Abstract:
The present invention is directed to an electrolytic cell that is completely sealed during the electrolysis operation during production of oxidant. Gasses generated within the electrolysis operation, primarily hydrogen that is liberated at the cathode surface, increase the pressure within the cell, and the gas pressure is ultimately utilized to expel the oxidant from the cell chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 09/907,092, entitled “Portable Water Disinfection System,” filed on Jul. 16, 2001, and the specification and claims thereof are incorporated herein by reference. This application is also related to U.S. patent application and PCT Application entitled “Electrolytic Cell for Surface and Point of Use Disinfection”, Attorney Docket 30750-1001, filed on even date herewith, the specification and claims thereof which are also incorporated herein by reference. This application also claims priority to U.S. Patent Application Ser. No. 60/448,994 entitled “Electrolytic Cell for Surface and Point of Use Disinfection”, filed Feb. 21, 2003, the specification thereof which is also incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to an electrolytic cell producing oxidants that operates in batch mode and utilizes gas pressure generated within the cell to transfer the contents from the electrolytic cell.  
         BACKGROUND OF THE INVENTION  
         [0003]    Electrolytic technology utilizing dimensionally stable anodes (DSA) has been used for years for the production of chlorine and other mixed-oxidant solutions. Dimensionally stable anodes are described in U.S. Pat. No. 3,234,110 to Beer, entitled “Electrode and Method of Making Same,” whereby a noble metal coating is applied over a titanium substrate.  
           [0004]    An example of an electrolytic cell with membranes is described in U.S. Pat. RE 32,077 to deNora, et al., entitled “Electrode Cell with Membrane and Method for Making Same,” whereby a circular dimensionally stable anode is utilized with a membrane wrapped around the anode, and a cathode concentrically located around the anode/membrane assembly.  
           [0005]    An electrolytic cell with dimensionally stable anodes without membranes is described in U.S. Pat. No. 4,761,208 to Gram, et al., entitled “Electrolytic Method and Cell for Sterilizing Water.” 
           [0006]    Commercial electrolytic cells have been used routinely for oxidant production that utilizes a flow-through configuration that may or may not be under pressure that is adequate to create flow through the electrolytic device. Examples of cells of this configuration are described in U.S. Pat. No. 6,309,523 to Prasnikar, et al., entitled “Electrode and Electrolytic Cell Containing Same,” and U.S. Pat. No. 5,385,711 to Baker, et al., entitled “Electrolytic Cell for Generating Sterilization Solutions Having Increased Ozone Content,” and many other membrane-type cells.  
           [0007]    In other configurations, the oxidant is produced in an open-type cell or drawn into the cell with a syringe or pump-type device, such as described in U.S. Pat. No. 6,524,475 to Herrington, et al., entitled “Portable Water Disinfection System.” 
           [0008]    U.S. patent application Ser. No. 09/907,092 to Herrington, et al., entitled “Portable Water Disinfection System,” the specification of which is incorporated herein by reference, describes disinfection devices that utilize, in one instance, a cell chamber whereby hydrogen gas is generated during electrolysis of an electrolyte, and provides the driving force to expel oxidant from the cell chamber through restrictive check valve type devices. In this configuration, unconverted electrolyte is also expelled from the body of the cell as hydrogen gas is generated. In an alternate configuration in the same application, hydrogen gas pressure is contained in a cell chamber during electrolysis, but the pressure within the cell chamber is limited by the action of a spring loaded piston that continues to increase the volume of the cell chamber as gas volume increases. Ultimately, a valve mechanism opens, and the spring-loaded piston fills the complete volume of the cell chamber forcing the oxidant out of the cell chamber.  
           [0009]    In the current embodiment of the present invention, the cell chamber incorporates an inactive gas chamber at the top of the cell that allows the accumulation of gas (e.g. hydrogen gas). The gas pressure is generated, and this pressure is ultimately utilized as the sole driving force to expel the oxidant from the bottom of the cell through a valve mechanism. Utilizing this mechanism, complete electrolytic conversion of the electrolyte in the cell chamber is achieved allowing optimal operational efficiency.  
