EP2755773A1

EP2755773A1 - Method for separating overspray

Info

Publication number: EP2755773A1
Application number: EP12756111.6A
Authority: EP
Inventors: Michael Schlipf
Original assignee: Eisenmann SE
Current assignee: Eisenmann SE
Priority date: 2011-09-17
Filing date: 2012-09-05
Publication date: 2014-07-23
Also published as: US20140338533A1; CN103702770A; DE102011113708B4; WO2013037461A1; BR112014006384A2; BR112014006384A8; DE102011113708A1; RU2014103966A

Abstract

In a method for separating overspray produced during the painting of objects, the overspray is absorbed by an air flow and transported to a separating surface (26) of a separating device (16) over which a separating liquid (58) flows. In said process, a large part of the overspray merges with the separating liquid, is transported away by said separating liquid, and is removed from the separating liquid by separation. Separating liquid (58) is fed to the separating surface (26) by means of a dispensing device (32), which is arranged in such a way that the total discharge mass flow (GM) of the separating liquid (58) is dependent at least on the viscosity of the separating liquid (58). Furthermore, separating liquid (58) having a predetermined inlet mass flow (ZM) is fed to the dispensing device (32), wherein the inlet mass flow (ZM) of the dispensing device (32) is equal to the total mass flow (GM), and the viscosity of the separation liquid (58) during the operation of the separation device (32) is calculated.

Description

Method for separating overspray

The invention relates to a method for depositing overspray resulting from the coating of objects by means of a separation device, in which a) the overspray is taken up by an air stream and transported to a separation surface of the separation device which is overflowed by a separation liquid, a large part at least of the overspray solids the separation liquid passes, is transported away from it and removed by separation from the separation liquid; b) the separating surface is supplied to separating liquid by means of a dispensing device which discharges Abscheideflüssigkeit with a total discharge mass flow and is arranged such that the Gesamtaustrag- mass flow of the Abscheideflüssigkeit depends at least on the viscosity of the Abscheideflüssigkeit; wherein c) the discharge device separating liquid is supplied with a pre ^¬ given inlet mass flow.

With manual or automatic application of coatings on items a partial flow of the paint, of my ^¬ in general will contain both solid as well as solvents and / or binding ^¬ medium, not applied to the object. This partial flow is called "overspray" in the professional world. The overspray is detected by the air flow in the spray booth and fed to a separation. Especially in systems with a larger paint consumption, for example in systems for painting vehicle bodies, preferably wet separation systems are used, in which method of the type mentioned are used.

In order for the paint particles picked up by the separating liquid to be able to be guided away from the separating surface without any problem, the separating liquid must fulfill special criteria. These include, for example, that the adhesive effect of the paint particles must be repealed so that they, if they come through the Abscheideflüssigkeit with the Abscheidefläche in contact, not adhere to this.

A method of the aforementioned type is known for example from DE 10 2008 046 409 B4 or DE 10 2008 046 414 AI, where for this purpose a water-based or oil-based Abscheideflüssigkeit with entklebenden properties with respect to the overspray particles is used. There, the Abscheideflüssigkeit is conveyed via a feed line into a tub and discharged from it by means of rotating rollers, which protrude into the Abscheideflüssigkeit.

It should be ensured as uniform as possible and runner and nasenfreie wetting of Abscheidefläche and it is particularly desirable that the Abscheideflüssigkeit can flow down largely laminar at the Abscheidefläche, i. that a thin film forms on the separation surface, which moves evenly downwards.

The latter properties depend strongly on the viscosity of the separating liquid, which should therefore be monitored during operation of the separating device. This is done, for example, in DE 10 2008 046 409 B4 by a conventional viscometer, by means of which, in the inlet of the separator, Separating liquid to the dispensing device, the viscosity of the separating liquid is determined.

In practice, the separating ^{liquid is} guided in a circuit ^¬ run and regenerated after receiving the overspray particles on the separation surface of the separator. Even after the regeneration, however, paint residues are still distributed in the separating liquid. These can cause the sensors of the viscometers to be disturbed and the viscosity measurement leads to erroneous measurement results.

