Patent Description:
The problematic of liquidation of microorganisms by use of cavitation with a specially shaped nozzle and an entry body which increases efficiency of cavitation is solved in the file <CIT>, where, however, is not considered influence of low temperature plasma. In device, which is here described, comes to cavitation due to decrease of pressure behind narrowed cross section with consequent generation of super cavitation followed with not so extensive area of water vapor.

Higher efficiency in liquidation of microorganisms is reached with use of plasma technologies. The principle is that in the area of super cavitation are inserted electrodes with high voltage. By all so far known designs are electrodes placed in the way that the electromagnetic field has perpendicular direction to direction of flowing liquid.

There is known the whole range of technologies which are used for plasma treatment of liquids, possibly powder materials which are dispersed in liquid. These are mainly discharges working in atmospheric pressure. We can divide discharges into two groups either where the plasma is in direct contact with the liquid or not. As an example of discharges with direct contact of the liquid with the plasma is possible to mention for example jet discharges burning with regard to surface of the liquid or under its surface as is it described in the file <CIT>, various surface discharges on the surface of liquid mentioned in the documents<NPL>and LUKEŠ, P. , DOLEŽALOVÁ, E. , SISROVA, I. and ČLUPEK, M. , Aqueous-phase chemistry and bactericidal effects from an air discharge plasma in contact with water: evidence for the formation of peroxynitrite through a pseudo-second-order post-discharge reaction of H2O2 and HNO2, <NPL>, possibly diaphragm discharges which are described in the publication <NPL>, furthermore discharges in bubbles generated by gas flow described in the document PAW<IMG>AT, J. , HENSEL, K. and IHARA, S. , Generation of oxidants and removal of indigo blue by pulsed power in bubbling and foaming systems, Czechoslovak Journal of Physics, <NUM>, <NUM>(Supplement <NUM>), B1174-B1178, or by heat by electric current excited discharges described in the article <NPL>. Into the second category, thus the group of discharges without direct contact with the liquid we can list discharges above the surface of the liquid possibly discharges in multiphase systems of liquids where the liquid is dispersed into aerosol or vapor and the discharge burns in this aerosol as it is described for example in the section <NPL>. One from disadvantages is then for example impossibility of treatment of the liquids which do not withstand higher temperatures.

Use of above mentioned induced discharges is quite significantly limited also by a small interactive area of plasma in comparison with capacity of by plasma treated liquid. Moreover some discharges, especially jet discharges need for their operation expensive gases as are for example argon or helium and it is in reality possible only in technologies where is necessary to treat small amount of liquids with high added value of plasma treatment therefore these types of discharges are not usable by applications where are main criteria costs.

Problem of ignition of discharge in liquids is necessity of an exceptionally high intensity of electric field, more than <NUM> MV/cm for excitation of avalanche ionization which leads to electric breakdown. Practically is therefore used trick with generation of gaseous micro bubbles in the area of discharge whereby critical value of electric field breakdown decreases under 10kV/cm. When used ohmic heating the amount of energy used only for evaporation of the liquid and formation of bubble makeup up to <NUM>% of total input. Possible solution of this shortage is artificial pumping of gases in the form of micro bubbles into the liquid, namely either through a high voltage electrode or into the area of discharge space. Complication for ignition of the discharge this way is often high electric conductivity of the liquid which enables to reach break down intensity of the electric field only in capacity of only few bubbles. Consequently the resulting plasma is highly non-homogenous, filamentary and space restricted. This is solved through excitation of plasma in the form of HV pulse charging where the energy in pulse is enormous and thus is possible to create discharge in the bubbles. However pulse discharge has quite high costs connected with high purchase price of charging high-voltage pulse sources and also next significant costs especially for modification of this technology for higher capacities.

Generation of plasma in liquids is followed with sonoluminiscence which appears during implosion of bubbles of vapors in liquids where are these bubbles generated by high-frequency waves without external application of electric field which leads to production of plasma bubbles in size in order <NUM> and lifecycle around 100ps.

