Abstract:
The present invention comprises an insertion type electrode adapted to operate at modulated high voltages by use of a thin layer polyer as a dielectric.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to electrostatic treatment of fluid systems and more particularly to the construction and operation treating devices having electrostatic fields. 
     Apparatus for the treatment of moving liquid by causing electric current flow or discharge therein and/or impressing electrically induced fields thereacross have been known for many years, but the application of such devices to common industrial and domestic problems, such as water system scaling and clogging, has met with varying success. Some installations have appeared to be functional while others which seemed to be operating under generally similar circumstances obviously failed and no broadly accepted reasons for the different results have been advanced. The optimum type, size and characteristics of a treater to produce desired and reliable results in a particular environment appear to have been unnecessarily limited with respect to DC voltage imposed on the electrostatic field. A predictive method is disclosed in U.S. Pat. No. 4,073,712 wherein a positively charged axially placed conduit electrode insulated by a dielectric material provides an electrostatic field through flowing water in the conduit whereabout the conduit has a negatively charged electrode, thereby providing a three capacitor system. 
     A large number of factors and complex interactions are apparently involved in the treating process. This seems logical since such liquid systems are themselves usually highly complex, including variations in dissolved salts, suspended solids, turbulence, pH, piping, electrical environment, temperature, pressure, etc. Many liquid clogging mechanisms, including water system scaling, involve the electrostatic relations between suspended particles, the carrier liquid and the walls of the piping network. Thus, an electrostatic field effectively developed across a section of flowing water primarily affects not only the water, but mainly suspended, especially colloidal size, particles immersed in the water. The effect of the field will depend, in large measure, upon the relationship of the natural electrostatic charge on such immersed particles to the electrostatic charge on the various surfaces of the treater and how the latter charge induces a response on the liquid contacting surfaces of the piping network. If relative conditions are proper, the particles will be urged by the field to remain in suspension or migrate toward a charged electrode isolated from the walls of the piping network, thus reducing the tendency to form flow restricting deposits. The reduction of colloid particles which are capable of acting as seeds for nucleation of scale building crystal formations results in reduced tendency for scale deposition. 
     The natural electrostatic charge on the immersed particles in the liquid, or more accurately, the overall charge effect of the various groups of particles normally associated in the same system, can be determined by known procedures, but the control of the electrostatic charge on critical treater surfaces has been heretofore very limited due to configuration of the electrodes. The present invention reverses a decades old method of fabricating conduit electrostatic field treatment devices such that the positive, ground electrode is situated generally within the axial space of the conduit, whereabout are situated dielectric insulated negatively charged electrode(s) such that the liquid flowing in the conduit becomes negatively charged for later process advantage. 
     The electrostatic field between particular water treater surfaces, in large part, can be predicted and controlled by limiting certain parameters in treater construction and installation, especially the dielectric constant of the insulating material or materials in contact with the water, the efficiency of the insulating material or materials and seals in preventing charge leakage, and the physical size ratio of the treater parts which form the surfaces producing the electrostatic field across the water complex under treatment. The word “water”, as used herein, means water complexes containing dissolved and suspended solids, etc., as are normally found in a great many industrial and domestic applications. Of more importance, however, is to provide a method whereby high DC voltages may be effectively developed across the flowing fluids. 
     The manipulation of electrical potentials, to produce relationships within certain parameters calculated from an equation which presents a mathematical model of the treater as three capacitors connected in series, results in operable treaters, while devices having relationships falling outside those parameters are apparently less-functional or only marginal in operation. The parameters of those variables are described with reference to a specific example below. 
     The principal objects of the present invention are: to provide operable and efficient electrostatic water treaters; to provide such treaters which function to predictably inhibit the formation of scale from colloidal particles immersed in flowing water; to provide a treater construction which substantially reduces the formation of scale in piping systems and may function to remove scale already formed; to provide a method of designing operable and efficient electrostatic treaters for particular installations; to provide a method of treating water to reliably inhibit the formation of certain clogging deposits in the piping system containing same; to provide a dependable alternative to many types of chemical water treatment; and to provide such methods and apparatus which have wide application in improving desired properties of water for industrial and domestic purposes at minimal cost and maximum safety. 
     In specific examples of the invention, DC voltage is applied across the electrodes at a range unexpectedly high in relation to the teaching of the prior art in this field. The placement of sufficient axially facing positively charged electrode surface area or a plurality of separate electrodes and surfaces about an axial space-occupying negative ground electrode dramatically increase the surface area in which negative charge may be extended into the flowing liquid, thereby permitting comparatively extremely high DC voltages. 
