A control assembly for an electrocoagulation cell (1) comprising a plurality of electrodes, a releasable connection means (6) between at least a selection of the electrodes and electrical connection means (9, 10, 9A, 10A) attached to the releasable connection means (6) which in use is connectable to a power supply (12). An electrocoagulation system comprising a plurality of electrodes (2), an electrolytic cell (1) having an internal chamber which contains the plurality of electrodes (2), and a power supply (12) connectable to a power source and also connectable to the electrodes said power supply having control means (14, 24) for providing a selected constant output current or selected constant output voltage whereby the electrolytic cell may process samples of varying characteristics.
This invention relates to an electrocoagulation system which an electrocoagulation cell includes as well as a control assembly for an electrocoagulation cell.BACKGROUND OF THE INVENTION
Electrolytic cells are commonly used for treating liquids to change the liquid for a predetermined purpose. Electrocoagulation is a particular electrolytic treatment process for separating and removing contaminants or undesirable contents from a liquid.
Typically an electrocoagulation cell contains electrodes and an electrolyte that is to be treated. The treatment process may be performed in a number of ways depending on the nature of the electrolyte.
Numerous prior patents describe electrocoagulation systems of which AU 707432 describes an electrochemical treatment device for softening water. The device is powered by a current generator producing a current which is adjustable and applied to an anode and cathode terminal of an electrolytic tank. The cathode is comprised of a number of plates which are held in place by connection of a plurality of bars. The bars are joined together to an anode terminal. The plates are joined together by a separate bar to a cathode terminal.
Another prior system is described in AU 738707 where a portable electrocoagulation apparatus includes an electrolytic cell having a plurality of vertically extending reaction blades. A selection of the blades have tabs which are electrically connected to power terminals for receiving power. The blades are held in place by a plurality of non-conductive rods. A control unit controls the system operation and applied power.
A further system is described in U.S. Pat. No. 4,790,923, where an electrolytic cell produces a halogen biocide and oxygen in a liquid containing a halogen salt. A plurality of bipolar electrode plates is mounted in the cell with only a select number of electrodes being connectable to a power supply.
Yet another system is described in WO 94/00860 where an electrolytic filter has electrically configurable connections to active electrodes in an electrolytic cell. A sensor senses a resistivity variation in the electrolytic solution and a control circuit varies the current flow by adjusting the separation between electrodes using relay contact switches for electrically connecting or disconnecting each active electrode.
A major drawback of the above systems is they are designed for a specific electrolyte or liquid which is to be treated. The electrodes used, their quantity and desired power requirements are specific to the liquid being treated.
A further drawback of conventional electrocoagulation systems is the high cost associated with designing a system for each specific application. Substantial testing and modification is required where the liquid stream changes in its concentration of contaminants.OBJECT OF THE INVENTION
It is an object of the invention to provide an improved electrocoagulation system.
It is a further object of the invention to provide an improved control assembly for an electrocoagulation cell that facilitates treatment of various liquids or species.SUMMARY OF THE INVENTION
In one form, although it need not be the only or indeed the broadest form, the invention in a first aspect resides in a control assembly for an electrocoagulation cell comprising:
- (i) a plurality of electrodes;
- (ii) releasable connection means between at least a selection of the electrodes comprising an elongate busbar which is arranged normal to respective top edges of each electrode in plan view and which extends through a notch, slot or aperture located in individual tabs which each extend upwardly from an adjacent top edge of each electrode whereby the busbar is spaced from the top edges of each electrode so as to avoid contact with liquid contained in the electrocoagulation cell in use as well as a plurality of fasteners attached to said busbar whereby each fastener abuts or is located closely adjacent to an adjoining surface of each electrode; and
- (iii) electrical connection means attached to the busbar at each end thereof which in use is connectable to a power supply.
The releasable connection means may facilitate the number of electrodes releasably connected to be varied according to specific requirements for treating a particular electrolyte.
The electrodes may be connected in a series arrangement.
The electrocoagulation cell can treat the electrolyte at a rate of 1 Litre per minute or 5 Litres per minute or 10 Litres per minute or 100 Litres per minute or 500 Litres per minute (LPM).
