JP2018153782A - Wet coating booth circulating water treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet coating booth circulating water treatment device capable of sucking a coating sludge with a device whose mouthpiece position can be moved, removing a settled sludge of a pit, and making it unnecessary to periodically clean the pit.SOLUTION: There is provided a wet coating booth circulating water treatment device, including: a pit that accepts wet coating booth circulating water; suction means for sucking and recovering a coating sludge, having a suction port movable in water in the pit; a reaction tank into which water sucked by the suction means is introduced; means for adding a medicine to the water to be introduced or having been introduced into the reaction tank; stirring means provided in the reaction tank; a floating separator for introducing reaction water from the reaction tank, and floating and separating the sludge and treated water; returning means for returning the treated water from the floating separator to the circulating water pit; and discharge means for discharging sludge from the floating separator.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wet paint booth circulating water treatment apparatus for separating paint sludge from wet paint booth circulating water containing a solvent-based paint.

  Spray painting is performed in the painting process of automobiles, electrical equipment, metal products, etc., and a large amount of overspray paint (excess paint) that does not adhere to the object is generated. The amount of generation reaches about 50% to 60% of the paint used except for electrostatic coating with high coating efficiency. Therefore, it is necessary to remove and recover excess paint from the environment of the painting process. In order to collect surplus paint, a wet paint booth by washing with water is usually adopted, and the washing water is circulated. In this case, in order to prevent the paint from remaining and accumulating in the circulating water, circulation is performed. Coagulating and separating excess paint in water has been performed.

  The paint is roughly classified into a solvent-based paint using only an organic solvent such as thinner and a water-based paint using water. Solvent-based paints are superior to water-based paints in terms of weather resistance and chipping resistance, and are often used especially in automotive top-coat clear coatings. Since the particles of the paint particles are highly sticky, there is a problem in that they adhere to various facilities and cause severe stains, or agglomerate into large clumps and easily clog.

  For this reason, it is important to make the solvent-based paint non-tacky when aggregating the wet paint booth circulating water containing the solvent-based paint.

  In JP-A-11-290864, a tackifier is added to the drainage of a wet paint booth (water curtain type) pit, partitions are provided at the bottom and top of the pit, and the floating sludge and sediment of the tack-free paint A facility is described in which sludge is continuously sucked together with circulating water, solid-liquid separation is performed with a filter to recover solids, and treated water is returned to the pits. However, as described in this document, sedimentation of precipitated sludge is inevitable, and regular cleaning is necessary.

JP-A-11-290864

Patent Document 1 has the following problems.
(1) As described above, sedimentation of settled sludge is unavoidable, and regular drainage cleaning is necessary for stable operation of the booth.
(2) In the drainage cleaning of the precipitated sludge, the precipitated sludge is often sucked with a vacuum, and in this case, the moisture content of the sludge is high and the amount of waste is enormous.
(3) Precipitation sludge suction can remove only sediment deposition sludge in the immediate vicinity of the suction mouth when the suction mouth is at a fixed position, and stably removes sediment deposition to such an extent that there will be no problem with booth operation for a long time. It is not possible to do so, and drainage cleaning is necessary.
(4) Accumulated sludge is often sludge-like, and it is very difficult to suck this together with water and separate it into solid and liquid using a filter because clogging prevents sufficient filtration speed. It is.

  The present invention provides a wet paint booth circulating water treatment device capable of sucking paint sludge with a device that can move the suction port, removing sediment sludge from the pit, and making periodic cleaning of the pit unnecessary. The purpose is to provide.

The wet paint booth circulating water treatment apparatus of the present invention has a pit for receiving the wet paint booth circulating water and a suction means for sucking and collecting the accumulated paint sludge, which has a suction port movable in the water in the pit. A reaction tank into which the water sucked by the suction means and paint sludge are introduced, a means to be introduced into the reaction tank or to add a chemical to the introduced water, and the reaction tank. An agitation means, a levitating separation apparatus in which reaction water is introduced from the reaction tank and levitated and separated into sludge and treated water;
Discharging means for discharging sludge from the floating separator.

  In one aspect of the present invention, the stirring means is a pump that sucks air in the vicinity of the water level in the reaction tank and discharges the air into the reaction tank.

In one embodiment of the present invention, the drug is at least one or both of a polymer flocculant and a tackifier.
In one aspect of the present invention, a turbidity sensor that detects turbidity of water is provided in at least one of the suction unit, the reaction tank, and a path from the suction unit to the reaction tank. Control means for controlling at least one of the position of the suction port and the addition amount of the medicine according to the detected value is provided.

  In the apparatus of the present invention, the paint sludge accumulated in the pit is sucked by the suction means and subjected to the floating separation process. According to the present invention, periodic cleaning of pits can be eliminated. According to one embodiment of the present invention, by performing appropriate solid-liquid separation, the water content of recovered sludge can be reduced, and the amount of waste can be reduced.

It is a block diagram of the processing apparatus of the wet paint booth circulating water which concerns on embodiment.

