U.S. patent number 3,870,485 [Application Number 05/305,126] was granted by the patent office on 1975-03-11 for cooling tower.
This patent grant is currently assigned to Aza-yunohara, Japan Gasoline Co., Ltd., Oaze-Futsuk-aichi, Shin-Nihon Reiki Co., Ltd.. Invention is credited to Motoyoshi Hashitani, Hiroyoshi Kurohara, Hiroo Shiraishi, Senji Takenaka, Shinjiro Tomita, Nobuo Yamada.
United States Patent |
3,870,485 |
Shiraishi , et al. |
March 11, 1975 |
COOLING TOWER
Abstract
A cooling tower comprising an outer casing provided with air
inlets and an air outlet, net-like fillers disposed in said outer
casing, a liquid distributor for sprinking a fluid to be cooled
onto the fillers, a basin for receiving the fluid which has been
sprinkled from said liquid distributor and flowed downwardly along
said fillers, a suction blower mounted to direct air to said
fillers disposed in the outer casing, and an eliminator provided to
prevent splash liquids formed in the outer casing from dispersing
outside the outer casing.
Inventors: |
Shiraishi; Hiroo (Fukuoka,
JA), Kurohara; Hiroyoshi (Chikushi, JA),
Tomita; Shinjiro (Fukuoka, JA), Takenaka; Senji
(Yokohama, JA), Yamada; Nobuo (Yokohama,
JA), Hashitani; Motoyoshi (Niiza, JA) |
Assignee: |
Japan Gasoline Co., Ltd.
(Tokyo, JA)
Shin-Nihon Reiki Co., Ltd. (Tokyo, JA)
Aza-yunohara (Chikushino-shi, Fukuoka-ken,, JA)
Oaze-Futsuk-aichi (Chikushino-shi, Fukuoka-ken,,
JA)
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Family
ID: |
26359579 |
Appl.
No.: |
05/305,126 |
Filed: |
November 9, 1972 |
Foreign Application Priority Data
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Mar 6, 1972 [JA] |
|
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47-22373 |
Mar 22, 1972 [JA] |
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47-28670 |
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Current U.S.
Class: |
96/357; 62/305;
239/566; 261/DIG.11; 261/DIG.72; 261/98 |
Current CPC
Class: |
F28C
1/14 (20130101); F28F 25/087 (20130101); F28F
25/06 (20130101); F28G 9/00 (20130101); Y02B
30/70 (20130101); Y10S 261/72 (20130101); Y10S
261/11 (20130101) |
Current International
Class: |
F28C
1/14 (20060101); F28F 25/08 (20060101); F28F
25/00 (20060101); F28G 9/00 (20060101); F28F
25/06 (20060101); F28C 1/00 (20060101); B01f
003/04 () |
Field of
Search: |
;261/112,111,97,98,DIG.11 ;55/257 ;239/193,566 ;62/310,305
;165/115,117,174 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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962,753 |
|
Jul 1964 |
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GB |
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1,215,187 |
|
Dec 1970 |
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GB |
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Primary Examiner: Miles; Tim R.
Assistant Examiner: Chiesa; Richard L.