Analogic type of bubbles is possible to generate also with a fast flow of liquid through a suitably shaped contraction when appears so called hydrodynamic cavitation. In the articles <NPL> and <NPL> is described layout where the couple of HV electrodes is placed outside of shaped contraction whose electromagnetic field is perpendicular to direction of liquid flow in tube and in this way formed cavitation cloud they ignite intensive but space restricted plasma and herewith only comes to poor treatment of the liquid. The device which is described in the file <CIT> is always based on two electrodes (powered and grounding) which are present in the area of cavitation and furthermore it does not enable any inlet of gasses or solid powder into the area of plasma discharge. In the publication<NPL> [<NUM>] is mentioned design where was for formation of cavitation cloud used rotating cylinder with revolutions 7200rev/min. , also here were both powered electrodes placed directly in the cavitation cloud and resulting plasma was also strongly non-homogenous.

An example of treatment of fluids by the use of plasma discharge combined with cavitation occurring in a waist of the fluid flow is disclosed in: $.

An extreme example of formation of bubbles in liquids is then formation of foam which is a thermodynamically unstable colloid structure with high concentration of dispersed gas. This is therefore a two-phase system where the water is present in the form of a thin membrane which is separated by gas bubbles. The foam can be generated by whipping, gas pumping, shaking or vacuuming. All depends on characteristic of the liquid, temperature, pressure, presence of various surfactants and so on. In such foamy environment is possible to simply ignite the discharge and treatment of the liquid is highly effective up to 10x better than in above mentioned discharges. Disadvantage is then the necessity to supply big amount of gas, energy demandingness of foam production especially when characteristic of the liquid prevent generation of foam and furthermore not big suitability of usage in higher quantities.

The aim of the invention is to eliminate above described disadvantages of known designs and create such method of plasma treatment of liquids and a device for generation of low-temperature plasma in liquids which would be universally suitable for industrial plasma treatment of various types of liquids with wide variety of characteristic and conductibility including liquids with dispersed powders which would not need for right function high volume of working gas, would be energetically, spatially and investment modest, would generate plasma in the whole cross section of supplied liquid and would enable simple dimensioning and scaling up for various flows.

in a first aspect, the invention discloses a device for treatment of liquids according to claim <NUM>.

In a second aspect the invention discloses a method for treatment of liquids according to claim <NUM>.

Advantageous embodiments are disclosed in the dependent claims.

With presented invention is reached higher efficiency because when is used a full powered electrode the discharge is electrically excited in diluted vapors of the liquid without access of air which is advantageous for flammable liquids and dispersions. Also the plasma burns in super-cavitation from the powered electrode to capacity of the liquid and for different conductivities of the liquid is not necessary to optimize distance of the electrodes. Conductivity of the liquid has influence only on length of the zone with powered plasma namely at keeping of constant performance thus it is not necessary to optimize distance of the electrodes for given medium with various parameters. In case of use of a hollow powered electrode is possible to suck into the flowing liquid gas, reaction liquid or particles in form of powder which are then dispersed into the working liquid and consequently treated by formed plasma in super-cavitation. In case of use of even hollow grounding electrode is possible to treat also solid non-conductive materials in form of fibers or rods.

Particular examples of invention design are schematically illustrated in enclosed drawings where:.

The drawings which illustrate presented invention and consequently described examples of particular design do not in any case anyhow limit the extent of the protection which is defined by the claims.

The device for pursuit of the method of treatment of liquids consists, in basic design which is illustrated in <FIG>, of mutually in series connected a pressure regulator <NUM> and a cavitation tube <NUM> which is formed by in series on each other connected a cylindrical inlet chamber <NUM>, confusor <NUM>, cylindrical working chamber <NUM>, diffusor <NUM> and a cylindrical discharge chamber <NUM>. In the inlet chamber <NUM> is perpendicularly to the lengthwise axis of the cavitation tube <NUM> placed an electrode support <NUM> to which is fixed an oblong powered electrode <NUM> placed on the lengthwise axis of the inlet chamber <NUM> and reaches with its free end into the working chamber <NUM>, whereas the powered electrode <NUM> is electrically conductive connected with the electrode support <NUM> yet both elements <NUM> and <NUM> are from the body of the cavitation tube <NUM> electrically insulated. To the electrode support <NUM> is connected a high voltage source <NUM> by which is via the electrode support <NUM> powered the powered electrode <NUM>. In the discharge chamber <NUM> is placed the grounding electrode <NUM> by the help of which is grounded also the liquid flowing in the cavitation tube <NUM>. The circular shape of cross section of the cavitation tube <NUM> is not only possible design, as the cross section of the cavitation tube <NUM> can have arbitrary shape.

