Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 BACKGROUND OF THE INVENTION:
The present invention relates to a method and apparatus for
separating particles from a flow by centrifugal force.
More specifically, the invention relates to a method and
apparatus for separating the specific heavier components
from a flow of a gaseous medium in which these particles are
suspended, whereby centrifugal force is employed for the
separation. The flow which includes the gas which is the
lightest component of the flow and the heavier particles
suspended therein is first diverted from a straight path into
a curved path. An eddy flow is caused by the direct contact
of the flow with the inner curvature zone of an eddy chamber
in which an eddy separation is accomplished by means of a
rotating eddy. The specific lighter component, namely the
clean gas, is sucked out centrally of the eddy chamber~ The
flow of the gas with the particles suspended therein is in-
troduced tangentially into the eddy chamber and along the en-
tire width or axial length of the eddy chamber. The removal
of the clean gas may be accomplished by two suction pipes
connected to suction fans and reaching axially and mirror-
symmetrically substantially into the centex of the eddy
chamber.
German Patent 2,160,415, inventor Ernst-August Bielefeldt
laid open to public inspection on July 5, 1973 in the Federal
Republic of Germany, discloses a method as described above.
In said German Patent the separated particles are removed tan-
gentially out of the eddy chamber by means of a partial flow
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1 which contains a partial volume of the entire gas particle
mixture. If it is necessary to collect the particles separ-
ated by such a device as disclosed in the above German Patent,
a so-called direct separator must be connected to the centri-
fugal separator downstream thereof.
British Patent 733,786 (patentee Waagner-Biro Aktiengesell-
schaft) published July 20, 1955, discloses a centrifugal type
dust separator, particularly for multi-cellular plants in
which secondary current flows are to be suppressed and in
which the ends of a dust separator cell are provided with
radially extending outputs. The input of the separator cell
extends tangentially.
U. S. Patent 474,490 (G. Walter~ patented May 10, 1892 des-
cribes a dust collector which is so arranged that the inlet
as well as the dust particle outlet extend tangentially.
The inlet and dust outlet extend over the entire axial width
of the separator chamber, however, in such a manner that the
dust is collected by gravity in a downwardly pointing dust
hopper. The intentional generation of secondary flows is not
disclosed by U. S. Patent 474,490.
OBJECTS OF THE INVENTION:
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In view of the above it is the aim of the invention to
achieve the following objects singly or in combination:
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1 to provide a method for the separation of heavier
particles from a lighter gas by centrifugal force in such a
manner that the particles are transported into a collecting
chamber substantially without the aid of a primary flow but
with the aid of a secondary flow;
to arrange the exit openings for the separated
particles in such a manner that the secondary flow will
transport the separated particles directly into such open-
ings without the aid of an external suction;
to construct a centrifugal separator in such a
manner that the exit openings for the particles are located
axially in the end walls of the separating chamber;
to operate and construct a centrifugal separator
in such a manner that its separation efficiency is comparable
to electrostatic precipitators or separators operating with
cloth filtersi and
to drive the primary circular eddy flow in the
eddy chamber at an r.p.m. of about 50,000.
SUMMARY OF THE INVENTION:
According to the invention the axially effective flow compo-
nents of the secondary flow are utilized to carry the separ-
ated particles through openings in the axial end walls of
the eddy chamber, preferably without any suction effect at
these openings. Thus, the invention provides in a surpris-
ingly simple and inexpensive manner a direct separator which
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1 may be advantageously integrated into a dust separator
system comprising a plurality of eddy chambers. Further,
the present separator may be used as a centrifuge, as a
so-called hydroseparator and so forth. The separators
according to the invention may be installed in a dust bin
or may be connected thereto. Similarly the present devices
are suitable for individual use and may be constructed in
various sizes.
The present apparatus comprises an eddy chamber which accord-
ing to the invention is provided with dust removal openings
in its axial end walls. These openings are located close
to the cylindrical wall of the chamber. In addition, the
chamber may be provided with a so-called peeling slot which
is known as such. In a further improved embodiment of the
invention a crescent shaped channel forming wall member is
installed in the eddy chamber whereby apparently secondary
flows are created on both sides of the crescent shaped separ-
ation wall which forms a flow rotating channel. Dust removal
openings are then located adjacent to the crescent shaped
wall and adjacent to the outer wall but in the axial end
walls of the eddy chamber.
