RU2137534C1 - Foam preparation device - Google Patents

Abstract

FIELD: process of mixing liquids and gases for preparation of foam; chemical, food-processing and other industries; construction engineering. SUBSTANCE: device includes reservoir with bottom where drive shaft is mounted on which at least one blade is secured. At least one helical turbulizing member is secure on edge of blade opposite to direction of rotation. Edges of blades and members directed towards rotation may be sharpened. Reservoir may be additionally provided with pipe unions for supply of air, water, foaming agent and foam stabilizer and for discharge of foam prepared. EFFECT: generation of foam at low specific density at low power expenses. 8 cl, 1 dwg

Description

 The invention relates to the field of technology for mixing liquids and gases to produce foam and can be used in chemical, construction, food and other industries.

 Many production processes are carried out in a binary gas-liquid system. Such processes include absorption of gas components by liquids and desorption of gases from the liquid phase, evaporation and condensation of liquids, rectification, gas purification, and production of foamed products.

 To obtain foam as a result of the interaction of liquid and gas, it is proposed to use two fundamentally different types of devices.

 The first type of device is based on passing gas through a liquid layer. Devices that implement this principle include a housing with fittings for supplying liquid and gas and fittings for the discharge of foamy liquid and gas, as well as a grill located horizontally and dividing the housing into two parts (Tarat E. Ya. Et al. Foam mode and foamy apparatus. L ., "Chemistry", 1977, p. 17). When using this device, fluid flow passes over the grill. Under the grate, a gas stream enters through the openings in the grate and through the gas layer, creating a foam. The disadvantage of this design should recognize the limited foaming capabilities caused by the design features of the device. The size of the holes in the grating, as well as their number, has a limiting value, limited by the strength characteristics of the grating material and its dimensions. The fluid flow rate along the grate is limited by the need to create a sufficiently thin continuous flow. The gas velocity and flow rate have limit values that prevent the entrainment of fluid through the gas outlet fitting. In addition, the principle of passing gas through a liquid alone does not allow sufficient foaming, since the degree of mixing of gas and liquid in this case is not large.

 The second type of device is based on the principle of rotation of the nozzle in the foaming material in the presence of air. Such devices make it possible to obtain better foaming, however, they also have corresponding fundamental and structural limitations, which will be obvious from further consideration.

 A device for producing foamed materials (RU, 2001669) is known, comprising a container mounted on a drive shaft by a working body with cavitation elements fixed on its periphery on the carriers. The working body is made in the form of a closed-loop nimbus with partitions installed inside the nimbus symmetrically with respect to the axis of its rotation. Carriers of cavitation elements are located vertically on the outside of the partitions, and cavitation elements are located vertically at an equal distance from each other. A foaming material, in particular a protein mass, is placed in the container, and the working body is rotated. Through rotation of the working body, as well as the action of cavitation elements, the processed material is saturated with air to form a foam. However, the rotation speed of the working element is limited by the hydrodynamic resistance of the medium being processed, which does not allow achieving foam with a high multiplicity.

 Also known is the design of a foam generator (SU, 1165448), comprising a housing with inlet and outlet nozzles, separated by a horizontal partition with holes in the circulation chamber and the foaming chamber. A rotating wheel is placed in the foaming chamber. Air and liquid foaming material enter the housing through the nozzles. In the mixing chamber, foam is generated by rotating the wheel. The foaming liquid that has not come into contact with air enters the circulation chamber, from where it re-enters the foaming chamber. Since the fluid has significant hydrodynamic resistance to the wheel, the possibilities for creating foam are limited.

 The closest analogue of the present invention can be recognized as a device for the preparation of foam (RU, 2005079), containing a container with a bottom, a lid and an outlet pipe. A cylindrical mesh shell is installed in the cavity of the vessel with the formation of a vertical annular chamber for the passage of foam. A cylindrical cup is fixed in the bottom of the container, in the upper part of which, placed in the shell with a shutter, a foaming chamber is formed. In the foam chamber there is a mixing mechanism in the form of a drive shaft with fixed impellers. In the foam chamber serves a liquid medium that creates foam, as well as air. When the drive shaft with the impellers rotates, foam forms, which enters the annular chamber through the mesh shell and is discharged through the nozzle. A disadvantage of the known device is the high hydraulic resistance exerted by the liquid medium to the rotation of the drive shaft with the impellers, which prevents the formation of foam with high multiplicity.

