Patent Application
20140262759
The present disclosure relates electrolytic cells, and in particular, to an outlet from the housing containing the cell electrodes.
Electrolytic cells are used in a variety of different applications for changing one or more characteristics of a fluid. For example, electrolytic cells have been used in cleaning/sanitizing applications, medical industries and semiconductor manufacturing processes. Electrolytic cells have also been used in a variety of other applications and have had different configurations. For cleaning/sanitizing applications, electrolytic cells are used to create anolyte liquids, catholyte liquids, and/or combined anolyte and catholyte liquids, for example. Anolyte liquids containing hypochlorous acid (and other forms of free chlorine) have known sanitizing properties, and catholyte liquids have known cleaning properties. Also, electrolytic cells have been used to create liquids with charged nano-sized and micron-sized gas-phase bubbles, which are believed to improve the cleaning efficacy of the liquid by picking up dirt particles and preventing their re-deposition. The present disclosure relates to electrolytic cells used in these and other applications.
An aspect of the present disclosure relates an electrolytic cell. The cell includes a housing having a liquid inlet and a liquid outlet outlet, an anode and a cathode positioned within the housing and defining a reaction chamber therebetween, and a liquid flow path, from the liquid inlet to the liquid outlet, which passes through the reaction chamber. A transition duct is positioned at the liquid outlet and has a duct inlet, a duct outlet and a transition section along which internal side walls of the transition section converge along the liquid flow path to define a smooth transition from a first cross-sectional area to a second cross-sectional area of the transition duct. The first cross-sectional area is at least two times greater than the second cross sectional area.
In a particular aspect, the internal side walls of the transition section converge along at least one plane that is parallel to a direction of fluid flow along the liquid flow path.
In a particular aspect, the internal side walls of the transition section have a minimum radius of curvature of 5 millimeters along the at least one plane that is parallel to the direction of fluid flow.
In a particular aspect, the internal side walls of the transition section are curvilinear in the at least one plane that is parallel to the direction of fluid flow.
In a particular aspect, the internal side walls of the transition section are rectilinear in the at least one plane that is parallel to the direction of fluid flow.
In a particular aspect, the ratio of the first cross-sectional area to the second cross-sectional area is between 5:1 and 20:1.
In a particular aspect, the transition section has a length of at least 20 millimeters and less than 100 millimeters along which the transition section transitions from the first cross-sectional area to the second cross-sectional area.
In a particular aspect, the transition section has a generally rectangular shape in at least one cross-sectional plane that is transverse to a direction of fluid flow along the liquid flow path.
In a particular aspect, the transition section has a funnel shape along at least one plane that is parallel to a direction of fluid flow along the liquid flow path.
In a particular aspect, the transition section is conical.
In a particular aspect, the transition duct has an internal channel that transitions from a generally rectangular shape at a location of the first cross-sectional area to an oval or elliptical shape at a location of the second cross-sectional area.
In a particular aspect, the liquid flow path through the transition duct has a first direction at the duct inlet and a second direction at the duct outlet, which is perpendicular to the first direction.
In a particular aspect, the transition duct is physically attached to the housing or is fabricated as a single, continuous piece of material with a portion of the housing.
Another aspect of the present disclosure relates to an electrolytic cell, which includes a housing with a liquid inlet and a liquid outlet outlet, an anode and a cathode positioned within the housing and defining a reaction chamber therebetween, and a liquid flow path, from the liquid inlet to the liquid outlet, which passes through the reaction chamber. A transition duct is positioned at the liquid outlet and has a duct inlet, a duct outlet and a funnel-shaped transition section along which internal side walls of the transition section converge in at least one plane that is parallel to a direction of fluid flow along the liquid flow path. The transition section defines a smooth transition from a first cross-sectional area to a second cross-sectional area of the transition duct, wherein a ratio of the first cross-sectional area to the second cross sectional area is in a range of 2:1 and 20:1 and the transition section has a length of at least 20 millimeters and less than 100 millimeters.
