Abstract:
A filtration apparatus and method for filtering a stream. The apparatus comprises a rotor that contains an inlet for the stream and an array of cavities operatively arranged to receive the stream from the impeller. The rotor member further includes membranes, operatively positioned within the array of cavities, for separating the impurities from the stream, and a permeate outlet for delivering a permeate from the rotor. A drive member is included for rotating the rotor so that the stream is exposed to a centrifugal force. In one preferred embodiment, the rotor contains a baffle plate to distribute the stream about the inner portion and an impeller vane adapted to receive the stream.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to an apparatus for separating impurities from a stream. More particularly, but not by way of limitation, this invention relates to an apparatus and method for separating impurities from a stream utilizing centrifugal forces. 
   Reverse osmosis (RO) is a filtration process for the removal of ionic and organic polluants from wastewater. Prior art techniques utilize a filtration process by which large arrays of high pressure piping and pressure pumps direct the affluent to filters. This process yields low volumes of filtrated output (permeate), utilizes large areas for pipe array ad components and concentration polarization and membrane fouling hinders the wide application of RO filtration process. 
   Prior art RO, ultra filtration, and nano filtration utilizes a static pressure flow across membranes to induce filtration. This process uses pressure vessel piping which causes a build up of sedimentation against these membranes which hinders the function of the cross flow membranes which results in a decrease in filtrate flux. This concentration polarization and membrane fouling limits the volume of permeate production which leads to not utilizing the standard RO process as a viable alternative to disposal. 
   Therefore, there is a need for an apparatus and method that will remove ionic and organic pollutants from a stream. There is also a need for an apparatus and method that will provide for an efficient reverse osmosis process. These and many other needs will be met by the invention herein disclosed. 
   SUMMARY OF THE INVENTION 
   A filtration apparatus for filtering a stream is disclosed. The apparatus comprises a rotor member having an inner portion and an outer portion. The rotor member comprises an inlet for the stream; an array of cavities operatively arranged to receive the stream from the impeller, with the array of cavities being arranged at a angle of between 45 degrees and 10 degrees relative to a horizontal axis of the rotor member. The rotor member further includes means, operatively positioned within the array of cavities, for separating the impurities from the stream, and a permeate outlet for delivering a permeate from the rotor bowl. The apparatus may also contain drive means, operatively connected to the rotor member, for rotating the rotor member so that the stream is exposed to a centrifugal force. 
   In one preferred embodiment, the rotor member contains a baffle plate to distribute the stream about the inner portion. The rotor member may also contain an impeller vane arranged on the inner portion of the rotor bowl and wherein the impeller vane is adapted to receive the stream. 
   The separating means may comprise a spiral wound membrane cartridge adapted to fit within the cavities. In one preferred embodiment, the rotor bowl contains a retentate outlet for delivering the retentate from the rotor bowl. The retentate outlet of the rotor member may contain a back pressure valve for regulating the pressure within the retentate outlet and keeping the retentate flowing in a radially inward direction. In the most preferred embodiment, the permeate outlet is directed to the outer portion of the rotor bowl so that the permeate is directed radially outward. Also in the most preferred embodiment, the retentate outlet is directed to an inner chamber located radially inward from the array of cavities so that the retentate is directed radially inward. In the preferred embodiment, the filter array is orientated at a angle between 60 degrees and 10 degrees relative to the horizontal axis of the rotor member, and in the most preferred embodiment, the filter array is orientated at an angle of approximately 45 degrees relative to the horizontal axis of the rotor member. 
   A method of separating an affluent is also disclosed. The method comprises providing a rotor apparatus, and wherein the rotor apparatus comprises a rotor member including an inlet for the stream; an array of cavities operatively arranged on the outer periphery of the rotor apparatus and adapted to receive the affluent; a membrane, positioned within the array of cavities, for separating the impurities from the stream and, a permeate outlet for delivering a permeate from the rotor bowl. The method further includes flowing the affluent to the inlet of the rotor apparatus and rotating the rotor apparatus. A centrifugal force is created within the inner portion of the rotor apparatus so that the affluent is forced to the outer periphery of the rotor apparatus. 
