JP2016101187A - Air purification system preventing reduction in decomposition efficiency of contaminated air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air purification system achieving further reduction of low concentration of pollutants in the air by solving the problem in that it is necessary to reduce the process air flow rate for noise reduction depending on the installation environment, and such a reduction in the air flow rate reduces the flow rate of the contaminated air in a reaction tube, resulting in a reduction in decomposition efficiency of contaminants.SOLUTION: There is provided an air purification system that achieves a mechanism for preventing a reduction in the decomposition efficiency of the contaminated air by maintaining decomposition reaction characteristics in a reaction tube inside the system even when the capacity of a fan for introducing the contaminated air into the reaction tube is lowered to reduce air flow rate. The air purification system can maintain the performance regardless of the process air flow rate by incorporating a gas flow passage cross-sectional area adjusting function for achieving the above in the system and causing the function to be operated according to air flow rate control.SELECTED DRAWING: Figure 9

Description

Air purification used in a relatively small space for the purpose of preventing health damage caused by long-term inhalation of low-concentration VOCs and odorous substances, and improving the indoor environment by sterilization and inactivation of viruses. Relates to the device.

The air purification device includes a device that removes substances such as dust in a broad sense, but in the present invention, it refers to a device that removes chemical substances such as VOCs and odorous substances. Used in general households, offices, hospitals, factories, etc.

In particular, in hospitals and clinics where ventilation is not sufficient, there is a strong demand for development of processing devices such as small VOCs that are compatible with bacteria and viruses. In the waiting room, consideration must be given to the air environment only where an unspecified number of physically vulnerable persons gather.

As an air purification device, a removal device that lowers the concentration of high concentration VOC at a level of several hundred ppm has been commercialized, but a removal device that makes low concentration VOC or the like zero is hardly commercially available.

Many of the purification means use a photocatalytic functional film. By irradiating the photocatalytic functional film with ultraviolet light or the like, the photocatalyst is excited to decompose the chemical substance. However, due to the characteristics of the photocatalyst, the reaction rate is slow and it is possible to cope with the removal of a small amount of chemical substances.

In order to improve the efficiency of the decomposition reaction by such a photocatalyst, the positional relationship between the photocatalyst excitation light source and the photocatalyst functional film has been devised. In JP-A-2000-262606, a plurality of photocatalyst tubes are arranged in parallel. An arranged air purification device is disclosed.

JP 2000-262606 A

The photocatalyst is excited by irradiation with ultraviolet rays or the like, and decomposes VOC or the like. However, if the decomposition product stays in the vicinity of the photocatalyst functional film, VOC or the like is not supplied to the photocatalyst and inhibits new decomposition.

In order to prevent the decomposition products from staying in the vicinity of the photocatalytic functional film, it is necessary to maintain the gas flow velocity in the vicinity of the photocatalytic functional film at a high speed, but in a quiet environment such as a home, office, or hospital. Then, it is considered that there are many cases where the fan air volume is decreased, and as a result, the gas flow rate in the vicinity of the photocatalytic functional film cannot be maintained and the operation is slowed down, and the decomposition efficiency is lowered.

An object of the present invention is to provide an air purification device in which the flow rate does not slow in the vicinity of the photocatalytic functional film and the decomposition efficiency by the photocatalyst does not decrease even when the fan air volume is reduced.

In order to solve the above problems, an air purification device according to the present invention is provided in the air purification device in order to suppress residence of decomposition products decomposed by the photocatalyst in the vicinity of the photocatalytic functional film in the air purification device. The gas flow passage cross-sectional area is changed so as to ensure the flow velocity even when the fan air volume is reduced.

An adjustment mechanism such as a lid type or a shutter type is added to adjust the cross-sectional area of the gas flow path according to the fan air volume.

It is a figure which shows the structure of a reaction tube. It is a figure which shows the structure of the reaction tube assembly. It is a figure which shows the structure of the air purification apparatus which concerns on embodiment of this invention. It is a figure which shows the relationship between a fan air volume and the flow velocity in a reaction tube. It is a figure which shows the relationship between a gas flow-path cross-sectional area and the flow velocity in a reaction tube. It is a figure which shows the relationship between the flow velocity in a reaction tube, and decomposition | disassembly efficiency, such as contaminated air. It is a figure which shows the example which opens and closes the inlet port of a reaction tube in a group. It is a figure which shows the example which opens and closes the inlet port of a reaction tube separately. It is a figure which shows the structure of the inlet port part in the air purification apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of the slide shutter of an air purifying apparatus, Comprising: It is a mechanism which plugs the inlet of a reaction tube for every one or two with a slide mechanism. It is a figure which shows the structure of the shutter accommodating part of the slide shutter of an air purifying apparatus. It is a figure which shows the spiral airflow generation | occurrence | production structure provided in the reaction tube.

