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Патент USA US3074875

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Jan. 22, 1963
3,074,865
J. J. GAYSOWSKI
METHODS 0F AND APPARATUS FOR DEMINERALIZING RAW WATER
Filed May 18, 1959
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United States Patent Odtice
Patented dan. 22, i953
l
proved circulating system involving an ion exchange
35K/'4,865
METHÜBS 0F AND APPARATUS FDR BE
MliNERAHZiNG iii-iii’ WATER
Eoseph J. Gaysowslri, Chicago, iii., assigner to General
Electric Company, a corporation of New York
nina May is, rasa, ser. Nn. stessa
19 Ciainìs. (Cl. 26d-15B
treatment unit and a buifer tank so as to limit the de
generation of the ion exchange resin incorporated in a
system incident to a draw-,off of demineralized water
therefrom, so that the recovery time interval of the ion
exchange resin is reduced to a substantial minimum, and
further wherein an electrodialysis unit is provided in the
buffer tank selectively to remove anions therefrom to
increase the pH of the water prior to admission to the
The present invention relates to water demineralizing
methods and apparatus, and particularly to such methods 10 ion exchange unit, whereby to reduce corrosion in the
and apparatus employing an electrodialysis unit operable
circulating system.
to increase the pH of the treated water and a water treat
A further object of the invention is to provide an`i1n~
ment unit involving both ion exchange and electrodialysis.
proved method and apparatus of the character noted, in
it is a general object of the invention to provide an
cluding an electrodialysis unit associated with a hot Water
improved method and apparatus of the character noted, 15 storage tank and operable selectively to remove anions
employing electrodialysis and containing structure to pass
from the water Within the storage tank to decrease cor
a direct current whereby selectively to withdraw anions
rosion thereof.
from the Water being treated, so that the pH thereof is
A still further object of the invention is to provide
raised to minimize corrosion of the watern storage tank
in a method and apparatus of the character noted, au
and other metallic parts that come in contact with the 20 electrodialysis unit in combination with a hot water
treated water.
Another object of the invention is to provide in a water
storage tank a method and apparatus for selectively re
moving anions from the water therein, so as to raise the
heater, wherein an improved arrangement for applying
the operating current to the electrodialysis unit is pro
vided in combination with the heaters for the hot water
tank, whereby the electrodialysis unit is operated when
pH of the water and thus provide protection for mate 25 the heaters are operated.
riale which come into contact with the treated water.
Further features of the invention pertain to the par
A further object of the invention is to provide in a
ticular arrangements of the steps of the methods and of
method and apparatus of the character noted, an im
the elements of the apparatus whereby the above-outlined
proved arrangement for passing current through the elec
and additional operating features thereof are attained.
trodialysis cell so that the anolyte solution therein is 30
The invention both as to its organization and method
selectively iiushed and periodically removed and renewed
of operation, together with further objects and advan
in accordance with the concentration of the anions
tages thereof, will best be understood by reference to
therein, whereby to minimize the amount of treated water
the following specification taken in combination with t.e
utilized to hush the anolyte therefrom and to minimize
accompanying drawings in which:
back migration of removed anions from the eiectrodialysis 35
FEGURE l is a diagrammatic illustration of a water
cell into the treated water.
storage tank embodying the present invention and the
Another object of the invention is to provide an inn
control apparatus and circuits lfor controlling the opera
proved method and apparatus oi the character notedy
tion thereof, and in which the method of the present
employing a water treatment unit having therein an ion
invention is carried out; and
exchange resin bed characterized by both cation exchange
FIG. 2 is a diagrammatic illustration of a water de
centers and anion exchange centers, the water treatment
mineralizing apparatus embodying the present invention
unit containing structure to pass a direct current through
and the controi apparatus and circuits for controlling
the resin bed to regenerate the bed by means of electro
the operation thereof, and in which the method of the
dialysis, and an arransement for substantially matching
present invention is carried out.
the regenerating rates of the cation exchange centers and
At the outset, it is noted that the present invention is
the anion exchange centers, so that following a draw-ohc
predicated upon the discovery that in the storage of raw
of dcrnineralized water from the system, substantially
yacid waters, the pH thereof can be satisfactorily raised
equal recovery or regeneration of the cation exchange
by selectively removing the anions therefrom by means
centers and anion exchange centers takes place during a
of electrodialysis, the increase in the pH reducing the
given recovery time interval.
attack of the acid water upon metal parts in contact
Another object of the invention is to provide in a
therewith, and further when the pH is raised above 7
method and apparatus of the character noted, an im--
there is formed on the metal surfaces in contact there
proved arrangement of applying 'the regenerating current
with a further protective coating produced by precipita
to the resin bed so that the rates of degeneration of the
cation exchange centers and the anion exchange centers
thereof are substantially matched and so that the rates
tion of calcium and magnesium ions and more specifically
salts thereof on the metal surfaces. Only a relatively
small amount of anions need be extracted when treating
of regeneration thereof are substantially matched, with
most raw waters to obtain alkaline water and thus to
protect both the storage tank and the entire piping system
associated therewith.
change centers and the anion exchange centers are always
60
substantially equal in order to avoid changing the pH of
The present invention is further predicated upon the
the water passing through the demineralizing unit.
discovery that the performance characteristics of a water
A further object of the invention is to provide in a
demineralizing system embodying electrodemineralizing
the result that the regeneration states of the cation ex
method and apparatus of the character noted an im
proved arrangement for regenerating the ion exchange
resin, wherein the cation exchange centers and the anion
exchange centers have substantially equal total ion ex
change capacities in total grains of dissolved solids that
can be extracted from the raw water between regenera
apparatus involving both ion exchange and electrodialysis
can be drastically improved by applying the regenerating
current to the removal of anions substantially continu
ously while intermittently applying or varying the regen~
erating current to the removal of cations so that the re~
covery or regenerating rates of the anion and cation ex
tions of the bed.
change centers of the resins employed can be selectively
Another object of the invention is to provide in a 70 varied to obtain a substantial match therebetween, This
method and apparatus of the character noted, an im
improved method and apparatus taires advantage of the
3,074,865
peculiar recovery characteristics of the ion exchange resins
wherein the cations in general migrate at a faster rate
through the bed of ion exchange resin than do the anions
under the application of the same regenerating current
whereby in two comparable anion exchange `and cation
4
mineral salts supplying thereto such cations as:,Ca++,
Mg++, Fe++, Na+, K+, etc., and such anions as: HCOf,
894--, Cl“, C03-_, etc. Moreover, this raw water may
be quite hard and may have a total dissolved solids con
tent as high as about 70 grains per gallon (1200 p.p.m.).
exchange resins have approximately the same ion ex
In the operation of the system 1610, the raw water is de
change capacities and at substantially the same state of
mineralized, whereby the demineralized or treated water
delivered to lthe supply pipes 1353 and 222 has a total
dissolved solids content not in excess of 3 grains per
substantially faster than the anion exchange resin. As a
result the cation exchange resin has a relatively low ap 10 gallon (5l p.p.m.).
Fundamentally, the storage Itanlr 1111 comprises an
parent specific resistance and the anion exchange resin
outer cylindrical shell or body 1432 which may be formed
has a relatively high apparent specitic resistance, the ratio
preferably of hot rolled steel as are all other parts of
between the two specific resistances mentioned being
the tank 1%1, a bottom header 1%, and a top header'
about 1:2. Accordingly, following the unit degeneration
of the two resins and with the same direct voltage applied 15 104. The upper portion of the header 1114s has mounted
therein an electrodialysis unit 105 including a ceramicv
between the anodes and cathodes associated therewith,
chamber or wall 166 disposed within the tank 191 andthe regenerating current through the cation exchange
electrically insulated therefrom by an insulating gasket>
resin is about three times that through the anion ex
167 and cooperating with the header lit-i to form an
change resin, whereby to pass the required coulombs to
eiîect substantially equal regenerations of the two resins, 20 anolyte chamber 109. The ceramic chamber 1% is
porous whereby Water and ions therein can pass there
whereby approximately one unit of time is required for
regeneration, the cation exchange resin will be regenerated
regeneration of the cation exchange resin and approXi~
through, the chamber being formed for example of
porous aluminum silicate or porous aluminum oxide.
mately three units of time are required for regeneration
The ceramic chamber 166 will therefore be resistant to
of the anion exchange resin. Moreover, these time in
tervals become further disproportional in the event of 25 elevated temperatures when the tank 101 is also used as
the degeneration of the resins in excess of one unit, due
to the normal recovery rates of the resins; whereby the
state of generation of the cation exchange resin frequently
becomes substantially higher than that of the anion ex
change resin, in the event of an excess draw-orf oÍ de
mineralized water from the system, with the result that in
the subsequent draw-off “acid water” is obtained, as the
cation exchange resin is far more eiïective than the anion
exchange resin.
Now it has been discovered that the time interval re
quired to effect the complete regeneration of the cation
exchange centers in a bed can be substantially matched
a water heater, as will be explained hereafter, and the
chamber 106 is electrically non-conductive and further
is resistant to attack by acid solutions which will be
formed in the anolyte chamber 169 therein during opera
A plastic iitting or
cover 1638 is provided to close the upper end of the cham
ber 165, the cover 108 heilig formed of electrical insulat
30 tion of the electrodialysis unit 16S.
ing material and receiving therethrough and mounting
therein an anode 11d which may be formed of platinized
35 tungsten, titanium, or other suitable material.
