Integrated water treatment system

An integrated water treatment system for sanitizing the water in a water system and reducing scaling includes an electrolytic cell through which water is passed. An electronic control system is coupled to the electrolytic cell, to provide a drive current to the cell to generate a sanitizer by electrolysis. The control system applies a variable frequency alternating voltage drive to said cell to reduce scaling build-up in the system.

BACKGROUND

Electrolytic cells can be used to generate a sanitizer, e.g., halogen, such as bromine or chlorine, for providing sanitizing water treatment in a body of water. For example, electrolytic cells may be used to sanitize swimming pools, fountains, spas, hot tubs and other bodies of water. The electrolytic cell may include plates mounted in a recirculating flow path for the body of water. The water has a dissolved electrolyte which when subjected to electrolysis is transformed into a sanitizer. For example, a salt such as sodium chloride may be dissolved in pool water. When subjected to electrolysis, the halogen (chloride) portion of the salt may be generated to form a sanitizer which has the ability to oxidize or kill bacteria, algae and other unwanted elements. Electrolytic cells are known in the art. One example is the ECOmatic™ system marketed by Balboa Direct.

Electrolytic cells may be susceptible to calcification scaling. Calcification or other scaling may also build up on other elements of a water system.

DETAILED DESCRIPTION

In the following detailed description and in the several figures of the drawing, like elements are identified with like reference numerals. The figures are not to scale, and relative feature sizes may be exaggerated for illustrative purposes.

An exemplary embodiment of an integrated water treatment system may be capable of electrolytic generation of a sanitizer, e.g. a halogen such as chlorine or bromine, from a conductive electrolyte in the water, and capable of reducing build-up of scaling by calcium compounds or other scale forming substances. Exemplary applications for the water treatment system include, but are not limited to, pools, spas, fountains, boilers, cooling towers, and ship ballast compartments.

FIG. 1is a schematic block diagram of an exemplary embodiment of an integrated water treatment system200. The system may include an electrolytic cell202through which the water is passed, a power source204and a time-varying signal generator206. A sanitizer may be generated by electrolysis using a current applied to the cell by the power source204. In addition to the generation of a sanitizer, the system may also condition the water by the application of a signal to the cell by generator206to prevent scaling build-up inside the cell and on associated hardware.

In an exemplary embodiment, the power supply204may function as a constant current source for the cell202. The AC signal generator206may in an exemplary embodiment provide a variable frequency, low voltage signal applied to the cell202.

In an exemplary embodiment, the electrolytic cell202may be a two terminal cell, with terminals A, B, constructed with multiple plates of a metal, such as titanium. The plates may typically be coated with a corrosion resistant material, such as, for example, rhuthenium dioxide, to prevent decomposition due to the electrolytic process. Additional plates may be added in parallel to increase the sanitizer output and improve the reliability of the cell. An exemplary electrolytic cell suitable for the purpose is described in application Ser. No. 11/294,181, entitled “Electrolytic Cell Assembly,” filed Dec. 5, 2005, the entire contents of which are incorporated herein by this reference.

FIG. 2is a schematic diagram of an exemplary embodiment of the cell202, wherein one plate202A is positioned centrally between outer plates202B,202C, and connected to terminal A. The outer plates202B,202C are connected to terminal B in this exemplary embodiment, and thus have opposite polarity from the polarity of terminal A. Additional plates, e.g. plates202D,202E may be positioned between the center plate and the outer plates, and are not connected to either terminal or to each other. This configuration is merely one example of a possible configuration for the cell. For example, the cell may employ single plates for each polarity.

In an exemplary embodiment, the electrolytic sanitizing generator function of the system200may be controlled by the closed loop application of current into the cell202.FIG. 3illustrates an exemplary embodiment of an electrical schematic of the electrolytic generator portion of the system200. Input power from a typical AC power source (e.g., 120 Vac or 240 Vac) may be converted to a low voltage (e.g., 30 VAC) via a step-down transformer210. This low AC voltage is rectified by rectifier circuit212to provide a DC voltage (e.g., 40 VDC) and applied to the cell202to drive an average direct current into the cell.

The application of current to the cell may be monitored and adjusted to remain substantially constant across varying water conditions or changes in the electrolyte in the water in the cell202. In an exemplary embodiment, a controller230may monitor the current flow by sensing the voltage at node224, e.g. by conductor226to an analog to digital converter comprising the controller230. Periodically, or on a demand basis, the direction of the current may be reversed in order to clean deposits or contamination from the cell. This may be accomplished in an exemplary embodiment by switches214,216,218,220, under control of the controller230. In an exemplary embodiment, the switches may be solid state devices, e.g. transistors. For current flow in a first direction through the cell, switches214and220may be set to a closed state, and switches216and218set to an open state. Current from the power supply will flow through switch214, the cell202, switch220and resistor222to a ground. To reverse the current flow direction, the switch states are reversed, so that current flows through switch216, the cell202, switch218and resistor222to ground.

