APPARATUS FOR STERILIZING A LIQUID

Abstract

An apparatus for sterilizing a liquid comprises a container (10) having an inlet (12), an outlet (14) and an interior (16) with an outer wall (18), and at least one light source (32) which is adapted to emit radiation in the ultraviolet wavelength range, in particular UV-C radiation, through the outer wall (18) into the interior (16), the outer wall (18) of the interior (16) for this purpose being configured to be at least partially transparent. The inlet (12) comprises at least one opening (28), which is positioned and aligned in relation to the outer wall (18) of the interior (16) and the at least one light source (32) in order, when a pressure is exerted on the liquid to be admitted through the at least one opening (28) and to be sterilized, to form a liquid jet (30) directed onto the outer wall (18) in a region of the at least one light source (32) and/or above the latter, and/or to form a liquid film (31) there. The liquid jet (30) impinging on the outer wall (18) may, for example, flow down thereon as a thin liquid film (31) in front of the at least one light source (32) and thereby lead to effective sterilization even with a low penetration depth of the UV radiation.

Claims

1. An apparatus for sterilizing a liquid, comprising: a container (10) having an inlet (12), an outlet (14) and an interior (16) with an outer wall (18); at least one light source (32) which is adapted to emit radiation in the ultraviolet wavelength range, in particular UV-C radiation, through the outer wall (18) or from a position on the outer wall (18) into the interior (16); wherein the inlet (12) comprises at least one opening (28), which is positioned and aligned in relation to the outer wall (18) of the interior (16) and the at least one light source (32) in order, when a pressure is exerted on the liquid to be admitted through the at least one opening (28) and to be sterilized, to form a liquid jet (30) directed onto the outer wall (18) in a region of the at least one light source (32) and/or above the latter, and/or to form a liquid film (31) there.

2. The apparatus as claimed in claim 1, wherein the at least one opening (28) is respectively formed as a nozzle, and/or the opening (28) is configured to form the liquid jet (30) directed onto the outer wall (18) in such a way that it can impinge on the outer wall (18) as a focused or fanned-out jet and can flow down thereon as a thin liquid film (31) in front of the at least one light source, or as a finely distributed spray mist it fills a volume adjacent to the region of the at least one light source (32).

3. The apparatus as claimed in claim 1 or 2, wherein the inlet (12) comprises a supply line (13) at least partially guided through the interior (16), the at least one opening being formed in the supply line.

4. The apparatus as claimed in claim 3, wherein the interior (16), or its outer wall (18), comprises a section (19) which has a midaxis (X).

5. The apparatus as claimed in claim 4, wherein the supply line (13) extends substantially along or at a distance parallel to the midaxis (X) of the section (19).

6. The apparatus as claimed in one of claims 3 to 5, wherein a multiplicity of openings (28) are provided in the supply line (13).

7. The apparatus as claimed in claim 6, wherein the multiplicity of openings (28) in the supply line (13) are arranged in a direction along the midaxis (X).

8. The apparatus as claimed in claim 6 or 7, wherein the multiplicity of openings (28) in the supply line (13) are arranged in an azimuthal direction with respect to the midaxis (X).

9. The apparatus as claimed in one of claims 3 to 8, wherein the at least one opening (28) is respectively adapted to direct a focused liquid jet (30) onto the outer wall (18).

10. The apparatus as claimed in one of claims 3 to 9, wherein the supply line (13) or at least one section (24) thereof, which comprises the at least one opening (28), is adapted to be movable, in the case of the section (19) of the interior (16) in particular rotatable about the midaxis (X), in order to reorientate a principal jet direction of the liquid jet (30), in which case an apparatus (44) for moving the supply line (13) or the section (24) thereof, which drives the movement, in particular a rotation, may be provided in particular.

11. The apparatus as claimed in one of claims 3 to 9, furthermore comprising a deflecting element which is provided in or at the at least one opening (28) and is adapted to deflect a principal jet direction of the liquid jet (30) in the interior (16).

12. The apparatus as claimed in one of the preceding claims, furthermore comprising an apparatus (38) for adjusting the pressure of the liquid in the supply line (13) before the at least one opening (28), the apparatus being adapted to adjust the strength of the liquid jet (30).

13. The apparatus as claimed in claim 12, wherein the apparatus (38) for adjusting the pressure of the liquid in the supply line (13) is adapted to generate a pulsating liquid jet (30).

