JP2777623B2 - Hazardous gas removal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing low-concentration harmful gases from environmental air.

[0002]

For the removal of the Related Art harmful gases such as NO _X and SO _X, various oxidation or reduction catalyst for treating an exhaust gas from automobiles and power plants have been developed.
However, they exhibit their performance at a high temperature of several hundred to 1000 ° C. for harmful gases having a high concentration of several hundred ppm, and have a high use cost and a low concentration of harmful gas of several ppm in environmental air. No consideration was given to gas removal.

Therefore, the present inventors have proposed titanium dioxide (T
Invented a photocatalyst comprising a mixture of iO ₂ ) and activated carbon and capable of efficiently removing ppm-level nitrogen oxides and the like in environmental air by light irradiation (Japanese Patent No. 1613301).
We have also developed a technology for applying this photocatalyst to tunnel exhaust treatment, and found that the addition of an iron-based metal oxide such as iron (III) oxide further increases the photocatalytic activity. Kaihei 3-233100 and others 3
Cases). This photocatalyst oxidizes low-concentration nitrogen oxides and the like in the air and captures them in the form of nitric acid.The performance of the photocatalyst gradually increases over time as the active part of the surface is mainly covered with oxidation products. Although reduced, the activity is easily restored by washing the photocatalyst with water to remove oxidation products.

[0004]

When a harmful gas removing device is constructed using the above-mentioned photocatalyst, the photocatalyst is carried on an appropriate member to guide air containing the harmful gas to the light source, and light is emitted from the light source. It is necessary to have a structure in which the photocatalyst and the harmful gas are brought into good contact with each other while irradiating, and the oxidation products adhered to the photocatalyst are periodically washed away with water. FIG. 16 shows an example of such a conventional structure, in which a photocatalyst 52 is carried on the inner wall surface of a cylindrical tube 51, and a light source 53 for irradiating light is disposed at the center of the cylindrical tube 51. Air containing a harmful gas is introduced from one end of the cylindrical tube 51, flows in contact with the photocatalyst 52 as shown by the arrow, and is discharged from the other end.

However, in this type of structure, the degree of agitation of air in the tube is small, so that the harmful gas in the outer layer close to the tube wall is in good contact with the photocatalyst, but the inner layer has a small contact ratio, and is therefore removed as a whole. There was a problem that the rate was low. If a baffle plate or the like is provided in the middle of the air passage, the degree of agitation is increased and the removal rate is improved, but on the other hand, a problem arises in that the washing mechanism for washing the catalyst surface with water becomes complicated. Therefore, the present invention provides a harmful gas removing device that enhances the degree of stirring without providing a special member such as a baffle plate, achieves good contact between the harmful gas and the photocatalyst, and simplifies washing of the photocatalyst with water. It is the purpose.

[0006]

According to the present invention, a photocatalyst is supported on the surface of a blade-like reaction plate made of a thin plate, and the reaction plates are arranged in a blind manner to achieve the above object. In that case, an appropriate number of reaction plates are integrated with a rectangular support frame to form a catalyst module, and if a harmful gas removing device is assembled in units of this module, the structure of the device becomes simpler and assembly becomes easier, By combining the modules in various directions, the stirring of the air can be further promoted, and the advantage that the capacity of the apparatus can be freely adjusted by increasing or decreasing the number of modules is obtained. Similarly, if an appropriate number of light sources are integrated with a rectangular support frame to form a light source module, a harmful gas removing device can be configured by simply stacking the light source module in combination with the catalyst module, and the structure of the device is further simplified. Become.

[0007] In this case, it is preferable to form a reaction unit by appropriately unitizing a number of modules to form a reaction unit, and then assembling a required number of reaction units. As a result, various conveniences can be obtained, for example, the layout in the apparatus and operation control can be performed in units. When the apparatus is configured by assembling a plurality of the reaction units, an openable / closable damper is provided at an air inlet / outlet of each reaction unit, and this damper is closed to wash the photocatalyst for each reaction unit.
For example, when ventilating a motorway tunnel, it becomes possible to partially advance the cleaning of the photocatalyst in units of units while continuing the operation of the blower.

