) and through an adjacent evaporation cabin (30). The painting cabin (10) is divided into two adjacent zones consecutive in the direction of the conveyor movement through which zones air currents (V4a, V4b) are passed one after the other. Air currents (V2, V5) being drawn from the zones are washed and cleaned in related color particle separator devices (12a, 12b) and heated with heaters (22,24) above the respective due points. The solvent loaded discharge air currents (V10, V11) are fed from the evaporation cabin (30) into a combustion plant. The air currents are adjusted in such manner that in the entrance area underpressure exists and a fresh air current (V1) is passing into the cabin (10). A security control and maintainance equipment is described.

Description

The invention relates to a device for applying coating media, e.g. Paint on objects that are conveyed one after the other through several adjoining painting chambers through which an air flow is forcibly guided, the exhaust air of which is in each case passed through a paint particle separating device by means of fans and then the painting chamber adjoining in the conveying direction of the objects and from the last painting chamber for removal the organic liquid vapors is fed to a cleaning system.

From DE-A1-2 404 404 a painting device with several painting chambers is known, to which an air flow is applied, which is led from painting chamber to painting chamber. The exhaust air is guided by a fan over a guard and filter device and fed to the following painting chamber. The total air flow that is required in a painting chamber determines the required air volume flow through the entire device, so that the solvent saturation of the exhaust air at the end of the device that is fed to the cleaning system results from this air flow and the paint consumption, in practice only one insufficient degree of saturation for economical combustion of exhaust air can be achieved. It is necessary to ventilate painting and drying systems in such a way that the paint mist reflected in the paint spraying and the evaporating solvent are removed and the solvent in the exhaust air that leaves the system accordingly does not exceed a concentration that complies with environmental protection regulations , which requires the purification of the exhaust air, which, however, does not cover the costs if the solvent concentration is low, if the energy content is too low for the required heating capacity of the air volume. In addition, there is the disadvantage of this known device that the individual paint booths are largely separated on the input side by silhouette doors so that the air streams of different solvent concentrations do not mix or escape on the input side.

It is also known from DE-A1-3 030 045 to feed a painting chamber with a circulating air stream many times and, after enriching the air with solvent of the coating material to a permissible maximum value, to supply a partial air stream as exhaust air from an incineration plant. The disadvantage here is that a regulating or at least one control device is required which determines the size of the partial air flow. Furthermore, it is necessary that the chamber and spraying device each have to be cleaned in a time-consuming manner in order to coat an object with a plurality of coating media, for example different colors. In addition, the chamber is only suitable for operation with the doors closed, since the highly enriched solution vapors would otherwise escape; this means that it is not possible to arrange the chamber around a conveyor belt when the inlet and outlet are open.

It is an object of the invention to improve the device according to DE-A1-2404404 in such a way that a significantly higher solvent concentration can be achieved and the objects can be coated with the inlet of the painting chamber open without solvent vapors escaping from the inlet.

The solution to the problem is that in each painting chamber at least two ventilation zones are arranged next to one another in the conveying direction of the objects and that the exhaust air from the ventilation zone on the inlet side in the conveying direction of the objects is in each case via a further paint particle separating device by a fan of the outlet-side ventilation zone in the same painting chamber as Another air stream is supplied for this painting chamber and the exhaust air of a painting chamber, which is fed to the subsequent one, is taken from the ventilation zone on the outlet side and the inlet side of the subsequent painting chamber is fed and the exhaust air is fed to the last ventilation zone of the cleaning device and that an inlet air stream is ventilation zone on the inlet side of the first painting chamber is fed, which is lower in relation to the exhaust air flow of this ventilation zone, so that on the inlet side a lower suppression uck exists and another fresh air stream enters through the entrance.

An advantageous embodiment of the device consists of the fact that the air is so often passed through the painting and / or evaporation system as circulating air, the exhaust air discharge being metered in such a way that the maximum solvent concentration reaches the permissible explosion safety concentration, and the number of Circulations in connection with the respective zone width is selected so that the air speed in the painting zones corresponds to a predetermined value and the explosion safety concentration limit is not exceeded in any area.

The device offers the advantageous possibility of directly combusting the exhaust air, which is highly enriched with solvent vapor, without preheating and of supplying the heat released to the drying process. The amount of heat is so great that no further heating energy has to be added to a downstream drying system.

The color particle separation device is advantageously designed as a washing, filtering and drying device. The constant removal and washing out of the paint mist from the air has the advantage on the one hand that hardly flammable and difficult to remove deposits of dye form in the painting zone and that in particular with multiple or Multi-color paints no mixing or overlapping of the colors occur.

