Abstrict A liquid desiccant dehumidifier includes a liquid desiccant absorber
arranged to receive concentrated liquid desiccant and absorb moisture
contained in ambient air passed through the absorber thereby diluting
the liquid desiccant. A first heat exchanger is operative to heat
dilute liquid desiccant received from the desiccant absorber prior
to passage to a boiler that evaporates moisture from the diluted
liquid desiccant to create steam and reconstitute the desiccant
into a concentrated liquid desiccant. Dilute liquid desiccant from
the first heat exchanger first passes to a condenser that receives
steam from the boiler and sensibly heats the dilute liquid desiccant
to a higher second temperature without direct exposure to steam
or air. A second heat exchanger communicates with the condenser,
the boiler and the first heat exchanger and is operative to further
heat diluted liquid desiccant received from the condenser to a higher
third temperature prior to entry into the boiler by recovering waste
heat from the boiler. A pump draws concentrated liquid desiccant
from the boiler through the heat exchangers and passes it to the
absorber.
Claims What is claimed is:
1. A liquid desiccant dehumidifier for absorbing moisture contained
in ambient air, said dehumidifier comprising, in combination:
a liquid desiccant absorber adapted to enable passage of ambient
air through said desiccant absorber and being operative to receive
concentrated liquid desiccant so as to absorb moisture contained
in the ambient air and dispense dilute liquid desiccant;
a boiler operatively associated with said absorber to receive and
boil dilute liquid desiccant to remove moisture in the form of steam
from said liquid desiccant to reconstitute the dilute liquid desiccant
into concentrated liquid desiccant; and
a condenser communicating with said boiler and said absorber so
as to receive steam from said boiler and receive dilute liquid desiccant
from said absorber, said condenser being operative to recover latent
heat of condensation from said steam so as to sensibly heat said
dilute liquid desiccant prior to entry into said boiler without
directly exposing said dilute liquid desiccant to air.
2. The liquid desiccant dehumidifier as defined in claim 1 further
including a heat exchanger fluidly communicating with said desiccant
absorber, said condenser and said boiler so as to receive concentrated
liquid desiccant from said boiler and dilute liquid desiccant from
said desiccant absorber, said heat exchanger being operative to
transfer heat from said concentrated liquid desiccant to said dilute
liquid desiccant and deliver preheated dilute liquid desiccant to
said condenser.
3. The liquid desiccant dehumidifier recited in claim 2 wherein
said heat exchanger comprises at least one tube assembly including
an inner tube concentrically disposed within an outer tube to define
an annulus therebetween.
4. The liquid desiccant dehumidifier recited in claim 3 wherein
dilute liquid desiccant from said desiccant absorber is passed through
said inner tube, and concentrated liquid desiccant is passed through
said annulus.
5. The liquid desiccant dehumidifier recited in claim 3 wherein
dilute liquid desiccant from said desiccant absorber is passed through
said annulus, and concentrated liquid desiccant is passed through
said inner tube.
6. The liquid desiccant dehumidifier recited in claim 3 wherein
said inner tube is fabricated from polytetrafluoroethyline, and
said outer tube is fabricated from silicone rubber.
7. The liquid desiccant dehumidifier recited in claim 2 wherein
said heat exchanger comprises at least one tube assembly including
an inner tube fabricated from polytetrafluoroethyline concentrically
disposed within an outer tube fabricated from silicone rubber to
define an annulus therebetween.
8. A liquid desiccant dehumidifier as defined in claim 1 further
including a heat exchanger fluidly communicating with said condenser,
said boiler and said desiccant absorber so as to receive concentrated
liquid desiccant from said boiler and heated dilute liquid desiccant
from said condenser, said heat exchanger being operative to transfer
heat from said concentrated liquid desiccant to said heated dilute
liquid desiccant to further preheat the dilute liquid desiccant
prior to delivery to said boiler, said heat exchanger being disposed
with respect to said boiler to recover waste heat from said boiler.
9. The liquid desiccant dehumidifier recited in claim 8 wherein
said heat exchanger comprises at least one tube assembly including
an inner tube fabricated from polytetrafluoroethyline concentrically
disposed within an outer tube fabricated from silicone rubber to
define an annulus therebetween.
10. A liquid desiccant dehumidifier as defined in claim 1 wherein
said desiccant absorber has a top and a bottom and includes a plurality
of horizontally and vertically disposed plates between said top
and bottom, said plates being capable of wetting by desiccant, a
distributor disposed above said plates for introducing concentrated
desiccant into said desiccant absorber, and a drain pan for collecting
dilute desiccant at said bottom of said desiccant absorber.
11. A liquid desiccant dehumidifier as defined in claim 10 wherein
said plates comprise microglass fiber plates.
12. The liquid desiccant dehumidifier recited in claim 1 wherein
said condenser comprises an inner shell disposed within an outer
housing defining at least one chamber between said inner shell and
said housing.
13. The liquid desiccant dehumidifier recited in claim 12 wherein
said inner shell is fabricated from materials selected from the
group including inconel, monel, titanium, polytetrafluoroethyline,
polytetrafluoroethyline-coated copper, polytetrafluoroethyline-coated
aluminum, and polytetrafluoroethyline-coated stainless steel; and
said outer shell is fabricated from materials selected from the
group of polytetrafluoroethyline, polycarbonate, polyvinylidene
fluoride, polypropylene, silicone rubber, polyethylene, and polystyrene.
14. The liquid desiccant dehumidifier recited in claim 12 wherein
said condenser further comprises at least one steam inlet communicating
steam from said boiler with said at least one chamber and at least
one solution inlet communicating dilute liquid desiccant with said
inner shell.
15. The liquid desiccant dehumidifier recited in claim 12 wherein
said condenser further comprises at least one steam inlet communicating
steam from said boiler with said inner shell and at least one solution
inlet communicating dilute liquid desiccant with said at least one
chamber.
16. The liquid desiccant dehumidifier recited in claim 12 wherein
said inner shell divides said housing into two separate compartments,
each compartment having a steam inlet and a condensate outlet, said
housing further comprising a plurality of baffles to prevent short
circuiting from said steam inlets to said condensate outlets.
17. The liquid desiccant dehumidifier recited in claim 1 wherein
said condenser comprises a housing and a plurality of tubes, said
tubes being supported by opposing support plates, said tubes communicating
with a steam inlet to receive steam from said boiler, said housing
including a solution inlet to receive dilute liquid desiccant.
