Abstract:
The present invention provides for a device and method of creating hydrodynamic cavitation in fluids. The device comprises a chamber formed by a wall where the wall has a first orifice and an opposing second orifice that are both in fluid communication with said chamber. The first orifice and the second orifice share the same center-line and the first orifice has a diameter smaller than that of the second orifice. The method comprises the steps of: introducing a first liquid stream through the first orifice of the device to create a first liquid jet; introducing a second liquid stream through the second orifice of the device to create a second liquid jet; creating a high shear intensity vortex contact layer when the first liquid jet interacts with and penetrates the second liquid jet; and creating and collapsing cavitation caverns and bubbles in the high shear intensity vortex contact layer.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    The present invention relates to a device and method for creating hydrodynamic cavitation in fluids. This device and method according to the present invention may find application in mixing, synthesis, assisting in chemical reactions, and sonochemical reactions in the chemical, food, pharmaceuticals, cosmetics processing, and other types of industry.  
           [0003]    2. Description of the Related Art  
           [0004]    Cavitation is the formation of bubbles and cavities within a liquid stream resulting from a localized pressure drop in the liquid flow. If the pressure at some point decreases to a magnitude under which the liquid reaches the boiling point for this fluid, then a great number of vapor-filled cavities and bubbles are formed. As the pressure of the liquid then increases, vapor condensation takes place in the cavities and bubbles, and they collapse, creating very large pressure impulses and very high temperatures. According to some estimations, the temperature within the bubbles attains a magnitude on the order of 5000° C. and a pressure of approximately 500 kg/cm 2 . Cavitation involves the entire sequence of events beginning with bubble formation through the collapse of the bubble. Because of this high energy level, cavitation has been studied for its ability to mix materials and aid in chemical reactions.  
           [0005]    There are several different ways to produce cavitation in a fluid. The way known to most people is the cavitation resulting from a propeller blade moving at a critical speed through water. If a sufficient pressure drop occurs at the blade surface, cavitation will result. Likewise, the movement of a fluid through a restriction such as an orifice plate can also generate cavitation if the pressure drop across the orifice is sufficient. Both of these methods are commonly referred to as hydrodynamic cavitation. Cavitation may also be generated in a fluid by the use of ultrasound. A sound wave consists of compression and decompression cycles. If the pressure during the decompression cycle is low enough, bubbles may be formed. These bubbles will grow during the decompression cycle and contract or even implode during the compression cycle.  
           [0006]    Both of these methods of cavitation to enhance mixing or aid in chemical reactions have had mixed results, mainly due to the inability to adequately control cavitation. U.S. Pat. Nos. 5,810,052, 5,931,771 and 5,937,906 to Kozyuk disclose an improved device capable of controlling the many variables associated with cavitation.  
           [0007]    Of relevance to the present invention are U.S. Pat. Nos. 5,466,646 and 5,417,956 to Moser which disclose the use of high shear followed by cavitation to produce metal based materials of high purity and improved nanosize. While the results disclosed in these patents are improved over the past methods of preparation, the inability to control the cavitation effects limit the results obtained.  
           [0008]    Furthermore, U.S. Pat. No. 5,931,771 introduced a method of producing ultra-thin emulsions and dispersions, which in accordance with the invention is comprised of the passage of a hydrodynamic liquid flow containing dispersed components through a flow-through channel internally having at least one nozzle. Located after the nozzle and along the stream is a buffer channel which is directed by its open end in the nozzle side. Inside the nozzle, a high velocity primary liquid jet, which enters into the buffer channel at a minimal distance from the nozzle. In the buffer channel, flowing out from this channel, a secondary liquid jet is formed, which moves in the buffer channel towards the primary jet and forms with the surface of the primary jet a high intensity vortex contact layer. In the high intensity vortex contact layer, collapsing cavitation caverns and bubbles are generated which disperse emulsions and dispersions to submicron sizes.  
