Note: Descriptions are shown in the official language in which they were submitted.
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COOLING EQUIPMENT
This invention relates to equipment including a
dry cooling tower section having a tube bundle through
which a medium to be cooled is circulated and over which
air is passed to cool the medium. More particularly, it
relates to improved equipment of the type shown in U. S.
Patent No. 2,545,926, wherein the air is passed through a
wet cooling tower section upstream of the dry section where
it may be humidified and thus cooled prior to passage over
the tube bundle of the dry section.
With such equipment, it is possible to cool the
medium to a greater extent than is possible with ordinary
dr~T cooling towers, and/or to reduce the size of the tube
bundle surface and thus the cost of the dry section.
Since the wet section may be used only when required - i.e.,
in hot climates - such equipment was designed primarily for
use in areas where water is at a premium. Also, the water
may be process fluid or makeup water, and thus corrosive or
brackish, without detracting from the overall operation of
the equipment.
However, environmental considerations make it
difficult to dispose of contaminated water in a conventional
manner. Although efforts have been made to dispose of it
by evaporation, conventional equipment for this purpose is
quite e~pensive. It has therefore been propcsed to evapor-
ate the water in the wet section of equipment of the type
above described, at least in those areas where such equip-
ment is otherwise useful for the reasons above r,oted.
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~ lowever, when used in the ordinary manner - i.e.,
only in hot weather - this equip~ent has limited evapor-
atlng capacity. On the other hand, the danger of freeze up
of both liquid medium in the tube bundles and water in the
wet section during periods of low ambient temperature
normally prevents use of this equipment as other than a
hot weather peaking device. Furthermore, solids in the
water often used to precool the air in the wet section settle
out in thetray above the fill, and depending on the concen-
tration of the contaminants, this may require that the traybe cleaned frequently, thus putting the entire equipment out
of service.
An object of this invention is to provide equip-
ment of this type which, while serving its original purpose,
is capable of evaporating considerably more water, and, more
particularly, of such construction that ambient air may be
precooled in the wet section on a continuous year round
basis without danger of freeze up.
Another object is to provide cooling equipment of
this or other types having a wet cooling tower section re-
quiring a minimum of maintenance even when the water contains
a high concentration of solids.
These and other objects are accomplished, in
accordance with the illustrated embodiment of this invention,
by equipment of this type having a housing which encloses
the inlet to the wet section, the outlet from the dry
section, and other outer side and top walls of said sections.
More particularly, the housing has means for selectively
venting air which has passed through the wet section and
across the tube bundle or recirculating it successively
through the wet section and across the tube bundle of the
dry section. In this manner, the wet section may be oper-
ated not only to precool the air during the summer months,
but also during the winter months, because the recirculated
air is sufficiently warm to prevent freeze up of either
wat:er in the wet section or liquid medium in the tubes of
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the tube bundle. Furthermore, since recirculation of the
air increases its temperature over that of the ambient
air, more water may be evaporated due to the increased
ability of the air to take on the water through which it
passes in the wet section. Preferably, a means is pro-
vided for mixing ambient air with air which is recirculated,
in any desired proportions, thereby making the equipment
more adaptable and flexible in climates which are neither
particularly hot nor particularly cold.
More particularly, the housing has a first por-
tion which encloses the inlet to the wet section, a second
portion enclosing the outlet from the dry section, and a
first opening connecting the first and second portions.
The first housing portion has a second opening for admit-
ting air therethrough, the second housing portion has a
third opening to vent air therefrom, and means such as
adjustable louvers are provided for controlling the flow
of air through the first, second and third openings. Thus,
the first opening may be closed and the second and third
openings opened to cause ambient air passing through the
we1: section and across the tube bundle of the dry section
to be vented from the dry section, or, alternatively, the
second and third openings may be closed and the first open-
inc, opened to cause air to be recirculated through .he wet
section and across the tube bundle.
