METHOD FOR SANITIZING AN ELECTRODEIONIZATION DEVICE
BACKGROUND OF THE INVENTION
[001] The present invention relates to a water purification system that
incorporates an electrodebnization (EDI) device; and more particularly to a method
of sanitizing the EDI device.
[002] Electrodeionization generally refers to a process for purifying liquids
by combining ion exchange resins, ion exchange membranes, and electricity to purify
the liquids. The use of water purification systems has increased in many industries. In
particular, pure water is used in many industrial processes. Some of these processes
include: producing semiconductor chips, power plant operations, petrochemical
applications and producing pharmaceuticals. Ion exchange resins, reverse osmosis
(RO) filtration, and electrodialysis techniques have been used to reduce the
concentration of ions in a liquid. EDI devices are now commonly used as RO post
treatment to reduce the concentration of ions producing ultra-pure water.
[003] An EDI device generally includes an internal chamber, within which
alternating arrangements of cation permeable membranes and anion permeable
membranes define compartments. The diluting compartments contain ion exchange
resin particles, which are regenerated through electric field induced water
dissociatioa The concentrate compartments may contain ion exchange particles or
inert plastic netting to maintain membrane separation, and allow water flow. An
applied electric current induces ion migration from the diluting compartments through
the ion exchange media and ion permeable membranes into the concentrating
compartments. The Kquid flowing through the concentrating compartments is
discarded or partially recycled. The purified liquid flowing through the diluting
compartments is recovered as demineralized liquid product.
[004] Operation of the water purification system infects the EDI device with
bacteria and other undesirable substances. A sanitization process is used to disinfect
the EDI device. Some disinfecting methods involve passing a disinfecting solution,
which may include a chemical, at a temperature sufficient to inactivate any
microorganisms in the EDI device.
[005] There are a few issues with known methods of disinfecting the EDI
device. Known methods require external equipment (water supply, heating means,
etc) to disinfect the EDI device. Chemical disinfecting solutions may contain
chemicals that react with the active components in the EDI device. This may lead to
component degradation and the decrease of the usable life of the EDI device. These
issues add to the cost and complexity of the water purification system
[006] For the foregoing reasons, there is a desire for an improved method of
disinfecting an EDI device. The method should reduce the need for external
equipment and disinfecting chemicals.
BRIEF DESCRIPTION OF THE INVENTION
[007] In accordance with an embodiment of the present invention, a method
of sanitizing an electrodeionization (EDI) device, the method comprising; providing
an EDI device comprising an internal chamber comprising: an anode compartment
adjacent a first end of the internal chamber, a cathode compartment adjacent an
opposite second end of the internal chamber, and a plurality of ionic membranes
positioned between the anode and the cathode compartments; stopping a fluid supply
to the internal chamber; supplying an electrical power across the anode and the
cathode compartments until a temperature within the internal chamber is within a
sarritization range; and controlling the electrical power to maintain the temperature
within the internal chamber within a sarritization range; wherein the elevated
temperature produced by the electrical power sanitizes the EDI device while the fluid
supply is minimized.
[008] In accordance with an alternate embodiment of the present invention, a
method of sanitizing an electrodeionization (EDI) device associated with a deionized
water producing system, the method comprising: providing a water purification
system configured for producing deionized water, the water purification system
comprising at least one o a micro-filtration apparatus, an activated carbon tower, or
a reverse osmosis apparatus; providing an EDI device, integrated with the water
purification system, wherein the EDI device comprises an internal chamber
comprising: an anode compartment adjacent a first end of the internal chamber, a
cathode compartment adjacent an opposite second end of the internal chamber, and a
plurality of io ni membranes positioned between the anode and the cathode
compartments; modulating an isolation valve to stop a fluid supply to the internal
chamber; supplying an electrical power to the internal chamber to create a
temperature rise with the internal chamber; determining whether a temperature within
the internal chamber is within a sanitization range; and maintaining the temperature
within the sanitization range; wherein the electrical power sanitizes the EDI device.