           [0009]    In addition, the invention of U.S. Pat. No. 5,720,551 features a method for use in causing emulsification in a fluid. In the method, a jet of fluid is directed along a first path, and a structure is interposed in the first path to cause the fluid to be redirected in a controlled flow along a new path, the first path and the new path being oriented to cause shear and cavitation in the fluid. The first path and the new path may be oriented in essentially opposite directions. The coherent flow may be a cylinder surrounding the jet. The interposed structure may have a reflecting surface that is generally semi-spherical, or is generally tapered, and lies at the end of a well. Adjustments may be made to the pressure in the well, in the distance from the opening of the well to the reflecting surface, and in the size of the opening to the well. The controlled flow, as it exits the well, may be directed in an annular sheet away from the opening of the well. An annular flow of a coolant may be directed in a direction opposite to the direction of the annular sheet.  
           [0010]    According to the invention of U.S. Pat. No. 6,227,694, a method for causing a reaction between two or more reactive substances comprises the step of colliding a flow of one reactive substance against a flow of another reactive substance at a high flow rate to cause a reaction between them. Furious turbulence and cavitation occur when the jet flows collide together at high speeds.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention provides a device for creating hydrodynamic cavitation in fluids comprising a chamber formed by a wall where the wall has a first orifice and an opposing second orifice that are both in fluid communication with said chamber. The first orifice and the second orifice share the same center-line and the first orifice has a diameter smaller than that of the second orifice. The device may further comprise a second pair of opposing orifices disposed in the wall such that the second pair of opposing orifices is in fluid communication with the chamber.  
           [0012]    In another embodiment, a device for creating hydrodynamic cavitation in fluids comprises a flow-through channel having a wall wherein the wall has a first orifice that is in communication with the flow-through channel for introducing a first liquid stream into the flow-through channel and a second orifice opposite the first orifice that is in communication with the flow-through channel for introducing a second liquid stream into the flow-through channel. The first orifice and second orifice share the same center-line and the first orifice has a diameter smaller than that of the second orifice. The introduction of the first liquid stream through the first orifice creates a first liquid jet and the introduction of the second liquid stream through the second orifice creates a second liquid jet. When the first liquid jet impinges with the second liquid jet, the first liquid jet penetrates the second liquid jet thereby creating a high shear intensity vortex contact layer. Preferably, the flow-through channel is configured for passing a hydrodynamic liquid through the flow-through channel. The first liquid stream comprises a first liquid and the second liquid stream comprises a second liquid, where the first and second liquids may be the same or different.  
           [0013]    In another embodiment, the present invention provides for a device for creating hydrodynamic cavitation in fluids comprising a flow-through channel for passing a hydrodynamic liquid where the flow-through channel has an outlet, a cavitation chamber situated within the flow-through channel where the cavitation chamber is defined by a wall and an exit orifice, and a restriction wall in physical communication with the wall and the flow-through channel to prevent the hydrodynamic liquid from exiting the flow-through channel before entering the first and second orifices. The wall includes a pair of opposing orifices wherein the first and second orifices share the same center-line and are in communication with the chamber and the first orifice has a diameter smaller than that of the second orifice. The device may further comprise a second cavitation chamber situated within the flow-through channel in series with the first cavitation chamber, the second cavitation chamber having a pair of opposing orifices that share the same center-line and have different diameters. Alternatively, the wall may further include a second pair of opposing orifices that share the same center-line and have different diameters.  
           [0014]    Additionally, the present invention provides for a method of creating hydrodynamic cavitation in fluids comprising: providing a first orifice and a second opposing orifice in a wall of a chamber such that the first and second orifices share the same center-line and the first orifice has a diameter smaller than that of the second orifice; introducing a first liquid stream through the first orifice to create a first liquid jet; introducing a second liquid stream through the second orifice to create a second liquid jet; creating a high shear intensity vortex contact layer when the first liquid jet interacts with and penetrates the second liquid jet; and creating and collapsing cavitation caverns and bubbles in the high shear intensity vortex contact layer.  
