Abstract:
A static mixer tank includes upper/first and lower/second mixing chambers, with the two mixing chambers being separated by a swirl chamber. The upper mixing chamber is arranged at an upper end of the mixing tube where materials would initial begin passage there through, and the lower mixing chamber is arranged at a lower end of the mixing tube and receives materials that may have to some degree been mixed by their passage through the upper mixing chamber. A series of baffles in the mixing chamber are arranged in sinusoidal or saw-tooth pairs that can be oppositely arranged, so that the mixer turns a drop of water into hundreds of micro-bubbles of rotating fluid, which allows the chemicals to exit the mixer and react with fluid in a storage tank as much five times faster than previously known. A variation includes a sand trap using the swirl chamber, cap, diverter chamber, and diffusing plate to separate sediment from a liquid without using a filter of moving parts.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to fluid mixing devices and fluid—solid separating devices. More particularly, the present invention relates to fluid mixing devices and fluid—solid separating devices which include a static material mixing apparatus and a cap. The present invention also relates to methods of using same. 
   2. Description of the Related Art 
   Static mixers are known in the art as devices that provide a way to mix materials without a motor (or rotor) and the energy required to power the motor (typically by spinning) and/or provide a swirling and/or agitating action to cause the materials to mix without requiring an energy source for the mixing action to occur. 
   One such type of static mixer includes a number of vanes arranged sequentially within a conduit. Whereas it is normally desirable for a fluid to have a laminar (smooth) flow, the vanes are arranged to create a turbulent flow by having the material strike the vanes on its path through a conduit (e.g., a pipe or barrel) by dividing the flow into a series of sub-streams, and then causing the sub-streams to recombine with a swirling action when exiting a particular vane, only to strike a successive vane and subdivide again, followed by recombination. The action of the material dividing and recombining as it passes through the conduit results in a completely homogeneous mixture being discharged from the conduit. 
   In the aforementioned mixer, the vanes are often constructed of complicated geometric configurations that are not only expensive to manufacture, but have been known at times to cause large variations in the pressure of the materials as they are being mixed by their passage through the conduit. The large drops of pressure at some portions of the configuration of the vanes are particularly undesirable, as the difference in the pressure at different points may cause the acceleration of the fluid in the pipe to reach undesirable levels. 
   U.S. Pat. No. 4,511,258 to Federighi et al. (herein after “Federighi &#39;258”) incorporated herein by reference discloses a mixing element that is simpler to manufacture than the vanes and in many ways, more effective because there are no large drops in pressure. Federighi &#39;258 discloses a symmetrically formed mixing element to eliminate precision alignment with the conduit that was often necessary when using vanes. The mixing element includes two substantially identical segments having a sinuous cross-section between opposite ends. 
   In U.S. Pat. No. 4,936,689 to Federighi (hereinafter “Federighi &#39;689”) incorporated herein by reference, the inventor admits that certain prior art static mixers, which included those described in a previous patent (Federighi &#39;258), had a shortcoming that becomes evident when mixing liquids that contain solids; such mixers are prone to clogging. In order to keep the mixer from staying unclogged, repeated maintenance at constant intervals is required, but there also needs to be a monitoring system in place to make sure there is no clogging. Not only is the use of the prior art system inefficient and costly, but the unclogging can be unpleasant when the mixer is used to mix sanitation items, such as sewage. 
   In addition, Federighi &#39;689 discloses at column 3, lines 34-40 that a primary benefit of the invention is that solids suspended within the fluids can pass through an internal chamber  16  of the conduit  12  via a gap  21  between the radially spaced segments  14   a ,  14   b.    
   However, there are still clogging problems and varying drops in pressure within the conduit that are associated with prior art static mixers. Thus, there is a need in the art for an improved static mixer. 
   There is also a need for improved gas-liquid contacting and liquid-liquid contacting to enhance water treatment, e.g., water chlorination or water treatment with ozone, because the simple use of an in-line mixer is insufficient for efficient contacting in a small space. 
   There is also a need for improved compact sand filters. 
   SUMMARY OF THE INVENTION 
   The invention provides a static mixer including a tank and a mixing tube inside the tank. The mixing tube is made of an upper/first and lower/second mixing chambers, with the two mixing chambers being separated by a swirl chamber. Each mixing chamber provided with baffles to be a static mixer. The upper mixing chamber is arranged at an upper end of the mixing tube where materials would initially begin passage there through, and the lower mixing chamber is arranged at a lower end of the mixing tube and receives materials that may have to some degree been mixed by their passage through the upper mixing chamber. The downwardly directed mixed stream then reverses direction by passage into an inverted cap, which includes a diverting plate, at a lower end of the tube which discharges the fluid stream such that the discharged fluid stream continues to swirl and mix in the tank with the other fluid in the tank. 
