JP7560976B2 - Air purification filter unit and air purification fence structure - Google Patents

Description

The present invention relates to an air purification filter unit and an air purification fence structure for removing contaminants contained in air entering and leaving an area to be purified.

In recent years, technological developments have been underway to remove pollutants such as nitrogen oxides (NOx), sulfur oxides (SOx), and volatile organic compounds (VOCs), as well as fine particulate matter (particles), from the air that enters and leaves the purification areas where air pollution is severe, such as roads on which vehicles pass and industrial areas densely populated with power plants and factories, where there is a high volume of automobile traffic.

For example, as shown in Patent Document 1, a technology for removing pollutants and fine particles from the air entering and leaving a purification target area such as a road is used in which a catalytic purification unit in which a catalytic fiber sheet material capable of removing pollutants contained in the air is arranged in a ventilation passage through which the air flows, and a fine particle filter made of an electrostatically charged nonwoven fabric capable of removing fine particles contained in the air are provided as an air purification filter unit. Specifically, the air purification filter unit is arranged such that a plurality of catalytic fiber sheet materials are stacked side by side with a ventilation space formed between adjacent catalytic fiber sheet materials along the ventilation direction in the ventilation passage, and a breathable spacer is sandwiched in this ventilation space, and the sheet-like electrostatically charged nonwoven fabric is arranged in the catalytic purification unit in a state where it covers the opening in the ventilation space. Also, an air purification fence structure is known in which such air purification filter units are stacked so as to surround at least a part of the periphery of the purification target area with the ventilation direction in the ventilation passage as the thickness direction.

In this type of air purification filter unit, multiple catalyst fiber sheet materials are stacked and arranged in a state where a ventilation space is formed along the surface of the catalyst fiber sheet between adjacent catalyst fiber sheet materials, so that air can flow through the ventilation space and come into contact with the catalyst fiber sheet material, thereby removing pollutants. As a result, air can be purified with little ventilation resistance, and pressure loss can be made very small.

In particular, the oxidation and removal of NOx requires a relatively long contact time. However, in the air purification filter unit, the air flowing through the ventilation space formed between adjacent catalytic fiber sheet materials flows along the surface of the catalytic fiber sheet material for a relatively long time, and even some of the air gets between the fibers of the catalytic fiber sheet material, so that the pollutants contained in the air can be effectively brought into contact with the catalytic fibers and oxidized and removed.

Furthermore, in the air purification filter unit, a sheet-like particulate filter made of electrostatically charged nonwoven fabric that removes particulates contained in air passing through in the thickness direction is arranged in the catalyst purification unit in a state where it covers the opening in the ventilation space. The air containing particulates is rectified by the ventilation space and collides with the particulate filter from a direction intersecting the surface of the particulate filter with the flow direction aligned. Therefore, the particulate filter can exert its particulate capture ability while allowing the air to pass through well against the airflow resistance in the thickness direction. As a result, the particulates can be removed by electrostatically adsorbing and holding them on the particulate filter without significantly increasing the overall pressure loss.

JP 2020-28852 A

However, even in the above-mentioned conventional air purification filters, the air containing fine particles must pass through the sheet-like fine particle filter (electrostatic nonwoven fabric) in the thickness direction, and an increase in ventilation resistance is unavoidable. Therefore, although the fine particle removal rate is high, it cannot be said to be sufficient in terms of the amount of removal.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an air purification filter unit and an air purification fence structure that can perform both catalytic purification function and particulate removal function better than conventional methods.

The characteristic configuration of the air purification filter unit of the present invention for achieving the above object is a catalytic purification unit in which a plurality of catalyst fiber sheet materials are stacked and arranged to form a ventilation space along the surface of the catalyst fiber sheet materials between adjacent ones of the plurality of catalyst fiber sheet materials, and a separator made of a sheet-like electrostatically-charged nonwoven fabric is arranged in the ventilation space so that the surface direction is parallel to the ventilation direction in the ventilation space,
The separator serves to remove fine particles contained in the air flowing along the surface direction of the electrostatically charged nonwoven fabric.

