EDI module with stabilizing DC current

• US 7,261,802 B2
• Filed: 07/07/2003
• Issued: 08/28/2007
• Est. Priority Date: 08/07/2002
• Status: Active Grant

• Current Assignee: Zhejiang OMEX Environmental Engineering Co., Ltd. (DuPont de Nemours, Inc.)
• Original Assignee: Zhejiang OMEX Environmental Engineering Co., Ltd. (DuPont de Nemours, Inc.)
• Inventors: Xu, Guorong, Luo, Guolin
• Primary Examiner(s): Phasge; Arun S.
• Application Number:
  US10/614,536
• Publication Number:
  US 20040027100A1
• Time in Patent Office: 1,513 Days
• Field of Search: 204/524, 204/533, 204/536, 204/632, 204/519, 204/628
• US Class Current: 204/628
• CPC Class Codes: B01D 61/48 having one or more compartments filled with ion-exchange material , e.g. electrodeionisation
• CPC Class Codes: B01D 61/52 Accessories; Auxiliary operation
• CPC Class Codes: B01D 61/54 Controlling or regulating
• CPC Class Codes: B01D 63/107 Specific properties of the central tube or the permeate channel
• CPC Class Codes: C02F 1/4695 electrodeionisation
• CPC Class Codes: C02F 2201/46125 Electrical variables
• CPC Class Codes: C02F 2201/4616 Power supply
• CPC Class Codes: G05F 3/06 using combinations of saturated and unsaturated inductive devices, e.g. combined with resonant circuit
• CPC Class Codes: H02M 7/17 arranged for operation in parallel

Abstract

A stabilizing DC current interface for an electro-deionization (EDI) water purifying module. Each EDI module comprises anionic/cationic membranes, a center pipe, nets/spacers in concentrate/dilute water chambers and an anode and cathode for coupling to the stabilizing DC current interface. Because a stabilized DC current is provided by the interface, the power to each EDI module is not influenced by water temperature, flow rate, water quality in the module, thereby providing a stabilized quality product water while saving energy. A plurality of EDI modules can be operated in electrical series using a DC current interface resulting in reduced DC power consumption.

Claims

1. An electrodeionization (EDI) module purifying a fluid flow which EDI module is energized by DC power between an anode and a cathode, which converts an AC source into a stable DC current comprises:

a transformer coupled to the AC source which can be adjusted for providing varying AC power at an output of the transformer;

a phase-controller for controlling operation of a rectifier base on the AC power and on a feedback signal from the DC power;

an autotransformer for adjusting said transformer to further adjust DC voltage/current output according to fluid temperature, fluid flow rate, fluid quality, or variances in the AC source or in the construction of the EDI module.

2. The electrodeionization EDI module of claim 1, wherein said autotransformer is automatically adjusted by an automatic control system which comprises:

a sampling circuit having an input coupled to said anode;

a reference voltage circuit having an input coupled to an output of said sampling circuit to form an electrical power interface input, said reference voltage circuit comparing said electrical power interface input against a reference voltage to generate difference signal;

an amplifier for amplifying said difference signal; and

a DC motor having an electrical power input coupled to a DC power supply through a switch controlled by said amplifier, said DC motor having a mechanical output coupled to and controlling a spindle of said autotransformer based on said difference signal.

3. The electrodeionization EDI module of claim 1, wherein said feedback signal comprises a voltage signal.

4. The electrodeionization EDI module of claim 1, wherein said rectifier is a full-wave rectifier.

5. The electrodeionization EDI module of claim 1, wherein said rectifier comprises a single-phase rectifier.

6. The electrodeionization EDI module of claim 1, wherein said rectifier comprises a three-phase rectifier.

7. The EDI module of claim 1, further comprising alternating anionic and cationic membranes which define alternating fluid chambers and concentrate chambers for conveying said fluid flow and a concentrate flow, respectively, said fluid chambers comprising ion exchange resins, all of which are spirally-wound around a central conductive pipe and all of which are contained within a conductive lining, said central conductive pipe comprising said cathode and said conductive lining comprising said anode, said cathode and said anode being connected to an electrical interface respectively.

8. An EDI module according to claim 7, wherein the electrical power interface further comprises an automatic control system coupled to an autotransformer for automatically adjusting said autotransformer.

9. An EDI module according to claim 8, wherein said automatic control system comprises:

a sampling circuit having an input coupled to said anode;

a reference voltage circuit having an input coupled to an output of said sampling circuit to form an electrical power interface input, said reference voltage circuit comparing said electrical power interface input against a reference voltage to generate difference signal;

an amplifier for amplifying said difference signal;

a DC motor having an electrical power input coupled to a DC power supply through a switch controlled by said amplifier, said DC motor having a mechanical output coupled to and controlling a spindle of said autotransformer based on said difference signal.