In a second aspect of the invention there is provided an electrocoagulation system comprising:
- (i) a controller that is selectable for providing both a constant output current and/or a constant output voltage whereby the electrolytic cell may process samples of varying characteristics;
- (ii) a voltage regulator;
- (iii) a transformer having a primary coil connected to the voltage regulator;
- (iv) a rectifier connected to a secondary coil of the transformer; and
- (v) a voltage or current regulator which receives an output from the rectifier and together with said controller effects a firing control of the voltage regulator.
The electrocoagulation system of the second aspect may also include a programmable logic control (PLC) for checking parameters associated with the flow of an electrolyte to and through the cell.
There also may be provided flow control means for delivering the electrolyte to the electrocoagulation cell.
In a preferred form of the invention, the flow control means includes a digital controller, variable AC motor drive, feed pump with pump motor and a flow transmitter.
The power supply of the second aspect may be connected to a three phase AC power source.
Preferably, the constant output current and the constant output voltage is a direct current (DC).
Preferably, if a constant output current is selected, then the DC current is maintained constant with respect to a reference set by the control means and the DC voltage may vary.
Preferably, if a constant output voltage is selected, then the DC voltage is maintained constant with respect to a reference set by the control means and the DC current may vary.
The constant output current or voltage may be set at a level according to the type of electrolyte which is to be treated.BRIEF DESCRIPTION OF THE DRAWINGS
In a preferred form, the invention will be described with reference to an electrocoagulation cell and system of the type described in the co-pending International Patent Application No. PCT/AU01/00054. However, it should be noted that the invention could also be realised with other types of electrocoagulation cells.
Referring now to
The electrocoagulation cell is used in fluid treatment plants for treatment and purification of a conductive solution such as might be produced by a manufacturing, treatment, refining or other process. Typically, a conductive solution is caused to flow between electrodes 2 at different electrical potentials. A current is caused to flow between the electrodes through the solution which results in a chemical reaction within the solution and in many cases, between the solution and the electrode material which comprises the electrode.
The electrodes 2 of the electrocoagulation cell 1 are made from metal alloys or other suitable metals and are shaped to fit into individual grooves (not shown) within the electrode housing 5. The electrodes are designed to provide sufficient reaction surface area to effectively treat an electrolyte solution such as water up to the maximum design rate of cell 1. Electrodes are unipolar (anodic or cathodic) or bipolar (anodic and cathodic). Bipolar electrodes have both surfaces of the electrode plate reacting with the electrolyte solution. One side is anodic, the other cathodic. Unipolar electrodes are either wholly anodic or wholly cathodic. Unipolar electrodes located at the ends of the reaction cell, (see
When the operating parameters of the electrocoagulation system are satisfied, a power supply is adjusted in its voltage or current and applied to the system, according to the specific power requirements for a particular liquid or species to be treated in the electrocoagulation cell. The power is disengaged whenever any of the operating parameters are outside their operational range or when a user manually stops the electrocoagulation system by activating a stop switch.
Referring now to
Each selected electrode 2 includes a slot 7 (shown in
The connected electrodes are uni-polar and hence are either anionic or cationic depending on the polarity of the power applied through power leads 9 and 10 each of which have connectors 9A and 10A having apertures (not shown) retained by nuts 10B on each side of connectors 9A and 10A. The remaining sixteen unconnected electrodes are bi-polar and they are charged by the energised electrolytic solution.
In the above arrangement of the busbar, the bar is threaded so that the securing nuts 11a can be threadably secured to the bar thereby bearing tight against the electrodes 2 to secure them to the bar 8. The bar may be made of a brass material which is resistant to rust and has good conductivity properties. However, other suitable material having these properties may used to secure and electrically connect the electrodes, such as steel.
The washer 11b assists in the protection of the electrode against wear from the nut 11a. The washer also increases the surface area of the current applied to the electrodes.
In operation, the bar 8 is placed in the slots 7 of adjacent electrodes 2 and the securing nuts 11a and washer 11b are secured against the electrodes to hold it in place. To replace an electrode, the securing nuts 11a are loosened so that they no longer bear tight against the electrode and the bar is simply lifted so that access can be gained to the electrodes as shown in
The electrocoagulation cell is designed to treat fluid such as water at various flow rates. In one embodiment of the invention, a power supply outputs the desired power requirements for treating the electrolyte solution at various flow rates.
