Note: Descriptions are shown in the official language in which they were submitted.
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SOLIDS -LI QUIDS
oo 2 SEPARATION ~)EVICE
o 3 Samuel H. Dorcheus
BACKGROllND OF THE INVENTION
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7 This invention concerns a solids-liquids separation
8 apparatus including a rotable cylindrical drum where flow
9 movement of process liquid is provided rom a first level
of 1uid contained within the drum to a higher in elevation
11 level outside the drum. The c~bove function is provided by
12 a series of internal bailers contained within the drum
13 structure.
14
Field of Invention
16
17 The present invention relates to a rotary liquids-
18 solids separation drum device particlllarly to an apparatus
19 for filtering solid parti.cles from a liquid-solid slurry,
including washers for pulp and paper stock pulps. The
21 device provides for the movement of fluid from a sump at
22 the bottom of the interior of the rotary drum to a site
23 higher in elevation, namely to a centerline level without
24 the use of pumps.
26 Descri~1o _____ rior Art
27
28 According to various processes well-known to the art
29 and prior art apparatus, drum filters have been used for
many years in which a filter fabric is conveyed about a-
31 perforated rotating drum and filtrate is extracted from a
32 mat of slurried solid material on the fabric into the drum
33 interior. A typical arrangement is seen in U.S. Patent
34 Number 2,745,712 which provides for countercurrent washing
of cooking li~uor from paper pulp. Such patent shows wash
36 liquor which has been sprayed on ~he exterior of the drum
37 being conducted through the mat on the outside surface of
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1 the drum and through the apertures in the drum into the
2 drum interior. To conserve the wash water being used for
3 the washing cycle and to move the wash water to a precedi~g
4 drum for countercurrent washing a gravity flow from the
drum directly into a lower container by means of dxop
6 tubes 2, 4, 6 and 8 is provi~ed. Figure 5 of the patent
7 particularly shows the movement of the interior wash water
into the lower tank.
U.S. Patent Mumber 4,160,297 shows a machine and
11 process for washing paper pulp stock and similar free-
12 filtering materials including a series of horizontally
13 disposed wash drums, each mounted in a tank. Two endless
14 filter belts are trained to pass over each of said drums
and through liquid contained in each of the tanks. A mat
16 Of pulp is formed between endless filter belts and carried
17 under each of the drums for washing therein. Wash liquor
18 passes through the pulp mat as it travels under said drums
19 thereby washing the pulp mat and the liquor passes from
drum to drum by gravity flow. Thus in this ~ype of device
21 it is necesary to have the tanks stepped in elevation so
22 tha~ the materials from one tank flows into a lower tank.
23 Like~7ise, it is necesary tc have a mechanism fol rising
24 the liguid within the inside of the tank to a succeeding
tank. This is accomplished by a series of siphon tubes
26 which extend downwardly into the drum and terminate adjacent
27 to cylindrical sidewalls thereof. A suitable primer means
28 is also needed to provide initial suction to the siphon
29 tubes-
31 U.S. Patent Number 4,324,116 shows a further mechanism
32 for conducting wash water from the interior of the drum to
33 another tank through which the drum passes. In this
34 patent a series of radial extending filtrate conduits are
disposed within the drum and in operation a rotary valve
36 communicates with the conduits to permit liguid to flow
37 through the apertures in the sidewall of the ~rum and then
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1 from the drum via a port 22. This port is connected to
2 apply vacuum to the apertures and a pump is provided to
3 move the recovered wash liguor to an upstream tank conta n-
4 ing a second drum. As can be seen in each of these above
patents, flow is either provided by gravity, by suction
6 vacuum or by pumping to remove -the fluid within the drum
7 to a higher site outside the drum.
9 SUMMARY
11 The present invention is an improved, energy~conserving
12 apparatus for transferring fluid from an interior sump in
13 a drum-t~pe filter or washer to another station in the
14 flow path of the fluid slurry being treated wherein it is
desired ~o move such fluid to ~ point higher in elevation
16 than the sump level. The above function is performed by
17 one or more fixed bailers fixed to rotate with the drum
18 so as to pick up fluid from the drum sump and discharge
19 the flui~ at a higher elevation normally at the dru~
centerlin~ so that ~he fluid can then flow by gravity to
21 an upstream or downstre~m tank or other discharge point.