   The method further includes directing the affluent to the array of membranes arranged on the outer periphery of the rotor apparatus and separating the affluent in the membrane into a permeate stream and a retenate stream. Next, the permeate is produced from the rotor apparatus and the retentate stream is also produced from the rotor apparatus. In one preferred embodiment, the step of directing the affluent to the array of membranes includes channeling the affluent about a baffle arranged within the inner portion of the rotor apparatus. Also, the step of directing the affluent to the array of membranes includes channeling the affluent to a plurality of impeller vanes arranged on the inner portion of the rotor apparatus. 
   In one preferred embodiment, the permeate outlet is directed to the outer portion of the rotor bowl and wherein the step of producing the permeate includes directing the permeate radially outward. The method may also include the step of producing the retentate stream from the rotor apparatus by directing the retentate to an inner chamber located radially inward from the array of cavities so that the retentate is directed radially inward. Additionally, the method may include controlling the back pressure within the retentate outlet when producing the retentate stream from the rotor apparatus. 
   An advantage of the present invention is the centrifugal force that is created mimics pressures set up in a static pressure vessel by the tangential escape vector through the apparatus. Another advantage is that the present invention can use prior art vertical centrifuges that can be retrofitted to contain the membranes. Still yet another feature is that the present invention can be used as a reverse osmosis process to remove ionic and organic pollutants from a stream. 
   A feature of the present invention is that the created centrifugal forces also set up vortices which induce a spiral flow through the membrane that promotes sediment discharge enhancing the flux improving permeate volumes and membrane performance. Another feature is that the desired rotation speed of the centrifuge is determined by the desired filter pressure and type of filtration to be utilized. Another feature is a rotor bowl that holds the filter array that utilizes the force of the tangential escape vector velocity for particle separation. Another feature is that the filter array can be arranged about the periphery of the rotor bowl at an angle varying between 20 degrees to 50 degrees relative to the horizontal axis of the rotor bowl. 

   
     BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a partial cross-sectional view of the rotor member of the present invention. 
       FIG. 2  is an isometric view of an exploded view of the rotor member seen in  FIG. 1 , which includes the rotor bowl and rotor cone. 
       FIG. 3  is an isometric view of the rotor cone seen in  FIG. 2 . 
       FIG. 4  is a partial cross-sectional view of the assembled apparatus of the present invention. 
       FIG. 5  is a partial cross-sectional view of the rotor member seen in  FIG. 1 . 
       FIG. 6  is an exploded partial cross-sectional view of the membrane within a cavity. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIG. 1 , a partial cross-sectional view of the rotor member  2  of the present invention will now be described. More specifically, the rotor member  2  comprises a rotor cone  4  that is operatively connected to a rotor bowl  6 . The rotor cone  4  has an outer conically shaped wall  8 . At the apex of the outer wall  8  is the inlet  10 , and wherein the inlet  10  will allow for the entry of the stream as will be explained in greater detail later in the application. Extending radially inward, the rotor cone  4  has an inner conically shaped wall  12  that extends to the baffle  14 , and wherein the baffle  14  extends about the periphery of the inner wall  12 . The stream will be directed through the inlet  10  and the centrifugal force will tend to force the stream to the inner wall  12 . The baffle  14  will then channel the stream radially inward, as will be described in greater detail later in the application. 
   The rotor cone  4  also contains a circumferential cavity, denoted by the numeral  16 , and wherein the circumferential cavity  16  has contained therein internal thread means seen generally at  18 . The rotor cone  4  will be threadedly connected to the rotor bowl  6 . More specifically, the rotor bowl  6  contains a circumferential ridge  20  and wherein the circumferential ridge  20  has external thread means  22  that are configured to engage the internal thread means  18  so that the rotor bowl  6  is attached to the rotor cone  4 . It should be noted that other means for attachment are possible such as pinning the cone  4  and bowl  6  together. 
   The rotor bowl  6  contains an outer conically shaped wall  24 . As seen in  FIG. 1 , when the rotor cone  4  and the rotor bowl  6  are attached, the rotor member  2  has a conical shape.  FIG. 1  shows that the outer wall  24  contains outlets  26 ,  28  for the permeate, as will be described later in the application. The rotor bowl  6  contains an underside  30  of the rotor bowl  6  that in turn extends to an inner circular cavity, denoted by the numeral  32 , and wherein the inner circular cavity  32  extends to the base pedestal  34 . The retentate channels  35   a ,  35   b  are shown and wherein the retentate channels  35   a ,  35   b  direct the retentate into the cavity  32 . The retentate is the stream that has not been filtered and still contains undesirable components. The base pedestal  34  will be connected to the drive mechanism for rotating the rotor member, as will be described later in the application.  FIG. 1  also shows the retentate channels  35   c ,  35   d.    
