Note: Descriptions are shown in the official language in which they were submitted.
CA 02711355 2010-08-04
MEMBRANE FILTER MODULE
Description
The invention relates to a membrane filter module.
[0001] Such membrane filter modules are known for example from EP 0 897 319 B
1 as well as US
6,209,727 B1. These filter modules consist of a multitude of membranes, which
are layered over one
another, wherein in each case flow paths or surfaced flow channels for the
supply of the medium as
well as for the discharge of the filtrate, are formed in an alternating manner
between the membranes.
Moreover, rotors are arranged in the supply paths for the medium to be
filtered and these are rotatingly
driven by a central shaft, in order to distribute the supplied medium over the
membranes. The supply
of the medium in the flow paths between the membranes, as well as the
discharge of the filtrate from
the flow paths between the membranes, is effected from the outer periphery. As
a rule, membrane
carrier plates made of plastic which are shaped in a complicated manner and
which are expensive to
manufacture, are necessary as carriers for the membranes. Moreover, these
modules require a
relatively large construction space on account of the membrane carrier plates.
[0002] It is the object of the invention to provide an improved membrane
filter module, which is less
expensive to manufacture and which furthermore may be constructed in a more
compact manner.
[0003] This object is achieved by a membrane filter module with the features
specified in claim 1.
Preferred embodiments are to be deduced from the dependent claims, the
subsequent description as
well as the attached figures.
[0004] As with the known membrane filter modules, the membrane filter module
according to the
invention is formed of a multitude of membranes, which are arranged lying over
one another. The
membranes lie over one another, such that their surfaces extend essentially
parallel to one another and
the membranes lie over one another in an essentially congruent manner. First
and second flow paths
are formed in an alternating manner in each case between two adjacent
membranes. With a multitude
of membranes, thus the first and second flow paths always alternate. The first
flow path serves for the
supply of the medium to be filtered, as well as for the discharge of
concentrate, whilst the second flow
path serves for the discharge of filtrate. A first flow path always serves for
the supply of the medium
to two membrane surfaces of two adjacent membranes, said surfaces lying
opposite one another, on
account of the alternating arrangement of the first and second flow paths.
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[0005] According to the invention, it is now envisaged for the supply channel,
which connects
several of the first flow paths to one another and through which the medium is
led to the first flow
paths, not to be situated on the outer periphery of the membranes, as is known
from the state of the art,
but in the inside of the outer periphery. This means the channel extends
through the membrane
surfaces. A very compact and space-saving arrangement is created in this
manner. Thereby, one
preferably provides a channel, which extends through the membranes in a
direction normal to the
membrane surfaces, additionally to a rotor shaft. The at least one supply
channel, which connects the
first flow paths to one another, is preferably situated in the region of the
outer half of the radius of the
membranes, particularly preferably close to the outer periphery, but
preferably distanced to the outer
periphery.
[0006] Further preferably, in each case a membrane carrier plate is arranged
between the
membranes, which delimit a second flow path. These membrane carrier plates fix
the membranes such
that they lie to one another in an essentially plane and parallel manner.
Thus, due to the alternating
arrangement, a membrane carrier plate lies between a first and second
membrane, a first flow path is
formed between the second and third membrane, again a membrane carrier plate
lies between the third
and fourth membrane, and a first flow path is again formed between the fourth
and fifth membrane,
etc. The second flow paths thereby in each case run along the surfaces of the
membrane carrier plates,
between the surfaces of the membrane carrier plate and the adjacent membranes.
[0007] The membrane carrier plates are in each case preferably designed as
disks with plane
surfaces. This permits a very inexpensive design, since the membrane carrier
plates may be simply cut
from a plate material, and require no structuring on the surface at all. Thus,
the membrane carriers
plates are further preferably manufactured from metal, for example rust-free
stainless steel. This
permits the membrane carrier plates to be designed significantly more thinly
with the same stability,
than was the case with the membrane carrier plates of plastic used in the
state of the art. The thinner
design of the membrane carrier plates, with a multitude of membranes layered
over one another, with
membrane carrier plates lying therebetween, as a whole leads to a
significantly reduced construction
length of the complete membrane filter module.
[0008] Further preferably, in each case a spacer material, through which the
second flow path runs,
is arranged between the surfaces of the membrane carrier plate and the
adjacent membranes. The
spacer material is a porous material, for example a non-woven, through which
the filtrate may flow.
The spacer material thus keeps the adjacent membranes at a distance to the
surfaces of the membrane
carrier plates, so that a surfaced flow path for the discharge of filtrate is
created between the
membrane and the membrane carrier plate.