Referring now to
A rectifier 16 converts the AC voltage into a DC signal and the adjusted and rectified signal is displayed on a display 17 for viewing by an operator. Depending on the type of treatment required and the types of electrodes used, the output signal may be a DC signal with a negative polarity adjusted by a reverse polarity timer 18 or a positive output signal adjusted by a forward polarity timer 19. The output of the power supply 12 is then applied to the busbar and electrodes of the electrocoagulation cell 1.
The variac of the power supply is rated at 15 amps with a maximum of 250 v AC. If the power source is required for a 10 LM electrocoagulation system, the variac is required to be rated at 28 amps due to the increased flow rate.
If the electrocoagulation system is operating at 10 LM, then a maximum output of 110 v DC at 28 amps is required to power the system. The power supply for the 10 LM system is similar to the 5 LM system except that is requires a larger variac rated at 28 amps and powered by 240 v single phase AC input at 20 amps (maximum).
The power supply will now be described in more detail with reference to FIGS. 5 to 8. Referring to
The power supply in
A voltage and a current potentiometer 24 (shown as one) connect between the main switch 20 and the voltage regulator 21 to control a DC output 25 to be either constant current or constant voltage. A voltage or current regulator 26 receives an output from the rectifier 23 and together with the potentiometer 24, effect the firing control 27 of the voltage regulator 21.
In the present embodiment, the power supply has two distinct modes of operation that allow the user to maintain either constant output voltage or constant amperage. These values are set by the voltage or current potentiometer 24. When the current potentiometer is set for constant current, the voltage pot is rotated to “100%” which allows the powersupplyto float output voltage between 0 and a full rated DC voltage. The constant current pot can then be set to the desired output current depending on the type and consistency of the electrolyte being treated.
As the load is increased or decreased, the amperage will remain at the set point while the voltage will vary. If the constant voltage pot is set at less than 100% output, the voltage will then be limited to this set point. In this case, if the set point is less than the required voltage to maintain a set current level, an automatic cross over to constant voltage will occur.
Alternatively, to maintain constant voltage, the constant current pot can be rotated clockwise so that it is at 100% thereby allowing the power supply to float the output current between zero and full rated DC amperage.
As noted above, the constant voltage pot is set to the desired output voltage, such as 110 v DC and as the load is increased or decreased, the voltage will remain at 110 v DC while the DC amperage will vary. If however, the constant current pot is set at less than 100%, the output current will be limited to the set point. Alternatively, if the set current is less than the minimum current required to maintain the set voltage level, an automatic cross over to constant current will occur.
A current trip is provided for protection against exceeding a maximum DC amperage rating of the power supply. If the DC amperage is exceeded, the power supply will continue to run, however, there will not be any output. Similarly, an over temperature relay 36 is provided to sense any overheating in rectifier 23 and if there is overheating, shutting down the power supply at the main switch 20.
The power supply of the present embodiment provides control of either the voltage or the current to produce a constant current or voltage at the desired output level.
Details of the power supply are illustrated in
Referring now to
The operation of the process flow and the power supply will be described with reference to
A flow transmitter 55 provides a signal to the PLC 47 whether the measured flow rate is greater than a low flow-set point and if so, the PLC signals the DC power supply 48 to start operation to provide a voltage across the electrodes of the electrocoagulation cell 1.
The power supply will cease applying a voltage across the electrodes if the mode switch 45 is set to a function other than a “run”, or a stop button is pressed, or a fault condition is detected in 51, or any other sensed parameter such as low flow is sensed in the flow transmitter 55. In these cases, the PLC will signal the power supply to stop operating.
The PLC can also cause the operation of the electrocoagulation to be paused, if for example a liquid level in a feed tank falls below the low level switch. In this case, the switch will open and the system will go into a pause mode where it will wait until there is sufficient fluid in the feed tank before automatically restarting the feed pump and the DC power supply.
In a further embodiment, the flow rate of the liquid entering the electrocoagulation system may be controlled by the power supply of the present invention. Referring to
The flow transmitter 55 measures the flow rate of the water being delivered to the electrocoagulation cell and transmits a signal back to the digital controller 21. The digital controller 21 then makes adjustments to its control signals in order to bring the measured flow rate to the flow rate set point entered by the user at 56. It will be appreciated that the flow rate of the electrolyte or water through an electrocoagulation cell may be of critical importance in the performance of the system.