Raw water to be treated is supplied to the bottom of
the tank 161 from the raw water supply pipe 12@ through
to> the »time interval required to eíîect the complete re
a check valve 12,1 and a connecting conduit 122, the check
valve 121 permitting flow only from the pipe 12€) into
generation of the anion exchange centers in the bed by
providing an anode in a body of anolyte contacting the 40 the conduit 122. Raw water is also supplied to flush
bed and a lirst cathode in a body of catholyte contacting
the anolyte and catholyte chambers of the treatment unit
the bed and a second cathode in the bed, and selectively '
201 as will be described more tully hereafter, raw Water
applying potential between the anode and the first and
being supplied for this purpose from the pipe 121B through
second cathodes, whereby the application of potential
a connecting conduit 123.
between the anode and the ñrst cathode nonconcurrently
with the application of potential between the anode and
the second cathode ei-lects substantial displacements both
of >sorbed anions from the bed into the anolyte and of
which delivers water to be treated to the treatment unit
291 for further treatment. rl`-he water within the tank
sorbed cations from the bed into the catholyte, and
whereby the application of potential between the anode
chamber 109 of the electrodialysis unit 165, the cover
ing the features of the present invention and in which
the method of the present invention is carried out, is
speciñcally designed for home use, and essentially com
prises a water storage tank 1F11, a treatment unit 201,
through the valve falls to another predetermined value.
The header 104 is provided with an outlet pipe 131
101 also is used to flush and renew the anolyte in the
10S being provided with a conduit 1li() having a solenoid
and the cathode either concurrently or nonconcurrently 50 valve 141 therein. communicating with a second conduit
with the application of potential between the anode and
142 that empties into the drain. The valve 141 is nor
the iirst cathode elîects substantial displacement only of
mally closed and is of the marginal type wherein the
sorbed anions from the bed into the anolyte.
solenoid is actuated to open the valve only when the cur
Referring now to FlGS. l and 2 of the drawings, the
rent through the solenoid coil rises to a predetermined
demineralizing apparatus there illustrated and embody
value and further the valve is closed when the current
The electrodialysis unit 105 is electrically operated and,
accordingly, the demineralizing system further comprises
a source of electrical power of 236 volts A.-C., single
a raw water supply pipe 12h, a first demineralized or 60 phase, three wire Edison system, including three conduc
treated water supply pipe 133, and a second deminer
tors 151, 152 and 153, the conductor 152 being grounded.
-alized or treated water supply pipe 222. The raw water
in the raw water supply pipe 12€) is under pressure and
is connected to the city Water main, not shown; while the
The conductor 151 connects with a switch 154 which
when positioned as illustrated by solid lines connects
the conductor 151 through a fuse 155 and a iixed resistor
tirst demineralized water supply pipe 133 is normally 65 156 to a variable resistor 157 having a wiper 158 in
connected through a ñrst manually operable supply valve
electrical contact therewith and movable therealong. The
132 to points of use requiring large Volumes of water but
demanding less highly demineralized water and the sec
wiper 1S8is connected by a conductor 159» to one ter
minal of the coil for the solenoid valve 141 and the
ond demineralized watery supply pipe 222 is normally
other terminal of the solenoid coil is connected by Va
connected through a second manually operable supply 70 conductor
16d to the input terminal of a rectiiier 161.
valve 225 to points ofv use requiring a smaller volume of
The
output
terminal of the rectiíier 161 provides a direct
demineralized water but demanding'highly demineralized
voltage which is applied by a conductor 162 to the anode
water, the points of use ordinarily being positioned in
11d disposed within the chamber 196, the rectiñer 161
the home but not being shown. The raw water in the
supply pipe 12% contains substantial amounts of dissolved 75 being poled so that a positive potential with respect to
5
ground potential is applied to the anode 110, the tank
6
fewer anions are present, the wiper 15S is adjusted to
provide more resistance in series with the rectifier 161
and conversely it the anion concentration is lower, then
101 being grounded by means of a conductor 152 con
nected to the header 103 thereof, whereby the tank serves
the wiper 153 is adjusted to remove resistance from the
as the cathode for the anode 110 of the electrodialysis
unit 105. In order to smooth the direct voltage applied Ul circuit and thus increase the current ilow through the
rectilìer 161 and through the eiectrodialysis unit 165'.
between the anode 110 and the tank 102, a capacitor 163
Since the total current utilized is small, there is substan
is provided and has one terminal thereof connected to the
tially no gas formation either at the anode 110 or on the
conductor 1e?. and the other terminal thereof connected
surface of the steel tank 101 which serves as a cathode.
by the conductor 164 to the tank 11%1 which is grounded
l0. Any gases such as oxygen or chlorine ‘which are formed
as has been explained above.
in the chamber 106 about the anode 110 will be tlushed
It will be seen therefore that the eleotrodialysis unit
out when the val-ve 141 is opened whereby to prevent mix
105 will have operating potentials applied thereto when
ing thereof with any hydrogen gas which may be formed
the switch 154i- is positioned to connect the fuse 155 to the
on the wall of the tank 1111, the hydrogen gas formed
conductor 151, the parts when so connected applying a
direct voltage between the anode 110 and the tank 101 15 tending to rise and be tlushed from the tank 101 through
the conduit 131 and the gases formed in the chamber 1%
through the porous chamber 106, the water within the
similarly rising to the top thereof and passing outwardly
tank 101 and within the chamber 106 serving as the elec
through a conduit 141?, whereby there will be no mixing
trolyte therefor. The applied voltage will cause migra
of hydrogen gas with the gases formed about the anode
tion of anions from the tank 101 through the wall of
the porous chamber 106 and into the body of anolyte 20 110.
lt further is contemplate-d that the tank 101 may be
109 disposed therein. The migration of anions from the
used as a water heater and to this end it is provided
body of water within the tank 101 into Ithe anolyte 109
with electric heating elements 101 and 1&2 that have been
will serve to raise the pH of the water within the tank
illustrated as being of the wrap-around typo. Electrical
101 since the anions therein are in effect replaced by
energy for operating the heating elements 151 and 132
hydroxyl ions, thus raising the pH thereof. As migra
is derived from the main conductors 151 and 153 through
tion of anions into the anolyte 109 proceeds, the pH of
fuses 183 and läßt connected to the input terminals of a
the water within the tank 101 will gradually rise, but
thermostatic switch 185, the switch 185 being provided
with the usual adjusting knob 186 whereby to adjust the
whereas the increased concentration of anions in the 30 operating temperature of the water heater. The output
terminals of the switch 185 are connected to conductors
anolyte 1&9 will substantially reduce the resistivity there
the speciiic resistivity `thereof may be slightly lowered
due to the replacement of the anions by hydroxyl ions,
of whereby to cause an increase in the ilow of current
between the anode 106 and the inner surface of the tank
187 and 153 which are in turn connected to the heating
elements 181 and 182 which are in parallel with each
other. The use of the electrodialysis unit 105 in the tank
1%1 serving as a cathode and ythus cause an increase
in current flow through the solenoid valve 141. When 35 101 has important `advantages when the tank 101 is a
water heater, since the heated acid waters have a greater
the current liow through the solenoid valve 141 reaches
corrosive eiiîect upon the tank 101 than do cold acid
a predetermined value, the valve 141 will be opened,
waters.
and since the water within the tank 101 is under pres
The switch 154 can be moved to the dashed line posi
sure because of the connection thereof to the supply
tion
of FIG. l whereby to connect the conductor 187 to
40
main, water from the tank 101 will gradually pass through
the fuse 155 whereby to provide the current for the
the openings in the porous chamber 106 at the rate of a
rectifier circuit supplying the anode 110 from the con
few drops per minute thereby to force anolyte therefrom
ductor 187. When the circuit is thus connected, the elec
via conduits 140 and 142 to the drain. Although the
trodialysis unit 105' is operated only when the thermo
passage of water through the ceramic chamber 106 is
static switch 185 is closed whereby to provide operating
slow, eventually suilicient water will pass so that the
potentials for the heating elements 1%1 and 1821. Nor
anolyte 109 will be substantially replaced whereby to in
mally the therinostatic switch 185 is closed after a draw
crease the resistivity thereof and thus reduce the current
oi’? of water from the tank 101 through the conduit 131
ñow between the anode 110 and the grounded tank 101
followed by the admission of cold raw water through
serving as a cathode. When the current flow is reduced
to a predetermined amount, the marginal solenoid valve 50 the conduit 122 into the bottom of the tank 101. Ac
cordingly, the electrodialysis unit 105 begins to operate
141 will close and will remain closed until the anion
concentration in the anolyte 1119 rises to a value such
as to conduct a current suñicient to operate the marginal
solenoid valve 141.
From the foregoing, it will be seen that the electro
dialysis cell 105 may be operated substantially continu
ously to remove the anions from the water within the tank
upon the addition of fresh cold acid water to the tank
101 since the addition of cold 4water thereto causes the
thermostatic switch 185 to operate whereby to close the
switch and to energize the heating elements 1&1 and 182.
