JP7043172B2 - Irradiation device - Google Patents

Description

The present invention relates to an irradiation device for irradiating a fluid with ultraviolet light.

It is known that ultraviolet light has a sterilizing ability, and a device that irradiates ultraviolet light is used for sterilizing treatment in medical and food processing sites. Further, a device for continuously sterilizing a fluid such as water by irradiating it with ultraviolet light is also used. Examples of such a device include a device in which an ultraviolet LED is arranged on the inner wall of a pipe end of a flow path formed of a straight tubular metal pipe (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-16074

In order to irradiate the fluid flowing in the flow path with ultraviolet light with high efficiency, it is desirable to have a structure having a high ultraviolet light reflectance on the inner wall surface of the flow path. However, bubbles may be generated or disappeared on the inner wall surface of the flow path depending on the state of the fluid. When bubbles are generated, the ultraviolet light is scattered by the bubbles on the inner wall surface of the flow path, and the intensity distribution of the ultraviolet light in the flow path changes with the passage of time. Then, the amount of ultraviolet light acting on the fluid varies, and the bactericidal effect and the organic substance decomposition effect due to the ultraviolet light irradiation also vary.

The present invention has been made in view of these problems, and one of its exemplary purposes is to provide an irradiation device that reduces variation in irradiation amount while increasing the irradiation efficiency of ultraviolet light.

The irradiation device of one embodiment of the present invention has a flow path structure in which at least a part of the inner wall surface of the flow path is made of a fluororesin material having an arithmetic mean roughness of 2 μm or less, and ultraviolet light toward the inside of the flow path structure. It is equipped with a light source that irradiates the light source.

According to this aspect, by using a fluororesin material for the inner wall surface of the flow path, the flow path structure has high durability against ultraviolet light, and the reflectance of ultraviolet light on the inner wall surface of the flow path is increased to be efficient for fluids. Can be irradiated with ultraviolet light. Further, by setting the surface roughness of the fluororesin material to 2 μm or less, it is possible to prevent bubbles from adhering to the inner wall surface of the flow path and reduce the time change of the illuminance distribution of the ultraviolet light in the flow path. As a result, it is possible to suppress variations in the amount of ultraviolet light acting on the fluid and stabilize the irradiation performance of the irradiation device.

The fluororesin material may be polytetrafluoroethylene (PTFE).

The flow path structure may include a straight pipe made of a fluororesin material. The light source may be arranged to irradiate the inside of the straight tube with ultraviolet light in the axial direction of the straight tube.

The light source may output ultraviolet light having a wavelength of 250 nm to 300 nm.

According to the present invention, it is possible to reduce the variation in the irradiation amount while increasing the irradiation efficiency of ultraviolet light in the flow path.

It is sectional drawing which shows schematic the structure of the irradiation apparatus which concerns on embodiment. It is a graph which shows typically the illuminance distribution in the flow path which concerns on a comparative example. It is a graph which shows typically the illuminance distribution in the flow path which concerns on an Example. It is a figure which shows typically the structure of the purification apparatus which concerns on embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are designated by the same reference numerals, and duplicate description will be omitted as appropriate.

FIG. 1 is a cross-sectional view schematically showing the configuration of the irradiation device 10 according to the embodiment. The irradiation device 10 includes a flow path structure 12 and a light source 14. The flow path structure 12 includes a straight pipe 20, an inflow pipe 26, an outflow pipe 28, an irradiation window 30, and an end wall 32. The irradiation device 10 is used to irradiate a fluid such as water flowing inside the straight tube 20 with ultraviolet light to perform a sterilization treatment or a purification treatment.

The light source 14 is configured to irradiate the inside of the flow path structure 12 with ultraviolet light. The light source 14 is arranged at the first end portion 22 of the straight tube 20, and irradiates ultraviolet light in the axial direction of the straight tube 20 toward the inside of the straight tube 20 through the irradiation window 30. The light source 14 includes, for example, an LED (Light Emitting Diode) that emits ultraviolet light, and outputs ultraviolet light in the vicinity of 250 nm to 300 nm, which is a wavelength having high sterilization efficiency. When the irradiation target is water, the light source 14 is preferably configured to output ultraviolet light of 265 nm to 285 nm, and outputs, for example, ultraviolet light of 270 nm, 275 nm, or 280 nm. The light source 14 may include an optical element such as a lens or a reflector for adjusting the irradiation direction of the ultraviolet light output from the ultraviolet light LED.

