Water softener abstract
A demand initiated method for regenerating a water softener which
operates the softener ion exchange bed over a capacity range in
which the resin is most efficiently restored by exposure to brine.
The reserve capacity of the softener is adjusted in response to
the amount of softening capacity used since the last regeneration,
as is the quantity of saturated brine to be used for the next regeneration,
which is scheduled when the reserve capacity is exceeded, or the
remaining available capacity will not be adequate for normal usage
on the next day of the week.
Water softener claims
We claim:
1. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration, and
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range.
2. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 1 wherein said design exchange
capacity is selected by,
a) determining the average number of days between successive prior
regenerations,
b) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days, and
c) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days.
3. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
defining the lower limit for a first capacity range is set at naught
percent, and said allocated capacity defining the upper limit of
said first capacity range is set at fifty percent of said selected
design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration and,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range.
4. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 3 wherein said threshold capacity
is represented by the formula N/(N+2), said allocated capacity is
represented by the formula (N+1)/(N+2), and N represents the number
of the step in the progression as N increases from 0 to 9.
5. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 4 wherein as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared.
6. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration and,
as the threshold value of the presently selected capacity range
is exceeded, the next capacity range is selected, against which
the remaining available exchange capacity of the resin bed, as a
percentage of the selected design exchange capacity is compared,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range.
7. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
and said allocated capacity defining each successive capacity range
in said progression of capacity ranges being a greater percentage
of the selected design exchange capacity than said threshold capacity
and said allocated capacity defining the prior capacity range, with
said threshold capacity increasing by a larger percentage of said
selected design capacity than said allocated capacity for each successive
capacity range, such that each successive capacity range becomes
narrower,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration and,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range.
8. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
9. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 8 wherein said design exchange
capacity is selected by,
a) determining the average number of days between successive prior
regenerations,
b) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days, and
c) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days.
10. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
defining the lower limit for a first capacity range is set at naught
percent, and said allocated capacity defining the upper limit of
said first capacity range is set at fifty percent of said selected
design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
11. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 10 wherein said threshold
capacity is represented by the formula N/(N+2), said allocated capacity
is represented by the formula (N+1)/(N+2), and N represents the
number of the step in the progression as N increases from 0 to 9.
12. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 11 wherein as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared.
13. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration, as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
14. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
and said allocated capacity defining each successive capacity range
in said progression of capacity ranges being a greater percentage
of the selected design exchange capacity than said threshold capacity
and said allocated capacity defining the prior capacity range, with
said threshold capacity increasing by a larger percentage of said
selected design capacity than said allocated capacity for each successive
capacity range, such that each successive capacity range becomes
narrower,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
15. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range, and
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity.
16. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 15 wherein said design exchange
capacity is selected by,
a) determining the average number of days between successive prior
regenerations,
b) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days, and
c) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days.
17. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
defining the lower limit for a first capacity range is set at naught
percent, and said allocated capacity defining the upper limit of
said first capacity range is set at fifty percent of said selected
design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range, and
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity.
18. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 17 wherein said threshold
capacity is represented by the formula N/(N+2), said allocated capacity
is represented by the formula (N+1)/(N+2), and N represents the
number of the step in the progression as N increases from 0 to 9.
19. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 18 wherein as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared.
20. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration, as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range, and
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity.
21. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
and said allocated capacity defining each successive capacity range
in said progression of capacity ranges being a greater percentage
of the selected design exchange capacity than said threshold capacity
and said allocated capacity defining the prior capacity range, with
said threshold capacity increasing by a larger percentage of said
selected design capacity than said allocated capacity for each successive
capacity range, such that each successive capacity range becomes
narrower,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range, and
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity.
22. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity,
d) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
23. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 22 wherein said design exchange
capacity is selected by,
a) determining the average number of days between successive prior
regenerations,
b) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days, and
c) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days.
24. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
defining the lower limit for a first capacity range is set at naught
percent, and said allocated capacity defining the upper limit of
said first capacity range is set at fifty percent of said selected
design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity,
d) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
25. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 24 wherein said threshold
capacity is represented by the formula N/(N+2), said allocated capacity
is represented by the formula (N+1)/(N+2), and N represents the
number of the step in the progression as N increases from 0 to 9.
26. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 25 wherein as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared.
27. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration, as the threshold
value of the presently selected capacity range is exceeded, the
next capacity range is selected, against which the remaining available
exchange capacity of the resin bed, as a percentage of the selected
design exchange capacity, is compared,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity,
d) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
28. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) establishing a progression of capacity ranges, a threshold capacity
defining the lower limit of each range, and an allocated capacity
defining the upper limit of each range, said threshold capacities
and said allocated capacities each being expressible as a percentage
of the selected design exchange capacity, said threshold capacity
and said allocated capacity defining each successive capacity range
in said progression of capacity ranges being a greater percentage
of the selected design exchange capacity than said threshold capacity
and said allocated capacity defining the prior capacity range, with
said threshold capacity increasing by a larger percentage of said
selected design capacity than said allocated capacity for each successive
capacity range, such that each successive capacity range becomes
narrower,
ii) selecting from said progression of capacity ranges a particular
capacity range against which the remaining available exchange capacity
of the resin bed, as a percentage of the selected design exchange
capacity, is compared,
iii) determining the amount of exchange capacity of the resin bed,
as a percentage of the selected design exchange capacity, which
has been used since the most recent regeneration,
iv) scheduling a regeneration of the resin bed when the amount
of exchange capacity of the resin bed used since the most recent
regeneration is greater than the allocated capacity of the selected
capacity range,
c) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity,
d) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
29. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration by,
i) determining the average number of days between successive prior
regenerations,
ii) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days,
iii) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days,
b) determining when a regeneration of the resin bed should be scheduled
based upon the amount of the selected design exchange capacity which
has been used since the most recent regeneration, and
c) regenerating the resin bed to the selected design exchange capacity.
30. A method of scheduling the regeneration of a resin bed of a
water softener as set forth in claim 29 wherein the quantity of
saturated brine to be used for each regeneration cycle is determined
by,
a) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
b) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
c) determining a first quantity of saturated brine required to
regenerated the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
d) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
e) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
f) passing said preferred quantity of saturated brine through said
resin bed to regenerate the resin bed to the selected design exchange
capacity.
31. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration by,
i) determining the average number of days between successive prior
regenerations,
ii) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days,
iii) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days,
b) determining when a regeneration of the resin bed should be scheduled
by,
i) determining the average amount of exchange capacity used each
day of the week by monitoring and recording on a daily basis the
quantity of water of a predetermined hardness passing through the
water softener,
ii) scheduling a regeneration when the amount of exchange capacity
of the resin bed used since the most recent regeneration plus one
and one half times the average exchange capacity of the resin bed
used on the next day of the week is greater than the selected design
exchange capacity, and
c) regenerating the resin bed to the selected design exchange capacity.
32. A method of scheduling regeneration of a resin bed of a water
softener based upon the remaining available exchange capacity of
the resin bed comprising the steps of:
a) selecting a design exchange capacity to which the resin bed
is to be regenerated at the next regeneration by,
i) determining the average number of days between successive prior
regenerations,
ii) increasing the design exchange capacity when the average number
of days between regenerations falls below a predetermined minimum
number of days,
iii) decreasing the design exchange capacity when the average number
of days between regenerations exceeds a predetermined maximum number
of days,
b) determining when a regeneration of the resin bed should be scheduled
based upon the amount of the selected design exchange capacity which
has been used since the most recent regeneration,
c) determining the quantity of saturated brine to be used for each
regeneration cycle,
i) establishing the approximate exchange capacity of the resin
bed resulting from regenerating the resin bed from a predetermined
state of exhaustion for each of a progression of different quantities
of saturated brine,
ii) determining the approximate remaining available exchange capacity
of the resin bed immediately prior to regeneration,
iii) determining a first quantity of saturated brine required to
regenerate the resin bed to the selected design exchange capacity
from the predetermined state of exhaustion,
iv) determining a second quantity of saturated brine required to
regenerate the resin bed to the approximate remaining available
exchange capacity of the resin bed, from the predetermined state
of exhaustion,
v) determining a preferred quantity of saturated brine required
to regenerate the resin bed to the design exchange capacity, by
subtracting the second quantity of saturated brine from the first
quantity of saturated brine, and
vi) passing said preferred quantity of saturated brine through
said resin bed to regenerate the resin bed to the selected design
exchange capacity.
