Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROVND OF THE INVENTION
This invention relates to exhaust fume treatment apparatus
and, more particularly, relates to apparatus for removing materi-
als from an entraining exhaust gas utilizing a rotating wheel and
housing to effect such separation.
Although use in other environments is contemplated, the pre-
sent invention arose in connection with the development of exhaust
hood systems and integrated exhaust hood-air curtain systems usable
in a variety of situations in which fumes produced by a device are
to be exhausted from an enclosure in which the device is located
and in such a way as to protect personnel or the like adjacent -
~; such device from deleterious or unpleasant effects which might be
caused by such fumes. Cook tops or the like in food preparation
establishments including restaurants, hamburger stands, etc. pro-
vide one example of situations to which the present invention is
directed.
In such establishments, the air above such cooking apparatus
(for example, griddles, grills, open deep fat frying vats, kettles,
pressure cookers, etc.) may frequently carry objectionahle quan-
tities of fatty or greasy materials in suspension or entrainment.Thus, the present invention, in materially reducing or substanti- ~ ;
ally eliminating the level of foreign materials, such as grease
particles or the like, from air exhausted therethrough, is intend-
ed to improve environmental quality. While the embodiments dis-
closed in Canadian application Serial No. 193 216, filed February
22, 1974, by Willard K. Ahlrich and entitled "Exhaust Fume Treat-
ment Apparatus" achieve this end in a generally satisfactory man-
ner, the ernbodiments herein disclosed in detail further improves
the basic invention by enhancing contaminant removal performance
and providing additional operational advantages.
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According to the present invention there is provided
in an exhaust fume treatment apparatus for removing con-
taminant materials from the gas, the combination comprising:
a substantially cylindrical extractor housing with an inlet
and an outlet in opposite end walls thereof;
suction blower means coupled to said outlet for drawing
gas through said extractor housing;
a rotatable, substantially cup-shaped slinger wheel in said
: extractor housing and opening towards said inlet, the peripheral
portion of said slinger wheel comprising a circumferentially
spaced plurality of substantially axially extending, gas con-
tacting blade means responsive to gas flow therebetween toward
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said outlet for (1) massing thereon contaminant materials from
said gas, (2) migrating said masses toward said inlet, and (3)
substantially tangentially throwing said masses;
a substantially cylindrical screen spaced between said
slinger wheel and extractor housing periphery and having
openings angled outwardly and toward the extractor housing
inlet end for directing the thrown masses out of the gas flow
from said slinger wheel and with a component of motion toward
the extractor housing inlet end;
- 10 whereby to more uniformly axially distribute contaminant
masses collected in the zone between said screen and housing
peripheral wall despite net axial gas movement toward said
housing outlet.
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BRIEF DESCRIPTION OF THE DRAI~INGS
Figure 1 is a fragmentary, oblique view of an exhaust
fume treatment apparatus embodying the invention.
Figure 2 is an enlarged, fragmentary side view, substan-
tially in central cross section, of the apparatus of Figure 1.
Figure 3 is a sectional view substantially taken on the
line III-III of Figure 2.
Figure 4 is a sectional view substantially taken on the
line IV-IV of Figure 2.
Figure 5 is an enlarged fragmentary cross sectional view
substantially as taken on the line V-V of Figure 2 and lies
below Figure 1.
Figure 6 is an enlarged fragmentary cross sectional view
substantially as taken on the line VI-VI of Figure 2 and lies
below Figure 1.
Figure 7 is an enlarged cross sectional view substantially
taken on the line VII-VII of Figure 4 and lies below Figure 1.
. Figure 8 is an enlarged fragmentary cross sectional view
substantially taken on the llne VIII-VIII of Figure 4 and lies
below Figure 1.
: Figure 9 is an enlarged central cross sectional view sub- `
stantially taken on a line IX-IX of Figure 3.
