Note: Descriptions are shown in the official language in which they were submitted.
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DUAL PATH DRIFT ELIMINATOR STRUCTUR~
AND METHOD FOR CROSSFLOW COOLING TOWER
This invention relates to cross10w water cooling
towers and especially improved drift eliminator constructions
and methods for effectively removing entrained water particles
from generally horizontally directed air currents leaving the
tower fill structure. More particularly, it is concerned with
such eliminators and methods wherein -the moist airstreams are di-
verted at a first angle upwardly relative to the initial path
thereof, and thereafter again diverted along a second diversion
path situated laterally of the first path in order to greatly en-
hance removal of entrained water particles; in addition, the con-
struction of the eliminator allows individual water drainage from
the respective div~rsion paths, so that troublesome water blockage
of the eliminator is avoided.
In evaporative water cooling towers of the crossflow
variety heat is removed from initially hot water by causing the
latter to gravitate through a surface~increasing fill assembly
in crossflowing intersecting relatîonship to currents of cool air
directed through the fill. Drift eliminators are usually pro-
vided to remove entrained droplets or particles from the air leav-
ing the tower fill structure. I drif~ eliminator structures arenot employed in such tQWers, substantial quantities of water can
be discharged into the atmosphere. This results in undesirable
operating conditlons leading to e~cessive wetting of surrounding
areas and corresponding coating thereof with mineral deposits.
In addition, icing of adjacent equipment and structures can readily
occur during wintertime operations. Thus, adequate drift elimi-
natlon is very necessary with evaporative type cooling towers,
especially when large towers are ~sed in metropolitan areas or
as part of a large industrial complex where cold weather occurs.
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(Dkt. #16143)
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One type of drift eliminator for water cooling towers
which has been used successfully for a number of years is de-
picted and described in U. S, Patent No. 2,892,509. The Herring-
bone drift eliminator of this patent utilizes a number of wooden
slats which are both transversely and longitudinally inclined
for deflecting the air from the fill assembly upwardly at an angle
to effect removal of water droplets therefrom as the particles of
moisture impinge upon the double inclined surfaces of the elimi-
nator slats. More effective removal of entrained water from the
airstream is accomplished by providing a double pass of elirnina-
tor slats with the first layer being disposed with the longitudi-
nal axis thereof inclined in one direction, while the next layer
is longitudinally inclined in the opposite direction. Although
highly effective, the Herringbone eliminator structure declines
in performance as higher air velocities are encountered. Inclina-
tion and overlapping of the slats is correlated with the static
air pressure drop to pxevent an undesirable decrease in perfor-
mance of the tower and in an effort to more effectively remove
water droplets from the moist airstream. With increasing concern
about the potential dele~erious environmental effects of cooling
tower drift, especially when brackish or saltwater is used as
the cooling mPdium, a need has arisen for a more efficient drift
eliminator than is inherent in the Herringbone, without signifi-
cant cost increases or a decrease in thermal performance of the
overall tower unit.
Another approach to drift elimination is found in U. S.
Patent No. 3,065,587 which dis~loses honeycomb eliminators asso-
ciated with horizontal wooden slats somewhat similar to the first
pass of the Herrirlgbone design. Further, in one specific embodi-
ment disclosed în Fig. 9 of the drawings of this paten~, the useo~ a pair of adjacent, coplanar, angularly disposed cellular
honeycomb sections is taught. Although honeycomb eliminators have
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found substant~al application, their principal usage has been
limited for the most part to smaller package-type counterflow
towers because of the problems associated with providing a pack
of sufficient structural integrity in order to minimize the ex-
ternal supports needed to hold the eliminator in position across
the moist air outlet face of the fill assem~ly without sagging,
warping, or collapse of the cellular material.
U. S. Patent No. 3,500,615 to Meek, discloses the type
of two ~ass drift eliminator wherein separate eliminator packs
are respectively composed of interconnected, alternating corru-
gated sheets, with the separate packs being located such that the
corrugated sheets in each are at right angles relative to the
sheets in the adjacent pack. Actual testing of this type of
eliminator structure has demonstrated ~hat it does not give ade-
quate drift elimination, and that the pressure drops attributable
to the unit are e~cessive. It is believed that a prime reason
for the deficiency of this type of eliminator stems from the fact
that no means is provided for separately draining the respective
corrugated packs, and that accordingly the air passages thereof can
become partially or fully blocked with water. The accumulated
water is then very susceptible to becoming reentrained in the cool~
ing air, thus further lessening the drift e].imination properties
of this type of eliminator construction.