Safety circuits on the operating units and accesses enable safe operation and safe inspection of the systems.

A maintenance and operating station and the control device are advantageously designed to be explosion-proof and are arranged in the vicinity outside the systems. This has advantageously made it possible to significantly reduce the size of the coating chamber, which in turn has reduced the air throughput compared to conventional chambers, which leads to correspondingly small circulating air and air purification systems.

1 and 4 show exemplary embodiments for high-performance barrel painting devices for single-color and two-tone painting.

The size of the painting chambers has only been selected so that sporadic manipulation of the barrel spray chairs is possible. To change the color or adjust the spray guns, the spray chairs are moved out of the paint chambers. This enables a high concentration of solvents in the circulating air of the painting chamber, since an operator does not have to be in this zone all the time. The amount of air that has been reduced to a minimum and which is aimed specifically at the spray chairs in order to avoid a fog of paint during spraying has been reduced to an acceptable, technically possible minimum. This air is constantly filtered and washed out in order to be cleaned of adhering paint particles before being blown into the paint chamber in order to avoid any loss of quality on the painted surfaces. During the passage of the air through the painting chamber - the air is used five times, for example - there is a constant increase in temperature in order to avoid condensation of the moisture from the washed-out air on the barrel. The solvents released in the painting area are absorbed into the air. After the air in the painting chamber has been entered in the last stage, it is led into the subsequent evaporation zone. There it continues to take up solvent and is then fed into the furnace itself as furnace fresh air from the furnace entrance lock. The proportion of the supply air that cannot be taken in as fresh air in the furnace is fed directly to the thermal exhaust air purification system as fresh air via a bypass line with a separate fan. It has been made possible to supply the entire circulating air required in the painting process with the solvents escaping from the paint both in the painting zone and in the evaporation zone to the furnace and thus also to the thermal exhaust air purification.

Instead of the vertical air flow shown in the examples, a horizontal one can also be selected. For this purpose, dry filters are suitably used for the separation of color particles.

It is an advantageous variant of the device to arrange fresh air zones between painting chambers, in which people have access to the paint material conveyed there. The adjacent outlet or inlet is operated by a directional nozzle with circulating air, as shown at the transition to the evaporation system, and the amount of exhaust air from the adjacent zone is increased compared to the supply air, so that a certain amount of fresh air enters or the solvent vapor leaves is kept away from this zone.

• Fig. 1 shows a single-chamber painting and evaporation system with double air circulation in the vertical, offset in depth section;
• Fig. 2 shows a two-chamber painting and evaporation system with four-fold air circulation in the vertical, offset section A-A;
• FIG. 3 shows a horizontal section of the plant according to FIG. 2 reduced with the maintenance and control station;
• Fig. 4 shows a diagram of the control device with safety circuit.

1 schematically shows a painting chamber 10 and an evaporation system 30 in which the paint 11, barrels, clocked from production to production, passes from left to right and is then passed directly into a drying oven. The color particle separation device 12a, b are washing towers which are arranged laterally offset to the passage of the barrels 11, as can be seen correspondingly from the horizontal section Fig. 3 line A-A.

In the painting position, in which the warm barrel 11 is shown, it is rotated during the all-round high-pressure spray painting.

So that the reflected paint mist is removed, the barrel 11 is surrounded on all sides from top to bottom by air currents V4a, b at a speed of approximately 0.5 m / s. These air flows totaling 6000 m ³ / h are composed of the fresh air flow V3 of 2500 m ³ / h and a circulating air flow V2 of 3500 m ³ / h and are preheated by fans 21, 19a via heating registers 22, 24 and via distributor filters 23, 25 supplied to the painting chamber 10. A fresh air stream V1 with 100 m ³ / h is additionally drawn in through the entrance of the painting chamber, since the throughput of the circulating air fan 19a is designed to be higher than that of the fresh air fan 21, so that no solvent vapors escape from the painting chamber 10. The fresh air V3 is supplied on the side of the entrance. The circulating air V2 coming from the entrance and the least loaded is drawn off in the entrance half of the chamber bottom 14.

A further air flow V5 of -5000 m ³ / h is drawn off through the right chamber bottom 14 by the fan 19b and, according to the position of an adjustable throttle valve 31 in a partial flow V6, is blown from the evaporation chamber 30 through the passage opening to the painting chamber 10 via a directional nozzle 34 and pressed into the evaporation chamber in a second partial flow V7 of 3500 m ³ / h.

From this the fan V32 draws the exhaust air V8 highly enriched with solvent and leads this in accordance with the position of an adjustable distributor flap 33 in a partial stream V9 back into the evaporation chamber, which corresponds to the outlet stream V11, which is drawn off above the adjacent drying oven and is fed to the evaporative combustion system in a further partial stream V10.