Alternatively, samples of the recirculating liquid can be taken and measured. Here, however, the apparatus and personnel expenses are quite large.

It is therefore an object of the invention to develop a method of the type mentioned in such a way that a reliable determination of the viscosity of the Abscheideflüssigkeit can take place during operation of the separation device, without causing the above-mentioned difficulties.

This object is achieved in a method of the type mentioned above in that d) the separation device is operated such that the inlet mass flow of the dispenser is equal to the Gesamtaustrag mass flow of the dispenser and calculates the viscosity of the Abscheideflüssigkeit during operation of the separator becomes.

According to the invention it has been recognized that the viscosity of separating liquid can be calculated when the amount of the discharged separating liquid is dependent on the visco sity ^¬ as the in the rolling principle of the prior Technique for example is the case. This will be discussed further below.

Consequently, it is favorable if the discharge of separation liquid to the separation surface takes place by means of at least one roller projecting into the separation liquid and the discharge mass flow is AM = cv _w η, where c is a proportionality factor, v _w the rotational speed of the roller and η the viscosity the separating liquid is.

It may be advantageous if the discharge device feeds the separation surface in a first manner with a discharge mass flow which depends at least on the viscosity of the separation liquid, and the discharge device discharges separation liquid in at least a second manner with a secondary mass flow and the secondary mass flow during operation of the separation device is measured with a measuring device. In the case of the above-mentioned roller principle, the discharge via the rollers represents, for example, the supply of the separating liquid to the separation surface. The delivery by a second mode can then be provided, for example by an overflow, so that the level of the separating liquid in the trough remains largely constant.

Embodiments of the invention will be explained in more detail with reference to the drawing. In this show:

1 shows a painting booth of a surface treatment plant with an overspray separation device in one

Front view;

FIG. 2 is a perspective view of two separation units and three electrode units of the separation device of FIG. 1; FIG. 3 shows a section of a delivery device of the separation units, by means of which separation surfaces of the separation units a separation liquid can be supplied, along the section line III-III in FIG. 4;

Figure 4 is a section with partial view of the dispenser along the angled section line IV-IV in Figure 3;

Figure 5 schematically shows a first embodiment of a

Device for determining the amount of separating liquid lost by overflow per unit time;

6 shows schematically a second embodiment of a

Device for determining the amount of separating liquid lost by overflow per unit time.

First, reference is made to FIG. 2, a painting booth of a surface treatment installation is designated therein, in which vehicle bodies 4 are painted, after they have been placed in the painting booth 2 upstream, not specifically shown pretreatment stations, e.g. cleaned and degreased.

The painting booth 2 comprises an overhead painting tunnel 6, which is bounded by vertical side walls 8 and a horizontal cabin ceiling 10, but is open on the front sides and downwards in such a way that cabin exhaust air laden with overspray can flow downwards. The cabin ceiling 10 is formed in the usual way as a lower boundary of the air supply space (not shown) with filter cover. To be painted vehicle bodies 4 can be transported by means of a conveyor system 12, which will not be discussed here in detail, from the input side of the painting tunnel 6 to its output side. Inside the painting ^¬ tunnels 6 are not specifically shown application devices, by means of which the vehicle bodies 4 can be applied in a manner known per se with paint.

Below a lower opening of the painting tunnel 6 is an upwardly to the painting tunnel 6 open towards the separation chamber 14, in which is formed during painting paint overspray.

In the separation chamber 14, a separation device 16 is arranged with a plurality of in the longitudinal direction of the separation chamber 14 successively arranged separation units 18, which will be discussed in more detail below.

The cabin air coming from the painting tunnel 6 and laden with overspray is directed via air guide plates 20 to the separating device 16 and flows through them from top to bottom, being freed from entrained overspray particles. Thereafter, the cleaned cabin air passes into a discharge area 22 formed by air baffles, which is arranged below the separation device 16 and from where it, optionally after a certain conditioning, the paint tunnel 6 can be supplied again as fresh air. The conditioning may in particular be a readjustment of the temperature, the humidity and possibly the removal of solvents still in the air.