.' Figure 10 is a side view of a modified slinger wheel con-
struction, useable in place of that shown in Figure 2.
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Figure 11 is an enlarged, fragmentary sectional view taken
on the line XI-XI of Figure 11.
Figure 12 is a side view of a blade of the modified slinger
wheel of Figure 10.
Certain terminology will be used in the following description
for convenience in reference only and will not be limiting. The
words "up", "down", "right" and "left" will designate directions
in the drawing to which reference is made. The words "front"
and "rear" will refer to the direction of gas flow through the
apparatus, forwardly being the normal flow direction. The words
"in" and "out" will refer to directions toward and away from,
respectively, the geometric center of the device and designated
parts thereof. Such terminology will include derivatives and
words of similar import.
DETAILED DESCRIPTION
Turning to the accompanying drawings, attention is first
directed to components having a general, though not specific,
correspondence to application Serial No. 193 216.
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Thus~ Figure 2 herein discloses an extractor 34 having an
inlet 37 for contaminant-bearing gases, and an exhaust blower
35 having an outlet 40 and driven by a motor 44 in a manner
hereafter discussed. The exhaust blower 35 is preferably a
conventional single inlet centrifugal blower comprising a
housing 51, including end walls 52 and 53 and a spiral-shaped
peripheral wall 54. A bearing 64 is fixed with respect to wall
52. An inlet port 56 in the left end wall 53 is faced by an
adaptor ring assembly, preferably of welded construction,
including an inlet cone 59, cylindrical adaptor 61 and annular
plate 57, all fixed with respect to the side wall 53, as by bolts
not shown.
A conventional open ended centrifugal blower wheel 69 is
disposed in the blower housing 51. The wheeI 69 includes a
rightward end plate 71 having a hub 72 securable to a shaft
assembly hereafter discussed, an annular left end plate 73 and
axially extending blower blades 75 for, upon rotation in one
direction, moving gas rightwardly through the collar 59 and out -
.
the outlet 40.
:... 20 The extractor 34 includes a substantially cylindrical
housing 81 comprising end walls 83 and 82 having respective
coaxial inlet and outlet openings 87 and 86. The extractor in-
let 37 is defined by a cylindrical inlet collar 98 located
within opening 87 by an annular flange 101 secured to side wall
83, as by screws not shown.
An annular flange 91 is fixed, preferably welded, to the
edge of extractor outlet opening 86. A transverse web 95 extends
chordally across the annular flange 91 near the center thereof,
preferably being fixed thereto by welding, and fixedly supports
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a bearing 65.
A slinger wheel 106 is spaced within the extractor housing
81 and includes a rightward end plate 107 having a hub 108. The
end plate 107 is spaced axially between the bearing 65 and
inlet collar 98 and radially inward from housing peripheral wall
84. The annular left end plate 110 of slinger wheel 106 is
coaxially supported on rightward end plate 107 by preferably
identical, circumferentially spaced and axially extending blades
111, and is adjacent the inlet collar 98. The blades preferably
have end flanges 112 for connection to the plates 107 and 110,
as by rivets. The slinger wheel may include diagonal bracing ~ - `
rods 116 between the hub 108 and ones of the blades.
A collection trough 131, fixed as by welding to the bottom
of the extractor housing 81, extends along at least the major
length of housing 81. A preferably downwardly flanged waste
outlet opening 132 in the bottom of the extractor housing
peripheral wall communicates with trough 131. A conduit 136
couples bottom portion of the blower housing 51 with the trough
131. The trough 131 has an outlet conduit 138 terminated as
desired.
Turning now more specifically to the improvement disclosed
herein and wherein the present disclosure departs from that of
my referenced application above mentioned, attention is first
directed to Figures 1-2 herein.
The extractor housing 81 and blower housing 51, supported
by a suitable framework 201, are coupled by an elongate cylindri-
cal tunnel 203. The tunnel 203 preferably snugly sleeves over
the adaptor member 61 and axial flange 91 and is fixed thereto,
as by screws not shown, for defining an elongate flow passage
coupling the interiors of the housing 81 and 51 substantially in
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gas tight relation.