According to the above characteristic configuration, the air purification filter unit has a catalytic fiber sheet and a separator, so the air passing through the air purification filter unit comes into contact with both the catalytic fiber sheet and the electrically charged nonwoven fabric of the separator. This allows pollutants such as NOx contained in the air to be captured and rendered harmless by the catalytic fiber sheet, while fine particles can be removed by the electrically charged nonwoven fabric of the separator, so that both the catalytic purification function and the fine particle removal function can be achieved.

Specifically, since a plurality of catalyst fiber sheet materials are stacked and arranged in a state in which a ventilation space is formed along the surface of the catalyst fiber sheet between adjacent catalyst fiber sheet materials, the air can be removed by contacting the catalyst fiber sheet material while flowing through the ventilation space. As a result, the air can be purified with little ventilation resistance, and an air purification filter unit with extremely little pressure loss can be obtained. In addition, the air flowing through the ventilation space formed between the adjacent catalyst fiber sheet materials flows along the surface of the catalyst fiber sheet material for a relatively long time, and even a small amount of air enters between the fibers of the catalyst fiber sheet material, so that the pollutants contained in the air are well contacted with the catalyst fibers and oxidized and removed. In particular, a relatively long contact time is required for the oxidation and removal of NOx, so the configuration in which the air flows along the surface of the catalyst fiber sheet material for a relatively long time as described above is effective.
Therefore, by reducing the pressure loss that occurs when air is passed through the ventilation space formed between adjacent catalyst fiber sheet materials, it is possible to pass air through the ventilation space using only natural wind or the like without the need for a separate blower, and it is possible to realize an air purification filter unit that can effectively remove pollutants contained in the air.

The separator, which is made of an electrically charged nonwoven fabric and removes fine particles contained in the air flowing along the surface direction of the electrically charged nonwoven fabric, is arranged in the ventilation space so that the surface direction is parallel to the ventilation direction in the ventilation space. Therefore, the air containing fine particles flows through the ventilation space and comes into contact with the electrically charged nonwoven fabric, and the electrically charged nonwoven fabric electrostatically adsorbs and holds the fine particles, thereby removing the fine particles. That is, in the air purification filter unit having the above characteristic configuration, unlike conventional air purification filter units, the air containing fine particles does not need to pass through the electrically charged nonwoven fabric in the thickness direction, so that the fine particles can be effectively removed without increasing the ventilation resistance, and not only the removal rate but also the removal amount is large. Furthermore, since the air flowing through the ventilation space flows through the ventilation space for a relatively long time, the fine particles contained in the air are effectively captured by the electrically charged nonwoven fabric even if the surface direction of the electrically charged nonwoven fabric is parallel to the ventilation direction in the ventilation space.

In this way, in an air purification filter unit having the above characteristic configuration, the air passing through the air purification filter comes into contact with the catalytic fiber sheet material and the separator. This allows pollutants such as NOx contained in the air to be rendered harmless by the action of the catalytic fiber sheet material, and fine particles can be removed by the separator, so that both the catalytic purification function and the fine particle removal function can be achieved.

A further characteristic feature of the air purification filter unit according to the present invention is that the catalyst fiber sheet material is activated carbon fiber.

The above characteristic configuration has a high purification effect on pollutants, especially NOx, so it is highly useful for catalytic purification of automobile exhaust gases, etc.

A further characteristic feature of the air purification filter unit according to the present invention is that the separator is made by forming the sheet-like electrostatically-charged nonwoven fabric into a pleated shape, and is disposed in the ventilation space so that the top portion extends along the ventilation direction in the ventilation space.

According to the above characteristic configuration, the air flowing through the ventilation space comes into contact with both sides of the separator, so that fine particles contained in the air are effectively captured by the electrically charged nonwoven fabric that constitutes the separator. In addition, according to the above characteristic configuration, the ventilation space formed between each of the multiple adjacent catalyst fiber sheet materials is maintained in shape by the separator, so that the ventilation space becomes extremely narrow, making it difficult for air to flow, and other problems can be prevented.

A further characteristic feature of the air purification filter unit according to the present invention is that it comprises a main casing having air ports formed on both sides thereof that are open to the outside air, a ventilation passage is formed inside the main casing that connects both of the air ports, and the catalytic purification unit is disposed in the ventilation passage so that the air ports communicate with an opening in the ventilation space.

