JPH0132416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a clean air supply system that removes minute particles and supplies dust-free clean air.

[Prior art and its problems]

As a system for removing this type of microparticles and supplying clean air, a system using a high-performance filter made of various types of folded high-density fine fiber material has been implemented. Among these high-performance filters, 0.3 μ
An ultra-high performance filter called a HEPA filter, which has a particle collection rate of 99.97% or more for particles of m, is the optimal and highest performance filter of this type. The configuration and operation of a conventional clean air supply system will be explained with reference to FIG.

In Fig. 1, 1 is a HEPA filter, 2 is a blower, 3 is a freezing/dehumidifying device, 4 is a heating device, 5 is a work area, 6 is a shower, 7 is an air flow path, 8 is introduced air, and 20 is a temperature detection device. shows.

The introduced air 8 is pre-washed with a shower 6, frozen and dehumidified with a freezing and dehumidifying device 3, and the cooled air is heated with a heating device 4 to reach a set temperature, and then passed through a HEPA filter 1 with a blower 2. It is flown into the working area 5 after removing fine particles. The air in the working area 5 is partially recycled together with the introduced air 8 through the airflow line 7. The heating device 4 is
According to the output signal of the temperature detection device 20, the work area 5
In the case of FIG. 1, the temperature is controlled by turning the heating device 4 on and off.

Regarding the conventional clean air supply system, the present inventors confirmed through experiments that it became clear that the conventional clean air supply system has the following drawbacks. It was previously believed that there was no correlation between the relative humidity of the supplied air and the cleanliness of the HEPA filter outlet air.
However, according to experiments conducted by the present inventors, it has become clear that the following correlation exists. It has been observed that when the relative humidity of the air supplied to the HEPA filter changes suddenly, microparticles collected by the HEPA filter are released from the HEPA filter, reducing the cleanliness of the air supplied to the work area. .

An example of the experimental results is shown in Figure 2. The horizontal axis in FIG. 2 represents the time axis, and the vertical axis represents the particle number concentration in the air supplied to the work area and the relative humidity of the air supplied to the HEPA filter. As is clear from Figure 2, while the relative humidity is approximately constant, the particle concentration is almost zero regardless of the relative humidity value, whereas the particle concentration sharply increases only when the relative humidity suddenly changes. , the concentration of particles larger than 0.3 μm is 5600 to 9450 particles/m ³
, and air cleanliness is declining.

Another example of the experimental results is shown in FIG. This experimental example shows a case where the relative humidity changes more slowly than the experimental example shown in Figure 2. In this case, the maximum particle concentration of 0.3 μm or more is 560 particles/ ^m3 , and the relative humidity It is recognized that there is no practical problem as long as the change is not rapid.

As mentioned above, in conventional clean air supply systems, the relative humidity of the air flowing to the HEPA filter changes suddenly due to turning on/off of the heating device and sudden changes in the temperature and humidity of the introduced air, causing the air flowing to the work area to change suddenly. The disadvantage was that air cleanliness decreased.

[Purpose of the invention]

An object of the present invention is to provide a clean air supply system capable of eliminating the drawbacks of the conventional systems and stably supplying highly clean air.

[Key points of the invention]

The present invention includes a relative humidity detection means for detecting the relative humidity of air flowing into a HEPA filter, and a relative humidity adjustment means for controlling the relative humidity to a predetermined value based on an output signal of the relative humidity detection means. The purpose is to adjust the relative humidity of the air flowing into the filter to prevent sudden changes in the relative humidity and to stably supply highly clean air.

[Embodiments of the invention]

FIG. 4 shows an embodiment of the present invention, in which the same components as in the conventional system are given the same reference numerals and their explanations will be omitted. In FIG. 4, reference numeral 9 indicates a relative humidity detection device which is a relative humidity detection means, and 13 indicates a humidification device which is a relative humidity adjustment means and includes a humidification steam blowing section 10, a humidification steam supply valve 11, and a humidification steam introduction section 12. .