The circulating air streams V2, V5 are each guided through color particle separating devices, washing towers 12a, 12b. The air passes through a grate 14 at the bottom of the chamber and sweeps over the sump 13 to the edge 13b of the wash tower, which is led to the level 13a of the sump surface, which is constantly held by a guard, thereby passing the air under the edge in a vortex, also called a water roller 15, passes into the tower 12a, b and the ink drops are washed out. The water droplets absorbed by the air are then separated out on the baffle plates 16 and the perforated filter 17 and other filters. The cleaned air is then heated in the heating register 24 above the dew point to such an extent that no condensation occurs during the expansion in the following chamber pass. The water in the sump 13 contains a coaling agent for paint mist.

Further details are shown in FIG. 2, in which similarly equipped painting chambers are arranged one behind the other, the exhaust air from the first painting chamber being passed twice through the second painting chamber. The reference numerals are chosen accordingly as in Fig. 1 and partially differentiated by attached letters. Transport rails 40, on which the barrels roll from one spraying station to the other, run through the painting chambers 10a, b.

During the spraying, the barrels are stored on barrel chairs 41 and are driven by rollers 42, so that they are uniformly painted on all sides. In the present case, different colors are applied (in separate strips) in the two painting chambers. A sharp demarcation is made by stencils near the barrels (not shown) and the removal of the paint mist through the air. The barrel chairs are mounted on rollers 62 with rollers 63 and can be moved out of the painting chambers for operating and maintenance purposes.

At the bottom of the sump 13 there is a conveyor belt 60, which is led out on one side and is used to discharge the washed-out paint sludge.

After painting, the barrels are set up and transferred to a roller conveyor 43 and transported in cycles through the evaporation system until they are conveyed into the drying oven by the conveyor belt 44.

Behind each fan 19a, b, c there is a ventilation flap 50 which can be controlled by a signal S19 and which, in the event that cleaning of the system is necessary, allows rapid ventilation into the exhaust air pipes 51. The position of the flaps is communicated to the control device 70 by detectors via signal lines M50.

In Figure 3 there is a horizontal crack of the system of Fig. 2, from which it can be seen that the 4 washing towers 12a to d are alternately laterally offset from the painting chambers and the transport route of the barrels. The air duct 64 effect the assignment of the air emerging from the respective zone below to the associated wash tower. For the accessibility of the painting chambers and for the extension of the spray chairs 41a, b, safety doors 61 are attached, which can be opened from the inside at any time and from the outside only when the door lock is released by a control signal S61 from the control device 70. In addition, all the doors 61 are monitored by a closing control, the signal M61 of which is evaluated in the control device 70.

The control device is arranged in a cabinet next to the painting chambers between the maintenance areas of the spray chairs. It carries a control panel and control panel 73, from which the functions of the spray guns, the transport drives, the fans and flap drives are controlled and the alarm signals are received via the compressed air lines and cables 72.

For explosion protection, the cabinet is airtight and supplied with compressed air from outside the safety zone 63 via a pressure regulator 74 and monitored by a pressure switch, so that no air containing solvent can enter it and explosions cannot be ignited.

At the entrance of the evaporation chamber 30 there is the barrel erecting device and conveyor system 46. The step-by-step roller conveyor 43 transfers four times in parallel to a correspondingly slower roller conveyor 45, on which the solvent is largely evaporated.

When the system is fully sprayed, 3500 m ^{3 of} exhaust air with a concentration of 20 g / m ^{3 of} solvent are emitted per hour, which corresponds to a calorific value of 50 m ³ / h of heating gas. If thicker layers of paint are applied, even higher concentrations, e.g. B. 30 g / m ³ arise.

4, the control device 70 is shown schematically. It is connected to the control display and control panel 73 and is clocked by a clock C. Furthermore, the control device receives the message signals Mx, which are emitted by the modules indicated by the associated reference symbols, and emits the control signals Sx, which are also identified by corresponding reference symbols.

Before the spray guns are started up by signal SS, the following message appears: Doors closed M61; Vent flaps closed M50; Fans 19, 32 in operation M19, M32; Cabinet pressure available M75, and water level available M13, checked for presence. Otherwise, the missing messages are displayed and spraying is not started or stopped.

If an inspection is required by actuating the operating device, spraying is stopped via signal SS and the vent is opened via signal S50.

The fans remain active via signals S19 and S32. If working for a specified safety time is determined via signals M19, M32, the door locks are released via signal S61.