           [0010]    Other inventions that utilize gas pressure generated from electrolysis are also described in the literature. U.S. Pat. No. 4,138,210, to Avedissian, entitled “Controlling the Pressure of a Gas Generator,” describes a gas torch that utilizes an electrolytic mechanism for generating and controlling pressure of hydrogen gas that is used as the feed gas for the torch. U.S. Pat. No. 5,221,451 to Seneff, et al., entitled “Automatic Chlorinating Apparatus,” describes a chlorine gas generating cell that operates at the same pressure as the treated water flow stream. Water under pressure flows through the closed cell and replenishes the electrolyte level in the cell. Partitions within the electrolytic cell maintain separation of the chlorine gas that is aspirated in the water stream. Chlorine and hydrogen gas generated within the cell maintain a pressure balance between the chlorine gas phase and the pressure of the liquid water flowing through the cell so that unconverted electrolyte is not drawn into the flowing water stream. U.S. Pat. No. 5,354,264 to Bae, et al., entitled “Gas Pressure Driven Infusion System by Hydrogel Electrolysis,” describes a system that generates and controls the production of oxygen and hydrogen gas in an electrolytic hydrogel process for the purpose of closely regulating the amount of liquid drugs that are delivered under gas pressure to the human body.  
         BRIEF SUMMARY OF THE INVENTION  
         [0011]    The preferred embodiment of the present invention is an apparatus to produce a disinfecting solution to treat a fluid. The apparatus comprises at least one cell. The cell comprises at least two electrodes wherein at least one electrode comprises at least one cathode and at least one electrode comprises at least one anode. The apparatus comprises a control circuit for providing an electrical potential between at least one cathode and at least one anode, wherein the control circuit is in electrical contact with at least one cathode and at least one anode.  
           [0012]    During generation of oxidants, electrolyte is located within the cell housing between the anode and cathode, and a controlled electrical charge passes through the electrolytic solution from at least one cathode and at least one anode, thereby generating at least one oxidant in the electrolyte. An energy source in electrical contact with the control circuit delivers a controlled electrical charge having a predetermined charge value.  
           [0013]    A headspace in the electrolytic cell accumulates generated gas under pressure for the purpose of utilizing the generated gas pressure to expel the contents of the cell on completion of electrolysis.  
           [0014]    Prior to electrolysis, electrolyte is introduced into the cell via an inlet port. The inlet port comprises an inlet port mechanism such as a valve to seal the inlet port after the electrolyte has entered the cell. The cell further comprises an outlet port and outlet port mechanism such as a valve to seal the outlet port during electrolysis. After electrolysis, the outlet port mechanism opens and allows discharge of electrolyzed oxidant through the outlet port.  
           [0015]    In the preferred embodiment, the apparatus comprises a positive displacement pump for transfer of the electrolyte to an interior of the cell. In an alternative embodiment, the inlet port mechanism comprises a control valve to allow transfer of electrolyte to the interior of the cell. In another embodiment of the present invention, the inlet port mechanism comprises a dual control valve to allow transfer of electrolyte to the interior of the cell while simultaneously allowing gas to vent out of the cell. Prior to electrolysis during the fill operation, gas venting, depending on system design, may be required in order to allow electrolyte to flow to the interior of the cell without restriction from gas pressure buildup in the confined space within the cell.  
           [0016]    In another embodiment of the present invention, the inlet port mechanism comprises a check valve to allow transfer of electrolyte to the interior of the cell. During electrolysis the check valve restricts flow of gas and fluids out of the cell.  
           [0017]    The apparatus of the present invention comprises an electrolyte storage container. The electrolyte storage container may be a permanent part of the apparatus, or it may be a replaceable electrolyte storage container. To allow free flow of electrolyte solution from the electrolyte storage container, the container comprises a vent valve to release negative pressure from within the electrolyte storage container to allow free flow of electrolyte from the container. In the preferred embodiment, the electrolyte storage container comprises a quick disconnect valve on the container discharge port to allow removal of the container from the system without loss of electrolyte from the container. In an alternative embodiment, the electrolyte storage container is collapsible.  