           [0015]    In another embodiment, a method of creating hydrodynamic cavitation in fluids comprising: passing a hydrodynamic liquid through a flow-through channel having a wall; providing a first orifice and a second opposing orifice in the wall of the flow-through channel such that the first and second orifices share the same center-line, the first orifice has a diameter smaller than that of the second orifice; introducing a first liquid stream through the first orifice to create a first liquid jet; introducing a second liquid stream through the second orifice to create a second liquid jet; creating a high shear intensity vortex contact layer when the first liquid jet interacts with and penetrates the second liquid jet; and creating and collapsing cavitation caverns and bubbles in the high shear intensity vortex contact layer.  
           [0016]    Furthermore, a method of creating hydrodynamic cavitation in fluids comprising: passing a hydrodynamic liquid through a flow-through channel having an outlet; providing a cavitation chamber situated within the flow-through channel having a wall and an exit orifice; directing the liquid through the first orifice to create a first liquid jet; directing the liquid through the second orifice to create a second liquid jet; creating a high shear intensity vortex contact layer when the first liquid j et interacts with and penetrates the second liquid jet; and creating and collapsing cavitation caverns and bubbles in the high shear intensity vortex contact layer. The wall includes a pair of opposing orifices wherein the first orifice and the second orifice share the same center-line and are in communication with the chamber and the first orifice has a diameter smaller than that of the second orifice. The method may further comprise: directing the liquid exiting from the exit orifice of the chamber towards a second cavitation chamber situated downstream of the chamber in the flow-through channel; directing the liquid through the first orifice of the second cavitation chamber to create a third liquid jet; directing the liquid through the second orifice of the second cavitation chamber to create a fourth liquid jet; creating a second high shear intensity vortex contact layer when the third liquid jet interacts with and penetrates the fourth liquid jet; and creating and collapsing cavitation caverns and bubbles in the second high shear intensity vortex contact layer. The second cavitation chamber includes a wall having a pair of opposing orifices disposed therein wherein the first orifice and the second orifice share the same center-line and are in communication with the second chamber and the first orifice has a diameter smaller than that of the second orifice. Alternatively, the method may further comprise: directing the hydrodynamic liquid through a third orifice in the wall of the chamber to create a third liquid jet; directing the liquid through a fourth orifice in the wall of the chamber opposite the third orifice to create a fourth liquid jet, the third and fourth orifices share the same center-line and the third orifice has a diameter that is smaller than the fourth orifice; creating a second high shear intensity vortex contact layer when the third liquid jet interacts with and penetrates the fourth liquid jet; and creating and collapsing cavitation caverns and bubbles in the second high shear intensity vortex contact layer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:  
         [0018]    [0018]FIG. 1 is a longitudinal cross-section of a first embodiment of the device according to the present invention wherein the device comprises a flow-through channel that includes a cavitation chamber having two opposed jetting orifices that empty into the chamber.  
         [0019]    [0019]FIG. 2 is a longitudinal cross-section of a second embodiment of the device according to the present invention wherein two opposed jetting orifices are provided in a flow-through channel wherein the two opposed jetting orifices are the only two inlets.  
         [0020]    [0020]FIG. 3 is a longitudinal cross-section of a third embodiment of the device according to the present invention wherein two opposed jetting orifices are provided in a flow-through channel having an inlet wherein the two opposed jetting orifices are secondary inlets.  
         [0021]    [0021]FIG. 4 is a modification of the first embodiment of the device according to the present invention wherein the device comprises three pairs of opposing jetting orifices.  
