Note: Descriptions are shown in the official language in which they were submitted.
l(~S;~2~
This application is ~or an improvement invention
related to my prior filed u.S. patent application Serial No .
468,659, filed ~ay 10, 1974~ entitled "Air-to-Air Heat E~changer"
now U.S. Patent 3,905,850, and U.S. patent application Serial
No. 473,512, filed May 28, 1974, entitled `'Grease Collecting
Heat Exchanger Installation", now U.S. Patent 3,982,588.
The instant invention relates generally to fluid heat
exchanger apparatus adapted for exchange of heat between flowing
streams of fluid, and in particular to vertical counterflow heat
exchangers which can be employed as air-to-air or air-to-water
heat exchangers. The present heat exchanger apparatus is
especially useful in cooling hot exhaust air with cold water
for energy conservation and condensation of air pollutants, in
cooling hot water with cold ambient air, or in cooling hot
ambient air with cold water for air conditioning.
According to one aspect of the present invention
there is provided a heat exchanger apparatus comprising counter-
flow heat exchanger means including a first set and a second
set of heat exchanger passages separated from each other by
heat exchanger plates in heat exchanging relationship with said
first and second passages on opposite sides thereof, both sets
of said passages extending completely through the heat exchanger
between inlets and outlets; support means for supporting the
heat exchanger means so that said passages extend substantially
, vertically between their top ends and bottom ends; gas trans-
~ mission means for transmitting gas into inlets at the bottom :
'. ends of the first passages and causing said gas to flow upward
through said first passages out of outlets at their top ends; and
liquid transmission means for spraying liquid directly onto the
surfaces of the heat exchanger plates in the second passages
l adjacent the top ends thereof and causing said liquid to flow
downward through said second passages along said surfaces and
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out of outlets at their bottom ends so that said liquid and
said gas flow in opposite directions along the surfaces on
opposite si.des of the same portion of one of said heat exchanger
plates for direct counterflow heat exchange laterally through
the thickness of sa~d plates.
It has ~een known to spray ~ater into one set of
passages in air-to-air heat exchanger, as shown in U.S. Patent
1,4Q9,520 of Bird and U~S. Patent 2,825,210 of Carr. In the
former patent the heat exchanger i~ horizontal and the water ~ :
is sprayed in the outlet end of one set of air passages so
that the ~ater does not flo~ down the length of the passages.
In the latter patent the heat exchanger plates are supported by
ru~ber spacers ~hich separate the two different sets of passages
so that there is no appreciable direct lateral transfer of heat
through the thi.ckness of the separating members in the manner of :.:
the counterflo~ heat exçh.anger of the present invention.
The pre~ent air-to-water heat exchanger apparatus has
the advantage. that the exit temperature of the air being cooled
or of the w~tex ~eing heated can he easily controlled by adjust-
ing the ~ater flo~ or air flow with a valve or damper which
may be automatic~ operated by a temperature æensor. Another ~-
~ advantage is that the apparatus is reversible and can also be
'~ u~ed for cool~.~g hot ~ater and warming cold air without modifi-
cat;ons in the heat exchanger. In addition, the high latent
~heat of steam ox moist exhaust air can be recovered by transfer
to clean water flow~ng through other passages in the exchanger
fox heating ~uild~.ngs ox other uses.
i According to another aspect of the present invention
there is provided a heat exchanger and condenser apparatus
3Q comprising: a plurality of counterflow heat exchanger units
each including a first set and a second set of passages separated
from each other by heat exchanger plates in heat exchanging
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relationship with the first and second passages on opposite
sides thereof; support means for supporting the heat exchanger
units in at least two rows so that said passages extend sub-
stantially vertically between their top and bottom ends; a
pair of inlet conduits each extending across one of the ends of
each of the heat exchanger units in a different row; an inter-
mediate conduit extending between said pair of conduits across
said one end of both rows of heat exchanger units; a discharge
conduit extending across the other ends of both rows of heat
exchanger units; first transmission means for transmitting hot
exhaust air in through said pair of conduits, through said first
set of passages in said heat exchanger units and out through
said discharge conduit; and second transmission means for
transmitting another fluid through said second passages in said
heat exchanger units in the opposite direction to said exhaust
air and out through said intermediate conduit, said other fluid
being colder than the exhaust air to cool said exhaust air :
sufficiently to cause gaseous pollutants therein to condense on
the surfaces of said first passages as liquid pollutants which
2~ flow down said first passages and out of the heat exchanger ~ -
units.