   In particular, the mixing tube is typically a conduit comprising an upper mixing chamber, a swirl chamber, a lower mixing chamber and diverter valve (also termed a “diverter chamber”). The upper mixing chamber has a first inlet and a first outlet and an axial centerline in a longitudinal direction of main stream flow. The swirl chamber has a second inlet and a second outlet, the second inlet being in fluid communication with the first outlet of the upper mixing chamber. The lower mixing chamber has a third inlet and a downwardly directed third outlet and an axial centerline in the longitudinal direction of main stream flow, the third inlet of the lower mixing chamber being in fluid communication with the second outlet of the swirl chamber. A plurality of baffles are arranged within the upper mixing chamber and the lower mixing chamber, wherein the plurality of baffles are shaped and arranged for subdividing a flow of an additive material against a plurality of portions of an internal perimeter of the upper mixing chamber and the lower mixing chamber, and for redirecting the subdivided flow of the additive material to the axial centerline of the upper and lower mixing chambers to form a single direction mixing vortex axial to the centerline of the upper mixing chamber and the lower mixing chamber. The diverter chamber has sidewalls provided at a lower end of the conduit below the lower mixing chamber, the diverter chamber having a fourth inlet and a fourth outlet, the fourth inlet being in fluid communication with the third outlet of the lower mixing chamber and arranged in the longitudinal direction of the main stream flow of the lower mixing chamber, and the fourth outlet comprising a plurality of slits in the diverter chamber sidewalls, the slits being radially arranged relative to the axial direction of the lower mixing chamber. A cap is provided having a bottom wall and one or more cap sidewalls, the cap being connected to a lower portion of the diverter chamber, and the cap sidewalls spaced from the diverter chamber and having a height that extends upwardly at least approximately to a height of the plurality of slits to overlap the slits and define an annular region between inner surfaces of the cap sidewalls of the cap and outer walls of the diverter chamber. A diffuser plate is spaced from an upper edge of the cap to define a discharge area, the diffuser plate extending radially from the conduit to define a surface which overlaps the entire annular opening defined by an upper edge of the cap and the conduit, the diffuser plate being generally parallel to the upper edge of the cap. 
   The invention permits the mixing of liquid additives or gaseous additives to a liquid stream with increased efficiency than known heretofore in a static mixer. The internal design of the mixer turns a drop of water into hundreds of micro bubbles, which allows the chemicals to mix and react as much five times faster than a prior art static mixer. The micro bubbles increase the available surface area that can react with the other chemicals. 
   For purposes of illustration and not intended to limit the scope of the invention in any way, some of the multitude of materials that can be mixed using the present invention includes air, chlorine, ozone, fertilizer, phosphates, potassium, peroxide. The micro bubbles can be used to boost the effectiveness of air, chlorine, ozone, or anything else that is required to be mixed thoroughly. 
   The swirl chamber is formed by spacing the upper mixing from the lower mixing chamber by the desired length and circumference of the swirl chamber. The swirl chamber may optionally include a rotational passageway to assist in causing the liquid to continue to rotate (swirl) as it passes through the swirl chamber. 
   Moreover, the swirl chamber provides an advantage in that the materials to be mixed continue to spin while traveling downwardly toward the second/lower mixing chamber. The lower mixing chamber is optionally formed such that there are baffles arranged to cause fluid rotation in a direction that is opposite to the upper mixing chamber. 
   In one particular embodiment of the invention, the static mixer has first and second longitudinally elongated baffles. Each baffle has a plurality of attached segments forming a series of peaks and valleys resulting in a saw-tooth or sine curve longitudinal cross-section. Each segment extends from one peak of the respective baffle to an adjacent valley of the respective baffle. The peaks and valleys of the longitudinal cross-section of the first baffle alternate with the peaks and valleys of the longitudinal cross-section of the second baffle. 
   A method for mixing a first liquid material and an additive material in the static comprises the steps of: 
   passing a first liquid material and an additive material through an upper mixing chamber, a swirl chamber, a lower mixing chamber and a diverter chamber of a conduit in a tank; 
   the upper mixing chamber having a first inlet and a first outlet and an axial centerline in a longitudinal direction of main stream flow; 
   the swirl chamber having a second inlet and a second outlet, the second inlet being in fluid communication with the first outlet of the upper mixing chamber; 
   the lower mixing chamber having a third inlet and a downwardly directed third outlet and an axial centerline in the longitudinal direction of main stream flow, the third inlet of the lower mixing chamber being in fluid communication with the second outlet of the swirl chamber; 
   a plurality of baffles arranged within the upper mixing chamber and the lower mixing chamber, wherein the plurality of baffles are shaped and arranged for subdividing a flow of the first material and the additive material against a plurality of portions of an internal perimeter of the upper mixing chamber and the lower mixing chamber, and for redirecting the subdivided flow of the first material and the additive material to the axial centerline of the upper and lower mixing chambers to form a single direction mixing vortex axial to the centerline of the upper mixing chamber and the lower mixing chamber to form a mixed stream; 
   discharging the mixed stream from the lower mixing chamber downwardly into the diverter chamber; 
   discharging the mixed stream from the diverter chamber laterally through slits, radially arranged in sidewalls of the diverter chamber relative to the axial direction of the lower mixing chamber, into an annular region defined between outer walls of the diverter chamber and inner sidewalls of a cap and passing the mixed stream upwardly through the annular region, the cap having a bottom wall and the cap sidewalls, the cap being connected to a lower portion of the diverter chamber, and the cap sidewalls spaced from the diverter chamber and having a height that extends upwardly at least approximately to a height of the plurality of slits to overlap the slits and define an annular region between inner surfaces of the cap sidewalls of the cap and outer walls of the diverter chamber; 
   the mixed stream discharging from the annular region and being diverted by a diffuser plate spaced from an upper edge of the cap to define a discharge area, the diffuser plate extending radially from the conduit to define a surface which overlaps the entire annular opening defined by an upper edge of the cap and the conduit, the diffuser plate being generally parallel to the upper edge of the cap; 
   discharging the mixed stream from the discharge area such that the mixed stream has centrifugal motion when the mixed stream discharges from the discharge area and contacts the material in the tank; and 
   receiving the mixed material from an exit port of the tank arranged to receive the mixed stream as the mixed stream rotates upward in the tank. 
