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INVENTION
Patent of the Russian Federation RU2131094

CAVITATION HEAT GENERATOR

The name of the inventor: Pischenko Leonid Ivanovich (UA); Merenkov Yuri Alexandrovich (UA)
The name of the patent holder: Pischenko Leonid Ivanovich (UA); Merenkov Yuri Alexandrovich (UA)
Address for correspondence: 107076, Moscow, ul.Stromynka, 19, building 1, ap. 24, Kazantsev Vladimir Sergeevich
Date of commencement of the patent: 1997.04.14

The invention relates to heat engineering and can be used in all branches of the national economy to produce a significant amount of thermal energy, in particular for heating (directly in pipelines) viscous liquids such as oil in order to reduce viscosity and improve rheological properties.

The primary area of ​​application of the invention is heating of civil objects and power supply of heat-intensive technological productions.

The technical result consists in the fact that the intensification of the process of liquid heating and the increase in the efficiency of the heat generator is achieved through the performance of a liquid flow accelerator in the form of a flow chamber with a supply branch pipe, a confuser and a branch pipe for draining the treated liquid. Inside the flow chamber, supercavitating blades mounted on the hub are installed The said blades along the outer surface are covered by a coaxial cylinder on the outer surface of which there is another group of supercavitating blades with the opposite direction of flow twisting, the inner group of supercavitating blades being fixed to the hub and the braking device being in the form of a flow interrupter with a drive located behind the working element Downstream, the branch pipe is connected to a heat accumulator, the output of which is connected to heat consumers and a network pump, the output of which is connected through the body to the branch pipe.

DESCRIPTION OF THE INVENTION

The invention relates to heating engineering and can be used in all branches of the national economy where it is necessary to obtain a significant amount of thermal energy, in particular, the invention can be used to heat (directly in pipelines) viscous liquids such as oil in order to reduce viscosity and improve its rheological properties. The primary area of ​​application of the invention is heating and power supply for heat-intensive technological processes.

From the prior art, high power heat generator designs are known, for example, in the centralized form of supplying heat-intensive industrial technologies and civil buildings and structures.

At present, heat pumps are increasingly used as heat generators ( see, for example, ac USSR No. 458691, 1972 [1] and Russian patent No. 2,045,715, 1993 [2] ). When working in these devices, the reverse cycle is performed, i.e. There is an absorption of heat from the environment with the subsequent transfer to its body with a higher temperature. Structurally, the heat pump contains a closed loop along the working body, which includes a device that circulates the working fluid, heat exchangers, devices that circulate in the circuits of the low-temperature coolant from the environment and the high-temperature coolant, the drive motor and control and monitoring devices. Heat, taken away from the environment, increases the overall efficiency of the heat installation, is summarized by the heat obtained from the conversion of electricity. The use of heat pumps for the purpose of heat supply is a promising direction in heating engineering. However, the efficiency of these units is relatively low, so they have not found wide application.

Known are the devices of heat pumps that use changes in the physical and mechanical parameters of the medium, in particular pressure and volume, to produce thermal energy ( see, for example, ac USSR No. 458691, 1972 [1] and Russian patent No. 2045715, 1993 [ 2] ).

In known devices, for example, a vapor-air mixture or liquid can be used as a medium. In these devices, by changing the pressure and the velocity of the medium, thermal energy is generated, which reduces the energy costs for obtaining heat.

The heat pump [1] , which functions as a heat generator, whose working medium is liquid-water, contains a body in the form of a sealed spherical vessel filled with a working medium with a heat exchanger located therein, a network pump that compresses the medium inside the housing, supply and return heating mains equipped with Shut-off valves, and heat consumer.

The main drawback of this heat pump is the very high working pressure developed in the case, which reaches 1000 atm . Such operating parameters of the installation present increased requirements for the strength of the body parts, shut-off valves and pipelines, which leads to an increase in the cost of the installation.

In addition, the use of a residential heating system is dangerous because of the high operating pressure.

For the prototype of the invention, the authors selected a thermal generator [2] , including a body with a cylindrical part, a liquid accelerator, made in the form of a cyclone, the end side of which is connected to the cylindrical part of the body. At the base of the cylindrical part opposite the cyclone, a braking device is mounted.

Due to the fact that the body of the heat generator in the lower part is equipped with a cyclone, the working fluid under pressure, tangentially entering it, runs in a spiral, and moves in the form of a vortex flow, the velocity of which increases; Then it enters the cylindrical part of the body, whose diameter is several times larger than the diameter of the injection hole, and then into the braking device. Such a design allows the body to reduce the speed and pressure of the medium, while in accordance with the known laws of thermodynamics, the mechanical energy of the fluid is changed to increase its temperature.

Increase the efficiency of heating the fluid contributes to an additional braking device installed in the bypass pipe. The pressure drop at the outlet of the brake device in the upper part of the housing due to the ratio of the outlet opening of the housing and the bypass pipe ensures the prevalence of the hot liquid flow over the cold one.

The known device [2] uses changes in the physical and mechanical parameters of the medium, in particular pressure and volume, to produce thermal energy.

The essence of the heat generator work according to the prototype is to accelerate the flow in the cyclone and stage-by-stage operation of the received kinetic energy on brake devices of various designs. However, the efficiency at each stage of kinetic energy activation is low, hence it follows that the overall efficiency can not be high.

The technical problem , the solution of which is directed to the invention, is the increase of efficiency due to the intensification of the process of liquid heating and the reduction of energy costs.

