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Патент USA US3037637

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June 5, 1962
Filed June 22 ,
G. H. TOMLINSON ll
APPARATUS FOR SEPARATING DIRT FROM AQUEOUS
3,037,628
SUSPENSIONS OF PULP FIBERS
1953
3 Sheets-Sheet 1
612%27225725022 JI
June 5, 1962
3,037,628
G. H. TOMLINSON n
APPARATUS FOR SEPARATING DIRT FROM A QUEOUS
SUSPENSIONS OF‘ PULP FIBERS
Filed June 22, 1953
3 Sheets-Sheet 2
55
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June .5, 1962
G. H. TOMLINSON n
3,037,628
APPARATUS FOR SEPARATING DIRT FROM AQUEOUS
SUSPENSIONS 0F‘ PULP FIBERS
Filed June 22, 1953
5 Sheets-Sheet 5
61
ice
_
3,037,628
Patented June 5, 1962
2
the ?bre width, of the order of about 10 times, and in
order to prevent plugging and matting relatively low con
sistencies are used, the ?nal stock having a consistency of
3,037,628
APPARATUS FOR SEPARATING DIRT FROM
AQUEOUS SUE‘aPENSiONS OF PULP FIBERS
0.3 to 0.4%.
George H. Tomlinson II, Cornwall, Ontario, Canada, as
signor to Dominion Tar and Chemical (10., Montreal,
Quebec, Canada, a corporation of Canada
Filed June 22, 1953, Ser. No. 363,277
Inasmuch as screens are not completely
selective in their action, multiple screening is often used,
but in spite of this, some shive will carry through. By
cooking the pulp by relatively drastic means the quantity
of initial shive is diminished, and in bleaching, further
6 Claims. (Cl. 209—Z11)
“chemical cleaning” of shive is obtained due to removal
In addition to
This invention relates to a new and e?icient method 10 of lignin which binds the ?bres together.
and apparatus for cleaning an aqueous suspension of pulp
or paper-making ?bres whereby objectionable foreign ma
“chemical cleaning,” mechanical attrition is also obtained,
this resulting ‘from the action in pumps through the pulp
mill, and particularly in the beater, jordan or other re?n
ing equipment in the paper mill whereby many of the
terial including that usually referred to as “dirt" is re
moved by means of combined centrifugal and shear action
in a device which can be classed as a vortex type separator. 15 individual ?bres are torn apart.
By a balance of multiple
screening with chemical and mechanical de?bring it is pos
The present application is a continuation-in-part of my
co-pending application Serial No. 205,655, ?led January
sible to control shive content in the ?nal ?ne paper to a
12, 1951, now abandoned.
reasonably low level, with the chemical cleaning normally
In the conversion of wood or other ?brous material to
acting as the control point—that is, the amount of chem
pulp and paper three main classes of foreign matter and 20 ical or temperature or time at the cooking or bleaching
“dirt” must be considered.
stages is increased when the shive count appears to be un
(1) Portions of the wood which have not completely
reasonably high at any point along the system; this nor
mally results in lower pulp yields and sometimes in ex
broken down into individual ?bres as a result of the chem
ical and/ or mechanical action. A particle of such mate
rial may ‘be relatively large such as an unde?bred chip or
knot, but when broken down to size such as might be
cessive degradation in pulp.
The control of “bark dirt” is an even more serious prob
lem. Whereas the shive is normally somewhat longer
than it is wide this enhancing its chance of being rejected
embedded in a sheet of paper it is referred to as a “shive.”
(2) Pieces of bark which do not disintegrate in cook
ing and remain as black or dark colorured specks in the
?nal pulp.
(3) Foreign matter of non-?brous origin that enters the
by the screen, bark dirt tends to be random in shape, ap
proaching a sphere. Moreover, it is less susceptible to
Thus conventionally, to obtain a ?ne paper
free of bark dirt, it is necessary to take extra precautions
30 bleaching out.
system with the wood or at any subsequent stage, this in
with the wood used. This means recycling of logs through
cluding sand, pipe-scale, fly-ash, cinders, etc.
the barking drums to remove all traces of adhering bark.