Water softener description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel method and apparatus for
regenerating the water softening or conditioning material in an
automatic water softener system.
2. Background Information
Water softening with ion exchange material, such as resin particles
or the like, is well known in the art. During the softening process,
typically called the service cycle, the ion exchange resin particles
acquire hardness inducing ions from raw water which is being treated,
in exchange for soft ions. That is, ions which do not induce hardness
to water. After continued contact of the resin particles with hard
raw water, the particles ion exchange capacity is considerably diminished
and regeneration of the resin particles must be accomplished, conventionally
by contacting the resin particles with a brine solution, i.e., an
aqueous solution of sodium chloride or potassium chloride or the
like, during a regeneration cycle.
The ion exchange process, which takes place during the regeneration
of the ion exchange material, is accomplished in a softener or resin
tank of well known construction. A separate brine tank is conventionally
used to form brine for use during the regeneration cycle. When regeneration
is initiated in the softener system, brine drawn from the brine
tank passes through the bed of ion exchange material in the softener
tank to reverse the exchange of ions and revitalize the bed by removing
hardness inducing ions and replacing them with sodium ions, for
example, from the brine.
The amount of brine which is required to regenerate a bed of ion
exchange material of a predetermined volume, is dependent upon the
extent to which the bed is exhausted during the service cycle. This,
in turn, is dependent upon a number of factors, including: (1) the
hardness of the water being treated; and (2) the quantity of water
treated during the service cycle. The cost of operating the softening
system may be reduced by limiting the amount of salt utilized in
each regeneration cycle and the frequency of regeneration cycles
to only that necessary to regenerate the resin particles.
Most water softeners are designed to regenerate on a predetermined
timed cycle which is determined by taking into consideration the
above-mentioned factors. The water softening system regenerates
itself on the predetermined time cycle even if the water softening
system is subjected to either an abnormally high or low usage during
a particular period of time. In the instance of abnormally low usage,
a waste of salt and water results. In the instance of abnormally
high usage, the water softening system is unable to adequately soften
all of the water passing through the system.
Many control systems have been proposed to take into account water
usage on a real time basis. Such systems have been based upon means
which detect the state of exhaustion of the resin bed or means which
measure the quantity of water which has passed through the resin
bed since the most recent regeneration cycle.
Systems which attempt to detect the state of exhaustion of the
resin bed are disclosed in U.S. Pat. Nos. 3246759 and 4257887.
These systems utilize electrodes, mounted in the resin bed, which
are connected to a circuit which detects the condition of the resin
bed. When the condition of the resin bed is such that rejuvenation
should occur, a control circuit is activated to start the regeneration
cycle. These systems, which rely on the difference in conductivity
between beds of exhausted and rejuvenated resin particles, have
not been completely reliable, are relatively expensive, and may
result in salt usage which is not always in direct proportion to
the volume of water processed.
One example of a softening control system which utilizes a means
to measure the quantity of water which has passed through the bed
is disclosed in U.S. Pat. No. 3687289. This system utilizes a
metering device associated with the soft water line to draw off
a predetermined proportion of the water flowing from the soft water
line. The drawn-off water is directed to a pump chamber having an
adjustable water storage capacity. The amount of water drawn off
from the soft water line is directly proportional to the storage
capacity of a pump chamber. The water stored in the pump chamber
is periodically directed to the brine storage tank. The brine storage
tank includes means to activate a timer when the water level in
the brine tank reaches a predetermined level to signal the need
for regeneration. The predetermined proportion of water drawn off
is adjusted dependent upon the hardness of the water being treated.
The above discussed water softener systems signals a regeneration
after the usage of a predetermined amount of soft water. However,
the regeneration cycle is usually delayed so as to occur at night.
Therefore, the resin bed must have a reserve capacity to provide
soft water for the remaining portion of the day after the need for
a regeneration is signaled. The reserve capacity is typically selected
to be that remaining after approximately 70% of the capacity of
the resin bed is used. This large reserve capacity is needed to
maintain soft water service in the event that the need for regeneration
is signaled early in the day. Although such water softener systems
may be designed or adjusted to vary the reserve capacity of the
resin bed, once determined, the reserve capacity becomes fixed.