18. The liquid desiccant dehumidifier as defined in claim 17 wherein
said tubes comprise convoluted or corrugated tubes.
19. The liquid desiccant dehumidifier recited in claim 17 wherein
said tubes are fabricated from polytetrafluoroethyline, and said
support plates have at least one silicone rubber sheet attached
thereto.
20. The liquid desiccant dehumidifier recited in claim 1 further
comprising a frame fabricated from materials selected from the group
of polypropylene, polyethylene, polytetrafluoroethyline, polyvinylidene
fluoride, polycarbonate, PVC and polystyrene.
21. The liquid desiccant dehumidifier recited in claim 1 wherein
said liquid desiccant is selected from the group including aqueous
LiCl, LiBr and CaCl.sub.2.
22. The liquid desiccant dehumidifier as defined in claim 21 wherein
said liquid desiccant comprises a mixture of at least two of the
group including aqueous LiCl, LiBr and CaCl.sub.2.
23. The liquid desiccant dehumidifier recited in claim 1 wherein
said boiler includes a vessel fabricated from plastic.
24. The liquid desiccant dehumidifier recited in claim 23 wherein
said plastic is selected from the group of including polytetrafluoroethyline,
polycarbonate, and polyvinylidene fluoride.
25. The liquid desiccant dehumidifier recited in claim 1 further
comprising means for pumping concentrated liquid desiccant into
said desiccant absorber.
26. A liquid desiccant dehumidifier comprising, in combination:
a liquid desiccant absorber for absorbing moisture contained in
ambient air passing through said desiccant absorber, said desiccant
absorber being adapted to receive concentrated liquid desiccant
and dispense dilute liquid desiccant;
a boiler for boiling dilute liquid desiccant to generate steam
by evaporating moisture from the liquid desiccant and reconstituting
it into concentrated liquid desiccant;
a condenser communicating with said boiler and said absorber so
as to receive steam generated by said boiler and receive dilute
liquid desiccant from said absorber, said condenser being operable
to sensibly heat the dilute liquid desiccant therein by recovering
the latent heat of condensation as steam received from said boiler
is condensed to thereby heat said dilute liquid desiccant prior
to delivery to said boiler; and
a heat exchanger communicating with said condenser, said boiler
and said absorber, said heat exchanger being operable to transfer
heat from concentrated liquid desiccant directed to said heat exchanger
from said boiler to the heated dilute liquid desiccant directed
to said heat exchanger from said condenser to further heat the dilute
liquid desiccant prior to delivery to said boiler, said heat exchanger
comprising at least one tube assembly including an inner tube concentrically
disposed within an outer tube to define an annulus therebetween,
said at least one tube assembly being coiled around said boiler
to recover waste heat from said boiler.
27. The liquid desiccant dehumidifier recited in claim 26 wherein
dilute liquid desiccant from said condenser is passed through said
inner tube, and concentrated liquid desiccant from said boiler is
passed through said annulus.
28. The liquid desiccant dehumidifier recited in claim 26 wherein
dilute liquid desiccant from said condenser is passed through said
annulus, and concentrated liquid desiccant from said boiler is passed
through said inner tube.
29. The liquid desiccant dehumidifier recited in claim 26 wherein
said inner tube is fabricated from Teflon, and said outer tube is
fabricated from silicone rubber.
30. A liquid desiccant dehumidifier comprising, in combination:
a liquid desiccant absorber for absorbing moisture contained in
ambient air passing through said desiccant absorber, said desiccant
absorber being operative to receive concentrated liquid desiccant
and dispense dilute liquid desiccant, a boiler for receiving and
boiling dilute liquid desiccant to evaporate moisture and generate
steam therefrom so as to reconstitute the liquid desiccant into
concentrated liquid desiccant;
a first heat exchanger adapted to receive dilute liquid desiccant
from said desiccant absorber and transfer heat to said dilute liquid
desiccant from concentrated liquid desiccant so as to raise the
temperature of the dilute liquid desiccant to a first temperature;
a condenser communicating with said boiler and said first heat
exchanger so as to receive steam generated by said boiler and dilute
liquid desiccant from said first heat exchanger at substantially
said first temperature, said condenser being operative to sensibly
heat the dilute liquid desiccant therein to a second temperature
by subjecting said dilute liquid desiccant to latent heat resulting
from condensation of steam received from said boiler without directly
exposing said dilute liquid desiccant to air,
a second heat exchanger communicating with said condenser, said
boiler and said first heat exchanger, said second heat exchanger
being operative to receive concentrated liquid desiccant from said
boiler and transfer heat to dilute liquid desiccant received from
said condenser so as to raise the temperature of the dilute liquid
desiccant to a third temperature, said dilute liquid desiccant at
the third temperature being directed to said boiler, and said concentrated
liquid desiccant from said boiler being directed to said first heat
exchanger, said second heat exchanger being disposed with respect
to said boiler to recover waste heat from said boiler; and
means for pumping concentrated liquid desiccant into said absorber.
31. The liquid desiccant dehumidifier recited in claim 30 wherein
said desiccant absorber includes a top and a bottom and comprises:
a plurality of horizontally and vertically disposed interconnected
microglass fiber plates; a distributor disposed above said fiber
plates at said top of said desiccant absorber for introducing the
concentrated desiccant into said desiccant absorber; and a drain
pan for collecting the dilute desiccant disposed at said bottom
of said desiccant absorber.
32. The liquid desiccant dehumidifier recited in claim 30 wherein
said first heat exchanger comprises at least one tube assembly including
an inner tube concentrically disposed within an outer tube to define
an annulus therebetween.
33. The liquid desiccant dehumidifier recited in claim 32 wherein
dilute liquid desiccant from said desiccant absorber is passed through
said inner tube, and said concentrated liquid desiccant is passed
through said annulus.
34. The liquid desiccant dehumidifier recited in claim 32 wherein
dilute liquid desiccant from said desiccant absorber is passed through
said annulus, and concentrated liquid desiccant is passed through
said inner tube.
35. The liquid desiccant dehumidifier recited in claim 32 wherein
said inner tube is fabricated from polytetrafluoroethyline, and
said outer tube is fabricated from silicone rubber.
36. The liquid desiccant dehumidifier recited in claim 30 wherein
said second heat exchanger comprises at least one tube assembly
including an
inner tube concentrically disposed within an outer tube to define
an annulus therebetween, said at least one tube assembly being coiled
around said boiler to recover said waste heat.
