EP2872677B1

EP2872677B1 - Electrolytic cell with catholyte recycle

Info

Publication number: EP2872677B1
Application number: EP13816164.1A
Authority: EP
Inventors: Scott R. Limback; Barry R. TAYLOR; Kevin A. WUEBBEN; Marvin C. Trulsen; Lylien TAN
Original assignee: Ecolab USA Inc
Current assignee: Ecolab USA Inc
Priority date: 2012-07-11
Filing date: 2013-07-10
Publication date: 2019-01-09
Anticipated expiration: 2033-07-10
Also published as: EP2872677A4; US20150053569A1; US20140014528A1; WO2014011736A1; EP2872677A1

Description

FIELD OF THE INVENTION

The invention relates to an electrolytic cell, method and system with a catholyte recycle feature. In particular, the invention relates to an electrolytic cell configured to recycle catholyte by gravity feed for increasing chlorine capture and concentration from the in situ generation of electrolysis solutions.

BACKGROUND OF THE INVENTION

The production of acidic electrolyzed water and alkaline electrolyzed water by the electrolysis of water in which chlorine electrolyte has been added is well-known. Commercially available three-chamber electrolytic cells are one exemplary means for electrolyzing sodium chloride solutions. In a conventional mode of operation, these cells have two output solutions that are simultaneously provided, namely an acidic solution containing hypochlorous acid and hydrochloric acid in a relatively dilute form (anolyte), and an alkaline solution containing sodium hydroxide (catholyte). The hypochlorous acid in the acidic solution is a form of free chlorine and a very effective germicide. However, in the acidic solution, hypochlorous acid is relatively unstable; it is in equilibrium with the molecular chlorine in the solution, which over time will come out of the solution. Some of the chlorine in the solution escapes into the vapor head space above a contained body of the solution. There is also a chlorine odor associated with the solution, as well as the possibility of chlorine concentrations developing in the vapor space above the body of chlorine solution that exceed allowable NIOSH limits. As the need arises to generate a solution with greater germicidal efficacy (e.g., to create a solution that can be registered with the EPA as a sanitizer or disinfectant), the concentrations of chlorine in the vapor space above the solution become more problematic.
In addition, the chlorine in hypochlorous acid is a very aggressive oxidizing agent. Surfactants that might be added to the solution to enhance wetting properties are readily attacked by the chlorine in the hypochlorous acid. The same is true for surface materials with which the solution might come into contact during its application. Both of these problems become more significant as the strength of the solution is increased to enhance efficacy. All of these problems arc mitigated by adding a base, such as a sodium hydroxide, to the acidic solution to raise its pH and to create an alkaline solution in which the chlorine in the hypochlorous acid has been converted to its ionic form, the hypochlorite ion.
US 5,985,110 A discloses an electrolytic cell comprising an anode chamber and a cathode chamber with inlets and outlets, an electrolyte feed adapted for providing a source of anions and cations to the anode and cathode chambers, the outlet of the cathode chamber connected in fluid communication with the inlet of the anode chamber, and the inlet of the cathode chamber connected in fluid communication with a liquid source. The electrolytic cell further comprises a degassing chamber having an inlet and outlet, the inlet connected in fluid communication with the cathode chamber the outlet connected in fluid communication with the anode chamber.
In traditional cells, sodium hydroxide is produced during the operation of the cell. Therefore, a use in this art has been identified which includes using the alkaline solution in a self-contained process to neutralize the acidic solution produced by the cell and generate an alkaline sodium hypochlorite solution. This can be accomplished by simply mixing the acidic and alkaline solutions together in a post-cell operation. However, this approach has disadvantages. For instance, the free chlorine concentration in the acidic solution is diluted by simply mixing the two streams together. In addition, combining the two streams in a post-cell mixing operation does not allow for possible increases in chlorine capture efficiency.
Accordingly, it is an objective of the claimed invention to develop an improved electrolytic cell, method and system for generating in situ electrolysis solutions such as chlorine bleach solutions from salt and water.
A particular object for the invention is an improved electrolytic cell that provides for increased chlorine capture efficiency and concentrations by recycling catholyte through the anode chamber of the electrolytic cell.
A further object of the invention is to accomplish catholyte recycling by gravity feed.
These and other objects of the invention will be readily ascertained by one skilled in the art based on the description of the invention.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, the invention is an electrolytic cell configured to increase chlorine capture and concentration in the cell's output solution. The electrolytic cell includes an anode chamber and a cathode chamber with inlets and outlets, and an electrolyte feed that provides a source of anions and cations to the anode and cathode chambers. The outlet of the cathode chamber is connected in fluid communication with the inlet of the anode chamber and the inlet of the cathode chamber is connected in fluid communication with a liquid source. The cell includes a degassing chamber having an inlet and outlet. The inlet of the gassing chamber is connected in fluid communication with the cathode chamber and the outlet of the degassing chamber is connected in fluid communication with the anode chamber to accomplish recycling of the catholyte through the anode chamber. The inlet of the degassing chamber is also elevated above the outlet of the anode chamber to move catholyte through the anode chamber by gravity.