More recently, a water softener system has been designed which
utilizes a micro-computer to adjust the reserve capacity from day
to day in response to soft water usage. The system includes a turbine
water meter which measures the quantity of water passing through
the resin bed. Based upon the quantity and hardness of the water
which has passed through the resin bed, the micro-computer calculates
the percentage of the capacity of the resin bed used since the last
regeneration. The micro-computer employs an algorithm to make calculations
and decisions based on accumulated time and water use. The algorithm
allows a large reserve for days immediately following a regeneration
and reduces the amount of reserve capacity as more days of significant
water usage accumulate since the most recent regeneration. At such
time as the reserve capacity for a day is reached, the water softener
is scheduled for regeneration that night with a preselected fixed
quantity of salt.
A system similar to the just described system utilizes a similar
algorithm with additional criteria for reducing the probability
of actual usage exceeding the variable reserve. This system determines
and stores water average usage for each particular day of the week.
At the end of each day the calculated reserve capacity remaining
in the resin bed is determined and compared with the stored water
usage average for the next day. If the reserve capacity remaining
is not adequate to meet the expected demand on the next day, the
water softener is scheduled for regeneration that night with a preselected
fixed quantity of salt.
The just described micro-computer systems utilize a variable reserve
capacity and are able to schedule regenerations more in proportion
to water usage and to thereby more accurately reduce the reserve
capacity of the resin bed at the time of regeneration. However,
both of these systems use a fixed quantity of salt for each regeneration.
That is, the quantity of brine solution directed through the resin
bed is the same during each regeneration. Accordingly, in instances
where the reserve capacity of the resin bed is relatively high at
the time of regeneration, a greater quantity of salt is passed through
the bed than is necessary to rejuvenate the resin particles in the
bed. As a result salt is wasted.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a demand
initiated method for regenerating a water softener which will maximize
the efficient use of salt and minimize the use of water for regeneration,
and prevent the exhaustion of the softening ability of the ion exchange
resin bed prior to a regeneration. It is a further object of this
invention to operate the softener ion exchange bed over a capacity
range wherein the resin is most efficiently restored by exposure
to brine.
In accordance with this invention a water softener system is provide
which employs a method of regeneration which both maximizes the
efficient use of salt and minimize the use of water for regeneration.
With usage following normal usage patterns for the system, the method
of regeneration employed by the system also prevents the exhaustion
of the softening ability of the ion exchange resin bed prior to
a regeneration. Further, the method of operating the system causes
the ion exchange bed to function over a capacity range wherein the
resin is most efficiently restored by exposure to brine.
The water softener system of the present invention is operated
according to a method which measures the amount of softening capacity
of resin bed used since the last regeneration, adjusts the reserve
capacity periodical in accordance with soft water usage, and further
employs a method of determining the quantity of salt to be used
during each regeneration of the system. The system of this invention
employs automatic means to make efficient use of the water softener's
residual capacity which remains when the softener's resin bed is
regenerated prior to complete exhaustion. The present invention
further maximizes the efficient use of salt during each regeneration
by selecting a quantity of salt needed to regenerate the resin bed
to a preselected design capacity, which preselected design capacity
is less than the maximum or theoretical capacity of the resin bed.
More specifically, the method of regenerating a water softener in
accordance with this invention, includes making an initial selection
of a design exchange capacity to which the resin bed is to be regenerated
during each regeneration cycle. This design exchange capacity is
preferably approximately equal to the exchange capacity in grains
of the resin bed at that particular salt dosage wherein the exchange
capacity in grains of the bed divided by the particular salt dosage
in pounds is at least approximately 3350. It has been determined
that such a design exchange capacity makes efficient use of the
brine solution during each regeneration cycle. The system is regenerated,
when at the end of any preselected time period, the percentage of
the design capacity of the resin bed used since the last regeneration
cycle exceeds a predetermined percentage in the range of 50 to 100
percent. The resin bed is regenerated with a brine solution made
with a salt dosage which is approximately equal to that which is
necessary to regenerate the resin bed to its design capacity.
