Note: Descriptions are shown in the official language in which they were submitted.
l3Z6S
SLUDOE SEPARATION APPARATUS
BACKGROUND OF THh' INVENTION
The present invention relates to an apparatus for
separating sludge from a liquid and may be advantageously used
in conjunction with a spray booth wherein water is used to
remove oversprayed particles from the air.
The spraying of coatings such as paints, enamels,
lacquers, etc. is commonly conducted in booths in which a flow
of air transports oversprayed particles and volati~e organic
solvents away from the worker. An efficient method of removing
oversprayed particles from the air within such a booth is to
provide water washes in the path of the coating spray and/or air
flow, the water washes trapping the airborne particles. A spray
booth of this type is disclosed in U.S. Patent NoO 4,484,513,
issued on November 27, 1984. In such spray booths, the trapped
paint particles travel with the water to a holding tank from
which the water is recirculated to the water washes. Most
holding tanks have chemicals added to the water therein for
agglomerating the paint spray particlPs, and many of the
agglomerated particles form a floating piece of sludge.
While watar wash spray booths have effectively cleaned
the air that is exhausted from the spray booth, the problem
remains of how to dispose o~ both the agglomerated spray
particles cleaned from the air and the water used to clean the
air. For example, when solvent-based coatings are used in the
spray booth, significant amounts of hydrocarbons may be released
into the air, not only during initial spraying, but also as they
evaporate from the agglomerated oversprayed particles floating
in the water in the holding tank. Further, discharge of the
water utilized in the spraying booth presents a substantial
waste disposal problem. Due to the solvents, paint particles
and the paint agglomerating chemicals contained therein, the
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water may not be directly discharged into sewage systems.
Because of problems associated with disposal of the water, it
is desirable to use the water for as long as possible before
replacing it. However, concomitant with the use of the water
is the need to prevent the formation of septic conditions
therein. Although certain chemicals may be used to prevent
septic conditions in the water, such chemicals add further to
the pollution problem entailed in the eventual discharge of the
water.
Because the sludge contains, in part, recoverable
pigments, it may, in some instances, if collected, be recycled
by chemical companies. Often the, maintenance o~ the spxay
booth had involved the periodic skimming of the sludge from the
tank and the dispatching o~ a Crew to drain and manually scrape
sludge from the bottom of the holding tank.
A sludge separation device that addresses the concerns
discussed above is disclosed in U.S. Patent No. 4,432,870~
issued February 21, 1984. The device of the patent employs a
separate sludge removal tank from which floating sludge is
transf~rred to a collection bin ~y means of a reciprocating
skimmer. The present inVention constitutes an improvement over
the above-referenced sludge separation device in that the water
levels of the holding tank and the separation tank are no longer
required to be substantially the same in order for li~uid and
sludge to be transferred therebetween, thereby making the
retrofitting of existing spray booths with the inventive
separation device not dependent on the elevation of the holding
tank of the spray booth. Collaterally, the inventive separation
device removes the requirement that the water levels in the
respective tanks be precisely controlled in order for sludge and
liquid to be transported from the holding tank to the separation
tank and for clarified liquid to be returned
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from the separation tank to the holding tank.
Addi-tionally, the drive system for reciprocating the
skimmer that forms a part of the separation clevice is
improved so as to be subjected to fewer stresses durinq
the course of operation and less lilcely to come in
contact with contaminating and corrocling sludge ancl
water during the course of operation.
SUM~IA~Y OF THE INVENTION
These advantages are obtained by a sludge
separating apparatus that inc:Ludes a separation tank for
receiving a supply of liquid and sludge from an adjacent
holding tank. Pump means is utili%ed for transporting
suspendecl sludge from t]-e adjacent holding tan1c to the
separation tank, with the pump means having an inle-t ln
the holcling tank and an outlet in the separation tank.
In order to prevent sludge particles from settling on
the bottom of the separation tank and to circulate such
particles upwardly toward the surface of the liquid, the
outlet from the pump is disposed at the bottom of the
separa-tion tank, and a baffle plate is disposed in the
separation tank adjacent the outlet for directing the
suspended sludge entering through the outlet toward the
surface of the liquid held in the separation tank.
