Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR SEPARATING GASEOUS COMPONENTS FROM
POURABLE MEDIA AND DEVICE AND INSTALLATION THEREFOR
The invention relates to a process, a device, and an installation using this
device
for the separation of gaseous components from pourable media, in particular
suspensions of solids.
Processes and devices for the separation of gases from liquids, suspensions
and
liquid-material-gas-mixtures lmown so far operate on the principle of a
centrifuge.
Here the medium to lie separated from the gas must be set in rotation, the
heavier
components being enriched at longer radii because of stronger centrifugal
forces
and the gases and more volatile components mainly at shorter radii and at the
center of rotation, rf;spectively. The gas concentrated at shorter radii is
then
evacuated from the. system via an appropriate conduit. In most cases
underpressure is applied to the extraction system for the evacuation of gas.
Centrifugal systems of that kind are described in the applicant's Austrian
Patent
No. 392,216, in U.S. Patent No. 4,326,863 and U.S. Patent No. 4,410,337 and
operate with a central rotor carrying mostly rectangular and planar blades or
ledges for energy supply running parallel to its axis. According to Austrian
Patent
No. 392,216 a cage rotor and a substantially central, upwardly directed axial
gas
discharge pipe are provided. According to U.S. Patent No. 4,326,863 the gas is
evacuated in an upward direction through the 'hollow rotor itself having
radial
openings, and according to U.S. Patent No. 4,410,337 in a downward direction
through a hollow rotor, the rotor having radial passages and being terminated
by a
disk at its bottom, from which the ribs run upwardly and which has passages
for
the evacuation of gas corresponding to the internal cavity of the rotor.
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A disadvantage of such processes is that energy has to be introduced into the
medium for generating swirl, which energy is completely or partly lost in the
further course of the process.
A further disadvantage residua in the fact that complicated control is often
necessary in order to avoid that a large amount of gas, in particular air, but
no
other components are separated. This applies in particular when varying
amounts
of gas occur in the medium to t>e degassed during operation.
Conventional processes are furthermore disadvantageous in that additional
devices
aiming at a stabilization of the spout-like gas separation are necessary for
efficient
operation.
With media and liquid-material-gas-mixtures, respectively, as for instance the
suspensions of fibrous material occurnng in paper and pulp industry, the
gaseous
components (mostly air) adhere well to the fiber network, thus making the
segregation of gaseous and non-gaseous components (water, fibers, etc.) more
difficult. In these cases, it is of major importance to keep the distance the
gas has
to travel inside the medium in order to reach the zone from where it may be
evacuated as short as possible. The result thereof is that with known
processes
long dwelling times of the medium in the region of the centrifuge are
necessary
because of the long travel distances, and thus the throughput of the medium is
strongly limited or the centrifu;;e becomes very long.
A further disadvantage of kno~Nn processes and devices resides in the fact
that, in
order to prevent the concomitant separation of non-gaseous components,
provision
has to be made for devices functioning as a sieve. Especially with media
likely to
form clots, as for instance thf; fiber suspensions dominating the paper and
pulp
industry, the components carried along with the evacuated gas may result in
clogging. Rinsing means are necessary in order to prevent this.
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The present invention avoids the above disadvantages. For this purpose it
proposes a process which is cr~aracterized in that underpressure zones are
formed
by relative movement between the media and a body, in particular a rotary
body,
arranged within these; media, as a result of the shape thereof and in that the
gas
accumulating in the underpressure zones is evacuated via the interior of the
body.
The effect of centrifugal force is employed for separating gaseous components
from the medium. Advantageously according to the invention the medium
enriched with gas, entering the interior of the body together with accumulated
gas,
is subject to further degassing by centrifugal force inside the body.
Conveniently the medium del;assed inside the body is recycled to the medium
surrounding the body.
The relative movement between the body and the medium may be achieved by
moving the body or the medium, but also by simultaneously moving the body and
the medium.