Prior to using the system of this invention, the exchange capacity
of the resin bed is determined for various salt dosages. The exchange
capacity of the resin bed for each particular salt dosage is approximately
equal to the capacity of the resin bed subsequent to regeneration
with the particular salt dosage, after having been exhausted to
one grain hardness. This procedure is repeated for different salt
dosages to determine the exchange capacity of the resin bed for
various predetermined salt dosages.
After a period of use following a regeneration, the available exchange
capacity of the resin bed is determined by subtracting the exchange
capacity of the resin bed used since the last regeneration from
the selected design capacity of the resin bed. The exchange capacity
of the resin bed used since the last regeneration is determined
by measuring the volume of water passing through the resin bed since
the last regeneration and multiplying that volume by the hardness
of the water. The salt dosage to be used during m the next regeneration
cycle is determined by subtracting the salt dosage required to provide
the available exchange capacity from the salt dosage required to
provide the design exchange capacity.
Apparatus in accordance with this invention utilizes a turbine
water meter located in the soft water outlet line of the water softener
to measure the water usage in gallons since the last regeneration.
A micro-computer is provided which is programmed to receive an input
from the water meter, an input of the grains of hardness of processed
water, and to automatically make the necessary calculations to determine
when to regenerate the resin bed and to determine the proper salt
dosage in terms of water fill time to the brine tank prior to each
regeneration.
The regeneration of a resin bed of the water softener in accordance
with the above method and apparatus fully restores the resin bed
to its design capacity upon completion of each regeneration cycle.
The amount of saturated brine in the brine tank prior to each regeneration
is just enough to restore the resin bed to its design capacity.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of an automatic water conditioning
system of the general type which embodies the present invention.
FIG. 2 is a chart showing a typical relationship between softening
capacity in grains and salt dosage.
FIG. 3 is a graphic representative of the terms used in referring
to the softening capacity of a water softener.
FIG. 4 is a graphic representative of the terms used in referring
to the softening capacity of a water softener and the term used
in describing the method of this invention.
FIG. 5 is a chart of the values of threshold capacities and allocated
capacities by index levels in accordance with the method of this
invention.
FIG. 6 is a flow chart illustrating the sequence of steps undertaken
by a micro-processor in controlling the regeneration of a softener
in accordance with one aspect of the method of this invention.
FIG. 7 is a flow chart illustrating the sequence of steps undertaken
by a micro-processor in creating historic day of the week usages
of softening capacity, and for scheduling a regeneration based thereon
in accordance with one aspect of this invention.
FIG. 8 is a flow chart illustrating the sequence of steps undertaken
by a micro-processor in adjusting the amount of saturated brine
to be used for a regeneration based on the number of days between
regenerations.
FIG. 9 is a flow chart illustrating the sequence of steps undertaken
by a micro-processor in determining the amount of saturated brine
to be used for a regeneration based on upon the capacity used or
progress since the last regeneration.
FIG. 10 is a flow chart illustrating the sequence of steps undertaken
by a microprocessor in controlling the regeneration of the resin
bed of a water softener employing all aspects of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
To assist in the understanding of the water softener regeneration
control system of this invention, a schematic diagram of a water
conditioning system of conventional construction as shown in FIG.
1 will be described. The system 10 is designed to soften water when
it is delivered to a residence or business for use during what is
typically called the "service cycle" of the system. Periodically
the system 10 must be regenerated to restore its softening capability.
The system 10 is regenerated by the use of a brine solution during
a "regeneration cycle". The present invention is concerned
with the control of the regeneration cycle.
During a service cycle, raw or hard water is passed through an
supply pipe 12 to a control valve 14. The control valve 14 supplies
the raw water through a pipe 16 to a tank 18 which contains a bed
of ion exchange resin particles. The raw water passes through the
bed of resin and is withdrawn from the tank 18 through an outlet
pipe 20. The water withdrawn through the outlet pipe 20 which has
been softened by contact with the ion exchange resin again passes
through the control valve 14 to a service pipe 22.
When the ion exchange resin losses its capacity to effectively
soften the water passing through it, regeneration is necessary.
A regeneration cycle typically includes cycles to backwash and rinse
the resin. Those cycles are followed by a brine cycle during which
a brine solution flows through the ion exchange resin particles.
