A ROTO-DYNAMIC HIGH PRESSURE MACHINE

MACHINE CENTRIFUGE HAUTE PRESSION

English Abstract

An improved pump or compressor of the centrifugal
type is provided, which has an impeller surrounded by a
housing and having a disk, a first plurality of vanes
provided near the disk, cover disks provided about the edges
of the vanes, and a second plurality of vanes provided on
the outwardly directed sides of the cover disks. Two
pressure steps are created by the first plurality of vanes,
each side of the disk and the cover disks. Two additional
pressure steps are created by the second plurality of vanes,
the cover disks, and pump housing walls that are located
adjacently to the second plurality of vanes. Single or
multiple flow conduits are arranged among the various inlets
and outlets of the pressure steps, such that a fluid flows
through the various pressure steps, with the last pressure
step being closest to a motor unit and an outlet connected
to the last pressure step being on the same side and facing
in the same direction as an inlet. Demands for higher
efficiencies, improved compactness and a simpler, more
symmetrical design are met by this configuration.

Claims

7
CLAIMS:
1. A pump or compressor of a centrifugal type for
providing high pressures, comprising:
a rotary shaft;
a motor connected to the shaft;
an impeller connected to the shaft and surrounded
by a housing, where the impeller comprises a circular disk
connected to a hub;
a first set of two or more vanes provided on each
side of the circular disk;
cover disks provided on the edges of the first set
of vanes; and
a second set of two or more vanes provided on the
outwardly directed sides of the cover disks, where two
pressure steps are formed by the first set of vanes, each
side of the circular disk and the cover disks, and an
additional two pressure steps are formed by the second set
of vanes, the cover disks, and a set of pump housing walls
located adjacently to the second set of vanes, with single
or multiple flow conduits arranged between the outlet of a
first pressure step and the inlet of a second pressure step,
between the outlet of the second pressure step and the inlet
of a third pressure step and between the outlet of the third
pressure step and the inlet of a fourth pressure step, and
where a last pressure step, which has a highest output
pressure, is closer to the motor than any other pressure
step and is connected with an outlet, which is located on
the same side of the pump or compressor as an inlet and
faces in the same direction as the inlet.

Description

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A ROTO-DYNAMIC HIGH-PRESSURE MACHINE.
FIELD OF THE INVENTION
The invention relates to a high-pressure machine,
and more particularly, to a pump for liquids or a compressor
for obtaining a media transport, including gaseous media,
under high pressure.
BACKGROUND OF THE INVENTION
When pumping liquids to high levels where
consequent high pressures are required, a pump of the
centrifugal type is preferred. Such a pump comprises a pump
impeller on a rotating shaft, such an impeller being
designed with a hub and a circular disk provided with one or
several impeller vanes. The liquid enters in an axial
direction in the center and leaves the impeller at the
periphery. A pump housing surrounding the impeller
transforms the kinetic energy to pressure energy, thereby
raising the transport to a higher level.
At higher heads, it is common to use pumps with
high rotation speeds and relatively small diameters. It is
also possible to connect a number of pumps in series by
connecting the outlet from a first step to the inlet in a
second step and so on. An example is shown in EP-A-355781,
where five steps are connected in series.
When a certain operation point at a certain
rotation speed is chosen, it can be an advantage to use
several steps, as the pump impellers can operate at rotation
speeds which are superior in terms of efficiency. This
increase of efficiency is mainly related to the fact that
the friction losses at the back sides of the impeller hubs,
as a part of the total losses, decrease. However, linking

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losses between the steps are added. A further disadvantage
is that the relatively complicated design means that service
and maintenance become complicated and in addition, long
shafts bring about increased mechanical stress.
Another way to obtain high pump heads is to
connect two identical pressure steps in series as is shown
in US-A-958 765 and DE-353 698. The pump impellers are here
arranged mirror-inverted, but have in other respects
conventional designs. US-A-2 136 939 discloses a pump with
two pressure steps having a common hub disk, thereby
obtaining a reduction of the disk losses. Both of these
solutions, however, have in common the problem that they
only allow two pressure steps. Therefore, these
conventional solutions are not always sufficient in terms of
obtaining the desired pump head.
What is needed, therefore, is a pump or compressor
having more than two pressure steps that can achieve a high
efficiency, while minimizing linking losses and avoiding
complicated designs.
2 0 SUI~iARY OF THE INVENTION
According to the invention there is provided a
pump or compressor of a centrifugal type for providing high
pressures, comprising: a rotary shaft; a motor connected to
the shaft; an impeller connected to the shaft and surrounded
by a housing, where the impeller comprises a circular disk
connected to a hub; a first set of two or more vanes
provided on each side of the circular disk; cover disks
provided on the edges of the first set of vanes; and a
second set of two or more vanes provided on the outwardly
directed sides of the cover disks, where two pressure steps
are formed by the first set of vanes, each side of the
circular disk and the cover disks, and an

