Fluid processing apparatus having multiple rectifying plates

A fluid processing apparatus includes: a casing having a fluid inlet pipe and a fluid outlet pipe; multiple rectifying plates with holes in parallel with each other provided within the casing on a side of the fluid inlet pipe, the rectifying plates being perpendicular to a longitudinal axis of the casing; and a light source for irradiating fluid passing from the fluid inlet pipe through the casing to the fluid outlet pipe with ultraviolet rays.

This application claims the priority benefit under 35 U.S.C. § 119 to Japanese Patent Application No. JP2018-027757 filed on Feb. 20, 2018, which disclosure is hereby incorporated in its entirety by reference.

BACKGROUND

Field

The presently disclosed subject matter relates to a fluid processing apparatus using ultraviolet rays.

Description of the Related Art

Generally, a fluid processing apparatus using ultraviolet rays with a short wavelength of about 240 to 380 nm is used as a fluid sterilizer, a fluid disinfector, a fluid purifier and so on.

A first prior art fluid processing apparatus is constructed by a casing serving as a fluid passage along its longitudinal axis direction, a light source for irradiating fluid within the fluid passage with ultraviolet rays, and a hollow fiber membrane filter provided within the casing on the upstream side thereof for changing the fluid stream from a turbulence flow state to a laminar flow state (see: JP2017-87104A). Therefore, fluid in the laminar flow state can be irradiated uniformly with ultraviolet rays, thus enhancing the processing efficiency of fluid.

In the above-described first prior art fluid processing apparatus, however, when the hollow fiber membrane filter is clogged due to aging, the laminar flow rate of fluid is non-uniform, so that the processing efficiency of the fluid processing apparatus would deteriorate.

A second prior art fluid processing apparatus is constructed by a single rectifying plate with small holes instead of the hollow fiber membrane filter of the first prior art fluid processing apparatus (see: JP2017-51290A). Therefore, the fluid stream is also changed by the single rectifying plate from a turbulence flow state to a laminar flow state, thus enhancing the processing efficiency of the fluid processing apparatus.

In the above-described second prior art fluid processing apparatus, although the flow rate of fluid in the proximity of the inner face of the casing is relatively small, the flow rate of fluid in the center of the casing is relatively large, so that the fluid flowing through the center of the casing would not be sufficiently irradiated with ultraviolet rays.

SUMMARY

The presently disclosed subject matter seeks to solve one or more of the above-described problems.

According to the presently disclosed subject matter, a fluid processing apparatus includes: a casing having a fluid inlet pipe and a fluid outlet pipe; multiple rectifying plates with holes in parallel with each other provided within the casing on a side of the fluid inlet pipe, the rectifying plates being perpendicular to a longitudinal axis of the casing; and a light source for irradiating fluid passing from the fluid inlet pipe through the casing to the fluid outlet pipe with ultraviolet rays.

According to the presently disclosed subject matter, since there are multiple rectifying plates, fluid passed through the multiple rectifying plates can become in a laminar flow state whose average flow rate is low, so that the fluid would be equally irradiated with ultraviolet rays.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1is a perspective view illustrating a first embodiment of the fluid processing apparatus according to the presently disclosed subject matter, andFIG. 2is a longitudinal cross-sectional view taken along the line II-II inFIG. 1.

InFIGS. 1 and 2, the fluid processing apparatus is constructed by a cylindrical casing1for passing fluid to be processed therethrough and a light-emitting diode (LED) accommodating chamber2adhered to an aperture1cof the casing1on the downstream side. The casing1and the LED accommodating chamber2are partitioned by an ultraviolet transmitting window3which is mounted on the aperture1cof the casing1.

The casing1is a cylindrical straight pipe made of stainless, Teflon (trademark) resin or the like having an inner diameter of 134 mm, for example, and an outer diameter of 140 mm, for example, and is about 580 mm long. The casing1is provided with a fluid inlet pipe1aon the upstream side whose diameter is 43 mm, for example, and fluid outlet pipes1b-1and1b-2on the downstream side whose diameter is 43 mm, for example. The flow rate of fluid passing from the fluid inlet pipe1athrough the casing1to the fluid outlet pipes1b-1and1b-2is about 100 L/min.

