Note: Descriptions are shown in the official language in which they were submitted.
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T 5059
SWIRL TUBE SEPARATOR
The present invention relates to a swirl tube
separator for the separation of solids from a mixture
of fluid and solids.
The separation of solids from a mixture of fluid
and solid particles using a swirl tube separator is
based on different centrifugal forces acting on the
fluid and the solids of the swirling mixture.
USA patent specification No. 2 890 764 discloses a
swirl tube separator for separating solids from a
mixture of fluid and solids, the separator comprising:
- a housing having a cylindrical mid section;
- an inlet opening for the mixture arranged near a
first end of the housing;
- a solids outlet opening arranged near a second end
of the housing;
- a fluid outlet conduit being arranged
concentrically within the housing, said outlet conduit
comprising a small diameter section, a large diameter
section and a frustoconical section for interconnecting
the small diameter section and the large diameter
section, the small diameter section having a free end
which is in direct fluid communication with the
interior of the housing and the large diameter section
extending through said first end of the housing; and
- a swirl zone which extends, when the separator is
being used, through the interior of the housing from
near the inlet opening to a location near the solids
outlet opening.
The lower end of the fluid outlet conduit
coincides with the lower end of the swirl zone.
As can be seen in Figures 10 and 14 of the prior
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art document the ratlo of the dlstance from sald free end of the
small dlameter sectlon of the fluid outlet condult to the location
to whlch the swlrl zone extends and the lnner dlameter of the
cyllndrlcal mld sectlon of the houslng ls much less than 1.
Appllcants have now found that the separatlon efflclency
of a swirl tube separator can be lmproved by selecting a larger
ratio between sald dlmenslons.
Accordlngly, it ls an ob~ect of the present lnventlon to
provlde a swirl tube separator having a higher separation
efflclency than the known separator.
To thls end the swlrl tube separator accordlng to the
lnventlon ls characterlzed ln that the speclflc dlstance from sald
free end of the small dlameter sectlon of the fluid outlet condult
to sald locatlon near the sollds outlet openlng to whlch the swirl
zone extends is between 1.0 and 3.0, the specific length of the
large dlameter sectlon of the fluld outlet condult ls between 1.0
and 1.4 and the speclflc length of the lnlet part of the houslng
ls between 0.50 and 0.70.
Here the speclflc dlstance ls referred to as the ratlo
of the above-mentloned distance to the lnner dlameter of the
cyllndrlcal mid sectlon of the houslng.
Herelnafter ln the speclflcation and in the claims the
expressions "specific distance", "specific length" and "speciflc
inner diameter" are used to refer to the ratio of said distance,
length and lnner dlameter to the inner diameter of the cyllndrlcal
mld sectlon of the houslng.
The lnventlon wlll now be descrlbed by way of example ln
more detall wlth reference to the accompanylng drawings, wherein:
B
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Flgure 1, shows schematically a cross-sectlon of the
swirl tube separator according to the lnventlon; and
Flgure 2, shows schematlcally a cross-sectlon of an
alternatlve swlrl tube separator accordlng to the lnventlon.
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Reference is made to Figure 1. The swirl tube
separator comprises a housing 1 having an inlet part 3
at its upper end and a solids outlet opening 5 at its
lower end part. The inlet part 3 is in communication
with an inlet opening 9.
An open-ended fluid outlet conduit 11 extends
concentrically into the housing 1. The lower end of the
fluid outlet conduit 11 is arranged between the inlet
part 3 and the solids outlet opening 5. The fluid
outlet conduit 11 comprises a large diameter section in
the form of a primary section 13, a downwardly tapering
frustoconical section 15 joined to the lower end of the
primary section 13, and a small diameter section in the
form of a secondary section 17 joined to the lower end
of the frustoconical section 15. The largest inner
diameter of the frustoconical section 15 is equal to
the inner diameter of the primary section 13 and the
smallest inner diameter of the frustoconical section 15
is equal to the inner diameter of the secondary section
17.
Swirl imparting means in the form of swirl vanes
19 are arranged in the inlet part 3 and between the
inner wall of the housing 1 and the outer wall of the
primary section 13 of the fluid outlet conduit 11.
A swirl zone 20 extends in the housing 1 between
the swirl imparting means in the form of swirl vanes 19
and the solids outlet opening 5.
During normal operation a mixture of gas and solid
particles is introduced into the inlet part 3 through
inlet opening 9. The mixture flows downwardly between
the inner wall of the housing 1 and the outer wall of
the primary section 13 of the fluid outlet conduit 11,
and passes the swirl vanes 19, which swirl vanes 19
impart a swirl to the mixture. The swirling mixture
forms a vortex in the swirl zone 20.
