NZ613190B2 - Novel shape of filtering elements - Google Patents
Novel shape of filtering elements Download PDFInfo
- Publication number
- NZ613190B2 NZ613190B2 NZ613190A NZ61319012A NZ613190B2 NZ 613190 B2 NZ613190 B2 NZ 613190B2 NZ 613190 A NZ613190 A NZ 613190A NZ 61319012 A NZ61319012 A NZ 61319012A NZ 613190 B2 NZ613190 B2 NZ 613190B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- crown
- axis
- row
- flow
- channel
- Prior art date
Links
- 238000001914 filtration Methods 0.000 title claims abstract description 204
- 239000012530 fluid Substances 0.000 claims abstract description 20
- 239000000706 filtrate Substances 0.000 claims abstract description 9
- 238000009434 installation Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 abstract description 8
- 239000007788 liquid Substances 0.000 abstract description 3
- 238000001471 micro-filtration Methods 0.000 abstract description 2
- 238000001728 nano-filtration Methods 0.000 abstract description 2
- 238000001223 reverse osmosis Methods 0.000 abstract description 2
- 238000000108 ultra-filtration Methods 0.000 abstract description 2
- 239000000758 substrate Substances 0.000 abstract 14
- 229910052799 carbon Inorganic materials 0.000 description 37
- 230000002093 peripheral effect Effects 0.000 description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 229910010272 inorganic material Inorganic materials 0.000 description 3
- 239000011147 inorganic material Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000012466 permeate Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- -1 C ... Inorganic materials 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000012465 retentate Substances 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2313/00—Details relating to membrane modules or apparatus
- B01D2313/14—Specific spacers
- B01D2313/146—Specific spacers on the permeate side
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2319/00—Membrane assemblies within one housing
- B01D2319/02—Elements in series
- B01D2319/025—Permeate series
-
- B01D29/0056—
-
- B01D29/009—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
- B01D29/01—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements
- B01D29/03—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements self-supporting
- B01D29/035—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements self-supporting with curved filtering elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/15—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces
- B01D33/17—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with rotary filtering tables
- B01D33/19—Filters with filtering elements which move during the filtering operation with rotary plane filtering surfaces with rotary filtering tables the table surface being divided in successively tilted sectors or cells, e.g. for discharging the filter cake
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
- B01D63/06—Tubular membrane modules
- B01D63/066—Tubular membrane modules with a porous block having membrane coated passages
Abstract
Disclosed is a filtering element for nano-filtration, ultra-filtration, micro-filtration or reverse osmosis (I), for filtering a fluid, gaseous or liquid medium using tangential separation . The filter element has non circular passages for increased surface area and non-aligned aligned passages for greater mechanical strength of the substrate. The filtering element comprises a rigid cylindrical porous substrate (1) having a longitudinal central axis (A) and including a plurality of channels (C01, C11, C12... C21, C22... Cn1, Cn2...) for circulating the fluid medium to be filtered, with a view to recovering a filtrate at the periphery (11) of the substrate (1). The channels (C01, C11, C12... C21, C22... Cn1, Cn2) are arranged in the substrate (1) parallel to the central axis (A) thereof and defining at least three filtering rings (F1, F2...Fn). The three rings closest to the periphery of the substrate, referred to as the rings of row n, n-1 and n-2, there is at least one substantial alignment of three adjacent axes selected from among the axes (Y, Y1, Y2...Yn, Y11,... Y21..., Yn1...) of the passage and linking corridors, and the axes (X, X1... Xn, X11,... X21..., Xn1) of the channels. When the filtering element has more than three filtering rings, at least one of the rings closest to the periphery of the substrate, referred to as the rings of row n, n-1 and n-2, has a number of channels which is not a multiple of the number of channels of the ring closest to the centre of the substrate, referred to as the ring of row 1. greater mechanical strength of the substrate. The filtering element comprises a rigid cylindrical porous substrate (1) having a longitudinal central axis (A) and including a plurality of channels (C01, C11, C12... C21, C22... Cn1, Cn2...) for circulating the fluid medium to be filtered, with a view to recovering a filtrate at the periphery (11) of the substrate (1). The channels (C01, C11, C12... C21, C22... Cn1, Cn2) are arranged in the substrate (1) parallel to the central axis (A) thereof and defining at least three filtering rings (F1, F2...Fn). The three rings closest to the periphery of the substrate, referred to as the rings of row n, n-1 and n-2, there is at least one substantial alignment of three adjacent axes selected from among the axes (Y, Y1, Y2...Yn, Y11,... Y21..., Yn1...) of the passage and linking corridors, and the axes (X, X1... Xn, X11,... X21..., Xn1) of the channels. When the filtering element has more than three filtering rings, at least one of the rings closest to the periphery of the substrate, referred to as the rings of row n, n-1 and n-2, has a number of channels which is not a multiple of the number of channels of the ring closest to the centre of the substrate, referred to as the ring of row 1.
Description
NOVEL SHAPE OF FILTERING ELEMENTS
The present invention relates to the technical field of tangential
separation using filtration elements suitable for ensuring the separation of
the molecules or of the particles contained in a fluid medium to be treated.
The subject of the invention targets, more specifically, new filtration
elements comprising a rigid porous support in which circulation channels for
the fluid to be filtered are arranged, said support having an original
geometry.
The subject of the invention finds a particularly advantageous
application in the field of filtration in the broad sense, and especially
nanofiltration, ultrafiltration, microfiltration or reverse osmosis.