The framework 2Ql here includes a support 202 fixedly
locating the bearing 64 on the closed rightward end wall 52 of
the blower housing 51, coaxially of the blower wheel 69.
` While it is contemplated that the slinger wheel 106 may be
rotatably supported and driven independently of the blower wheel
- 69, by a separate motor located substantially in place of bearing
65 in Figure 2, the preferred embodiment employs a telescoped
shaft assembly 206 and common drive motor 44 for supporting and
driving the wheels 106 and 69.
The shaft assembly 206 (Figure 2) includes a hollow stub
shaft 2Q8 rotatably supported at its rightward end by bearing 64.
The stub shaft 208 extends leftwardly through an opening in
blower housing wall 52 and adjacent its leftward end fixedly
supports the hub 72 of blower wheel 69 for rotation therewith.
The shaft assembly 206 further includes an elongate inner
shaft 209 which extends coaxially through the hollow stub shaft
- 208 and is rotatably supported therein, as by conventional sleeve
bearings, not shown. The elongate shaft 209 extends leftwardly
from the stub shaft 208, through the tunnel 203 and partially
, .
into the extractor housing 81. The elongate shaft 209 fixedly
supports the slinger wheel hub 108 and extends through a major
portion of the length of the slinger wheel. The bearing 65
rotatably supports the leftward portion of the shaft 209 and
slinger wheel 106. The bearing 65 and shaft 209 also radially
support the leftward end of stub shaft 208. The shafts 208 and
209 are axially fixed, as by collars at the bearings 64 and 65.
As shown in Figure 2, the blower wheel 69 and slinger wheel
106 are independently driven, normally at different speeds by
a common motor 44 through separate drives 212 and 213. Advantages
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- include elimination of a costly second motor and the ability to
precisely and reliably preselect and control the speeds of such
wheels. The motor 44 here has oppositely extending shaft ends.
The drive 212 comprises dual pulleys 215 and 216 respectively
- fixed on stub shaft 208, between blower housing wall 52 and
bearing 64, and on the leftward shaft end of motor 44, and
coupled by conventional V-belts 217. The drive 213 comprises
single pulleys 218 and 219 respectively fixed to a rightward
extension 221 of elongate shaft 209 and the rightward shaft end
of motor 44 and coupled by a V-belt 222. The ratios of the drives
212 and 213 are preferably selected such that the slinger wheel
is driven at optimum blade tip speed and the blower wheel
provides optimum airflow velocity through the blades of the
slinger wheel, both for maximum efficiency. Thus, a small
diameter, higher speed blower wheel can be used with a relatively
large diameter, low speed slinger wheel, permitting an increase
in the number, and total area, of slinger wheel blades for
greater gas contact and contaminant extraction capacity, without
an undesired increase, beyond optimum, in slinger wheel blade tip
speed. Thus, as shown in Figure 2, the pulley ratios of drives
212 and 213 cause motor 44 to keep the slinger wheel shaft 209
at a lower speed than blower wheel shaft 208. The blower wheel
drive 212 is the more heavily loaded of the two drives and employs
dual belts 217, in contrast to the single belt 222 in slinger
wheel drive 213.
The extractor inlet 37 is normally coupled to a desired
source of contaminant laden gas to be cleaned, such as grease
laden air. As seen in Figure 1, an inlet duct 224, which for
example may be conventionally connected to a cook-top range hood,
`30 receives incoming air or gas indicated by the arrow L directed
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~65Z~3
thereinto and routes same through a cylindrical extension 225
snugly secured to inlet collar 98 (Figure 2).