According to this characteristic configuration, the catalytic purification unit is arranged in a ventilation passage that communicates with both air ports formed on both sides of the main casing, with the air port communicating with an opening in the ventilation space. Therefore, air passing through the ventilation passage flows smoothly into the ventilation space of the catalytic purification unit, and the passing air comes into contact with the catalytic fiber sheet material and the separator. This allows the catalytic purification function of the catalytic fiber sheet material for pollutants and the particulate removal function of the separator to be satisfactorily achieved with a simple configuration.

The characteristic configuration of the air purifying fence structure of the present invention for achieving the above-mentioned object is that it is an air purifying fence structure for removing pollutants contained in the air entering and leaving the area to be purified, and is composed of a plurality of air purifying filter units stacked so as to surround at least a portion of the periphery of the area to be purified, with the air flow direction in the ventilation passage being the thickness direction.
Furthermore, it is more preferable that the area to be purified is a road and that the sheets are arranged in layers along the road.

With this characteristic configuration, the air flowing in and out of the area to be purified can be efficiently circulated through each ventilation passage using only natural wind, etc., without the need for a separate blower, and pollutants and fine particles contained in the air can be efficiently removed.

When the air purification filter unit is used as an air purification fence structure, the direction of air flow through the air purification filter unit may change depending on environmental conditions, but it is preferable to position the air purification filter unit so that the catalytic purification function and particulate removal function are sufficiently exerted for airflow from any direction.

FIG. 2 is a perspective view of the air cleaning filter unit. FIG. 2 is a cross-sectional elevation view of the air purification filter unit. FIG. 2 is a cross-sectional plan view of the air cleaning filter unit. FIG. 2 shows the air purifying fence structure positioned relative to the area to be purified. FIG. 2 shows the air purifying fence structure positioned relative to the area to be purified. 1 is a graph showing particulate removal performance (2.5 μm or more and 5.0 μm or less). 1 is a graph showing particulate removal performance (1.0 μm or more and less than 2.5 μm). 1 is a graph showing particulate removal performance (0.3 μm or more and less than 1.0 μm). 3 is a graph showing NOx removal performance.

The following describes an air purification filter unit and an air purification fence structure according to an embodiment of the present invention. Note that although preferred examples are described below, each of these examples is described to more specifically illustrate the present invention, and various modifications are possible without departing from the spirit of the present invention, and the present invention is not limited to the following description.

[Air purification filter unit]
An air cleaning filter unit 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

As shown in Figures 1 to 3, the air purification filter unit 1 includes a catalyst purification unit 1A in which a plurality of catalyst fiber sheet materials 2 are stacked to form a ventilation space 10a along the surface of the catalyst fiber sheet materials 2 between adjacent catalyst fiber sheet materials 2, and a separator 5 made of a sheet-like electrostatically charged nonwoven fabric is arranged in the ventilation space 10a so that the surface direction is parallel to the ventilation direction in the ventilation space 10a, and the separator 5 is configured to remove fine particles contained in the air flowing along the surface direction of the electrostatically charged nonwoven fabric.

1 and 3, the air purification filter unit 1 includes a main casing 20 having air ports 22 formed on both side surfaces thereof, the air ports 22 being open to the outside air, and a ventilation passage 10 is formed inside the main casing 20, the ventilation passage 10 communicating with both air ports 22. A catalytic purification unit 1A is disposed in the ventilation passage 10.
That is, the main casing 20 includes a pair of plate-like members 24 on both sides in the width direction, and a pair of wire meshes 26 on both sides in the length direction. Each wire mesh 26 is fixed by a rectangular frame member (not shown) that is provided across the upper ends or lower ends of the pair of plate-like members 24. The main casing 20 includes air vents 22 at both ends in the thickness direction, and includes a ventilation passage 10 with a rectangular cross section perpendicular to the thickness direction inside, with these air vents 22 communicating with each other. That is, the main casing 20 is formed in a rectangular tube shape with air vents 22 at both ends in the thickness direction. The main casing 20 can be easily manufactured by forming a frame from aluminum or plastic plates.
As a result, in the air purification filter unit 1, a pair of air ports 22 formed on both sides of the main casing 20 are open to the outside air, so that when air A, such as natural wind, blows in a certain direction, one of the pair of air ports 22 opens toward the upstream side of the flow of air A, and the other opens toward the downstream side of the flow of air A, as shown in Fig. 1. In other words, the flow direction of air passing between the pair of air ports 22 becomes the ventilation direction of the ventilation passage 10. In this embodiment, the ventilation direction is the thickness direction of the main casing 20.