         [0022]    [0022]FIG. 5 is a modification of the first embodiment of the device according to the present invention wherein the device further comprises a second cavitation chamber situated in the flow-through channel in series with the first cavitation chamber.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    Referring now to the drawings wherein the showings are for purposes of illustrating various embodiments of the present invention only and not for purposes of limiting the same, FIG. 1 illustrates a longitudinal cross-sectional view of a first embodiment of the device  10  comprising a flow-through channel  15  having an inlet  20  and an outlet  25 . Situated within the flow-through channel  15  is a cylindrical cavitation chamber  30  defined by a front wall  35  perpendicular to the flow-through channel  15 , a wall  40  parallel to the flow-through channel  15 , and an exit orifice  45  in communication with the outlet  25 . The arrangement of the cavitation chamber  30  within the flow-through channel  15  creates an annular opening  33 . Wall  40  has a first jetting orifice  50  and a second jetting orifice  55  oriented directly opposite the first jetting orifice  50  such that the first jetting orifice  50  and the second jetting orifice  55  directly face each other and share the same center-line X. The diameter of the first jetting orifice  50  is smaller than the diameter of the second jetting orifice  55 . The cavitation chamber  30  also includes a flange  60  in communication with wall  40  and the flow-through channel  15  to direct fluid into the cavitation chamber  30  and restrict fluid from exiting the flow-through channel without being directed into the first jetting orifice  50  or second jetting orifice  55 .  
         [0024]    In operation, a hydrodynamic liquid stream moves along the direction, indicated by arrow A, through the inlet  20  and flows into flow-through channel  15 . As the liquid stream approaches the front wall  35 , the liquid stream is directed towards the annular opening  33 . One portion of the liquid stream, indicated by arrow B, passes through the annular opening  33  and enters the first jetting orifice  50  forming a high velocity liquid jet  65  (hereinafter referred to as “smaller liquid jet  65 ” because this liquid jet exits the smaller diameter jetting orifice  50 ). Additionally, the other portion of the liquid stream, indicated by arrow C, passes through the annular opening  33  and enters the second jetting orifice  55  forming a high velocity liquid jet  70  (hereinafter referred to as “larger liquid jet  70 ” because this liquid jet exits the larger diameter jetting orifice  55 ).  
         [0025]    Both smaller liquid jet  65  and larger liquid jet  70  flow into chamber  30  where they impinge along center-line X. Once the smaller liquid jet  65  and the larger liquid jet  70  impinge, smaller liquid jet  65  penetrates and interacts with larger liquid jet  70  thereby creating a high shear intensity vortex contact layer  75  between the liquid jets  65 ,  70 . Cavitation caverns and bubbles are created in the high shear intensity vortex contact layer  75 . During the collapse of cavitation caverns and bubbles, high localized pressures, up to 1000 MPa, arise and the level of energy dissipation in the flow-through channel  205  attains a magnitude in the range of 1 10 -1 15  watt/kg. Under these physical conditions in the liquid, on the boundary of the bubble and inside the bubble itself in the gas phase, chemical reactions proceed such as oxidation, disintegration, synthesis, etc. After the cavitation bubbles collapse, the liquid is transported from the cavitation chamber  30  through the exit orifice  45  and exits the outlet  25 , indicated by arrow D.  
         [0026]    Although the first embodiment includes only one pair of opposing jetting orifices, it is possible to provide two or more pairs of opposing jetting orifices within the wall  340  and in communication with the chamber  330 . As in the case of the first embodiment, the first opposing jetting orifice of each pair has a diameter smaller than that of the second opposing jetting orifice. This alternate design is shown as device  300  in FIG. 4, with arrow A representing the flow of hydrodynamic fluid through the flow-through channel  305 . Wall  340  includes a first pair of opposing jetting orifices  350 ,  355 , a second pair of opposing jetting orifices  360 ,  365 , and a third pair of opposing jetting orifices  370 ,  375 . The device  300  is structurally and functionally identical to the device  10  of the first embodiment, except for the addition of two pairs of opposing jetting orifices  370 ,  375 .  
         [0027]    Although the first embodiment includes only one cavitation chamber  30 , it is possible to provide two or more cavitation chambers in series within the flow-through chamber. This alternate design is shown as device  400  in FIG. 5, with arrow A representing the flow of hydrodynamic fluid through the flow-through channel  405 . The device  400  includes a first cavitation chamber  430  defined by a front wall  435 , a wall  440  having a pair of opposing jetting orifices  450 ,  455 , and an exit orifice  445 . Additionally, the device  400  includes a second cavitation chamber  460  defined by a front wall  465 , a wall  470  having a pair of opposing jetting orifices  475 ,  480 , and an exit orifice  485 . The device  400  is structurally and functionally identical to the device  10  of the first embodiment, except for the addition of the second chamber  460 .  
