Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The present invention relates to a f~lme gas purification system which may be
used in conjunction with food cooking e~,uipment. The system may, in particular, be
used with cooking equipment wherein the cooking zone or area is completely enclosed in
a housing or cooking hood such as, for example, a self-contained fried food (dispensing)
S machine.
DESCRIPTION OF T~E PRIOR ~RT
10 Typically food items such as *ench fries, onion rings, chicken nuggets, -fish nuggets, and
the like are prepared by being heated or cooked in a hot cooking liquid (such as an oil
or fat). Since such food products have a high water content, the largest constituent of
the exhaust fume gas is water vapour or steam. However, the fume gas is typically a
complex blend or mixture of gases, vapours and/or particulates (the blend usually
~5 including air) which also contains a certain amount of particulate matter and/or gasified
oil/fat residues. The organic component of the exhaust fume gas may, for example,
include high temperature degradation products of the cooking oil and of any animal -fats
contained in the products themselves. It is therefore desirable to be able to remove
fume gas from the cooking area in order to avoid an undesirable accumulation of organic
20 matter such as grease etc. on the surfaces of various objects in the vicinity of the cooking
area, the accumulation of which could present a danger (e.g. of fire).
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Fume gas removal systems which ~Ise ~ans to transport fllme gas from a (interior)
cooking area to some more remote location are widely used in commercial and
residential bwildings. The simplest system expels fume gas (which includes air) from the
cooking area of a building into the atmosphere using a -fan. In most instances, however,
S a fan ;s used in association with a canopy exhaust hood and a filter; under the in:fluence
of the fan, the exhaust hood channels fume gas (which includes air) from the cooking
area to the filter which removes (condensed) particulates (of grease and the like) before
the fume gas combination is subsequently expulsed. However, such filters get rapidly
clogged up with grease material with the resulting loss of filtering efficiency.
Other more complex systems are also known. U.S. patent no. ~,900,341 to Csabai, for
example, relates to a purification system for scrubbing exhaust fume gas generated dwring
cooking. The system as taught in this patent generally comprises
a) a container comprising
a (lower) inlet,
an (upper~ ou-tlet, and
a fixed packed bed (comprising a plurality of stationary filter elements)
disposed between the inlet and the outlet,
b) cooling means;
c) wetting means to wet said filter elements;
d) means for co]lecting liquid, contaminant particles and condensates, etc.;
and
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e) a blower to indwce a negative pressure in said outlet.
In accordance with the teachings of this reference, exhaust fume gas is passed through a
chilled mass of wetted filter elements (e.g. glass balls or marbles) such that:
S a) water vapour is condensed;
b) the wet surfaces of the filter elements captures solicl particulate
matter impinging thereon; and
c) vaporized organic material such as fat or oil also
condenses out the fume gas.
However, it is to be particularly noted that U.S. patent no. 4,900,341 teaches or points to
a system wherein:
a) the container has an inlet which is operatively connected to the lower
portion of the container and an outlet which is operatively connected to the
lS upper portion of the container;
b) the fixed packed bed is disposed above, and is spaced apart from, the inlet
which is associated with the lower portion of the container,
d) the means for cooling the exhaust fume gas (e.g. to induce the
condensation of a sondensable component of the exhaust fume gas)
includes a cooling coil which surrounds the outside surface of the container
itself;
e) the wetting means includes means for recirculat;ng a wetting liquid medium
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from the lower portion for redistribwtion over the filter elements; and
f) it is taught to direct about 2/3 of the recirculated liquid medium through
the filter elernents and 1/3 against the chilled, vertical inside wall of the
container such that a uniform capillary coating on the filter elements may
be attained for scrubbing while the portion of the liquid me~tium flowing
down on the walls, is chilled so as to absorb heat from the (hot) exhawst
fume gas.
The net result of the above is that for the system as taught in U.S. patent 4,900,341, the
exhaust fume gas and the contaminant collecting liquid medium flow in counter current
fashion relative to each other; additionally, heat is drawn from the system along the side
walls of the container while relatively hot f~lmes may pass up through the filter elements
starting from below the filter elements. Therefore exhaust fume gas which percolates
upwards through the center of the filter elements can contact liquid medi~lm which is
relatively warm as compared to the liquid medium adjacent the cooled side wall of the
container or which is initially introduced at the top of the filter elements. This can
encourage a relatively gradual cooling of the exhaust fume gas such that ~ny condensable
component(s) of the exhaust fume gas may have sufficient time to coalesce around the
outer surface of the filter elements and form hard to remove films thereabout. This can
lead to clogging and require that countermeasures be taken such as the introduction of a
2~ detergent or the like into the recirculation circuit to facilitate removal of such coatings.