37. The liquid desiccant dehumidifier recited in claim 36 wherein
dilute liquid desiccant from said condenser is passed through said
inner tube and concentrated liquid desiccant from said boiler is
passed through said annulus.
38. The liquid desiccant dehumidifier recited in claim 36 wherein
dilute liquid desiccant from said condenser is passed through said
annulus and concentrated liquid desiccant from said boiler is passed
through said inner tube.
39. The liquid desiccant dehumidifier recited in claim 30 wherein
said condenser comprises an inner shell disposed within an outer
housing defining at least one chamber between said inner shell and
said housing.
40. The liquid desiccant dehumidifier recited in claim 39 wherein
said inner shell is fabricated from materials selected from the
group including inconel, monel, titanium, polytetrafluoroethyline,
polytetrafluoroethyline-coated copper, polytetrafluoroethyline-coated
aluminum, and Teflon-coated stainless steel; and said outer shell
is fabricated from materials selected from the group of Teflon,
polycarbonate, polyvinylidene fluoride, polypropylene, silicone
rubber, polyethylene, and polystyrene.
41. The liquid desiccant dehumidifier recited in claim 39 wherein
said condenser further comprises at least one steam inlet communicating
steam from said boiler with said at least one chamber and at least
one solution inlet communicating heated dilute liquid desiccant
from said first heat exchanger with said inner shell.
42. The liquid desiccant dehumidifier recited in claim 39 wherein
said condenser further comprises at least one steam inlet communicating
steam from said boiler with said inner shell and at least one solution
inlet communicating heated dilute liquid desiccant from said first
heat exchanger with said at least one chamber.
43. The liquid desiccant dehumidifier recited in claim 39 wherein
said inner shell divides said housing into two separate compartments,
each compartment having a steam inlet and a condensate outlet, said
housing further comprising a plurality of baffles to prevent short
circuiting from said steam inlets to said condensate outlets.
44. The liquid desiccant dehumidifier recited in claim 30 wherein
said condenser comprises a housing and a plurality of tubes, said
tubes being supported by opposing support plates, said tubes communicating
with a steam inlet to receive steam from said boiler, said housing
including a solution inlet to receive dilute liquid desiccant from
said first heat exchanger.
45. The liquid desiccant dehumidifier recited in claim 44 wherein
said tubes comprise convoluted or corrugated tubes.
46. The liquid desiccant dehumidifier recited in claim 44 wherein
said tubes are fabricated from polytetrafluoroethyline, and said
support plates have at least one silicone rubber sheet attached
thereto.
47. The liquid desiccant dehumidifier recited in claim 30 further
comprising a frame fabricated from materials selected from the group
including polypropylene, polyethylene, polytetrafluoroethyline,
polyvinylidene fluoride, polycarbonate, PVC and polystyrene.
48. The liquid desiccant dehumidifier recited in claim 30 wherein
said liquid desiccant is selected from the group including aqueous
LiCl, LiBr and CaCl.sub.2.
49. The liquid desiccant dehumidifier recited in claim 48 wherein
said liquid desiccant is a mixture of at least two of aqueous LiCl,
LiBr and CaCl.sub.2.
50. The liquid desiccant dehumidifier recited in claim 30 wherein
said boiler includes a vessel fabricated from plastic.
51. The liquid desiccant dehumidifier recited in claim 50 wherein
said plastic is selected from the group including polytetrafluoroethyline,
polycarbonate, and polyvinylidene fluoride.
52. A liquid desiccant dehumidifier comprising, in combination:
a liquid desiccant absorber for absorbing moisture contained in
ambient air entering the dehumidifier and passing through said desiccant
absorber, said desiccant absorber being constructed and arranged
for receiving concentrated liquid desiccant and dispensing dilute
liquid desiccant,
a boiler for boiling dilute liquid desiccant to evaporate moisture
to reconstitute the liquid desiccant into concentrated liquid desiccant;
a first heat exchanger operable to transfer heat from concentrated
liquid desiccant to dilute liquid desiccant directed to said first
heat exchanger from said desiccant absorber so as to raise the temperature
of the dilute liquid desiccant to a first temperature, said first
heat exchanger being disposed below said desiccant absorber to enable
dilute liquid desiccant from said absorber to be gravity fed to
said first heat exchanger;
a condenser fluidly communicating with said boiler to receive steam
generated by boiling liquid desiccant in said boiler, said condenser
further fluidly communicating with said first heat exchanger to
receive dilute liquid desiccant from said first heat exchanger at
substantially said first temperature, said condenser being operable
to sensibly heat the dilute liquid desiccant therein to a second
temperature by recovering the latent heat of condensation as steam
received from said boiler is condensed, said condenser being configured
to sensibly heat said dilute liquid desiccant without directly exposing
said liquid desiccant to air, said condenser being disposed below
said first heat exchanger to enable dilute liquid desiccant from
said first heat exchanger to be gravity fed to said condenser;
a second heat exchanger fluidly communicating with said condenser,
said boiler and said first heat exchanger, said second heat exchanger
being operable to transfer heat from concentrated liquid desiccant
directed to said second heat exchanger from said boiler to the dilute
liquid desiccant directed to said second heat exchanger from said
condenser at said second temperature to raise the temperature of
the dilute liquid desiccant to a third temperature, said dilute
liquid desiccant at the third temperature being directed to said
boiler, said second heat exchanger being disposed with respect to
said boiler to recover waste heat from said boiler and being disposed
below said condenser to enable dilute liquid desiccant from said
condenser to be gravity fed to said second heat exchanger and to
said boiler; and
means for pumping concentrated liquid desiccant to said absorber.
53. An interchange heat exchanger, comprising:
at least one tube assembly including an inner flow tube fabricated
solely from polytetrafluoroethyline concentrically disposed within
an outer flow tube so as to define as annulus therebetween, said
outer flow tube being fabricated from a heat insulating material
selected from a group including silicon rubber, said inner and outer
flow tubes being operative to facilitate heat transfer between a
first liquid passed through said inner flow tube and a second liquid
passed through said annulus.
54. A interchange heat exchanger as defined in claim 53 wherein
said inner tube is formed as a circumferentially convoluted or corrugated
tube to enhance heat transfer.