In an exemplary embodiment, the control circuit230may include a microprocessor and associated control and support circuitry, with the microprocessor programmed to execute an algorithm to control the switches214-220to provide a variable pulse width modulated DC-to-DC constant current source function. Input power from a utility source such as 240 Vac 60 Hz power may be transformed by the transformer210to a low voltage, e.g. of approximately 30 VAC. The low voltage power may be rectified and filtered by circuit212to provide a constant DC voltage used to drive the cell and generate the sanitizer. The low voltage power may also be used to power the microprocessor and support circuitry.

In an exemplary embodiment, upon power-up, closed-loop application of constant current is controlled via the microprocessor-based controller230, which increases the current applied to the cell until the monitored average current matches the requested or a set point current level. The controller230may achieve this by pulse width modulating the DC voltage applied to the cell. For example, say current is being passed from terminal A to terminal B by suitable setting of switches216and218to the open state, and switches214and220set to the closed position. The current through the cell may be pulse width modulated by opening and closing switch214, under control of the control circuit230. When conditions change in the electrolyte, the microprocessor detects an increase (or decrease) in the current passing through the cell, and adjusts the applied voltage to reduce (or increase) the current back to the desired level.

In an exemplary embodiment, water conditioning may be accomplished through the application of a AC signal waveform to the cell. In an exemplary embodiment, the AC signal waveform may be a switched, variable high frequency signal capacitively coupled to the cell. This high frequency signal may be connected to the cell along with the current source generating the sanitizer, resulting in a superposition of two signals. The superposition of signals may both generate sanitizer and reduce or substantially prevent scaling on the cell plates.

FIG. 4is a schematic diagram of an exemplary embodiment of a water conditioning system206of a water treatment system. An input power source, e.g. delivering in this example 20 VDC, is applied to the system206at node250. Solid state switches240and242are connected in series to node246, between the node250and node252, connected to ground. A coupling capacitor244and resistor245connect node246to terminal A of the cell202. Terminal B of the cell202is connected to node252.

In an exemplary embodiment, a microprocessor-based control circuit254may generate a time-varying signal, e.g. a square wave or rectangular wave signal with a variable frequency greater than 1 Hz, e.g. in a frequency range from 1 Hz to 20 KHz or higher, by selective actuation of the solid state switches240,242. The generated signal waveform is capacitively coupled to the cell202by capacitor244, which transfers charge stored in the capacitor into the cell in a short amount of time. The capacitively-coupled, time-varying signal applied to the cell202may reduce or prevent the build-up or scaling of deposits on the cell and associated components. Various waveforms may be employed for this purpose. One exemplary waveform is a variable frequency waveform wherein the frequency is slowly swept from about 3 KHz to about 5 KHz in a period of one minute, and then repeats.

In an exemplary embodiment, the control circuit254may control the switches240,242to generate a square wave or rectangular wave signal waveform. By selectively opening and closing the switches, positive-going and negative-going waveform portions may be applied to the coupling capacitor244. For example, by opening switch240and closing switch242, node247is pulled down to the potential of a floating ground at node252. Similarly, by opening switch242and closing switch240, node247is pulled up to the potential of the power supply, e.g. 20 VDC at node250. Repetition of this cycle will result in a rectangular wave signal waveform being applied to the coupling capacitor244, which is series connected to the cell202(modeled as a capacitor). The microprocessor control circuit254may readily modify the duty cycle and frequency of the rectangular wave signal. The coupling capacitor244will filter the waveform applied to the electrolytic cell202.

Exemplary signal waveforms are depicted inFIGS. 5A-5C.FIG. 5Aillustrates an exemplary set of control signal waveforms generated by the control circuit254and applied to the control terminals of switches242(top waveform) and242(bottom waveform). In this exemplary embodiment, the signal applied to the control terminal of switch242varies between 20 volts and 15 volts, and the signal applied to the control terminal of switch240varies between 0 volts and 5 volts.FIG. 5Billustrates an exemplary square wave waveform applied to node247by the switching of switches240,242.FIG. 5Cshows an exemplary high frequency time-varying current through resistor245resulting from the drive signal ofFIG. 5B.

FIG. 6is a schematic diagram of an exemplary embodiment of an integrated water treatment system with a common controller. Like numbered elements from the embodiments ofFIGS. 3 and 4are integrated together, to drive the cell202to generate a sanitizer through electrolysis, and to reduce or eliminate scaling buildup on the cell plates and other components of the water system. The microprocessor control circuit260is configured to carry out functions of both controllers230and240of the embodiments ofFIGS. 3 and 4. It is noted that the ground connections228,248for this exemplary embodiments are respective floating grounds, and are not connected to earth ground. The circuit260may apply a composite drive signal to the cell, which is the superposition of the drive signal for the sanitizing function and the high frequency time-varying signal for the treatment function.FIG. 5Dillustrates an exemplary variable pulse width modulated DC-to-DC constant current drive applied to terminals A and B of the cell for the sanitizing function.FIG. 5Eillustrates an exemplary composite drive signal applied to the cell terminals. The composite drive signal depicts an exemplary embodiment in which the polarity of the constant current component of the drive signal is reversed periodically or intermittently, e.g. every few hours or so.