BRIEF FIGURE DESCRIPTION:
In order that the invention may be clearly understood, it
will now be described, by way of example, with reference
to the accompanying drawings, wherein:
Fig. 1 is a sectional view through a separator
apparatus according to the invention along
the section line 1 - 1 in Fig. 2;
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1 Fig. 2 is a sectional view along section line 2 - 2
in Fig. l;
Fig. 3 illustrates a view similar to that of Fig. 1
however with the modification that acrescent
shaped separation wall forms two flow channels
whereby the sectional view extends along sec-
tion line 3 - 3 in Fig. 4;
Fig. 4 i5 a sectional view along section lines 4 - 4
in Fig. 3;
Fig. 5 is a view similar to that of Fig. 4, however,
illustrating staggered end walls for the
separation chamber proper;
Fig. 6 is an enlargement of the area llyl~ in Fig. 5;
and
Fig. 7 shows a sectional view similar to that of
Figs. 1 or 3, with a peeling slot in the
lateral wall of the separation chamber.
DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND
OF THE BEST MODE OF THE INVENTION:
Figs. 1 and 2 show a separator apparatus comprising a sub-
stantiaily cylindrical eddy chamber 1 formed by a curved
wall 2 and two axial end walls 15 as best seen in Fig. 2.
The eddy chamher 1 has a longitudinal central axis 1' which
extends perpendicularly to the plane of the drawing in
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1 Fig. 1. Two immersion piPes 8 extend mirror-symmetrically and
coaxially relative to said central chamber axis 1' into the
chamber as best seen in Fig. 2. Suction fans represented by
arrows Qre are operatively connected to the immersion pipes 8
for the withdrawal of the clean gas from the eddy chamber. The
inner ends of the immersion pipes 8 are spaced from each other
so that a substantially point shaped sink flow Z is formed in
the zone between the inner ends of the pipes 8. A "point shaped"
sink flow is a sink flow in which the flow lines converge toward
a point as shown in Fig. 2.
An inlet channel 12 which extends along the entire axial length
of the chamber 1 as best seen in Fig. 2, merges tangentially
into the chamber 1 as best seen in Fig. 1. According to the
invention the axial end walls 15 of the chamber 1 comprise par-
ticle discharge slots 14 which may be located near the outer
wall 2 and/or near the pipes 8. The eddy chamber 1 is, for
example, enclosed by a particle collecting housing 16 forming
with its lower end a bin or bunker 7 from which the particles
may be periodically removed, for example manually.
In operation, the flow of gas with the particles suspended
therein is forced into the inlet channel 12 as indicated by
the arrow Qro a very rapidly rotating "stationary" eddy is
generated in the eddy chamber 1. The fan means for driving
the flow Qro into the chamber 1 are not shown. According to
the invention the "stationary" eddy flow constitutes a primary
eddy flow 17 rotating at about 50,000 r.p.m. The primary eddy
flow 17 induces in the eddy chamber 1 a secondary flow 18
which adjacent to the central axis 1' travels toward the sink
flow Z and which travels along the inner surface of the walls
of the chamber 1 axially outwardly toward the exit openings
or slots 14 in the axial end walls 15 of the chamber 1. By
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1 utilizing the secondary flow 18 for transporting the particles
directly into and through the exit openings 14 the invention
achieves a surprisingly high efficiency for centrifugal separ-
ators. According to the invention the cleaning efficiency is
better than 99.9% of the particles carried in the gas flow Qro.
Such a cleaning efficiency has been achieved heretofore only
by means of electrostatic precipitators or by cloth type fil-
ters. Moreover, the invention removes particles having sizes
as small as about one half of a micron.