It is therefore a primary object of the invention to
provide dual pass cellular drift eliminator structures and method
for use in crossflow water cooling towers which overcomes many
of the problems associated with drift eliminators used heretofore
in commercial practice, and that are operable to remove a signifi-
cantly higher portion of entrained water particles from hi~h ve-
locity moist airstreams leaving the fill assembly of a coolingtower without substantial increase in the overall cost of the
eliminator assembly, or significant increase in the static air
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pressure drop associated with the use thereof.
A further important objeet of the invention is to pro-
vide two-pass drift eliminator structure and methods especially
adapted for use with crossflow water cooling towers, and which
are effective to remove entrained water particles from generally
horizontally directed airstreams leaving the tower fill in a man-
ner essentially independent of stream velocity through utiliza-
tion of dual path elimina~ors having spaced, cellular, diversion
path-defining structures disposed to first divert the airstreams
upwardly and preferably laterally at an angle relative to the nor-
mal path thereof, and to thereafter divert the streams laterally
to one side of the first diversion pakh~ In particular, a repre-
sentative ~ector of the air approaching the eliminator, and a
representative vector of the air during the first diversion there-
of, establish a reference plane; and a representative vector of
the air during the second diversion thereof is situated at an
angle with respect to the established reference plane.
A still further important object of the invention is
to provide a dual path drift eliminator of the type described
wherein the first and second diversion path-defining cellular
struetures thereof are spaced a sufficient distance to permit sepa-
rate drainage of the volumes of water collected in each section -
so that water blockage of the air inlet face of the drift elimina-
tor structure is avoided to minimize accumulation and re-entrain-
ment of water in the air leaving the eliminator.
Yet another aim of the invention is to provide multi-
cell dual path drift eliminator constructions which are configured
to present nestable packs permitting complemental positioning of
a plurality of the packs without creation of objectionable vertical
gaps between the sections which could allow substantial volumes of
entrained water to escape to the atmosphere.
A still further object of the invention is to provide
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a ~ulticell dual path elimin~tor ~ebricated of rigidized pre-
~orme~ sheets pre~erably eomposed o~ neopr~ne a~be3to~ and where
in the deformed surfaces thereof are configured and arranged ~o
th~t the drift eliminator pack3 can be produced by ~tacking and
gluing the preformed ~ections util:izing desirable assembly line
tech~iques.
In genexal ter~s, ~he presen~ invention pro~icles,
in a crossflow cooling tower, a ho~: water distributor;
; a cold water collection ba~in beneath said dis~ributor;
~ill 0~ruc~ure locsted b~wae~ d basi~ ~nd ~i8tr~utor or
dispers~g hot w4t~r ~rav~tllti~g fro~ th~ la~t~r; ~n~an~ ~or di-
rectl~g amble~lt-derlYed al~ throu~ ~aid ~ill structu2~ c~o~-
flowizlg ln~er~ec~g relatlo~ship to the flow o ~t~r ~her2-
through ~os cooli~g o~ th~ ter; two-pa~s, c~llular drlf~ eliml-
nator ~truc~ur~ po~ieio~d pro~i ~ 1 t~ the air ~xlt ~ce o~ ~a~d
f~ll st~ucture for r~o~lng drople~s of w~ter e~trai~d ~hi~
the mol~ alr leav~ng th~ truc~ure, ~aid el~m~na~or ~ruc-
tuse c~m~r~sing: ~ plural~y of horiæo~lly spaced, elo~ga~d,
g~erally uprlgh~, ~ran~er~ly V-~haped memb~3 each hs~ing
~ir~t and 3econd g~ner~lly planar ~hees~ or~e~ed ~t a~ ~gl~
rQla~v~ to ea~h other; partitio~ m~an~ ~oin~d to ~d po~ltioned
bPtw~en each oppo~ed p~ir of ad~acen~ fls~t ~d ~ec~d ~heet~ o~
pro~imal Y-shaped me~be~s di~idl~g ~he ~pace hereb~tween i~o
