JPH0157627B2 - - 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 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 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, as a method of contacting the paint mist-containing air with purifying water, 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 used. . In these figures A
is air containing paint mist, W is water for purification, 1 is a target plate, and 2 is a deflection plate. Each of these four has its advantages and disadvantages, but the main problem is that
In either case, the separation efficiency of paint mist is incomplete, especially the separation of mist with small particle size (10 microns or less).

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 v is the airflow velocity at the inlet 4.
As a first approximation, we ignore the deceleration of the airflow, and while R>
b, then the distance X(d) that the mist particles move radially outward due to centrifugal force due to the change in direction 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 ³ /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 effective width L is increased.

(b) Reduce X(d), that is, b. In other words, it divides the airflow.

(c) Increase v.

In the case of the target method, it is easy to understand if you think of increasing the effective width L.

That is, since α・(R+b/2)=L, the formula () becomes X(d)=L/R+b/2・(ρp/ρ−1)v/18ν・
This is because it can be expressed as d ² −().

Among the above (a), (b), and (c), the present invention covers (a) and (b).
The emphasis is on

In order to achieve the above object, the present invention provides horizontal or nearly horizontal collision surfaces in the downward flow path of paint mist-containing air, with the opening area between the collision surfaces decreasing in the downstream direction. In addition to providing multiple stages,
The collision surfaces other than the lowest stage are arranged symmetrically with respect to the central axis of the flow path, with the overflow end that causes purified water to flow down to the next stage on the inside and the air outflow end on the outside. The end and the air outflow end are both placed outside and arranged symmetrically about the central axis.

With this configuration, the present invention provides the following effects.

B. In the method of contacting and mixing air containing paint mist with water for purification, trapping the paint in the water, and separating the paint from the air, the ratio of the flow rate G of air containing paint mist to the amount of water L (L/G) determines the efficiency of the purifier. In other words, the efficiency is better when the amount of water is larger than the amount of air.

The purifying device of the present invention has a plurality of upper and lower collision surfaces which serve as separation and trapping surfaces for paint mist particles, and the paint mist-containing air is divided into a plurality of parts by the collision surface. Therefore, the width of the airflow of paint mist-containing air is reduced at each impingement surface, and the total effective width of all impingement surfaces is large. This is a configuration that satisfies both measures (a) and (b) above, and with this configuration, the water/air ratio increases and the critical diameter dc of the mist particles can be made considerably smaller than before. It is possible to improve the mist separation efficiency or reduce the critical diameter of the captured particles.

(b) With the configuration of the present invention, air passing through the upper collision surface can freely escape without being restrained. Therefore, the relatively clean air that has been separated from the paint mist does not cross the purification water in the lower stage where the paint concentration is high and become contaminated again, making it possible to improve the paint mist separation efficiency. .

C. The opening area decreases as it goes to the lower stage, whereas all of the water for purification flows to the lower stage, so the water/air ratio increases as the stage goes lower. Therefore, effective paint mist separation action can be expected even in the lower stage.

Note that there is no problem in using countermeasure (c) in conjunction with implementing the present invention.

Preferred embodiments of the present invention will be described below.

[] First example. Figures 6 and 7.

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
3 is a cleaning plate (tray) that slopes gently downward toward the outlet; 14 is a series of long partition plates; 16 is a diagonal bottom plate; 17 is a drainage groove; and 18 is a duct leading to the 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 mist particles.

Reference numeral 19 designates a flow path for the paint mist-containing air going downward, and 20 and 20 designate guide plates that form the flow path and guide the flow of overflowing purification water.
The guide plates 20, 20 are a long series. The flow path 19 has an elongated rectangular shape in cross section. The lower ends of the guide plates 20, 20 are bent inward. Below the lower ends 21, 21 of the guide plates 20, 20, target plates 6 are provided in four upper and lower stages, the upper surface of which is the collision surface 5. In the upper three stages, two plates 6 are arranged side by side symmetrically with respect to the central axis 22. The inner end of each plate 6 serves as an overflow end for purification water. There is one plate 6 in the fourth lowest stage, and it is symmetrical with respect to the central axis 22. All plates 6 have an elongated rectangular shape. Also, the separation end of the airflow is outward and slopes upwardly. Note that it is desirable that the collision surface 5 be coated with a substance such as Teflon that prevents the adhesion of paint particles.

[] Second example. Figure 8.

The air flow path 19 is formed by a cylindrical guide plate 23, the upper two plates 6 have an annular shape sharing the central axis 22, and the lowermost third plate 6 has a concentric circular shape. A plurality of such cylindrical ring type cylinders may be arranged in parallel, or if the diameter is large, only one cylinder may be used.

In each example, the number of six plate stages is arbitrary.

[Brief explanation of drawings]

Figures 1 to 4 are sectional views of conventional examples;
Fig. 5 is a model diagram explaining inertial separation, Figs. 6 to 8 illustrate embodiments of the present invention, Fig. 6 is a vertical cross-sectional view of almost the whole, and Fig. 7 is a vertical cross-section showing the main part. FIG. 8 is a perspective view. 5... Collision surface, 19... Air flow path, 22... Central axis.

Claims (1)

[Claims] 1 Flow path 19 for air containing paint mist heading downward
A horizontal or nearly horizontal collision surface 5 is provided within the collision surface 5.
In addition to providing upper and lower multiple stages with the opening area decreasing toward the downstream side, collision surfaces 5 outside the lowest stage are provided.
is arranged symmetrically with respect to the central axis 22 of the flow path 19, with the overflow end where the purified water flows down to the next stage being inside and the air outflow end being outside, and the collision surface 5 at the lowest stage is located between the overflow end and the air outlet end. A paint mist-containing air purifying device for a paint booth configured to be arranged symmetrically about the central axis 22 with both the outflow ends facing outside.