In the prior art, many filtration elements are known that are produced
from a support of tubular or flat nature. Filtration elements of tubular type
comprising a porous support, for example made of an inorganic material, for
example made of ceramic, in which a series of channels is arranged, have in
particular been proposed. This support may be combined with one or more
separating layers, for example made of an inorganic material, deposited on
the surface of each circulation channel and connected to one another and to
the support by sintering. These layers make it possible to adjust the filtration
power of the filtration element.
In the field of tubular filtration elements, the rigid porous support is of
elongated shape and has a transverse cross section that is usually polygonal
or circular. Many supports comprising a plurality of channels parallel to one
another and to the longitudinal axis of the porous support have already been
proposed, in particular, by the applicant. For example, filtration elements
comprising a series of non-circular channels are described in patent
application WO 93 07959 in the name of CERASIV, patent application
EP 0 780 148 in the name of CORNING, patent application WO 00/29098 in
the name of ORELIS, patents EP 0 778 073 and EP 0 778 074 in the name of
the applicant and patent applications WO 01/62370 in the name of Société
des Céramiques Techniques and FR 2898513 in the name of ORELIS. In
operation, the channels communicate, on the one hand, with an inlet
chamber for the fluid medium to be treated and, on the other hand, with an outlet chamber. The
surface of the channels is, usually, covered with at least one separating layer that ensures the
separation of the molecules or of the particles contained in the fluid medium circulating inside
the channels, in a given direction, from one end of the channels known as the inlet end to the
other end known as the outlet end. Such a filtration element produces, via a screening effect, a
separation of the molecular or particulate species of the product to be treated, insofar as all the
particles or molecules greater than the diameter of the pores of the zone of the filtration element
with which they are in contact are stopped. During the separation, the transfer of the fluid takes
place across the support and optionally the separating layer or layers when they are present, and
the fluid spreads into the porosity of the support in order to be sent to the outer surface of the
porous support. The portion of the fluid to be treated that has crossed the separating layer and
the porous support is referred to as the permeate or filtrate and is recovered by a collection
chamber surrounding the filtration element.
With a view to increasing the surface area of the channels enabling the filtration of the
fluid, it is often sought to have a large number of channels within one and the same support. Due
to the large number of channels, the number of possible arrangements of the channels with
respect to one another is large. Within this context, the applicant, concerned with offering new
filtration elements, proposes, within the context of the present disclosure, a new support
geometry.
It is an object of the invention to improve upon the prior art at least to an extent or to
provide an alternative thereto.
There is disclosed herein a filtration element for filtering a fluid medium comprising a rigid
porous support of cylindrical shape having a longitudinal central axis and comprising a plurality
of channels for the circulation of the fluid medium to be filtered with a view to recovering a
filtrate at the periphery of the support, which channels are made in the support parallel to its
central axis, said channels defining filtration crowns, of at least three in number, in each of
which:
- the channels have a noncircular transverse cross section, the transverse cross section of
each channel having an axis of symmetry that passes through the center of the support,
- two neighboring channels are separated by flow and connection paths, said flow and
connection paths having an axis of symmetry that passes through the center of the support,
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- the ratios between the hydraulic diameters of any two channels of the filtration crowns
are all within the interval 0.75-1.25,
said filtration crowns being distributed concentrically and separated from one another by a
continuous porous zone, without overlap between two adjacent crowns, and at the three crowns
closest to the periphery of the support, known as row n, n-1 and n-2 crowns, there is at least a
substantial alignment of 3 adjacent axes among the axes of the flow and connection paths and
the axes of the channels, which promotes the mechanical strength of the support, wherein when
the filtration element has more than three filtration crowns, there is at least one crown among the
three crowns closest to the periphery of the support, known as row n, n-1 and n-2 crowns, the
number of channels of which is not a multiple of the number of channels of the crown closest to
the center of the support, known as row 1 crown.
Such filtration elements which have a high transparency are highly advantageous for their
filtering capacity.
Furthermore, within the context of the disclosure, the applicant evaluated the existing
stress fields within supports comprising a series of at least 3 crowns of channels and
demonstrated that the maximum stress was at the crowns closest to the periphery of the support.
The applicant proposes to select particular positionings of the three crowns closest to the
periphery of the support, with a view to improving the mechanical performances of the filtration
element.
According to a first preferred embodiment, the substantial alignment between the axes of
the flow and connection paths and the axes of the channels which promotes the mechanical
strength of the support corresponds to the fact that at least one axis of a flow and connection
path of the crown closest to the periphery of the support, known as row n crown, is substantially
aligned with the axis of an adjacent channel of the crown of lower row n-1, said axis of the
channel itself being substantially aligned with the axis of an adjacent flow and connection path
of the crown of lower row n-2.
According to a second preferred embodiment, the substantial alignment between the axes
of the flow and connection paths and the axes of the channels, which promotes the mechanical
strength of the support, corresponds to the fact that at least one axis of a channel of the crown
closest to the periphery of the support, known as row n crown, is substantially aligned with the
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axis of an adjacent flow and connection path of the crown of lower row n-1, said axis of the
flow and connection path being itself substantially aligned with the axis of an adjacent channel
of the crown of lower row n-2.
The two embodiments above may also be combined together.
According to one further embodiment that can be combined with the preceding
embodiments, at least one axis of a flow and connection path of the crown closest to the
periphery of the support, known as row n crown, is substantially aligned with the axis of an
adjacent flow and connection path of the crown of lower row n-1, said axis of the flow and
connection path of the row n-1 crown being itself substantially aligned with the axis of an
adjacent flow and connection path of the crown of lower row n-2.