T te electrodialysis unit 105 will continue to operate draw
ing anions into the anolyte 1%9 and thus raising the pH
of the Water within the tank 1il1 so long as the heating
elements 181 and 132 are operative and more particular
ly as long as the thermostatic switch 185' is closed. The
eration the pH of the water ‘nay rise to a pH of 7 or
highs whereby to provide a water which will not attack 60 variable resistor 157 can be adjusted so that the electro
.dialysis unit 105 during the heating period withdraws
or corrode the inner wall of the tank 101 and other parts
101. Removal of the anions from the water will raise
the pH ot the water and after a sufñcient period of op
in the demineralizing system. When the pH of the water
within the tank lill rises above 7, it has been found that
the walls of the tank 101 will become coated with deposits
oi compounds, for example, calcium carbonate or magne
sium hydroxide which further serve to protect the steel
tank 101 against corrosion upon subsequent addition of
acid water thereto since the acid water preferentially
dissolves the calcium carbonate and magnesium hydroxide 70
suflicient anions to provide corrosion protection, the orig
inal anion concentration in the cold raw water being
known.
The tank 101 further is useful as a buffer tank in
the water dernineralizing system when the treatment unit
201 is connected therein whereby to apply both ion ex
change and electrodialysis in the treatment of the raw
water whereby to provide a highly demineralized water
as an output from the system. Referring to FIG. 2 of the
drawings, it will be seen trat the treatment unit 201
comprises an outer shell 202, a pair of permeable dia
or other coating and does not attack or corrode the steel
tank
The variable resistor 157 has been provided so
phragrns 203 and 20d arranged within the outer shell
that the current ñow through the electrodialysis unit 105
202 and cooperating therewith to define an anolyte cham
can be adjusted to accommodate different anion concen
trations in the raw water in the supply pipe 120. If 75 ber 20S having a rod-like anode 206 therein and a cath
3,024.365
S
olyte chamber 207 having a rod-like cathode 26211 therein.
rl`he elements 2û2, 233 and 2nd are arranged in an up
usually preferred because of its high dissociation constant.
Normally the water in gel relationship with the polymer
standing position, the diaphragms 2113 and 2114i defining
should be present in an amount of at least 15% of the
therebetween a treatment chamber 210 which is provided
with a transverse apertured plate 2119 defining a connect
ing chamber 211 therebeiow. Disposed upon the aper
tured plate 2d@ is a porous mass of glass iibers 212 sup
porting thereon a porous ion exchange bed 215 (prefera
bly a synthetic organic polymeric exchange resin) accom
modating ready passage there through of the water under
going treatment. The resin in the bed is characterized
by both anion exchange centers and cation exchange
centers whereby to eilî'ect removal of both anions and
cations from water passing through the treatment cham
ber 21€». More particularly, the resin in the bed 215 may
comprise a single resin having a first type of chemical
groups therein defining cation exchange centers and a sec
ond type of chemical groups therein defining anions ex
weight of the dry resin.
whereby discrete particles of the two types of resins are
mineralized is supplied from the pipe 126) via the conduit
present, one of the resins being a cation exchange resin
and the other being an anion exchange resin. The two
122 into the lower portion of the tank 191 and thence
:Hows through the tank 1411 via the pipe 131 into the upper
resins may be intimately mixed whereby particles of anion
exchange resin are interspersed with particles of cation
portion of the treatment chamber 21€), and thence through
the porous resin bed 215 and thence into the collecting
exchange resin or alternatively the two resins may be
conñned to separate beds. Preferably the resin or resins
are chosen so that the bed 215 has substantially equal
chamber 211. The treated water further flows from the
Wat-er is supplied from the tank 101 through the con
duit 131 to the treatment unit 26:1 and particularly to
the upper portion of the treatment chamber 210 thereof.
An outlet conduit 220 is connected to the shell 202 and
communicates with the collection chamber 211 and is con
ilected to a iirst conduit 221 which conveys treated Water
back to the tank 101 and to the second conduit 222 which
conducts treated and highly demineralized water to the
point of use through the manually opera-ble control valve
225. The conduit 221 connects to the input side of a
circulating pump 170, the outlet of the pump 17u con
necting with a conduit 173 which is connected through a
check valve 173 to the inlet conduit 122 for the tank
101. The pump 171i is suitably driven ‘by an electrical
_pump motor 171 drivingly connected thereto. Accord
change centers. ln another preferred construction, the
bed 215 is formed of two separate and discrete resins 20 ingly, it will be understood that the raw water `to be de
cation and anion exchange capacities in total grains of
collecting chamber 211 through the conduits 220 and 221
to the pump 171i, and thence via the conduit 172 and the
check valve 173 to the inlet conduit 122 for the tank 101.
dissolved solids that may be removed from the water
If there is a demand for treated water, water also may flow
undergoing treatment.
from the collecting chamber 211 via the conduits 220 and
More particularly, when a separate and discrete anion
exchange resin is used with a separate and discrete cation
exchange resin, the anion exchange resin is of bead-like
formation and may comprise the strong base resins sold
under the names “Amberlite lRAeLlOO” and “Amberlite
IRA-4l0”; and this cation exchange resin is of bead-like
formation `and may comprise the strong-acid resin SOld
under the name “Amberlite lità-120.” An anion exchange
resin of the type specilied essentially comprises a stable in 110
222 and the valve 225 to a point of use or from the buffer
tank 101 via the conduits 131 and 133 and the valve 132
to another point of use. In the circulation of the water
exchange described above, it is demineralized; whereby
the demineralized Water is accumulated in the tank 1631
and the treatment unit 201 for dispensing through the out
let conduits 133 and 222 as require-d.
The anolyte chamber 20S and the catholyte chamber
21W are provided with apparatus to supply fresh anolyte
soluble synthetic organic polymer, active basic functional
and catholyte thereto; more particularly, raw water from
groups chemically bonded thereto and dissociable into
free mobile anions to impart a positive charge to the poly
mer, and water in gel relationship with the polymer. Simi
larly, a cation exchange resin of the type speciñed essen
the inlet pipe 120 is conveyed via the pipe 123 to the in
put side of a solenoid valve 226. The outlet side of the
tially comprises a stable insoluble synthetic organic poly
mer, active acidic functional groups chemically bonded
thereto and dissociable into free mobile cations to impart
a negative charge to the polymer, and Water in gel rela
tionship with the polymer. The active basic functional
solenoid valve 226 is connected to a conduit 227 which
is provided with a first outlet 223 for anolyte and a second
outlet 229 for catholyte. The lower portion of the anO
lyte chamber 205 communicates with an upstanding con
duit 231 extending upwardly through the anolyte cham
ber 265 and to the exterior of the outer shell 292 and is
provided on the upper end thereof with a funnel 232
groups attached to the associated organic polymer are
for receiving fresh anolyte from the outlet 22S for de
oriented with respect to the interfaces thereof so as to be
livery to the anolyte chamber 2135. Similarly, the lower
partially or completely dissociable in the internal gel Water
portion of the catholyte chamber 2117 connects with an
into fixed positive ions linked to the polymer and into
upstanding conduit 233 which extends through the upper
-mobile exchangeable negative ions, and similarly, the ac 55 portion ofthe outer shell 202 and is provided at the upper
tive acidic functional groups attached to the associated
end thereof with a funnel 234 cooperating with the outlet
organic polymer are oriented with respect to the interfaces
229 for delivery of catholyte into the catholyte chamber
thereof so as to be partially or completely dissociable in
297. Accordingly, raw water can be fed from the supply
pipe 120 via the conduits 123 `and 227 under the control
the polymer and into mobile exchangeable positive ions. 60 of the solenoid valve 226 and via the outlets 228» and 229
Typical such polymers to which active basic functional
into the funnels 232 and 234 to supply new anolyte and
groups may be attached include: urea-formaldehyde resins,
catholyte to the anolyte chamber 20S and the catholyte
melamine-formaldehyde resins, polyalkylene-polyamine
chamber 297, respectively. Upon the addition of new ano
formaldehyde resins, and the like; and such suitable active
lyte tothe anolyte chamber 2115, the excess anolyte ilows
lbasic functional groups include: quaternary ammonium
through a conduit 235 communicating with the upper por
the internal gel water into iixed negative ions linked ’to
hydroxides, amino groups, the guanidyl group, »the di
' tionof the anolyte chamber 2595, the conduit 235 com
cyanodiamidine group, and like organic nitrogen-contain
municating with the drain. A similar overliow conduit
ing basic groups; the quaternary ammonium hydroxide
236 is provided for the catholyte chamber 207 and com
municates with the upper portion thereof, the conduit 235
groups, the, guanidyl and dicyanodiamidine residue being
usually preferred because of their high dissociation con 70 also communicating with the drain. The conduits 235
and 235 serve to regulate the maximum amount of anolyte
tents. Typical such polymers to which active acidic func
and catholyte present in the anolyte chamber 2115 and
tional groups may b_e attached include: phenol-aldehyde
resins, polystyrene-divinylbenzene copolymers, and the
the catholyte chamber 207, respectively.
like; and such suitable active acidic functional groups in~
The treatment unit 261 is supplied with operating po-`
clude: _80311, -.-COOH, and the like; »_SOal-I íbeing
y tentials from a rectifier 240 which has the input terminals
3,074,865"
ii
tion of cations from the resins 225 into the catholyte
thereof connected to the main supply conductors 151 and
chamber 267 or even to cause back diffusion ot cations
253. The negative output terminal of the rectifier 2d@
-from the catholyte chamber 267 into the treatment cham
is connected to ground through the conducto-r E52 and is
er 21h or alternatively to cause a rate of migration of
further connected to the upper end of the cathode 29h51
by two parallel circuits. The ñrst circuit includes a C91 cation-s equal to that of the anions. To this end a sec
ond cathode 2Mb is provided for the treatment unit 261
normally closed switch 255e interconnecting the con
and is positioned in the treatment chamber 21S and dis
ductor 152 and a variable resistor 256111 having a mov
posed toward the diaphragm 2M» which forms a common
able contact 25751 thereon selectively shorting out a por
wail between the treatment chamber 210 and the catholyte
tion of the resistance but normally being positioned to
short out all of the resistance of the resistor 256e as
illustrated in PEG 2. A conductor 252a connects the
resistor 256e to the upper end of the cathode 22861. The
second parallel circuit is from the conductor .1152 through
a pair of normally closed switch contacts 251:1 to a con
ductor 25h11 which connects to one end of a variable re
sistor 25311. ri`he variable resistor 25541 is provided with
a movable contact 251m making electrical connection
therewith and connected to short out selected portions
of the resistance or the resistor
and, more particu~
chamber 267.