In another embodiment, the invention is a method for chlorine capture in an electrolytic cell. An electrolytic cell having an anode chamber and a cathode chamber with inlets and outlets is provided. An electrolyte is fed to the cell for providing a source of anions and cations to the anode and cathode chambers. Catholyte is recycled from the cathode chamber through the anode chamber and an output solution is dispensed from the anode chamber. The method also includes communicating catholyte from the cathode chamber through a degassing chamber before recycling through the anode chamber, and gravity feeding catholyte from the degassing chamber through the anode chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is an exemplary illustration of a system of the present invention using an electrolytic cell.
Figure 2 is another exemplary illustration of a system of the present invention using the electrolytic cell shown in Figure 1.
Figure 3 is an exemplary schematic illustrating one embodiment of an electrolytic cell of the present invention.
Figure 4 is an exemplary schematic illustrating another embodiment of an electrolytic cell of the present invention.
Figure 5 is a plot illustrating the change in pH of the output solution versus the input current for both 100% catholyte recycle and no recycle tests.
Figure 6 is a plot illustrating the increase in chlorine capture rate versus the change in input current for both 100% catholyte recycle and no recycle tests.
Figure 7 is a plot illustrating the change in chlorine capture versus the input current for both 100% catholyte recycle and no recycle tests.
Figure 8 is a plot illustrating the current efficiency versus the input current for both 100% catholyte recycle and no recycle tests.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to an improved electrolytic cell, its method, and a system disclosing the same. Various embodiments of the present invention will be described in detail with reference to the drawings, wherein like reference numerals represent like parts throughout the several views. Reference to various embodiments does not limit the scope of the invention. Figures represented herein are not limitations of the various embodiments according to the inventions and are presented for exemplary illustration of the invention only.
Figure 1 illustrates an exemplary system 10 of the present invention for accomplishing in situ generation of electrolysis solutions using an electrolytic cell, such as an electrolytic cell 12 with two or more chambers. The system 10 illustrated in Figure 1 is one exemplary embodiment of a system configured to increase the chlorine capture efficiency and concentration in an output solution provided by the cell 12. In the exemplary system 10 illustrated in Figure 1 is shown several components for facilitating operation of the cell 12. The cell 12 is divided by membranes into an electrolysis chamber with a positively charged electrode (anode), a middle or intermediate chamber, and an electrolysis chamber with a negative charge electrode (cathode). Further description of the electrolytic cells suitable for use according to the invention is set forth in U.S. Patent Application Serial No. 12/743,785 (Ecolab USA Inc.).
One of the inputs to the cell 12 is water from a water source. Water is communicated through a line which is selectively opened and closed by a valve 26. A pressure regulator 24 may be incorporated into the line to regulate the pressure of the water from the source pressure as is appropriate for use in the system 10. A pump 22, such as a peristaltic pump, may also be included in the line to pump water from the water source into the cathode chamber 35 through the cathode chamber inlet 36. The pump 22 allows the volume of water communicated through the inlet 36 to be controlled, such as at a preferred volumetric rate of flow. The water passes through the cathode chamber 35, producing an alkaline solution containing sodium hydroxide (catholyte). Catholyte exits the cathode chamber 35 through cathode chamber outlet 38. The catholyte is then communicated to the degassing tower 14 as new water is pumped into the cathode chamber 35 from pump 22. The catholyte enters the degassing tower 14 through the degassing tower inlet 44. The degassing tower 14 separates hydrogen gas from the catholyte liquid solution received from the cathode chamber 35 of the electrolytic cell 12. The hydrogen gas exits the degassing tower 14 through a vent 48 which allows the hydrogen gas to be released into the atmosphere at atmospheric pressure. In one design, gas (e.g., hydrogen gas) bubbles are separated from the catholyte at the point where the catholyte liquid enters the degassing tower inlet 44 with the gas being vented and the degassed fluid falling by gravity to the accumulation chamber at the bottom of the degassing tower 14. The degassing tower 14 includes an overflow 50 to allow excess catholyte solution to be drained off into a drain or