   In a second embodiment of the present invention, a sand trap having an internal swirl chamber permits water to pass the internal swirl chamber and into a diverting plate, to permit heavier particles to settle to the bottom of the tank for blow down. 
   In particular, the present invention provides a sandtrap device comprising: 
   a tank; a fluid outlet port arranged at an upper portion of the tank; a drain port arranged at a lower portion of the tank; a conduit comprising a mixing chamber and a diverter chamber inserted into the tank; a cap; and a diffuser plate. The mixing chamber has a first inlet and a first outlet and an axial centerline in a longitudinal direction of main stream flow. A plurality of baffles are arranged within the mixing chamber, wherein the plurality of baffles are shaped and arranged for subdividing a flow of an additive material against a plurality of portions of an internal perimeter of the upper mixing chamber and the lower mixing chamber, and for redirecting the subdivided flow of the additive material to the axial centerline of the upper and lower mixing chambers to form a single direction mixing vortex axial to the centerline of the upper mixing chamber and the lower mixing chamber. The diverter chamber has sidewalls provided at a lower end of the conduit below the mixing chamber, the diverter chamber having a second inlet and a second outlet, the second inlet being in fluid communication with the first outlet of the mixing chamber and arranged in the longitudinal direction of the main stream flow of the mixing chamber, and the second outlet comprising a plurality of slits in the diverter chamber sidewalls, the slits being radially arranged relative to the axial direction of the mixing chamber. The cap has a bottom wall and one or more cap sidewalls, the cap being connected to a lower portion of the diverter chamber, and the cap sidewalls spaced from the diverter chamber and having a height that extends upwardly at least approximately to a height of the plurality of slits to overlap the slits and define an annular region between inner surfaces of the cap sidewalls of the cap and outer walls of the diverter chamber. The diffuser plate is spaced from an upper edge of the cap to define a discharge area, the diffuser plate extending radially from the conduit to define a surface which overlaps the entire annular opening defined by an upper edge of the cap and the conduit, the diffuser plate being generally parallel to the upper edge of the cap. A length of the conduit within the tank chamber is approximately one-half to two thirds of a height of the tank. 
   In its method respects, the present invention provides a method for separating solids from liquid in the sandtrap device of the present invention, comprises: passing a feed stream comprising liquid and solids through a conduit comprising a mixing chamber and a diverter chamber inserted into a tank, the mixing chamber having a first inlet and a first outlet and an axial centerline in a longitudinal direction of main stream flow; passing the feed stream through a plurality of baffles arranged within the mixing chamber, wherein the plurality of baffles are shaped and arranged for subdividing a flow of the feed stream against a plurality of portions of an internal perimeter of the mixing chamber, and for redirecting the subdivided flow of the feed stream to the axial centerline of the mixing chamber to form a single direction mixing vortex axial to the centerline of the mixing chamber; downwardly discharging the feed stream into a diverter chamber having sidewalls provided at a lower end of the conduit below the mixing chamber, the diverter chamber being in fluid communication with the mixing chamber and arranged in the longitudinal direction of the main stream flow of the mixing chamber, discharging the feed fluid from the diverter chamber laterally through slits, radially arranged in sidewalls of the diverter chamber relative to the axial direction of the lower mixing chamber, into an annular region defined between outer walls of the diverter chamber and inner sidewalls of a cap and passing the mixed stream upwardly through the annular region, the cap having a bottom wall and the cap sidewalls, the cap being connected to a lower portion of the diverter chamber, and the cap sidewalls spaced from the diverter chamber and having a height that extends upwardly at least approximately to a height of the slits to overlap the slits and define an annular region between inner surfaces of the cap sidewalls of the cap and outer walls of the diverter chamber; the feed stream discharging from the annular region and being diverted by a diffuser plate spaced from an upper edge of the cap to define a discharge area, the diffuser plate extending radially from the conduit to define a surface which overlaps the entire annular opening defined by an upper edge of the cap and the conduit, the diffuser plate being generally parallel to the upper edge of the cap; discharging the feed stream from the discharge area such that the feed stream has centrifugal motion to separate at least a portion of the solids from the liquid in the feed stream when the feed stream discharges from the discharge area and contacts the material in the tank to produce a liquid product stream; receiving the liquid product stream from a fluid outlet port of the tank arranged at an upper portion of the tank to receive the liquid product stream as the liquid product stream rotates upward in the tank; and receiving the separated solids from a drain port arranged at a lower portion of the tank; wherein a length of the conduit within the tank chamber is approximately one-half to two thirds of a height of the tank. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other characteristics of the invention will be clear from the following description of a preferred form of the embodiments, given as non-restrictive example, with reference to the attached drawings wherein: 
       FIG. 1  is a schematic of a tank including a mixing device according to the present invention. 
