Note: Descriptions are shown in the official language in which they were submitted.
CA 02581268 2007-03-07
SINGLE STAGE LIQUID RING VACUUM PUMP HAVING DOUBLE AXIAL INLET
The present invention relates to a single-stage liquid-
ring vacuum pump having a double axial inlet with flat-
distribution plates.
The present invention is particularly adapted for use
in suction of aeriform substances also containing small
solid particles or wet aeriform substances that, by
effect of the compression fo llowing suction, cause
water condensation, which is noxious to other types of
pumps.
Pumps of this type are used in processes involving de-
aeration, impregnation, boiling, vacuum condensation,
distillation, drying, sterilisation, filtration and
solvent recovery.
By way of example, these pumps are therefore used in
the sector concerning processing of plastic materials
for example, where removal of the humidity that
otherwise would be dangerous is required, or in all
sectors in which it is necessary to create the vacuum,
such as the pharmaceutical, chemical, petrochemical
sectors, chemical or food distilleries, refineries, oil
mills, dairies, etc.
Single-stage liquid-ring vacuum pumps having a double
axial inlet generally comprise a central body defined
in the specific technical field as spacer. The spacer
internally confines a cylindrical chamber having a
regular or irregular circular section with a
longitudinal extension axis that, when the pump is
installed, is oriented in a horizontal direction.
Housed in the chamber is an impeller fitted on a shaft
extending parallel to the longitudinal extension axis
of the chamber and spaced apart therefrom. The impeller
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is therefore mounted eccentrically in the chamber.
Installed on each of the opposite axial ends of the
spacer is a cover closing the chamber and having
passages for admission and exhaust of the fluid to be
pumped and of a working liquid. In particular, each of
the two covers internally has a first compartment oDen
towards a first region of the chamber through a suction
opening formed in a head wall delimiting the chamber.
The first compartment also communicates with a suction
manifold through a flanged body mounted on the cover
itself. A second compartment opens on a second region
of the chamber through an exhaust or pressurized
opening formed in a head wall delimiting the chamber,
which exhaust opening preferably has smaller sizes than
the feeding opening. The second compartment further
communicates with an exhaust manifold through a flanged
exhaust or presurized body, mounted on the cover too.
The flanued suction bodies of the two covers are
mutually connected by said suction manifold which ;!~s
defined by a pipe disposed above the spacer and
Dreferably running parallel to the longitudinal axis of
the chamber. At an intermediate portion of the suction
manifold there is a suction inlet designed to be
connected to the environment from which the fluid is to
be sucked.
The flanged exhaust bodies of the two covers are
mutual7~y connected by said exhaust manifold which is
defined by a pipe disposed above the spacer and
preferably running parallel to the longitudinal axis of
the chamber. At an intermediate portion of the exhaust
manifold there is an exhaust or pressurized outlet
designed to be connected to the environment into which
the sucked fluid is to be introduced.
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Each of the two covers is further provided with a third
compartment that is open towards the chamber and
communicates with a filling inlet for the working
liquid which is formed in a head wall delimiting the
chamber. The feeding inlet is defined by an attachment
element mounted on the cover itself and designed to be
coupled, through suitable pipes, with a feeding source
for supply of said working liquid.
In particular the working-liquid feeding system
contemplates use of pipe fittings and connecting pipes
between each of the individual feed inlets present on
the covers and the main element for attachment to the
plant with, as a result, further complexity for
installation of the pump before use.
The impeller while being only one, is divided into two
axial portions working in parallel.
The fluid sucked by the suction -i-nlet is shared between
the two flanged suction bodies and enters the
cylindrical chamber through each of the suction
openings present on the covers. At each of the two
axial portions of the impeller, the fluid is enclosed
between two successive vanes and a ring defined by the
working liquid that, by effect of the centrifugal
force, lies close to the cylindrical side wall of said
chamber. The nrogressive volume variation created
between the two vanes and the liquid ring, by virtue of
the eccentric rotation of the impeller relative to the
spacer and the liquid ring, first creates a fluid
expansion and, subsequently, a fluid compression until
said fluid is ejected through the exhaust openings. The
ejected fluid is then conveyed through the manifold
into the single exhaust outlet.
