Patent Description:
Conventionally, chlorine has been typically used for disinfection treatment in water treatment. In recent years, however, disinfection treatment with chlorine has been found to have room for improvement in disinfection performance. Hence, for sufficient disinfection of water, such as drinking water, to be treated by disinfection treatment, techniques using ultraviolet light have been studied. A typical ultraviolet irradiation apparatus for irradiating water to be treated with ultraviolet light includes a mercury lamp as a light source. With the ultraviolet irradiation apparatus including a mercury lamp, however, the risk of mercury coming into contact with water to be treated due to aging degradation of the apparatus or the like cannot be eliminated.

In view of this, water treatment apparatuses using LEDs as ultraviolet light sources have been developed in recent years (for example, see <CIT>). <CIT> discloses a water treatment apparatus (hereafter also referred to as a "first conventional water treatment apparatus") in which LED elements as ultraviolet light sources are arranged in a space defined by a transparent member serving as a window portion. <CIT> also discloses a water treatment apparatus (hereafter also referred to as a "second conventional water treatment apparatus") including a transparent sealing member of glass or the like for protecting LED elements as ultraviolet light sources from water. <CIT> discloses a water treatment apparatus having the features of the preamble of claim <NUM>. <CIT>, <CIT> and <CIT> disclose further related prior art.

In the first conventional water treatment apparatus, in the case where condensation forms in the space in which the LED elements as ultraviolet light sources are installed, the exposed LED elements may be damaged. In the second conventional water treatment apparatus, the LED elements as ultraviolet light sources are kept from being damaged by water, but the sealing member provided for each LED element causes a decrease in the intensity of ultraviolet light emitted from the LED element, so that the desired irradiation intensity cannot be ensured adequately.

It could therefore be helpful to provide a water treatment apparatus that uses unsealed, i.e. exposed, LED elements as ultraviolet light sources and can prevent the LED elements from being damaged due to condensation while maintaining the intensity of ultraviolet light emitted from the LED elements.

As a result of extensive studies, we discovered the following: In a water treatment apparatus that subjects water to be treated to ultraviolet treatment with ultraviolet light emitted from LED elements, by providing an LED element housing chamber that houses LED elements with exposed light emitting surfaces and also causing dry gas to flow into the housing chamber, the LED elements can be prevented from being damaged due to condensation while maintaining the intensity of ultraviolet light emitted from the LED elements.

The above-mentioned problem is solved by a water treatment apparatus having the features of claim <NUM>. Advantageous further developments are set out in the dependent claims.

By arranging the LED elements in the LED element housing chamber in a state in which their light emitting surfaces are exposed and also causing dry air to flow into the LED element housing chamber, the LED elements can be prevented from being damaged due to condensation while maintaining the intensity of ultraviolet light emitted from the LED elements.

Furthermore, in the water treatment apparatus according to the present disclosure, a light collection plate that surrounds each of the plurality of LED elements is located in the LED element housing chamber, and a gap is provided between the light collection plate and the window portion. The light collection plate collects ultraviolet light from the LED element, thus further increasing the ultraviolet irradiation intensity for the water to be treated. Moreover, by providing a gap between the light collection plate and the window portion so as to keep the light collection plate from being in contact with the window portion, the condensation prevention effect by the dry gas is further enhanced.

Preferably, in the water treatment apparatus according to the present disclosure, an installation density of the plurality of LED elements is <NUM>,<NUM> elements/m<NUM> or more. As a result of the LED installation density being a high density of <NUM>,<NUM> elements/m<NUM> or more, the ultraviolet irradiation intensity for the water to be treated can be further increased to enhance the disinfection effect by the water treatment apparatus.

Preferably, the water treatment apparatus according to the present disclosure comprises a cooling device located on a side of the LED element housing chamber opposite to the flow channel. By cooling the LED element housing chamber from the back side, i.e. the side opposite to the flow channel, life reduction and failures of the LED elements can be prevented.

Preferably, the water treatment apparatus according to the present disclosure comprises a seal member between a member forming the flow channel and the transparent member forming the window portion, and a seal member between the transparent member forming the window portion and a member forming the LED element housing chamber. By providing a seal not only on one side of the transparent member forming the window portion but on both sides of the transparent member, the reliability of the water treatment apparatus can be improved.