FIG. 2 shows two adjacent separation units 18 of the separation device 16. As can be seen there, A separating unit 18 comprises two mutually spaced parallel rectangular side plates 24. The respective outer surfaces of the side plates 24 form Abscheideflächen 26 at which flows down a Abscheideflüssigkeit during operation of the separator 16 from the top down, which is suitable, solid particles from the paint resulting from the painting process -Overspray record.

The side plates 24 are connected to each other at their upper opposite end edges by a curved portion 28, whose clear outer contour corresponds in cross-section to a semicircle and which forms the top of the separation unit 18.

At the apex of the curved portion 28 of the separation units 18, this is formed to a bearing groove 30 open at both ends, in which a discharge device 32 is arranged, by means of which separation liquid can be supplied to the separation surfaces 26 and of which an embodiment for the sake of clarity only in the figures 3 and 4 is shown. This will be discussed in more detail below.

At their lower edges, the side plates 24 each carry a gutter 34, which runs parallel to the side plates 24 of the separation units 18 and is inclined downwards in the direction of an end face 36 of the separation unit 18.

As can be seen in FIG. 1, a collecting channel 38 is provided at the lower end of the drainage channels 34 arranged there, into which the separating liquid flows and which extends in the longitudinal direction of the painting booth 2. About this collection channel 38 laden with overspray particles deposition liquid flows from the La 2 and can be a cleaning and reprocessing, in which the separating liquid is freed from the Overspraypartikeln. The separation liquid thus regenerated is then returned to the separation device 18 in a cycle.

In the separation apparatus 16 each pair of adjacent separation units 18 are arranged maintaining a distance from one another ^¬. Between two adjacent separation units 18 as well as the free side plates 24 of the two outermost separation units 18 within the separator 16, respectively, an electrode device 40, each of which is connected to a high voltage ^¬ source 41 extends. Alternatively, the electrode means 40 may be powered by a single high voltage source. The separation units 18 are connected to ground potential.

When painting the vehicle bodies in the painting tunnel 6, the cabin air located there is loaded with paint Overspraypartikeln. These may still be liquid and / or sticky but also more or less firm. The laden with paint overspray cabin exhaust air flows through the lower opening 12 of the painting tunnel 6 in the separation chamber 14th

There, this air is directed through the air baffles 20 in the direction of the separation device 16 and flows between adjacent separation units 18 in the direction of the outflow region 22.

The electrode devices 40 are set up in such a way that corona discharges occur in a manner known per se, by means of which the overspray particles in the passing exhaust air of the cabin are effectively ionized. The ionized overspray particles then pass through the ground potential side plates 24 of two adjacent Abscheideeinheiten 18 and extending therebetween electrode means 40. Due to the electrical field formed there, the ionized overspray particles are deposited on the Abscheideflächen 26 of the side plates 24 of the separation units 18 and are there from the taken along along flowing Abscheideflüssigkeit.

In the figures 3 and 4, an embodiment of the dispenser 32 is now shown in detail.

At each end face of the bearing groove 30, a bearing unit 42 is attached. The bearing units 42 support two rollers 44, 46 which extend parallel to each other in the longitudinal direction of the bearing groove 30 while maintaining a distance in a horizontal plane.

The rollers 44, 46 can be driven by not shown here drive means such that they rotate with different rotational direction. In FIG. 3 this is shown by corresponding arrows.

The rollers 44, 46 protrude with a lying below the plane defined by their axes of rotation 48 area in a trough 50, which can be filled with the Abscheideflüssigkeit so that the rollers 44, 46 then submerged in some areas in the Abscheideflüssigkeit. The tub 50 is attached via not specifically shown connecting members in the bearing groove 30. On both sides of the tub 50 spring plates 52 are arranged, which serve as drainage surfaces for the Abscheideflüssigkeit. The spring plates 52 lie with a respective upper outer edge on the outer circumferential surface of the rollers 44, 46 and with a respective opposite lower outer edge of the curved portion 28 of the Abscheideinheit 18 at. Separating liquid is thus stripped off at the rotation of the rollers 44, 46 on the spring plate 52 and flows over this as a continuous layer on both sides of the curved portion 28 of the Abscheideinheit 18 and from there as a continuous layer to the Abscheideflächen 26th

The trough 50 is fed from below via a feed line 56 provided with a throttle valve 54 with the separating liquid coming from a reservoir 57 shown only in FIG. 3, and the rollers 46 dive into the separating liquid. This can be seen in Figures 3 and 4, where the Abscheideflüssigkeit 58 and the liquid level in the tub 50 is designated 60. In Figure 4, the tub 50 in phantom and projecting into the tub 50 part of the roller 44 is shown in dashed lines.