The timer motor 242 further drives a
third switch actuating cam 250 controlling a switch 251
having a pair of normally ‘biased closed contacts 25111
and a pair of normally biased open contacts 252]).
When the cam 250 is in the position illustrated in FiG. 2,
the contacts 251a are closed whereby to connect the
ground potential on the conductor 152 to the cathode
Ziiâia via the conductor 25801, the resistor 253e and the
by-pass contact 254@ When the cam 25d is in the po
sition to close the switch contacts 25112, the switch con
larly, is connected to the conductor 252a whereby to 20 tacts 25151 are open and a connection is made from the
conductor E52 through the switch contacts 25117 via a
form a connection with the cathode 298:1. Normally
conductor 258e, a resistor 25341 having a movable contact
the resistor 253 is completely shorted out as illustrated
in FIG. 2.
2545.1, and the conductor 252a to the upper end of the
The demineraiizing system 2% further comprises a
timer motor 242 of »the synchronous type and bridged
across the conductors 252 and 25?». Preferably the timer
motor 242 is of the “Teiechron” type and comprises an
output shaft 2033 having a iirst switch actuating cam 244
cathode 2G31), whereby ground potential is applied to
both the cathode 29851 and the cathode Ztläb when the
switch 25511 is in its normally closed position so that
there is no driving potential between the cathodes Ziläa
and Ztiiib, the anode 2% in effect operating only in co
operation with the cathode 228k. As a result there will
driven thereby Íor controlling the opening and closing of
a switch 245. The switch 245 is biased open and when 30 be no migration of cations from the resin bed 215 into
the catholyte chamber 2ti7 but.l there will be movement
closed by the cam 241i» connects the conductor 252 'to a
of anions from the resin bed 225 into the anolyte chamber
conductor 246 whereby to apply electrical energy to the
206 in the usual manner. As has been explained above,
pump motor 17]. which has the other input terminal
the cation exchange centers or resins are more readily
thereof grounded through the conductor i152. A second
regenerated than the anion exchange centers or resins
switch actuating cam 25a-7 is driven by the timer motor
whereby the cation exchange resin may be said to have
shaft 243 and controls a normally biased open switch
a higher »rate of regeneration, assuming that the anion
245. When the cam 247 is in position to close the switch
and cation resins are at a similar state of generation.
24S, the switch connects the conductor 315i to a con
The above described method of operation of the system
ductor 249 connected to one of the input terminals of
the solenoid valve 226 being grounded through the con
therefore continuously regenerates the anion exchange
ductor i572.
resin at a predetermined rate, and periodically applies
potentials to cause regeneration of the cation exchange
resin at a rate higher than that of the anion exchange
In view of the foregoing, it will be understood that in
the operation of the demineralizing system, the timer
motor 222 periodically closes and later opens the switch
245, whereby the electric drive motor l'ïi is periodically
operated to eiïect operation of the pump 17h, with the
result that the water undergoing treatment is circulated
from the treatment chamber 22€? of the treatment unit
261 and through the tank lili and then back to the treat
ment chamber 2id; whereby the circulated water is de
mineralized as previously noted. Also, in the operation
of the demineralizing system, the timer motor 242 pe
riodically closes and later opens the switch 222, whereby
resin and at other times at a rate lower than that of the
anion exchange resin, the latter rate being substantially
zero, whereby to achieve substantially equal regenera
tion of the cation exchange resin and the anion exchange
resin by proper arrangement of the switch actuating cam
250.
in another preferred method of operation of the treat
ment unit 203i, the cathode 262i: is connected to the
rectiñer 24o continuously. To this end the conductor
152 is connected through a normally open switch 255b
the solenoid of the valve 226 is correspondingly ener
to one end of a resistor 256b having a movable contact
gized and later deenergized periodically. When the sole
noid of the valve 22:6 is thus energized, the Valve 225 is
operated from its closed position into its open position
25717 thereon normally to short out a portion of the
resistance thereof, the other end of the resistor 256!) be
ing connected to the conductor 252b. Accordingly, when
the switch 255]) is closed, some potential slightly positive
so as to supply water through the conduit 227 to be used
with respect to ground is applied to the cathode 298i; con
as fresh anolyte from the outlet 22S via the funnel 232
and the conduit 231, and further to supply water as fresh 60 tinuously. The operation of the cam 25h may apply
catholyte from the conduit 227 via the outlet 229 into
the funnel 234 and the conduit 233 and thus into the
catholyte chamber 227. When the fresh anolyte is thus
ground potential to the cathode 2Mb by the contacts
25M) or some other potential can be applied or even
the same potential by properly adjusting the shorting c011
tact 251th along the resistor 253b.
In View of the foregoing, it will be understood that in
is displaced therefrom and flows via the conduit 235 to 65
the operation of the system Íliitl, the tank wl may be
the drain (not shown); and likewise when fresh catholyte
is thus supplied into the catholyte chamber 267 the
used as a water storage tank, the switch £54 being posi
tioned to connect the conductor §51 to the fuse 155
catholyte therein is displaced therefrom and iiows via
whereby to operate the electrodialysis unit 105 directly
the conduit 236 to the drain.
supplied into the anolyte chamber 295, the anolyte therein
During the operation of the treatment unit 291 in ac 70 from the supply line 151. When the system is so oper
ated, raw Water which may have a substantial acid con
cordance with the present invention it is desirable to
tent indicating an excess or' anions therein as compared to
apply an operating potential thereto in a manner such
as to cause a substantially constant rate of migration of
the cations therein will be obtained from the supply pipe
anions from the resin 2î5 into the anolyte chamber 295
22€? under pressure to the conduit 222 and via the diffuser
and to cause alternately lesser and greater rates of migra 75 130 into the bottom' of the tank Mii. The electrodialysis
annees
12
'n «
unit 1135 will operate to draw anions from the body of
water inthe tank 101 through the porous ceramic cham
ber 106 into the anolyte 1w thereof, the anolyte 169 be
coming increasingly more acid during operation while
the water within the tank 1il1 becomes less acid, the pH
rising to a value above pl-I 7. Further protection for the
storage tank or as both a storage tank and a water heat
er. The tank 161 when used in combination with the
treatment unit 261 to provide highly demineralized water
serves as a buffer tank in the System.
In the operation
of the demineralizing system, the timer motor 242 pe
riodically closes and later opens the switch 2li-5, whereby
the electric drive motor 1"/1 is correspondingly periodi
walls of the tank 101 is provided by the fact that if cal- ì
cally operated to effect corresponding operation of the
cium, magnesium and carbonate ions are present in the
pump 17d with the result that the water undergoing
raw water, a further protective coating of calcium car
bonate and magnesium hydroxide will be formed on the 10 treatment is circulated from the treatment chamber 210 of
the treatment unit 291 and through the buffer tank 1491
inner wall of the tank 101 whereby partially to neutralize
and thus back to the treatment unit 21d whereby the cir
fresh acid raw water as it is introduced into the bottom of
culated ywater is demineralized as previously noted. Also
the tank 101. Eventually the ion concentration in the
in the operation of the demineralizing system, the timer
anolyte 199 will rise’to a value such that the current flow
motor 242 periodically closes and later opens the switch
between the anode 110 and the wall of the tank 161
243, whereby the solenoid of the valve 226 is correspond
acting as a cathode will be sufficient such that the ñow
ingly energized and later deenergized periodically. When
of current through the solenoid of the valve 141 will be
the solenoid of the valve 226 is thus energized, the Valve
enough to open the normally closed valve 141 and thus
226 is operated from its closed position into its open po
permit seepage of water into the anolyte 109, the excess
sition so as to supply water as fresh anolyte from the con
anolyte overflowing through the conduit 1d@ via the con
duit 227 via the conduit 228 into the funnel 232 and
duit 142 to the drain. ln a practical system, the flow
thus into the anolyte chamber 265; fresh catholyte is like
rate through the anolyte 1il9 is only a few drops per min
wise provided on the opening of the solenoid valve 226
ute which is suil‘lcient to reduce the ion concentration in
from the conduit 227 via the conduit 229 into the fun
the anolyte 109 but is not suiiicient seriously to decrease
nel 234 and thus into the catholyte chamber 2%’7 of the
the water in the tank 1tl1. When the ion concentration
treatment unit 201. When fresh anolyte is supplied to
in the anolyte 109 has fallen to a predetermined value,
the anolyte chamber 295, the anolyte therein is displaced
the current flowing through the solenoid of the valve 141
therefrom and flows via the conduit 235 to the drain; and
will be too low to hold the valve open and therefore
likewise when fresh catholyte is supplied to the catholyte
the valve will close whereby to interrupt the flow of fresh
anolyte through the porous chamber wall 166. Any 30 chamber 207, the catholyte therein is displaced therefrom
and flows via the conduit 236 to the drain.
gases formed at the anode or at the cathode will be
When the valve 225 is opened, the demineralized wa
hushed from the tank 101 without coming into contact,
ter flows from the conduit 222, while raw water from the
the anode gases being flushed to the drain by the `con
supply pipe 12@ is supplied via the conduit 122 into the
duits 14d and 142 and the cathode gases passing through
bottom of the buffer tank 1M and forces the previously
the conduit 131 to the first outlet pipe 133 via the valve
demineralized water therefrom through the treatment unit
132.