The solution of the task in view is provided by the fact that in a cavitation heat generator comprising a housing equipped with a liquid accelerator and a braking device, in accordance with the invention, the liquid accelerator is made in the form of a flow chamber with a supply branch pipe, a confuser and branch pipes for removing the treated liquid, In the form of supercavitating blades fixed to the hub, which are covered by a coaxial cylinder on the outer surface and supercavitating blades are located on the outer surface of the cylinder, the direction of twisting of which is opposite to that of the twisting of the flow by internal supercavitating blades fixed to the hub, the braking device being designed as a breaker Flow with the drive located downstream of the working element, the branch pipe is connected to a heat accumulator whose output is connected to a commercial heat consumer and a network pump whose output is connected through the housing to the branch pipe. Between the working element and the flow interrupter there is a liquid flow sampling device connected to an additional flow chamber inside which is installed an operating element providing a super-cavitation flow regime followed by an additional flow-drive interrupter along the flow path, the outlet of the flow chamber is connected through a hub with a hub And a collector covering the outer surface of the flow chamber having a perforation in the area of ​​the working element, in which a turbulator is arranged in the housing in front of the working member in the form of a flow interrupter with an actuator connected to the drive of an additional flow interrupter which is connected to the drive of the main flow interrupter . Between the network pump and the casing is placed a pre-actuated cavitation activator made in the form of a confuser, a flow chamber tangentially connected to the housing inside which a working element is mounted on the hollow hub; The hollow hub is connected to the heat accumulator mainly at the upper point. In the flow chamber, nozzles are installed downstream of the working element, preferably perpendicular to the flow direction, whose inputs are connected to the outlet of the network pump. The axes of the nozzles are arranged at an angle to each other. The actuator of the interrupter drives is connected via a regulator to a temperature sensor, one of the controller inputs being connected to the noise sensor behind the operating element. The turbulator, made in the form of a flow interrupter, is equipped with additional flow guides made, for example, in the form of plates mounted on the movable part of the interrupter at an angle to the incoming flow. The interrupter and the additional interrupter are connected in such a way as to ensure the displacement of the moment of the beginning of the pulses in the interrupters. The leading edge of the coaxial cylinders, on which supercavitating blades are installed, directed against the flow of liquid, is sharp, with a beveled inner surface made in the form of a smooth concave profile, and the leading edge of the hub facing the flow of liquid is sharp, with a bevelled outer surface made In the form of a smooth concave profile. At the output of the heat generator, in front of the heat accumulator, a pressure regulator is installed. All the units in contact with the liquid are made with an organosilicon coating.

THEORETICAL FOUNDATIONS OF THE PROPOSED CAVITATIONAL HEAT GENERATOR FOLLOWING

As we know, chemistry, besides substances and their interactions, also studies the interaction of energy and matter. As a rule, energy sources limit the possibility of researchers' influence on the reactivity of substances. The interaction of the electric current with matter proceeds over short periods of time and is characterized by high energy, whereas thermal interactions occur over large time intervals and at lower energies. The interaction of sound waves with matter makes available for studies by chemists such ranges of energies and time scales that are unattainable in other cases. The pressure necessary for the chemical reaction in a liquid is obtained by generating intense sound waves in it. Such waves create alternating regions of compression (condensation) and rarefaction, in which bubbles with a diameter of the order of 100 μm can form . When bubbles collapse (less than 1 microseconds), the gas contained in them can be heated to 5500 ^° C - this temperature is close to the surface temperature of the sun. For the first time the unusual effect of intense sound waves during propagation in a liquid - the region of phenomena related to ultrasonic chemistry (sound chemistry) - was discovered in 1927 . A.Lumis. The intensification of sound chemical research began in the 1980s shortly after the creation of inexpensive and reliable sources of ultrasonic oscillations of high intensity (with a frequency of more than 16 kHz , which is higher than the level of human auditory perception), ultrasound is now used in medical practice, in the industry for welding plastic parts and cleaning Materials and even in everyday life in alarm devices (warning of robbery), etc.

These applications, however, are not related to the chemical effect of ultrasound, which can, for example, increase the reactivity of the metal powder by more than 10 ⁵ times. It can give such a rapid relative movement of metal particles that they will melt in a collision. Ultrasound can create and microscopic "foci of flame" in a cold liquid. These chemical effects of ultrasound are caused by physical processes, through which gas and vapor bubbles arise, grow and collapse in the liquid. Ultrasonic waves, like all sound waves, include compression and rarefaction cycles. During compression cycles, local pressure rises occur in the liquid, which leads to the convergence of its molecules with each other; During the rarefaction cycles, local pressure drops occur, as a result of which the molecules are separated from each other. During the rarefaction cycle, a sound wave of sufficient intensity can generate bubbles. The particles of the liquid are held together by the forces of attraction, which determine its tensile strength. In order to form a bubble, the value by which the local pressure in the rarefaction cycle decreases, must exceed the strength of the liquid by rupture. The required value of pressure drop depends on the type of liquid and its purity. The breaking strength of an absolutely pure liquid is so great that the available ultrasonic sources can not create a pressure drop sufficient to form bubbles. For absolutely pure water, for example, a pressure drop of more than 1000 atm would be required , while the most powerful ultrasonic generators create a pressure of up to about 50 atm. However, the tensile strength of liquids decreases due to the gas "trapped" by cracks on the microscopic solid particles present in the liquid. This effect is similar to the reduction in strength caused by cracks in solid materials. In the region of reduced pressure, the trapped gas begins to exit from the cracks, forming a small bubble, passing into the solution. In most cases, liquids are quite heavily contaminated with dust and other solid impurities. In tap water, for example, bubbles are formed at a pressure of only a few atmospheres.

The bubble in the liquid is unstable: if it is large, it will float to the surface and burst; If it is small, it will be squeezed by the liquid and disappear. However, when interacting with an ultrasonic wave, the bubble will continuously absorb energy during alternating compression and rarefaction cycles. This interaction leads to the growth and contraction of the bubbles, disrupting the dynamic equilibrium between the vapor inside them and the liquid from the outside. In some cases, ultrasonic waves will support the existence of bubbles, causing only fluctuations in its size. In other cases, the average size of the bubbles will increase. The growth of the bubble is determined by the intensity of the ultrasound. Ultrasound of high intensity can lead to such a rapid expansion of the bubble in the vacuum cycle that it no longer shrinks in the compression cycle. Consequently, in this process, the bubbles can quickly grow in a single period of the ultrasonic wave.