If the condensed pollutants tend to solidify as a
deposit on the surfaces of the passages, they may be removed by
injecting solvents or cleaning agents into the air flowing
through such passages. In addition, solid particle pollutants
~, can be removed from the air by depositing water or a more
viscous liquid, such as oil, on the surface of the passages to
collect impinging particles and remove them with the collecting
liquid.
3Q According to a further aspect of the present invention
there is provided a heat exchanger apparatus comprising: ;
counterflow heat exchanger means including a first set and a
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second set of heat exchanger passages separated from each
other by heat exchanger plates in heat exchanging relationship
with said first and second passages, both of said sets of
passages extending completely through said heat exchanger
between inlets and outlets, said heat e~changer plates having
their ends split into two end portions which.are joined to
different heat exchanger plates on opposite sides thereof to
form said first and second passages; support means for support-
ing the heat exchanger apparatus so that said passages extend
substantially ~ertically between top ends and bottom ends;
first transmission means for transmitting a gas into inlets at
the bottom ends of the first passages and causing said gas to
flow-upward through. said first passages out of outlets at
their top ends; and second transmission means for transmitting
another fluid into inlets at the top ends of the second passages
and cause said other fluid to flow downward through said second
passages along said $urfaces and out of outlets at their bottom
ends.
The splitting of the ends of the heat exchanger plates
; ~Q provides a more ef~icient heat exchanger which is capable of
handling an extremely large amount of air flow in the range of
hundreds of thousands of cu~ic feet per minute.
Counter~low heat exchangers have been proposed, such
as in my earlier U.S. Patent 3,381,747, comprising a series of
- heat exchanger plates disposed within a housing defining a
multiplicity of channels or passages extending side-by-side along
the housing and constructed so that fluid flowing in alternate
ones of the ch.~nnels exchanges heat with the 1uid flowing in
: the remainder of the channels. To be efficient, the exchanger
- 3Q plates defining such channels should have large surface expanses
exposed to the fluids passing through the exchanger. Toward
these ends, I have found that thin metallic sheets of consider- :
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able width, and preferably corrugated to increase the
turbulence of fluids passing through the exchanger, may be
utilized in producing a highly satisfactory exchanger for many
types of applications.
In the manufacture of such an exchanger, because of
the flexible nature of the plates or sheets making up the
exchanger plates, and the great number of plates which ordinarily
make up a typical exchanger, there are certain problems presented
in assembling the unit with the plates properly positioned in a
permanent manner within the exchanger, and with the completed
unit having the desired strength and rigidity. To be kept in
mind also is any method utilized in making the exchanger should
be one which lends itself to be performed without the need of
using highly trained personnel, and in a quick and expeditious
manner.
In the accompanying drawings which illustrate
exemplary embodiments of the present invention:
Figure 1 is a diagrammatic elevation view illustrating
an air-to-water heat exchanger apparatus made in accordance with
one embodiment of the present invention, with parts of the
exchanger housing broken
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JC:srd 19484 3/1/78
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away for clarity;
Fig. 2 is a perspective view of a portion of
the assembly of heat exchange plates and associated
water sprayer provided in the heat exchanger apparatus
of Fig. l;
Fig. 3 is a horizontal section view taken along
line 3-3 of Fig. 2;
Fig. 4 is a perspective view of an air-to-air
heat exchanger apparatus in accordance with another
embodiment of the invention; and
Fig. S is a vertical section view taken along
~; line 5-5 of Fig. 4.
~ A preferred embodiment of the heat exchanger
, apparatus of the present invention is the air-to-
water heat exchanger apparatus shown in Fig. 1 and
includes a counterflow type of heat exchanger 1. The
heat exchanger includes a housing containing an assembly
' ~ of heat exchanger plates shown in Fig. 2 which form a
first set and a second set of fluid passages separated
by the exchanger plates in a manner hereafter described.
.. ,
Heat exchanger 1 is supported so that the passages
extend substantially vertically between top and bottom
,~ I
ends. The bottom ends of one set of passages are
connected to an air inlet conduit 2 which transmits
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air into such inlet from any source, such as a source
of hot humid exhaust air having a temperature of, for -~
~, example, 180F. dry bulb and 140F. wet bulb. The
top ends of such one set of passages are attached to
an air outlet conduit 3 which discharges the air to the
atmosphere after it is cooled in the heat exchanger 1
while flowing upward through the one set of passages
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in the direction of ~rrows ~. "luch of the moi~ture
in the air condenses on the surfaces of the passages
and flows downward out of the heat exchanger apparatus
through a drain. As a result, the dischargea air at
outlet 3 is also of lower humidity and may have a
temperature of 60F. dry bulb and 6~F. wet bulb.
