US3928186A

US3928186A - Combined pulp cleaning system including high and low pressure drop hydrocyclone cleaners

Info

Publication number: US3928186A
Application number: US382068A
Authority: US
Inventors: Rudolf Zemanek
Original assignee: Boise Cascade Corp
Current assignee: Officemax Inc
Priority date: 1973-07-24
Filing date: 1973-07-24
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: CA1021723A; SE7409573L; FR2238534B1; BR7406050D0; JPS5070962A; SE403634B; JPS5431230B2; DE2435416A1; SE7703200L; FI223974A7; GB1482113A; FR2238534A1; SE423729B; DE2435416B2

Abstract

A method and apparatus for effecting low-pressure separation from a suspension of reclaimed wastepaper of both cellulose pulp fibers and light impurity particles having a specific gravity less than that of the pulp fibers, characterized by the use of a wastepaper cleaner operable in the low-pressure hydrocyclone mode to deposit the heavier pulp fibers at the bottom of a chamber and to establish an upward flow of the lighter particles in a vertical vortex in the central portion of the chamber. The invention also includes a method and apparatus for separating the cellulose pulp fibers from a reclaimed wastepaper suspension by a combined high-pressure drop low-pressure drop separation process, use being made of a high-pressure drop hydrocyclone separator that is connected in unitized construction with the low-pressure wastepaper cleaner. Finally, an improved waste-paper cleaning system is disclosed including in combination with the highpressure drop low-pressure drop separator a further low-pressure wastepaper cleaner for effecting second-stage cleaning of the lighter separated impurity particles, and a further hydrocyclone separator for effecting second-stage cleaning of the heavier separated impurity particles.

Description

United States Patent 1191 1111 3,928,186

Zemanek Dec. 23, 1975 COMBINED PULP CLEANING SYSTEM INCLUDING I-IIGH AND LOW PRESSURE Primary Examiner-Frank W. Lutter DROP HYDROCYCLONE CLEANERS Assistant ExaminerRalph J. Hill [75] Inventor: Rudolf Zemanek, Vancouver, Wash. Attorney Agent or Firm-Lawrence Laubscher [73] Assignee: Boise Cascade Corporation, Boise, [57] ABSTRACT Idaho A method and apparatus for effecting low-pressure [22] Filed: July 24, 1973 separation from a suspension of reclaimed wastepaper of both cellulose pulp fibers and light impurity parti- 1 PP 332,068 cles hav ng a specific gravity less than that of the pulp 1 1 fibers, characterized by the use of a ,wastepaper 52 11.5. C1. 209/211 919999 P9table the WV-Pressure hydmcychne 51 Int. (:1. 1304c 5/103 mode 9 the heavier P fibers at the b99919 5 Fidd f s 209011. 210/512 R 512 M of a chamber and to establish an upward flow of the 210/84; lighter particles in a vertical vortex in the central portion of the chamber. The invention also includes a [56] References Cited method and apparatus for separating the cellulose UNITED STATES PATENTS pulp fibers from a reclaimed wastepaper suspenslon by a comb1nedh1gh-pressure drop lowpressure drop sep- 2,377,524 6/1945 I Samson et all. 209/211 aration s u b i ad f a high-pressure 3:333:33; 3/132? 52213111111111?" 111111 51132 35,; 9 11999191109989.9999 that is inimit- 2.s43,26s 7/1958 Rakowsky ..209/211x constructo the bwpressure wastepaper cleaner. Finally, ,an improved waste-paper cleaning 209/211 X 210/84 X system 1s d1sclosed including 1n combmation with the 209/211 X high-pressure drop low-pressure drop separator a fur- 209/168 X ther low-pressure wastepaper cleaner for effecting se- 209/211 cond-stage cleaning of the lighter separated impurity u 209/211 particle's, and afurther hydrocyclone separator for ef- 210/512 R fecting second-stage cleaning of the heavier separated 2,849,930 9/1958 Freeman et al. 3,052,361 9/1962 Whatley et a1 3,425,545 2/ 1969 Zemanek et al.. 3,428,175 2/ 1969 l-lukk i 3,486,619 12/1969 Grundelius et al. 3,543,932 12/1970 Rastatter 3,696,934 10/1972 Oisi 3.747.757 7/1973 Kalthoffetal.... 209/211 i ufi 1 .385 9/1973 Pouillon 209/168 x mp ty Pa 3,764,005 1011973 Zemanek 209 211 9 Claims, 5 Drawing Figures Light Porticti Impurity Rejects Pulp Fiber Accepts US. Patent Dec.23,1975 Sheet1of3 3,928,186