FIG. 7illustrates an exemplary embodiment of a spa or pool system1, which may include an integrated water treatment system. In an exemplary embodiment, a spa or pool system1may include a vessel2holding a body of water2A. The spa or pool system1may also include a pump3for recirculating the water. In an exemplary embodiment, the pump3may draw water from the body of water2A through a filter4A and a secondary suction port4B into a recirculating water flow line4, and pump the water back into the body of water2A through a discharge side of the recirculating water flow line4. The filter may be located at various locations in the system1, and is diagrammatically shown inFIG. 7. In an exemplary embodiment, the recirculating water flow line may be piping, for example PVC piping. A heat exchanger or heater3A may be in the water flow line4.

In an exemplary embodiment, the system1may include an electrolytic cell assembly5. The electrolytic cell assembly5may include an electrolytic cell housing or electrode plate support6supporting electrode plate set21, and a connection port or cell retainer7for detachably connecting the housing6to an opening in the flow line4. The cell retainer7may include an opening fluidically connected to the flow path8through the flow line4. In an exemplary embodiment, the cell retainer7may be attached to a tee44which is connected in the flow line4. The electrode plate set21may extend through the cell retainer7and into the flow path8within the flow line4. Operation of the electrolytic cell assembly5, in an appropriate aqueous solution, may cause the generation of halogens, for example chlorine or bromine, thereby providing sanitizing water treatment for water moving along the flow path8through the flow line4. The cell assembly5may also be operated to condition the water to reduce or eliminate scaling on components of the cell assembly and the spa or pool system1. In an exemplary embodiment, the electrolytic cell assembly may be located on the flow line4on the discharge side of the pump3. In another embodiment, the electrolytic cell assembly may be located on the flow line4on the intake side of the pump. The particular configuration of the exemplary electrolytic cell is described more particularly in co-pending application Ser. No. 11/294,181.

Referring again toFIG. 7, in an exemplary embodiment, the spa or pool system1includes a control system10, which receives electrical power from an external power source9, typically a line voltage at 120 VAC or 240 VAC. The control system10provides auxiliary power lines11to supply power at the appropriate voltage and current levels to operate and control various components of the spa or pool system1, including for example the pump3. Other typical components may include a water heater3A and a light system. In an exemplary embodiment, the control system10includes an electrolytic cell drive circuit19which provides electrical power to drive the electrolytic cell5through lines18. The control system10may include a microprocessor-based controller12which provides control signals and power to the electrolytic cell drive circuit19. Alternatively, the drive circuit19may be a stand alone circuit which may interact with control system10. The control system10and the drive circuit19collectively perform the functions of microprocessor control circuit260ofFIG. 6, to perform the sanitizing and de-scaling functions. In an exemplary embodiment, the control system10may be programmed to activate the de-scaling function whenever the pump3is activated, and the de-scaling function is de-activated when the pump is off.

FIG. 7Aillustrates an alternate exemplary embodiment of a spa or pool system100. In an exemplary embodiment, the electrolytic cell assembly5is connected in a separate recirculating water path or circuit400. A pump300may be controlled by the control system10to recirculate water through the water path400and the cell5. This permits independent control over functions provided by the cell5, e.g. sanitizing and de-scaling functions, without requiring the heating and/or water recirculation functions provided by pump3to be activated. The control system10may include a microprocessor-based controller12which provides control signals and power to the electrolytic cell drive circuit19. Alternatively, the drive circuit may be a stand alone circuit which may interact with control system10, or may even be a stand-alone control/drive system.

FIG. 8is a simplified diagrammatic illustration of a water system300with a water vessel302, which may be a boiler, a ship's ballast, a fountain basin, a pool or spa, by way of example only. A pump304recirculates water from the vessel302through a water flow path306. The system may include other components in the water flow path, such as a filter or a heater, for example, but for simplicity these are not shown inFIG. 8. A cell202is mounted in the water flow path306. A controller260controls the operation of the cell202as well as the pump304in this embodiment. The cell202may be operated by the controller to perform sanitizing and de-scaling functions, in a manner described above regarding the embodiments ofFIGS. 1-6.

Among the advantages of the integrated water treatment system exemplified inFIG. 8is that a single cell may be operated to perform both the sanitizing and the water conditioning functions, and a single controller system may operate the cell. This may reduce cost, space requirements for multiple elements, and may improve system reliability.

Although the foregoing has been a description and illustration of specific embodiments of the invention, various modifications and changes to the subject matter can be made by persons skilled in the art without departing from the scope and spirit of the invention as defined by the following claims.