The extractor 34 includes means for enhancing axial distri-
bution uniformity of extracted contaminants therein, and which
thereby contribute to greater extraction efficiency, in the sense
of greater percentage removal of contaminant materials from the
incoming gas. Attention is now directed to components of the
extractor 34 contributing to such increased distribution -
uniformity.
- 10 Thus, a multi-part gas deflector Z28 (Figures 2 and 4)
comprises axially spaced, preferably circular primary and
secondary plates 230 and 231. The plates, or discs, 230 and 231
are coaxial with shaft 203 within and spaced intermediate the
ends of the slinger wheel 106. The secondary plate 231 lies
approximately half-way between the axial ends of the slinger
wheel 106 and is preferably less than half the outside diameter
thereof. A coaxial hub 232 on the secondary plate 231 fixedly
~ locates the deflector 228 on the shaft 209.
; The annular primary plate 230 radially overlaps the periphery
of secondary plate 231. The periphery of annular plate 230
preferably extends to more than half the diameter of the slinger
wheel 106, but is spaced inboard of the slinger wheel blades 111.
The plate 230 is spaced upstream of secondary plate 231 and is
preferably in the upstream (left) half of the slinger wheel 106.
The inner periphery of the annular plate 230 is spaced outward
of shaft 209 by a gas passage 234 (Figure 4) to the face of
secondary plate 231. Blade-like tabs 236 at the inner periphery
of primary plate 230 extend upstream and in part an initial
rotation to the adjacent incoming gas flow. The tabs 236 are
preferably angled to the shaft axis and adjacent radii of primary
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plate 230, as shown in Figure 4, and tend also to impel adjacent
incoming gas through passage 234 and against secondary plate
231. In the preferred embodiment shown, circumferentially
spaced, radial cuts 237 (Figure 4~ in the inner peripheral portion
of plate 230 result in circumferentially adjacent, substantially
trapezoidal flaps 238, triangular leading edge portions of which
are bent to form the tabs 236. Axial members, such as spacer
bolts 239, extend upstream from secondary plate 231 and support
the primary plate 230 for rotation with the shaft 209.
; 10 The slinger wheel blades 111 (Figures 2, 5 and 6) may vary
in number. However, in one wheel, tests indicate improved -~
performancewith 32 blades, as compared with 16.
Each blade 111 is of substantially Z-shaped cross section
(Figure 5) having an axially extending central web 241 of sub- -
stantially rectangular shape. The central web 241 of the mounted
blade is angled, as at A, to a radius R of the slinger wheel,
such that its radially outer portion trails its radially inner
portion during normal rotation of the slinger wheel. Integral
inner and outer longitudinal edge flanges 243 and 244, respec-
tively, extend from the central web 241 and are oppositely
circumferentially angled from the web to respectively lag and
lead same during normal wheel rotation. A trailing trough 248
is thus formed by the central web 241 and inner flange 243.
The outer flange 244 and the adjacent portion of the central web
241 have trailing contaminant material accumulation surfaces 246.
The upstream (left in Figure 2) end portion of the outer flange
244 tapers, e.g. is cut away on a slope, at 247. Thus the radial
width of the outer flange 244, at the upstream extremity thereof
goes substantially to zero. The longitudinal extent of the
tapered portion 247 is preferably between about 1/8 and 1/4 of
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the blade length. In addition, the blade 111 is twisted (see
Figure 6) about its longitudinal axis and throughout its length,
such that the tapered, upstream end portion 247 of the outer
flange 244 trails the downstream end thereof during normal
slinger wheel rotation.
A cylindrical screen 251 coaxially extends substantially the
length of the extractor housing 81. The screen 251 is spaced
closely radially inboard from the housing peripheral wall 84
and substantially further radially outboard of the slinger wheel
106. The screen 251 is fixedly located, preferably by spaced
bolt-spacer assemblies 252 (Figure 5), though a screen of
; sufficient stiffness tending to resume a flat condition may
sufficiently rigidly locate itself in the housing merely with
backing spacers on the peripheral wall 84.