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additional two pressure steps are formed by the second set
of vanes, the cover disks, and a set of pump housing walls
located adjacently to the second set of vanes, with single
or multiple flow conduits arranged between the outlet of a
first pressure step and the inlet of a second pressure step,
between the outlet of the second pressure step and the inlet
of a third pressure step and between the outlet of the third
pressure step and the inlet of a fourth pressure step, and
where a last pressure step, which has a highest output
pressure, is closer to the motor than any other pressure
step and is connected with an outlet, which is located on
the same side of the pump or compressor as an inlet and
faces in the same direction as the inlet.
In accordance with the invention, a pump or a
compressor having more than two pressure steps is provided,
which has a very high efficiency due to the minimization of
disk losses. The device according to the invention also
provides a design that is very compact, easy to mount and
adaptable with regard to axial forces and seal pressures.
The present invention, by allowing more than two
pressure steps, permits the achievement of higher pump
heads. By having a common hub disk, disk losses are
minimized and the use of multiple steps results in higher
efficiencies, as described above. Additionally, by having a
compact, easy to mount design, conventional problems such as
complicated service and maintenance, linking losses between
steps, and increased mechanical stresses due to long shafts
are minimized or avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a sectional view of the pump of an
embodiment of the subject invention; and

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Figure 2 shows the sectional view of Figure 1
inserted in a sectional view of a submersible pump.
DETAILED DESCRIPTION OF THE INVENTION
In the drawings, 1 stands for a rotary shaft and 2
is a pump impeller hub having a disk, 3. 4, 5, 6, and 7 are
impeller vanes, 8 and 9 are cover disks and l0 is a part of
a pump housing comprising walls 11 and 12 opposing the
impeller. 13, 14, 15, 16 and 17 symbolize seals, and 18,
19, 20 and 21 stand for inlets to the pressure steps. 22,
23, 24 and 25 stand for diffusers in the pump steps. 26, 27
and 28 stand for flow conduits and 29 and 30 stand for the
inlet and the outlet, respectively, for the pump. 31 stands
for the motor unit.
According to the invention, the high-pressure pump
comprises a pump housing 10 within which a rotating hub 2
with a connected disk 3 is arranged. The disk 3 is on each
side provided with vanes 5 and 6 respectively.
Each group of vanes 5 and 6 are provided with a
cover disk 8 and 9, respectively, thereby creating a double-
2o sided closed pump impeller. The cover disks 8 and 9 are on
their respective opposite sides provided with additional
vanes which form another double sided pump impeller together
with the pump housing walls 11 and 12, respectively. In
this way, a four-step pump impeller is created having two
closed and two open channels.
The pump operates in the following way: the
liquid is sucked in through the inlet 29 and flows to the
inlet 18 of the first pressure step. This step is formed by
the vanes 4, the cover disk 8 and the pump housing wall 11.
A flow conduit 26 goes from the diffuser 22 of said first
pressure step to the inlet 19 of a second pressure step,

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said second step being formed by the vanes 5, the underside
of the hub disk 3 and the cover disk 8. A second flow
conduit 27 goes from the diffuser 23 of said second pressure
step to the inlet 20 of a third pressure step, said third
5 step being formed by the vanes 6, the upside of the hub disk
3 and the cover disk 9. A third flow conduit 28 goes from
the diffuser 24 of said third pressure step to the inlet 21
of a fourth pressure step, said fourth step being formed by
the vanes 7, the cover disk 9 and the pump housing wall 12.
Finally, the liquid leaves the pump via the diffuser 25 of
the fourth pressure step through the outlet 30.
The pump according to the present invention
provides a number of advantages when compared with
conventional high-pressure pumps having one or several
pressure steps.
The efficiency is very high because multiple
pressure steps bring about more favorable specific rotation
speeds and considerable reductions in disk losses.
As shown in Figure 1, the last pressure step,
having the highest output pressure, is located adjacently to
the motor unit 31 and closer to the motor unit 31 than any
other pressure step. Additionally, the outlet 30, connected
to the last pressure step, is located on the same side of
the device as the inlet 29 and faces in the same direction
as the inlet 29. This design, where both the inlet 29 and
the outlet 30 are located on the same side of the device and
also near the motor unit, results in a very compact,
substantially symmetrical pump. This highly compact,
symmetrical design results in greater opportunities to
reduce axial forces, as well as seal pressures, when
compared with conventional devices. Problems such as
complicated service and maintenance, linking losses between

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steps, and increased mechanical stresses due to long shafts
are also minimized. The simple design also results in a
pump that is much easier to mount than conventional multi-
step pumps.
In the embodiment of the invention that is
described above, the importance of minimizing the pressure
difference between two adjacent pressure steps has been
stressed. If it is more important to minimize the axial
forces, another order between the steps might be preferable.
It is anticipated by the invention that various such mutual
orders of the pressure steps may be employed. The scope of
the invention also includes an embodiment where all of the
channels in the impeller are closed.
As previously mentioned, the invention is not
limited to pumps for liquids, but is also applicable for the
pressurizing of gaseous media.

Representative Drawing