In the harmful gas removing apparatus according to the present invention, power is mainly consumed by the light source and the blower. However, in order to save power while considering the quality of air after passing through the apparatus, the harmful gas concentration and the apparatus must be reduced. Consideration must be given to the relationship with the operating conditions of the equipment.To achieve this, a gas sensor that measures the concentration of harmful gas at the inlet or outlet of the air in the device, and the mounting angle of the reaction plate and lighting of the light source based on the measurement results of this gas sensor Means for increasing or decreasing the number or the amount of light may be provided. Although the removal rate of the harmful gas is better as the mounting angle of the reaction plate with respect to the ventilation direction is larger, the power consumption of the blower for obtaining a constant processing air volume increases because the pressure loss increases. In addition, the reaction unit is divided into a plurality of processing systems and installed, and a gas sensor for measuring a harmful gas concentration at an inlet or an outlet of air, and the operation of the reaction unit is controlled for each processing system based on the measurement result of the gas sensor. It is also possible to increase the efficiency of the operation and save power by providing the means for performing the operation.

[0009]

[Function] A photocatalyst is supported on the surface of a blade-shaped reaction plate made of a thin plate, and the reaction plates are arranged in a blind manner and air is allowed to flow. Therefore, the contact between the harmful gas and the photocatalyst is performed evenly without providing a baffle plate or the like.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Note that the same reference numerals are used for parts corresponding to each other in each embodiment. FIG. 1 is a perspective view showing the catalyst module 1. An appropriate number (six in the illustrated case) of blade-like reaction plates 2 carrying a photocatalyst on both surfaces are arranged in a blind manner at an appropriate angle, and both ends thereof are supported by a rectangular support frame 3 to be integrated. , Catalyst module 1
Is composed. The air containing the harmful gas flows through the inside of the support frame 2 as shown by the arrow, and comes into contact with the reaction plate 2. As shown in the figure, the number of the reaction plates 2 is appropriately grouped into a module to form a module, and as will be described later, the harmful gas removing device is configured as a unit to facilitate assembly of the device.

The reaction plate 2 is formed by applying an adhesive to the surface of a rectangular thin plate made of plastic, aluminum, iron, or the like, and then applying a photocatalyst powder (a mixed powder of TiO ₂ powder and activated carbon powder or an oxidized powder thereof). (Mixed powder to which iron powder is added). The support frame 3 is formed by bending from an iron plate or the like, and its size is preferably 1 to 2 m in length and width and 10 to 20 cm in depth (thickness). The mounting angle of the reaction plate 2 is determined in consideration of the contact property of the harmful gas and the pressure loss, and is preferably 30 to 45 degrees with respect to the horizontal. However, when the mounting angle is adjusted according to the gas concentration as described later, the reaction plate 2 is configured to be rotatable around the support shaft.

FIG. 2 shows a reaction unit 4 which is made into a unit by using an appropriate number of the catalyst modules 1.
That is, 5 to 6 catalyst modules 1 are inserted into a duct 5 having a rectangular cross section with a space 6 therebetween, and a mercury lamp that irradiates the ceiling plate and the floor surface of the space 6 with light having a wavelength of 400 nm or less toward the reaction plate 2. A light source 7 is arranged, and a washing nozzle 8 for ejecting washing water to the reaction plate 2 is arranged on the ceiling surface to form a unit. The harmful gas removing device is configured by appropriately grouping the number of the reaction units 4 up, down, left, and right according to the ventilation area, but such a unit configuration can be freely constructed by increasing or decreasing the number of the reaction units 4 to any size. Further, as described later, there is an advantage that the cleaning operation of the photocatalyst can be performed in units.

The air flowing through the reaction unit 4 in the direction of the arrow is changed and stirred by the reaction plate 2 each time it passes through each catalyst module 1, and the harmful gas in the air uniformly contacts the photocatalyst. In the illustrated case, the reaction plates 2 of each catalyst module 1 are oriented in the same direction. Although the reaction plate 2 is horizontal in the illustrated example, the reaction plate 2 may be vertical by rotating the catalyst module 1 by 90 degrees.