10. An EDI module according to claim 7, wherein said feedback signal comprises a voltage signal.

11. An EDI module according to claim 7, wherein said rectifier is a full-wave rectifier.

12. An EDI module according to claim 7, wherein said rectifier comprises a single-phase rectifier.

13. An EDI module according to claim 7, wherein-said rectifier comprises a three-phase rectifier.

14. The EDI module of claim 11, wherein the electrical power interface comprises a transformer coupled to the AC source that is adjustable for providing varying AC power at the transformer output and a phase-controller for controlling the operation of a rectifier based on the AC power and on a feedback signal from the DC power.

15. The EDI module of claim 14, wherein the transformer comprises an autotransformer.

16. A method for providing a stable DC current to the electrodeionization (EDI) module of claim 1 from an alternating current (AC) source wherein the at least one EDI module purifies a fluid flow when DC power is provided between an anode and a cathode of the EDI module, said method comprising a step of rectifying the AC power from the AC source into DC power using phase control and DC power feedback to stabilize the DC current after rectification that is unaffected by the fluid temperature, fluid flow rate, fluid quality, or variances in the AC source or in the construction of the at least one EDI module.

17. The method of claim 16, wherein said step of rectifying the AC power comprises synchronizing a phase controller with the AC power.

18. The method claim 17, wherein said step of rectifying the AC power comprises feeding back a voltage signal from the DC power to said phase controller.

19. The method of claim 16, wherein said phase controller uses proportional/integral control to generate pulse commands to a rectifier.

20. The method of claim 19, wherein said step of using proportional/integral control permits the control of pulse command parameters.

21. The method of claim 20, wherein said pulse command parameters include pulse width.

22. The method of claim 20, wherein said pulse command parameters include pulse amplitude.

23. The method of claim 20, wherein said pulse command parameters include pulse edge slope.

24. The method of claim 19, wherein step of rectifying the AC power into DC power comprises disposing an autotransformer between the AC source and a rectifier, said autotransformer being adjustable.

25. The method of claim 24, wherein said step of disposing an autotransformer between the AC source and said rectifier comprises automatically controlling the adjustment of said autotransformer based on said DC current.

26. The method of claim 25, wherein said step of automatically controlling the adjustment of said autotransformer comprises:

coupling a DC motor output to said autotransformer;

continuously comparing a portion of said DC power to a reference and using a difference between said portion of said DC power and said reference to activate said DC motor.

27. At least two electrodeionization (EDI) modules of claim 1 connected in electrical series for purifying a fluid flow which are energized by DC power between an anode of one of said at least two EDI modules and a cathode of the other one of said at least two EDI modules, wherein the DC power energizes the EDI module with stable DC current with a stable DC current that is converted from an AC source by an electrical power interface which further adjusts the DC voltage/current output so that the DC current that energizes the EDI module is unaffected by the fluid temperature, fluid flow rate, fluid quality, or variances in the AC source or in the construction of the EDI module.

28. At least two EDI modules according to claim 27, wherein said electrical power interface comprises a transformer that is coupled to the AC source, which transformer is adjustable for varying AC power at an output of the transformer, a phase-controller for controlling the operation of a rectifier based on the AC power and a feedback signal from the -DC power, said rectifier having a positive node and a negative node, and wherein said positive node is coupled to the anode of at least one of the at least two EDI modules and wherein said negative node is coupled to the cathode of another one of said at least two EDI modules, and wherein the cathode of at least one of the at least two EDI modules is coupled to the anode of said another one of said at least two EDI modules.

29. A method for providing a DC current to at least two electrodeionization (EDI) modules of claim 1 that are connected in electrical series, from an alternating current (AC) source wherein the at least two EDI modules purify a fluid flow when DC power is provided between an anode of one of said at least two EDI modules and a cathode of the other one of said at least two EDI modules, said method comprising a step of rectifying the AC power from the AC source into DC power and powering said at least two EDI modifies with the same DC current.

30. The method of claim 29, wherein said step of rectifying the AC power comprises using phase control and DC power feedback to stabilize the DC current after rectification that is unaffected by the fluid temperature, fluid flow rate, fluid quality, or variances in the AC source or in the construction of the at least EDI module.

31. The method of claim 30, wherein said step of rectifying the AC power comprises synchronizing a phase controller with the AC power.

32. The method claim 31, wherein said step of rectifying the AC power comprises feeding back a voltage signal from the DC power to said phase controller.

33. The method of claim 30, wherein said phase controller uses proportional/integral control to generate pulse commands to a rectifier.

34. The method of claim 33, wherein said step of using proportional/integral control permits the control of pulse command parameters.