The water treatment apparatus according to the present disclosure can prevent the LED elements from being damaged due to condensation while maintaining the intensity of ultraviolet light emitted from the LED elements.

In the accompanying drawings:
<FIG> is a schematic diagram of a water treatment apparatus according to one of the disclosed embodiments.

An embodiment of a water treatment apparatus according to the present disclosure will be described in detail below, with reference to drawings. For example, the water treatment apparatus according to the present disclosure can be installed in large-scale facilities such as water purification plants, small-scale water dispensers, sewage treatment plants, and ultrapure water production equipment, and can be used for drinking water disinfection treatment.

<FIG> is a schematic diagram of a water treatment apparatus according to one of the disclosed embodiments. A water treatment apparatus <NUM> illustrated in <FIG> is a water treatment apparatus that subjects water to be treated to ultraviolet treatment with ultraviolet light emitted from LED elements. The water treatment apparatus <NUM> includes: a flow channel <NUM> through which water to be treated flows; an LED element housing chamber <NUM> located on the outside of the flow channel <NUM> with a window portion <NUM> being interposed therebetween; and a plurality of LED elements <NUM> arranged in the LED element housing chamber <NUM>. The LED element housing chamber <NUM> has an inlet <NUM> and an outlet <NUM> for dry gas. The light emitting surfaces of the LED elements <NUM> are exposed to the space in the LED element housing chamber <NUM>. The water treatment apparatus <NUM> irradiates the water to be treated flowing through the flow channel <NUM> with ultraviolet light emitted from the LED elements <NUM> in the LED element housing chamber <NUM>, to perform disinfection treatment. The resultant treated water may be, for example, delivered to any type of facility for drinking water supply, as drinking water.

Each functional unit in the water treatment apparatus <NUM> will be described in more detail below. In the following description, the side on which the water to be treated flows into the water treatment apparatus <NUM> is referred to as "upstream side", and the side on which the treated water flows out of the water treatment apparatus <NUM> is referred to as "downstream side".

The flow channel <NUM> may be formed in a double pipe structure <NUM> including an inner pipe <NUM> and an outer pipe <NUM> that may be, for example, SUS pipes. The inner pipe <NUM> is surrounded by the outer pipe <NUM> located on the outer circumferential side of the inner pipe <NUM>. The outer pipe <NUM> has an outlet (not illustrated) for the treated water at, for example, its outer circumference surface, without being limited thereto. A gap is provided between the edge of the inner pipe <NUM> on one side in the axial direction and the window portion <NUM>. Such a gap may be defined by an optional displacement prevention member <NUM>. The displacement prevention member <NUM> is not limited as long as it can define a gap <NUM> between the edge of the inner pipe <NUM> on one side in the axial direction and the window portion <NUM>, and may be formed by, for example, a flange, a spigot joint type flange, and/or a lock pin. Thus, the displacement prevention member <NUM> illustrated in <FIG> may be a spigot joint type flange having a spigot joint type projection that may hold the inner pipe <NUM> at a predetermined position and define the gap between the inner pipe <NUM> and the window portion <NUM>, although not illustrated in detail. The displacement prevention member <NUM> is, however, not limited to a spigot joint type flange, and may be, for example, a normal flange without a spigot joint type projection. In this case, for example, the gap between the inner pipe and the window portion can be defined by a structure in which the inner pipe is pressed downward in the axial direction and, at a position at which the inner diameter of the tapered inner circumferential surface of the displacement prevention member matches the outer diameter of the inner pipe, held so as not to move further downward in the axial direction.

The end of the outer pipe <NUM> on the window portion <NUM> side in the axial direction may have a flange. The displacement prevention member <NUM> illustrated as a spigot joint type flange and the flange of the end of the outer pipe <NUM> are fixed to each other, and extend beyond the inner pipe <NUM> to one side in the axial direction. In particular, the displacement prevention member <NUM> holds the window portion <NUM>, and is connected to the window portion <NUM> liquid-tightly. Although the displacement prevention member <NUM> and the outer pipe <NUM> are illustrated as separate members in <FIG>, they may be combined as one member. That is, the outer pipe <NUM> may surround the inner pipe <NUM> and also have a structure of defining the gap <NUM> between the edge of the inner pipe <NUM> on one side in the axial direction and the window portion <NUM>.

