Fluid sterilization device

Abstract

To provide a fluid sterilization device which achieves a high rectifying function by a rectifier, and which allows for a reduction in dimension in an axial direction.SOLUTION: A fluid sterilization device 10 includes an outside tube 22 through which a fluid as a sterilization object flows from one end side to the other end side in an axial direction, a rectifier 42 including a plurality of tapered holes 43 whose diameter increases from one end side to the other end side in the axial direction, and a light source 67 irradiating, with ultraviolet light, a sterilization processing space 39 on the other end side relative to the rectifier 42.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fluid sterilization device that irradiates fluid flowing in a tubular passage with ultraviolet light for sterilization.

Background Art

[0002] Patent Document 1 discloses a fluid sterilization device that irradiates fluid flowing in a tubular passage with ultraviolet light for sterilization. In this fluid sterilization device, a rectifying plate having a plurality of through-holes is disposed on the inlet side of the tubular passage, and by flowing the fluid through the sterilization treatment space in a rectified state, unevenness in the irradiation amount of ultraviolet light on the fluid flowing in the tubular passage is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the rectifying plate of Patent Document 1, the through-hole in the central portion in the radial direction of the rectifying plate has a larger diameter than the through-holes in the peripheral portion. Thereby, the radial uniformity of the velocity distribution of the fluid on the downstream side of the rectifying plate is promoted. Note that all the through-holes of the rectifying plate of Patent Document 1 are cylindrical holes.

[0005] On the other hand, it has been proposed to dispose two rectifying plates in total on the upstream side and the downstream side with a gap in the axial direction. In that case, the upstream rectifying plate has a plurality of first through-holes of cylinders in a relatively central portion in the radial direction, and the downstream rectifying plate has a plurality of second through-holes of cylinders having a larger diameter than the first through-holes distributed over the entire surface. Thereby, the fluid flowing into the tubular passage from the inlet can be rectified with a relatively short length in the axial direction.

[0006] An object of the present invention is to provide a fluid sterilization device capable of achieving a high rectifying function with a rectifying plate and further reducing the axial dimension.

Means for Solving the Problems

[0007] The fluid sterilization device of the present invention includes a tube body having a tubular passage for flowing the fluid flowing in from the inlet on one end side in the axial direction to the outlet on the other end side in the axial direction; a rectifying plate having a plurality of tapered holes whose diameters increase from the one end side to the other end side in the axial direction, disposed in the tubular passage, and partitioning the tubular passage into an introduction space on the one end side and a sterilization treatment space on the other end side; a light source for irradiating ultraviolet light to the sterilization treatment space; and is provided with.

Advantages of the Invention

[0008] According to the present invention, by forming the through holes of the rectifying plate into tapered holes whose diameters increase in the fluid flow direction in the tubular passage, a high rectifying function can be achieved. As a result, the axial dimension of the fluid sterilization device can be reduced.

Brief Description of the Drawings

[0009]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 7A

Figure 7B

Figure 7C

Figure 7D

Figure 8

Figure 9

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, a plurality of embodiments of the present invention will be described. Needless to say, the present invention is not limited to these embodiments. For the constituent elements common among the plurality of embodiments, the same reference numerals are used, and for the constituent elements with the same reference numerals that have been described in the previous embodiments, the description will be omitted in the subsequent embodiments.

[0011] (Configuration) FIG. 1A is a perspective view of the liquid sterilizer 10. FIG. 1B is a front view of the liquid sterilizer 10. FIG. 2 is a longitudinal sectional view of the liquid sterilizer 10. FIG. 3 is an enlarged view of the end portion on the light source unit 12 side of the liquid sterilizer 10.

[0012] The liquid sterilization device 10 includes a housing portion 11, a light source portion 12, an inlet portion 13, and an outlet portion 14. The inlet portion 13 and the outlet portion 14 are integrally formed with the housing portion 11. The liquid sterilization device 10 is typically arranged with its axial direction aligned with the vertical direction with the light source portion 12 on the upper side (vertically placed), as shown in FIG. 1B.