   The rotor bowl  6  has a topside  36  and wherein the topside  36  contains the circumferential ridge  20 . The topside  36  contains a plurality of angled bores seen generally at  38 ,  40 . In the preferred embodiment, the angle of the bore is between 70 degrees and 10 degrees relative to horizontal, and in one preferred embodiment, the angle is between 50 degrees and 20 degrees relative to horizontal, and in the most preferred embodiment is 45 degrees relative to horizontal. The bores  38 ,  40  will have contained therein membrane members and wherein the membrane members will be in one preferred embodiment spiral wound membranes.  FIG. 1  shows membranes  45   a ,  45   b  disposed within bores  38 ,  40 . The membranes will be discussed in greater detail with reference to  FIG. 6 . Returning to  FIG. 1 , the topside  36  also contains a plurality of impeller vanes such as seen at  42 ,  44 . The impeller vanes  42 ,  44  receive the stream from the baffle  14  and directs the stream to the bores  38 ,  40  for separation within the membranes. 
   The flow in  FIG. 1  is represented by flow arrows as the rotor member  2  is being rotated. The flow arrows “A” depicts the stream entering the inlet  10 . The arrows “B” represent the stream that has been forced into the inner wall  12  due to the centrifugal force. The pressurized stream will be directed radially inward “C” due to the baffle  14 , and in turn, the stream is channeled into the impeller vanes  42 ,  44 . The pressurized stream, energized by the centrifugal force created due to the rotation of the rotor member  2 , will be separated within the membranes  45   a ,  45   b  as seen by arrows “D”. The separated stream (referred to as the permeate) is collected from the center tubes  46   a ,  46   b  of the membranes  45   a ,  45   b  and the permeate outlets  26 ,  28  are aligned with the center tubes  46   a ,  46   b  in order to channel the permeate radially outward from the rotor member  2  as seen by arrows “E”. The retentate is produced via the channels  35   a ,  35   b  from the membrane that has not entered the center tube (i.e. unfiltered fluid), as denoted by the arrow “F” into the circular cavity  32 . Note that both the retentate and the permeate will continue to be pressurized which in turn aids in removing the retentate and permeate from the rotor member  2 . A discussion of the flow through the membranes will be described with reference to  FIG. 6 . 
   Referring now to  FIG. 2 , an exploded isometric view of the rotor member  2  seen in  FIG. 1  will now be described. The rotor member  2  includes the rotor bowl  4  and rotor cone  6 . The impeller vane assembly  50  is shown in  FIG. 2 . The impeller vane assembly  50  consist of a plurality of impeller vanes. For instance, the impeller vane  42  and the impeller vane  44  from  FIG. 1  are shown. The impeller vanes are rigid, with a vertically extending surface radially mounted on the top side of the rotor bowl  6  that directs the stream to the angled bores and more particularly to the membranes.  FIG. 2  depicts a total of eight (8) vertically extending vanes, namely vanes  42 ,  44 ,  51   a ,  51   c ,  51   d ,  51   f ,  51   g.    
   In the preferred embodiment shown in  FIG. 2 , there are eight (8) angled bores included within the rotor member, namely the bores  38 ,  40  (previously described) as well as the bores  52 ,  54 ,  56  (not shown in this view),  58 ,  60 ,  62  (not shown in this view). In the most preferred embodiment, each bore will have an impeller vane that aids in directing the stream from the baffle to the membranes. Thus, the baffle  14  directs the stream that has been energized with the centrifugal force to one of the impeller vanes, namely vanes  42 ,  44 ,  51   a ,  51   b ,  51   c ,  51   d ,  51   f ,  51   g  which in turn directs the energized stream to the bores  38 ,  40 ,  52 ,  54 ,  58 ,  60 ,  62 . As mentioned earlier, the bores  38 ,  40 ,  52 ,  54 ,  58 ,  60 ,  62  will contain membranes that are used for separation and filtration purposes.  FIG. 2  also depicts the permeate outlets  26 ,  28 , as well as permeate outlets  29   a ,  29   b ,  29   c ,  29   d.    