55. A method for absorbing moisture from ambient air, said method
comprising the steps of;
passing the ambient air through a concentrated liquid desiccant
so as to remove moisture from the ambient air and create dilute
liquid desiccant,
boiling the dilute liquid desiccant to remove moisture therefrom
in the form of steam and reconstitute the dilute liquid desiccant
into heated concentrated liquid desiccant,
recovering latent heat of condensation from said steam and utilizing
said heat to sensibly heat said dilute liquid desiccant prior to
boiling said dilute liquid desiccant to remove moisture therefrom,
said sensible heating being effected without directly exposing the
dilute liquid desiccant to air.
56. The method as defined in claim 55 including the step of preheating
said dilute liquid desiccant prior to said sensible heating thereof.
57. The method as defined in claim 56 wherein said step of preheating
said dilute liquid desiccant includes transferring heat to said
dilute liquid desiccant from said heated concentrated liquid desiccant.
58. The method as defined in claim 56 wherein said step of boiling
said dilute liquid desiccant includes passing said dilute liquid
desiccant into a boiler, and including the step of utilizing waste
heat from said boiler to further preheat said dilute liquid desiccant
prior to boiling thereof.
59. The method as defined in claim 55 including the step of transferring
heat to the dilute liquid desiccant so as to further heat the dilute
liquid desiccant after said step of sensibly heating said dilute
liquid desiccant but prior to said step of boiling the dilute liquid
desiccant.
60. The method as defined in claim 59 wherein said step of boiling
said dilute liquid desiccant is carried out in a boiler, said step
of transferring heat to the dilute liquid desiccant after said step
of sensibly heating said dilute liquid desiccant including transferring
heat to said dilute liquid desiccant from heated concentrated liquid
desiccant as reconstituted in said boiler.
61. The method as defined in claim 60 wherein said step of transferring
heat to the dilute liquid desiccant after said step of sensibly
heating said dilute liquid desiccant further includes transferring
heat to said dilute liquid desiccant from waste heat from said boiler.
62. A method for absorbing moisture contained in ambient air, said
method comprising the steps of:
passing ambient air through a liquid desiccant absorber having
concentrated liquid desiccant therein operative to absorb moisture
contained in the ambient air so as to create dilute liquid desiccant;
passing the dilute liquid desiccant from the absorber to a boiler
operative to boil the dilute liquid desiccant to remove moisture
in the form of steam and reconstitute the dilute liquid desiccant
into concentrated liquid desiccant;
passing steam from the boiler to a condenser;
passing dilute liquid desiccant from the absorber to said condenser
prior to passage to said boiler, said condenser being operative
to recover latent heat of condensation from said steam and sensibly
heat the dilute liquid desiccant without directly exposing the dilute
liquid desiccant to air; and
passing said heated dilute liquid desiccant from the condenser
to the boiler.
Description BACKGROUND
1. Field of the Invention
The present invention relates generally to room air dehumidification,
and more particularly, to a liquid desiccant dehumidifier which
is portable, energy efficient, and corrosion resistant.
2. Description of the Prior Art
It is known in the art to dehumidify ambient air using liquid desiccant
systems. These devices typically utilize hygroscopic liquids such
as lithium bromide (LiBr), lithium chloride (LiCl) or calcium chloride
(CaCl.sub.2) as the desiccant solution. Desiccant units offer advantages
over commercial dehumidifiers based on vapor compression technology,
specifically in terms of lower energy usage.
In a desiccant system, the desiccant solution absorbs moisture
from ambient air exposed to the solution. As the desiccant solution
continues to absorb moisture, it becomes dilute and must be regenerated.
In the regeneration process, the desiccant solution is heated to
evaporate the excess moisture or the desiccant solution is brought
into contact with a hot gas to desorb the excess moisture. In some
expedients, air regenerators are used to regenerate the desiccant.
These arrangements have relatively high operating costs as energy
is required to provide a source of heat and to generate a suitable
flow of air. In others, boiler-type regenerators are employed. However,
boiler embodiments are expensive, as the corrosive nature of liquid
desiccant solutions necessitates the use of costly corrosion resistant
metals.
A liquid desiccant dehumidfication system in which a liquid desiccant
is regenerated with a boiler is described in U.S. Pat. No. 4939906
("the '906 patent"). The '906 patent discloses a gas-fired
desiccant boiler and a combined desiccant regenerator/interchange
heat exchanger, in which the combined regenerator/heat exchanger
utilizes steam produced from the boiler to provide heat for partial
regeneration. The desiccant boiler has a liquid/vapor separator
chamber and thermosyphon recirculation to reduce scale and corrosion
of the boiler. Specifically, the overall system is shown in FIG.
1 wherein outdoor air is drawn into the system through an inlet
duct 22 and is evaporatively cooled by a water spray 24. The cooled
air is directed to a desiccant conditioner 26 to which return air
is also directed through a duct 30. In the desiccant conditioner
26 the return air is contacted with a liquid desiccant solution
from a sprayer 28. The desiccant liquid is disclosed as lithium
calcium chloride.
This dehumidified air is then supplied to the space to be dehumidified,
or it can be sensibly cooled through an evaporative cooler 32. The
desiccant dehumidifies the air stream, and in the process its moisture-absorbing
capability is reduced; this capability is regenerated by passing
a portion of the dilute desiccant from the conditioner 26 to a first
interchange heat exchanger 44 wherein the temperature of the desiccant
is raised. The weakened desiccant is partially concentrated in an
air-desiccant regenerator 46 in which heated air from a regeneration
air heater 48 contacts the liquid desiccant. This desiccant is pumped
through a second interchange heat exchanger 52 and thereafter to
a desiccant boiler 56 in which regeneration of the desiccant is
completed. The water vapor generated in the desiccant boiler 56
raises the temperature of the air passing through the regeneration
air preheater 48. The interchange heat exchangers 44 52 reduce
the temperature of the regenerated desiccant as it returns along
the pipe 60 to the conditioner 26.
The boiler 56 is depicted in FIG. 2 and operates on natural circulation,
with the density of the fluid (part liquid, part vapor) in the "fired"
tubes 70 being less than the density of the liquid in the outer
"unfired" tube 74. A porous ceramic burner 80 facilitates
combustion to provide a heat source and hot combustion gases are
blown through a combustion chamber formed by a housing 88 enclosing
the fired tubes 70 and flow across fins 90 of the fired tubes 70.