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[0009] It is further preferable for the supply channel to be formed in each
case by way of at least one
hole in the membrane carrier plates. Such a hole may be cut into the plane
membrane carrier plates in
a very simple manner or incorporated in another manner. Thus a supply channel
to the first flow paths
through a part, preferably through the complete membrane filter module, is
created by way of the
successive holes of the individual membrane carrier plates.
[0010] The two membranes enclosing the membrane carrier plate, i.e. the
membranes which border
the membrane carrier plate at the opposite surfaces of the membrane carrier
plate, are further
preferably connected to one another, preferably welded, on the inner periphery
of the hole in the
membrane carrier plate. Thus, an annular welding seam may be formed on the
inner periphery of the
hole. Then, preferably, a hole through the membrane is likewise formed in the
inside of the annular
welding seam, so that the supply channel there may extend through the
membrane. The membranes
may however also be sealingly connected in another suitable manner, e.g.
bonded or clamped. The
supply channel in this manner is merely formed by way of holes in the membrane
plates and the
membrane plate carriers, which are stacked on one another, without an
additional pipe or likewise
being necessary. The holes in the several membranes or membrane carrier plates
may thereby lie over
one another in a flush manner. According to a fu ther preferred embodiment
however, the holes in the
individual membrane carrier plates and which define the supply channel, and
accordingly the holes in
the membranes and which are formed in the region of these holes, may be offset
to one another. This
means that with the multitude of membrane carrier plates which are stacked
over one another, the
individual holes in the membrane carrier plates do not lie over one another in
a flush manner, but
offset to one another from membrane plate to membrane plate. An improved
distribution of the
supplied medium in the filter module is achieved in this manner. Preferably,
the membrane carrier
plates are all designed in an identical manner, which means the holes are also
designed in an identical
manner. For the offset of the holes, the membrane carrier plates are merely
arranged offset to one
another in the angular position about their middle axis. In this manner, a
helical course of the position
of the holes may be achieved over the whole length of the membrane filter
module. However, it is also
conceivable to arrange the holes flush with one another in sections, and to
merely offset the position of
the holes to one another between the individual sections.
[00111 The first flow paths between the membranes, as described above, are
preferably designed as
free spaces, in which in each case a rotor is located, which serves for
distributing the medium in the
free space, so that the medium flows simultaneously over the membranes. The
supply is located where
the rotor moves over the membrane with the greatest speed, by way of the
arrangement of the supply
channel in the outer half of the membrane. Thus the medium flowing in through
the supply channel is
distributed in a particularly effective manner.
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[0012] The individual rotors are preferably arranged on a common motor shaft
which extends in
each case through a central hole in the membrane carrier plates. The central
rotor shaft, as is known
from known membrane filter modules, may be rotatingly driven by a drive motor,
which is preferably
arranged on a lower side of the membrane filter module. The central hole, as
described, is arranged
distanced to the hole for the supply channel.
[0013] The membranes enclosing a membrane carrier plate are furthermore
connected to one
another also at the inner periphery of the central hole, preferably welded,
and comprise a hole in the
inside of the thus formed annular seam or welding seam, through which hole the
rotor shaft extends.
The design of the welding seam, inasmuch as this is concerned, is similar to
the welding seam in the
hole for the supply channel. Here too, a suitable other sealed connection
between the membranes may
be applied.
[0014] The second flow paths, which serve for the filtrate discharge, are
preferably open to the outer
periphery of the membranes, which means the filtrate exits at the outer
periphery of the filter module
and there is collected in a casing, which includes the filter, and led away.
The medium to be filtered is
preferably introduced into the supply channel through a hole in the base plate
or the upper plate of the
stack of membranes. Then accordingly, the concentrate is led out of the supply
channel at the opposite
end of the membrane filter module.
[0015] Further preferably, in each case, an outer spacer ring is arranged on
the outer periphery of the
membrane, between the membranes which in each case delimit the first flow
path. This ensures that
the membranes delimiting the first flow path, as well as the membrane carrier
plates lying behind
these, are held at a defined distance, so that a free space arises between the
membranes, in which the
rotor may rotate.
[0016] The complete arrangement of the membranes lying over one another, with
spacer materials
and membrane carrier plate, which lie therebetween as the case may be, is
preferably fixed by way of
guide rods, which are arranged outside the outer periphery of the membranes.
This permits a very
simple assembly. The guide rods thereby fix the membrane carrier plates with
the membranes
arranged thereon, thereby in particular in the radial direction, so that they
may not displace to one
another in the radial direction. In the axial direction, the membranes lying
over one another, with the
membrane carrier plates lying therebetween, are fixed by way of a base plate
and a cover plate, or are
pressed onto one another.