The screen 251 comprises a portion of a commercially avail-
able expanded metal sheet, in which the open area, defined by
the openings 254 (Figure 7) substantially exceeds the closed area,
defined by the integral, narrow, elongated segments 256 of the
sheet. The openings 254 through the expanded metal sheet 251 are
inclined. The openings have parallel axes 257 (Figure 8) inclined
to perpendiculars P of the plane of the sheet 251. Restated, the
segments 256 bounding the openings 254 all have faces with
parallel inclinations or inclination components 259 which define
the inclination of the bounded openings 254 with respect to the
plane of sheet 251.
It is important, in the present invention, that the expanded
metal sheet 251 be oriented with its inclined openings 254
angled in the proper one of the several possible directions.
Thus, according to the present invention, the screen 251 is so
oriented within the extractor housing (Figure 2) such that the
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outwardly extending axes 257 of the openings 254 are angled axially
toward the inlet (leftward) end of the extractor housing. The
openings 254 thus tend to channel contaminant particles, thrown
from the slinger wheel 106, toward the inlet end of the
extractor housing 81.
Within the flow passage 204 defined by tunnel 203 (Figures
2 and 3), a plurality, here four, of symmetrically and substantially
evenly circumferentially spaced struts 261 extend convergently
upstream toward the bearing 65. The downstream ends of the
struts 261 are anchored to a preferably planar ring 263 concen-
tric with and fixed, as by bolts, to the upstream face of blower
: inlet cone 59 adjacent the wall of tunnel 203. The upstream
ends of the struts 261 are fixed to the bearing supporting web
95. The struts 261 eliminate axial vibration in bearing 65 and
in shaft 209 and enable mounting of the bearing 65 axially close
to the slinger wheel 106 to provide adequate rotational support
therefor.
A further deflector 267 (Figures 2, 3 and 9) includes a hub
268 fixed to the shaft 209, by any conventional means, for
rotation therewith. While it is contemplated that the deflector
267 may be a flat disc, it is preferably formed as a shallow cone
convergent toward its upstream end and having a narrow radial
edge flange 269 as shown. The deflector 267 is about one-half
the diameter of the tunnel 203 and lies axially close to the
ring 263. A reduced flow cross section zone 271 is thus defined
between the deflector 267 and the tunnel periphery and ring,
whereby to subject passing gas flow to several reversals in
radial direction, with accompanying decelerations. A contaminant
exit conduit 273 couples the bottom of an annular low gas
velocity space 274, at the "corner" formed by ring 263 and the
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: adjacent periphery: of tunnel 203 with the drain conduit 136.
The contaminant drain portion of the apparatus, including
trough 131 and conduits 136 and 273, is preferably covered with
any conventional insulative material, as schematically indicated
at 276 (Figure 2). This is particularly useful where the in-
coming gas-contaminant mixture has an elevated temperature and
extracted contaminants tend to solidify when cooled toward
- ambient temperature. The drain structure, including trough 131,
- conduits 136 and 273 and outlet 138, is somewhat remote from
the gas flow through the apparatus and such contaminant materials
may tend to cool and become less flowable therein. In such
instance, the insulation 276 reduces heat loss from the drain
system, keeping contaminants therein flowable. Under more extreme
conditions a heating means, such as electrical heating coils 277,
energized by a conventional source not shown, may be placed
against the surfaces of the drain system 131, 138, 136 and 273,
within the insulation 276.
The apparatus of Figures 1-9 is normally substantially self-
cleaning in use, wherein at least the great majority of extracted
contaminant materials exit through the drain outlet 138. How-
ever, it is contemplated that in some instances, as with
especially sticky or adhesive contaminant materials, occasional
cleaning may be desired. To this end, a wash pipe 280 (Figures
2-4) extends through the upper portion of extractor inlet 37,
offsets upwardly along entry wall 83, extends downstream
immediately inboard of the screen 251, downwardly along the down-
stream extractor end wall 82, downstream within the upper portion
of the tunnel 203, through openings in the ring 263 and cone 59,
and terminates in the upper portion of blower housing 51.
