Ultraviolet irradiation water treatment apparatus

An ultraviolet irradiation water treatment apparatus includes a vessel having a cylindrical side portion, and plural rod-shaped ultraviolet lamps are disposed in parallel with a central axis of the side portion in the vessel. A water inlet pipe through which water flows into the vessel is provided in an outer wall of the side portion at a position in a tangential direction of an inner periphery of the side portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultraviolet irradiation water treatment apparatus which irradiates water with an ultraviolet ray to inactivate or detoxify algae, microbes, pathogenic protozoa, and the like in a water-purifying treatment, a sewage treatment, a food effluent treatment, a chemical effluent treatment, a deep-sea vessel ballast water treatment, and the like, for example, and to an ultraviolet irradiation water treatment apparatus of high ultraviolet irradiation efficiency.

2. Description of the Related Art

Conventionally, waterworks in Japan are managed based on sanitarian safety by chlorination.

Recently, water system contamination problems have been generated by new and reconstructed pathogenic microbes such as cryptosporidium and Giardia. There are also the problems of mass generation of algae with the progress of eutrophication, which is organic matter pollution, in lakes, dams, and rivers, which are water service resources. The mass generation of algae causes an unusual odor and taste, discoloring, aggregation, sedimentation inhibition, filter clogging, and filtrate water leakage problems. Additionally, a chlorine agent injected for the purpose of disinfection reacts with the organic matter in raw water to produce toxic by-products such as trihalomethane.

The improvement in management of a basic pattern in which the aggregation, filtration, and chlorination are sequentially performed is being studied to solve these problems for conventional waterworks in Japan.

Specifically, use of ultraviolet disinfection, in which water is irradiated with an ultraviolet ray, is now replacing the conventional chlorination method. In ultraviolet disinfection, disadvantageously complicated chemical injection control is not required, and no toxic by-products such as trihalomethane are not generated. Ultraviolet disinfection is also highly effective at suppressing the proliferation of cryptosporidium, which reduces infectability thereof. Therefore, sometimes an ultraviolet irradiation treatment is performed to oxidize and disinfect residue organics at water purification works.

In ultraviolet disinfection, usually, filtered water or aggregated and sedimented water is irradiated, as this provides high ultraviolet transmission efficiency. However, sometimes the raw water is irradiated with an ultraviolet ray in order to improve the aggregation or to eliminate the infectability of pathogenic protozoa such as cryptosporidium. That is, the raw water is irradiated with an ultraviolet ray instead of use of prechlorination.

Ultraviolet irradiation also effectively prevents the reproduction of algae, which is desired in the water-purifying treatment.

Where ultraviolet irradiation is used to kill pathogenic microbes or protozoa, ultraviolet in the wavelength range of 200 nm to 300 nm, which is called the UV-C band, is effective. A low-pressure or medium-pressure mercury lamp in which mercury vapor is enclosed in a lamp is used to generate a UV-C band ultraviolet ray.

An apparatus in which one or plural ultraviolet lamps are disposed in parallel is well known as an apparatus for irradiating water with an ultraviolet ray (see “ULTRAVIOLET DISINFECTION GUIDANCE MANUAL”, United States Environmental Protection Agency, June 2003, Draft).

However, the ultraviolet irradiation dose necessary to inactivate pathogenic protozoa, microbes, and virus, which are disinfection targets, depends on the microbial species in question. Therefore, it is necessary for the water containing the pathogenic protozoa, bacteria, and virus, which are the disinfection targets, to be effectively irradiated with an ultraviolet ray within the period of time the water is present in the ultraviolet irradiation water treatment apparatus.

Since the intensity of an ultraviolet ray is decreased in inverse proportion to the square of the distance from the ultraviolet lamp, in order to effectively irradiate the water with the ultraviolet ray, it is necessary to cause the water to pass near the ultraviolet lamp.

Therefore, Jpn. Pat. Appln. KOKAI Publication No. 9-503160 discloses a method in which a spiral guide vane is disposed in order that the water flows while swirling in an outer periphery of the ultraviolet lamp, and Jpn. Pat. Appln. KOKAI Publication Nos. 2004-512905 and 2001-516637 disclose a method in which a secondary flow, such as a vortex flow, is induced such that the whole body of water passes near the ultraviolet lamp.

The configuration shown inFIG. 41can be cited as an example of a conventional ultraviolet irradiation water treatment apparatus100.

In the ultraviolet irradiation water treatment apparatus100, water W1enters from a water inlet pipe102located in a lower portion of a cylindrical vessel101, and the water W1rises in an axial direction of the vessel101. Then, the water W1flows out from a water outlet pipe103located in an upper portion of the vessel101. An ultraviolet lamp105surrounded by a protective tube104is disposed along a central axis of the cylindrical vessel101. A spiral guide vane106is disposed in the vessel101. In an ultraviolet irradiation water treatment apparatus100having the above-described configuration, the water W1flows while swirling around the ultraviolet lamp105along the spiral guide vane106. Therefore, the whole body of water W1can evenly be irradiated with the ultraviolet ray.

The configuration shown inFIG. 42can be cited as another example of a conventional ultraviolet irradiation water treatment apparatus,100S. InFIG. 42, the same components as those inFIG. 41are designated by the same numerals, and an overlapping description is omitted.

In the ultraviolet irradiation water treatment apparatus100S, the water W1flows in from the water inlet pipe102formed in the lower portion of the cylindrical vessel101, and the water W1rises in the axial direction of the vessel101. Then, the water W1flows out from the water outlet pipe103formed in the upper portion of the vessel101. The ultraviolet lamp105surrounded by the protective tube104is disposed in the central axis of the cylindrical vessel101. A spiral flow path110having a semicircular shape in section is formed in an inner wall surface of the cylindrical vessel101so as to surround the ultraviolet lamp105. That is, in the ultraviolet irradiation water treatment apparatus100S having the configuration shown inFIG. 42, the water W1flows in from the water inlet pipe102, and the water W1passes through the spiral flow path110. This enables the water W1to flow while swirling in the outer periphery of the ultraviolet lamp105. Therefore, the whole body of water W1can evenly be irradiated with an ultraviolet ray. Because the spiral flow path110has a semicircular shape in section, a vortex flow is induced as a secondary flow of the fluid. Therefore, the water W1passes near the ultraviolet lamp105, and the water W1can efficiently be irradiated with an ultraviolet ray.

However, there are the following problems in the conventional ultraviolet irradiation water treatment apparatus.

(A) In the case where plural ultraviolet lamps are used to treat a large amount of water, the structure of the apparatus necessarily becomes more complicated, which could increase the risk of failure. Additionally, the production cost is high since the apparatus has a complicated structure.

(B) In order to treat a large amount of water, it has also been considered to dispose plural ultraviolet lamps in parallel with the direction in which the water flows. However, in the case where plural ultraviolet lamps are disposed, and one of the lamps has broken, the neighborhood of the broken ultraviolet lamp is insufficiently irradiated with ultraviolet rays, since the ultraviolet rays from the surrounding ultraviolet lamps are blocked by the broken ultraviolet lamp.