     The present invention comprises an insertion type electrode adapted to operate at modulated high voltages by use of a thin layer polymer as a dielectric. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a cutaway section of a treater according to the present invention. 
     FIG. 2 in a cross sectional view of cylindrical conduit treater according to the present invention. 
     FIG. 3 is a cutaway side view of an treater according the present invention whereby an inlet and outlet portions are formed at a right angle to the treater conduit. 
     FIG. 4 is a cutaway side view of an treater according the present invention whereby an inlet and outlet portions are formed with straight-on flanges for abutting conduits for connection to the treater conduit. 
     FIG. 5 is a top view of a plate embodiment of the treater of the present invention. 
     FIG. 6 is the Section A—A of FIG.  5 . 
     FIG. 7 is side view of an improvement of a vessel-insertable or conduit-insertable electrode as disclosed in U.S. Pat. No. 4,073,712, which is incorporated herein by reference. 
     FIG. 8 is the section B—B shown in FIG.  7 . 
     FIG. 9 is a side view of a threaded base supporting electrode of the present invention. 
     FIG. 10 is a cross section CC of FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is now discussed with reference to the Figures. In FIG. 1, a treater section  100  is adapted to operation within a cylindrical support conduit  101 , which is preferably made of PVC or fiberglass or similar relatively non-conductive material as compared with metal pipes. The present invention contemplates the use of a wide variety of support conduit materials, not excluding metal pipes and other such conductive conduits, however it is most preferred that the immediate support tube layer closest to the positive electrode  102  consist primarily of non-conductive polymer materials. As shown in FIG. 2, the separation of the electrode  102  and support conduit  101  is improved with addition of a non-conductive insulation epoxy layer  104  which may optionally and preferably form a continuous protective sheath between the cylindrical support conduit  101  and cylindrical electrode  102 . The addition of this epoxy layer  104  may in some circumstances be sufficient, in addition to or in combination with an intervening non-conductive support conduit  101 , to permit the use of a more structurally acceptable metal support conduit about the electrode  102  without severely disabling the electrostatic capacitance required for operation of the present treater. 
     Electrode  102  is connected to a positive DC power source, with appropriate filters to smooth typical AC “ripple”, capable of producing at least about 10,000 VDC. When a flowing fluid is moved through dielectric/negative electrode space  107 , negative electrode  102  is connected to ground, thereby permitting a novel method of particulate and colloid treatment by using the large surface area of the enclosing walls of a liquid tight conduit for presentation of the positive electrical field instead of the smaller surface area of the axial space filling electrode  105 . As shown in FIG. 2, a consideration of the collection of positive charges at the liquid containing walls of dielectric  103  will allow the viewer to appreciate that the greater volume of liquid will pass close to the inside wall of dielectric  103 , and thus through the positive electrical field, than to the outside wall of negative electrode  105 . The prior art comprises a consistent teaching that the reverse polarity should by used for generating electrostatic fields through flowing liquids for imposing on the particles a positive charge. The present invention comprises not only a reverse polarity, but also use of a DC voltage range from about 10,000 to 40,000 VDC or higher with an extremely low power usage of about 5 watts. 
     In a specific example of the present invention as shown in FIG. 1, 30,000 VDC are applied across electrode  102 , a relatively thin copper cylinder with little structural support, to electrode  105 , a stainless steel pipe about 1.5 inches OD and extending down the axial cross section of treater  100 , through dielectric  103 , comprising Kevlar or an equivalent dielectric which forms a liquid tight seal about the axial facing portion of electrode  102  with the support conduit  101 , as shown in FIGS. 3 and 4. Support conduit  101  comprises PVC of sufficient strength and thickness to maintain longitudinal support for the flowing fluid and structural integrity of a liquid tight seal between dielectric  103  and support conduit  101 . It will be apparent to the skilled person that electrode  102  must be entirely isolated from liquid flowing in space  107  to maintain appropriate capacitance for the electrostatic field to be imposed across space  107 . In this specific example, space  107  is about {fraction (1/25)} inches with cooling water flowing in that space at about 200 gallons per minute. 
