Device for TOC reduction in ultrapure water

Abstract

To provide a device for reducing TOC in ultrapure water. [Solution] To reduce TOC by UV radiation in the production of ultrapure water, a cylindrical UV reactor surrounded by a quartz sleeve radiates through an annular water flow channel with a maximum width of 10 mm to 15 mm. This causes the water to circulate within an annular zone highly exposed to the 185 nm wavelength of UV radiation, as well as all other wavelengths below 200 nm. To optimize the mixing of the water within the zone, baffles or perturbation devices are provided in a series of locations to affect the mixing of different layers of liquid, thereby promoting the radial movement of water around the quartz tube.

Description

Technical Field

[0001] The present invention relates to water treatment, and more particularly to a process involving ultraviolet (UV) radiation for obtaining ultrapure water.

Background Art

[0002] In the field of water treatment, including the production of ultrapure water, a UV wavelength of nm is commonly used to reduce the total organic carbon (TOC) content in water. However, this UV wavelength is strongly absorbed in water, and beyond mm from the UV source, all wavelengths below nm and nm are considered to be essentially completely absorbed by water. Typically, low-pressure mercury lamps emit spectra at

[0005] nm and nm.

[0003] Conventionally designed UV reactors do not include restricting the distance from the UV source to the outer wall of the chamber to mm or less. In some cases, the reactor includes a large cylinder in which a plurality of elongated UV lamps are axially arranged. In such a cylinder, water circulates around the lamps. Nevertheless, the maximum distance of UV propagation in water often exceeds mm. US Patent No. US Patent No. US Patent Application Publication No.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] U.S. Patent No. 5,352,359 [Patent Document 2] U.S. Patent No. 5,846,437 [Patent Document 3] U.S. Patent Application Publication No. 2011 / 0318237 [Patent Document 4] U.S. Patent Application Publication No. 2011 / 0024365 [Patent Document 5] British Patent Document No. GB2579966 [Patent Document 6] U.S. Patent No. 12,077,456 [Overview of the project] [Means for solving the problem]

[0006] The present invention provides an improved, more efficient UV reactor for treating water, particularly for reducing TOC and producing ultrapure water, in a cylindrical configuration where water flows axially between an internal UV emitting device and a boundary cylindrical wall. The distance over which UV radiation, particularly the 185 nm wavelength, travels radially is preferably about 10 mm or less to ensure perfect UV treatment of the water. The cylindrical shell of the reactor is preferably made of polished stainless steel, resulting in relatively high reflectivity. A central elongated UV lamp is surrounded by a quartz sleeve, and water circulates along and around the quartz sleeve while traveling axially throughout the reactor. The annular cross-section providing a channel for the water is preferably about 10 mm or less in width in a preferred embodiment. Thus, the water circulates within a reactor zone that is greatly exposed to the 185 nm wavelength.

[0007] The annular flow channel for water includes baffles or perturbators, the shape of which is a key aspect of the present invention. One or more baffles or perturbators are preferably flat structures extending inward from the reactor shell wall, blocking the flow in many annular channels and establishing flow shapes that are asymmetrical with respect to both directions, i.e., left / right and up / down, but not symmetrical with respect to both directions, i.e., left-right flow openings different from those in the up / down direction. The shape of the perturbators induces vortices, which work favorably for the movement of water between different radial layers without creating undesirable large pressure drops within the reactor. This allows the maximum number of TOC molecules present in the water to be exposed as close to the quartz sleeve as possible and react with OH radicals produced by photolysis.

[0008] In one embodiment of the present invention, the annular flow channel through the tube can be up to 15 mm wide when combined with a baffle or perturbation device that is effective in causing active outward and inward water movement within the channel to maximize exposure to UV radiation.

[0009] In one preferred embodiment, the length of the reactor includes multiple perturbation devices, but with respect to successive perturbation devices, its shape is rotated.

[0010] The perturbation device within the UV reactor of the present invention, which may be limited to a flow channel width of approximately 10 mm, optimizes flow disturbances to increase the UV dose to each molecule of water. Tests have shown that the specific energy requirements with this design can be reduced by 1.5 times compared to current conventional configurations. In addition, the present invention uses fewer UV lamps and a smaller footprint, which can typically be reduced by up to 3 times.

