Abstrict A liquid desiccant regeneration system for use with a dehumidifying
apparatus, the system comprising a water reducer for removing water
from diluted desiccant, and a sump for holding concentrated desiccant,
first and second bodies movable in the sump, a first of the bodies
being operable to energize the water reducer when the desiccant
in the sump reaches a selected high water content level, and a second
of the bodies being operable to stop operation of the water reducer
when the desiccant in the sump reaches a selected low water content
level, whereby to maintain the water content of the desiccant in
the sump between selected high and low levels.
Claims Having thus described our invention, what we claim as new and desire
to secure by Letters Patent of the United States is:
1. A liquid desiccant regeneration system for use with a dehumidifying
apparatus, said system comprising a sump, a water reduction means
adapted to remove water from the desiccant, a supply pipe interconnecting
said water reduction means and said sump for conveying desiccant
from said water reduction means to said sump, a return pipe interconnecting
said sump and said water reduction means for conveying desiccant
from said sump to said water reduction means, first and second flotation
bodies movable in the desiccant in said sump, first switch means
for starting said water reduction means, second switch means for
stopping said water reduction means, the first of said bodies having
thereon means for tripping said first switch means, said first body
being operable in response to movement thereof in the desiccant
in said sump to trip said first switch means to energize said water
reduction means when said desiccant in said sump reaches a selected
high water content level, and the second of said bodies having thereon
means for tripping said second switch means, said second body being
operable in response to movement thereof in said desiccant in said
sump to trip said second switch means to stop operation of said
water reduction means when said desiccant in said sump reaches a
selected low water content level, whereby to maintain said water
content of said desiccant in said sump between said selected high
and low water content levels.
2. The liquid desiccant regeneration system in accordance with
claim 1 in which said water reduction means comprises a boiler adapted
to vaporize moisture content of said desiccant therein, said boiler
having means for discharging said vaporized moisture.
3. The liquid desiccant regeneration system in accordance with
claim 1 wherein said first body is of a density more than a lowest
density desired for said desiccant in said sump, and said second
body is of a density less than a highest density desired for said
desiccant in said sump.
4. A liquid desiccant regeneration system for use with a dehumidifying
apparatus, said system comprising means for reducing water content
of desiccant to increase the density of said desiccant, a sump for
retaining desiccant acted upon by said water content reducing means,
conduit means extending from said means for reducing water supply
content to said sump and adapted to convey desiccant from said means
for reducing water content to said sump, a return conduit extending
from said sump to said water content reducing means for conveying
desiccant from said sump to said water content reducing means, first
and second flotation bodies disposed in and freely movable in said
desiccant in said sump, a first of said bodies having a selected
first density greater than a lowest density desired for said desiccant
in said sump, a second of said bodies having a selected second density
less than a highest density desired for said desiccant in said sump,
said first body having thereon means for tripping a first switch
means, said second body having thereon means for tripping a second
switch means, said first switch means being operatively connected
to said first body switch tripping means and to said water content
reducing means, and said second switch means being operatively connected
to said second body switch tripping means and said water content
reducing means, whereby upon accretion of water content in said
desiccant in said sump to a point at which said density of said
desiccant is less than said first density, said first body is adapted
to move in a first direction to cause said first body switch tripping
means to operate said first switch means to initiate operation of
said water content reducing means, and whereby upon reduction of
water content of said desiccant in said sump to a point at which
said density of said desiccant is more than said second density,
said second body is adapted to move in a second direction to cause
said second body switch tripping means to operate said second switch
means to stop operation of said water reducing means, whereby to
maintain the density of said desiccant in said sump substantially
between first and second water content levels.
5. The liquid desiccant regeneration system in accordance with
claim 4 wherein said first body means for tripping said first switch
means and said second body means for tripping said second switch
means each comprise a cord.
6. The liquid desiccant regeneration system in accordance with
claim 4 and further including a circulating pump disposed in said
return conduit, said first and second switch means being operatively
connected to said circulating pump and adapted to turn on said circulating
pump when said operation of said water content reducing means is
initiated, and adapted to turn off said circulating pump when said
operation of said water content reducing means is stopped.
7. The liquid desiccant regeneration system in accordance with
claim 4 in which said first direction is toward a bottom of said
sump and said second direction is toward a top of said sump.
8. The liquid desiccant regeneration system in accordance with
claim 7 in which said lowest and highest densities are equal, respectively,
to aqueous LiCl desiccant concentrations of about 38%-44%.