[0013] The liquid sterilization device 10 is an example of a fluid sterilization device and sterilizes water as a liquid which is also a fluid. The liquid sterilization device 10 is installed, for example, in a water storage tank such as an ice maker, a water supply pipe, a water heater, a water server, a circulation device (cooling water of a chiller), and a drink server.

[0014] The water after sterilization by the liquid sterilization device 10 is usually provided for drinking. Note that the sterilization in the circulation device is performed to prevent the viscosity of the circulating water from increasing and causing power loss when bacteria in the circulating water multiply.

[0015] The inlet portion 13 and the outlet portion 14 have screw grooves cut in their circumferential portions for connecting to pipes (not shown) in the device where the liquid sterilization device 10 is installed (FIG. 1B). The water sterilized by the ultraviolet light of the light source portion 12 in the liquid sterilization device 10 flows axially from the side of the inlet portion 13 (one end side) to the side of the outlet portion 14 (the other end side) through a tubular passage formed in the housing portion 11 and composed of an introduction side space 38 and a sterilization treatment space 39.

[0016] The light source portion 12 is attached to the housing portion 11 with its central axis aligned with the central axis of the housing portion 11 at the other end side in the axial direction of the liquid sterilization device 10. The inlet portion 13 is provided at the end of one end side of the housing portion 11 in the axial direction. The outlet portion 14 is provided on the side portion of the housing portion 11 protruding radially at a position separated by a predetermined distance from the other end to the one end in the axial direction.

[0017] The housing part 11 has an inner pipe 21 and an outer pipe 22 which are coaxially arranged. Both the inner pipe 21 and the outer pipe 22 are of straight pipe type. The inlet part 13 and the outlet part 14 are integrally provided on the outer pipe 22. The inlet 34 and the outlet 35 are respectively defined on the inner circumferential side of the inlet part 13 and the outlet part 14, and communicate the inside and outside of the outer pipe 22.

[0018] The inner pipe 21 has an end - side inner pipe member 17 and an other - end - side pipe member 18 which are joined to each other by the tightening force of a fixing nut 47 (to be described later) from one - end side and the other - end side in the axial direction. The inner pipe 21 is inserted into the outer pipe 22 from the opening at the other - end side of the outer pipe 22. The end - side inner pipe member 17 and the other - end - side pipe member 18 are open at both axial ends.

[0019] The other - end - side pipe member 18 has a small - diameter part 25 at the other - end side and a large - diameter part 26 at the one - end side in the axial direction. The annular space 29 is formed between the inner circumference of the outer pipe 22 and the outer circumference of the small - diameter part 25. There is a stepped part at the boundary between the small - diameter part 25 and the large - diameter part 26. This stepped part is located on the one - end side of the outlet 35 in the axial direction. Thereby, the outlet 35 is entirely exposed to the annular space 29 without being covered by the large - diameter part 26.

[0020] In this embodiment, the stepped part protrudes from the small - diameter part 25 perpendicular to the axial direction of the inner pipe 21, that is, parallel to the radial direction of the inner pipe 21. It is also possible to make the stepped part a tapered stepped part instead of a perpendicular stepped part to smoothly change the direction of the water flow from the annular space 29 to the outlet 35.

[0021] The flow - straightening plate 42 is inserted into an annular groove 20 formed on the inner circumferential side of the joint part 19 between the end - side inner pipe member 17 and the other - end - side pipe member 18 at its periphery, and is clamped by the mutual joining force of the end - side inner pipe member 17 and the other - end - side pipe member 18 from both axial sides. This joining force is generated by the axial tightening force of a fixing nut 47 (to be described later).

[0022] The rectifying plate 42 divides the tubular passage defined by the inner tube 21 on the inner peripheral side into an introduction-side space 38 on one end side and a sterilization treatment space 39 on the other end side. FIGS. 4A and 4B are views of the rectifying plate 42 as seen from the other end side in the axial direction and from an obliquely other end side, respectively. In FIGS. 2, 4A, and 4B, the rectifying plate 42 has a plurality of tapered holes 43 penetrating in the axial direction. The tapered holes 43 are open at both the one end side and the other end side in the axial direction with circular upstream openings 44a and downstream openings 44b. The diameter of the upstream opening 44a < the diameter of the downstream opening 44b. That is, the tapered holes 43 gradually increase in diameter from one end side to the other end side in the axial direction.