Attorney, Agent or Firm: Woodhams, Blanchard and Flynn
Claims
What we claim is:
1. A cooling tower comprising a casing having side wall means with
air inlet opening means for atmospheric air near the lower end
thereof, said casing having outlet opening means at its upper end
for discharging heated air; a basin disposed below said casing for
receiving cooled liquid therefrom; an air-moving impeller
associated with said outlet opening means for drawing air into said
casing through said inlet opening means and discharging the air
through said outlet opening means; gas-liquid contact means
comprising a plurality of generally upright porous sheet-like
screens each having an undulating configuration, said screens being
arranged in association with each other to define upright passages
for flow of upwardly rising air which air is adapted to contact
liquid flowing downwardly on the screens; a plurality of liquid
distributors mounted inside said casing between the upper ends of
said screens and said outlet opening means, said liquid
distributors being arranged in a generally horizontal array for
distributing liquid substantially uniformly onto the upper ends of
said screens, each liquid distributor comprising an elongated outer
tube which is closed at both its axial ends and which has a series
of axially spaced openings of essentially the same size along its
lower side for discharging liquid substantially vertically
downwardly onto the upper ends of the screens, an elongated inner
tube fixed to and projecting through one axial end of said outer
tube and extending axially therein substantially to the other axial
end of said outer tube, said inner tube being radially spaced from
the interior wall of said outer tube to define therewith an annular
zone for holding a quantity of the liquid, the axial end of said
inner tube disposed within said outer tube being closed and the
other axial end of said inner tube being connected to a source of
the liquid, the portion of said inner tube located within said
outer tube having a series of axially spaced openings along its
upper side, so that liquid supplied to said inner tube overflows
therefrom upwardly through said openings in said inner tube and
then flows downwardly in said annular zone and accumulates to a
substantial depth therein and the liquid flows downwardly through
the openings in said outer tube under substantially uniform
pressure along the entire length of said outer tube and onto the
upper ends of said screens; and eliminator means mounted in said
casing above said liquid distributors for minimizing the flow of
splash liquid through said outlet opening means.
2. A cooling tower as set forth in claim 1, wherein the screens are
disposed in an inclined manner with adjacent screens being
oppositely inclined so that the crest portion of each screen
crosses the trough portion of the adjacent screen and there are
formed passageways for the passage of the air flow between such
portions.
3. A cooling tower as set forth in claim 1, wherein the screens are
disposed so that the screens are arranged in parallel to each other
and the crests and troughs of each pair of adjacent screens
confront and are spaced from each other with a continuous
passageway being formed between each pair of screens.
4. A cooling tower as set forth in claim 1, including a dry heat
exchanger mounted in said casing between the upper end of said
eliminator and said outlet opening means, said dry heat exchanger
comprising a plurality of externally-finned tubes mounted in a
horizontal array and disposed in the path of the air flow; and a
device for feeding liquid mounted in said casing above said dry
heat exchanger and arranged for spraying liquid onto the fins to
dissolve solids adhering thereon.
5. A cooling tower as set forth in claim 1, wherein said eliminator
includes spaced-apart undulating vane plates disposed at an angle
to the air flow for preventing splash liquids formed in the outer
casing from dispersing outside the outer casing.
Description
CROSS-REFERRENCE TO RELATED APPLICATION
This application is related to our copending application U.S. Ser.
No. 305,127, filed Nov. 9, 1972.
BACKGROUND OF THE INVENTION
a. Field of the Invention
This invention relates to improvements in a cooling tower for
cooling a fluid, such as a process fluid.
In general, a cooling tower comprises an outer casing provided with
air inlets and an air outlet, fillers disposed in said outer
casing, a liquid distributor for sprinkling a fluid to be cooled on
to the fillers, a basin for receiving the fluid which has been
sprinkled from said liquid distributor and flowed downwardly along
said fillers, a fan mounted to direct air to said fillers disposed
in said outer casing, and an eliminator provided to prevent splash
liquids formed in said outer casing from dispersing outside the
outer casing. In short, cooling towers are devices which can
accomplish the cooling of a fluid efficiently by utilizing
effectively the evaporative latent heat of the fluid itself.
B. Description of the Prior Art
Fillers varying in configuration and properties are used in cooling
towers of this type. Especially, fillers comprising a
water-permeable plane plate 24 or wavy plate having small
projections 25 on the surface of the plate 24, such as illustrated
in FIG. 6, are widely used. In case fillers of this type are
employed, as is seen from FIG. 6, a fluid (hereinafter referred to
as "water" because in many cases the fluid is water) which flows
downwardly forms flowing films 26 and 27 on both the front and back
surfaces of the plane or wavy plate 24, and a part 28 of the film
flowing on one side permeates through the plate 24 and joins the
film flowing on the other side. In such a state, these films move
downwardly in parallel to the air flow 29.