In addition, the pressure regulator 74, the transport drives, the throttle valves 31, 33 and the water level 13a are controlled or regulated and monitored via the signals M74, MT, M31, M33, M13a and the associated signals S74, ST, S31, S33, S13a , which ensures a completely safe operation of the system.

Claims (7)

1. Apparatus for applying coating medium, e.g. spray paint, to target objects (11), which are conveyed in sequence through several adjoining spray-booths (10, 10a, 10b), through which there is a forced circulation of air (V4a), and where the outgoing air (V5, V7) is directed by ventilators (19c, 19d) through the respective paint particle separator device (12a, 12c), and is subsequently channelled in the transport direction of the target objects (11) to the adjoining spray-booth (10b), and from the last spray booth (10b) to a cleaning apparatus for the removal of organic liquid vapors, characterized by the fact that in each spray-booth (10, 10a, 10b) at least two aeration zones are located adjacently in the transport direction of the target objects (11), and that the outgoing air (V3) of the inlet side aeration zone is forced in the transport direction of the target objects (11) via an additional respective paint particle separator device (12a, 12d) by a ventilator (19a, 19d) to the outlet side aeration zone in the same spray-booth (10, 10a, 10b) as an additional circulation of air (V4b) for this spray-booth (10, 10a, 10b), and respectively the outgoing air of one spray-booth (10a), which is directed to the adjoining booth, is taken from the outlet side aeration zone and is directed to the respective inlet side of the adjoining spray-booth (10b), and the outgoing air (V10, V11) from the last aeration zone of the cleaning apparatus, and that a flow of inlet air (V3) is directed to the inlet side aeration zone of the first spray-booth (10, 10a), which quantitively is less than the flow of outgoing air (V2) from this aeration zone, with the result that a partial vacuum is created at the inlet side, and an additional flow of fresh air (V1) enters through the inlet.

2. Apparatus according to claim 1, characterized by the fact that the paint particle separator device (12a, 12b, 12c, 12d) consists of a washing unit with a water roller (15), water separators such as impact plates (16), perforation filters (17) and/ or fiber filters (18), to which a ventilator (19a, 19b) is connected, of which the air line on the discharge side leads to a distributor box (20) which contains a heating register to heat the air above the dew pointforthe individual spray-booths (10a, 10b) and aeration zone.

3. Apparatus according to claim 1, characterized by the fact that an evaporation unit (39) with an open aperture is connected to the last spray-booth (10b) in the direction of transport, and the outgoing air (V5) from the last spray-booth (10a, 10b) is directed to the evaporation unit (30) via the paint particle separator device (12b), whereby a partial air flow (V6) is channelled through a controllable regulator (31) and a direction nozzle (34), which points diagonally and preferably from above against the aperture of the spray-booth into the evaporation unit (30), and whereby the outgoing air (V10, V11) from the evaporation unit (30) is directed to the combustion unit.

4. Apparatus according to claim 3, characterized by the fact that an air discharge ventilator (32) is connected to the evaporation unit (30), which features a distribution flap (33) located in the outlet line, which distributes the flow of air (V8) between a circulation and an outlet line.

5. Apparatus according to one of the previously specified claims, characterized by the fact that controllable air outlet flaps (50) are located in the circulation lines, which when in the open position interrupt the circulation flow and lead to an air outlet line (51), and by the fact that the air outlet flaps (50) are equipped with position indicators.

6. Apparatus according to one of the previously specified claims, characterized by the fact that a spray device, preferable a drum stool (41), is located in each of the spray booths (10, 10a, 10b) in the working position, which carries a drive unit (42) for a drum which runs with rollers (63) on rails (64) which lead through a safety door (61) in the booth wall to a waiting point next to the spray-booth (10).

7. Apparatus according to claim 6, characterized by the fact that a control unit (70) with a display and operation panel (71) is located next to the waiting point at the spray devices (41), which is connected to the controllable units (31, 33, 61, 50), the transport devices (40, 43, 44), the drives (42) and spray devices over control lines (Sx) and status signal lines (Mx) by cable and/or compressed air lines (72), and which are connected to a clock (C) and are accommodated in an air-tight cabinet which contains a pressure control device (75) which is also connected to the control unit (70) via a signal line (M75), and that the interior of the cabinet is connected via a pressure regulator (74) to a compressed air inlet line (71) which leads from outside the explosion-proof limit, and that the spray device is only actuated by the control signal (SS) when the status signals (M50, M61, M19, M32, M75, M13a), the connected status of the air outlet flaps (50), the safety doors (61), the running of the ventilators (19a, 19b, 19c, 19d; 32), pressure in the cabinet (70) and the current water level (13a) are received.

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