(C) Crystal quartz or synthetic quartz is used as a material for the protective tube which is disposed to protect the ultraviolet lamp. The crystal quartz or synthetic quartz glass tube is highly fragile, and easily breaks if subjected to slight impact. Therefore, in the case where an ultraviolet lamp is broken, unfortunately, mercury enclosed in the ultraviolet lamp leaks into the water, or fragments of the quartz glass tube constituting the ultraviolet lamp and protective tube are mixed into the water.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided an ultraviolet irradiation water treatment apparatus which causes water to flow in, performs an ultraviolet ray irradiation treatment, and causes treated water to flow out, wherein the apparatus main body includes a vessel having a cylindrical side portion, an inside of the vessel includes: a plurality of rod-shaped ultraviolet lamps which are disposed in parallel with a central axis of the side portion; and a plurality of protective tubes which are separately disposed to protect each ultraviolet lamp so as to surround each ultraviolet lamp, and an outer wall of the vessel includes: a water inlet pipe which is provided in a tangential direction of an inner periphery of the side portion to cause the water to flow in; and a water outlet pipe which causes the treated water to flow out.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

FIG. 1is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10according to a first embodiment of the invention, andFIG. 2is a plan view showing the ultraviolet irradiation water treatment apparatus10.

In the ultraviolet irradiation water treatment apparatus10, water W1is caused to flow in, the water W1is irradiated with the ultraviolet ray, and the treated water W2is caused to flow out.

A vessel20of the ultraviolet irradiation water treatment apparatus10includes a cylindrical side portion21.

A water inlet pipe22and a water outlet pipe23are provided in an outer wall of the vessel20. End faces24A and24B are provided in both end portions of the vessel20.

The water inlet pipe22is provided in a tangential direction T of an inner periphery of the side portion21to cause the water W1to flow in.

The water outlet pipe23is provided in the vessel20to cause the treated water W2to flow out. The water outlet pipe23is disposed in an outer wall of the side portion21along a flow direction of the water W1flowing from the water inlet pipe22. More particularly, the water outlet pipe23is provided in the tangential direction of the inner periphery of the side portion21.

The water inlet pipe22and the water outlet pipe23are disposed in end portions21A and21B which are different from each other in the side portion21. In other words, the water inlet pipe22and the water outlet pipe23are connected to the vessel20with the central axes of the water inlet pipe22and water outlet pipe23apart from each other. Inner diameters of the water inlet pipe22and water outlet pipe23are not more than a half of an inner diameter of the side portion21.

Ultraviolet lamps30A to30F and protective tubes31A to31F are disposed inside the vessel20.

The ultraviolet lamps30A to30F are disposed in parallel with a central axis S of the side portion21. The ultraviolet lamps30A to30F are disposed in end surfaces24A and24B, and the ultraviolet lamps30A to30F are provided at equal intervals on a circumference around the central axis S. Specifically, a quartz tube rod in which electrodes are attached to both ends is formed in a U-shape and used as the ultraviolet lamp. The inside of the quartz tube is in a substantial vacuum state and only mercury vapor is present in the quartz tube. When a high voltage is applied between the electrodes of the quartz tube to generate a discharge, electrons excite the mercury vapor to emit an ultraviolet ray.

In the first embodiment, an ultraviolet lamp, which emits an ultraviolet ray having a wavelength of 200 nm to 300 nm is used, but an ultraviolet lamp which emits an ultraviolet ray having a wavelength of 254 nm is more preferably used. The water W1is exposed to the ultraviolet ray to detoxify the disinfection target substance in the water. An ultraviolet lamp having a diameter of about 2 to about 10 cm is used.

The protective tubes31A to31F protect the ultraviolet lamps30A to30F such that the water W1does not directly contact the ultraviolet lamps30A to30F. Therefore, the protective tubes31A to31F are separately disposed so as to surround each of the ultraviolet lamps30A to30F. The protective tubes31A to31F are made of quartz glass, and the protective tubes31A to31F are disposed in the end surfaces24A and24B.

The action of the ultraviolet irradiation water treatment apparatus10according to the first embodiment will be now described.

The water W1flows into the vessel20through the water inlet pipe22. At this point, because the water inlet pipe22is formed in the tangential direction T of the inner periphery of the vessel20, the water W1flowing into the vessel20swirls (seeFIG. 3).

The water W1becomes such a swirling flow that flow velocity is increased on the side of an inner wall21W of the side portion21. At this point, the ultraviolet lamps30A to30F emit an ultraviolet ray having a wavelength near 254 nm. The ultraviolet ray having the wavelength near 254 nm acts as a disinfection ray to inactivate cryptosporidium of anti-chlorine microbes, fungi such as microbes and colibacillus, virus, and algae in the water. This enables the water W1to be disinfected.

The water W1disinfected by the ultraviolet ray is discharged as the treated water W2from the water outlet pipe23. Then, the treated water W2is delivered to the next water-purifying process or directly supplied to a user.

As described above, according to the ultraviolet irradiation water treatment apparatus10according to the first embodiment, the water inlet pipe22is provided in the outer peripheral wall of the side portion21in the tangential direction T of the inner periphery of the side portion21, so that the water W1can swirl. Therefore, the water W1can flow while effectively contacting the ultraviolet lamps30A to30F, and the ultraviolet irradiation efficiency can be increased. In other words, the swirling flow is generated so that the whole of the water W1can efficiently be irradiated with the ultraviolet ray.

That is, the water W1has uneven flow in the connection portion between the vessel20and the water inlet pipe22and water outlet pipe23in the case where the water inlet pipe22and the water outlet pipe23are not formed in the tangential direction of the inner periphery of the vessel20, like a conventional ultraviolet irradiation water treatment apparatus100T whose plan view is shown inFIG. 4. When the water W1has a high flow rate, because most of the water W1flows more smoothly from the water inlet pipe22to the water outlet pipe23, the whole body of water W1cannot evenly be irradiated with the ultraviolet ray. Because a transit time (irradiation time) in the vessel20is decreased, a sufficient ultraviolet dose cannot be applied for the disinfection.

On the contrary, in the ultraviolet irradiation water treatment apparatus10according to the first embodiment, the water W1does not flow smoothly, but has a swirling flow, so that the transit time can be lengthened. The ultraviolet dose (mJ/cm2) is calculated by integration of the ultraviolet illumination (mW/cm2) and irradiation time (sec). In the ultraviolet irradiation water treatment apparatus10according to the first embodiment, since the water W1is irradiated with the ultraviolet dose of 10 mJ/cm2or more, the infectability of the cryptosporidium to human can be inactivated.

In the ultraviolet irradiation water treatment apparatus10according to the first embodiment, the water W1can evenly be irradiated with the ultraviolet ray even if one of the ultraviolet lamps is broken.