FIG. 3 shows the light source module 9. An appropriate number (three in the illustrated case) of light sources 7 such as black lights arranged in parallel are supported at both ends by a rectangular support frame 10 formed by bending a steel plate or the like having the same dimensions as the support frame 3 of the catalyst module 1. And integrated. FIG. 4 shows a reaction unit 4 formed by using the catalyst modules 1 and the light source modules 9 in appropriate numbers. Catalyst module 1 and light source module 9 in duct 5
Are alternately stacked with a space 6 therebetween, and a washing nozzle 8 for ejecting washing water toward the reaction plate 2 and the light source 7 on the ceiling surface.
Are arranged into a unit. In this case, since the light source 7 is also modularized, it is easier to assemble the unit than in the case of FIG. 2, and since the light is emitted not from the duct wall surface but from the ventilation space, the catalyst surface can be more uniformly irradiated. Although the light source 7 is parallel to the reaction plate 2 in the figure, it is also possible to rotate the light source module 9 by 90 degrees and make them orthogonal.

FIG. 5 shows a light source module 9 with a reflection mirror 11.
Is provided. Of the light from the upper and lower light sources 7 in the light source module 9, those going to the ceiling surface and the bottom surface of the support frame 10 are wasted. Therefore, a reflection mirror 11 is provided between the support frame 10 and the light source 7 so that the wasted light is directed forward and backward (left and right in the figure) to the photocatalyst. The illustrated reflection mirror 11 is formed along a part of the arc of the ellipse indicated by the broken line, and the light source 7 is located near one of the focal points of the ellipse, and the long axis of the ellipse is turned upward or downward to turn the light source 7 upward or downward. It reflects downward light horizontally. Effective use of light by reflection is also possible by making the inner wall surfaces of the support frame 10 and the duct 5 (FIG. 4) mirror surfaces.

FIG. 6 shows a case where the catalyst modules 1 in FIG. 4 are alternately inverted and the reaction plates 2 are alternately turned in the opposite direction. As a result, as described above, the degree of stirring of the air passing through the reaction unit 4 is further increased, and the contact of the unreacted harmful gas with the photocatalyst is further promoted. Further, in this example, in addition to the washing nozzle 8 on the duct ceiling, washing nozzles 12 are provided in a vertically arranged manner on a pipe standing along the opposing surface between the catalyst module 1 and the light source module 9 to enhance the washing effect. ing.

FIG. 7 shows a large catalyst module 13 constituted by connecting two catalyst modules 1 horizontally and four vertically. In the figure, the directions of the reaction plates 2 of the adjacent unit catalyst modules 1 are different from each other horizontally and vertically and combined. By changing the direction of the reaction plate 2 not only in the flow direction of the air but also in the same plane, the air can be better agitated. FIG. 8 shows a large light source module 14 formed by connecting eight light source modules 9 like the large catalyst module 13. Although the light sources 7 are all oriented in the same direction in the figure, they may be combined in different directions as in FIG.

FIG. 9 shows the large catalyst module 13 described above.
FIG. 3 is a plan view showing a layout of a harmful gas removing device configured by assembling a light source module 14 and a light source module 14. A large number of large catalyst modules 13 and four large light source modules 14 each connected in a horizontal C-shape are laminated in the air flow direction indicated by an arrow with a space 6 therebetween. Each of the large modules 13 and 14 is provided with a ventilation path 15 including a bypass road of a motorway tunnel and a flue of an underground parking lot.
Then, it is suspended from the ceiling, for example, in a curtain wall system. The cross-sectional area of the ventilation passage 15 that is often excavated in the ground is limited, and the point of removing harmful gases is how to increase the catalyst area in a limited space. By arranging the large catalyst modules 13 in a C-shape as shown in the figure, it is possible to increase the catalyst area with respect to the same ventilation area as compared to simply crossing the ventilation path at right angles. The washing nozzle 8 installed on the ceiling surface of the space 6 is also arranged along the C-shaped surface.

