JP2008264741A - Paint waste liquid separation apparatus and paint waste liquid separation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paint waste liquid separation apparatus and a paint waste liquid separation method by which paint components are separated with high separation efficiency without using a large quantity of flocculant and a flocculated material having sufficient buoyancy is formed. <P>SOLUTION: In the paint waste liquid separation apparatus and the paint waste liquid separation method, the powdery flocculant and raw water are vigorously stirred to instantly disperse the flocculant in the raw water and to efficiently take-in the paint components in the raw water. As a result, the paint components and the circulating water are satisfactorily separated from each other even with a small quantity of the flocculant. The flocculant, the raw water and air are stirred at the same time, thereby the resultant flocculated material involves bubbles to have buoyancy to be easily suspended and then, is easily and efficiently recovered. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a paint waste liquid separation device and a paint waste liquid separation method for effectively separating paint components in waste liquid in which surplus paint at the time of painting is collected.

  2. Description of the Related Art Conventionally, as a coating method for articles having complicated shapes such as automobiles, building materials, and electrical appliances, a spray coating method in which paint is sprayed in a coating booth is often used. In this spray coating method, the amount of paint that contributes to actual painting is about 30% of the sprayed paint, and the remaining 70% is surplus paint. These surplus paints are generally captured by a water curtain or the like provided in the painting booth and collected in circulating water. Then, after the circulating water containing the surplus paint component is collected in the circulating water pit, the circulating water and the paint component are separated according to a predetermined method, and the separated paint component is recovered and recovered by an appropriate disposal method. Discarded. In addition, the circulating water from which the paint component has been removed is reused for collecting excess paint. The circulating water containing the paint component is generally called raw water.

  In the above surplus paint treatment method, when the paint used for painting is an organic solvent-based oil paint, the collected paint components do not dissolve in the circulating water and exist as an adhesive solid. Yes. For this reason, if an appropriate amount of an aggregating agent generally called a spray mist treating agent is added to the circulating water, these coating components become a fine solid having no adhesive force and easily aggregate to form an aggregate. Then, by collecting the aggregate, the circulating water and the paint component can be separated relatively easily. However, in recent years, emission regulations for VOCs (Volatile Organic Compounds) have been strengthened, and in paints for painting, the switching of paints to be used from conventional oil-based paints to non-organic solvent-based water-soluble paints has also been rapid. Has been done. Since these water-soluble paints dissolve and disperse in the circulating water, it is extremely difficult to separate the circulating water and the paint components as compared with the oil-based paints.

  In order to solve the above problem, in the invention disclosed in [Patent Document 1] below, circulating water and paint components are separated by adding an alkaline substance such as sodium hydroxide as a flocculant to the water-soluble paint waste liquid. It is carried out.

JP 2006-231269 A

  However, the invention disclosed in [Patent Document 1] requires a very large amount of flocculant for separation of water-soluble paint waste liquid, and also requires a step of neutralizing waste water after separation and an acid-based chemical. Become. In addition, this treatment method is a method limited to a limited number of water-based paints, and since the separated wastewater is premised on disposal, the reuse of wastewater as circulating water is significantly limited. The That is, in the invention disclosed in [Patent Document 1], although the cost for the flocculant itself is relatively low, in addition to requiring a plurality of steps and chemicals for the treatment after the coating component separation, the reuse of treated water is possible. In other words, there is a problem that a large amount of water is required to replenish the circulating water at all times.

  In this regard, if a flocculant such as the above-mentioned spray mist treatment agent is used, the cost of the flocculant itself is high, but since the flocculant component hardly remains in the circulating water, the circulating water can be used without using a special process or chemical. Can be reused repeatedly. However, the separation of the water-soluble paint requires a large amount of a flocculant, and there is a problem that the cost for the flocculant is remarkably increased. Further, since the components of the flocculant are also aggregates, if a large amount of the flocculant is added, there is a problem that the amount of aggregates to be recovered is increased by that amount and the disposal cost of the aggregates is increased.