The present disclosure is directed to an electrolytic cell for generating one or more electrolytic output streams from a feed liquid using electrolysis. The cell can be used in a variety of different applications, such as cleaning or sanitizing applications, medical applications, and semiconductor manufacturing processes. The cell may be configured within a stationary system configured to dispense an electrochemically-activated liquid to an application site, to fill portable containers or mobile cleaning/sanitizing units (e.g., such as mobile floor cleaners sold by Tennant Company of Golden Valley, Minn.), or may be configured as an onboard electrolytic cell within in a mobile cleaning unit, for example.
During the electrochemical process, undesirable deposits known as “scale” may form within the electrolytic cell. For example, scale may precipitate on one or more of the cell electrodes. Since precipitates such as calcium carbonate are electrically insulating, the scale deposits increase the electrical resistance across the cell, thereby lowering efficiency of electrolysis. In addition, scale deposits can increase the flow resistance through the cell and through the outlet(s) from the cell. As a result, the electrochemical process can become less efficient. A number of methods and devices have been developed to deal with these problems. For example, control circuits have been designed for periodically reversing the voltage potential applied across the cell electrodes to repel and discharge scale deposits on the electrode surfaces. Further, the electrode and housing materials have been modified to help reduce scale build-up within the cell.
In an exemplary embodiment of the present disclosure, the cell housing is modified to reduce the tendency of scale from precipitating on the interior surfaces of the housing containing the cell electrodes, and more specifically at or along the outlet port(s) of the cell, for example.
It is believed that scale may precipitate on the surfaces of the housing when the velocity of the liquid flowing through the housing or outlet is slow, such as when caused by turbulent flow due to sharp transitions in the cross-sectional area of the flow path. Also, once scale begins to deposit onto the interior surfaces of the housing, this further increases the turbulence and enables even more scale to deposit onto the housing surfaces. Scale deposits may clog the flow path, particularly at flow restrictions such as at outlet ports where the cross-sectional area of the flow path is constricted. Often, electrolytic cells have small inlet and outlet ports that connect to conduit for feeding liquid to and from the cell. An aspect of the present disclosure is directed to maintaining laminar flow through the transition between the reaction chambers containing the cell electrodes and the outlet port(s) of the cell. This is accomplished, for example, by maintaining a smooth transition between the relatively large cross-sectional area of an outlet from the cell reaction chambers and a relatively small cross-sectional area of the conduit connected to the outlet port(s) of the cell.
Electrolytic cell 10 further includes a transition duct 34 that reduces turbulence in the flow of liquid through a transition between the reaction chambers and the outlet port(s) of the cell. Transition duct 34 maintains a smooth transition between a relatively large cross-sectional area 36 of an inlet-end of the transition duct, at the outlet from the cell reaction chambers, and a relatively small cross-sectional area 38 at an outlet-end of the transition duct, where outlet 32 connects to a conduit (not shown) for feeding the electrochemically-enhanced liquid to an application site, a storage container or dispenser, for example. In embodiments having separate outlets from the cathode chamber(s) 14 and the anode chamber(s) 16, a transition duct may be positioned at the outlet of each chamber. Transition duct 34 can have any suitable cross-sectional shape in a direction transverse to fluid flow, such as a rectangular, a circular or an oval shape. Transition duct can also have any suitable orientation relative to housing 12 or the orientation of electrodes 20 and 22. In the example shown in
Electrolytic cell 10 can have any number of cathodes and anodes and can have any suitable shape, construction or arrangement. For example, the electrodes can be flat plates, coaxial plates, rods, or combinations thereof. The electrodes can be made from any suitable material, for example stainless steel, a conductive polymer, titanium and/or platinum, or other material. One or more of the electrodes may (or may not) be coated with a material, such as platinum, iridium and/or ruthenium oxide. In one embodiment, each electrode plate comprises platinum-coated titanium. The particular electrode material may be selected as a function of the desired chemical species generated during the electrolysis process. Each electrode can have, for example, a solid construction or can have one or more apertures, such as a mesh. Multiple cells 10 and/or electrodes can be coupled in series or in parallel with one another, for example.