According to one further embodiment that can be combined with the preceding
embodiments, at least one axis of a channel of the crown closest to the periphery of the support,
known as row n crown, is substantially aligned with the axis of an adjacent channel of the crown
of lower row n-1, said axis of the channel of the row n-1 crown being itself substantially aligned
with the axis of an adjacent channel of the crown of lower row n-2.
What is meant by “substantially aligned”, in each of the above cases, will be defined in
the remainder of the description. Generally, this means that a certain tolerance in the alignment
may be granted, without however making the mechanical characteristics of the filtration element
fall too considerably. For example, the axes X and Y (X and Y and Y and X or Y and
n n-1 n-1 n-2 n
X and X and Y ) which are substantially aligned in accordance with the invention are
n-1 n-1 n-2
perfectly merged or form an angle of less than or equal to 3°, and preferably less than 2° and
preferentially less than 1°. In all the cases presented in the description, the perfect alignment of
the axes envisaged corresponds to the particularly preferred configuration.
A channel or path of a crown of row i and the path or channel which is closest thereto in
the neighboring crown of row i+1 or i-1 are referred to as adjacent.
According to particular embodiments that can be combined with the preceding
embodiments which will be explained in detail in the description which follows, the filtration
elements according to the invention may have one or other of the features below or any
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combination of these features, or even all of these features, when they do not exclude one
another:
on the one hand, the axis of a flow and connection path of the crown closest to the
periphery of the support, known as row n crown, is aligned with the axis of an adjacent channel
of the crown of lower row n-1, with a tolerance of ±16% and, preferably, of ±10%, of the value
of the angular sector defined by the two axes of symmetry of the flow and connection paths
delimiting said channel of the row n-1 crown and, on the other hand, said axis of the channel is
itself substantially
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aligned with the axis of an adjacent flow and connection path of the
crown of lower row n-2, with a tolerance of ±16% and, preferably, of
±10%, of the value of the angular sector defined by the two axes of
symmetry of the flow and connection paths delimiting said channel of
the row n-1 crown;
- on the one hand, the axis of a channel of the crown closest to the
periphery of the support, known as row n crown, is aligned with the
axis of an adjacent flow and connection path of the crown of lower
row n-1, with a tolerance of ±16% and, preferably, of ±10%, and
preferentially of ±5%, of the value of the angular sector defined by
the two axes of symmetry of the flow and connection paths delimiting
said channel of the row n crown and, on the other hand, said axis of
the flow and connection path is itself substantially aligned with the
axis of an adjacent channel of the crown of lower row n-2, with a
tolerance of ±16% and, preferably, of ±10%, and preferentially of
±5%, of the value of the angular sector defined by the two axes of
symmetry of the flow and connection paths delimiting said channel of
the row n-2 crown;
- on the one hand, an axis of a channel of the crown closest to the
periphery of the support, known as row n crown, is aligned with the
axis of an adjacent channel of the crown of lower row n-1, with a
tolerance of ±16% and, preferably, of ±10%, and preferentially of
±5%, of the value of the angular sector defined by the two axes of
symmetry of the flow and connection paths delimiting said channel of
the row n-1 crown, and, on the other hand, said axis of the channel
of the crown of lower row n-1 itself being substantially aligned with
the axis of an adjacent channel of the crown of lower row n-2, with a
tolerance of ±16% and, preferably, of ±10%, of the value of the
angular sector defined by the two axes of symmetry of the flow and
connection paths delimiting said channel of the row n-1 crown;
- on the one hand, the axis of a flow and connection path of the crown
closest to the periphery of the support, known as row n crown, is
aligned with the axis of an adjacent channel of the crown of lower row
n-1, with a tolerance of ±16% and, preferably, of ±10%%, and
preferentially of ±5%, of the value of the angular sector defined by
the two axes of symmetry of the flow and connection paths delimiting
said channel of the row n-1 crown and, on the other hand, said axis
of the channel is itself substantially aligned with the axis of an
adjacent flow and connection path of the crown of lower row n-2,
with a tolerance of ±16% and, preferably, of ±10%%, and
preferentially of ±5%, of the value of the angular sector defined by
the two axes of symmetry of the flow and connection paths delimiting
said channel of the row n-1 crown;
- on the one hand, the axis of a flow and connection path of the crown
closest to the periphery of the support, known as row n crown, is
aligned with the axis of an adjacent flow and connection path of the
crown of lower row n-1, with a tolerance of ±3° and, preferably, of
±2°%, and preferentially of ±1°, on the other hand, said of the flow
and connection path of the the row n-1 crown is itself substantially
aligned with the axis of an adjacent flow and connection path of the
crown of lower row n-2, with a tolerance of ±3° and, preferably, of
±2°, and preferentially of ±1°;
- the number of channels per crown is increasing from the row n-2 to n
crowns. This makes it possible in particular to have, in these last three
crowns, an even lower variability of the hydraulic diameter of the
channels from one crown to the next. Usually, the number of channels
in each of these crowns will be greater than or equal to 4 and will
increase by at least 2 channels per higher row;
- the ratios between any two transverse cross-sectional surface areas of
channels belonging to the filtration crowns are all within the interval
0.75-1.25, preferably within the interval 0.95-1.05;
- the row n, n-1 and n-2 crowns each have a number of channels that
is a multiple of an integer m and the number of axes of a flow and
connection path of the row n crown, which are substantially aligned
with the axis of an adjacent channel of the crown of lower row n-1,
with said axis of the channel itself substantially aligned with the axis
of an adjacent flow and connection path of the crown of lower row n-
2, corresponds to this integer m. Such a configuration offers a very
good burst strength of the filtration element;
- the channels of one and the same filtration crown are all identical and
preferably are spaced an equal distance apart from one another. They
are also preferably oriented in the same manner with respect to the