The inner pipe <NUM>, the outer pipe <NUM>, and the optional displacement prevention member <NUM> form the flow channel <NUM> and a treated water flow channel <NUM> into which the treated water that has passed through the flow channel <NUM> and has been treated with ultraviolet light from the window portion <NUM> flows.

The flow of water that has passed through the flow channel <NUM> and collided with the window portion <NUM> is irradiated with ultraviolet light from the LED element housing chamber <NUM> via the window portion <NUM> while flowing along the surface of the window portion <NUM>. The water to be treated that has flown into the water treatment apparatus <NUM> and passed through the flow channel <NUM> thus undergoes ultraviolet treatment and turns into treated water. The treated water flows along the surface of the window portion <NUM> toward the inner wall surfaces of the inner pipe <NUM>, the outer pipe <NUM>, and the displacement prevention member <NUM>, thus passing through the gap <NUM> and reaching the treated water flow channel <NUM> defined by the inner pipe <NUM>, the outer pipe <NUM>, and the displacement prevention member <NUM>. The treated water then passes through the treated water flow channel <NUM>, and flows out of the water treatment apparatus <NUM> through the outlet at the outer circumference surface of the outer pipe <NUM>.

The window portion <NUM> is, for example, desirably made of a transparent material having high ultraviolet light transmittance. For example, the window portion <NUM> is preferably formed by a transparent member obtained by forming a transparent material such as quartz glass (SiO<NUM>), sapphire glass (Al<NUM>O<NUM>), or fluorine-based resin in plate shape. In terms of durability, transparency, and the like, the transparent material is preferably quartz glass. The window portion <NUM> is located on one side in the axial direction (the lower side in <FIG>) of the double pipe structure <NUM> composed of the inner pipe <NUM> and the outer pipe <NUM>. The LED element housing chamber <NUM> is located on the outside of the flow channel <NUM> with the window portion <NUM> being interposed therebetween.

The LED element housing chamber <NUM> contains the plurality of LED elements <NUM>. These LED elements <NUM> have their light emitting surfaces exposed to the space in the LED element housing chamber <NUM>. Herein, the expression "a light emitting surface of an LED element is exposed" means that a light emitting surface formed by placing an epitaxial layer and the like of an LED structure on a substrate such as a sapphire substrate is not covered by a structural part, such as a lens and/or a sealing member, not directly contributing to light emission. Ultraviolet light emitted from the plurality of LED elements <NUM> whose light emitting surfaces are exposed to the space in the LED element housing chamber <NUM> is applied to the water to be treated flowing in the inner pipe <NUM>.

Each LED element <NUM> may be, for example, an element that emits ultraviolet light of a wavelength of <NUM> or more and more preferably <NUM> or more and <NUM> or less and more preferably <NUM> or less. Ultraviolet light in such wavelength ranges particularly has high disinfection power.

The plurality of LED elements <NUM> may be, for example, arranged in a state of being fixed to an LED substrate <NUM>,without being limited thereto. The installation density of the plurality of LED elements <NUM> in the LED element housing chamber <NUM> is preferably <NUM>,<NUM> elements/m<NUM> or more. By arranging the LED elements in the LED element housing chamber <NUM> at a high density of <NUM>,<NUM> elements/m<NUM> or more, the ultraviolet irradiation intensity can be increased, and the disinfection performance of the water treatment apparatus <NUM> can be improved. In the present disclosure, such high density arrangement of LED elements is enabled as a result of employing a structure of arranging the plurality of LED elements <NUM> with their light emitting surfaces being exposed to the space in the LED element housing chamber <NUM>.

