Abstract:
The present application is directed toward a method of destroying microorganisms using a device for treating a medium flowing through the device with a hydrodynamic cavitation field or a super cavitation field for destroying microrganisms contained in the medium.

Description:
CROSS-REFERENCES TO RELATED APPLICATION 
       [0001]    This application is a Continuation-In-Part of U.S. application Ser. No. 11/499,453 filed Aug. 4, 2006 and claims priority to German Application No. 10 2005 051 072.8 filed 25 Oct. 2005. 
     
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable 
       INCORPORATION-BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    The invention regards a degermination procedure. 
         [0007]    2. Description of the Related Art 
         [0008]    In particular liquid, at least flow capable media, e.g. water and waste water often are germ infested, thus contaminated with living microorganisms like viruses or bacteria, which have to be removed or at least deactivated. 
         [0009]    In a typical degermination situation bacteria are in drinking water or in useable water. 
         [0010]    The purification was done so far in various ways, depending on the application and the prevailing conditions: 
         [0011]    Chemical killing of the microbes is often performed through adding chemical substances destroying the living microorganisms, e.g. chlorine or ozone in a sufficiently strong concentration. 
         [0012]    Thereby one of the problems is, that though the mixing never is complete or 100%, it has to be assured, that at any location in the media a sufficient minimum concentration of the added chemical is present, which often means, that such a high concentration is provided in other locations, thereby causing detrimental effects for the user. 
         [0013]    Another customary possibility is the removal of the microorganisms from the medium through a cold procedure, e.g. through filtration. The disadvantage is that such fine filters require a very high manufacturing and maintenance effort, since they clog very quickly without sufficient maintenance and, thereby, become impermeable and unusable. 
         [0014]    Another possibility is killing the living microorganisms through heat and/or pressure, however, a very high energy consumption occurs. On the other hand, depending on the medium, through the necessary high temperature or pressure, desired chemical, physical or taste properties of the medium are influenced in a detrimental manner. 
         [0015]    On the other hand, the cavitation effect is known and is based on the fact that gas bubbles are created in a rapidly flowing liquid and imploded subsequently. During hydrodynamic cavitation, this occurs through high regional pressure differentials in the flowing liquid, mostly caused through strong variations in the flow velocity due to cross section contractions or expansions. 
         [0016]    Also known are ultrasonic cavitation and cavitation through local addition of energy, e.g. through a laser beam. 
         [0017]    The generation of hydrodynamic cavitation bubbles occurs in a moving liquid through a drop in static pressure below the vapor pressure of the liquid, forming vapor filled gas bubbles, e.g. due to a flow contraction. Subsequently, when the static pressure increases, again through an expansion of the flow cross section and the static pressure increases again above the vapor pressure, the gas bubbles collapse. 
         [0018]    The static pressure becomes zero or negative in water when the flow velocity increases beyond a certain value, depending on the environmental conditions, e.g. at the separation edges approximately 14 m/sec. 
         [0019]    The contraction and subsequent expansion of the flow cross section can be accomplished by locating an obstacle body in a flow chamber, wherein the remaining gap e.g. between the obstacle body and the surrounding housing of the flow chamber forms the gap. 
         [0020]    Through locating multiple obstacle bodies behind each other, due to space constraints, preferably shaped as discs perpendicular to the flow direction, the cavitation effect is multiplied, in particular, through reducing the annular gap surface in flow direction from one disc to the next. 
         [0021]    In addition to the first cavitation field forming in the annular gap area, supplemental cavitation fields are created in the flow-through cavities between the obstacle bodies, and through spatial superposition of the particular cavitation fields a so called super cavitation field is created, causing a multiplication of the cavitation effect of each single cavitation field. 
         [0022]    Thereby, it is state of the art to provide the reduction of the area of the annular gap in flow direction through:
       a sequence of discs as obstacle bodies, increasing in size in flow direction, forming a cut off cone in their entirety in a surrounding cylindrical housing as flow through chamber, e.g. according to DE 44 33 744, or   in an also conical housing as flow through chamber, however with less conicity than the conicity of the cone or cut off cone formed by the obstacles, so that a reduction of the annular gap in flow through direction is still present, e.g. according to EP 1 280 598, wherein a so called hydrodynamic super cavitation field is created.       
 
         [0025]    It is, for example, state of the art to use the cavitation effect created in this manner for mixing a suspension or emulsion with minor effort and without mechanically driven parts. 
