Patent Application
20130188442
Research and development of the present invention and application have not been Federally-sponsored, and no rights are given under any Federal program.
This invention relates to a method of agitation and mixing various liquid substances, dissolving solids in liquid, making emulsions, extracts, milling solids in presence of liquids and more.
The main characteristic of currently known methods of agitation of liquids is that the liquid to be mixed is moved inside a stationary installed container. Friction forces between the liquids and wall of the container breaks the liquid's movement. The higher speed of movement of the liquids, the stronger the breaking force. Most of the existing mixers are specialized at performance within rather narrow range of characteristics: mixing of low viscosity liquids, mixing of high viscosity liquids, making emulsions or extracts, milling solids in liquids etc. There is no universal apparatus for a variety of mixing processes.
Typical drawbacks of prior art mixers are:
The invented method has at least some of the following objectives:
To create a versatile and effective mixer for different types of liquids and mixing applications.
To provide a method for mixing in accordance with the foregoing, characterized by such positive features as: minimal formation of foam or bubbles during the mixing process, increase quality of mixing if mass of liquid to be mixed increases, instant mixing of whole volume of liquid.
To provide a method of the kind indicated, resulting in efficient mixing of liquids in large vessels.
To provide a method in accordance with the above, resulting in a simplified structure and controlling of processes, and thus, mixers of reduced production cost.
The core principle of the invented mixing technology is steering of a vertically placed container with liquid or liquid with small particle substances to be mixed inside. Radial ribs extend upward from the bottom of the container. The ribs can be made integrally with the container, as one body, or separately and then firmly attached to the container's bottom such that rotation of the container is transferred to ribs at the same speed and mode.
Rotation of the container with ribs generates three types of forces applied to the liquids inside: centrifugal (Fc), gravity (Fg), and friction (Ff). In FIGS. 26,27 a schematic liquids hydrodynamics during the mixing process is shown. When the rotation of the container with liquids starts, the ribs together with the centrifugal force Fc push liquid from the triangle spaceween the ribs toward the container's wall. The space is being emptied instantly, and the liquid above the spaces drops down and fill the emptied spaces. This new portion of liquid is also pushed towards the wall and so on. This relocation of liquids generates their flow from central part of the container towards the wall.
Due to friction force Ff between the wall and the liquid, the latter gets the horizontal rotation about the wall. This rotation, in turn, generates centrifugal force Fc pressing the liquid against the wall. The higher the speed of rotation of the liquid, the larger the centrifugal force, the higher the pressure of liquids pushing against the wall, the larger the friction force that rotates the liquid horizontally, and the higher the speed of rotation of the liquid.
The centrifugal force Fc, not only increases friction force Ff but also pushes up the liquid along the wall. Due to centrifugal pressure the liquid at the wall goes upward and can reach the top of the wall. At the same time, gravity force Fg applied to the liquid acts in opposite direction. At some point the gravity force overwhelms the force elevating the liquid. Then the liquid drops down back into the spaces between ribs at the bottom. Dropped liquid is pushed toward the wall and goes upward due to Fc once again, repeating the cycle. A wall to wall whirlpool appears at the central part of the container. As a result, liquid gets directed in a 3D motion in the horizontal and vertical planes, producing some of the extraordinary features of the mixer.
As it was shown by tests, if the speed of steering is 500-600 rpm or more, relocation of the central part of the liquid body inside the container toward the wall is made in a fraction of a second. Accordingly, the whirlpool's bottom goes downward until it reaches the bottom of the container and finally, the liquid takes the form of a sleeve around the wall. Contacting surface between the liquids and the container's wall is maximized, and intensity of the mixing increases dramatically. What is also important, mixing of whole volume of the liquids begins instantly and appears explosive-like, causing intensive mixing of liquids at relatively low speeds of liquid's driver (500-600 rpm).