That is, when at least one ultraviolet lamp is deteriorated or broken, because an output of the ultraviolet lamp is decreased, the illumination lacks around the ultraviolet lamp whose output is lowered, and insufficient disinfection is possibly performed. For example,FIG. 5shows the illumination distribution in the vessel20in the case where one ultraviolet lamp30F of the ultraviolet lamps30A to30F is turned off. InFIG. 5, the numeral L1designates a sufficient illumination region and the numeral L2designates an insufficient illumination region.FIG. 5is a sectional view showing the side portion21of the vessel20.

On the contrary, in the ultraviolet irradiation water treatment apparatus10according to the first embodiment, the water W1has a swirling flow, so that the water W1can sufficiently be irradiated with the other lit ultraviolet lamps30A to30E, and the disinfection can sufficiently be performed. That is, even if one (30F) of the ultraviolet lamps is broken or turned off, the influence of the turned-off or broken ultraviolet lamp can be reduced.

In the ultraviolet irradiation water treatment apparatus10according to the first embodiment, plural ultraviolet lamps30are disposed in parallel, and the water flows so as to contact all the ultraviolet lamps, which enhances the irradiation efficiency. Therefore, because the ultraviolet irradiation water treatment apparatus can be downsized, the apparatus is easily incorporated into existing facilities.

Considering that the ultraviolet irradiation water treatment apparatus10is used for water-purifying treatment, this exerts a significant effect. This is because water-purifying treatment facilities are widely used in society at large. Therefore, there is a demand for such an ultraviolet irradiation water treatment apparatus that can be incorporated into the existing facilities and equipment. For example, in an ultraviolet irradiation water treatment apparatus including only one ultraviolet lamp, it is necessary to increase the total length of the apparatus. On the other hand, the ultraviolet irradiation water treatment apparatus10according to the first embodiment includes plural (six) ultraviolet lamps, so that the irradiation efficiency is increased several times (six times) for the same total length.

Sometimes the water W1can be irradiated more effectively with an ultraviolet ray by providing a baffle40in the ultraviolet irradiation water treatment apparatus10according to the first embodiment.FIGS. 6 and 7are a side view and a plan view showing an example of an ultraviolet irradiation water treatment apparatus10A including the baffle40.

An effect of providing the baffle40will be described below.

When the water W1flowing from the water inlet pipe22has a high flow rate, because the transit time of the water W1in the vessel20is decreased, sometimes a sufficient ultraviolet dose is not obtained. The baffle40is provided in the inner wall21W of the side portion21such that a longitudinal direction of the baffle40runs parallel to the central axis S, whereby the swirling flow of the water W1can be weakened. This enables the flow to be increased in the central portion of the vessel20. Accordingly, the water W1can sufficiently be irradiated with an ultraviolet ray.

The number of baffles40is not limited to one, and plural baffles40may be provided. However, the ultraviolet lamps30A to30F tend to make the flow smoother. Therefore, it is necessary that the number of baffles and a position, a size, and a shape of the baffle be determined in consideration of the flow rate of the water W1, and the diameter and position of the ultraviolet lamps, the diameter of the water inlet pipe22, and the position of the water outlet pipe23.

Second Embodiment

FIG. 8is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10B according to a second embodiment of the invention, andFIG. 9is a plan view showing the ultraviolet irradiation water treatment apparatus10B. The same components as the first embodiment are designated by the same numerals, and an overlapping description is omitted unless otherwise needed. In the following embodiments subsequent to the second embodiment, overlapping descriptions are also omitted.

In the ultraviolet irradiation water treatment apparatus10B according to the second embodiment, a cleaning apparatus50is incorporated into the ultraviolet irradiation water treatment apparatus10A according to the first embodiment.

The cleaning apparatus50includes a cleaning component51, a moving component52, a drive shaft53, and drive motor54.

The cleaning component51scrapes the protective tubes31A to31F to wash out stains. Specifically, a resin brush made of a fluorocarbon resin or the like which is not deteriorated by an ultraviolet ray, or a metal brush made of SUS can be used as the cleaning component51. More preferably, a stainless steel brush is used.

A ring-shaped cleaning component may be used instead of the brush-shaped cleaning component51. Specifically, an O-ring made of a fluorocarbon resin or the like can be used. When a brush is used as the cleaning component51, bristles on the brush may break and sometimes fragments are mixed into the treated water W2. Therefore, it is necessary to perform membrane separation to remove the fragments in the next treatment process. On the other hand, when an O-ring is used as the cleaning component51, the membrane separation process can be eliminated. Therefore, preferably an O-ring is used as the cleaning component51in the water-purifying treatment.

The moving component52fixes the cleaning component51to the drive shaft53to support the cleaning component51, and the moving component52moves the cleaning component51along the drive shaft53according to rotation of the drive shaft53. Specifically, the moving component52is attached to the cleaning component51, and the moving component52is connected to the drive shaft53with an external and internal thread structure.

The drive shaft53is provided along the central axis S of the vessel20, and the rotation of the drive shaft53drives the moving component52along the central axis S. That is, the drive shaft53is connected to the moving component52with the external and internal thread structure, whereby the rotational energy of the drive shaft53is converted into the drive energy of the moving component52.

The drive motor54is used to rotate the drive shaft53. The drive motor54can be drive-timed. For example, the drive motor54can be set by a built-in timer so as to be driven every 15 minutes.

As described above, the ultraviolet irradiation water treatment apparatus10B includes the cleaning apparatus50, so that disinfecting performance using ultraviolet irradiation can be maintained.

An action of the cleaning apparatus50will be described next.

The organic and inorganic matter dissolved in the water W1attach to the surfaces of the protective tubes31A to31F. Particularly, for the inorganic matter such as calcium, solubility is lowered as water temperature increases. Therefore, when the protective tubes31A to31F are heated by heating the ultraviolet lamps30A to30F, calcium and the like are precipitated and attach to the surfaces of the protective tubes31A to31F. In this case, the calcium and the like attaching to the surfaces of the protective tubes31A to31F are called “stains”.

The contaminated surfaces of the protective tubes31A to31F block the irradiation of the water W1with the ultraviolet ray, thereby lowering the disinfecting performance of the ultraviolet irradiation water treatment apparatus10B. In order to avoid the lowered disinfecting performance, it is necessary that the protective tubes31A to31F be cleaned several times a day.

Therefore, in the ultraviolet irradiation water treatment apparatus10B according to the second embodiment, the protective tubes31A to31F are cleaned by physical cleaning in which the surface of the protective tube is scraped with a brush or cleaning ring. Therefore, because the surfaces of the protective tubes31A to31F are always cleaned, the disinfecting performance of the ultraviolet irradiation can be maintained. Chemical cleaning may also be used, which involves cleaning with chemicals.

The attachment (stain) removed by the cleaning is discharged along with the treated water W2. At this point, it is necessary that the concentration of the removed attachment in the treated water be lower than a certain water quality criterion. The requirement can be met by increasing the cleaning frequency.