Dividing means, such as a plate, isolates the separation
tan~s into two regions, the outlet of the pump means
being in the first region. The dividing means allows
relatively sludge-free or clarified liquid to pass into
the second region, and liquid return means associated
therewith returns the clarified liquid to the holding
tank. An automatic skimmer including a carriage that
has a pusher plate mounted thereon is associated with
the first region of the separation tank. The pusher
plate of the skimmer engages sludge floating on the
surface of the liquid and drives the sludge over an
upstanding wall bounding the first region of the
separation tank into a collection drum or the like. The
drive means for reciprocating the skimmer inclucles an
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endless chain entrained about two gears, one of th~ gears being
rotated by a motor to rotate the chain. An actuator attached
to the chain is captured within a channel secured to the
carriage, the channel being oriented perpendicular to the
direction of skimmer travel.
BRIEF DESCRIPTION OF ~E DRAWINGS
FIG. 1 is an elevational view of a spray booth and an
attached sludge separation device embodying the various features
of the invention;
10FIG. 2 is an enlarged e:levational view in partial
cross-section of the sludge separation device shown in FIG. 1,
F~G. 3 is a side elevational view in partial cross-
section of the sludge separation device shown in FIG. 2;
FIG. 4 is a fragmentary cross-sectional view of the
sludge separation tank taken substantially along line 4-4 in
FIG. 3;
FIG~ 5 is an enlarged fragmentary view of a portion of
the liquid return means associated with the sludge separation
tank;
20FIG. 6 is a view of a portion of the liquid return
means taken substantially along line 6-6 in FIG. 5;
FI~. 7 is a fragmentary cross-sectional view of a
portion of the holding tank including the intake associated with
the pump means o~ the instant invention;
FI~. 8 is a top vi~w of the holding tank and intake
shown in FIG. 7;
~IG~ 9, appearing on the same sheet as FIG. 1, is a
rragmentary perspective view of the automatic skimmer associated
with the instant invention;
30FIG. 10. is a side view of the automatic skimmer and
its reciprocating drive means;
FIG. 11 is a top view of the automatic skimmer its
associated drive means illustrated in FIG~ 10; and
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FIG. 12 is an enlaryed view of the actuator and
-traclc that form a par-t oE the reciprocating drive means.
DETAILED D~SCRIPTION OF THE PREFERRED EMBODIMENT
... . _ . .. . . _
Referring to FIG. l, a spray booth, generally
indicated by lO, is illus-trated which utili~es a ~ater
wasn including a water curtain comprising a plurality of
s-taggered ba-Efle panels ll spanning the booth 10 for
removing oversprayed particles from the air. T~e booth
lO has a housing 12 within which various articles are
situate~ hile they are being sprayed. The housing 12
circumscribes airborne particles o~ the spra~ and
includes a front end opening 14, and au-tomatic c~evices
or a worker in the booth directs a spray ~un or the like
at articles suspended within the booth. Air circula-tion
apparatus (not shown) draws air -throug~ the open front
14 of the booth and exhausts it exterior of the plant
through an upper exhaust pipe 15. Water ls circulated
by a pump 16 from a lower holding -tank 18 throu~h a
conduit in-to a reservoir (not shown) adjacent the upper
end of the baffle panels 11. The water over~lows the
reservoir and cascades over the surfaces of the baffle
panels 11 to form the water curtain. The cascading
water entrains the airborne particulates drawn througll
the booth, and then returns to the holding tank 18. As
previously noted, the entrained particulates agglomerate
on the surface of the water in the holding tank 18 to
form a sludge.
A sludge separa-tion tank l9, shown along side
the spray booth 10, includes a rectangular upper portion
having vertical sidewalls 20, while a lower trough
portion of the tank 19 has sidewalls 22 which angle
inward from the vertical sidewalls 20 of the upper
portion of the tank 19 and meet at the narrow hottom
25. As illustrated, the sidewalls 22 of the tank are
inclined at about an angle of 45.
In accordance with the present invention, pump
means is provided for transporting floating sludge from
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the holdin~J tank 18 to the sludge separation 19. Thus,
there is no requirement that the separation tank 19 be
positioned so that the water level therein is at the
same elevation as the water level in the holding tank 18
in order for water to flow therebetween, or that the
separation tank 19 even be contiguous with the holding
tank 18 of the spray booth 10. Turning to the cdrawings,
the pump means includes an in:Let box or sludge collector
26 spanning a corner of the holding tank 18. As best
seen in FIG. 8, the inlet box 26 is substantially
trapezoidal in cross-section when viewed from above.
