TECHNICAL FIELD

The method for purification of gas medium under atmospheric pressure, in particular atmospheric air, respectively the device for implementation of the method and the ultrasonic emitter for it will find application in equipment for purification of air under atmospheric pressure wherever it is needed, including in an urban environment, for example for household and technical use, in the industry, in closed spaces such as residential and office premises, and in specialized premises or mobile objects having isolated environment where it is necessary to maintain the air pure from organic and mechanical particles.

BACKGROUND ART

EP 3778033 Al describes an ambient air purification device based on an electrostatic method for collecting particulate contaminants from the air, and a method for its control. The electrostatic method comprises creating an electromagnetic field from a generating electrode and a trapping electrode oppositely arranged to each other. The method proceeds as follows: after switching on the generating electrode, a high potential difference is formed between the generating electrode and the trapping electrode, thus producing a corona discharge. The dust particles are then moved to the trapping electrode where they are collected and accumulated, thus achieving an air purification effect. The trapping electrode is capable of changing its position relative to the generating electrode, and provision is also made for its being composed of a plurality of structures spaced apart.

Disadvantages of the known solution are that, when applying the method in an urban environment, arc discharges are possible and shielding is necessary due to the risk of electric shock. Furthermore, at high concentrations of polluting particles its efficiency is low.

DISCLOSURE OF INVENTION

The problem to be solved is to provide a highly efficient purification of a gas medium by avoiding the possibility of arc discharges.

The problem is solved by a method for purification of a gas medium under atmospheric pressure, which includes creating an electromagnetic field between two electrodes, one of them being a generating electrode and the other one being a trapping electrode. According to the invention, a high-voltage pulse tension with a field intensity of at least 250 V/cm is applied between the electrodes and an ultrasonic field is simultaneously applied, creating a non-self-contained pulsed gas discharge, wherein water is injected into the gas discharge medium by sputtering. The electromagnetic field intensity being maintained until the desired purification is achieved.

It is recommended that the high-voltage pulse tension is within the range of 10 to 30 kV. The ultrasonic field has frequency of about 1MHz and power of 5 to 10 W. A device is also created for implementing the method for purification of a gas medium under atmospheric pressure, which includes a generating electrode and a trapping electrode arranged opposite to each other. According to the invention, the generating electrode is a high-voltage pulse electrode, connected to a high-voltage pulse generator, and the trapping electrode is grounded and implemented by at least one ultrasonic emitter connected via a matching unit to an adjustable DC source having an output stage to the matching unit. The output stage is also coupled to a setting generator. The high-voltage pulse generator is also connected through the matching unit to the setting generator. A differential amplifier and a normalizing amplifier are also provided in parallel to the matching unit, and are all connected to a control block.

It is recommended that the ultrasonic emitters of the trapping electrode be spaced at least 50 mm apart.

Suitably, the control unit shall include a gas contamination measuring device.

Optionally, the control unit is provided with a display.

The ultrasonic emitter unit formed comprises a housing having an opening with a support, in which housing, connected to the support, a metal sound reflector package is disposed having two cylindrical piezoceramic elements fixed thereto and a half-wave emitting concentrator, extending outwardly from the housing and centrally through the opening. It consists of a tubular element with walls in a hyperbolic curve, the front end of which is formed as part of a spherical concave surface at the most concave point of which there is a nozzle opening connected to a water supply pipe centrically and longitudinally arranged throughout the package and through the housing.

The spherical concave surface at the front end of the half-wave emitting concentrator has a radius of 500 mm to 1000 mm.

The metal sound reflector and the half-wave emitting concentrator are made from material with low coefficient of linear temperature expansion at 20°C a = (9- 10).1 O^/K.

Suitably, the material from which the metal sound reflector and the half-wave emitting concentrator are made, is kovar.

Suitably, as an embodiment, the material from which the metal sound reflector and the half-wave emitting concentrator are made, is titanium alloy.