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US. Patent Dec. 23, 1975 Sheet 3 of 3 3,928,186

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commcwawsw $303525 35 mm (among others), hydrocyclone apparatus for separating particles of different specific gravities from. a paper pulpsuspension are'well known in the art. More particularly, these knownhydrocyclone separators are suitable for separating-from a suspension impurity particles having a specifiogravity that is greater than that of the cellulosepulp. In order to remove particles of impurities having a specific gravity less than that of the cellulose pulp fibers,-it has been proposed to use separating screens which are efficient inremoving only the large and spherical-plastic particles, since the smaller and flat particles pass readily through the screen openings (holesor slots);. .The conventional hydrocyclone is incapable of removingsynthetic plastic material, or materials suchzasink, hot melt or thelike. j

i The present, invention is based on the concept of removing: the-lighter particles from the wastepaper suspension by a lowpressure process.

Accordingly, the primary object of the present invention is toprovide a low-pressure wastepapercleaner method and apparatus for separating from a reclaimed wastepaper suspension both the cellulose .pulp fibers and the lighterimpurity particles having a specific gravity less than that of the pulp fibers.The suspension is introduced at relatively low pressure (on the order of 5 psig) tangentially intothe upper end of a low-pressure drop hydrocyclone chamber having an outlet at its lower end through which are discharged the heavier pulp fibers that are thrown centrifugally outwardly and travel downwardly in the chamber in a helical path. The lighter impurity particles are displaced radially inwardly .in the chamber and engage an upwardly convergent" conical diverter that establishes an upward vortex flow centrally within the chamber, whereby the lighter impurity particles may be dispensed via an outletvthat communicates with the upper end of the chamber. i

A further objectof the present invention is to provide a high-pressure drop low-pressure drop method and apparatus for separating in three fractions from a reclaimed wastepaper suspension the cellulose, pulp fibers, heavy impurity particles having a specific gravity greater than that of the pulp fibers, and light impurity particles'l aying a specific gravity lower than that of the pulp fibers. To this end, a high-pressure drop hydrocyclone iscij eeted colinearly in spaced relation below the aforementioned low-pressure drop wastepaper cleaner, an "intermediate housing being rigidly connected, between the high-pressure hydrocyclone cleaner and the'low-pressure dropwastepaper cleaner 10 define .a ni taryrigid separator having separate outlets for' fdis'cliarging the cellulose pulp fibers, the light impurity particles and the heavy impurity particles, 'res'pecti'v'elyff Another'objec tof the present invention is to provide an improved system for'acc'urately separating the pulp fibers and the light and heavy impurity particles from a reclaimed wastepaper cleaner suspension, character- 'ized in that-the'light particle outlet of the high-pressure drop low-pressure dropseparator is connected with a second-stage low-pressure wastepaper cleaner which supplies at its upper outlet the final light particle rejects and returns from its lower outlet to the original suspensionvtank the suspension which includes reclaimable cellulose pulp fibers. Furthermore, the heavy rejects discharged from the lower outlet of the high-pressure drop low-pressure drop separator may be fed to the inlet of a further hydrocyclone separator (such as the two-body separator of theaforementioned Zemanek application Serial No. 117,566) for separation into the final heavy particle rejects and a suspension containing the cellulose pulp fibers that is returned to the original suspension supply tank and/or the heavy particle reject tank associated with the-high-pressure drop low-pressure drop cleaner.

Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawing, in which: 7

FIG. 1 is a diagrammatic sectional elevational view of a cylindrical embodiment of the low-pressure drop wastepaper cleaner of the present invention;

FIG. 2 is a diagrammatic sectional elevational view of a modification of the wastepaper cleaner of FIG. 1 wherein the lowerportion of the housing is conical;

FIG. 3 is a diagrammatic sectional elevational view of a high-pressure'drop low-pressure drop separator apparatus that incorporates the operating principles of the wastepaper cleaner of FIG. 1;

FIG. 4 is a detailed view of a modification of the apparatus of FIG..3; and

FIG. 5 is an improved wastepaper cleaning system that includes the wastepaper cleaner of FIG. 1 and the high-pressure drop low-pressure drop separator apparatus of FIG. 3.

