Patent Application
20150284266
The present invention relates to a novel ultraviolet disinfection apparatus and a disinfection method.
It is known that deep ultraviolet rays having a wavelength of 200 nm to 350 nm has a disinfection effect. An ultraviolet disinfection apparatus performing disinfection by irradiating such a deep ultraviolet rays is actually used. A typical light source used in the ultraviolet disinfection apparatus is a low pressure mercury lamp (so-called, disinfection lamp) radiating a light having a wavelength of 253.7 nm (mercury resonance line) generated by discharge of low pressure (about 0.1 Pa) mercury steam. The disinfection lamp is widely used for disinfection of water, powder and a container in a cooking room, a hospital or a pharmaceutical factory.
In recent years, an ultraviolet disinfection apparatus using modularized deep ultraviolet light-emitting diodes (hereinafter referred to as “deep ultraviolet LEDs”) as a light source has been developed having a longer life and lower consumed power than the mercury lamp.
When fluid such as water is disinfected using an ultraviolet disinfection apparatus using such deep ultraviolet LEDs, the deep ultraviolet rays are generally irradiated while the fluid to be treated flows in terms of efficiency.
Specifically, as an apparatus where deep violet rays are irradiated while a light source is arranged in fluid to be disinfected, there is known an apparatus including an LED module arranging a plurality of deep ultraviolet LEDs on a surface inside of a treatment tank including an inlet part and an outlet part of an object to be treated and combining a rear surface of a first heat exchanger plate and a rear surface of a second exchanger plate, the respective exchange plates including a protection cover water-tightly covering the deep ultraviolet LEDs, in a state that a deep ultraviolet LED of the first heat exchanger plate is not overlapped back-to-back with a deep ultraviolet LED of the second heat exchanger plate (see Patent Document 1). As an apparatus where deep violet rays are irradiated while a light source is arranged outside of an object to be disinfected, there is known an apparatus including a light source arranged at a position sandwiched by a flow path made of bent quartz glass and cooled by the object to be disinfected flowing through the flow path (see Patent Document 2).
Patent Document 1: Japanese Patent Application Laid-open No. 2012-115715
Patent Document 2: Japanese Patent Application Laid-open No. 2010-194414
However, as the intensity of the deep ultraviolet rays radiated from the deep ultraviolet LEDs is significantly lower than the intensity of the deep ultraviolet rays radiated from the disinfection lamp, in order to perform sufficient disinfection, a number of deep ultraviolet LEDs should be arranged in line to prolong an irradiation time per unit amount of the object to be disinfected. There is a limitation to perform disinfection efficiently on a relatively large amount of the objects to be disinfected. For example, in the apparatuses described in Patent Documents 1 and 2, the deep ultraviolet LEDs are arranged planarly in the module used as the light source. In order to provide a required irradiation amount, each module itself has a large area. In addition, the number of the modules disposed within the treatment tank should be increased in the apparatus described in Patent Document 1 and a flow path length should be longer in Patent Document 2.
The present invention solves the above-described problems by arranging deep ultraviolet LEDs for utilizing an inner space in a module as a light source more effectively and by combining with a light condenser that effectively condenses the deep ultraviolet rays emitted from the light source.
Specifically, a present invention is an ultraviolet disinfection apparatus characterized by including:
a flow path surrounded by a material having a transmitting property to ultraviolet rays having a disinfection action through which a fluid object to be disinfected passes;
a light source disposed externally to the flow path for emitting ultraviolet rays having a disinfection action,
a light condenser for condensing the ultraviolet rays emitted from the ultraviolet light-emitting devices,
In the apparatus of the present invention, it is preferable that a mechanism for generating a turbulence flow in the flow path is disposed.
Preferably, the apparatus of the present invention includes a light condensing and ultraviolet emitting unit including:
a light source including an ultraviolet light-emitting module where a plurality of “ultraviolet light-emitting devices having a disinfection action” is disposed on a side surface of a cylindrical or polygonal base such that a light axis of each ultraviolet light-emitting device passes through a center axis of the base and the ultraviolet rays are radially emitted to the center axis, and
a light condenser including a long elliptical reflective mirror or a parabolic reflective mirror,
More preferably, the apparatus of the present invention according to the above-described embodiments includes a plurality of the light condensing and ultraviolet emitting units, the light condensing and ultraviolet emitting units are arranged around the flow path, and the object to be disinfected is irradiated with the ultraviolet rays condensed multi-directionally.