center of the support. Thus, the stresses exerted on the channels of
one and the same crown are more uniform;
- the widths of the flow dividers are equal within one and the same
crown and are equal from one crown to the next;
- the width of each flow divider is constant over its entire length;
- the filtration element comprises a central channel, preferably of
circular shape, and the filtration crowns are distributed concentrically
with respect to the central channel; conventionally, the expression
“central channel” means a channel having a transverse cross section
that passes through the central axis of the support and is centered
about said axis;
- the filtration crowns are distributed over concentric circles;
- all the channels of the filtration crowns have a trapezoidal or
triangular cross section;
- all the channels of the filtration crowns are, in particular, delimited by
two side walls, an outer wall, fillets and optionally an inner wall, the
fillets each having an arc-shaped profile, the radius of which is
preferably greater than or equal to 0.3 mm, and preferably belongs to
the range extending from 0.3 to 1.5 mm;
- the filtration element comprises at least four filtration crowns and
where an axis of a flow and connection path of the row n crown is
substantially aligned with the axis of an adjacent channel of the crown
of lower row n-1, with said axis of the channel itself substantially
aligned with the axis of an adjacent flow and connection path of the
- crown of lower row n-2, there is also substantial alignment between said axis of the flow
and connection path of the row n-2 crown and the axis of the adjacent flow and
connection path of the row n-3 crown;
- the support has a circular or polygonal cross section;
- the mean thickness of the porous zone closest to the central axis is less than the mean
thickness of the porous zone closest to the periphery of the support and on moving from
the central axis of the support toward its periphery, the mean thickness of a porous zone
is either identical to the next zone, or smaller;
- the surface of the channels is covered with at least one inorganic filtration layer.
Another subject of the present disclosure is the filtration installations or modules
comprising a filtration element in a housing.
Various other features will emerge from the description given below with reference to the
appended drawings which show, as nonlimiting examples, embodiments of the supports
according to the invention.
Figure 1A is a cross-sectional view, deliberately on a larger scale, of an exemplary
embodiment of a filtration element.
Figure 1B is a cross-sectional view of a filtration element, given by way of comparison,
similar to that from figure 1A, but in which the row n crown has been shifted by a rotation of
3.75° about the longitudinal axis of the support.
Figure 1C is a cross-sectional view of a filtration element, given by way of comparison,
similar to that from figure 1A, but in which the row n-2 crown has been shifted by a rotation of
11.25° about the longitudinal axis of the support.
Figure 2 is a cross-sectional view, deliberately on a larger scale, of another exemplary
embodiment of a filtration element.
Figure 3A is a cross-sectional view, deliberately on a larger scale, of another exemplary
embodiment of a filtration element.
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Figure 3B is a cross-sectional view of a filtration element similar to that from figure 3A,
but in which the row n-1 crown has been shifted by a rotation of 7.5° about the longitudinal axis
of the support.
The transverse cross section of a filtration element corresponds to its cross section taken
perpendicular to its central axis. Generally, the structure and the dimensions of the transverse
cross section are constant over the entire length of the filtration element and the geometry over
this cross section is therefore representative of the geometry of the multichannel filtration
element which has a symmetry of extrusion. Throughout the description, the concepts of angle,
thickness, cross section and displacement within the support are understood to mean in the plane
of a transverse cross section of the support. Regarding a transverse cross section of the support,
mention will be made equally of the axis of the support and the center of the support.
As emerges from the various figures 1A, 2, 3A and 3B, the inorganic filtration element I
has a shape suitable for ensuring the separation or filtration of molecules or particles contained
in a fluid medium, preferably a liquid medium, of varied nature that may or may not comprise a
solid phase. The filtration element I comprises a rigid porous support 1 consisting of a material
having a transfer resistance that is suitable for the separation to be carried out. In particular, the
support 1 is made from one or more inorganic materials, such as metal oxides (titanium dioxide,
alumina or zirconia in particular), carbon, carbide or nitride of silicon or metals. The support I is
made in an elongated shape or in the form of a pipe that extends along a longitudinal central axis
A. The porous support 1 generally has a mean hydraulic pore diameter between 2 and 12 μm.
The support 1 has a transverse cross section which may be of various shapes, for example
hexagonal or, as in the embodiments illustrated in the figures, circular. The support 1 thus has a
cylindrical outer surface 1 .
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The support 1 is arranged in order to comprise a plurality of channels
C , C , C …, C , C …, C , C … (generically referred to as C ) made
01 11 12 21 22 n1 n2 ij
parallel to the longitudinal axis A of the support. The channels are distributed
in a filtration zone of row i, it being possible for each filtration zone to
comprise one or more channels and to be separated by a porous zone. Thus,
each porous zone Z is between two filtration zones, each filtration zone
comprising a channel or a plurality of channels, when it is a question of a
filtration crown. The channels C each have a surface 2 that may be covered
with at least one separating layer, not represented, intended to be in contact
with the fluid medium to be treated circulating within the channels. The
nature of the separating layer or layers is chosen as a function of the
separating or filtration power to be obtained and forms, with the support, an
intimate connection, so that the pressure originating from the liquid medium
is transmitted to the porous support 1. This or these layers may be
deposited from, for example, suspensions containing at least one metal oxide
of the titanium dioxide, alumina or zirconia type in particular, optionally as a
mixture, and that are conventionally used in the production of mineral
filtration elements. This or these layers are subjected, after drying, to a
sintering operation which makes it possible to consolidate them and to
connect them to one another and also to the porous support 1.