14. The apparatus as claimed in one of the preceding claims, wherein the at least one opening (28) is a nozzle, furthermore comprising an apparatus (40) for adjusting a nozzle, which is adapted to selectively adjust a spatially fanned-out liquid jet (30) with a comparatively large aperture angle, or a strongly focused liquid jet (30) with a comparatively small aperture angle.

15. The apparatus as claimed in one of the preceding claims, furthermore comprising: a sensor (42) which is configured to register a turbidity of the liquid (13) that has flowed down on the outer wall (18) in the container (10), and a control apparatus which is connected to the sensor (42) and selectively to the apparatus (38) for adjusting the pressure of the liquid in the supply line (13), to the apparatus (40) for adjusting the nozzle and/or to the movable section and which is configured to correspondingly adjust the pressure in the supply line (13), the aperture angle of the liquid jet (30) or the principal jet direction or the rotational speed as a function of the registered turbidity of the liquid.

16. The apparatus as claimed in one of the preceding claims, wherein the at least one light source (32) is an LED emitting radiation in the ultraviolet wavelength range, in particular UV-C radiation, a multiplicity of LEDs preferably being provided.

Description

BRIEF DESCRIPTION OF THE DRAWING(S)

[0045] FIG. 1 shows a diagram of the spectral UV-C transmission T [in %] at a wavelength of 254 nm in water as a function of the layer thickness d [in mm], specifically for ultrapure water (SSK254 at d=10 mm: 99%), drinking water (SSK254 at d=10 mm: 98%), drinking water (SSK254 at d=10 mm: 85%), wastewater (SSK254 at d=10 mm: 75%), and wastewater (SSK254 at d=10 mm: 50%);

[0046] FIG. 2A shows a vertical UV-C reactor according to a first embodiment in a schematic cross-sectional view from the side;

[0047] FIG. 2B shows the vertical UV-C reactor of FIG. 2A in a schematic cross-sectional view from above;

[0048] FIG. 3A shows a horizontal UV-C reactor according to a second embodiment in a schematic cross-sectional view from the side;

[0049] FIG. 3B shows the horizontal UV-C reactor of FIG. 3A in a schematic cross-sectional view from the end side;

[0050] FIG. 4 shows a schematic representation of a further exemplary embodiment, for example based on the first or second embodiment, with the possibility of feedback of the disinfected liquid and a corresponding control apparatus.

[0051] In the following description of preferred exemplary embodiments, it should be taken into account that the present disclosure of the various aspects is not restricted to the details of the construction and the arrangement of the components as are presented in the following description and in the figures. The exemplary embodiments may be implemented or carried out in a variety of ways in practice. It should furthermore be taken into account that the expressions and terminology employed here are used merely for the purpose of specific description and they should not be interpreted restrictively by the person skilled in the art per se.

[0052] First, FIG. 1 illustrates in a diagram the influence of a reduction in the transmission as a function of the layer thickness due to turbidity or pollution with various water qualities. The spectral UV-C transmission T [in %] is shown at a wavelength of 254 nm conventionally used for this purpose in water as a function of the layer thickness d [in mm], specifically for ultrapure water (curve T(Wc): SSK254 at d=10 mm: 99%), drinking water (curve T(Wt1): SSK254 at d=10 mm: 98%), drinking water (curve T(Wt2): SSK254 at d=10 mm: 85%), wastewater (curve T(Ww1): SSK254 at d=10 mm: 75%), and wastewater (curve W(w2): SSK254 at d=10 mm: 50%).

[0053] As may be seen, ultrapure water absorbs the irradiated UV-C light comparatively weakly. However, the wavelength-dependent radiation absorption is greatly influenced because of compounds dissolved in the water as well as by undissolved substances, as may be seen clearly in FIG. 1 from the curves for drinking water and wastewater. The extent of the UV-C absorption is consequently correlated with the water quality. The attenuation of the radiation as a function of the layer thickness is determined by an optical measurement and may be expressed as a spectral attenuation coefficient SSK. For example, 10 mm may be taken as a reference layer thickness. Measurement values for the attenuation coefficient are often used in the scope of sterilization and water treatment. In particular, the special coefficient SSK254 is determined without prior filtration at the wavelength 254 nm, so that substances causing turbidity and particles are also jointly registered with this coefficient. The measurement value is therefore increased in comparison with other coefficients (for example SAK), but precisely this coefficient is practically relevant in reactors because it is the extent of the actual radiation through the liquid for a given total layer thickness which is important.