The power supply may also control other functions associated with operation of the electrocoagulation system. For example, a cell drain control may be incorporated into the system whereby the cell is drained prior to cleaning, shut down or maintenance. Similarly, the system may be actuated to facilitate cleaning the cell using a cleaning solution in which case no voltage will be applied between the electrodes.
The invention has been described with reference to exemplary embodiments. However, it should be noted that other embodiments are envisaged within the spirit and scope of the invention, for example the power supply for the 100 LPM system could be used for a flow rate of 500 LPM.
1. A control assembly for electrocoagulation cell comprising:
- a. a plurality of electrodes;
- b. releasable connection means between at least a selection of the electrodes comprising an elongate busbar which is arranged normal to respective top edges of each electrode in plan view and which extends through a notch, slot or aperture located in individual tabs which each extend upwardly from an adjacent top edge of each electrode whereby the busbar is spaced from the top edges of each electrode so as to avoid contact with liquid contained in the electrocoagulation cell in use as well as a plurality of fasteners attached to said busbar whereby each fastener abuts or is located closely adjacent to an adjoining surface of each electrode; and
- c. electrical connection means attached to the busbar at each end thereof which in use is connectable to a power supply.
2. A control assembly as claimed in claim 1 wherein the busbar is threaded and the plurality of fasteners comprise one or more threaded nuts each having an associated washer.
3. A control assembly as claimed in claim 1 wherein the electrical connection means comprises a power lead secured to an electrical connector having an aperture for engaging with an adjacent end of the busbar.
4. A control assembly as claimed in claim 3 wherein each electrical connector is attached to the busbar with a fastener on either side of the connector.
5. An electrocoagulation system comprising:
- a. a controller that is selectable for providing both a constant output current and/or a constant output voltage whereby the electrolytic cell may process samples of varying characteristics;
- b. a voltage regulator;
- c. a transformer having a primary coil connected to the voltage regulator;
- d. a rectifier connected to a secondary coil of the transformer; and
- e. a voltage or current regulator which receives an output from the rectifier and together with said controller effects a firing control of the voltage regulator.
6. An electrocoagulation system as claimed in claim 5 wherein the control means in a voltage and current potentiometer.
7. An electrocoagulation system as claimed in claim 6 wherein the potentiometer is set for a constant output DC current thereby allowing the power supply to provide a variable output DC voltage.
8. An electrocoagulation system as claimed in claim 6 wherein the potentiometer is set for a constant output DC voltage thereby allowing the power supply to provide a variable output DC current.
9. An electrocoagulation system as claimed in claim 5 which has an adjustable switch connectable to the power source and which is also connected to the voltage regulator.
10. An electrocoagulation system as claimed in claim 5 which further includes a polarity switch relay to select an output polarity.
11. An electrocoagulation system as claimed in claim 5 which further includes a current trip for protection against exceeding a maximum DC amperage rating of the power supply.
12. An electrocoagulation system as claimed in claim 5 which further includes an over temperature relay to sense any overheating in the rectifier.
13. An electrocoagulation system as claimed in claim 9 which comprises:
- (vi) an adjustable switch connectable to a power source;
- (vii) a voltage regulator connected to the switch;
- (viii) a transformer having a primary coil connected to the voltage regulator;
- (ix) a rectifier connected to a secondary coil of the transformer and;
- (x) said control means being connected between the switch and the voltage regulator to control a DC output applied to the electrolytic cell to have said selected constant current or said selected constant voltage.
14. A power supply as claimed in claim 13 which further includes a polarity switch relay to select an output polarity.
15. A power supply as claimed in claim 13 which further includes a voltage or current regulator which receives an output from the rectifier and together with said control means effects a firing control of the voltage regulator.
16. A power supply as claimed in claim 13 wherein said control means includes a voltage and current potentiometer.
17. A power supply as claimed in claim 13 which further includes a current trip for protection against exceeding a maximum DC amperage rating of the power supply.
18. A power supply as claimed in claim 13 which further includes an over temperature relay to sense any overheating in the rectifier.
Filed: Nov 19, 2003
Publication Date: May 11, 2006
Inventor: Cameron King (Albion)
Application Number: 10/535,540
International Classification: C25B 9/04 (20060101);