Water softener abstract
Regeneration controller and method for controlling regeneration
of a water softener are provided. The controller includes a water
meter configured to output a signal indicative of the volume of
influent water received by the water softener. A water-hardness
indicator, such as a conductivity meter or ion-selective electrode,
is configured to output a signal indicative of a degree of hardness
of the influent water. A processor is coupled to receive the respective
signals from the water meter and the hardness indicator. The processor
is further configured to calculate a value indicative of the total
level of hardness removed by the water softener. A comparator is
coupled to receive a signal indicative of the quantity of resin
capacity of the water softener. The comparator is further configured
to receive the value indicative of total hardness to issue a regeneration
command based on comparing the resin capacity relative to the value
of total hardness.
Water softener claims
What is claimed is:
1. A regeneration controller for water softener comprising: a water
meter configured to output a signal indicative of the volume of
influent water received by the water softener; a waxer-hardness
indicator configured to output a signal indicative of a degree of
hardness of the influent water, wherein the water-hardness indicator
comprises an ion-selective electrode configured to measure degree
of calcium ion concentration in the influent water; a processor
coupled to receive the respective signals from the water meter and
the water-hardness indicator, the processor being configured to
compute a value indicative of the total level of hardness removed
by the water softener; and a comparator coupled to receive a signal
indicative of the capacity of the resin in the water softener, the
comparator further configured to receive the value indicative of
total hardness to issue a regeneration command based on comparing
the resin capacity relative to the value of total hardness.
2. The regeneration controller of claim 1 wherein the water-hardness
indicator comprises a conductivity meter configured to measure a
degree of conductivity of the influent water.
3. The regeneration controller of claim 2 further comprising memory
for storing a functional relationship for relating the degree of
conductivity measured by the conductivity meter to degree of hardness
of the influent water.
4. The regeneration controller of claim 2 further comprising a
look-up table for relating the degree of conductivity measured by
the conductivity meter to a degree of hardness of the influent water.
5. The regeneration controller of claim 1 further comprising memory
for storing a functional relationship for relating the degree of
calcium ion concentration measured by the ion-selective electrode
to a degree of hardness of the influent water.
6. The regeneration controller of claim 1 further comprising a
look-up table for relating the degree of calcium ion concentration
measured by the ion-selective electrode to a degree of hardness
of the influent water.
7. The regeneration controller of claim 1 wherein the total level
of hardness removed by the water softener is calculated based on
the product of the volume of influent water by the degree of hardness
of the influent water.
8. The regeneration controller of claim 1 wherein the comparator
is configured to generate the regeneration command when the total
level of hardness computed by the processor is equal to the level
of resin capacity of the water softener.
9. A method for controlling regeneration of a water softener, the
method comprising: measuring the volume of influent water received
by the water softener; measuring a signal indicative of degree of
hardness of the influent water, wherein the signal comprises a measurement
of calcium concentration in the influent water; calculating a value
indicative of the total level of hardness removed by the water softener;
providing the quantity of resin capacity of the water softener;
and relating the quantity of resin capacity to the value of total
hardness to determine whether or not regeneration is to be commanded
for the water softener.
10. The control method of claim 9 wherein the signal indicative
of the degree of hardness of the influent water comprises a measurement
of a degree of conductivity of the influent water.
11. The control method of claim 9 further comprising relating the
measured degree of conductivity degree of hardness of the influent
water.
12. The control method of claim 9 further comprising relating the
measured degree of calcium concentration to a degree of hardness
of the influent water.
13. The control method of claim 9 wherein the total level of hardness
removed by the water softener is calculated based on multiplying
the volume of influent water times the degree of hardness of the
influent water.
14. The control method of claim 9 wherein the regeneration command
is issued when the calculated total level of hardness is equal to
the resin capacity of the water softener.
Water softener description
BACKGROUND OF INVENTION
The present invention is generally related to water softeners,
and, more particularly, to a controller and method for controlling
regeneration of a water softener based on the total hardness (e.g.,
concentration of calcium carbonate) removed from the influent water
to the softener. Here, total hardness is defined as the hardness
of the water times the total volume of water softened.
Municipal water treatment plants often draw water from several
sources that vary in hardness. For example, when the source of the
water is groundwater, the water can be relatively hard, which is
equivalent to, for example, a high concentration of calcium carbonate.
However, when the source of the water is surface water, the water
can be relatively soft, such as characterized by a low concentration
of calcium carbonate. Many municipal water treatment plants use
both types of water in varying proportions. The proportion of hard
and soft water used by a municipal water treatment plant may also
vary over time. Therefore, the hardness of the water actually delivered
to the consumer can vary considerably throughout the year. Many
consumers use water softeners to soften the water used in their
homes, the work place, schools, etc. These water softeners are typically
preset to soften water of a predefined degree of hardness. The presetting
action assumes that the predefined hardness of the influent water
to the softener remains constant.
Thus, in the past, it has been assumed that the hardness of the
influent water to the water softener remained constant. Further,
it is believed that the only variable that water softeners have
been known to measure is the volume of water treated by the softener.