[0054] For an exemplary application of the embodiments described below in dishwashers or washing machines, in FIG. 1 the two curves T(w1) and T(w2) are relevant for wastewater, especially the curve for more strongly polluted wastewater T(w2). They show that even with layer thicknesses of 5 mm, only 10% of the initial intensity of the UV-C radiation remains.

[0055] A first embodiment of an apparatus for sterilizing a liquid is shown in FIGS. 2A and 2B. The apparatus comprises a container 10 having an inlet 12, an outlet 14 and an interior 16 with an outer wall 18. The interior 16 comprises an upper cylindrical section 19 and a lower conical or funnel-shaped section 17, which tapers from the cylindrical section to the outlet 14. The cylindrical section and the conical section form a section with a common midaxis X. The midaxis X extends parallel to the force of gravity G in this particular exemplary embodiment. The outer wall 18 may be formed to be transparent entirely or only in the region of a number of light sources 32, in this exemplary embodiment of UV-C LEDs. In particular, it is transmissive for the radiation emitted by the UV-C LEDs. The UV-C LEDs may, for example, emit radiation with a wavelength of 265 nm and the respective power may be from 50 to 100 mW.

[0056] As may be seen by viewing FIGS. 2A and 2B together, the light sources 32 are arranged in 3 groups respectively of 9 LEDs. The UV LEDs are in this case distributed at equal distances from one another around the midaxis X on (or behind) the outer wall 18 and emit their radiation with a principal beam direction onto the midaxis X. The three groups of light sources 32 are in turn arranged at equal distances from one another along the midaxis X in the region of the cylindrical section. In this exemplary embodiment as in others too, more or fewer LEDs may also be provided in the rows, the number of rows may likewise be varied, and the LEDs may also emit radiation with a different wavelength in order to achieve supplementary effects. The power supply and the control of the LEDs are not depicted in the figures for the sake of simple representation.

[0057] The inlet 12 in the exemplary embodiment shown in FIGS. 2A and 2B is formed by a supply line 13, which is provided as a rotatable tube with a section 24 at the distal end in which an opening 28 is set up, through which the liquid to be sterilized is admitted into the interior 16. In particular, the opening 28 may be configured as a nozzle. The opening 28, or the nozzle, is aligned onto the outer wall 18, i.e. it has for example a flow axis which is transverse to the midaxis X of the interior 16 and is preferably perpendicular thereto. In particular, the flow axis is directed onto the outer wall 18, specifically onto a region of the outer wall 18 in which the UV-C light sources 32 are arranged. The light sources 32 therefore lie opposite the opening 28, or nozzle. A plurality of such openings 28 or nozzles may also be set up in the section 24.

[0058] The supply line 13 extends substantially along the midaxis X of the cylindrical section 19. As described, the supply line or else only a limited section 24 with the nozzle head, in particular a front section 24 as illustrated in FIG. 2A, may be adapted to be rotatable at least in this section 19, the rotation axis coinciding with the midaxis X as schematically indicated in FIG. 2A. Likewise schematically indicated is an apparatus 44 for moving the supply line 13 with the section 24 at its distal end. Other than implied in FIG. 2A, the apparatus 44 may also be arranged outside the interior 16. The apparatus may be connected to the power supply (not shown) in order to drive the rotation of the supply line 13, or of the section 24 with the opening 28, about the midaxis X. It is, however, also possible for the rotation to be driven from the flow pressure of the liquid flowing through and for the apparatus 44 merely to convert the forces into rotation, as is known for example from the mechanism of conventional sprinkler and (garden) watering installations.

[0059] As is represented in FIGS. 2A and 2B, the opening 28, or the nozzle, is configured to direct a liquid jet 30 onto the outer wall 18. This may impinge on the outer wall 18 as a focused or fanned-out jet and can flow down thereon as a thin liquid film 31 past the respective light source 32, i.e. driven by gravity, in the direction of the outlet 14. As an alternative or in addition, the nozzle may project the liquid as a finely distributed spray mist and thereby fill a volume adjacent to the region in which the light sources 32 are arranged. The UV-C LEDs therefore irradiate the liquid film traveling past, which has a thickness much less than the penetration depth of the UV-C radiation, or a multiplicity of very fine droplets, the penetration depth also being sufficient here so that effective sterilization can take place.