Referring first more particularly to FIG. 1, the wastepaper cleaner is operable to separate from the cellulose pulp fibers of a wastepaper pulp suspension the lighter impurity particles of materials such as synthetic plastics, ink, adhesives, hot melt particles and the like. Use is made of a cylindrical housing 2 containing a low pressure drop-chamber 4, an inlet 6 for introducing the suspension tangentially into the upper end of the chamber, and first and

second outlets

8 and 10 arranged centrally in the bottom and top walls of the chamber, respectively. Mounted within the bottom opening 8 is a diverter means 12 including a tubular bottom portion 12a upon the upper portion of which is supported a conical upwardly convergent portion 12b. As illustrated in the drawing, the conical portion is supported by the tubular bottom portion at an elevation greater than that of the outlet opening. The cylindrical portion contains a tangential discharge slot 12c for the discharge of material from the chamber 4 into the diverter chamber 12d, and discharge conduit 14 communicates with the lower'end of the diverter chamber. Throttle valve 16connected in the conduit 14 affords means for regulating the back pressure in

chambers

12d and 4. Mounted in the second outlet l0v is a baffle 18 the lower end of which extends to a level below that of the inlet 6, thereby to partially isolate the second outlet -10 from the inlet 6.

' In" operation, the wastepaper suspension is supplied-at a relatively low pressure (on the order of 5 psig) and a relatively low flow ratetangentially into the upper end of the chamber 4 via inlet 6. As the suspension flows downwardly in the chamber 4 toward the outlet 8, the heavier cellulose pulp fibers are thrown centrifugally outwardly and travel downwardly in a helical path adjacent the chamber side wall, whereupon at the bottom of the chamber the pulp fiber-liquid carrier suspension flows through the discharge slot 120, and helically downwardly in the diverter chamber 12d and the discharge conduit 14. Owing to the centrifugal helical flow of the heavier cellulose pulp fibers the lighter impurity particles are displaced inwardly of the chamber 4 and engage the conical diverter surface 12b, whereupon an upwardly directed low-pressure vortex flow of the lighter impurity particles is established in the central portion of the chamber and outwardly therefrom via the second outlet 10.

It has been found in practice that owing to the lowpressure upward movement of particles within the central portion of the housing, there are removed by the low pressure central vortex not only the lighter impurity particles but also relatively fine particles of higher specific gravity which are not separated by centrifugal force. Preferably the outlet pressure of discharge conduit 16 is atmosphere, whereby a relatively low-pressure drop of about psig is achieved.

In the modification of FIG. 2, the housing 2' includes a cylindrical upper portion 2a and a conical downwardly convergent lower portion 2b, thereby to effect a slightly greater acceleration of the heavier pulp fibers adjacent the bottom portion of the chamber. The structure and operation of this embodiment is otherwise similar to that of FIG. 1, like parts being identified by primed reference numerals.

Referring now to the high-pressure drop low-pressure drop embodiment of FIG. 3, a reclaimed wastepaper suspension containing cellulose pulp fibers and heavy and light impurity particles having specific gravities greater and less than that of therpulp fibers, respectively, is supplied at a relatively high pressure (on the order of -50 psig) to a high-pressure drop downwardly convergent conical hydrocyclone chamber 24 contained within the lower portion 22a of the housing 22. The suspension is introduced tangentially into the hydrocyclone chamber via inlet 26, whereupon the suspension flows downwardly in the chamber toward the first outlet 28. Owing to centrifugal force, the heavier impurity particles assume a downward helical path adjacent the wall surface of the chamber 24 and are discharged via the first outlet 28. The cellulose pulp fibers and the lighter impurity particles are displaced radially upwardly in the chamber 24 and assume an upward vortex flow for discharge via baffle 29 and a second discharge opening 20 contained in the upper end wall of chamber 24. The discharge pressure is approximately 5 psig, whereupon the pressure drop between the inlet and outlets of the hydrocyclone separator is about 25 to 45 psig for inlet pressures of 30 to 50 psig, respectively.