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However, the single-stage liquid-ring pumps having a
double axial inlet with flat-distribution plates of
known type which have been briefly described above have
many limits and drawbacks.
In particular, the Applicant has perceived that the
bulkiness and weight of the pumps of known type should
be reduced. In fact, the vertical bulkiness of known
pumps is greatly affected by the presence of the
suction and exhaust manifolds that must be mounted on
the pump itself .
Furthermore, also the presence of four flanges that are
required for connection of the two manifolds to the
pump adversely affects the bulkiness and weight of the
covers, and therefore the bulkiness and overall weight
of the pump itself because the flanged feeding inlets
and exhaust outlets are positioned on the covers, and
the flange size is fixed and strictly linked to the
flow rate of the fluid to be treated. Under this
situation, the technical task underlying the present
invention consists in conceiving a single-stage liquid-
ring vacuum pump having a double axial inlet with flat-
distribution plates that is capable of substantially
obviating the mentioned drawbacks.
In particular, it is an aim of the present invention to
propose a single-stage liquid-ring vacuum pump having a
double axial inlet with flat-distribution plates that
is able to reduce the overall bulkiness and the pump
weight and to optimise the suction and exhaust fluid
mechanics, the supplied performance being the same.
Within the scope of this technical task, it is an
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important aim of the invent;_on to conceive a single-
stage liquid-ring vacuum pump having a double axial
inlet with flat-distribution plates that can be more
easily transported and installed.
The technical task mentioned and the aims specified are
substantially achieved by a single-stage liquid-ring
vacuum pump having a double axial inlet with flat-
distribution plates that is characterised in that it
"10 comprises one or more of the technical solutions
claimed in the appended claims.
The ciescr;-ption of a preferred but not exclusive
embodiment of a single-stage liquid-ring vacuum pump
having a double axial inlet with flat-distribution
plates in accordance with the invention is now given by
way of non-limiting example and illustrated in the
accompanying drawings, in which:
- Fig. 1 is an overall perspective view of a single-
stage liquid-ring vacuum pump having a double axial
inlet with flat-distribution plates in accordance with
the invention;
- Fig. 2 shows an exploded view of the pump seen in
Fig. 1;
- Fig. 3 is a front view of the pump in Fig. 1;
- Fig. 4 is a section view taken along line IV-IV in
Fig. 3;
- Fig. 5 is a section view taken along line V-V in Fig.
4;
- Fig. 6 is a perspective view of a first element of
the pump shown in Fig. 1;
- Fig. 7 is a perspective view of a second element of
the pump seen in Fig. 1; and
- Fig. 8 is a front view of a third element of the pump
seen =Ln Fig. 1.
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With reference to the drawings, a single-stage liquid-
ring vacuum pump having a double axial inlet with flat-
distribution plates has been generally identified with
reference numeral 1.
The pump comprises a central body 2 or spacer, better
shown in Figs. 2 and 6. The central body 2 has a
cylindrical side wall 3 of circular or substantially
circular section, internally delimiting a cylindrical
or substantially cylindrical chamber 4 having a
longitudinal extension axis "X".
Housed in chamber 4 is an imbeller 5 fitted on a shaft
6, said shaft extending parallel to the longitudinal
extension axis "X" of the chamber. 'r'he longitudinal
axis "Y" of the shaft 6 is spaced from the longitudinal
extension axis "X" of the chamber (Fig. 4) . In known
manner, the impeller 5 is therefore eccentrically
mounted in chamber 6, as better shown in Fig. S. One
end 6a of the shaft 6 emerges from the pump to enable
connection to a motor, not shown.
Formed at each of the two opposite axial ends 7 of the
central body 2, i.e. on opposite faces of the cylinder
defined by the body 2 itself, is a suction opening 8
and an exhaust opening 9 (Fig. 2).