into a container (e.g., a day tank) for storing the catholyte solution. The degassing tower 14 also includes a degassing tower outlet 46 connected in fluid communication with pump 16 (e.g., a peristaltic pump). The pump 16 pumps the catholyte solution from the degassing tower 14 into the anode chamber 39 of the electrolytic cell 12 via the anode chamber inlet 40. Use of the pump 16 permits the feed rate of catholyte solution into the anode chamber 39 to be controlled, (e.g., at a rate slightly less than the rate at which catholyte is discharged from the cathode chamber 35) to avoid pumping air into the anode chamber 39. The catholyte enters the anode chamber 39, creating an alkaline solution in which the chlorine and the hypochlorous acid has been converted to its ionic form, the hypochloric ion, thereby generating alkaline sodium hypochlorite solution. The output solution is communicated from the anode chamber by dispensing via anode chamber outlet 42. To facilitate the electrolytic process, electrolyte such as a brine solution is formulated in tank 18. The electrolyte is pumped from the tank 18 through outlet 58 using pump 20. The electrolyte is communicated through a line into an intermediate chamber in the electrolytic cell 12 via inlet 32. The electrolyte passes through the intermediate chamber between the cathode chamber 35 and the anode chamber 39 and exits the electrolytic cell 12 through outlet 34. The electrolyte then returns back to the tank 18 by traveling through the line and through tank inlet 52. The tank 18 is fed water from a water source. A valve 28 may be connected inline for selectively opening and closing the line to permit flow of water into the tank 18 through inlet 54. A flow control device 30 may be included in-line to control the rate of which water is introduced into the tank 18. One or more sensors, such as a level sensor 56, may be used in connection with tank 18 to monitor the volume of electrolyte within the tank.
As illustrated in Figure 1, incorporating a pump 16 between the outlet 38 of the cathode chamber 35 and the inlet 40 of the anode chamber 39 allows the rate at which catholyte from the cathode chamber 35 is introduced into the anode chamber 39 to be controlled. Figure 2 illustrates another exemplary system 10 of the present invention, such as where it is desirable to recirculate all of the catholyte (i.e., "100% recycle") produced by the cathode chamber 35 through the anode chamber 39 of the electrolytic cell 12.
In Figure 2, another exemplary system 10 of the present invention is illustrated. The system includes components and features similar to the system 10 illustrated in Figure 1. However, in Figure 2, the outlet 46 of the degassing tower 14 is connected in fluid communication with the inlet 40 of the anode chamber 39 of the electrolytic cell 12. This system 10 is different from the system shown in Figure 1 in that a pump (i.e., pump 16) is not used to communicate catholyte from the degassing tower 14 into the inlet 40 of the anode chamber 39. In lieu of the pump 16 illustrated in Figure 1, the system 10 in Figure 2 uses gravity to feed the catholyte solution from the degassing tower 14 into the inlet 40 of the anode chamber 39 of the electrolytic cell 12. Gravity feed of the catholyte from the degassing tower 14 into the anode chamber 39 of the electrolytic cell 12 is accomplished by positioning the inlet 44 to the degassing tower 14 at a position at least level with or above the outlet 42 of the anode chamber 39. The flow of output solution from the anode chamber 39 is controlled by a non-equilibrium scenario in the head pressure established between the volume of catholyte in the degassing tower 14 and the output solution in the anode chamber 39 of the electrolytic cell 12. As catholyte enters the degassing tower 14 via the inlet 44, a reservoir of catholyte solution collects within the degassing tower 14. As the level of the reservoir reaches the level of the outlet 42 of the anode chamber, the head pressure on the reservoir of liquid catholyte solution within the degassing chamber 14 forces the output solution in the anode chamber 39 out the outlet 42. Thus, as the rate of flow of catholyte into the degassing tower 14 increases, the rate at which catholyte solution flows into the anode chamber 39 also increases. In this configuration, all the catholyte solution produced by the cathode chamber 35 is recycled through the anode chamber 39 of the electrolytic cell 12. The recycling process is achieved by gravity feeding the catholyte solution from the degassing tower 14 through the anode chamber 39. This configuration also prevents air from being introduced into the anode chamber 39 of the electrolytic cell 12, since liquid head pressure is used to move the catholyte solution from the degassing tower 14 through the anode chamber 39. While the catholyte solution is in the degassing tower 14 hydrogen gas is released from the solution and exits through a vent 48 into the atmosphere at atmospheric pressure. The present invention also contemplates that a degassing membrane with an accompanying vacuum pump may be used in place of the degassing tower for degassing the catholyte liquid solution at a pressure above atmospheric pressure. In this design, the acquired hydrogen gas could be directed/diverted to another location, release or collection point. The cell 11 could also be designed to include a degassing membrane that operates at atmospheric pressure and docs not require a pump by using atmospheric pressure exerted on the degassing membrane.