Weak desiccant is pumped into the fired tubes 70 through a manifold
94 which causes water in the desiccant to be vaporized. Accordingly,
a density differential is created between the fluid in the fired
tubes 70 and the unfired tubes 74 connected between the manifold
94 and a liquid/vapor separator 98 outside the combustion chamber
housing 88. This density differential induces a natural flow of
desiccant solution up the fired tubes 70 and down the unfired tubes
72. In this manner, the natural circulation of desiccant keeps the
inside walls of the fired tubes 70 coated with desiccant to thereby
reduce or prevent "hot spots" from forming on the inside
of the fired tubes 70 to reduce corrosion and scale build up in
the fired tubes 70.
The liquid vapor separator 98 at the top of the boiler 56 separates
water vapor from the concentrated liquid desiccant. A portion of
the concentrated desiccant is withdrawn from the bottom of the liquid/vapor
separator 98 and is returned to the desiccant conditioner 26. Water
vapor flowing out of the top of the liquid/vapor separator 98 is
subsequently condensed to heat air for use in an earlier regeneration
step shown in FIGS. 3 and 4.
The combined regenerator/interchange heat exchanger, depicted in
FIGS. 3 and 4 comprises two (2) interchange heat exchangers 44
52 the desiccant regenerator 46 and the regeneration air heater
48. The combined desiccant regenerator/interchange heat exchanger
is identified by the reference numeral 102 and is constructed by
alternately stacking two (2) different corrugated plates (see FIG.
4) to define alternating flow channels. Water vapor or steam from
the desiccant boiler 56 is introduced near the top of the regenerator/exchanger
102 in alternate channels (plate A). This water vapor is condensed,
thereby transferring heat to the air and weak desiccant entering
adjacent channels near the top of the regenerator/heat exchanger
102 (plate B). The upper portion of each plate corresponds to the
desiccant regenerator 46 and regeneration air heater 48. As the
water vapor condenses, the weak desiccant and air mixture is heated
and the desiccant is partially regenerated. Warm air and moisture
are exhausted by fan 106 to the outdoors. An entrainer 108 is provided
to prevent desiccant from escaping the combined regenerator/exchanger
102. The partially regenerated desiccant flows into the middle of
a channel plate B, and is further heated by the hot concentrated
desiccant removed from the liquid/ vapor separator 98. Hot concentrated
desiccant from the boiler 56 is introduced at the middle of plate
A while the partially regenerated desiccant is removed from the
middle of plate B. The partially regenerated desiccant is then pumped
to the desiccant boiler 56. Diluted desiccant from the regenerator/heat
exchanger 102 is introduced at the bottom of the plate A and is
heated by the hot desiccant from the boiler 56. The heated dilute
desiccant from the regenerator/heat exchanger 102 is then removed
from the center of plate B and pumped to the top of plate B.
The apparatus shown and described in the '906 patent suffers from
several disadvantages. The regeneration process described therein
requires the flow of hot air through the system in order to operate.
This necessitates the use of additional components such as fans,
air preheaters, and liquid/vapor separators, which adds system complexity.
Furthermore, the multiple stacked plate interchange heat exchanger
configuration is complex and takes up a relatively large amount
of space. This arrangement is not suitable for use in a small portable
unit.
SUMMARY OF THE INVENTION
In view of the disadvantages in the prior art, it is an object
of the present invention to provide a portable liquid desiccant
dehumidifier which efficiently regenerates the liquid desiccant
using a simple arrangement having a minimum number of components.
It is another object of the present invention to provide a portable
liquid desiccant dehumidifier which is energy efficient.
It is still another object of the present invention to provide
a portable liquid desiccant dehumidifier which utilizes primarily
plastic components to prevent corrosion.
It is yet another object of the present invention to provide a
portable liquid desiccant dehumidifier in which steam to desiccant
heat recovery takes place in a condenser.
It is a further object of the present invention to provide a portable
liquid desiccant dehumidifier in which plastic components are used
for the interchange heat exchangers.
It is yet another object of the present invention to provide a
portable liquid desiccant dehumidifier in which the waste heat radiating
from the boiler is utilized in an interchange heat exchanger for
desiccant regeneration.
It is still another object of the present invention to provide
a portable liquid desiccant dehumidifier having a boiler which is
primarily elongated in a horizontal orientation to minimize the
temperature gradient and consequent concentration differential in
the liquid desiccant.
It is yet another object of the present invention to provide a
portable liquid desiccant dehumidifier which is lightweight, energy
efficient, and inexpensive to manufacture.
It is a further object of the present invention to provide an improved
heat exchanger employing at least one TEFLON tube concentrically
disposed within a silicone rubber tube.
In accordance with the foregoing objects and additional objects
that will become apparent hereinafter, the present invention provides
a liquid desiccant dehumidifier, including a liquid desiccant absorber
for absorbing moisture contained in ambient air entering the dehumidifier
and passing through the desiccant absorber, the desiccant absorber
constructed and arranged for receiving concentrated liquid desiccant
and dispensing dilute liquid desiccant. A boiler is provided for
boiling partially preheated dilute liquid desiccant to evaporate
moisture to reconstitute the liquid desiccant into concentrated
liquid desiccant. A condenser fluidly communicates with the boiler
to receive steam generated by boiling liquid desiccant in the boiler,
and with the absorber to receive dilute liquid desiccant from the
absorber. The condenser is operable to sensibly heat the dilute
liquid desiccant therein by recovering the latent heat of condensation
as steam delivered from the boiler is condensed, to preheat the
dilute liquid desiccant prior to delivery to the boiler to increase
operating efficiency.
In a preferred embodiment, the invention provides a liquid desiccant
dehumidifier including a liquid desiccant absorber for absorbing
moisture contained in ambient air entering the dehumidifier and
passing through the desiccant absorber, the desiccant absorber constructed
and arranged for receiving concentrated liquid desiccant and dispensing
dilute liquid desiccant. A boiler is provided for boiling partially
preheated dilute liquid desiccant to evaporate moisture to reconstitute
the liquid desiccant into concentrated liquid desiccant. A first
heat exchanger fluidly communicates with the desiccant absorber
and a second heat exchanger. The first heat exchanger is operable
to transfer heat from the concentrated liquid desiccant to the dilute
liquid desiccant directed to the first heat exchanger from the desiccant
absorber to raise the temperature of the dilute liquid desiccant
to a first temperature. A condenser fluidly communicates with the
boiler to receive steam generated by boiling the liquid desiccant
in the boiler, and with the first heat exchanger to receive partially
heated dilute liquid desiccant from the first heat exchanger at
the first temperature. The condenser is operable to sensibly heat
the dilute liquid desiccant therein to a second temperature by recovering
the latent heat of condensation as steam delivered from the boiler
is condensed. The second heat exchanger fluidly communicates with
the condenser, the boiler and the first heat exchanger. The second
heat exchanger is operable to transfer heat from concentrated liquid
desiccant directed to the second heat exchanger from the boiler
to the dilute liquid desiccant directed to the second heat exchanger
from the condenser at the second temperature to raise the temperature
of the dilute liquid desiccant to a third temperature. The dilute
liquid desiccant at the third temperature is directed to the boiler
and the concentrated liquid desiccant from the second heat exchanger
is directed to the first heat exchanger. The second heat exchanger
is disposed with respect to the boiler to recover waste heat from
the boiler. A pump is provided for pumping concentrated liquid desiccant
into the absorber.