In its preferred and illustrated embodiment, the
ho~lsing has a fourth opening in the first portion to admit
ambient air thereto, and means such as adjustable louvers
for controlling the admission of air thereto. Thus, the
second opening may be closed, and the first, third and
fourth openings partially opened to cause ambient and re-
circulated air to be combined prior to passage through the
wet section. Thus, this equipment makes it possible to
pass lO0~ an~ient air once through the wet section, to re-
circulate lO0~ of the air therethrough, or to pass mixturesof the two in any desired proportion.
In accordance with another novel aspect of the
present invention, the cooling tower of the wet section
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comprises, as compared with conventional cooling towers
of this type, a plurality of side-by-side trays above the
fill each for distributing water over a portion thereof,
and a plurality of side-by-side sumps below the fill each
for collecting water therefrom, with the trays and sumps
being arranged in pairs one above the other so that water
distributed from the tray of each pair is collected in the
sump thereof. More particularly, means are provided for
supplying water to a first tray, and for discharging water
from a last sump, together with means for lifting water from
the first and each additional sump intermediate the first
and last sump and supplying it to a successive tray. Thus,
the water flows in series rather than in parallel fashion,
so that as evaporation takes place in each section, the
solids are more highly concentrated in the subsequent
section, and the water in the last tray contains the great-
est concentration of solids. As a consequence, it is con-
templated that only the interior of the tower modules and
trays of the last such sections will require frequent clean-
ing, and only that part of the overall tower be taken outof operation.
In one aspect of the present invention, there is
provided cooling equipment, comprising a wet cooling tower
section having an inlet and outlet, fill intermediate the in-
let and outlet, and means for distributing water over the fillso as to cool air as it flows through the wet tower section,
a dry cooling tower section having an inlet and outlet and a
bundle of tubes through which a fluid to be cooled may be
passed and over which air may be passed to cool such medium,
means for causing air to pass successively through the wet
section and across the tube bundle of the dry section, whereby
air which passes over the tube bundle is first cooled by water
in said wet section, and a housing enclosing the inlet to the
wet section, the outlet from the dry section and other outer
side and top walls of said sections, said housing having means
for selectively venting air which has passed over said tube
bundle or recirculating such air successively through the wet
~_~section and across said tube bundle.
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In the drawings, wherein like reference characters
are used throughout to designate like parts:
Fig. 1 is a top plan view, broken away in part,
of equipment constructed in accordance with the present
invention;
Fig. 2 is a cross-sectional view of such equip-
ment, as seen along broken lines 2--2 of Fig. 1, and with
the louvers in the housing openings arranged to cause air
which passes successively through the wet section and
across the tube bundle of the dry section to be vented
from the dry section,
Fig. 3 is a longitudinal cross-sectional view of
equipment, as seen along broken lines 3--3 of Fig. 2;
Fig. 4 is another cross-sectional view of the
equipment, similar to Fig. 2, but with the louvers in the
housing openings arranged to cause part of the air which
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passes successively through the wet section and across
the tube bundle of the dry section to be vented from the
dry section and the remainder thereof to be combined with
ambient aix for recirculation through the wet and dry
S sections; and
Fig. 5 is another cross-sectional view of the
equipment, similar to Figs. 2 and 4, but with the louvers
in the housing openings arranged to recirculate all of the
air which passes successively through the wet section and
across the tube bundle of the dry section.
With reference now to the details of the above-
described drawings, the overall equipment, which is desig-
nated in its entirety by reference character 10, includes
a pair of wet cooling tower sections W extending longi-
tudinally in laterally spaced-apart, parallel relation, and
a dry cooling tower D extending longitudinally intermedi-
ate the wet sections above an air chamber or plenum 11 which
is common to both wet sections and has a bottom wall 12
extending laterally beneath them. As previously mentioned,
and as will be described in detail to follow, equipment 10
also includes a housing EI which encloses the inlet to the
wet section, the outlet from the dry section, and other
outer side and top walls of the sections. As best shown in
Fig. 1, the overall equipment, including the wet and dry
sections and housing H have inner vertical walls which divide
it longitudinally into end-to-end modules lOA, lOB, lOC
and lOD, and outermost vertical walls which close the outer
ends of the outermost modules.