         [0028]    Furthermore, although the preferred cavitation chamber  30  is cylindrical in shape, it is contemplated that any shape may be possible provided that the liquid flow is permitted to enter the cavitation chamber  30 . Such shapes may include cubical, conical, spherical, semi-spherical, or rectangular.  
         [0029]    [0029]FIG. 2 represents a second embodiment according to the present invention. FIG. 2 illustrates a longitudinal cross-sectional view of the device  100  comprising a flow through channel  105  having a first inlet  110 , a second inlet  115 , and an outlet  120 . The first inlet  110  includes a first jetting orifice  125  and the second inlet  115  includes a second jetting orifice  130 . The first jetting orifice  125  is oriented directly opposite the second jetting orifice  130  such that the first jetting orifice  125  and the second jetting orifice  130  directly face each other and share the same center-line X. The diameter of the first jetting orifice  125  is smaller than the diameter of the secondjetting orifice  130 .  
         [0030]    In this embodiment, a first hydrodynamic liquid stream, indicated by arrow A, enters the first inlet  110  and passes through the first jetting orifice  125  forming a high velocity liquid jet  135  (hereinafter referred to as “smaller liquid jet  135 ” because this liquid jet exits the smaller diameter jetting orifice  125 ) that flows into flow-through channel  105 . Additionally, a second hydrodynamic liquid stream, indicated by arrow B, enters the second inlet  115  and passes through the second jetting orifice  130  forming a high velocity liquid jet  140  (hereinafter referred to as “larger liquid jet  140 ” because this liquid jet exits the larger diameter jetting orifice  130 ) that flows into flow-through channel  105 . Both the smaller liquid jet  135  and the larger liquid jet  140  flow into the flow-through channel  105  where they impinge along center-line X. Once the smaller liquid jet  135  and the larger liquid jet  140  impinge, smaller liquid jet  135  penetrates and interacts with larger liquid jet  140  thereby creating a high shear intensity vortex contact layer  145  between the liquid jets  135 ,  140 . Cavitation caverns and bubbles are created in the high shear intensity vortex contact layer  145 . During the collapse of cavitation caverns and bubbles, high localized pressures, up to 1000 MPa, arise and the level of energy dissipation in the flow-through channel  205  attains a magnitude in the range of 1 10 -1 15  watt/kg. Under these physical conditions in the liquid, on the boundary of the bubble and inside the bubble itself in the gas phase, chemical reactions proceed such as oxidation, disintegration, synthesis, etc. After the cavitation bubbles collapse, the liquid is transported from the flow-through channel  105  to the outlet  120  indicated by arrow C.  
         [0031]    The device  100  according to the present invention is capable of receiving liquids having the same or different characteristics, which provides the operator with the ability to modify and control the desired cavitation effects. It is important to note that the first and second hydrodynamic liquid streams discussed above comprise a first and second liquid, respectively. The first and second liquids may be the same liquid, different liquids, or any combination thereof. Each liquid may be a pure liquid, a liquid containing solid particles, a liquid containing droplets, an emulsion of multiple materials, a slurry, or a suspension. Additionally, each liquid may be introduced to the device under different physical conditions and chemical compositions. Such physical conditions may include pressure, temperature, viscosity, and density. Such chemical compositions may include different chemical formulations and concentrations.  
         [0032]    Furthermore, although the second embodiment illustrates a flow-through channel having a pair of opposing jetting orifices disposed therein, it is contemplated that any chamber may be provided with a pair of opposing jetting orifices to practice the present invention. Such chambers may include tank, a pipe, a spherical vessel, a cylindrical vessel such as a drum, or any other desired shape. It is also contemplated that any size and shape may be possible provided that the liquid flow is permitted to enter the chamber. Such shapes may include cubical, conical, spherical, semi-spherical, or rectangular.  