       FIG. 2  is a cross section of an assembly of the diverter plate, diverter valve and cap of  FIG. 1 . 
       FIG. 3  is an exploded view of the components shown in  FIG. 2 . 
       FIG. 4  is a photograph of a static mixing device suitable for being employed in the embodiment of  FIG. 1  with portions of tube removed to show the internal baffles of the upper and lower mixing chambers. 
       FIG. 5  is a photograph of the upper mixing chamber of the embodiment of  FIG. 4  with a portion of the tube removed to better show the baffles. 
       FIG. 6  is a photograph of the lower mixing chamber of the embodiment of  FIG. 4  with a portion of the tube and the deflecting plate removed to better show the baffles. 
       FIG. 7  is a close up photograph of the end cap of the lower mixing chamber of  FIG. 4  with a portion of the tube and the deflecting plate removed to better show the baffles. 
       FIG. 8  is a perspective view of a pair of baffles having a small washer at one end and a larger washer at the other end. 
       FIG. 9  is a side view of a pair of baffles having a small washer at both ends. 
       FIG. 10  illustrates a single drop of additive. 
       FIG. 11  illustrates a single drop of additive subdivided into a plurality of micro bubbles to enhance mixing saturation. 
       FIG. 12  is a schematic drawing of a sand trap according to another embodiment of the present invention, wherein the sand trap separates solid particles from liquids without using a filter. 
       FIG. 13  illustrates an embodiment of the sand trap consistent with the embodiment of  FIG. 12 . 
       FIG. 14  is a photograph of an upper section of the embodiment of the sand trap of  FIG. 14 . 
       FIG. 15  is a close up photograph of an end cap suitable for the mixing section of  FIG. 14  with a portion of the tube and the deflecting plate removed to better show the baffles. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   It is understood by a person of ordinary skill in the art that the drawings are presented for purposes of illustration and not for limitation. The embodiments shown and described herein do not encompass all possible variations of the arrangement of structure, and an artisan appreciates that many modifications can be made within the spirit of the invention and the scope of the appended claims. 
     FIG. 1  is an illustration of a first embodiment  10  of the present invention having a tank  12  and a static mixing device  11  according to the present invention located within the tank  12 . The tank  12  has an outlet or drain valve  14  near a lowermost portion to facilitate drainage by gravity. The tank  12  may be filled with a first material  15 , which may or may not be a fluid material. A feed stream  2  including water and an additive feeds an upper end of the static mixing device  11 . In the mixing device  11  the water and additive are mixed to form a mixed stream  17 . Then in the tank  11  the mixed stream  17  mixes with the contents of the tank  11  and then exits the tank through discharge conduit  42  as a discharge stream  4 . 
   Still referring to  FIG. 1 , the mixing device  11  has an upper mixing chamber  16  and a lower mixing chamber  18  separated by a swirl chamber  20 , with an upside down cap  22  at the end of the lower mixing chamber  18 . The upper mixing chamber  16 , lower mixing chamber  18  and the swirl chamber  20  may have a conduit (or pipe or tube)  24  as an external housing. There can be a common conduit  24  or a series of connected conduits arranged to house the upper and lower mixing chambers  16 ,  18  and the swirl chamber  20 . Inside the conduit  24  is a passageway. The diameter of the conduit passageway can be either the same throughout or varied in size. At the end of the lower mixing chamber  18  there is a diffuser plate  46 , followed by a diverter valve  28  (also termed a diverter chamber), which provides an annular space between the lower mixing chamber  18  and the cap  22 . 