Perpendicularly fixed in the LED accommodating chamber2is a substrate21where multiple LED elements (light source)22are mounted to emit ultraviolet rays with a short wavelength of 240 to 380 nm for sterilization, disinfection, and purification and so on. In this case, the ultraviolet rays emitted from the LED elements22are substantially in parallel with the longitudinal axis of the casing1.

The substrate21is made of heat-dissipating metal such as copper and aluminum, and the power of the LED elements22is supplied from the substrate21. Note that a heat sink or heat-dissipating fins made of aluminum or the like can be provided on the back of the substrate21. Also, a reflector with a rotating parabolic mirror can be provided to guide the ultraviolet rays from the LED elements22to the casing1.

The ultraviolet rays emitted from the LED elements22pass through the ultraviolet transmitting window3to an ultraviolet irradiating chamber12of the casing1. The ultraviolet transmitting window3is made of quartz, sapphire, fluoric resin or the like. Note that a convex lens can be provided between the LED elements22and the ultraviolet transmitting window3to converge the distribution of ultraviolet rays from the LED elements22. Thus, the processing effect such as the sterilizing effect, the disinfecting effect, the purifying effect and so on can be enhanced.

Further, rectifying plates41and42made of metal or fluoric resin such as perfluoro-alkoxy-alkane (PFA) or perfluoro-ethilene-propene-copolymer (FEP) are provided on the upstream side in a rectifying chamber11of the casing1. The rectifying plates41and42, which are distant from each other by about 45 mm, are perpendicular to the longitudinal axis of the casing1. Therefore, the casing1is divided into the rectifying chamber11and the ultraviolet ray irradiating chamber12separated by the rectifying plate42. The rectifying plates41and42within the rectifying chamber11are operated so as to make the flow rate within the ultraviolet ray irradiating chamber12lower and more uniform, so that the fluid would be uniformly irradiated with ultraviolet rays from the LED elements22and the average ultraviolet ray irradiation amount would be higher. In this case, the fluid in the rectifying chamber11is also irradiated with ultraviolet rays from the LED elements22, if the rectifying plates41and42are made of fluoric resin such as PFA or FEP for passing ultraviolet rays.

The rectifying plates41and42ofFIG. 2are explained in detail with reference toFIGS. 3A and 3B, respectively.

As illustrated inFIG. 3A, which is a front view of the rectifying plate41, the rectifying plate41is circular with a center coinciding with the center axis of the casing1, so that the rectifying plate41can be internally contacted at the inner face of the casing1. The rectifying plate41has a large number of holes41awhose diameter d1is about 5 mm.

As illustrated inFIG. 3B, which is a front view of the rectifying plate42, the rectifying plate42is circular with a center coinciding with the center axis of the casing1, so that the rectifying plate42can be internally contacted at the inner face of the casing1. The rectifying plate42has a large number of holes42awhose diameter d2is about 2 mm.

Also, the aperture rate of the holes42ain the rectifying plate42is smaller than that of the holes41ain the rectifying plate41, i.e.,
d1·n1/S1>d2·n2/S2(S1=S2)

where n1is the density of the holes41ain the rectifying plate41;S1is the area of the rectifying plate41;n2is the density of the holes42ain the rectifying plate42; andS2is the area of the rectifying plate42.

Since the aperture rate of the holes42ais smaller than that of the holes41a, the fluid resistance of the rectifying plate42is larger than that of the rectifying plate41, so that a rectifying operation would be performed upon the fluid passed through the rectifying plate41. Thus, the laminar effect of the fluid would be further enhanced.

Note that, if the aperture rate of the holes42ain the rectifying plate42is larger than that of the holes41ain the rectifying plate41, the fluid in a small turbulence flow rate passed through the rectifying plate41would easily pass through the rectifying plate42, so that the laminar state of the fluid passed through the rectifying plate42would be insufficient.