In accordance with the invention, the support 1 comprises at least
three filtration crowns F , F , …F (generically referred to as F ) which are
1 2 n i
distributed concentrically. Two adjacent (i.e. successive or neighboring)
filtration crowns are separated by a continuous porous zone. A porous zone
Z is therefore inserted between two neighboring filtration crowns F. The
porous zones, which are zones of porous material in which the filtrate
circulates, are described as continuous since there is a clear delimitation
between two adjacent filtration crowns, i.e. there is no overlap, nor
intersection between two adjacent filtration crowns. In other words, a
channel of a filtration crown cannot be found, even only partly, between two
channels of an adjacent filtration crown.
Each crown constitutes a filtration zone and may be defined as a set of
channels located over a closed curve, i.e. the barycenters of these channels
are located over this curve. In the examples illustrated, the channels of one
and the same crown are located over a circle.
Within each crown, the channels have noncircular cross sections. In the
examples illustrated, the channels of the crowns are of trapezoidal shape.
More generally, the channels of the filtration crowns define sectors of these
filtration crowns, the shape of which is suitable for the filtration and
mechanical strength requirements. These channels have one wall that faces
the periphery 1 of the support (referred to as outer wall), one wall facing
the center A of the support (referred to as inner wall), and two side walls R
connecting the inner wall and the outer wall. Usually, the side walls are
connected to the inner and outer walls by fillets. In certain cases, the inner
wall could be replaced by a fillet connecting the two side walls R. The
endpoints of a wall are the points located at these two ends, just before the
fillets. For each side wall, a direction d is defined which connects these two
endpoints. Within the context of the invention, this direction d heads toward
the center of the support and the side walls R will also be referred to as
radial walls. Nevertheless, this direction d does not necessarily pass through
the center of the support. But the directions d of the two radial walls R of
one and the same channel intersect at a point located around the center of
the support, with respect to said channel, and in particular at a point D
located between said channel and the center of the support, as in the
example illustrated in figure 1A. According to the variants illustrated in the
figures, the radial walls R that participate in the definition of the contour of a
channel correspond to two straight sides and the direction d is therefore
merged with these sides. Furthermore, two channels of one and the same
crown are said to be neighboring if they have a flow and connection path P
in common. This flow and connection path P therefore constitutes a divider
separating two neighboring channels of one and the same crown.
For the remainder of the description, it is considered that the filtration
crowns and the porous zones occupy different rows which increase in the
direction of the periphery of the support. Thus, for two filtration crowns (or
porous zones) considered, the filtration crown (or respectively the porous
zone) closest to the periphery is considered to be of a higher row relative to
a filtration crown (or respectively a porous zone) closer to the center and
considered to be a filtration crown (or respectively a porous zone) of a lower
row. Thus, a crown of given row is surrounded by the crown or crowns of
higher row.
In the example illustrated in figure 1A, the support comprises three
filtration crowns F to F and a central channel C , which makes it possible
1 3 01
in particular to avoid an accumulation of material at the center of the
support. In the example illustrated, the central channel C is of circular
shape, but a shape of polygonal or other type could also be provided. On the
other hand, each filtration crown is composed of a series of noncircular
channels. The central channel is separated from the filtration crown of row
1, by a porous zone Z . The filtration crowns F and F are separated by a
0 1 2
porous zone Z and the filtration crowns F and F are separated by a porous
1 2 3
zone Z . In each filtration crown, the channels are separated by flow dividers
for the filtrate, generically referred to as P and P in the row 1 crown, P in
the row 2 crown and P in the row 3 crown. These flow dividers P , P and
3 1 2
P enable the filtrate to travel inside the support from one porous zone to
the next, up to the peripheral zone Zp, which is also porous, in order to
emerge on the outer surface 1 of the support 1. In the example illustrated
in figure 1A, the channels of the crown F , closest to the periphery of the
support, have an arch-shaped profile as described in patent FR2741821 in
the name of the applicant. But provision could just as well be made for the
width of the zone Zp located between the outer wall of a channel of the
crown F and the periphery 1 of the support to be constant.
In order to facilitate the transport of the filtrate, said flow and
connection paths P , P and P have an axis of symmetry, which passes
1 2 3
through the center A of the support. These axes of symmetry are referred to
generically as Y and Y in the row 1 crown, Y in the row 2 crown and Y in
1 2 3
the row 3 crown. The paths P and the axes of symmetry Y are assigned
subscript values in the following manner: within a row i crown, the flow and
connection path located between the channels C and C is referred to as
ij i(j+1)
P and its axis of symmetry is Y .
ij ij
The various channels of the filtration crowns also have an axis of
symmetry generically referred to as X which passes through the center of
the support, with a view to optimizing the filtering surface area. These axes
of symmetry are generically referred to as X in the row 1 crown, X in the
row 2 crown and X in the row 3 crown and, according to a more specific
naming, they bear the same subscript values as the channel of which they
are the axis.