l~dlvitual, ~lo~ga ~d d~cr~te cell~ located ~o~ pa~g~ o
~ deri~d mol~t air ~herethrough, ~he aix cell~ betwe~ ~he
first ~d seco~d ~heets r~p~c~vely pre~en~l~g ~orse~po~dl~g
Ride-by-8id~ f~ r9~. a~d ~eco~d el~ml~tor Bectlon~, ~ald ~lda-b~-
s~de el~m~ator 8ectio~ ~etwe~ re~pect~ve pa~r~ of V~haped
~ ~ber~ belng located ~n ~paced relationshlp to o~ znother ~o
def~n~ ther~betwee~ ge~rally uprlght w~ter drainage p~s~ag~
for ~ach cell re~pec~el~ ~d ~xte~din~ gen2rally rom ~h~ ~op
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to the bottom o~ 9aici dr~t ~llminator for at lea3t p~rtlal dral~-
sge along respecti~re drai~age ps~age~, the psrtition mQan~ pre-
ser~tin~ the ~r cells of ~aid firse eliD2ina~0r 8eCtioD, and che
l~rst sheet~ beln~ loc ted to def ~ne lo~gitud~ n~lly parallel ai~
pa~age~ for r~cel~l~g alx from s,~id ou~le~ face a~d orie~ted
for dit~ert~g ~uch alr upwardl7 r~lat~ to ~he l~ ial path o2
the ~lr leavl~g s~d e~it face ~uch tha~ a ~ec~or r~pr~e~tlng
the tra~el o mol~t a~r alo~g aaid inlti~Ll pa~h, arld a v~ct~r
repre~enting the tra~l. of mol~t alr ~lorlg th~ ~ir pa~g~ o
10 said ~r~t s~ctiorl, cooperati~rely es~cabl~s~ing ~ r~fere~c~ pl~
the partition m~ d~fining he sir cell~ of ~ald ~cond el~ml
nator ~ect$on ~nd the seco~d sheet~ be ln~ loca~ed ~o de~ine longl-
tudln~lly parallel alr passage~ ~or recei~i~g a~t aft:er flow
thereo~ through said fir~ ol~ to~ ~ctlo~ snd orie~ted for
dlvart~g such air lat~rall7 r~lati~e to th~ pa~h o~ ~ir lea~ing
~aid ~rst ~l~mlnator aectlo~, ~u h ~hs~ a ~eccor represerL~in~
thg t~aYel of air alon~ t~e air pa~ages of s~d ~econd ~ectlon
is a1: an angl~ relat~e to ~aid re~er~ce pla~a.
In another aspect, the present invention provides
a drift eliminator structure adapted to be positioned
adjacent the air exit face of the fill structure of a
cro~lo~ cool~n~ tow~r for remoYi~g e~tra~ed water droplet8
fr~m the moist a~.r, leavin~ a~id f~ll 8txu~ture, sa1d drl t el~m~
na~or at~ cturQ co~pri~ing: ~ plural~ of horizo~tally ~paced,
elonga~ed, ge~rall~ upright, tran8~aræel~ V~ ped member~ each
h~vln& firs~ and 8econd generally pla~ar she~tg oriented at a~
~ngle relatiYe ~o each other; par~lon nean~ ~oined to and po-
~it~n~.d bet~ee~ each oppo~d pair of ad3~cent Rheets of proxi-
mal Y-shaped me~bers dividing the space therebetween înto i~di-
30 vidua~, elo~gated discrete cells loc~t~d for pa~sage of flll-
d~rlved moist air ~chereehrough, ~he air cells ~etween th~ f~rst
~ - 5a -
a~d ~econd ~heet~ re~pectively ~resenting corre~po~ding side-b7-
~ide fir~e and ~econd eliminator ~ectlo~ id ~ide-b7-side elimi-
nator ~ection~ between re~pecti~e pair~ of V-~haped me~bers be~ng
located in ~paced relation~hip to one ano~her to deflne therebe-
tween generally upright water draina~e passages for e~ch cell
respectiv~ly and extendlng generally ro~ the ~op to the bott~m
of ~aid drlft eliminator for at least part~al water drai~age along
resyective dral~age p~age~, t~ p~rt~tion mean~ pre~enting th~
~lr cell~ of s~id fir~ elimlnator s~ction and the fir~t ~heet~
bei~ located to define long~tu~inally parallel air cells for
receivi~g ~ir ~rom aaid outle~ ~ace ~nd ori~ted for divertlng
such air upw~rdly relat~e t~ the initial p~th of the air lea~Lr~
~a~d exit ~Ace ~uch th~t a vector repre~enti~g the t~a~el of ; 3t
air alo~g said initial path, ~nd a ~ector repre~nting the tra~el
of moi~ air alo~g the air passa~e~ of sald ~irst ~cti~n, co-
operstively establishin~ a referencP plane, the par~ition me~3
defining the ~ir cell~ of said ~econd elimi~ator section and the
seco~d sheeta belng locat~d to define longitudinally parallel a~r
pas~age~ for receivi~g ai~ ater 10w thereof through ~ald f~r~t
oliminato~ ~c~o~ aad orlented ~or d~erel~g ~uch Rir laterally
relat~e to th~ p~th of ~lr leav~ng said fir~t elimi~ox ~ec~lon,
~uch th8t ~ ~ector repEesent~Qg the t~avel of ~ir al~g ehe air
paa~a~e~ of ~aid 8ec~d ~a~lo~ 4~ a~ ~ sngl~ r~l~tiv~ to ~aid
r~f~ranc~ pla~e.