  In order to separate the water-soluble paint component from the circulating water, it is effective to make particles large until separation is possible. This treatment is also the same as the invention disclosed in [Patent Document 1]. , Requires a large amount of flocculant.

  Furthermore, as a method of collecting the aggregate, it is preferable to use a technique in which the aggregate is levitated and collected because the equipment configuration is easy. As a method for floating the agglomerates, it is common to produce fine bubbles in water, attach them to the agglomerates, and float the agglomerates by the buoyancy of the bubbles. However, depending on the agglomerates that are generated, the buoyancy of the attached bubbles may not be sufficiently lifted, and there is a problem that the recovery efficiency is poor.

  The present invention has been made in view of the above circumstances, and it is possible to separate paint components without using a large amount of flocculant with high separation efficiency of paint components, and to generate agglomerates having sufficient buoyancy. It is an object of the present invention to provide a paint waste liquid separation device and a paint waste liquid separation method that can be applied.

The present invention is a paint waste liquid separation apparatus for separating a circulating water and a paint component by introducing a powdery flocculant into the circulating water containing the paint component.
A flocculant supply unit 52 for supplying a powdery flocculant;
A first stirrer 54 that stirs the flocculant supplied from the flocculant supply unit 52, the circulating water containing the paint component, and the air simultaneously at a high speed;
A second stirring unit 56 that stirs the mixed liquid produced by the stirring of the first stirring unit 54 at a slower speed than the first stirring unit 54;
A third stirring unit that stirs the mixed liquid generated by the stirring of the second stirring unit 56 at a slower speed than the second stirring unit 56;
The above-mentioned problem is solved by providing a paint waste liquid separation device 50 characterized by comprising:
Also, a paint waste liquid separation method for adding a flocculant and separating circulating water containing paint components into circulating water and paint components,
A first agitation step of simultaneously agitating the circulating water and air containing the powdery flocculant and the paint component at high speed;
A second stirring step of stirring the liquid mixture produced by stirring in the first stirring step at a speed slower than that of the first stirring step;
A third stirring step of stirring the liquid mixture produced by the stirring in the second stirring step at a slower speed slower than the second stirring step;
The above-mentioned problems are solved by providing a method for separating paint waste liquid, characterized by comprising:
In addition, the flocculant used in the paint waste liquid separation method described above,
The above-mentioned problem is solved by providing a paint waste liquid separation method characterized by being a flocculant having a swelling property that expands and aggregates while taking in a paint component when added to circulating water containing the paint component.

The paint waste liquid separation apparatus and paint waste liquid separation method according to the present invention have the above-described configuration and procedure.
(1) When the flocculant and raw water are mixed, the dispersibility of the flocculant is increased and the separation efficiency of the paint components is improved by stirring rapidly and rapidly. For this reason, the amount of the flocculant to be used can be reduced and the cost for the flocculant can be reduced. In addition, the amount of the aggregate to be generated is also reduced, so the disposal cost of the aggregate can also be reduced. .
(2) By relatively stirring the flocculant, raw water, and air at the same time, and further decreasing the stirring speed stepwise, it is possible to generate a relatively large agglomerate that contains bubbles and has a certain degree of buoyancy. For this reason, the produced | generated aggregate can float easily and it can collect | recover aggregates efficiently.

  An embodiment of a paint waste liquid separating apparatus and a paint waste liquid separating method according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a paint waste liquid treatment system including a paint waste liquid separation device according to the present invention. FIG. 2 is a schematic configuration diagram of the first embodiment of the paint waste liquid separating apparatus according to the present invention. FIG. 3 is a schematic configuration diagram of the second embodiment of the paint waste liquid separating apparatus according to the present invention. The embodiments described here are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic configuration diagram of a paint waste liquid treatment system 100 including a paint waste liquid separation device 50 according to the present invention. The paint waste liquid treatment system 100 shown in FIG. 1 is a preferred example of the paint waste liquid treatment system provided with the paint waste liquid separation device 50 according to the present invention. Therefore, the arrangement of each tank, the aggregate recovery mechanism, and each tank The configuration of the intervening piping, the pressurized water generating section, and the like are not particularly limited to the following.