         [0026]    When the collapse of a large number of bubbles, so called cavitation bubbles occurs in proximity to the separation surface between two phase areas, e.g. large oil droplets in water, thereby the second component, in this case the oil droplets are divided into smaller units and, thereby, a very fine mixture of the two components and a very fine suspension or emulsion are created. 
       BRIEF SUMMARY OF THE INVENTION 
       [0027]    It is an objective of this invention to deactivate microorganisms permanently, in particular living microorganisms in a flow capable medium, in particular a liquid, with comparatively low energy consumption, without negatively influencing the other properties of the medium. 
         [0028]    Subsequently a “flow capable medium” is always called a “liquid” without limiting the invention thereto. 
         [0029]    The objective is to implode the thus generated cavitation bubbles under a pressure so high that the cellular membranes of the microbes close to the bursting bubble, or also in the bubble, tear open, thereby killing the microbes. Therefore, the pressure differentials occurring at the obstacles have to be strong enough, and preferably the total pressure level of the operation of the cavitator has to be high enough. 
         [0030]    Through providing a first obstacle body as an impact plate, thus with an impact surface providing an obstacle in flow direction as strong as possible, wherein the impact surface is flat or even concave towards the first flow component, a partial destruction of the microbes can be accomplished through impact alone. 
         [0031]    The impact, therefore, is strongly mixing in particular, since beyond the first obstacle body there is no holder protruding against the flow direction of the first component, since this first and also the subsequent obstacle bodies can be held on a holder shaped as a central axis, protruding from the opposite direction, this means against the flow direction, in the center of the flow chamber. 
         [0032]    Since in flow direction, after the entrance opening, first a cross-section contraction, and then a cross section-expansion, both preferably conical, occur. Through the cross-section expansion a vacuum is created in the flow-through chamber in front of the impact plate, which improves the function. 
         [0033]    A flow-through gap decreasing in size, measured in main flow direction can, especially in combination with the impact of the first component onto the first obstacle body, be accomplished through the obstacle bodies decreasing in size in main flow direction and thereby also the length of the annular gap around the obstacle bodies, thereby forming a narrowing cone in flow direction. 
         [0034]    Thereby, a wall of a surrounding housing can run parallel to the cone of the obstacle bodies, or even have more conicity (larger angle at the tip of the cone), which increases the effect of the decreasing annular surface. But, also a reduced cone shape (smaller angle) at the tip of the housing is possible, slightly reducing the effect through the cone shape of the obstacle bodies. 
         [0035]    The effect of the cross-section expansion and of the turbulence is even better when between the cross-section expansion and the impact plate a section with approximately constant cross section of the housing is located in order to stabilize the pressure conditions over the cross section. 
         [0036]    The liquid is exhausted through an exhaust opening, flowing out of the housing preferably in a radial manner, in particular shaped as a radial gap. 
         [0037]    The efficiency of the device, typically inserted into an existing tubular conduit, can be increased through—e.g. depending on the flow velocity in the in feed tube, the viscosity of the particular components and their mix ability—adjusting the obstacle bodies in a radial manner, the distance amongst each other, and/or in groups, or even in their entirety, relative to the surrounding housing, whereby in a conical housing also the absolute size of the annular gaps is changed. 
         [0038]    Furthermore, it is advantageous for the obstacle bodies to be plate-shaped in order to simplify the manufacture and to make them less expensive and, in particular, to make them thin enough so that they can oscillate at their free ends in flow direction, facilitating the generation and separation of vapor bubbles. 
         [0039]    Also, this development is facilitated through providing the separation edges of the obstacle bodies, thus e.g. the plates, as sharp as possible. 
         [0040]    The flow through gap between the obstacle bodies and the housing can, for example with round obstacle bodies, thus discs, be the radial gap between the free circumferential edge of the discs and the surrounding housing. 
         [0041]    However, other embodiments are possible wherein the plate-shaped obstacle bodies at their radial outermost point reach the housing and are connected with it in this location, but e.g. not along the whole circumference, but only in segments, and in the segments between radially extending slots or gaps are provided which can be radially spaced amongst each other and can be spaced from one obstacle body to the next, serving as flow through gaps. 
         [0042]    The formation of vapor bubbles and, thereby, the occurrence of cavitation is furthermore facilitated through the length of the separation edges being as long as possible. For this purpose, especially when the obstacle bodies are disc shaped with their circumference forming the separation edge, these can be increased in length through an undulated or serrated shape wherein the non-linear profile can be present when viewing in axial direction, in lateral direction, or in both directions. 