291 and into the demineralized Water supply pipe 222.
The tank 161 can also be operated as a hot water
In the arrangement, when demineralized water is drawn
storage tank by applying heating potential from the con
off from the conduit 222, raw water is supplied t-o the
ductors 151 and 153 through the thermostatic switch 185
to the heating elements 181 and 182. The electrodialysis 40 bottom of the buffer tank 161 and mixes with the previ
ously demineralized water therein so that a substantial
unit 105 may be utilized as described above, the operating
dilution of the raw water takes place, and thereafter the
current therefor being obtained directly from the conduc
mixed water is pumped in the local loop circuit from the
tor 151 by placing the switch 154 in position to connect
treatment unit 261 into the buffer tank 1011 back to the
the conductor 151 and the fuse 155. Alternatively the
switch 15d may be positioned to connect the conductor 45 treatment unit 2i?1 and through the ion exchange bed
215 so as to effect dornineralization of the mixed water
187 to the fuse 155 whereby the electrodialysis unit 165
is operated only when the heating elements 181 and 182
are operated. In this arrangement, a draw-od of heat
ed alkaline water from the tank 101 through the conduit
131 via the valve 132 and the outlet 133 will cause the
introduction of cold raw acid water from the supply pipe
120 to the bottom of the tank 1111. The thermostatic
switch 185 will sense the condition of the cold water
in the bottom thereof to close the switch and apply oper
ating potential to the conductors 187 and 1&5. Accord
ingly, the heating elements 181 and 182 will begin to
and the corresponding degeneration of the ion `exchange
bed 215.
After the draw-off from the system, and as
time proceeds, the ion exchange bed 215 is regenerated
by virtue of the application of the potential between the
anode 206 and the cathodes
and ZtlSb. Specifically,
the bed 215 is regenerated with the exchange of the
sorbed anions and cations of the mineral salts for hy
droXyl ions and hydrogen ions and with the migration of
the anions of the mineral salts through the diaphragm
263 into the anolyte contained in the anolyte chamber 205
unit 105 which will be operated since the thermostatic
and with the migration of the cations of the mineral
salts through the diaphragm 20d into the catholyte con
tained in thecatholyte chamber 267. The anions and the
cations are subsequently îlushed along with the anolyte
and catholyte from the respective chambers 295 and 2li?
switch 1155 has been closed. The resistor 157 can be ad
justed with knowledge of the anion content of the raw
water and the temperature thereof so that the required
the water, the anions being flushed to the drain via the
operate to heat the water within the tank 101. The in
troduction of the raw water into the tank 101 will also
raise the anion content of the water in the tank; these
excess anions will then be removed by the electrodialysis 60
amount of anions will be removed by the electrodialysis
unit 105 during the time that the thermostatic switch 155
is closed i.e. during the time that it is required to
operate the lheating elements 181 and 132 whereby to
and are ultimately carried into the drain. The electro
dialysis unit 165 further serves to remove anions from
conduits 14d and 142 as has been described above.
raise the temperature of the water in the tank lill to the
In the system the conduits 131, 22h”, 221 and 222, or
at least appropriate sections thereof, are formed of i11
sulating material in order to minimize stray electric cur
rents therebetween by virtue of the fact that the potential
ter being either- heated or unheated as the case may be
ment unit lill is provided with a mixed resin bed 215
desired operating temperature therefor.
70 with respect to ground potential in the upper portion of
the treatment unit Zilli may be substantially different
The demineralizing system can further be operated to
from that in the bottom of the treatment unit 201.
combine ion exchange with electrodialysis whereby to pro
ln a constructional example ofthe system ìtlil, the treat
vide substantially completely demineralized water, the wa
depending upon whether the tank 191 is operated as a 75 containing separate and discrete anion exchange resin par
:nordsee
13V
ticles and separate and discrete cation exchange resin
particles, the two resins having equal volumes and con
taining equal volumes of resin, and may, for example, con
tain one cubic foot or" the appropriate resin. Moreover,
in the demineralizing system, the water pressure in the
treatment unit Zul should not be in excess of 45 p.s.i.
When the resin beds are fully regenerated and a draw-oil:`
of demineralized water from the supply pipe 222 is ef
fected, the resins are degenerated by substantially equal
amounts, whereby it is desirable that the rates of recov
ery or regeneration of the resins should be equal in the
time interval immediately following the draw-oil of de
mineralized water from the conduit 222,; and this can
be acc mplished by matching the regeneration or recov
ery rates of the resins. Speciíically, in order to obtain
this objective in accordance with one preferred method of
14
of operating potential to the cathodes 208e and Ztlâib can
be adjusted so that the total cation regeneration will
equal the total anion regeneration over a period or" time,
‘Jhen no potential is applied to the cathode 29de and
ground potential is applied to the cathode 2Mb, there
will be back migration or diffusion of cation from the
catholyte chamber Ztl? into the treatment chamber 2li)
whereby further to reduce the cation regeneration rate
as compared to the case wherein ground potential is ap
plied concurrently to both the cathodes Ztlâa and 266]).
In a third preferred method of operating the treatment
unit Zilil, both the switches 2550.' and 25512 are placed in
the closed positions thereof and the resistors 253g and
253b are adjusted so that the maximum resistance is pre
operating the Vsystem lili), the anion exchange resin -is
sented thereby, the resistance values of the resistors 253e
and 253i) being suiliciently high «that they present a sub
stantially open circuit condition even when connected
preferably maintained under a substantially constant op
through the switch contact-s 25151 or 251th to the con
ductor 152. Operating potential will now be concurrently
regeneration thereof. At the same time the regeneration 20 applied to both the cathode Zdâa and the cathode Zil‘ßb
erating potential whereby to effect substantially constant
rate of the cation exchange resin is varied and is selec
tively alternately changed between a iirst constant regen
and the values of the potentials applied thereto can be
eration rate substantially higher than the regeneration rate
of the anion exchange resin andy a second lower regen
the rate of cation extraction Vfrom the bed 215.5 will be
equal to the rate of anion extraction from the bed 2id.
Thus by suitably adjusting the Values of the resistors 256:1
and 256!) in the circuit, the total anion extraction can be
matched with the total cation extraction for continuous
operation of the treatment unit 25M.
It is further pointed out that in any of the three meth
30 ods of operating the treatment unit Ztll described above,
eration rate which is substantially less than the regenera
tion rate of the anion exchange resin, the second rate be
ing essentially zero, whereby over a suitable period of
time the total regeneration of the cation exchange resin
substantially matches that of the total regeneration of
the anion exchange resin.v rl`he above described method
is achieved by operating the system lilo with the switch
255e closed, the switch 255% open and the resistors 25341,
253!) and 256e completely shorted out, all as is illustrated
in FiG. Z of the drawings. With the parts so connected
and adjusted, the first regeneration rate of the cation ex
adjusted by means of the resistors 256e and 25627 so that
the various adjustable resistors 253e, 25311, 2565i and
25e!) can be adjusted to obtain the optimum operating
characteristics for the treatment unit Zilli.
in the overall operation of the system to demineralize
Water, the electrodialysis cell idle' will remove a certain
portion of the anions from the raw water and the remain
ing anions extracted from the water will be removed by
voltage between the cathode 263e disposed in the catho
the anion exchange resin in the treatment unit ìtlîl. All
lyte chamber Ztl?" and the anode Bilo. The lower regen
of the cations removed during the demineralization `of the
eration rate of the cation exchange resin is obtained by
closing the switch contacts 25M whereby to place the 40 water will be removed by the cation exchange resin in the
treatment chamber 2li), The regeneration of the cation
cathode Zíi'íëb disposed in the treatment chamber 2li? in
exchange resin can be adjusted by suitable operation of
the circuit in parallel with the cathode tibo. There will
the cam 259 in cooperation with the switch contacts 25M:
be no driving potential between the resin
in the treat
whereby the removal of the anions by the anion exchange
ment chamber 2li? and the catholyte in the catholyte
resin and the removal of cations by the cation exchange
chamber 267 so that substantially no regeneration of the
resin will be balanced to obtain an output from the treat
cation exchange resin is obtained and there will be sub
ment unit Zti‘l in the supply conduit 222 which has sub
stantially no passage of cations through the diaphragm
stantially the pH of the water entering the treatment unit
21% from the treatment chamber Zilli into the catholyte
Edil through the conduit E31, whereby the demineralized
chamber 267 or from the catholyte chamber Zi?? into the
change resin is obtained by applying the full operating
treatment chamber 2id.