Dirt particles can of course be present in a considerable
range of sizes. With regard to the minimum size of ma
terial referred to as “dirt” the Technical Association of
However, logs contain ingrown bark around knots, etc.,
the Pulp and Paper Industry (frequently referred to as
“TAPPI”) has given (Standard T213) the following de?
nition: “Dirt in pulp is de?ned as any foreign matter which
is embedded in a sheet, which has a marked contrasting
colour to the rest of the sheet when viewed by re?ected
and many mills resort to treatment with “rossers,” “wood
peckers,” etc., to remove both wood and bark around the
most seriously affected areas. When the wood, even after
such drastic cleaning, is chipped, it is found that the
chipper dust contains considerable bark fragments, and
a fraction passing a 1A; inch mesh, which amounts to
about 1% to. 3% of the wood, is normally screened off
light and which has an equivalent area of 0.08 sq. mm. or
and discarded to obtain a reduced bark speck count in the
more.” With paper (Standard T437) foreign matter in
the sheet is similarly de?ned with the exception that par
?nal pulp.
The minimization of high speci?c gravity extraneous
ticles of 0.04 sq. mm. or more are considered as “dirt.” 45
dirt is normally accomplished in three ways, namely, by
On account of the extremely divergent physical char
taking precautions to avoid its entry to the system by pro~
acter and size of the “dirt” particles that may be present
viding for thorough Washing of the logs, ?ltration of proc
many varied methods of cleaning have been devised and
ess water, etc., by rif?ing in the pulp mill, and by the use
are conventionally employed in combination in order to
of stationary centrifugal cleaning tubes in the paper mill,
obtain a ?nal product which is reasonably uncontaminated 50 all three methods usually being used in combination.
with ‘foreign materials that ‘would mar the appearance and
It is thus apparent that through direct and indirect ex
serviceability of the ?nal sheet of pulp or paper.
In the manufacture of a bleached chemical pulp, the
pense the cost involved in producing a clean sheet of pulp
or paper is extremely high. The individual conventional
relatively small percentage of non-disintegrated wood pre
means of cleaning are normally speci?c for one type
sent in the pulp, is normally partially removed by “screen 55 and/ or size of “dirt,” and even for that type and/or size
ing.” Knots and unde?bred chips are ?rst removed by pass
the e?iciency is often low, while for types and sizes of
ing the stock through perforated plates, the perforations
“dirt” other than that for which the equipment was de
being about 1A” diameter. The stock is then ?ne screened,
signed, the ef?ciency may be essentially zero.
on either ?at screens having slots about 8 to 12 mils wide
By the methods of the present invention shive, bark
or on rotary screens having perforations of about 60 mils
“dirt” and high speci?c gravity dirt can all be removed
diameter. The pulp is then bleached, passed over ri?lers
to settle out “heavy” dirt, and rescreened, usually through
simultaneously from the ?bre and, within certain wide
limitations, this is accomplished regardless of the size of
?at screens similar to those described above. In the paper
the particles. Furthermore, by the choice of certain
mill'the stock is normally screened once again and passed
dimensions of the individual cleaning units, which will
through stationary centrifugal cleaners designed to re 65 modify the flow of the separated dirt within the unit, it
move particles of high s.g. dirt which the screens and/ or
ri?iers have failed to catch.
has been found possible to extend the range in the size of
particles removed in one direction or the other as may
The diameter of a single ?bre is of the order of 1 mil
be desired.
and it might be assumed that it would be possible to use
This combination of results, which has been obtained
slots of but slightly greater width for screening purposes. 70 in a vortex type separator, has never been described as
having been accomplished by any previously available
However, from a practical standpoint it is necessary with
?at screens to have the slots many times greater than
means or device.