9. The liquid desiccant regeneration system in accordance with
claim 8 in which said selected first density corresponds to an aqueous
LiCl desiccant concentration of about 38.5% and said selected second
density corresponds to an aqueous LiCl desiccant concentration of
about 43.5%.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid desiccant regenerating systems
for use with dehumidifying apparatus, and is directed more particularly
to a system for maintaining the water content of desiccant within
a selected range.
2. Description of the Prior Art
The use of liquid desiccants, such as lithium chloride and calcium
chloride, for dehumidifying air is well known. In the course of
removing water from the air, the desiccant absorbs moisture, becomes
diluted, and must be regenerated, that is, must be stripped of its
water content to a degree such that the desiccant is relatively
concentrated and more readily able to absorb moisture from the air.
Regeneration usually requires heating the desiccant to drive off
the excess water. Alternatively, a hot gas may be passed over the
desiccant to absorb the excess moisture. Another alternative regeneration
method includes heating the desiccant and passing a gas through
the desiccant. In one typical application, the desiccant is conveyed
to a boiler, where the dilute liquid desiccant is heated and the
excess moisture is removed in the form of steam. The resulting concentrated
desiccant is then conveyed, though heat exchange means, to a desiccant
reservoir, or sump, from which the desiccant is drawn for dehumidifying
operations.
In such systems, it is critical that the proper concentration of
desiccant be discharged from the sump for use in the dehumidifying
system.
In systems in common use, a level sensor and switch monitors the
level of desiccant in the sump, but not the concentration, or density,
of the desiccant. In the event of a desiccant leak or overcharge,
the sensors detect the change in level, which is interpreted to
indicate an erroneous desiccant concentration.
It is deemed desirable to have available a system by which the
density, and thereby water content, of the desiccant is maintained
in a desired range, without regard to the level of the desiccant
in the desiccant sump.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide a desiccant
regeneration system having means for automatically maintaining the
water content of the desiccant within a pre-selected range.
With the above and other object in view, as will hereinafter appear,
a feature of the present invention is the provision of a liquid
desiccant regeneration system for use with a dehumidifying apparatus,
the system comprising water reduction means adapted to receive a
dilute desiccant, remove water from the desiccant, and discharge
a relatively concentrated desiccant, a sump for holding the desiccant,
first and second bodies disposed in the sump and freely movable
therein, a first of the bodies being operable to energize the water
reduction means when the desiccant in the sump reaches a selected
high water content level, and a second of the bodies being operable
to stop operation of the water reduction means when the desiccant
in the sump reaches a selected low water content level, whereby
to maintain the water content of the desiccant in the system between
the selected high and low water content levels.
The above and other features of the invention, including various
novel details of construction and combinations of parts, will now
be more particularly described with reference to the accompanying
drawings and pointed out in the claims. It will be understood that
the particular device embodying the invention is shown by way of
illustration only and not as a limitation of the invention. The
principles and features of this invention may be employed in various
and numerous embodiments without departing from the scope of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is made to the accompanying drawing in which is shown
an illustrative embodiment of the invention, from which its novel
features and advantages will be apparent.
In the drawings:
FIG. 1 is a diagrammatic representation of a liquid desiccant regeneration
system illustrative of an embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing, it will be seen that an illustrative
embodiment of the invention includes a means 2 for reducing the
water content of desiccant 4. The water content reducing means 2
may comprise a boiler 6 as shown diagrammatically in FIG. 1 or
may comprise an alternative means for reducing water content of
desiccant, such as a hot gas flow apparatus adapted to flow a heated
gas over the desiccant to absorb moisture from the desiccant (not
shown). The boiler 6 includes a tank 8 for holding a quantity of
the desiccant 4 heat supply means 10 for heating the desiccant
4 and vent means 12 for discharging the separated moisture in the
form of steam. A water reduction switch means 14 is operative to
start and stop the heat supply means 10. Operation of the heat supply
means 10 serves to vaporize moisture in the desiccant 4 to reduce
the water content of the desiccant, thereby to increase the concentration
and density of the desiccant, thereby to enhance the ability of
the desiccant subsequently to absorb moisture.
The system further includes a sump 20 adapted to receive and retain
desiccant 4' acted upon by the water content reducing means 2. A
supply conduit 22 interconnects the boiler tank 8 and the sump 20
and facilitates the flow of relatively concentrated desiccant from
the water content reducing means 2 to the sump 20.