In a still further aspect of the present invention,
a method is provided for removing entrained water particles from
a moist sir~tream tra~eli~g a~o~g a ge~erally hor~o~tal in~ti~l
path, eompr1sl~g ~:he 8tep8 of: ~ni~ally divertl~g ~aid moist
air~tre~ upwardly relsti~e to sald ~ ia} path such ths~ a ~ector
represe~ti~g ~ravel of ~he i~ a~r ~long ~aid l~ltlal pa~h, ~nd
a vectox ~eprese~tlng txa~al of the molst al~ during ~a~d upward
and lateral diverslo~, cooperati~l~ e~tablish a reference pla~e,
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said diverslon lncludl~g ths~ 8t:ep5 of moving ~aid moist air into
i~dlvidual elongated fir~t ~lr eell~ located in parallel relatton-
ship and orie~ted :or cau~l~g ~aid upward d~version ~d de1ned by;
walls pre~e~ting said flr~ air cells th~rebetwe~; thereaf~er
seco~darll~ diYerting the i8'C Air 1at~rRlly relQtl~7e to the
pa~h of the alr from the firs~ air cellB ~ch that ~ v~ctor repre~
sentl~g travel of the mol~t 8ir du~.i~g the ~econd lateral diverslon
~hereof i8 ~t a~ le relat~ve . o said reiEerence pla~e, said
~econdEIr~ divar310~ clud~r~g the ~Iteps o~ virlg ~aid molst air
from said f~ r~t alr cella into ind~vidual elo~ga~ed seco~d a~r
cell~ spaced fro~ the flr~t a:Lr.~cells di~oaed i~ parallel rela-
tioDLship ~d or~ ented ~or cau~ a~ d ~e~ond lateral divez~lon
and defined by wall~ pre~e~ting said second air cell~ therebetweer~;
permitting the entr~ined ~ater p~ticles irl said nlr~tream to lm-
pin~e agaiwt ~he wall~ d~firLi~g said fir~ d ~eco~d alr cPlls
durl~g ~ald ~ltial aDd ~econdar~ dlv~r~ior~ of the ai~tream; and
draini~g th~ water collected by Ylrtue of ~aid implngeme~t by al-
low~g ~t lPast a p~t of ~a~d w~t~r to gra~itate be~ee~ ~ld
first s~d ~econd alr c~l~. 8 along th~ spac~ therebe~eeII .
2C In th~ drawingn:
Figure 1 is a fr~mentary end elevational view o a
dual pat~ ~lticell eliminator pack and ~howing a pair of ~qpaced,
angulaxly corrugated neoprene asbesto~ 5ection5 secured to a
tra~sver3ely V-shaped support panel therefor;
Fig. 2 is a fxagmentary, side elevational view OIC t}~e
eliminator pack illustrated in Fig. l;
~ig. 3 is a ~ragmentary top plan view o the drift
eliminator pack depicted in Fig. 2;
Fig. 4 is anotner 3idP elev~tional view of the drift
eliminator paek depicted in Fig~. 2 and 3 and taken along line
4-4 o~ Fig. 3;
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Fig. j is an essentially schematic, frag~en~ar~f ~D
plan view of a pair o~ nes~able drlft eliminator pack~, shown in
complemental nested relationship.