Preferably, in the disinfection apparatus of the present invention, the object is disinfected when an ultraviolet transmittance is 50% or less defined by a percentage of a ratio of transmitted ultraviolet intensity to irradiated ultraviolet intensity {(transmitted ultraviolet intensity/irradiated ultraviolet intensity)×100(%)} when the object to be disinfected having a thickness of 1 cm is irradiated with ultraviolet rays having a disinfection action.
The ultraviolet disinfection apparatus of the present invention uses a light source including a plurality of “ultraviolet light-emitting devices (deep ultraviolet light-emitting devices) emitting ultraviolet rays (deep ultraviolet rays) having a disinfection action combined with a light condenser for condensing the ultraviolet rays emitted from each ultraviolet light-emitting device, thereby irradiating the object to be disinfected with deep ultraviolet rays having high intensity by the light condensing, which results in efficient disinfection. In the ultraviolet disinfection apparatus of the present invention, the object to be disinfected passes through the flow path and the light source and the light condenser are disposed externally to the flow path, thereby facilitating maintenance of the apparatus.
According to the ultraviolet disinfection apparatus of the present invention, the object to be disinfected is disinfected when the ultraviolet transmittance is 50% or less defined as described above, and the mechanism for generating the turbulence flow in the flow path is disposed, whereby the object to be disinfected flowing through the center part flows near a wall surface of the flow path, even when the ultraviolet rays irradiated from outside of the flow path is less likely to arrive at the object to be disinfected flowing through the center part of the flow path. Accordingly, if the length of the ultraviolet ray irradiation area is adequate, the object to be disinfected can be uniformly irradiated with ultraviolet rays, thereby performing sure disinfection.
When the ultraviolet disinfection apparatus of the present invention includes the “light condensing and ultraviolet emitting unit” including the light source combined with the light condenser, ultraviolet rays can be irradiated over an ultraviolet ray irradiation area having a rectangle shape and a high and uniform ultraviolet intensity, thereby down-sizing the apparatus. Furthermore, depending on an arrangement of the light condensing and ultraviolet emitting unit, the irradiation area can be freely arranged. For example, when a plurality of the light condensing and ultraviolet emitting units are arranged around the flow path and the object to be disinfected is irradiated with the ultraviolet rays condensed multi-directionally, the disinfection can be performed more efficiently. In addition, when the light condensing and ultraviolet emitting units are arranged in line, an ultraviolet disinfection area can be lengthened.
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An ultraviolet disinfection apparatus of the present invention is characterized by including:
a flow path surrounded by a material having a transmitting property to ultraviolet rays (deep ultraviolet rays) having a disinfection action through which a fluid object to be disinfected passes;
a light source disposed externally to the flow path for emitting ultraviolet rays having a disinfection action,
a light condenser for condensing the ultraviolet rays emitted from the ultraviolet light-emitting devices,
Hereinafter, a preferable embodiment of the ultraviolet disinfection apparatus of the present invention will be described referring to drawings taking a disinfection apparatus as an example, the disinfection apparatus including a “light condensing and ultraviolet emitting unit” 130 including:
a light source including an ultraviolet light-emitting module where a plurality of deep ultraviolet light-emitting devices are disposed on a side surface of a cylindrical base such that a light axis of each deep ultraviolet light-emitting device passes through a center axis of the base and the deep ultraviolet rays are radially emitted to the center axis,
a light condenser including a long elliptical reflective mirror,
As the deep ultraviolet light-emitting devices 112, LEDs (deep ultraviolet LEDs) emitting deep ultraviolet rays having a wavelength of 200 nm to 350 nm, preferably emitting deep ultraviolet rays having a wavelength of 240 nm to 290 nm are used. The deep ultraviolet LEDs are arranged in a state that the devices are mounted on a sub mount or in a state that they are housed in a package and that ultraviolet rays are preferably emitted in a constant direction. Although not shown, wiring for feeding electric power externally to the deep ultraviolet light-emitting devices, circuits for operating correctly the deep ultraviolet light-emitting devices and the like are formed on the sub mount or the package. Electrical power is fed to the wiring or the circuits via wiring formed on a surface of or inside of the cylindrical base 111.