The central body 2 further has an opening 10 (only
visible in FJ g. 7) at each of said two axial ends 7,
said opening being designed to feed a working liquid 11
that will define the liquid ring.
In the preferred embodiment herein shown, these
openings 8, 9, 10 are formed in a plate 12. As shown in
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Figs. 2 and 4, each of the two plates 12 closes a
respective end 7 of the cer_tral body 2 and confines
chamber 4. In addition, each plate 12 lies close to an
edge of the impeller vanes 13 and to an end surface of
the impeller hub 5a, so that a work volume for a fluid
14 to be treated is defined between two consecutive
vanes 13 and together with the liquid ring.
Further auxiliary exhaust openings 9a known by
themselves and therefore not further described can be
present next to the exhaust opening 9, said exhaust
opening 9 having smaller sizes than the suction opening
8, as visible in Figs. 2 and 4. The auxiliary exhaust
openinas 9a are preferably closed by flexible blades or
similar elements not shown that under the action
exerted by the fluid, open when the pressure overcomes
a predetermined threshold.
Both suction openings 8 are in fluid communication with
a suction manifold 15 having a suction inlet 16 adapted
to be connected to the environment from which the fluid
14 is to be sucked.
Both exhaust openings 9 are in fluid communication with
an exhaust manifold 17 having an exhaust outlet 18
adapted to be connected to the environment into which
the previously sucked fluid 14 is to be introduced.
The opening 10 designed to feed the working l-quid 11
is in fluid communication with a feed manifold 19
having a feeding inlet 20 adapted to be connected to a
feeding source not shown, for supply of said liquid 11.
Advantageously the suction manifold 15 and exhaust
manifold 17 are integrated into the central body 2.
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=
Preferably, the feed manifold 19 too is integrated into
the central body 2.
In more detail, as better shown in Figs. 2, 5 and 6,
the suction manifold 15 and exhaust manifold 17 are
formed close to the cylindrical side wall 3 of the
central body 2 and are preferably located close to an
upper portion of the pump 1, considering the installed
pump 1 resting on the ground with its longitud-nal axis
i0 "X" disposed horizontally.
The two manifolds 15, 17 preferably extend narallel to
the longitudinal axis "X" and preferably are symmetric
relative to a vertical plane passing through said
lonaitudinal axis "X".
In the preferred embodiment herein illustrated, the
suction manifold 15 and exhaust manifold 17 are formed
of one piece construction, by melting for example, with
the central body 2. The manifolds are formed in the
thickness of the central body 2 wall.
The geometric configuration thus taken enables the
suction and exhaust fluid mechanics to be optimised
because generation of imbalances or disequilibrium
between the incoming and outgoing fluids is avoided.
Therefore the construction symmetry outlined above
gives further advantageous aspects to the pump being
the ob"ect of the invention.
Each of the two manifolds 15, 17 is confined by a
convex portion 21 of the outer surface of the
cylindrical wall 3 and by an arched portion 22 having
opposite edges oriented as generatrices of the
cyli_ndrical wall 3 and joined to the cylindrical wall 3
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itself (Fig. 6) The manifold shape seen in cross
section is not however given in a limiting sense. In
fact the wall 22 can have different shapes and the
outer surface of the cylindrical wall 3 can be such
shaped as to give the manifold the most appropriate
section.
At an axially intermediate portion of the suction
manifo7-d 15, a suction duct 23 of circular section is
present and it preferably extends verticaliy from said
manifold 15 and terminates with the suction inlet 16.
A flange 24 surrounds the suction inlet 16, is also
preferably formed of one piece construction with the
suction duct 23 and the suction manifold 15, and is
used to connect the pump 1 to the environment from
which the fluid 14 is to be drawn.
Likewise, at an axially intermediate portion of the
exhaust manifold 17, an exhaust duct of circular
section 25 is present which extends vertically from
said manifold 17 and terminates with the exhaust outlet
18.