3,037,628
L
1%.
space 21, extending along the axis of cone section 5 within
the upward spiralling stream of clean stock passing to out
let‘ 9. The liquid seal 55 may be maintained by means of
a barometric leg from which the rejected stock will drain,
'1
It has heretofore been considered axiomatic that in a
vortex separator the smaller the diameter of the unit the
greater the centrifugal force, and therefore the greater the
separation factor that will be obtained. Unexpectedly I
have found that the separation factor can be increased by
increasing the diameter of the unit providing that the inlet
or by means of a pump ?tted with a level control on the
suction side. It has been found that, when the apparatus
of the present invention is operated in conformity with
this modi?cation, the rate of flow through the rejects dis
charge aperture 6 is approximately one-third greater than
and outlet size, the cone angle, and the pressure differ
ential are not altered. This results in increased efficiency
for the removal of all types of dirt present in pulp sus
pensions, including wood dirt, shive, etc. Unexpectedly
10 when discharged into atmosphere.
This results from a
decreased diameter of the liquid-free axial core due to its
decreased pressure, and the diameter of the aperture 6
can be adjusted to give the desired rate of rejection when
operating under these conditions. This modi?cation pre
vents entrainment of air in the accepted stock.
such a separator has a very much higher e?iciency in the
removal of shive than units having dimensions in the
same proportion but of smaller diameter even though the
latter will develop greater centrifugal force and may be
more e?icient in removing extremely small particles of a
A satisfactory method of simultaneously removing the
size not normally classed as dirt.
The different action obtained by units of different size
and proportion results not only from the centrifugal force
but also from the shear rates developed in the unit. The
ratio between these may be adjusted to obtain any given
desired result by the proper sizing and proportioning of
the dimensions of the unit as will hereinafter be described.
By the method of the present invention an aqueous
suspension of the pulp at a consistency that may be in the
range of 0.4% to 1.2% is introduced under pressure
through a pipe set tangentially to a cylinder, one end of
which is connected to the large end of a truncated cone of
about 10° to 30° contained angle having an opening of
at least one half inch at its truncated apex through which
a suspension of the concentrated dirt and a small portion 30
of the ?bre is discharged, while the cleaned pulp is dis—
charged through an outlet in axial alignment with the
apex, this outlet extending through the otherwise closed
end of the cylindrical section. The small percentage of
fibre rejected with the dirt can be subsequently reclaimed 35
as will be hereinafter described.
Proceeding now to a more detailed description of the
rejected stock from the unit and maintaining a vacuum in
the liquid-free vortex column is shown in FIGURE 1.
The cone section 5 of the separator terminates at ori?ce 6
which is centered in a vertical pipe section 56, sealed to
the cone at its upper end 57. The vertical pipe 56 is con
nected at its lower end to horizontal pipe 58 which is
sealed at one end 59 and connects at the other end to a
commercially available water ejector 60. The ejector is
actuated by water ‘under pressure through pipe 61 and
valve 62 and discharges under submergence through pipe
63 into box 64, the liquid level of which is controlled by
valve 65, through which the additional dilution water is
added. The diluted rejects in box 64 may be pumped
through pump 66 to a secondary cleaner not shown. If
desired, a vacuum line 67 may also be connected at the
upper section of the liquid-free column 21 at the top of
cleaned stock outlet pipe 9 of the vortex separator.
Vacuum line 67 may be centered on the liquid-free column
by insertion through elbow 16, which is connected to out
let pipe ‘9 through reducer 15. Vacuum line 67 may be
invention reference will be made to the accompanying
connected to any suitable source of suction. For example,
it may be connected to evacuated pipe 58 by means of
drawings wherein:
connecting piping 68. The accepted cleaned and deaerated
modi?cation of the invention whereby materials lighter
separated air will be drawn through ejector 60 and dis
charged to the atmosphere through the liquid seal in box
FIG. 1 is a fragmentary longitudinal sectional view 40 stock is delivered from elbow 16 through pipe 19 to its
point of use.