[Catalyst purification unit]
The catalytic purification unit 1A is configured by arranging a catalytic fiber sheet material 2, which is made of sheet-like catalytic fibers capable of removing pollutants contained in the air A, in an air passage 10 formed inside a main casing 20 and through which air A flows. That is, the catalytic purification unit 1A causes air A to flow through the air passage 10, thereby bringing the pollutants contained in the air A into contact with the catalytic fibers constituting the catalytic fiber sheet material 2, and oxidizing and removing them through the catalytic function.

Furthermore, the catalytic purification unit 1A is configured to reduce the pressure loss that occurs when air A is passed through the ventilation passage 10 in which the catalytic fiber sheet material 2 is arranged, so that air A can be passed through the ventilation passage 10 using only natural wind or the like without the need for a separate blower, and pollutants contained in the air A can be effectively removed.

Specifically, in the ventilation passage 10, a plurality of catalyst fiber sheet materials 2 are stacked and arranged while forming a ventilation space 10a between adjacent ones along the ventilation direction. That is, in the ventilation passage 10, a plurality of catalyst fiber sheet materials 2 are stacked and arranged with the surface of each catalyst fiber sheet material 2 parallel to the ventilation direction, and each catalyst fiber sheet material 2 is spaced apart so that a ventilation space 10a along the ventilation direction is formed between each of the adjacent catalyst fiber sheet materials 2. Therefore, in the ventilation passage 10, the air A flows through the ventilation space 10a along the surface of the catalyst fiber sheet material 2, and the pressure loss that occurs at that time is very small compared to the case where all the air A passes through the catalyst fiber sheet material 2. In addition, the plurality of catalyst fiber sheet materials 2 in this embodiment are stacked and arranged with the surface of each catalyst fiber sheet material 2 parallel to the vertical width direction of the main casing 20 and the catalyst fiber sheet materials 2 lined up in the horizontal width direction.

The catalyst fiber constituting the catalyst fiber sheet material 2 is made of activated carbon fiber capable of effectively oxidizing and removing pollutants in the air A, particularly NOx.
The activated carbon fibers constituting the above-mentioned catalyst fiber sheet material 2 preferably have a specific surface area within the range of 400 to 500 ^m2 /g as measured by the nitrogen adsorption method, and in the pore distribution analyzed by the MP method, micropores with a diameter of 2 nm or less are preferably those with a diameter of 1 nm or less that account for 80% or more of the total micropore volume. The adsorption and catalytic functions of such activated carbon fibers make it possible to remove nitric oxide (NO), which is particularly difficult to remove at room temperature, from the NOx that causes air pollution, over a long period of time at room temperature.
Furthermore, as the activated carbon fiber constituting the above-mentioned catalyst fiber sheet material 2, it is more preferable to use pitch-based activated carbon fiber (e.g., "A-5" manufactured by A-DOLL Co., Ltd.) or polyacrylonitrile (PAN)-based activated carbon fiber, which can more effectively remove NOx in particular.

The catalyst fiber sheet material 2 is made of activated carbon fiber processed into a sheet-like nonwoven fabric.

In addition, the catalyst fiber sheet material 2 used has a flat rectangular cross-sectional shape in the ventilation direction of the ventilation passage 10, and further, multiple catalyst fiber sheet materials 2 formed in a flat plate shape are stacked in the ventilation passage 10 with separators 5 made of electrostatically charged nonwoven fabric sandwiched between adjacent ones.
That is, in the ventilation passage 10, a plurality of catalyst fiber sheet materials 2 and a plurality of separators 5 are alternately stacked, and a ventilation space 10a formed between adjacent ones of the plurality of catalyst fiber sheet materials 2 is maintained in shape by the separators 5. In the ventilation space 10a, the air A flows smoothly between the separators 5 and the catalyst fiber sheet materials 2 while suppressing an increase in pressure loss.