The straight pipe 20 extends axially from the first end 22 to the second end 24. The straight tube 20 is made of a fluororesin material, for example, polytetrafluoroethylene (PTFE) which is a total fluorinated resin. PTFE is a chemically stable material, excellent in durability, heat resistance and chemical resistance, and has a high reflectance of ultraviolet light. By forming the straight tube 20 with a fluororesin material such as PTFE, the ultraviolet light from the light source 14 can be reflected by the inner wall surface 18 and the ultraviolet light can be efficiently propagated in the axial direction of the straight tube 20.

The straight pipe 20 does not have to be entirely made of PTFE, and the inner wall surface 18 in contact with the fluid may be made of PTFE. For example, a PTFE liner may be attached to the inner surface of a pipe made of another resin material or metal material to form a straight pipe 20.

The first end 22 of the straight tube 20 is provided with an irradiation window 30 for transmitting ultraviolet light from the light source 14. The irradiation window 30 is made of a member having a high transmittance of ultraviolet light such as quartz (SiO ₂ ), sapphire (Al ₂ O ₃ ), and an amorphous fluororesin. An end wall 32 is provided at the second end 24 of the straight pipe 20. The end wall 32 is made of a fluororesin material such as PTFE, like the straight pipe 20. The end wall 32 does not have to be entirely composed of PTFE, and at least the inner surface 34 of the end wall 32 may be composed of PTFE.

The inflow pipe 26 is provided near the first end portion 22 of the straight pipe 20, and extends in the radial direction orthogonal to the axial direction of the straight pipe 20. The outflow pipe 28 is provided near the second end portion 24 of the straight pipe 20, and extends in the radial direction of the straight pipe 20. Therefore, in the irradiation device 10, the fluid flows in from a position close to the light source 14, flows inside the straight tube 20 in a direction away from the light source 14, and then is discharged. The inflow pipe 26 may be configured to be on the outflow side, and the outflow pipe 28 may be configured to be on the inflow side.

In the present embodiment, the arithmetic average roughness Ra of the inner wall surface 18 of the straight pipe 20 is configured to be 2 μm or less. In order to reduce the surface roughness Ra of the inner wall surface 18 to 2 μm or less, for example, the inner wall surface 18 may be machined to remove minute irregularities on the inner wall surface 18. In addition, the surface roughness Ra of the inner wall surface 18 can be reduced to 2 μm or less by using a mold in which the surface forming the inner wall surface 18 is mirror-finished as the mold for forming the straight pipe 20.

The fluororesin material constituting the inner wall surface 18 of the straight pipe 20 exhibits superhydrophobicity due to its high surface energy. Therefore, if fine irregularities are present on the inner wall surface 18, bubbles are likely to adhere to the irregularities, and once the bubbles are formed, they are difficult to remove. According to the findings of the present inventors, it is known that when the arithmetic mean roughness Ra of the PTFE surface exceeds 2 μm, bubbles adhere to the surface, and when Ra exceeds 9 μm, a large number of bubbles adhere. ..

When bubbles adhere to the inner wall surface 18 of the straight tube 20, reflection or scattering occurs on the surface of the bubbles due to the difference in refractive index between the fluid and the bubbles, which affects the ultraviolet light illuminance distribution inside the straight tube 20. Since the location where bubbles are generated is not always constant, the illuminance distribution in the flow path changes depending on the number and location of bubbles generated, and the amount of ultraviolet light irradiated to the fluid varies. In addition, diffuse reflection is predominant on the surface of the fluororesin material, and incident ultraviolet light is scattered in various directions, whereas specular reflection is predominant on the bubble surface, and incident ultraviolet light is specified. It is easily reflected strongly in the direction of. As a result, when bubbles are generated, the illuminance distribution in the flow path tends to be non-uniform. In the present embodiment, the arithmetic average roughness Ra of the inner wall surface 18 is set to 2 μm or less in order to reduce the variation in the irradiation amount due to the generation of bubbles.

FIG. 2 is a graph schematically showing the illuminance distribution in the flow path according to the comparative example, and shows the time change of the illuminance distribution in the radial direction in the flow path. In this comparative example, a PTFE tube having an inner diameter of 40 mm and an arithmetic mean roughness Ra of the inner wall surface of the flow path of 4 μm was used, and the illuminance distribution was measured at a position 150 mm away from the light source. The inside of the PTFE tube is filled with pure water. FIG. 2 shows a graph of the illuminance distribution measured at a plurality of timings, and standardizes the intensity value when the light intensity is maximum as 1. As shown in the figure, when the surface roughness of the inner wall surface of the flow path is large, the light intensity varies, and it can be seen that the intensity changes by about 30% at the maximum.