EXAMPLE

Embodiments of the present invention arc further defined in the following non-limiting example. It should be understood that this example, while indicating a certain embodiment of the invention, is given by way of illustration only.
Figure 3 is a schematic illustration of an electrolytic cell 100 configured with the combined features shown in Figure 2 generally within line 3-3. The cell illustrated in Figure 3 is but one exemplary illustration of an electrolytic cell 100 that includes the combined components shown within the line 3-3 in Figure 2. According to a preferred embodiment of the invention, the electrolytic cell 100 may be disassembled (i.e., taken apart) into its component parts for troubleshooting, repairing or replacing worn or damaged components, or for cleaning. The design of the electrolytic cell 100, as discussed below, permits plumbing lines in connection to the inlets and outlets of the cell on a single side through a single manifold 102 that is a component part of the electrolytic cell 100. Similar to the electrolytic cell 12 shown in Figures 1-2, the electrolytic cell 100 illustrated in Figure 3 includes an anode chamber 104 on one side of the intermediate chamber 108 and a cathode chamber 112 on the opposite side of the intermediate chamber 108. These chambers may be fabricated from polypropylene; however, other materials such as polyvinyl chloride (PVC) or polyethylene are contemplated materials of the present invention. According to one configuration of the electrolytic cell 100, the cathode chamber 112 is generally U-shaped. The cathode chamber 112 includes an inlet 122 and an outlet 124. The inlet to the cathode chamber 112 is located on an external face of manifold 102. The inlet 122 includes a flow path through the manifold 102 into the cathode chamber 112. Similarly, the outlet 124 from the cathode chamber 112 is a flow path in fluid communication with an inlet 126 to the degassing chamber 125. The inlet 126 of the degassing chamber 125 is positioned or elevated above the location of the outlet 128 to the degassing chamber 125. The outlet 128 is connected in fluid communication through the inlet flow path 130 to the anode chamber 104. In addition to an outlet 128 being connected in fluid communication with the inlet 130 of the anode chamber 104, the degassing chamber 125 includes a drain outlet 138. In one aspect of the invention, a flow control device (e.g., a valve) may be configured in the degassing chamber 125 to selectively close and open liquid flow through the drain outlet 138. Similarly, a flow control device may be used in the flow path of the degassing chamber 125 to selectively open and close the flow path to the outlet drain 138 to drain fluid from the anode chamber 104 and the degassing chamber 125. The degassing chamber 125 also includes a vent outlet 134 in the manifold 102 providing a flow path for gasses venting from the degassing chamber 125 into the ambient environment. The anode chamber 104 is separated from the intermediate chamber 108 by an anode electrode 114 (e.g., such as a coated l'itanium material) and an anion exchange membrane 106. Similarly, a cation exchange membrane 116 and a cathode electrode 110 (e.g., such as a bare Hastelloy material) separate the intermediate chamber 108 from the cathode chamber 112. The intermediate chamber 108 may include a support member (not shown) as set forth in U.S. Patent Application Serial No. 13/185,874 (Ecolab USA, Inc.). As further illustrated in Figure 3, an outlet 132 is included in the manifold 102 that is in fluid communication via a flow path to the anode chamber 104. The intermediate chamber 108 includes an inlet 118 in the manifold 102 connected in fluid communication through a flow path with the intermediate chamber 108 and an outlet 120 in the manifold 102 also connected in fluid communication with the intermediate chamber 108. The inlet 122 to the cathode chamber 112 in the manifold 102 may include a drain outlet 136 whereby liquid in the cathode chamber 112 may be selectively drained using a flow control device (e.g., a valve) not shown. As further illustrated in Figure 3 and discussed above, the inlet 126 to the degassing chamber 125 is positioned or elevated above the level of outlet 128 in fluid communication with anode chamber 104 via inlet 130. The inlet 126 to the degassing chamber 125 is also positioned or located at an elevation above the outlet 132 to the anode chamber 104. In operation, a body of catholyte is reservoired between the level of the outlet 132 and the inlet 130 to the anode chamber 104. The head pressure of liquid reservoired in the degassing chamber 125 creates flow through the outlet 132 from the head pressure resulting from gravity acting on the liquid in the anode chamber 104. Thus, it is preferred that the inlet 126 to the degassing chamber 125 is at least at or above the level of the outlet 132 to the anode chamber 104 to facilitate movement of liquid through the anode chamber by gravity.