In a preferred embodiment, the desiccant absorber includes a top
and a bottom and comprises: a plurality of horizontally and vertically
disposed interconnected microglass fiber plates; a distributor disposed
above the fiber plates at the top of the desiccant absorber for
introducing the concentrated desiccant into the desiccant absorber;
and a drain pan for collecting the dilute desiccant disposed at
the bottom of the desiccant absorber.
The first heat exchanger comprises at least one tube assembly including
an inner tube concentrically disposed within an outer tube to define
an annulus therebetween. The dilute liquid desiccant from the desiccant
absorber is passed through the inner tube, and the concentrated
liquid desiccant is passed through the annulus, or vice-a-versa.
The second heat exchanger comprises at least one tube assembly
including an inner tube concentrically disposed within an outer
tube to define an annulus therebetween. The tube assembly is coiled
around the boiler to recover waste heat passing through the walls
of the boiler. The concentrated liquid desiccant from the boiler
is passed through the annulus and the partially heated dilute liquid
desiccant from the condenser is passed through the inner tube, or
vice-a-versa.
In a preferred embodiment, the inner tubes of the heat exchangers
are fabricated from TEFLON and the outer tubes are fabricated from
silicone rubber. The inner tubes may be convoluted or corrugated
to increase the available heat transfer area.
In a preferred embodiment, the condenser comprises an inner shell
disposed within an outer housing defining at least one chamber between
the inner shell and the housing. Steam is directed to the inner
shell from the boiler through a steam inlet. The housing includes
a solution inlet to direct partially heated dilute liquid desiccant
from the first heat exchanger into the at least one chamber. A solution
outlet communicates with the chamber and directs partially heated
dilute desiccant at the second temperature to the second heat exchanger.
The inner shell is fabricated from materials including inconel,
monel, titanium, TEFLON, TEFLON-coated copper, TEFLON-coated aluminum,
and TEFLON-coated stainless steel; and the outer shell is fabricated
from materials including TEFLON, polycarbonate, polyvinylidene fluoride,
polypropylene, silicone rubber, polyethylene, and polystyrene.
In an alternative embodiment, the condenser comprises at least
one steam inlet communicating steam from the boiler with the at
least one chamber and at least one solution inlet communicating
partially heated dilute liquid desiccant from the first heat exchanger
with the inner shell.
The condenser may incorporate a plurality of fins associated with
the inner shell and a plurality of fins associated with the housing.
The inner shell may be provided with a plurality of baffles to prevent
short circuiting
from the steam inlet to the condensate outlet.
In another embodiment, the condenser comprises a housing and a
plurality of convoluted tubes. The tubes are supported by opposing
support plates, and communicate with a steam inlet to receive steam
from the boiler. The housing includes a solution inlet to receive
partially heated dilute liquid desiccant from the first heat exchanger,
and a solution outlet through which partially heated dilute liquid
desiccant is delivered to the second heat exchanger. The tubes are
fabricated from Teflon, and the support plates include at least
one silicone rubber sheet attached thereto.
In a preferred embodiment, the respective components are disposed
with respect to one another to take advantage of gravity feed to
communicate the liquid desiccant from the absorber to the boiler
via the first and second heat exchangers and the condenser, thereby
eliminating the need for multiple pumps in the system.
BRIEF DESCRIPTION OF THE DRAWINGS
In accordance with the above, the present invention will now be
described in detail with particular reference to the accompanying
drawings.
FIG. 1 is an exploded isometric view of the portable liquid desiccant
dehumidifier in accordance with the present invention;
FIG. 1A is a block diagram depicting the general operation of the
invention;
FIG. 2 is an exploded isometric view of a desiccant absorber assembly;
FIG. 2A is a detail view of the microglass fiber plates in the
absorber;
FIG. 3 is an isometric view of a boiler;
FIG. 4 is a an isometric view of a coiled interchange heat exchanger
and the boiler;
FIG. 5 is an isometric view of a split interchange heat exchanger;
FIG. 5A is a plan view of an inner tube for an interchange heat
exchanger having a convoluted profile;
FIG. 5B is a plan view of an inner tube for an interchange heat
exchanger having a corrugated profile;
FIG. 6 is an isometric cut-away view of a condenser in a first
embodiment;
FIG. 7 is an isometric cut-away view of an inner shell of the condenser
shown in FIG. 6;
FIG. 8 is an isometric cut-away view of a condenser in a second
embodiment;
FIG. 9 is an isometric cut-away view of a condenser in a third
embodiment;
FIG. 10 is an isometric cut-away view of a frame for housing the
respective components of the system; and
FIG. 11 is an isometric cut-away view depicting the frame and some
of the components installed therein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the several views of the drawings, there is shown
a portable liquid desiccant dehumidifier ("PLDD"), generally
characterized by the reference numeral 10.
Referring now to FIGS. 1 and 1A, the PLDD 10 includes a liquid
desiccant absorber 12 for absorbing moisture contained in ambient
air entering dehumidifier 10 and passing through desiccant absorber
12. The desiccant absorber 12 is constructed and arranged for receiving
concentrated liquid desiccant at the top of desiccant absorber 12
and dispensing dilute liquid desiccant from the bottom of desiccant
absorber 12. The desiccant solution may be any one of several conventional
solutions, including aqueous LiBr, LiCl or CaCl.sub.2 as described
above, or any mixture of these solutions. Referring now to FIGS.