     The present treater  100  is improved with two other specific embodiments as shown in FIGS. 3 and 4. FIG. 3 is generally a right angle inlet/outlet embodiment  200  such that flowing liquid enters inlet pipe  206  and flows into chamber  204  of right angle connector  203 , whereafter the flowing liquid passes to the inlet of the conduit embodiment of the treater of the present invention, of which treater  100  is a part and at the inlet of which is situated in-line or static mixer  207 . Flow  209  describes the turbulent flow of the liquid relatively violently against the walls of dielectric  103  such that the flows is driven primarily against its positively charged field. It has been found that the prior art rods and pipes used as the positive electrode could produce an effective electrostatic field of only about 1.0 inches about the electrode. The present invention, however, has dramatically improved the performance of the electrostatic treating field of the conduit treaters with this reversal of polarity. 
     In FIG. 3, the flowing liquid continues in turbulent flow along space  107  between electrode  105  and dielectric  103  through a second mixer  208 , into chamber  202  of right angle connector  201 , whereafter the flowing liquid passes to outlet  212 . It may be appreciated that electrode  102  comprises a cylinder of conductive material connected to positive DOC current source  210  and encased in a liquid tight containment of the cylinder ends of dielectric  103  sealed to the overlapping cylinder ends of support conduit  101 . Negative ground electrode  105  rests with one end in support  205  in the inside wall of connection  203  and extending through the axial space of the cylinder defined by electrode  102  through chamber  202  and the wall of connection  201  with liquid tight seal  211  to the exterior of connection  201  for connection to a ground. 
     Similarly, a straight flow inlet/outlet embodiment  200 ′ is shown in FIG. 4, wherein flanges  213  are adapted to connect to straight sections of liquid carrying conduit and whereby the treated liquid flows through space  107 . Static mixers  207 ′ create turbulent flow but also support electrode  105 , which is connected to ground  214 . 
     In yet another embodiment of the present invention, FIG. 5 shows a top view of a plate comprising, as shown in FIG. 6, a top insulating and support layer  303  adapted to form a liquid tight seal about positive electrode  102 ′ in conjunction with dielectric  103 ′. Dielectric  103 ′ comprises Kevlar or an equivalent liquid sealing and long lasting polymer is coextensive with the downward face of electrode  102 ′ and is sealed at its edges with layer  303 . A ground electrode  105 ′ is separated from the downward face of dielectric  103 ′ and is coextensively normal to its downward face such that an electrostatic field is formed in space  107 ′. Legs  302  raise the assembly of layer  303 , electrode  102 ′ and dielectric  103 ′ above electrode  105 ′ such that a space is created having apertures between that assembly and the upward face of electrode  105 ′, whereby liquids may flow therebetween and particulates and colloids may obtain a mainly singular charge. 
     The lengths of the treater  100  sections commercially appropriate for many applications comprise lengths of 18, 24 or 36 inches depending on flow rates, particulate concentration, polarity of the liquid, degree of required particulate non-aggregation or surface adhesion in a downstream process or application, and other such variables. 
     The present invention also comprises using one treater  100  section of the above embodiments to produce a liquid stream of primarily positively charged particulates and a treater generating such an electrostatic field that a second liquid stream comprises primarily negatively charged particles, whereafter the first and second liquids are flowed quiescently into a common container, albeit from opposite sides of the container. The container will thereby have therein an interface zone between a positive zone in which the first liquid exists with positively charged particles and a negative zone in which the second liquid exists with negatively charged particles. The interface zone thereby induces a state of preferential aggregation such that the aggregates may, upon reaching critical size and density in relation the motion of the liquid in the interface zone, fall to the bottom of the container to be easily removed without substantially adhering to the walls of conduits or the container. 
     In another embodiment of the present invention, the above embodiments may be used in the specific applications of treating liquids from chillers, cooling towers, steam boilers, tubesides of heat exchangers, plate and frame exchangers, reverse osmosis systems, river water, domestic hot water loops, commercial dishwashers, ice machines, machine shop coolant systems, nozzle sprayers, scrubber systems and water softening systems. 
     With reference to FIGS. 7 and 8, an improvement of a vessel-insertable or conduit-insertable electrode  700  is shown. One of the most important requirements of liquid treatment by electrostatic field wherein the positive field is disposed about an axially located electrode as shown in U.S. Pat. No. 4,073,712 is to create as much liquid flow through the effective electric field range as possible, thereby causing a greater percentage of particulates evenly distributed through the flowing liquid to be affected by the electric field. When laminar flow occurs across the insertable positive electrode, the system configuration and electric field strength, when all particulates must be within the effective electric field, are strictly determined by the distance from the outsided surface of the insulating dielectric of the positive electrode to the inner surface of the conduit or vessel. It is a further invention to provide within such a laminer flow conduit or vessel a positive electrode having integral flow turbulating means such that laminar flow liquids approaching the electrode are moved about the positive electrode and are substantially all the particles lying within the flowing liquid are brought within the effective electric field although theoretically outside of the effective electric field range as predicted in U.S. Pat. No. 4,073,712. 
