JPH0133222B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air purification device containing paint mist for a paint booth.

In a spray painting booth, the following measures are taken to prevent excess paint mist floating in the air as a result of overspray from adhering to the entire surface of the booth and from worsening the work atmosphere.

A clean air suction section will be formed on the ceiling side of the booth.

The floor is a grating floor, and a duct (exhaust plenum) with a blower is installed to suck air containing paint mist from below and exhaust clean air after removing paint mist to the atmosphere.

By bringing paint mist-containing air into contact with purification water on the upstream side of the blower and below the grating floor, the paint mist in the air is collected in the purification water, thereby converting it into clean air.

The water that collects paint mist (sludge) is led to a separation tank, where it is clarified and circulated using a pump.

Conventionally, the target method shown in FIG. 1, the direction change method shown in FIG. 2, or the hybrid method shown in FIGS. 3 and 4 have been known as methods for bringing the paint mist-containing air into contact with purifying water. . In these figures A
is mist-containing air, W is water for purification, 1 is a target plate, and 2 is a direction change plate. Each of these four methods has its advantages and disadvantages, but the problem with all of them is that they all have insufficient efficiency in separating paint mist, and in particular, separation of paint mist with small particle sizes (10 microns or less) is incomplete. .

The present invention aims to improve this problem.

The model shown in FIG. 5 will be considered within the range to which Stokes' resistance law can be applied, with inertial separation as the main force. In this figure, 3 is a recessed guide surface for purifying water and air containing paint mist, 4 is its inlet, and O
is the center of curvature of the guide surface 3, α is the effective central angle, R is the effective radius obtained by subtracting 1/2 of the width b of the inlet 4 from the radius of curvature of the guide surface 3, and ν is the airflow velocity at the inlet 4.
As a first approximation, we ignore the deceleration of the airflow, and R≫b
Then, the distance X(d) that the paint mist particles move radially outward due to the centrifugal force due to the deflection (direction change) over the central angle α radian is: X(d)=α(ρp/ ρ−1) v/18ν・d ² −(
) d: Particle diameter [m] ρp: Particle density [Kg/m ³ ] ρ: Air density [Kg/m ³ ] ν: Kinematic viscosity coefficient of air [m ² /sec] When X (dc) = b dc: Capture critical diameter Particles with d>dc are captured, and particles with d<dc remain in the airflow.

In other words, particles with smaller diameters are more difficult to capture.

Therefore, in order to reduce the trapping critical diameter dc, from the above formula (), (a) Increase α. In other words, the circumference L is increased.

(b) Reduce Xd, that is, b.

(c) Increase v.

Among these, the present invention places emphasis on (a).

The paint mist-containing air purification device for a paint booth according to the present invention has a series of arc-shaped or similar shapes connected to and below the purifying water flowing wall, and having a vertical plane or a surface close to it in the vertical middle part, and the upper end. and a concave guide surface for purifying water and paint mist-containing air whose tangent at the lower end is in the horizontal direction or in a direction gently inclined to the horizontal direction, and the introduction passage for the paint mist-containing air is connected to the upper end of the guide surface. It is formed along the section.

The structure of the recessed guide surface mentioned here will be briefly explained with reference to FIG. In both cases, the upper starting point can be not only P ₁ but also P ₂ or P ₃ .
It is also shown that the lower end point can be not only Q ₁ but also Q ₂ or Q ₃ . It also shows that there are 3×3=9 combinations of both points. P ₁ and Q ₁ are directly above and below the center of curvature O of the perfect circle E, and P ₂ , P ₃ , Q ₂ , and Q ₃ have tangents thereto of 40 degrees or less, preferably 30 degrees or less with respect to the horizontal. and preferably 15 degrees or less.

The guide surface 5 is in relation to the perfect circle E, and in Fig. 6, A is the same, B is a bulge in the upper half, C is a bulge in the lower half, D is a bulge in both the upper and lower halves, and E is a large number. The cases of polygonal lines of tangent line groups are shown respectively. Note that the polygonal line method also applies to B, C, and D. Although there are no restrictions in principle on the degree of bulge, the center of curvature, and the radius, it can be said that the smaller the bulge, the better. Incidentally, 6 represents the downstream wall of purification water.

