CA1072287A - Apparatus for irradiating flowable material - Google Patents

Abstract

AN APPARATUS FOR IRRADIATING FLOWABLE MATERIAL

Abstract of the Disclosure The distributing box is sealed with respect to the conveying drum via a sealing groove which is supplied with a barrier fluid. The sealing groove extends along the bottom edge of the side walls and the base of the distribution box.
In addition, each end of the distributing roller is resiliently mounted and is provided with an annular seal ring which is biased against a side wall of the box. The annular groove of each seal ring is also supplied with a pressurized barrier fluid to effect a seal. In addition, at least one passage is provided in a bottom edge of each side wall which extends from a point upstream of the distributing roller to a point down-stream of the roller and on the side facing the roller.

Description

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-~P,~ ~ ' .

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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 .
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 , . . , ' '. ' : ~ :. ' ' . : '.

~Z~7 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 ,: .
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 , .
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 .
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 ~ '7 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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Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an apparatus for irradiating flowable material, the combination comprising a rotatable drum on which the flowable material is to be irradiated;
a pivotally mounted distribution box having an outlet end and a pair of side walls mounted over said drum for discharging a flow of material onto said drum periphery; a rotatable distributing roller mounted in said side walls of said box and extending across said outlet end of said distribution box to form the discharged material into a thin layer on said drum, said roller being rotatable in a direction opposite to said drum; a sealing groove formed in at least said side walls of said distribution box, said groove having an open side facing said drum; and means for supplying a barrier fluid to said sealing groove to seal said side walls of said distribution box and said drum relative to each other.

2. An apparatus as set forth in claim 1 wherein said distribution box has a base extending across and over said drum and said sealing groove is formed in said base to seal said base and said drum relative to each other.

3. An apparatus as set forth in claim 1 wherein said distributing roller includes a recess in each end face thereof facing a respective side wall of said distributing box, and which further comprises an annular seal ring movably mounted in each respective recess axially of said roller, said ring having an annular groove facing a respective box side wall, means for supplying a barrier fluid to said groove of each seal ring to seal each respective roller recess and respective side wall relative to each other, and means spring-biasing each seal ring against a respective side wall.

4. An apparatus as set forth in claim 3 wherein each seal ring is slidably mounted in a respective roller recess and has a peripheral groove in flow communication with said annular groove thereof.

5. An apparatus as set forth in claim 3 wherein each seal ring has a spherical peripheral surface in peripheral contact with said roller.

6. An apparatus as set forth in claim 1 which further comprises a support having said distribution box supported thereon and in spaced balanced relation to said drum.

7. The combination as set forth in claim 1 which further comprises a pair of pivotal bearings journalling each respective end of said roller therein, and means resiliently mounting each bearing in an upward direction.

8. An apparatus as set forth in claim 1 wherein said sealing groove has a widened section in each respective side wall near said distributing roller and which further comprises at least one passage in the bottom edge of a respecti-ve side wall extending from a point in said sealing groove upstream of said roller to a point downstream of said roller in a side of said respective side wall facing said roller.

9. An apparatus as set forth in claim 1 which further comprises means above said drum for directing a radiation beam onto said drum.

10. In combination with a rotatable drum and a distribution box having an outlet end and a pair of side walls mounted over said drum for discharging a thin layer of flow-able material onto said drum periphery;
a sealing groove formed in at least said side walls of said distribution box, said groove having an open side facing said drum; and means for supplying a barrier fluid to said sealing groove to seal said side walls of said distribution box and said drum relative to each other.

11. The combination as set forth in claim 10 further comprising a rotatable distributing roller mounted in said side walls and extending across said outlet end of said box to form the discharged material into a thin layer on said drum; and a pair of annular seal rings, each seal ring being mounted between a roller end and a respective side wall, each said seal ring having an annular groove facing a respective side wall wherein said means for supplying a barrier fluid supplies barrier fluid to said groove of each seal ring to seal each respective roller end and respective side wall relati-ve to each other.

12. The combination as set forth in claim 11 wherein said roller has a recess in each end with a respective seal ring slidably mounted therein axially of said roller.

13. The combination as set forth in claim 11 which further comprises means spring-biasing each seal ring against a respective side wall.

14. The combination as set forth in claim 11 which further comprises a pair of pivotal bearings journallling each respective end of said roller therein, and means resiliently mounting each bearing in an upward direction.

15. The combination as set forth in claim 11 wherein said sealing groove has a widened section in each respective side wall near said distributing roller and which further comprises at least one passage in a bottom edge of a respective side wall extending from a point in said sealing groove upstream of said roller to a point downstream of said roller in a side of said respective side wall facing said roller.

16. The combination as set forth in calim 11 which further comprises means above said drum for directing a radiat-ion beam onto said drum.

17. The combination as set forth in claim 10 which further comprises means above said drum for directing a radiation beam onto said drum.