Capacitive deionization system

Abstract

A capacitive deionization system comprising: a CDI device; a power supply device electrically connected with the CDI device, capable of providing a programmable voltage and/or a programmable current to the CDI device in response to an input signal; at least one of: (i) an electric current meter for measuring the electric current I flowing through the CDI device; and (ii) a voltage meter for measuring the voltage V supplied to the CDI device; an optional output stream sensor for monitoring the output stream and providing an optional output stream data DE; an optional input stream sensor for monitoring the input stream and providing an optional input stream data DI; a control device capable of sending an output signal to the power supply device to maintain or alter the voltage V and/or current I according to at least one of the results of I-ICREF, I-IDREF, V-VCREF, V-VDREF and optionally DE-DECREF and DE-DEDREF, wherein ICREF and IDREF are preset reference current data in the charge cycle and the discharge cycle, respectively, VCREF and VDREF are preset reference voltage data in the charge cycle and the discharge cycle, respectively, and DECREF and DEDREF are preset reference output stream data in the charge cycle and discharge cycle, respectively.

1 . A system for treating an aqueous input stream to produce an output stream comprising redistributed ions, comprising:
 a CDI device for the input stream to enter and the output stream to exit, capable of operating in a charge cycle and a discharge cycle;   a power supply device electrically connected with the CDI device, capable of providing a programmable voltage and/or a programmable current to the CDI device in response to an input signal;   at least one of: (i) an electric current meter for measuring the electric current I flowing through the CDI device; and (ii) a voltage meter for measuring the voltage V supplied to the CDI device;   an optional output stream sensor for monitoring the output stream and providing an optional output stream data DE;   an optional input stream sensor for monitoring the input stream and providing an optional input stream data DI;   a control device capable of sending an output signal to the power supply device to maintain or alter the voltage V and/or current I according to at least one of the results of I-ICREF, I-IDREF, V-VCREF, V-VDREF and optionally DE-DECREF and DE-DEDREF, wherein ICREF and IDREF are preset reference current data in the charge cycle and the discharge cycle, respectively, VCREF and VDREF are preset reference voltage data in the charge cycle and the discharge cycle, respectively, and DECREF and DEDREF are preset reference output stream data in the charge cycle and discharge cycle, respectively.   
   
   
       2 . A system according to  claim 1 , wherein the output stream sensor comprises an electrical conductivity meter and the output stream data DE comprise output stream electrical conductivity data DEEC. 
   
   
       3 . A system according to  claim 1 , wherein the input stream sensor comprises an electrical conductivity sensor and the input stream data DI comprise input stream electrical conductivity data DIEC. 
   
   
       4 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable voltage to the CDI device; and   during the charge cycle in which a charge voltage V is supplied to the CDI device wherein V>0, if I-ICREF≦0, the control device sends a signal S 1  to the power supply device to change V to enable the discharge cycle such that V decreases to 0, and then maintain V=0 until I-IDREF≦0 when the control device sends a signal S 2  to the power supply device to change V to enable the charge cycle.   
   
   
       5 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable voltage to the CDI device; and   during the charge cycle in which V>0, once I-ICREF≦0, the control device sends a signal S 3  to the power supply device to change V to enable the discharge cycle such that V decreases to a value below 0, and then maintain V≦0 until I-IDREF≦0 when the control device sends a signal S 3  to the power supply device to change V to enable the charge cycle.   
   
   
       6 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable voltage to the CDI device; and   during the charge cycle in which a charge voltage V is supplied to the CDI device wherein V>0, if DE reaches DECREF, the control device sends a signal S 1 A to the power supply device to change V to enable the discharge cycle such that V decreases to 0, and then maintain V=0 until DE reaches DEDREF when the control device sends a signal S 2 A to the power supply device to change V to enable the charge cycle.   
   
   
       7 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable voltage to the CDI device; and   during the charge cycle in which V>0, once DE reaches DECREF, the control device sends a signal S 3 A to the power supply device to change V to enable the discharge cycle such that V decreases to a value below 0, and then maintain V≦0 until DE reaches DEDREF when the control device sends a signal S 3 A to the power supply device to change V to enable the charge cycle.   
   