As can be understood from the above examples, in the present invention,
Because the circumference of the recessed guide surface is set sufficiently long,
In other words, theoretically, as guaranteed by equation (), the critical diameter dc for trapping paint mist particles can be made considerably smaller than in the past. In other words, by simply improving the structure of the guide surface, compared to the conventional structure, it is possible to separate smaller particles with the same separation efficiency, and it is possible to increase the separation efficiency with the same particle size. It is.

In addition to countermeasure A, in carrying out the present invention,
There is nothing wrong with using countermeasures B and C together.

Preferred embodiments of the present invention will be described below.

[] First example. Figures 7 and 8.

7 is a painting booth, 8 is a wall, 9 is a grating floor, 10 is an object to be painted such as an automobile body, 11
12 is a purification water supply header; 13 is a cleaning plate (tray) that slopes gently downward toward the flow outlet; 14 and 15 are a series of long partition plates; the outer surface of the partition plate 15 is a flow wall 6; Also serves as 16 is a diagonal bottom plate, 17 is a drainage groove, and 18 is a duct leading to an exhaust plenum. A, which is represented by a broken line, is the flow of air, and W, which is represented by a solid line, is the flow of water.

The dots are paint mist particles. Reference numeral 19 denotes a series of long gutter-shaped guide plates having a perfect circular arc extending over 180 degrees, and the inner surface thereof is a recessed guide surface 5. 20 is a target plate. Reference numeral 21 denotes a guide plate for forming a passage 22 through which air containing paint mist is introduced along the upper end portion of the guide surface 5. Purification water also overflows onto the guide plate 21. The flow wall 6 and the inlet channel 22 have a common opening 23 to the coating booth 7. In this example, since the two guide plates 19, 19 are arranged back to back, paint sludge adhering to the guide plate 5 can be cleaned very easily through its large 180 degree opening. Note that it is desirable that the guide surface 5 be coated with a substance such as Teflon that prevents the adhesion of paint particles.

The paint mist-containing air is effectively purified by inertial separation on the guide surface 5 and collision separation on the target plate 20.

[] Second example. Figure 9.

This has two guide plates 19, 19 facing each other and a common target plate 20. A central supply header 12 is provided between the air guide plates 21, 21, and an opening at the upper end of the guide plates 21, 21 is provided. Water for purification is being overflowed.

[] Third example. Figure 10.

This has one opening 23, guide plates 19, 21,
There is also one target plate 20.

[] Fourth example. Figure 11.

This shows that the downstream wall 6 and the introduction passage 22 face the coating booth 7 through separate openings 23', 23''.

[Brief explanation of drawings]

Figures 1 to 4 are sectional views of conventional examples;
FIG. 5 is a model diagram explaining inertial separation, FIGS. 6A to 6E are sectional views showing various examples of recessed guide surfaces, FIGS. The figure is a vertical cross-sectional view of almost the whole, and FIGS. 8 to 11 are cross-sectional views of main parts of different embodiments. 5... Recessed guide surface, 6... Downward wall, 22... Introductory passage.

Claims (1)

[Claims] 1. A series of arcuate or similar shapes connected to and below the purification water flowing wall 6, with a vertical plane or a surface close to it in the vertical middle part, and tangents at the upper and lower ends. A recessed guide surface 5 for purifying water and paint mist-containing air is formed in the horizontal direction or in a direction gently inclined to the horizontal direction, and an introduction passage 22 for the paint mist-containing air is formed along the upper end portion of the guide surface 5. Paint mist-containing air purification device for the paint booth that is being formed in the state. 2. The paint mist-containing air purification device for a paint booth according to claim 1, wherein the guide surface 5 is in the shape of a perfect circular arc with a central angle of 180 degrees or approximately 180 degrees. 3. The paint mist-containing air purification device for a painting booth according to claim 1, wherein the falling wall 6 and the introduction passage 22 have a common opening to the painting booth. 4. The paint mist-containing air purification device for a paint booth according to claim 1, wherein the bottom and top surface of the introduction passage 22 overlaps the flow surface of the purification water.