In the case of low-intensity ultrasound, the bubble size oscillates in phase with the pressure during the vacuum and compression cycles. The surface of such a bubble during the rarefaction cycle increases somewhat in comparison with the compression cycle. Since the amount of gas diffusing into or out of the vial depends on the surface area of ​​the bubble, diffusion into the bubble during the rarefaction cycles will be somewhat greater than diffusion from it during the compression cycles. Consequently, for each period of the ultrasonic wave the bubble expands somewhat more than it contracts, and with time the bubbles will slowly grow. A growing bubble can gradually reach a critical size at which it most effectively absorbs the energy of ultrasound. This size depends on the frequency of the ultrasonic wave. At 20 kHz , for example, the critical size (diameter) of the bubble is about 170 μm . Such a bubble can quickly grow in one wave period. Once the bubble size has increased rapidly, it can no longer effectively absorb ultrasound energy. Without supplying energy from the outside, the bubble can not be. The liquid squeezes it, and it collapses. When bubbles collapse, conditions for unusual chemical reactions occur. The gases and vapors inside the bubble are compressed, intensively releasing heat, due to which the temperature of the liquid in the immediate vicinity of the bubble rises, and thus a hot micro region is created. Despite the fact that the temperature of this region is extremely high, the region itself is so small that the heat dissipates rapidly. According to the estimates of the University of Illinois at Erban-Champen, the heating and cooling rates of the liquid exceed 10 ^9o C / s . This corresponds to the cooling rate of molten metal when it is spilled onto a surface cooled to a temperature near absolute zero. Thus, at any point in time, the bulk of the liquid has an ambient temperature. The exact values ​​of the temperatures and pressures reached by bubble collapse are difficult to determine both theoretically and experimentally. However, these quantities are of fundamental importance in the description of sound chemical phenomena. For an approximate description of the bubble collapse dynamics, various theoretical models with different degrees of accuracy were proposed. The drawback of all these models is the impossibility of an accurate description of bubble dynamics in the final stages of collapse. The most complex models give temperatures of the order of 10 3 ^° C , ^{pressures of} 10 ² - 10 ³ atm, and a heating time of less than 1 μs . The temperature of the collapsing bubble can not be measured with a thermometer, since the heat dissipation occurs too quickly. One way to measure temperature is to determine the rate of known chemical reactions, since the temperature is related to the negative inverse logarithm of the reaction rate. If we measure the velocities of several different reactions that occur in the created ultrasonic medium, then we can calculate the temperature reached after the collapse of the bubble. In determining the relative velocities of a series of sound chemical reactions, D. Hammerton established the presence of two different temperature regions associated with the collapse of a bubble. The gas contained in the bubble reaches a temperature of about 5500 ^° C , while the liquid in the immediate vicinity of the bubble is 2100 ^° C. For comparison, the flame temperature of the acetylene burner is about 2400 ^° C. Although the pressure achieved when the bubble collapses is more difficult to determine experimentally than the temperature, there is a correlation between these two quantities. Thus, for maximum pressure, an estimate of 500 atm can be obtained, which is half the magnitude of the pressure in the deepest place of the World Ocean-the Mariana Trench. Despite the fact that the local values ​​of temperature and pressure, reached when bubble collapse is extreme, it is possible to successfully monitor the course of sound chemical reactions. The intensity of bubble collapse and, consequently, the nature of the reaction is influenced by factors such as the frequency of the ultrasonic wave, its amplitude, ambient temperature, statistical pressure, the nature of the liquid and gas dissolved in it.

The sound chemical processes in liquids depend mainly on physical effects during rapid heating and cooling caused by the collapse of the bubble. For example, it is proved that when water is irradiated with ultrasound by the energy of ultrasonic waves, water ( H ₂ O ) is split into highly reactive hydrogen atoms ( H ₂ ) and hydroxyl ( OH ) radicals. In a rapid cooling stage, hydrogen atoms and hydrosilic radicals recombine to form hydrogen peroxide ( H ₂ O ₂ ) and molecular hydrogen H ₂ . If other compounds are added to the water irradiated with ultrasound, many secondary reactions may occur in it. Organic compounds are strongly decomposed in such a medium, and inorganic compounds can be oxidized or reduced.

In some organic liquids, ultrasound irradiation results in physicochemical reactions. Thus, alkanes, the main components of crude oil, can be split into smaller fragments (for example, gasoline), usually for this, the crude oil is cracked when heated to a temperature above 500 ^° C. However, the treatment of alkanes with ultrasound causes their cleavage at room temperature, with the product of this process being acetylene, which can not be produced in sufficient quantity by simple heating. Perhaps the most surprising chemical phenomenon associated with ultrasound is its ability to create microscopic "foci of flame" in cold liquids, as a result of so-called sonoluminescence. This happens when a micro region with a high temperature arises when a bubble collapses in a liquid; Molecules in this region can be excited with transition to high-energy states. When molecules return to the ground state, they emit light. E. Flint in 1987 , found that ultrasonic irradiation of hydrocarbons gives an amazing result: the color of the emitted light is the same as the flame of a gas burner. The action of ultrasound on a liquid was also used to accelerate chemical reactions in solutions. The example of organometallic compounds containing metal-carbon bonds is especially indicative. This wide class of substances plays an important role in the production of plastics in the manufacture of microelectronic circuits and the synthesis of drugs, herbicides and pesticides.

In 1998, P. Schubert first investigated the effect of ultrasound on organometallic compounds, in particular, on pentacarbonyl iron Fe (CO) ₅ . The obtained results, when compared with the data on the effect of light and heating on Fe (CO) _5, indicate the originality of the chemical processes caused by ultrasound. When Fe (CO) _{5 is} heated, it decomposes into carbon monoxide (CO) and a fine iron powder that spontaneously ignites in the air. When Fe (CO) _{5 is} exposed to ultrasonic radiation, it first decays into Fe (CO) ₄ and free CO fragments. The Fe (CO) ₄ molecules can then be recombined to form the compound Fe (CO) ₉ . The collapse of the bubble leads to a different result. It is accompanied by the release of a quantity of heat that is sufficient to split several CO groups, but as a result of subsequent rapid cooling, this reaction stops before it is completed. Thus, when ultrasound acts on Fe (CO) ₅ , an unusual cluster compound Fe ₃ (CO) _{12 is} formed. The sound chemistry of two immiscible liquids, for example, oil and water, is determined by the ability of ultrasound to emulsify the oil in the liquid, as a result of which the microdroplets of one liquid form an emulsion into the other. Ultrasonic compressions and rarefactions of matter cause the accumulation of energy by molecules on the surface of the liquid, which subsequently overcome the adhesion forces that keep them in a large drop, then the droplet splits into smaller fragments, and gradually the liquid is emulsified. Emulsification can accelerate chemical reactions between immiscible liquids due to a strong increase in their contact surface. A large contact surface facilitates the penetration of molecules from one liquid to another - an effect, as a result of which certain reactions are accelerated. For example, the emulsification of mercury in various liquids leads to particularly interesting reactions; By A. Fry of the University of Wesley, who found that many mercury reactions with bromo-organic compounds represent intermediate stages of the formation of new carbon-carbon bonds. Such reactions play a decisive role in the synthesis of complex organic substances. Extreme conditions created near hard surfaces can also be used to impart chemical activity to "non-reactive" metals. For example, R.Johnson studied the reactions of carbon monoxide with molybdenum and tantalum, as well as with other metals, close to them in reactivity. For the formation of metal carbonyls, the usual methods require a pressure of 100-300 atm and a temperature of 200 to 300 ^° C. However, when irradiated with ultrasound, their formation can occur at room temperature and atmospheric pressure. The collapse of the bubble, in addition to all the effects described above, can be accompanied by the release of a shock wave into the liquid. The sound chemical processes on solid particles in a liquid are determined to a great extent by such shock waves, under the influence of which the microscopic particles of a metal powder come together at a speed exceeding 500 km / h .