Plural spray nozzles 281, preferably laterally directed, are
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spaced along the length of the pipe 280. A conventional and ex-
ternally located source S is actuable to supply a solvent or wash
liquid solution under pressure to the pipe 280 and the resulting
spray from the nozzIes 281 cleans the interior surfaces of hous-
ings 81 and 51, tunnel 203, and components therein, of adhering
contaminant materials, which flush out through the drain system
outlet 138. Such cleaning means, when supplied, will normally be
used only periodically, preferably when the apparatus is not in
the process of extracting contaminants from an incoming contam-
inant-laden gas.
While the present invention is not limited to particular di-
mensions, the following tabulation indicates, for the sake of ex-
ample, approximate dimensions employed in one unit built in accord
with the present invention.
Extractor housing 81: 38" O.D. x 23" long
Slinger Wheel 106 : 30" O,D. x 15" long
spacing to wall 82 approx. 5"
- Blade 111 : approx. 2 3/4" wide
axial twist from end to end of
5 to 10
Deflector 228 : Plate spacing approx. 2 1/4"
Plate 230: 18" O.D. x 7" I.D.
Plate 231: 12" I.D. with spac-
ing to end plate 107 of about 8"
Screen 251 : spacing to wall 84 approx. 3/4"
Tunnel 203 : 26" dia. x 22" long
Deflector 267 : 12" O.D. x 1 1/2 long
Blower housing 51 : Shaft axis to scroll bottom 21"
Shaft axis to scroll top 16"
Shaft axis to top of outlet
18 1/4"
length 9 1/2"
Blower Wheel 69 : 24" O.D. x 7" long
OPER~TION
While the operation of the Figure 1-9 embodiment is generally
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indicated above, and certain basic operational concepts are
detailed in application Serial No. 193 216, the operation of : -
the Figuresl-9 embodiment herein is summarized, for convenience, ~.
:~ below.
With the extractor inlet 37 coupled to a source of contami-
nant-laden gas, e.g. a cook-top hood, as through inlet extension
: 225 and duct 224, and the drain conduit 138 terminated as
desired, operation is initiated by energizing motor 44 (Figure 2)
.~: to rotate shafts 208 and 209 at respective speeds determined by
the ratiosof drives 212 and 213. The rotating blower wheel 69
- draws gas from extractor inlet 37 radially outwardly through the- bladed portion of slinger wheeI 106 and tunnel 203, and expells ~:~
the cleaned gas through blower outlet 40. The solid line arrows ~- -
L (Figure 2) and solid line arrows C generally indicate gas flow to
and from, respectively, the slinger wheel blades 111. The broken -
line arrows G generally indicate the migration of portions of
accumulated contaminant masses along the blades, the movement ofcontaminant masses tangentially thrown from the blade and the
movement of contaminant masses through the screen 251.
I have found that, absent the deflector 228, gas flow
through the slinger wheeI 106 tends to disproportionately
concentrate at the downstream (rightward in Figure 2) ends of
the blades 111 and that a disproportionately large part of the
contaminant material collected on the blades 111 is at such
downstream ends thereof. Such results in reduced extraction
efficiency (in terms of percent of contaminants extracted from
the contaminated gas flow). Particularly, it is believed that,
. under such condition, contaminants approach the downstream blade
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ends at excessive concentrations and ve~ocities and cannot be
fully collected by the blades, whereas the quantity per unit
time of contaminants approaching the upstream blade ends is
substantially under the collection capability of the blades.
Thus the amount of gas per unit time which can be processed and
the percentage of contaminants removed are reduced. A
modification in application Serial No. 193 216 improved this
situation somewhat with a small deflector disc located some- ~-
what downstream of center in the slinger wheel.