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The swirling solid particles in the mixture are
flung towards the inner wall of the housing 1 by the
centrifugal forces acting on them. At the inner wall of
the housing 1 the solid particles flow downwardly by
gravitational forces. The solid particles are
discharged from the swirl zone 20 through the solids
outlet opening 5.
The gas in the vortex is withdrawn from the swirl
zone 20 through the fluid outlet conduit 11.
The alternative swirl tube separator shown in
Figure 2 is additionally provided with a vortex
stabilizer 21 arranged at or near the solids outlet
opening 5. The vortex stabilizer 21 comprises a vortex
stabilizer plate 23 arranged perpendicular to the
central longitudinal axis of the housing 1, and a
vortex finder rod 25 arranged parallel to the central
longitudinal axis of the housing 1 and extending in the
direction of the fluid outlet conduit 11.
Normal operation of the alternative swirl tube
separator is similar to normal operation of the swirl
tube separator with reference to Figure 1. The function
of the vortex stabilizer is to stabilize the vortex in
the housing 1 and to delimit the lower end of the
vortex.
The inlet part 3 of the housing 1 may alter-
natively be provided with swirl imparting means in the
form of a tangential inlet (not shown).
Normal operation of a swirl tube separator
provided with a tangential inlet is similar to normal
operation of the swirl tube separator provided with
swirl vanes 19.
The swirl tube separator according to the
invention is similarly operated when a mixture of
liquid and solid particles is introduced into the inlet
part 3.
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It has been found that the discharge of solid
particles through the fluid outlet conduit can be
further reduced by choosing the dimensions of the swirl
tube separator according to each of the following
specifications: the specific length of the secondary
section 17 of the fluid outlet conduit 11 to be between
0.25 and 1.0, the specific length of the frustoconical
section 15 of the fluid outlet conduit 11 to be between
0.20 and 0.30, the specific inner diameter of the
lo secondary section 17 of the fluid outlet conduit 11 to
be between 0.20 and 0.40, the specific inner diameter
of the primary section 13 of the fluid outlet conduit
11 to be between 0.55 and 0.75, the specific length of
the primary section 13 of the fluid outlet conduit 11
to be between 1.0 and 1.4, and the specific length of
the inlet part 3 to be between 0.50 and 0.70.
The following experiments 1-3 have been carried
out to illustrate the swirl tube separator according to
the invention.
The expression "swirl number" is used to refer to
the ratio of the tangential component of the mixture
velocity to the axial component of the mixture
velocity.
Experiment 1
The swirl tube separator used in experiment 1 had
the following characteristics: specific distance
between lower ends of the fluid outlet conduit and the
swirl zone = 2.18, specific length of the secondary
section of the fluid outlet conduit = 0.57, specific
length of the frustoconical section of the fluid outlet
conduit = 0.26, specific length of the primary section
of the fluid outlet conduit = 1.21, specific length of
the inlet part = 0.60, specific inner diameter of the
secondary section of the fluid outlet conduit = 0.38,
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specific inner diameter of the primary section of the
fluid outlet conduit = 0.65.
A mixture of gas and solid particles was supplied
to the inlet part of the cylindrical housing. The gas
had a density of 1.23 kg/m3 and the pressure difference
between the gas at the inlet part and in the fluid
outlet conduit was 1930 Pa. The swirl number of the
mixture in the swirl zone near the swirl imparting
means was 1.73. The mixture contained 0.092 kg/m3 solid
particles having a mean diameter of 14 ~m. As a result
it was found that 99.63% of the solid particles was
discharged through the solids outlet opening and 0.37%
through the fluid outlet conduit.
Experiment 2
The swirl tube separator used in experiment 2 had
the following characteristics: specific distance
between lower ends of the fluid outlet conduit and the
swirl zone = 2.43, specific length of the secondary
section of the fluid outlet conduit = 0.31, specific
length of the frustoconical section of the fluid outlet
conduit = 0.26, specific length of the primary section
of the fluid outlet conduit = 1.21, specific length of
the inlet part = 0.60, specific inner diameter of the
secondary section of the fluid outlet conduit = 0.38,
specific inner diameter of the primary section of the
fluid outlet conduit = 0.65. A mixture of gas and solid
particles was supplied to the inlet part of the
cylindrical housing. The gas had a density of 1.23
kg/m3 and the pressure difference between the gas at
the inlet part and in the fluid outlet conduit was 2000
Pa. The swirl number of the mixture in the swirl zone
near the swirl imparting means was 1.73. The mixture
contained 0.092 kg/m3 solid particles having a mean
diameter of 14 ~m. As a result it was found that 99.47%
of the solid particles was discharged through the
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solids outlet opening and 0.53% through the fluid
outlet conduit.