         [0043]    If the non-linear, thus undulated or serrated, shape is visible in axial direction, the surrounding housing—seen in axial direction—can be also shaped in an analogous manner so that over the whole circumference a respectively constant cross section between housing and separation edge can be maintained, or the housing is internally round, so that the distances to the separation edge change in circumferential direction. 
         [0044]    When the device is additionally provided so that during its operation certain flow conditions are maintained, the cavitation effect is pronounced in particular. 
         [0045]    Thus, the cross-section contraction after the intake opening should be sized so that the flow velocity at the tightest location of the cross-section contraction corresponds to the flow velocity in the flow gap of the last obstacle body. Correspondingly, the flow velocity thereafter, at the exhaust after the last obstacle body, should be slightly higher than in the flow gap at the last obstacle body. 
         [0046]    A particularly simple embodiment is provided when discs with constant diameter in flow direction are provided as obstacle bodies and the decreasing annular gap is provided through a contraction of the housing in main flow direction. However, this effect is less pronounced than with conically decreasing obstacle bodies, discs in particular. 
         [0047]    Advantageous is, furthermore, a strong cross-section contraction behind the intake opening so that from the intake opening to the tightest spot of the cross-section contraction the flow velocity increases by a factor of 9-13, in particular, by a factor of 10-12, in particular, by a factor of 10.5-11.5. 
         [0048]    It is, furthermore, advantageous when the obstacle bodies relative to each other and/or to the surrounding housing are positioned and sized so that the flow velocity in the flow-through gap at the last obstacle body in flow direction, compared to the flow through gap at the first obstacle body is increased by a factor of 1.8-2.5, in particular by 2.0-2.3. 
         [0049]    The same is true when it is accomplished that the flow velocity from one obstacle body to the next obstacle body in the respective flow-through gap increases by a factor of 1.1-1.4. 
         [0050]    As an optimum compromise between simple construction and high efficiency of the device, a number of obstacle bodies between 3 and 10, in particular between 5 and 7, has become apparent. When, with discs made from metal, from stainless steel in particular, the thickness is between 1 mm and 4 mm, in particular between 2 mm and 3 mm, the manufacture is very simple. A cutting plane perpendicular to the main plane of the plates can be used and the plates are still sufficiently elastic. 
         [0051]    The axial distance from the middle to the middle of two neighboring obstacle bodies should be between 2 times and 7 times the thickness of the plates, in particular 3 times to 5 times. 
         [0052]    The radial width of the annular gap between the exterior circumference of the plate-shaped obstacle bodies and the housing should be between 1 and 5 mm, in particular between 1.5 and 3.8 mm. 
         [0053]    Furthermore, an axial length of the section with constant cross section of the housing between the cross-section expansion and the impact plate, of 0.7 to 1.4 times the diameter after the cross-section expansion, thus, of the constant cross-section, has proven advantageous. 
         [0054]    Also, the interior free diameter after the cross-section expansion, thus in the section with constant cross section, should be between 0.9 times and 2.0 times, in particular between 0.9 times and 1.1 times the free cross section of the in and/or out flowing conduit. 
         [0055]    Preferably, especially the first obstacle body provided as an impact plate, possibly also the second obstacle body, will have a much larger extension in axial direction than the other more plate-shaped obstacle bodies. These first obstacle bodies, which are thicker in axial direction, preferably have a circumferential annular concave indentation along their outer perimeter so that they each have two circumferential annular concave indentation along their outer perimeter so that they each have two annular circumferential, axially spaced separation edges, wherein the indentation should correspond at least to the size of the radial width of the annular gap, preferably be a multiple of this gap. 
         [0056]    The separation edges are particularly efficient when they have an acute angle of less than 60°, seen in cross section, in particular less than 50° or even less than 45°, being sharp in particular. 
         [0057]    Thereby, preferably, the first separation edge in main flow direction of the first obstacle body should still be in the section of constant interior diameter of the housing, and only the second, as well as all other separation edges should already be located in the axial area of the decreasing interior diameter of the housing. 
         [0058]    Overall, the device should be sized and shaped so that over the whole length of the device a pressure drop of at least 2.5 bar, better 4.5 to 5 bar is accomplished. 
         [0059]    For availability in longitudinal direction, several obstacle bodies can be put together in a group so they can only be moved in longitudinal direction along the central axis, in particular, in the area of the last obstacle bodies which reduces the complexity of the construction, but only decreases efficiency in a negligible manner. 