In this embodiment, the separator 5 is a sheet of electrostatically charged nonwoven fabric molded into a pleated shape, and is arranged in the ventilation space 10a so that the tops extend along the ventilation direction in the ventilation space 10a. Therefore, air A flows along the tops of the pleats while coming into contact with both the front and back surfaces of the separator 5 in the ventilation space 10a.

The charged nonwoven fabric is preferably a nonwoven fabric that has been subjected to an electret treatment. As the electret treatment, known methods can be used, such as methods that use electrical action, such as polarization by high voltage, collision of charged ions, and injection of charged particles, methods that use interaction with solids, such as friction and collision, and methods that use contact and collision with liquid. From the viewpoints of low pressure loss and high efficiency in removing fine particles, methods that use contact with liquid or methods that use friction with solids are preferred.

The electrostatically-charged nonwoven fabric preferably includes a reinforcing net. The reinforcing net is intended to impart rigidity to the electrostatically-charged nonwoven fabric and improve its shape retention and processability. Synthetic fibers, inorganic fibers, and metal fibers can be used as materials for the reinforcing net, but from the viewpoints of thermal adhesion and processability, it is preferable to use synthetic fibers.

In this embodiment, as shown in Figures 1 and 3, in the catalytic purification unit 1A, a plurality of catalytic fiber sheet materials 2 are stacked in the ventilation passage 10 with the surface of each catalytic fiber sheet material 2 parallel to the ventilation direction, and each catalytic fiber sheet material 2 is spaced apart so that a ventilation space 10a along the ventilation direction is formed between each of the adjacent catalytic fiber sheet materials 2. Separators 5 are also arranged between each of the adjacent catalytic fiber sheet materials 2. A plurality of one-end openings 21a are formed as openings 21 at one end side in the flow direction of the ventilation space 10a formed by the catalytic purification unit 1A, and a plurality of other-end openings 21b are formed as openings 21 at the other end side. The catalytic converter unit 1A is arranged in the ventilation passage 10 so that each of the openings 21a on one end side is located on one of the air ports 22 in the main casing 20, and each of the openings 21b on the other end side is located on the other of the air ports 22 in the main casing 20.

In the air purification filter unit 1 having the above configuration, even if the flow of air A, such as natural wind, flowing from the upstream air port 22 through the ventilation passage 10 to the downstream air port 22 is relatively weak, as shown in FIG. 3, the air A will flow from the upstream air port 22 through the one end opening 21a of the catalytic purification unit 1A, the ventilation space 10a, and the other end opening 21b, and will be discharged to the outside of the air purification filter unit 1 from the other end opening 21b.

Therefore, the air purification filter unit 1 can purify air with little ventilation resistance and remove pollutants by contacting the catalytic fiber sheet material 2 while the air A flows through the ventilation space 10a, and is an air purification filter unit with extremely little pressure loss. Furthermore, in the air purification filter unit 1, the air A flowing through the ventilation space 10a formed between adjacent catalytic fiber sheet materials 2 flows along the surface of the catalytic fiber sheet material 2 for a relatively long time, and even a small amount of air enters between the fibers of the catalytic fiber sheet material 2, so that the pollutants contained in the air A come into good contact with the catalytic fibers and are oxidized and removed. Therefore, this air purification filter unit 1 reduces the pressure loss that occurs when air A flows through the ventilation space 10a formed between adjacent catalytic fiber sheet materials 2, and can flow air A through the ventilation space 10a only by natural wind without providing a separate blower, and can effectively remove pollutants contained in the air A.

Furthermore, in the air purification filter unit 1, the air A containing fine particles comes into contact with the charged nonwoven fabric while flowing through the ventilation space 10a, and the charged nonwoven fabric electrostatically attracts and holds the fine particles, thereby removing the fine particles. That is, unlike conventional air purification filter units, the air A containing fine particles does not need to pass through the charged nonwoven fabric in the thickness direction, so that the air resistance does not increase and the fine particles can be effectively removed, and not only the removal rate but also the amount of removal is large. Furthermore, the air A flowing through the ventilation space 10a flows through the ventilation space 10a for a relatively long time, so that even if the surface direction of the charged nonwoven fabric is parallel to the ventilation direction in the ventilation space 10a, the fine particles contained in the air are effectively captured by the charged nonwoven fabric.