However, I find, from continuing efforts to improve the
apparatus disclosed in application Serial No. 193 216, that
- gas distribution uniformity along the blades and extraction
performance are further enhanced by the two stage deflector -
228 of Figures 2 and 4 herein. Thus, a portion of the incoming
gas stream passes through the central opening of primary de-
flector 230, and is deflected radially by the upstream face of
secondary plate 231. Other incoming gas is initially rotated
by the adjacent tabs 236, part thereof also being deflected
through the central opening 234 and part thereof moving radially
outwardly, even with a somewhat reversed (leftward) motion,
along the leftward face of plate 230. Further incoming gas re-
flects from the annular upstream face of plate 230 radially
and somewhat axially reversely outwardly. The remaining incoming
flow enters the slinger wheel substantially axially outboard of
the deflector 228 and interacts with the deflected flow portions
above discussed. The result is substantial axial uniformity in
distribution of the gas flow outward between the blades 111.
The gas L (Figures 2 and 5) moving outwardly through the
bIaded periphery of the slinger wheeI 106 normally tends
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(momentarily ignoring drive 213) to rotatably drive the slinger
wheel, in the same direction as the blower wheel, and may be
thought to push on the trailing faces of the blades 111. Thus,
if free to rotate on its shaft, the slinger wheel 106 would be
rotated by gas flow drawn therethrough by the suction blower 35.
Indeed, a relatively compact but high speed blower wheel
could, by such gas flow, rotate a free wheeling larger diameter
slinger wheel at above optimum blade tip speed, degrading extrac-
tion efficiency. However, increasing slinger wheel diameter
beyond that of the blower wheel advantageously permits increasing
thenumberof slinger wheel blades and hence the slinger wheel
surface area available for accumulation of contaminant materials
from the gas flow. Thus, in the particular embodiment shown in
Figure 2, a relatively small, hence economical blower wheel is
rotated at a relatively high speed, whereas a notably larger
diameter slinger wheel has its rotational speed fixed at a
slower rotational rate for optimum extraction by drive 213.
Depending on the gas flow drawn through the slinger wheel, the
drive 213 may be negative, that is, impose a braking force on
the slinger wheel to prevent such gas flow from overspeeding the
slinger wheel.
As the gas flow L strikes and is deflected by the blades 111,
it tends to slow and deposit entrained contaminants on the blades,
particularly on the trailing accumulation surfaces 246 at and
adjacent the outer edge flanges 244. While accumulated contami-
nant masses on the blades (as at Go Figure 5) in part tend to be
thrown tangentially from the blades, the axial twist T (Figure
6) in the blades, causing the upstream end of flange 244 to trail
the downstream end thereof, results in migration of a portion of
the accumulated contaminants upstream along the blades toward the
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cut-away portion 247. The cut-away portion 247, by tapering
the upstream accumulation surface area of the outer flange 244,
enhances release of contaminant masses from the upstream portion
of the blade. This increases the proportion of accumulated
contaminates thrown from the upstream blade end of the blades.
Such increase counteracts the tendency of contaminant materials
to accumulate and/or migrate downstream on the blades, as due
to the net axial downstream movement of gas flow adjacent the
tips of the blades. More particularly, gas flow out of the
wheel 106 takes on a downstream motion component preparatory to
movement past the extractor end wall 82 and tunnel 203.
Despite slowing of the gas flow by the blades 111 and the
large annular gas flow space radially outboard of the slinger
wheel tending again to keep gas velocity and entrainment
capability low, the net downstream axial gas movement in this
area may tend to angle somewhat axially downstream the normally
tangential path of accumulated masses thrown from the wheel.