In a particular example, electrolytic cell 10 has five parallel plate electrodes, including three cathode electrodes interleaved with two anode electrodes (or three anodes interleaved with two cathodes), each separated from one another by a suitable gap that lacks a barrier 18. Each electrode in this example is formed of a solid titanium plate that is coated with platinum.
In embodiments that include a barrier 18, the barrier may include a membrane (e.g., an ion exchange membrane) or other diaphragm or separator that separates cathode chamber 14 and anode chamber 16. In embodiments in which barrier 18 is a membrane, barrier 18 can include a cation exchange membrane (i.e., a proton exchange membrane) or an anion exchange membrane. In some embodiments, barrier 18 includes a material that does not act as a selective ion exchange membrane, but maintains general separation of the anode and cathode compartments. In particular examples, the barrier material may include a hydrophilic microporous material that conducts current between the anode and cathode electrodes and facilitates production of bubbles in the output liquid. Exemplary materials for such a barrier include polypropylene, polyester, nylon, PEEK mesh, Polytetrafluoroethylene (PTFE), polyvinylidene difluoride and thermoplastic mesh, for example.
To produce an electrochemically-enhanced liquid, the cathode and anode chambers of electrolytic cell 10 are fed with a liquid, such as water or a mixture of water and a salt solution (e.g., H2O and sodium chloride or potassium chloride), through inlet 30, and a voltage potential difference is applied between the cathode electrode(s) 20 and the anode electrode(s) 22 to induce an electrical current between the electrodes and through the liquid (across barrier 18, if present).
End plate 44 includes the inlet 30 and a tube adapter 46. Tube adapter 46 is connected to the inlet 30 (or formed integrally therewith) and is configured to connect to a conduit, such as a flexible tube, for receiving a supply of feed liquid. In this example, tube adapter 46 is a male type adapter configured to the flexible tube by a friction fit. For example, the outer diameter surface of tube adapter 46 may include one or more annular ribs or flanges 48, which assist in retaining the end of a flexible tube or other conduit (not shown) onto the end of tube adapter 46. Other types of adapters can be used to connect a conduit to the inlet 30. The inlet 30 is fluidically coupled to gaps between the cathode 20a-20c and the anode electrodes 22a-22b at an inlet end of the cell 10.
In this example, end plate 44 also includes the outlet 32 and transition duct 34. A tube adapter 52 is coupled to the output of transition duct 34. The outlet 32 is fluidically coupled to the gaps between the cathode electrodes 20a-20c and the anode electrodes 22a-22b at an outlet end of the cell 10, which is opposite to the inlet end of the cell, for example. In one example, transition duct 34 is physically connected to end plate 44 (or another component part of the housing). For example, transition duct 34 may be a component part distinct from end plate 44 and physically attached directly to end plate 44 or may be fabricated with end plate 44 (or another part of the cell housing) as a single, continuous piece of material. In the example shown in
Each electrode plate 20, 22 further includes an electrically-conductive terminal 76 extending from a perimeter of the frame 60 and electrically connected to the respective electrode 62. A control circuit (not shown) can then be connected to the various terminals 72 through electrical leads for applying a voltage potential between the electrodes 62.