The LED element housing chamber <NUM> is surrounded by an LED element housing chamber defining flange <NUM>, the window portion <NUM>, and the LED substrate <NUM>. The LED substrate <NUM> has a dry gas inlet <NUM> through which dry gas flows into the LED element housing chamber <NUM>. The LED element housing chamber defining flange <NUM> has at least one dry gas outlet <NUM> and preferably has a plurality of dry gas outlets <NUM>, at its wall portion defining the LED element housing chamber <NUM> in the axial direction of the water treatment apparatus <NUM>.

Herein, "dry gas" denotes air whose dew-point temperature is not higher than the dew-point temperature of ambient air of the installation environment of the water treatment apparatus <NUM>. More specifically, the dry gas may be air having a dew point of <NUM> or less. The temperature of the dry gas may be room temperature (JIS Z <NUM>), without being limited thereto. The dry gas that has flown into the LED element housing chamber <NUM> through the dry gas inlet <NUM> collides with the window portion <NUM>, flows along the window portion <NUM>, and is eventually released from the dry gas outlet(s) <NUM>. By circulating the dry gas in the LED element housing chamber <NUM> in this way, the LED elements can be prevented from being damaged due to condensation.

A light collection plate <NUM> that surrounds each LED element <NUM> is located in the LED element housing chamber <NUM>, and a gap is provided between the light collection plate <NUM> and the window portion <NUM>. When each LED element <NUM> is provided with the light collection plate <NUM> such as a reflector, ultraviolet light emitted from the LED element <NUM> can be collected to further increase the ultraviolet irradiation intensity for the water to be treated. The shape of the light collection plate <NUM> can be freely optimized based on the distance from the window portion <NUM>, the area and thickness of the window portion <NUM>, and the like. The light collection plate <NUM> such as a reflector may be held via a light collection plate holding member <NUM> such as a reflector mount.

A gap is provided between the top part of the light collection plate <NUM> in the axial direction and the window portion <NUM>. With a gap between the light collection plate <NUM> and the window portion <NUM>, the fluidity of the dry gas in the LED element housing chamber <NUM> can be increased to further enhance the condensation prevention effect by the dry gas. The size of the gap can be set freely, but is preferably <NUM> or more and <NUM> or less. If the size of the gap is <NUM> or more, the light collection effect by the light collection plate <NUM> can be ensured adequately. If the size of the gap is <NUM> or less, the condensation prevention effect by the dry gas can be enhanced adequately.

The transparent member forming the window portion <NUM> is held from both sides in the axial direction by the displacement prevention member <NUM> and the LED element housing chamber defining flange <NUM>. The displacement prevention member <NUM>, the LED element housing chamber defining flange <NUM>, and the flange at the end of the outer pipe <NUM> may be fixed to each other. The fixing method is not limited, and may be, for example, a typical fixing method using bolts <NUM> and nuts <NUM> illustrated in <FIG>.

Preferably, a first seal member <NUM> is located between the displacement prevention member <NUM> and the transparent member forming the window portion <NUM>, and a second seal member <NUM> is located between the transparent member forming the window portion <NUM> and the LED element housing chamber defining flange <NUM>. The first seal member <NUM> is pressed from above and below in the axial direction by the displacement prevention member <NUM> and the window portion <NUM>, to enhance the sealing connection between the displacement prevention member <NUM> and the window portion <NUM>. The second seal member <NUM> is pressed from above and below in the axial direction by the window portion <NUM> and the LED element housing chamber defining flange <NUM>, to enhance the sealing connection between the window portion <NUM> and the LED element housing chamber defining flange <NUM>. The first seal member <NUM> and the second seal member <NUM> are each a member capable of, as a result of being interposed and compressed between connection objects, ensuring the sealing of the pipe members as the connection objects. More specifically, the first seal member <NUM> and the second seal member <NUM> may be, for example, packing or gaskets. The seal members such as packing or gaskets may be members containing an elastic material such as rubber.

By sealing the transparent member not only on the flow channel <NUM> side but on both sides, the reliability of the water treatment apparatus <NUM> can be improved. In the case where the water to be treated leaks into the LED element housing chamber <NUM>, the water treatment apparatus <NUM> fails. The stringent sealing structure described above can, however, prevent water from entering the LED element housing chamber <NUM>.

