NL2005472C2 - DEVICE AND METHOD FOR PURIFYING A FLUID - Google Patents

Description

Device and method for purifying a fluid. The invention relates to a device for purifying a fluid, more in particular for purifying an aqueous liquid stream.

Various types of purification, in particular water purification, are known from practice. Many of these 10 methods use a membrane to filter a liquid. This is a relatively expensive product. A membrane is also relatively sensitive to contamination, whereby the process time in which the purification can be functionally used is reduced due to the required cleaning actions.

It is an object of the invention to counteract the above problems and to provide an effective and efficient purification of a fluid.

This object is achieved with the device for purifying a fluid according to the invention, the device comprising: - a container for the fluid; - electrodes placed in the holder operatively connected to an alternating voltage source; and - an ultrasonic wave generator placed in the holder.

By providing electrodes that are operatively connected to an alternating voltage source, an alternating voltage field (AC field) can be applied to the liquid that has been introduced into the container. A first purifying effect is hereby achieved. At least one ultrasonic wave generator is placed in the holder such that it is thereby possible to apply an ultrasonic field in the holder. A second purifying effect 2 is hereby achieved. It has surprisingly been found that a combination of the first stress field and the second ultrasonic field results in a high degree of purification of the liquid. This liquid preferably relates to water in which undesired components are present which must be purified therefrom.

The effects of the AC field and ultrasonic field reinforce each other. This is probably caused by the damage caused by the applied ultrasonic field to the cell walls, thereby enhancing the effect of the AC field on the core. Preferably, the fields are therefore at least partially overlapped. The container preferably comprises an inlet and an outlet for continuously flowing the container with the fluid in use. In this way a continuous process is obtained and the purification can be implemented effectively. This is accomplished by the effective purification achieved by combining an AC field and an ultrasonic field. A kind of flow-through reactor according to the invention can hereby be realized.

In an advantageous preferred embodiment according to the present invention, the voltage source comprises the frequency in the range of 1 kHz - 1 GHz, preferably 10 kHz - 1 MHz, and most preferably 100 kHz - 500 kHz.

It has been found that the alternating voltage in the said ranges, and preferably in the most specific range, leads to an effective first purification effect. The specific frequency depends, among other things, on the fluid and any impurities present therein.

It has been found that for the purification of an aqueous liquid stream a frequency of about 120 kHz results in an effective purification.

3

In a preferred embodiment according to the invention, the frequency of the ultrasonic sound produced by the sound source is in a range of 15 kHz-100 MHz and preferably 15 kHz-25 kHz, 25 kHz - 100 kHz, 100 KHz - 1MHz and / or 1 MHz - 100 MHz.

It has been found that in the frequency range of 15 kHz - 40 kHz the cell walls of microorganisms become permeable and that efficient and effective killing is achieved at higher frequencies. Moreover, it is possible to generate cavitation bubbles in the fluid at these 10 frequencies.

Ultrasonic sound in the context of the invention will be understood to mean sound with a frequency greater than 1 kHz, in particular greater than 10 kHz and more in particular greater than 18 kHz. The transition zone of "audible ultrasonic sound", which differs per person, is included in the term ultrasonic. In general, an upper limit of the frequency of ultrasonic sound is defined at 800 MHz. Sound with a frequency above 800 MHz is called hypersonic sound. In this text ultrasonic means both ultrasonic up to 800 MHz and hypersonic sound above 800 MHz.

In an advantageous preferred embodiment according to the present invention, the device comprises a direct voltage source for applying a direct voltage across the electrodes.

By applying a direct voltage field in the fluid, chlorine will be formed in the aqueous liquid stream, such as a waste water stream, which has an effective effect on the killing of, for example, microorganisms. This effect is enhanced by the use of an ultrasonic field with which the cell wall is damaged so that the chlorine becomes considerably more effective.

4

In an advantageous embodiment according to the present invention, the device comprises a UV source placed in the holder.

By providing a UV source, UV radiation can be introduced into the fluid. Such UV radiation has a direct effect on any impurities in the fluid to be purified. This radiation can directly damage DNA structures.

The device according to the invention is preferably provided with an X-ray source. X-rays have a killing effect on the microorganisms in particular. As for UV radiation, the effect of the X-ray radiation is enhanced by application in the ultrasonic field according to the invention.

Combining an AC field and an ultrasonic field brings about a reinforcing effect. Optionally combining these fields with one or more of DC, UV and X-ray results in a kind of hurdle approach with which contaminants such as microorganisms and algae run up against different barriers, the sum of which many contaminants are too many . This further enhances the purifying effect.

In a further advantageous preferred embodiment according to the present invention, the device comprises recirculating means for recirculating at least a part of the fluid.

By providing recirculation means, the fluid can be fully or partially recirculated.