           [0018]    In an alternative embodiment of the present invention, the apparatus comprises a microprocessor circuit that identifies the electrolyte storage container with system. The remaining contents of the electrolyte storage container can be determined by virtue of the microprocessor by keeping track of the number of operations of the apparatus, and knowing the volume of electrolyte used during each operational cycle.  
           [0019]    The apparatus further comprises a fluid storage container for storage of a fluid to be treated by the oxidant solution. In the preferred embodiment, the fluid storage container comprises an oxidant measuring device. In the preferred embodiment, the oxidant measuring device is a chlorine measuring device. In an alternative embodiment of the present invention, the chlorine measuring device is a solid-state semiconductor commonly referred to as a “sensor-on-a-chip”. In a further embodiment of the present invention, the oxidant measuring device comprises an oxidation reduction potential (ORP) measuring device. To ensure accuracy of the ORP measuring device, the oxidant sensor may also comprise a device for measuring temperature and pH and adjusting the ORP value for variations in temperature and pH.  
           [0020]    In an alternative embodiment of the present invention, the apparatus comprises an oxidant storage container in lieu of a fluid storage container. Alternately, the apparatus comprises a port for injection of oxidants directly into a selected source to be treated. The source to be treated my be a closed fluid body such as a water tank, open fluid body such as a swimming pool, a pipe with fluid flowing therein, a sump such as in a cooling tower, a basin, trough, and/or a plenum for spraying oxidant into a gas stream such as an air duct or other gas stream for oxidizing constituents in the gas stream.  
           [0021]    The apparatus of the present invention further preferably comprises a microprocessor control system. The control system measures and controls power to the anode and cathode, controls activation of the inlet port feed mechanism, the outlet port mechanism, and the oxidant measuring device. Further, the apparatus comprises an electrolyte storage container microprocessor for identifying the electrolyte storage container with the system. The electrolyte storage container microprocessor maintains a record of a number of electrolytic cycles associated with the electrolyte storage container for the purpose of determining the remaining volume and remaining number of cycles available in the electrolyte storage container. By this means, the electrolyte storage container can be removed from the system and replaced by an alternate electrolyte storage container. Data recorded in the microprocessor allows the control system of the apparatus to keep track of the remaining electrolyte in each unique electrolyte storage container.  
           [0022]    Broadly, it is a primary object of the present invention to provide a batch mode electrolytic cell that utilizes a gas chamber space above the electrodes within a confined cell. During electrolysis, gases, primarily hydrogen gas, are utilized to expel the generated oxidant from the electrolytic cell via a cell discharge valve to a fluid to be treated, or an oxidant storage container.  
           [0023]    A primary advantage of the present invention is that a simple gas chamber space above the electrodes within an electrolytic cell is utilized to provide the driving force to expel oxidant from the electrolytic cell to a fluid to be treated. This configuration allows complete electrolysis of the electrolyte for efficient operation, and does not rely on a flow-through cell or separate pumping devices to transfer the oxidant to the fluid to be treated. Gas pressure generated in the electrolysis process is utilized to provide the force to transfer oxidant from the cell. This configuration allows for very low cost manufacturing for applications in consumer devices, or other low fluid volume systems.  
           [0024]    Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0025]    The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings:  
         [0026]    [0026]FIG. 1 is a view of an electrolytic cell with a gas chamber space above the electrodes;  
         [0027]    [0027]FIG. 2 is a system configuration utilizing a pump to transfer electrolyte to an electrolytic cell with a gas chamber;  
         [0028]    [0028]FIG. 3 is a system configuration utilizing gravity to transfer electrolyte to an electrolytic cell with a gas chamber; and  
         [0029]    [0029]FIG. 4 is a system configuration utilizing gravity to transfer electrolyte to an electrolytic cell with a gas chamber and a dual valve mechanism to vent the cell chamber during fill. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    The present invention comprises an electrolytic cell and method for generation of oxidants that are utilized to disinfect surfaces, liquids, or airborne contaminants.  