In operation, the electrolytic cell 100 provides a water-electrolyzing device outputting alkaline sodium hypochlorite solution, which accomplishes one or more of the objectives of the invention by providing an increase in chlorine capture efficiency and chlorine concentration in the output solution. In operation, water is introduced into the electrolytic cell 100 through an inlet 122 to the cathode chamber 112. Simultaneously and continuously during operation of the cell, an electrolyte, such as a brine solution, is introduced into the intermediate chamber 108 through inlet 118. Alkaline water (catholyte) is generated in the cathode chamber 112 by loading electric current so as to electrolyze the water in the presence of electrolyte supplied by means of electrophoresis from the intermediate chamber 108. The catholyte, which may consist of sodium hydroxide or potassium hydroxide and hydrogen gas generated in the cathode chamber 112 is discharged through outlet 124 into the degassing chamber 125 via inlet 126. During this process, the electrolyte solution in the intermediate chamber 108 is circulated to maintain the concentration of electrolytes in the intermediate chamber 108. The catholyte (e.g., sodium hydroxide) resides in the degassing chamber 125, thereby releasing hydrogen gas through the vent outlet 134. The alkaline solution (catholyte) travels through the outlet 128 of the degassing chamber 125 into the anode chamber 104 via inlet 130. The catholyte is electrolyzed in the presence of electrolytes supplied by means of electrophoresis from the intermediate chamber 108, and thereby generates an alkaline sodium hypochlorite solution. This is accomplished by converting the chlorine in the hypochlorous acid to its ionic form, the hypochlorite ion. The head pressure created by gravity acting on the reservoir of catholyte liquid in the degassing chamber 125 forces this solution from the anode chamber 104 through the outlet 132 in the manifold 102 as an output solution of the electrolytic cell 100. This process is specifically different than a traditional electrolytic cell in that the catholyte solution is recycled through the anode chamber instead of passing fresh water through the anode chamber 104. Suitable operating conditions for the electrolytic cell 100, particularly the generation of an alkaline solution (e.g., catholyte) in the cathode 112, is described or referred to in U.S. Patent Application Serial No. 11/438,454 . According to one embodiment of the invention, all of the catholyte produced by the cathode chamber 112 is recirculated through the anode chamber 104 under force of gravity acting on a reservoir of catholyte liquid in the degassing chamber 125. The electrolyte may be pumped through the intermediate chamber 108 as discussed above in the description relating to the system shown in Figure 1. One or more of the flow paths within the electrolytic cell 100 may be configured with a flow control device (e.g., a valve) to permit one or more of the flow paths to be selectively opened or closed to drain catholyte or the output solution from the cell. For example, catholyte may be drained from the degassing chamber 125 via the drain outlet 138 by opening the flow path using a flow control device (not shown). Similarly, the solution within the anode chamber 104 may be drained through the drain outlet 138. The manifold 102 may include one or more flow control devices, either electrically or manually operated, for controlling the flow through drain outlet 138 and/or drain outlet 136. In the event the catholyte in the cathode chamber 112 is drained from the cell 100, the liquid passes through the flow path connected in communication with the liquid with the drain outlet 136 in manifold 102. Alternatively, the flow control device may be configured in the plumbing external to the manifold 102 whereby one of more of the flow paths into or out of the electrolytic cell are selectively closed or opened to inhibit or permit liquid flow into or out of the electrolytic cell 100.
Figure 4 is a schematic illustration of another electrolytic cell 100. Like the electrolytic cell 100 shown in Figure 3, the electrolytic cell 100 shown in Figure 4 is another exemplary illustration of an electrolytic cell that includes the combined components shown within the lines 3-3 in Figure 2. The electrolytic cell 100 includes a chamber 108 for holding an electrolyte solution for providing cations and anions. An electrolytic solution is provided to the chamber 108 through the inlet 118 and exits from the cell 100 through the outlet 120. An anode chamber 104 and a cathode chamber 112 are contained within the chamber 108. These chambers may be fabricated from polypropylene; however, other materials such as polyvinylchloride (PVC) or polyethylene are contemplated materials of the present invention. The cathode chamber 112 includes an inlet 122 and an outlet 124. The inlet to the cathode chamber may be located on an external face of the manifold 102. The inlet 122 includes a flow path through the manifold 102 into the cathode chamber 112. Similarly, the outlet 124 from