The flange 24 too surrounding the exhaust outlet 18 is
preferably of one piece construction with the exhaust
duct 25 and the exhaust manifold 17 and is used to
connect the pump 1 to the environment ir_~to which the
sucked fluid 14 is to be introduced.
As shown in Figs. 2 and 6, also the feed manifold 19
for the working liquid 11 is preferably integrated into
the central body 2, in the same manner as the manifolds
15, 17.
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This feed manifold 19 is formed at the cylindrical side
wall 3 of the central body 2 and is preferably located
close to a lower side portion of pump 1.
In the preferred embodiment herein illustrated, the
feed manifold 19 extends parallel to the longitudinal
axis "X" of the central body 2 and is of one piece
construct-on, by melting for example, with the central
body 2.
This feed manifold 19 is confined by a convex portion
26 of the outer surface of the cylindrical wall 3 and
by an arched wall 27 having opposite edges oriented as
generatrices of the cylindrical wall 3 and joined to
the cylindrical wall 3 itself (Fig. 6).
An attachment element 28 is present at an axially
intermediate portion of the feed manifold 19 and it
extends from said manifold 15 and terminates with the
feeding inlet 20 for supply of the working liquid 11.
Said attachment element 28 too is preferably formed
unitary, by melting for example, with the central body
2.
The wall 27 can have different shapes and the outer
surface of the cylindrical wall 3 can be such shaped as
to give the manifold the most appropriate section.
To enable passage of fluid 14 from the suction manifold
15 to the suction opening 8 and from the exhaust
opening 9 to the exhaust manifold 17, pump 1 comprises
a pair of covers 29 each abutting against one of the
ends 7 of the central body 2 (Figs. 1 and 2).
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r
Each cover 29 is mounted on one of the plates 12, said
one plate therefore being interposed between the
central body 2 and cover 29 (Fig. 4); in this way the
assembly tightness to the fluids is simplified because
only a hermetic tightness between the cover 29 and
plate 12 and between the plate 12 and central body 2 is
required to be ensured. In parti cular the necessity of
seals simultaneously operating on the three parts is
avoided, which would make the assembling process more
complicated and would impair the overall pump
reliability.
The two covers 29, two plates 12 and central body 2 are
pack-wise closed by means of tie-rods 29a passing
through slots formed in the covers 29 themselves (Fig.
1).
In addition, as better shown in Figs. 2 and 7, each of
the two plates 12 has a f i rst aperture 30 in register
with the suction man-_fold 15 and shaped like the cross
section of this manifold 15, a second aperture 31 in
register with the exhaust manifold 17 and shaped like
the cross section of this manifold 17 and a third
aperture 32 in register with the feed manifold 19 and
shaped like the cross section of this manifold 19. The
first, second a~id third apertures 30, 31, 32 are formed
close to a peripheral edge of plate 12 (Fig. 7).
Cover 29 on a concave face 33 thereof facing the
respective plate 12 delimits a first compartment 34
(Figs. 2 and 8) t:hat, when pump 1 is assembled, is in
fluid communication with the respective suction opening
8 of plate 12 and with the suction manifold 15, a
second compartment 35 in fluid communication with the
respective exhaust opening 9 of plate 12 and with the
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exhaust manifold 17 and a third compartment 36 in fluid
communication with the feed manifold 19 for the working
liquid 11 and with the respective opening 10 in plate
12 to supply said working liquid 11.
Said compartments 34, 35, 36 are seDarated from each
other by baffles 37 and delimited by a peripheral edge
38 of cover 29 and an inner edge 39, said inner edge 39
surrounding a central hole 40 designed to receive the
shaft 6(Fias. 8 and 4) . Said shaft 6 further passes
through a central hole 40a formed in each nlate 12.
Each plate 12 has opposite flat surfaces, is coupled
with one of the ends 7 of the central body 2 on a
single plane and is further coupled with the respective
cover 29 on a single plane. This flat coupling without
coupling locators enables the working operations to be
simplified, the production times and costs to be
improved and the sealing capacity of the pump to be
greatly increased.
in fact, the peripheral edge 38, inner edge 39 and
baffles 37 of cover 29 abut against plate 12 and are
coplanar.