These filtration crowns F to F are distributed as follows on moving
from the central axis A toward the periphery 1 of the support:
- the row 1 filtration crown F consists of 8 identical channels C to
1 11
C of trapezoidal shape,
- the row 2 filtration crown F consists of 16 identical channels C to
2 21
C of trapezoidal shape,
- the row 3 filtration crown F consists of a crown of 24 identical
channels C to C of trapezoidal shape.
31 324
The number of channels present in each filtration crown therefore
increases on moving from the center toward the periphery of the support.
The channels of one and the same crown are described as identical,
given that they have in particular the same shape, the same cross section
and the same hydraulic diameter to within small variations due to the
manufacturing process. According to a precise embodiment, the outer
diameter of the support could be 41 mm, and the mean hydraulic diameters
(corresponding to the arithmetic mean of all the hydraulic diameters of the
channels of a crown) over the crowns of rows 1, 2 and 3, could be 4.00 –
4.04 – 4.00 respectively and 4.00 mm for the central channel C . There is
therefore also a small variability of the hydraulic diameters from one crown
to the next. The same is true for the transverse cross-sectional surface
areas. The mean transverse cross-sectional surface areas (corresponding to
the arithmetic mean of all the transverse cross-sectional surface areas of the
channels of a crown) over the crowns of rows 1, 2 and 3, are 14.7 – 14.5 –
13.8 respectively and 12.5 mm for the central channel C .
The filtration crowns F to F are distributed concentrically with respect
to the central channel C . The barycenters of the channels C C …. C of
01 11, 12 18
the row 1 crown F are located over a circle coaxial to the central axis A, this
coaxial circle having a smaller diameter with respect to the coaxial circle over
which the barycenters of the channels C C …. C of the row 2 filtration
21, 22 216
crown F are located and so on.
According to one essential feature of the invention, in the embodiment
presented in figure 1A, at least one axis Y of a flow and connection path
P of the row 3 crown F closest to the periphery 1 of the support 1 is
3 3 1
substantially aligned with the axis X of an adjacent channel of the crown F
of lower row 2, said axis X of the channel itself being substantially aligned
with the axis Y of an adjacent flow and connection path P of the crown F
1 1 1
of lower row 1. Within the context of the invention, it is considered that the
axis Y of a flow path P is substantially aligned with the axis of symmetry X of
a channel, when the two axes are merged or form an angle having an
angular value of less than ±16% and, preferably, of less than ±10%, and in
particular of less than ±5%, of the value of the angular sector defined by the
two axes of symmetry of the flow and connection paths delimiting said
channel. The angular sector defined by two neighboring axes Y corresponds,
for example, to an angle of 5° to 60°. In particular, the two axes X and Y
n-1 n
on the one hand and Y and X on the other hand which are substantially
n-2 n-1
aligned in accordance with the invention are perfectly merged or form an
angle of less than or equal to 3°, and preferably less than 2° and
preferentially less than 1°. According to one preferred variant, Y , X and
n n-1
Y are perfectly aligned. The double alignment in accordance with the
invention allows the filtration element to withstand high operating pressures.
Indeed, the applicant observed that the maximum stresses located in the
zone where the flow and connection path P emerges from the row 3 crown
level with the middle of the outer wall of the channel of the row 2 crown,
were compensated for by the fact that the flow and connection path P of
the crown F of row 1 emerged substantially in the middle of the inner wall
of this same channel of the row 2 crown.
In figure 1A, given that in one and the same crown and therefore in
particular over the crown F , all the channels are identical and regularly
spaced apart from one another, the angular sectors defined by two axes of
symmetry Y (for example Y and Y ) of the flow paths P surrounding a
2 21 22 2
channel of the row 2 crown are all equal. In the example illustrated, these
angular sectors are equal to 15°. Furthermore, in figure 1A, an exact
double superimposition of axes in accordance with the invention is observed,
on 8 occasions, over a transverse cross section of the support. The number
of channels present over each of the crowns F to F is a multiple of this
number 8. There is strict alignment:
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F closest to the periphery 1 of the
32 3 1
support 1 and the axis X of the adjacent channel C of the crown
22 22
F of lower row 2, and, on the other hand, between the axis X of
2 22
the channel C and the axis Y of the adjacent flow and connection
22 11
path P of the crown F of lower row 1, and
11 1
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
3 24
channel C of the crown F of lower row 2, and, on the other hand,
24 2
between the axis X of the channel C and the axis Y of the
24 24 12
adjacent flow and connection path P of the crown F of lower row
12 1
1, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
38 3 26
channel C of the crown F of lower row 2, and, on the other hand,
26 2
between the axis X of the channel C and the axis Y of the
26 26 13
adjacent flow and connection path P of the crown F of lower row
13 1
1, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
311 3 28
channel C of the crown F of lower row 2, and, on the other hand,
28 2
between the axis X of the channel C and the axis Y of the
28 28 14
adjacent flow and connection path P of the crown F of lower row
14 1
1, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
314 3 210
channel C of the crown F of lower row 2, and, on the other hand,
210 2
between the axis X of the channel C and the axis Y of the
210 210 15
adjacent flow and connection path P of the crown F of lower row
1
1, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
317 3 212
channel C of the crown F of lower row 2, and, on the other hand,
212 2
between the axis X of the channel C and the axis Y of the
212 212 16
adjacent flow and connection path P of the crown F of lower row
16 1
1, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
320 3 214
channel C of the crown F of lower row 2, and, on the other hand,
214 2
between the axis X of the channel C and the axis Y of the
214 214 17
adjacent flow and connection path P of the crown F of lower row
17 1
1, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 3 crown F and the axis X of the adjacent
323 3 216
channel C of the crown F of lower row 2, and, on the other hand,
216 2
between the axis X of the channel C and the axis Y of the
216 216 18
adjacent flow and connection path P of the crown F of lower row
18 1
It should also be noted that the transverse cross section represented in
figure 1A has 4 axes of symmetry.