[0023] In FIG. 3, the other-end-side pipe member 18 has a plurality of notch grooves 50 with a U-shaped cross section at equal angular intervals in the circumferential direction on the circumferential end face at the other end side in the axial direction. The quartz plate 45 has the peripheral edge portion at one end side fitted into the stepped portion on the inner circumference of the other end portion of the outer tube 22 and is applied to the circumferential end face of the other-end-side pipe member 18, and an annular spacer 56 is applied to the peripheral edge portion at the other end side.

[0024] The circuit board 57 is inserted into the through hole of the fixing nut 47, has the surface on the quartz plate 45 side, and has a light source 67 at the center of the surface. The heat sink 58 has one end side inserted into the through hole of the fixing nut 47 in the axial direction, is applied to the end face of the fixing nut 47 at the flange portion at the other end side, and is fixed to the end face of the fixing nut 47 by a plurality of screws 60.

[0025] The fixing nut 47 is fixed to the housing portion 11 as a pipe body by screwing into the screw groove formed on the outer peripheral portion of the other end portion in the axial direction of the outer tube 22. This screwing moves the fixing nut 47 from the other end side to the one end side in the axial direction, and axially clamps the one-end-side inner tube member 17 and the other-end-side pipe member 18 accommodated in the outer tube 22 with the annular spacer 56 and the quartz plate 45 to bring them into a joined state. Thus, the one-end-side inner tube member 17 and the other-end-side pipe member 18 axially sandwich the peripheral edge portion of the rectifying plate 42 in the annular groove 20 while being joined to each other.

[0026] (Sterilization effect) Water (not shown) as the fluid to be sterilized is pumped by a pump (not shown) and enters the inlet 34. Next, the water flows from the inlet 34 into the introduction-side space 38, and at this time, it spreads in the radial direction of the inner pipe 21 due to the increase in the passage cross-sectional area.

[0027] Thereafter, it passes through the tapered holes 43 of the rectifying plate 42 and enters the sterilization treatment space 39. When the water passes through the tapered holes 43, it spreads in the radial direction as the direction perpendicular to the axial direction, and after jetting from the tapered holes 43, it diffuses at a diffusion angle corresponding to the taper angle θ (FIG. 9) of the tapered holes 43. As a result, at the other end side (downstream side) of the rectifying plate 42, the water flows jetted from the adjacent tapered holes 43 into the sterilization treatment space 39 come into contact with each other at an appropriate inclination angle, suppressing the radial diffusion and achieving rectification parallel to the axial direction.

[0028] The light source 67 irradiates the water in the sterilization treatment space 39 with ultraviolet light from the other end side in the axial direction through the quartz plate 45. Thereby, bacteria and the like mixed in the water are sterilized. The water hits the quartz plate 45, changes its direction from the axial direction to the radially outer side, and enters the annular space 29 through the notch groove 50. In the annular space 29, the water flows from the other end side to the one end side in the axial direction, opposite to that in the sterilization treatment space 39, changes the direction of the flow to the radially outer side at the location of the outlet 35, and flows out of the liquid sterilizer 10 through the outlet 35.

[0029] Since the notch groove 50 communicates the upper end of the sterilization treatment space 39 and the upper end of the annular space 29, it is avoided that air pockets or water stagnation are generated in the upper parts of the sterilization treatment space 39 and the annular space 29 (the upper part in the vertical placement in FIG. 1B).

[0030] When ultraviolet light passes through air, its intensity greatly decreases, which causes a decrease in the sterilizing power. Also, if the water stays in the sterilization treatment space 39 without flowing, the stagnant water becomes the residual water in the sterilization treatment space 39 after the operation of the liquid sterilizer 10 ends. When the non-operating time is long, bacteria multiply in the residual water. Therefore, when restarting the operation, it is necessary to wait for the use of the sterilized water until the residual water in which bacteria have multiplied is discharged from the liquid sterilizer 10.