Advantageously according to ~:he invention the relative movement is achieved
by
preferably continuous rotation of the body.
Conveniently according to th~~ invention the relative movement is achieved by
preferably continuous rotation of the body and movement, preferably for
conveyance of the medium.
In industrial processes quite frequently media of varying composition, for
instance
due to changing pressure and temperature conditions, are to be subjected to a
treatment. In order to optimize the separation of gas from medium of varying
composition, according to the invention the relative speed is adjusted by
changing
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the speed of movement of the body and/or the medium, in particular in
dependence of the state parameters of the medium to be degassed.
Conveniently according to the invention the direction of flow of gas inside
the
body is changed by deviating it.
Underpressure is applied in order to promote the separation of gas from the
medium. Advantageously according to the invention the gas separated from the
medium is removed from ~:he interior of the body under application of
underpressure.
Conveniently according to the invention the underpressure applied is adjusted
in
dependence on the state param~;ters of the medium to be degassed.
The invention also relates to a device for separating gaseous components from
pourable media, in particular f ~r carrying out the process according to the
present
application.
The invention is characterized primarily in that the device for generating
relative
movement is disposed between the media and a body arranged within these media,
which body is in particular provided rotatably and has a shape generating
underpressure on the surface of the body in the course of this relative
movement,
and in that the body has at least one inlet in the region of the underpressure
zones,
which inlet communicates with. a gas discharge for transporting off separated
gas.
According to an advantageous; embodiment of the invention the body takes the
form of a rotary body and the ;;as discharge has at least on through-channel
in the
body and open in the region of the radially outer circumference.
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Conveniently according to thf; invention the channel open in the region of the
radially outer circumference discharges into an enlarged cavity, preferably in
the
region of the radially outer circumference.
Advantageously according to the invention the channel open in the region of
the
radially outer circumference communicates with a further channel, optionally
via
an enlarged cavity.
Conveniently according to the invention the body has several arms.
Advantageously according to the invention several arms are arranged in one
plane.
According to the present invention it may also be convenient for the arms to
be
arranged in at least two planes with respect to the rotational axis,
preferably above
each other.
Conveniently according to the invention the gas discharge opens into a
collecting
channel. -
According to an advantageous embodiment of the invention the gas discharge
communicates with a gas evacuation device, in particular a suction device,
preferably via the collecting channel.
In order to promote the evacuation of gas from the medium the body of
appropriate shape is moved. .According to an advantageous embodiment of the
invention the body and the arms, respectively, is/are connected to a drive
device,
in particular to a drive shaft.
Conveniently according to the invention the collecting channel is arranged in
the
drive shaft. Preferably according to the invention the collecting channel is
arranged between hub and shah;.
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The configuration of the entrar.~ce opening on the body exerts a major
influence on
the efficiency of the separation of gas from the medium. Conveniently
according
to the invention at least one inlet is of circular cross section. Preferably
at least
one such inlet is formed as a bore.
Conveniently according to the present invention several such bores are, at
least
substantially in a radial direction, arranged adjacent to each other on the
body.
According to the present invention it is also advantageous for several such
bores to
be arranged adjacent to each other on the body, at least substantially in
parallel to
the rotational axis.
According to a preferable embodiment of the invention at least one inlet takes
the
form of a slot. Conveniently the at least one slot-like inlet is oriented in
the radial
direction.
Preferably according to the irmention the at least one inlet has a cross
section
widening in the direction towards the interior of the body, preferably in a
continuous fashion.
According to an advantageous embodiment of the invention at least one
additional
profile being oriented at least substantially in parallel to the rotational
axis is
provided in the region of the radially outer circumference.
The invention also relates to an installation using the device for separating
gaseous
components from pourable media, in particular solid suspensions, described
above. Conveniently according to the invention the device is arranged within a
housing. According to another advantageous embodiment of the invention the
device is arranged ire a channel, in particular a pipe, a bent and a curved
pipe,
respectively.