In fillers of this type, since projections 25 are provided only on
one surface, the mingling of water in the film 27 is insufficient
on the side where no projections are provided, and the flow rate is
higher on this side. The most characteristic feature of fillers of
this type resides its water permeability, but since the flow rate
of the film 26 on the front surface is lower than that of the film
27 on the back surface, permeating water 28 is allowed to permeate
in the direction to the film 27 from the film 26, resulting in an
increase of the flow amount of the film 27 on the back surface.
Accordingly, it is impossible to attain sufficient mixing of the
layer 30 of saturated air comprising a portion of the air flow 29
with the remainder of the fresh air, and the effect of heat
transfer between air and water is further reduced. Moreover, since
fillers of this type are composed of water-permeable porous plane
plates 24 or wavy plates, in some environments, dust and the like
contained in air are carried by the water into the pores of the
plate and clog same. Thus, and the water permeability, the
characteristic feature of these fillers, is greatly reduced. These
are defects of the conventional fillers of this type.
Fillers composed of water-permeable plane plates disposed in an
inclined manner, such as illustrated in FIG. 7, are also used. In
fillers of this type, a flowing film 32 is formed on the upper
surface of the inclined plane plate 31, and a part of the film 32
permeates to the inside of the inclined plane plate 31 to form a
flowing film 33. These films 32 and 33 fall down onto a plane plate
35 in the form of drops 34 (which are caused to move in an almost
horizontal direction by the action of the air flow). Thus, fillers
of this type are characterized in that the release of the heat from
the water can be accomplished effectively by allowing water to flow
in the above manner in the form of flowing films and drops.
Like the fillers illustrated in FIG. 6, the water-permeable fillers
of this type are defective in that the pores can be clogged with
dust or the like contained in air and their water permeability is
reduced or lost, with the result that formation of the flowing
films cannot substantially be expected and the effect of increasing
the surface area of water by forming the film is reduced, whereby
the merit or advantage gained by providing a water-permeating plane
plate in an inclined manner is reduced almost in half.
The fillers of this type are also characterized in that the heat
transfer effect by flowing films and drops can be attained
effectively by changing the form of the flow of water alternately
from flowing films 32 and 33 to drops 34. Namely, as many fine
drops as possible are dispersed in the air flow and the time for
contact between such water drops and air is maintained for a long
time, to thereby accomplish the heat transfer effectively. However,
since at the time when films 32 and 33 are changed into drops 34,
these water drops 34 have a great particle size and they are caused
to move in the horizontal direction by the air flow 36, the change
of these water drops into fine splashes on the inclined plane plate
cannot be expected, and good results are not obtained with respect
to the effect of transfer of heat from water to air, even though
the residence time of water in air is long.
For the foregoing reasons, conventional fillers characterized by
the water-permeable property, such as illustrated in FIGS. 6 and 7,
cannot be said to exhibit as good a heat transfer effect in
comparison with fillers of this invention which will be detailed
hereinbelow.
Furthermore, there are used fillers composed of a
non-water-permeable plane plate having concavo-convex projections
thereon, such as shown in FIG. 8.
In fillers of this type, projections 38 are provided for mixing the
flowing film 37 and lowering the rate of downward flow of the film
37. However, the thickness of the film 37 abruptly increases
upstream of the projection 38 or in the concave portion of the back
surface (see portions 39 and 40), and therefore, the increase of
the surface area of water for evaporation is inhibited. Further,
the direction of flow 41 of air is changed by the projections 38
and a layer 42 of saturated air is formed and an increase of the
pressure drop of air occurs. For the above-mentioned reasons the
heat transfer between air and water cannot be conducted completely
effectively.
Still further, as illustrated in FIGS. 9 and 10, porous net-like
cylinders which are used as packing in deaerators are sometimes
used as fillers in cooling tower.
Fillers of this type take the form of a porous net-like cylinder
composed of segments of a net molded to have a cylindrical form or
like form, and these cylindrical segments are aligned in the
lateral or longitudinal direction as illustrated in FIG. 9 or
spaced from each other by a certain distance as illustrated in FIG.
10.
