EA000004B1 - Method of turbulence-pulverisation of materials (variants) and device for carrying out said method (variants) - Google Patents

Abstract

The invention relates to the turbulence-pulverisation of materials and can be used for the high-capacity fine pulverisation of poly-dispersed materials or as a mass-exchange device and chemical reaction-intensifier. The method is as follows: within the turbulence formed by streams of an energy-carrying medium introduced at an angle to the corresponding radius of the pulverisation zone, local concentrations of acoustical energy are created, each stream being pulsed at a frequency different to that of the other streams. The device comprises a chamber with means for feeding in the material, ducts for feeding in the energy-carrying medium, nozzles for discharging the end product, and gas-stream high-frequency oscillators. Each duct for feeding in the energy-carrying medium communicates with the chamber cavity via the corresponding gas-stream oscillator and the exit angle of the energy carrier stream relative to the corresponding radius of the chamber is 60-85 DEG . Each gas-stream oscillator can take the form of a slit nozzle and a coaxially arranged resonator between which is located an oscillating channel; one lateral wall of the resonator and one of the walls of the nozzle lie in the same plane. The resonators of the gas-stream oscillators can be tuned to various resonance frequencies or can contain high-frequency gas-stream oscillators each of which takes the form of an assembly comprising two units (nozzle unit and resonator unit).

Description

The invention relates to vortex grinding of materials and can be used for fine high-performance grinding of polydisperse materials in various industries for example: mining, chemical, construction, energy, food, medical.

From the prior art, a method of vortex grinding of material is known (USSR author's certificate No. 1282894, class B 02C 19/00, 1983.), including the introduction of a jet of energy carrier at an angle to the radius of the grinding zone bounded by the side and end walls, and the formation of a high-speed vortex, supply of the source material with the possibility of involving it in the vortex flow, the generation of gas-dynamic disturbances in the vortex flow at points located along the perimeter of the side wall and at the same angular distance from each other, and the target th product.

From [1], it is also known that a gas-dynamic device for vortex grinding of material, including a grinding chamber, equipped with a estrus for supplying the starting material with an energy supply pipe with an adjustable installation angle relative to the camera radius, a target product output pipe and vortex flow gas-dynamic disturbance sources made in Helmholtz resonators located tangentially to the chamber.

A common disadvantage of the above method and device for vortex grinding of material is low productivity. Due to the fact that the increase in productivity is inevitably associated with an increase in the overall dimensions of the grinding chamber and, as a consequence of the path traveled by the stream for one full revolution along its inner perimeter, a noticeable decrease in the average value of its speed occurs due to the flow, including due to increasing various kinds of energy losses. This reduces the kinetic energy of the particles, which leads to a decrease in the efficiency of their grinding, as well as to a decrease in productivity and achievable grinding fineness.

There is also known a method of vortex grinding of material (US patent No. 3648936, B 02 C 19/06, 1970.), including tangential input of energy jets at an angle to the corresponding radius of the grinding zone, limited by the side and end walls of the grinding chamber, with the formation of a high-speed vortex, feed source material into the chamber with its involvement in the vortex gas flow and the output of the target product.

From [2] it is also known a gas-dynamic device for vortex grinding of material that implements the method [2], including a grinding chamber equipped with means for supplying the source material, nozzles for supplying energy and a nozzle for outputting the target product.

The disadvantages of the known from [2] method and device is the low efficiency of fine grinding of polydisperse systems, since the dispersion of the source material occurs in a mode of stable rotational motion.

The technical problem solved by the invention is to increase the grinding efficiency and reduce the heterogeneity of the dispersed composition of the target product.

The problem is solved in that in the method of vortex grinding of the material, which includes introducing jets of energy carrier at an angle to the corresponding radius of the grinding zone bounded by the side and end walls, and forming a high-speed vortex, supplying the source material with the possibility of involving it in the vortex flow and outputting the target product, according to the invention, before entering the energy carrier jets into the grinding zone, a pulsating flow regime is created in them.

