Abstract:
An apparatus for charging particles in non-conductive liquids, so they agglomerate and can be removed by filtering, is comprised of a housing which contains a non-conductive insert having a multiplicity of channels. The incoming stream is divided into two halves, each of which is flowed through a set of charging channels which contain electrodes, preferably metal brush-like electrodes. One set of electrodes is charged to a high positive voltage; the other set is charged to a high negative voltage. The liquid streams are then merged and flowed trough a set of mixing channels, along the path of which are one or more reversals in flow direction. The mixing channel path length is substantially longer than the charging channel path length.

Description:
This application is a continuation of patent application Ser. No. 11/973,225, filed Oct. 10, 2007, now abandoned. 
    
    
     TECHNICAL FIELD 
     The present invention relates to filtering of non-conductive liquids by a process which includes flowing the liquid past high voltage electrodes. 
     BACKGROUND 
     A particular kind of apparatus, such as described in U.S. Pat. No. 5,788,827 of Munson, has been used in commerce for removing very fine particles from non-conductive liquids, such as lubricating oil used in large machines. The process carried out by the apparatus involves dividing a liquid stream into two portions, and contacting the portions respectively with high voltage positive and negative electrodes, so that the particles become charged. Then, the liquid stream portions are re-combined, and the particles agglomerate, making them much easier to remove by downstream depth filtration. 
     There is a continuing desire to improve the performance of the foregoing kind of apparatus, and to provide apparatus which is more easily and economically constructed than in the past. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to improve an apparatus and method for filtering, in particular to improve the way in which particles are charged. A further object is to simplify and reduce the cost of the construction and assembly of particle-agglomerating filtering apparatus. Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be apparent from the following description and the accompanying drawings. 
     In accord with an embodiment of the invention, a stream of non-conductive liquid containing particulate contaminant is treated by dividing the stream into two halves and flowing the stream halves through separate charging channels which contain charging electrodes. One set of charging channels has electrodes with a high positive voltage; the other set of one or more charging channels has electrodes charged to a high negative voltage. For example, up to 15,000 volts plus and 15,000 volts minus may be used. Upon exiting the charging channels, the two liquid streams are merged and flow along a lengthy up and down path within a set of one or more mixing channels. Due to the effects of the high voltage and the charge imparted to the particles, the particles agglomerate in the mixing channels, which facilitates their subsequent removal from the liquid. In an improvement, the electrodes are comprised of conductive bristles, preferably a row of metal bristles which spirals along a conductive post; and preferably there are three parallel helical bristle electrodes in three parallel charging channels. 
     In an embodiment of the invention, channels run vertically up and down along the length of the body of a non-conductive plastic insert contained within a housing which receives and discharges the oil stream being treated. A bottom cap and upper cap are mated with an insert body, to direct the flow between the channels in the body. The inflow to the insert is first divided into two separate stream portions by the top cap. Each portion flows through a set of charging channels, preferably vertically down channels in the body of the insert. At the bottom of the body is a bottom cap which merges the two stream half portions. The merged liquid stream flows upwardly to the top cap, and then downwardly through the body to the bottom cap, and then again to the top cap, through a set of one or more mixing channels. The stream then exits the top cap, and flows to the outlet of the housing within which the insert is contained. The length of the flow path from beginning to end of the mixing channels is substantially greater, preferably about three times greater, than the flow path length from beginning to end, through the charging channels. The cross sectional area of the entry openings of the charging channels is substantially greater than the cross sectional area of the mixing channels, preferably about three times greater. 
     In use of the invention, particles within the liquid are charged and agglomerate. The invention is convenient to fabricate and assemble. The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of preferred embodiments and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is an isometric view, partially cut-away, of a housing. 
         FIG. 2  is an isometric view of an insert, comprised of a body, top cap, and lower cap, which is placed within the housing of  FIG. 1  during use. 
         FIG. 3  is an isometric view of a three unit charging electrode assembly. 