By the way, the ventilation tower of the motorway tunnel continuously discharges the contaminated air in the tunnel to the outside of the tunnel, and the stop of the blower is not allowed. Therefore, when carrying out the catalyst cleaning of the harmful gas removing device installed in combination with such a ventilation tower, it is necessary to close the ventilation holes before and after the device. By the way, if the cleaning is performed in the open state, the cleaning water is blown off by the wind and does not reach the photocatalyst sufficiently, and the cleaning sewage is scattered to pollute the periphery of the apparatus.

FIG. 10 shows a reaction unit 4 in which damper doors are provided before and after the unit body in consideration of this point. A damper door 16 is attached via hinges 17 to the front and rear ventilation openings 4a of the unit body in which the catalyst modules 1 and the light source modules 9 are alternately stacked.
The damper door 16 has a structure in which a plurality of blade-shaped dampers 19 are rotatably supported by a vertical support shaft (not shown) on a support frame 18 having the same shape as that of the modules 1 and 9, and a water washing for washing the photocatalyst inside. Many nozzles 8 are arranged. In this embodiment, no washing nozzle is provided in the unit body,
The front and rear washing nozzles 8 cover all washing.

During the cleaning operation, the front and rear damper doors 16 are closed, and the damper 19 is rotated 90 degrees from the state shown to close the ventilation port 4a. The cleaning of the apparatus constituted by assembling a plurality of the reaction units 4 is sequentially performed in units of the reaction units 4. Thus, the harmful gas can be continuously removed while partially cleaning the apparatus. FIG. 11 shows a reaction unit 4 in which catalyst cleaning is performed by immersion instead of jetting of cleaning water. This is a device in which the damper door 16 is closed and the unit body sealed is filled with washing water from the water injection pipe 20, and the photocatalyst is immersed in water for washing. During the washing, the washing water overflows from a certain level. It is discharged from the drain 21.

FIG. 12 conceptually shows an example in which the harmful gas removing device 22 in which the reaction units 4 of FIG. 10 or FIG. 11 are assembled is installed in a ventilation path 15 connecting a motorway tunnel 23 and a ventilation tower (not shown). It is shown. The harmful gas is removed from the contaminated air extracted from the motorway tunnel 23 as indicated by the black arrow, and discharged from the ventilation tower outside the mine as indicated by the white arrow.

The photocatalyst is periodically washed to recover the catalytic activity, and the water in the washing water tank 24 is pressurized by the washing pump 25 and sent to the harmful gas removing device 22. The washing is sequentially performed in units of the reaction units 4 as described above, and the other reaction units 4 are operated while any one of them is being washed. The waste water after washing is once stored in a sewage tank 26 and then sent to a neutralization tank 28 by a drain pump 27 with a filter. Since the wastewater from which the oxidation products on the photocatalyst have been washed away contains nitric acid and the like, the wastewater is discharged after neutralization by adding a neutralizing agent in the neutralization tank. When the cleaning is completed, the damper door 16 (FIGS. 10 and 11)
Then, the damper 19 is opened and air is blown to wash the next reaction unit 4. Since the contaminated air of the motorway tunnel contains tar content, it is preferable to add an oil film remover, for example, a polysoap such as sodium alkylbenzene sulfonate, to the washing water.

FIG. 13 shows a gas sensor 29 for measuring the concentration of harmful gas at the inlet or outlet of the air of the harmful gas removing device 22.
Is a block diagram conceptually showing a configuration for controlling the reaction plate 2 or the light source 7 based on the measurement result. In this case, as shown in FIG. 14, the reaction plate 2 of each catalyst module 1 is attached to a rotating shaft 30, and the rotating shaft 30 linked to each module by a chain 31 is connected to a pulse motor 3.
2 so that the mounting angle θ of the reaction plate 2 (FIG. 13) can be arbitrarily adjusted within a range of 0 to 90 degrees. When θ = 0, that is, when the reaction plate 2 is parallel to the ventilation direction shown by the arrow in FIG.
The pressure loss increases as θ approaches 90 degrees,
The removal rate of the harmful gas is smallest when θ = 0 from the positional relationship with the light source 7, and increases as θ approaches 90 degrees.