Such collisions are so intense that they cause the particles to melt at the point of impact. This melting increases the reactivity of the metal, since it leads to the removal of the metal oxide coating (film). Such protective oxide coatings are found on most metals and are the cause of the appearance of patina on copper products and bronze sculptures. Since ultrasonic treatment increases the reactivity of metal powders, it also increases their catalytic activity. For many reactions, a catalyst is needed so that they flow at the required or even appreciable rate. The catalyst is not consumed in the reaction, but only accelerates the reaction of other substances. The influence of ultrasound on particle morphology, surface composition, and catalytic activity was investigated by D. Casadonte and S. Doktich . They found that under the influence of ultrasound, a sharp change in surface morphology occurs in such catalysts as nickel, copper, and zinc powders. The surfaces of the individual particles are smoothed out and the particles are combined into extensive aggregates. An experiment to determine the composition of the surface of nickel showed that the oxide coating is removed, and therefore the catalytic activity of the nickel powder is greatly increased. In general, ultrasonic irradiation increases the efficiency of nickel powder as a catalyst by more than 10 ⁵ times . Under such conditions, nickel powder is active as some special catalysts currently used, however it is not ignited and is cheaper.

Ultrasound is useful in almost every case where a liquid and a solid need to react. In addition, it can penetrate a large volume of liquid and is therefore well suited for industrial applications. In the future, the use of ultrasound in chemical processes should be very diverse. As for the synthesis of drugs, ultrasound can increase the yield of products compared to traditional methods.

However, the highest achievements in sound chemistry can be associated with the production of new materials with unusual properties. For example, the very high temperature and pressure reached during the reaction can lead to the synthesis of refractory materials (such as carborundum, tungsten carbide and even diamond). Refractory materials have high heat resistance and huge structural strength. They find an important use in the industry as abrasives and insertion tools with increased hardness.

Extremely fast cooling, accompanied by collapse of the bubble, can be used to create metal glasses. Such amorphous metals have an unusually high corrosion resistance and strength.

Although the chemical applications of ultrasound are still at the initial stages of development, in the coming years one should expect rapid progress in the field of sound chemistry. The use of ultrasound in laboratory reactions is widely spread, and the transfer of available technologies to industrial-scale reactions is apparently not far off. At the heart of the technologies being developed lie the latest achievements in the research of the chemical effects of ultrasound.

The effects given above (including cavitation) are caused by the action on the liquid medium of ultrasound, sufficient for the occurrence of these intensity effects. Despite all the splendor of the gamma achieved by the physicochemical effects of ultrasonic cavitation (or ultrasonic cavitation treatment), the following drawbacks are inherent.

All the results are achieved near the ultrasonic radiator, and as the radiator is removed from the radiator, the processing energy is sharply reduced, which prevents its wide application in industrial volumes. Hydrodynamic cavitation is analogous to ultrasonic cavitation in terms of cavitation cavity nucleation, its development and subsequent collapse, according to the effect exerted on the media in the zone of its action, and differs only in the nature of its origin, i.e. Kind of "emitter". However, this seemingly insignificant difference is significant, since hydrodynamic cavitation is characterized by the fact that the entire mass of the liquid participates in the processes of formation (development and collapse) of the cavitation cavities. Next, the term "cavitation flow regime of fluid" is used, which (in the authors' opinion) most fully characterizes the phenomena that occur, namely, conditions are created for generating cavitation bubbles that are close in diameter and independent of position relative to the "emitter"; Conditions are possible when the entire liquid is converted into cavitation bubbles. Obviously, this boundary condition is more than necessary. It is really enough that in the vapor phase (cavitation bubbles) pass about or slightly more than half the volume of the liquid, then when the cavitation bubbles collapse, there will be something to process. The number of generated bubbles can be determined by the volume of the cavity, where cavitation bubbles are collected. It was experimentally established that the diameter of the bubbles is approximately the same, which leads to a much larger (than with ultrasonic cavitation) value of the total energy released. The fact that the number of cavitation bubbles in hydrodynamic cavitation is many times greater makes the last conclusion undeniable.

The efficiency of cavitation treatment (of any nature) is determined by the specific energy of the cumulative microjets formed during the collapse of cavitation bubbles arising from the collapse of the cavity behind the cavitator ("emitter") multiplied by the number of cavitation bubbles.

It is believed that the specific energy of the cumulative jets is proportional to the square of their velocity, and the velocity directly depends on the square root of the pressure in the flow chamber. Thus, the dispersion energy is proportional to the first degree of pressure in the dispersion chamber, i. E.

To increase the energy of dispersion in cavitation systems, an expansion of the flow is provided by means of a diffuser. The maximum pressure increase in this case, even with unlimited infinite expansion of the flow, will tend to the value of the velocity head before expansion

And at a flow velocity in the flowing part, for example, v = 2 m / s , is P = 0.02 atm , and at v = 10 m / s P = 0.5 atm maximum.