InFIG. 4, which shows a simulated flow rate of fluid in the fluid processing apparatus ofFIGS. 1, 2 and 3, assume that the flow rate of fluid at the fluid inlet pipe1ais 1.20 m/s. In this case, although the flow rate of fluid immediately before the rectifying plate41is high, i.e., 0.65 m/s (=54%), the flow rate of fluid between the rectifying plates41and42is low, i.e., 0.20 to 0.30 ms (=17 to 25%). Also, the flow rate of fluid between the rectifying plate42and the fluid outlet pipes1b-1and1b-2in the ultraviolet ray irradiating chamber12is lower, i.e., 0.10 to 0.15 m/s (=8 to 12%). Also, the flow rate of fluid at the fluid outlet pipes1b-1and1b-2is 0.75 m/s (=60%). Thus, the laminar flow rate of fluid in the ultraviolet ray irradiating chamber12of the casing1is very low and uniform.

Contrary to this, inFIG. 5, which shows a simulated flow rate of fluid in a fluid processing apparatus similar to the above-described second prior art fluid processing apparatus where only the rectifying plate41is provided while the rectifying plate42is not provided, assume that the flow rate of fluid at the fluid inlet pipe1ais 1.20 m/s. In this case, the flow rate of fluid immediately before the rectifying plate41is also 0.65 m/s (=54%). However, the flow rate of fluid between the rectifying plate41and the fluid outlet pipes1b-1and1b-2is 0.10 to 0.45 m/s (=8 to 38%). In more detail, the flow rate of fluid in proximity to the inner face of the casing1is 0.10 (=8%), while the flow rate of fluid at the center of the casing1is 0.40 to 0.45 m/s (=33 to 38%). Also, the flow rate of fluid at the fluid outlet pipes1b-1and1b-2is 0.75 m/s (=60%). Thus, the laminar flow rate of fluid in the ultraviolet ray irradiating chamber12of the casing1is 0.10 to 0.45 (=8 to 38%), and therefore, it is neither low nor uniform.

Thus, the fluid processing efficiency is more excellent in the fluid processing apparatus ofFIGS. 1, 2 and 3where two rectifying plates are provided than in the fluid processing apparatus where a single rectifying plate is provided.

InFIG. 6, which illustrates a modification of the fluid processing apparatus ofFIG. 2, a rectifying plate43is inserted between the rectifying plates41and42ofFIG. 2. The rectifying plate43, which is also made of metal or fluoric resin, is perpendicular to the longitudinal axis of the casing1to further make the flow rate within the ultraviolet ray irradiating chamber12of the casing1lower and more uniform.

As illustrated inFIG. 7B, which is a front view of the rectifying plate43, the rectifying plate43is circular with a center coinciding with the center axis of the casing1, so that the rectifying plate43can be internally touched at the inner face of the casing1. The rectifying plate43has a large number of holes43awhose diameter d3is about 3.5 mm.

Also, the aperture rate of the holes43ain the rectifying plate43is smaller than that of the holes41ain the rectifying plate41and larger than the holes42aof the rectifying plate42, i.e.,
d1·n1/S1>d3·n3/S3>d2·n2/S2(S1=S3=S2)

where n3is the density of the holes43ain the rectifying plate43; and

S3is the area of the rectifying plate43.

Since the aperture rate of the holes43ais smaller than that of the holes41aand larger than the holes42a, the fluid resistance of the rectifying plate43is larger than that of the rectifying plate41and smaller than that of the rectifying plate42, so that a rectifying operation by the rectifying plate43would be performed upon the fluid passed through the rectifying plate41. Thus, the laminar effect of the fluid would be further enhanced.

