JPH0112550B2 - - 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 order to prevent excess paint mist floating in the air as a result of overspraying in a spray painting booth from adhering to the entire surface of the booth and, in particular, from deteriorating the working atmosphere, the following measures are taken.

A clean air absorption section is 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 purifying water on the upstream side of the blower and below the grating floor, the paint mist in the air is collected by the purifying water, thereby converting the air 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 are 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 the separation efficiency of paint mist is insufficient, especially the separation of paint mist with small particle size (10 microns or less). be.

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 concave 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 v 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 paint mist particles move radially outward due to centrifugal force due to a change in direction over a central angle α radian is: X(d)=α(ρ _p /ρ-1) v/18ν・d ² () d: Particle diameter [m] ρ _p : 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: critical diameter for capture 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, increase the circumference (L).

(b) Reduce X(d), that is, b. In other words, reduce the airflow width.

(c) Increase v.

Of these, the present invention places emphasis on (a) and (b).

The paint mist-containing air purification device for a paint booth according to the present invention faces one opening to the paint booth and is connected to each of the facing purification water flow walls and is arranged below each of them in a series of arcuate or similar shapes up and down. A recessed guide surface for purifying water and paint mist-containing air is formed in the intermediate part in the direction, and has a vertical surface or a surface close to it, and the tangents at the upper and lower ends are in the horizontal direction or in a direction gently inclined with respect to the horizontal direction, Further, a passage for introducing paint mist-containing air from a direction along the upper end portion of each of these guide surfaces is formed so as to branch left and right in the middle of the width direction of the opening.

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. In Fig. 6, A is the same, B is the upper half is bulged, C is the lower half is bulged, D is the upper half and the lower half are bulges, and E is the bulge. The cases of polygonal lines with multiple tangent lines 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 these examples, in the present invention, the circumference of the recessed guide surface is sufficiently long, and one opening for the coating booth is divided into two, reducing the air flow width by half. Theoretically, as guaranteed by formula (), the critical diameter dc for trapping paint mist particles can be made extremely smaller than in the past. In particular, as an effect of dividing the introduction passage into two, the width of b becomes 1/2 for the same flow velocity v compared to the conventional method, so that the diameter of the trapped particles becomes smaller.
When the captured particle size is the same, that is, when the width b is the same as one, the flow velocity v is 1/2, so the pressure loss is 1/4, and energy saving can be achieved. Of course,
Flow rate settings intermediate to , are also possible.

(Q=S×v) In addition to countermeasures (a) and (b), countermeasure (c) may be used in combination with countermeasures (a) and (b) in carrying out the present invention.

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 is a trolley, 12 is a purification water supply header, 1
Reference numeral 3 denotes a cleaning plate (tray) that gently slopes downward toward the flow outlet; 15 is a series of elongated partition plates; the outer surface of the partition plate 15 also serves as the flow wall 6; 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.

That is, one opening 20 is formed in the middle of the cleaning plate 13, and there are downstream walls 6, 6 facing each other facing this opening 20, and concave guide surfaces 5, 5 are formed symmetrically in series with each other. There is. A target plate 21 is provided at the center between the lower ends of both guide surfaces 5,5. 22, 22 are guide surfaces for forming passages 23, 23 through which air containing paint mist is introduced along the upper end portions of the guide surfaces 5, 5. There is also a purification water supply header 24 between both guide plates 23, 23, and each guide plate 2
Purification water also overflows onto the upper surfaces of 3 and 23. still,
It is desirable that the guide surface 5 be coated with Teflon or other material to prevent the adhesion of paint particles.

The paint mist-containing air is effectively purified by the synergy of the inertial separation due to the centrifugal force on the guide surface 5, the collision separation on the target plate 21, and the fact that the substantial air flow widths b and b are made sufficiently small.

[] Second example. Figure 9.

A horizontal tray 25 is provided below the opening 20, a header 24 is placed in the middle, and the tray 25 is placed below the opening 20.
Both ends of the guide surface 5 are finished, and the type _P2 in FIG. 6 is adopted as the guide surfaces 5, 5, and the airflow widths b, b are sufficiently small in this case as well.

[Brief explanation of drawings]

Figures 1 to 4 are sectional views of conventional examples;
5 is a model diagram explaining inertial separation, FIGS. 6 A to 6 are sectional views showing various examples of recessed guide surfaces, and FIGS. 7 to 9 illustrate embodiments of the present invention,
FIG. 7 is a longitudinal sectional view of almost the whole, FIG. 8 is a longitudinal sectional view of the main part, and FIG. 9 is a longitudinal sectional view of the main part of another embodiment. 5... Recessed guide surface, 6... Downward wall, 20... Opening, 23... Introduction passage.

Claims (1)

[Scope of Claims] 1. A series of arc-shaped or similar shapes arranged vertically in the middle of each of the purifying water flow-down walls 6, 6 which face one opening 20 for the painting booth and are connected to each other and below each of them. is formed with recessed guide surfaces 5, 5 for purifying water and paint mist-containing air that have a vertical surface or a surface close to it, and the tangents at the upper and lower ends are in the horizontal direction or in a direction gently inclined with respect to the horizontal direction, Moreover, passages 23, 23 for introducing paint mist-containing air from the direction along the upper end portion of each of these guide surfaces 5, 5 are formed in the middle of the width direction of the opening 20, branching left and right. Air purification device containing paint mist in a painting booth. 2 Each of the guide surfaces 5, 5 has a central angle of 180 degrees or approximately
The paint mist-containing air purifying device for a paint booth according to claim 1, which has a perfect circular arc shape of 180 degrees. 3. The paint mist-containing air purification device for a paint booth according to claim 1, wherein the bottom and upper surfaces of each of the introduction passages 23, 23 also serve as a flow surface for purification water.