   As shown in  FIG. 1 , the diverter valve  28  (also termed a “diverter chamber”) has sidewalls  13  provided at a lower end of the conduit below the lower mixing chamber  18 , the diverter valve  28  has an inlet  15   a  and an outlet  28   a . The inlet  15   a  being in fluid communication with an outlet  17   a  of the lower mixing chamber  18  and arranged in the longitudinal direction of the main stream flow of the lower mixing chamber  18 . The diverter valve outlet  28   a  comprising a plurality of slits  28   a  in the diverter valve sidewalls  9 . The slits  28   a  being radially arranged relative to the axial direction of the lower mixing chamber  18 . The cap  22  has a bottom wall  6  and one or more cap sidewalls  13 , the cap  22  being connected to a lower portion of the diverter valve  28 , and the cap sidewalls  13  spaced from the diverter valve  28 . The cap  22  has a height L 1  that extends upwardly at least approximately to a height L 2  of the plurality of slits to overlap the slits and define an annular region between inner surfaces of the cap sidewalls of the cap and outer walls of the diverter chamber. Typical heights L 1  of the cap  22  range from about 1 to 3 inches. The diffuser plate  46  is separated from an upper edge of the cap  22  a distance “L 3 ”. Typically the diffuser plate  28  is located about 0.25 to about 2 inches, for example from about 0.5 to 1.5 inches, above the upper edge of the cap  22 . Typically the diffuser plate  46  has an annular shape. However, other shapes are also suitable. 
     FIG. 2  and  FIG. 3  illustrate the construction of the lower portion of the end cap of the mixing device according to the present invention.  FIG. 2 , which is a cross section of a cap such as shown in  FIG. 7 , is comprised of three parts that are preferably connected using an adhesive. However, an artisan appreciates there are other techniques to assembly the structure of the lower assembly. 
   For example, as shown in  FIG. 2 , the diverter plate  26 , which has an outer diameter “D 1 ” that is approximately the same size as the outer diameter “D” of the cap  22 , also has a stepped portion  465  complementary to a stepped portion  225  of cap  22 . The extension  46 A of the diffuser plate  46  is preferably bonded to the cap  22  at the meeting of the steps  225 ,  465 , but an artisan appreciates there are other way to connect these pieces to each other. In turn, the lower end of conduit  24  is inserted into the diffuser plate  46  to be seated in a central portion of the cap  22 , with the diverter valve shaft having an outer diameter D 2 . The central portion of the cap  22  can be sized to receive the conduit  24  as a type of friction fit, but an adhesive is preferably used to attach the conduit to the cap diffuser pale extension  46 A and the extension  22 A of the cap  22 . Adhesive may also be applied between the steps  225 ,  464 . 
   The diffuser plate  26  being spaced a distance “L 3 ” from an upper edge of the cap  22  to define a discharge area, the diffuser plate  46  extending radially from the conduit of the mixing device  11  to define a surface which overlaps the entire annular opening defined by the upper edge of the cap  22 . The diffuser plate  46  is generally parallel to the upper edge of the cap  22 . 
   An annular area (AA) is defined between the upper edge of the cap  22  and the walls  13  of the diverter valve  28  and a discharge area (DA) is defined by phantom cylindrical sidewall in the space from the upper portion of the inner sidewalls  13  of the cap  22  to the diffuser plate  46 . Typically a ratio of an annular area (AA) to the discharge area (DA) ranges from about 1:0.7-3, or from about 1:0.8-2, or from about 1:1-1.5. 
   For example, if hypothetically the annular area has an outer diameter of about 2.5 inches (radius of about 1.25 inches) and an inner diameter is about 1 inch (radius of about 0.5 inches), the annular area (AA) is calculated as follows:
 
AA=π[ r   o   2   −r   i   2 ]=[(1.25 inches) 2 −(0.5 inches) 2 ]=4.1 sq. in.
 
   and if the phantom cylinder discharge area (DA) has the diameter of about 2.5 inches and a height of about 0.6 inches, the discharge area (DA) is calculated as follows:
 
DA=π× d×h =3.14×2.5 inches×0.6 inches=4.7 sq. in.
 
   Thus, the ratio of AA:DA is 1:1.14 
     FIG. 4  is a photograph of a static mixing device suitable for being employed in the embodiment of  FIG. 1  with portions of tube removed to show the internal baffles of the upper and lower mixing chambers.  FIG. 2  shows an elongated pair of baffles for each of the upper and lower mixing chambers. 
     FIG. 5  is a photograph of the upper mixing chamber  16  of the embodiment of  FIG. 4  with a portion of the tube removed to better show the baffles  26 . 
     FIG. 6  is a photograph of the lower mixing section of the embodiment of  FIG. 4  with a portion of the tube and the deflecting plate removed to better show the baffles  26 . 
     FIG. 7  is a close up photograph of the end cap  22  of the lower mixing chamber of  FIG. 4  with a portion of the tube and the deflecting plate removed to better show the baffles. 
     FIG. 8  is a perspective view of the set of baffles  26  having a small washer  38  at one end and a larger washer  39  at the other end. The larger washer  39  of an upper set of baffles  26  is provided to contact the upper edge of the swirl chamber  20  to force flow from the upper chamber  16  through the center hole of the washer  39  into the swirl chamber  20 . The larger washer  39  of a lower set of baffles  26  is provided to contact the lower edge of the swirl chamber  20  to force flow from the swirl chamber  20  through the center hole of the washer  39  into the lower chamber  16 . The large washer is also useful to center the baffles  26  in the event a series of baffles are employed in either mixing chamber  16 ,  18 . 