FIG. 3 is a graph schematically showing the illuminance distribution in the flow path according to the embodiment, and shows the time change of the illuminance distribution when using PTFE having an arithmetic mean roughness Ra of 1.8 μm on the inner wall surface of the flow path. Shows. Also in this embodiment, a PTFE tube having an inner diameter of 40 mm was used, and the illuminance distribution was measured at a position 150 mm away from the light source with the inside of the PTFE tube filled with pure water. FIG. 3 also shows a graph of the illuminance distribution measured at a plurality of timings, and standardizes the intensity value when the light intensity is maximum as 1. In this embodiment, since the surface roughness of the inner wall surface of the flow path is small, the variation in light intensity is small, and the intensity change is only about 5% at the maximum. In this way, by setting the surface roughness to 2 μm or less, it is possible to reduce the time change of the illuminance distribution in the flow path and reduce the variation in the irradiation amount.

FIG. 4 is a diagram schematically showing the configuration of the purification device 70 according to the embodiment, and shows an application example of the above-mentioned irradiation device 10. The purification device 70 includes an irradiation device 10 and a processing device 60. The purification device 70 is a purification system for performing a two-step purification treatment, and after the pretreatment is performed by the treatment device 60, the post-treatment is performed by the irradiation device 10.

The processing device 60 includes a processing tank 62 and an aeration device 64. The treatment device 60 is a device for purifying treatment using microorganisms. Inside the treatment tank 62, a contact material to which aerobic microorganisms adhere is provided. The aeration device 64 supplies air to the fluid inside the treatment tank 62 so that the fluid supplied from the inflow path 71 is purified by the action of aerobic microorganisms. The fluid treated in the treatment tank 62 is supplied to the irradiation device 10 through the connecting path 72 after the solid matter is removed.

The irradiation device 10 irradiates the fluid supplied from the processing device 60 through the connection path 72 with ultraviolet light to purify the fluid, and discharges the treated fluid from the outflow path 73. Since air is supplied through the aeration device 64 in the processing device 60, the fluid supplied through the connecting path 72 has a relatively high amount of dissolved air, and bubbles are likely to be generated. However, in the irradiation device 10, since the surface roughness of the inner wall surface of the flow path is set to 2 μm or less, bubbles adhere to the inner wall surface of the flow path even when a fluid having a high amount of dissolved air is supplied. Can be suitably suppressed. As a result, the irradiation device 10 can irradiate ultraviolet light with high efficiency and suppress the occurrence of irradiation unevenness due to bubbles. Therefore, according to the present embodiment, the processing capacity of the purification device 70 can be stabilized.

The present invention has been described above based on the embodiments. It is understood by those skilled in the art that the present invention is not limited to the above embodiment, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present invention. It is about to be.

In the above-described embodiment, the case where a straight pipe-shaped flow path structure is used is shown, but the shape of the flow path structure is not particularly limited. In the modified example, the entire flow path is not formed in a linear shape, and a bent portion may be provided in at least a part of the flow path. Further, the cross-sectional shape of the flow path may be circular or polygonal.

In the above-described embodiment, a case where a fluororesin material is used for the entire inner wall surface of the flow path is shown. In the modified example, a fluororesin material may be used for a part of the inner wall surface of the flow path. By setting the surface roughness Ra of the fluorine-based resin material used for a part of the wall surface of the flow path to 2 μm or less, the adhesion of bubbles on the surface of the fluorine-based resin is suppressed, and the reflection of ultraviolet light on the surface of the fluorine-based resin. The characteristics can be stabilized.

In the above-described embodiment, a case where an ultraviolet LED is used as the light source 14 is shown. In the modified example, an ultraviolet lamp may be used as a light source, or an ultraviolet lamp having a center wavelength or a peak wavelength of 250 nm to 260 nm, for example, 254 nm may be used.

10 ... Irradiation device, 12 ... Channel structure, 14 ... Light source, 18 ... Inner wall surface, 20 ... Straight pipe.

Claims (4)

A flow path structure in which at least a part of the inner wall surface of the flow path is made of polytetrafluoroethylene (PTFE) having an arithmetic mean roughness of 2 μm or less.
An irradiation device including a light source that irradiates ultraviolet light toward water flowing inside the flow path structure. The irradiation device according to claim 1, wherein at least a part of the inner wall surface of the flow path made of PTFE is formed by cutting. The flow path structure includes a straight pipe composed of the PTFE.
The irradiation device according to claim 1 or 2, wherein the light source is arranged so as to irradiate ultraviolet light in the axial direction of the straight tube toward water flowing inside the straight tube. The irradiation device according to any one of claims 1 to 3, wherein the light source outputs ultraviolet light having a wavelength of 250 nm to 300 nm.

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