However, the inlet box 26 may be of any non-circular
cross-sectional shape, such as triangular or
rectangular, as a circular cross-section encourages t'ne
formation of an undesirable vortex or whirlpoo] in the
inlet box 26. The upper and outer edge of the inlet box
26 inclucles a weir 28 coextensive therewith and
vertically adjus-table so that its upper edge is just
below the water level of the holding tank 18. In
practice, the inlet box 26 best functions when the edge
of the weir 28 is one-half to three-quarters of an inch
below the surface of t'ne water. The adjustability of
the height of the weir 28 may be provided by any
expedient method, such as the slot and bolt conbination
illustrated in the drawings. Accordingly, water and
surface sludge flows over the weir 28 into the inlet box
26 and is transported to the separation tank 19.
In order to better circulate the water, and,
consequently, the surface sludge in the holding tank 19
toward the inlet box 26, a plurality of water discharge
nozzles or auxiliary water jets, such as that indicated
by 29 (FIGS. 7, 8), extend into the interior of the
holding tank 18 at or near the surface of the water held
therein. Such water je-ts 29 are directed toward the
inlet box 26 and pressurized water from the circulatlon
pump 16 is expelled therefrom to help create a generally
circular flow through the holcling tank 18 so as to urge
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floating particles of sludge toward the inlet box 26.
Such water jets also serve to oxygenate the water in the
holding tank 18. Addi-tional water jets (not shown) may
be employed near the bottom of the holding tank so as to
sweep the bottom of settled particulates and circulate
the same toward the surface of the water.
Connected to the inlet box 26 is a suction line
or pipe 30 that leads to a se:Lf-priming pump 31. In
order to further and more ful:Ly aerate or oxygenate the
water in the booth 10, air is deliberately injected into
the water. To this end, an alr line 32 (FIG. 2~ is
connected to the suction pipe 30 intermediate of the
inlet box 26 and the pump 31 adjacent a venturi 34
disposed in the suction pipe 30 just upstream of the
pump 31. The high suction force of the pump 31 causes
increased velocity of water flow through the venturi
34. This creates a negative pressure relative to the
ambient pressure to draw air down the upstanding air
line 32 and into the water flowing into the pump 31,
whereby air is aspirated into the stream of the
sludge-laden water~ In addition to preventing septic
conditions in the water, the entrained air bubbles
adhere to the sludge particles so as to buoy same when
discharged into the separation tank 19, thus promoting
the formation of a sludge froth on the surface of the
water held therein which will be removed by skimming.
As illustrated, the upper inlet of the air line 32 is
disposed over the separation tank 19 so that, upon
stopping the pump 31 a liquid in the line 32 will rise
only as high as the water in the tank and not rise
sufficiently to flow from the air line and begin a
siphoning action through the line 32.
After entering the pump 31, the sludge-laden
water is transported up a pipe 35 through an overhead
elbow 36 located above the surface of the water in the
separation tank 19. The water is then directed
downwardly through a pipe 3~ (FIG. 3) and is expelled
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therefrom through an outlet 39 alony the narrowe-l bottom
25 of -the separation tank 19. In order to prevent the
siphoning of the sluclge-laden water back from the
separation tank 19 into the holding tank 18 after the
pump 31 is shu-t down, a vacuum vent 40 (best seen in
FIG. 3) is connected to the top of the elbow 36. The
air entering the elbow 36 above the height of the water
in the separation tank 19 acts to break any siphoning
action after the stopping of the pump 31. As
illustrated, the inlet of the vacuum vent ~0 extends
downwardly and is disposed over the separation tank l9
so that any liquid that may travel therethrough while
the pump 31 is activated flows into the sepaxation tank
19 .
In accordance with the invention, a baffle
plate 41, best seen in ~IGS. 3 and 4, is disposed in the
narrowed bottom 25 of the separation tank 19 adJacent to
the outlet 39 through which sludge-laden water is
discharged into the separation tank 19. In practice,
the baffle plate 41 is approximately five inches in
height and spaced from the bottom of the tank 19 by
approximately one inch. To direct the incoming sludge
toward the surface of the water in the separation tank
19, the baffle plate 41 is inclined away from the outlet
39 at an angle of from approximately 3 to 5 from
vertical. Additionally, the outlet 39 is angled at
approximately 45 to diffuse the sludge-laden water as
it is discharged into the separation tank 19.
A second baffle plate or divider 42 extends
between the two opposite sides 20 of the upper portion
of the separation tank 19 "upstream" of the outlet 39
for the sludge-laden water so as to divide the
separation tank into two parts, 44, 45. The upper edge
of the baffle extends above the surface of the water in
the separation tank 19, while the bottom of the haffle
42 is spaced from the bottom of the tank 19 so that
wa-ter may f]ow underneath. As shown by the directional
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arrows in FIG. 3, the sludge-laden water discha~ging the
pipe outlet 39 hits the baffle 41 and is deflectecl
upwardly to create a circular rotational flow on the
left side of the baffle plate 42 to float the sludge to
the top of the tan~c without settling of the sluclge.