However, the addition of a detergent or the like can itself lead to undesirable side
effects such as foaming which in turn must also be dealt with by additional measures
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such as the addition of antifoaming agents. The use of detergents etc. may thus
increases the complexity of the cleaning liquicl and require constant vigilance on the part
of an operator such that these additives are not carried by recycled air back to the
cooking area so as to conta[ninate the cooking area.
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It would be advantageous to have a scrubber system of the type described in U.S.
patent no 4,900,341 but which may avoid the above mentioned disadvantages.
It would also be advantageous to have an effective scrubber system which is
10 efficient, economical, easily installed and has low operation and maintenance costs.
It would in particular be advantageous to have a fume purification system which
could effectively be used in a fried food dispens;ng machine.
SUMMARY OF I~IE INVENTION
Surprisingly, in accordance with the present invention, it has been observed that by first
passing the exhaust fume gas through a quench zone followed by passage through a zone
20 comprising a packed bed such as disclosed in U.S. patent 4,900,341, a condensate layer
does not tend as readily to build up over the -filter elements and that the spaces between
the filter elements have less tendency to become obstructed. The separated fume
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contarn;nants may thereafter be removed from the following s~lmp zone in any (known)
manner such as described, for example, in U.S. patent 4,900,3~1 referred to above. The
present invention thus exploits a three zone system, namely a system having an upper
quench zone, an intermediate fixed bed zone and a lower sump zone (as shall be
S described herein).
In accordance with the present invention, the word "quench" is to be understoocl as being
a characterization (relative to fume gas) indicative of a temperature drop and/or an
entrainment of (solid) particles, as effectecl by liquid particles of a spray of liq~
mediual. Thus, for example, in accordance with the present invention any reference to
expressions such as "quench zone", "quench ef~ect" or the like are to be understood as
being a reference to a zone, effect, etc., wherein the temperature of the fume gas may
be lowered and/or (solid) particles thereof may be entrained (e.g. taken up, captured,
entrapped, etc.) by liquid particles of a (quench) spray of liquid medium.
The present invention, in a general aspect, provides a purification system for scrubbing
exhaust fume gas fr~m a cooking area, said system having,
a container having gas inlet means for the intake of said exhaust f~lme gas and gas
outlet means for the discharge of scrubbed exhaust fume gas therefrom,
said container having a flow path defined therein for communicating said
inlet means with said outlet means, said flow path including a fixed bed
zone and a lower sump zone, said fixed bed zone comprising a plurality of
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filter elements, said lower sump zone being disposed below said fixecl bed
zone,
wetting means for wetting said filter elements with a liquid medium,
said lower sump zone being configured to collect liquid medium leaving
S said fixed bed zone, said wetting means having a recirculation circuit
comprising recycle means for recycling liquid med;um from said sump zone
to said filter elements for wetting said filter elements,
cooling means for cooling said liquid medium,
overflow means ~or draining liquid medium from said sump zone so as to limit thelevel of liquid medium in said lower sump zone, and
blower means for inducing negative pressure at said gas outlet means,
said system being characterized in that :
said flow path includes
an upper quench zone for contacting said exhaust fume gas with said liquid
medium prior to passage of exhaust fume gas through said fixed bed zone,
said gas inlet means is operatively connected to said upper quench zone,
said quench zone has quench spray means for providing a quench spray of said liquid
medium for contacting exhaust fume gas delivered to said quench zone from said gas
inlet means,
said recycle means comprises means for recycling liquid medium from said lower sump
zone to said quench spray means,
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said cooling means comprises means for cooling the liquid medium prior to delivery
thereof to said qwench spray means, and
said gas outlet means has outlet aperture means communicating with the lower sump
zone, said outlet apertwre means being disposed so as to be above the level of the liquid
S medium as defined by the overflow means.