The cylindrical base 111 functions not only as a support to fix and hold the deep ultraviolet light-emitting devices 112, but also as a heat sink. By passing a cooling medium 118 such as cooling water and cooling air through the flow path for a cooling medium 113 inside, a temperature increase caused by heat radiation from the ultraviolet light-emitting devices is prevented such that the devices are operated stably and device lives can be prolonged.
In the present invention, as a number of deep ultraviolet light-emitting devices are intimately mounted on the surface of the cylindrical base 111 as described later, it is especially important to remove efficiently heat generated at the ultraviolet light-emitting devices. Accordingly, the cylindrical base 111 is preferably mainly composed of a metal having a high thermal conductivity such as copper and aluminum and a ceramic. In addition, in order to increase a contact area of the cooling medium, it is preferable that an inner wall surface of the flow path for a cooling medium is subject to grooving. Further, when the cylindrical base 111 is composed of the metal material, it is preferable that an insulation layer is formed in order to insulate a copper wire or a circuit for feeding electrical power from an external power source to the ultraviolet light-emitting devices.
At a side surface of the cylindrical base 111, a plurality of the deep ultraviolet light-emitting devices 112 is arranged along a circumferential direction of the base such that extended lines of light axes 115 of the deep ultraviolet light-emitting devices 112 pass through the center axis 114 of the base 111 and light emitting surfaces are directed outwardly. As a result, ultraviolet rays emitted from the ultraviolet light-emitting devices emitted radially from the center axis 114. Note that the light axes 115 of the deep ultraviolet light-emitting devices 112 mean center axes of light beams emitted from the deep ultraviolet light-emitting devices and are almost synonymous to travel directions of the light beams. Also, note that “arranged such that the light axes 115 pass through the center axis 114 of the base 111” means that such a status is realized as much as possible and there is no problem that the light axis 115 is tilted slightly from the status.
The deep ultraviolet light-emitting devices 112 are preferably arranged so as to form lines in a longitudinal direction of the cylindrical base 111 as shown in the longitudinal cross-sectional view in
In the main body 150, it is preferable that the emitted-side housing 125 and the light-condensed-side housing 126 can be mutually attached/detached or opened/closed using a hinge. At top and bottom openings on both sides of the main body 150 shown in
Surfaces of the emitted-side reflective mirror 120 and the light-condensed-side reflective mirror 123 are preferably composed of a material having a great reflectance to ultraviolet rays, e.g., a platinum group metal such as Ru, Rh, Pd, Os, Ir and Pt; Al, Ag, Ti; an alloy containing at least one of these metals; barium sulfate; or magnesium oxide. On the basis that the reflectance is especially high, it is especially preferable that they are formed of Al, a platinum group metal, an alloy containing the platinum group metal, barium sulfate or magnesium oxide. When they are composed of the metal material, in order to prevent surfaces from oxidizing or scratching and to prevent the reflectance from decreasing, it is preferable that the surface are coated with an ultraviolet transmitting material such as quartz and an ultraviolet transmitting dielectric.
In the ultraviolet light-emitting apparatus 100, the ultraviolet light-emitting module 110 is disposed such that the center axis 114 is coincide with the focal axis 121 of the emitted-side reflective mirror. The light condensing and ultraviolet emitting unit 130 is composed of the emitted-side housing 125 that is the light condenser including the emitted-side reflective mirror 120, and the ultraviolet light emitting module 110. In addition, a flow path 140 is arranged such that the center axis is coincide with the light condensing axis 122 of the emitted-side reflective mirror (the focal axis 124 of the light-condensed-side reflective mirror). As the ultraviolet light emitting module 110 and the flow path 140 are disposed at the position, the deep ultraviolet rays emitted radially from the ultraviolet light emitting module 110 is reflected at the emitted-side reflective mirror and the light-condensed-side reflective mirror and is condensed converging on the focal axis of the light-condensed-side reflective mirror. The flow path 140 is effectively irradiated with the deep ultraviolet rays condensed. Thus, in the ultraviolet light-emitting apparatus 100, in principal, all deep ultraviolet rays emitted radially from the ultraviolet light emitting module 110 can be condensed on the focal axis of the light-condensed-side reflective mirror, and ultraviolet rays emitted not to the flow path 140 (for example, emitted to the opposite direction or the horizontal direction) can be effectively used.