An adsorbent such as activated carbon coated with a photocatalyst is fixed to the inner wall of a cylindrical tube, and a photocatalyst excitation light source having a length substantially equal to the cylindrical tube is inserted into the cylindrical tube. A tube in which the light source is fixed at the center so that the distance to the tube is uniform is called a reaction tube.

The inside of the reaction tube becomes a gas flow path to be purified.

The distance between the photocatalyst excitation light source and the photocatalytic functional film is set to a distance at which the decomposition reaction is efficiently performed. For the interval,
An example is shown here.

Depending on the processing capacity required for the air purifier, a required number of reaction tubes are arranged in parallel, and a fan with a high static pressure is installed to satisfy the air flow rate in the flow passages narrowed down in each reaction tube.

An embodiment of the present invention will be described. The air purification device is composed of a reaction tube assembly in which a fan and a plurality of reaction tubes are assembled. The fan provided on the discharge port side creates a negative pressure in the device and sucks contaminated air into the air purification device. The contaminated air is decomposed and adsorbed while passing through the inside of the reaction tube assembly, and the purified air is sent out of the apparatus by a fan. In another example, a fan can be provided on the inlet side to create a positive pressure in the apparatus, thereby creating a flow rate of air necessary for the reaction in the reaction tube.

When reducing the air volume of the fan, the cross-sectional area is reduced by closing the gas flow path in units of reaction tubes, and the necessary flow velocity in the reaction tube can be ensured even if the fan air volume is small.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In one embodiment of the present invention, the reaction tubes 2 as shown in FIG. 1 constitute six reaction tube assemblies as shown in FIG. The number and arrangement method of the reaction tubes 2 can be changed according to the size restricted by the processing capacity and the installation area of the air purifier.

As shown in FIG. 1, the reaction tube 2 has an activated carbon 5 fixed on the entire inner wall of the cylinder with a binder and coated with a photocatalytic functional film 6.

A rod-like photocatalyst excitation light source 4 is installed at the center of the cylinder of the reaction tube 2, and the photocatalyst is excited by the photocatalyst excitation light source 4. The light source may be of any type as long as it has a function of efficiently generating ultraviolet rays for excitation and sterilization of the photocatalyst. A light emitting device such as a cold cathode tube, a hot cathode tube, or a semiconductor such as an LED may be used.

The inside of each reaction tube becomes a flow path of the contaminated air 11. The photocatalyst excited by ultraviolet rays decomposes chemical substances such as VOC and odorous substances, and the activated carbon 5 adsorbs the decomposition products.

By the mechanism described above, the air that has passed through the reaction tube 2 becomes clean air 10 from which VOCs and odorous substances have been removed.

The shape of the photocatalyst excitation light source 4 is not limited to a rod shape but may be a U-shaped tube shape as long as the light intensity necessary for the photocatalytic reaction in the reaction tube 2 is obtained. Accordingly, the cross-sectional shape of the reaction tube 2 can be changed to an ellipse or the like.

FIG. 3 is a schematic view of a reaction tube assembly and an air purification device using a fan 8.

Contaminated air 11 is taken into the apparatus by the fan 8, and the clean air 10 purified by the reaction tube assembly is discharged out of the apparatus.

As long as the reaction tube assembly is configured to enter the flow of air by the fan 8, the arrangement thereof does not have to be performed by the illustrated method. The fan 8 may be present on both sides of the reaction tube assembly. If the flow velocity in the reaction tube 2 is ensured, the position of the fan is not defined.

In the schematic diagram of the air purification apparatus shown in FIG. 3, the graph showing the relationship between the air flow rate of the fan and the flow velocity in the reaction tube generally has a relationship as shown in FIG. 4 if pressure loss is ignored. The flow velocity in the reaction tube changes in proportion to the air volume of the fan.

The fan airflow is generally switched stepwise such as strong, medium, and weak, but the airflow can be changed continuously.

In quiet environments such as homes, offices, and hospitals, or in environments that do not like blowing with a large air volume, it is considered that there are many cases where the fan 8 is operated with a reduced air volume, in which case it passes through the reaction tube 2. The flow rate of air to be reduced is also reduced.

As a result, the reaction product tends to stay in the vicinity of the photocatalytic functional film in the reaction tube 2, the supply of new contaminated air is hindered, and the decomposition efficiency deteriorates.

Even when the air volume of the fan 8 is lowered, in order to maintain the flow velocity in the reaction tube 2 necessary for good decomposition efficiency, the gas flow channel cross-sectional area may be reduced to increase the flow velocity per unit area.