More strictly from the point of view of the occurring physical and mechanical processes, the specific energy of the cavitation action of a single cavitation bubble can be represented by the dependence

Analysis of the above dependence, from the point of view of achieving the highest intensity of energy release, proves the need to achieve the largest values ​​of the maximum radius of the cavitation bubble formed and being prepared to collapse, and the increase in pressure in the collapse zone. However, these are mutually exclusive terms. With increasing pressure in the collapse zone, the bubble size decreases. When the pressure decreases, the bubbles are formed quite large, but because of the small difference in pressure inside and outside the bubble, the collapse does not take place vigorously.

To increase the hydrodynamic cavitation energy released by the "radiator", a pressure pulsation generator is used, made in the form of a flow interrupter consisting of a fixed disk and a rotating disk with radial windows. The installation of a flow interrupter behind the "radiator" (cavitator) along the flow path makes it possible to provide (at a large cross section of the interrupter) the growth conditions for larger microbubbles - with the interrupter open (and collapse) - when the breaker is closed (significantly increased pressure). This can be achieved only when the breaker is installed behind the cavitator in the course of the flow and is only characteristic of a cavitation mixer. This is one of the distinguishing features of this technical solution. The creation of pulsations with the arrangement of the means for creating pulsations to the cavitator leads to a change in the flow velocity of the liquid flowing onto the cavitator. This leads to a change in the size of the cavity formed behind the blades due to a change in the number of cavitation microbubbles, which provides some intensification of the mixing process. Changes in pressure behind the cavitator in the cavity do not occur, since the pressure behind the cavitator in the cavity under the cavitation flow regime is constant and equal to the pressure of the saturated vapor of the liquid, which does not depend on the speed of flow around the cavitator. Consequently, the specific energy generated in the cavitation flow regime must be represented by the dependence

It is obvious that the energy generated by the cavitation flow is directly proportional to the pressure in the collapse zone. Especially this dependence is manifested when cavitation treatment of liquids at a temperature approaching the boiling point. In this case, the difference ( P - P _np ) approaches zero, and consequently, no changes in velocity, velocity pulsations to the blades, changes in the profile of the blades, etc. They can not provide mixing conditions, i.e. Bubbles will be formed though large, but they either do not collapse, or the energy will be minimal (the physical meaning of what is happening is analogous to boiling water in a kettle). This issue has not been studied until now, but it is extremely relevant, as it opens new possibilities for a sharp intensification of the process of cavitation processing. When the breaker is instantly closed, a shock wave is generated that propagates against the motion of the dispersed medium at approximately the speed of sound in a given medium. The pressure at the front of the shock wave is determined by the formula of NE Zhukovsky : P ₂ = C V , where C is the propagation velocity of shock waves in the medium, - density of the medium; V is the velocity of the medium.

Even at a small flow velocity at the outlet v = 2 m / s, the pressure at the front of the shock wave is: P = 1550 · 100 · 2 = 31 atm.

Thus, if instead of the channel and diffuser expansion used, the shock wave generator is installed at the output, then the specific energy of dispersing will increase in

The motion of a shock wave with such a high pressure on its front towards the flow causes a very significant local compression of it. This phenomenon is used in the hydrodynamic cavitation treatment of liquids (of any nature and origin) at the boiling point.

In the light of the above, it should be clarified that in the proposed device, the brake device performs a new function - the power amplifier of the collapse of cavitation bubbles. In the case of known methods of achieving cavitation (including ultrasonic) - this is the way to increase the energy supplied to the "emitter". Hydrodynamic cavitation is characterized by an "insidious" feature that allows us to use the flow conditions of cavitators to create conditions for generating a large number of cavitation bubbles of large diameter. Let us dwell on some processes for the generation of cavitation bubbles. In the process of hydrodynamic cavitation, several stages are distinguished: the presence of the embryo of a cavitation bubble (the center of formation); The birth of a cavitation bubble; The growth of cavitation bubble size due to the pressure difference inside and outside the bubble; The growth of the dimensions of the cavitation bubble due to the forces of inertia is an inert state; Collapse of cavitation bubbles. Each stage is characterized by a negative implementation time or, more clearly, by the length of the cavern run. Obviously, the length of the cavity should be sufficient to complete all stages of the process.

Further, the task is to increase the flood of the cavern, i.e. Achievement of the required magnitude of the cavity midsider. This can be achieved by increasing the number of radiators, radiator grids, etc. Hydrodynamic cavitation here also opens up new possibilities for its use. Installation of a wedge-shaped blade along the axis of the stream, providing a twisting flow, generating the formation of microvortices, and hence the formation of an additional number of them. By enclosing the central blades along the outer diameter with the peripheral blades, the flow of liquid in the opposite direction is ensured and new areas of microvortices are generated, the interaction of which with the microvortices generated behind the blades mounted on the axis doubles the relative velocities of the microflows, which facilitates their interpenetration into each other and Provides a cavity filled with cavitation bubbles completely in the midsection. When the flow rate decreases, the intensity of microbubble formation decreases until cavitation disappears. The creation of a stable mode of cavitation in its developed stage with a change in performance can reduce specific energy costs. It is established that the organosilicon coating KNN -121 promotes partial wetting of the surface. This ensures fluid slip along the surface of the cavity blades. The appearance of these flow conditions made it possible to increase sharply, by 30-40% , the length of the cavity and the number of cavitation microbubbles, which provided a significant increase in the intensity of the process, completely eliminating the erosion of the mixer elements.

The best results were achieved with a coating thickness of 0.1 mm for the silicone coating KNN -121 . The tests showed the resistance of the KNN -121 coating in various media and variable temperatures. The intensity of erosion is directly proportional to the length of the cavern (a dimensionless parameter is usually used - the relative length of the cavern, which is the ratio of the length of the cavern to the diameter of the casing). The magnitude of erosion is estimated from the change in the mass of the cavitator over a certain period of time.

