Patent Application
20190389745
This disclosure relates to a device for irradiating a flowing medium with UV radiation, in particular for water disinfection, comprising a flow path for the medium, which is preferably laterally delimited by a cladding tube, and a gas discharge lamp which has a preferably annular lamp vessel, arranged coaxially with respect to the flow path and enclosing a plasma chamber for a lamp plasma that emits UV radiation, and an excitation coil for electrodeless inductive excitation of radiation of the lamp plasma.
DE 10 2015 218 053.0 discloses a UV radiation device for water disinfection. In this document, a dual-end gas discharge lamp having terminal electrodes is provided in a conducting tube, for subjecting the medium flowing on the outer side to UV radiation.
UV medium pressure lamps usually have a UVC yield between about 10% and 15%, at high power densities (electric power) of about 20 to 60 W/cm3 plasma volume, while UV low pressure lamps have a high UVC yield of about 30% to 45%, however with considerably lower power densities of less than 0.5 W/cm3.
This disclosure teaches a UV irradiation reactor for flowing media, which operates with high efficiency and which satisfies special requirements, in particular with regard to the flow geometry and the lamp excitation, by using an electrodeless lamp type.
Accordingly, according to a first aspect of this disclosure, it is proposed that a flow conduit body is arranged in the flow path, wherein the flow conduit body is adapted by virtue of its shape and/or position, to influence the flow of the medium for an even radiation absorption. This makes it possible to ensure that each volume element of the flowing medium passing through the lamp receives a substantially uniform radiation dose.
In this context, it is of particular advantage if the flow conduit body is arranged axially in an annular chamber of the flow path irradiated by the gas discharge lamp, and if the flow conduit body has an in particular spherical head piece, on which the medium frontally flows.
An added benefit for a detection and, if necessary, adjustment of the irradiation can be achieved by arranging a UV sensor for detecting an irradiation intensity of the radiation emitted by the gas discharge lamp in a region of the flow conduit body that is permeable to UV radiation.
The use of such a sensor can be further simplified in that the flow conduit body has an end portion guided into the region of a connection flange for the flow path, and in that the UV sensor is insertable and removable via the end portion.
A further aspect of this disclosure provides that the lamp vessel comprises a lamp extension communicating with the plasma chamber for adjusting the vapor pressure of a component of the lamp plasma, wherein a temperature control device (temperature controller) is coupled to the lamp extension for temperature adjustment. This also allows the radiation efficiency of the plasma discharge to be further optimized.
In a particularly simple embodiment, which remains largely unaffected by the alternating magnetic field for lamp excitation, the temperature control device has an air duct configured for the controlled supply of cooling or heating air to the lamp extension.
Alternatively or additionally, it is also conceivable that the temperature control device has a Peltier element and/or electrical heating element, which are thermally coupled to the lamp extension.
In this case, a self-sufficient solution can be realized, in that the tempering is supplied with electrical energy through a decoupling coil, wherein the decoupling coil absorbs the energy from the electromagnetic alternating field generated by the excitation coil.
A further aspect of this disclosure provides that at least one radiation reflector for reflecting UV radiation into the medium is arranged on the flow path upstream and/or downstream of the gas discharge lamp. As a result, radiation components emerging laterally from the lamp can be reflected several times, which leads to an increase in reactor efficiency, in particular in the case of very transparent media.
In this connection, it can also be advantageous if the radiation reflector, preferably embodied as a cylindrical cladding tube mirror, has a conductive portion, preferably containing aluminum and a non-conductive portion, preferably made of PTFE, wherein the non-conductive portion is positioned near the gas discharge lamp and the conductive portion is arranged further away from the gas discharge lamp.
According to a further aspect of this disclosure, it is proposed that the lamp vessel and the excitation coil are enclosed in a shielding housing designed to shield alternating electromagnetic fields, so that permissible EMC limit values can be maintained outside thereof.
In order to ensure additional protection in the event of a leakage or line break, it is advantageous if the shielding housing is tightly connected to a fitting for the passage of the medium.
A high irradiation efficiency can also advantageously be achieved in that the medium flows through and around the radially inner side and outer side of the annular gas discharge lamp.
The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.
The flow reactor 10 shown in
The gas discharge lamp 20 comprises an annular lamp vessel 28 made of quartz glass, which encloses a plasma chamber 30 for a low-pressure plasma formed from mercury and noble gas. The lamp vessel 28 communicates with a lamp extension 32 for adjusting the mercury vapor pressure, wherein a temperature control device 34 is coupled to the lamp extension 32 for temperature adjustment.
To increase the efficiency, a lamp mirror 36 can be introduced between the excitation coil 22 and the lamp vessel 28, which mirror reflects back the useful radiation into the plasma chamber 30 and is permeable to the alternating fields of the excitation coil 22. The lamp mirror 36 can be provided by applying a mirror layer to the lamp vessel 28.