         [0060]    A process for destroying microorganism contained in a flowable capable medium of the present invention includes the steps of creating gas bubbles and imploding them through hydrodynamic a first component therein in a main flow direction into an intake opening in a cavitator device having a housing, one exhaust opening, a flow through chamber located between the intake opening and the exhaust opening, and a plurality of obstacle bodies with planes perpendicular to the main flow direction being located in the flow through chamber, the cavitator device further having a flow-through gap formed between edges of the obstacle bodies and the surrounding housing wherein the obstacles bodies have sharp separation edges; passing the flow capable medium through a first conical cross-section contraction and into a short conical cross-section expansion thereby creating a vacuum in the flow-through chamber in front of a first obstacle body; feeding in a second component through a hollow conduit having a central axis and an opening therein into the flow-through chamber in a second flow direction facing against main flow direction and in front of first obstacle body; stablizing pressure conditions by forming a constant cross section of the housing between the cross-section expansion and the first obstacle body to increase the effects the cross-section expansion and turbulence; partially destroying the microbes found in the flow capable medium by impacting them against the first obstacle body in the flow direction as strong as possible; continuing cavition of the medium next to a plurality of obstacle bodies located in main flow direction in the housing having decreasing free diameter; and exhausting the component through the exhaust opening. 
         [0061]    An alternate embodiment is a method of destroying microorganisms using the device described herein for treating a medium flowing through the device with a hydrodynamic cavitation field or a super cavitation field for destroying microorganisms contained in the medium. 
     
     
       DETAILED DESCRIPTION OF THE DRAWINGS 
         [0062]    Embodiments according to the invention are subsequently described in more detail. 
           [0063]      FIG. 1  shows the cavitator as a separate component. 
           [0064]      FIG. 2  shows the complete device, that is, the cavitator installed in a conduit 
           [0065]      FIG. 3  shows a longitudinal cut view through a part of the cavitator. 
           [0066]      FIG. 4  illustrates a cross section through a part of the cavitator. 
           [0067]      FIG. 5  illustrates a cross section through another design of the cavitator. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0068]      FIG. 1  shows the cavitator by itself having a conduit as a housing  2 , preferably rotationally symmetrical to a main-flow direction  10 , shown in  FIGS. 1 and 2 , flowed through by a first component  21  in main-flow direction  10  from the right to the left. 
         [0069]    Thereby, a left, open-front face forms an intake opening  3   a  for the first component  21  flowing into a flow-through chamber  5 , hereby initially passing a conical cross-section contraction  13  up to a tight section  18 . 
         [0070]    Thereafter, comes a substantially faster, thus shorter, cross-section expansion  14  to a free pass through, approximately corresponding to the free pass through at the intake opening  3   a  or slightly larger, but with an expansion section of only ⅕ to 1/10 of the length of the contraction section. 
         [0071]    Thereafter, follows a section  17  with constant diameter of the flow-through chamber  5 , after which a longer section of conical decrease of the free cross section follows with a subsequent expansion with an equal rate. 
         [0072]    Cavitation occurs next to obstacle bodies  7   a,b,c , located in flow-through chamber  5 , the first of which is still in the area of section  17  with constant interior diameter, and the others are located thereafter in main-flow direction  10  in the area of the decreasing free diameter. 
         [0073]    The obstacle bodies  7  are located on a central axis  15  protruding from the side of the exit opening  4  in the center of flow-through chamber  5 , protruding into it, ending with a first obstacle  7   a.    
         [0074]    With a central axis  15  provided as a hollow conduit  16 , it serves as an in feed for a second component  22 , thereby being inducted into flow-through chamber  5  in flow direction  12 , thus in reverse flow to flow direction  11  of first component  21 , originating in the second in feed opening  3   b , thus in the front face of first obstacle body  7   a  facing against main-flow direction  5 . 
         [0075]    First obstacle body  7   a , thereby, serves as an impact plate  9  for first component  21  with an impact surface  9   a , concave against flow direction II of first component  21  and having a second intake opening  3   b  for second component  22  at its deepest point. 
         [0076]    First obstacle body  7   a , shaped as an impact plate  9 , has the largest cross section, while the following obstacle bodies  7   b  and  7   c  have a correspondingly decreasing cross section, preferably analogous to the decreasing free diameter in flow-through chamber  5  so that the radial width of the annular flow-through gap  6  between the obstacle body and the surrounding housing  2  in flow direction  10  remains constant or decreases. 
         [0077]    Obstacle bodies  7   a - d  shown as examples have several axially spaced circumferentially extending separation edges  8  protruding most against housing  2 . 