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Conveniently according to the invention the device is arranged in an oblique
position in the housing and channel, respectively.
Advantageously accarding to i:he invention the device is arranged in an
eccentric
position in the housing and channel, respectively.
According to an advantageous embodiment of the invention the device is
arranged
downstream of a container and protrudes at least partly from the housing and
channel, respectively, into the container.
Conveniently according to th~~ invention the device is arranged upstream of a
pump.
Advantageously according to the present invention the device is directly
connected
to the shaft of the pump. According to a preferably embodiment of the
invention
the device takes the form of a ~~ump rotor vane.
The invention will naw be described by way of the exemplary embodiments in the
drawings, wherein
Fig. 1 shows a side view of a dwice according to the invention,
Fig. 2 shows a plan view in direction B according to Fig. 1,
Fig. 2a shows a plan 'view of a further device according to the invention,
Fig. 3 shows section .A-A according to Fig. 1 as well as flow lines of the
medium,
Figs. 3a and 4a show a plan view of a device according to the invention with
flow
lines shown,
CA 02117055 2000-08-09
Figs. 4b to 11 show side vif;ws of diverse variants of the type and place of
positioning of suction openings,
Fig. 12 shows a side view of a variant of the invention having additional
elements
for generating a centrifugal effi;ct,
Figs. 13 to 15 show side views of variants of the assemblage of the device in
an
installation,
Figs. 16 and 17 show vertical ;sections of variants of the device directly
connected
to a pump shaft,
Figs. 18 and 19 show side viems of variants for arranging the device upstream
of a
pump,
Fig. 20 shows a side view of a variant for discontinuous use of the device,
Fig. 21 shows a side view ilh~strating the incorporation of the device in a
pump
rotor vane, and
Fig. 22 shows section C-C according to Fig. 21.
Fig. 1 shows a side view of a device according to the invention which
essentially
consists of a body 1 having arms 2 extending radially outwards, each of which
is
provided with channels 3 and 4, an inlet 5 and a cavity 6 opening outwardly,
so
that there is a connection to space 13 where the medium to be degassed is
located.
The suction opening or inlet > connects space 13 to channel 4, which is in
turn
connected to cavity 6. Channel 3 connects cavity 6 to the suction conduit or
collecting channel 7. Body 1 is connected to a drive shaft 9, so that the
whole
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device rotates in direction 20 :in a housing 12 the medium may enter through
an
opening 10 and from which the medium may exit through an opening 11.
Fig. 2 shows a plan view of the device, similar parts being indicated with the
corresponding reference numerals according to Fig. 1. An embodiment having
three arms 2 is shown in plan view in Fig. 2a.
Section A-A according to Fig. t is shown in Fig. 3. Fig. 3a shows a plan view
of a
device according to the invention, this figure giving, on the one hand, media
flows
and, on the other hand, important operation and device parameters. With
reference to these figures the process is to be explained in more detail now.
Rotation of the device generates a relative speed R between the medium to be
degassed and the arrr~s 2. The medium now flows around arms 2 in direction 19,
generating underpressure zone ~ 8 having a pressure p3 in certain locations of
the
arms 2 and in its surroundings, where the gas or gas-enriched medium
accumulates because of its low specific density. The relative speed R is
chosen so
that it results in a sufficient pressure difference (pl-p3) to cause the
separation of
gas. Here the relative speed R is determined by the number of revolutions n as
well as the radial dimensions yll, r2, r3, 13, 14), the number of revolutions
being
higher than a minimum value of about 200 - 300 rpm. The gas or gas mixture
accumulated in the underpressure zones 8 subsequently, via inlet 5, enters
channel
4 and furthermore cavity 6. Pressure p2 prevailing in collecting channel 7 is
set so
that it is lower than pressure p3 of underpressure zones 8. In this cavity 6,
due to
the higher centrifugal force prevailing there, the gas or gas-enriched medium
is
effectively completely separat~,d from non-gaseous components possibly
present.