BRIEF DESCRIPTION OF THE DRAWING
[009] FIG. 1 is a schematic illustrating a known water purification system
[010] FIG. 2 is a schematic illustrating a water purification system, in
accordance with an embodiment of the present inventioa
[01 1] FIG. 3 is a flowchart illustrating a method of disinfecting an EDI
device, in accordance with an embodiment of the present inventioa
DETAILED DESCRIPTION OF THE INVENTION
[012] The present invention has the technical effect of disinfecting an EDI
device of a water purification system. The present invention may be applied to an
EDI device having an internal chamber comprising ion exchange components. The
ion exchange components may include, but are not limited to, an anode compartment
adjacent a first end of the internal chamber, a cathode compartment adjacent an
opposite second end. The internal chamber may also comprise a plurality of ion
selective membranes positioned between the anode and the cathode compartments.
As illustrated and described herein, embodiments of the present invention seek to
sanitize the EDI device without the use of sanitization chemicals or a secondary hot
water supply.
[013] Detailed example embodiments are disclosed herein However,
specific structural and ftmctional details disclosed herein are merely representative for
purposes of describing example embodiments. Example embodiments may, however,
be embodied in many alternate forms, and should not be construed as limited to only
the embodiments set forth herein. For example, but not limiting of, the water
purification system 100, as illustrated in FIGS. 1 and 2, comprise the following
components: a heat exchanger 105; a micro -filtration apparatus 110; an activated
carbon tower 15; a tank 120; a pumpl25; a reverse-osmosis apparatus 130; and an
EDI device 140. Embodiments of the present invention are not intended to be limited
to a water purification system 1 0 comprising all of those components. Indeed,
embodiments of the present invention may be applied to other water p urifi ca t
systems 00 comprising more or less than the aforementioned components.
[014] Accordingly, while example embodiments are capable of various
modifications and alternative forms, embodiments thereof are illustrated by way of
example in the drawings and will herein be described in detail. It should be
understood, however, that there is no intent to limit example embodiments to the
particular forms disclosed, but to the contrary, example embodiments are to cover all
modifications, equivalents, and alternatives Ming within the scope of example
embodiments.
[015] It will be understood that, although the terms first, second, etc. may be
used herein to describe various elements, these elements should not be limited by
these terms. These terms are only used to distinguish one element from another. For
example, a first element could be termed a second element, and, similarly, a second
element could be termed a first element, without departing from the scope of example
embodiments. As used herein, the term "and/or" includes any, and all, combinations
of one or more of the associated Msted items.
[016] Referring now to the FIGS., where the various numbers represent like
elements throughout the several views, FIG. 1 is a schematic illustrating a known
water purification system 100. FIG. 1 may be considered a non-Hmiting example of a
known configuration of a water purification system 100. Feedwater enters the heat
exchanger 105 and is treated by the micro- filtration (MF) apparatus 110 and then by
the activated carbon (AC) tower 15. Next, the feedwater is fed from the tank 120 to
the reverse osmosis (RO) apparatus 130 via the pump 125. If required, the permeated
water from the RO apparatus 130 is conditioned by the heat exchanger 135. Next, the
feedwater is treated by the EDI device 140.
[0 ] A known method of sanitizing the water purification system 100 may
involve the following steps. First, for disinfecting purposes, hot water of around 175
Degrees Fahrenheit may flow from the heat exchanger 105 to the RO apparatus 130
via the MF apparatus 10, the tower 115, the tank 120, and the pump 125.
[018] Next, the EDI device 140 is disinfected. Here, water at an ambient
temperature flows through the heat exchanger 105, the MF apparatus 110, the tower
1 5, the tank 120, the pump 125, the RO apparatus 130, the heat exchanger 135, and
the EDI device 140. The heat exchanger 135 heats the ambient water at a specified
rate until the temperature reaches around 175 Degrees Fahrenheit, as the water exits
the diluting compartment of the EDI device 140. Next, the hot water flows through
the EDI device 140 for a designated soak time. Next, the hot water is cooled at
designated rate until the temperature at the outlet of the diluting compartment is
around 95 Degrees Fahrenheit.
[019] FIG. 2 is a schematic illustrating a water purification system 100, in
accordance with an embodiment of the present invention. Embodiments of the
present invention provide a system for disinfecting the EDI device 140, without the
use of a heated water supply and/or chemicals. The majority of the components of the
water purification system 100 may be the same or similar to those illustrated in FIG.