The total time of concurrent
application oi‘ operating potential to the cathodes Ztl'dcz
and Zëtìt': will be chosen with respect to the nonconcurrent
operation thereof so that the total cation extraction from
the resin 21.5 will equal the total anion extraction there
from during' a complete cycle of operation of the treat
nient unit.
in a second preferred method oi operating the treat
water from the outlet conduit 222 will be neutral or
slightly `alkaline and substantially the same pH as the
water entering the treatment unit Zbl from «the conduit
§31.
Further, in a practical installation, the ñrst outlet con
duit i3d: would be connected to points requiring large
volumes of water at which fully demineralized water is
not necessarily required such as in a shower or a bath
tub, whereas the second demineralized water'outlet con
ment unit Zul to achieve substantially equal regeneration
duit 222 would be connected to those points of use which
of the anion exchange centers and the cation exchange
centers in the resin 215, both the switches 255e and 255'!) 60 require highly demineralized water and generally in lower
volumes such -as dish washers, clothes washers, and the
like. Accordingly a large sustained draw-off such as dur
ing a shower will cause dernineralized water in the butler
tank. lill to be drawn into the conduit 131 and to the
trol cam Z50. Vv’hen the switch contacts Zilla are closed,
ground potential will be applied from the conductor i152 65 point of use via the valve i222 and the conduit §33. At
the beginning of the draw-od the water will be substan
to the cathode Eutin, whereby to obtain a iirst high regen
tially fully demineralized but in the course of a long
eration rate of the cation exchange resin. Thereafter the
cam 239 will operate to open the switch contacts 25141
sustained draw-oil, the water will become progressively
are placed in their respective open positions so that po
tential will be applied alternately or nonconcurrently
to the cathodes .iiSn and Eltiâlb by operation of the con
and to close the switch contacts 25E!) thereby removing
less highly demineralized and eventually substantially raw
ground potential from the cathode Edda and applying 70 water will issue from the output conduit i153. The pas
ground potential from the conductor l5?, to the cathode
sage of such water having a high mineral content directly
Èíiâb. This will provide a second regeneration rate of
through the treatment unit Zbl would rapidly exhaust
the cation exchange centers which will be less than the
the unit Zul and further would place the resins therein in
regeneration rate of the anion exchange centers. By
such a condition that it would require a substantial period
proper shaping of the cam 525i?, the time of application 75 of time to eñect any substantial regeneration thereof by
3,074,865
15
the application of the regenerating potential between the
What is claimed is:
y
tank, an inlet pipe adapted to contain raw water under
pressure and connected -to the bottom of said butter tank,
an electrolytic cell including structure defining a treat
nient compartment and a catholyte compartment and an
treatment unit 29j. is reserved for those points of use
which do require highly demineralized Water, those points
anoly-te compartment with a lirst ion permeable dia
of use being connected to the second outlet conduit 222.
phragm »as >a 4common wall between said treatment com
‘lt is to be understood in the above description of the
partment and said catholyte compartment and with a
second ion permeable diaphragm as a common wall be
tween said treatment compartment and said anolyte com
partment, said electrolytic cell also including a cathode in
said catholyte compantment and an anode in said anolyte
system when utilizing both ion exchange and electro
dialysis to demineralize the water, the butter tank itil
may also be utilized as a water heater, whereby to supply
hot demineralized water to the outlet conduits 133 and
222. Further, the switch i54- may be placed in either of
compartment, means for supplying raw water as a catho
the positions thereof whereby either to operate the elec
trodialysis unit 105 continuously or to operate the electro
alysis unit îtlS only when the heating elements lßl and
and for supplying raw water as an aiiolyte from said in
i552 are operated.
let pipe into said anolyte compartment, -a bed or" ion ex
lyte from said inlet pipe into said catholyte compartment
change material arranged in said treatment compartment
Recapitulating: in the system of the present invention,
and including both cation exchange centers and anion ex
the storage tank for the water is protected from attack by
acid raw waters by employing `therein an electrodialysis
unit which preferentially removes anions from the water
to raise the pH thereof and also when the pH rises above
7 »to deposit a protective coating of basic salts on the walls
oi the tank, the salts reacting with subsequently added
raw water to raise the pH thereof. When producing fully
demineralized water using the system of the present in
vention, the water to be demineralized is íirst introduced
,
l. Apparatus for demineralizing raw water containing
dissolved metal salts; said apparatus comprising a buffer
anode 2% and the cathode 20S. By selectively connect
ing the points of use requiring large sustained draw-olîs
and not requiring highly demineralized water to the iirst
outlet conduit 133, the demirieralization capacities of the
change centers, a Íirst conduit connecting the top of said
buffer tank and >the top of said treatment compartment, a
second conduit connecting the bottom 0E said treatment
compartment and the bottom of said butter tank, a pump
25
included in said second conduit and operative to eiîect
local circulation of water from the bottom of said treat
nient chamber via said second conduit into the bottom of
said buiîer tank .and from the top of said butter tank via
into the buffer tank containing previously demineralized
said tirst conduit into the top of said treatment chamber,
water so that it i-s substantially diluted; and the resulting
mixed Water is circulated in local loop circuits from 4the
whereby the circulated water proceedsV upwardly through
buñer tank to `an ion exchange bed and back to the buiì‘er
tank. The cation exchange resin and the anion exchange
resin in the bed are regenerated by like amounts at equal
average rates; more speciñcally, the anion exchange resin
is regenerated at a predetermined rate and the cation ex
change resin is regenerated 4at the same rate or is alter
said buffer tank «and downwardly through said treatment
chamber and whereby the circulated water is demineral
ized by said bed with the resulting degeneration thereof,
means for applying a potential between said anode and
said cathode to cause displacement of sorbed cations from
said bed Ithrough said first diaphragm into the catholyte in
said catholyte compartment `and to cause displacement of
sorbed anions nom said bed through said second dia
nately regenerated at a lirst ratel relatively higher than
phragm into the anolyte in said anolyte compartment with
the predetermined rate of the anion exchange resin and at
a second rate substantially lower than the predetermined 40 the resulting regeneration ‘of said bed, a íirst drawoiî con
duit connected to the bottom of said treatment compart
rate or” the anion exchange resin, the second regeneration
ment, a first di'awotl valve included in said first drawolî
rate being in one preferred method of operation substan
conduit, whereby opening of said lii‘st di'awoiî valve
tially zero, so that the total regeneration of the anion ex
change resin substantially matches the total regeneration
elteets the l’iow of raw water from said inlet pipe into the
bottom oi' said butter tank and the consequent flow of
of the cation exchange resin. The control of the regen
eration rate of the cation exchange resin is accomplished
water through said buffer tank via said first conduit into
the top of said treatment compartment and therethrough
by increasing the effective resistance through the bed
which is in turn achieved by placing a second cathode in
and through said bed into said first drawotï conduit and
the bed adjacent to the catholyte chamber whereby to
therefrom to the exterior with the result that both the
modify the force moving cations from the resin bed into 50 storage capacity or” said Ibutter tank and the demineralizing
the catholyte chamber. The supply of adequate amounts
capacity of said bed may be employed Vin supplying a de
of highly demineralized water to those points requiring
mand for demineralized water from said ñrst drawoiî
such water is lassured in the present system by providing
conduit, a second drawoiî conduit connected to the top of
a second outlet for demineralized water positioned be
sai-d butter tank, and a second drawoíî valve included in
said second drawoñ conduit, whereby opening of said
ing to points of use requiring less highly demineralized
second drawoff valve eiiec-ts the i'low of raw water from
water and being subject to long sustained draw-olie.
said inlet pipe into the bottom of said bilder tank and the
consequent iiow of water through said buffer tank into
in view of the foregoing, it is apparent that there has
said second dr'awofî conduit and therefrom to the exterior
been provided an improved water demineralizing method
and system utilizing electrodialysis to provide corrosion GO with the result that only the storage capacity of said butter
tank Vmay be employed in supplying a demand for de
protection for the storage tank and other parts subject to
tween the butter tank and the treatment unit and connect
corrosion coming in contact with the water and further a
system involving both ion exchange and electrodialysis,
mineralized Water from said second drawolî conduit.
2. The apparatus set forth in claim l, and further com
prising means for heating the Water stored in said buffer
wherein the recovery or regeneration rates of the anion
exchange resin and the cation exchange resin are sub 65 tank, whereby hot demineralized water is supplied from
either one of said drawoñ conduits upon opening of the
stantially matched, so that the states of charge or regen
corresponding one of said drawoff valves.
eration of the two resins are substantially matched in
3. Apparatus for lden'iineralizing raw water containing
the operation of the system.
dissolved metal salts; said »apparatus comprising a buffer
While there has ybeen described what is at present con 70 tank, an inlet pipe adapted to contain raw Water under
sidered yto be a certain preferred embodiment of the in
pressure and connected to said 'buffer tank, hollow struc
vention, it will be understood that various modifications
ture defining an anolyte chamber and including a porousmay be made therein, and it is intended to cover in the
Wall that is permeable both to water` and to ions con
appended claims all such modifications as tall within
tained therein, means for mounting said structure upon .
said buffer tank in sealed relation therewith and with said
the true spirit and scope ofthe invention.