FIG. 1 shows a general view of a cavitation heat generator

FIG. 2 - flow interrupter

FIG. 3 is a view A of FIG. 2

Cavitation generator, contains a body 1, equipped with a liquid accelerator and a brake device; The liquid accelerator is made in the form of a flow chamber 2 with a branch pipe of the inlet 3, a confuser 4 and a branch pipe 5 for draining the treated liquid. Inside the flow chamber 2 there is installed a working element in the form of internal supercavitating blades 6 fixed to the hub 7 which are covered on the outer surface by a coaxial cylinder 8 on the outer surface of which there are supercavitating blades 9 whose direction of flow twisting is opposite to the direction of twisting of the flow by the internal supercavitating blades 6, Fixed to the hub 7, and the braking device is made in the form of a flow interrupter with a drive located downstream of the working element. The branch pipe 5 is connected to a heat accumulator 10 whose output is connected to a commercial heat consumer 11 and a network pump 12 whose output is connected to the branch pipe of the inlet 3. The flow chamber 2 is connected to a branch pipe 5 for draining the treated liquid through the diffuser 13. The mains pump 12 is connected to a branch pipe 3 through the confuser 14. The flow interrupter is made in the form of disks 15 and 16 with radial windows 17 and 18. The disk 15 is fixed and the disk 16 is mounted on the actuator 19 which is connected to the actuator 20. Between the diffuser 13 and the disk 15 A diaphragm 21 is installed between the working element and the flow interrupter. A fluid flow-taking device 22 is connected to the additional flow chamber 23 inside which is installed an operating element providing a supercavitational flow regime in the form of supercavitating blades 24 fixed to a hub 25 that are covered on the outer surface A coaxial cylinder 26. On the outer surface of the cylinder 26, there are supercavitating blades 27. In the flow chamber 23, the hub 25 is fixed by profiles 28, an additional flow interrupter equipped with a drive is installed downstream of the flow chamber. The interrupter consists of disks 29 and 30 with radial windows 31 and 32. The disk 29 is fixed and the disk 30 is mounted on the actuator 33. A narrowing is made between the disk 25 and the flow chamber 23. The output of the flow chamber 23 is connected by a line 35 through the housing 1 With a hub 7 made hollow and a manifold 36 surrounding the outer surface of the flow chamber 2 having a perforation in the area of ​​the working element, in which a turbulator is arranged in the housing 1 in front of the working element in the form of a flow interrupter with an actuator 37 connected to an additional A flow interrupter that is connected to the drive 19 of the flow interrupter.

The turbulator is in the form of disks 38 and 39 with radial windows 40 and 41. The disk 38 is fixed and the disk 39 is mounted on the actuator 37.

Between the network pump 12 and the housing 1 is placed a pre-actuated cavitation activator made in the form of a confuser 14 of the flow chamber 42 tangentially connected to the housing 1, inside which a working member is mounted on the hollow hub, the hollow hub 43 is connected to the heat accumulator 10, preferably at the upper point. The working element is made in the form of supercavitating blades 44 fixed to the hollow hub 43, which are covered by the coaxial cylinder 45 along the outer surface, and supercavitating blades 46 are located on the outer surface of the cylinder 45.

In the flow chamber 42, nozzles 47 and 43 are installed downstream of the working element, preferably perpendicular to the direction of flow, the inputs of which are connected to the outlet of the network pump 12 through the valves 49 and 50.

The nozzle axes 47 and 48 are arranged at an angle to each other. The actuator mechanism 20 of the interrupters is connected via a regulator 51 to a temperature sensor 52, one of the inputs of the regulator 51 being connected to a noise sensor 53 behind the operating element.

The turbulator, made in the form of a flow interrupter, is equipped with additional flow guides made, for example, in the form of plates 54 ( fig.3 ) mounted on the movable part of the breaker at an angle to the incoming flow.

The interrupter and the additional interrupter are connected in such a way as to ensure the displacement of the moment of the beginning of the pulses in the interrupters.

The leading edge of the coaxial cylinders 8, 26, 45, on which the supercavitating blades 9, 27, 46 facing the liquid flow are formed, is sharp, with a beveled inner surface made in the form of a smooth concave profile, and the leading edge of the hub 7, 25, 43 , Directed towards the flow of liquid, is made sharp, with a bevelled outer surface, made in the form of a smooth concave profile.

At the output of the heat generator, a pressure regulator 55 is installed, the output of which is connected to the actuator 56.

All the units in contact with the liquid are made with a silicon-organic coating, for example of the following composition: Al ₂ O ₃ - 10-40% by weight, asbestos 10-30% by weight, mica-muscovite 1-10% by weight, binder - The rest .

When the pump 12 is turned on, the liquid through the diffuser 14 enters the flow chamber 42 at a pressure of 4-8 atm , where the flow is separated. One part of the flow enters the blades 44, where due to the narrowing of the flow section and the swirling of the flow, the flow rate of the liquid increases and the pressure decreases. When the saturated vapor pressure is reached, a cavitation cavity is formed behind the blades 44, a field of microbubbles is formed in the tail part of the cavity. As a result of the collapse of the cavitation bubbles, fields of cumulative microjets with a velocity of the order of 10 ⁵ m / s and shock pressures up to 10 ⁵ atm arise.

In addition, due to the curling of the flow, microvortices are formed, contributing to the formation of cavitation bubbles. Another part of the stream enters the supercavitating vanes 46, behind which cavities arise, the latter interacting with the cavern formed by the vanes 44. Because of the multidirectional twisting of the flows, the microvortices and the resulting cumulative micro-jets and their impact interaction are mutually influenced and penetrated. The total cavern is characterized by a high intensity of formation of cavitation bubbles, microfrogs and microvortices. A portion of the liquid flow after the pump 12 enters the nozzles 47 and 43, which are oppositely directed. Interacting, the liquid jets form a cavity ( cavitation by the method of Academician L. Sedov ), which introduces additional non-stationarity into the main cavity and intensifies the process. In the case where the axes of the nozzles 47 and 43 are directed at an angle to each other, an additional twisting of the flow occurs and as a result, the unsteadiness of the cavity increases, which ensures an increase in the number of microbubbles. The total cavern through the branch pipe 3 enters the body 1, where the collapse of the cavitation bubbles ends.

Gases and vapors from the heat accumulator 10 are ejected into the hollow hub 43 and fall into the cavity. These gases are the centers of formation of additional cavitation bubbles and, in addition, deaerated hot water supplied to the commercial heat consumer 11, which reduces the corrosion of metal structures.