illustrating one embodiment of the present invention,
Entrained air carried in the stock through tangential
FIG. 2 is a longitudinal sectional view illustrating a
inlet pipe 8 to the vortex separator head piece 7 is im
modi?cation of the structure of the reject outlet,
mediately driven towards the centre of the unit where it
FIG. 3 is a longitudinal sectional view of the structure
carries down outlet pipe 9 to its lower end where it
at the accepted stock outlet,
passes to the liquid-free column 21. When vacuum pipe
FIG. 4 is a sectional view of a modi?cation of the
67 is used, the separated air will normally follow this
rejects outlet,
route to evacuated pipe 58, but if pipe 67 is not used,
FIG. 5 is a sectional view along the line 10-10 of
most of the separated air will follow the alternate route
FIG. 4,
down the liquid-free column to evacuated pipe 58. The
FIG. 6 is a fragmentary sectional view illustrating a
than water can be removed simultaneously with dirt of
64. It has been found that a Penberthy No. 7 ejector
when operating at an actuating water pressure of 45
high speci?c gravity.
In continuation application Serial No. 694,479, now
Patent 2,878,934, issued March 24, 1959, there is dis
pounds per square inch, this requiring 45 United States
gallons per minute, will remove the liquid and solids re
closed a separator comprising a cone section having a
tangential inlet at the upper end thereof, a rejects dis
charge outlet at the apex end and an accepted stock out
jects from a unit of 12 inches diameter with 2 inches
let at the base. There is provided a vacuum chamber in
ori?ce, while at the same time maintaining a vacuum in
the liquid-free column of 29 inches of mercury when re~
ferred to an atmospheric pressure of 29.9 inches (2.2
centimetres of mercury absolute pressure). It should
be noted that in spite of this high vacuum maintained in
diameter stock inlet and outlet and 1/2 inch rejection
communication with the apex outlet which affords a liquid
free space into which air entering through the liquid free
core is discharged together with a stream of suspension
containing dirt particles.
the liquid-free column, there is suf?cient energy in the
There is shown in FIG. 1 herein a modi?cation of the
separator disclosed in Patent 2,878,934 and it can be seen 65 rotating column of liquid leaving outlet pipe 9 to allow
that the rejected material is discharged directly into a
vacuum chamber provided by a casing 53 arranged im
mediately below the “dirt” discharge aperture 6. The
solid and liquid components of the rejects are continu
ously withdrawn from casing 53 through a drain pipe 54 70
in which a liquid seal 55 is maintained so that said casing
provides a liquid-free space into which the rejects are dis
charged from cone section 5, said space being maintained
under sub-atmospheric pressures with the result that a
suction is created in the previously mentioned liquid-free
delivery of the cleaned stock against atmospheric pres
sure or even to elevate the stock to an upper ?oor should
this be required.
If it is desired to remove dissolved air in addition to
the entrained air, the modi?cation shown in FIGURE 3
may be used. Cleaned-stock outlet pipe 9 of the vortex
separator is extended by pipe 69 into spray chamber 70
consisting of a cylindrical pipe section set at right angles
to the axis of the unit and sealed at both ends 71 and 72.
75 Spray chamber 70 is connected by line 73 to a suitable
3,037,628
5
droplets thus facilitating the removal of dissolved air by
which have a speci?c gravity less than that of Water and
thus go to the liquid~gas interface at the central liquid
free column at the axis. Curiously, when operating the
separator in the normal Way, some of this material will
be found in the rejected stock, and it is believed that this
may possibly result from such a rapid movement towards
the centre that it breaks through the surface and then
means of the vacuum. The droplets hitting the walls of
spray chamber 70 drain down and out through drain con
nection 74. It is desirable to set spra-y chamber 70 at
ever, such removal is not complete, and when such ma
terial is present in any considerable concentration, it may
vacuum pump, and stock is drawn from the evacuated
chamber by means of drain pipe 74. The lower end of
the liquid-free column is sealed from atmosphere by suit
able means. The rotational motion of the stock emerg
ing from outlet pipe '69 results in the formation of a
hollow cone spray in which the liquid is broken into small
drops by gravity through the liquid-free column. How
be desirable to provide for its positive removal. This
right angles to the axis of the cleaner, since this prevents
can be accomplished by a modi?cation of the arrange
a rotational motion in the spray chamber, which would
ment used in FIGURE 1 where pipe ‘67, replaced by pipe
otherwise submerge the outlet of pipe 69 thus preventing
‘82 of FIGURE 6, is so enlarged as to include a thin an
the formation of spray.