The separated components are; again recycled to the medium flow through the
outer end of cavity 6. The purified gas enters the collecting channel 7 via
channel
3. With appropriate design of the device and choice of operation parameters
(e.g.
number of revolutions, underyressure) no control is necessary during
operation.
This results in high safety of operation even with highly varying operating
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conditions and markedly di:Eferent compositions of the liquid-material-gas-
mixture.
Advantageously inlet S is forrr.~ed so that it results in the evacuation of
gas over a
certain area by a large radial extension and thus keeps the distance the gas
has to
cover in the mediurrc in order to reach the zone of suction short. With media
which are difficult to degas the distance may be kept correspondingly short by
increasing the number of revolutions n in order to achieve effective degassing
anyhow.
The separation of non-gaseous components from the gas by differing centrifugal
forces of the components caused by the differences in density takes place in
cavity
6. Separation is effected at a distance 14 from the center of rotation. The
forced
dislocation of the process of separation to a relatively large distance 14
from the
center of rotation as compared to known processes with the formation of spouts
near the center of rotation resu:~ts in extremely good separation of the
components.
The (solid and liquid) components separated from the gas are recycled to the
medium via the cavity 6 open towards the outside. The gas is redirected and
evacuated from the device v-ia channel 3 and collecting channel 7. For the
functioning of the de;vice wherein the gas is redirected there is a lower
limit of
dimension r2-13 or cavity 6. This is, on the one hand, determined by the fact
that
the medium enters the cavity E~ because of the pressure difference pl-p2
(external
pressure of the medium minus pressure in collecting channel 7). Due to the
rotation a counterpressure is generated by the centrifugal forces until a
penetration
depth of the medium of 11-lq has been reached, where a pressure equilibrium
comes about. On the other hand, the cross sectional area of the cavity 6
between
14 and 13 is to be kept so large that the gas may unrestrictedly pass from
channel
4 to channel 3.
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The pressure drop from outer space 13 via cavity 6 into channel 3 or 7 may be
promoted by appropriately forming the outer contour 14 of body l and arms 2,
respectively, if, for instance, the outer contour 14 takes such a form that
the radial
extension of arms 2 decreases in the direction opposite the direction of
rotation,
thus creating an unde:rpressure zone 8 in this region. Because of the
underpressure
zone 8 the medium cannot penetrate into the cavity 6 as deeply as this would
be
the case with a cylindrical outer contour 14.
Thus with this process, even in case of varying operating conditions, no
control
activities are necessary; instesad, effective degassing of the medium at high
operating reliability takes place because of the practically delay-free
procedure
even in case of highly unsteady operating conditions. Even in the extreme case
of
the medium being completely free of gas no non-gaseous components may get out
of the system if the dimensions and operative parameters are chosen
appropriately.
In this case the medium flows into channel 4 via inlet 5 and returns to the
outer
space 13 via cavity 6.
The medium is conveyed by appropriately shaping the arms 2 and angles a and
~3,
receptively, with respect to the; rotational axis. The angles a and [3,
respectively,
are chosen in dependence on the amount of throughput of medium to be degassed,
the number of revolutions, and the desired conveyance behaviour, and with one
embodiment of the rotor vane Type may differ as to the radius. Ordinarily
angle a
>_ ~3.
The cross section of inlet 5 arid its course, respectively, may be different.
Thus
Fig. 4a in plan view and Fig. 41~ in side view, respectively, show a slot-like
inlet 5,
extending over the total length of arm 2. Fig. 4a again shows the individual
media
flows (liquid-material-gas-mixture, gas, non-gaseous components). By way of
example Fig. 5 shoves diverse configurations of inlet S, these being
employable
alone as well as in combination. It illustrates bores 5' arranged near shaft 9
and
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ending, on the one hand, in a channel 4 and, on the other hand, in a cavity 6.