In fillers of this type (in the case of the arrangement shown in
FIG. 9), when water 43 flows down on the cylindrical segment 44, a
part of the water flows in the form of a film 45 along the outer
surface of the cylindrical segment 44 downwardly in the peripheral
direction and the other part of the water flows along the inner
surface of the cylindrical segment 44 in the form of a film 46
downwardly in the peripheral direction. These films 45 and 46 flow
on the outer and inner surfaces of such segments successively while
following a locus such as designated as 47.
In the filler assembly composed of segments arranged in the above
manner, a reduction of the rate of falling of water may be
accomplished effecively but the films 45 and 46 form water film
walls or drops of a large size in the cross section of the air flow
direction such, as designated by numeral 48, and such walls or
drops inhibit the flow of air and the heat transfer effect is
extremely reduced on the outer surface of the cylindrical segment.
As a result, the object of using a porous plate, i.e., the object
of conducting the heat transfer effectively on both surfaces of the
plate, is not attained.
The filler assembly shown in FIG. 10 overcomes the defects of the
filler assembly shown in FIG. 9. In this case, water 50 falls in
the form of films 51 and 52 on the inner and outer surfaces of the
cylindrical segments downwardly in the peripheral direction, and
the water falls down onto the next lower cylindrical segment in the
form of drops 53. As in the case of the inclined plane plate shown
in FIG. 7, however, at the time when the film is changed into
drops, water is collected on the lowermost end portion of the
cylindrical segment and falls in the form of drops of a large size
or discontinuous plate-like films. Further, since these drops or
discontinuous films fall in parallel to the air flow 54 on one
line, the effective contact between air and water is not entirely
attained throughout the total section of the air flow, and hence,
the transfer of the heat from water to air is not sufficiently
effective. Moreover, in case filler assemblies composed of such
cylindrical segments are packed as fillers into a certain vessel, a
great number of supporting members or spacers must be provided to
support these segments respectively. Thus, these supporting members
or spacers reduce greatly the flow of air, resulting in an increase
of the pressure drop. Further, an increase in the manufacturing
cost of the fillers and increase of expenses for construction of
the cooling tower are inevitably brought about.
For the foregoing reasons, in the filler assembly composed of the
above-mentioned cylindrical segments, the evaporation surface area
of water formed per unit volume of water is as low as, or is less
than, in the conventional fillers illustrated in FIGS. 6, 7 and 8,
and the effect of the heat transfer between air and water is not
good.
SUMMARY OF THE INVENTION
This invention relates to an evaporative cooling tower which
comprises an outer casing provided with air inlets and an air
outlet, net-like fillers of a wavy configuration provided in the
outer casing, a liquid distributor of a double-tube structure
mounted to sprinkle a fluid to be cooled, a basin for receiving the
fluid which has been sprinkled from said liquid distributor and
flowed along said fillers, a suction blower mounted to direct air
to the fillers provided in the outer casing, and an eliminator of a
wavy plate-like configuration disposed for preventing splash
liquids formed in the outer casing from dispersing outside the
outer casing.
This invention also relates to an evaporative cooling tower of the
above structure wherein the fluid to be sprinkled from the liquid
distributor is sea water and a dry heat exchanger is provided at
the air outlet to remove fine droplet splashes of sea water leaking
out of the eliminator, especially salt components contained
therein.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view illustrating an embodiment of the
cooling tower of this invention.
FIG. 2 is a view showing a filler of this invention composed of net
segments of an inclined wavy configuration.
FIG. 3 is a view illustrating a filler of this invention composed
of net segments of a horizontal wavy configuration.
FIGS. 4 and 5 are partially enlarged, sectional views illustrating
the behaviors of water and air passing through the filler of this
invention.
FIG. 6 is a view illustrating the behaviors of water and air
passing through a conventional filler of a water-permeable plane
plate or wavy plate.
FIG. 7 is a view illustrating the behaviors of water and air
passing through a conventional filler of a water-permeable plane
plate which is installed in an inclined position.
FIG. 8 is a view illustrating the behaviors of water and air
passing through a conventional filler of a non-water-permeable
plane plate provided with concavo-convex projections formed
thereon.
FIGS. 9 and 10 are views illustrating the behaviors of water and
air observed when net-like cylinders conventionally used as packing
are employed as fillers of the cooling tower of this invention.