     FIG. 7 shows the insertable electrode  700  having a turbulating length  701  comprising structural support composite  709 , conductive layer  710  and dielectric layer  711 , as shown in FIG.  8 . The generally disclosed “twists” in length  701  comprise in the side view of FIG. 7 the sloping ridge  704  and sloping valley  705 . Length  701  is connected electrically to threaded connector  702 / 703 . 
     Electrode  7  is preferably and most inexpensively fabricated from a single piece of composite polymers and fibers or a single polymer such that it may effectively provide all the structural support needed by the electrode  700  to accomplish the objects of this invention. The single piece is originally formed as a flat piece of rectangular stock having measurements of a thickness  708 , width  707  and length  701 , which in a specific embodiment are respectively about 0.5 inches, 1.5 inches and 36 inches. This single piece is treated with heat or other appropriate methods to cause the flat stock to be twisted with respect to the two ends of the length  701 . The number of twists shown in FIG. 7 is three over a length of about 36 inches, however the number of twists may be from 1 to 5 or more depending on the liquid flow properties and required structural strength required for maintaining the electrode  700  in a appropriate axial space position in the conduit, as well as providing a desired liquid turbulence as shown the liquid path  706  in FIG.  7 . 
     The twisted single piece is then dipped in a conductive metal, such as copper, which will appropriately plate on the outer surface of the twisted single piece. This conductive metal becomes the positive electrode material as shown in FIG. 8 as conductive layer  710 . The composite twisted single piece  709  plated with an appropriate thickness of a conductive layer  710  is then dipped or otherwise coated with a relatively high dielectric material such as Kynar® or Kevlar® or less preferably Teflon®. One end of the length  701  is electrically connected with liquid tight seal about its contacting circumference to connector  702 , which is connected to threaded piece connector  703 . The assembly of these separate pieces comprise the electrode  700  which is insertable into a relatively small orifice of a conduit or vessel for creation of an electrostatic field. Length  701  may also extend from less than 24 inches to 48 inches or more, although above 48 inches structural support may need to be enhanced with some electrically neutral support means. Thickness  708  and width  707  are primarily dependent on the requirements for structural strength as well as the required difference in height between ridge  704  and valley  705  to generate a desired turbulence in the flowing liquid. 
     With reference to FIGS. 9 and 10, alternate embodiments of the present invention are now described. Electrode  800  comprises a threaded connection consisting of a base piece  801  and threaded section  805 , the two being integrally joined such that section  805  is threadably and sealingly connectable to a threaded pipe opening, that opening arranged to provide an electrode location in the pipe as shown substantially as in FIG.  1 . Electrode  800  is base supportable so that piece  801  abuts an exterior face of a pipe opening for sealing against liquid leaks. 
     Electrode  800  is shown having a base electrode section  802  and end section  803 , with a broken away portion to indicate that the overall electrode length  822  is preferably provided for current commercial designs of 24, 29 and 39 inches corresponding to sections  802  and  803  combined lengths of 18, 24 and 36 inches. It is understood that distance  107  of FIG. 1 comprises a generally effective distance from the surfaces of sections  802  and  803  to the inside surface of an electrically conductive portion of the enclosing pipe electrically connected with metallic section  805 , section  805  electrically connected with ground (negative) connection wire  806  that passes through bores  808 ,  809  and  811  to reach from an pipe-external connection to an inside surface connection to section  805 . It will be readily appreciated that the polarity of the embodiments of FIGS. 9 and 10 are opposite in relation to pipe and electrode as compared to the embodiments of FIGS. 1-4. 
     As seen in FIG. 10, piece  801  and section  805  provide base support for section  802  in the circular bore of section  805  communicating with the smaller diameter bore  808  of piece  801 . That circular bore of section  805  has a slightly large diameter that of the cylindrical section  802  so that the right end of section  802  may be potted in an epoxy  810 . A thin insulating layer  819  extends around and defines an outer surface of sections  802  and  803 . Layer  819  consists of thin layer of PVC, Teflon®, or other equivalent material. The skilled person is instructed with this disclosure of layer  819  that Teflon® is generally more expensive than PVC and is preferred in applications where the operational liquid temperature is above about 130° F., while PVC may be used below that temperature, as in warmed cooling water flows. 