The water treatment apparatus <NUM> preferably includes a cooling device <NUM> on the side of the LED element housing chamber <NUM> opposite to the flow channel <NUM>. For example, the cooling device <NUM> may be composed of a cooling chamber <NUM> provided in a cooling plate and a cooling water line <NUM> through which cooling water flows into the cooling chamber. The water treatment apparatus <NUM> has a feature of causing dry gas to flow into the LED element housing chamber <NUM>, as mentioned above. Accordingly, in the water treatment apparatus <NUM>, it is impossible to cool the LED elements <NUM> by using the water to be treated flowing through the flow channel <NUM>. Moreover, the light emitting surfaces of the LED elements <NUM> are exposed to the space in the LED element housing chamber <NUM> without being protected by lenses, sealing members, or the like in the water treatment apparatus <NUM>. Hence, in the water treatment apparatus <NUM>, it is also impossible to cool the LED elements <NUM> by introducing cooling water directly into the LED element housing chamber <NUM>. In view of this, in the present disclosure, the cooling device <NUM> is provided on the side of the LED element housing chamber <NUM> opposite to the flow channel <NUM>, with it being possible to cool the LED elements <NUM>. By cooling the LED elements <NUM> in this way, the life of the LED elements <NUM> can be increased, and failures of the LED elements <NUM> can be prevented.

Although not illustrated, the cooling water line <NUM> may be connected to the outer pipe <NUM>, to supply the treated water to the cooling chamber <NUM> as the cooling water. The treated water as the cooling water circulated in the cooling chamber <NUM> may meet the treated water flowing out of the outer pipe <NUM>, through a cooling water drainage line (not illustrated). If the cooling water line <NUM> is connected to the outer pipe <NUM>, the LED elements <NUM> can be cooled without installing a separate power source for supplying water to the cooling chamber <NUM>. With such a structure, the water treatment efficiency of the water treatment apparatus <NUM> can be further improved.

While the water treatment apparatus according to the present disclosure has been described above by way of an embodiment, the water treatment apparatus according to the present disclosure is not limited to the foregoing embodiment. The water treatment apparatus according to the present disclosure can be subjected to changes as appropriate.

Specifically, for example, although the foregoing embodiment describes the case where the cooling chamber <NUM> is a void in the cooling plate which is a plate-like member supporting the LED substrate <NUM>, the cooling chamber may be, for example, an inner space of a pipe provided in any of various shapes such as spiral and zigzag. The cooling chamber having such a structure can contribute to higher LED element cooling efficiency.

Claim 1:
A water treatment apparatus that subjects water to be treated to ultraviolet treatment with ultraviolet light emitted from LED elements (<NUM>), the water treatment apparatus comprising:
a flow channel (<NUM>) through which water to be treated flows;
an LED element housing chamber (<NUM>) located on outside of the flow channel (<NUM>), with a window portion (<NUM>) formed by a transparent member being interposed therebetween; and
a plurality of LED elements (<NUM>) arranged in the LED element housing chamber (<NUM>),
wherein the LED element housing chamber (<NUM>) has an inlet (<NUM>) and an outlet (<NUM>) for dry gas, and
light emitting surfaces of the plurality of LED elements (<NUM>) are not covered by a structural part not directly contributing to light emission and the light emitting surfaces are exposed to a space in the LED element housing chamber (<NUM>), characterized in that
the water treatment apparatus further comprises a light collection plate (<NUM>) surrounding the respective LED elements (<NUM>) so as to collect ultraviolet light emitted therefrom and arranged in the LED element housing chamber (<NUM>),
a gap is provided between the light collection plate (<NUM>) and the window portion (<NUM>) so as to allow a flow of the dry gas to pass through,
the window portion (<NUM>) is located on one side in an axial direction of the flow channel (<NUM>) formed in a double pipe structure (<NUM>) including an inner pipe (<NUM>) and an outer pipe (<NUM>), such that the flow of water that has passed through the flow channel (<NUM>) and collided with the window portion (<NUM>) is irradiated with ultraviolet light from the LED element housing chamber (<NUM>) via the window portion (<NUM>) while flowing along a surface of the window portion (<NUM>).