  First, surplus paint generated in a painting booth (not shown) is collected in circulating water by a water curtain or the like, and stored in the circulating water pit 22 through the drainage groove 20 as raw water. The circulating water pit 22 is provided with a water intake device 24, and the raw water stored in the circulating water pit 22 by the water intake device 24 is conveyed to the raw water supply tank 32 and supplied to the paint waste liquid separator 50 according to the present invention. . At this time, excess raw water in the raw water supply tank 32 is discharged to the circulating water pit 22 via the drainage basin 32a. In FIG. 1, a float pump is used as the water intake device 24 and the upper layer portion of the raw water stored in the circulating water pit 22 is taken, but the water intake position is not particularly limited to the upper layer portion. Water may be taken from the middle or bottom layer. The circulating water pit 22 may be provided with a pit stirring device 26 for stirring the stored raw water.

  The raw water supplied to the paint waste liquid separator 50 is separated by the paint waste liquid separator 50 into circulating water and aggregates indicated by ● in FIG. The separated agglomerates together with the circulating water are discharged to the aeration trough 34 of the levitation tank 30. The aeration trough 34 is provided with a pressurized water discharge port 48a, and the pressurized water discharge port 48a is connected to a pressurized water generator 40 described later via a pressure adjustment valve 48c. The pressurized water from the pressurized water generator 40 is released to normal pressure at the pressure adjustment valve 48c before being discharged at the pressurized water discharge port 48a. At this time, the air dissolved in the pressurized water appears as fine bubbles (micro air), and this micro air is discharged into the aeration trough 34 through the pressurized water discharge port 48a. This micro air adheres to the agglomerates in the aeration cage 34 and further increases the buoyancy against the agglomerates.

  Aggregates that have floated on the surface layer of the levitation tank 30 due to adhesion of micro air, etc. are scraped off by a scraping device 36 attached to the levitation tank 30 and appropriately collected via a waste outlet 38, etc. It is discharged in accordance with a predetermined disposal method. The agglomerates discharged to the collection container 39 and the like are subjected to natural standing filtration or a filter (not shown), a filtration device, and the like to remove excess moisture, and this moisture is discharged to the circulating water pit 22 as circulating water.

  Further, the circulating water from which the paint component in the floating tank 30 has been separated is stored in the circulating water tank 35 through the separated circulating water intake 30 a provided in the lower part of the floating tank 30. The circulating water stored in the circulating water tank 35 is discharged into the circulating water pit 22 through the intake water tank 35a.

  Further, the circulating water tank 35 is provided with a water intake 42 a for supplying the circulating water to the pressurizing pump 42 of the pressurizing water generating unit 40. When the pressurizing pump 42 is operated, the circulating water is taken from the water intake 42a, and the circulating water taken by the negative pressure adjusting valve 41 provided between the water intake 42a and the pressure pump 42 is used. A negative pressure is generated. The pressurizing pump 42 sucks air from an intake port 44 connected to the pressurizing pump 42 by the negative pressure generated in the circulating water. The air sucked from the intake port 44 and the circulating water supplied from the intake port 42a are sent to the gas-liquid separation pipe 48 while being mixed and pressurized by the pressurizing pump 42. Due to the pressurization by the pressurizing pump 42, a predetermined amount of air is dissolved in the circulating water, whereby the pressurized water is accumulated in the gas-liquid separation pipe 48. Then, the pressurized water generates micro air from the pressurized water discharge port 48a to the aeration trough 34 as described above. Excess air that cannot be dissolved in the circulating water is exhausted from an adjustment valve 48 b provided in the gas-liquid separation pipe 48.

  The circulating water pit 22 is provided with a circulating water intake port 28a connected to the circulating pump 28, and the circulating pump 28 supplies the circulating water in the circulating water pit 22 to the painting booth. The above is the outline of the paint waste liquid treatment system 100. The circulating water taken from the intake tank 35a is stored in a second circulating water pit different from the circulating water pit 22 so that only the circulating water from which the paint components are separated is supplied to the painting booth. May be.