A timer 24 initiates the brine cycle by actuating the control valve
14 to direct water from the supply pipe 12 through a pipe 26 and
aspirator valve 28 to pipe 30. The flow through pipe 30 which passes
through control valve 14 is directed by the control valve to outlet
pipe 20. The water from pipe 26 passing through the aspirator valve
28 creates a pressure reduction by Venturi effect in a pipe 32 which
extends to near the bottom of a brine tank 34. Due to the pressure
reduction, brine is drawn from the brine tank 34 through the pipe
32 and flows with the water through pipe 30 control valve 14 and
pipe 20 to the bottom of resin tank 18. The flow of brine through
the ion exchange resin particles removes the hardness creating ions
and carries them, with the discharge water, through pipe 16 control
valve 14 to a drain 36. The flow of water through pipe 26 as controlled
by timer 24 is continued long enough to withdraw all of the brine
available to the pipe 32 in the brine tank 34. Thereafter the control
valve 14 stops the flow of water to pipe 26 from pipe 12 and instead
directs it to outlet pipe 20 to backwash the ion exchange resin
particles. Prior to the next regeneration cycle, water from the
supply pipe 12 is directed by the control valve 14 to the brine
tank 34 to create brine for the next regeneration cycle. In accordance
with this invention, the softening system 10 also includes a microprocessor
control 38 and a water meter 40.
The present invention is directed to an improved method and apparatus
for controlling the regeneration cycle, so as to provide improved
efficiency in the use salt and water for regeneration, while at
the same time insuring that softening capacity will not be lost
between regeneration cycles.
Referring to FIG. 2 a theoretical salt versus capacity curve for
an ion exchange resin bed is shown. The amount of ion exchange resin
in the resin tank will determine the maximum theoretical operating
capacity of the softener. However, operating the softener at its
maximum theoretical capacity point, results in relatively inefficient
salt usage. If the softener is operated at lower points on the salt/capacity
curve, the salt efficiency will increase. In accordance with method
of this invention, the softener control is designed to force the
softener to operate on the lower, more efficient portion of the
salt/capacity curve.
The volume of water flow through the resin tank 18 from the pipe
12 to the pipe 22 is measured by the water meter 40. The softening
capacity used since the last regeneration is determined by multiplying
the quantity of water used, as measured by the water meter 40 by
the predetermined hardness of the hard water entering the resin
bed through the pipe 12. Softening capacity is typically expressed
in term of grains of hardness. The total softening capability of
the system following a regeneration can be expressed in terms of
grains of hardness, as can the amount of softening capacity which
has been used since the last regeneration.
Referring to FIG. 3 which is a capacity bar chart, terms used
in setting forth the use of softening capacity of a softener in
terms of its last regenerated capacity will be explained. Immediately
following the regeneration of the resin bed, the full regenerated
capacity is available as represented by 0% Exhausted on the left.
As the softener is used to soften water, the used softening capacity
is represented by the portion of the bar chart labeled "Capacity
Used". The exhaustion of the softening capacity of the resin
bed is indicated on the right of FIG. 3 by 100% Exhaustion. Thus,
the portion of the bar chart to the right of the line identified
by the letter "P" represents the remaining capacity. As
indicated by the arrow at the top of FIG. 3 progress represented
by the letter "P", is measured in terms of the portion
of the capacity available after the last regeneration which has
been used.
One procedure which has been used for determining when the resin
bed should be regenerated is based upon reserving a fixed amount,
typically 30% of the total regenerated capacity. Thus, when use
exceeds 70% of the total regenerated capacity, a regeneration is
scheduled.
Referring now to FIG. 4 added to the capacity bar chart of FIG.
3 are two additional values, one of which is a "threshold capacity"
as indicated by the letter "T" and an "allocated
capacity" as indicated by the letter "A". In accordance
with the method of this invention, regeneration of a water softener
resin bed is based upon comparing the percentage of capacity used
to a range of capacity values, the lower limit of which is defined
as a Threshold Capacity and the higher limit of which is defined
as an Allocated Capacity. In a preferred embodiment of this invention,
ten index levels, or ranges of capacity vales are established. The
percentage of capacity used or "progress" is compared
to one of the index levels. The threshold and allocated capacities
are determined by the following formuli:
T=N/(N+2)
A=(N+1)/(N+2)
Where: T=Threshold Capacity
A=Allocated Capacity
N=Index Level
Using these formulas for establishing the threshold and allocated
capacities, their percentage values for index levels 0 through 9
are shown in the chart of FIG. 5.