FIGS. 11 and 12 are sectional views illustrating the liquid
distributor of this invention having a double-tube structure.
FIG. 13 is a view illustrating a part of the eliminator of a wavy
plate-like form according to this invention.
FIG. 14 is a view illustrating a part of a vane plate of the
eliminator.
FIG. 15 is a perspective view illustrating a modified cooling tower
according to the invention.
FIG. 16 is a sectional view of one of the tubes used in the dry
heat exchanger employed in the embodiment of FIG. 15.
FIG. 17 is an end view of the structure shown in FIG. 16.
DETAILED DESCRIPTION OF THE INVENTION:
A primary object of this invention is to provide fillers for a
cooling tower which can completely overcome the above-mentioned
defects of conventional fillers customarily used for a cooling
towers, such as water-permeable fillers shown in FIGS. 6 and 7,
non-water-permeable fillers shown in FIG. 8 and the fillers of net
cylinders shown in FIGS. 9 and 10 and which can attain effective
cooling with high efficiency by utilizing the advantageous features
of these conventional fillers sufficiently.
This invention relates to a cooling tower comprising a plurality of
water-permeable fillers disposed therein to conduct an effective
gas-liquid contact, characterized in that net or screen-like plates
of a wavy configuration are used as filler segments.
Accordingly, this invention provides a cooling tower which
comprises an outer casing 13 provided with air inlets 10, 11 and an
air outlet 12, fillers 1 of wavy porous net-like plates disposed in
the outer casing 13, a liquid inlet 2 and, a liquid distributor 3
for sprinkling a fluid to be cooled onto the fillers, a basin 6 for
receiving the fluid which has been sprinkled from said liquid
distributor 3 and flowed downwardly along said fillers, a discharge
conduit 7 for discharging the cooled liquid, a waste outlet 8, a
suction blower 5 disposed to direct air to the fillers 1 provided
in the outer casing, and an eliminator 4 mounted to prevent splash
liquids formed in the outer casing from dispersing outside the
outer casing. A support 14 is provided for the fillers and inlets
9, 9 for liquid are provided.
In accordance with one feature of this invention, there is provided
a cooling tower of the above structure wherein a cylindrical liquid
distributor having a double-tube structure, sectional views of
which are shown in FIGS. 11 and 12, is provided as the liquid
distributor.
This cylindrical liquid distributor 3 has a double-tube structure
consisting of an outer tube 55, both ends of which are closed, and
a liquid feed tube 56 inserted through one end of the outer tube
55, one end of said liquid feed tube 56 being closed. Liquid
openings 57 are provided at suitable intervals along the lower side
of said outer tube 55, and liquid overflow openings 58 are provided
along the upper side of the liquid feed tube 56. When a
conventional cylindrical liquid distributor (single-tube structure)
is employed, a uniform pressure distribution of the liquid
introduced in the tube cannot be obtained along the entire length
of such a tube. More specifically, the pressure of the liquid
differs between the inlet end of the tube and the opposite end of
the tube. Therefore, the amount of the liquid sprayed on the unit
area of the cooling zone is not uniform, and hence, it is
impossible to obtain an efficient contact between the liquid and
air on the filler surface. In contrast, when the liquid distributor
3 of a double-tube structure is provided according to this
invention, the liquid overflowing from the openings 58 is
transferred to the outer tube 55 and sprayed from the openings 57
of the outer tube. Thus, the spraying can be accomplished under
substantially uniform pressure along the entire length of the tube
55. As a result, the coolant liquid is uniformly distributed and
sprayed.
In accordance with another feature of this invention, there is
provided a cooling tower of the above-mentioned structure, wherein
a wavy plate-like eliminator 4, details of which are illustrated in
FIGS. 13 and 14, is provided for preventing splash liquids formed
in the outer casing from dispersing outside the outer casing. This
eliminator 4 includes wavy vane plates 59 disposed at suitable
intervals, and supported on supporting members 60. Liquid droplets
61, present in the air stream, which flows in the direction of
arrow 63 impinge violently against the surfaces of the wavy
plate-like vane plates 59, and flow downwardly thereon while
forming a liquid film 62. In the case of an ordinary zigzag
eliminator, the thus formed liquid film tends to split off liquid
droplets again therefrom, and these droplets are discharged outside
the outer casing. In such case, the resistance to passage of air is
increased, resulting in an increase of the pressure drop.