22 The device acts to pick up fluid from the interior of the
23 drum ~lo~ ~he l~ngitudinal len~th of tll~ ~rum and r.love
24 the pic}ce~-up fluid laterally along the axis of the drwn,
as the bailer pick-up means moves in its rotary cycle to a
26 higher elevation and to a point of discharge of the fluid,
27 whereby t~e fluid is caused to flow by gravity towards an
28 outlet po~sition adjacent the central axis of the dxum.
29 The device may also be employed to move fluid coming in
one trun~ion into the drum sump and then by the bailer-
31 action ou~ the other trunnion.
32
33 ~RIEF DESCRIPTION OF THE DRAWINGS
34
The ~resent invention may be readily ascertained by
36 the follo~7ing detailed description and appended drawings
37 which are offered by way of illustration only and not in
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1 limitation of the invention, the scope of which is defined
2 by the appended claims and e~uivalents. In the drawings:
4 Figure 1 is an end skeleton view of the bailer struc-
ture after the start of the bailer cycle;
7 Figure 2 is a similar view at the staxt of the dis-
8 charge cycle;
Figure 3 is a similar view beyond the end of the
11 typical cycle;
12
13 Figure 4 is a partial schematic elevation view of a
14 pulp washing machine according to the present invention;
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16 Figure 5 is a cross sectional view of a drum washer
17 utilizing the invention;
18
19 Figure 6 is a view of the drum,~aken on lines 6-6 of
Figure 5;
21
22 Figure 7 is a partial side view of the joint bet~een
23 the baffle plates making up the discharge trough of the
24 invention;
26 Figure 8 is a view of support structure taken on
27 lines 8-8 of Fig. 5
28
29 Figure 9 is a partial cross-sectional view o the
support and outlet structure for the trunnion of a t~ical
31 drum filter;
32
33 Figure 10 is a schematic elevation view of a gravity
34 decker utilizing the invention; and
36 Figure 11 is a schematic elevation view of a gravity
37 filter utilizing the invention.
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DETAILED DESCRIPTION OF DRAWINGS
3 A particular utilization of this invention is for
4 pulp washer configurations which employ a wash li~uor flow
from a drum tank through a slurry mat on a drum to the
6 interior of the drum with su~sequent removal of the fil-
7 trate from the interior drum sump. In this invention this
8 is done by means of interiorally placed bailers which
9 convey fluid filtrate from the sump to an exit at the drum
axis. The bailers rotate with the drum in a rotary cycle
11 and in a first portion of the rotary cycle act to pick up
12 fluid from the fluid sump within the drum and move it
13 upwards to an elevation where it is dischargeable by
14 gravity flow into an outlet contained at the rotation axis
1~ of the drum. This is illustrated clearly in relatively
16 rudimentary terms in Figures 1-3.
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18 Fisure 1 shows the initial part of the pic]s-up cycle
lC3 wherein a bailer lO having a lip portion ll functions to
pick up fluid within the sump and convey it upwardly in a
~1 fluid holding trough 14 formed by the lip portion and a
~2 longitudinal-extending baffle 12. The bailer lO is rotated
23 in the clockwise position about the rotatioil axis ~t a
24 fluid outlet 13.
26 Figure 2 shows the rotation after approximately 45
27 travel from the initial pick up. At this point, the tip
28 edge of the lip ll and the adjacent surface of baffle 12
29 forming the trough 14 is in a horizontal plane and the
~lope of the baffle allows fluid to flow down the surface
31 o~ baffle 12 into outlet 13. By the time the pick-up lip
32 ~l has reached a top vertical position as shown in Figure
33 3, discharge of all fluid from the trough 14 has been
34 accomplished and the bailer is ready to make another half
revolution and to again pick up and hold fluid from the
36 sump when it has reached the approximate so-called six
37 o'clock position in its rotary movement. The tip edge of
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1 the pick-up means 11 will intersect the fluid upper surface
2 in the sump before that position and will scoop the fluid
3 into the trough as it revolves around the bottom part cf
4 the rotary cycle. Figure 1 actually illustrates the cycle
as it is leaving the sump with the scooped-up fluid within
6 trough 14-
8 Figure 4 illustrates application of the invention to
9 a paper pulp washer. A washer such as typically shown in
U.S. Patent Number 4,160,297 and 4,324,116 illustrates
11 countercurrent washing through the utilization of multiple
12 drums and tanks in the pulp washer. Figure 4 is a partial
13 illustration of a co-current version of an overall pulp
14 washing system. Drums 20 and 21 rotate within fluid tanks
22 and 23. A pair of bailers 24 and 25 are shown in
16 drum 20 only for illustration purposes. Normally four
17 bailers will be contained in each drum, one in each quad-
18 rant, so that the various functions of the bailing device
19 will be simultaneously performed during the entire rotary
cycle. Bailers ~4 and 25 have bailer pick-up means 26 and
21 27 extending generally at right angles to the radially
22 extending baffles 28 and 29. The pick-up means are attached
23 to a series of conical or pyra~,lidal baffles which together
24 form troughs which hold the scooped up fluid from sump 32.