On one end face of the separation unit 18, the trough 50 has an overflow trough 62, via which separating liquid 58 flows out of the trough 50 when the liquid level 60 of the separating liquid 58 reaches a certain level. So that the liquid level 60 of the separating liquid 58 inside the channel 50 is always high enough for the rolls 44, 46 to always immerse in the separating liquid 58, the tank 50 is continuously supplied with as much separating liquid 58 as it is discharged through the rolls 44, 46 and the overflow trough 62 is discharged from the tub 50. The rate of capture liquid into gutter 50 is determined by means of a flow meter 64, as known per se and located in the feed line 56.

The dispenser 32 thus provides separation liquid 58 in a first manner, namely via the rollers 44, 46, and in a second manner, viz Overflow trough 62, from. The total quantity of separating liquid 58 which emerges from the trough 50 per unit of time is thus the sum of the discharge through the rolls 44, 46 and the separating liquid 58 flowing out via the overflow trough 62.

As a conveying quantity of the mass flow in kg s ^"1 is taken as a basis here. Thus, the delivery device is from 32 separating liquid 58 through the rollers with a Discharge mass flow AM and the overflow channel 62 with a Ne ben mass flow NM. The sum of the discharge By measuring the overflow quantity of separating liquid 58 per unit time, ie, the secondary mass flow NM of the separating liquid, it is possible, with knowledge of the inflow quantity per unit of time as inflow mass flow ZM, to determine the outflow mass AM and secondary mass flow NM - amount applied over the rollers 44, 4, 6 and above are determined 58, the viscosity of separating liquid, which further un ^¬ th will be explained in detail this, the overflow channel 62 58 performs the separating liquid to a Messein ^¬ direction 66. Figure 5 shows the first.. embodiment of the measuring Rich ^¬ tung 66 is a flow-measuring device 68th This comprises a tube 70 syphonartiges, in which a measuring space 72 is arranged with a paddle wheel 74, which is traversed by the Ab ^¬ separating fluid 58. The tube 70 is ex sheath liquid 58 from the two downcomers 32 of a separation unit 18, for example via a non-egg ^¬ gens shown here, hopper at an upper inlet end 76 supplied ^¬ leads, flows through the pipe 70 and leaves it via an off ^¬ sheeting 78, from where it is conducted into the collecting channel 38 of the separation device 16. The flow rate through the Pipe 70 and thus the amount of overflow per unit time of Abscheideflüssigkeit 58 from the trough 50 of the dispenser 32 of each considered Abscheideinheit 18 is proportional to the speed of the impeller 74; This is detected by a speed sensor 80, which is indicated only schematically in FIG.

FIG. 6 shows, as a second exemplary embodiment of the measuring directions 66, an interval measuring device 82. In this case, the separating liquid 58 flows via the overflow channel 62 out of the trough 50 into an intermediate container 84, which has an upper inlet 86 for this purpose. The bottom 88 of the intermediate container tapers like a funnel to an outlet 90, which can be selectively released or closed via a diverter valve 92.

The interval measuring device 82 also includes a level sensor 94 that communicates with a valve controller 96. Whenever the level of the deposition liquid 58 in the surge tank 84 reaches a predetermined maximum level, the level sensor 94 outputs a corresponding output signal to the valve controller 96, which then opens the valve 92. Abscheideflüssigkeit 58 now flows through the outlet 90 from the intermediate container 84 and is guided into the collecting channel 38 of the separator 16.

If the Abscheideflüssigkeit 58 in the intermediate container 84 then also reaches a predetermined minimum level, a corresponding output signal of the level sensor 94 causes the valve 92 is closed. The level of the settling liquid 58 in the surge tank 84 then rises again and the cycle begins again.