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[0017] For fixation, the guide rods are preferably in contact with the outer
periphery of membrane
carriers arranged between the membranes and/or of the spacer rings.
Preferably, the spacer rings as
well as the membrane carrier plates are fixed on the outer periphery by way of
guide rods.
[0018] For this, spacer pieces maybe arranged on the guide rods, which in each
case are in contact
with the outer periphery of the membrane carrier plates and the outer spacer
rings. The spacer pieces
may thereby be designed, such that in each case a spacer piece is envisaged
for contacting the spacer
ring and an adjacent membrane carrier plate. The spacer pieces may be
profiled, in order, with
different outer diameters of spacer ring and membrane carrier plate, to be
able to contact both on the
outer periphery. Thus the spacer ring may preferably have a larger outer
diameter than the membrane
carrier plate.
[0019] The invention is hereinafter described byway of the attached figures.
In these are shown in:
Fig. I schematically, a membrane filter system with a membrane filter module,
according to
the invention,
Fig. 2 a plan view of the membrane filter module according to Fig. 1,
Fig. 3 a sectioned view along line III-I11 in Fig. 2,
Fig 4 enlarged, the detail IV from Fig. 3,
Fig. 5 enlarged, the detail V from Fig. 3 and
Fig. 6 an enlarged, sectioned view of the detail VI in Fig. 1.
[0020] The membrane filter system shown in Fig. 1 comprises a membrane filter
module 2, in which
a central rotor shaft 4 is arranged, said shaft being rotatingly driven via a
belt drive 6 by an electric
motor 8.
[0021] Fig. 2 shows a plan view of the part of the membrane filter module 2,
which is situated in the
inside of the housing 10. In Fig. 2, from above, one may recognise the
uppermost membrane carrier
plate 12. An outer spacer ring 14 is placed onto this at the outer periphery
of this plate. This spacer
ring 14 ensures that a defined distance to the membrane carrier plate 12 or
cover plate 15, which lies
thereabove, remains. Moreover, the spacer ring 14 on the outer periphery holds
the membrane, which
lies over the membrane carrier plate 12, bearing on the membrane carrier plate
12 or on a spacer
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material arranged on this. The membrane carrier plates 12 itself is formed as
a plane disk and is cut
preferably from a plane sheet metal, preferably stainless steel sheet.
[0022] A rotor 16 is arranged above the membrane carrier plate 12, in the free
space enclosed by the
spacer ring 14, and this rotor is connected to the rotor shaft 4 in a
rotationally fixed manner and is thus
rotatingly driven by this. The rotor shaft 4 extends through a central hole 18
in the membrane carrier
plate 12. The membrane carrier plate 12 moreover comprises a second hole,
which is arranged radially
to the outside, distanced to the central hole 18. The hole 20 forms part of a
supply channel, through
which the medium or fluid to be filtered is supplied. The rotor 16 distributes
this fluid over the
membrane.
[0023] The further construction of the membrane filter module is now explained
by way of the
sectioned view in Fig. 3, as well as the enlarged detail views in Figures 4 to
6.
[0024] The membrane filter module 2 comprises a multitude of membranes 22
lying over one
another. In the shown example, twenty membranes 22 are provided, which are
arranged over ten
membrane carrier plates 12. The membranes 22 do not bear directly on the
membrane carrier plates
12, but are held at a distance to the membrane carrier plate 12 by a spacer
material 24. The spacer
material 24 is fluid permeable, so that it forms a surfaced flow path between
the membrane 22 and the
membrane carrier plate 12 which borders this. The filtrate is discharged
through the spacer material
24.
[0025] As described, the supply of the medium or fluid to be filtered, is
effected through the holes
20. Such a hole 20 is formed in each of the membrane carrier plates 12.
Thereby, the circular
membrane carrier plates 12 are all designed in an identical manner, but are
arranged rotated to one
another with respect to the longitudinal axis of the rotor shaft 4, in a
manner such that the holes 20 in
the individual membrane carrier plates 12 are not flush with one another. The
medium to be filtered is
led through the holes 20 into first flow paths 26 between the membranes 22.
The first flow paths 26
form surfaced flow paths in each case between two membranes 22, at their sides
which are away from
the membrane carrier plates 12. The first flow paths 26 in the form of free
spaces and the second flow
paths formed by the spacer material 24, thus alternate in a regular manner
between the membranes 22.
The rotors 16 are arranged in each case in the free spaces forming the first
flow paths 26. The
discharge of concentrate is likewise effected through the supply channel
formed by the holes 20. The
medium to be filtered is introduced into the thus formed supply channel from
the lower side, i.e.
through the base plate 28, and the concentrate is led away through an opening
at the opposite end of
the membrane stack, i.e. through the cover plate 15.