In FIG. 13, a necessary pulse signal is supplied from the control unit 33 to the drive circuit 34 based on the harmful gas concentration measured by the gas sensor 29, so that the mounting angle θ of the reaction plate 2 is appropriately increased or decreased. That is, when the measurement gas concentration is high, the mounting angle θ is increased to increase the removal rate. that time,
If it is necessary to secure a constant processing air volume,
5 to increase the flow rate of the blower 36 to prevent a decrease in wind speed due to an increase in pressure loss. On the other hand, when the measured gas concentration is low, the removal angle is reduced to a necessary minimum by reducing the mounting angle θ, and the flow rate of the blower 36 is reduced by the reduced pressure loss to reduce the blowing power. In addition to the control described above,
The removal rate can be increased by increasing the mounting angle θ while the flow rate of the blower 36 remains unchanged, or the processing air volume can be increased by decreasing the installation angle θ to suppress fluctuations in power consumption.

In FIG. 13, the lighting of the light source 7 can be controlled based on the gas concentration measured by the gas sensor 29 as shown. That is, when the gas concentration is low, it is not necessary to turn on all the light sources 7. The control unit 33 instructs the lighting circuit 37 to turn on the light sources 7 of some of the light source modules 9, and turns off others (black). Display) to save power. In that case, the reaction plate 2 out of the light
Is horizontal as shown to avoid unnecessary pressure loss. Instead of turning off the light source 7, it is also possible to control the voltage to increase or decrease the amount of light.

When the target space for removing harmful gas is large, such as in a motorway tunnel or a large-scale underground parking lot, the treatment system for harmful gas is divided into a plurality of treatment systems, and a treatment system that operates according to the concentration of harmful gas is provided. The decision is more effective from the viewpoint of power saving. FIG. 15 shows such a configuration. The ventilation passage 15 for discharging contaminated air from the motorway tunnel 23 is divided into two ventilation passages 15A and 15B.
A, 15B required number of reaction units 4 and blowers 36
And one gas sensor 29 at the air inlet.
Are provided in common, and the air outlet is provided with a gas sensor 29 for each of the ventilation paths 15A and 15B. In addition, each ventilation path 15
The reaction units 4 provided in A and 15B are divided into two groups, a former stage and a latter stage. In such a configuration,
When the measured gas concentration is low or the required processing air volume is small, the reaction unit 4 and the blower 36 may be operated only in one system, for example, only in the ventilation path 15A. Further, it is possible to determine which of the reaction units 4 of each system is the former stage or the latter stage, and which one of them is to be operated, and to control the mounting angle of the reaction plate 2 and the light amount of the light source 7 already described above. It is also possible to add.

[0028]

As described above, according to the present invention, the photocatalyst is supported on the surface of the blade-like reaction plate made of a thin plate,
By arranging the reaction plates in a blind format and letting air flow through, the agitation of air is improved without the need for baffles, etc., and the removal rate of harmful gases is increased. A device can be obtained. Also,
In this case, if the reaction plate and the light source are modularized and laminated, the structure becomes simpler, and various advantages are obtained such that the orientation of each module can be appropriately changed to improve the degree of stirring of air.

[Brief description of the drawings]

FIG. 1 is a perspective view of a catalyst module showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a reaction unit using the catalyst module of FIG.

FIG. 3 is a perspective view of a light source module showing an embodiment of the present invention.

4 is a longitudinal sectional view of a reaction unit in which the catalyst module of FIG. 1 and the light source module of FIG. 3 are stacked.

FIG. 5 is a longitudinal sectional view showing a configuration in which a reflection mirror is provided in the light source module of FIG. 3;

FIG. 6 is a longitudinal sectional view of a reaction unit in which a catalyst module is alternately inverted.

FIG. 7 is a front view showing a large catalyst module to which the catalyst modules of FIG. 1 are connected.

FIG. 8 is a front view showing a large light source module to which the light source modules of FIG. 3 are connected.

9 is a plan view showing a layout of a harmful gas removing apparatus in which the large catalyst module of FIG. 7 and the large light source module of FIG. 8 are stacked.