Hence, if the water hardness varied, the softener would undesirably
regenerate prematurely or not often enough.
In view of the foregoing considerations it would be desirable to
provide a water softener and techniques that permit measuring the
variability of the hardness of the water over time. It would be
further desirable to provide a water softener with a regeneration
controller programmed to regenerate the softener based on the total
hardness removed from the influent water, as opposed to based on
an assumption likely to incorrectly reflect the actual composition
of the water. It would be further desirable to provide a regeneration
technique that avoids any unnecessary discharge of salt (e.g., brine)
to the surrounding environment.
SUMMARY OF INVENTION
Generally, the present invention fulfills the foregoing needs by
providing in one aspect thereof, a regeneration controller for a
water softener comprising a water meter configured to output a signal
indicative of the volume of influent water received by the water
softener. A water-hardness indicator, such as a conductivity meter
or an ion-selective electrode, is configured to output a signal
indicative of a degree of water hardness of the influent water,
such as may be indicated by a conductivity measurement or a calcium
concentration measurement, respectively. A processor is coupled
to receive the respective signals from the water meter and the water-hardness
indicator. The processor is further configured to calculate a value
indicative of the total level of hardness removed by the water softener.
A comparator is coupled to receive a signal indicative of the quantity
of resin capacity of the water softener. The comparator is further
configured to receive the value indicative of total hardness to
issue a regeneration command based on comparing the resin capacity
relative to the value of total hardness.
In another aspect thereof, the present invention further fulfills
the foregoing needs by providing a method for controlling regeneration
of a water softener. The method allows measuring the volume of influent
water received by the water softener. The method further allows
measuring a signal indicative of a degree of hardness of the influent
water, such as by measuring the degree of conductivity of the influent
water or the concentration of calcium in the water. A value indicative
of the total quantity of hardness removed by the water softener
is calculated. The resin capacity of the water softener is provided,
e.g., is known. The resin capacity is related to the value of total
hardness to determine whether or not regeneration is to be commanded
for the water softener.
BRIEF DESCRIPTION OF DRAWINGS
The features and advantages of the present invention will become
apparent from the following detailed description of the invention
when read with the accompanying drawing in which:
FIG. 1 is a block diagram of an exemplary regeneration controller
that, in accordance with aspects of the present invention, may be
configured to issue a command to regenerate the softener based on
the total hardness actually removed from the influent water.
DETAILED DESCRIPTION
Below is generic background information solely for the purpose
of providing a cursory description of one exemplary operation of
a typical water softener. This background information in no way
should be construed as limiting the scope of the present invention
described further below. A water conditioner may comprise at least
two tanks a resin tank and a brine (e.g., salt) tank. The resin
tank is filled with a resin that, for example, comprises relatively
small beads of cross-linked polystyrene sulfonic acid. This resin
may be referred to in the art as a cation resin. The beads may be
constructed to exhibit a permanent electrical charge. The charge
may cause the beads to attract positively charged ions. For example,
the resin may be initially placed into service with Na.sup.+ ions
on the beads. When the hardness ions (e.g., Ca.sup.2+ and Mg.sup.2+)
come in contact with the Na.sup.+, such ions would displace the
Na.sup.+ on the beads. The Na.sup.+ is eventually dissolved into
the water. This sodium generally leaves the resin tank and may be
delivered to the tap with the treated water. In theory, when most
of the Na.sup.+ is removed from the resin beads, regeneration equipment
should start the regeneration process. As explained in the background
section of the present specification, prior to the present invention,
in practice, the regeneration process could be started regardless
of whether or not regeneration is actually needed. The equipment
may temporarily allow raw water (e.g., untreated water) to pass
to the house during regeneration. This action may be done so as
to avoid salt used during regeneration to enter the plumbing of
the site. The resin may then be regenerated by drawing in a relatively
high concentration of salt (e.g., NaCl, KCl) solution from the brine
tank. This salt solution is washed over the depleted resin. The
salt solution may contain Na.sup.+ and Cl.sup.- ions. The Na is
placed back onto the resin beads and the Ca.sup.2+, Mg.sup.2+ and
Cl.sup.- are washed down the drain. The resin may then be rinsed
with fresh water to remove any remaining residual salt. Additional
water may be added to the brine tank to dissolve salt for the next
regeneration cycle. The equipment may then command a service mode
and there would be treated water available from the softener.
The inventor of the present invention has innovatively recognized
that in order to optimize the benefits of a water softener, including
appropriate brine usage for regeneration, it would be advantageous
to regenerate the softener just when the ion exchange resin of the
softener has actually been exhausted. The ion exchange resin of
the softener should preferably be regenerated, when the hardness
removed from the influent water equals the resin capacity (e.g.,
total mass of hardness or grains of hardness). The loading of the
ion exchange resin is a function of the water hardness (e.g., grains
per gallon) times the volume of the water (gallons).