[0011] An additional embodiment of the present invention may use multiple UV lamp tubes, in which case the UV radiation will not penetrate more than 10 mm (or 15 mm if there is adequate baffling) into the water. [Brief explanation of the drawing]

[0012] [Figure 1] It is a perspective view showing the UV water purification reactor of the present invention. [Figure 2] It is a cross-sectional perspective view showing the reactor. [Figure 3] It is a side elevation view showing the reactor with a shortened length. [Figure 4] It is a schematic cross-sectional view showing the position of the baffle or perturbation device in the reactor structure as seen along the plane 4-4 of FIG. 3. [Figure 5] It is a schematic cross-sectional view showing the position of the baffle or perturbation device in the reactor structure as seen along the plane 5-5 of FIG. 3. [Figure 6A] It is an enlarged view showing an example of the baffle. [Figure 6B] It is a perspective view of an operable baffle configuration. [Figure 7] It is a perspective view showing the baffle of FIG. 6A. [Figure 8] It is a cross-sectional view showing the baffle as seen along the plane 8-8 of FIG. 6A. [Figure 9] It is a schematic perspective view showing one of the baffles arranged in the tubular reactor. [Figure 10] It is a schematic perspective view showing the turbulent mixing flow induced by the baffle arranged in the reactor tube. [Figure 11] It is a schematic perspective view showing the turbulence induced by two consecutive baffles in different orientations by 90° in the reactor tube. [Figure 12] It is a perspective view showing a further example for the reactor tube having a plurality of UV lamp assemblies. [Figure 13] It is a perspective view showing a further example for the reactor tube having a plurality of UV lamp assemblies. [Figure 14] It is a cross-sectional elevation view showing the structure for preventing the escape of UV radiation from the inlet and outlet. [Figure 15] It is a cross-sectional elevation view showing the structure for preventing the escape of UV radiation from the inlet and outlet.

Best Mode for Carrying Out the Invention

[0013] FIG. 1 shows an ultra-pure water treatment UV reactor 10 in one embodiment for removing TOC from water. The water inlet and water outlet are shown at 12 and 14. As shown, the tube is of an elongated shape and in one embodiment can have, for example, an outer diameter of approximately 7 cm and a total length of about 1.7 meters. This is only an example and other dimensions can be used. A series of internal baffles 16 are shown within the reactor tube 18.

[0014] The cross-sectional view of FIG. 2 shows the reactor tube 18 including a UV lamp 20 preferably located centrally within an elongated quartz sleeve 22. The sleeve 22 is preferably made of high purity quartz (synthetic quartz). The interior of the sleeve 22 is sealed against the inflow of liquid. The water to be treated flows through an annular channel 24 between the outside of the quartz sleeve 22 and the inside of a cylindrical shell 18 which is preferably polished stainless steel. To ensure that all molecules of water and its contaminants are preferably exposed to UV radiation of a wavelength of 185 nm, the absolute maximum width of the annular channel 24 is 10 mm.

[0015] FIG. 3 shows some details of the structure of a preferred embodiment of the reactor. The reactor tube 18 is shown with its length shortened as indicated by the broken line 26 in the figure for clarity.

[0016] As noted above, the length and diameter of the tube can vary. The wall thickness of the tube 18 can be, for example, about 2 mm (+ / - 0.2 mm), but this can also vary.

[0017] As seen in the figure, the baffles 16 are preferably spaced within the tube 18. FIG. 3 shows five baffles as an example. The figure also shows another structure at 28 which simply functions to hold the quartz sleeve 22 centrally within the cylindrical tube 18.