As indicated above, in accordance with the present inYention, it has been observed that it
is advantageous to initiate the scrubbing of exhaust fume gas by first passing the exhaust
fume gas through a quench zone. In the quench zone, the fume gas may be brought into
10 contact and intermingle with a liquid medium spray (e.g. of finely divided liquid particles,
a liquid mist or the like). By means of such contact, for example, any hot exhaust gas
rmay be relatively rapidly (or suddenly) cooled. It is believed, that the condensation, in
this way, of any condensable component of the fume gas, produces more or less (solid)
contaminant particles of relatively small size as compared to the spacing between the
15 filter elements and which have less tendency to coalesce and stick to the surface of the
filter elements~
In accordance with the present invention, the tempcrature of the liquid medium used to
quench the fume gas, the flow rate of the recycled liquid medium, the spray pattern
20 produced by a quench spray head(s) (or nozzle(s)), the disposition of the exhaust fume
gas inlet with respect to the quench spray pattern, etc., are selected, (in light of the
temperature of the incoming exhaust fume gas, the flow rate of the incoming fume gas,
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the particle content of the incoming exhaust fwme gas, etc.) with a view to bring the
fume gas stream and the liquid rnedium into collision above the fixed bed zone, for the
formation and/or capture of fume parLicles into drop(let)s of liquid mec~ium, which after
passing through the fixed bed, may be collected from the sump zone.
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As mentioned, the quench zone has quench spray means for providing a quench spray of
the liquid medium for contacting exhaust fume gas which is delivered to the quench zone
-from the gas inlet means. The quench spray means may take any form whatsoever for
this purpose. The spray mealls may, Eor example, compr;se one or more quench spray
10 heads or nozzles for developing a quench spray. The quench spray prodwced by the
quench spray means may take on any spray pattern configuration and may be oriented in
any direction or fashion in the quench zone provided that the spray produced is such that
fume gas and liquid medium (particles) come into collision above the fixed bed zone, i.e.
the desired "quench effect" is obtained thereby. If more than one spray head is involved
15 all of the spray heads may each produce a spray oriented in a common direction; they
may each produce a spray oriented in a different direction; or groups of spray heads may
provide a spray orientation different from other group~s) of spray heads; etc...
The quench spray means may, for example, provide a spray pattern of conical
20 configuration; a conical configuration may comprise one or more conical elements
(provided by one or more spray heads) which may each, if desired, be directed towards
the fixed bed zone. The quench spray means may, for example, comprise a quench spray
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head which develops a conical spray pattern clirected towards the f;xecl bed zone. It is to
be understood that a reference to a spray pattern~ as being directed towards the fixed
bed zone, is a reference to a spray pattern wherein liquid medium is initially sprayed in
the (general) direction of the fixed bed zone rather than, for example, (generally)
S sideways towards the container wall or (generally) upwards away from the rixecl bed
(although these latter orientations may also be possible).
In accordance with the present invention the cooling means may take any desired
configwration. The cooling means, for example, may, if clesired, comprise a refrigeration
10 member (e.g. cooling coil) which surrounds (at least the outside surface of the walls o~)
the container adjacent the lower sump æone ~the container/coil combination may have a
configuration analogous to that described in the U.S. patent ~,900,342 rnentioned above);
in this case the liquid medium is chilled in the lower sump zone prior to entering the
recirculation circuit.
However, in accordance with a preferred aspect of the present invention, the
recirculation circuit itself may include cooling means for cooling the liquid medium prior
to delivery thereof to the quenching spray means. Thus, in accordance with the present
invention, the recirculation circuit may, for example, have cooling means comprising a
20 tubing member for the conveyance of liquid medium through the interior thereof and a
refrigeration member disposed for the extraction of heat from liquid medium passing
through the tubing member, the refrigeration member being operatively connected to a
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re~rigerator system for the extraction of heat from liquid medium passing through said
tubing member.
The tubing member and the refrigeration member may, for example, form an integral
S unit wherein the refrigeration member forms part of the tubular wall of the tube
member; the refrigeration member may, for example, have the conriguration of a coil
member having an inlet and outlet for a cooling medium used to extract heat from the
liquid medium. Alternatively, the tubing member and the refrigeration member may be
separate elements; in this case, the refrigeration member may be a refrigeration (e.g.
10 coil) member which may, if desired, be disposed within the tube member (so as to be
directly ;n the path of the liquid medium) or it may be disposed about the exterior of the
tubing member. If the refrigeration (e.g. coil) member is disposed within the tubing
member, any inlet and outlet means thereof will of course have to pass through the wall
of the tubing member for comlection to a refrigeration system; if the refrigeration (e.g.