   In  FIG. 3 , an isometric view of the rotor cone  4  seen in  FIG. 2  will now be described. This view depicts the underside portion of the rotor cone  4  so that the internal threads  18  are shown, along with the baffle  14 . In the most preferred embodiment, the baffle  14  extends about the periphery of the internal rotor cone  4  so that the stream that has been forced radially outward will come into contact with the baffle  14  and wherein the baffle  14  will then direct the stream to the impeller vane assembly  50  (not shown in this view). 
   Referring now to  FIG. 4 , a partial cross-sectional view of the assemblied apparatus of the present invention will now be described. The rotor bowl  6  is fixedly attached to a drive means  64 , such as an electric motor, for rotating the rotor bowl  6 . The rotor member  2  is generally encased within an outer shell  66 . The outer shell  66  includes an inlet passage  67  for the incoming stream. The outer shell  66  also includes a permeate outlet  68  that is operatively associated with all the permeate outlets (in this view showing outlets  26 ,  28 ), and wherein the first outlet  68  will direct the energized permeate from the outer shell  66  as shown by the arrow “G”. The outer shell  66  further includes a retentate outlet  70  that is operatively associated with the retentate outlet channels (in this view showing outlet channels  35   a ,  35   b ), and wherein the second outlet  70  will direct the energized retentate from the rotor member  2  as shown by arrow “H”. 
   In  FIG. 5 , which is a partial cross-sectional view of the rotor member  2 , the cavity  32  is shown, and wherein the cavity  32  is shown as an inner circular cavity, wherein the retentate channels, for instance retentate channel  35   a  and retentate channel  35   c , is directed radially inward to the cavity  32 . The impeller vane assembly  50  is also shown as well as the permeate outlets  29   a ,  26 ,  29   b ,  29   a.    
     FIG. 6  is an exploded partial cross-sectional view of the membrane  45   a  taken from  FIG. 1 . Hence, as the stream is channeled via the impeller vanes  51   a ,  44 ,  51   b ,  51   c ,  51   d ,  42 ,  51   f ,  51   g , the stream (which is under pressure due to the centrifugal force, and is referred to as the energized stream) will enter into the membrane  45   a . The membrane  45   a  may be a spiral wound membrane member that is commercially available from The Dow Chemical Company under the name FILMTEC Membranes. Membranes for reverse osmosis come in a variety of membrane materials but two important kinds are the thin-film composite membranes and the cellulose acetate membranes. It should be noted, however, that with respect to the invention herein disclosed, the specific composition of the membrane does not matter. In the preferred embodiment, the membrane will be configured in the spiral would cartridge design with a perforated permeate tube  46   a , outer housing and flow pattern as shown in  FIG. 6 . 
     FIG. 6  also depicts the back pressure valve  80  that is placed into the retentate channel  35   a  in order to regulate pressure within the membrane  45   a  and the outlet  26  which in turn prevents back flow back through the membrane  45   a  to the impeller vanes. The back pressure valve  80  is commercially available from Circle Seal Controls Inc. under the name 5100 Series Valve. As understood by those of ordinary skill in the art, the stream will interact with the membrane and wherein the filtered fluid (referred to as the permeate) will be directed to the center tube  46   a  (see arrows “J”). From the center tube  46   a , the permeate will be directed to the permeate outlet  26  (see arrow “E”). The unfiltered fluid (referred to as the retentate) will be directed through the membrane  45   a  (see arrows “D”) and then to the retentate channel  35   a  (see arrow “F”) which in turn is directed to the cavity  32 . Note that the center tube  46   a  is perforated and aligned with the permeate outlet  26 , while the remainder of the cross-sectional area of the membrane  45   a  will be in communication with the retentate channel  35   a . Hence, the stream “D” at the end of membrane  45   a  will enter the retentate channel  35   a.    
   Although the present invention has been described in terms of specific embodiments, it is anticipated that alterations and modifications thereof will no doubt become apparent to those skilled in the art. It is therefore intended that the following claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.