[0031] In the liquid sterilization device 10, the notch groove 50 at the other end of the other end side pipe member 18 prevents air accumulation and fluid retention in the housing portion 11, so that it is possible to prevent a decrease in the sterilization power of the liquid sterilization device 10 and the generation of residual water.

[0032] (Flow velocity analysis diagram) FIG. 5 is a diagram showing a cross-sectional direction. FIGS. 6A, 6B, 6C, and 6D are diagrams showing the flow velocity distributions in the Ac-Ac cross-sectional view of FIG. 5 for the fluid sterilization devices of Comparative Examples 1, 2, and 3 and the liquid sterilization device 10 of the embodiment. FIGS. 7A, 7B, 7C, and 7D are diagrams showing the flow velocity distributions in the Bc-Bc cross-sectional view of FIG. 5 for the fluid sterilization devices of Comparative Examples 1, 2, and 3 and the liquid sterilization device 10 of the embodiment.

[0033] The flow velocity distributions in these figures are obtained from simulations performed by the inventor, and the flow velocity is shown in a plurality of stages. In these figures, the whiter the region, the higher the flow velocity.

[0034] Comparative Example 1 is a flow velocity distribution diagram without a flow straightening plate. Comparative Example 2 is a flow velocity distribution diagram when two flow straightening plates are provided. The axial through holes of the two flow straightening plates in Comparative Example 2 are both cylindrical holes, and the diameter of the cylindrical hole of the upstream flow straightening plate is smaller than that of the downstream flow straightening plate. Comparative Example 3 is an example in which one flow straightening plate with a through hole being a cylindrical hole is provided. In contrast, the liquid sterilization device 10 of the embodiment in FIGS. 6D and 7D includes a flow straightening plate 42. The taper angle θ (FIG. 9) of the taper hole 43 of the flow straightening plate 42 is set to 14°.

[0035] Comparative Example 1 (Figs. 6A and 7A), 3 (Figs. 6C and 7C) have a white region that extends longer toward the other end side, while Comparative Example 2 (Figs. 6B and 7B) has a short white region. The small area of the white region in the tubular passage means a high rectification state. Also, in the liquid sterilization device 10 of the embodiment (Figs. 6D and 7D), it can be seen that the axial position where the fluid ejected from the downstream rectifying plate in Comparative Example 2 reaches a stable rectification state after ejection can be achieved almost at the axial position of the upstream rectifying plate. Thus, it can be understood that by using the rectifying plate 42 of the liquid sterilization device 10, while obtaining the same rectification effect as using two rectifying plates with different pore diameters, the liquid sterilization device 10 can be reduced in the axial direction.

[0036] The inventor further obtained the following findings in the simulation test. In Comparative Example 2 (using two rectifying plates), when the rectification chamber length (the length of the portion upstream of the rectifying plate) is decreased from 10 mm to 5 mm, the effect of homogenizing the flow velocity distribution weakens. On the other hand, in the liquid sterilization device 10 of the embodiment, it was found that even when the rectification chamber length (the length of the portion upstream of the rectifying plate, corresponding to the length of the inner pipe member 17 on one end side) is decreased from 10 mm to 5 mm, the effect of homogenizing the flow velocity distribution can be maintained.

[0037] Furthermore, in Figs. 6D and 7D, although the taper angle θ (Fig. 9) of the tapered hole 43 was set to 14°, even when the taper angle θ is increased up to 18.4°, almost the same effect as when the taper angle θ is 14° can be obtained. The preferable range of the taper angle θ will be described with reference to Fig. 9 below.

[0038] (Range of the taper angle θ) Fig. 9 is an explanatory diagram of the preferable range of the taper angle θ of the tapered hole 43. The taper angle θ of the tapered hole 43 is defined as the intersection angle between the side edge line of the tapered hole 43 and the central axis line of the rectifying plate 42 in the cross-section of the rectifying plate 42 (the cross-section shown in Fig. 9) when the rectifying plate 42 is cut by a plane including its central axis line. Note that the direction of the central axis line of the rectifying plate 42 and the axial direction of the liquid sterilization device 10 are parallel to each other.