15 coil) member is disposed about the exterior of the tubing member it will be in heat
transfer contact with the tubing member in some suitable fashion (e.g. simple contact,
welded contact, etc.).
It has been observed that, by placing cooling means in the recirculation circuit, a lower
20 liquid medium temperature (during continuous use) may be more readily obtained and
maintained, than as was observed for a system such as shown in U.S. patent no.
4,~00,341. ~ccordingly, this preferred configuration may provide for a relatively low
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temperatLlre liquid mediwm for delivery to the quench zone, the temperature of the
liquid medium being relatively more readily controllable by extracting heat from the
liquid medium as it passes through the recirculation circuit. The refrigeration system,
which may be connected to the refrigeration mermber, may be manipulated as desired in
S any (known) manner. By way of example, the temperature of the liquid medium in the
lower sump zone may, if desired, be maintained in the temperature range of from about
SQ to about lOQ C.
The refrigeration system may take any (known) form provided that it ef-fects the desirecl
10 heat extraction. The refrigeration system rnay, for example, comprise a cooling system
wherein cooling liquid (e.g. relatively cool water) is circulated through the refrigeration
member. Alternatively, the refrigeration member may be connected to or form part of a
(known) compressor/evaporator/condenser refrigeration system or arrangement.
15 In accordance with the present invention, the gas outlet means may include (cover)
means for inhibiting liquid medium from falling or passing into the outlet means. More
particularly, the gas outlet means may have a head portion configured to so inhibit the
liquid medium; the end of the gas outlet means may, for example, be U-shaped and be
disposed upside down so that the end of one arm of the U defines the gas outlet
20 aperture which communicates with the lower sump zone and the other arm of the U
communicates with the rest of the outlet means.
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Alternatively, the outlet means may comprise a head portion and a main portion, the
lhead portion defining a channel ~or changing the direction o~ flow of the scrubbed fume
gas upwards before the scrubbed fume gas is discharged, the channel having an upper
end and a lower end, the upper end communicating with a discharge channel defined by
S the main portion, and the lower end comprising the outlet aperture means.
The head portion may, for example, comprise an outer tubular member open at one end
and closed off at the other end; the main portion may also comprise a tube member; an
end element of the tube member (hereinafter referred to as the inner tube element) may
10 be sized so as be disposed within the outer tubular member such that a portion thereof
extends out of the open end of the outer tubular member and the open end of the inner
tube element within the outer tubular member is adjacent to but spaced apart frorn the
closed end of the ou-ter tubular member. The outer tubular member and the inner tube
member can be spaced apart such that they define an annular channel therebetween; the
15 open end of the inner tube member which is adjacent the closed end of the outer tubular
member may communicate with the upper end of the annular channel. The lower end
of the annular channel can in this way define an annular aperture communicating with
the lower sump zone. I~he inner element may be spaced apart from the outer tubular
member in any suitable fashion such as by spacer elements, etc..
The filter elements may take any suitable (known) form; e.g. spherical (glass) balls such
as glass marbles. Other types of filter elements may include known packing elements
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such as raschig rings, berl saddles, etc.
In accordance with the present invention, the blower means may be operatively
connected to the gas outlet means by a charcoal filter cartridge and the blower means
5 may communicate with the atmosphere for the discharge of scrwbbed fume gas to the
atmosphere.
The purification system o~ the present invention may particularly be wsed in conjunction
with a self-containecl fried food dispensing machine wherein fume gas generatecl d~lring
10 cooking of food products in a hot cooking oil bath are collected (from a hood enclosing
the cooking area), cooled and purified with the scrubbed fume gas being vented to the
atmosphere instead of being rec;rculated to the hood; in this way a negative pressure
may be maintained in the hood.
lDES~RIPTION OF THE DRAWINGS
An example embodiment of the invention is illustrated in the drawings wherein:
Figure 1 is a schematic side view of the prior art system taught in U.S. patent no.
4,~)0,341 partially Cllt away to expose interior features thereof;
Figure 2 is a schematic side view of an example embodiment of a system in
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accordance with tlle present invention partially cut away to expose interior
features thereof;
Figure 3 is a top view of the spray pattern produced by the quench spray head
shown in figure 2, and
Figure 4 is a partially cut away detail perspective view of the outlet means shown in
figure 2.