2 and 2A, desiccant absorber 12 includes a distributor 14 disposed
at the top of desiccant absorber 12 which receives concentrated
liquid desiccant and delivers the liquid desiccant through a plurality
of "spaghetti" tubes 16 extending radially outward from
a central hub 18. The desiccant absorber 12 includes a plurality
of horizontally and vertically disposed interconnected microglass
fiber plates. The vertical plates are identified by the reference
numeral 20 and are supported by horizontal interconnecting fiber
plates 22 as shown. The top plate 22 is referred to as a distribution
sheet. The concentrated desiccant wicks into the distribution sheet
22 and down the vertical plates 20. The vertical plates 20 contain
beads 21 which separate and support contiguous vertical plates 20.
Ambient air is drawn into the unit and forced through the microglass
fiber plates by a fan 23 (see FIG. 1), where the moisture in the
air is removed as the air makes contact with the liquid desiccant.
As the desiccant dehumidifies the air stream, the moisture-absorbing
capability of the desiccant is reduced and the desiccant must be
regenerated. This dilute desiccant is collected in a drain pan 24
disposed at the bottom of desiccant absorber 12. The drain pan 24
includes an intermediate support plate 26 defining at least one
drain hole 28 which enables the dilute desiccant to flow into a
bottom chamber defined between support plate 26 and a bottom wall
30 of drain pan 24. A drain tube 32 including a one-way or check
valve 33 extends from the bottom chamber to direct the dilute desiccant
out of absorber 12. The absorber components are disposed within
a frame 35 as shown in FIG. 10 which can be fabricated from materials
including, but not limited to, polypropylene, polyethylene, polytetrafluoroethyline,
referred to herein under the trademark TEFLON, polyvinylidene fluoride,
polycarbonate, PVC or polystyrene. The frame 35 includes a plurality
of shelves 37a, 37b, and 37c for supporting the respective components
of the unit described below.
The dilute liquid desiccant is regenerated into concentrated desiccant
by boiling the liquid desiccant in a boiler 34 at a temperature
in the range of from approximately 260.degree. F. to 320.degree.
F. An improvement over prior art systems resides in the use of steam
from desiccant regeneration to sensibly preheat the dilute liquid
desiccant. The dilute liquid desiccant is passed through a condenser
and preheated using the latent heat of condensation of the steam
produced by boiling the liquid desiccant. Preferably, a series of
interchange heat exchangers are employed to further preheat the
dilute liquid desiccant entering the boiler 34 by recovering heat
from the concentrated liquid desiccant delivered to absorber 12
from boiler 34 to further increase operating efficiency. These components
are described in more detail below.
The boiler 34 is shown in FIG. 3 and is configured in the shape
of a tub or vessel having an elongated horizontal dimension. The
horizontal elongation provides a uniform temperature gradient, and
thus a uniform concentration level of the liquid desiccant solution,
as compared to a vertically elongated boiler. The boiler 34 includes
side walls 36 a bottom wall 38 a top wall 40 and a peripheral
support flange 42 for supporting the other dehumidifier components
above the boiler. The boiler 34 is constructed from materials including,
but not limited to, polycarbonate, polyvinylidene fluoride, TEFLON
and the like. A heating element 44 is coiled proximal to the bottom
wall 40 as shown, and is connected to a pair of leads 46 in a conventional
manner. A thermocouple 48 extends into boiler 34 to monitor the
internal temperature. The leads 46 and thermocouple 48 extend through
top wall 40. The heating element 44 and thermocouple 48 are operably
associated with a controller (not shown) for maintaining boiler
34 at the optimum temperature. A pair of steam outlets 50 extend
through top wall 40 to deliver steam generated by boiling the liquid
desiccant to a condenser described in more detail below.
Referring now to FIG. 4 a drain tube 51 is coupled to one of the
side walls 36 to enable boiler 34 to be emptied as required. A U-fitting
52 is coupled to the upper region of one of the side walls 36 to
receive preheated dilute liquid desiccant from the condenser through
an inlet port 54 and to dispense concentrated liquid desiccant
through an outlet port 56. The U-fitting 52 communicates with a
coiled interchange heat exchanger 58 which comprises at least one
tube assembly including an inner tube 60 concentrically disposed
within an outer tube 62 to define an annulus 64 therebetween. The
tube assembly is coiled around boiler 34 to recover the waste heat
radiating through side walls 36. This arrangement is exemplary,
as the tube assembly could be embedded within the side walls 36
or disposed in contact with top wall 40. The concentrated liquid
desiccant from boiler 34 enters the annulus 64 through side wall
36 and is directed to outlet port 56. The partially heated dilute
liquid desiccant from the condenser is passed through the inner
tube 60 in a direction counter to the concentrated liquid desiccant
and enters boiler 34 through side wall 36. Alternatively, the concentrated
liquid desiccant is passed through inner tube 60 and the dilute
liquid desiccant is passed through annulus 64. In a preferred embodiment,
inner tube 60 is fabricated from TEFLON, and outer tube 62 is constructed
from silicone rubber. The TEFLON inner tube 60 has relatively high
heat conductivity, while the outer silicone rubber tube 62 has a
relatively low thermal conductivity, and is a good insulator. These
components can withstand relatively high temperatures (.about.400.degree.
F.), and are not corroded by the desiccant solution. To improve
efficiency, inner tube 60 may be convoluted as shown in FIG. 5A
or corrugated as shown in FIG. 5B. It is to be understood that the
use of this type of TEFLON/silicone rubber tube-in-tube heat exchanger
is not limited to a liquid desiccant system. There are many applications
in which this arrangement may be employed. The particular operation
of the coiled interchange heat exchanger 58 will be described in
more detail below.
Referring now to FIG. 5 there is depicted a split interchange
heat exchanger 66 which includes a pair of tube assemblies 68.
Each tube assembly 68 comprises an inner tube 70 concentrically
disposed within an outer tube 72 to define an annulus 74 therebetween.
The dilute liquid desiccant from desiccant absorber 12 is gravity
fed to the interchange heat exchanger 66 where it is directed through
a manifold 76 and into the inner tubes 70. Concentrated liquid desiccant
from boiler 34 is first delivered through coiled interchange heat
exchanger 58 and thereafter directed through a U-fitting 78 coupled
to the respective outer tubes 72 and into the annuli 74. Alternatively,
dilute liquid desiccant is passed through annuli 74 and concentrated
liquid desiccant is passed through inner tubes 70. In this manner,
heat is transferred from the concentrated liquid desiccant to the
dilute liquid desiccant within split interchange heat exchanger
66. The concentrated liquid desiccant is thereafter drawn into a
pump 80 (see FIGS. 1 and 1A) through a U-fitting 82 coupled to the
respective outer tubes 72. The pump 80 delivers the concentrated
liquid desiccant to distributor 14 of absorber 12. The partially
heated dilute liquid desiccant flows through a manifold 84 to the
condenser. During this stage, the dilute liquid desiccant dispensed
from absorber 12 is raised to a first temperature. As discussed
above with respect to coiled interchange heat exchanger 58 the
inner tubes 70 may be fabricated from TEFLON and the outer tubes
72 may be constructed from silicone rubber. Likewise, the inner
tubes may be provided with a convoluted or corrugated profile as
shown in FIGS. 5A and 5B, respectively.