         [0031]    Referring to FIG. 1, which shows the preferred embodiment of the invention, electrolyte solution  14 , preferably, a sodium chloride brine solution is introduced into cell housing  12  which comprises positive anode  17  and negative cathode  18  wherein electrolyte solution  14  is electrolytically converted to an oxidant solution within the confined space of electrolytic cell  10 . Any electrolyte solution for generating an oxidant is useful in accordance with the present invention.  
         [0032]    During electrolysis, hydrogen gas is liberated at cathode  18  and accumulates in headspace  13 . As hydrogen gas accumulates in headspace  13 , gas pressure increases according to the well known gas equation, PV=nRT wherein P is the pressure of the gas, V is the volume of the chamber, n is the moles of gas, R is the molar gas constant, and T is the absolute temperature. Gas pressure increases by virtue of the fact that inlet valve  15  and outlet valve  16  are both closed.  
         [0033]    To initiate the process, outlet valve  16  is closed and inlet valve  15  is open. Electrolyte solution  14  is introduced to cell housing  12  either by gravity feed or by utilizing a fluid transfer device such as a pump to introduce the electrolyte solution  14  to interior of the cell housing  12 .  
         [0034]    After electrolyte solution  14  has been introduced into cell housing  12 , inlet valve  15  is closed, and electrical power is applied across the positive electrode, anode  17 , and negative electrode, cathode  18 . Anode  17  and cathode  18  are sealed within cell housing  12 .  
         [0035]    During electrolysis, hydrogen gas is generated at the surface of cathode  18 . The hydrogen gas bubbles rise and accumulate in headspace  13 . As electrolysis continues, gas pressure within headspace  13  rises creating a pressure within cell housing  12 . With proper design, approximately all of the sodium chloride within electrolyte solution  14  is efficiently converted to oxidant.  
         [0036]    The volume of headspace  13  determines the pressure that is built up within cell housing  12 . The appropriate pressure desired is a function of the system design and the required pressure needed to discharge the oxidant contents within cell housing  12  to the oxidant storage device, or preferably, the fluid to be treated. The fluid to be treated may be at zero pressure, or any other pressure such as the pressure in a normal water supply system.  
         [0037]    Oxidant produced from the electrolysis of electrolyte solution  14  is discharged from cell housing  12  by opening outlet valve  16 . Most of the hydrogen gas generated in the electrolysis process is also discharged from cell housing  12  through outlet valve  16 . Efficient production of oxidant can be generated in a series of batch process sequences previously described, and can utilize the gas pressure generated in the electrolysis process to provide the force necessary to introduce the oxidant to the fluid to be treated, without the need for auxiliary pumps or transfer devices.  
         [0038]    The preferred embodiment of the system of the present invention is shown in FIG. 2. In the preferred embodiment, electrolytic cell  10  receives electrolyte solution  14  from an electrolyte storage container  38 . Electrolysis occurs within cell  10  and the resulting oxidant solution is then transferred to fluid  46  to be treated within fluid storage device  44  which may or may not be under pressure.  
         [0039]    In the preferred embodiment, electrolyte storage container  38  is removable for subsequent replacement by new electrolyte storage container  38 . Electrolyte storage container  38  comprises vent valve  42  that allows the introduction of air into electrolyte storage container  38  as electrolyte solution  40  is drawn out of container  38  thereby avoiding negative pressure in container  38 . Electrolyte storage container  38  can be quickly removed from the system by means of quick disconnect self-sealing valve  36 .  
         [0040]    In an alternative embodiment of the present invention, container  38  comprises a microchip device that identifies container  38  with the total system, and provides for electronic monitoring of the volume of the contents of container  38  based on the number of cycles of the system.  
         [0041]    In another embodiment of the present invention, electrolyte storage container  38  can be replaced with a brine generating device. A brine generating device is filled with salt, preferably a halogen salt, and water mixes with the halogen salt to produce a liquid brine solution. The liquid brine solution performs as electrolyte  40 .  