10 The prior art system of U.S. patent ~,900341 ( as illustrated in f;gure 1) and the example
system of the present invention (as illustrated in figLlre 2) will both be described
hereinafter in order to illustrate the differences between the present invention and the
teachings of the ~J.S. patent. Both systems will be described in relation to exhaust fume
gas produced during the frying of a food product in a hot coo~cing oil or fat; the exhaust
15 fume gas being confined in a hood which is mounted right over and fully encloses the
frying area (not shown). An exhaust port is located on one side of the hood where the
fume gas is concentrated. Exhaust fume gas is sucked from the exhaust port into a
condenser unit where most of the fume gas purification and conditioning takes place.
20 Referring to figure 1, the prior art system shown, has a container which is configured as
a cylindrical double walled container; the outer wall 1 is spaced apart from the inner
wall 2. The inner wall 2 defines the interior boundaries of the container. A (copper)
tube (refrigeration) cooling coil 3 is disposed between the outer wall 1 and the inner wall
2; the coil 3 extends -from the bottom of the inner wall to a point adjacent the top
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thereof. The coil 3 is helically wo~lnd aroLlnd the cylindrical inner wall 2 and is in heat
transfer contact with the outer surface of the inner wall 2 (e.~. the wall 2 ancl coil 3 are
made of heat conducting material and the coil 3 rnay be welded to the surface of the
wall 2). To provide cooling, the coil 3 may ~e part of a refrigeration system (not shown)
5 which can comprise a suitable (known) compressor/evaporator/condenser refrigeration
arrangement; the co;l 3 being configured to extract heat from the interior of the
container through the wall 2.
The container has an upper gas outlet 4 which communicates with the interior o-f the
10 container through a removable do~lble walled access cover 5; the portion of the inlet 4
defining the inlet aperture thus communicates with the upper portion of the interior of
container. The container also has a lower inlet the aperture of which ;s designated by
the reference number 6; as may be seen the inlet extends through the double wall of the
base of the container sufficiently such that the inlet aperture 6 is above the level 7 of the
15 liquid medium ~ (e.g. an aqueous medium such as water or a water solution) in the
lower portion of the container.
The container has an upper portion as indicated by the reference number 9 and a lower
portion as indicated by the reference number 10. The upper portion 9 corresponds to a
20 fixed bed zone whereas the lower portion 10 corresponds to a lower sump zone; these
zones are both in the flow path whereby the inlet 4 is in fluid (i.e. gas) communication
with the outlet 6.
The fixed bed zone comprises a bed 11 of filter elements which consist of solid glass
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balls (e.g. marbles). The bed 11 extends laterally cornpletely across the interior of the
container. The balls are packed and s~lpported on a circular wire mesh 12. The mesh
12 is -fixed relative to the inner surface of the wall 2 by being supported on brackets
which are fixed (e.g. welded) to the wall 2. The rmesh 12 has openings large enough to
5 allow liquid medium, gas, etc. to pass through but still support the bed 11 thereabove.
The bed 11 extends upwardly to a point adjacent the cover S; as seen, a layer 13 of the
balls at the top of bed 11 covers a spray head 14 which shall be re~erred to again below.
The lower sLImp zone contains the liquid -medium 8, the level 7 of which is determinecl
10 by the "T" shaped overflow LS. The overflow 15 has a wide mouth; the opening of the
mouth is flush with the level of liqllid medium 8 which it is desired to be maintained in
the lower sump zone. The overflow 15 is necessary because the water content of the
liquid medium is continuously augmented by condensation water from the exhaust fume
gas. The overflow also allows for drainage of any (layer of) fat/oil scrubbed from the
15 fume gas. Excess liquid medium is drained off into the tank 16 via piping and a check
valve 17; the check valve 17 is present to prevent air from entering the lower sump zone
through the overflow 15 since during operation the container is under negative pressure.
The liquid medium 8 in the sump zone can be recirculated continuously by a
20 recirculation circuit which cs~mprises recycle means comprising a pllmp 18 and two
conduits members 19 and 20. The conduit member 19 has an inlet 21 at the base of the
lower sump zone; from inlet 21 liquid medium can pass through the pump 18 to conduit
20. Conduit 20 can convey the liquid medium to the spray head 14 from which the
liquid medium may be distributed over the filter elements (i.e. balls) so as to cascade
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downwardly through the filter elements wetting them and event-lally leaving the fixed
bed zone and falling back into the lower sump zone as inclicated generally by the
reference number 22.