It is established that the greatest intensity of generation of cavitation bubbles is achieved when the flow of pulsating action imposed on the cavitation mode is provided, which is provided by the liquid flow interrupter. As the disk 35 rotates with the radial windows 41, the radial windows 40 of the disk 38 alternately overlap, resulting in a pulsation of the flow pressure. The greatest effect is manifested when the frequencies of pulsations of the cavity coincide with the working element in the flow chamber 42 and the pressure pulsations caused by the flow interrupter, i.e. At resonance of frequencies. Generation of heat occurs in this section of the heat generator and the liquid warms up. An additional unexpected effect was that in the area between the flow chamber 42 and the flow chamber 2, not all the bubbles completely collapsed, some of the gas did not dissolve in the liquid, i.e. Before the flow chamber 2, an activated liquid was formed, the activation of the liquid being manifested in two ways; The heated liquid more easily passes into the cavitation flow regime, but more importantly, the entire liquid is saturated with the active nucleating centers of the cavitation bubbles. The flow of liquid through the confuser 4, accelerating, enters the blades, where due to the narrowing of the cross-section and twisting, the flow rate increases and the pressure decreases. When the saturated vapor pressure is reached, a cavitation cavity is formed after the blades 6, a field of microbubbles is formed in the tail part of the cavity. As a result of the collapse of the cavitation bubbles, fields of cumulative microjets with velocities of the order of 10 ⁵ m / s and shock pressures up to 10 ⁵ atm arise. In addition, due to the curling of the flow, microvortices are formed, which contribute to the formation of cavitation bubbles (note the non-stationary character of the tail part of the cavity).

The other part of the liquid flow enters the supercavitating blades 2, behind which a cavity arises, the latter interacting with the cavity formed by the blades 6. Because of the multidirectional twisting of the flows, the cavitation microtunks penetrate each other and their impact interaction. In addition, microvortex interaction is observed. The total cavern is characterized by a high intensity of formation of cavitation bubbles, microfrogs and microvortices. The tail part of the total cavern and has a non-stationary character. It is established that the greatest intensity of heat generation is achieved when pulsation flow is applied to the cavitation mode, which is provided by the flow interrupter. When the disk 16 rotates with the windows, the radial windows 17 of the disc 15 alternate overlap, which results in a pulsating flow. The greatest effect is manifested when the frequencies of pulsations of the tail part of the cavern coincide with those of the flow pulsations, i.e. At resonance. In this case, the intensity of the cavitation noise is considerably increased, which is transferred to the mixer body and is perceived by the primary converter 53 (for example, a piezoelectric hydrophone). The analog output signal of the primary converter 53 is input to a secondary indicating and recording device 51 having a voltage regulating unit. As an engine 20, an induction motor with a squirrel-cage rotor with saturation chokes included in the stator network is selected. The intensity of the noise measured by unit 53 is converted to voltage and by means of regulator 51, the speed of the motor 20 is controlled by varying the rotational speed of the pulsator (hence, the frequency of the generated pulsations).

In Table. 1 comparative data ( with USSR AC 1083782 ) are given.

The zone of collapse of cavitation microbubbles is determined by direct measurement of the level of cavitation noise. In the collapsing zone, the noise intensity is the highest, and by moving the sound level meter along the flow section, the location of the collapse zone is determined. On the other hand, the collapse of cavitation bubbles occurs in the region of variation of the flow cross-section, namely in the region of the diffuser 13. At this point, the kinetic energy of the flow decreases with increasing potential energy. The flow rate decreases and the pressure increases, which determines the energy and the place of collapse of the cavitation bubbles.

The use of a chopper results in a pulsation of both the flow rate and the flow pressure and, very importantly, after the working element downstream. The cavitator and the incompressible fluid flow to the cavitator serve as a damper. After the cavitator, a liquid-gas medium is formed along the flow path, which is compressed. Thus, pulsations act on the cavity, causing an increase in the unsteadiness of the cavity, and intensify the collapse of the bubbles, and due to the compressibility they hardly affect the entire flow section (cavern).

The temperature meter 52 corrects the control signal of the controller 51, correcting the engine speed 20 when the temperature in the nozzle 5 changes.

The liquid pressure pulsations generated on the disc 15 act on the cavity formed behind the working element in the flow chamber 2 through the diaphragm 21. The diaphragm 21 plays a dual role: it also serves to create an increased pressure behind the flow chamber 2, and under the action of pressure pulsations by the disk 15 before Diaphragm generates secondary pressure pulsations. Thus, two volumes of liquid are formed between the flow chamber 2 and the disk 15, where shock pulsations of pressure occur, which greatly intensifies the process of collapse of the cavitation bubbles, and hence the process of heat generation. The heated liquid through the branch pipe 5 is diverted to the heat accumulator 10 from which it is supplied to the commercial heat consumers 11. At the outlet of the branch pipe 5, an actuating mechanism 56 is installed that regulates the pressure in the branch pipe 5. The control input of the actuator 56 is connected to a pressure regulator 55 controlling the pressure in the branch pipe 5. Thus, the total overpressure in the heat generator is maintained, which at all stages intensifies the process.

Between the diaphragm 21 and the disk 15, a fluid extraction device 22 is connected to the flow chamber 23. The liquid flows through the device 22 into the flow chamber 23 where the liquid flow is separated. One part of the fluid flow enters the blades 24, where, due to the narrowing of the flow section and the swirling of the flow, the fluid velocity increases and the pressure decreases. When the saturated vapor pressure values ​​reach the cavity 24, a cavitation cavity is formed, in the tail part of which a microbubble field is formed. As a result of the collapse of the cavitation bubbles, fields of cumulative microjets with velocities of the order of 10 ⁵ m / s and shock pressures up to 10 ⁵ atm arise. In addition, due to the curling of the flow, microvortices are formed, contributing to the formation of cavitation bubbles. Another part of the liquid flow enters the supercavitating vanes 27, behind which a cavity arises, the latter interacting with the cavern formed behind the blades 24. Due to the multidirectional twisting of the flows, the cavitation microstruks cross each other and their impact interaction. In addition, there is interaction of microvortexes. The total cavern is characterized by a high intensity of formation of cavitation bubbles, microfrogs and microvortices.