In this way, in the air purification filter unit 1 according to this embodiment, the air A passing through the air purification filter unit 1 comes into contact with the catalytic fiber sheet material 2 and the separator 5 without a significant increase in pressure loss. As a result, pollutants such as NOx contained in the air A can be rendered harmless by the action of the catalytic fiber sheet material 2, and fine particles can be removed by the separator 5, so that both the catalytic purification function and the fine particle removal function can be achieved.

[Air Purifying Fence Structure]
An embodiment of an air purifying fence structure 30 according to the present invention will be described with reference to Figures 4 and 5. Figures 4 and 5 are diagrams showing the state in which the air purifying fence structure 30 is placed in the area to be purified.

4 and 5, an air purification method for removing pollutants contained in air A entering and leaving a target purification area such as a highway 50 is realized by arranging a plurality of the air purification filter units 1 described thus far in parallel along the periphery of the target purification area such as a highway 50, with the thickness direction being the airflow direction in the ventilation passage 10. For example, a plurality of air purification filter units 1 are arranged along the periphery of the target purification area, with one of the air ports 22 formed in the main casing 20 facing the target purification area.
In other words, the air purification filter unit 1 has small pressure loss when air A is passed through the ventilation passage 10 in which the catalytic fiber sheet material 2 and separator 5 are arranged, so that without the need for a separate blower, the air A entering and leaving the highway 50 can be smoothly passed through the ventilation passage 10 using only natural wind on the highway 50 or wind generated by automobiles traveling on the highway 50, and the pollutants contained in the air A can be effectively brought into contact with the catalytic fiber sheet material 2 for oxidization and removal, and further the fine particles contained in the air A can be brought into contact with the separator 5 made of an electrostatically charged nonwoven fabric for adsorption and removal.

The above air purification method can also be carried out by an air purification fence structure 30 shown in FIGS.
That is, the air purifying fence structure 30 for removing pollutants and fine particles contained in the air A entering and leaving a purification target area such as a highway 50 is formed by stacking a plurality of the above-mentioned air purifying filter units 1 so as to surround at least a portion of the periphery of the purification target area such as a highway 50, with the air flow direction in the ventilation passage 10 being the thickness direction.

For example, as shown in Figure 4, in an air purifying fence structure 30 formed by stacking the above-mentioned air purifying filter units 1 in multiple rows and multiple stages along the boundary between a motorway 50 and a sidewalk 51, a flow of air A is generated from the motorway 50 side to the sidewalk 51 side when a vehicle passes over the motorway 50.
Therefore, by utilizing this flow, the air A flowing out from the roadway 50 side to the sidewalk 51 side flows through the ventilation duct 10 where the pressure loss of each air purification filter unit 1 is small, and pollutants such as NOx contained in the air A come into good contact with the catalytic fiber sheet material 2 arranged in the ventilation duct 10 and are oxidized and removed, and further, the fine particles contained in the air A come into good contact with the separator 5 and are adsorbed and removed.

As shown in FIG. 5, the air purification fence structure 30 is arranged in the median strip at the boundary between the opposing lanes for the motorway 50 as the purification target area, and the flow of air A generated between the opposing lanes is utilized to circulate the air A through the ventilation passage 10 with small pressure loss of each air purification filter unit 1, and pollutants such as NOx contained in the air A come into good contact with the catalyst fiber sheet material 2 arranged in the ventilation passage 10 and are oxidized and removed, and fine particles contained in the air A come into good contact with the separator 5 and are adsorbed and removed. In addition, by arranging the air purification fence structure 30 in a form that covers the sky above the motorway 50 as the purification target area, the air A can be circulated through the ventilation passage 10 with small pressure loss of each air purification filter unit 1 by utilizing the flow of air A from the motorway 50 upward, and pollutants such as NOx contained in the air A can be oxidized and removed, and fine particles contained in the air A can be brought into good contact with the separator 5 and adsorbed and removed.