  Next, a first embodiment of the paint waste liquid separating apparatus 50 according to the present invention will be described with reference to FIG. A paint waste liquid separating apparatus 50a according to the first embodiment of the present invention shown in FIG. 2 includes a flocculant supply unit 52 that supplies a powdery flocculant, a flocculant supplied from the flocculant supply unit 52, raw water, and air. Are mixed at the same time and rapidly agitated at high speed to agglomerate the paint components in the raw water, and the mixture of the circulating water and the aggregate separated by the first agitator 54 is the first agitator 54. The second agitation unit 56 that agglomerates the aggregates by rapidly stirring at a slower speed and grows into larger aggregates, and the mixed liquid of the circulating water and the aggregates from the second agitation unit 56 is second. It has a ripening tank 58 which is a third stirring part for adhering the aggregates and growing them into larger aggregates by stirring at a slower speed than the stirring part 56.

  The flocculant supply unit 52 supplies a predetermined amount of the flocculant to the water intake port 60 of the first stirring unit 54 in a powder form intermittently or at a constant supply rate. A hopper or the like that can control the supply amount is provided. It is preferable to use it.

  The first stirring unit 54 takes in the flocculant, raw water and air simultaneously from the water intake 60 and stirs them rapidly at a high speed. The water intake 60 of the first stirring unit 54 is air and powder simultaneously with the raw water. In order to be able to take in the flocculent agent, the opening is arranged so as to face upward near the water surface. Note that, as shown in FIG. 2, the water intake 60 may be provided at the bottom of the raw water supply rod 62.

  The number of rotations of the first stirring unit 54 is required to be about 1000 rpm or more in order to rapidly agitate the powdered flocculant and the raw water to efficiently aggregate the paint components in the raw water. In addition, since the upper limit of the rotational speed is not particularly limited, it is preferable to use a bipolar submersible pump having a rotational speed of 3000 to 3600 rpm as the first stirring unit 54 with the water inlet facing upward. Further, a 4-pole submersible pump having a rotational speed of 1500 to 1800 rpm and a known stirrer having a rotational speed of 1000 rpm or more can be used.

  The second agitating unit 56 agitates the mixed liquid stirred by the first agitating unit 54 at a speed slower than that of the first agitating unit 54, and a known agitator or the like may be used. It is preferable to use a static mixer that is a static mixer that is not used.

  The aging tank 58 that is the third stirring unit is a water tank of a predetermined size, and is installed so that the discharge port of the second stirring unit 56 faces the bottom layer part of the aging tank 58 in the horizontal direction.

  Next, a paint waste liquid separating apparatus 50b which is a second embodiment of the paint waste liquid separating apparatus 50 according to the present invention will be described with reference to FIG. FIG. 3 is a view of the configuration paint waste liquid separating apparatus 50b as viewed from the raw water supply tank 32 side, and the floating tank 30 is located on the back side of the paint waste liquid separating apparatus 50b. The paint waste liquid separator 50b shown in FIG. 3 has the same configuration as the paint waste liquid separator 50a, but the discharge port of the first stirring unit 54 and the water intake port of the second stirring unit 56 are connected by a hose 64. The second stirring unit 56 is disposed so as to be exposed to the outside of the aging tank 58 that is the third stirring unit.

  In the paint waste liquid separating apparatus 50a of the first embodiment, since the second stirring unit 56 is installed in the aging tank 58, the size of the second stirring unit 56 to be used is limited, and the second stirring unit 56 can be easily used. 56 cannot be exchanged. However, in the paint waste liquid separating apparatus 50b, since the second stirring unit 56 is disposed so as to be exposed to the outside of the aging tank 58, the size of the second stirring unit 56 is not limited, and the second stirring unit 56 to be used is not limited. The degree of freedom of selection can be expanded. Moreover, the 2nd stirring part 56 can be easily replaced | exchanged according to the kind, density | concentration, etc. of coating component in raw | natural water.