It is established that the greatest intensity of heat generation is achieved when pulsation flow is applied to the cavitation mode, which is provided by the flow interrupter. As the disk 30 rotates with the windows 32, the radial windows 31 of the disk 29 alternately overlap, resulting in a pulsation of the fluid flow pressure. The greatest effect occurs when the pulsation frequencies of the tail part of the cavity coincide with the pulsations of the fluid pressure, i.e. At resonance of frequencies. The heated liquid from the flow chamber 23 through the line 35 enters through the hollow hub 7 into the cavity behind the working element in the flow chamber 2. From the line 35 through the annular collector 36, liquid enters the cavity region outside it into the zone of intense heat generation. The liquid is heated in the flow chamber 23, the presence of unblocked bubbles and undissolved gases activates the fluid from which they enter the cavity through the axis and through the annular collector 36 from outside the cavity and create the conditions for further increase in the number of generated bubbles.

Thus, on the working element located in the flow chamber 2, the activated heated liquid is supplied to three areas: on the supercavitating blades 6 and 9; Hollow hub 7; Outside the cavity through the annular manifold 36, which creates the conditions for generating the largest possible number of cavitation bubbles and as a result of generating the maximum amount of heat.

Placing the plates 54 on the disc 39 at an angle to the incident flow provides additional flow turbulence behind the disk 39, thereby achieving a uniform distribution of the undissolved gases in the liquid and increasing its homogeneity. In addition, the arrangement of the plates 54 at an angle makes it possible to use part of the energy of the stream to rotate the fluid.

The displacement of the moment of the beginning of the pulses in the interrupters allows the maximum amount of activated liquid to be supplied to the flow chamber 2 at the time of overlapping of the windows 17 and 18, thereby increasing the pulsation amplitude.

Execution of the inner surface of the coaxial cylinders 45, 26, 8 in the form of a smooth concave profile reduces the hydraulic resistance of the cylinders, smoothly compress the flow to the axis, reducing friction against the cylinder wall. In addition, the hubs 43, 25, 7 with the outer surface in the form of a smooth concave profile form a stream, directing it to the blades 44, 24, 6, respectively.

The installation at the outlet of the heat generator behind the nozzle 5 of the pressure regulator allows, all other things being equal, to maintain the excess pressure necessary for intensive heat generation.

The use of silicone coatings to coat internal surfaces can reduce the energy consumption of a heat generator and increase the life of its work. The test data are summarized in Table. 2 . In Table. 3 shows the compositions of CPC (silicone coating).

In Table. 4 shows the parameters that determine the obtaining of a positive effect, depending on the composition of the coating. It should be noted that the initial erosion, even insignificant, leads to a chain reaction of destroying the cavitator.

Tests of the proposed coating showed its reliability and efficiency.

It should be noted that the known coatings are not resistant to wetting agents, which leads to intensive wear of the coating, and, in addition, the surface of these coatings is characterized by a roughness that adversely affects the efficiency of the cavitator.

At the same time, the proposed coating with an extremely high resistance to mechanical wear and high thermal stability and chemical resistance is distinguished by an increased smoothness. This increases the efficiency of work by increasing the length of the cavity at a constant flow rate.

The given composition of the coating made it possible to obtain the best operating conditions (i.e., to reach the maximum length of the cavity at a stable flow rate) of the cavitation heat generator with increasing mechanical strength and thermochemical resistance.

The industrial applicability of the proposed invention is assured, since its use significantly increases the efficiency of heat generation, especially in process plants with variable capacity.

CLAIM

1. Cavitation thermal generator comprising a housing equipped with a liquid accelerator and a brake device, characterized in that the liquid accelerator is made in the form of a flow chamber with a supply branch pipe, a confuser and a branch pipe for withdrawing the treated liquid, an operating element in the form of super-cavitating blades fixed On the hub, which are covered by a coaxial cylinder along the outer surface, supercavitating blades are located on the outer surface of the cylinder, the direction of twisting of which is opposite to that of the twisting of the flow by internal supercavitating blades fixed to the hub, and the braking device is in the form of a flow interruption with a drive located behind the working element Downstream, the branch pipe is connected to a heat accumulator, the output of which is connected to a commercial heat consumer and a network pump, the output of which is connected through the housing to the branch pipe.

2. Generator according to claim 1, characterized in that between the working element and the flow interrupter there is installed a liquid flow-taking device connected to an additional flow chamber, inside which there is installed a working element providing a super-cavitation mode, followed by an additional flow- The outlet of the flow chamber is connected through the body to the hub provided by the hollow and the collector covering the outer surface of the flow chamber provided with perforations in the area of ​​the working element, in which a turbulator is arranged in the housing in front of the working element in the form of a drive-driven interrupter, Interrupters of the respective flows are interconnected.

3. Generator according to claim 1 and 2, characterized in that between the network pump and the casing is placed a pre-actuated cavitational activator made in the form of a confuser, a flow chamber tangentially connected to the housing, inside which a working member is mounted on a hollow hub, the hollow hub is connected to a heat accumulator Preferably at the top.

4. Generator according to claim 3, characterized in that in the flow chamber behind the working element in the flow direction nozzles are installed perpendicularly to the direction of flow, the inputs of which are connected to the outlet of the network pump.

5. Generator according to claim 4, characterized in that the nozzle axes are arranged at an angle to each other.

6. Generator according to claim 1, characterized in that the actuator of the chopper drive is connected through a regulator to a temperature sensor, one of the controller inputs being connected to a noise sensor behind the operating element.

7. Generator according to claim 2, characterized in that the turbulator, which is made in the form of a flow interrupter, is equipped with additional flow guides made, for example, in the form of plates mounted on the movable part of the interrupter at an angle to the incoming flow.

8. Generator according to claim 2, characterized in that the interrupter and the additional interrupter are connected to provide a bias of the start of pulses in the interrupters.

9. Generator according to claims 1-8, characterized in that the leading edge of the coaxial cylinders facing the flow of liquid is sharp, with a bevelled inner surface made in the form of a smooth concave profile, and the leading edge of the hub facing the flow of liquid is sharp, With oblique external surface, made in the form of a smooth concave profile

10. Generator according to. 1 - 9, characterized in that a pressure regulator is installed at the output of the heat generator.

11. Generator according to claims 1 to 9, characterized in that all components in contact with the liquid are made with an organosilicon coating.

print version
Date of publication 08.11.2006gg

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