RU2395460C2 - Method of liquid decontamination by uv-radiation and device to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to decontamination of water or any other fluid. Proposed method consists in irradiating stationary or moving fluids by UV-radiation of semiconductor LEDs. Said radiation is introduced into fluid to be decontaminated with the help of flexible quartz waveguide is bent many times on radius r ≤ R_d, where R_d is band radius whereat conditions of complete disturbance of internal reflection for operating mode in the case of single-mode fiber or modes that carry major fraction of radiation in the case of multi-mode fiber. Proposed device comprises at least one UV-range LED and at least one flexible optical waveguide bent as described above.

EFFECT: reduced power consumption at sufficient radiation dose.

8 cl, 7 dwg

Description

FIELD OF THE INVENTION

The present invention relates to methods of bactericidal ultraviolet (UV) irradiation for disinfecting water or another liquid infected with pathogenic microbial flora in a predetermined volume (flow rate) and an appropriate device for implementing the inventive method.

State of the art

Water disinfection with UV radiation refers to non-reagent disinfection methods and involves the use of UV radiation sources, mainly mercury gas discharge lamps of low or high pressure, fed from the electric network through the appropriate ballasts, or based on electrodeless microwave gas discharge lamps fed directly by microwave energy .

It is known to use light emitting semiconductor diodes in the UV spectral range (UFSID) as UV radiation sources.

The disinfected effect of UV radiation is based on irreversible damage to DNA and RNA molecules of microorganisms caused by breaks or changes in the chemical bonds of organic molecules, which, in turn, are caused by photochemical reactions stimulated by absorbed radiant energy.

The degree of inactivation of microorganisms is proportional to the intensity and duration of UV radiation, or the dose of radiation.

It is known that, from an economic point of view, it is optimal to use UV treatment of liquid media with a higher transmittance and stable quality indicators; therefore, for the most complete and successful disinfection of liquid media, it is important to ensure uniform distribution of the required radiation dose over the entire volume of the disinfected medium.

The known method, where depending on the necessary bactericidal power, determine the number of sources of UV radiation and place them evenly in the space or volume of the disinfected medium, while the energy is supplied to the source of UV radiation from an external source of electrical energy, and the sources of UV radiation are placed in this way in order to isolate them from contact with the medium being processed, for example, in a contact chamber (source “Water Supply of St. Petersburg”, under the editorship of F.V. Karmazinov, St. Petersburg, publishing house “New Journal”, 2003).

Significant absorption of UV radiation by water leads to non-uniform illumination during external irradiation with UV sources and, as a result, different local disinfection efficiencies in the volume of water. Therefore, the known method is effective only in a thin aqueous layer. This requires a special organization of the shape of the water stream or the use of UV radiation sources with excessive power consumption. These factors lead to complication, appreciation and decrease in the effectiveness of the disinfecting effect of UV radiation. This leads to an increase in the required bactericidal power and, as a consequence, an increase in the number of UV radiation sources, and therefore, the total power consumption.

The specified method is implemented in most installations with submersible and non-submersible radiation sources, as well as in combined installations.

The most simple and low-power installations of pressure (with submersible sources of UV radiation) type consist of a housing in which UV lamps are placed, enclosed in a protective quartz case. Installations with submersible sources of UV radiation provide higher efficiency of the use of bactericidal radiation, but are structurally more complex, moreover, during their operation it is impossible to prevent contamination of the protective quartz cover.

Tray-type installations (with non-immersed sources of UV radiation) are simpler in design and operation, but have lower efficiency of using bactericidal power, and their depth is limited by the thickness of the water layer transparent to UV radiation. Combined installations combine the advantages of installations with submersible and non-submersible radiation sources.

As sources of UV radiation in the described devices, low-pressure lamps with a power consumption of 2-200 W and an operating temperature of 40-150 ° C are used, and high-pressure lamps with a power in the range of 50-10000 W at an operating temperature of 600-800 ° C . The bactericidal power of low pressure lamps does not exceed 30%, and high pressure lamps - 10% of power consumption. By the end of the lamp life (usually 5-15 thousand hours), their bactericidal power decreases.

A device is known that implements the above UV irradiation method from US Pat. No. 5,451,791 of 09/19/1995, where a device for disinfecting water is proposed. The installation is equipped with a camera in which the source of UV radiation is located - a traditional tubular mercury UV lamp fed through the ballasts from an alternating current main. In the same chamber, under the mercury lamp, there are UV-transparent pipes through which the water to be disinfected flows.

The disadvantages are the design complexity, the loss of scattering and absorption of UV radiation in the tubes, the need for preventive cleaning of the tubes from contaminants that absorb UV radiation.