[0060] A sharply focused jet may furthermore be generated by the nozzle, which in respect of germs accumulating on the outer wall with possible formation of biofilms may achieve a mechanically abrasive effect so that the germs or biofilms may be removed and possibly the latter may be prevented from being created at all. In order to generate a corresponding pressure in the liquid—as schematically represented in FIG. 2A—an apparatus 38 for adjusting the pressure of the liquid in the supply line 13 may be provided before the opening or openings 28 in the flow direction. The apparatus 38 may, for example, be constructed in the manner of a pump. The apparatus is in this case configured to adjust the strength of the liquid jet 30 indirectly by adjusting the pressure. The apparatus 38 for adjusting the pressure of the liquid in the supply line 13 may be controlled by the control apparatus described above or another control apparatus (likewise not represented). In this case, an operating mode in which a pulsating liquid jet 30 is generated may be provided. This may further improve the abrasive effect on the outer wall 18.

[0061] It should be noted that, in the exemplary embodiment shown in FIGS. 2A and 2B, a plurality of nozzles may be set up in the azimuthal direction on the distal section. Optionally, the supply line 13 may also be adapted to be displaceable in the direction of the midaxis X in order to be able to sweep over and abrasively treat different sections and regions of the interior 16. A plurality of sections 24 respectively having one or more nozzles may also be provided. Furthermore, the sections 24 may also be adapted to be rotatable relative to the supply line 13, which is itself then installed fixed, i.e. does not need to be rotatable.

[0062] A second embodiment of an apparatus for sterilizing a liquid is shown in FIGS. 3A and 3B. FIG. 3A shows in particular a horizontal UV-C reactor for sterilizing a liquid in a side view, while FIG. 3B shows the horizontal UV-C reactor of FIG. 3A in a schematic cross-sectional view from the end side. Similarly as in the first embodiment, the apparatus comprises a container 10 having an inlet 12 with a supply line 13, an outlet 14 and an interior 16 with an outer wall 18. Other than in the first embodiment, the interior 16 or a cylindrical section 19 with a midaxis X is formed almost flat, i.e. the midaxis X is almost perpendicular to the direction of gravity, see FIG. 3A. However, a slight inclination of the midaxis X relative to a horizontal direction remains here in order to allow a downward flow of the sprayed liquid (see the liquid 31a flowing down in FIG. 3A). A funnel-shaped section 17 forms the transition to a vertically aligned outlet 14, to which it tapers.

[0063] In other regards, the structure is very similar as in the first embodiment. Light sources 32 are positioned in 11 groups of UV-C LEDs arranged in rows of 9 each annularly around the midaxis X on the outer wall 18. The groups are arranged at equal distances from one another along the midaxis X. The supply line 13 also extends along the midaxis here, although it may also be arranged offset relative thereto, for example by a slight offset in the upward vertical direction, since for example an upwardly directed jet must act against the force of gravity and the jet force is therefore slightly reduced here.

[0064] On the other hand, the flat arrangement of the cylindrical section 19 of the interior leads to an accumulation of liquid 31a flowing down on the lower side of the cylinder (see FIG. 3B), where an abrasion effect is consequently more difficult to achieve. It is, however, also possible to compensate for this by the offset of the supply line 13 taking place precisely for this reason in the vertical direction downward in order to impact the liquid flowing down with a sharp and stronger (since it is close) jet and therefore to prevent biofilms from forming.

[0065] In the second embodiment, a plurality of (in the schematic representation: five) rotatable sections 24 are shown, which are set up along the midaxis in the supply line 13 at equal distances. More or fewer rotatable sections 24 may also be provided. As in the first embodiment, openings 28 or nozzles directed onto the outer wall are provided therein, which direct the liquid to be sterilized as a liquid jet 30 onto the outer wall 18, on which it flows downward in the circumferential direction (see FIG. 3B), collects there and then flows down in the axial direction (parallel to the midaxis X) to the funnel-shaped section 17 and from there in the outlet 14. The sections 24 may be firmly connected to the supply line 13 and be rotatable together therewith or may be adapted to be rotatable individually and separately relative to the supply line 13. An apparatus 44 for moving the supply line 13 and/or the sections 24 may be provided, as described in the first embodiment.

[0066] In respect of an apparatus 38 for adjusting the pressure of the liquid in the supply line 13, which is also optionally provided in the second embodiment, reference may be made to the comments relating to the first embodiment.