The low-pressure suspension of cellulose pulp fibers and lighter impurity particles is introduced into a cylindrical intermediate chamber 34 contained in an intermediate portion 22b of the housing, the side wall portion of said intermediate chamber containing an outlet 36 which communicates via conduit 38 with the inlet 106 of the low-pressure chamber 104 contained in the upper portion 220 of the housing 22. The upper housing portion 220 contains a first outlet 108 that communicates with the bottom portion of the chamber 104, and a second outlet 110 centrally arranged in the upper wall of the chamber. Arranged in the bottom of the chamber are diverter means 112 including a cylindrical lower portion 112a and an upwardly convergent conical portion 112b. Discharge conduit 114 containing throttle valve 116 communicates with the first outlet 108, and arranged in the second outlet is the baffle means 118 having a tubular lower portion 118a that extends downwardly in the chamber 104 at least to the level of the inlet 106, thereby to isolate the second outlet from the inlet.

As the suspension introduced via inlet 106 flows downwardly in chamber 104 toward the outlet 108, the heavier cellulose pulp fibers are thrown centrifugally outwardly toward the wall of the chamber and pass downwardly in a helical path for discharge via outlet 108. The lighter impurity particles are displaced inwardly and engage the conical diverter portion 112b, whereupon a vortex flow of the lighter impurity particles is established upwardly in the central portion of the chamber 104 toward the outlet 110 for discharge via the opening 120 contained in the upper end wall 118b of the baffle means.

Consequently, it is apparent that the high-pressure drop low-pressure drop apparatus of FIG. 3 is operable by a single unitary construction to separate from the initial reclaimed wastepaper suspension heavy impurity particles at outlet 28, light impurity particles at outlet 120, and acceptable cellulose pulp fibers at outlet 1 14. The back pressure of chamber 104 (and, to a certain extent, the back pressures of chambers 34 and 24) may be controlled by appropriate adjustment of throttle valve 116.

As shown in the modification of FIG. 4, in the event that the suspension contains a certain degree of air, the second outlet 120' is arranged in the side wall of the baffle and an air outlet 122 is provided in the upper end wall 118b of the baffle. Consequently, air is readily separated from the suspension adjacent the light particle outlet.

The wastepaper cleaner and high-pressure drop lowpressure drop components are particularly suitable for use in the improved wastepaper cleaning system illustrated in FIG. 5. The reclaimed wastepaper suspension-which has a 0.30.7% concentration and includes cellulose pulp fibers, heavy impurity particles having a specific gravity higher than that of the pulp fibers, and light impurity particles having a specific gravity lower than that of the pulp fibers--is introduced in the supply tank and is pumped by pump 152 at a relatively high pressure (30-50 psig) to the inlet 226 of the high-pressure drop chamber 224 contained in the lower portion 222a of the housing 222 of the highpressure drop low-pressure drop separator 222. The heavy impurity particles are deposited into tank 154 via outlet 228 and are pumped by pump 156 to the inlet 158 of the two-body separator apparatus 160 (which apparatus is disclosed in detail in the Zemanek application Ser. No. 117,566). The separator 160 serves as a second-stage device including a first outlet 162 for supplying the final heavy impurity particles, a second outlet 164 for returning to the supply tank 150 a first suspension of a lighter portion of the heavy impurity particles (which possibly includes redeemable cellulose pulp fibers), and a third outlet 166 which returns to the heavy reject tank 154 a second suspension of a heavier portion of the heavy impurity particles (which possibly includes a small quantity of redeemable pulp fibers) third .outlet 166 to the heavy particle reject tank 154.

The low-pressure upper wastepaper cleaner portion 2220 of the combined high-pressure drop low-pressure drop separator 222 serves to provide the acceptable cellulose pulp fibers via first outlet 308 and discharge conduit 314, and the light impurity particle rejects are supplied to tank 170 via the second outlet 320. These rejects are pumped by pump 172 at a relatively low pressure (about 5 psig) to the inlet 406 of the low-pressure drop wastepaper cleaner 402, which apparatus serves as a second stage separator for the light impurity particles. Final light particle rejects are supplied via watepaper cleaner outlet 410, and the suspension produced at outlet 408 (which may include some acceptable cellulose pulp fibers) is returned to the supply tank 150.

