RU2111044C1 - Method for separating two-phase mixtures - Google Patents

Abstract

FIELD: environmental control; cleaning of gases from aerosols; cleaning of liquids and condensate from suspended matter. SUBSTANCE: mixture to be separated into two individual phases is admitted into cleaning chambers arranged above surface of filtering element, followed by turbulizing admitted medium to such a point as to form vortex intended to clean filtering element from any adhering matter. Then portion of fluid medium laden with non-separable matter is again passed through filtering element, while remaining portion of it carrying separable matter is discharged from filtering element. EFFECT: higher efficiency. 5 dwg

Description

 The invention relates to the separation of two-phase mixtures containing a fluid, gas or liquid medium mixed with liquid or solid particles.

 The invention can be used in the purification of gases from aerosols or condensate and liquids from suspensions, in the separation of particles included in the mixture, by size, when thickening dust gases and suspensions.

 A known method of separation of two-phase mixtures, in which the mixture is fed to the filter element, part of the fluid is passed through the filter holes of the element, and the rest of the medium with detachable particles is removed from the filter. The main disadvantage of this method is the difficulty of removing sediment with filter elements.

 Known bag filter (ed. St. N 309716), having dust extraction holes in the bottom of the sleeves. Sleeves are cleaned of dust by blows of cords suspended in the sleeves.

 Also known is a continuous thickener filter thickener with rigid filter elements (ed. St. N 978892). In this filter, the precipitate is removed from the elements by flushing it with a suspension stream.

 Also known is a slotted filter with rigid filter elements (ed. St. N 719663). In the filter, the precipitate is removed by a rotating scraper.

 Also known is a filter for cleaning liquids with elastic sleeves (ed. St. N 1681896). To clean the sleeves, they are periodically collapsed under a differential pressure.

 All of these methods for the separation of mixtures are distinguished by the complexity of the cleaning system, insufficient reliability and the rejection of the continuity of the filter.

 Also known is a filter for separating sludge and liquid (ed. St. N 1792722, class B 01 D 29/00). The filter has a casing, a support element in the form of a truncated cone and a mesh fixed to the support element. In the filter, the precipitate is washed off the mesh by maintaining the speed of the mixture when it flows through a tapering cone. The specified method is adopted as a prototype of the proposed.

 A significant disadvantage of this method of separation of the mixture is the unreliability of cleaning the filter. When filtering the medium through the pores of the filter material, the separated particles are carried away by the flow of the medium and are attracted to the inlet of the pore openings. The resulting narrowing of the flow creates a pressure drop that presses the particle against the hole. The narrowing is "clogged" with particles of smaller sizes, which should not have been separated from the medium. In this case, the hydraulic characteristics of the filter element are changed and the filter starts to work in an off-design mode. On the other hand, the sediment layer formed flows around the main stream and can only be washed off at a high speed, which requires an increase in hydraulic losses in the filter.

 These disadvantages are eliminated by the separation of mixtures of the proposed method.

 According to this method, as well as according to the known method, a mixture of a fluid gas or liquid medium with solid or liquid particles is fed to the filter element, a part of the fluid with inseparable particles is passed through the filter element, and the rest of the fluid with detachable particles is diverted from the filter element.

 According to this method, in contrast to the known method, a two-phase mixture is fed into the treatment chambers above the filter element surface before separation, and a vortex is formed in each chamber with the possibility of self-cleaning of the filter element from the separated particles.

 The invention is based on the well-known law of fluid dynamics: when a stream flows around a surface behind a ledge lying below the surface, a vortex is excited. The recess, limited by two oncoming ledges, forms a rectangular niche, or chamber, which is filled with a stable vortex. It is proposed to supply a two-phase mixture to the filter element through such chambers. When the filter is in operation, a vortex is installed in each chamber behind the front ledge, which occupies part of the chamber and flows around the main stream and the mixture flow entering the chamber. In this case, part of the separated particles is carried away by the vortex and returned to it in the main stream. The remaining particles are deposited on the filter. When the filter is clogged, the flow rate of the mixture through the chamber decreases, and the vortex increases in size and, capturing the surface of the filter, clears it of sediment. When the filter is completely clogged, the vortex occupies the entire chamber and removes the accumulated sediment from it, restoring the flow of the medium through the filter.