The advantages of the method devised - when applied under atmospheric pressure and especially in an urban environment - consist in avoiding the occurrence of arc discharges (atmospheric lightning), which is due to the use of a non-self-contained pulsed gas discharge. The application of pulsed excitation of the gas medium allows to adjust the rate of increase of the ion concentration in the medium and to achieve balance between the shock ionisation and recombination under atmospheric pressure in highly efficient gas medium purification.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a block diagram of the device for implementing the method according to the invention;

Fig. 2 is a longitudinal section of an ultrasonic emitter according to the invention;

Fig. 3 is a general block diagram of a manufacturing embodiment of the device according to the invention.

EXAMPLES OF THE INVENTION EMBODIMENTS

According to the invention, a method is created for the purification of a gas medium, such as atmospheric air, which method is based on creating a non-self-contained pulsed gas discharge under atmospheric pressure. The method includes the following steps:

An electromagnetic field of at least 250 V/cm is created in the gas medium by applying a high-voltage pulse tension between electrodes, (one of them being a high-voltage pulse electrode 1 and the second one being a trapping electrode 2 which is grounded.) Simultaneously with the creation of the electromagnetic field, an ultrasonic field is applied to the gas medium, thus creating a non-self-contained pulsed gas discharge causing ionization of particles 3 commensurate with 0.001 mm and smaller.

Also simultaneously, water is injected into the gas medium by ultrasonic sputtering;

- Wherein the electromagnetic field intensity is maintained until the desired purification is achieved.

As a result, the ionized particles 3 entrain other contained fine particles to the trapping electrode 2, accumulating there.

The method avoids electrical breakdown by applying a quasi-steady state pressure change to the gas medium through the excitation of ultrasonic waves in the ionized area. The frequency of the sound field is matched to the lifetime of the ions formed. When synchronization of the ultrasonic field in frequency and phase with the frequency and phase of the electric field is achieved, the required amplitude of the excitation voltage is lowered.

The field intensity is not less than 250 V/cm, realized at a high-voltage pulse tension of 10 to 30 kV. Under these conditions the process of collection of fine particles in the ionized medium takes place. When the described process is carried out in a gas medium in a closed space, the concentration of fine particles decreases steadily. When additional contaminated gas medium, such as ambient air, from another space is introduced through the ionized area, the newly introduced air is purified as a result of the ionization process and the accumulation of fine particles, thereby significantly reducing the mass of newly introduced contaminants in the purified space.

For a stable non-self-contained discharge process, ultrasonic field frequency of about 1 MHz and power of about 5 - 10 W is applied.

A device for implementation of the method for purification of gas medium under atmospheric pressure has been designed, which puts into effect the power density of the electromagnetic field and is shown in the block diagram of Fig. 1. The device includes a generating electrode and a trapping electrode 2 arranged opposite to each other. According to the invention, the generating electrode is a high-voltage pulse electrode 1 connected to a high-voltage pulse generator 4. The trapping electrode 2 is grounded and is implemented by at least one ultrasonic emitter 5, connected via a matching unit 6 to an adjustable direct current source 7 having an output stage 8 to the matching unit 6, which output stage 8 is also connected to a setting generator 9. The high-voltage pulse generator 4 is also connected via the matching unit 6 to the setting generator 9. A differential amplifier 10 and a normalizing amplifier 11 are also provided in parallel to the matching block 6. These are all connected to a control unit 12. In a preferred embodiment, a gas contamination measuring device (not shown) is provided in the control unit 12 to switch the method implementation device on/off. Suitably, the control unit 12 has a display showing the results of the purification as well as other control information.

Typically, the trapping electrode 2 is composed of a plurality of ultrasonic emitters 5 arranged side by side at a distance of at least 50 mm.

Fig. 2 shows a longitudinal section of an ultrasonic emitter 5 designed for carrying out the method for purification of gas medium and for use in the device for carrying out the method. Irrespective of its specific purpose, it can also be used in other devices where necessary. The ultrasonic emitter 5 includes a housing 13 having an opening 14 with a support 15. A metal sound reflector package 16 with two cylindrical piezoceramic elements 17 fixed thereto, and a half-wave emitting concentrator 18 extending outside the housing 13 and centrally through the opening 14, is disposed within the housing 13 connected to the support 15.