The other set of passages in the heat
exchanger have their top ends employed as water ~-
inlets 5 by providing a water sprayer 6 either outside
of the heat exchanger and above the water inlets or
; inside the heat exchanger within such inlets. Water
is sprayed onto the surfaces of such other set of
passages by sprayer 6 adjacent the top ends thereof
and is caused to flow downward in the direction of
arrows 7 along such surfaces provided by one side of
the heat exchanger plates. When cooling hot exhaust
air, cold water of, for example, about 40F. is
delivered to the heat exchanger by sprayer 6 and hot
water of, for example, about 140F. is discharged
into a water outlet conduit 8 connected to th~ bottom
ends of the other set of passages. As shown in Fig, 1,
the heat exchanger 1 is supported in a vertical
~, position and may extend through a hole in the roof 9
of a building containing the source of the hot exhaust
air.
The heat exchanger plate assembly 10 within
the e~changer is shown in Fig. 2 and includes a plurality
-$ ~ of exchanger plates 12, 14, 16, 18, and 20. The plates
are arranged in the assembly in substantial parallelism.
Each of the plates has a length conforming sub~tantially
to the length of the exchanger with which the assembly
i~ to be incorporated. The plates further may be
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;rc ~ ]~83-1~490 ~/2~/76 ~1
provided with corrugations extending transversely of
the plates, whereby any fluid, liquid or gas, moving
through the exchanger is given a degree of
turbulence.
Each of the plates at each of its ends i5 '~
split with a cut 22 extending longitudinally of the
plate. The cut parallels the longitudinal edges 26
and 28 of the plate, and normally is made about mid-
way between the longitudinal edges, thus to divide
the end of each plate into a pair of end portions or
tongue segments, exemplified by tongue segments 12a ~-
and 12b, of equal width.
The tongue segments of each exchanger plate
end are shown bent in reverse directions. ~hus,
tongue segment 12a, as shown in Fig. 2, is bent to
curve outwardly (where it will meet with the housing
of the exchanger which i3 assembled about the core
~ ~ element) and tongue ~egment 12b below segment 12a is
;i bent to curve inwardly. Considering exchanger
~plate 14, its upper tongue segment 14a is bent inwardly,
whereas its lower tongue segment 14b is bent outwardly
to meet tongue ~egment 12b. Where adjacent ends of
tongue segments meet, they may be fixed together using
a~overlying angle piece, such as angle piece 24,
secured in place as by crimping.
It will be noted that whereas the upper
tongue segment 12a of plate 12 is bent outwardly, and
the lower one 12b is bent inwardly, at the opposite
end of the exchanger plate the upper tongue segment 12c
is bent lnwardly wherea~ the lower one is bent outwardly.
This same relationship holds true for the tongue
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segments at each set of ends of an exchanger plate. ~ ;
A divider member shown at 30, including a horizontal
wall expanse 32 and a vertical marginal flange 34,
may be inserted into cuts forming the tongue segments,
at each set of ends of the exchanger plates. The
divider member, when positioned as shown in Fig. 2,
serves to separate end portions of channels defined
on opposite sides of the various plates~ Thus, and
considering channel 40 in Fig. 2, th0 divider separates
this channel where such is defined between tongue
se-g~emts 18a, 16a, from portions of channels 38 and
42 below the divider, defined between tongue segments
20b, 18b, and 16b, 14b respectively.
~ s shown in Fig. 2, one set of passages or
channels 36, 40, and 44, at the end of the assembly
pictured at the bottom of Fig, 2, open to the end of
the assembly above the divider. At the opposite end
of the assembly, these channels open up to the end
of the assembly below the divider. ~he reverse i5
true for the other set of passages or channels 32, 42, ~ -
, . . .
~ and 46, which at the end of the assembly pictured at
~.,
the bottom of Fig. 2, open to the end of the assembly
below the dlvider, and at the opposite end of the
assembly, open to the end of the assembly above the
di~ider.
With the arrangement, and assuming thP
prese~ce of an encompassing casing, it should be
~ obvious that one set of channels may be utilized for
: r~ : the passage of one body o fluid through the exchanger,
and an alternating set for the passage of another body
of fluid through the exchanger, with such bodies of
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JC:p~ 19~8~~~9~9Q 2/2~/7~ ~1
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fluid passing through multîple flow paths inter~persed
with each other.