The ultraviolet irradiation efficiency can also be increased in the absence of plural ultraviolet lamps in the ultraviolet irradiation water treatment apparatus10B. Specifically, an ultraviolet irradiation water treatment apparatus10C can be cited.FIGS. 10 and 11are a side view and a plan view showing the ultraviolet irradiation water treatment apparatus10C.

The ultraviolet irradiation water treatment apparatus10C includes not plural ultraviolet lamps but only one ultraviolet lamp. Even though the ultraviolet irradiation water treatment apparatus10C includes only one ultraviolet lamp, the water W1can be caused to swirl to enhance the ultraviolet irradiation efficiency.

In the ultraviolet irradiation water treatment apparatus10C, because the ultraviolet lamp is disposed on the central axis S of the vessel20, the drive shaft53of the cleaning apparatus50is disposed apart from the central axis S. Therefore, the same action and effect as the installation of the baffle40can be obtained in the case where the drive shaft53is disposed apart from the central axis S.

Third Embodiment

FIG. 12is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10D according to a third embodiment of the invention.

In the ultraviolet irradiation water treatment apparatus10D according to the third embodiment, the vessel of the ultraviolet irradiation water treatment apparatus10according to the first embodiment is modified to include a contaminant recovery mechanism. Specifically, the ultraviolet irradiation water treatment apparatus10D further includes a connection pipe60, a contaminant trap container70, and contaminant recovery piping80.

The vessel20of the ultraviolet irradiation water treatment apparatus10D includes a reversely conical discharge portion25in the lower portion of the side portion21and a connection portion26below the discharge portion25.

The water outlet pipe23is disposed along the central axis S. A lower end23L of the water outlet pipe23is disposed below lower ends of the ultraviolet lamps31A to31F.

The connection pipe60is used to connect the connection portion26of the vessel20and the contaminant trap container70.

The contaminant trap container70is connected to the vessel20through the connection pipe60to accumulate the discharged water W1and a contaminant D contained in the water W1. The contaminant trap container70is disposed below the connection pipe60. Therefore, the connection pipe60can be inserted in and connected to the contaminant trap container70.

The contaminant recovery piping80is used to recover the contaminant D accumulated in the contaminant trap container70. The contaminant D accumulated in the contaminant trap container70can be discharged by opening the contaminant recovery piping80on a recovery date and time.

An action of the ultraviolet irradiation water treatment apparatus10D according to the third embodiment will be described below.

The water W1flows into the vessel20through the water inlet pipe22.

The water W1flowing into the vessel20sequentially flows clockwise near the outer peripheries of the six ultraviolet lamps30A to30F arranged in the circumferential direction of the side portion21.

The water W1flows efficiently from the upper end to the lower end in the central axis direction of the vessel20. That is, the water W1flows downward along the central axis S while swirling spirally in the vessel20. A flow F of the water W1during the swirl is expressed, for example, as shown inFIG. 13.FIG. 13is a sectional view showing the side portion21which is a cylindrical portion.FIG. 14is a view showing a velocity distribution in a flow direction of the ultraviolet lamp30A in a section taken on line1-1′ ofFIG. 13.

As described above, usually the water W1is irradiated with an ultraviolet ray while swirling in the vessel20.

However, due to an accidental impact, sometimes the protective tubes31A to31F are broken and therefore the ultraviolet lamps30A to30F break.

In such cases, fragments of the quartz glass tube constituting the ultraviolet lamps30A to30F and protective tubes31A to31F are mixed into the water W1, or the mercury enclosed in the ultraviolet lamps30A to30F leaks into the water W1. The fragments of the quartz glass tube and the mercury become contaminant D of the water W1.

In comparison with water, which has a specific gravity of 1, the quartz glass tube has a specific gravity of 2.2 and mercury has specific gravity of 13.5. The swirl of the water containing the quartz glass tube and mercury pushes the substance having a larger specific gravity to the outside in the swirling direction by a centrifugal separation action. That is, a centrifugal force is applied to the water by the swirling flow, and heavy substances are separated from the fluid flowing in the vessel20. The separated substances such as glass and mercury reach the inner wall21W of the side portion21, and the substances are collected downward along the inner wall21W by gravitation.

That is, in the ultraviolet irradiation water treatment apparatus10D according to the third embodiment, even if the contaminant D is thoroughly mixed with the water W1, the contaminant D can surely be guided to the contaminant trap container70by the centrifugal separation action caused by the spiral swirling flow of the water W1and gravitation. Therefore, the treated water W2in which the contaminant D is mixed can be prevented from flowing out.

Thus, in the ultraviolet irradiation water treatment apparatus10D according to the third embodiment, the whole body of the water W1can efficiently be irradiated with an ultraviolet ray.

Even if an ultraviolet lamp is broken due to an accidental impact, the contaminant is not mixed into the treated water W2, due to a centrifugal separation action, so that ultraviolet irradiation can be performed safely and surely.

In the event that a part of the ultraviolet lamps30A to30F is broken or turned off, because the water W1flows near all the ultraviolet lamps30A to30F, the water W1can continuously be irradiated with an ultraviolet ray without interrupting the running of the apparatus.

Because the water-purifying facilities always run as a social infrastructure, the water W1always flows into the ultraviolet irradiation water treatment apparatus. In the case where the water W1always flows into the ultraviolet irradiation water treatment apparatus, an ultraviolet lamp and protective tube may break due to the water-hammer action if the contaminant recovery piping80is carelessly opened. The ultraviolet irradiation water treatment apparatus10D according to the third embodiment comprises the contaminant trap container70in which the contaminant D can be tentatively accumulated, so that any breakage of the ultraviolet lamp and protective tube due to water-hammer action can be contained.

In the ultraviolet irradiation water treatment apparatus10D according to the third embodiment, because the need for installing a recovery pond to recover the contaminant is eliminated, the structure of the water-purifying facilities and the like can be simplified. That is, in the ultraviolet irradiation water treatment apparatus10according to the first embodiment, as shown inFIG. 15(A), a recovery pond6is required to recover the contaminant D between a catchment well5and an aggregation and sedimentation pond7. The recovery pond6includes a partition plate6A, and the contaminant D, which does not pass over the partition plate6A, collects at the bottom of the recovery pond6. On the other hand, as shown inFIG. 15(B), since the ultraviolet irradiation water treatment apparatus10D according to the third embodiment includes the contaminant trap container70in which the contaminant D can be tentatively accumulated, the need for installing a recovery pond6can be eliminated.

Fourth Embodiment

FIG. 16is a schematic view showing installation sites of ultraviolet lamps30A and30F of an ultraviolet irradiation water treatment apparatus10E according to a fourth embodiment of the invention.

The ultraviolet irradiation water treatment apparatus10E according to the fourth embodiment differs from the first embodiment and second embodiment in the installation sites of the ultraviolet lamps30A to30F and protective tubes31A to31F.