Each wet section module is of more or less con-
ventional construction in that it has fill 13 over whichwater is adapted to be distributed from a tray 14 there-
above and from which water is collected in a sump 15 there-
below. As well known in the art, the fill has a large sur-
face area, such as a series of staggered slats, as indi-
cated diagrammatically in Fig. 2, so as to promote contactof water with air passing laterally through the wet
section.
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Lach dry section module is also of more or less
conventional construction in that it includes a tube
bundle 16 having tubes extending laterally across an open-
ing defined between the side walls 17 of the frame of the
dry section which connect at their lower ends with the top
walls 18 of the frame of the wet section. A fluid medium
to be cooled is circulated through the tubes of the bundle
16 by means of inlet and outlet conduits 19 and 20, and
air is caused to flow upwardly across the tube bundle by
means of two banks of fans 21 each mounted within a fan
ring 22 supported on the frame of the dry section above
the bundle. The banks of fans are separated from one
another by a vertical wall 27A of the dry section frame so
that each bank draws air primarily from the wet section
adjacent thereto.
As indicated by the arrows of Figs. 2, 4 and 5,
air which is drawn across the bundle is first caused to
pass from the inlet to the ou~tlet and thus through fill 13
of each wet section, and then into and through the plenum
11. As will be described below, when the air has been drawn
across the bundle and out the fan ring at the outlet of the
dry section, it is either vented from the housing or re-
circulated therein, or partially vented and recirculated.
Preferably, mist eliminators 24 are mounted in the plenum
intermediate each wet section outlet and dry section inlet
for the purpose well known in the art.
~ ousing H is divided into first portions 25A
each of which encloses the inlet to one of the wet
sections, and second portions 25B each enclosing the outlet
from one bank of fans of the dry section. More particular-
ly, the housing portions have top walls which merge to form
a top wall for the housing, and the first housing portions
also have side and bottom walls which, with the top wall,
enclose not only the inlet to the wet section and outlet
from the dry section, but also the other outer side and top
walls of the sections.
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The first and second housing portions are sepa-
rated from one another by common side walls having
louvered openings 26 therein, so as to control the flow of
air from each second portion to the adjacent first portion.
As also shown in the drawings, the side walls of first
housing portions are also provided with louvered openings
27, so as to control the admission of ambient air thereto,
and thus to the inlet to each wet section. Also, the top
walls of the second housing portions are provided with
louvered openings 28 so as to control the venting of air
from such portions, and the top wall of the first housing
portions are provided with louvered openings 29 to ~co,ntrol
B the admission of ambient air to such first portion ~ and
thus, similarly to the louvered opening 27, the admission
of ambient air to the inlet to each wet section.
During the hottest part of the year, the
louvered openings may be arranged to operate the equipment
in conventicnal fashion. That is, louvers 26 and 29 may be
closed, and louvers 27 and 28 opened, as illustrated in
Fig. 2, to cause ambient air to pass through the wet
section, across the tube bundle 16 of the dry section, and
then vented to the atmospheLe. However, during the cold-
est part of the year, and particularly during subfreezing
temperatures, the louvers 27, 28 and 29 may be closed, and
louvers 26 fully opened, as shown in Fig. 5, so as to
recirculate air successively through the wet and dry sec-
tions. During moré moderate temperatures, it may be
preferable to pass a mixture of ambient and recirculated
air through the sections, in which case, as shown in Fig.
4, louvers 27 are closed and louvers 26, 28 and 29 are
partially opened, so as to combine ambient air with some
of the recirculated air, and vent the remainder thereof.