In such a configuration, the freezing and dehumidifying capacity of the freezing and dehumidifying device 3 is such that the relative humidity of the frozen and dehumidified air is below a predetermined humidity, for example, 40 RH%, regardless of the temperature and humidity conditions of the introduced air 8. , the relative humidity of the air humidified by the humidifier 13 and flowing into the HEPA filter is, for example, 50RH.
%. If the heating device 4 is turned on or off, the relative humidity of the air flowing into the HEPA filter will change suddenly, but in the system shown in FIG. The relative humidity is controlled by turning on and off the humidifying steam supply valve 11 that controls the humidity to a predetermined value, thereby preventing sudden changes in the relative humidity. Although FIG. 4 shows an example in which the humidifying steam generating section 10 is provided in front of the heating device 4, it can also be provided in the rear of the heating device 4.

FIG. 5 shows another embodiment, and the difference from the one in FIG. 4 is that a humidifying device 16, which is a relative humidity adjusting means, is connected to a humidifying steam blowing section 10, a water reservoir 15, and a humidifying steam generating heater 14. In this structure, the relative humidity is controlled by the power of the humidifying steam generating heater 14.

FIG. 6 shows yet another embodiment, in which the relative humidity adjusting means includes a freezing and dehumidifying device 3 and a heating device 4.
It is. The relative humidity of the air flowing into the HEPA filter 1 is detected by the relative humidity detection device 9, and the relative humidity is controlled by turning on and off the freezing and dehumidifying device 3 and the heating device 4 based on the output signal of the relative humidity detection device 9. be.

〔Effect of the invention〕

According to the invention, a relative humidity detection means for detecting the relative humidity of air flowing into the HEPA filter;
By including a relative humidity adjusting means for controlling the relative humidity to a predetermined value based on the output signal of the relative humidity detecting means, the relative humidity of the air flowing into the HEPA filter is adjusted and sudden changes are prevented. , the effect of stably supplying highly clean air can be obtained.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a conventional clean air supply system, Fig. 2 is an example of experimental results for the conventional system, Fig. 3 is an example of experimental results different from Fig. 2, and Fig. 4 is an example of an embodiment of the present invention. FIG. 5 is a block diagram of a different embodiment of the present invention, and FIG. 6 is a block diagram of a further different embodiment of the present invention. 1: HEPA filter, 2: Air blower, 3: Refrigeration dehumidifier, 4: Heating device, 9: Relative humidity detection device, 10: Humidifying steam outlet, 11: Steam supply valve,
12: Humidifying steam introduction section, 14: Humidifying steam generation heater, 15: Water reservoir, 13, 16: Humidifying device.

Claims (1)

[Scope of Claims] 1. Clean air consisting of a filter that collects particulates, a blower that supplies air that is purified by the filter, a shower for pre-cleaning the air, a freezing and dehumidifying device, and a heating device. The supply system includes a relative humidity detection means for detecting the relative humidity of air flowing into the filter, and a relative humidity adjustment means for controlling the relative humidity to a predetermined value based on an output signal of the relative humidity detection means. Features a clean air supply system. 2. In the clean air supply system as set forth in claim 1, the relative humidity adjusting means is a humidifying device provided in front or behind the heating device and comprising a humidifying steam blowing part, a humidifying steam supply valve, and a humidifying steam introducing part. A clean air supply system characterized in that relative humidity is controlled by turning on and off the humidifying steam supply valve. 3 In the clean air supply system according to claim 1, the relative humidity adjusting means is a humidifying device provided in front or behind the heating device and comprising a humidifying steam outlet, a water reservoir, and a humidifying steam generating heater, and A clean air supply system characterized in that humidity is controlled by electric power of the humidifying steam generating heater. 4. In the clean air supply system according to claim 1, the relative humidity adjusting means is a freezing dehumidifying device and a heating device, and the relative humidity is controlled by turning on and off the freezing dehumidifying device and the heating device. clean air supply system.