On the other hand, it is desirable that masses thrown from the
wheel 106 reach the screen 251 with a relatively uniform axial
distribution. Thus, it becomes additionally desirable to
eliminate disproportionately heavy gas flow and contaminant
accumulation at the downstream end of the slinger wheel. Thus,
the aforementioned uniform distribution on the blades enhances
the desired uniform distribution of contaminants at the screen
251. Indeed uniformity in the latter distributijon is sub-
stantially attainable even with somewhat greater amounts of
contaminant materials thrown from the upstream, as compared
with the downstream, portions of the blades.
Axial uniformity of contaminant material accumulation on
the extractor housing peripheral wall 84 is desirably enhanced
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by the angling of the screen hole axes 257, which tends to
impart an axially upstream motion component to particles moving
through the screen holes despite the net downstream movement of
adjacent gas flow between the screen and slinger wheel.
As a result of this attention to uniformity of distribution
by use of deflector 228, the particular configuration of blades
111 and arrangement and configuration of screen 251~ increased
extraction efficiency, in terms of percentage of contaminant
materials removed from the gas stream has been obtained.
The cleaned gas flow, indicated by arrows C (Figure 2),
exits from between the slinger wheel and housing end wall 82 and
enters the tunnel 203. I have found radially nonuniform gas
flow in the tunnel 203, with greater gas density adjacent the
shaft 209 than near the tunnel periphery. To counteract this
and simultaneously provide a secondary extraction capability for
even further reduction of contaminants in the flow, the deflector
267 angularly deflects the gas flow outwardly from the shaft 209
and toward the annular corner area 274. Upon encountering the
; ring 263, the gas flow is deflected inward, undergoing radial
deceleration and tending to deposit remaining contaminants, if
any, in the annular corner zone 274, before entering the blower
35.
Accumulated contaminants behind screen 251 and, if any, in
the annular corner zone 274 drain downwardly along the cylindri-
cal walls of the housing 84 and tunnel 203 and into trough 131
directly or through conduits 273 and 136.
Despite the high proportion of open area in the screen,
its close spacing from the extractor housing peripheral and
endwalls substantially reduces the velocity of any gas flow in
the "dead air" space between the screen and extractor housing
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i~65Z~3
peripheral wall 84. Such reduces possible reentrainment of
contaminants behind the screen by the gas flow passing out of the
slinger wheel and toward the tunnel 203.
Spent cleaning liquid from the wash apparatus 280, 281
drains from the housings 84 and 51 and tunnel 203 automatically
through the drain system 131. Thus, such a periodic cleaning
of the housings 84 and 51 and tunnel 203, andof their contents
; tends toclean the drain system as well. ;
- MODIFICATION
Figures 10-12 disclose a modified slinger wheel 106B with
modified blades lllB. The primary modification is that the ~-~
- radially outer edge of the central web 241B of blade lllB is
angled and diverges from the inner web edge toward the upstream
end of the slinger wheel. Thus, the upstream end of the central -
web 241B is wider than the downstream end and the upstream end
247B of outboard flange 244B lies radially offset beyond its
downstream end. Correspondingly, the upstream diameter of
modified slinger wheel 106B is greater than its downstream
diameter. Such results in an increase in blade tip speed from
downstream to upstream blade ends, tending to further enhance,
due to increased centrifugal force, upstream migration of
contaminant materials along the accumulation æone of the blade
lllB and to increa e throwing of contaminant masses from the
slinger wheel upstream end. The central web 241B in this
modification is flat, rather than twisted.
While the apparatus of Figures 1-12 herein is disclosed
with a horizontal shaft axis, adaptation to a vertical axis
orientation is contemplated. In the latter instance, the drain
system 131 may be eliminated or, preferably, rearranged with
its feeder conduits coupled to the bottom end walls of the
-22-
:' "'`
.
106SZ~;3
of the housings 81 and 51.
Although a particular preferred embodiment of the
invention has been disclosed in detail for illustrative
purposes, it will be recognized that variations or modifica-
tions of the disclosed apparatus, including the rearrangement
of parts, lie within the scope of the present invention.
:, :
: :
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