Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to an apparatus for treating flowable mate~
rial The invention is particularly useful in an apparatus for irradiat-
ing sewage sludge with electron beams.
As is known, various types of devices have been utilized for treat-
ing flowable material, and in particular irradiating sewage sludge with
electron beams. In one such apparatus, as described in Swiss Patent 583,586
(U.S. Pat. 4,074,138), a pivotally mounted distribution box bears on the per-
iphery of a conveying drum and serves to apply a thin layer of the flowable
material onto the drum. In this construction, the discharge side of the
distribution box is formed by a distributing roller which extends between two
side walls of the box and which rotates in the opposite direc-tion to the con-
veying drum. In addition, the side walls of the box bear on lateral turnings
or shoulders of the conveying drum. ;
However, in these constructions~ the flowable material, and there-
fore any abrasive particles in the material, may enter between the side walls
I
and the shoulders of the drum and cause wear on both the box and drum. ~-
Briefly, the invention provides an apparatus which is comprised of
a rotatable drum, a distribution box having an outlet end and a pair of side
walls mounted over the drum for discharging a thin layer of flowable material ~
onto the drum peripheryg a sealing groove fo~med in at least the side walls ;;
of the distribution box with an open side facing the drum and means for supply-
ing a barrier fluid to the sealing groove to seal the side walls and the drum
relative to each other.
The apparatus may include a rotatable distributing roller which is
mounted 1n the side walls of the distribution box and extends across the out-
let end of the box. This roller forms the discharged material into a thin
layer on the drum and is rotatable in a direction opposite to the drum. AlSOg
a sealing means may be provided between each roller end and a respective box
side wall to prevent leakage. For example~ an annular seal ring may be pro-
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vided with each ring mounted between a roller end and a respective side wall.
Each seal ring has an annular groove which faces a side wall and a means is
provided for supplying barrier fluid to the groove in order to seal the rol-
ler end and the side wall relative to each other. In addition, each seal
ring is movably mounted within a recess in ~he roller end and is spring~
biased by a suitable means axially of the roller against a side wall of the
distribution box.
In order to prevent material from entering between the sliding ring
seal and the distributing roller, each ring seal can be formed with a peri-
pheral groove which faces th0 roller and is in flow communication with the
annular groove of the seal ring.
Each seal ring may have a spherical peripheral surface which is inpPripheral contact with the roller in order to allow angular motion between
the roller and the box side walls. In similar fashion, the contact surfaces
by which the ring seal contacts the side wall of the box may also be a spheri-
cal surface~
The apparatus may also include a means above the drum for directing
a radiation beam ontD the dru~.
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The distribution box is preferably supported on a suitable
support in spaced balanced relation to the conveying drum. To this end,
the distribution box may be balanced by an appropriate adjustment of the
support, the weight distribution of the box, the forces produced by the
distributing roller on the material and the forces produced by the barrier
~luid in the sealing groove in the distribution box. In this way, the box
can be carried by the conveying drum wi~hout contact.
In order to prevent damage to the distributing roller by trapped
solids, the roller may be journalled in pivotal bearings and the bearings
are mounted in a means which resiliently mount the bearing in an upward
direction.
In order to prevent particles of sludge from accumulating in the
sealing grooves of the distribution box, the bottom edge of each side wall
may have a widened section near the distributing roller in which at least
one passage is formed which extends from a point in the sealing groove
upstream of the roller to a point downstream of the roller in a side wall
facing the roller.
In the accompanying drawings, which illustrate an exemplary
embodiment of the present invention:
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Fig. 1 illustrates a verticle sectional view
through an apparatus according to the invention,
Fig. 2 illustrates a partial view of the apparatus
of Fig. 1;
Fig. 3 illustrates a view taken on line III
of Fig. 2;
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Fig. 4 illustrates a horizontal sectional view
taken Gn line IV - IV of Fig. 3; and
Fig. 5 illustrates a view taken on line V - V of
Fig. 2.
Referring to Fig. 1, the apparatus for irradiating
a flowable material, such as sewage slud~e, includes a large
hollow rotatable conveying drum 1, for example, of a diameter
of 2 meters and a length of 3 meters onto which a layer of
material can be deposited. The drum 1 is rotatably mounted on
two journals 2 (shown diagramatically) and is driven via a
transmission (not shown) in the direction indicated by an
.~ arrow 3. -~
A distribution box 5 is mounted over the drum 1
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and is disposed upstream of the top dead center point of the
drum 1 as viewed in the direction of rotation of the drum 1.
~; This distribution box 5 is constructed with a pair of side
walls 6, and an end wall 7 and a base 8. The side walls 6
continue in the form of lugs or the like 9 beyond the end wall
7 and are rotatably mounted on a support in the form of a rod
10 .
The distribution box 5 also has an outlet end for
discharging a flow of material onto the periphery of the drum 1.
As shown, a rotatable distributing roller 12 is mounted in .-
: 30 the side walls 6 and extends across the outlet end of the . .