         [0078]    A third obstacle body  7   c , seen in a longitudinal cut view, is provided with an annular groove at its outer circumference, confined in axial direction in front and in back by a separation edge  8  having two flat impact surfaces parallel to each other and exactly perpendicular to the axial direction. 
         [0079]    Flanges of the annular grooves in the enveloping surfaces of these obstacle bodies transition into these front faces with an acute angle so that separation edges  8  are formed, whose angle at the foremost separation edge, thus at the impact surface  9   a , is approximately 45°, and both angles in the separation edges even are below 45°. 
         [0080]    Fourth obstacle body  7   c  consists of several, in this case three, axially spaced and solidly connected radial discs with constant thickness, whose narrow outside enveloping surfaces are parallel to the flow direction  10  and, thereby, perpendicular to the disc plane. A single disc is shown as obstacle body  7   b , which will be the preferred shape for obstacles. 
         [0081]    Preferably, obstacle bodies  7   a, b, c  are separately adjustable along central axis  15 . In addition, the whole axis  15  is adjustable in axial direction, as can best be seen from  FIG. 2 , showing the installation of the mixer  1  into an existing conduit  19 . 
         [0082]    From conduit  19  initially an angulation and an offset in parallel to the initial extension of the conduit  19  is created through elbows  23 , including shut off valves  24 , located in the in feed and out flow of mixer  1 . 
         [0083]    Through the two additional elbows  23 ′, through which a transition is provided into the now parallel offset extension of the conduit  19 , the cavitator  1  can be mounted in parallel to the initial extension of conduit  19  between the two elbows  23 ′. 
         [0084]    In this manner, straight central axis  15 , which can serve as a conduit  16  for feeding second component  22  at the same time, can be run out through the exterior wall of one elbow  23 ′ and can there be supported relative to a support  23 ′, and can be axially adjusted through a thread and a locking nut  26 . 
         [0085]      FIG. 2  shows that the free cross-section at intake opening  3   a  and at exhaust opening  4  corresponds to the free cross-section of the remaining conduit  19 , and that housing  2  of the cavitator is provided in two parts, wherein the one part  2   a  is the housing part where obstacle bodies  7  are located, and the other housing part  2   b  is the one containing the cross-section contraction in front of the obstacle body and the subsequent cross-section expansion. 
         [0086]      FIG. 3  shows a particular embodiment of obstacle bodies  7  shaped as preferably single, however, at least at their outer perimeter, thin discs  7 ′. Their thickness relative to their material elasticity is selected so that they can flexibly oscillate in and against flow direction  10 , whereby the occurrence of the cavitation effect is accelerated. For this purpose, discs  7 ′ are held in their center, and the discs are possibly provided thinner than the rest at the level of their free circumferential edges. 
         [0087]      FIGS. 4 and 5  show particular designs of flow-through gap  6 . 
         [0088]    In  FIG. 4 , analogous to  FIGS. 1 and 2 , it is assumed that flow-through gap  6  is an annular gap between the interior obstacle body  7  and housing  2 , radially surrounding obstacle body  7  on the outside. 
         [0089]    For extending separation edge  8 , thus of the circumferential outer edge of obstacle body  7  and thereby for improving the cavitation effect,  FIG. 4  shows how an extension can be accomplished, seen in longitudinal direction, through an undulated or serrated shape of separation edge  8 . When flow-through gap  6  shall have constant width over its circumference, also the inside contour of housing  2  is shaped analogous. 
         [0090]      FIG. 5 , on the other hand, shows a solution wherein flow-through gap  6 ′ is not an annular gap between obstacle body  7 ″ and housing  2 . To the contrary, obstacle body  7 ″ is partially connected with housing  2  at its outer perimeter, however, obstacle body  7 ″ comprises, from the outer edge towards the inside almost into the center, several approximately radially extending flow-through gaps  6 ′ which, for example, can expand radially from the inside to the outside. These approximately radially extending separation edges  8  can be provided straight and can extend exactly radially or also serrated (separation edge  8 ′) or they also can be provided undulated (separation edge  8 ″). 
         [0091]    In order to improve the cavitation, flow-through gaps  6 ′ of the particular obstacle bodies axially arranged behind each other can be offset in circumferential direction, as shown in the right half of  FIG. 5 . 
         [0092]    The surfaces F 6  of flow-through gaps  6  can thereby change in flow direction  10  from one obstacle body to the next in a defined manner, e.g. they can be reduced, by making the opening angles of these segment shaped flow through gaps in flow direction smaller and smaller and/or due to the reduction of the interior diameter of the flow-through chamber, thus of housing  2 .