CA1255609A - Solids-liquids separation device - Google Patents

Abstract

ABSTRACT

The specification describes a solids-liquids separation apparatus which includes a rotatable cylindrical drum where flow movement of process liquid is provided from a first level of fluid contained within the drum to a higher in elevation level outside the drum.
This feature is provided by a series of internal bailers contained within the drum structure.

Description

~L~55~

~l--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.

Field of Invention 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 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 ~ZSS~;~9 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 ~2~S~

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.

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.

33 ~RIEF DESCRIPTION OF THE DRAWINGS

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 ~2~5~0~

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;

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;

19 Figure 6 is a view of the drum,~aken on lines 6-6 of Figure 5;

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 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;

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.
~7 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 ~55~13g 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 ~5 5 60 9 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.

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.
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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.

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.

~25~
g 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.

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.

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.

Claims (5)

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

1. A paper pulp washer, comprising a wash drum having a generally cylindrical side wall through which liquid can pass to the interior of the drum and having end closure walls, said drum being mounted for rotation about its horizontal axis, a filter belt trained over a portion of the exterior of said side wall to hold a mat of solid material to be washed, a fluid sump formed at the lower horizontal confines of said rotatable drum, means for passing wash fluid through said mat and into said sump, a drum outlet connected to at least one end of said drum and located above said sump, and bailer scoop means disposed within said drum and mounted for rotation with said drum and into the sump in a first portion of a rotary cycle, said bailer scoop means including baffle means forming a horizontal fluid holding trough when said baffle means has a vertical ascending directional component and laterally flowing and discharging fluid from said trough and into said drum outlet in a second portion of said rotary cycle, said trough including a bottom wall sloped toward said drum outlet.

2. The washer of claim 1, in which said drum outlet comprises an open fluid conveying hub at the rotative axis of the drum.

3. The washer of claim 1, in which said baffle means extends from one edge of said bailer scoop means to the other edge and terminates with one edge of said baffle means in flow communication with said hub.

4. The washer of claim 1, wherein said baffle means includes a longitudinal extending baffle and a longitudially extending pickup means fixed to said baffle and extending in juxtaposed clearance with the inner peripheral surface of said drum to form with said baffle, said fluid holding trough, said baffle being a conical member with its apex extending toward and in flow communication with said drum outlet.

5. The washer of claim 1, in which said baffle means includes a longitudinally extending baffle and a longitudinally extending pickup means fixed to said baffle and extending in juxtaposed clearance with the inner peripheral surface of said drum to form with said baffle said fluid holding trough, said baffle being a pyramidal member with its apex extending toward and in flow communication with said drum outlet.