In the first embodiment, the diameters of the holes in the rectifying plates can be the same as illustrated inFIGS. 8A and 8B, which illustrate modifications ofFIGS. 3A and 3B, respectively. InFIGS. 8A and 8B, the diameter d1of the holes41ain the rectifying plate41is the same as the diameter d2of the holes42ain the rectifying plate42, i.e., d1=d2=d. InFIGS. 8A and 8B, n1>n2is satisfied, so that the aperture rate of the holes42ain the rectifying plate42is smaller than that of the holes41ain the rectifying plate41. Also, the densities of the holes in the rectifying plates can be the same as illustrated inFIGS. 9A and 9B, which illustrate modifications ofFIGS. 3A and 3B, respectively. InFIGS. 9A and 9B, the density n1of the holes41ain the rectifying plate41is the same as the density n2of the holes42ain the rectifying plate42, i.e., n1=n2=n. InFIGS. 9A and 9B, d1>d2is satisfied, so that the aperture rate of the holes42ain the rectifying plate42is smaller than that of the holes41ain the rectifying plate41. In any case, d1·n1/S1>d2·n2/S2is satisfied.

Generally, in the first embodiment, multiple rectifying plates with holes can be provided in the rectifying chamber11. In this case, when a first one of the rectifying plates is closer to the fluid inlet pipe1athan a second one of the rectifying plates, the aperture rate of the holes in the second rectifying plate is smaller than that in the first rectifying plate.

FIG. 10is a perspective view illustrating a second embodiment of the fluid processing apparatus according to the presently disclosed subject matter, andFIG. 11is a longitudinal cross-sectional view taken along the line XI-XI inFIG. 10.

InFIGS. 10 and 11, the casing1has an inner diameter of 133 mm, for example, and an outer diameter of 139 mm, for example, and is about 560 mm long, a little shorter than 580 mm. The casing1is provided with a fluid inlet pipe1aon the upstream side whose diameter is 35 mm, for example, and a fluid outlet pipe1bon the downstream side whose diameter is 35 mm, for example. The flow rate of fluid passed from fluid inlet pipe1athrough the casing1to the fluid outlet pipe1bis about 100 L/min.

Further, rectifying plates51and52made of metal or fluoric resin such as PFA or FEP are provided on the upstream side in a rectifying chamber11′ of the casing1. The rectifying plates51and52, which are distant from each other by about 45 mm, are perpendicular to the longitudinal axis of the casing1. Therefore, the casing1is divided into the rectifying chamber11′ and the ultraviolet ray irradiating chamber12separated by the rectifying plate52. The rectifying plates51and52within the rectifying chamber11′ are operated so as to make the flow rate within the ultraviolet ray irradiating chamber12lower and more uniform, so that the fluid would be uniformly irradiated with ultraviolet rays from the LED elements22and the average ultraviolet ray irradiation amount would be lower. In this case, the fluid in the rectifying chamber11′ can be also irradiated with ultraviolet rays, if the rectifying plates51and52are made of PFA or FEP.

The rectifying plates51and52ofFIG. 11are explained in detail with reference toFIGS. 12A and 12B, respectively.

As illustrated inFIG. 12A, which is a front view of the rectifying plate51, the rectifying plate51is circular with a center coinciding with the center axis of the casing1, so that the rectifying plate51can be internally contacted at the inner face of the casing1. The rectifying plate51has a large number of holes51awhose diameter d1is about 5 mm and a fluid stream suppressing circular section51bat the center surrounded by the holes51a. The diameter of the fluid stream suppressing circular section51bis not smaller than the fluid inlet pipe1a, i.e., 35 to 40 mm.

As illustrated inFIG. 12B, which is a front view of the rectifying plate52, the rectifying plate52is circular with a center coinciding with the center axis of the casing1, so that the rectifying plate52can be internally contacted at the inner face of the casing1. The rectifying plate52has a large number of holes52awhose diameter d2is about 2 mm and a fluid stream suppressing ring-shaped section52bon the periphery surrounding the holes52a.

Also, the aperture rate of the holes52ain the rectifying plate52is smaller than that of the holes51ain the rectifying plate51, i.e.,
d1·n1/S1>d2·n2/S2
where n1is the density of the holes51ain the rectifying plate51except for the fluid stream suppressing circular section51b; and

S1is the area of the holes51a;n2is the density of the holes52ain the rectifying plate52except for the fluid stream suppressing ring-shaped section52b; and

S2is the area of the holes52a.