3,074,865
17
porous wall in covering relation with an opening provided
in said buñer tank, whereby one side of said porous wall
is in contact with the water in said buffer tank and the
other side of said poro-us wall is in contact with the ano
lyte in said anolyte chamber, an anode element disposed
in said anolyte chamber in contact with the anolyte there
in and electrically insulated from said buffer tank, means
for applying a potential between said anode element and
18
displacements both of sorbed anions from said bed into
the anolyte in said first chamber and of sorbed cations
from said bed into the catholyte in said third chamber,
and whereby the application of potential between said
anode and said second cathode either concurrently or
nonconcurrently with the application of potential be
twen lsaid anode and said first cathode effects substantial
gration of anions from the water in said buffer tank
displacement only of sorbed anions from said bed into the
anolyte in said first chamber, said displacements of sorbed
anions and sorbed cations from said bed effecting corre
through said porous wall into the anolyte in said anolyte
chamber, whereby the pH of the water in said buffer tank
said bed.
said buifer tank as a -cathode element so as to cause mi
sponding anion regeneration and cation regeneration ot
5. The apparatus set forth in claim 4, wherein said
second cathode is disposed in said second chamber ad
from said buñer tank passes through said porous wall as 15 jacent to said second diaphragm, so that the major por
tion of said bed is disposed between said first diaphragm
fresh anolyte into said anolyte chamber, an electrolytic
and said second cathode.
cell includ-ing structure defining a treatment compartment
6. The apparatus set forth in claim 4, wherein said
and a catholyte compartment and an anolyte compart
bed of `io-n exchange material comprises a mixed bed of
ment with a first ion permeable diaphragm as a common
wall between said treatment compartment and said cathoH 20 discrete paiticles of anion exchange resin and of cation
exchange resin.
lyte compartment and with a second ion permeable dia
7. Apparatus for dernineralizing raw water containing
phragm as a common wall between said treatment corn
is increased, means for selectively discharging to the ex
terior anolyte from said anolyte chamber, whereby water
partment and said anolyte compartment, said electro
dissolved metal salts, comprising an eleotrolytic cell iri
anolyte compartment with the resulting regeneration of
either concurrently or nonconcurrently with the applica
mon wall between said first arid second chambers and a
third chamber, and whereby during said second time inter
val there is effected substantial displacement only of
cluding structure defining first and second and third charn
lytic cell also including a cathode member in said catho
lyte compartment and an ari-ode member in said anolyte 25 bers, a ñrst ion permeable diaphragm disposed as a com
nron wall between said first and second chambers and a
compartment, a bed of ion exchange material arranged
second ion permeable diaphragm disposed as a common
in said treatment compartment and including both cation
wall between said second and third chambers, a bed of
exchange centers and anion exchange centers, conduit
ion exchange material having both cation exchange cen
means completing a closed series loop circuit from said
buffer tank to said treatment compartment and thence 30 ters 4and anion exchange centers and disposed in said
second chamber, means for conducting raw water through
back to said buffer tank, an outlet pipe adapted to contain
said second chamber into contact with said diaphragms
demineralized water under pressure and connected to said
4and into ion exchange relation with said bed, whereby
loop circuit on the outlet side thereof, valve mechanism
the raw water is demineralized with the resulting degen
arranged in said outlet pipe, whereby opening of said
35
eration of said bed, said first chamber being adapted to
valve mechanism effects the supply of demineralized water
contain a body of anolyte therein in contact with said
from said treatment compartment to said outlet pipe and
first diaphragm and said third chamber being adapted to
effects the supply of raw water from said inlet pipe to said
con-tain a body off catholyte therein in contact with said
buffer tank, pump means for effecting local circulation of
second diaphragm, an »anode disposed in said first cham
water in said loop circuit from said buffer tank through
said treatment compartment and back to said buffer tank, 40 ber and a first cathode disposed 4in said third chamber and
a `second cathode disposed in said second chamber, and
whereby the circulating water is demineralized by said
cyclic means for applying potential between said anode
bed with the resulting degeneration thereof and whereby
and said first `and second cathodes, wherein in each cycle
the pH of the water in said treatment compartment is
potential is applied during a first time interval between
decreased, and means for applying a potential between
said anode member and said cathode member to cause 45 `said anode and said first cathode nonconcurrently with the
Iapplication of potential between said anode and said sec
displacement of sorbed cations from said bed into the
ond c-athode and potential is applied during a second time
catholyte in said catholyte compartment and displacement
interval between said anode and said second cathode
of sorbed anions from said bed into the .anolyte in said
50 tion of potential between said anode and said first cath
Said bed.
ode, whereby during said first time interval there are
4. Apparatus for deminei‘alizing raw water containing
effected substantial displacements of both sorbed anions
dissolved metal salts, comprising an electrolytic cell in
from said bed into the anolyte in said first chamber and
cluding structure defining first and second and third cham
of sorbed cations from said bed into the catholy-te of said
bers, a first ion permeable diaphragm disposed as a com
second ion permeable diaphragm disposed as a common
wal between said Isecond and third chambers, a `bed of ion
so-rbed anions from said bed into the anolyte in said first
chamber, said displacements of sorbcd anions and sorbed
cations from said »bed effecting corresponding anion re
chamber, means for conducting raw water through said 60 generation and cation regeneration of said bed.
8. The apparatus set forth in claim 7, wherein during
second chamber tinto Contact with said diaphragms and
said first time interval the rate of displacement of sorbed
into ion exchange relation with said bed, whereby the
cations from said bed is substantially higher than the rate
raw water is demineralized with the resulting degeneration
of] displacement of sorbed anions from said bed, and
of said bed, said first chamber being adapted to contain a
wherein said first and second time intervals are so related
body of anolyte therein in contact with said first dia
that during each cycle the total displacements of sorbed
phragm and said third chamber being adapted to contain
anions and of sorbed cations from said bed are substan
a body of catholyte therein in contact with said second
tially equivalent in order to effect substantially equivalent
diaphragm, an anode disposed in said first chamber and
anion regeneration and cation regeneration of said bed.
a first cathode disposed in said third chamber and a sec
9. Apparatus for demineralizing raw water containing
ond cathode disposed in said second cham er, and means
dissolved metal salts, comprising an electi'olytic cell in
for selectively applying potential between said anode and
cluding structure detinirig first and second and third cham
said first and second cathodes, whereby the application of
bers, a first ion permeable diaphragm disposed as a com
potential between said anode and said first cathode non
exchange material having both cation exchange centers
and anion exchange centers and disposed in said second
concurreritly with the application of potential between
mon wall between said ñrst and second chambers and a
said anode and said second cathode effects substantial 75 second ion permeable diaphragm disposed as a common
Vsombere
Y
,
i9
,
2@
,
wall between said second and third chambers, a bed of ion
said second chamber into contact »with said kdiaphragms
exchange material having both cation exchange centers
and into ion exchange relation with said bed, whereby the
and »anion exchange centers and disposed in said second
chamber, means for conducting raw water through said
raw 4water is demineralized with the resulting degeneration
raw water is demineralized with the resulting degenera
tion of said bed, said first chamber being adapted -to con
.tain a body of anolyte therein in contact with said first
diaphragm and said third chamber being adapted to con
tain a body of catholyte :therein in contact with said second
of said bed, said fir-st chamber being adapted to contain
« diaphragm, an anode-disposed in said first chamber and a
a body of anolyte therein in contact with said first dia
phragm and said third chamber being adapted to contain
a body of catholyte therein in contact with said second
fir-st cathode disposed in said third cham-ber and a second
cathode disposed in said second chamber, and means for
y diaphragm, an anode disposed in said first chamber and a
l Áand said first cathode and for applying a relatively low
first cathode disposed in said third chamber and a second
`cathode disposed in said second chamber, and means for
, 1whereby the applications of said potentials effect „bot-h a
second .chamber into contact with said diaphragrns and
into ion exchange relation with said bed, whereby the
applying a relatively high potential between said anode
potential between said anode and saidfsecond cathode,
i continuously applying potential between said anodeand 15 substantial displacement of -sorbedvanions firom- said bed
said first cathode and for selectively applying potential
into the >anolyte in Vsaid «first chamber and a substantial
displacement of sorbed cations from lsaid -bed into the
catholytein said third chamber, said displacement vof
sorbed anions from `said bed effecting corresponding anion
tential between said anode and said second cathode effects 20 regeneration thereof at a first rate and vksaid displacement
substantial displacements both of sorbed anions from said
of sorbed cations from said bed effecting corresponding
bed into the anolyte in said first chamber and of sorbed t cation regeneration thereof at a second rate,.and wherein
. between said anode `and said second cathode, whereby
the application of potential between said anode and said
first cathode nonconcurrently with Ithe application of po
cations from `said bed into the catholyte in said third
» said first and second regeneration rates substantially match
chamber, and whereby the application oñ potential'be
each other lso as to maintain substantially equivalent
tween said anode and said second cathode concurrently
anion ¿regeneration and cation regeneration of said bed.
yl2. The method of demineralizing raw water containing
dissolved metal salts, comprising passing the raw water
`through a bed of ion ,exchange material _including both
,anion exchange centers and cation exchange centers and
- with the application of poten-tial between said anode and
said first »cathode effects substantial displacement only of
sorbed anions from said bed into the anolyte in said first
chamber, said displacements of sorbed anions and sorbedn
cations from said bed effecting corresponding anion re
generation and cation vregeneration of said bed.