5 Plate 23 and cap 24 are respectively disposed over the inlet aperture 6 and the opening
of the overflow 15 to prevent drops of the cascading liquid medium from entering into
the aperture 6 and the overflow opening. The circular plate 23 is rno~lnted on the mesh
12 such that it also deflects the incoming gas stream form inlet aperture 6 laterally for
distribution at the bottom of the marble packing.
A blower 25 is operatively connected to the outlet 4 to induce a negative pressure at the
inlet aperture 6 while sucking treated fume gas out of outlet 4. When the blower 25 and
the pump 18 are activated, the exhaust fume gas entering the container by inlet aperture
6 percolates upwardly through the bed 11 in the direction of the arrow 26 as liquid
15 medium flows downwardly in the opposite direction for return to the lower sump zone.
To complete the purification the blower 25 pushes the treated f~lme gas through a
charcoal filter cartridge 28 before being returned to the hood 29 at inlet port 30. The
charcoal cartridge 28 is intended to remove any remaining odour and gas constituents
20 before the scrubbed fume gas is directed into the hood 29; reference may be made to
U.S. patent 4,900,341 for a more detailed description of such cartridges. Known
cartridges such as those made by AMETEK, Wisconsin, U.S.A. may be llsed for this
purpose.
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Referring now to fig~lre 2, the illLIstratecl system (which is an example embodiment of a
purification system in accordance with the present invention) has a container which is
configured as a cylindrical single wall conta;ner 31.
5 The container 31 has an upper gas inlet 32 which commwnicates with the upper portion
of the interior of container 31; the top of the container to which the inlet 32is attached
may comprise a removable top to provide access to the interior of the container 31. The
container 31 also has a lower outlet which has a head portion 33 and a main portion 34.
The container 31 has an upper portion as indicated by the re-ference n~lmber 35, an
intermediate portion designated by the reference number 36 and a lower portion as
indicated by the reference n~lmber 37. The upper portion 35 corresponds to a quench
zone, the intermediate portion 3~ corresponds to a fixed bed zone and the lower portion
15 37 corresponds to a lower sump zone; these three zones are all in the flow path whereby
the inlet 32is in fluid (i.e. gas) communication with the outlet.
The fixed bed zone of the system illustrated in -figure 2is essentially the same as the
fixed bed zone illustrated and described above with respect to figure 1. Accordingly,
20 only those features of the fixed bed zone of figure 2 which are diEferent from the fixed
bed zone shown in figure 1 will be referred to hereinafter. Thus, as can be seen from
figure 2, the top 38 of the fixed bed zone is spaced apart frorn the quench spray head 39.
Additionally the head portion 33 of the outlet extends Llp through the body of the
(marble) bed 40.
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The lower sllmp zone of the system shown in fi~lre 2 is the same as the lower swmp
zone illustrated and descr;bed with respect to figure 1. Accordingly the lower sump zone
of figure 2 will not be described in detail hereinafter. Thus, the lower sump zone of
figure 2 is shown as containing a liquid medium 41, the level 42 of which is determined
5 by the "T" shaped overflow 43. The overflow 43 drains l;quid medium to a tank 44 in
the same manner as previously described with respect to fig~lre 1.
The quench zone has a quench spray head 31 disposed therein. The spray head 31 ;s
shown as producing a spray of liquid medium which is directed towards the fixed bed
10 zone. The quench spray extends laterally more or less completely across the top 38 of
the fLxed bed zone. In this embodiment therefore the fume gas passing into the quench
zone from the inlet 32 may face a spray pattern as shown in figure 3 if a spray head of
the type HHSJ (from Spraying Systems Co. Pensylvania, U.S.A.) is used. I~he spray
pattern (designated by the reference number 45) is shown in figure 2 as having an
15 essentially conical form when viewed from the side but when viewed from the top as in
figure 3 the spray also has a spiral like pattern (designated by the reference number 46);
i.e. the three dimensional spray pattern is of a spiralling cone the apex of which is at the
quench spray head 31. ~ different quench spray head may of course be usecl to produce
other types of spray patterns and need not necessarily produce a spray covering the
20 entire top 38 of the fixed bed zone provided of course that the desired "qllench effect" is
obtained.