As it was described, the centrifugal force Fg pressing the liquids toward the wall and generating the friction force between the liquid and the wall, determines the intensity of mixing process—as centrifugal force increases, friction force between the liquid and container's wall also increases. It creates still another unusual feature of the invented mixer: the bigger the diameter of mixing container, the larger the centrifugal force Fc, and the more intensive mixing process. This feature is especially important for mixing liquids in bulk, and in contrast with any of the existing mixing methods, where increase in diameter of the container decreases intensity of mixing.
In some applications, the efficiency of the method can be intensified by attachments comprising of a mesh placed across liquid's flow. Such attachments are especially effective, for example, for dissolving of solid particles in liquid and preparation of extracts. Liquid flow presses the particles against the mesh but they cannot go through. In contrast, power flow of liquids runs through the mesh contacting with particles on its way. It effectively enforces the above processes.
Other effective applications of mixers with mesh are mixing of high viscosity liquids or preparation of emulsions. Powerful flow of liquids running through the mesh is being disrupted into smallest drops, and become full-section of flow after the mesh. The number of such disruptions and restorations of liquid flow is tens of thousands per min. The mixer with mesh is in high shear.
As it is clear, a combination of basic container with mesh attachments convert the mixer into an universal mixing combine.
The following advantages of the invented method have been revealed:
easy mixing of both: low or high viscosity liquids;
no foam or bubbles during the mixing process;
instant vigorous mixing at low speed of driving means;
intensive mixing with larger quantity of liquids being mixed;
no contact between liquids and mixing driver;
operation of mixing processes is provided by controlling of spinning of the container only.
Summarizing the above, it should be stated that the invented method is conceptually different from the prior art. Design of existing mixers is based on moving of the liquids to be mixed about a stationary container, whereas in the invented method the movement of liquid is created by spinning the mixing container. Liquid in the container gets impelled along all three directions and intensive mixing is accomplished due to friction force, centrifugal force and gravity force applied to the liquids.
A structure of the invented mixer in different structural versions in preferred embodiment is shown in
1. Laboratory Mixers.
The mixers consist of a container of up to 10 liters volume, in which the liquids to be mixed are located, a driver for stirring the container with a coupling mechanism connecting the driver and the container, a housing, and an operating control unit. The container is a metal or plastic canister of cylindrical shape, or beakers used conventionally for laboratory applications, or flasks, adapted to the invented mixing method.
Container's lid 18 (FIGS. 4,5) prevents the liquids from spilling out during the mixing process. The lid can be separated from the container, as shown in the presented embodiment, or integrated with it in one body. In first case the lid has a means for liquid-tight connection with the container withstanding pressure of liquid generated inside the container when the mixer is in use. At the top of the lid 18 is an opening 19 for loading liquids into the container. Based on experiments, the diameter of the opening should be about 0.5-6 times the diameter of the lid. Rim 20 around the opening, facing inside of the container is desirable.
As a structure to be rotated, the container as it is and with the lid must be well balanced to eliminate twisting during the mixer's operation.
Driving mechanism 2 and housing 3 are shown in FIGS. 6,7. The driving mechanism includes a reversible electric motor 211 capable of rotating the container with liquid. Motor shaft 212 extends toward the container. Male component 213 of male/female connection between the motor shaft and the container is attached to the shaft. It is designed to fit the female components 15 and 16 on the container. Component 213 includes slots 214 designed to align and mesh with teeth 17. Such meshing should be tight enough to provide reliable transfer of motor rotation to the container, without shocks at the beginning of mixer's operation and when the mode of rotation of the motor is changed.
Speed, direction and protocol of motor rotation are controlled by operating means. The liquid flow inside the container may be smooth and laminar at slow speeds or turbulent and very intensive at high speed. At given speed the intensity of mixing depends on mode of rotation of the container: slowest at one way rotation, moderate at run-stop-run mode, and highest at clockwise-counterclockwise mode. Speed and mode of rotation determine mixing protocol during laboratory tests.
Housing 3 is a cylinder comprising of bottom 311 and walls 321. Electric motor 211 is attached to the bottom 311 by any convenient way. Walls 321 are made for safety and to protect the operator from damage when the mixer is in use. The housing is made of heavy weight material, for example, cast iron, to prevent rocking of the mixer if imbalanced loads are applied. Diameter D provides convenient placement of cylinder 1 inside the housing.
