Abstract:
A method of mixing together liquids or liquid/solid combinations, and mixing apparatus/universal combine utilizing a vertical spinning container or vessel having a rib, or a cross rib in its bottom wall. The container is spun about a vertical axis with no wobbling component to the motion. Meshed elements are used for high shear mixing. Start/stop routines, and variable acceleration/speed values are used, to facilitate complete mixing. Use of ‘impeller’ blade stirrers is completely eliminated.

Description:
[0001]    Research and development of the present invention and application have not been Federally-sponsored, and no rights are given under any Federal program. 
       FIELD OF THE INVENTION 
       [0002]    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. 
       BACKGROUND ART 
       [0003]    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&#39;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. 
         [0000]    Typical drawbacks of prior art mixers are:
       mixing is not always complete, or more often extended time is required in order to obtain a resultant homogeneous mixture.   in many cases, undesirable aeration takes place as a consequence of air being introduced into the liquid. Bubbles of air result, and these represent either un-mixed material, or alternately, material that has been mixed but which requires that the bubbles be broken up either mechanically, or with a suitable anti-foaming reagent additive.   mixing of high viscosity liquids involves more powerful energy consuming equipment.   mixers for laboratories and industrial needs are structurally complicated and have sophisticated electronic control systems which are rather expensive.       
 
       SUMMARY OF THE INVENTION 
       [0008]    The invented method has at least some of the following objectives: 
         [0009]    To create a versatile and effective mixer for different types of liquids and mixing applications. 
         [0010]    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. 
         [0011]    To provide a method of the kind indicated, resulting in efficient mixing of liquids in large vessels. 
         [0012]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a vertical section view of a mixing laboratory apparatus adapted to practice the method of the present invention. 
           [0014]      FIG. 2  is a top plan view of the apparatus of  FIG. 1 . 
           [0015]      FIG. 3  is a bottom view of the apparatus of  FIG. 1 . 
           [0016]      FIG. 4  is a top plan view of a cover for the apparatus of  FIG. 1 . 
           [0017]      FIG. 5  is a vertical section view of a cover for the apparatus of  FIG. 1 . 
           [0018]      FIG. 6  is a vertical section view of a base for the mixing laboratory apparatus of  FIG. 1 . 
           [0019]      FIG. 7  is a top plan view of the base of  FIG. 6 . 
           [0020]      FIG. 8  is a vertical section view of a mixing laboratory apparatus, with meshed ribs at the bottom. 
           [0021]      FIG. 9  is a top plan view of the apparatus of  FIG. 8 . 
           [0022]      FIG. 10  is a top plan view of an attachment with meshed ribs for the apparatus of  FIG. 8 . 
           [0023]      FIG. 11  is a vertical section view of the attachment with meshed ribs of  FIG. 8 . 
           [0024]      FIG. 12  is a vertical section view of a mixing laboratory apparatus with circular meshed attachment at the bottom. 
           [0025]      FIG. 13  is a top plan view of the circular meshed attachment of  FIG. 12 . 
           [0026]      FIG. 14  is a top plan view of the circular meshed attachment of  FIG. 12 . 
           [0027]      FIG. 15  is a vertical section view of the circular meshed attachment of  FIG. 14 . 
           [0028]      FIG. 16  is a vertical section view of a mixing laboratory apparatus, with vertical meshed attachment at wall. 
           [0029]      FIG. 17  is a top plan view of the apparatus of  FIG. 16 . 
           [0030]      FIG. 18  is a vertical section view of a mixing laboratory apparatus, with solid element at a bottom, instead for ribs in  FIG. 1 . 
           [0031]      FIG. 19  is a top plan view of the apparatus of  18 . 
           [0032]      FIG. 20  is a vertical section view of a milling laboratory apparatus, with knife attachment. 
           [0033]      FIG. 21  is a top plan view of the apparatus of  FIG. 20 . 
           [0034]      FIG. 22  is a top plan view of the knife attachment of  FIG. 20 . 
           [0035]      FIG. 23  is a vertical section view of the knife attachment of  FIG. 22 . 
           [0036]      FIG. 24  is a vertical section view of an industrial mixing apparatus adapted to practice the method of the present invention. 
           [0037]      FIG. 25  is section view of the apparatus of  FIG. 24  along 1-1. 
           [0038]      FIG. 26  is a scheme of liquids movement to be mixed using apparatus of present invention. The vertical section view. 
           [0039]      FIG. 27  is a scheme of movement of liquids to be mixed using apparatus of present invention. The horizontal section view. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    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&#39;s bottom such that rotation of the container is transferred to ribs at the same speed and mode. 
         [0041]    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&#39;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. 
         [0042]    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. 