S~p 32 is at the situs A of the fluid which is desired to
26 ~e moved to a higher elevation point. As the drum and its
27 attached bailers are rotated clockwise, the combination of
28 the bailer pick-up and the baffles scoop up a volume of
29 sump fluid into the trough and transport it to a higher
elevation along the rotary cycle. When the bailer 25, for
31 example, reaches the position illustrated by the dotted
32 lines at 42, the trough is at such an angle so as to allow
33 fluid contained in the trough, formed by the bailer pick-up
34 means and the baffle, to flow by gravity down the baffle
towards its apex and length-wise of the drum to an outlet
36 30 contained in the drum trunnion 31. Fluid which has
37 been raised from situs A flows into the outlet 30 where it
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1 is transported by gravity through line 40 to situs B
2 typically the sump 41 of tank 23 through ~hich the other
3 drum 21 xotates. Situs B is at an elevation above situs ~.
~ but below the elevation of the outlet 30 of such tank 22.
Filter belt 35 is pulled through the total system by the
6 rotary mo~ion of the various drums 21 and 22. Illustrated
7 also is top drum 36 which acts as a spray wash drum.
8 Suitable sprays 37 spray wash fluid on the filter belt and
9 its mat of paper or other fibers so that the paper stock
may be washed clean of digestor chemicals, for example.
11 Wash water flow 38 from drum 36 may fall by gravity onto
12 incline f~owdeck 39 and become part of the fluid in sump
13 41 within tank 23.
14
Figure 5 shows a cross-sectional view of a drum
16 filter including this invention. Drum 50 contains a
17 cylindrical surface 51 which is apertured so as to allow
18 passage G~ filterable liguid or filtrate through the
19 apertures. Drum ends 52 generally ~ëal the inte.rior of
the drum. Centrally o the drum ends at the axis of ~he
21 drum are trunnions 53 which rotate in suitable trunnion
22 bearings and allow passage of fluid collected in the
23 interior ~f the drum to an exterior point. Baffles 54 are
24 provided within the drum and are connected to a framework
fixedly connected to the dxum interior. This frame~ork
26 comprises a first pair of support rings 60 situated,at the
27 extremetie~s of the drum, a second pair of support rings 61
28 at a midp~int between the central part of the drum and
~9 each drum ~nd and a central support ring 62 for supporting
~0 a series ~f baffles which form the fluid-conducting troughs
31 of this i~ention. Baffles 54 are shown as forming a pair
32 o~ pyrami~al members having abutting base portions at the
33 central p~rtion of the dr~ at ring 62 at the lateral
34 midpoint o~ the drum. The apices o ~he pyramidal baffles
extend towards the drum ends of the drum 50 and are in
36 flow comm~nication with a circle sector outlet 63 contained
37 in hub 53~ The truncated apex of each of these pyramidal
38 members terminates at a point 59 within the trunnion 53.
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1 Figure 6 is a view taken at the centerline of the
2 drum 50 and shows the "swastika"-like pickup means 55, 56,
3 57 and 58 extending around the inner periphery of the
4 cylindrical wall 51 of the drum 50. Pickup lips 55-58
form with the section wa].ls and baffles 54 a longitudinally-
6 extending trough or overall baffle means having a minimum
7 depth at the midpoint of the drum and a maximum depth
8 adjacent the drum outlet at point 59. Section walls 67
9 give structural integrity and stiffness to the drum as
well as providing the sides of the formed trough. Lips
11 55-58 run generally parallel to the inner periphery of the
12 drum 50 while the surface of the baffles extend inwardly
13 as the baffle progresses from its basepoint to the end of
14 the drum. Section walls 67 form the sides of the trough.
1~ Thus, all fluid that is picked up by the pickup means
~6 flows outwardly towards the ends of the drums to the
17 circle sector 63 contained in trunnions 53. Baffles 54
18 forming the bottom of the trough may also be made from two
19 conical members with abutting bases:~t the midpoint of the
drum length with their open apices ending in the trunnions
21 or may be in the form of one cone or pyramid extending the
22 whole length of the drum. In the latter case, outward
~3 flow of fluid will occur at one end of the drum only.