Preferably, the ripple frequency in each group of jets corresponds to a range of 50 - 500 Hz, and the ripple frequency in the second group of jets corresponds to a range of 1 5 - 25 kHz, and the introduction of jets with different ripple frequencies is carried out in an alternating sequence.

The problem is also solved in that the gas-dynamic device for vortex grinding of the material, containing a grinding chamber, equipped with means for feeding the source material, channels for supplying energy and a pipe for outputting the target product, according to the invention, further comprises high-pressure gas-jet emitters, with each channel energy supply is connected with the cavity of the grinding chamber through the corresponding gas-jet emitter.

In an embodiment of a gas-dynamic device for vortex grinding of material, it comprises a grinding chamber equipped with means for supplying the starting material, channels for supplying energy and a pipe for outputting the target product, and also, according to the invention, that it further comprises high-pressure gas-jet emitters, each of which is made in the form of a unit consisting of two blocks, one of which is nozzle, and the other is resonator, while the nozzle block is made in the form of a series of nozzles, hydraulically connected x between itself and an energy supply channel by collecting channel formed in the nozzle block and the resonator unit is configured as a series of resonators disposed opposite the nozzles. Between the nozzle and resonator blocks is located the output radiating channel in the form of a slit, the bottom of which is made in the form of a reflector of acoustic waves. In addition, gas-jet emitters should be located along the inner perimeter of the side wall of the grinding chamber and along its generatrix, while the resonators of each resonator block can be made adjustable, with the possibility of tuning to different resonant frequencies. Additionally, the resonators can be located in vertical rows along the wall of the grinding chamber, with a monotonic decrease in their resonant frequency in the direction from the top to the bottom of the grinding chamber, while the resonators in each block can have a different resonant frequency.

The advantage of the proposed method is that in the field of centrifugal forces of the vortex, under the action of which the dispersible material moves, local areas of increased and reduced pressures are created, under the action of the gradients of which local additional accelerations of particles falling into these areas occur. Local areas of high and low pressures are created in the volume of the grinding chamber due to the emission of ultrashort waves (VHF) into its cavity. As a result of this, a change in the trajectory of particle motion and their angular velocity occurs, leading to an increase in the frequency of collisions. In this case, the collision energy does not have time to dissipate, which leads to the accumulation of energy in the volume of particles and their transition to an elastic-stressed state. Upon reaching the critical limit of this state, the particles are destroyed. Further fragmentation of particle fragments occurs similarly to the above. In addition, due to the formation of the VHF field in the cavity of the grinding chamber, the particles absorb VHF energy with the simultaneous action of a periodic alternating load when they pass through areas of relative rarefaction and high pressures. This contributes to the multiplication and growth of microdefects of the internal structure of particles and their destruction.

The generated ultrasonic vibrations of various frequencies contribute to increasing the uniformity of the dispersed composition of the target products, because The absorption of acoustic energy by particles of different sizes occurs at different resonant frequencies. This is due to the fact that radiation of high frequencies is better absorbed by small particles, and by low frequencies by large ones. A wide range of VHF frequencies provides absorption of wave energy by all particles.

The location of the input zones, energy carrier (VHF sources) at the same angular distance from each other, provides a periodic pattern of changes in disturbing influences throughout the grinding zone.

The invention is further illustrated by drawings and a description thereof.

In FIG. 1 shows a gas-dynamic device for vortex grinding of materials, a longitudinal section; in FIG. 2 is a section AA in FIG. one; in FIG. 3 - an embodiment of the device (longitudinal section); in FIG. 4 is a section BB in FIG. 3; in FIG. 5 - section BB (embodiment); in Fig.6 is a fragment of section bb in Fig. 5 (axonometric projection); FIG. 7 is a fragmentary sectional view of FIG. 4 (embodiment of a gas-jet emitter); in FIG. 8 is a fragmentary view of FIG. 4 (embodiment of a gas-jet emitter); in FIG. 9 is a fragment of a section of FIG. 4 (embodiment of a gas-jet emitter); in FIG. 10 is a fragment of section BB in FIG. 5 (embodiment of a gas-jet emitter); in FIG. 11 is a fragment of section B-B in FIG. 5 (embodiment of a gas-jet emitter); in FIG. 12 is a fragment of section B-B in FIG. 5 (embodiment of a gas-jet emitter).