         [0042]    In the preferred embodiment, electrolyte  40  is transferred to electrolytic cell  10  by a positive displacement pump such as diaphragm type pump  30  with inlet valve  32  and outlet valve  34  integral with the pump head. As previously described, electrolysis of the electrolyte solution occurs within cell  10  thereby converting electrolyte solution  14  to disinfecting oxidants. With proper sizing of cell  10 , the concentration of electrolyte  14 , and the amount and duration of electrical power applied to electrolyte  14  within cell  10 , very efficient conversion of electrolyte  14  is facilitated.  
         [0043]    Concurrent with production of oxidants, gas is generated within headspace  13  thereby developing pressure. Upon completion of electrolysis, discharge valve  16  is opened allowing the discharge of oxidant to fluid storage container  44 .  
         [0044]    In the preferred embodiment, outlet valve  16  is preferably a solenoid valve. The fluid to be treated is held in container  48 . This may be a water storage tank. Alternate embodiments include a container that holds a fluid to be treated that can be used to disinfect surfaces, for instance, a spray bottle.  
         [0045]    In the preferred embodiment, the system is controlled by microprocessor  50 . In the preferred embodiment, the system is a batch process that maintains a residual oxidant value, preferable a chlorine residual value, in fluid storage container  44 . Fluid storage container  44  comprises an oxidant residual monitoring device, preferably chlorine sensor  48 .  
         [0046]    In an alternative embodiment, the oxidant residual monitoring device comprises an oxidation reduction potential (ORP) sensor or chlorine sensor mounted on an integrated circuit device (aka chlorine sensor-on-a-chip).  
         [0047]    In the preferred embodiment, the fluid level in fluid storage container  44  is not important to maintaining the desired oxidant residual value. Chlorine sensor  48  monitors the chlorine residual value via microprocessor  50 . If the chlorine residual value is below the desired value, microprocessor  50  instructs the system to produce another batch of oxidant in cell  10 . In this mode of operation, neither the oxidant demand of the fluid to be treated, nor the volume of fluid in the fluid storage container  44  are important to maintaining the desired chlorine residual value. If the chlorine residual value is not sufficient, microprocessor  50  continues making oxidant in batches until the desired chlorine residual is maintained.  
         [0048]    In an alternative embodiment shown in FIG. 3, the electrolyte is transferred by gravity via inlet solenoid valve  60  instead of fluid transfer pump  30  shown in FIG. 2. The operational scenario with inlet solenoid valve  60  works well if fluid transfer line sizes are adequately sized to avoid flow resistance due to electrolyte fluid viscous effects or hydraulic locking that avoids transfer of vent gasses in the fluid transfer lines.  
         [0049]    In an alternative embodiment of the present invention, inlet solenoid valve  60  is replaced with a simple check valve. With proper timing via microprocessor  50 , the batch process is terminated by removing power from anode  17  and cathode  18  and opening outlet solenoid valve  16 . As the contents of cell  10  are discharged, outlet solenoid valve  16  can remain open long enough for electrolyte  40  to flow into cell  10 , and then outlet solenoid valve  16  is closed. Electrolyte flows through the inlet check valve and the check valve will close after electrolyte  40  has entered cell  10 . The inlet check valve prevents the flow of gas from moving backwards up to electrolyte storage container  38 .  
         [0050]    In an alternative embodiment shown in FIG. 4, the electrolyte is transferred by gravity via dual inlet valve  70  and  72  which also incorporates a vent line to relieve pressure within electrolytic cell  10  allowing free flow of electrolyte  40  into cell  10 .  
         [0051]    Applications of the present invention are especially applicable to low-cost water treatment systems for the home-use and consumer market. However, it will be obvious to those versed in the art that this invention can be utilized in a variety of applications including spray bottle applications for surface cleaning, potable water treatment systems, wastewater treatment systems, swimming pool treatment systems, cooling tower treatment systems, and other applications where a disinfectant is utilized to treat a fluid.  
         [0052]    Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.