In the experiments carried out, cylindrical piezoceramic elements 17 with a total size of 028 mm and a thickness of 20 mm were used. Their specific dimensions are determined by the properties of the piezoceramic elements 17 that are used in each particular case and may vary to achieve the required frequency and power of the ultrasonic field mentioned above.

The half-wave emitting concentrator 18 is a tubular element with walls along a hyperbolic curve, the front end 19 of which forms part of a spherical concave surface having a radius (R) of 500 mm to 1000 mm, at the most concave point of which a nozzle opening 20 is located. This nozzle opening 20 is connected to a water supply pipe 21 centrally and longitudinally disposed throughout the package and through the housing 13, as shown in Fig. 2.

The ultrasonic emitter 5 is grounded, the metal sound reflector 16 and the half- wave emitting concentrator 18 being made of material with low coefficient of linear thermal expansion at 20 °C, e.g. a = (9-10).10' ⁶ /K. This material may be, for example, kovar or titanium aloy.

The water supply tube 21 is provided for adjusting the conductivity of the gas discharge medium between the two electrodes 1, 2, which is accomplished by injecting a small amount of water into the gas discharge medium by sputtering. Thus, an advanced technology of electrical sputtering and ionization of water is realized. The water pressure is provided by a micro-pump 22 (Fig. 3), which enables the waterjet to be supplied in pulses. The micro-pump 22 is fed by a deionised water vessel 23.

The electrical supply of the ultrasonic emitter 5 has a common potential Earth with the high-voltage pulse electrode 1 and acts as a common anode.

The high-voltage pulse generator 4 produces positive pulses with amplitude of 30 kV and frequency of 500 - 1500 kHz, which is adjustable. The distance between the high-voltage pulse electrode 1 and the trapping electrode 2 (grounded) can be varied, and in the experiments carried out it was between 500 mm and 800 mm. The high-voltage pulse electrode 1 and the matching unit 6 in this example are connected to a split transformer, which allows the phase ratio of the electric and ultrasonic fields to be accurately adjusted.

With the electric and ultrasonic fields thus matched, conditions are created for a combination of appropriate micro-volume pressure and instantaneous intensity of the electric field applied to the gas medium, and an initial instantaneous concentration of current carriers is created, giving rise to an ion-electron current. Ionization of the gas medium to a hot arc discharge is avoided by termination of the electrical influence, which is accomplished by the control unit 12. Synchronously, the influence of the ultrasonic field is also terminated. The medium recombines. With a delay determined by the instantaneous value of the current between the electrodes, a further process of impact and ionisation begins. The process undergoes a steady state and adjusts to quasi-stationarity.

APPLICATION OF THE INVENTION

It is envisaged that the invention will be most commonly applied in practice to the purification of the air of residential and office spaces, and other use spaces from organic and mechanical particles. In the most commonly envisioned application, a frame is constructed comprising a high-voltage pulse electrode column and an opposing trapping electrode column in which frame the elements of the device for implementation of the method are incorporated. The frame is disposed in an open environment or in a room or, for example, in a suitable opening adjacent to outside air or in an opening between two rooms. The high-voltage pulse electrode 1 and the trapping electrode 2 are connected via the control unit 12 to a respective power supply as indicated above.

When the device is switched on, the method for purification of ambient air is carried out via its elements, all processes taking place automatically when the device is in operation. The accumulated fine particles shall be removed, where necessary, by any of the common approaches such as among other, vacuuming and washing.

In the experiments explained above, the following characteristics were achieved: length of the two electrodes - 650 mm, distance between the electrodes up to 800 mm. For safe operation, the high- voltage pulse electrode 1 and the trapping electrode 2 are preferably arranged in shielding channels, for example with a cross-section of 100x100 mm (not shown). Practically, the device set up for the implementation of the method operates as an ionization channel in a space of a gas medium, i.e., atmosphere. Suitably, depending on the volume in which the purification method and the device are used, a volume-appropriate number of devices arranged in a plane of the required calculable length are arranged. The distance between them shall be determined experimentally so as to ensure the purification of the specified volume.

The electrical consumption of one channel is about 220 W.