While the improved system of FIG. 5 has been disclosed with regard to the separation of impurities from reclaimed wastepaper stock, it is apparent that the system has utility in many other applications, such as the cleaning of virgin pulp or paper stock ahead of a paper machine. 1

Although in accordance with the PatentStatutes the preferred form and embodiments of the invention has been disclosed, it will be apparent that various modifications may be made without deviating from my inventive concept.

What is claimed is:

l. The method of separating from a reclaimed wastepaper suspension the cellulose pulp fibers and heavy and light particles of impurities having specific gravities greater and less, respectively, than that of the pulp fibers, which comprises the steps of I a. supplying the suspension tangentially at a pressure of about 30-50 psig. into the upper end of a highpressure centrifugal hydrocyclone separator chamber;

b. withdrawing the heavy impurity particle rejects from the bottom of the high-pressure chamber, whereby a vertical vortex of light impurity particles and pulp fibers is formed in the center of the highpressure chamber;

0. withdrawing from the upper end of the high-pressure chamber the second suspension including the pulp fibers and the light impurity particles;

d. supplying the second suspension at a pressure of about 5 psig. tangentially into the upper end of a low-pressure hydrocyclone chamber;

e. withdrawing from the bottom of the low-pressure chamber a third suspension including the pulp fibers that flow helically downwardly adjacent the wall of the low-pressure chamber, whereby the light particles are displaced radially inwardly and downwardly in the low-pressure chamber;

f. diverting the light particles upwardly to form a vortex flow thereof in the central portion of the low-pressure chamber; and

g. withdrawing from the top of the low-pressure chamber a fourth suspension including the light impurity particles.

2. The method as defined in claim 1, and further including the steps of h. supplying the fourth suspension tangentially at a pressure of about 5 psig. to the upper end of a second low-pressure chamber;

i. withdrawing from the bottom of the second lowpressure chamber the suspension including reclaimable pulp fibers and returning this suspension to the original suspension; and

j. withdrawing from the upper end of the second low-pressure chamber the final light impurity particles.

3. The method as recited in claim 2, and further including the'steps of k. feeding a suspension including the heavy impurity particles discharged from the high-pressure centrifugal hydrocyclone chamber to the upper end of a second high-pressure centrifugal hydrocyclone chamber;

1. withdrawing final heavy impurity particles from the lower end of the second hydrocyclone chamber; and

m. returning to the suspension source of at least one of he high-pressure hydrocyclone chambers from the upper end of the second high-pressure hydrocyclone chamber the suspension which includes reclaimable cellulose pulp fibers.

4. Low-pressure drop apparatus for separating from a liquid suspension cellulose pulp fibers and particles of impurities having a specific gravity less than that of the cellulose pulp fibers, comprising a. means for supplying said suspension under pressure;

b. a housing having top, bottom and side walls defining a vertical hydrocyclone chamber, said housing being cylindrical and having a uniform diameter throughout its length,

l. the upper portion of said housing side wall containing an inlet opening connected with said suspension supply means for supplying said suspension tangentially into the upper end of said chamber;

2. the lower end of said housing containing a first outlet opening;

3. the central portion of the upper end of said housing containing a second outlet opening;

. upwardly convergent conical diverter means centrally mounted on the bottom wall of said vertical hydrocyclone chamber, said diverter means including an upwardly convergent conical diverter member, and cylindrical support means supporting said conical diverter member a given distance above said housing bottom wall and above said first outlet opening, said cylindrical support means having an outer diameter which correponds with the maximum diameter of said conical diverter member; and

d. tubular baffle means connected with the central portion of the housing top wall and communicating at its upper end with the second outlet opening, the lower end of said baffle means extending downwardly in said chamber to a level slightly below that of said inlet opening;

e. the pressure of said suspension supply means being such as to establish a pressure difference of about 5 psig. between said inlet opening and said firstoutlet opening, whereby the pulp fibers are separated from the suspension by centrifugal force and pass downwardly in the chamber in an outer helical path adjacent the side wall surface of the chamber for discharge via said first outlet, said diverter means establishing in the central portion of the chamber within the outer helical path an upwardly directed small helical vortex flow of the impurity particles of the suspension for discharge via said second outlet opening.