1. For comparison purposes, the discussion of FIG. 2 will focus on the aspects and
the features of the present inventioa As illustrated in FIG. 2, embodiments of the
present invention do not require the heat exchanger 135 to heat water for use in
disinfecting the EDI device 140. As described below, an isolation valve 145 stops the
water supply flowing into the EDI device 140 while the disinfecting process is
performed.
[020] Embodiments of the present invention use electrical power to disinfect
the EDI device 140. Here, an electrical supply device 160 may use resistive heating
to heat the internal chambers of the EDI device 140. The heating may occur until the
internal chambers reach a sanitization temperature.
[021] The resistive heating is a result of the ionic movement through the
internal chamber. The friction that is created through the ionic movement increases
the temperature within the internal chamber. As the temperature of the internal
chamber increases, the viscosity of the fluid therein decreases, the friction also
decreases, and the ionic movement increases. This, along with other water splitting
phenomena, ay result in an overall decrease in the electrical resistance of the EDI
device 140. Given the proportional relatfonship between voltage (V) and the product
of current (I) and resistance (R), V= I*R. the following non- limiting example
demonstrates the effect of the heating of the internal chamber, in an embodiment of
the present invention
■ Initially, the temperature of the internal chamber is around 20
Degrees Centigrade, and the voltage around 150 Volts.
■ A constant current is applied and the voltage becomes an
indication of the resistance.
■ The voltage decreases to around 100 Volts when the water
within the internal chamber is in the sanitization temperature
range.
Thus, the voltage drop across the EDI device 140 may be monitored to determine
whether the internal chamber is within the sanitization range.
[022] Temperature devices, such as, but not limiting of, thermocouples,
resistance temperature detectors (RTDs), or the like, may also determine when the
sanitization temperature has been reached. A first embodiment of the temperature
device may comprise an external temperature device 155, which may determine the
temperature on a surface outside of the EDI device 140. This may be considered the
skin temperature and may correlate to temperature within the internal chamber. A
second embodiment of the temperature device may comprise internal temperature
device 150, which may determine the temperature inside the internal chamber. A
third embodiment of the temperature device may comprise a device that measures a
temperature of the water within the internal chamber, which correlates to the
temperature inside of the internal chamber.
[023] After the internal chamber maintains the sanitization temperature for a
soak time, a rinse may be performed to remove collected organic and inorganic
impurities from the EDI device 140.
[024] In an alternate embodiment of the present invention, a recirculation
system 165 may be integrated with the EDI device 140. This feature may increase the
efficiency of the sanitization process. In an embodiment of the recirculation system
165, the discharge flowing through an outlet of the EDI device 140 is returned to an
inlet of the EDI device 140.
[025] In another alternate embodiment of the present invention, the EDI
device 140 may serve as the primary heat source tor sanitizing the water purification
system 100. For example, but not limiting of. the water exiting an outlet of the EDI
system 100 may be within the saniti/ation range. This water may be circulated
through components of the water purification system 100 which require sanitization.
[026] Depending on the size and complexity of the water purification system
100, the available heat torn the EDI device 40 may be inadequate to sanitize some
components. Here, the embodiments of the present invention may allow for
integration with a booster heater 170 or the like. This may comprise the form of a
preexisting external heat source, a new external heat source, or combination thereof
In use, the EDI device 140 may serve as the primary heat source and the booster
heater 170 as the secondary, which collectively operate to provide sufficient heat to
sanitize the components of the water purification system 100.
[027] FIG. 3 is a flowchart illustrating a method 300 of disinfecting an EDI
device, in accordance with an embodiment of the present inventio a The steps of the
method 300 may be performed manually; automatically via a control system, or the
like; or via a combination of manual and automatic steps. The following discussion
focuses on an application where the steps of the method 300 are automatically
performed via a control system, or the like.