The gas discharge lamp 20 can be operated with a very high electrical power of up to about 1 kW per 0.1 m of lamp length (measured in the flow direction). The plasma chamber 30 can have a radial extent of up to approximately 5 cm, while the guide tube 14 has a diameter of, for example, 30 cm. For special applications, miniaturized reactors 10 are also conceivable, for example with a total power of 100 W and a guide tube diameter of 1 cm. The separation of the medium or fluid to be irradiated (liquid and/or gas) by means of the guide tube 14 allows the thermal decoupling of the lamp vessel 28 and thus the achievement of the optimum operating point (for example, about 30 to 60° C. depending on the filling). It is also conceivable to cool the lamp 20 by means of the fluid itself and possibly also by additional active or passive cooling on the side of the lamp remote from the guide tube 14. In operation, a gas discharge occurs in the plasma chamber 30 with the emission of UV radiation, in particular UVC radiation at 253.7 nm, which is particularly efficient for the sterilization of liquids or fluids.
In order to reduce the fields radiated by the excitation coil 22 outside the reactor arrangement, a shielding housing 38 is provided. In the simplest case, depending on the operating frequency, this can consist of highly conductive metals such as aluminum or copper. If insufficiently conductive metals (cast iron, etc.) are used, it is possible to line or coat them with conductive layers on the inside of the housing. The shielding housing should be designed so that also a leakage of substances is prevented in case of a possible breakage of the guide tube 14 or lamp vessel 28. It must therefore be designed accordingly for the operating pressure and reliably seal with respect to the flanges 16, 18 by means of seals 40.
The UV sensor 26 allows the detection of the UV radiation intensity in a relevant spectral range for evaluating the radiation power output from the gas discharge lamp 20 directly into the flowing medium. This can be done by considering the transparency of the medium as well as the permeability of the guide tube 14 and possibly a depositing of soil on the guide tube.
The UV sensor 26 is expediently arranged in a fluid-tight holding portion 44 of the flow conduit body 24. In this case, the flow conduit body 24 may have an end portion 46, which is guided into the region of the connecting flange 18, via which the UV sensor 26 is inserted and removed.
In order to increase the irradiation efficiency, especially in the case of very transparent fluids, by backscattering, the holding section 44 is cladded by a UV mirror layer 48, which is interrupted or transparent to the UV radiation in the region of the sensor 26.
The flow conduit body 24 makes it possible to influence the flow of the fluid in such a favorable manner, that the flow velocity distribution allows a high reactor efficiency. This can be achieved by adjusting the flow rate at any location in accordance with the irradiation intensity, so that the fluid volume element flowing through the reactor 10 absorbs the same dose of radiation and this dose achieves a maximum value based on the lamp power used. This can also be achieved in that a strong turbulence through the flow conduit body 24 ensures a high mixing of the fluid.
As shown, the flow conduit body 24 can be arranged axially in the center of the flow and can be so large in diameter that the effective area through which fluid flows becomes smaller than the optical path length in a strongly absorbing fluid. For this purpose, the flow conduit body 24 is advantageously provided with an in particular spherical head piece 50 on which the medium flows frontally.
As shown in the block diagram of
The cooling and heating of a region in the appendix or lamp extension 32 is performed by means of a Peltier element 56 and an associated control unit 58 for electronic adjustment and temperature measurement. For heating, the switch 60 is closed, and for cooling, switch 62 is closed. For the regulation, a temperature sensor 64 is provided. Additional shielding may be implemented around the lamp extension 32, possibly preventing inadvertent heating of the mercury or amalgam induced by the magnetic alternating field in the cold chamber delimited by the lamp extension 32 (not shown). Typical optimal cold chamber temperatures are, depending on filling, approx. 35° C. (pure mercury-inert gas discharge) up to about 100° C. (Hg bound in amalgam).
A cooling/heating of the lamp extension 32 by means of tempered air flow is also possible in a simple manner since air and suitable air guide elements do not interact with the magnetic alternating field.
As illustrated in
The reflectors 66 which are positioned near the lamp should be made of electrically non-conductive materials (e.g., PTFE), and should not be absorbing (field weakening) for the working frequency of the alternating field. Otherwise, the magnetic field is changed unfavorably, which leads to a significant reduction in the overall efficiency of the arrangement.
Optionally, at some distance from the lamp (approx. corresponding to the lamp outside diameter), the reflector 68 may also be electrically conductive, in which case a high conductivity should ensure that the resulting eddy currents do not lead to high electrical losses. The advantage can be that even cheap aluminum mirrors can be used here. Furthermore, an electrically conductive reflector 68 shields the fields in the direction of the flanges 16, 18.
As illustrated in
In the embodiment of a flow reactor 10 shown in
While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 104 273.3 | Mar 2017 | DE | national |
This application is a continuation of PCT/EP2018/054924, filed Feb. 28, 2018, which claims priority to DE 10 2017 104 273.3, filed Mar. 1, 2017, the entire disclosures of each of which are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2018/054924 | Feb 2018 | US |
| Child | 16557795 | US |