The partially heated liquid desiccant at the first temperature
is delivered to a condenser 86 from split interchange heat exchanger
66 as shown in FIGS. 1 and 1A. Referring now to FIGS. 6 and 7 there
is depicted a first embodiment of condenser 86 which is comprised
of an inner shell 88 disposed within an outer housing 90 defining
at least one chamber 92 between inner shell 88 and housing 90. The
housing 90 includes a plurality of side walls 94 a top wall 96
and a bottom wall 98. A pair of steam tubes 100 communicate with
inner shell 88 through top wall 96 to deliver steam from boiler
34. A pair of air vents 102 likewise communicate with chamber 92
through top wall 96 to evacuate excess air therefrom. A condensate
tube 104 communicates with inner shell 88 through bottom wall 98
to drain condensate into a condensate pan 106 (see FIG. 1A). An
inlet tube 108 communicates with chamber 92 through one of the side
walls 94 to deliver partially heated dilute desiccant to condenser
86 from split interchange heat exchanger 66. An outlet tube 110
is similarly disposed to communicate with chamber 92 on an opposite
side of condenser 86 to deliver dilute desiccant which is sensibly
heated to a second temperature by the latent heat of condensation
as the steam condenses in the inner shell 88 to the coiled interchange
heat exchanger 58 via the inlet port 54 of U-fitting 52 shown in
FIGS. 1 and 4. To facilitate heat transfer, inner shell 88 is fabricated
from materials including inconel, monel, titanium, TEFLON, TEFLON-coated
copper, TEFLON-coated aluminum, and TEFLON-coated stainless steel.
The housing 90 is fabricated from materials including TEFLON, polycarbonate,
polyvinylidene fluoride, polypropylene, silicone rubber, polyethylene,
and polystyrene. If a plastic such as TEFLON is used for the housing
90 the wall thickness is made suitably thick to provide the necessary
insulating properties.
The condenser 86 may incorporate a plurality of fins 112 located
on the exterior of inner shell 88 and a plurality of fins 114 disposed
on bottom wall 98 of housing 90. The inner shell 88 may be provided
with a plurality of baffles 116 to prevent short circuiting from
steam inlets 100 to condensate outlet 104.
Although depicted with the steam being directed into the inner
shell 88 and the liquid desiccant being directed into the chamber
92 the opposite arrangement may be employed with the liquid desiccant
directed into the inner shell 88 and the steam delivered to the
chamber 92. Referring now to FIG. 8 there is shown an alternative
embodiment of a condenser 86a, including a housing 90a and inner
shell 88a, where the inner shell 88a segregates housing 90a into
two compartments 92a, 92b, respectively. A steam inlet tube 100a
communicates with compartment 92a, and a steam inlet tube 100b communicates
with compartment 92b. Partially heated dilute dessicant solution
is delivered to inner shell 88a through solution inlet 108a, and
is sensibly heated by the latent heat of condensation as the steam
condenses in the respective chambers 92a, 92b. Condensate flows
out of chambers 92a, 92b, via condensate outlets 104a, 104b, respectively.
Partially heated dilute dessicant at the second temperature flows
out of inner shell 88a through solution outlet 110a to coiled interchange
heat exchanger 58. Baffles 112a, 112b are provided in chambers 92a,
92b, respectively.
Referring now to FIG. 9 there is shown a third embodiment of a
condenser 86b, comprising a housing 90b and a plurality of tubes
118 which may be convoluted or corrugated as described above with
regard to the interchange heat exchangers and shown in FIGS. 5A
and 5B. The tubes 118 are supported by opposing support plates 120
and communicate with respective steam inlets 100c, 100d through
which steam is delivered from boiler 34. The housing 90b includes
a liquid dessicant solution inlet 108b to receive dilute liquid
desiccant from split interchange heat exchanger 66 and an outlet
110b to deliver partially heated liquid dessicant at the second
temperature to the coiled interchange heat exchanger 58. The tubes
118 are fabricated from Teflon, and the support plates 120 include
at least one silicone rubber sheet attached thereto.
Referring now to FIG. 11 the respective components of the PLDD
10 are shown stacked within frame 35.
During the operating cycle, ambient air is drawn into the unit,
through absorber 12 and exhausted to the room by fan 23. The moisture
in the air is extracted as the air makes contact with the liquid
dessicant wicking accross the microglass fiber wick plates 20 22.
Dilute liquid dessicant is gravity fed from drain pan 24 of absorber
12 to manifold 76 of split interchange heat exchanger 66 wherein
it is raised to a first temperature through heat transfer from concentrated
liquid dessicant flowing through annuli 74. The dilute liquid desiccant
at the first temperature is then delivered to the condenser 86
in which the latent heat of condensation from condensing steam sensibly
heats the liquid desiccant to the second temperature without exposing
the desiccant to steam. The liquid dessicant at the second temperature
is thereafter delivered to the coiled interchange heat exchanger
58 in which it is further heated to a third temperature prior to
introduction into boiler 34 for regeneration. The coiled interchange
heat exchanger 58 recovers waste heat radiating from the walls 36
of boiler 34. The concentrated liquid desiccant solution produced
by boiling the liquid desiccant is drawn through the coiled interchange
heat exchanger 58 and split interchange heat exchanger 66 and thereafter
delivered to distributor 14 of absorber 12 by pump 80. The stacking
of the respective components as shown in FIG. 1 provides for the
gravity feed of dilute liquid desiccant from absorber 12 to boiler
34 through the first and second heat exchangers and the condenser,
thereby eliminating the need for multiple pumps in the system.
The present invention has been shown and described in what are
considered to be the most practical and preferred embodiments. It
is anticipated, however, that departures can be made therefrom and
that obvious modifications will be implemented by persons skilled
in the art. |