  Hereinafter, with reference to FIG. 1, the processing apparatus for the wet paint booth circulating water which concerns on embodiment is demonstrated. Return water (paint-containing water) from the wet coating booth is introduced to one end side of the pit 2 through the pipe 1. A pipe 10 for taking out water is provided on the other end side of the pit 2.

  The inside of the pit 2 is divided into four zones 2a, 2b, 2c, and 2d by standing walls 3 and 4 that rise from the bottom surface, and a hanging wall 5 that is provided in a vertical direction so as to be submerged from above the water surface to below the water surface. Yes. The upright walls 3 and 4 and the hanging wall 5 are provided in parallel to each other. These directions are perpendicular to the direction connecting the one end and the other end (left end and right end in the figure) of the pit 2. The hanging wall 5 is located approximately in the middle of the standing walls 3 and 4.

  Float pumps 7 and 8 are disposed in the zones 2b and 2c, respectively. The float pump 7 is preferably located in the zone 2b, but the float pump 8 may be located in the zone 2d.

  A paint detackifying agent can be added to the zone 2 a of the pit 2 by an adding device 9.

  A suction pipe 15 is inserted from above the water surface to near the bottom so as to suck the sludge S accumulated at the bottom of the pit 2. The tip of the suction tube 15 is a suction port 15a. A pipe 19 for supplying backwash water or backwash air is connected to the upper portion of the suction pipe 15. The pipe 19 is provided with a valve 19a. The upper end of the suction pipe 15 is connected to a suction pump 17 via a valve 16.

  Discharge water from the discharge port of the suction pump 17 is sent to the first tank 21 of the reaction tank 20 through the transparent tube 18. The reaction tank 20 is partitioned into a first tank 21 and a second tank 22 by a partition wall (overflow wall) 23. In the first tank 21 and the second tank 22, submersible pumps 24 and 25 are respectively installed in a suspended manner. The suction port of the submersible pump 24 is in the vicinity of the water level of the first tank 21, and when the submersible pump 24 is operated, only air or air and water in the first tank 21 are sucked. Yes. The discharge port of the submersible pump 24 faces downward, and the entrained air is discharged downward in the first tank 21.

  A pipe 28 is connected to the discharge port of the submersible pump 25 so that water can be supplied to the floating separator 30.

  The levitation separator 30 is divided into a separation chamber 35, an advection chamber 36, and an overflow chamber 37 by a tank 31 and partition walls 32 and 33 provided in the tank 31. An advection port 34 is provided at the lower end of the partition wall 32. An outlet 38 is provided in the lower part of the overflow chamber.

  A scraper 40 is provided so as to scrape off the sludge floating in the separation chamber 35. The scraper 40 has a finned belt 44 that is wound around rollers 41, 42, and 43 so as to be endlessly rotatable. The scraped sludge is scraped up along the guide slope 45 and discharged to the collection tank 50. It is configured.

  A water permeable plate 51 is horizontally installed in the lower part of the collection tank 50, and a bag-like flexible container (flexible container) 52 is disposed above the water permeable plate 51 in an open state.

  In this wet paint booth circulating water treatment device, the paint booth return water from the pipe 1 flows into the pit 2, the non-adhesive agent is added, some sludge is precipitated, and some sludge is Surface. The sludge that has floated is sent to the separation chamber 35 of the floating separation device 30 by the float pumps 7 and 8. The water that has been purified by separation of sludge by sedimentation and flotation is sent to the painting booth via the pipe 10, the pump 11, and the pipe 12.

  The sludge precipitated in the pit 2 is sucked by the suction pipe 15 and introduced from the transparent tube 18 to the first tank 21 of the reaction tank 20. An aqueous solution of a cationic polymer or an anionic polymer is added as a polymer flocculant from the tank 26 or 27 to the first tank 21 (which may be the tube 18) by pumps 26a and 27a. And by the action | operation of the pump 24, it mixes with air and water, and an aggregation process and a bubble adhesion process are performed. The agglomerated sludge to which bubbles are attached overflows the partition wall 23 together with the water in the first tank 21, flows into the second tank 22, and is supplied to the separation chamber 35 of the levitation separator 30 through the pump 25 and the pipe 28. Is done.

  The sludge that floats in the separation chamber 35 is scraped out by the scraper 40 and dropped into the flexible container 52. The water from which the sludge has been separated flows into the advection chamber 36 from the advection port 34, overflows the partition wall (overflow wall) 33, and returns to the pit 2 from the overflow chamber 37 and the outflow port 38 via the pipe 39. . The water (separated water) that has permeated through the flexible container 52 and the water permeable plate 51 is returned to the pit 2 through the outlet 53 and the pipe 54. When the inside of the flexible container 52 is filled with sludge, it is replaced with a new flexible container.

  In this manner, wet paint booth drainage can be treated efficiently.