         FIG. 4  is a top view of the insert body of  FIG. 2 , showing the directions in which liquid flows within the vertical-running channels of the insert body. 
         FIG. 5  is an isometric view of an insert body showing in phantom the internal liquid flow channels. 
         FIG. 6  is an exploded isometric view of an insert with one of two charging electrode assemblies. 
         FIG. 7  is a view looking downwardly on the top cap of the insert. 
         FIG. 8  is a plan view showing the interior side of the insert top cap. 
         FIG. 9  is a vertical cross section view of the insert top cap, along line  9 - 9  of  FIG. 7 . 
         FIG. 10  is an isometric view looking showing the upper side of the insert top cap. 
         FIG. 11  is an isometric view showing the interior side of the insert top cap. 
         FIG. 12  shows the lower or exterior surface of the insert bottom cap. 
         FIG. 13  shows the upper or interior surface of the bottom cap. 
         FIG. 14  is a sectional view of the insert bottom cap along line  14 - 14  of  FIG. 13 . 
         FIG. 15  is an isometric view showing the lower or exterior surface the bottom cap. 
         FIG. 16  is an isometric view showing the upper or interior of the bottom cap. 
         FIG. 17  is top view of the insert of  FIG. 2  showing the electrodes in position in the channels. 
         FIG. 18  is a side elevation sectional view of the insert of  FIG. 2  with the electrodes in place, taken along line  18 - 18  of  FIG. 17 . The arrows show the liquid flow paths. 
         FIG. 19  is top view like  FIG. 17 . 
         FIG. 20  is a side elevation sectional view like  FIG. 18 , taken along line  20 - 20  of  FIG. 19 . The arrows show liquid flow paths. 
         FIG. 21  is top view like  FIG. 17 . 
         FIG. 22  is a side elevation view like  FIG. 18 , taken along line  22 - 22  of  FIG. 19 , and showing the paths of the liquid. 
     
    
    
     DESCRIPTION 
     This application is a continuation of application Ser. No. 11/973,225, filed Oct. 9, 2007, the disclosure of which is hereby incorporated by reference. The invention embodiments herein are described with reference to the illustrations, which for convenience of description show the apparatus in vertical orientation, typical of how the device is used. However, the invention may be used in other orientations. 
     In an embodiment of the invention, a housing  30  contains an insert  40  which has a multiplicity of internal channels for liquid flow. Liquid being treated enters the top end of the housing and is divided into two streams as it enters the channel openings at the top of the upper part of the insert. Each stream flows internally in the insert, first past a charging electrode and then to a point of merger with the other stream. The merged streams then flow through a series of channels, finally to the top of the insert, and then to the exit of the housing. 
       FIG. 1  shows housing  30  in partial cutaway. Housing  30  may be the housing of a commercial filter used for other kind of filtering apparatus; in particular, it may be a portion of a 15/40/80CN Series filter assembly sold by Parker Hannifin Corporation, Metamora, Ohio. (As sold by Parker Hannifin, the filter assembly comprises a filter element and an electric sensor. These are not used in the invention.) Housing  30  has a fitting  41  for passage of two electrical leads  32  through the wall of the housing. Each lead respectively carries positive and negative voltage to terminals  90  at the upper ends of each of the two charging electrode assemblies  80 , as described below. 
       FIG. 2  shows a non-electrically conductive insert  40  which is, during use of the apparatus, inserted into interior cavity  43  of housing  30 . Insert  40  is an assembly of three separately fabricated elements, namely top cap  60 , body  62 , and bottom cap  66 . The exploded view of  FIG. 6  shows how the portions fit together and how they contain the electrodes. Top cap  60  of insert  40  is secured to body  62  by means of four screws  64 ; and, bottom cap  66  is secured to the body  62  by means of four screw  68 . Index marks  70  are provided on the mating pieces to insure that those portions are properly aligned to each other upon assembly. Insert  40  may be constructed of nylon, or another non-electrically conductive material compatible with the liquid being handled. Insert body  62  has a plurality of round channels,  50 ,  52 ,  54  and  102 . As will be appreciated, the diameter of the channels may vary according to the size of the housing and the liquid flow contemplated. 