In the fourth embodiment, a first inner periphery C1is set around the central axis S and a second inner periphery C2is set inside the first inner periphery C1in the vessel20, the first ultraviolet lamps31A,31C, and31E are disposed at equal intervals on the first inner periphery C1, and the second ultraviolet lamps31B,31D, and31F are disposed at equal intervals on the second inner periphery C2. The second ultraviolet lamps31B,31D, and31F are disposed in a certain angular configuration at midpoints between the first ultraviolet lamps31A,31C, and31E respectively.

In other words, three ultraviolet lamps30A,30C, and30E are arranged at equal circumferential angles of 120° as an outer peripheral array. The remaining three ultraviolet lamps30B,30D, and30F are arranged at equal intervals as an inner peripheral array on an inner periphery of a smaller array radius than that of the outer peripheral array, and circumferential angles of the ultraviolet lamps30B,30D, and30F are shifted by 60°.

FIG. 16shows an array method when the six ultraviolet lamps30A to30F are arranged. However the invention is not limited to the array method ofFIG. 16.

An action of the ultraviolet irradiation water treatment apparatus10E according to the fourth embodiment will be described below.

The water W1flows into the vessel20through the water inlet pipe22.

The water W1flowing into the vessel20flows downward along the central axis S while swirling in the vessel20. At this point, the water W1impinges on the first ultraviolet lamp30A in the outer peripheral array, and the water W1passes through the ultraviolet lamp30A while divided onto the side of the inner wall21W and onto the side of the inner periphery C2.

Then, water W1Ao flowing onto the side of the inner periphery C2of the ultraviolet lamp30A impinges on the first ultraviolet lamp30B in the inner peripheral array. Then, the water W1Ao passes through the ultraviolet lamp30B while divided onto the side of the outer periphery C1and onto the side of the central axis S.

Then, water W1Bo flowing onto the side of the outer periphery C1of the ultraviolet lamp30B and water W1Ai flowing onto the side of the inner wall21W of the first ultraviolet lamp30A in the outer peripheral array merge to impinge on the second ultraviolet lamp30C in the outer peripheral array.

Then, similarly, the water W1sequentially flows around the second ultraviolet lamp30D in the inner peripheral array, the third ultraviolet lamp30E in the outer peripheral array, the third ultraviolet lamp30F in the inner peripheral array, and so on.

Thus, in the ultraviolet irradiation water treatment apparatus10E according to the fourth embodiment, the ultraviolet lamps are arrayed in the first inner periphery C1and the second inner periphery C2respectively. Therefore, a retention region where the flow stops between the ultraviolet lamps is not formed, which enables the water W1to flow securely.

That is, a retention region where the flow stops between the ultraviolet lamps is formed in the case where all the ultraviolet lamps30A to30F are arrayed on the same radius. For example, inFIG. 17, a retention region R is formed at the back of the ultraviolet lamp30A along the swirling direction of the water W1. If a retention region is formed, the whole body of the water cannot be evenly irradiated with an ultraviolet ray. In the ultraviolet irradiation water treatment apparatus10E according to the fourth embodiment, compared with the ultraviolet irradiation water treatment apparatus in which the ultraviolet irradiation lamps are arranged on the same circumference, the whole body of the water can be evenly irradiated with an ultraviolet ray to enhance the ultraviolet irradiation efficiency.

In the event that a part of the ultraviolet lamps30A to30F is broken or turned off, because the water W1flows near all the ultraviolet lamps30A to30F, the ultraviolet irradiation treatment can continuously be performed without interrupting the running of the apparatus.

Fifth Embodiment

FIG. 18is a schematic view showing a configuration of an ultraviolet irradiation water treatment apparatus10F according to a fifth embodiment of the invention.FIG. 19is a schematic view showing a configuration of a cleaning apparatus90of the fifth embodiment.

In the ultraviolet irradiation water treatment apparatus10F according to the fifth embodiment, a cleaning apparatus90is incorporated into the ultraviolet irradiation water treatment apparatus10D according to the third embodiment.

The cleaning apparatus90includes a cleaning component91, a moving component92, a drive shaft93, a drive motor94, and a gear-change mechanism95.

The cleaning component91scrapes the protective tubes31A to31F to wash out a stain. As shown inFIG. 20, the cleaning component91includes a first guide vane type cleaning plate91A, a second guide vane type cleaning plate91B, and a coupling component91C.

The first guide vane type cleaning plate91A is a semicircular cleaning plate which is obliquely disposed such that the downstream side of the swirling flow of the water W1is located below the upstream side of the swirling flow. The first guide vane type cleaning plate91A includes three cleaning wipers91D to clean the protective tubes31A to31C.

The second guide vane type cleaning plate91B is a semicircular cleaning plate which is coupled to the first guide vane type cleaning plate91A to form a circular shape and obliquely disposed to cause the water W1to further swirl. The second guide vane type cleaning plate91B is coupled so as to be located below the first guide vane type cleaning plate91A. The second guide vane type cleaning plate91B includes three cleaning wipers91D to clean the protective tubes31D to31F.

The coupling component91C is used to couple the first guide vane type cleaning plate91A and the second guide vane type cleaning plate91B.

The moving component92fixes the cleaning component91to the drive shaft93to support the cleaning component91, and the moving component92moves the cleaning component91along the drive shaft93according to the rotation of the drive shaft93. The moving component92is attached to the first guide vane type cleaning plate91A. The moving component92and the drive shaft93are connected to each other with an external and internal thread structure.

The drive shaft93is provided along the central axis S of the vessel20, and the rotation of the drive shaft93drives the moving component92along the central axis S. Specifically, the thread is processed over the drive region of the drive shaft93, whereby the rotation of the drive shaft93vertically lifts the moving component92having the threaded inner surface. In other words, the drive shaft93and the moving component92are connected with the external and internal thread structure so that the rotational energy of the drive shaft93can be converted into the lifting energy of the moving component92.

The drive motor94is used to rotate the drive shaft93. The drive motor94can be drive-timed. For example, the drive motor94can be set by a built-in timer so as to be driven every 15 minutes.

The gear-change mechanism95is used to change the rotation speed of the drive motor94.

In addition, the cleaning apparatus90includes a guide component96, a guide rail97, fixing plates98A and98B, and bearings99A and98B other than the components in the above described configuration. The guide component96is used to latch the first guide vane type cleaning plate91A and second guide vane type cleaning plate91B in the guide rail97. The bearings99A and99B fix the guide rail97respectively to the fixing plates98A and98B provided in the upper and lower portions of the drive region.

An action of the ultraviolet irradiation water treatment apparatus10F according to the fifth embodiment will be described below.

The drive motor94is driven to rotate the drive shaft93on a previously set date and time or as needed.

Then, the moving component92moves up and down along the central axis S of the vessel20according to the rotation of the drive shaft93. The moving component92is attached to the first guide vane type cleaning plate91A, and the first guide vane type cleaning plate91A and the second guide vane type cleaning plate91B are coupled by the coupling component91C. Therefore, the rotation of the drive shaft93vertically moves the whole cleaning component91.