Since the aperture rate of the holes52ain the rectifying plate52is smaller than that of the holes51ain the rectifying plate51, the fluid resistance of the rectifying plate52is larger than that of the rectifying plate51, so that a rectifying operation would be performed upon the fluid passed through the rectifying plate51. Thus, the laminar effect of the fluid would be further enhanced.

The fluid stream of the fluid processing apparatus ofFIGS. 10, 11, 12A and 12Bis explained next with reference toFIG. 13.

As illustrated inFIG. 13, fluid is supplied from the fluid inlet pipe1ato collide with the fluid stream suppressing circular section51bof the rectifying plate51, so that the fluid would be stirred between the fluid inlet pipe1aand the rectifying plate51by the fluid stream suppressing circular section51bthereof. Then, the fluid passes through the holes51aof the rectifying plate51to collide with the fluid stream suppressing ring-shaped section52bof the rectifying plate52, so that the fluid would be stirred between the rectifying plates51and52by the fluid stream suppressing ring-shaped section52bof the rectifying plate52. Finally, the fluid passes through the holes52aof the rectifying plate52into the ultraviolet ray irradiating chamber12of the casing1irradiated with ultraviolet rays from the LED elements22. In this case, the fluid stream within the ultraviolet ray irradiating chamber12is in a laminar flow rate state whose flow rate is lower and more uniform as compared with the first embodiment as illustrated inFIGS. 1, 2 and 3. Since the ultraviolet rays emitted from the LED elements22are substantially in parallel with the longitudinal axis of the casing1, the fluid would be equally irradiated with the ultraviolet rays from the LED elements22, which is explained with reference toFIG. 14.

InFIG. 14, assume that 3000 fluid particles at10L/min supplied to the casing1were observed by simulation while the fluid particles were irradiated with ultraviolet rays of28J from the LED elements22. In this case, the average dose energy EAVEwas large, i.e., 20.1 mJ/cm2.

Contrary to this, inFIG. 15, which the dose energy characteristics of a fluid processing apparatus where no rectifying plates are provided, under the above-mentioned same condition, the average dose energy EAVEwas small, i.e., 16.4 mJ/cm2.

InFIG. 16A, which is a first modification of the fluid processing apparatus ofFIG. 11, a rectifying chamber11′A is constructed by a rectifying plate51A smaller than the rectifying plate51ofFIG. 11having the holes51aand the fluid stream suppressing circular section51b, a rectifying plate52A similar to the rectifying plate52ofFIG. 11having the holes52aand the fluid stream suppressing ring-shaped section52b, and a coupling section such as a cylindrical section53A made of metal or fluoric resin with no holes coupled between the external circumference of the rectifying plate52A and the fluid stream suppressing ring-shaped section52bof the rectifying plate52A. In this case, the rectifying plate52A is in parallel with the rectifying plate52B by the cylindrical section53A, and the center of the rectifying plate52A is coincident with that of the rectifying plate52B by the cylindrical section53A.

When the rectifying plates51A and52A with the cylindrical section53A are mounted within the casing1, only the rectifying plate52A is contacted internally at the inner face of the casing1without contacting the rectifying plate51A at the inner face of the casing1, thus simplifying an assembling operation of the rectifying chamber11′A.

In the fluid processing apparatus ofFIG. 16A, fluid at a high flow rate passes along the inner face of the casing1outside the rectifying plate51A around the cylindrical section53A to coincide with the fluid stream suppressing ring-shaped section52bof the rectifying plate52A. Thus, the high flow rate of fluid can be mitigated.

InFIG. 16B, which is a second modification of the fluid processing apparatus ofFIG. 11, a rectifying chamber11′ B is constructed by a sloped (cone-shaped) cylindrical section53B with no holes instead of the cylindrical section53A ofFIG. 16A.