In accordance with the method of this invention for controlling
regeneration, if the progress since the last regeneration is less
than the threshold capacity of the index level currently being used,
no action with respect to initiating a regeneration will be taken,
and the progress will be compared against the same index level for
successive days as long as the progress does not exceed the threshold
capacity. The progress will continue to be compared to the threshold
and allocated capacities of the same index level on a daily basis,
until the progress is greater than the threshold capacity. When
the threshold capacity is exceeded, the next index level will be
used for comparison with the progress on the next day.
Since the threshold value for the index level 0 as shown in FIG.
5 is 0 should there be use of capacity on the first day, the method
of this invention will be indexed to the first level. As the progress
is compared on a daily basis with the current index level, should
the threshold value be exceeded but not the allocated value, the
progress comparison on the subsequent day will be at the next index
level. However, if on any day the comparison shows the allocated
capacity for the current index level to have been exceeded, a regeneration
of the resin bed will be scheduled. In summary, in accordance with
this method of controlling the scheduling of regeneration, the incrementing
of the index level to the next level can only occur once per day,
and if the index level is changed, it will only change at the time
of day when a regeneration occurs if one is called for.
FIG. 6 schematically represents the routine for scheduling a regeneration
of the resin bed of a softener in accordance with one aspect of
the method of this invention. That is, in accordance with this regeneration
method (1), the comparison of progress to the threshold and allocated
capacities for the index levels set forth in FIG. 5. With threshold
and allocated values for index levels determined in accordance with
the formula previously set forth, in accordance with this regeneration
method 1 if progress as represented by the letter P is greater
than allocated value as represented by the letter A, then the index
level N is reset to 0 and a regeneration scheduled. If the progress
is not greater than the allocated value and further is not greater
than the threshold value, then a regeneration is not scheduled.
However, if the progress is not greater than the allocated value
but is greater than the threshold value, then the index level is
advanced by 1. If the index level is not 10 the allocated and threshold
values at the next index level are utilized for the following day's
comparison. If the index level is equal to 10 it is reset to 9
for use in the next day's comparison.
The method for controlling the regeneration of a water softener
resin bed in accordance with this invention also takes into consideration
the day of the week. As will be hereinafter described, if the previous
method for determining whether or not a regeneration should be scheduled
does not call for a regeneration, then a regeneration may be scheduled
based upon a comparison with a historical day of the week usage.
In accordance with this aspect of the method of this invention,
at the beginning of each day, the current percent capacity used
(progress) is stored as a reference value P.sub.R. At the end of
each day, the current day's water usage (U) is calculated by subtracting
the progress at the beginning of the day (P.sub.R) from the progress
at the end of the day (P) as set forth in the following formula:
The historical daily capacity (H.sub.D) for the particular day
of the week just completed is then updated according to the formula:
A regeneration is scheduled if 150% of the historical daily usage
for the next day of the week will be greater than the remaining
capacity which may be expressed as:
FIG. 7 schematically represents the routine for scheduling a regeneration
of the resin bed of a softener in accordance with another aspect
of the method of this invention. That is, a comparison is made of
the progress at the end of a day to the next calendar day historic
usage. In accordance with this regeneration method (2), the usage
during a day, as determined by subtracting the usage of the progress
at the beginning of day from that at the end of the day is, used
in accordance with the formula set forth above to establish a new
historical daily usage for the just completed calendar day. One
and one half times the historical usage for the upcoming calendar
day is then compared to the remaining capacity of the softener.
If one and one half times the historical usage for the next calendar
day is greater than the remaining capacity, a regeneration is scheduled.
If it is not greater, a regeneration is not scheduled.
The method of this invention also involves a variable capacity
calculation which is based upon a variable reserve and a variable
salt dosage. For a particular water softener resin bed, five index
capacities (I.sub.c) are established. For the initial regeneration
of the resin bed, the middle or third out of 5 index levels is chosen.