     FIG. 8  shows the elongated baffles  26  are each made up of a series of segments  32  forming a series of peaks and valleys. The peaks and valleys generally follow a sinusoidal or saw-tooth pattern. This pattern of segments causes the fluid to disburse/splatter and lends itself to causing droplets to break up into a plurality of micro bubbles. 
     FIG. 9  illustrates the pair of baffles  30   a ,  30   b  removed from the conduit.  FIG. 9  is a perspective view of a pair of baffles  30   a ,  30   b  which differ from baffles  26  of  FIG. 6  in that the baffles  30   a ,  30   b  of  FIG. 9  have a small washer  38  at both ends.  FIG. 8  is a side view of the pair of baffles  30   a ,  30   b  of  FIG. 9 .  FIG. 9  shows the peaks and valleys of the longitudinal cross-section of first baffle  30   a  alternate with the peaks and valleys of the longitudinal cross-section of the second baffle  30   b  referring to  FIG. 9 , each of the baffles  30   a ,  30   b  has an inside edge  31   a  and an outside edge  31   b . The segments of the first baffle  30   a  define a first crossing location  34  on a portion of the inside edge between the peak and the valley of the first battle segment. Each segment of the second baffle  30   b  defines a second crossing location  36  on a portion of its inside edge between the peak and valley of the second baffle segment. The first crossing location  34  crosses, and typically is attached to, a respective second crossing location  36 . 
   Still referring to  FIG. 9 , each baffle width narrows in a direction transverse to each peak and value by anywhere from approximately 40% to 80%. Circular ends  38  are arranged at respective longitudinal edges of baffles  30   a ,  30   b . The circular ends are positioned substantially perpendicular to the longitudinal direction of the segments that comprise the baffle pair  30   a ,  30   b , and define respective axial holes at each end. 
   Typically, the circular ends  38  provide a uniform support structure as a base for the baffle pair  30   a ,  30   b . The diameter of each circular end  38  is usually less than an internal diameter of the conduit  24  in which it is arranged. The circular ends may also be constructed of different size diameters. For example, a first circular end can have a diameter that is large enough to extend to the internal diameter of the conduit  24 . In such a case, the second circular end can be made to be somewhat smaller in diameter than the first circular end so as to facilitate seating of the second circular end in another component of the device. It is also possible that the diameter of the second circular end can be larger than the first circular end. 
   Optionally, the baffles in the lower mixing chamber  18  can be arranged so as to be opposite of those arranged in the upper mixing chamber  16 . The arrangement of the baffles in the upper mixing chamber and lower mixing chamber can be designed to reverse the rotation of the fluid as it passes through the lower portion of the conduit after passage through the upper portion. 
   Referring to  FIG. 1 , the diffuser plate  46  extends radially from at least a lower portion of the conduit  24  housing the lower mixing chamber. The diffuser plate  46  has an annular area defined by its diameter, and is spaced from the upper portion of the cap  22  to define a discharge area. The ratio of the annular area to the discharge area ranges from 1: about 0.75 to 2, typically 1: about 1 to 1.5. This ratio assists to maintain a high flow rate out of the discharge area when desired to enhance the mixing in the tank outside of the tube. 
   A typical maximum flow rate through a mixing chamber of the embodiment of  FIG. 1  is 24 gallons per minute for a 12 inch inside diameter tank with a mixing chamber conduit having about a 1 inch inside diameter. 
   Still referring to  FIG. 1 , the directional diverter valve  28  has an upper end in fluid communication with an axial hole of the circumferential end of the pair of baffles in the lower mixing chamber. The cap  22  has substantially concentric sidewalls having a diameter larger than at least a portion of the diverter valve  28 , so as to define a channel there between. A series of openings  28   a  (e.g., slits) are provided in at least a sidewall of the diverter  28 . The sidewalls of the cap typically extend at least as high as a top of the openings  28   a.    
     FIG. 10  shows an illustration of one drop  60  of an additive, e.g. chlorine containing additive.  FIG. 11  shows this drop  60  transformed into a plurality of micro bubbles of the additive because of the design of the static mixer according to the present invention. As a result of the creation of micro bubbles, the present invention is faster and provides more efficient mixing of the additive to the liquid in the tank. 
   In operation, while referring to the embodiment shown in  FIG. 1 , where two materials are about to be mixed together, such as, for example a second material such as an additive such as chlorine and the first material  15  in liquid form (such as water in the tank  10 ), the chlorine can be poured into the inlet  40 . The interior of the tank  12  typically contains the second material and liquid first material  15 . Once the second material (in this case chlorine) is poured into the inlet  40 , the second material flows downward through the mixing chambers. 
