SU1066630A1 - Method of preparing finely dispersed mixes - Google Patents

Abstract

A method for producing fine-dispersed mixtures by creating cavitation in a liquid by rotating blades and simultaneously adding an additive component to the flow of cavitating liquid, which, in order to improve the mixing quality due to the impact of the shock waves, the cavitating liquid and / or the additive component, the exhaust gas is saturated with an exhaust gas caused by shock waves, cavitating liquid and / or the additive component. the flow of the mixture obtained is narrowed down to the formation of a jet of supersonic flow rate.

Description

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The invention relates to the mixing and emulsification of hardly stirred and viscous substances (water and oil, gasoline and bit 1m), the dispersion of solids (starch-containing raw materials, paints and varnishes) in a liquid medium in which cavitation cavities are formed, and can be used in chemical, food, pulp and paper and other industrial fields. A known method of producing fine mixtures by displacing a liquid or solid component with a flow of cavitating liquid, supplying the admixed components into the cavity and subsequent cavitation-cumulative effects due to micro- and macroturbulent eddies of high intensity that occur during the collapse of gas bubbles detached from the tail section. .. / -1 However, the degree of homogenization and dispersion, carried out in this way, may be insufficient for hardly mixed Vep1, eats . There is also known a method of obtaining fine mixtures by creating cavitation in a liquid by rotating blades while simultaneously feeding additional component 2 into the flow of cavitating liquid. The cavitation-cumulative effect (effects of cavities) in this case is enhanced by turbulent displacement of QMexi. This increases the degree of homogenization and dispersion, but to an insignificant degree, since the possibilities of intensifying the displacement process due to the formation of shock waves in the mixture are not used. The aim of the invention is to improve the quality of mixing due to the impact of shock waves. This goal is achieved in that according to the method of obtaining fine mixtures by creating cavitation in a liquid with rotating blades while simultaneously feeding an additional component into the flow of cavitating liquid, the cavitating liquid and / or additional component are saturated with gas, after which the resulting mixture stream is narrowed to form a supersonic jet expiration The method is implemented in a device comprising a shaft located in a housing cavity with blades mounted on it having a supercavitating profile, nozzles for supplying fluid and an additional component, a jet former located in the housing cavity, made in the form of a nozzle of a supersonic profile, with a pre-cavity cavity communicating with the nozzle housing through which gas is supplied. The jet former can be formed by the constriction of the M body and / or the shaft extension. FIG. Figure 1 shows schematically a device implementing the proposed method, a longitudinal section; in fig. 2 is the same embodiment; channel in the blades x attached to the shaft; in fig. 3 - the same, the embodiment of the additional blades attached to the body; pas figs. 4 execution of the jet former in the form of a local expansion of the shaft; in fig. 5 the same, in the form of a local narrowing of the body; in fig. 6 is a section AA of FIG. 1 (form of supercavitating profile of the blades); in fig. 7 - dependence of particle size on the number of revolutions of the shaft with blades; in fig. 8 dependence of particle size on the processing time. An apparatus for carrying out the method for producing fine mixtures comprises a shaft 3 located in the cavity 1 of the housing 2 with blades 4 fixed on it, and a supercapture profile forming caverns 5; and a jet spreader in the form of a nozzle of a supersonic profile, formed by local narrowing 6 of housing 2 and local widening m 7 of shaft 3. Preheated cavity is connected through hole 8 in housing 2 with a valve device 9 for supplying the additional component and gas ( Fig. I) through the hole 8 and the channels 10 of the zlo) 7asg x 4 and the shaft 3, respectively, with the device for feeding the component to be mixed and GGS (Fig. 2 and Fig. 3). In case 2, blades 11 with a supercavcating profile can be fixed. The function of these blades is to prevent the fluid from moving into rotational motion by the rotor blades, as well as to promote the intensification of the mixing process. The jet former may be shaped by localizing 7 of the shaft 3 and the surface of the body 2 is inappropriate ;. narrowing 6 of the housing 2 and the surface of the shaft. The fluid flow enters the housing 2 and moves along the blade 1 due to the rotation of the blades 4 of the shaft 3. At the same time, cavitation cavities 5 are formed behind the blades 4 and 1. The mixed veins and / or gas (air) enters the tail part of the cavities through the tail) stn 8 and channel 10. The tail portions of the caverns, which are entrained in the constricted part of the nozzles, are crushed on microbubbles, when the coalescence collapses, MtJKpocTpyH accumulation is formed by high energy. The occurrence of an outflow through a nozzle, the shock waves enhance the cavitation – stimulative effect on the mixture. The physical effect of the formation of shock effects is that the speed of sound of a 3 2-phase gas-liquid stream containing gas vapor bubbles, separated from the cavities, ranges from 8 to 15 m / s. Due to the low speed of sound in a hyzryk medium, the achievement of a gatienium flux in this narrow section of the nozzle becomes quite possible. Exceeding the velocity of the outflow of a bubble flow over the speed of sound in a 2-phase medium leads to a supersonic outflow and the appearance of shock waves. The physical essence of the shock waves themselves is that at the front of the moving shock wave all parameters of the fluid flow undergo a break - pressure, density, speed. The gap is a sharp change in the value of the parameter. An abrupt change in pressure, density, and speed causes intense dispersion and mixing of the components. The effectiveness of the impact of shock waves is very significant and significantly enhances the cumulative effects. The reflection of waves from the hull and solid surfaces causes their superposition and the overall efficiency of the dispersion and mixing process increases further. The table shows the comparative indicators of the degree of dispersion obtained by the known (cavitation-cum, / C3 (/ haime and / and oem) and / ff / WC / 7fr 2Q 25 phage.

Srig.Z l tpvnym) and proposed (with shock waves) methods (fat -f water - the original components). Of great importance is the coordination of the operating modes of the supercavitating device with a supersonic nozzle. FIG. 7 and 8 show as an example the characteristic dependences with a fat content of 3.1% and 36 ° C. With other parameters: fat content of 2.5-3.5% and 25-40 ° C, the character of dependencies does not change, only a slight shift is observed with respect to the axes. From FIG. 8 it follows that after a certain time has been reached, the average diameter of the fat globules remains practically unchanged. The change in treatment time is achieved by recirculating the flow. From FIG. 7 it follows that with some modes of rotation of the blades, the results are worse. There is a maximum corresponding to speeds of 20003000 rev / MiiH, which are listed in the table below. 2. At these speeds, fat globules are smallest. Thus, the proposed method can significantly improve the quality of the mixture with a short duration of the mixing process.

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Claims (2)

METHOD FOR PRODUCING THIN-DISPERSE MIXTURES by creating cavitation in a fluid by rotating blades with the simultaneous supply of an additional component to the cavitated fluid stream, characterized in that, in order to improve the quality of mixing due to the action of shock waves, the cavitated liquid and / or additional component is saturated with gas, after whereby the flow of the resulting mixture is narrowed to the formation of a jet of supersonic flow rate. liquid component 3 _Λ Mixture