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[0026] The filtrate flows through the spacer material 24 radially outwards and
exits to the outside at
the outer periphery between the outer spacer rings 14. Then it is collected in
the housing 10 and may
be discharged via an outlet 30 in the housing 10.
[0027] The membranes 22 which are situated on both sides of the respective
membrane carrier plate
12, are welded to one another in the central holes 18, as well as the holes
20. An annular welding seam
situated on the inner periphery of the hole 20, as well as a welding seam
situated on the inner
periphery of the central hole 18, are provided for this. The membranes 22 are
also broken through in
the holes 18 and 20, i.e. within the annular welding seams, so that the rotor
shaft 4 may extend through
the membranes 22, and a free passage for the medium to be supplied is formed
in each case in the
holes 20. It is ensured by way of the sealed connection of the membrane 22
situated on both sides of
the membrane carrier plate 12, on the inner periphery of the holes 18 and 20,
that the medium to be
filtered may not enter directly from the first flow paths 26 or the central
hole 20, into the region
between the membranes 22 and the membrane carrier plates 12, in which the
spacer material 24 is
arranged. In this manner, one ensures that a passage into this region is only
possible through the
membrane 22.
[0028] A simpler and compacter construction of the membrane filter module 2 is
ensured by way of
the supply of the medium to be filtered, through the holes 20, which are
situated in the inside of the
outer periphery of the membranes 22 and the membrane carrier plates 12, since
no supply channels
need to be placed on the outer periphery. Simultaneously, a good distribution
of the medium to be
supplied is achieved in the free spaces 26 between the membranes 22, in which
the rotors 12 are
arranged, since the medium enters into these spaces in a direct manner and
does not need to be
introduced into these from the outer periphery. Moreover, a very simple
construction of the membrane
carrier plates 12 is possible. These require no special shaping or profiling
on their surfaces
whatsoever, but may be designed as smooth disks. Inasmuch as this is
concerned, they may be cut
from a sheet metal. This permits a thinner construction compared to a membrane
carrier plate 12
formed of plastic, by which means the total axial length of the membrane
filter module is shortened.
[0029] Guide rods 32 are arranged on the outer periphery of the membrane
carrier plates 12 and the
membranes 22, for centering or fixing the membrane carrier plates 12 in the
radial direction with
respect to the longitudinal axis X of the rotor shaft 4. At least three guide
rods 32 are distributed
uniformly over the outer periphery of the membrane filter module 2, so that
movements of the
membrane carrier plates 12 may be prevented in all radial directions. It is to
be understood that one
may also arrange more than three guide rods 32. Spacer pieces 34 are placed
onto the guide rods 32,
wherein a spacer piece 34 is provided for each step of the membrane filter
module 2, consisting of a
membrane carrier plate 12 and an associated outer spacer ring 14. The spacer
pieces 34 have a central
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bore, through which the guide rod 32 extends. Moreover, they comprise two
sections 36 and 38 in the
axial direction. The section 36, whose axial length corresponds to the
thickness of the membrane
carrier plate 12 and the layers of spacer material 34 bearing on both sides,
has a larger outer diameter
than the section 38. The section 38 corresponds in its axial length to the
axial thickness of a spacer
ring 14. The spacer rings 14 have a larger outer diameter than the membrane
carrier plates 12. The
section 36 with the largest diameter of the spacer piece 34 bears on the outer
periphery of the
membrane carrier plate 12, whilst the section 38 with the smaller diameter
bears on the outer periphery
of the spacer ring 14. In this manner, the membrane carrier plate 12, as well
as the spacer ring 14 are
fixed in the radial direction between the guide rods 32 with the applied
spacer pieces 34. The spacer
pieces 34 additionally ensure that the individual membrane carrier plates 12
are held at a defined
distance to one another, and the spacer material 24 at the outer periphery
between the spacer rings 14
may not be compressed beyond a certain amount when the complete membrane
filter module 2 is
pressed together by way of tightening the base plate 28 and cover plate 15.
The outer periphery
between the guide rods 32 remains free, by way of the fact that only few,
preferably three guide rods
32 are arranged distributed on the outer periphery, so that in these regions,
the filtrate may exit radially
to the outside out of the spacer material 24.
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List of reference numerals
2 - membrane filter module
4 - rotor shaft
6 - belt drive
8 - drive motor
- housing
12 - membrane carrier plate
14 - outer spacer ring
- cover plate
16 - rotor
18 - central hole
- hole
22 - membrane
24 - spacer material
26 - first flow path
28 - base plate
- outlet
32 - guide rod
34 - spacer piece
36, 38 - sections of the spacer piece
X - longitudinal axis
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