 The technical problem solved by the use of the present invention is to develop a device design with low hydraulic resistance to rotation of the working body.

 The technical result obtained by the implementation of the invention is to develop a simple and effective design of a foaming device, which allows to obtain a foam with a low specific gravity at low energy costs.

 To achieve the technical result, it is proposed to use a device that is a container in which a shaft is placed on which at least one blade is rigidly fixed, the edge of which, opposite to the direction of rotation of the shaft, contains at least one screw-like turbulizing element, the longitudinal axis of which is preferably practically oriented perpendicular to the shaft, with the edges of the blade and elements facing in the direction of rotation made sharpened. In the case of using more than one blade with mixing elements, it is desirable to place them at different heights along the length of the shaft with mismatch of the projections of the blades on the bottom of the tank. Capacity can be installed both horizontally and vertically. In the case of horizontal installation of the tank, the device can operate in continuous mode. In any case, the device may include a nozzle for supplying a foaming agent, a nozzle for supplying water and a nozzle for supplying air, as well as a nozzle for removing foam. In the case of using an open container, especially installed vertically, the air supply fitting may not be available. The maximum number of blades is limited by the length of the shaft. The distance between the blades is usually chosen arbitrarily. Turbulent elements are usually helical plates of solid material, oriented almost perpendicular to the shaft and attached to the blade by any known means. It is desirable that the shape of the blades and mixing elements allows to minimize the hydrodynamic resistance of the mixed foaming agent. The blades and mixing elements are preferably made of metal, in particular stainless steel or titanium. The blades can be made of different lengths and contain a different number of turbulizing elements. Preferably, the length of the blades is reduced towards the exit of the foam. Between the inlet of the foaming agent and the exit of the foam, a nozzle can be placed for supplying a foam stabilizer, in particular cement mortar.

 The drawing shows the basic design of the device for producing foam, an embodiment of the device, oriented horizontally. The device contains a container 1, closed at both ends, a shaft 2 made with the possibility of connecting to the drive, a blade 3 is mounted on the shaft 2, on which turbulence elements 4 are fixed. The device also contains a nozzle 5 for supplying water, a nozzle 6 for supplying a foaming agent, a nozzle 7 for feeding air and fitting 8 of the foam outlet.

 The entire structure is made of stainless steel of various grades, and the choice of steel grades is determined by the designation of the structural units.

 When using the device, the shaft 2 is connected to any engine, preferably an electric one. The nozzle 7 is connected to an air source (which can also be used as an external medium), the nozzle 6 is connected to a source containing a foaming agent (in particular, diisobutyric acid azonitrile), the foam nozzle 8 is connected to a foam collecting tank (not shown). The drive is turned on, the shaft 2 starts to move (the speed of the shaft depends on the required properties of the foam, as well as on the initial foaming agent). Through the nozzle 5 serves water. Through the ejection effect or using compressors, air and a foaming agent are introduced into the container. Under the action of rotating blades with mixing elements, the mixture of foaming agent and water foams. To stabilize the resulting foam through the fitting (not shown), located on the container between the fittings 5 and 8, serves a foam stabilizer, in particular a solution of a binder component (for example, cement). By changing the speed of rotation of the shaft, as well as the flow rate of water, air and a foaming agent (and foam stabilizer), it is possible to obtain foam with the desired characteristics, including with a uniquely low density at low energy costs and a simple device design.

Claims (8)

 1. A device for preparing foam, containing a container with a bottom in which the drive shaft is installed, characterized in that at least one blade is rigidly fixed to the drive shaft, at least one turbulent screw element is located on its edge facing in the opposite direction to the rotation moreover, the edges of the blades and elements facing in the direction of rotation are made sharpened.  2. The device according to claim 1, characterized in that at least two blades are installed on the shaft.  3. The device according to claim 1, characterized in that if more than one blade is placed along the shaft length, they are placed at different heights along the shaft length so that their projections onto the bottom of the tank do not match.  4. The device according to claim 1, characterized in that the tank is installed horizontally.  5. The device according to claim 1, characterized in that the tank is installed vertically.  6. The device according to claim 1, characterized in that the container further comprises at least one inlet fitting for supplying air, water, a foaming agent and a foam stabilizer to the container.  7. The device according to claim 1, characterized in that the container further comprises a foam discharge fitting.  8. The device according to claim 1, characterized in that the turbulizing element is made of solid material and oriented almost perpendicular to the shaft.