the cathode chamber 112 is a flow path in fluid communication with an inlet to the degassing chamber 125. The inlet 126 of the degassing chamber 125 is positioned or elevated above the location of the outlet 128 to the degassing chamber 125. The outlet 128 is connected in fluid communication through the inlet flow path 130 to the anode chamber 104. In addition to an outlet 128 being connected in fluid communication with the inlet 130 of the anode chamber 104, the degassing chamber includes a drain outlet 138. The degassing chamber 125 includes a vent outlet 134 that provides a flow path for gasses venting from the degassing chamber 125 into the ambient environment at atmospheric pressure. The anode chamber 104 is separated from the electrolytic solution in chamber 108 by an anode electrode 114 (e.g., such as coated titanium material) and an anion exchange membrane 106. Similarly, a cation exchange member 116 and a cathode electrode 110 (e.g., such as bare Hastelloy) separate the cathode chamber from the electrolytic solution in chamber 108. The electrolytic solution (e.g., brine) in the reservoir of chamber 108 serves as a source of anions and cations that are transferred into the anode chamber 104 and cathode chamber 112, respectively, by electrophoresis. Similar to the design shown in Figure 3, an outlet 132 in the manifold 102 is connected in fluid communication via flow path to the anode chamber 104. Chamber or reservoir 108 includes an inlet 118 in the manifold 102 connected in fluid communication through a flow path with the chamber or reservoir 108 and an outlet 120 in the manifold 102 also connected in fluid communication with the chamber or reservoir 108. The inlet 122 to the cathode chamber 112 in the manifold 102 may include a drain outlet 136 whereby liquid in the cathode chamber 112 may be selectively drained using a flow control vice (e.g., a valve) not shown. The inlet 126 to the degassing chamber 125 is positioned or elevated above the level of the outlet 128 in fluid communication with the anode chamber 124 via inlet 130. The inlet 126 to the degassing chamber 125 is also positioned or located at an elevation above the outlet 132 to the anode chamber 104. In operation, a body of catholyte is reservoired between the level of the outlet 132 and the inlet 130 to the anode chamber 104. Gas bubbles (e.g., hydrogen gas) are separated from the catholyte at the point where the catholyte liquid enters the degassing tower inlet 144 with the gas being vented and the degassed fluid falling by gravity to the accumulation chamber at the bottom of the degassing tower. The head pressure of the liquid reservoir in the degassing chamber 125 creates flow through the anode chamber 104 and outlet 132 of the anode chamber. Thus, it is preferred that the inlet 126 to the degassing chamber 125 is at least at or above the level of the outlet 132 to the anode chamber 104 to facilitate movement of liquid through the anode chamber 104 by gravity. Thus, as addressed above, the electrolytic cell may consist of as few as two chambers or more than two chambers to perform the process of electrophoresis.
Figures 5-8 illustrate plots showing data acquired by exploratory testing of an electrolytic cell 100 according to the exemplary embodiments of the invention which are shown. The electrolytic cell 100 configured to recycle catholyte into the anode chamber 104 from the cathode chamber 112 demonstrated improved efficiencies over traditional cells that do not recycle the catholyte into the anode chamber. In particular, the electrolytic cell produced an output solution having a higher pH using less electrical current than traditional cells where the catholyte is not recycled through the anode chamber 104.
Figure 6 illustrates another plot of chlorine capture versus the electrical current applied to the electrodes for achieving electrolysis. The plot illustrates evidence of the invention meeting its objectives by providing increased chlorine capture using less electrical current by recycling catholyte from the cathode chamber through the anode chamber 104, as illustrated in the embodiments identified in the invention. Note that less chlorine is captured at the expense of the same current using the traditional method of introducing water into both of the cathode chamber 112 and anode chamber 104 and producing a working solution in a post-mixing arrangement.
Figure 7 provides a plot illustrating further evidence of the increase in chlorine capture rate accomplished by recycling the catholyte from the cathode chamber 112 through the anode chamber 104.
Lastly, the plot in Figure 8 illustrates the efficiency of the electrolytic cell of this invention given the amount of electrical current required to operate the cell and produce the same results. Note that the electrolytic cell using 100% catholyte recycle more efficiently uses the same amount of current provided to the electrodes than the traditional no-recycle configuration that generates chlorine solutions by electrolysis accompanied by a post-mixing operation.