         [0033]    [0033]FIG. 3 represents a third embodiment according to the present invention. FIG. 3 illustrates a longitudinal cross-sectional view of the device  200  comprising a flow through chamber  205  having an inlet  207  and an outlet  220 . The flow-through channel also includes a first ancillary inlet  210  and a second ancillary inlet  215 . The first ancillary inlet  210  includes a first jetting orifice  225  and the second ancillary inlet  215  includes a second jetting orifice  230 . The first jetting orifice  225  is oriented directly opposite the second jetting orifice  230  such that the first jetting orifice  225  and the second jetting orifice  230  directly face each other and share the same center-line X. The diameter of the first jetting orifice  225  is smaller than the diameter of the second jetting orifice  230 .  
         [0034]    In this embodiment, a first hydrodynamic liquid stream moves along the direction, indicated by arrow A, through the inlet  207  and flows into the flow-through channel  205 . As the liquid stream is passing through the flow-through channel  205 , a second hydrodynamic liquid stream, indicated by arrow B, enters the first ancillary inlet  210  and passes through the first jetting orifice  225  forming a high velocity liquid jet  235  (hereinafter referred to as “smaller liquid jet  235 ” because this liquid jet exits the smaller diameter jetting orifice  225 ) that flows into flow-through channel  205 . Additionally, a third hydrodynamic liquid stream, indicated by arrow C, enters the second ancillary inlet  215  and passes through the second jetting orifice  230  forming a high velocity liquid jet  240  (hereinafter referred to as “larger liquid jet  240 ” because this liquid jet exits the larger diameter jetting orifice  230 ) that flows into flow-through channel  205 . Both the smaller liquid jet  235  and the larger liquid jet  240  flow into the flow-through chamber  205  where they impinge along center-line X. Once the smaller liquid jet  235  and the larger liquid jet  240  impinge, smaller liquid jet  235  penetrates and interacts with larger liquid jet  240  thereby creating a high shear intensity vortex contact layer  145  between the liquid jets  235 ,  240  and the first liquid flow. Cavitation caverns and bubbles are created in the high shear intensity vortex contact layer  245 . During the collapse of cavitation caverns and bubbles, high localized pressures, up to 1000 MPa, arise and the level of energy dissipation in the flow-through channel  205  attains a magnitude in the range of 1 10 -1 15  watt/kg. Under these physical conditions in the liquid, on the boundary of the bubble and inside the bubble itself in the gas phase, chemical reactions proceed such as oxidation, disintegration, synthesis, etc. After the cavitation bubbles collapse, the liquid stream is transported from the flow-through channel to the outlet  220 , indicated by arrow D.  
         [0035]    The device  200  according to the present invention is capable of receiving liquids having the same or different characteristics, which provides the operator with the ability to modify and control the desired cavitation effects. It is important to note that the first and second hydrodynamic liquid streams discussed above comprise a first and second liquid, respectively. The first and second liquids may be the same liquid, different liquids, or any combination thereof. Each liquid may be a pure liquid, a liquid containing solid particles, a liquid containing droplets, an emulsion of multiple materials, a slurry, or a suspension. Additionally, each liquid may be introduced to the device under different physical conditions and chemical compositions. Such physical conditions may include pressure, temperature, viscosity, and density. Such chemical compositions may include different chemical formulations and concentrations.  
         [0036]    Furthermore, although the third embodiment illustrates a flow-through channel having a pair of opposing jetting orifices disposed therein, it is contemplated that any chamber may be provided with a pair of opposing jetting orifices to practice the present invention. Such chambers may include tank, a pipe, a spherical vessel, a cylindrical vessel such as a drum, or any other desired shape. It is also contemplated that any size and shape may be possible provided that the liquid flow is permitted to enter the chamber. Such shapes may include cubical, conical, spherical, semi-spherical, or rectangular.  
         [0037]    Although the invention has been described with reference to the preferred embodiments, it will be apparent to one skilled in the art that variations and modifications are contemplated within the spirit and scope of the invention. The drawings and description of the preferred embodiments are made by way of example rather than to limit the scope of the invention, and it is intended to cover within the spirit and scope of the invention all such changes and modifications.