Therefore, it is necessary to increase the operation power.
In this embodiment of the cooling tower of this invention provided
with the above eliminator, the amount of the liquid discharged
outside the casing is extremely lowered, for instance, to less than
0.02% of the total amount of the circulated liquid, and the
pressure drop of the air flow is also reduced to an extremely low
level.
In accordance with a still further feature of this invention, there
is provided a cooling tower of the above-mentioned structure,
wherein sea water is used as the liquid and a dry heat exchanger is
provided at the air outlet to remove fine droplet splashes of sea
water leaking out of the eliminator, especially salt components
contained therein.
Since the principle of removal of splash liquids by the eliminator
resides in the utilization of the flow of air passing through the
apparatus, it is difficult to remove completely fine droplet
splashes of sea water. Further, if it is intended to remove
completely splashes of sea water by the action of the eliminator,
the pressure drop of air is increased and a great power is
necessary for operating the suction blower sufficiently, which
results in economical disadvantages.
In case an ordinary eliminator is used, more than 0.02% of
circulated sea water is allowed to disperse outside the outer
casing by failure to remove it by an action of the eliminator.
Even when the eliminator of this invention is used, it is difficult
to attain complete prevention of dispersion of fine droplet
splashes of sea water outside the outer casing, and a very small
quantity of sea water is discharged outside the outer casing. The
thus-splashed sea water discharged outside the outer casing
together with waste air influences harmfully the environments of
not only the factory but also neighbouring private houses, and
there is a fear of causing a pollution problem.
The above defects can be completely overcome by the provision of a
dry heat exchanger of this invention such as illustrated in FIGS.
15, 16 and 17. Namely, fine droplet splashes of sea water that
cannot be completely removed by the eliminator 4 can be completely
eliminated by the action of this dry heat exchanger without
substantial increase of the power for the suction blower. An
example of the dry heat exchanger to be used in this invention is
illustrated in FIG. 15, and one of the heat-exchange tubes employed
therein is illustrated in FIGS. 16 and 17. The dry heat exchanger
has a structure including a plurality of tube 69 each having fins
70 bonded to the periphery of the tube 69. As the heat source to be
introduced into the tubes in this dry heat exchanger, various high
temperature fluids may be used, and it is also possible to utilize
the high temperature of the incoming fluid to be cooled. In this
case, the fluid to be cooled is introduced from an inlet 65 and
discharged from an outlet 68, and then introduced into the cooling
tower from the inlet of the pipe 2 for feeding a fluid to be
cooled. The thus introduced fluid to be cooled is sprinkled from
the liquid distributor, as described above, and is cooled while it
flows downwardly along the surface of the fillers.
Removal of scales of salt components (composed mainly of NaCl) thus
deposited on the surfaces of these finned tubes is accomplished in
the following manner.
At regular intervals, for instance, every 1 to 2 days, the suction
blower 5 is stopped for a short time, and sea water is fed in
through inlet 67 and is sprayed on the fins of the tube of the dry
heat exchanger of the from the liquid distributor 66 for supplying
sea water, whereby the scales are dissolved in the thus-sprayed sea
water. Then, the sea water containing scales dissolved therein is
collected in the liquid-collecting basin 6 and discharged from the
waste opening 8.
Other objects and features of this invention will be apparent from
the detailed description given hereinbelow.
FIG. 1 is a perspective view illustrating one embodiment of the
cooling tower of this invention. This cooling tower is a cooling
tower of the counter-flow type. The invention will now be described
by reference to an example relating to a cooling tower of the
counter-flow type, but needless to say, this invention can be
applied to any conventional cooling towers, as long as the
application does not deviate from the essence of this
invention.