[0067] A multiplicity of modifications and variations of the exemplary embodiments above are possible so long as the scope defined in the appended claims is not departed from. For instance, the multiplicity of openings 28 or nozzles in the supply line 13 may be arranged in an azimuthal direction with respect to the midaxis (X). If the density of the arrangement of the nozzles is sufficient so that the opposite outer wall 18 is sprayed or is irradiated (liquid jet 30) comprehensively with the liquid to be sterilized in the region of the UV-C LEDs, and this also takes place with a sufficient strength, the rotatability of the supply line 13 and/or sections 24 may readily be omitted. It is also possible to spray only neuralgic regions in a static, non-rotatable arrangement of the openings 28 or nozzles. Full abrasion of the outer wall is not absolutely necessary.

[0068] Furthermore, an apparatus 40 for adjusting one or more nozzles may be provided in addition, which is adapted to selectively set up a spatially fanned-out liquid jet 30 with a comparatively large aperture angle or a strongly focused liquid jet 30 with a comparatively small aperture angle. This applies for both embodiments shown.

[0069] In addition, a sensor 42 which is configured to register a turbidity or a fluorescence of the liquid, which has flowed down on the outer wall, in the container 10 may be provided. A control apparatus 50 (represented only in FIG. 4) may advantageously be provided for this purpose, which is connected to the sensor 42, to the apparatus 38 for adjusting the pressure of the liquid in the supply line, to the apparatus 40 for adjusting the nozzle and/or the movable section, and which is configured to correspondingly adjust the pressure in the supply line 13, the aperture angle of the liquid jet 30 or the principal jet direction or the rotational speed as a function of the registered turbidity of the liquid.

[0070] FIG. 4 shows a further exemplary embodiment, with the aid of which possible feedback and repeated UV disinfection of the liquid may be carried out in order to further increase the quality of the sterilization. The container 10, shown in FIG. 4, of an apparatus for sterilizing a liquid may, with the features it contains, including the inlet 12 and the outlet 14, correspond substantially to the exemplary embodiments of FIGS. 2A and 2B or 3A and 3B. One particular feature here is a return line 56, which leads back from the outlet 14 to the inlet 12. This return line 56 allows batchwise operation. At the points of connection respectively to the inlet 12 and the outlet 14, the return line 56 branches off and is in this case controlled by 3-way valves 52, 54. In the return line 56, there may optionally be a pump 58 which drives the return flow. As an alternative, the pump 58 may also be positioned in the outlet 14 before the 3-way valve 54 in the flow direction, in which case the same pump may then be used for the return flow as well as for the through-flow operation (i.e. for pumping from the reactor).

[0071] The 3-way valves 52, 54 may be controlled by a control device 50 which also controls the apparatus 38, shown in FIG. 2A or 3A, for adjusting the pressure of the liquid in the supply line 13, the apparatus 44 for moving the supply line or the rotatable section thereof, the measurement with the sensor 42, and/or the apparatus 40 for adjusting the nozzle and/or the movable section. The control device 50 may also be connected to the pump 58 in order to maintain the return flow depending on a measurement result by the sensor 42 (for example transmission measurement or particularly also fluorescence measurement) until a desired measurement result is obtained, after which the 3-way valves 52, 54 are switched to through-flow. The position of the sensor 42 may also lie in the interior in the case of the fluorescence measurement, since the UV-C LEDs can deliver the necessary fluorescence excitation here. By fluorescence excitation (for example by the UV-C radiation source) and a sensor 42 sensitive in the UV-A, UV-B and/or visible range, the amount and possibly the nature of the contamination present may be deduced. In order to avoid erroneous measurements, the sensor 42 may be filtered in respect of the excitation light source so that the exciting UV-C radiation is thus not transmitted but is preferably reflected. The control device 50 may furthermore control the UV-C light sources 32 as well.

LIST OF REFERENCES

[0072] 10 container [0073] 12 inlet [0074] 13 supply line [0075] 14 outlet [0076] 16 interior [0077] 17 funnel-shaped section of the interior [0078] 18 outer wall of the interior [0079] 19 cylindrical section of the interior [0080] 24 rotatable selection of the supply line [0081] 28 opening for liquid jet, nozzle [0082] 30 liquid jet [0083] 31 liquid film flowing down [0084] 32 light sources, UV-C LEDs [0085] 38 apparatus for adjusting the pressure of the liquid in the supply line [0086] 40 apparatus for adjusting the opening/nozzle [0087] 42 fluorescence or turbidity sensor [0088] 44 apparatus for moving the supply line or the rotatable section thereof [0089] 50 control apparatus [0090] 52, 54 3-way valves [0091] 56 return line [0092] 58 pump [0093] G gravity [0094] P pressure generated in the liquid [0095] X midaxis (cylindrical interior)