     In use, when insert  40  is positioned within housing  30 , the liquid being treated flows through the inlet  47  of the housing  30  into portion of interior cavity  43  which is above the insert. Skirt  49  of the housing  30  extends downwardly from the interior top of the housing; and, it is received in the recess  51  of insert top cap  60 , and sealed by o-ring  69 . Thus, the in-flowing liquid can only flow around the exterior of skirt  49 , and the liquid flows to and through the six open upper ends of a first set of three channels  50  and a second set of three channels  52 , which open ends are arranged around insert top cap  60 , as can be seen in  FIG. 10 . 
     As described further below, the two sets of channels  50  and  52  comprise two parallel flow paths. In particular, the three channels  50  define a first flow path for a first stream portion. And the three channels  52  define a second flow path for a second stream portion. The symmetry of the upper openings of the channels  50 ,  52  at the top of the insert  40  comprises means which causes approximately fifty percent of the liquid to follow each of two parallel stream flow paths. The channels  50 ,  52  which contain electrodes  81  are called charging channels because particles in the liquid are charged by the electrodes in such channels. The other channels of the insert are called flow-mixing channels, because the liquid streams which exit the two sets of the charging channels have flow through them as merged streams. After traveling within the insert and through the mixing channels, liquid exits insert  40  by flowing out of the two upper ends of channels  54  in top cap  60 , and then toward housing exit port  53 . See  FIGS. 2 ,  10  and  22 . 
       FIG. 3  illustrates one of two electrode assemblies  80 , also called charging assemblies. Each assembly  80  is comprised of three electrical elements  81 , which are also referred to as charging electrodes. The three electrodes are electrically connected in parallel at their lower ends by trident bus  83 . The electrodes  81  of a first assembly  80  are positioned within the three parallel channels  50  of the insert  40 . The electrodes  81  of a second charging assembly  80  are positioned in the three parallel openings  52 . See the exploded view of  FIG. 6  (where only one of the two assemblies  80  is shown for simplicity of illustration). The cutaway view of  FIG. 18  shows a charging assembly in position within the insert. As shown in  FIG. 16 , as well as  FIG. 18 , the insert bottom cap  66  has six supports  87 , for supporting the electrode assemblies at the trident busses  83 . 
     Each electrode  81  comprises a post  85  of about one-eighth inch diameter. The bottom ends of the posts  85  connect to trident bus  83 . In each electrode  81  a multiplicity of bristles project radially outwardly from the post  85  and toward the bore of the channel in which the electrode is positioned. The row of bristles helically rises (spirals) upwardly along the length of the post. The turns of the bristle row are spaced apart vertically on one-quarter inch centers. The bristles comprise wires and the electrode is about 0.9 inch diameter. As pictured, each electrode  81  extends nearly fully along the length of the channel in which it is positioned. Each electrode assembly  80  has an electrical connector  90  at its upper end, for connection to one of electrical leads  32  illustrated in  FIG. 1 . Charging electrodes  80  are made of stainless steel, or another electrically conductive material compatible with the liquid handled. 
       FIG. 5  shows the path of the channels inside body  62  of insert  40 .  FIG. 4  indicates the direction of the flow in each channel, with “D” indicating that the flow is down, and “U” indicating that the flow is up. “D.B.” indicates that the flow is downwardly and also past a charging electrode. 
       FIGS. 19-22  are cross sections of the insert in different planes. The bold arrows in the channels indicate the direction in which liquid flows within the channels of three parts  60 ,  62 ,  66  of the insert. The drawings and flow indications are mutually supportive of how the insert is constructed and the method of the invention. In brief, the divided halves of the liquid stream, which down-flow past the charging assemblies, meet in space  120  of the bottom cap. The re-merged or mixed liquid then flows upwardly to the top cap, then downwardly to the bottom cap again, then upwardly to and through the top cap and out of the housing  30 . 