Instead of detecting a minimum level, the valve 92 can also be kept open only for a sufficiently long time, so that it is ensured that the intermediate container 84 is completely emptied when re-closing the valve 92. From the period between the closing and the opening of the valve 92 results in knowledge of the measuring volume of the interval measuring device 82, the amount of overflow per unit time of Abscheideflüssigkeit 58 from the trough 50 of the dispenser 32 of each considered Abscheideinheit 18. The measuring volume of the interval measuring device 74th is the volume in the intermediate tank 76 between the minimum level and the maximum level.

Values of the overflow quantity per unit of time of the delivery device 32 and also changes of the overflow quantity over time can thus be determined and recorded over time with both the flow meter 68 and the interval meter 82. With the above-mentioned flow meter 64 in the feed line 56, the inflow amount of separating liquid into the trough 50 of the dispenser 32 and, as a result, also changes in the inflow amount over time can be detected and detected.

Knowing the flow rate of separating liquid into the sump 50 of the dispenser 32 and knowing the amount of overflow of separating liquid from the sump 50 of the dispensing device 32, the viscosity of the precipitating liquid can now be calculated as follows:

As noted above, the total discharge mass flow GM to settling liquid of the dispenser 32 is the sum of the discharge mass flow AM through the rollers 44, 46, ie, through the rollers 44, 46 from the tub 50 per unit time discharged amount of the separating liquid, and the secondary mass flow NM in the form of the amount of separating liquid flowing out of the tub 50 via the overflow trough 62.

Separating liquid is supplied to the separation surfaces 26 with the discharge mass flow AM = dm _A / dt [kg s ^_1 ].

The discharge mass flow AM is proportional to the circulation speed v _w [ms ^"1 ] of the rollers 44, 46 and to the viscosity η [kg m ^_1 s ^{" 1} ] of the separating liquid. The Um ^¬ running speed of the rollers 44, 46, the speed at which the roller surface of the spring plate 52 passes. V _w = 2 π fr, where f is the speed [s ^_1 ] and r is the radius [m] of the rollers 44, 46.

Thus, AM = cv _w η. The proportionality constant c [s ^_1 ] depends, inter alia, on the specific design of the delivery device 32, for example on the specific design of the spring plates 52.

This means that the discharge mass flow AM is, for example, the greater the viscosity η of the separating liquid, given an unchanged circulation speed v _{w of} the rollers 44, 46, for example. With a higher viscosity η adheres to the circulation of the rollers 44, 46, a larger amount of Abscheideflüssigkeit on the rollers 44, 46 and is promoted by these to the spring plates 52, as at a lower viscosity η the Abscheideflüssigkeit. In other words, the discharge mass flow AM of the separation liquid changes as its viscosity η changes.

Since the discharge mass flow AM depends on the viscosity η of the separating liquid, the total discharge mass flow GA also depends on the viscosity η of the separating liquid from. In general terms, the dispensing device 32 thus discharges separating liquid with the total discharge mass flow GM and is set up such that the total discharge mass flow GM of the separating liquid depends at least on the viscosity η of the separating liquid 58.

The secondary mass flow NM of separating liquid from the trough 50 of the discharge device 32 is NM = dm _NM / dt [kg s ^"1 ] The inflow mass flow of separating liquid into the

Tray 50 of the dispenser 32, ie, the amount of trapping liquid flowing into the tray 50 from the reservoir 57 per unit time is accordingly ZM = dm _ZM / dt [kg s ^"1 ].

In the well 50, the level 60 of the deposition liquid 58 remains in equilibrium when the condition

ZM = GM = AM + NM is satisfied. The separation device is thus operated such that the inlet mass flow ZM is equal to the total discharge mass flow GM. Then the viscosity of the separating liquid can be calculated during the operation of the separating device 16, in that:

ZM - NM = AM = cv _w η and η = (ZM - NM) / (cv _w ).