[0039] The definitions of the symbols in Fig. 9 are as follows. tl: Thickness of the rectifying plate 42 (= dimension of the rectifying plate 42 in the direction of the central axis) di: Diameter of the upstream opening 44a do: Diameter of the downstream opening 44b Fw: Flow direction of the main flowing water in the tubular passage Φa: Diameter of the rectifying plate 42 Ra: A predetermined value less than 1 (e.g., 0.65)

[0040] In order to set the preferable range of the taper angle θ, the following formula 1 is introduced. Formula 1: (2·tl) / (di + do) < Ra

[0041] The reason why 0.65 is desirable as Ra is as follows. Consider the case where di = do on the left side of Formula 1. di = do means that instead of the tapered hole 43, it is a cylindrical hole. When the fluid sterilizer has only one rectifying plate and all the plurality of through-holes of the rectifying plate are cylindrical holes with the same diameter, when Ra ≥ 0.65, the rectifying state on the downstream side of the rectifying plate is inappropriate, that is, the flow velocity distribution has poor radial uniformity in the tubular passage and the function as a rectifying plate is insufficient. For this reason, 0.65 is selected as Ra.

[0042] It should be noted that Ra must be less than 1 because if Ra ≥ 1, the thickness of the rectifying plate becomes larger than the diameter of the through-hole, and the through-hole becomes an orifice, leading to a significant decrease in the flow velocity. In addition, the rectifying plate needs to have the function as the partition wall Wp (Fig. 9) in order to perform the rectifying function.

[0043] Regarding the relationship between the taper angle θ and the various parameters of Formula 1, there is the following relationship of Formula 2. Formula 2: tanθ = (do - di) / (2·tl)

[0044] For example, when di = 3 mm, do = 4 mm, and tl = 2 mm, Equation 1 is satisfied and θ = 14°. Also, when di = 3 mm, do = 5 mm, and tl = 2 mm, Equation 1 is satisfied and θ = 26.5°. Note that the taper angles θ = 14° and 18.4° described in relation to FIGS. 6D and 7D above are also values within the range that satisfies the conditions of Equation 1.

[0045] Summarizing the preferred range of the taper angle θ, it is the range of the taper angle θ derived from Equation 2 while satisfying the requirements of Equation 1. Since a plurality of taper holes 43 must be formed in the rectifying plate 42, it goes without saying that do < Φa.

[0046] (Another rectifying plate) FIG. 8 is a view of another rectifying plate 72 as seen from the other end side in the axial direction. The rectifying plate 72 has a plurality of taper holes 43 (FIG. 4A) as through holes penetrating in the axial direction and a plurality of cylindrical holes 74 that are not taper holes. When the rectifying plate 72 is divided into two parts in the radial direction, the central part and the peripheral part, the taper holes 43 are formed in the central part, and the cylindrical holes 74 are formed in the peripheral part.

[0047] When water, which is the fluid to be sterilized by the liquid sterilization device 10, flows from the inlet 34 into the introduction side space 38, it spreads in the radial direction. The water on the peripheral side of the introduction side space 38 in the radial direction is suppressed from spreading in the radial direction by the inner peripheral walls of the one - end - side inner pipe member 17 and the other - end - side inner pipe member 18 until it reaches the notch groove 50 in the axial direction and proceeds. Conversely, when the water on the peripheral side passes through the taper holes 43, the axial flow along the inner peripheral wall of the introduction side space 38 is likely to be inhibited by the taper holes 43.

[0048] Therefore, in the rectifying plate 72, the water in the central part in the radial direction passes through the taper holes 43, and the water in the peripheral part passes through the cylindrical holes 74, thereby making the rectifying effect higher for the water in the peripheral part than when passing through the taper holes 43.

[0049] In addition, in both the rectifying plates 42 (Fig. 4A) and 72 (Fig. 8), the plurality of tapered holes 43 are continuous in any array direction (vertical, horizontal, or diagonal array direction), and one tapered hole 43 is not isolated from the other tapered holes 43, that is, there is no cylindrical hole 74 adjacent in any array direction.