   While passing through the upper mixing chamber  16 , the baffle pair  30   a ,  30   b  divides the flow into two downwardly flowing streams that subsequently recombine. In other words, the design of the baffles force the path of the streams to opposite outside walls of the conduit and then redirect the separated streams to the axial center to form a single direction mixing vortex axial to the centerline (longitudinal axis) of the mixing chambers. 
   As the liquid flows past the location where the two baffles cross, the mixing vortex is sheared and the main stream is divided again, but now flows in an opposite directional rotation. After exiting the upper chamber, the fluid enters the swirl chamber  20  prior to entering the lower chamber  18 . 
   In both the upper and the lower mixing chambers, the mixing is being performed around the axial centerline and in the direction of the main stream flow, having considerably less back pressure realized with better mixing than conventional static mixers. 
   The baffles in the lower mixing chamber  18  terminate in the lower mixing chamber  18 , and the fluid enters into the diverter valve  28 . The fluid flows through the slits  28   a  in the sidewalls of the diverter valve  28  with a centrifugal force causing it to rotate about a centerline of the diverter valve. Then the liquid is redirected upwardly (due to the cap) while still retaining its spinning motion through the annular space between the cap  22  and the diffuser plate  46 . The diffuser plate  46  redirects the upwardly spinning liquid to travel laterally with a spinning motion. 
   The diffuser plate  46  essentially turns the tank into a big mixing tank because the spinning motion of the liquid discharged from the diverter valve  28  causes the liquid  15  in the tank to rotate. The liquid mixed with the first material (in this case chlorine) then travels upwardly and discharges through a port  27  in an upper portion of the mixing tank typically alongside the top inlet. 
   Sand Trap 
   A second embodiment of the present invention is suitable for another use, namely to separate solids from liquids, typically to separate sand (or other solids) from water. 
     FIG. 12  is a schematic drawing of a sand trap  100  according to the second embodiment of the present invention. 
   The sand trap  100  contains a tank  120 , having an outlet or drain valve  140  near a lowermost portion to facilitate drainage by gravity. The sand trap  100  contains the at least one mixing chamber  200 , the cap  22 , the diffuser plate  26  and diverter valve  280  (also termed a “diverter chamber”) 
   Still referring to  FIG. 12 , the in-line mixer extends a distance “L” to be shorter than the mixer shown in  FIG. 1 , so as to leave a significant distance “H 1 ” above the bottom of the tank  120 . This distance “H 1 ” is approximately from about one-half to two-thirds of the height “H 2 ” of the tank  120 . 
   In operation, the sand trap  100  has water containing sand or other fine particles running through the swirl chamber  200  that exits via the diverting valve  280 . The water exiting the diverting valve has centrifugal movement. As the cap  220  redirects the spinning water upward and the diffuser plate  260  directs the spinning water laterally, the heavier particles, such as sand, shale, etc. will settle in the bottom of the tank for a blow-down via the drain  140 . Thus the sediment can be separated from the liquid without using any moving parts, and without requiring filter cartridges, electricity, or backwashing. Typical particle size of separated sand is that of “sugar sand.” A typical particle that can be separated by the present invention for example has a particle size such as 5 to 400 microns or 20 to 200 microns. Additional chemicals such as alum can be added if desired to the water to enhance separation. 
   The sand trap  100  separates solid particles from liquids without using a filter. As shown in  FIG. 12 , a feed stream  102  feeds the mixing device  200  located in a tank  120  provided as the conduit  202  containing a mixing chamber  206  employing a pair of baffles  223  ( FIG. 15 , baffles  223  shown in white) as a static mixer. The typical maximum flow rate through the mixing chamber  206  is 24 gallons per minute for a tank having an inside diameter of about 10 inches and a conduit  202  having an inside diameter of about 1 inch. 
   The tank  120  shown in  FIG. 10  is approximately 12 inches in diameter, but this size can be varied according to need. 
   The pair of baffles  223  is the same as or similar to the pair of baffles (see  FIG. 6 ) in the lower chamber  18  of the first embodiment. The mixing chamber  200  terminates into the diverter chamber  280  (also termed a “diverter valve”). The feed stream  102  discharges from the mixing chamber  200  into the diverter chamber  280 . The stream  102  then discharges through slits  216  provided in sidewalls of the diverter chamber  280  into an annular region defined between the outer walls of the diverter chamber  280  and the inner sidewalls  230  of an upside down cap  220 . The feed stream then exits from the annular region and is deflected by the diffuser plate  260  as stream  231  which enters the surrounding liquid in the tank  198 . Stream  231  has a centrifugal motion as it discharges from between the upper edge of the cap  220  and the diffuser plate  260  such that the solids travel radially and then downwardly while the liquids travel upwardly and discharge as product stream  250  through outlet conduit  252  which extends below the upper liquid surface  253 . 