Fig. 6 is an essentially schematic, fragmentary Pnd
elevational view of a drift eliminator pack illustrating the water
droplet removal operation thereof in a cros~low-~ype cooling tower;
Fi~. 7 i3 aIl essentially schematic top plan vie-~ of a
pair of nested elimina~or pack~ and further ~how~ng the wa~er
droplet removal ~unction thereo;
Fig. ~ is a graphic~l repre~entation ~howing th~ en-
hanced drift elimin~tion capabil~es of the eliminator ~tructures
of the pre~ent invention, compared with a coplanar-~ype two pa~s
honeycom~ dri~t eliminator depicted in U. S. Patent No. 3,065,587;
~ig. 9 is an ess n~ially 3chema~ic, fragmentary, ve~-
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t:ical sectional view of a hyperbolic crossflow cooling tower
shown with a plurality of multi-pack, vertically stacked elimi-
nator sections positioned adjacent the exit face of the fill
structure thereof;
Fig. 10 is an essentially schematic, fragmentary, ver-
tical sectional view of a mechanical draft crossflow cooling
tower with a plurality of multi-pack, vertically stacked elimi~-
nator sections positioned adjacent the exit face of the ~ill
structure thereof;
Fig. 11 is an essentially schematic, fragmentary, ver-
tical sectional view of a mechanical draft crossflow cooling
tower, illustrating a plurality of vertically stacked eliminator
sections in an inclined, complemental orientation relative to the
exit face of the structure ~hereof; and
Fig, 12 is a view identical with that shown in Fig. 11
excépt that the eIiminator sections are in horizontally offset
relationship with one another.
Drift eliminator pack 20 incorporating the preferred
concepts hereof is illustrated in Figs. 1-4. In general, elimi-
nator pack 20 comprises a plurality of side-by-side pairs o~ air
passage-defining partition means pre~erably in the fo~m of elon-
gated, angularly corrugated sPgments 22 7 with the opposed seg-
ments of each pair being sandwiched between a pair of identical,
preformed7 imperforate, transversely V-shaped support panels 24.
The latter present first and second generally planar
sheets which are angularly oriented with respect to one another.
The segment pairs and panels are positioned in alternating, ad-
hesively secured, stacked relationship as best seen in Fig. 2 in
order to define an elongated, multicell dual path eliminator pack.
Each segment 22 is an elongated? preformed member
preferably composed of neoprene asbestos and having a plurality of
aligned, side-by-side, generally sinusoidal, angularly disposed
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corrugations 26 along the length thereof. Similarly, each panel
24 is an integral member preferably formed of neoprene asbestos
and presenting an included obtuse angle "X" (see Fig. 3). Al-
though other materials such as vinyl can be used to ~orm seg-
ments 22 and panels 24, neoprene asbestos is preferred from the
standpoint o~ cost and ease of fabrication.
Referring specifically to Fig. 3, it will thus be seen
that eliminator pack 20 presents a first cellular section 28 with
a secondary, identically configured cellular section 30, laterally
disposed with respect to section 28 and separated therefrom by a
distance referred to by the numeral 32. The individual elongated
cells within each cellular section 28 and 30 are defined by the
individual corrugations 26 in the respective segments 22, as well
as the adjacent support panels 24, as will be readily seen.
The angular, generally V-shaped disposition of the sup-
port panels 24 permits complemental positioning o~ a number of
eliminator pac-ks 20 in aligned, end-to-end relationship as de-
picted in Figs. 5 and 7. For example J a pair of ~liminator packs
20a and 20b can be complementally and nestably positioned in an
abutting manner without any objectionable vertical gaps along the
joint therebetween. This permits rapid positioning of a plu-
rality of adjacent eliminator packs 20 in complemental, juxtaposed,
covering relationship to the air outlet face of cooling tower
fill structure without the need of shiplap joints or other mechani-
cal interconnection between the respective eliminator packs, as
has been conventionally required.