Accordingly, as the ba-ffle plate 41 deflects incoming
sludge away from the bottom oE the separation tank and
-toward the surface of the water held therein, floatinq
sludge will remain in the first region 44 of the
separation tank, as defined by the baffle plate 42,
while clarified water relatively free from floating and
suspended sludge flows from the left side of the
separation tanlc and drops and flo~s under the baffle 41
into the second region 45.
Contiguous with the second or sludge-free
region 45 is a reservoir 46 into which the clarified
water flows over a weir 48 (FIGS. 3-6) integra] with the
end panel 49 of the separation tank 19. The clari f ied
water is then returned by gravity to the holding tank 18
through a pipe 50. In accordance with the invention,
the height of the upper edge of the weir 48 is
adjustable so as to regulate the water level in the
separation tanlc 19. To this end, the weir 48 is
pivotally attached to the end panel 49 by means of, for
example, a llinge 51 (FIG. 5) coextensive with t~e weir
and the upper edge of the end panel 49. Once the
desired height of the edge is achieved by pivoting the
weir 48 about the hinge 51, the position of the weir is
maintained by two friction pads 52 (FIGS. 5-6) in the
form of nylon bolts that engage opposite sides 53 of the
return reservoir 46. The nylon bolts are disposed at
opposite ends of the weir 48 and are secured thereto by
means of ears 54 integral with the weir. The nylon
bolts are received in threaded holes in the ears 54 and
may be screwed to exert sufficient force against the
sidewalls 53 of the reservoir 46 to maintain the
position of the weir 48.
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Briefly summarizing the operation of the system
to this point, a major portion of the overspra~
particles are trapped by the water cascading down the
baffle panels 11 and is dumped into the holding tank
18. rrhe particles and water are then transported to the
sludge separation tank 19 where the partic]es are
floated to the surface of the first region D~4 of the
separation tank, while clarified water is returned fro~
the second region 45 to the holding tank 18, whereupon
the water is recirculated to the baEfle panels 11. In
keeping with the invention, the agglomerated particles
forming the sludge floating in the first region 4~ of
the separation tank 19 are removed by a skimmer,
generally indicated by 55, that is periodically
reciprocated to shove the sludge up an upstanding wall
or inclined panel 56 extending outwardly from the sludge
separation tank 19 and over the edge of the panel 56
into a sludge collection container or drum 58.
Preferably, t'ne collection drum includes a hose 59
leading from the bottom of the drum 58 to the holding
tank to form a supernatent drain, and in practice, the
drum 58 is lined with a disposable liner (not shown).
~fter the collection drum 58 is filled, it is sealed to
prevent further release of hydrocarbons and forwarded to
a chemical company -for recovery of pigments or is
forwarded to a chemical disposal company.
Returning to the drawings, the skimmer 55
includes a carriage 59 that straddles the separation
tank 19 and rolls on four wheels 60 over parallel tracks
61 running along the sides of the tank 19 and upwardly
along the inclinecl panel 56. The sludge is skim~ed from
the surface of the water by a pusher plate 62 which has
a transverse dimension generally equal to the distance
between -the vertical sidewalls 20 of the separation tank
19. l'he pusher plate 62 may be mounted to the carriage
59 as described in U. S. Patent Mo. ~,~32,870, so as to
pivot between a vertical skimming position (when the
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carriage 59 travels from right to left as seen in FIGS.
3 and lO) and a tilted return position (when the
carriage 59 travels from left to right) in which the
pusher plate is entirely out of the water. When in ;.ts
vertical skimming position, the pusher plate 62 extends
below the surface of the water in the separation tank 19
so as to engage the floating sludge. The d.rive of the
skimmer has proven to be difficult in that not only must
the drive reciprocate the skimmer rectiliniarly but also
the drive must accommodate the tilling of the slcimmer as
it pushes sludge over the end of the tank.