[0050] (Modification example) In the liquid sterilization device 10, the ultraviolet light from the circuit board 57 irradiates the water as the fluid to be sterilized in the sterilization treatment space 39 in the axial direction. The ultraviolet light of the present invention may be arranged on the radially outer side of the tubular body so as to irradiate the water in the sterilization treatment space 39 from the radially outer side. In that case, the liquid sterilization device 10 does not need to have a double structure of the inner tube 21 and the outer tube 22, and the inner tube 21 is omitted. Then, the water flows out directly from the sterilization treatment space 39 to the outlet 35 without passing through the annular space 29.

[0051] In the liquid sterilization device 10, the housing portion 11 constitutes the tubular body, and the outer tube 22 constitutes the cylindrical member. An annular space 29 is formed between the outer peripheral portion of the other end side tube member 18 and the inner peripheral portion of the outer tube 22. In the present invention, the annular space 29 and the notch groove 50 can be omitted. In that case, the outlet 35 opens into the sterilization treatment space 39 in the other end side tube member 18 and communicates directly with the sterilization treatment space 39 without passing through the annular space 29.

[0052] In the liquid sterilization device 10, the quartz plate 45 is provided as the plate-shaped transmission member. The plate-shaped transmission member of the present invention can also be made of other materials that have a predetermined resistance to ultraviolet light, can transmit ultraviolet light, and ensure strength.

Explanation of reference numerals

[0053] 10... Liquid sterilization device, 11... Housing part (pipe body), 12... Light source part, 17... Inner pipe member on one end side, 18... Outer pipe member on the other end side, 19... Joint part, 20... Annular groove, 21... Inner pipe, 22... Outer pipe (cylindrical member), 29... Annular space, 34... Inlet, 35... Outlet, 38... Inlet side space, 39... Sterilization treatment space, 42, 72... Rectifying plate, 43... Taper hole, 45... Quartz plate (plate-shaped transmission member), 47... Fixing nut, 50... Notch groove, 67... Light source, 74... Cylindrical hole.

Claims

1. a tube having a tubular passage for allowing a fluid that has flowed in from an inlet at one end in the axial direction to flow in the axial direction to an outlet at the other end in the axial direction; a straightening plate having a plurality of tapered holes whose diameters increase from the one end side to the other end side in the axial direction, the straightening plate being disposed in the tubular passage and dividing the tubular passage into an introduction space on the one end side and a sterilization treatment space on the other end side; A light source that irradiates the sterilization treatment space with ultraviolet light; A fluid sterilization device comprising:

2. 2. The fluid sterilization device of claim 1, said tubular body comprising: a first end pipe member defining the introduction space on its inner periphery; and a second end pipe member defining the sterilization treatment space on its inner periphery, joined to the first end pipe member in the axial direction, and clamping a peripheral portion of the baffle plate in the axial direction by an annular groove formed between the first end pipe member and the second end pipe member at the inner periphery of the joint.

3. 3. The fluid sterilization device according to claim 1 or 2, The inlet is open to the introduction space opposite the flow straightening vane in the axial direction, A fluid sterilization device characterized in that the baffle plate has the plurality of tapered holes arranged in a radial center portion and a plurality of cylindrical through holes arranged in the radial peripheral portion.

4. 3. The fluid sterilization device of claim 2, the other end side pipe member has a plurality of notched grooves in a circumferential direction on an opening periphery that opens at the other end in the axial direction, the pipe body includes a cylindrical member disposed coaxially with the other end side pipe member and defining an annular space between the other end side pipe member and an outer periphery of the other end side pipe member, the annular space communicating with the outlet port on the outer periphery side, a plate-shaped transparent member through which the ultraviolet light passes contacts a peripheral edge of the opening of the other end side tube member to close the peripheral edge of the opening; The fluid sterilization device, wherein the light source is disposed on the other end side of the plate-shaped transparent member in the axial direction.

5. The fluid sterilization device according to any one of claims 1 to 4, When a thickness of the flow straightening plate is tl, diameters of an upstream opening and a downstream opening which are openings on the one end side and the other end side in the axial direction of the tapered hole are di and do, respectively, and Ra is a predetermined value less than 1, (2・tl) / (di+do)<Ra A fluid sterilization device, characterized in that the following relationship is satisfied.

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