The flow path 140 is surrounded by a material having transmitting properties to ultraviolet rays having a disinfection action, through which a fluid object to be disinfected 160 passes. Accordingly, the object to be disinfected 160 is irradiated with the deep ultraviolet rays transmitted through a surrounding diaphragm such as a quartz tube wall and a sapphire tube wall and is disinfected. The object to be disinfected 160 is a non-limiting liquid, and may be a gas such as air, a liquid such as water and a slurry where a small amount of a minute solid is suspended. When the object to be disinfected 160 flows to the flow path 140, a pretreatment that the object to be disinfected 160 passes through a filter or an adsorption layer is preferably performed in advance, as appropriate.
In order to perform sure disinfection, it is preferable that a mechanism for generating a turbulence flow in the flow path is disposed at the flow path 140. The mechanism for generating a turbulence flow is not especially limited as long as the turbulence flow is generated. Examples include a turbulence grid disposed within the flow path or an inlet of the flow path, irregularity formed on an inner wall surface, turbulence generation chips filled within the flow channel and a turbulence generation apparatus for randomly turning a impeller. When the flow of the object to be disinfected forms a so-called “laminar flow”, the object to be disinfected flowing through the center part of the flow path may not be sufficiently irradiated with the deep ultraviolet rays, depending on the type of the object to be disinfected, the intensity of the deep ultraviolet rays irradiated and the diameter of the flow path. By generating the turbulence, the object to be disinfected flowing through the center part of the flow path can flow near a wall surface of the flow path. Accordingly, if the length of the ultraviolet ray irradiation area is adequate, the object to be disinfected can be uniformly irradiated with ultraviolet rays, thereby performing sure disinfection. In view of the above, attachment of the turbulence generation mechanism is effective when the object to be disinfected having a low deep ultraviolet transmittance, e.g., the object to be disinfected having an ultraviolet transmittance of 50% or less, especially 40% or less, is disinfected. The ultraviolet transmittance is defined by a percentage of a ratio of transmitted ultraviolet intensity to irradiated ultraviolet intensity {(transmitted ultraviolet intensity/irradiated ultraviolet intensity)×100(%)} when the object to be disinfected having a thickness of 1 cm is irradiated with ultraviolet rays having a disinfection action. By attaching the turbulence generation mechanism, sure disinfection can be performed, even when the flow path has a large diameter. Therefore, a flow rate of the object to be disinfected can be increased and a disinfection efficiency can be further increased. A relationship between the ultraviolet transmittance and the thickness of a liquid phase is described in “Tsuneo Harada, et al.,: Germicidal lamp, Toshiba review, Vol. 6, No. 5, p289 (1951)”, for example. According to this, the transmittance of milk, refined sake, beer, glucose injection (20%) or synthetic sake is 40% or less.
While the ultraviolet disinfection apparatus 100 shown in the drawings have been illustrated, it should be understood that the ultraviolet disinfection apparatus of the present invention is not limited thereto. For example, any light-condensed-side reflective mirror having a shape different from the long elliptical reflective mirror used as the emitted-side reflective mirror can be used as long as the ultraviolet rays are reflected to the emitted-side reflective mirror without leaking the ultraviolet rays to outside. As the emitted-side reflective mirror, a parabolic reflective mirror 120′ can be used instead of the long elliptical reflective mirror. A light condenser including the parabolic reflective mirror 120′ can be combined with the ultraviolet light-emitting module 110 to provide a light condensing and ultraviolet emitting unit 130′. A plurality of the light condensing and ultraviolet emitting units 130 or light condensing and ultraviolet emitting units 130′ may be used. The light condensing and ultraviolet emitting units may be arranged around the flow path 140 and the object to be disinfected may be irradiated with the ultraviolet rays condensed multi-directionally.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-240250 | Oct 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/006284 | 10/24/2013 | WO | 00 |