In addition, as shown in Figs. 4 and 6, an end edge 41
of the cylindrical wall 3 and end edges 41 of the
arched walls 22, 27 lie in the same plane and abut
against plate 12.
Each plate 12 has the respective suction opening 8
facing chamber 4 and the first compartment 34, the
respective exhaust opening 9 facing chamber 4 and the
second compartment 35 and the respective opening 10 for
supply of the working liquid 11 facing chamber 4 and
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the third compartment 36.
The first aperture 30 of plate 12 further faces the
first com-Dartment 34 and the suction manifold 15, the
second aperture 31 faces the second compartment 35 and
the exhaust manifold 17 and the third aperture 32 faces
the third compartment 36 and the feed manifold 19.
Referring in parti cular to Fig. 4, a flange or box 42
carrying a bearing 43 which supports shaft 6 is housed
in each of the holes 40 of covers 29.
Installed between each flange 42 and the shaft 6 is a
rotating sealing element 44 known by itself, which lies
between the impeller 5 and the respective bearing 43.
Possible liquid leakages are collected by means of a
pipe fitting 45 positioned in flange 42, said pipe
fitting opening into said flange 42 close to the shaft
6 between the sealing element 44 and the respective
bearing 43. Interposed between the bearing 43 and pipe
fitting 45 is an annular gasket 46.
The collected liquid 11 can be recycled by connecting
said pipe fittings 45 to a circuit for re-introduction
of the leaked liquid 11 into the feed manifold 19.
Each of the two covers 29 has a pair of support feet 47
provided with holes for anchoring the pump 1 to a base.
Finally, as shown in the preferred embodiment Fig.
4, the pump 1 comprises an auxiliary flange, or bearing
support, 48 located at the end 42a opposite to the end
6a of the shaft 6 to be connected to the motor and
housed in the main flange 42 in coaxial relationship.
The auxiliary flange 48 carries the bearing 43
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supporting the shaft 6 and is axially adjustable
relative to the main flange 42, so as to easily adjust
the axial position of the shaft 6 and impeller 5 in
chamber 4.
in particular, adjusting screws 49, not shown in
detail, are used to move the auxiliary flange 48 within
the main flange 42 along an axial direction, while
locking screws 50 lock the two flanges 48, 42 to the
desired position, once adjustment has been carried out.
The pump in accordance with the invention achieves the
intended purposes and offers many advantages.
In fact, the supplied performance being the same, the
pump of the invention is much more compact and lighter
in weight than the pumps of the known art. The weight
reduction as compared with pumps of same performance is
about 30% and the reduction in volume is about 40%.
This result has been achieved because said suction and
exhaust manifolds with flanged inlets and outlets are
integrated into the central body and a single-
attachment feed is provided; in addition, due to the
presence of said single-attachment feed, the flanges
for coupling to the manifolds and the feeding inlet
present in covers of known pumps have been eliminated.
Consequently, the two covers have been greatly reduced
in size and bulkiness which has brought about an
important reduction in weights and materials.
Furthermore, due to the reduced weight and bulkiness,
the pump of the invention can be transported and
installed in a simpler and quicker manner.
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Installation is also simplified as a result of the fact
that the integrated manifolds are already in place and
must not be mounted in situ.
In addition, a feeding integrated with a single
attachment element does not require pipe fittings and
particular plant connections.
The compactness in an axial direction of the pump of
the invention also enables the shaft length of the
imbeller to be reduced, as compared with known pumps of
same performance. This reduction, in addition to
involving a decrease in the shaft weight, also gives
rise to a reduction in the shaft bending during
rotation and, therefore, to an important vibration
reduction.
The vibration reduction brings about, as a consequence,
an increase in the fatigue life of the pump components
and a decreased operational noise.