The air purifying fence structure 30 can simultaneously remove fine particulate matter (PM2.5, etc.) contained in exhaust gas, such as carbon black, elemental carbon, tire wear dust, and purify the NOx contained in exhaust gas, in areas along highways 50 near industrial areas, ports, cargo dumps, bus terminals, and other locations with high traffic and heavy congestion, as well as around thermal power plants and waste incinerators, where exhaust gas concentrations are high.
Therefore, no power consuming equipment such as a blower is required, and the device can be ventilated using only natural wind and the wind from traveling cars to purify the air A. In addition, the device can be installed like a fence at the edge of the road, and there is no need to modify the existing road structure or install space, making it easy to install. Furthermore, the activated carbon fiber used for purification does not need to be replaced for a long period of time because its performance can be restored by washing with water. The activated carbon fiber after washing can also be dried using the passing air A and exhaust gas.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[Example]
As the air purification filter unit 1 shown in FIG. 1, an air purification filter unit 1A having a catalytic purification unit 1A disposed in the ventilation passage 10 inside the main casing 20 was prepared.
Here, the catalytic purification unit 1A was made by laminating a catalyst fiber sheet material having a length*width*thickness of 50*20*0.4 (cm) and a separator 5 (number of pleats: 37) cut from an electrostatically charged nonwoven fabric (EF-R-25 manufactured by Toyobo Co., Ltd.) pleated to a predetermined height (8 mm in Example 1, 10 mm in Example 2) and further processed into a ribbon (ribbon width 5 mm, interval 12 mm) and cut to a length*width of 50*20 (cm). In Example 1, 50 sheets of the catalyst fiber sheet material 2 and 5 were used, and in Example 2, 45 sheets of the catalyst fiber sheet material 2 and 5 were used. The electrostatically charged nonwoven fabric used included a reinforcing net (basis weight 30 g/m ² ) and had a total basis weight of 70 g/m ² .

The obtained air purification filter unit 1 was measured for its fine particle (PM) removal performance using a small wind tunnel air purification performance test device. The air purification filter unit 1 was loaded into the test device at a location that would be a 50 cm x 50 cm cross section of the ventilation section, and the passing wind speed was adjusted to 0.05 to 0.25 m/s using a blower. PM was defined as fine particles contained in air A in the test room, and was measured for one minute each at the inlet and outlet of the air purification filter unit 1 using a particle counter (Shibata Scientific, GT-526S). The fine particle (PM) removal rate was calculated from the difference between the inlet and outlet for each particle size of PM (three types: 2.5 μm or more and 5.0 or less, 1.0 μm or more and less than 2.5 μm, and 0.3 μm or more and less than 1.0 μm).
The removal performance of the pollutant NOx of the obtained air purification filter unit 1 was measured using a small wind tunnel air purification performance test device in the same manner as above. _NO2 was used as NOx, and the flow rate was controlled from a gas cylinder with a concentration of 1%, and the _NO2 was introduced into the air A so that the concentration was about 1 ppm at the inlet of the air purification filter unit 1. The NO2 concentration was measured for 30 minutes each at the inlet and outlet of the air purification filter unit 1 using an automatic NOx measuring device (Anatec Yanaco, XCL-880US). The _NO2 removal rate was calculated from the concentration difference between the inlet and the outlet.

PM removal rate = (inlet concentration - outlet concentration) / inlet concentration * 100 (%)
_NO2 removal rate = (inlet concentration - outlet concentration) / inlet concentration * 100 (%)

Comparative Example
The catalytic purification unit 1A, measuring 50 x 50 x 20 cm in length x width x thickness, was placed in the ventilation passage 10 of the main casing 20 and loaded as it was into the small wind tunnel type air purification performance test device as the air purification filter unit 1, and the PM removal performance was measured in the same manner. Note that the separator of the catalytic purification unit 1A was a wire mesh formed into a corrugated shape with peaks of 8 mm in height.

As a result, as shown in Figures 6 to 8, in the air purification filter unit 1 according to Example 1 and Example 2, the PM removal rate was significantly improved in both cases. Specifically, the PM removal rate when the wind speed was 0.253 m/s was 58% in Example 1 and 55% in Example 2 in the measured particle size range of 2.5 μm or more and 5.0 μm or less, 34% in Example 1 and 20% in Example 2 in the measured particle size range of 1.0 μm or more and less than 2.5 μm, and 20% in Example 1 and 16% in Example 2 in the measured particle size range of 0.3 μm or more and less than 1.0 μm. In contrast, it was revealed that the PM removal performance of the air purification filter unit 1 according to the comparative example was very low, and in particular, fine particles of 0.3 μm or more and less than 1.0 μm were hardly removed and slipped through.
9, the _NO2 removal rate was also significantly improved in the air purifying filter units 1 according to Examples 1 and 2 compared to the air purifying filter unit 1 of the Comparative Example. Specifically, the _NO2 removal rate when the wind speed was 0.253 m/s was 59% in Example 1 and 58% in Example 2, while it was 24% in the Comparative Example.