[028] As will be appreciated, the present invention may be embodied as a
method, system, or computer program product. Accordingly, the present invention
may take the form of an entirely hardware embodiment, an entirely software
embodiment (including firmware, resident software, micro-code, etc.) or an
embodiment combining software and hardware aspects all generally referred to herein
as a "circuit", "module," or " system". Furthermore, the present invention may take
the form of a computer program product on a computer-usable storage medium
having computer-usable program code embodied in the medium. As used herein, the
terms "software" and "firmware" are interchangeable, and include any computer
program stored in memory for execution by a processor, including RAM memory,
ROM memory, EPROM memory, EEPROM memory, and non- volatile RAM
(NVRAM) memory. The above memory types are exemplary only, and are thus not
limiting as to the types of memory usable tor storage of a computer program. Any
suitable computer readable medium may be utilized.
[029] The computer- usable computer- readable medium may be, for
example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared,
or semiconductor system, apparatus, device, or propagation medium More specific
examples (a non exhaustive list) of the computer- readable medium would include the
following: an electrical connection having one or more wires, a portable computer
diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM),
an erasable programmable read-only memory (EPROM or Flash memory), an optical
fiber, a portable compact disc read-only memory (CD-ROM), an optical storage
device, a transmission media such as those supporting the Internet or an intranet, or a
magnetic storage device. Note that the computer-usable or computer- readable
medium could even be paper or another suitable medium upon which the program is
printed, as the program can be electronically captured, via, for instance, optical
scanning of the paper or other medium, then compiled, interpreted, or otherwise
processed in a suitable manner, if necessary, and then stored in a computer memory.
In the context of this document, a computer-usable or computer-readable medium
may be any medium that can contain, store, communicate, propagate, or transport the
program for use by or in connection with the instruction execution system, apparatus,
or device.
[030] The term processor, as used herein, refers to central processing units,
microprocessors, microcontrollers, reduced instruction set circuits (RISC), application
specific integrated circuits (ASIC), logic circuits, programmable logic controllers
(PLCs), and any other circuit or processor capable of executing the functions
described herein.
[031] Computer program code for carrying out operations of the present
invention may be written in an object oriented programming language such as Java7,
Smalltalk or C++, or the like. However, the computer program code for carrying out
operations of the present invention may also be written in conventional procedural
programming languages, such as the "C" programming language, or a similar
language. The program code may execute entirely on the user's computer, partly on
the user's computer, as a stand-alone software package, partly on the user's computer
R
and partly o a remote computer or entirely on the remote computer. In the latter
scenario, the remote computer may be connected to the user's computer through a
local area network (LAN) or a wide area network (WAN), or the connection may be
made to an external computer (for example, through the Internet using an Internet
Service Provider).
[032] The present invention is described below with reference to flowchart
illustrations and/or block diagrams of methods, apparatuses (systems) and computer
program products according to embodiments of the invention It will be understood
that each block of the flowchart illustrations and/or block diagrams, and combinations
of blocks in the flowchart illustrations and/or block diagrams, can be implemented by
computer program instructions. These computer program instructions may be
provided to a processor of a public purpose computer, special purpose computer, or
other programmable data processing apparatus to produce a machine, such that the
instructions, which execute via the processor of the computer or other programmable
data processing apparatus, create means for implementing the iunctions/acts specified
in the flowchart and/or block diagram block or blocks.
[033] These computer program instructions may also be stored in a
computer- readable memory. These instructions can direct a computer or other
programmable data processing apparatus to function in a particular manner. This is
such that the instructions stored in the computer-readable memory produce an article
of manufacture including instruction means which implement the iunction/act
specified in the flowchart and/or block diagram block or blocks. The computer
program instructions may also be loaded onto a computer or other programmable data
processing apparatus. These instructions may cause a series of operational steps to be
performed on the computer or other programmable apparatus to produce a computer
implemented process. Here, the instructions, which execute on the computer or other
programmable apparatus, provide steps or implementing the lunctions/acts specified
in the flowchart and/or block diagram blocks.
[034] In step 305, the method 300 may have determined that a sanitization of
the EDI device is required. There are many ways to determine when the EDI device
requires sanitization These include, but are not limited to, a time interval, schedule,
of the like; or measuring the level of bioactivity in the water purification system; or a
decrease in performance; or inspection of EDI device components.