In the example illustrated, there is also alignment between the adjacent
axes X of various channels of crowns 1, 2 and 3, on 8 occasions (at
channels C , C and C ; channels C , C and C ; channels C , C
11 21 31 12 23 34 13 25
and C ; channels C , C and C ; channels C , C and C ; channels
37 14 27 310 15 29 313
C , C and C ; channels C , C and C and channels C , C and
16 211 316 17 213 319 18 215
C ).
In order to demonstrate the contribution of the invention, a study was
carried out with Abaqus software in order to evaluate the stress field that
exists within the support, when a stress corresponding to a pressure of 100
MPa is imposed in each of the channels. It is important to note that the
distribution of the stresses is strictly the same, whatever internal force is
applied. The conclusions drawn from its calculations are therefore strictly
independent of the internal pressure value used. A support in accordance
with figure 1A was compared with supports in accordance with figures 1B
and 1C produced by way of comparison. Figures 1B and 1C are identical in
every respect to figure 1A, except that a rotation of a given angle with
respect to the longitudinal axis A has been applied, either to the row 3
crown, or to the row 1 crown. In figure 1B, the row 3 crown has been
shifted by a rotation of 3.75° about the longitudinal axis A of the support,
whereas in figure 1C it is the row 1 crown that has been shifted by a
rotation of 11.25° about the longitudinal axis A of the support. Indeed, in
figure 1B, whereas the axes Y , X and Y were aligned in figure 1A,
32 22 11
the axes X and Y are still aligned but are shifted by 3.75° with respect to
22 11
the axis Y . Similarly, in figure 1C, the axes X and Y are still aligned
32 22 32
but are shifted by 11.25° with respect to the axis Y . The maximum stress
calculated for figure 1A is 71.5 MPa, versus 77.4 MPa and 80.7 MPa
respectively for figures 1B and 1C. It therefore appears that the new
arrangement of the channels in the crowns of rows n to n-2 (corresponding
to rows 3 to 1 in figures 1A to 1C) in accordance with the invention
significantly reduces the local zones of weakness. The stresses observed are
linked to the pressure exerted by the fluid inside the channels, in particular in
the case of fluid hammer. This internal pressure tends to deform and
therefore to stress the material. The geometric configuration according to the
invention makes it possible to obtain a more balanced distribution of the
stresses within the cross section of the support. The fact, for example, of
finding over the cross section m times the optimal configuration, at a regular
angle interval, is in step with this balancing which limits the shearing effects.
The more unbalanced a configuration, the more there is a combination of
zones of high rigidity (where all the radial dividers would be aligned) with
zones of low rigidities (no alignment) and therefore of high deformations,
which leads to a greater shearing effect between these two zones.
Figure 2 illustrates another exemplary embodiment of the invention in
which the support 1 comprises 4 filtration crowns F to F . Here too, the
support also comprises a central channel C of circular shape in the example
illustrated, about which the filtration crowns F to F are distributed
concentrically. These filtration zones are distributed as follows on moving
from the central axis A toward the periphery 1 of the support 1:
- the row 1 filtration crown F consists of 6 identical channels C to
1 11
C of trapezoidal shape,
- the row 2 filtration crown F consists of 10 identical channels C to
2 21
C of trapezoidal shape,
- the row 3 filtration crown F consists of 15 identical channels C to
3 31
C of trapezoidal shape, and
- the row 4 filtration crown F consists of 20 identical channels C to
4 41
C of trapezoidal shape.
According to a precise embodiment, the outer diameter of the support
could be 25 mm, and the mean hydraulic diameters over the crowns of rows
1, 2, 3 and 4, could be 2.30 – 2.32 – 2.31 – 2.28 respectively and 2.30 mm
for the central channel C . There is therefore also a small variability of the
hydraulic diameters from one crown to the next. The same is true for the
transverse cross-sectional surface areas. The mean transverse cross-
sectional surface areas (corresponding to the arithmetic mean of all the
transverse cross-sectional surface areas of the channels of a crown) over the
crowns of rows 1, 2, 3 and 4, are 4.6 – 4.8 – 4.7 – 4.5 respectively and
4.2 mm for the central channel C .
In figure 2, the crowns of rows n to n-2 correspond to the crowns of
rows 2 to 4. In this implementation example, an exact double
superimposition of axes in accordance with the essential feature of the
invention is observed, on 5 occasions, over a transverse cross section of the
support. The number of channels present over each of the crowns F to F is
a multiple of this number 5. On the other hand, the number of channels
present over each of the crowns F to F (respectively 10, 15 and 20) is not
a multiple of 6 corresponding to the number of channels of the crown F
closest to the center of the support.