5. Combined high-pressure-drop low-presure-drop apparatus for separating from a liquid suspension cellulose pulp fibers, and first and second groups of impurities having specific gravities greater than and less than that of said pulp fibers, respectively, comprising a. means for supplying said suspension under pressure; 7

b. a unitary housing including a lower portion containing a vertically arranged downwardly convergent conical high-pressure-drop hydrocyclone separation chamber, an upper portion containing a vertically arranged generally cylindrical low-pressure-drop separation chamber, and a middle portion containing an intermediate chamber,

1. the upper side wall portion of said lower chamber containing a first inlet connected with said suspension supply means for supplying said suspension tangentially into said lower chamber;

2. the lower end of said lower chamber containing a first outlet;

3. the central portion of the upper end of said lower chamber containing a second outlet;

4. the central lower portion of said intermediate chamber containing a second inlet communicating with said second outlet;

5. the side wall portion of said intermediate chamber containing a third outlet;

6. the upper side wall portion of said upper chamber containing a third inlet connected with said third outlet for introducing the suspension tangentially into the upper end of said upper chamber;

7. the lower side wall portion of said upper chamber containing a fourth outlet; and 8. the top wall portion of said upper chamber containing a fifth outlet; and c. upwardly convergent conical diverter means centrally mounted on the bottom wall of said chamber, said diverter means including an upwardly convergent conical diverter member, and means supporting saiddiverter member a given distance above,

said housing bottom wall, whereby in said lower chamber the first group of impurities is separated from said suspension by centrifugal force for discharge via said first outlet, the remaining pulp fiber particles and second group of impurities having an upwardly directed vortex flow within said lower chamber fortangential introduction into said upper chamber via said second outlet, said second inlet, said intermediate chamber, said thirdo'utlet and said third inlet, whereby the pulpfibers a'res'eparated -by centrifugal force from said suspension in said upper chamber for discharge .via said fourth outlet, and said diverter means cause said second group of particles to form an upwardly directed vortex in the central portion of saidupper chamber for dischargevia said fifth outlet. 6. Apparatus as defined in claim 5, wherein said fourth outlet is connected with atmosphere and said suspension supply means has a pressure of about 30 to 50 psig, said lower chamber having a discharge pressure at said second outlet of about psig.

7. Apparatus as defined in claim 5, and further including second-stage heavy particle hydrocyclone separator means for recleaning the heavy impurity particles discharged from first outlet, said second-stage separator means being of the two-body type including a conical housing which is divided into upper and lower chambers by a horizontal baffle, said separator means including a fourth inlet for introducing the heavy particles from said first outlet tangentially into the upper end of the upper chamber of said second-stage separator, a sixth outlet (162) for discharging the final heavy rejects from the lower end of the lower chamber of said second-stage separator, a seventh outlet (166) for returning to the heavy particle rejects discharged from the first outlet the lighter impurity particles that are displaced upwardly in the central portion of said lower chamber, and an eighth outlet (164) for returning to the first inlet the lighter particles that are directed upwardly in the central portion of said upper chamber.

8. Apparatus as defined in claim 5, and further including light particle second-stage separator means for recleaning the light impurity particles discharged from 'said fifth outlet, said light particle second-stage separator means comprising a second housing containing a chamber and having at its upper end a fifth inlet for tangentially introducing into the chamber the lighter particles to be cleaned, a ninth outlet at its lower end for returning to the first inlet the heavier particles separated in said second housing, and a tenth outlet for discharging from the upper central portion of said second housing the final light rejects.

9. The method of separating from a suspension cellulose pulp fibers, and particles of impurities having a specific gravity lower than that of the pulp fibers, which comprises the steps of a. introducing the suspension tangentially into an inlet opening arranged at the upper end of a totally cylindrical hydrocyclone chamber, said chamber having at its lower end a pulp fiber outlet opening and at its upper end a light impurity particle outlet opening, said suspension being introduced into said chamber at a pressure producing a pressure drop of about 5 psig. whereby the heavier pulp fiber particles are centrifugally displaced outwardly and flow downwardly in a helical path toward the bottom of l the hydrocyclone chamber and wherein the lighter particles are displaced radially inwardly and downwardly in the chamber;

b. diverting the light impurity particles upwardly in a vortex toward the upper end of the hydrocyclone chamber by means of a conical diverter supported above the bottom wall of the chamber at an elevation above the pulp fiber outlet opening by means of a cylindrical support member having an outer diameter which corresponds with the maximum diameter of the conical diverter;

c. removing the pulp fibers adjacent the bottom of the chamber; and

d. removing the light impurity particles from the top of the chamber.