Due to the "stationary" primary eddy flow 17 the particles are
driven radially outwardly toward the inner surfaces of the
chamber wall 2 of the eddy chamber 1 to generate a secondary
flow 18. The secondary flow 18 moving axially outwardly along
the chamber walls 2 entrains the particles thereby transporting
them toward the axial end walls 15 of the chamber 1. The cham-
ber end walls divert the secondary flow radially inwardly along
the chamber walls 15 and toward the pipes 8. However, due to
the exit slots 14 according to the invention, the particles keep
travelling in the axial direction and thus out of the chamber 1
into the bin 7. The cleaned gas leaves the eddy chamber through
the immersion pipes 8 as shown by the arrows Qre. In this way
even the finest particles down to a size of about one half of
one micron are effectively removed from the flow. Although the
finest particles first travel axially inwardly driven by the
secondary flow along the immersion pipes 8, the sink flow in the
zone Z in combination with the secondary flow cause the finest parti-
cles to travel on spiral paths around the pipes 8. The spiral
paths have radii which increase radially outwardly in planes
extending perpendicularly to the longitudinal axis 1'. In
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1 other words, the largest radius of the spiral path is present
in the central zone around the sink flow zone Z whereby the
finest particles are carried again radially outwardly and
back into the axial secondary flow 18 toward the exits 14.
Thus, the finest particles do not reach the suction effect
zone adjacent to the inner openings of the suction pipes 8,
whereby a very efficient separation zone is present adjacent
to and around the suction pipes.
Fig. 3 shows an eddy chamber 20 within a curved wall 21 in
which there is arranged a crescent shaped wall member 4
forming a rotation channel 3 between the crescent member 4
and the curved wall 21. The crescent member 4 has such a
shape that the rotation channel 3 as viewed in the radial
direction has substantially a constant cross sectional width.
The rotation channel 3 extends across the entire axial length
of the chamber 20 as best seen in Fig. 4. According to the
invention discharge slots 5 are provided in the axial end
walls 15 adjacent to the curved wall 21 radially outwardly
of the crescent member 4 and further discharge openings 14'
are located in the axial end walls of the chamber 20 adjacent
to the crescent member 4 but radially inwardly thereof as seen
in Fig. 4. Separate secondary flows are generated radially
inwardly and outwardly of the crescent member 4 thereby dis-
charging the particles through the discharge openings 5 and
14' into the bin 7.
In the embodiment shown in Figs. 3 and 4 a very beneficial
separation mechanism for the particles dispersed in the gas
is achieved because the residence time of the particles in
the separation chamber is increased due to the fact that in
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1 the central sink flow zone Z only a partial volume of the
gas is withdrawn and another proportion of the gas will
travel through the rotation channel 3 around the crescent
member 4. Thus the longer residence times are achieved for
the finest particles in the chamber 20, whereby the transport
of the particles radially outwardly around the immersion pipes
8 is facilitated. The flow through the rotation channel 3 is
gradually enriched with particles by the continuous supply of
the raw or contaminated gas flow as indicated by the arrow Qro
to such an extent, for example, with dust particles, that the
so-called limit load is exceeded, whereby these particles are
continuously and easily discharged through the discharge
slots 5. Thus, the sucked off proportion of the clean gas
indicated b~ the arrows Qre is substantially improved with
regard to its quality or rather cleanness.
In Figs. 5 and 6 the eddy chamber 30 has end walls 31 and 32
as well as 33 and 34. Slots 5' are provided in the end walls 32
and 34. The end wall 31 is staggered axially inwardly relative
to the end wall portion 32. Similarly, the end wall 33 is
staggered axially inwardly relative to the wall portion 34.
This type of structure takes advantage of the fact that the
opening 14' and the opening 6 cooperate in the discharge of
particles as indicated by the arrows passing through the open-
ing 14' and the opening 6. Thus, the invention makes quite
certain that not only the particles which move axially with the
first secondary flow 1~ in the chamber 30 are removed through
the discharge opening 14', but that also particles which may
have remained in the secondary flow 9 in the rotation channel 3
and which are now travelling along a radial path 9' are effec-
tively discharged through the openings 6 located substantiallytangentially relative to the portion 9' of the secondary flow 9.
~t,..
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1 Fig. 7 shows a modification wherein the eddy chamber is
provided witha peeling slot 10 which facilitates the
removal of the coarser particles in the flow 11 because
these coarser particles are accumulated by the centrifugal
force along the inside surface of the eddy chamber.
Although the invention has been described with reference to
specific exemplary embodiments, it will be appreciated, that
it is intended to cover all modifications and equivalents
within the scope of the appended claims.
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