   
       8 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable current to the CDI device; and   during the charge cycle in which a charge current I is supplied to the CDI device wherein V>0, if V-VCREF≧0 the control device sends a signal SV 1  to the power supply device to change I to enable the discharge cycle such that V decreases to zero, and then maintain V=0 until I-IDREF≦0 when the control devices sends a signal SV 2  to the power supply device to change I to enable the charge cycle.   
   
   
       9 . A system according to  claim 1 , wherein:
 the power supply device provides a programmable current to the CDI device; and   during the charge cycle in which V>0, once V-VCREF≧0 the control device sends a signal SV 3  to the power supply device to change I to enable the discharge cycle such that V decreases to a value below zero, and then maintain V≦0 until V-VDREF≦0 when the control device sends a signal SV 3  to the power supply device to change I to enable the charge cycle.   
   
   
       10 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable current to the CDI device; and   during the charge cycle in which a charge current I and a charge voltage V are supplied to the CDI device wherein V>0, if DE reaches DECREF, the control device sends a signal S 1 A to the power supply device to change V to enable the discharge cycle such that V decreases to zero, and then maintain V=0 until DE reaches DEDREF when the control devices sends a signal SV 2 A to the power supply device to change I to enable the charge cycle.   
   
   
       11 . A system according to  claim 1 , capable of operating in a mode wherein:
 the power supply device provides a programmable current to the CDI device; and   during the charge cycle in which V>0, once DE reaches DECREF, the control device sends a signal S 3 A to the power supply device to change V to enable the discharge cycle such that V decreases to a value below zero, and then maintain V≦0 until DE reaches DEDREF when the control device sends a signal SV 3 A to the power supply device to change I to enable the charge cycle.   
   
   
       12 . A system according to  claim 1 , capable of operating in a mode wherein the discharge cycle starts with an initial discharge voltage VD 1  supplied to the CDI device, followed by a discharge voltage V<VD 1 . 
   
   
       13 . A system according to  claim 1 , wherein the CDI device comprises a membrane Ml over the surface of an electrode to selectively allow essentially only cations to pass through, and a membrane M 2  over the surface of the opposite electrode to selectively allow essentially only anions to pass through, during the operation of the CDI device. 
   
   
       14 . A system according to  claim 1 , wherein the control device collects and/or stores data V, I, DE, DI, ICREF, IDREF, VCREF, VDREF, DECREF, DEDREF, and computes the values I-ICREF, I-IDREF, V-VCREF, V-VDREF, DE-DECREF and DE-DEDREF. 
   
   
       15 . A system according to  claim 1 , capable of operating in a mode wherein ICREF is preset to correspond to a charge current of the CDI device at a time from ¼·τ to 4·τ, where τ is the RC time constant of the CDI device. 
   
   
       16 . A system according to  claim 1 , capable of operating in a mode wherein IDREF is preset to correspond to a discharge current of the CDI device at a time from ¼·τ to 4·τ, where r is the RC time constant of the CDI device. 
   
   
       17 . A system according to  claim 1 , capable of operating in a mode wherein the power supply device supplies an essentially constant voltage to the CDI device during the charge cycle of the CDI device. 
   
   
       18 . A system according to  claim 17 , capable of operating in a mode wherein the power supply device supplies a DC voltage from 0.2 to 5.8 volts to the CDI device during the charge cycle thereof. 
   
   
       19 . A system according to  claim 1 , wherein the CDI device comprises multiple CDI units, and the multiple CDI units are wired such that the discharge current of the some of the CDI units during the discharge cycle thereof can charge some some of CDI units sequentially or simultaneously during the charge cycle thereof. 
   
   
       20 . A system according to  claim 18 , wherein the control device is capable of controlling the electric switches between and among the multiple CDI units. 
   
   
       21 . A system according to  claim 1 , wherein the control device is further capable of controlling the flow rate of the input stream and/or the output stream.