Disposed in the sump 20 are first and second flotation bodies 24
26 which, in the embodiment shown in the drawing, are freely movable
in the sump 20. The first 24 of the flotation bodies is provided
with a selected first density which exceeds the lowest density desired
for the desiccant 4' in the sump. The second 26 of the flotation
bodies is provided with a selected second density which is less
than the highest density desired for the desiccant 4'.
The first body 24 is operatively connected, as by a first cord
28 to a first switch 30 which in turn is operatively connected
to the water reduction switch means 14 and to a circulating pump
32 in a return conduit 34 adapted to convey desiccant from the sump
20 to the water content reduction means 2.
Similarly, the second body 26 is operatively connected, as by a
second cord 36 to a second switch 38 which in turn is operatively
connected to the water reduction switch means 14 and to the circulating
pump 32.
The sump 20 is provided with a discharge conduit 40 through which
the relatively concentrated desiccant 4' of the sump 20 is moved
by a feed pump 42 from the sump 20 to a dehumidifying apparatus
44. The dehumidifying apparatus 44 is provided with a drain 46
which facilitates return of the desiccant from the dehumidifying
apparatus 44 to the sump 20. In the apparatus 44 the desiccant
absorbs moisture from the air being dehumidified and returns to
the sump 20 in a less concentrated condition than when it left the
sump.
The supply and return conduits 22 34 typically are passed through
a heat exchanger 48 so that the desiccant leaving the water content
reducing means 2 is cooled before entering the sump 20 and the
desiccant leaving the sump 20 is heated before entering the water
content reducing means 2.
In operation, relatively concentrated desiccant is conveyed from
the boiler tank 8 to the sump 20 by way of the supply conduit 22
and from and the sump 20 by way of the discharge conduit 40 to
the dehumidifying apparatus 44 from whence the desiccant drains
back into the sump 20 in a less concentrated condition, having
gained moisture from the air in the apparatus 44.
It is desirable to maintain the concentration of lithium chloride
(LiCl) desiccant in the sump in a range of about 38%-44%. As the
desiccant draining from the dehumidifying apparatus lowers the concentration,
and thereby the density, of the desiccant in the sump, the first
flotation body 24 which is of a density greater than that of 38%
LiCl, say equivalent to 38.5% LiCl for example, becomes more dense
relative to the desiccant. When the density of the desiccant passes
38.5% while dropping, the first flotation body 24 becomes more dense
that the desiccant and sinks toward the bottom of the sump 20. Continued
sinking of the body 24 pulls the core 28 which operates the first
switch 30 which, in turn, operates the water reduction switch means
14 to turn on the water content reducing means, and starts the circulating
pump 32 to convey desiccant from the sump 20 to the water content
reducing means 2. In the water reducing means 2 water is removed
from the desiccant which is returned, more concentrated, to the
sump 20 causing the concentration of the desiccant in the sump
20 to rise and the first flotation body 24 to rise.
The second flotation body 26 is provided with a density of less
than that of 44% LiCl, as for example equivalent to 43.5% LiCl,
so that at the density of the desiccant in the sump 20 increases,
the second flotation body becomes less dense relatively to the desiccant.
When the density of the desiccant passes 43.5% while rising, the
second flotation body 26 becomes less dense that the desiccant and
rises toward the top of the sump 20. Continued rising of the body
26 pulls the cord 36 which operates the second switch 38 which,
in turn, operates the water reduction means switch 14 to turn off
the water content reducing means, and to stop operation of the circulating
pump 32. The system then remains at rest until the concentration
of the desiccant in the sump again falls to just over 38.0%.
Thus, there is provided a system for maintaining the concentration
of the desiccant in a preselected range, the system being independent
of the level of the desiccant in the sump.
It is to be understood that the present invention is by no means
limited to the particular construction herein disclosed and/or shown
in the drawings, but also comprises any modifications or equivalents
within the scope of the claims. For example, the flotation bodies
may be slidably disposed on vertical rods and adapted to actuate
switches at given points in their travels along their respective
rods. In another alternative embodiment, the vertical position of
the bodies are detected by photo-electric cells which operate the
circulating pump and water content reducer heating means. While
a system utilizing LiCl has been described above, it will be apparent
that other desiccants may be used and that desired concentrations
and densities of such alternative desiccants may well be substantially
different from those noted above relative to LiCl. |