FIG. 1 is a block diagram of an exemplary regeneration controller
10 configured to issue a command to regenerate the softener based
on the total hardness removed from the influent water. As shown
in FIG. 1 controller 10 includes a water meter 12 for supplying
a signal indicative of the volume of influent water to the water
softener. Controller 10 further includes a water-hardness indicator
14 configured to output a signal indicative of a degree of the water
hardness of the influent water. In one exemplary embodiment, the
water hardness indicator comprises a conductivity meter configured
to measure the conductivity (e.g., microsiemens) of the influent
water. In another exemplary embodiment, the water-hardness indicator
comprises an ion-selective electrode configured, for example, to
measure the concentration (e.g., mg/L) of calcium of the influent
water to the softener. Although FIG. 1 illustrates water meter 12
to be upstream relative to water-hardness indicator 14 it will
be appreciated that the specific placement of the water meter relative
to the water-hardness indicator is of no consequence for purposes
of the present invention, and, accordingly, the specific block placement
shown in FIG. 1 should not be construed as limiting the invention.
Examples of conductivity meters that may be used include conductivity
meter, Model No. Sension 5 available from Hach Company, Model No.
3100 available from YSI Incorporated, Model No. 130A, available
from Thermo Orion. Examples of ion-selective electrodes that may
be used for measuring calcium concentration include Model Nos. A27504-06
and A-27504-34 available from Cole-Parmer.
Since the conductivity of the influent water is a function of the
total dissolved solids in the water, the conductivity of the water
comprises an indication or suggests an approximate measure of the
hardness of the water. Accordingly, in one exemplary embodiment
a processor 16 may include a memory 18 for storing a functional
relationship or a look-up table for relating the degree of conductivity
of the influent water as may be measured by a conductivity meter
to a degree of hardness (grains/gallon) of the influent water to
the softener. In another exemplary embodiment, memory 18 may be
configured for storing a functional relationship or a look-up table
for relating the degree of calcium ion concentration, as may be
measured by an ion-selective electrode to a degree of hardness of
the influent water. In each case, such a relationship or look-up
table may be experimentally and/or analytically derived using techniques
well understood by those skilled in the art.
For readers desirous of general background information regarding
the physical basis for relating the water conductivity and water
hardness, reference is made to textbook titled "Standard Methods
for the Examination of Water and Wastewater," edited by L.
S. Clesceri, A. E. Greenberg & R. R. Rhodes Truessell, 17.sup.th
Edition, 1989 and, more specifically, see table 2510:1 page 2-60
for an illustration for relating concentration of potassium chloride
to conductivity measurements.
In one exemplary embodiment, the degree of hardness can be calculated
as follows: Divide concentration (molarity) of potassium chloride
by 2=concentration of calcium (molarity). Multiply the concentration
of calcium (molarity) by 40 gm/mole=concentration of calcium (gm/L).
Multiply the concentration of calcium (gm/L) by 2.5=concentration
of hardness (gm/L) or CaCO.sub.3. Grains of hardness (grains/gal)=concentration
of hardness (gm/L) as CaCO.sub.3 divided by 0.0171 gm/L CaCO.sub.3
per grain hardness per gallon.
Processor 16 is further configured to monitor the total volume
(e.g., gallons) of water softened by the softener based on the signal
supplied by water meter 12. The total hardness (grains) removed
by the softener may be readily calculated by processor 16 by multiplying
the degree of hardness (e.g., grains/gallon calculated using the
functional relationship or look-up table stored in the memory of
processor 16) of the influent water times the volume of water treated
by the softener (e.g., gallons measured by water meter 12). Total
Hardness (e.g., grains)=Hardness (e.g., grains/gallon).times.Volume
of Water Softened (e.g., gallons). A comparator 20 receives the
measurement of total hardness calculated by processor 16. Comparator
20 further receives a signal 22 indicative of the ion exchange resin
capacity of the respective water softener. The value of this capacity,
for example, may be obtained from the specifications of the exchange
resin, or may be estimated based on the particular characteristics,
such as electrochemical and physical characteristics, of the specific
exchange resin in the respective water softener. As suggested above,
when the total hardness (e.g., grains) equals (e.g., grains) of
the ion exchange resin for the given water softener, the softener
will be commanded to regenerate itself in response to a regeneration
command issued by regeneration controller 10.
As suggested above, aspects of the present invention innovatively
allow measuring the total water hardness treated or removed by a
water softener. This is accomplished by measuring both the degree
of hardness (grains/gallon) of the influent water and the volume
of influent water treated by the softener.
In operation, regeneration controller 10 allows to selectively
regenerate the water softener, when the capacity of the ion exchange
resin equals the total hardness removed from the influent water.
This is expected to advantageously reduce the quantity of salt used
to regenerate the softener and, therefore, the quantity of brine
discarded to the surrounding environment, e.g., either a sewer or
a septic tank.
While the preferred embodiments of the present invention have been
shown and described herein, it will be obvious that such embodiments
are provided by way of example only. Numerous variations, changes
and substitutions will occur to those of skill in the art without
departing from the invention herein. Accordingly, it is intended
that the invention be limited only by the spirit and scope of the
appended claims. |