In making an exchanger with a core element
of the type described, and when it is remembered that
typically a far greater number of exchanger plates
are utilized than actually pictured in Fig 2, it
should be obvious that a problem arises with respect
to positioning properly the adjacent exchanger plates
where they extend in expanses between the ends of the
~ 10 plates. The plates usually are made of ~hin metal,
: and if corrugated tran~versely of their lengths, have
considerable flexibility in a transverse direction.
~'~ Further, they are easily twisted. Obviously, if
the plates are not properly oriented in the aompleted
exchanger with substantially uniform spacing existing
between them where they extend throughout their length,
~, the efficlency of the exchanger i9 affected. ~-
Thu~, according to this invention, the
~arious exchanger plates are arranged substantially as
pictured in Fig. 2. During assembly, and to tie the
various exchanger plates together, tying clips 48,
which may be metal strips attachable ko the edges of
the plate~, are assembled with the plates by fixedly
attaching them to~the edgeY of the plates at regions
; spaced along the length of the assembly. The clips
; are attached to each of the opposite sets of adjacent
edges in the plate~as~embly. The tying clip 48
specifically illustrated has slotted depressions formed
in it, the slots receiving edge portions of the plates
whlch may be twisted slightly after heing passed
through the slots to hold the clip in place. The
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l~ZZ~
exchanger plates are also fastened together at their
ends through joinder of the tongue segments with angle
pieces 24.
~s a next step in the manufacture of the
exchanger, a set of adjacent longitudinal edges 26 or
28 in the exchanger plate assembly 10 is permanently
fixed by embedding or encasing the edges in a re.sin
slab 49. In preparing such a slab, reinforcing
material, such as a fiberglass sheet, is laid down
lQ along the interior of a section of the metal housing
50 of the heat exchanger. Poured over this sheet is
a mass of uncured, hardenable synthetic plastic resin
material 49, such as a liquid epoxy resin, which is a
thermosetting resin that cures to form a hard mass.
The resin impregnates the reinforcing sheet, and the 1~-
~, :
~i~ resin and sheet form a hardenable layer on the inner
surface of the houæing section. The housing section,
which may be made of sheet metal, constitutes a form
; ~ . , .
confining the resin layer during this stage of the
i5e~ 20 manufacture~
The assembly of exchanger plates may then be
f~tted within the housing section! with a set of edges - -
` 2~ or 28 of the plates, as well as any tying strips 4
ccnnecting these edge~, then pressed downwardly to be
sunk into the layer 49 of resin and reinforcing
material. After a~period of time, on curing of the
resin mass, a strong,~r~gid slab 49 of synthetic
pla~tic results which bonds the longitudinal edges of
the heat exchanger plates to the h~using 50. Such slab
`30 ~-~ seals-the edges of the plates, and provides lnsulation
~`'7 ~ along one side of the exchanger, as well as forming a
i .. ;: , . .
~C.},w 1~4~3~ 2J26~7h ~1
rigid structural element along one side of the
plate assembly.
This operation may then be repeated ~y
preparing in another housing section another layer of
; resin and reinorcing material similar to the one
just described. The assembly of exchanger plates
may then he inverted, and the edges in the opposing
set of edges of the plates, together with tying strips,
sunk into this layer of material. On hardening,
another rigid slab is thus prepared encasing the edges
of the opposing set, and forming a rigid unit of slab
and various exchanger plates.
An article prepared as above includes the
core element of assembled exchanger plates, having
~i cured slabs of reinforced resin uniting and sealing
the edges in the opposed set of edges of the plates.
Encompassing the slabs of resinous material, and portions
of the sides of the exchanger plate assembly, are
~i housing sections which are joined together to form
the completed housing.
,
~¦ As shown in Figs. 2 and 3, the sprayer means
J 6 may include a plurality of pairs of sprayer pipes
51 provided ln each of the water passages 38, 42,
and 46 extending across their width adjacent the upper
ends thereof. The sprayer pipes 51 spray water onto
: ,
the surfaces of such passages adjacent their top ends
throu~h spray openings 52 spaced along such pipes.
.