In accordance with the invention, a drive
system is provided for periodically reciprocating the
carriage back and forth over the separation tank 19 and
to allow upward pivoting of the skimmer without
binding. Referring to FIGS. 9-12, the drive system,
generally indicated by 64, overlies the separation tank
19 and is supported by upstanding brackets 65 secured on
opposite ends of the separation tank 19. The drive
system 64 includes an endless roller chain 66 trainecl
about two sprockets or gears 68, 69, gear 6~ being
driven by a motor 70, while gear 69 is a free-wheel;ng
or idler gear. A protective guard 71 encloses the chain
66 and gears 68, 69 to prevent unintentional contact
therewith by personnel during the operation of the drive
system and to protect the system from dirt and grime.
In order to reciprocate the carriage 59, the chain 66
carries an actuator ball 72 that is captured in a ball
track or channel 74 secured to the carriage 59, the
groove and sidewalls 75 of the ball track 74 being
oriented perpendicular to the direction of reciprocation
of the carriage 59, as indicated by the arrow 76 in FIG.
12. Accordingly, the actuator ball 72, when moving with
the traveling chain 66 between the two gears or
sprockets 68, 69, will engage one of the sidewalls 75 of
the ball track 74 to push the carriage toward one or the
other ends of the separation tank 19. Upon engagement
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of the portion of the chain 66 supporting the actuator
ball 72 with either gear 68, 69, thus changing the
direction of travel of the actuator ball 72, the
actuator 72 will slide in the ball trac]c 7~ toward the
opposite end thereof and, upon rotation about the gear,
will engage the opposite ball track sidewall 75 to push
the carriage in the opposite direction. The spherica].
surface of the ball 72 allows the forward sidewall of
the ball track to s].icle upwardly therealong with the
rearward sidewall moving downwardly along the ball as
skimmer carriage moves up the inclined panel 56. In
order to prevent the chain 66 from slipping about the
gears 68, 69 during operation, two spring~loaded
plunger-type tensioners 78 (FIG. 11) are provicled to
tighten the chain 66 about the gears 68, 69.
Vescribing the actuator ball and ball traclc in
greater detail, in order to secure the actuator ball 72
to the chain G6, at least two pins 79 of the roller
chain 66 are hollow so as to receive screws 80 that
secure a carrier block 81 to the chain 66. (See FIG.
12.) The actuator ball 72 is secured to the carrier
block 81 by a bolt 82 received in a bore 84 coincident
with the diameter of the actuator ball 72. In or~ler to
reduce wear on the walls 75 of the ball track and to
lessen the friction between the walls and the actuator
ball 72, abrasion-resistent pads 85, preferably made of
ultra-high molecular weight polyethylene, are secured to
the walls of the ball track 74. As can be appreciated,
motion of the actuator ball 72 in the track 74 is
restricted only by the sidewalls 75 of the track, the
actuator ball being free to move up or down between the
walls and along the channel formed thereby. Thus, as
the forward wheels 60 hit the inclined truclcs 61 at the
upwardly inclined panel, the forward ena of the skimmer
tilts upwardly and the forward pad 85 slides upwardly
without binding along the upper forward quadrant of the
actuator ball 72. Conversely, when the skimmer plate 62
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comes down from -the inclined panel the ball slides along
the abrasion plates 85 without binding. Accordingly, no
undue aclditional stress is placed on tlle drive sys-tem
when, during its operation, the carriage travels up the
inclined panel 56 to push the sludge into the co]lection
drum 58, the ball trac]s 74 and carriage 59 being ahle to
rotate wi-th respect -to the actua-tor ball 71 at least the
amount of incline of the panel 56. As the ball 72
travels about the sprockets from one run of the chain to
the opposite run of the chain, the ball slicles
-transversely along the abrasion pads ~35 and in the
channel therebetween without binding.
In practice, the skimmer 55 of the slu~lge
separation apparatus is reciprocated intermittantly as
suEficient sludge frot}- accumulates on the surface of
the water in the separation tank 19. EIowever, the pump
31 will generally be operated continuously even through
brief periods when the booth lO is not being used for
spray coating. This ensures both the aeration of the
water in the tanks 1~3, 19 and the cleaning of the water
between coating opera-tions. When the spray booth lO is
unutilized for extended periods the pump 31 may be shut
down.
l'hus, it can be seen that a sludge separation
apparatus has been provided that fully meets the ob~ects
set forth above. ~hile the inven-tion has been described
with reference to a preferred embodiment, it is not
intended to so limit the invention. On the contrary, it
is intended to cover all alternatives, modifications and
equivalents within the scope of the invention as defined
by the appended claims. For example, the divider ~2 has
been described in terms of a baffle plate. However, any
structure capable of dividing the separation tank into
two regions while permitting only sludge-free water to
pass into one of the regions, such as a screen or the
like, could function equally well.