Since the rotational energy of the liquid leaving the 15 nulus of the tip-?owing stream, together with “?oating”
material in addition to the entrained air. In cases where
vortex-separator is dissipated in forming this spray, it is
simultaneous deaeration is not required and therefore
not possible to deliver directly to atmosphere through
Where a vacuum would not otherwise be applied, the
drain 74. When the stock is removed from spray cham
ber 70 by suitable means and vacuum is applied, then the
vortex separator can be mounted in an “upside-down”
differential across the separator is increased by approxi 20 position so that the removal of the skimmed surface liquid
through pipe 63 will be assisted by gravity. Similar pro’
mately one atmosphere as compared with the type of
vision must be made for removal of such material in the
operation previously described. Thus if the unit is set
secondary cleaner.
sufficiently high to provide a barometric leg for drain line
Having thus described the principles and several em
74-, the additional pressure required to elevate the stock
to this height is compensated for by the fact that the unit 25 bodiments of my invention which will allow the removal
of undesirable material ‘including that of both higher and
discharges into vacuum. With this arrangement, the re
lower speci?c gravity than that of water and of various
jects could also ‘be discharged through a barometric leg
as shown in FIGURE 2 and thus only the one pump hav
sizes and shapes, as well as ‘dissolved and/or entrained
ing the characteristics required for normal operation
would be required.
gases, it will be vunderstood that various modi?cations
may be resorted to within the scope and spirit of the in
vention as de?ned by the appended claims.
The embodiments of the invention in which an exclu
When the height of the building does not allow the use
of a barometric leg, a centrifugal pump ?tted with a
valve for controlling a liquid level in spray chamber 70'
just below the end of outlet pipe ‘69 must be used for re
moving the stock.
With this arrangement, the rejects
outlet may be arranged as shown in FIGURE 1.
sive property or privilege is claimed are de?ned as follows.
I claim:
1. Apparatus for de-aerat-ing an aqueous suspension of
cellulose ?bres and separating “dirt” particles therefrom
comprising“ a conical separating chamber in which the
suspension is whirled about a central axis to produce a
vortex of conical form having a central liquid-free core,
free column is shown in FIGURES 4 and 5.
Cone 5 is brought to an ori?ce diameter at outlet 6 40 a tangential inlet through which the suspension is con
tinuously fed to the larger end of said chamber to estab
which is approximately 55 to 75% of the diameter of
lish and maintain said vortex, a vacuum casing providing
the cleaned stock outlet. With a 12" diameter unit hav~
a liquid-free space into which the apex end of the sepa
ing a 10° cone, a 7.05 square inch cross section inlet and
rating chamber extends in air-tight connection with the
3" outlet, a satisfactory diameter at ori?ce 6 was found
wall structure of said vacuum chamber, yan outlet at the
to be 1.75 to 2.00 inches, with the former being pre
apex end of the separating chamber through which a
ferred. Connected to ori?ce 6 is ?aring truncated cone
An alternative method of sealing the rejection outlet
thus preventing the introduction of air through the liquid
section 75, its base dimension ‘being somewhat greater
stream of the suspension entraining “dirt” particles and
than the diameter of the cleaned stock outlet pipe, in this
a minor proportion of the cellulose ?bres is discharged
into the liquid~free space afforded by said vacuum cham
trally located solid plate 76 connected by radially extend 50 ber, a second outlet located at the larger end of the sepa
ing arms 77 to a ring member 77a. Plate 76 is of greater
rating chamber in axial alignment with said ?rst men
diameter than the ori?ce 6 having, for example, a diam
tioned outlet and through which is discharged a second
eter of 3 inches. Free access for the flow of suspension
stream of the suspension containing a major proportion
past the plate 76 is afforded by the spaces between the
of the cellulose ?bres and a suction conduit through
radially extending plate-supporting arms 77, said spaces 55 which air is withdrawn from the liquid-free core of the
being located immediately adjacent the wall of cone sec
vortex, said conduit having an end portion thereof ex
tion 75. The ring member 77a, supporting plate 76, is
tending into the end of said liquid-free core remote from
clamped between the base of cone section 75 and the base
the apex end of the separating chamber.