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distribution box 5 opposite to the end wall 7. The roller
12 forms the material which is discharged from the box 5 into
a thin layer on the drum 1 and is rotatable to the direction
opposite to the drum 1 as indicated by an arrow 15.
As shown in Fig. 3, each end of the roller 12 is
provided with a recess 13 from which a t~un,nionor the like 14 '
projects. Each trunion 14 passes through a side wall 6 via
an enlarged opening 27 and is journaled in a pivotal bearing
such as a spherical bearing 25. Each trunnion14 and bearing
25 is mounted on a pivotal swing arm 17 (Fig. 2) which is
able to pivot about a pivot pin 18 fixed in a side wall 6. ' -
As shown in Figs. 2 and 3, the arms 17 are biased by way of
resilient means such as springs 19 which bear on projections '
20 of the side wall 6 towards an abutment 22 which is here- " '-
inafter described. The height of the distributing roller 12
above the drum 1 can be adjusted by means of adjustable shims `"' ''' '
23 placed below the arms 17.
As shown in Fig. 3, a sliding ring seal 30 is
slidably disposed in each roller recess 13 and is secured in
a manner not shown against rotation relative to the roller
12. Each ring 30 faces a side wa~l 6 and is biased by suitable
means, such as a plurality of coil springs 31, into contact
30 against a side wall 6. Each seal ring 30 also has an
annular groove 32 which faces a respective side wall 6. This
provides an~advantage over ordinary ring seals in that there
is no wear.
As shown in Fig. 1, the support for the distribution '
box 5 also includes a resilient carrier 33 which is disp~osed
below the base 8 of the box 5. This carrier 33 employs two
adj!usting screws 34 which provide additional support for the
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box 5 and enable the box 5 to be adjusted relative to the
drum 1. A feed line 35 for the flowable material, such as
sewage sludge extends into the top of the box 5 to supply
the material.
A sealing groove 40 is formed in the side walls 6
and along the bottom 8 of the distribution box 5 in order to
seal the box 5 and the conveyor drum 1 relative to each
other. This sealing groove 40 has an open side facing the
drum 1 and as shown inFig . 3 includes a wall 41, a web 42,
and terminal parts 43 in each side wall 3. A suitable means
is connected to the groove 40 in order to supply a barrier
fluid for sealing the side wall 6 relative to the drum 1.
This means includes, for example~ a spigot 44 connected to
the groove 40 and a hose 45 which is able to supply a press-
urized barrier fluid, such as air. The sealing groove 40
also communicates with a groove 32 in each seal ring 30 via
bores 46 in the side walls 60
In addition, in the region below a bearing 25,
~ each side wall 6 has a widening section at the bottom edge
;~ ~ 20 which projects into the sealing groove 40 by way of a sill
47. The bottom edge ofthe side wall, as formed by the sill
47, also has a pair of passages 48, 49 therein. Each passage
48, 49 extends from points in the sealing groove 40 upstream
of the roller 12 to exit points 50, 51 downstream of the
roller 12 in a side of the side wall 6 facing the roller 12.
As indicated in Fig. 4, the passages 48, 49 are connected with- ;
out restriction at both ends to the sealing groove 40 and to
the inside surface of the side wall 6. Consequently, during
operation, a small amount of the barrier fluid can discharge
continuously from the sealing groove 40 through the exit
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points 50, 51. Alternatively, a groove (not shown) can
be formed in each side wall 6 to form a seal.
In addition, each seal ring 30 can be provided
with a peripheral groove (not shown) facing the inside wall
of the recess 13 to seal the ring 30 against the roller 12.
Also, the peripheral surface of each seal ring 30 may be
spherical and can be disposed in contact with the roller 12
to permit adjustments.
; Referring to Fig. 5, a confining member 60 is
fixed to the wall 41 at the ends of both arms of the channel-
shaped section of the sealing groove 40. The two confining
members 60 define the extent to which the material being
treated may spread out axially on the drum 1. Each member 60
is closed at both ends to form a rectangular box section,
the bottom side of thè bo~ being divided by a longitudinal
apperture with the longer arm 61 of the two arms 61, 62 being
~ inclined inwardly. As shown, the shorter arm 62 merges into
; a side surface 63 o the box section at a height slightl~
higher than the plane in which the longer arm 61 merges into
the side surface 64. Thls second side surface 64 also projects
beyond the box section at the end remote from the roller 12.
The members 60 may be secured to the walls 41 by screws 66
(Fig. 2) and may have a spigot 70 about half way along their
length through which a low pressure barrier fluid can be
supplied via a hose 71.
Referring to Fig. 1, the drum 1 is mounted in a
basin or tank 75 having an outlet 76 in the lower end. In
addition, an intermediate tank 78 having an outlet 79 is
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disposed downstream of the basin 75 and is separated from the
basin 75 by vertical wall 77. Also, a collecting tank or basin
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82 for irradiated material is disposed downstream of the tank
78. This basin 82 has an outlet 83 in the bottom and is
separated from the intermediate tank 78 by a vertical wall 80.