~- ~ The water flows down the length of such passages in
the direction of arrows 7 since they are supported in
a vertical position. The sprayer pipes 51 may be of
about 1/4 inch inner diameter and are connected to
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JC :}~w 19483-19490 2~2~/7~
32;~1 ~
larger header pipes 53 of one inch inner diame~e~ which in
turn - are connected to a main line pipe 54 of 4 inch
inner diameter. The main line pipe 54 is csnnected to
a water supply 56 through a valve 58. The water
supply may he connected to the output of a water
cooling tower whose input is connected to the water
outlet conduit 8 of the heat exchanger to reuse the
water after it has been cooled. The valve 58 may be
automatically or manually adjusted to vary the flow
of water through the heat exchanger and thereby
control:`the temperature of the air discharged from
such exchanger through conduit 3.
In addition, the heat exchanger apparatus of
Fig. 1 can be provided with a drain pipe 60 connected
to a collecting basin 61 in the bottom of the air
inlet conduit 2 to drain off any condensed water or
1 . :.
,~ pollutan~, such as carbonaceous vapors which con~ense
from the exhaust air as liquids onto the ~urfaces o
the heat exchanger passages through which the exhaust
alr flows. Thus, some of the air pollutants may he
chemical solvents which after condensing in the heat
, ~ -
exchanger run down the heat exchanger plates and are
recovered through the drain 60. In order to clean the
; surface~of the heat exchanger plates and remove solids
deposited on such plates, a source of cleaning liquid
62 is connected th~ough a valve 64 to the air outlet
conduit 3 at the top end of the air passages of the
heat exchanger. Thus, cleaning liquid is periadically
2 - ~ ~ injected into;the conduit 3 and flows down the ~urfaces
of the air passages for cleaning. Alternatively, the
cleaning liquid can be evaporated into the hat air
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~C:p~ 194~ 490 2/26/7~ ~l
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and transmitted into the inlet conduit 2 so th~t such
cleaning liquid condenses on the surfaces of the
first set of heat exchanger passages as the air flows
upward in the direction of arrows 4. ~he condensed
cleaning liquid flows downward along the surfaces of
the first passages and removes any solids deposited
on such surfaces. The condensed cleaning liquid is
collected in the basin 61 and is transmitted through
the drain 60 to a suitable evaporator (not shown) for
reevaporating it into the hot air stream to provide
a continuous cleaning operation.
Figs. 4 and 5 show another embodiment of the
vertical counterflow heat exchanger apparatus of the
present invention including a plurality of heat
exchanger units 1 similar to that previously describea
in Figs. 1 and 2. The heat exchanger units 1 are
supported in two rows so that the passages within such
heat exch~ngers extend substantially vertically. As
shown in Fig. 5, cool ambi~nt air flows upward in
~ !j 20 the direction of arrows 4 through one set of passages
and hot exhaust air flows downward in the direction of
arrows 7 thr~iugh the other set of passages. The two
sets of passages are separated from each other by the
' ' ! . `
heat exhanger plates a~ shown in Fig. 2.
In the preferred em~odiment, the heat exchanger
apparatus of Figs. 4 and 5 is employed to cool and
~b~ condense pollutants from hot contaminated exhaust aix
such as i9 emitted ~y a wood veneer dryer. The cold
.,,~
~;1 ambient air cools the hot exhaust air as it passes
: ~
~ 30 downward through the heat exchanger and causes
~ carbonaceous vapors and other gaseous pollutants
:~ -14-
JC pw l~t~3--19~0 ~r,~76 ~1
contained within the exhaust air to condense onto
the surfaces of the heat exchanger passageways. The
condensed pollutants are deposited as liquidc onto
the surfaces of the heat exchanger plates so that they
drain down such heat exchanger plates by gravity into
an exhaust air collection duct 66 extending horizontally
along the bottoms of the heat exchanger units. The
exhaust air is sucked from the bottom end of the heat
exchangers in the direction of arrows 67 through duct
66 by an exhaust a~r fan 68 to an exhaust discharge 70
which may be connected to a suitable exhaust stack
(not shown) which opens to the atmosphere. As a
result of the suction of the exhaust fan, a slightly
negative pressure is produced in duct 66 and the exhaust
air passages of the heat exchanger units 1 and the
exhaust air input ducting to such exchanger. ~he bottom
of the exhaust duct 66 slopes downwardly to a collec-
tion tank 72 where the liquid pollutants;are collected
. i - .. , -. for periodic removal.
~he contaminated exhaust air is transmitted
into thP apparatus of Fig. 4 through an exhaust inlet
duct 74. A filter sect~on 76 is provided in the inlet
i~ duct to filter solid particles from the exhaust air
before it is transmitted to a pair of side ducts 78
. .