When the cleaning component91is vertically moved, the cleaning wipers91D are moved while vertically scraping the surfaces of the protective tubes31A to31F. Therefore, the surfaces of the protective tubes31A to31F are cleaned.

Thus, in the ultraviolet irradiation water treatment apparatus10F according to the fifth embodiment, because the cleaning wipers91D are moved while vertically scraping the surfaces of the protective tubes31A to31F, stains can be prevented from adhering to the surface of the protective tube. Examples of the components of stains of the protective tubes31A to31F include organic matter in the water and inorganic matter such as iron, manganese, and calcium.

The cleaning component91according to the fifth embodiment includes the first guide vane type cleaning plate91A and the second guide vane type cleaning plate91B. The first guide vane type cleaning plate91A and the second guide vane type cleaning plate91B are obliquely disposed in the swirling direction of the swirling flow.

Therefore, in the upper portion of the side portion21of the ultraviolet irradiation water treatment apparatus10F, the guide vane type cleaning plates91A and91B are inclined along the line of flow of the spiral swirling flow, so that an increase in flow resistance can be suppressed.

On the other hand, in the lower portion of the ultraviolet irradiation water treatment apparatus10F, sometimes the swirling force of the water W1is weakened by the flow resistance in the upper portion to strengthen the flow rate in the axial direction. In such cases, the guide vane type cleaning plates91A and91B can act as a guide vane to restore the swirling flow.

That is, in the ultraviolet irradiation water treatment apparatus10F, the cleaning apparatus90includes the guide vane type cleaning plates91A and91B, so that an increase in flow resistance can be suppressed in the region where the swirling flow becomes dominant while the swirling flow can be restored in the region where the flow rate in the axial direction becomes dominant. Additionally, stains can be prevented from adhering to the surface of the protective tube. Therefore, effective ultraviolet irradiation can continuously be performed.

Sixth Embodiment

FIG. 21is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10G according to a sixth embodiment of the invention, andFIG. 22is a plan view showing the ultraviolet irradiation water treatment apparatus10G.

In the ultraviolet irradiation water treatment apparatus10G, the water W1is caused to flow in, the water W1is irradiated with the ultraviolet ray, and the treated water W2is caused to flow out.

The ultraviolet lamps30A to30F and the protective tubes31A to31F are disposed in the vessel20of the ultraviolet irradiation water treatment apparatus10G. The contaminant trap container70and the contaminant recovery piping80are disposed below the vessel20.

The vessel20of the ultraviolet irradiation water treatment apparatus10G includes the side portion21, the water inlet pipe22, the water outlet pipe23, the discharge portion25, the connection portion26, and a lid27.

The side portion21includes a cylindrical outer wall and a cylindrical inner wall, and the water inlet pipe22is attached to the side portion21while a part of the outer wall and the inner wall are communicated such that water W1flows in the tangential direction of the inner periphery.

The water inlet pipe22is provided in the tangential direction T of the inner periphery of the side portion21to cause the water W1to flow in.

The water outlet pipe23is provided in the vessel20to cause the treated water W2to flow out. The water outlet pipe23is disposed on the central axis S of the side portion21while piercing through the lid27.

The discharge portion25is provided at a lower end of the side portion21, and the discharge portion25is formed in a reversely truncated conical shape and has a decreased inner diameter at the lower end of the side portion21.

The connection portion26is connected to the contaminant trap container70. The connection portion26is provided at the lower end of the discharge portion25, and the connection portion26is formed in a cylindrical shape having the same inner diameter as that at the lower end of the discharge portion25.

The lid27is a cover which covers the upper end of the side portion21in a watertight manner. The ultraviolet lamps30A to30F and the protective tubes31A to31F are disposed in the back surface of the lid27.

The ultraviolet lamps30A to30F are disposed in parallel with the central axis S of the side portion21. The ultraviolet lamps30A to30F are disposed in the lid27, and the ultraviolet lamps30A to30F are provided at equal intervals on the circumference around the central axis S. Specifically, a quartz tube rod in which the electrodes are attached to both ends is formed in a U-shape and used as the ultraviolet lamp.

The protective tubes31A to31F are made of quartz glass such that the water W1does not directly contact the ultraviolet lamps30A to30F. In this case, the protective tubes31A to31F are separately disposed so as to surround each of the ultraviolet lamps30A to30F.

The guide plate41is attached to a region where an angle formed between the inner wall of the side portion21and the inner wall of the water inlet pipe22is an acute angle. Specifically, the guide plate41is attached such that the interval with the inner wall is gradually increased from the inner peripheral line of the side portion21.

The contaminant trap container70accumulates the water W1and the contaminant D contained in the water W1. Specifically, the contaminant trap container70is disposed below the vessel20, and the connection portion26is inserted into the contaminant trap container70. The contaminant trap container70accumulates the contaminant D which is contained in the water W1discharged from the connection portion26.

The contaminant recovery piping80is used to recover the contaminant D accumulated in the contaminant trap container70. The contaminant D accumulated in the contaminant trap container70can be discharged by opening the contaminant recovery piping80on a recovery date and time.

An action of the ultraviolet irradiation water treatment apparatus10G according to the sixth embodiment will be described below.

The water W1flows into the vessel20through the water inlet pipe22. At this point, the water W1is guided toward the inner wall direction of the vessel20by the guide plate41.

The water W1flowing into the vessel20sequentially flows clockwise near the outer peripheries of the six ultraviolet lamps30A to30F arrayed in the circumferential direction of the side portion21. The water W1flows from the upper end to the lower end in the direction of the central axis S of the vessel20. That is, the water W1flows downward along the central axis S while swirling spirally in the vessel20. The flow F of the water W1during the swirl is expressed as shown inFIG. 22.

The swirling flow reaching the lower end of the discharge portion25becomes an upward flow to rise along the central axis S, and the upward flow is discharged from the water outlet pipe23.

Thus, in the ultraviolet irradiation water treatment apparatus10G according to the sixth embodiment, the water inlet pipe22is attached while a part of the outer wall and the inner wall are communicated such that the water W1flows in along the tangential direction T of the inner wall of the side portion21, so that the water W1can swirl. Accordingly, the water W1can flow while effectively contacting the ultraviolet lamps30A to30F, and the ultraviolet irradiation efficiency can be increased.

Because the ultraviolet irradiation water treatment apparatus10G includes the guide plate41, the water W1can be guided toward the inner wall direction of the side portion21, which allows the direction of inflow dynamic pressure of the water W1to be converted into the swirling direction. Accordingly, a shearing force generated by the inflow dynamic pressure can be relaxed for the ultraviolet lamps30A and30F disposed near the entrance of the water inlet pipe22, and breakage of the ultraviolet lamp30and protective tube31can be prevented.