FIG. 10 is a perspective view of a reaction unit provided with dampers at an inlet and an outlet of air.

11 is a perspective view showing a configuration in which the photocatalyst of the reaction unit in FIG. 10 is immersed in cleaning water for cleaning.

FIG. 12 is a side view showing a configuration in which the harmful gas removing device of the present invention is applied to an automobile road tunnel.

FIG. 13 is a block diagram showing a configuration for controlling a harmful gas removing device based on a harmful gas concentration measured by a gas sensor.

FIG. 14 is a front view of the catalyst module in FIG.

FIG. 15 is a layout diagram showing a configuration of a harmful gas removing apparatus in which a reaction unit is installed in a plurality of processing systems.

FIG. 16 is a longitudinal sectional view of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Catalyst module 2 Reaction plate 3 Support frame 4 Reaction unit 7 Light source 8 Rinse nozzle 9 Light source module 10 Support frame 11 Reflection mirror 12 Rinse nozzle 15 Ventilation path 16 Damper door 19 Damper 22 Harmful gas removal device 23 Tunnel for motorway 24 Rinse tank 25 Cleaning water pump 26 Sewage tank 27 Drainage pump 28 Neutralization tank 29 Gas sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B01J 35/02 ZAB B01D 53/36 J 102D (72) Inventor Takeo Takahashi 1-1-1, Tanabe Shinda, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Inside Electric Co., Ltd. (72) Inventor Kazushi Shingai 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Masahiro Miyamoto 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Inside Fuji Electric Co., Ltd. (72) Inventor Satoshi Nishikata 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. Examiner at Fuji Electric Co., Ltd. Yoshihisa Seki (56) References JP-A-1-143630 (JP, A) JP-A-5-237381 (JP, A) JP-A-56-89836 (JP, A) Hei 4-117643 (JP, U) JP 58-13215 (JP, B2) JP 63-21536 (JP, B2) JP 2-62297 (JP, B2) (58) Fields surveyed (Int .Cl. ⁶ , DB name) B01D 53/94 B01D 53/86 B01J 21/06 B01J 21/18 B01J 35/02

Claims (7)

(57) [Claims] An air containing a harmful gas is brought into contact with a photocatalyst containing a mixture of titanium dioxide and activated carbon as a main component while irradiating light having a wavelength of 400 nm or less, and the harmful gas in the air is captured on the photocatalyst. In the harmful gas removing device for removing, a photocatalyst is supported on the surface of a blade-like reaction plate made of a thin plate, and an appropriate number of the reaction plates are arranged in a blind form .
At the same time, these reaction plates are integrated with a rectangular support frame
A harmful gas removing device comprising a catalyst module . 2. The light source module according to claim 1, wherein an appropriate number of light sources are integrated by a rectangular support frame.
The harmful gas removing device according to the above. 3. A suitably number laminating the above catalyst module and the light source module forms Then together the reaction unit
The harmful gas removing apparatus according to claim 2 , wherein a plurality of the reaction units are assembled . Wherein provided freely damper opening and closing the air inlet and outlet of the reaction unit, the harmful gas removing apparatus according to claim 3, characterized in that so as to wash the photocatalyst for each of the reaction unit by closing the damper . 5. A gas sensor for measuring the harmful gas concentration at the inlet or outlet of air, according to claim 1, characterized in that a means for increasing or decreasing the attachment angle of the reaction plate on the basis of the measurement results of the gas sensor The harmful gas removing device according to any one of claims 1 to 4 . 6. A gas sensor for measuring the entrance or harmful gas concentration at the outlet of air, claims, characterized in that a means for increasing or decreasing the number of lit or quantity of the light source based on the measurement result of the gas sensor The harmful gas removing device according to any one of claims 1 to 5 . With 7. installed separately above reaction unit to a plurality of processing systems, a gas sensor for measuring the harmful gas concentration at the inlet or outlet of air, the reaction unit by the processing system on the basis of the measurement results of the gas sensor The harmful gas removing device according to any one of claims 3 to 6 , further comprising means for controlling the operation of the harmful gas.