  When water sucked from the pit 2 flows through the transparent tube 18, the inside of the transparent tube 18 is seen through to determine whether sludge is mixed. When sludge is mixed, the suction port 15a of the suction pipe 15 is positioned at the same location, and suction is continued. If the sludge is not mixed in the water flowing through the transparent tube 18, the suction port 15a of the suction pipe 15 is moved to another position, and the sludge accumulated at that position is sucked. If necessary, the valve 16 is closed, the valve 19a is opened, and the inside of the suction pipe 15 is back-washed with water or air.

  In the present invention, a sensor for measuring the turbidity of water is installed in the transparent tube 18 or the reaction tank 20 through which the mixture of sludge and water sucked from the pit 2 passes, and the position of the suction port 15a or You may make it control the addition amount of a polymer.

  As the pump 17, various pumps such as a vacuum pump, a diaphragm pump, a winged submersible pump, a land-mounted winged pump, and a Mono pump can be used.

  The levitation separator 30 can employ a system that discharges levitation sludge with a scraper, as well as an apparatus that discharges levitation sludge with an overflow.

  The piping 39 for returning the treated water to the pit may be a natural flow type, but a vacuum pump, a diaphragm pump, a winged submersible pump, a land-fed winged pump, a Mono pump, or the like may be used.

  The container for receiving the sludge is not limited to a flexible container, and a container or a net having a hole through which separated water can flow out may be used.

  In addition to the polymer flocculant and non-adhesive agent, an antifoaming agent, a deodorizing agent, or the like may be used as the drug.

  The wet paint booth circulating water treatment device shown in FIG. 1 was used to collect sludge that had been deposited in the past during the painting operation (online) at the wet painting booth in the automobile parts factory. Since the booth was in operation, surplus paint always entered the circulating water, and these were treated with the non-adhesive agent added to the pit 2, and most of them floated in the pit 2. While the sedimentation sludge was being sucked, the existing floating sludge recovery system was also in operation, and the levitating separator simultaneously recovered the treated sludge that floated in pit 2 simultaneously with the sedimentation sludge.

  The mixture of the circulating water pit precipitate and the circulating water was sucked by the vacuum pump 17 through the suction pipe 15 made of aluminum pipe having a length of 2 m and a diameter of 40 mm, with a strainer attached to the suction port 15a. Check the turbidity of the water intake through the transparent tube (hose in this embodiment) 18 from the outlet of the vacuum pump 17 and change the water intake position according to the turbidity (when it becomes transparent, it means that the sludge has disappeared. The amount of polymer added was changed (the amount of polymer added decreased as the turbidity decreased).

  To the first tank 21 of the reaction tank 20, Chrystak B-342 as an anionic polymer and Crifix EC-482 as a cationic polymer were added as a polymer flocculant, and stirred with an underwater pump 24. At this time, only air was sucked into the submersible pump 24 to become agglomerated sludge containing air, which floated and overflowed into the second tank 22.

  Water and agglomerated sludge were sent to the floating separator 30 by the pump 25 of the second tank 22, where the sludge was separated and the sludge removed from the surface of the water was collected in a flexible container.

  It was operated for 30 hours, and 3564 kg (891 kg / flexible container × 4 bags, moisture content 73%) was collected as the sedimentation sludge. The solid content (dry amount) was 962 kg. In this pit, the moisture content of the sludge (sludge) when the accumulated sludge is sucked and removed with a vacuum car is 90%. Assuming that the same amount of solids has been removed, the amount of waste is 9620 kg, almost three times that of this time.

  Therefore, according to the device of the present invention, it was recognized that sludge having a low water content can be efficiently recovered.

2 Pit 7, 8 Float pump 15 Suction tube 20 Reaction tank 30 Flotation separation tank 50 Recovery tank 52 Flexible container

Claims (4)

Wet paint booth with pit to accept circulating water,
A suction means for sucking and collecting the accumulated paint sludge, comprising a suction port movable in the water in the pit;
A reaction tank into which water and paint sludge sucked by the suction means are introduced;
Means for adding a chemical to water introduced or introduced into the reaction vessel;
Stirring means provided in the reaction vessel;
A levitating separation device that introduces reaction water from the reaction tank and levitates and separates into sludge and treated water;
Return means for returning treated water from the levitation separator to the pit;
An apparatus for treating circulating water in a wet coating booth comprising discharge means for discharging sludge from the floating separator.   2. The treatment apparatus for circulating water in a wet coating booth according to claim 1, wherein the stirring means is a pump that blows air near a water surface level in the reaction tank and discharges the air into the reaction tank.   3. The wet paint booth circulating water treatment apparatus according to claim 1, wherein the chemical agent is at least one or both of a polymer flocculant and a non-adhesive agent. In any one of Claims 1-3,
A turbidity sensor for detecting turbidity of water is provided in at least one of the suction means, the reaction tank, and the path from the suction means to the reaction tank,
A wet paint booth circulating water treatment apparatus, characterized in that a control means is provided for controlling at least one of the position of the suction port and the amount of the drug added according to the detection value of the turbidity sensor.

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