of a tapering reducer cone section 78 provided at its apex
2. Apparatus for de-aerating an aqueous suspension of
end with an outlet ori?ce 79. The diameter of the outlet
cellulose ?bres and separating “dirt” particles and air
of ori?ce 79 should be somewhat less than that of ori?ce
therefrom comprising a conical separating chamber in
6, in this case a diameter of 0.5 to 0.75 inch being satis
which the suspension is whirled about a central axis to
factory. Centrally located in plate 76 is a small vertical
produce a vortex of conical form having a central liquid
projection 80 which may be a bolt fastened through the
free core, a tangential inlet through which the suspension
case 4 inches.
At the base of cone section 75 is a cen
plate. This centers and stabilizes the terminal location 65 is'continuously fed to the larger end of said separating
of the liquid-free column 21 which follows down from
chamber to establish and maintain said vortex, a vacuum
cone 5 through ori?ce ‘6 to plate 76. An air column 81
casing affording a liquid-free space into which the apex
develops below plate 76 extending to the ori?ce 79, and a
end of the separating chamber extends in air-tight con
hollow cone spray discharge 11 forms.
nection with the wall structure of said vacuum casing,
With wood pulp stocks, the various types of dirt nor 70 an outlet at the apex end of said separating chamber
mally present have a speci?c gravity greater than that of
through which a stream of the suspension entraining
water and when the proper unit has been selected, will be
“dirt” particles and a minor proportion of the cellulose
carried to the cone wall and discharged through the re
?bres is discharged into the liquid-free space afforded by
jection ori?ce. However, waste paper stocks and some
said vacuum casing, means for withdrawing said suspen
rag stocks may contain pieces of gum rubber, wax, etc., 75 sion from said vacuum casing, a spray chamber affording
3,087,628
7
a liquid-free space in the upper portion thereof, a second
outlet at the larger end of the separating chamber in axial
alignment with said ?rst mentioned outlet and through
which a second whirling stream of the suspension con
taining a major proportion of the cellulose ?bres is
whirled directly through said outlet into the liquid-free
space of said spray chamber to thereby effect separation
of air including dissolved air from said second stream
of the suspension, a conduit through which the liquid
8
in the liquid-free core of the vortex in the separating
chamber, and a suction conduit having one end connected
to said ejector and the other end extending into the end of
the liquid-free core remote from the apex end of the coni
cal separating chamber.
5. Apparatus for de-aerating an aqueous suspension of
cellulose ‘?bres and separating “dirt” particles therefrom,
comprising a conical separating chamber in which the
suspension is whirled about a central axis to produce a
free space of said spray chamber is connected to a source 10 vortex of conical form having a central liquid-free core,
of suction and means for withdrawing the suspension
from said spray chamber including provision for main
taining a pool of the suspension in said spray chamber to
seal the liquid-free space therein from atmosphere.
3. Apparatus for separating “dirt” particles from an
aqueous suspension of cellulose ?bres comprising a coni
cal separating chamber in which the suspension is Whirled
about a central axis to produce a vortex of conical form
having a central liquid-free core, a tangential inlet
through which the pulp suspension is continuously fed
a tangential inlet through which the pulp suspension is
continuously fed into the larger end of said chamber to
establish and maintain said vortex, an axial outlet at the
apex end of said chamber, a vacuum chamber affording
a liquid-free space into which air entering said liquid-free
core is discharged together with a stream of the suspen
sion containing “dirt” particles and a minor proportion
of the cellulose ?bres, and a second outlet located at the
larger end of said separating chamber in axial alignment
with said ?rst-mentioned outlet and through which is dis
into the larger end of said chamber to establish and main
tain said vortex, an outlet at the apex end of said cham
charged a second stream of the suspension containing a
mission of external air thereto, said means comprising a
?aring truncated cone section open at both ends and hav
ing its apex end secured to the apex end of said chamber,
a second tapering reducing cone section of truncated form
slightly less than the diameter of said liquid-free core.