Furthermore slot-like openings 5" are shown, the direction of which is
tangential
to the direction of movement and in any oblique arrangement thereto,
respectively,
this choice depending on the material parameters of the medium and the other
operating conditions. If the non-gaseous components may be separated easily,
channels 3 and 4 may be short as shown in Fig. 5 or a single cavity may
perform
the function of channels 3, 4 arid of cavity 6 (Fig. 6). The cross section of
inlets 5,
having the form of bores in Fi;;. 6, increases in the direction of cavity 3,
4, 6 and
this is how clogging by non-ga;~eous components carried along is prevented.
In case of minor amounts of ~;as to be separated the cavity 6 may also be very
small (Fig. 7). Also, as shown in Fig. 8, channels 3 and 4 may be directly
connected via opening 3'. Fig, 8 furthermore shows a variant of how to form
the
collecting channel 7, which in this case surrounds shaft 9 as an annular gap.
Fig. 9 and the plan view thereof in Fig. 10 show an embodiment with media that
are difficult to degas or large amounts of gas to be evacuated. Here body 1 is
provided with additional porticns 2' or 2" having openings 5' and 5",
respectively,
(shown as bores hc;re, but also possible in slot-like configuration), which
communicate with cavity 6 via channels 4' and 4", respectively, or optionally
via a
channel 4.
Fig. 11 shows a further embod invent of the device having an additional
portion 2"'
and a channel 4"', suction from the underpressure zone 8 taking place via
inlets 5.
Fig. 12 illustrates a variant of tile device according to the invention,
combining the
process according to the invention with the known processes employing
centrifugal effect. Elements l 5 are provided here, which are able to degas
the
medium in the outer peripheral region up to about rl according to the
principle of
a centrifuge. Appropriate portions 16 may be provided for stiffening purposes.
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The advantage of this embodiment resides in the fact that the length of the
construction is considerably shortened as compared to known devices and that
no
gas separation has to take place within the area of rl. Thus the distance to
be
covered by the gas to be separated is considerably reduced. The elements for
stabilizing the spout as well as the necessity for elaborate control may be
dispensed with as well. The individual gas velocity components are illustrated
here as well, namely in axial direction the same speed as medium c 1, in
radial
direction component: c2 dep~;nding on the medium to be degassed and the
operative parameters, and the velocity component c3 resulting therefrom in the
direction of the center of rotation. Because of the evacuation of gas over a
certain
area inside radius r l the otherwise necessary length of a centrifuge of 12 is
reduced to 11. As no spout-like gas separation near the center of rotation has
to be
done, no elements for. the stabilization thereof are necessary either. Because
of the
efficient separating function, the sieves or the like used so far may be
dispensed
with as well.
Figs. 13 to 15 show various an-angements of the device according to the
invention
in a housing 12 which is ordinarily disposed below a container to be
evacuated.
Fig. 13 differs from Fig. 14 in that in Fig. 13 the device is completely
contained in
the housing 12, while the device of Fig. 14 protrudes at least partly into the
container arranged thereabove.
Fig. 15 shows the arrangement of the device in housing 12 with an oblique
shaft 9.
In Figs. 16 and 17 the device is directly connected with the shaft 9 of a pump
arranged downstream thereof, the collecting channel 7 in Fig. 16 being
provided
centrally in the shaft 9 and sucked off via an annular chamber 17. By
contrast, in
Fig. 17 suction takes place via an annular gap 7'.
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Figs. 18 and 19 show arrangements of the device in a housing 12 to which pump
18 is directly connected.
If a liquid-material-gas-mixture is to be degassed discontinuously, an
arrangement
according to Fig. 20 is used.
Fig. 21 shows an embodiment wherein the device is directly integrated into the
pump rotor vane. Fig. 22 show ~ a section C-C according to Fig. 21.
Basically body 1 of the device may also take a form so as to achieve a
conveying
effect on the medium.
The illustrated embodiments of the invention only serve as examples and may be
modified by one skilled in the ~~rt within the scope of the claims
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