A continuous process is hereby maintained and the degree of purification can additionally be influenced by controlling the degree of recirculation. An effective purification process is hereby obtained. The degree of recirculation can be made dependent on a degree of purification of the fluid, for example by measuring the amount thereof.

In an advantageous preferred embodiment according to the present invention, the device comprises active carbon particles arranged in the holder 5.

By providing active carbon particles, the effect of the AC field, in particular, is enhanced and the purification caused by this is improved.

In a further advantageous preferred embodiment 10 according to the present invention, the ultrasonic wave generator is provided as an inner tube placed in the holder.

By providing the ultrasonic wave generator as a kind of inner tube, it is placed in the fluid to thereby effect an ultrasonic wave field in the fluid in an efficient and effective manner. The inner tube can itself function as a transducer. It is also possible to provide transducers over the surface of the inner tube.

Preferably, this inner tube that forms the ultrasonic wave generator is also used as one of the two electrodes. With this, the AC field can be laid over the inner tube and the outer tube that forms the container or reactor. In this way the ultrasonic field can be effectively combined with the AC field.

The invention furthermore relates to a method for purifying a fluid, comprising the steps of: - providing a device as described above / - applying an alternating voltage field in the holder; and - applying an ultrasonic wave signal in the holder.

Such a method offers the same effects and advantages as those mentioned in the device.

Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which: - Figure 1 shows a view of a holder with an AC field; and Figures 2A and 2B show a view of a reactor according to the invention.

A system 2 (Figure 1) comprises a container or reactor 4 into which a liquid 6 has been introduced. Provided in the liquid 6 is a first electrode 8 and a second electrode 10 which are connected to an AC voltage source 14 by means of a circuit 12. Furthermore, in reactor 4 an amount of active carbon particles 16 is provided. A purifying effect for liquid 6 is hereby achieved in system 2. This effect is enhanced by the use of transducers provided on the wall of reactor 4.

In an alternative system 18 (figures 2A and 2B) 20, a flow-through reactor 20 is used with a reactor wall 22. Liquid flows via inlet 24 in a direction indicated by arrow A into reactor 20. In reactor 20, furthermore, an inner tube 26 with a tube wall is arranged. 28. In the embodiment shown, a number of transducers 30 are provided on a tube wall 28 for realizing an ultrasonic field. The electrodes are formed by tube wall 28 and reactor wall 22 which are connected with circuit 32 to an AC voltage source 34. This creates an AC field in the space B between reactor wall 22 and tube wall 28. Optionally, this field is combined with a direct current field.

A liquid stream is preferably continuously exposed to an AC field and an ultrasonic field. This combination of fields reinforces the effects for the purification of the incoming liquid. Optionally, these fields are combined with direct voltage and / or UV radiation and / or X-rays to further enhance this purifying effect. If desired, the continuous system 5 can be combined with recirculation of a portion of the liquid stream to further improve the purification.

The present invention is by no means limited to the above described preferred embodiments thereof. The requested rights are determined by the following claims within the scope of which many modifications are conceivable. For example, it is possible to treat a fluid other than water according to the present invention, such as a sugar solution, beer, blood or urine. Furthermore, according to the invention, it is possible to make combinations of the described measures.

Claims (12)

A device for purifying a fluid, comprising: 5. a container for the fluid; - electrodes placed in the holder operatively connected to an alternating voltage source; and - an ultrasonic wave generator placed in the holder. Device as claimed in claim 1, wherein the holder comprises an inlet and an outlet for continuous flow of the holder with the fluid during use. 3. Device as claimed in claim 1 or 2, wherein the voltage source comprises a frequency in the range of 1 kHz -1 GHz, preferably 10 kHz - 1 MHz, and most preferably 100 kHz - 1000 kH2. 4. Device as claimed in claim 1, 2 or 3, wherein the ultrasonic wave generator comprises a frequency in the range of 15 kH2 - 100 MH2 and preferably in the range of 15 kHz - 25 kHz, 100 kHz -1 MHz and / or 1 MHz - 100 MHz. 5. Device as claimed in one or more of the claims 1-4, further comprising a direct voltage source for applying a direct voltage across the electrodes. Device as claimed in one or more of the claims 1-5, further comprising a UV source placed in the holder. 30 7. Device as claimed in one or more of the claims 1-6, further comprising an x-ray source placed in the housing. Device as claimed in any of the claims 1-7, further comprising recirculating means for recirculating at least a part of the fluid. Device as claimed in one or more of the claims 1-8, further comprising active carbon particles disposed in the holder. Device as claimed in one or more of the claims 9-9, wherein the wave generator is provided in the holder as an inner tube. Device as claimed in one or more of the claims Ι-ΙΟ, wherein the ultrasonic wave generator forms an electrode. 15 A method for purifying a fluid, comprising the following steps: - providing a device according to one or more of the preceding claims; 20. applying an alternating voltage field in the holder; and - applying an ultrasonic wave signal in the holder.