  In particular, when a static mixer is used for the second stirring unit 56, the number of static mixers to be connected can be increased or decreased depending on the conditions. Can do. In addition, a plurality of static mixers are connected to the second stirring unit 56 in advance, and a branch pipe and an open / close valve are provided at the connection part, so that mixing is performed by the open / close valve without adding or removing the static mixer. The number of static mixers through which the liquid flows can be increased or decreased.

  Next, the operation of the paint waste liquid separating apparatus 50 according to the present invention will be described. Here, an example using a flocculant having a swelling property that expands and aggregates while absorbing paint components and circulating water when introduced into raw water will be described.

  First, the flocculant supply unit 52 is filled with a predetermined powdery flocculant. Next, raw water is conveyed from the circulating water pit 22 or the like and supplied to the water intake 60 of the first stirring unit 54. At this time, by adjusting the position of the water intake 60 or the supply amount of the raw water so that the water intake 60 is not completely filled with the raw water, air is taken into the first stirring unit 54 together with the raw water from the water intake 60. . At the same time, a powdery flocculant is supplied from the flocculant supply section 52 to the water intake 60 at an intermittent or constant supply speed, and the flocculant, raw water and air are fed at high speed by the first stirring section 54. Stir rapidly. The suitable ratio of raw water and flocculant at this time varies depending on the type and composition of the coating component contained in the raw water, the concentration of the coating component in the raw water, the type of the flocculant used, and the like. Therefore, it is desirable to adjust the supply amount of the flocculant by the flocculant supply unit 52 so that the ratio of the raw water and the flocculant is in a range suitable for these conditions.

  The flocculant taken into the first stirring unit 54 is rapidly stirred with raw water and air by the first stirring unit 54. The flocculant is agitated with the raw water and air, and while entraining the air as fine bubbles, the paint component and the circulating water in the raw water, especially the paint component is taken in and expanded and aggregated. Separate water. The above corresponds to the first stirring step.

  Next, the mixed liquid of the aggregate and circulating water generated by the first stirring unit 54 is sent to the second stirring unit 56. Since the second stirring unit 56 stirs at a slower speed than the first stirring unit 54, the aggregates generated in the first stirring unit 54 aggregate and grow to form relatively large aggregates. In addition, the air which exists in a liquid mixture will also be involved as a bubble at the time of this aggregate formation. The above corresponds to the second stirring step.

  Next, the liquid mixture of the aggregate and circulating water generated by the second stirring unit 56 is discharged from the discharge port of the second stirring unit 56 into the aging tank 58 that is the third stirring unit. At this time, since the discharge port of the second stirring unit 56 is installed in the bottom layer portion of the aging tank 58 so as to face the horizontal direction, the mixed solution discharged from the second stirring unit 56 is generated by discharging the mixed solution. It is gently stirred in the aging tank 58 by the flow rate. As a result, the aggregates adhere to the surrounding aggregates and grow into larger aggregates. The above corresponds to the third stirring step.

  Since the agglomerates contain bubbles as described above, they gently float on the surface layer of the aging tank 58 due to the flow rate during discharge and the buoyancy of the bubbles. Then, the maturation tank 58 and the circulating water are discharged to the aeration tank 34 of the levitation tank 30. Thereafter, the agglomerates are collected and discarded according to the agglomerate collection path of the paint waste liquid treatment system 100 described above.

  Here, the flocculating agent having swelling property is that the coating component is taken up with the circulating water in a short time when it comes into contact with the raw water, so that the flocculating agent is expanded and aggregated. If only the paint component in the vicinity is taken in, it will aggregate. For this reason, in order to fully isolate | separate a coating-material component and circulating water, a lot of flocculants are needed.

  However, according to the paint waste liquid separation apparatus and paint waste liquid separation method according to the present invention, the powdered flocculant and raw water are rapidly stirred at a high speed of 1000 rpm or more, so the flocculant is instantaneously dispersed in the raw water. In particular, in the case of a flocculant having swelling properties, the paint component in the raw water can be taken in very efficiently. When the flocculant having swelling property is used in the paint waste liquid separation apparatus and paint waste liquid separation method according to the present invention, it is about 1 compared with the normal stirring speed although it depends on the type of the aqueous paint component in the raw water. Even with a small amount of flocculant of / 3 to 1/6, it was possible to sufficiently separate the paint components and the circulating water.