Alternatively are the electrode support <NUM> and the powered electrode <NUM> made hollow with formed common non-illustrated transit cavity which is open on one side out from the cavitation tube <NUM> and on the other side on free end of the powered electrode <NUM> reaches into the working chamber <NUM> as it is illustrated in <FIG>.

Another alternative is design of the grounding electrode <NUM> as a part of the shell of the cylindrical discharge chamber <NUM> as it is illustrated in <FIG>.

Another alternative which is illustrated in <FIG> is placement of an ejector <NUM> behind the discharge chamber <NUM>. The ejector <NUM> is formed by a supply chamber <NUM> which is connected to the discharge chamber <NUM> and a throat <NUM>. From the supply chamber <NUM> is sideways taken out a suction pipeline <NUM> which opens into the throat <NUM>. The ejector <NUM> can be alternatively substituted by a non-illustrated pump.

Alternatively is the grounding electrode <NUM> designed as an oscillating ultrasound powered tip which is connected to an ultrasound generator <NUM> as it is illustrated in <FIG>.

During pursuit of the method of treatment of the liquids according to the <FIG> is by the pressure regulator <NUM> kept such pressure value of the liquid which flows through the inlet chamber <NUM> into the cavitation tube <NUM> to enable, at the place of contraction, generation of cavitation or super-cavitation. The liquid is from the inlet chamber <NUM> taken to the confusor <NUM> where comes to significant increase of its speed and at the same time to decrease of the pressure, namely under pressure of saturated vapors. In this moment in the confusor <NUM> start to appear first bubbles which at high speed advance through the working chamber <NUM> where starts to generate cavitation. In the diffusor <NUM> comes, thanks to separation of a boundary layer, to next decrease of the pressure and significant extension of the cavitation zone which fills practically the whole space of the diffusor <NUM> and advances even into the discharge chamber <NUM> where comes to generation of cavitation cloud <NUM>. Possibly comes to generation of super-cavitation <NUM> when the liquid flows only through the central part of the discharge chamber <NUM> and around it is the space completely filled with super-cavitation medium as it is illustrated in <FIG>. By the high voltage source <NUM> whose frequency ranges between <NUM> to <NUM> is powered the powered electrode <NUM> through whose potential toward the grounding electrode <NUM> is generated electromagnetic field whose direction is parallel with the direction of liquid flow. Through this electromagnetic field are then powered the discharges of the plasma which burns in the whole area of the cavitation <NUM> or super-cavitation <NUM>.

In an alternative design when the electrode support <NUM> and the electrode <NUM> are made hollow, can be through the cavity, which is formed inside of them, supplied into the space of generation of the cavitation <NUM> or super-cavitation <NUM> gas or solid particles.

Claim 1:
A device for the treatment of liquids by the help of generation of an electrically powered discharge of low-temperature plasma in liquid environment where is, when the liquid flows, possible to achieve generation of cavitation or super-cavitation, said device comprising a pressure regulator (<NUM>) and a cavitation tube (<NUM>) mutually connected in series, the cavitation tube (<NUM>) is formed by an inlet chamber (<NUM>), a confusor (<NUM>), a working chamber (<NUM>), a diffusor (<NUM>) and a discharge chamber (<NUM>) mutually connected two by two, wherein the device further comprises a power electrode (<NUM>) placed in the inlet chamber (<NUM>) in its lengthwise axis in direction of liquid flow, the powered electrode (<NUM>) is by its free end reaching into the working chamber (<NUM>) and a high voltage source (<NUM>) to which the powered electrode (<NUM>) is electrically conductively connected wherein the powered electrode (<NUM>) is electrically insulated from the cavitation tube (<NUM>), wherein the device further comprises a grounded electrode (<NUM>) placed in the discharge chamber (<NUM>) and in electric contact with the liquid.