Flasks and beakers of regular shapes should be modified for the invented mixing technology. Compared with the container 1 with cylindrical wall described above, new parts should be added to both beakers and flasks for use with the mixer. These parts are vertical ribs at the bottoms and a means for male/female connection between beaker or flask and driving motor. Beakers should have also a watertight lid. The design of the new parts can be the same as described for cylindrical container.
The second version of the invented mixer is a container as described above with a second set of meshed ribs placed at the container's bottom (
As a sub-version of the second version, one can consider an attachment with circular mesh overlapping the ribs 13 (FIGS. 12,13,14,15). In described preferred embodiment, metal disk 72 with consoles 73 carry mesh 70. Diameter of said disk with said consoles is bigger than diameter of female coupling 15 with ribs 13. Shear effect of the attachment is accomplished when the flow of liquid created by ribs 13 and the centrifugal force is pushed through the mesh. The attachment is affixed to the container the same way as described for the second version of the invention.
In case of mixing of high viscosity liquids or preparation of emulsions, the processes can be effectively enforced if meshed ribs are installed at the wall of the container. The container with wall attachment is the third structural version of the invention. As shown in
The fourth structural version of the container is intended for mixing of foam-forming substances. The structure includes an element substituting ribs 13 at the bottom of the container, as shown in FIGS. 18,19. Actually, ribs 13 are integrated in one solid body 124. Similar to ribs 13, the body propels liquids toward the walls when the container is rotated, however, in contrast to ribs, it does so with minimal and gentle contacts with the liquid. Such contacts prevents forming foams during mixing process. At the same time, centrifugal force pressing liquid toward the wall exclude formation of bubbles. In the preferred embodiment the body 124 is of square shape, but may be different.
The fifth structural version of the container is intended for milling liquids with pulp or suspended solid particles. For this purpose, the attachment 40 is similar to those with meshed ribs in the first structural version (
As follows from the above description of the invention, a mixer comprising of a basic canister according to version one of the invention, and a set of attachments according to versions two, three, four and five is actually a universal mixing combine, performing a variety of processes of mixing liquids as well as liquids and solids.
As it is clear, the combine can include more than one container rotated by one motor, with proper systems for transfer of motor rotation to a number of containers.
One should not exclude usage of the invention for mixing of fine, non-sticky solid particles.
2. Industrial Mixers.
Referring now to FIGS. 24,25, are illustrated an apparatus for industrial mixing of liquids in bulk. Metal tank 521, having side walls 522 and bottom 523 is used as a container for liquids to be mixed. The top is fitted with a suitable removable cover 525. The latter has an inlet opening 526, and the bottom wall 523 of the tank has one or more outlet openings 527 (shown schematically), for withdrawing the liquid.
Tank 521 is supported on a combined turntable and coupling member 529, which is in turn carried on the shaft 531 of a motor 530.
The entire mechanism is preferably surrounded by a housing on the floor 56. The housing has side columns 532, and near the top, a bearing and sleeve 528, 533, 534 which provide lateral stability to the tank 521 when imbalanced loads are applied from inside. For safety reasons the mixer should have a surrounding fence (not shown).
Finally, in accordance with the method of the invention, bottom 523 of tank 521 has rib element 524.
In the preferred embodiment, in order to attach the tank 521, the ribs 524 in the bottom 523 thereof are hollow, and a vertical projection on the coupling member 529 extends into the hollow portion of the ribs 524 and thereby supports the bottom 523. As is clear, other coupling means connecting the tank with motor shaft 531 can be applied.
The tank is intended for solely rotation about vertical axis 535, as indicated by the two arrows 536, 537 in
As is clear, depending on application, the industrial mixer can be supplied with the attachments similar to those described for the laboratory mixers, or can have such attachments fixed permanently to bottom or wall of mixer's tank.
The objects set forth above, among those elucidated in, or made apparent from, the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown on the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense.