     Dielectric layer  816  forms an interface  817  with the inside surface of layer  819 . Interface  817  may comprise a connective epoxy for securing the layers together. Layer  816  comprises dielectric material to accomplish the objects of the invention system. A preferred material for layer  816  is Red Kynar® Flex. Kynar Flex® resins are similar to Kynar® resin in purity and chemical resistance, but they have higher chemical compatibility in high pH solutions, increased impact strength, and better clarity. In thin sections of tubing, Kynar is flexible and transparent. In the prior art, such resins are routinely used for corrosion protection. In the present invention, it has been found that layer  816  is the location of an intense electric field when the invention is operated at a preferred 20,000 to 40,000 VDC. It has been found that the dielectric properties of the Kynar® resins, and especially Red Kynar® Flex, for the electrostatic induction of liquid borne particles at high voltages are superior to many other materials. Breakdown of other dielectrics in this application mean that the electric field quickly “burns” through the dielectric and liquid sealing insulation, causing the electrode to short out and be destroyed. 
     In one specific embodiment, the thickness of the layer  816  is about 2.44 mm of Red Kynar® Flex with an outside diameter of about 38.33 mm. A range of effective specifications for this material will permit thicknesses of from 0.5 mm to over 5 mm, although the range of 1.5-3 mm is more preferable. Other appropriate dielectrics may be substituted such as other halogenated hydrocarbon polymers or other materials having similar dielectric properties. 
     Layer  813  is a conductor layer comprising metal or highly conductive composites effective for providing an evenly and axially distributed electrical field about the electrode. As such, it is preferable that interface  815  between layers  816  and  813  comprise a conductive epoxy for enhancing dielectric properties of layer  816  and structural support. Layer  813  in one embodiment is a copper cylinder with a thickness of about 1.48 mm with a narrow longitudinal slot cut into it (about 0.5-5 millimeters), such that the cylinder, in construction of the electrode, is inwardly compressed to reduce its effective outside diameter and then allowed to expand so that its outside surface is tightly held against the inside surface of layer  816 . This tight fit of the conductor against the dielectric improves electrode operation and provides for non-destructive expansion and contraction of the copper tube when it is heated or cooled in contact with layer  816 . The differential thermal coefficients of expansion of the layers  813  and  816  is one of the most serious problems of the prior art for such electrodes. Dielectrics effective for the electrodes of in the field present invention have very different such coefficients, such that a rapidly heated and expanding metal conductor will cause the dielectric to fracture, followed by electrode failure. 
     In another embodiment of the present invention, layer  813  comprises a solid aluminum cylinder having an outside diameter of about 34.1 mm, thereby leaving about 1 mm space between the aluminum and the inside surface of layer  816  at room temperature. Conductive epoxy preferably fills that space, although the superior flex and toughness of the Kynar® resins permit substantial aluminum expansion without rupture of the dielectric or substantial compromise of the electrical field around the electrode. Highly polycrystalline materials improve electrostatic induction for the present invention, such that other polymers such as KEVLAR® (long molecular chains produced from poly-paraphenylene terephthalamide) are also extremely useful as dielectrics for electrode  800 . Useful for dielectrics of the present invention are other polycrystalline polymers such as polyfluorinated hydrocarbon polymers such as Kynar® (polyvinylidene fluoride) and less preferably Teflon®. Kynar is a tough engineering thermoplastic that exhibits the stable characteristics of the fluoropolymers with more creep resistance, tensile and impact strength. 
     For structural support, the ends of layer  812  abut substantially solid plugs at either end of bore  814 . As described above, at the threaded end of the electrode, the plug comprises a small passage for wiring of the electrode and positive pole connection  812 . 
     A preferred power supply for the electrode  800  permits modulation of the potential from 20,000 to 40,000 VDC depending on input from transducers upstream and/or downstream measuring particulates, pH, flow rate, temperature, ionizing and polar component concentrations, and other such inputs for processes affected by the electrode  800  treatment of flowing liquids. 
     Although it is not known presently, the Red Kynar® Flex is a far superior dielectric in resisting “burn-out” for the high voltage operation of the invention electrode. A present preferred current is around from 100-150 microamps DC. The Black Kynar® and clear Kynar® have far reduced effectiveness as compared to the Red Kynar® Flex as a dielectric in the invention electrode. 
     The above design disclosures present the skilled person with considerable and wide ranges from which to choose appropriate obvious modifications for the above examples. However, the objects of the present invention will still be obtained by the skilled person applying such design disclosures in an appropriate manner.