As previously described, the foregoing àrrange-
ment enables operation of the wet sections of the tower
during all weather conditions and thus the whole year
around. This in turn permits water to be evaporated in
the wet section during the entire year, or at least during
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other than the hottest tem~cratures. More particularly,
this is made possible by virtue of the fact that the
recirculated air is sufficiently warmed as to prevent
freeze up. As also possibly previously described, the
warmer air which is recirculatecl through the wet sections
has increased ability to evaporate the water over ambient
air at a lesser temperature.
As previously described, and as best shown in
Figs. 1 and 3, the cooling tower of each wet section
module includes an individual tray and an individual sump
disposed above and below, respectively, fill 13. Thus,
with theoverall equipment divided into four modules, as
illustrated, there are four separate trays 14A, 14B, 14C
and 14D, and a corresponding number of separate sumps 15A,
15 15B, 15C and 15D. ~ore particularly, and as shown in Fig.
3, the vertical walls which divide the equipment into
modules extends to the bottom of each sump so that it, like
each of the trays, is separate from the others. Thus,
there are four pairs of trays and sumps, each tray of each
pair serving to distribute water over the fill which is
collected in the sump of the pair beneath it.
Water is supplied to a first tray 14A through
conduit 30, and a portion of this water, which remains
after evaporation in all four modules, is discharged or
blown down from a last sump 15D through conduit 31. As
previously described, this invention contemplates that
the water will be corrosive or brackish and contain a large
concentration of solids. In conventional equipment of this
type, the water distributed by the trays flows in parallel
fashion into the sump therebelow. According to the present
invention, however, the water is in effect caused to flow
in series fashion from one cooling tower module to the next.
Thus, as shown in Fig. 3, water which is collected in the
first sump 15A is supplieBd by means of a pump 32A and a
B 35 riser 33A to the tray ~ of the adjacent module. Then,
water in the second sump 15B is .supplied by means of a
pump 32B and a riser 33B to the tray 14C of the third
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g
module, and water in the third s~mp 15C is supplied b
means of a pump 32C and a riser pipe 33C to the tray 14D
of the last module. Water collected in the sump 15D of
the last module is supplied to discharge pipe 31 by means
of a pump 32D.
Since evaporation takes place in each module, the
amount of water supplied to eachtray is less than that
supplied to the preceding tray and the percentage of solids
collected in each successive sump wil] be correspondly
more. ~s a result, only water in the last sumps, or pos-
sibly only in the last sump, will have such a large concen-
tration of solids as to require that it be cleaned with
great frequency. This, of course, not only simplifies the
maintenance of the equipment, but also, due to its modular
construction, enables at least certain of the wet section
modul~s to contirue to operate while the trays of other
moc,ules are being cleaned.
Substantially equal heads of water may be main-
tained in each tray, despite the lesser volume of water
supplied to each successive tray,by means of holes in the
bottom of each tray of successively smaller size. That
is, as best illustrated by the blown-up portions of Fig.
3, holes 34A in tray 14A may be larger than the holes 34B in
the bottom of tray 14B, while the holes 34B may be larger
than the holes 34C in the bottom of tray 14C, and the
holes 34C may in turn be larger than the holes 3~4D in
the hottom of the tray 14D. Obviously, this same purpose
may be accomplished by means of trays of successively
smaller volume in the direction of water flow.
From the foregoing it will be seen that this
invention is one well adapted to attain all of the ends
and objects hereinabove set forth, together with other
advantages which are obvious and which are inherent to
the apparatus.
It will be understood that certain features and
~ubcombinations are of utility and may be employed without
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reEerence to other features and subcom~inations. This
is contemplated by and is within the scope of the claims.
As many possible embodim~nts may be made of
the invention without departing from the scope thereof,
it is to be understood that all matter herein set forth
or shown in the accompanying drawing is to be interpreted
as illustrative and not in a limiting sense.
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