The gas-dynamic device for vortex grinding of materials contains a housing 1, mainly of circular cross section, with a power supply pipe 2 and a target product output pipe 3, a grinding chamber formed by the side wall 4 and the upper and lower end walls of the housing 1. The pipe 3 is in communication with the internal cavity of the grinding chamber. On the upper end wall of the housing 1, a coaxially grinding chamber, a glass 5 is fixed with a coaxial pipe b for supplying the starting material, installed with a gap a relative to the upper end wall of the housing 1. In the upper part of the glass 5, a discharge pipe 7 is tangentially mounted for outputting a particularly thin fractions of the target product. In the side wall 4, high-pressure gas-jet emitters are made, containing channels 8 for supplying energy, nozzles 9 and resonators 1 0. In the embodiment (see FIG. 4), the resonators 10 are equipped with movable pistons II for adjusting the resonant frequency, while the angle of the jets (conventionally shown by arrow 12) of the energy carrier relative to the corresponding radius of the side wall 4 of the grinding chamber is 60 - 85 <198>.

In an embodiment (see Fig. 5; 6; 10; 11; 12), the gas-dynamic device for vortex grinding of materials contains several nozzle blocks located along the inner perimeter of the side wall 4 of the grinding chamber and the same number of resonator blocks located opposite the corresponding nozzle blocks . Each nozzle block includes a collector 13, communicated on one side through channel 8 with an energy source (not shown conventionally in the drawing), and on the other hand with nozzles 9 located along the generatrix of the side wall of the grinding chamber. The resonator block contains resonators 10 tuned to different resonant frequencies and also located along the generatrix of the side wall 4 of the grinding chamber, while the resonant frequency of the resonators 10 is adjusted so that it decreases monotonically from the top of the grinding chamber to its bottom. Each resonator 10 of the resonator block is coaxially located opposite the corresponding nozzle 9 of the nozzle block. To increase the power of acoustic vibrations introduced into the working volume of the grinding chamber in the output radiating channels, made in the form of slots 15 located between the nozzle 9 and the resonator 10 blocks. The bottom of the slots 15 is made in the form of cylindrical reflectors 1 4, while in the preferred embodiment, the centers of curvature of the reflectors lie on a circle with a diameter equal to the difference: D - R, where D is the inner diameter of the grinding chamber; R is the radius of curvature of the reflectors.

In an embodiment (see Fig. 7), the axis of the nozzles 9 and the output channels 1 5 of the gas-jet emitters are located at an obtuse angle; in another embodiment (see Fig. 8), the nozzle 9 and the output channels are installed at an acute angle; in the embodiment of FIG. 9, the gas-jet emitter has two output channels 15 and 16.

In other embodiments depicted in FIG. ten; eleven; 12, possible embodiments of resonator blocks with different resonant frequencies are shown, wherein in FIG. 1 0 shows a block with different heights of the resonators, determined by the slope of the surface of the output channel 15; in FIG. 11 shows an embodiment of the resonator block in the form of a slit with a height-variable depth; in FIG. 1 2 shows the embodiment of the resonator block, the resonant frequency of which is given by the execution of resonators with different transverse dimensions.

The operation of the device that implements the claimed method is as follows.

Depending on the embodiment, the energy carrier under excessive pressure is either supplied through the pipe 2 to the cavity of the housing 1, or directly supplied to the channels 8 and then enters the cavity of the grinding chamber. As gas-dynamic emitters pass, the jets formed using nozzles 9 flow onto the corresponding resonators 1 0, as a result of the interaction of the jets with an obstacle (resonators), self-oscillations are excited in them and a pulsating flow regime is created. Expiring from the output channels 15, the energy source enters at an angle of 60-85 ° to the corresponding radius of the grinding chamber with simultaneous emission of acoustic waves into its working volume. Directed at an angle to the corresponding radius of the grinding chamber, the energy carrier jets create a vortex flow in the chamber, in which local regions with an increased concentration of acoustic energy are created due to acoustic waves. The processed material is introduced through the pipe 6 into the chamber, which is involved in the vortex motion, breaking down into particles interacting in the process of destruction, between themselves and with the walls of the grinding chamber. Due to local distortions of the vortex field inside the grinding chamber, there is a constant change in the trajectory of particle motion, which leads to an increase in the frequency of their collisions and their accumulation of internal energy in the volume of each particle. When the internal (elastic) energy of the particles reaches a critical value, the particle is destroyed.