Known patented devices for ultraviolet water disinfection, which use UFSID, for example, US patent 6,579,495, dated June 17, 2003. The device is a manual, portable device for disinfecting water with UFSID, which are powered by a rechargeable battery built into the device.

In this device for disinfecting water poured into a vessel, you should move the device manually, mixing the water, to ensure that UV radiation can reach the entire volume of water.

US Pat. No. 7,270,748, dated September 18, 2007, describes a device for the UV disinfection of running water integrated in a sanitary faucet. The invention is a device for disinfecting water with UFSID embedded in a spout of a sanitary kitchen or bathroom mixer. UFSID is poured into the compound and isolated from the water flow using a transparent channel.

In this device, water flows by gravity inside a space surrounded by a large amount of UFSID, which should provide access to UV radiation to the entire volume of flowing water.

However, the above method and devices for its implementation have common disadvantages:

- UV radiation sources are located in close proximity to the disinfected medium or even in contact with it; to isolate them from the treated volume of the medium, it is necessary to have a barrier or wall that is transparent to UV radiation;

- conductors for power supply of UV radiation sources also need good insulation, because the medium, for example water, itself can be a good conductor of electric current, in case of its penetration to uninsulated parts of electric circuits, it is possible to disrupt the operation of sources, short circuit the power source;

- each of the described devices cannot be used simultaneously for disinfection of stationary and mobile volumes of the medium;

- to increase the working volume subjected to disinfection, it is required to increase the number of sources of UV radiation, which leads to the complication and cost of devices based on them;

- as you move away from the source of UV radiation, the radiation intensity and disinfection efficiency decreases, therefore, to obtain the minimum necessary intensity at any point in the treated volume, it is necessary that it is excessive near the source of UV radiation.

Thus, the described method and devices do not provide a uniform radiation field in the disinfected space, require excessive energy resources, careful isolation from the environment, are structurally complex, inconvenient in operation.

SUMMARY OF INVENTIONS

To disinfect large volumes of the medium, a significant factor is the reduction in energy consumption (power consumption). One measure is to reduce the loss of power dissipation of UV radiation, as well as the use of UV radiation sources with higher performance.

In some cases, there is a need to guarantee electrical safety, for example, in household UV-disinfectants for drinking water, or to disinfect hard-to-reach volumes of the medium.

The objective of the present invention is to increase the effectiveness of disinfection by reducing the bactericidal power supplied to the disinfected environment, while maintaining the required radiation dose, expanding the application of the UV disinfection method, and also creating a device that implements the inventive method.

The technical result is to reduce the required power consumption of UV radiation sources, expanding the capabilities of disinfection with UV radiation.

To solve this problem and obtain the indicated technical result, the first object of the present invention proposes a method of disinfecting water or another liquid with ultraviolet radiation, which consists in irradiating a stationary or moving disinfectable volume of liquid by radiation of light-emitting semiconductor diodes in the ultraviolet range, characterized in that the radiation is introduced into the disinfected volume with using a flexible quartz optical waveguide, while the optical waveguide is bent or much fold bend radius r≤R _d ,

where R _d is the bending radius under which conditions are created for the violation of total internal reflection for the working mode in the case of a single-mode fiber or for modes that bear the bulk of the radiation in the case of a multimode fiber,

or the source radiation is introduced into an optical waveguide with an open surface of the waveguide.

As the disinfected volume, the volume of water limited by the volume of the vessel containing it or limited by the disinfected section of the pipeline can be selected.

In order to evenly distribute UV radiation, the optical waveguide is given a stable configuration taking into account the geometry of the treated volume, such a configuration can be formed using materials with shape memory.

Or waveguides can be fixed in a certain way on the surface of the pipeline, performed in the form of various spirals, etc. geometric shapes. For example, along the length of pipelines can be used waveguides, twisted in spirals.

Due to the fact that, as the distance from the radiation source along the length of the waveguide, radiation will be consumed (reduced), it is possible to locate ultraviolet radiation sources from opposite ends of the optical waveguide to ensure uniformity of radiation along the entire length of the optical waveguide.

To create the effect of impaired total internal reflection on the surface of the optical waveguide, one can apply a substance, for example, MgF ₂ , which creates a film transparent on the surface of the spectrum, the refractive index of which is less than the refractive index of the material of the optical waveguide, but greater than the refractive index of water.

An option to create protection against the formation of a sedimentary film is to treat the surface of the optical waveguide with a water-repellent substance transparent in the working region of the radiation spectrum.

To implement the method, a device is proposed that includes at least one ultraviolet light-emitting semiconductor diode and at least one flexible quartz optical waveguide, the optical waveguide having a portion with an open surface of the waveguide, or the optical waveguide is bent many times with a radius of:

r≤R _d

where R _d is the bending radius under which the conditions for the violation of total internal reflection are created for the working mode (in the case of single-mode fiber) or for modes that carry the bulk of the radiation (in the case of multimode fiber).