         [0043]    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. 
         [0044]    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&#39;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&#39;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&#39;s driver (500-600 rpm). 
         [0045]    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&#39;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. 
         [0046]    In some applications, the efficiency of the method can be intensified by attachments comprising of a mesh placed across liquid&#39;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. 
         [0047]    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. 
         [0048]    As it is clear, a combination of basic container with mesh attachments convert the mixer into an universal mixing combine. 
         [0049]    The following advantages of the invented method have been revealed: 
         [0050]    easy mixing of both: low or high viscosity liquids; 
         [0051]    no foam or bubbles during the mixing process; 
         [0052]    instant vigorous mixing at low speed of driving means; 
         [0053]    intensive mixing with larger quantity of liquids being mixed; 
         [0054]    no contact between liquids and mixing driver; 
         [0055]    operation of mixing processes is provided by controlling of spinning of the container only. 
         [0056]    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. 
         [0057]    A structure of the invented mixer in different structural versions in preferred embodiment is shown in  FIGS. 1-25 . In this description two main ways of application of the mixers are considered: 
         [0058]    1. Laboratory Mixers. 
         [0059]    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.  FIGS. 1-5  show a preferred embodiment of the mixer with a container having cylindrical wall. The main parts of container  1  include: wall  12  and the first set of ribs  13  extending upward from the bottom  14  of the container. In the presented embodiment, the number of ribs is eight, but it may be more or less. As shown, the ribs  13  are made integrally with the container at its bottom. Based on data from the experiments, the height of the ribs above the bottom should be about 1/10 th - 1/12 th  of the container height. The container has the female coupling mechanism  15  providing male/female connection of the container to the driver, for transferring the driver shaft&#39;s rotational motion to the container. The coupling mechanism  15  is combined structurally with the ribs  13  as shown in FIGS.  1 , 2 . The mechanism comprises of: a tube-like chamber  16 , protruding inside of the container, designed to fit the male component of the mechanism extending from the driver (see below). Height H and diameters D 1  and D 2  of chamber  16  should provide reliable connection between the container and the driver, without wobbling and shifting the container during mixing process. Teeth  17  inside chamber  16  transfer rotation of the male component of the coupling from driver to the container. 
         [0060]    Container&#39;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. 
         [0061]    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&#39;s operation. 
         [0062]    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&#39;s operation and when the mode of rotation of the motor is changed. 
         [0063]    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. 
         [0064]    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. 
         [0065]    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. 
         [0066]    The second version of the invented mixer is a container as described above with a second set of meshed ribs placed at the container&#39;s bottom ( FIGS. 8-11 ). The main difference between this version compared to the one described above is this additional attachment: a metal disc  22  with vertical meshed ribs  30  at its periphery. Metal disc  22  with a center hole  24  rests on the lower part of female part of coupling mechanism  15 . Pins  23  extend upward from female part for coupling together with two holes  25  in disk  22 . It prevents rotation of the attachment about female coupling when the mixer works. Vertically placed meshed ribs  30  are attached to disk  22  in the way shown in FIGS.  8 , 9 . The meshed ribs  30  are located between solid ribs  13 . 
         [0067]    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. 
         [0068]    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  FIGS. 16-17 , in preferred embodiment, vertical meshed ribs  31  are located in central part of container&#39;s wall. As is revealed from experiments, the most intensive horizontal flow of liquids in mixing process according to the invented method is just along this part of the container. Ribs  31  are attached to a sleeve  32  which is to be inserted and can be removed from the container. Pins  33  extending from container&#39;s wall  12  provide vertical support for sleeve  32 . Opening  34  in the sleeve prevents vertical movement of the sleeve when the mixer operates. 
         [0069]    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. 
         [0070]    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 ( FIGS. 20-23 ). The difference is that ribs  30  are substituted by sharp knives  41 . During rotation of the container the knives cut the downstream flow with the product to be milled, which is dropping from the top to the container&#39;s bottom. As speed of rotation of the knives is high, milling of the products is effective. 
         [0071]    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. 
         [0072]    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. 
         [0073]    One should not exclude usage of the invention for mixing of fine, non-sticky solid particles. 
         [0074]    2. Industrial Mixers. 
         [0075]    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. 
         [0076]    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 . 
         [0077]    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). 
         [0078]    Finally, in accordance with the method of the invention, bottom  523  of tank  521  has rib element  524 . 
         [0079]    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. 
         [0080]    The tank is intended for solely rotation about vertical axis  535 , as indicated by the two arrows  536 ,  537  in  FIG. 24 . Rotation in each of the two opposite directions is contemplated. 
         [0081]    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&#39;s tank. 
         [0082]    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.