       FIGS. 12-16  illustrate insert bottom cap  66 . The bottom cap is shaped so that liquid, which flows downwardly through channels  50  of the insert body and into the cap  66 , flows into cavity  120 . Likewise, liquid flowing downwardly through channels  52  flows into cavity  120 . The two liquid streams merge in cavity  120  and flow upwardly through diametrically opposed channels  100  of body  62 . Note that channels  100  are located between the diametrically opposed sets of channels  50  and  52 . The remainder of the channeled flow in the insert, which is upward, downward and then upward again, enables mixing of the merged streams. 
       FIGS. 7-11  illustrate insert top cap  60 . Cavity  110  connects one up-flow channel  100  with a down-flow channel  102 . Cavity  112  connects the other opposing side up-flow channel  100  and the opposing side down-flow channel  102 . See  FIG. 20 . 
     Referring again to  FIGS. 12-16 , cavity  122  of insert bottom cap  66  connects the lower ends of both down-flow channels  102 . Liquid which is thus further mixed in cavity  122  flows upwardly through the up-flow channels  54  to the top cap. See  FIG. 22 . Liquid then exits the top cap, to flow within the interior of skirt  49  and then out the exit  53  of housing  30 . 
       FIGS. 17-19  and  21  show the wire bristle electrodes in the charging channels.  FIG. 17  is a view looking down onto insert  40 .  FIG. 18  is a vertical cross section of the same insert. The Figures show how the wire bristle charging electrodes fit closely into the bores of, and the bristles extend radially so the electrodes have essentially the same diameters or widths of their respective channels  50 ,  52 . Charging electrodes  80  impart a charge to fine particulate contamination in the liquid. The opposing polarity voltages are sufficient to later effect particle agglomeration in the mixing channels; up to about 15,000 volts plus is applied to one electrode assembly and up to about 15,000 volts minus is applied to the other electrode assembly. 
     From the foregoing and drawings, it will be understood that half the liquid which enters the housing will flow downwardly through the openings of the channels containing positive electrodes and particles therein will become positively charged. And half the liquid will flow downwardly through the openings of channels containing negative electrodes and particles therein will become negatively charged. 
     As illustrated, each of the two sets of charging channels comprises three parallel channels, each channel having a length which is about that of the insert body  62 . In contrast each of the two parallel sets of mixing channels is seen to comprise three channels in series. It is seen that the liquid flow path length of a charging channel is the distance from the entry (top) end of the set to the discharge (bottom) end of the set. That is, the length is nominally the length of the body  40 . It is seen that the liquid flow path length through a mixing channel set is similarly the distance between the entry (e.g., at the bottom of channel  100 ) and the exit (e.g., the top of channel  54 ). That is, the path length comprises three channels  100 ,  102 ,  54  connected in series together with the paths through the cavities in the upper and lower caps; and thus, the path length is nominally at least three or more lengths of the body  40 . 
     Thus, each mixing flow path length is nominally three or more times greater than the two identical charging channel set path lengths. There are two u-bends, or flow reversals, pictured along the length of each mixing channel path. If the initial flow direction reversal in cavity  120  is counted, there are three u-bends or reversals downstream of the charging channels. As shown in the drawings, that all channels have the same diameter. Thus, they show that the total cross sectional entry area of one set of mixing channels (e.g., the area of channel  100 ) is one third the total cross sectional entry area of one set of charging channels (i.e., the total of the areas of the openings of the three channels  52 ). 
     In the embodiments of the present invention described above, it will be recognized that individual electrodes and/or features thereof are not necessarily limited to a particular embodiment but, where applicable, are interchangeable and can be used in any selected embodiment even though such may not be specifically shown. 
     Spatially orienting terms such as upper, lower, bottom, vertical, and the like, refer to the positions of the respective elements shown on the accompanying drawing figures; and the present invention is not necessarily limited to such positions. 
     Although this invention has been shown and described with respect to one or more embodiments, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.