In order to uniformly distribute UV radiation and impart resistance to water flow, the optical waveguide has a stable configuration taking into account the geometry of the treated volume.

An option is the location of the light emitting semiconductor diodes of the ultraviolet radiation range from opposite ends of the optical waveguide.

The following detailed description is illustrated in the accompanying drawings:

Figure 1 depicts a variant of the device for implementing the method of disinfecting water with ultraviolet radiation using a single waveguide.

Figure 2 depicts a variant of the device for implementing the method of disinfecting water with ultraviolet radiation using a pair of waveguides.

Figure 3 depicts the shape of the arrangement of the waveguides along section AA according to a variant of the device using a single waveguide.

Figure 4 depicts the shape of the location of the waveguides along section AA according to a variant of the device using a pair of waveguides.

Figure 5 depicts a third embodiment of a device for implementing the method of disinfecting water with ultraviolet radiation using waveguides.

6 depicts the shape of the arrangement of the waveguides along section AA in the third embodiment of the device.

7 depicts the interface node of the optical fibers and light emitting diodes of the UV range.

The implementation of the invention

Figure 1 presents a variant of the device for implementing the method of disinfecting water with ultraviolet radiation using a single waveguide. This option is convenient for use in household mixers, i.e. when it is necessary to disinfect relatively small flows (volumes) of water. Such devices are effective for disinfecting the flow of water in pipes of small diameter.

The device operates as follows: to disinfect the flow of water in a small-diameter pipe — a household mixer (not shown), a flexible waveguide 1 is introduced through the spout of a household mixer, and a flange 4 with the opposite ends of the waveguide 1 and LEDs 3 fixed to it is mounted on the tap in the area pouring hole. The flow of water passes through the spiral of the waveguide, exposed to UV radiation, and exits through the spout. Power is supplied to the LEDs via cable 5.

Figure 2 presents a variant of the device for implementing the method of creating a field of ultraviolet radiation distributed in the disinfected volume of the medium using a pair of waveguides (1 and 2), with this arrangement two, three, four or more waveguides and, accordingly, the required number of sources can be used UV radiation (when the sources are located radially), depending on the required bactericidal power, which can be determined by the formula:

where D _PA is the dose of UV radiation equal to 165 J / m ² and necessary for inactivation of the most resistant bacteria Pseudom. Aeruginosa; d is the diameter of the pipeline, m; F is the flow rate of the medium (liquid or gas) through the pipeline, m ³ / s, η is a coefficient equal to 0.5 ... 1, taking into account the output of radiation from the waveguide and the uneven distribution of radiation over the irradiated volume.

Depending on the specific bactericidal power, the number of UV radiation sources is determined by dividing the obtained bactericidal power by the power radiated by one UV radiation source, P _s :

The number of waveguides is equal to the number of required sources when introducing UV radiation from one end of the waveguide and equal to half when introducing UV radiation from opposite ends.

It should immediately be noted that the drawings are purely illustrative and in no way limit the scope of the present invention.

5 and 6 show another embodiment of a device for implementing the method of creating a field of ultraviolet radiation distributed in the disinfected volume of the medium using more than one waveguide (1 and 2). With this arrangement, a sufficiently large number of both UV radiation sources and waveguides can be used, for example, when the sources are located both radially and along the entire length of the working section of the pipe 7. The interface unit 8 of the LED with the optical fiber is shown in Fig. 7, where Pos. 1 fiber guide, 3 LEDs, 9 nut, 10 insert, 11 frame, 12 o-ring from elastomer, 13 body are shown.

To ensure that UV radiation enters the disinfected environment in all cases, waveguides in the necessary sections of the waveguide or along the entire length create conditions for the violation of total internal reflection, which can occur:

- in the case of a change in the angle of incidence of ultraviolet or other radiation propagating in the waveguide;

- in case of a change in the ratio of the refractive indices of the fiber and the environment surrounding it.

In the first case, when the waveguide is bent, the angle of incidence of the radiation propagating through it changes. For the waveguide surface external with respect to the bend, the angle of incidence of the radiation decreases and, under certain conditions, can become less than the limiting α <α _pre . This circumstance will allow the radiation passing through the waveguide to go out into the medium that surrounds it.