VHF of various frequencies provide an increase in the homogeneity of the dispersed composition of the target product, since their wave energy is absorbed by both small and large particles. Theoretical and experimental studies have established that high-frequency radiation is absorbed predominantly by smaller particles, and small ones by larger ones. The VHF broadband frequency range provides resonant absorption of wave energy by particles of any (within reasonable limits) sizes. Dispersed target product is discharged through pipe 3 and enters the separation device.

In an embodiment, increasing the power of the generated VHF emitted into the grinding chamber volume is achieved due to the location between each nozzle and resonator blocks of the reflectors 1 4 with the direction of reflection of the VHF into the output channels 15, while in the preferred embodiment, the centers of curvature of the reflectors are located on circles with a diameter equal to DR, where D is the inner diameter of the grinding chamber; R is the radius of curvature of the reflectors.

An additional technical result that can be achieved by using this embodiment is that a disturbance in the vortex flow of the irradiated VHF is created with a certain frequency band based on the dispersed distribution of particles (dynamic classification by particle size) of the material being ground in the vortex flow vertical (camera height). It was experimentally established that in the lower part of the grinding chamber, larger fractions of the crushed material are mainly contained, and at the top, finer fractions. Lower gas-jet emitters generate sound vibrations of the lowest frequencies, the energy of which is effectively absorbed by large particles. Thus, the vertical spectral distribution of acoustic energy corresponds to the optimal absorption of its energy by 7 particles involved in the vortex flow, which leads to an increase in the efficiency of the device.

In other embodiments (see Figs. 7-9), depending on the physical and mechanical state of the material being processed, a particular variant or combination of embodiments of gas-dynamic emitters is selected. For example, when dispersing particularly hard, difficult to break materials, the emitter embodiment shown in FIG. 9 is advantageously combined with the emitters shown in FIG. 6, since in this embodiment a part of the radiation is directed towards the movement of the vortex flow. In this case, gas-dynamic emitters can be connected to a high pressure source both through the collector cavity of the housing 1 (see Fig. 1), and individually; the latter connection option is preferable for a mixed embodiment of gas-dynamic emitters, since in this embodiment, for efficient operation, it is necessary to provide various energy carrier flows through gas-dynamic emitters.

In all variants of execution, in the upper part of the grinding chamber, end currents of the energy carrier develop with small particles of dispersed material, which through the gap a enter the cavity of the cup 5 and are discharged through the pipe 7 for classification (if necessary) and separation.

The technical result from the use of the invention is expressed in increasing the uniformity of the dispersed composition of the target product, since the absorption of acoustic energy effectively occurs both in small particles of crushed material and in large ones. A wide range of frequencies of acoustic vibrations ensures optimal absorption of acoustic energy by all particles of the crushed material, which significantly increases productivity and reduces the energy intensity of the dispersion process. In addition, the scope of the proposed method and its implementing devices is greatly expanded, for example, the possibility of producing both hydrophilic and hydrophobic powders is easily realized; production of various pastes and utilization of harmful and environmentally hazardous industrial wastes.

An additional technical result, a significant increase in the efficiency of the device (when using the second embodiment of the gas-dynamic device) can be achieved with the most complete absorption of VHF energy by dispersible material. This is possible only if the generators are tuned in such a way that the generated VHF have such a spectral frequency distribution over the height of the grinding chamber that corresponds to the resonant frequency of the particles in the vortex flow at the corresponding level in the grinding chamber.