Since the exhaust air volume is the volume of the wind passing per unit area, it is expressed by the product of the unit area and the flow velocity. Therefore, the relationship between the gas channel cross-sectional area and the flow velocity in the reaction tube with the air volume of the fan 8 as a parameter is as shown in FIG. 5 if the pressure loss is ignored.
If the air volume is constant and the pressure is maintained, the flow velocity increases as the cross sectional area passing through decreases.

Also, a graph of the flow rate in the reaction tube and the decomposition efficiency such as VOC in the vicinity of the photocatalytic functional film is as shown in FIG.
The decomposition efficiency increases as the wind speed increases. As the wind speed increases, the decomposition efficiency slows down, but shows a characteristic of increasing to the right.

From FIG. 5 and FIG. 6, even if the air volume of the fan 8 is lowered, the flow velocity in the reaction tube 2 can be secured by reducing the gas flow path cross-sectional area, and as a result, the degradation efficiency can be prevented from being lowered. it can.

Next, a method for adjusting the gas channel cross-sectional area will be described.

The reaction tube assembly is composed of a plurality of reaction tubes 2 as shown in FIG.

By covering the inlets of some of the reaction tubes 2 in the reaction tube assembly, the flow velocity in the reaction tubes 2 without the lid can be increased. In the air purification apparatus as shown in FIG. 3, at the both ends of the reaction tube 2, the one far from the fan 8 becomes the intake port.

An example of the lid is shown in FIG. In FIG. 7, one lid 13 can close the intake ports of three reaction tubes 2 among all six reaction tubes 2. As a result, the space through which air passes is halved, and in a general interpretation ignoring the pressure loss, the flow velocity in the reaction tube 2 without the lid is twice that before the lid is closed, and the decomposition efficiency due to the decrease in the air volume of the fan 8 The decrease can be suppressed.

Another lid example is shown in FIG. In FIG. 8, the lid 13 is separated for each reaction tube, and the reaction tube can be closed individually. In FIG. 8, there are three reaction tubes with lids. However, by attaching lids to all six tubes, it becomes possible to control whether or not the six reaction tubes are to be covered. Although there is no operation, the range of adjustment is expanded.

7 and 8 show an example of a door-type lid as an example, but the method is not limited to this example. Any other method may be used as long as it can control opening and closing of the intake port or the exhaust port of the reaction tube 2.

7 and 8 show an example of a method for securing the flow velocity in the remaining reaction tubes 2 where the intake ports are not closed by individually opening and closing the intake ports of the reaction tubes 2. It is also possible to adjust the inlet of the air in stages.

In the example of FIG. 9, by providing a shutter-type shielding plate that adjusts the intake port area for each reaction tube of the air purification device, the flow velocity in each reaction tube of the reaction tube assembly can be adjusted.

As shown in FIG. 10, a method of adjusting the area by inserting / removing the sliding shutter 9 from both sides and individually closing the intake port individually for each reaction tube is conceivable. If the shutters on both sides are housed along the inner wall of the housing of the air purification device as shown in FIG. 11, the size of the air purification device housing 1 that is changed by adding the shutter can be minimized. .

As another method for ensuring the surface flow rate of the photocatalytic functional film in the reaction tube while reducing the total air flow, in order to generate a spiral flow in the reaction tube, a spiral air flow is generated in the air as shown in FIG. It is also effective to provide the rotary guide vanes 14 in a part or a plurality of locations in the intake port or reaction tube so as not to obstruct the light from the photocatalyst excitation light source.

DESCRIPTION OF SYMBOLS 1 Air purifier housing | casing, 2 Reaction tube, 3 Inner wall coated with binder, 4 Light source for photocatalyst excitation, 5 Activated carbon, 6 Photocatalyst functional film, 7 Light source electrode for photocatalyst excitation, 8 Fan, 9 Sliding shutter, 10 Clean air, 11 Contaminated air, 12 Air purifier air inlet,
13 lid, 14 rotating guide vanes.

Claims (3)

Each reaction inside the air purification device in the air purification device having a photocatalyst functional film, a light source for photocatalyst excitation, a plurality of reaction tubes composed of an adsorbent such as activated carbon, and a fan for introducing contaminated air into each reaction tube By selectively using a pipe, it has means for changing the cross-sectional area of the gas flow path through which air flows, and when the air volume is reduced, the cross-sectional area of the gas flow path is decreased and each reaction pipe in the air purifier is An air purification apparatus that ensures a linear flow velocity of flowing air and does not cause degradation of the decomposition efficiency of contaminated air. 2. The air purification device according to claim 1, wherein the gas flow passage cross-sectional area is preferably set and the decomposition efficiency is not lowered, and the degradation efficiency of contaminated air is not reduced. 2. The air purification apparatus according to claim 1, wherein a mechanism for generating an air vortex in the reaction tube is attached, the flow rate is increased, and the air staying in the tube is stripped off. No air purification device.