2~
Figure 7 shows a detail of the center ring and the
26 welding of the respective bases of each of the pyramidal
27 sections to that ring. Ring 62 comprises a first ring
~8 section 64 and a second ring section 66 joined by a
29 peripheral weld 65. ~ing 62 is attached both to the walls
of the pyramidal baffle and to the inner peripheral wall
31 of the cylindrical wall section 51 of drum 50.
32
33 Figure 8 shows a view of the drum of Figure 5 taken
34 on the lines 8-~. The framework on which the pickup scoop
means 55-58 is mounted comprises a spider 76 connected to
36 a support ring 75 which is connected to a surface of
37 trunnion 53 and welded to the inner periphery of the
38 cylindrical drum surface 51.
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1 Figure 9 is a partial view of the support and outlet
2 structure for the trunnion of a typical drum filter incor-
3 porating this invention. Trunnion 53 is supported on a
4 trul~nion bearing 70 which is supported by a trunnion
support 71. Trunnion bearing is provided between the end
~ wall 74 and the tank or vat 77 in which the drum 50 rotates
7 and the trunnion end. A suitable stuffing box 73 is
~ provided around the periphery of the trunnion 53 where it
9 passes throu~h the aperture 78 contained in tank end 74.
Extend.ing outwardly from the end of trunnion 53 is an
11 outlet box 72 which receives the filtrate from the interior
12 of the drum which is conveyed to it through the bailer
13 means. No seal is needed at the point of entrance of khe
14 trunnion into outlet box 72 unlike prior art devices.
Fluid picked up by lips 55-58 flow into trough 14 and are
16 conveyed down the slope of baffles 54 towards the apex of
17 the conical or pyram;.d members fo.rming the baffle structure.
18 Filtrate 68 thus flows towards that apex and is discharged
19 into outlet box 72 and falls by gra~t,.~.ty downwardly through
pipe 40 to any appropriate site.
21
22 Figure 10 shows a gravity decker or thickener u.sed in
23 the pulp and paper industry or in other industries where
24 thickening of slurries are desired. Appropriate feed is
fed into an inlet 81 in a semicylindrical tank 82 contain-
26 ing a rotary dr~ 83. Filtrate from the li~u.id solid
2~ slurry contained between the drum and the tank flows
28 through the perforated drum surface and forms inner sump
29 89. Bailer pickup means 88 scoops up the fluid filtrate
within the drum and picks up a volume 90 of such fluid and
31 conveys it upwardly to a discharge point ~t a portion of
32 the xotary cycle above the horizontal. Filtrate is shown
33 at 91 flowing into outlet 30. A mat is shown formed on
34 the surface of the drum 83 which is transferred to couch
roll 85. A doctor blade 86 scrapes off the fibrous mat
36 from roll 85 and the desired product 87 is transferxed to
37 further operations. Filtrate 91 is removed through outlet
38 port 30 as shown in Figure 9, for example.
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1 Figure 11 shows a gravity filter 92 which also may
2 use the present invention. In this embodiment, feed is
3 transferred by inlet 81 to tank 82 in which a drum 83
4 rotates. A portion of the liquid contained in the liquid-
slurry within the space between the tank 82 and drum 83 is
6 conducted by vacuum or hydrostatic head into an interior
7 portion of drum 83 forming a filtrate volume in sump 89.
8 Pickup means 88 scoops up the filtrate liquid in the sump
9 in its particular guadrant and moves a volume 90 of that
sump fluid around with tank 82 to and above the horizontal
11 position of the pickup means ~o a point which it can be
12 discharged as at 91 into the outlet port. As the filtrate
13 is removPd from the tank, other filtrate comes into the
14 succeeding quadrants and the material in the space between
the tank 82 and drum 83 increases in percent solids.
16 Thickened slurry exits the tank 82 by outlet 94. For
17 example, this particular modification may be used as a
18 black liquor filter for removing fiber from black liquor
19 prior to its evapora-tion.
21 It is also contemplated that the bailer of this
22 invention may be just one segment of a quadrant in which a
23 triangular baffle or floor is provided between two radial
~4 walls extending from the axis of a drum to the drum outer
cylindrical surface over a desired length of drum.
26 scoop lip picks up filtrate in a trough formed by the
27 baffle~ the radial walls and end walls of the drum The
28 apex of the baffle leads into a drain tube t the drum
2~ trunnion for discharge of the filtrate.
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