[Another embodiment]
In the above embodiment, the air purifying fence structure 30 is intended to purify a roadway 50, but the area to be purified may be an industrial area densely populated with factories or a facility where many people gather, and the air purifying fence structure 30 may be provided around the periphery of the area to be purified with the air purifying filter units 1 arranged side by side. For example, for the purpose of removing fine particulate matter, which has been attracting attention in recent years, the air purifying fence structure 30 may be installed at train stations and bus stops to reduce the concentration of fine particulate matter in the vicinity of these areas.

The air purification filter unit 1 may not only be used as the air purification fence structure 30, but may also be attached to a ventilation opening, ventilation duct, etc. to purify pollutants and remove fine particles in the ventilated air. For example, it may be attached to the air intake of an air conditioning filter in a building to reduce the concentration of fine particulate matter in the air.

In the above embodiment, the separator 5 is made of electrically charged nonwoven fabric molded into pleats, but this is not limited to the above. The electrically charged nonwoven fabric may be molded into any shape as long as it does not impede the flow of air A within the ventilation space 10a and the contact of air A with the catalytic fiber sheet material 2, and may even be a corrugated shape that maintains the shape of the ventilation space 10a. The height and number of pleats may also be changed, and the number of catalytic fiber sheet materials and separators used may also be changed.

In addition, in the above embodiment, activated carbon fiber is used as the catalyst fiber sheet material, but this is not limited to this, and any material that can remove pollutants such as NOx from the air can be used.

The configurations disclosed in the above embodiment (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, so long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments. They can be modified as appropriate within the scope of the purpose of the present invention.

The air purification filter unit 1 of the present invention can be used as an air purification fence structure to separate a purification target area, such as a road, from its surroundings, and to purify pollutants and remove fine particles contained in the air that enters and leaves the purification target area.

1: Air purification filter unit 1A: Catalytic purification unit 2: Catalytic fiber sheet material 5: Separator 10: Ventilation passage 10a: Ventilation space 20: Main casing 21: Opening 21a of ventilation space: One end opening 21b: Other end opening 22: Air vent 30: Air purification fence structure 50: Automobile road A: Air

Claims (6)

a catalytic purification unit in which a plurality of catalyst fiber sheet materials are stacked and arranged in a state in which a ventilation space is formed along the surface of the catalyst fiber sheet materials between adjacent ones of the plurality of catalyst fiber sheet materials, and a separator made of a sheet-like electrostatically-charged nonwoven fabric is arranged in the ventilation space such that the surface direction is parallel to the ventilation direction in the ventilation space;
The separator is an air purifying filter unit that removes fine particles contained in the air flowing along the surface direction of the electrostatic nonwoven fabric. The air purification filter unit according to claim 1, wherein the catalyst fiber sheet material is activated carbon fiber. The air purification filter unit according to claim 1 or 2, wherein the separator is a sheet-like electrostatically charged nonwoven fabric molded into a pleated shape, and is disposed in the ventilation space so that the top of the pleated shape extends along the ventilation direction in the ventilation space. The device has a main casing having air vents on both sides thereof, the air vents being open to the outside air;
A ventilation passage is formed inside the main body casing, the ventilation passage communicating both of the air openings.
4. The air cleaning filter unit according to claim 1, wherein the catalytic purification unit is disposed in the ventilation passage with the air port communicating with an opening in the ventilation space. 1. An air purifying fence structure for removing contaminants contained in air entering and leaving a target area for purification, comprising:
5. An air purifying fence structure comprising a plurality of the air purifying filter units according to claim 4 stacked together so as to surround at least a portion of the periphery of the area to be purified, with the thickness direction being the air flow direction in the air passage. The air purification fence structure according to claim 5, in which the purification target area is a roadway and is stacked along the roadside.

Images