The ultraviolet irradiation water treatment apparatus10G includes the vessel20having the reversely truncated conical discharge portion25and the contaminant trap container70. Therefore, even if the contaminant D is mixed into the water W1, the contaminant D can surely be guided to the contaminant trap container70by the centrifugal separation action caused by the spiral swirling flow of the water W1and gravity, and the treated water W2in which the contaminant D is mixed can be prevented from flowing out.

Seventh Embodiment

FIG. 23is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10H according to a seventh embodiment of the invention, andFIG. 24is a plan view showing the ultraviolet irradiation water treatment apparatus10H.

In the ultraviolet irradiation water treatment apparatus10H according to the seventh embodiment, the vessel of the ultraviolet irradiation water treatment apparatus10D according to the third embodiment is modified. Specifically, the vessel20includes an inflow portion28and a tapered portion29. The water inlet pipe22is attached not to the side portion21but to the inflow portion28.

The inflow portion28includes a cylindrical outer wall and a cylindrical inner wall, and the water inlet pipe22is attached to the inflow portion28while a part of outer wall and the inner wall are communicated such that the water W1flows in the tangential direction T of the inner wall.

The tapered portion29having the reversely truncated conical shape is provided at the lower end of the inflow portion28. In the tapered portion29, the diameter of the inflow portion28is gradually decreased to the diameter of the side portion21. That is, the inner diameter at the upper end of the tapered portion29is equal to the inner diameter of the inflow portion28and the inner diameter at the lower end is equal to the inner diameter of the side portion21.

An action of the ultraviolet irradiation water treatment apparatus10H according to the seventh embodiment will be described below.

The water W1flows into the vessel20through the water inlet pipe22. At this point, because there is no ultraviolet lamp30A in the inflow direction of the water W1, a swirling flow is effectively generated while the flow of the water W1is not blocked by the ultraviolet lamp30A.

The water W1of the swirling flow swirls in the tapered portion29while being brought close to the ultraviolet lamps30A to30F. Then, the water W1flows to the lower end of the discharge portion25while swirling near the outer peripheries of the ultraviolet lamps30A to30F in the side portion21.

The swirling flow reaching the lower end of the discharge portion25becomes the upward flow, the upward flow rises along the central axis S, and the upward flow is discharged from the water outlet pipe23.

Thus, the ultraviolet irradiation water treatment apparatus10H according to the seventh embodiment includes the inflow portion28whose inner diameter is larger than the inner diameter of the side portion21, so that the contact between the water W1and the ultraviolet lamp30A can be reduced immediately after the water W1flows in the inflow portion28. Because there is no ultraviolet lamp30A in the inflow direction of the water W1, the swirling flow is effectively generated while the flow of the water W1is not blocked by the ultraviolet lamp30A.

The distance between the ultraviolet lamp30and the swirling flow is gradually decreased in the tapered portion29, and the water W1swirls near the ultraviolet lamp30in the side portion21. Therefore, the ultraviolet irradiation effect can be enhanced.

Because the contact between the water W1and the ultraviolet lamp30A is reduced immediately after the water W1flows in the inflow portion28, the shearing force generated by the inflow dynamic pressure can be relaxed for the ultraviolet lamp30A and protective tube31A near the entrance of the water inlet pipe22.

Eighth Embodiment

FIG. 25is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10I according to an eighth embodiment of the invention, andFIG. 26is a plan view showing the ultraviolet irradiation water treatment apparatus10I.

In the ultraviolet irradiation water treatment apparatus10I according to the eighth embodiment, cover components32A to32F are added to the ultraviolet irradiation water treatment apparatus10H according to the seventh embodiment.

The cover components32A to32F are used to protect the protective tubes31A to31F in the inflow portion28respectively, and the cover components32A to32F are made of a metal such as iron or stainless steel. The cover components32A to32F are disposed in the vessel side of the lid27.

As described above, the ultraviolet irradiation water treatment apparatus10I includes the cover components32A to32F disposed in the outer peripheries of the protective tubes31A to31F, so that the direct action of the inflow dynamic pressure of the water W1on the protective tubes31A to31F can be relaxed. That is, because the inflow dynamic pressure of the water W1indicates a high value immediately after the water W1flows in the inflow portion28, sometimes it is necessary for the ultraviolet lamps30A to30F in the inflow portion28to be firmly protected rather than the protective tubes31A to31F made of quartz glass. In such cases, breakage of the ultraviolet lamps30A to30F and protective tubes31A to31F can be prevented by including the cover components32A to32F made of metal.

Ninth Embodiment

FIG. 27is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10J according to a ninth embodiment of the invention, andFIG. 28is a plan view showing the ultraviolet irradiation water treatment apparatus10J.

In the ultraviolet irradiation water treatment apparatus10J according to the ninth embodiment, a cover skirt33is added to the ultraviolet irradiation water treatment apparatus10H according to the seventh embodiment.

The cover skirt33is a cylindrical component which is disposed below the lid27so as to surround all the protective tubes31A to31F in the inflow portion28. The cover skirt33is made of a metal such as iron, aluminum, or stainless steel.

Therefore, similarly to the ultraviolet irradiation water treatment apparatus10I according to the eighth embodiment, breakage of the ultraviolet lamps30A to30F and protective tubes31A to31F can be prevented.

Additionally, a ring-shape flow path is formed by the outer peripheral surface of the cover skirt33and the inner wall of the inflow portion28. Therefore, compared with the ultraviolet irradiation water treatment apparatus10I in which the cover components32A to32F are separately attached to the protective tubes31A to31F, the water W1can be guided toward the inner wall direction of the inflow portion28, and the swirling flow can efficiently be generated.

Tenth Embodiment

FIG. 29is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10K according to a tenth embodiment of the invention, andFIG. 30is a plan view showing the ultraviolet irradiation water treatment apparatus10K.

In the ultraviolet irradiation water treatment apparatus10K according to the tenth embodiment, a recess portion27H is added to the lid27of the ultraviolet irradiation water treatment apparatus10H according to the seventh embodiment. The recess portion27H recessed in a cylindrical shape so as to push down all the whole ultraviolet lamps30A to30F. In this case, the recess portion27H pushes down the lid27by a height of the inflow portion28.

In the ultraviolet irradiation water treatment apparatus10K according to the tenth embodiment having the above-described configuration, the heights of the ultraviolet lamps30A to30F can be decreased compared with the ultraviolet irradiation water treatment apparatus10J according to the ninth embodiment. Similarly to the ultraviolet irradiation water treatment apparatus10J according to the ninth embodiment, the ring-shape flow path is formed by the outer peripheral surface of the recess portion27H and the inner wall of the inflow portion28, so that the swirling flow can efficiently be generated.

A terminal box is disposed in the recess portion27H to accommodate connection terminals of electric wires through which electric power is supplied to the ultraviolet lamps30A to30F, whereby the height of the whole of the apparatus can be decreased. As described in the first embodiment, the decrease in height of the apparatus is a necessary factor in introducing the ultraviolet irradiation water treatment apparatus to existing water-purifying facilities.