The fluid to be cooled, which has been heated in some other heat
exchange system, such as process fluid, is fed through a feed pipe
2 and sprinkled from the liquid distributor 3 of a double-tube
structure. At the same time, air is sucked from air inlets 10 and
11 by means of the suction blower 5. Thus, the heat exchange is
mainly effected on the surfaces of fillers 1 provided inside the
cooling tower, and a cooled process fluid is obtained.
As illustrated in FIG. 2, net or screen-like plates 1 of an
inclined wavy configuration are disposed on the filler rack 14 so
that the crests of waves of the every two adjoining filler
segments, for instance, segments 15 and 16, are inclined to touch
each other and a space for passage of the air flow is formed in the
vertical direction.
When sea water is used as the liquid, in this invention a dry heat
exchanger such as illustrated in FIGS. 15, 16 and 17 is provided
according to need so as to remove fine droplet splashes of sea
water leaking out of the eliminator, especially salt components
contained therein.
The operation of the cooling tower of this invention will now be
detailed.
Air is fed into the outer casing from air inlets 10 and 11 by
actuating the suction blower 5 and discharged from the air outlet
12. As is illustrated in FIGS. 2 and 3, air passes through spaces
formed between fillers. A process fluid (high temperature water) is
introduced as a fluid to be cooled from the inlet 2 and sprinkled
from openings of the liquid distributor 3 having a double-tube
structure. The process fluid sprinkled from this liquid distributor
is allowed to flow downwardly on the surface of the fillers in the
form of a film flow, and in this state it is gradually cooled. The
cooled process fluid is finally withdrawn from the outlet 7 and fed
to some other heat exchanging system.
In case the fluid to be cooled is sea water, in general, sea water
is introduced from an inlet 65 into the dry heat exchanger 64 in
order to utilize the heat contained in sea water effectively. This
sea water is then passed through the tube of the dry heat exchanger
64 and flowed out from a discharge opening 68, which is generally
connected to the inlet 2 of a pipe 2 for feeding the fluid to be
cooled to the cooling tower. Then, the sea water is cooled in the
above-mentioned manner. In order to remove scales of salts
(composed mainly of NaCl) deposited on the surfaces of the tubes
and fins of the dry heat exchanger 64, at suitable intervals, for
instance, every 1 to 2 days, the suction blower is stopped for a
short time and sea water is sprayed on the dry heat exchanger from
the liquid distributor 66 for supplying sea water, whereby scales
are dissolved in the thus sprayed sea water, following which the
sea water containing scales dissolved therein is collected in the
basin 6 and discharged from the waste opening 8.
In the embodiment illustrated in FIG. 1, a net plate 1 of an
inclined wavy configuration shown in FIG. 2 is employed, but of
course, it is also possible to employ a filler of a net plate of a
horizontal wavy configuration such as illustrated in FIG. 3.
The effects attained by providing these net plate fillers of this
invention in the cooling tower will now be described more
specifically.
The net plate 1 of an inclined wavy configuration used in the
embodiment of FIG. 1 permeates water therethrough regardless of
whether it flows on the front or back surface. Therefore, as
illustrated in FIG. 2, if the wave is inclined so that it is
longitudinal to the direction of falling of the water, the portion
of the trough on one side thereof is simultaneously the crest of
the wave on the opposite surface of the mesh line, and thus, both
the crest and trough are present on the same mesh line.
Accordingly, there does not occur the defect observed when a
water-permeable or non-water-permeable plate is arranged to form an
inclined wave such as shown in FIG. 2, namely the defect that water
is collected on the trough portion of the wave to form a so-called
water passage and the heat transfer effect is reduced.
Further, the net plates of inclined wavy configuration are packed
so that the packing directions of every two adjoining segments are
offset to each other. Therefore, as illustrated in FIG. 2, the air
flow 17 undergoes a mild mingling action at the crest portion of
one segment 16, and parts 18 of the air flow rise while being
contacted and mingled with each other. Thus, either the temperature
of the humidity can be maintained at the same level throughout the
air flow. In such state, the air flow has contact with water as the
fluid to be cooled. Therefore, the effect of the heat transfer from
water to air is very good.