[035] Referring again to FIG. 3, in step 310, the method 300 may isolate the
fluid supply to the EDI device. Here an isolation valve, or the like, may be modulated
in a manner that restricts the flow of fluid into the EDI device.
[036] In step 15. the method 300 may start the sanitization process. Here,
the EDI device may be substantially drained of fluid present within the internal
chamber. Then, an electrical supply device provides electrical power across the anode
and cathode compartments of the internal chamber. The electrical power is controlled
such that the temperature within the internal chamber reaches a sanitization range.
Here, the electrical power may b e in the form of current flowing through the
components of the internal chamber. In an embodiment the present invention, the
magnitude of the current may have a range of up to about 20 milliamperes per squared
centimeter.
[037] In step 320, the method 300 may determine whether the temperature
within the internal chamber is within a sanitization range. In an embodiment of the
present invention, temperature rise within the internal chamber may b e from about
120 degrees Fahrenheit to about 212 degrees Fahrenheit. Embodiments of the present
invention may use a temperature device to determine the temperature within the
internal chamber; as described. If the temperature is within the sanitization range,
then the method 300 may proceed to step 325; otherwise the method 300 may revert
to step 3 15 where the electrical supply device may be controlled in a manner that
increases the temperature of the internal chamber.
[038] In step 325, the method 300 may begin a sanitization hold, which may
be considered a soak time, or the like. The length of the sanitization hold may relate,
in part, to the sanitization temperature. A higher sanitization temperature may require
a shorter hold time, and vice- versa. In an embodiment of the present invention the
hold time may comprise a range of from about one hour to about six hours.
[039] In step 330, the method 300 may determine whether a sanitization hold
is complete. Here, the method 300 may determine if the hold time has elapsed. If the
sanitization hold is complete, then the method may proceed to step 335; otherwise the
method may revert to step 325.
[040] In step 335, the method may determine whether a water flush should
be performed. A flush may remove collected organic and inorganic impurities
produced during the sanitization from the EDI device. A flush may also cool the
components of the internal chamber. Generally, the flush may be performed until the
TOC discharge, discharge temperature, or discharge product resistivity is within an
acceptable range. If a flush is to be performed, then the method 300 may proceed to
step 340; otherwise the method may proceed to step 345.
[041] In step 340, the method 300 may perform the flush. The isolation
valve may be modulated to a position that allows fluid, such as, but not limiting of,
water, to enter the internal chamber. In an embodiment of the present invention a user
may determine the duration of flush. A user may also determine the physical
parameters (temperature, pressure, flowrate) of the fluid performing the flush.
[042] In step 345, the method 300 may b e considered complete. Here, the
water purification system may be ready for regular operation, or the like.
[043] The flowcharts and step diagrams in the FIGS, illustrate the
architecture, functionality, and operation of possible implementations of systems,
methods and computer program products according to various embodiments of the
present inventioa In this regard, each step in the flowchart or step diagrams may
represent a module, segment, or portion of code, which comprises one or more
executable instructions for implementing the specified logical iunction(s). It should
also be noted that, in some alternative implementations, the functions noted in the step
may occur out of the order noted in the figures. For example, two steps shown in
succession may, in fact, b e executed substantially concurrently, or the steps may
sometimes be executed in the reverse order, depending upon the iunctionality
involved. It will also be noted that each step of the block diagrams and/or flowchart
illustration, and combinations of steps in the block diagrams and/or flowchart
illustration, can b e implemented by special purpose hardware-based systems which
perform the specified functions or acts, or combinations of special purpose hardware
and computer instructions.