   The diverter chamber  280  has sidewalls provided at a lower end of the conduit  202  below the mixing chamber  200 . The diverter chamber  280  has an inlet  214  and an outlet  216 . The inlet  214  being in fluid communication with the outlet  208  of the mixing chamber  200  and arranged in the longitudinal direction of the main stream flow of the mixing chamber  200 , and the outlet  216  comprising a plurality of slits  216  in the diverter chamber sidewalls. The slits  216  are radially arranged relative to the axial direction of the mixing chamber  200 . Typically, there are six slits arranged in the diverter chamber sidewalls, but this number can be increased or decreased according to need. About 30-70% of the wall space should have slits  216  therein, with about 50% being a typical construction. These percentages are provided as guidance but an artisan appreciates that it is within the spirit of the invention and the scope of the appended claims to use percentages outside of those disclosed above. An artisan may consider the viscosity of the fluids and in the case of the sand trap, the size of the particles, when selecting the number of slits and the amount of wall space in which they are arranged. 
   The cap  220  has a bottom wall  222  and one or more cap sidewalls  230 , the cap  220  being connected to a lower portion of the diverter valve  280 , and the cap sidewalls  230  spaced from the diverter valve  280 . 
   The cap  220 , conduit  202  and diffuser plate are typically assembled as described in more detail above for the cap  22 , conduit  24  and diffuser plate  46  of the water filtration device of  FIGS. 2 and 3 . Thus, a channel extends downwardly from the diffuser plate  260  and has a stepped portion (not shown) which interlocks with a complimentary stepped portion (not shown) of a channel extending upwardly from the lower inner wall of the cap  220 . Then the lower end of the conduit  202  is slid through the channel extending downwardly from the diffuser plate  260  into the channel extending upwardly from the cap  220  and glued in place to not entirely block the slits  216 . 
   An embodiment of the diverter valve  280  shown in  FIG. 12  typically has an outer diameter of about 1 inch. The outer diameter of the diffuser plate  26  is at least as large as the outer diameter of the cap  220 . A typical embodiment of the cap  220  shown in  FIG. 12  has an outer diameter of about 2.6 inches, and the outer diameter of the diffuser plate  26  is also about 2.6 inches. The cap  220  has a height “L 1 ” that extends upwardly at least about to a height “L 2 ” of the plurality of slits  216  to overlap the slits  216  and define an annular region between inner surfaces of the cap sidewalls  230  and outer walls of the diverter chamber  280 . Typical heights L 1  of the cap  220  range from about 1 to 3 inches, for example about 2 inches. 
   The slits  216  are typically about 0.9 to 1.6 inches high (L 2 ), and about 0.4 inches wide. A typical height (L 4 ) of the inner sidewalls  230  of the cap  220  is about 1.8 inches high measured from the upper surface of the floor of the cap  220  to the upper edge of the cap  220 , (with the floor of the cap being approximately 0.25 inches thick). Thus, “L 4 ” identifies the height of the annular region, which is taller than the slits  216 , and the highest portion of the slits  216  should be arranged below the upper portion of the sidewalls  230  so that the liquid exiting the slits travels upward to exit the annular region and strike the diffuser plate  260 . The diffuser plate  260  is separated from an upper edge of the cap  220  by a distance “L 3 ” of typically about 0.25 to about 2 inches, e.g., from about 0.5 to 1.5 inches. Typically the diffuser plate  260  has an annular shape. However, other shapes are also suitable. 
   The diffuser plate  260  is spaced a distance “L 3 ” from an upper edge of the cap  220  to define a discharge area. In an embodiment of  FIG. 10 , the height “L 3 ” is approximately 0.6 inches from the upper edge of cap  220  to the lower edge of the diffuser plate  260 . The diffuser plate  260  extends radially from the conduit  202  of the mixing device  200  to define a surface which overlaps the entire annular opening defined by the upper edge of the cap  202 . The diffuser plate  260  is generally parallel to the upper edge of the cap  220 . 
   Typically, the above-described ratios of the annular area of flow through the cap and the discharge area between the cap and diffuser plate of the embodiment of  FIG. 1  also apply to this sand trap embodiment. 
     FIG. 13  illustrates an embodiment of the sand trap  100  consistent with the embodiment of  FIG. 12 . 
     FIG. 14  is a photograph of an upper section of the embodiment of the sand trap  100  of  FIG. 13 . 
     FIG. 15  is a close up photograph of a white end cap suitable for substituting for the black end cap of the sand trap  100  of  FIG. 14  with a portion of the tube and the deflecting plate removed to better show the baffles  223 . 
   One significant advantage of the present invention is that is there is a low liquid usage rate, and thus a low flow rate through the mixing chambers and the tank, there is sufficient time for the liquid and the additive to achieve saturation. 
   In contrast, another advantage of the present invention is that if there is a high liquid usage rate, and thus a high flow rate through the tube and the tank, then there is increased mixing of the liquid and the additive to achieve saturation. 
   It is also clear that, although the invention has been described with reference to a specific example, a person of skill will certainly be able to achieve many other equivalent forms, all of which will come within the field and scope of the invention.