The irradiation efficiency of the ultraviolet lamps30A to30F can also be increased. More specifically, due to the presence of the emission portions of the ultraviolet lamps30A to30F from the tapered portion29to the side portion21, the treated fluid W1flows closer to the ultraviolet lamp compared with the case of the inflow portion28. Accordingly, the treated fluid W1is irradiated with a strong ultraviolet ray to enhance the irradiation efficiency.

Eleventh Embodiment

FIG. 31is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10L according to an eleventh embodiment of the invention, andFIG. 32is a plan view showing the ultraviolet irradiation water treatment apparatus10L.

In the ultraviolet irradiation water treatment apparatus10L according to the eleventh embodiment, a first guide fin42and a second guide fin43are added to the ultraviolet irradiation water treatment apparatus10K according to the tenth embodiment.

The first guide fin42is a downward spiral plate, and the first guide fin42is attached to the inner wall of the inflow portion28.

The second guide fin43is a downward spiral plate, and the second guide fin43is attached to the outer wall of the recess portion27H.

In the above-described configuration, in the inflow portion28, the water W1is guided to the first guide fin42and second guide fin43, and the water W1flows while swirling downward. That is, the swirling flow can efficiently be generated. Accordingly, even if the ultraviolet lamps30A to30F or the protective tubes31A to31F are broken, the fragments of the broken glass or the liquid mercury can be guided to the lowermost contaminant trap container70by the centrifugal separation action.

Alternatively, a spiral pitch Po of the first guide fin42and a spiral pitch Pi of the second guide fin43are gradually narrowed in the flow direction, and an angle of lead of the first guide fin42may be larger than an angle of lead of the second guide fin43. Accordingly, because the swirling flow rate is accelerated in the flow direction, the centrifugal separation force can be improved. The “angle of lead” shall mean an angle formed by a tangent of the spiral line in the cylinder and a plane perpendicular to the axis.

Both the first guide fin42and the second guide fin43are attached in the eleventh embodiment. However, the same effect is also obtained only by one of the first guide fin42and the second guide fin43. The same effect is obtained by a spiral guide fin, in which the first guide fin42and the second guide fin43, are integrally coupled. That is, a combination of the first guide fin42and the second guide fin43and a method of fixing the first guide fin42and the second guide fin43are not limited thereby.

Twelfth Embodiment

FIG. 33is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10M according to a twelfth embodiment of the invention, andFIG. 34is a plan view showing the ultraviolet irradiation water treatment apparatus10M.

The ultraviolet irradiation water treatment apparatus10M according to the twelfth embodiment includes a side portion21S having a reversely truncated conical shape instead of the cylindrical side portion21in the vessel20of the ultraviolet irradiation water treatment apparatus10K according to the tenth embodiment.

As described above, the side portion21S is formed in the reversely truncated conical shape and a sectional area is gradually decreased toward the downward direction. Therefore, the flow rate is gradually accelerated in the swirling flow of the water W1. Accordingly, even if the contaminant D such as a glass fragment and mercury flows out due to the breakage of the ultraviolet lamps30A to30F or protective tubes31A to31F, the contaminant D can be recovered in the lower portion by the increased centrifugal separation force. That is, the recovery efficiency of the contaminant D can be increased.

In the case of no need for enhancing the recovery efficiency of the contaminant D, the height of the discharge portion25can be decreased. In this case, the height of the whole of the apparatus can be decreased.

Thirteenth Embodiment

FIG. 35is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10N according to a thirteenth embodiment of the invention, andFIG. 36is a plan view showing the ultraviolet irradiation water treatment apparatus10N.

In the ultraviolet irradiation water treatment apparatus10N according to the thirteenth embodiment, the lower end23L of the water outlet pipe in the ultraviolet irradiation water treatment apparatus10K according to the tenth embodiment is disposed above the lower ends of the ultraviolet lamps30A to30F. Specifically, the lower end23L of the water outlet pipe is at a height of half of each of the ultraviolet lamps30A to30F.

An action of the ultraviolet irradiation water treatment apparatus10N according to the thirteenth embodiment will be described below with reference toFIGS. 37 and 38.FIG. 37is a view showing a flow of the water W1in the ultraviolet irradiation water treatment apparatus10K, andFIG. 38is a view showing a flow of the water W1in the ultraviolet irradiation water treatment apparatus10N.

As shown inFIG. 37, in the case where the lower end23L of the water outlet pipe is located at the same height as the lower end of the ultraviolet lamp (lower end of the side portion21) or below the lower end of the ultraviolet lamp, because the water outlet pipe23becomes a shielding substance, the spiral angle (angle of lead) of the swirling flow is increased. Accordingly, the retention region R (left inFIG. 37) is generated in a region on the inflow side of the water W1to decrease the ultraviolet irradiation efficiency.

On the other hand, as shown inFIG. 38, in the case where the lower end23L of the water outlet pipe is located above the lower end of the ultraviolet lamp, because the swirling flow has a small spiral angle (angle of lead), a retention region R is not generated in the side portion21.

Thus, in the ultraviolet irradiation water treatment apparatus10N according to the thirteenth embodiment, the lower end23L of the water outlet pipe is located above the lower ends of the ultraviolet lamps30A to30F, so that retention region R can be prevented from being generated in the side portion21. That is, the water W1can swirl efficiently in the whole region of the vessel20to enhance the ultraviolet irradiation efficiency.

Additionally, the upward flow going upward from the discharge portion25is also irradiated with the ultraviolet ray, so that the ultraviolet irradiation efficiency can be increased.

Fourteenth Embodiment

FIG. 39is a side view showing a configuration of an ultraviolet irradiation water treatment apparatus10P according to a fourteenth embodiment of the invention, andFIG. 40is a plan view showing the ultraviolet irradiation water treatment apparatus10P.

In the ultraviolet irradiation water treatment apparatus10P according to the fourteenth embodiment, an outflow portion45and a water discharge pipe46are added to the ultraviolet irradiation water treatment apparatus10N according to the thirteenth embodiment.

The cylindrical outflow portion45is provided below the cover skirt27in a watertight manner, and the outflow portion45is coupled to the water outlet pipe23in the bottom surface thereof.

The water discharge pipe46is provided in the outer wall of the outflow portion45so as to pierce through the inflow portion21, and the water discharge pipe46is used to discharge the treated water W2from the water outlet pipe23. In this case, the discharge pipe46is attached in the direction orthogonal to the central axis S.

The protective tubes31A to31F including the ultraviolet lamps30A to30F therein are covered with the cover components32A to32F, and the protective tubes31A to31F are fixed to an upper-end tube plate flange.

Thus, in the ultraviolet irradiation water treatment apparatus10P according to the fourteenth embodiment, the discharge pipe46can be attached in the direction orthogonal to the central axis S. Therefore, the height of the whole of the apparatus can be decreased. Therefore, a space in the upper portion of the apparatus is increased, and the ultraviolet lamps30A to30F are easily drawn out and exchanged when the ultraviolet lamps30A to30F have broken down.