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q`~ and 80 extending horizontally across the top ends of -
the two rows of heat exchanger units. The exhaust air
is transmitted through side ducts 78 and 80 in the
, ~ :
direation of arrows 81 and downward through the heat
exchanger unit~.
.-~ 30 Cold, clean ambient air is transmitted from
:: ,~; - ~ - . .
~ the atmo~phere upward through inlet openings 82 in the
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bottom ends of the heat exchanger units 1 anc~. the
heated clean air îs discharged into a central duct
84 through outlet openings 86 at the top ends of
such heat exchanger units, as shown in Fig. 5. ~he
central duct 84 extends horizontally between the two
side ducts 78 and 80 acro~s the top ends of the heat
exchanger units and connect~ to a vert.ical duct 88.
The heated clean air is sucked through ducts 84 and 88
in the direction of arrows 89 by another air fan 90
connected between the bottom of duct 88 and clean air
discharge 92, which may be connected by suitable
ducting (not shown) back to the veneer dryer or to the
heating system of a building. ~his re~ults in a
considerable savings in heating costs since approx-
imately 70% of the heat in the exhaust air is
recovered by heat transfer in the heat exchangers to
the clean air.
In order to control the temperature of the
exhaust air emitted from the output of the heat
exchanger units 1, a temperature sensor 94 is located
at the output of the exhaust air collector auct 6~
and is electrically connected to a solenoid ~6 or :
other actuating means which controls the opening and
closing of a damper mechanism 98 provided in the path -
of the clean air, such as in the vertical duct 88. P~s
a result, the flow of clean air through the vertical
duct and the heat exchangers is automatically changed
to vary the amount of cooling of the exhaust air in
order to maintain the final temperature of the exhaust
air at the output of the heat exchangers at a
predetermined temperature of, for example, 150F.
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This is necessary, among other reasons, to maintain
the condensed pollutants in a liquid state so they
run down the surfaces of the heat exchanger passages
and duct 66 into the collection tank 72.
Typical temperatures of the exhaust air and
clean air before and after heat exchange are as
follows~ The exhaust air temperature is about 340F.
at inlet 74 and 150F. at the outlet of duct 66. The
clean air temperature is at an ambient level of, for
example, 70F. at inputs 82 and about 26nF. at
discharge 92 because of the heat exchange increase in
temperature of about 190F.
As a result of the drop in temperature of
the exhaust air from 340F. to 150F., substantial].y
all carbonaceous vapors and other gaseous pollutants
in the exhaust air are condensed onto the heat
exchanger passageways and very little pollutants are
; transmitted into the atmosphere through the exhaust
dischaxge 70 so that in many cases no further
pollution abatement equipment is necessary. Howaver,
a demister apparatus 100 is employed connected between
the output of the exhaust air collection duct 66 and
the exhaust fan 68. The demister apparatus is of
conventional type which contains a plurality of baffle~
for changing the direction of the air flow in order to : -
remove any partlcles of liquid or mist of condensed
water or pollutants from the exhaust air which are not
deposited on the surfaces of the heat exchanger or
?, ~
duct 66. The demister also drains into the aollection
tank 72.
The heat exchan~er passages through which the
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exhaust air is conducted downward in the direction
of arrow 7 may be cleaned by spraying clean liquîd
into such passageways through the pipe line 54 into
the sprayers 51, in a similar manner to that shown in
Figs. 1 and 2. ~hus, in~tead of spraying water for
condensing purposes as in Fig. 1, the sprayer apparatus
6 can be employed to spray cleaning liquid or steam for
removing condensation solids and other deposits from
the surface of the exhaust air passages.
It will be obvious to those having ordinary
skill in the art that many changes may be made in the
details of the above-described pxeferred embodiment
of the present invention without departing from the
spirit of the invention. For example, the exhaust gas
can flow upward in direction 4 while ambient air or
cold water flows downward in direction 7 in Fig. 5,
~; merely by moving side ducts 78 and 80 to the lower
ends of the heat exbhangers and providing the fluid
inlets 82 at the top ends of such exchangers. In
this case the duct 84 would discharge the exhaust air
and liquid drain means like 60 and 61 of Fig. 1 would
be provided in the lowered side ducts 78 and 80 to
remove the conden~ed pollutants, while duct 66 would
be used to discharge the heated ambient air or water.
, Therefore, the scope of the present invention should
only be determined by the following claims.
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