[0018] Exemplary embodiments of the baffle 16 are shown in Figures 6A, 6B, 7, and 8. In this preferred shape, the baffle includes a short section of sleeve 30 having the same outer diameter as the tube 18, welded into the steel tube 18 at a midpoint within the tube as shown. The baffle structure is indicated by 32. In this particular shape, the baffle structure is formed symmetrically both left-right and top-down, although the top and bottom shapes differ from the left-right shapes as shown. Top and bottom, the baffle in this embodiment has an inwardly facing convex curve (preferably an arc) 32a, while left and right, the baffle shape is concave on the inside, as shown by 32b on both sides, in order to fit onto the quartz tube 22. These shapes can be arcs, with arc 32a having a radius of approximately 22 mm and arc 32b having a radius of approximately 23 mm, resulting in a small gap with the outer diameter of the quartz tube to allow for mechanical assembly. In this example, the overall outer dimensions of the baffle are approximately 70 mm, as with the tube itself. The inner diameter of the tube can be approximately 66 mm. In this example, the thickness of the sleeve 30 can be approximately 2 mm, and the thickness of the baffle 32 can also be the same.

[0019] Figure 6B shows only the operational portion of the baffle structure located within the annular channel in the water flow path, without the tubular sleeve 30 (shown in Figures 6A, 7, and 8).

[0020] Figures 4 and 5 show that when two or more baffles are included, the orientation of consecutive baffles alternates, preferably by 90°. Thus, Figure 4 shows a baffle 16 as oriented in Figure 6A, and Figure 5 shows a baffle rotated by 90°. Similarly, baffles at further positions within the length of the tube 18 are also alternate in orientation. As can be seen in Figure 6A, only slight flow occurs on the left and right sides where the baffles overlap very close to the quartz tube 22. However, on the top and bottom, flow openings 40 are formed as shown, and these openings include two large regions connected by a narrow constriction with a minimum clearance of about 1-2 mm. To establish the desired turbulence of water through the tube 18, the baffles are deburred and have no sharp edges.

[0021] Figure 9 shows a perspective view of the baffle 16 inside the tube 18, where the baffle surrounds the quartz sleeve 22. Figure 10 schematically shows the turbulent flow of water through a single baffle 16 when there are main flow regions of baffles on the left and right. In this perspective view, the flow is from left to right, and eddies and streamlines containing vortices are roughly indicated by lines with arrows 36.

[0022] When multiple spaced baffles (as shown in Figures 4 and 5), which are rotated and staggered, are present within the length of the annular channel, the flow stream or vein is rotated within its volume. Also, as shown in Figure 10, vortices and vortices are created within the annular flow volume, thereby promoting the movement of water between different radial layers without causing undesirable pressure loss.

[0023] Figure 11 provides a schematic overview of the effects of multiple baffles arranged within the tube, i.e., within the annular flow space. The upstream baffle 16a is shown with its main open areas on either side, creating a main flow into two opposing, darkened flow regions. This induces a swirling or spiral motion of the flow, as well as vortices, and its effect is amplified when the flow reaches the second baffle 16b. Baffle 16b is rotated 90° from the first baffle, inducing rotation of the main flow and further vortices and eddies, thereby moving the water outward and inward, ensuring that all the water encounters the UV source (i.e., the quartz tube) in its forward portion.

[0024] It should be noted that baffles can take other forms with different flow channel configurations, as long as they are constructed to create swirls, eddies, and vortices within the water flow as water progresses through the tube. It is preferable that the rotational orientation of the baffles be staggered, with each having a main flow opening at 180° (or in a different form unbalanced between up / down and left / right). However, other baffle configurations are possible, such as non-flat baffles with grooves or wings that create a constant outward and inward movement for optimal UV exposure. The annular flow channel within the tube is preferably about 10 mm (+ / - 10%) wide, but this width can be up to 15 mm if the baffles provide adequate mixing so that all the water progresses near the quartz tube for part of the time.

[0025] Figures 12 and 13 show additional configurations of the reactor according to the present invention. In Figure 12, a grouping of six tubes is shown, each of which has its own annular flow volume section supplied by a single inlet 12 and a single outlet (not shown). Manifold plates 38 at each end connect all the tubes to the inlet and outlet. In Figure 13, nineteen tubes are shown, which are also supplied by a single inlet 12 and a single outlet, but each of which is provided with separate inlet flow rates by manifold plates 39 located at the inlet and outlet.

[0026] The reactor of the present invention is preferably constructed to prevent UV radiation from being directed to enter and pass through the reactor outlet 14 and inlet 12 (not shown). Figures 14 and 15 show two different structural arrangements to prevent this. In Figure 14, the UV lamp 20 is positioned so that its end 41 is in front of the outlet (to the right in Figure 14), thereby preventing radially directed UV radiation from being directed through the outlet (or inlet). In Figure 15, the lamp 20 is essentially full length, but a UV shield 42 is positioned between the lamp and the outlet 14.