The viscosity of the separating liquid reflects two important and necessary for a smooth operation of the Abscheideflu- sigkeit of the separating liquid resist: first, the separating liquid must be in a viscosity range at which it is ensured that the separating the separation surfaces 26 a From ^¬ distinction unit 18 overflows as a continuous layer and it involves at any tearing of the layer. Otherwise, for example, unwanted voltage flashovers could occur between the side plates 24 of the separation unit 18 and the electrode devices 40 of the separation device 16. This must be avoided in particular in explosion-protected areas such as paint shops.

A good flow behavior of the separating liquid can be achieved with a viscosity of the separating liquid, which with a flow cup according to DIN EN ISO 2431, German version EN ISO 2431: 1996, from 1996 with an outlet opening of 6 mm diameter, to a measurement between 2 and 100 seconds, preferably between 5 and 20 seconds and particularly preferably at 10.5 seconds leads.

In addition, the viscosity of the trap liquid provides insight into whether the above-mentioned regeneration of overspray-laden trap liquid has been successful. The viscosity of the deposition liquid changes when overspray particles are dispersed therein.

The inlet mass flow ZM is set during operation of the separation device 16 and monitored by means of the flow meter 64, so that the inlet mass flow ZM is known. The secondary mass flow NM is determined during the operation of the ex ^¬ distinguish device 18 with the measurement device 66 and monitored and is therefore also known.

From these values, the viscosity .eta. Of the precipitating liquid can now be determined during the ongoing operation of the precipitator. Device 16 is calculated and thereby monitored. Undesirable changes in the precipitation liquid, which are reflected in a change in their viscosity, can be counteracted directly by treating the precipitating liquid in the reservoir 57 to recover its original composition.

In a modification, it is also possible to dispense with the overflow channel 62 and the determination of the secondary mass flow NM of the separating liquid. In this case, separation liquid from the tub 50 is discharged only via the rollers 44, 46. For example, the equilibrium level 60 in the well 50 may be maintained by monitoring a level sensor for the level of the precipitating liquid in the tub 50 and increasing or decreasing the mass flow of the precipitating liquid via the supply line 56 when the level 60 reaches a lower or upper threshold level ,

In this case, the total discharge mass flow GM of the discharge device is equal to the roll discharge mass flow AM and the secondary mass flow NM is omitted in the above calculation, so that out

ZM = GM = AM = cv _w η for the viscosity of the separating liquid η = ZM / (cv _w ).

Claims

claims

1. A method for separating overspray resulting from the coating of objects by means of a separation device (32), in which a) the overspray is taken up by an air stream and transported to a separation surface (26) of the separation device (32) which is overflowed by a separation liquid (58) wherein a majority of at least the overspray solids pass into the deposition liquid (58), are transported away therefrom, and are removed by deposition from the separation liquid (58); b) the separation surface (26) Abscheideflüssigkeit (58)

is supplied by means of a dispensing device (32) which delivers separating liquid (58) with a total discharge mass flow (GM) and is set up in such a way that the total discharge mass flow (GM) of the separating liquid is at least equal to the viscosity (η) of the separating liquid ( 58) depends; wherein c) the discharge device (32) Abscheideflüssigkeit (58) with a predetermined feed mass flow (ZM) is supplied, characterized in that d) the separation device (32) is operated so that the inlet mass flow (ZM) of the dispenser ( 32) is equal to the total mass flow (GM) and the viscosity act (η) of the separation liquid (58) during operation of the separation device (32) is calculated.

A method according to claim 1, characterized in that the discharge of Abscheideflüssigkeit (58) to the Abscheidefläche (26) by means of at least one in the Abscheideflüssigkeit protruding roller (44, 46) and the discharge mass flow AM = cv _w η, where c Proportionality factor, v is the peripheral speed of the roller and η is the viscosity of the separating liquid (58).

The method of claim 1 or 2, characterized in that the discharge device (32) the Abscheidefläche (26) Abscheideflüssigkeit (58) in a first manner with a discharge mass flow (AM) supplies, which at least the viscosity (η) of the Dependent liquid (58) depends, and the discharge means (32) Abscheideflüssigkeit in at least a second manner with a secondary mass flow (NB) and outputs the secondary mass flow (NB) during operation of the separation device (16) with a measuring device (66) is measured.