The liquid medium in the sump zone of the system shown in figure 2 can be recirculated
continuously by a recirculation circuit which comprises a pump 47 and two conduits
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members 48 and 49. The condllit member 47 has an inlet 50 at the base of the lower
s~lmp zone; from inlet 50, liquid medium can pass through the condu;t ~8 and the pump
47 to conduit 49. Conduit member 49 can convey the liquid medium to the quench spray
head 31 from which the liquid medium may be sprayed to be browght into contact with
S the exhaust fume gas before both pass on through the fixed bed ~one. After passing
through the fixed bed zone the fume gas (as well as liquid medium) proceed to the lower
sump zone. Passage of fume gas ancl liquid medium through the three zones generally
proceeds in the result in occurrent-like fashion. The liquid medium distribllted over the
filter elements thus cascades downwardly through the ~ilter elements (e.g. marbles)
10 wetting them and eventually leaving the fixed bed zone and falling back into the lower
sump zone as indicated generally by the reference number 51. ~he fume gas in the
lower sump zone as designated by the reference number 52 proceeds to the head portion
33 of the outlet for discharge as shall be explained hereinafter.
15 A portion of the conduit 49 thereof has a heat conducting cooling coil tube member 53
disposed thereabout in heat transfer contact. The coil 53 is helically wound around the
portion of the conduit member 49. To provide cooling, the coil 53 may be part of a
refrigeration system (not shown) which can have a known
compressor/evaporator/condenser refrigeration arrangement; the coil 53 being
20 configured to extract heat from the liquid medillm passing through the portion of the
conduit member 49 in heat transfer contact with the coil 53. This portion of the conduit
member may for example comprise a coil section such as a Doucette coaxial coil
available from Doucette Industries Inc., Pennsylvania USA.
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The system may be associated with any suitable (known~ control means for measuring
temperature and flow rates, etc.
A cap 54 is disposed over the opening of the overflow 43 to prevent drops of the
S cascading liquid medium from entering into the overflow opening
As mentioned above, the head portion 33 of the outlet extends up through the body of
the (marble) bed 40. Referring to figures 2 and 4, the head portion 33 comprises an
outer tubular member 55 open at one encl and closed off at the other end. The main
10 portion 34 compr;se a tube end member 56. The end member 56 is dispose~ within the
outer tubular member 55 such that a portion thereof extends out of the open end of the
owter tubular member 55. The opening 57 of the tube end member 56 is adjacent to but
spaced apart from the closed end of the outer tubular member 55. The outer tubular
member 55 and the tube end member 56 are spaced apart such that they define an
15 annular channel 58 therebetween. The opening 57 the tube end member 56
communicates with the upper end of the annular channel. The lower end of the annular
channel 58 defines an annular aperture 59 which communicates with the lower sump
zone. As may be seen the annular aperture 59 communicates with the lower sump zone
and is disposed such that it is above the level 42 of -the liquid medium 41 (e.g. an
20 aqueous medium such as water or a water solution) in the lower portion of the
container. The end tube member 56 may be spaced apart from and fixed to the outer
tubular member 55 in any suitable fashion such as by spacer elements, etc.(not shown).
However, the outer tubular member 56, relative to the end tube member 57, may simply
be fixed to and supported by the mesh supporting the (marble) bed 40 so that the end
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tube member 57 merely extends into the interior of the outer t~lbular member 56 witho~lt
direct contact therewith; in this latter case, the mesh can be fixed (e.g. welded) to the
ollter surface of the outer tubular member 55 adjacent to the annular apertLlre 59.
S A blower 60 is operatively connected to the outlet main portion 33 so as to be able when
active to induce a negative pressure at the inlet aperture 32 while sucking treated fume
gas out of outlet. When the blower 60, the pump 47 and the refrigeration system
attached to the coil 53 are activated the system rnay proceed as follows: liquid medium
passes wpwardly through the conduit 49 where it is chilled by the coil 53 before being
10 passed on to the quench spray head 39; exhaust gas from the hood 61 is sucked into the
inlet 62 on the hood 61 where it is then passed on to the inlet 32 for injection into the
quench ~one for contact with the liquid medium spray from the quench spray head 31;
the fume gas and liquicl medium then proceed through the fixed bed zone and into the
lower sump zone where they separate; the separated liquid medium is then recirculated
15 from the lower sump zone; the separated fume gas then passes through a charcoal filter
cartridge 63 (such as described above with respect to figure 1) and is thereafter
discharged from the blower 60 to the atmosphere.
The cooling means could, if desired, of course be disposed as part of conduit 48.
While a particular and preferred embodiment of the invention has been described, it is
to be understood that various changes of materials and arrangements of the various may
be made by those skilled in the art without departing from the spirit and scope of the
present invention.
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