[0027] In this specification, the terms "approximately" or "about" used in conjunction with numerical limitations are intended to include a range of plus or minus 10% from the stated value.

[0028] The preferred embodiments described above are intended to illustrate the principles of the present invention and not to limit its scope. Other embodiments and variations of these preferred embodiments will be apparent to those skilled in the art and may be added without departing from the spirit and scope of the invention as defined in the claims.

Claims

1. A device for reducing the total organic carbon content (TOC) by UV oxidation in the production of ultrapure water, A long, slender cylindrical stainless steel tube, An elongated, high-purity quartz tube within the aforementioned stainless steel tube, wherein an annular channel volume is defined between the quartz tube and the stainless steel tube with a width of approximately 10 mm or less, A UV source within the quartz tube, arranged to emit UV radiation outward through the annular channel volume, wherein the radiation includes wavelengths smaller than 200 nm, A water inlet at one end of the elongated stainless steel tube and a water outlet at the opposite end, which allows water to be guided through the annular channel volume from one end to the opposite end, thereby oxidizing and / or reducing the TOC in the water, and A device equipped with the following features.

2. The device according to claim 1, comprising at least one baffle in the annular channel volume within the path of water flowing through the volume, the baffle causing exchange between the inner and outer layers of water as the water moves through the annular channel volume to expose substantially all of the thus flowing water to the vicinity of the quartz tube and the UV source.

3. The device according to claim 2, wherein the baffle is configured to disrupt the laminar flow of water by creating eddies and vortices in the flowing water.

4. The device according to claim 3, further comprising a series of baffles within the annular flow channel volume.

5. The device according to claim 4, each baffle having a main flow opening preferred in a particular rotational orientation, and the series of baffles being arranged alternately in rotational orientation for each baffle, so that as water flows through the annular channel volume, the water is further induced to mix and swirl, and all of the water essentially flows near the quartz tube.

6. A series of elongated stainless steel cylindrical tubes having the quartz tube and UV source described in claim 1, within a modular ultrapure water production device, wherein each of the inlet and outlet includes a manifold plate connecting the inlet or outlet to all of the stainless steel cylindrical tubes for the production of ultrapure water in high yield.

7. A device for reducing the total organic carbon content (TOC) by UV oxidation in the production of ultrapure water, A long, slender cylindrical stainless steel tube, An elongated, high-purity quartz tube within the aforementioned stainless steel tube, wherein an annular channel volume is defined between the quartz tube and the stainless steel tube with a width of approximately 15 mm or less, A UV source within the quartz tube, arranged to emit UV radiation outward through the annular channel volume, wherein the radiation includes wavelengths smaller than 200 nm, The aforementioned elongated stainless steel tube has a water inlet at one end and a water outlet at the opposite end, which allows water to be guided through the annular channel volume from one end to the opposite end to oxidize and reduce the TOC in the water, and Equipped with, A device comprising at least one baffle in the annular channel volume in a water path through the volume, the baffle being effective in causing exchange between the inner and outer layers of water as the water moves through the annular channel volume to expose substantially all of the thus flowing water to the vicinity of the quartz tube and the UV source.

8. The device according to claim 7, wherein the baffle is configured to disrupt the laminar flow of water by creating eddies and vortices in the flowing water.

9. The device according to claim 8, further comprising a series of baffles within the annular flow channel volume.

10. The device according to claim 9, wherein each baffle has a main flow opening that is preferred in a particular rotational orientation, and the series of baffles are arranged alternately in rotational orientation for each baffle, so that when water flows through the annular channel volume, the water is further induced to mix and swirl, and all of the water flows essentially near the quartz tube.

11. A series of elongated stainless steel cylindrical tubes having a quartz tube and a UV source as described in claim 7, in a modular ultrapure water production device, wherein each of the inlet and outlet includes a manifold plate connecting the inlet or outlet to all of the stainless steel cylindrical tubes for the production of ultrapure water in high yield.

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