 The vortex intensity depends on the flow rate, the shape of the front ledge and the size of the chamber. So, on a direct step, the gas flow velocity at which the vortex is excited is 5–10 m / s at normal pressure. In a water stream, a vortex is excited on a straight ledge at lower flow rates. With increasing flow velocity, the vortex intensity will increase. The formation of a vortex is also facilitated by the acute angle of the front ledge and the sharpening of the edge on the edge of the ledge.

 In FIG. 1 and 2 show the filter of example 1; in FIG. 3 - node 1 in FIG. 1, explaining the device and the operation of the cleaning and filtering elements; in FIG. 4 - filter according to example 2, section; in FIG. 5 - node II in FIG. 4.

 Example 1. The filter for cleaning air from dust (Figs. 1 and 2) consists of a housing 1 with a supply of 2 dusty air and an outlet 3 of captured dust, a cover 4 with an outlet 5 of purified air, a cleaning element 6 and a filter element 7. The latter are made in in the form of flat plates fixed between the housing 1 and the cover 4. The housing 1 has a channel narrowing downstream. Element 6 is made in the form of a lattice with grooves 8 perpendicular to the flow of the mixture. The lattice is fastened by jumpers 9 and pressed against the bottom surface to the element 7, which is a rigid porous permeable plate. The grooves 8 with the element 7 form a chamber 10.

 The filter works as follows. When passing dusty air through the housing 1 above the element 6 establishes the flow of the mixture at a constant speed. The mixture enters the chambers 10 and the air with non-separable dust is filtered through the element 7 into the cover 4 and exits through the outlet 5. Separated dust with part of the air exits the filter through the outlet 3.

 In chambers 10, stationary vortices 11 are excited and installed, which dust particles falling on them both from the main stream and from the ducts through the chambers 10 are thrown into the stream. The vortex 11a does not interfere with the flow of the mixture to the filter surface. With a partial clogging of the element 7, the flow of the mixture through the chamber 10 decreases and the vortex 11b increases in size and washes part of the filtering surface of the element 7, cleaning it of dust. If the chamber 10 is completely locked, the vortex 11b completely fills it and releases dust from the sediment. After this, the flow through the chamber 10 is restored and the vortex returns to the initial dimensions 11a.

 Example 2. A filter for separating the suspension from the liquid is shown in FIG. 3. The filter has a cylindrical housing 12 with an inlet 13 of the pulp, an outlet 14 of the filtrate and an outlet 15 of the sludge. A filter element 16 is installed in the housing in the form of a rigid truncated cone of porous permeable material. Rings 17 are installed inside the filter element 16, separated by spacers 18. The element 16 with rings 17 forms chambers 19 in which hydrodynamic vortices are excited during operation of the filter 20. The vortices have a closed toroidal shape, which provides greater stability of the vortex and lower speed and energy of its excitation.

 The described filter works similarly to the filter shown in example 1.

 The proposed method for the separation of the mixture differs from the known simplicity, reliability, continuity of action due to self-cleaning of the filter element from the precipitate.

 The method is applicable for flows with various shapes of the filter’s working surface: flat, cylindrical, conical, disk, and for various camera shapes: linear, annular, spiral, etc.

 The proposed method allows to separate the mixture in a wide range of its parameters - pressures, speeds, temperatures and densities of its working bodies, sizes and concentrations of solid particles. With increasing flow velocity, the vortex efficiency increases progressively.

Claims (1)

 The method of separation of two-phase mixtures, in which a mixture of a fluid gas or liquid medium with solid or liquid particles is supplied to the filter element, a part of the fluid with non-detachable particles is passed through the filter element, and the rest of the fluid with detachable particles is diverted from the filter element, characterized in that the two-phase mixture before its separation, they are led into the treatment chambers above the surface of the filter element, and in each chamber a vortex is formed with the possibility of self-cleaning by it of the filter element from the separated particles.

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