Claims

1. the upper portion of said housing side wall containing an inlet opening connected with said suspension supply means for supplying said suspension tangentially into the upper end of said chamber;

1. The method of separating from a reclaimed wastepaper suspension the cellulose pulp fibers and heavy and light particles of impurities having specific gravities greater and less, respectively, than that of the pulp fibers, which comprises the steps of a. supplying the suspension tangentially at a pressure of about 30-50 psig. into the upper end of a high-pressure centrifugal hydrocyclone separator chamber; b. withdrawing the heavy impurity particle rejects from the bottom of the high-pressure chamber, whereby a vertical vortex of light impurity particles and pulp fibers is formed in the center of the high-pressure chamber; c. withdrawing from the upper end of the high-pressure chamber the second suspension including the pulp fibers and the light impurity particles; d. supplying the second suspension at a pressure of about 5 psig. tangentially into the upper end of a low-pressure hydrocyclone chamber; e. withdrawing from the bottom of the low-pressure chamber a third suspension including the pulp fibers that flow helically downwardly adjacent the wall of the low-pressure chamber, whereby the light particles are displaced radially inwardly and downwardly in the low-pressure chamber; f. diverting the light particles upwardly to form a vortex flow thereof in the central portion of the low-pressure chamber; and g. withdrawing from the top of the low-pressure chamber a fourth suspension including the light impurity particles.

2. The method as defined in claim 1, and further including the steps of h. supplying the fourth suspension tangentially at a pressure of about 5 psig. to the upper end of a second low-pressure chamber; i. withdrawing from the bottom of the second low-pressure chamber the suspension including reclaimable pulp fibers and returning this suspension to the original suspension; and j. withdrawing from the upper end of the second low-pressure chamber the final light impurity particles.

2. the lower end of said housing containing a first outlet opening;

2. the lower end of said lower chamber containing a first outlet;

3. the central portion of the upper end of said housing containing a second outlet opening; c. upwardly convergent conical diverter means centrally mounted on the bottom wall of said vertical hydrocyclone chamber, said diverter means including an upwardly convergent conical diverter member, and cylindrical support means supporting said conical diverter member a given distance above said housing bottom wall and above said first outlet opening, said cylindrical support means having an outer diameter which correponds with the maximum diameter of said conical diverter member; and d. tubular baffle means connected with the central portion of the housing top wall and communicating at its upper end with the second outlet opening, the lower end of said baffle means extending downwardly in said chamber to a level slightly below that of said inlet opening; e. the pressure of said suspension supply means being such as to establish a pressure difference of about 5 psig. between said inlet opening and said first outlet opening, whereby the pulp fibers are separated from the suspension by centrifugal force and pass downwardly in the chamber in an outer helical path adjacent the side wall surface of the chamber for discharge via said first outlet, said diverter means establishing in the central portion of the chamber within the outer helical path an upwardly directed small helical vortex flow of the impurity particles of the suspension for discharge via said second outlet opening.

3. The method as recited in claim 2, and further including the steps of k. feeding a suspension including the heavy impurity particles discharged from the high-pressure centrifugal hydrocyclone chamber to the upper end of a second high-pressure centrifugal hydrocyclone chamber; l. withdrawing final heavy impurity particles from the lower end of the second hydrocyclone chamber; and m. returnIng to the suspension source of at least one of the high-pressure hydrocyclone chambers from the upper end of the second high-pressure hydrocyclone chamber the suspension which includes reclaimable cellulose pulp fibers.