  Even when a non-swellable flocculant is used, the use of the paint waste liquid separation device and the paint waste liquid separation method according to the present invention is more effective than the introduction of a dispersant into a large-capacity water tank and stirring. Separation efficiency is high and the amount of flocculant used can be reduced.

  From the above, according to the paint waste liquid separation apparatus and paint waste liquid separation method according to the present invention, the powder flocculant and the raw water are rapidly agitated to increase the dispersibility of the flocculant and to circulate the paint components and the circulation. Separation efficiency with water can be improved. For this reason, it is possible to reduce the use amount of the flocculant and reduce the cost for the flocculant. In addition, the amount of the resulting flocculant can be reduced and the disposal cost of the flocculant can be reduced.

  Furthermore, in the paint waste liquid separation apparatus and paint waste liquid separation method according to the present invention, the flocculant, raw water, and air are stirred at the same time, so that the aggregates in the first stirring section 54 and the aggregates in the second stirring section 56 are mixed. The growth is performed while enclosing fine bubbles. Therefore, the obtained aggregate contains bubbles and has buoyancy itself, so that it easily floats, and these aggregates can be recovered easily and efficiently. If the buoyancy of the aggregate itself is sufficient, the micro air generation mechanism need not be used. In this case, the configuration of the paint waste liquid treatment system 100 can be simplified.

  Furthermore, when the salt concentration and electrical conductivity of the circulating water are increased, adverse effects such as inducing and promoting rusting on the equipment in the painting booth and the metal part of the object to be painted occur. However, since the flocculant having swellability generally does not significantly increase the salt concentration or electrical conductivity of the circulating water, if the flocculant having swellability is used in the paint waste liquid separation method according to the present invention, the paint The circulating water after separating the components can be reused as circulating water for the painting booth without any special treatment.

  As the flocculant used in the paint waste liquid separation apparatus and paint waste liquid separation method according to the present invention, those having swelling properties as described above are suitable, but are also applicable to other flocculants added in powder form. In addition, the present invention can be modified and implemented without departing from the scope of the present invention.

It is a schematic block diagram of the paint waste liquid processing system provided with the paint waste liquid separation device concerning the present invention. It is a schematic block diagram of the 1st form of the coating-material waste-liquid separator which concerns on this invention. It is a schematic block diagram of the 2nd form of the coating-material waste-liquid separator which concerns on this invention.

Explanation of symbols

50, 50a, 50b Paint waste liquid separator
52 Flocculant supply section
54 1st stirring part
56 Second stirring section
58 Aging tank (third stirring section)

Claims (3)

In a paint waste liquid separator that separates circulating water and paint components by introducing a powdery flocculant into circulating water containing paint components,
A flocculant supply section for supplying a powdery flocculant;
A first stirring unit that simultaneously stirs the coagulant supplied from the coagulant supply unit, the circulating water containing the paint component, and air at a high speed;
A second stirring unit that stirs the mixed liquid generated by stirring in the first stirring unit at a speed slower than that of the first stirring unit;
A third stirring unit that stirs the mixed solution produced by stirring in the second stirring unit at a slower speed than the second stirring unit;
A paint waste liquid separation device characterized by comprising: A paint waste liquid separation method for separating a circulating water containing a paint component by adding a flocculant into a circulating water and a paint component,
A first agitation step of simultaneously agitating the circulating water and air containing the powdery flocculant and the paint component at high speed;
A second stirring step of stirring the liquid mixture produced by stirring in the first stirring step at a speed slower than that of the first stirring step;
A third stirring step of stirring the liquid mixture produced by the stirring in the second stirring step at a slower speed slower than the second stirring step;
A method for separating paint waste liquid, comprising: The flocculant used in the paint waste liquid separation method according to claim 2,
A paint waste liquid separation method characterized by being a flocculant having a swelling property that expands and aggregates while taking in a paint component when added to circulating water containing the paint component.

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