6. Apparatus for tie-aerating an aqueous suspension of
major portion of the cellulose ?bres, including an ejector
through which the suspension and air are discharged from
ber through which a portion of the suspension, entraining
said vacuum chamber, said ejector serving to maintain
“dirt” particles together with a minor proportion of the
cellulose ?bres, is continuously discharged from said 25 a vacuum in the liquid-free space of said chamber and in
the liquid-free core of the vortex in the separating cham
chamber, a second outlet at the larger end of said cham
ber and a suction conduit having one end connected to
ber in axial alignment with said ?rst mentioned outlet
said ejector and the other end extending into the end of
and through which va second stream of the suspension
the liquid-free core remote from the apex end of the
containing a major proportion of the cellulose ?bres is
continuously discharged from said chamber and means 30 conical separating chamber, said suction conduit being
centered with respect to the central longitudinal axis of
associated with the apex end of said chamber for sealing
the separating chamber and having an internal diameter
the adjacent end of the liquid-free core against the ad
having its base portion secured to the base portion of said
first mentioned truncated cone section, the opening at the
apex end of the reducing cone section being substantially
smaller than the outlet opening at the apex end of said
chamber and a solid plate-like member centered within
said cone sections and having a diameter greater than the
diameter of the opening at the apex end of said chamber,
there being flow passages provided between said plate-like
cellulose ?bres and separating “dirt” particles therefrom,
comprising a conical separating chamber in which the
suspension is Whirled about a central axis to produce a
vortex of conical form having a central liquid-free core,
a tangential inlet through which the pulp suspension is
continuously fed into the larger end of said chamber to
establish and maintain said vortex, an axial outlet at the
apex end of said chamber, a vacuum chamber affording
a liquid-free space into which air entering said liquid-free
core is discharged together with a stream of the suspen
member and said cone sections to provide for the ?ow of 45 sion containing “dirt” particles and a ‘minor proportion of
the cellulose ?bres, and a second outlet located at the larger
suspension past said plate member to and through the
end of said separating chamber in axial alignment with said
opening at the apex end of the reducing cone section.
?rst-mentioned outlet and through which is discharged at
4. Apparatus for de-aerating an aqueous suspension of
second stream of the suspension containing a major portion
cellulose ?bres and separating “dirt” particles therefrom,
comprising a conical separating chamber in which the 50 of the cellulose ?bres, including an ejector through which
the suspension and air are discharged from said vacuum
suspension is whirled about ‘a central axis to produce a
chamber, said ejector serving to maintain a vacuum in
vortex of conical form having a central liquid-free core,
the liquid-free space of said chamber and in the liquid
a tangential inlet through which the pulp suspension is
free core of the vortex in the separating chamber, and a
continuously fed into the larger end of said chamber to
establish and maintain said vortex, an axial outlet at the 55 suction conduit having one end connected to said ejector
and the other end extending into the end of the liquid
apex end of said chamber, a vacuum chamber alfording
free core remote from the apex end of the conical sepa
a liquid-free space into which air entering said liquid-free
rating chamber, said conduit being centered with respect
to the central longitudinal axis of the separating chamber
of the cellulose ?bres, and a second outlet located at the 60 and having an internal diameter greater than the diameter
of said liquid-free core.
larger end of said separating chamber in axial alignment
with said ?rst-mentioned outlet and through which is dis
References Cited in the ?le of this patent
charged a second stream of the suspension containing a
UNITED STATES PATENTS
major portion of the cellulose ?bres, including an ejector
through which the suspension and ‘air are discharged from 65 2,377,524
Samson et al ___________ __ June 5, 1945
said vacuum chamber, said ejector serving to maintain
2,571,219
De Cew ______________ __ Oct. 16, 1951
core is discharged together with a stream of the suspen
sion containing “dirt” particles and a minor proportion
a vacuum in the liquid-free space of said chamber and
2,878,934
Tomlinson ___________ __ Mar. 24, 1959
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