Experiment 3
The swirl tube separator used in experiment 3 had
the following characteristics: specific distance
between lower ends of the fluid outlet conduit and the
swirl zone = 1.96, specific length of the secondary
section of the fluid outlet conduit = 0.78, specific
length of the frustoconical section of the fluid outlet
0 conduit = 0.26, specific length of the primary section
of the fluid outlet conduit = 1.21, specific length of
the inlet part = 0.60, specific inner diameter of the
secondary section of the fluid outlet conduit = 0.38,
specific inner diameter of the primary section of the
fluid outlet conduit = 0.65.
A mixture of gas and solid particles was supplied
to the inlet part of the cylindrical housing. The gas
had a density of 1.23 kg/m3 and the pressure difference
between the gas at the inlet part and in the fluid
outlet conduit was 1980 Pa. The swirl number of the
mixture in the swirl zone near the swirl imparting
means was 1.73. The mixture contained 0.093 kg/m3 solid
particles having a mean diameter of 14 ~m. As a result
it was found that 99.57% of the solid particles was
discharged through the solids outlet opening and 0.43
through the fluid outlet conduit.
The following experiments 4-6 have been carried
out as comparison.
Experiment 4
The swirl tube separator used in experiment 4 had
the following characteristics: specific distance
between lower ends of the fluid outlet conduit and the
swirl zone = 1.53, specific length of the secondary
section of the fluid outlet conduit = 1.21, specific
length of the frustoconical section of the fluid outlet
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conduit = 0.26, specific length of the primary section
of the fluid outlet conduit = 1.21, specific length of
the inlet part = 0.60, specific inner diameter of the
secondary section of the fluid outlet conduit = 0.38,
specific inner diameter of the primary section of the
fluid outlet conduit = 0.6S.
A mixture of gas and solid particles was supplied
to the inlet part of the cylindrical housing. The gas
had a density of 1.23 kg/m3 and the pressure difference
~0 between the gas at the inlet part and in the fluid
outlet conduit was 1920 Pa. The swirl number of the
mixture in the swirl zone near the swirl imparting
means was 1.73. The mixture contained 0.095 kg/m3 solid
particles having a mean diameter of 14 ~m. As a result
~5 it was found that 99.49% of the solid particles was
discharged through the solids outlet opening and 0.51%
through the fluid outlet conduit.
Experiment 5
The swirl tube separator used in experiment 5 had
the following characteristics: specific distance
between lower ends of the fluid outlet conduit and the
swirl zone = 1.86, specific length of the secondary
section of the fluid outlet conduit = 0.56, specific
length of the frustoconical section of the fluid outlet
conduit = 0.56, specific length of the primary section
of the fluid outlet conduit = 1.21, specific length of
the inlet part = 0.60, specific inner diameter of the
secondary section of the fluid outlet conduit = 0.38,
specific inner diameter of the primary section of the
fluid outlet conduit = 0.65.
A mixture of gas and solid particles was supplied
to the inlet part of the cylindrical housing. The gas
had a density of 1.23 kg/m3 and the pressure difference
between the gas at the inlet part and in the fluid
outlet conduit was 1830 Pa. The swirl number of the
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mixture in the swirl zone near the swirl imparting
means was 1.73. The mixture contained 0.093 kg/m3 solid
particles having a mean diameter of 14 ~m. As a result
it was found that 99.53% of the solid particles was
discharged through the solids outlet opening and 0.47%
through the fluid outlet conduit.
Experiment 6
The swirl tube separator used in experiment 6 had
the following characteristics: specific distance
between lower ends of the fluid outlet conduit and the
swirl zone = 1.74, specific length of the secondary
section of the fluid outlet conduit = 1.07, specific
length of the frustoconical section of the fluid outlet
conduit = 0.26, specific length of the primary section
of the fluid outlet conduit = 1.21, specific length of
the inlet part = 0.60, specific inner diameter of the
secondary section of the fluid outlet conduit = 0.46,
specific inner diameter of the primary section of the
fluid outlet conduit = 0.65.
A mixture of gas and solid particles was supplied
to the inlet part of the cylindrical housing. The gas
had a density of 1.23 kg/m3 and the pressure difference
between the gas at the inlet part and at the fluid
outlet conduit was 1260 Pa. The swirl number of the
mixture in the swirl zone near the swirl imparting
means was 1.73. The mixture contained 0.093 kg/m3 solid
particles having a mean diameter of 14 ~m. As a result
it was found that 98.92% of the solid particles was
discharged through the solids outlet opening and 1.08%
through the fluid outlet conduit.