Claims

An electrolytic cell configured to increase chlorine capture and concentration in the cell's output solution, comprising:
an anode chamber and a cathode chamber with inlets and outlets;

an electrolyte feed adapted for providing a source of anions and cations to the anode and cathode chambers;

the outlet of the cathode chamber connected in fluid communication with the inlet of the anode chamber; and

the inlet of the cathode chamber connected in fluid communication with a liquid source,

further comprising a degassing chamber having an inlet and outlet, the inlet connected in fluid communication with the cathode chamber and the outlet connected in fluid communication with the anode chamber,

wherein the inlet of the degassing chamber is elevated above the outlet of the anode chamber to move catholyte through the anode chamber by gravity.
The electrolytic cell of claim 1 wherein the inlet of the degassing chamber is elevated above the outlet of the degassing chamber.
The electrolytic cell of claim 1 wherein the degassing chamber includes an outlet vent elevated above the outlet of the anode chamber.
The electrolytic cell of claim 1 wherein the degassing chamber includes a reservoir between the inlet and the outlet, the reservoir having a liquid level maintained generally at the level of the outlet of the anode chamber.
The electrolytic cell of claim 1 further comprising a manifold that incorporates the degassing chamber.
The electrolytic cell of claim 5 wherein the manifold includes:
a. a liquid inlet connected in fluid communication with the liquid source and inlet of the cathode chamber; and

b. a solution outlet connected in fluid communication with the outlet of the anode chamber.
The electrolytic cell of claim 5 wherein the manifold further comprises:
a. a vent outlet connected in communication with the degassing chamber;

b. an anolyte drain outlet connected in fluid communication with the anode chamber and the degassing chamber; and

c. a catholyte drain outlet connected in fluid communication with the cathode chamber.
The electrolytic cell of claim 1 further comprising a chamber connected in fluid communication with the electrolyte feed.
A method for chlorine capture in an electrolytic cell, comprising:
providing an electrolytic cell having an anode chamber and a cathode chamber with inlets and outlets;

feeding an electrolyte to the cell for providing a source of anions and cations to the anode and cathode chambers;

recycling catholyte from the cathode chamber through the anode chamber; and

dispensing an output solution from the anode chamber,

further comprising communicating catholyte from the cathode chamber through a degassing chamber before recycling through the anode chamber, and

gravity feeding catholyte from the degassing chamber through the anode chamber.
The method of claim 9 venting gas from the catholyte in the degassing chamber.
The method of claim 9 further comprising communicating electrolytes from the electrolyte feed through the cell.