Further, this net plate filler of an inclined wavy configuration
has the following structural advantages: (1) no water drops are
formed in the section of the air flow, (2) no supporting member or
spacer is necessary for supporting the filler, (3) concavo-convex
projections need not be provided on the filler, (4) it is
sufficient if about one bend of the inclined wave is formed on the
filler, (5) the inclination angle can be made smaller than as in
the conventional fillers, etc. Because of these structural
characteristics, in the case of the filler of this invention, the
pressure drop in the air flow can be greatly minimized as compared
with conventional fillers such as shown in FIGS. 7, 8, 9 and
10.
Also a net plate molded to have a horizontal wave such as shown in
FIG. 3 gives an excellent heat-transferring effect.
The filler of this type is inferior to the net plate of an inclined
wavy configuration shown in the embodiment of FIG. 1 with respect
to the action of contact and mingling in the air flow, but it is
advantageous in that the rate of falling of water is low and the
pressure drop of air is small.
In the case of the filler of this type, because of the small
pressure drop, the flow rate of air can be increased and a layer of
saturated air formed in the vicinity of the film flow is disturbed
by the contact between air and the linear flow of water or by the
mingling action of the air flow per se, with the result that the
evaporative heat transfer can be accomplished effectively.
In fillers of this invention such as shown in FIGS. 2 and 3, the
net plate has a property that water is allowed to pass through the
spaces of meshes completely, as illustrated in partially enlarged
views of FIGS. 4 and 5. Accordingly, the film flow 21 is converted
to a linear flow 22 by the mesh line 20 of the net, and forms of
linear flow and film flow appear alternately and the mingling of
the flow and the branching of the flow are caused to occur along
the mesh line of the net, whereby the rate of falling of water is
greatly reduced and the surface are for evaporation is greatly
increased. While such effective state is maintained along the net
plate of a wavy configuration, the air flow 23 has a contact with
the linear flow or film flow of water with the layer of saturated
air being disturbed by the form change of water from the linear
flow to the film flow or from the film flow to the linear flow.
Thus, a very effective heat transfer is accomplished.
Results of tests in which the fillers of this invention molded to
have a wavy configuration are compared with several conventional
fillers with respect to the falling rate of water are shown in
Table 1 given below.
Table 1 ______________________________________ Sample Falling Rate
No. Kind of Filler of Water Remarks
______________________________________ 1 non-permeable wavy 1.10
m/sec comparison plate composed of vinyl chloride resin 2
water-permeable wavy 0.75 m/sec example of plate filler of FIG. 6
arranged to have wavy form 3 non-permeating plate 0.702 m/sec
example of having concavo- filler of FIG. convex projections 8 4
water-passing net 0.623 m/sec example of plate (mesh size = filler
of this 2 mm .times. 2 mm) invention 5 water-passing net 0.522
m/sec example of plate (mesh size = filler of this 3 mm .times. 4
mm) invention ______________________________________
As is seen from the results shown in Table 1, when the wavy net
plate is used as the filler of the cooling tower, the falling rate
of water is very low as compared with the cases where the
conventional fillers are used. Therefore, the filler of this
invention can give a good efficiency of gas-liquid contact and
ensures a long contact time, with the result that the heat transfer
efficiency is very high as compared with the case of the
conventional fillers.
As detailed hereinabove, when fillers composed of a net plate
having a wavy configuration are used according to this invention,
formation of walls of water drops or water films is inhibited
without inviting an increase of the pressure drop in the air flow,
and the use of supporting members or spacers is not required, and
if provision of such members is necessary, the number of them can
be greatly reduced.
Furthermore, the provision of specific concavo-convex projections
on the filler is not required at all. Therefore, formation of
drifts of air and water can be prevented, and it is possible to
reduce the falling rate of water and maintain the contact between
water and air for a long time.
Moreover, the surface area of water for evaporation can easily be
increased, and linear and film flows of water suitable for
obtaining a good heat transfer effect can be formed and the
mingling and branching of these flows can always be accomplished.
As a result, without formation of a layer of saturated air, the
heat transfer can be conducted very effectively with high
efficiency between water and air. Thus, a cooling tower of a very
high cooling efficiency is provided according to this
invention.
* * * * *