.
30
contained in an inner compartment of -an electrolytic cell
and separated by a` first ion permeable diaphragm from a
body of lanolyte and separa-ted by a second ion permeable
. diaphragm from‘ia body of -catholytc,_and selectively ap
cluding structure defining first andsecond and third charn- f
plying potential between an lanode arranged in contact
t bers, a ñrst ion permeable diaphragm disposed as a corn C13 Ul with said body of anolyte and firstand second cathodes
„mon wall between said first and second. chambers and a
respectively arranged lin contact with said body of catho
second ion permeable diaphragm disposed as a common
`lyte land in contact with the water in said inner compart
wall between said second and third chambers, a bed of ion
ment, whereby ‘the application of potential between said
exchange material having both cation exchange centers
anode and said first cathode n.onconcurrently_with the
40
and anion exchange centers and disposed in said second
application of potential between said-anode and said sec
v chamber, means for conducting raw water. through said
ond cathode> effects substantial displacements both of
second chamber into, contact with said diaphragms and
sorbed :anions from said bed into said body of anolyte and
into ion exchange relation with said bed, whereby the raw
of sorbed cations from said bed into said body of catholyte,
water is demineralized with the resulting degeneration of
and whereby the application of potential between said
said bed, said first chamberk being adapted to contain a 45 anode and said second cathode either concurrently or
body of lanolyte therein in contact with said first dia
nonconcurrently `with the 'application of potential between
phragm and said third chamber being adapted to contain
said anode and said ñrst cathode effects substantial dis
a body of catholyte thereinin contact with said second
placement only of sorbed anions from said bed into said
diaphragm, an anode disposed in said first chamber and a
body of anolyte, said displacements of sorbed .anions and
50
first cathode disposed in said third -chamber and a second
sorbed cations from said bed effecting corresponding
cathode disposed in said second chamber, and means for
anion regeneration and cation regeneration of said bed.
alternately applying potential between said anode and said
13,. The method set forth in claim l2, wherein said sec
first cathode and between said anode and said second cath
- ond cathode is disposed in said inner compartment ad
ode, whereby the application of potential between said
jacent to said second diaphragm so that the. major por
anode and said first cathode effects substantial displace 55 tion of said bed is disposed between said first diaphragm
ments both of sorbed anions from said bed into the anolyte
and said second cathode, whereby 'the major portion 0f
in said first chamber and of sorbed cations from said bed
said bed is subiected to anion regeneration upon applica
into the catholyte in said third chamber, and whereby the
tion of potential between said anode and said second
application of potential between said anode and said
cathode.
~
second cathode effects substantial displacement only of 60
14.' The method. set for-th in claim l2, wherein said bed
sorbed anionsfrom said bed into the anolyte in said first
comprises a mixed bed of discrete particles of anion ex
chamber, said displacements of sorbed anions and sorbed
change resin Iand or" cation exchange resin.
» cations from said bed effecting corresponding anion regen
15. The method of demineralizing r-aw water containing
eration-and cation regeneration of said bed,
dissolved
metal salts, comprising passing the raw water
l -l l.Y Apparatus for demineralizing raw water containing 65 through a bed of ion exchange material including both
»Y dissolved metal salts, comprising an electrolytic cell in
anion exchange centers Iand cation exchange centers and
cluding structure defining first and second and third cham
contained inian inner compartment of ian electrolytic cell
bers,- a first ion permeable diaphragm disposed `as a com
'and separated by a first ion permeable diaphragm from a
„ mon wall between said first and second chambers and a
70 body «of anolyte and separated by a second ion permeable
second ion permeable diaphragm disposed as a common
diaphragm from ya body »of catholyte, and cyclically ap
wall between said second land third chambers, a bed of
plying potential between an lanode arranged in contact
ion exchange material having both cation exchange cen
with said body of anolyte yand first and second oathodes
10. Apparatus for dernineralizing raw water containing
dissolved metal salts, comprisingtan electrolytic cell in
i ters and anion exchange centers and disposed in said sec
respectively arranged in contact with said body of catholyte
ond chamber, means for conducting raw water through 75 and in contact with the water in `said inner compartment,
3,074,865
21
wherein in each cycle potential is applied between said
vfirst anode tand said first cathode during la first time in
terval nonconcurrently with the application of potential
between said anode and said second cathode «and poten
tial is applied between said anode and said second cathode
during a second time interval either nonconcurrently or
concurrently with the application of potential between said
anode and said first cathode, whereby during said first
22
both anion exchange centers and cation exchange centers
and contained in an inner compartment of an electrolytic
cell and separated by a first ion permeable diaphragm
from a body of anolyte and separated by a second ion
permeable diaphragm from a body of catholyte, and al
ternately applying potential between an anode arranged
in contact with said body of anolyte and first and sec
ond cathodes respectively arranged in Contact with said
body of catholyte and in contact with the water in said
time interval there are effected substantial displacements
both of sorbed anions from said bed into said body of 10 inner compartment, whereby the application of potential
between said anode and said first cathode effects sub
anolyte and of sorbed cations from said bed into said body
stantial displacements both of sorbed anions from said
of catholyte, and whereby during said second time interval
bed into said body of anolyte and of sorbed cations from
there is effected substantial displacement only of sorbed
said bed into said bed of catholytes, and whereby the
anions from said bed into said body of anolyte, said
displacements of sorbed anions and sorbed cations from 15 application of potential between said anode and said sec
ond cathode effects substantial displacement only of
said bed effecting corresponding anion regeneration and
sorbed anions from said bed into said body of anolyte,
cation regeneration of said bed.
said displacements of sorbed anions and sorbed cations
16. The method set forth in claim 15, wherein during
from said bed effecting corresponding anion regeneration
said first time interval the rate Iof displacement of sorbed
cations from said bed is substantially higher than the rate 20 and cation regeneration of said bed.
19. The method of demineralizing raw water contain
of displacement of sorbed anions from said bed, and
wherein said iirst and second time intervals are so related
ing dissolved metal salts, comprising passing the raw
water through a bed of ion exchange material including
both
anion exchange centers and cation exchange cen
lanions and sorbed cations from said bed are substantially
ters
and
contained in an inner compartment of an elec
25
equivalent in order to effect substantially equivalent anion
trolytic cell and separated by a first ion permeable dia
regeneration and cation regeneration of said bed.
phragm from a body of anolyte and separated by a sec
17. The method of demineralizing raw water containing
ond ion permeable diaphragm from a body of catholyte,
dissolved metal salts, co-mprising passing the raw water
continuously applying a relatively high potential between
through a bed of ion exchange material including both
an anode arranged in contact with said body of anolyte
anion exchange centers and cation exchange centers and 30 and a first cathode arranged in contact with said body
contained in a inner compartment of an electrolytic cell
of catholyte, and continuously applying a relatively low
that during each cycle the total displacements of sorbed
and separated by a first ion permeable diaphragm from
potential between said anode and a second cathode ar
1a body of anolyte and separated by a second ion permeable
ranged in contact with the water in said inner compart
diaphragm from a body of catholyte, continuously ap 35 ment, whereby the applications of said potentials effect
plying potential between an anode :arranged in Contact
both a substantial displacement of sorbed anions from
with said body of anolyte »and a first cathode arranged in
said bed into said body of anolyte and a substantial dis
contact with said body of catholyte, and selectively apply
placement of sorbed cations from said bed into said body
ing potential between said anode and a second cathode
of catholyte, said displacement of sorbed anions from
arranged in Contact with the water in said inner compart 40 said bed effecting corresponding anion regeneration
ment, whereby the «application of potential btween said
thereof at a first rate and said displacement of sorbed
anode and said ñrst cathode nonconcurrently with the
cations from said bed effecting corresponding cation re
application .of potential between said 'anode and said sec
generation thereof at a second rate, and wherein said
ond cathode effects substantial displacements both of
first and second regeneration rates substantially match
sorbed anions from ysaid bed into said body of anolyte 45 each other so as to maintain substantially equivalent
and of sorbed cations from said bed into said body of
anion regeneration and cation regeneration of said bed.
catholyte, and whereby the application of potential be
tween said «anode and said second cathode concurrently
with the application of potential between «said anode and
said first cathode eiî'ects substantial displacement only of 50
sorbed anions from said bed into said body of anolyte,
said displacements tof sorbed anions and sorbed cations
from said bed effecting corresponding anion regenera
tion and cation regeneration of said bed.
18. The method of demineralizing raw water contain 55
ing dissolved metal salts, comprising passing the raw
water through a bed of ion exchange material including
References Cited in the iile of this patent
UNITED STATES PATENTS
1,431,047
2,535,035
2,681,885
2,838,449
2,863,813
2,906,684
2,997,430
Ruben _______________ __ Oct. 3,
Briggs ______________ __ Dec. 26,
Briggs ______________ _- June 22,
Briggs ______________ __ June 10,
Juda et al. ____________ __ Dec. 9,
Stoddard ____________ _... Sept. 29,
1922
1950
1954
1958
1958
1959
Foyn _______________ _... Aug. 22, 1961
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