In the second case, in order to create the effect of violation of total internal reflection, it is necessary to apply a film transparent to the ultraviolet region of the spectrum with a refractive index having an intermediate value between the refractive indices of water and silica glass, for example, a magnesium fluoride layer MgF ₂ . The film thickness should be approximately equal to d = λ / n4, where λ is the wavelength of the middle of the working range of the spectrum of the device. This will lead to a decrease in the limiting value for the angle of incidence at the quartz glass-film interface and to an increase in the limiting value for the angle of incidence at the film-water interface. The refractive index of water in the spectral region 214 ... 350 nm n≈1.38. The refractive index of quartz glass is 1.46. With the right choice of the refractive index of the film on the fiber, it is possible to achieve the release of light propagating through the waveguide into the environment, such as water.

Reducing the required power consumption, and therefore, expanding the capabilities of UV disinfection, is achieved by uniform distribution of UV radiation over the volume of the disinfected medium due to the configuration of the waveguide, as well as by the absence of the use of radiation on the external environment when using the LED and waveguide, as in the inventive device the path from the radiation source to the disinfected volume of water

The device versions for implementing the method of disinfecting water with ultraviolet radiation shown in Figs. 1, 2, 5 consist of waveguides 1, 2, which (in the first and second embodiment of the devices) can be used with an optical quartz optical fiber, and UV radiation sources. As the ultraviolet radiation source may be used a semiconductor light emitting diode 3 in the ultraviolet range, e.g. UVTOP ^® LED Company Sensor Electronic Technology, Ink.

In order to organize the exit of radiation from the waveguide into the water (FIG. 3, FIG. 4, FIG. 6), the waveguides are bent, for example, in the form of a spiral with a radius r≤R _d , where R _d is the bending radius at which the conditions for breaking the full internal reflection for the operating mode in the case of a single-mode fiber or for modes carrying the bulk of the radiation in the case of a multimode fiber. The bending radius can be estimated by the formula:

where n ₁ , n ₂ are the refractive indices of the core and cladding of the fiber, respectively, d is the diameter of the core of the fiber. The above formula is also true for a fiber with an open surface. In this case, n ₂ is the refractive index of water, and d is the fiber diameter of the fiber.

Another option is to use optical waveguides with an open surface of the waveguide (not shown), so the law of light refraction says that the ratio of the sine of the angle of incidence of light to the sine of the angle of refraction is equal to the ratio of the refractive indices of the media. See, for example, Computational Optics. Directory. Under the total. ed. Accident, prof. M.M. Rusinova. Leningrad, "Engineering", 1984.

When light passes from an optically denser medium with a large refractive index to a less dense one with a lower refractive index, the angle of incidence cannot exceed the limiting value α _before , since the sine of the angle of refraction cannot be greater than unity. If the angle of incidence of light is greater than the limiting α> α _pre , complete internal reflection occurs. In this case, all the energy is reflected in the first, more optically dense medium. The phenomenon of total internal reflection is used in various optical details and, in particular, in optical waveguides or optical fibers.

Claims (8)

1. The method of disinfecting a liquid with ultraviolet radiation, which consists in irradiating a stationary or moving disinfectable volume of liquid with radiation of light-emitting semiconductor diodes in the ultraviolet range of the spectrum, characterized in that the radiation is introduced into the disinfected volume using a flexible quartz optical waveguide, while the optical waveguide is bent or bent many times r≤R _d, wherein R _d - bending radius, wherein the disorders are conditions for total internal reflection working mode in case of single-mode fibers or modes for carrying the main fraction of radiation in the case of a multimode fiber. 2. The method of disinfecting a liquid with ultraviolet radiation according to claim 1, characterized in that as the disinfected volume, a volume of liquid is selected, limited by the volume of the vessel containing it or limited by the disinfected section of the pipeline. 3. The method of disinfecting a liquid with ultraviolet radiation according to claim 1, characterized in that the optical waveguide is attached with a stable configuration taking into account the geometry of the treated volume. 4. The method of disinfecting a liquid with ultraviolet radiation according to claim 1, characterized in that the radiation is introduced into both ends of the optical waveguide. 5. The method of disinfecting a liquid with ultraviolet radiation according to claim 1, characterized in that a substance is applied to the surface of the optical waveguide, which creates a film transparent on the surface of the spectrum, the refractive index of which is less than the refractive index of the material of the optical waveguide, but greater than the refractive index of the liquid e.g. magnesium fluoride. 6. The device for implementing the method according to claim 1, comprising at least one ultraviolet light-emitting semiconductor diode and at least one flexible quartz optical waveguide, the optical waveguide being bent many times with a radius of: r≤R _d , where R _d is the bending radius under which conditions are created for the violation of total internal reflection for the working mode in the case of a single-mode fiber or for modes that carry the bulk of the radiation in the case of a multimode fiber. 7. The device according to claim 6, characterized in that the optical waveguide has a stable configuration, taking into account the geometry of the processed volume. 8. The device according to claim 6, characterized in that the light-emitting semiconductor diodes of the ultraviolet radiation range are located at opposite ends of the optical waveguide.

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