Most important however, the configuration of the elimi- --
nator packs 20 is designed to present a dual path, individually
draining, multicell unit that has proven to be extremely efective
in removing entrained water particles from moist airstreams leav-
ing the exit face of cooling tower fill structures. Referring to
schematic Figs. 6 and 7 wherein the water droplet removal opera-
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tion of the present eliminator in a crossflow type tower is de-
picted, it will be seen that the moist air is initially directed
against the air inlet face of ~irst cellular section 28. By vir-
tue of the fact that the individual cells thereof are inclined
upwardly relative to the initial path of air, the air is first
diverted along the inclined path thereof in passage therethrough.
Upon lea~ing the cellis of first cellular section 28,
the moist airstream next passes through the laterally oriented,
upwardly inclined cells o~ secondary cellular section 20. It is
important that the secondary air diversion path defined by cellu-
lar section 30 is æituated to one side of the first diverslon
path presented by section 28 in order to enhance the water removal
capabilities of the overall eliminator. Actual test results have
proven that this relative disposition of the respective cellular
sections has the effect of dramatically increasing ~he e~fective-
ness of the eliminator.
In order to more precisely describe the relative orien-
tation of diversion path defining sections 28 and 30 relative to
the initial path of molst air, the following is helpful. For ease
of discussion, the initial path and magnitude of such moist air
can be thought o~ as a representative single vec~or 38. Upon
entering section 28) the air represented by vector 38 is diverted
along a first diversion path represented by vector 40 which is
situated at an angle relative to vector 38. Vectors 38 and 40
also establish a reference plane which may be essentially ver~
cal or at any one of a number of angles with respect to the verti-
cal. The moist air next enters section 30 and is redîverted along
a second diversion path represented by vector 42, As best seen in
Fig. 7, vector 42 is situated at an angle with respect to the
reference plane established by vectors 38 and 40.
It will t:hus be seen that the preferred eliminator struc-
ture hereof is operable to divert the initial moist air path first
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upwardly and laterally and then laterally again so that the moist
air is varied in a number of directions duri.ng travel thereof
through the eliminator. In any event, such a dual path structure
defined by the relative dlsposition of the cellular sections mak-
ing up the eliminator has been proven to dramatically increase
drift elimination.
As discussed, the indivua.l cells defining ~irst cellu-
lar section 28 should be oriented at an upwardly inclined angle
relative to the initial path of moist air in order to initially 10 direct the moist airstreams therethrough. In more de~initive
terms, thls angle should broadly vary between about 10 to 60
relative to the horizontal in a crossflow tower application, more
preferably from about 15 to 50 , and most preferably at an angle
of about 30 .
It is also extremely desirable from the drit elimina-
tion standpoint to angularly orient the cells of secondary cellu-
lar section 30 with respect to the initial path of moist air, in
addition to the lateral disposition thereof relative to the cells
of cellular section 28. In this regard, the same inclination
angles listed above in connection with the cells of section 28
can be used to good advantage in orienting the cells of section
30. This has the effect of directing the streams upwardly through
the entire eliminator to facilitate discharge thereof from the
tower. Moreover, this orientation minimizes the objectiQnable
pressure drop across the eliminator.
During travel of moist air along the first and second
air diversion paths deined by cellular sections 28 and 30, the
inertia of the entrained water particles causes the latter to
impinge against the defining cellular sidewalls of the sections.
This in turn causes collection of the impinged water particles
on such sidewalls and permits removal o~ water droplets by gravi-
tational drainage, illustrated by arrows 44 and 46 in Fig. 7.
1 ~ ~ 5~ 7~
Such water drainage is greatly facilitated in the
present eliminator hy provision of the spacing 32 between cellu-
lar sections 28 and 30. By virtue of this spacing, the water
collected in each individual section 28 and 30 can he separately
drained to the cooling tower basin therebelow. This is advan-
tageous because of the fact that la:rge volumes of water, if drained
only from the alr entrance face of the eliminator, could cause
water blockage of the inlet face wh:ich in turn increases the static
air pressure drop across the eliminator and deleteriously effects
the overall per~ormance thereof. Thus, the spacing 32 between the
cell sections is particularly preferred, especially when the elimi- -
nator 20 is to be utilized in the crossflow type of cooling tower
where the ellminator packs are positioned in a generally upright
orientation.
The eliminator packs of the present invention are usable
in virtually all types of evaporative crossflow cooling towers.