4. Low-pressure drop apparatus for separating from a liquid suspension cellulose pulp fibers and particles of impurities having a specific gravity less than that of the cellulose pulp fibers, comprising a. means for supplying said suspension under pressure; b. a housing having top, bottom and side walls defining a vertical hydrocyclone chamber, said housing being cylindrical and having a uniform diameter throughout its length,

5. Combined high-pressure-drop low-presure-drop apparatus for separating from a liquid suspension cellulose pulp fibers, and first and second groups of impurities having specific gravities greater than and less than that of said pulp fibers, respectively, comprising a. means for supplying said suspension under pressure; b. a unitary housing including a lower portion containing a vertically arranged downwardly convergent conical high-pressure-drop hydrocyclone separation chamber, an upper portion containing a vertically arranged generally cylindrical low-pressure-drop separation chamber, and a middle portion containing an intermediate chamber,

6. Apparatus as defined in claim 5, wherein said fourth outlet is connected with atmosphere and said suspension supply means has a pressure of about 30 to 50 psig, said lower chamber having a discharge pressure at said second outlet of about 5 psig.

7. the lower side wall portion of said upper chamber containing a fourth outlet; and

8. Apparatus as defined in claim 5, and further including light particle second-stage separator means for recleaning the light impurity particles discharged from said fifth outlet, said light particle second-stage separator means comprising a second housing containing a chamber and having at its upper end a fifth inlet for tangentially introducing into the chamber the lighter particles to be cleaned, a ninth outlet at its lower end for returning to the first inlet the heavier particles separated in said second housing, and a tenth outlet for discharging from the upper central portion of said second housing the final light rejects.

8. the top wall portion of said upper chamber coNtaining a fifth outlet; and c. upwardly convergent conical diverter means centrally mounted on the bottom wall of said chamber, said diverter means including an upwardly convergent conical diverter member, and means supporting said diverter member a given distance above said housing bottom wall, whereby in said lower chamber the first group of impurities is separated from said suspension by centrifugal force for discharge via said first outlet, the remaining pulp fiber particles and second group of impurities having an upwardly directed vortex flow within said lower chamber for tangential introduction into said upper chamber via said second outlet, said second inlet, said intermediate chamber, said third outlet and said third inlet, whereby the pulp fibers are separated by centrifugal force from said suspension in said upper chamber for discharge via said fourth outlet, and said diverter means cause said second group of particles to form an upwardly directed vortex in the central portion of said upper chamber for discharge via said fifth outlet.

9. THE METHOD OF SEPARATING FROM A SUSPENSION CELLULOSE PULP FIBERS, AND PARTICLES OF IMPURITIES HAVING A SPECIFIC GRAVITY LOWER THAN THAT OF THE PULP FIBERS, WHICH COMPRISES THE STEPS OF A. INTRODUCING THE SUSPENSION TANGENTIALLY INTO AN INLET OPENING ARRANGED AT THE UPPER END OF A TOTALLY CYLINDRICAL HYDROCYCLONE CHAMBER, SAID CHAMBER HAVING AT ITS LOWER END A PULP FIBER OUTLET OPENING AND AT ITS UPPER END A LIGHT IMPURITY PARTICLE OUTLET OPENING, SAID SUSPENSION BEING INTRODUCED INTO SAID CHAMBER AT A PRESSURE PRODUCING A PRESSURE DROP OF ABOUT 5 PSIG. WHEREBY THE HEAVIER PULP FIBER PARTICLES ARE CENTRIFUGALLY DISPLACE OUTWARDLY AND FLOW DOWNWARDLY IN A HELICAL PATH TOWARD THE BOTTOM OF THE HYDROCYCLONE CHAMBER AND WHEREIN THE LIGHTER PARTICLES ARE DISPLACED RADICALLY INWARDLY AND DOWNWARDLY IN THE CHAMBER; B. DIVERTING THE LIGHT IMPURITY PARTICLES UPWARDLY IN A VOTEX TOWARD THE UPPER END OF THE HYDROCYCLONE CHAMBER BY MEANS OF A CONICAL DIVERTER SUPPORTED ABOVE THE BOTTOM WALL OF THE CHAMBER AT AN ELEVATION ABOVE THE PULP FIBER OUTLET OPENING BY MEANS OF A CYLINDRICAL SUPPORT MEMBER HAVING AN OUTER DIAMETER WHICH CORRESPONDS WITH THE MAXIUM DIAMETER OF THE CONICAL DIVERTER; C. REMOVING THE PULP FIBER ADJACENT THE BOTTOM OF THE CHAMBER; AND D. REMOVING THE LIGHT IMPURITY PARTICLES FROM THE TOP OF THE CHAMBER.