[044] As one of ordinary skill in the art will appreciate, the many varying
features and configurations described above in relation to the several exemplary
embodiments may be further selectively applied to form the other possible
embodiments of the present invention Those in the art will further understand that all
possible iterations of the present invention are not provided or discussed in detail
even though all combinations and possible embodiments embraced by the several
claims below or otherwise are intended to be part of the instant application. In
addition from the above description of several exemplary embodiments of the
invention, those skilled in the art will perceive improvements, changes, and
modifications. Such improvements, changes and modifications within the skill of the
art are also intended to be covered by the appended claims. Further, it should be
apparent that the fcregoing relates only to the described embodiments of the present
application and that numerous changes and modifications may be made herein
without departing from the spirit and scope of the application as defined by the
following claims and the equivalents thereof

CLAIMS
What is claimed is:
1. A method of sanitizing an electrodeionization (EDI) device, the method
comprising:
providing an EDI device comprising an internal chamber comprising: an
anode compartment adjacent a first end of the internal chamber, a cathode
compartment adjacent an opposite second end of the internal chamber, and a
plurality of ionic membranes positioned between the anode and the cathode
compartments;
stopping a fluid supply to the internal chamber;
supplying an electrical power across the anode and the cathode
compartments until a temperature within the internal chamber is within a
sanitization range; and
controlling the electrical power to maintain the temperature within the internal
chamber within a sanitization range;
wherein the electrical power sanitizes the EDI device while the fluid supply is
reduced.
2. The method of claim 1, wherein the step of controlling the electrical power to
maintain the temperature iurther comprises determining whether a sanitization
hold is complete.
3. The method of claim 2 iurther comprising the step of flushing the internal
chamber after the sanitization hold is complete.
11
4. The method of claim 1, wherein the step of supplying the electrical power
results in a temperature rise within the internal chamber of from about 120
degrees Fahrenheit to about 212 degrees Fahrenheit.
5. The method of claim 2, wherein an interval tor the sanitization hold comprises
a range of from about 5 minutes to about six hours.
6. The method of claim 1, wherein the electrical power comprises the form of
current flowing into the internal chamber.
7. The method of claim 6, wherein a current density comprises a range of up to
about 20 milliamperes per squared centimeter.
8. The method of claim 1 further comprising the step of a using a temperature
device to determine the temperature within the internal chamber.
9. The method of claim 8, wherein the temperature device is located within the
internal chamber; and detenriines the temperature within the internal chamber.
10. The method of claim 8, wherein the temperature device measures a
temperature of the fluid within the internal chamber.
1. The method of claim 8, wherein the temperature device is located external to
the internal chamber; and determines a skin temperature located on an external
surface of the EDI device.
12. The method of claim 6 further comprising monitoring a voltage of the EDI
device to determine if the internal chamber is within the sanitization range.
13. The method of claim 1 further comprising recirculating the fluid within the
chamber.
4 . The method of claim 1 tiirther comprising the step of providing a water
purification system configured for producing deionized water, the water
purification system comprising at least one of a micro -filtration apparatus, an
activated carbon tower, or a reverse osmosis apparatus; wherein the EDI
device is integrated within the water purification system.
15. A method of sanitizing an electrodeionization (EDI) device associated with a
deionized water producing system, the method comprising:
providing a water purification system configured for producing deionized
water, the water purification system comprising at least one of a microfiltration
apparatus, an activated carbon tower, or a reverse osmosis apparatus;
providing an EDI device, integrated with the water purification system,
wherein the EDI device comprises an internal chamber comprising: an anode
compartment adjacent a first end of the internal chamber, a cathode
compartment adjacent an opposite second end of the internal chamber, and a
plurality of ionic membranes positioned between the anode and the cathode
compartments;
modulating an isolation valve to stop a fluid supply to the internal chamber;
supplying an electrical power to the internal chamber to create a temperature
rise with the internal chamber;
determining whether a temperature within the internal chamber is witMn a
sanitization range; and
maintaining the temperature within the sanitization range;
wherein the electrical power sanitizes the EDI device while the fluid supply to
the internal chamber is substantially reduced.
16. The method of claim 15 ii rth r comprising the step of determining whether a
sanitizatio n hold is complete.
7. The method o f claim of claim 16 further comprising the step of flushing the
internal chamber after the sankization hold is complete.
18. The method of claim 15 iurther comprising the step of utilizing the EDI device
to sanitize the water purification system
19. The method of claim 18 forther comprising the steps of.
a. modulating the isolation valve to allow the fluid supply to flow into the
internal chamber;
b . discharging the fluid from the internal chamber; and
c. recirculating the fluid through the water purification system
20. The method of claim 19 fijrther comprising providing a booster heater to assist
with heating and maintaining the fluid supply to within the sanitization range.