Figures 9-12 illustrate the use of the present eliminators in the
context o~ annular crossElow cooling towers, which include circum-
scribing upright fill structure 48, an annular hot water delivery
basin 50 thereabove, and a cold water collection basin 57 under-
lying the fill. Fill 48 defines a central plenum chamber 54 with-
in the confines thereof, the latter being in communication with the
air currant-inducing apparatus associated with the overall tower.
For example, in Fig~ 9, an upright, natural draft-inducing hyper-
bolic stack 56 is fragmen~arily depicted, and in Fig. 10, a mechani-
cal draft-inducing fan assembly 58 is shown. Either of these ex-
pedients can be ut:ilized for inducing crossflowing currents of air
through ~ill structure 48 for evaporative cooling of hot water
descending through the latter.
It will be seen that the annular eliminator structures
utilized for drift el.imination with relatively tall, annular cross-
flow fill structures are comprised of a series of vertically stacked
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and juxtaposed eliminator sections which are defined by a number
of side-by-side, nested ce].lular eliminator packs 20. For example,
our sections 60, 62, 64 and 66 are shown in Figs. 9 and 10, and
the latter cooperatively extend substantially the entire height
of the respective fill stru~tures 48 in proximal, complemental
relationship with the air outlet faces thereof.
A mechanical draft crossflow cooling tower is also il-
lustrated in Fig. 11 wherein conventional fill structure 68 is
employed which is configured and arranged to compensate for water
pull-back at the base of the fill. Eliminator structure 70 is
inclined at substantially the same angle as the exit face of the
fill and i8 comprised of a series of three inclined eliminator
sections 72, 74 and 76. Thus, the overall eliminator structure
70 is complementally arranged with respect to the air outlet face
of fill structure 68.
In other instances, it has proven to be beneficial to
utilize an eliminator structure 78 as shown in Fig. 12 having
horizontally offset, multi-pack eli~inator sections positioned
with the lowermost section situated at the innermost position,
and all higher sections being horizontally offset outwardly there-
from. In this embodiment lowermost eliminator section 80 is
situated at the innermost position with higher eliminator section
82 and 84 being horizontally offset with respect thereto.
Actual testing in practice has proven that the dual path
dri~t eliminators hereof give dramatically enhanced water particle
removal from moist airstreams, as compared with conven~ional units.
It is beIie~ed that this stems from the use of first and second
cellular structures operable to first divert the mois~ fill air-
stream into a first di~ersion path disposed at an angle relative
to the normal path of the air, followed by a diversion along a
second diversion path dîsposed to one side of the first diversion
path. Such an irr~egular diversion of air through the eliminator
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maximizes the probability tha~ the erltrained water par~icles
will impinge against the defining sidewalls of the elimina~or cells
and thus collect for drainage therefrom. Also, provision of sepa-
rately draining first and second cellular sections as explained
is belie~ed to materially assist in drift elimination because
water accumulation and blockage of the air passages, and resul-
tant re-entrainment of water droplets, is e~fectively avoided.
These enhanced operationa:L characteristics will be
readily apparent from a study of the graphical representation of
Fig. ~. The latter represents a test conducted to determine the
respective water removal capabilities of a 5-inch width, two-pass
honeycomb drift eliminator similar to the type depicted in Fig. 9
o~ the drawings of U. S. Patent No. 3,065,587, compared with a
5-inch width dual path dri~t eliminator in accordance with the
present invention. The prior art eliminator uses coplanar, angu-
larly disposed cellular sections, The drit elimination capa-
bilities of the two~pass honeycomb were recorded as a function
of the velocity of air leaving a crossflow cooling tower ~ill
structure, and these results were arbitrarily taken to represent
a 100% drift rate. The same test was also performed with the
present dual path eliminator, and the results likewise plotted as
a function of airstream ~elocity from the fill structure. As
clearly shown in the graph, the drift elimination capabilities o~
the present eliminator structure are at least five times that of
the two-pass honey~omb eliminator at substantially all airstream
velocities. Thus, the bene~icial results obtainable with the
present eli~inator structure are conclusi~ely demonstrated.