A wide scraping chute 85 is pivotally mounted on the wall 80
and the horizontal top edge 86 of the chute 85 bears on the
periphery of the drum 1 while the discharge edge 87 of the
chute 85 terminates above the basin 82. A motor (not shown)
is provided to disengage the chute 85 from the drum. As
shown, a scraping chute 90 is pivotally mounted on the wall
77 of the tank 75 and follows the chute 85 in the direction
of rotation of the drum 1. This chute ~0 has a top edge
which is in permanent engagement with the drum 1 while the
discharge edge of the chute 90 terminates in the intermediate
tank 78.
An exit tube 98 of an electron beam accelerator
(not shown) is disposed above the top of the drum 1. The
electron beam accelerator directs an accelerator beam 99
onto the drum 1 substantially in a radial plane. Known
deflecting means are adapted to oscillate the electron beams
~; 20 during operation in the region between the two side walls 6
of the distribution box 5.
In operatlon for example, the drum 1 rotates at
a peripheral velocity of approximately 3 meters per second.
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The roller 12 which is connected by a transmission to the
drum 1 runs more slowly, for example at 2.5 meters per second.
The box 5 receives sewage sludge via the feed line 35 which
sludge rises to a predetermined level in the box 5. This
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sludge passes through a gap 100, for example of a width of ~ ~
5 millimeters, between the drum periphery and the distribut- `
ing roller pexiphexy onto the exposed surface of the drum 1 -
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and forms a thin layer 101 whose thickness is usually greater
than the thic]~ness of the gap 100. This layer 101 is carried
by the drum 1 through the irradiation zone below the tube 98
and is removed from the drum 1 by the top edge 86 of the
chute 85 and is conveyed into the tank or basin 82. This
sludge then passes from the basin 82 via the outlet 83 to a
distributing system andr for example, is broughk to fields
and distributed over them as fertilizer.
If the electronic irradiation ceases for any reason,
the motor raises the chute 85 so that the chute 90 guides
the layer 101 on the drum 1 to the intermediate tank 78.
The sludge is then automatically pumped into the tank containing
the non-irradiated sludge and can then therefore be sub-
sequently irradiated.
In order to reduce the wear of the drum 1 and
of the bottom edge of the distribution box 5, the pressure ~:
medium such as air is injected at a pressure of, for example
0.05 atmosphere gauge through the hose 45 into the sealing
groove 40. This pressurized air then passes into the annular
~;~ 20 groove 32 in the ring seals 30 and acts as a barrier to pre- :
vent sludge from entering the ~ap between the drum 1 and
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the bottom edge of the box 5.
Since the pressure in the sludge increases in the
nip or bite area 103 on the approach flow 5ide between the
drum 1 and the distributing roller 12, there is a possibility
that particles of sludge might pass through below the side
walls 6 into the sealing groove 40 in this high pressure
zone. However, the accumulation of sludge particles in the
sealing groove 40 is inhibited by means of the grooves 48,
49 which are continuously flushed by the barrier medium.
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Consequently, any sludge particles which due pass through
into the groove 40 are returned to the drum 1.
The barrier air which is fed through the spigots
70 to the distributing members 60 is under a pressure of
only about 0.003 atmosphere gauge. This barrier or sealing
air issues from below the arm 62 as a mist or curtain or
layer with sufficient pressure to oppose the tendency of
the thin layer 101 of sludge on the drum 1 to spread out
axially. Since the drum 1 conveys the sludge layer 101 down-
wardly the tendency of the sludge layer 101 to spreadout axially becomes negligible at some point . Thus, the
distributing members 60 may terminate above the top edge
86 of the chute ~5.
The advantage of the pivoted mounting of the roller
12 on the s~ing arm 17 is that very hard solids which may
be present in the sludge, such as the balls of ball bearings,
do not damage the roller 12 but merely lift the roller, on
one side or both. In this case, the seal rings 30 can
readily take up a skew position relative to the axis o the
roller 12. In order to prevent the seal ring from jamming
in the roller edge around them, the peripheral surace of the ~-
ring can be spherical instead of cylindrical as shown.
In order to inhibit the entry of sludge into the
gap between the seal ring 30 and the edge of the roller 12,
the cylindrical or spherical outside surface of the ring 30
and/or the inside cylindrical surface of the edge of the
roller 12 can be formed with a circular groove (not shown) ~ ;
which communicates via suitable ducts with the yroove 32 in
the seal ring 30. This permits barrier air to flow into
thè circular groove and build up a pressure to inhibit the
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entry of sludge.
Alternatively, instead of supplying the barrier
medium in the sealing groove 40 via the ducts 46 to the seal
rings, each seal ring 30 can be supplied by other ducts and
with a higher pressure barrier medium which may be of another
type, for example water. Further, it may be advantageous
to subdivide the sealing groove 40 in accordance with the
pressure of the entering sludge into peripherally consecutive
chambers at different pressures.
It is to be noted that the pivots 18 for the swing
arms 17 and the abuttments 20 can be fixed in place instead
of being mounted on the side walls 6 for vertical movement
with the side walls 6.
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