The variable capacity feature permits the regeneration of the softener
to be adjusted to the water hardness and usage pattern of a particular
installation. The decision to change the index capacity is based
upon the following formula:
Where:
H.sub.n =Historical number of days between regenerations
N.sub.d =Number of days since a regeneration
FIG. 8 schematically represents the routine for making the variable
capacity adjustment in accordance with one aspect of the method
of this invention. A new historic number of days between regenerations
is calculated in accordance with the formula set forth above. If
the new historic number of days between regenerations is less than
two and the index capacity is less than five, the index capacity
is increased by one. That is, if the index capacity were at the
initialization level of three, it would be increased to four. If
the new historic number of days is not less than two and the index
capacity not less than five, but the historic number of days is
greater than five and the index capacity greater than one, the index
capacity is decreased by one. That is, if the index capacity were
at the initialization value of three, it would be decreased to two.
The newly determined index capacity is then utilized in still another
step in the method of this invention, i.e., that of a salt and water
adjustment.
Assuming that there is enough salt available to create a saturated
brine solution of any amount of water to be used as brine, the salt
dosage may be adjusted by adjusting the amount of water utilized
to form the saturated brine. At the time of regeneration, there
will typically be, and in fact should be, in accordance with the
method of this invention, softening capacity remaining. That is,
the progress should always be less than 100% when a regeneration
is scheduled. The remaining or residual capacity of the resin bed
may be expressed in terms of the amount of salt (or saturated brine)
required to provide the remaining or residual capacity in the resin
bed. It being desirable to only use the amount of salt required
to restore the softener to its original capacity, the residual or
remaining capacity should be taken into account so as to reduce
the amount of salt used. The residual salt content for a high percentage
progress (that is, the resin bed approaching exhaustion) can be
approximated as:
SR=(100-P) / 100 * OPC / TCS
Where: SR=Residual salt
P=Progress to exhaustion (expressed in percentage)
OPC=Operating capacity (in grains)
TCS=Theoretical capacity of salt (5995 grains/lb)
The adjusted salt dosage (SDA) is then determined by subtracting
the residual salt (SR) from the operating salt dosage (OPS) which
may be expressed as follows:
Referring to FIG. 9 a schematic representation of the routine
implemented by a microprocessor for determining the salt dosage
to be used for the next regeneration is set forth. If the progress
since the last regeneration is less than 60%, the salt dosage to
be used to restore the softener should be at the lowest level, or
number 1. However, if the progress since the last regeneration is
greater than 60%, but less than 70%, the second salt dosage should
be used. Similarly, if the progress is greater than 70% but less
than 80%, the third salt dosage level should be used. If the salt
dosage is greater than 80% but less than 90%, the fourth salt dosage
level is used. Finally, if the progress since the last regeneration
is greater than 90%, the fifth salt dosage level is used for the
next regeneration.
Referring to FIG. 10 a schematic representation of the overall
routine for scheduling the occurrence and controlling the variables
of a regeneration in accordance with all aspects of the method of
this invention is set forth.
As indicated in the schematic representation, the index capacity
is set at 3 the number of days between regeneration at 3 historical
number of days at 3.56 and historic days usage at 15%. If it is
the initial regeneration, the softener is merely regenerated and
returned to service. The capacity used is measured and at the next
scheduled regeneration time, a decision is made in accordance with
the first aspect of this invention, as set forth in the schematic
representation of FIG. 6 as to whether or not a regeneration should
be scheduled. If a regeneration is not scheduled in accordance with
the first aspect, the usage is then utilized in determining whether
or not a regeneration should be scheduled in accordance with the
second aspect. If a regeneration is scheduled in accordance with
either aspect, the variable capacity adjustment, in accordance with
the schematic representation of FIG. 8 is made so as to provide
a salt and water adjustment, as set forth in the schematic of FIG.
9. The resin bed is then regenerated and returned to service. If
a decision is made not to regenerate in accordance with the second
aspect of the method, one day is added to the number of days between
regeneration for use in considering regeneration at the next scheduled
time.
It should be apparent to those skilled in the art, that while what
has been described is considered at present to be a preferred embodiment
of the method for regeneration of a water softener of this invention,
in accordance with the patent statutes, changes may be made in the
method without actually departing from the true spirit and scope
of this invention.
The appended claims are intended to cover all such changes and
modifications which fall within the true spirit and scope of this
invention. |