In another series of tests the drift eliminator of the
present invention was compared to two~pass structure of the type
disclosed in U. S. Patent No. 3,5~0,615. In particular, two sepa-
rate packs of 3 and 1/4 inches thickness were used, with the packs
being oriented at 90 relati~e to each other and placed in stacked,
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abutting relationship across the air exit ~ace of a counterflow-
type test cell (at 0 relative to the horizontal) speci~ically
designed for measuring counterflow drift elimination. The alter-
nating corrugated sheets in each pack had a corrugation pitch of
1.83 inches (measured in a plane perpendicular to the corrugation
valleys~, and a two-thirds inch peak-to~peak thickness. The ef-
ficiency in parts per million o~ entrained water to e~it air was
measured at air velocities of 400 and 550 ft./min., with a re-
circulating water load of lQ gallons per minute per square foot
(based upon the area of the cell exit face).
As a corollary test, a drift eliminator in accordan~e
with the present invention was measured in a similar crossflow-
type test cell. Tlle eliminator had a total width of 5 inches and
was placed adjacent the air exit face of the test cell at an angle
o 12 1/2 degrees relative to the ~ertical. The distance between
the V-shaped members of the eliminator was two-thirds inches, and
the e~fective drainage distance between the adjacent cellular sec-
tions was approxi~ately 3/8 inch. The corrugations o~ the sheets
between the V-shaped members was upwardly inclined at 60 relative
to the eliminator ~ace. This eliminator was tested at 400 and
550 ft./min. air velocities with a recirculating water load of 10
gallons per minute per square foot.
In ~oth cases drift and pressure drop were separately
measured to determine relati~e drift removal ef~iciencies. The ~-
following table su~marizes these test results, wherein Test I is
the eliminator o~ ~he type disclosed in Patent No. 3,500,615, and
Test II is the eliminator o~ the present invention. For ease of
comparison, the drlft and pressure drop results of Test I are taken
as 100%, and those of Test II are expressed as percentages of
this standard.
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TABLE
Test I Test II
Air Pressure Air Pressure
Velocit~ Drift Drop Veloci~y Dri~t Drop
.
400 (ft. min) -- 100% 400 (ft/min) -- 75~8v/o
550 --100% 550 -- 74 3%
400 100% -- ~00 26~3~/o --
500 100% -- 500 23.~% --
600 100% - 600 26.3% -- -
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The above data demonstrates that the eliminator hereof
gives significantly greater drift elimination (by a factor of
about four times) at all air velocities tested; moreover, this is
accomplished with a lesser pressure drop than that e~perienced
with the two-pass eliminator of Patent No. 3,500,615. Further-
more, since the latter eliminator was tested in a counterflo~ cell,
the comparative results would be expected to be even more dramatic
if this eliminator were used on a crossflow test cell. This stems
from the known fact that counterflow eliminators have inheren~ly
better drainage by virtue o the orientation thereof, and that
poor test results on a counterflow cell indicate that even worse
results would be found in a crossflow test.
Although the reasons for the dramatic improvement of
the eli~inator of the present invention over the eliminator of
Patent ~o. 3,500,615 are not completely understood, it is hypo-
thesized that lack of individual pack drainage in the latter unit
is a primary cause. Also, the construction of this eliminator
inherently provides a ~ertain percen~age of relatively unrestricted
airflow channels for the moist air, as opposed to the posi~ive up~
~; ward and lateral air diversion~ provided by the eliminator hereof.
The eliminator constructions o~ the invention are also
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advantageous in that fahrication is a simple matter and amenable
to production line techniques. In practice, an elongated, hollow
form is provided ~or the production o~ the eliminator packs 20.
An initially transversely V-shaped support panel 24 is ~irst
placed at the bottom of the ~orm, and the upraised apex portions
o~ a pair of currugated segments 22 are coated with conventional
heat-setting glue. The coated segments 22 are then positioned
on the panel 24 in spaced, side-by-side relationship ~ith one
another. Alternately, a single, elongated corrugated member can
be longitudinally cut and spread over the ape~ o~ the support
panel after glui~g. In this case the segments are comlected by
a thin strip o~ material but are identical in every other way
with the separate pairs of segments. A second panel section 24
is then placed over the corrugated segments 22 and the glue coat-
ing and placement procedure repeated. This is continued until
an eliminator pack havîng the desired number of cell-de~ining
layers is built up in the ~orm. At this point, the ~orm is trans-
~erred to a heating oven whereupon the heat-setting glue serves
to bond the respective segments and panel sections into a com-
pleted eliminator pack. In this manner, ~abrication costs aregreatly reduced and unskilled workers can be employed in the pro-
duction procedure.
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