At the outlet end of cell 10, end plate 44 includes a generally rounded rectangular (or oval, for 4 example) outlet aperture 82, which defines the outlet 30 provides a channel through which fluid can pass from the outlet apertures 66 in plates 20, 22 to the transition duct 34. The edges of aperture 82 are defined by the edges of a recess 86 formed in end plate 44 and an edge of insert 84. Insert 84 has a peripheral shape and thickness that matches the peripheral shape and thickness of recess 86, except at an opening that defines outlet aperture 82. Insert 84 and recess 86 are provided for manufacturing purposes. In one exemplary embodiment in which transition duct is molded or otherwise fabricated as a single continuous piece of material with end plate 44, recess 86 permits access to the interior of transition duct 34, so that the interior of the duct can be formed by a mold. After fabrication, insert 84 can then be glued or otherwise adhered within the recess 86 to close-off the opening formed by the recess (except for the desired outlet aperture 82). In an exemplary embodiment in which transition duct 34 is fabricated as a separate, distinct piece of material from end plate 44, the transition duct can be molded or otherwise fabricated without having to create recess 86 in end plate 44. In this embodiment, end plate 44 is simply fabricated with a rounded rectangular outlet aperture 82 (or an aperture with any other desired cross-sectional shape.
In a particular, non-limiting example, inlet 30 has a diameter 91 of 5.6 millimeters and has a cross-sectional area of about 24.6 square-millimeters; and outlet aperture 82 has a length 93 of 53.46 millimeters, a width 95 of 16 millimeters and a cross-sectional area of 848.4 square-millimeters, taking into account the radiused corners of the rounded-rectangular shape. So in this example, the area of outlet 32 is much greater than that of inlet 30.
The interior surface of transition duct 34 is visible through outlet aperture 82 in
The gradual change in cross-sectional area in this example can be seen clearly in
In the present example, the ratio of inlet width 100 to outlet diameter 102 of transition duct 34 is 4.3:1 (i.e., 53.46 mm/13.2 mm to 1). The transition between inlet width 100 to outlet diameter 102 is defined by gradually converging, curvilinear sidewalls 104 along the liquid flow path in the direction of fluid flow. Side walls 104 may be rectilinear in another embodiment. The transition section along which the side walls converge may extend from the inlet end of the duct 34 (duct inlet) to the outlet end of the duct (duct outlet) or may extend only along a transition section positioned between the duct inlet and the duct outlet, where the cross-sectional area of duct 34 transitions from the first cross-sectional area to the second cross-sectional area. In one exemplary embodiment, the transition section has a length of at least 20 millimeters and less than 100 millimeters. The transition section can have other lengths in other embodiments.
In the example shown in
Duct 34 has a generally rectangular cross-sectional shape (but with smooth, rounded internal corners) along at least one cross-sectional plane that is transverse to fluid flow and along least one cross-sectional plane that is perpendicular to the electrode plates, along a longitudinal axis of the cell 10, for example. In another embodiment, the two opposing internal side walls of duct 34 may also converge smoothly along the plane perpendicular to the electrode plates, along the longitudinal axis of the cell 10. The term “generally rectangular” means a rectangular shape that has flat side edges but may have sharp or curved corners between the side edges. As can be seen in
As shown in the side elevation view of
In another embodiment, transition duct 34 does not impart a flow direction change, but maintains a common flow direction from the inlet of the duct to the outlet of the duct. Also, the transition duct can have a variety of different cross-sectional shapes in different embodiments. For example, the duct may maintain a circular or oval cross-section along a plane transverse to the direction of fluid flow, more like a traditional funnel with a wide, conical mouth at the inlet, which transitions smoothly to a narrower stem at the outlet. The duct could extend perpendicularly from the end plate 40 of cell 10, for example. In another example, cell 10 has cylindrical shape with coaxial electrodes. In this example, the transition duct may be coaxial with the electrodes and extend from an end of the cell along a longitudinal axis of the cell, or may extend from a side wall of the cell similar to the embodiments of
Although the present disclosure has been described with reference to one or more embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure and/or the issued claims appended hereto. Also while certain embodiments and/or examples have been discussed herein, the scope of the invention is not limited to such embodiments and/or examples. One skilled in the art may implement variations of these embodiments and/or examples that will be covered by one or more issued claims appended hereto.