In the fluid processing apparatus ofFIG. 16B, more fluid at a high flow rate passes along the inner face of the casing1outside the rectifying plate51A around the cone-shaped cylindrical section53B to coincide with the fluid stream suppressing ring-shaped section52bof the rectifying plate52A. Thus, the high flow rate of fluid can be further mitigated.

InFIG. 16C, which is a third modification of the fluid processing apparatus ofFIG. 11, a rectifying chamber11′C is further constructed by a rectifying plate54with holes54ainserted between the rectifying plates51A and52A within the cylindrical section53A ofFIG. 16A. The rectifying plate54, which is also made of metal or fluoric resin, is in parallel with the rectifying plates51A and52A to further make the flow rate of fluid within the rectifying chamber11′C in a laminar flow state.

Also, the aperture rate of the holes54aof the rectifying plate54is smaller than that of the holes51aof the rectifying plate51A and larger than that of the holes52aof the rectifying plate52. Thus, the fluid resistance of the rectifying plate54is larger than that of the rectifying plate51A and smaller than that of the rectifying plate52A, thus further enhancing the laminar effect.

InFIG. 16C, a fluid stream suppressing ring-shaped section can be provided on the periphery of the rectifying plate54to further make the flow rate of fluid within the rectifying chamber11′C more uniform.

InFIGS. 16A, 16B and 16C, the cylindrical section53A can be replaced by three or more slender columns or plates.

In the second embodiment, the diameters of the holes in the rectifying plates can be the same as illustrated inFIGS. 17A and 17B, which illustrate modifications ofFIGS. 12A and 12B, respectively. InFIGS. 17A and 17B, the diameter d1of the holes51ain the rectifying plate51is the same as the diameter d2of the holes52ain the rectifying plate52, i.e., d1=d2=d. InFIGS. 17A and 17B, n1>n2is satisfied, so that the aperture rate of the holes52ain the rectifying plate52is smaller than that of the holes51ain the rectifying plate51. Also, the densities of the holes in the rectifying plates can be the same as illustrated inFIGS. 18A and 18B, which illustrate modifications ofFIGS. 12A and 12B, respectively. InFIGS. 18A and 18B, the density n1of the holes51ain the rectifying plate51is the same as the density n2of the holes52ain the rectifying plate52, i.e., n1=n2=n. InFIGS. 18A and 18B, d1>d2is satisfied, so that the aperture rate of the holes52ain the rectifying plate52is smaller than that of the holes51ain the rectifying plate51. In any case, d1·n1/S1>d2·n2/S2is satisfied.

Generally, also in the second embodiment, multiple rectifying plates with holes can be provided in the rectifying chamber11. In this case, when a first one of the rectifying plates is closer to the fluid inlet pipe1athan a second one of the rectifying plates, the aperture rate of the holes in the second rectifying plate is smaller than that in the first rectifying plate.

Also, in the above-described embodiments, the LED accommodating chamber2including the LED elements22(light source) is provided at the downstream side of the casing1. However, the LED elements22can be provided at the upstream side of the casing1as illustrated inFIG. 19. InFIG. 19, the rectifying plates41and42are made of PFA or FEP for passing ultraviolet rays therethrough.

Further, in the above-described embodiments, the casing1is of a straight pipe type. However, the casing1can be of a cone shape type where the farther the distance from the LED accommodating chamber2, the larger the diameter of the casing1, as illustrated inFIG. 20. As a result, the fluid in the casing1can be sufficiently irradiated with diverged ultraviolet rays from the LED elements22(light source).

Still further, the cross section of the casing1can be circular or polygonal, as illustrated inFIGS. 21A and 21B.

It will be apparent to those skilled in the art that various modifications and variations can be made in the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter. Thus, it is intended that the presently disclosed subject matter covers the modifications and variations of the presently disclosed subject matter provided they come within the scope of the appended claims and their equivalents. All related or prior art references described above and in the Background section of the present specification are hereby incorporated in their entirety by reference.