There is strict alignment:
- on the one hand, between the axis Y of the flow and connection
path P of the row 4 crown F closest to the periphery 1 of the
42 4 1
support 1 and the axis X of the adjacent channel C of the crown
32 32
F of lower row 3, and, on the other hand, between the axis X of
3 32
the channel C and the axis Y of the adjacent flow and connection
32 21
path P of the crown F of lower row 2, and
21 2
- on the one hand, between the axis Y of the flow and connection
path P of the row 4 crown F and the axis X of the adjacent
46 4 35
channel C of the crown F of lower row 3, and, on the other hand,
3
between the axis X of the channel C and the axis Y of the
35 23
adjacent flow and connection path P of the crown F of lower row
23 2
2, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 4 crown F and the axis X of the adjacent
410 4 38
channel C of the crown F of lower row 3, and, on the other hand,
38 3
between the axis X of the channel C and the axis Y of the
38 38 25
adjacent flow and connection path P of the crown F of lower row
2
2, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 4 crown F and the axis X of the adjacent
414 4 311
channel C of the crown F of lower row 3, and, on the other hand,
311 3
between the axis X of the channel C and the axis Y of the
311 311 27
adjacent flow and connection path P of the crown F of lower row
27 2
2, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 4 crown F and the axis X of the adjacent
418 4 314
channel C of the crown F of lower row 3, and, on the other hand,
314 3
between the axis X of the channel C and the axis Y of the
314 314 29
adjacent flow and connection path P of the crown F of lower row
29 2
It should also be noted that the transverse cross section of the support
1 represented in figure 2 has an axis of symmetry B.
In the example illustrated, there is also alignment between the adjacent
axes Y of various flow and transport paths of crowns 2, 3 and 4, on 5
occasions (at axes Y , Y and Y axes Y , Y and Y ; axes Y , Y
22 33 44; 24 36 48 26 39
and Y ; axes Y , Y and Y ; and axes Y , Y and Y ).
412 28 312 416 210 315 420
Figure 3A illustrates another exemplary embodiment of the invention
in which the support comprises five filtration crowns F to F and a central
channel C of circular shape, although here too a shape of polygonal or
other type could also be provided. The central channel is separated from the
filtration crown of row 1, by a porous zone Z . The filtration crowns F and
F are separated by a porous zone Z the filtration crowns F and F are
2 1, 2 3
separated by a porous zone Z , the filtration crowns F and F are separated
2 3 4
by a porous zone Z and the filtration crowns F and F are separated by a
3 4 5
porous zone Z . The filtration crowns F to F , which are concentric with
4 1 5
respect to the central channel C , are distributed as follows on moving from
the central axis A toward the periphery 1 of the support:
- the row 1 filtration crown F consists of 7 identical channels C to
1 11
C of trapezoidal shape,
- the row 2 filtration crown F consists of 13 identical channels C to
2 21
C of trapezoidal shape,
- the row 3 filtration crown F consists of 21 identical channels C to
3 31
C of trapezoidal shape,
- the row 4 filtration crown F consists of 24 identical channels C to
4 41
C of trapezoidal shape, and
- the row 5 filtration crown F consists of 27 identical channels C to
51
C of trapezoidal shape.
According to a precise embodiment, the outer diameter of the support
could be 25 mm, and the mean hydraulic diameters over the crowns of rows
1, 2, 3, 4 and 5 could be 1.57 – 1.60 – 1.60 – 1.62 – 1.62 respectively and
1.80 mm for the central channel C . There is therefore also a small
variability of the hydraulic diameters from one crown to the next. The same
is true for the transverse cross-sectional surface areas. The mean transverse
cross-sectional surface areas (corresponding to the arithmetic mean of all the
transverse cross-sectional surface areas of the channels of a crown) over the
crowns of rows 1, 2, 3, 4 and 5 are 2.1 – 2.1 – 2.2 – 2.2 – 2.3 respectively
and 2.5 mm for the central channel C .
In figure 3A, the crowns of rows n to n-2 correspond to the crowns of
rows 5 to 3. In this implementation example, an exact double
superimposition of axes in accordance with the essential feature of the
invention is observed, on 3 occasions, over a transverse cross section of the
support. The number of channels present over each of the crowns F to F is
a multiple of this number 3. On the other hand, the number of channels
present over the crowns F to F (respectively 24 and 27) is not a multiple of
7 corresponding to the number of channels of the crown F closest to the
center of the support.
There is strict alignment:
- on the one hand, between the axis Y of the flow and connection
path P of the row 5 crown F closest to the periphery 1 of the
55 5 1
support 1 and the axis X of the adjacent channel C of the crown
45 45
F of lower row 4, and, on the other hand, between the axis X of
4 45
the channel C and the axis Y of the adjacent flow and connection
45 34
path P of the crown F of lower row 3, and
34 3
- on the one hand, between the axis Y of the flow and connection
path P of the row 5 crown F and the axis X of the adjacent
514 5 413
channel C of the crown F of lower row 4, and, on the other hand,
413 4
between the axis X of the channel C and the axis Y of the
413 413 311
adjacent flow and connection path P of the crown F of lower row
311 3
3, and
- on the one hand, between the axis Y of the flow and connection
path P of the row 5 crown F and the axis X of the adjacent
523 5 421
channel C of the crown F of lower row 4, and, on the other hand,
421 4
between the axis X of the channel C and the axis Y of the
421 421 318
adjacent flow and connection path P of the crown F of lower row
318 3
3.
It should also be noted that the transverse cross section of the support
1 represented in figure 3A has an axis of symmetry B . At this axis of
symmetry C which coincides with the axes Y , X and Y , there is also
523 421 318
perfect alignment between the axis of the path separating the channels C
and C of the row 2 crown and the axis X of the path separating the
211 318
channels C and C of the crown of higher row 3, which axis is itself
318 319
aligned with the axes Y and X .
523 421
In the example illustrated, there is also alignment between the adjacent
axes X of various channels of crowns 3, 4 and 5, on 3 occasions (at
channels C , C and C ; channels C , C and C and channels C ,
31 41 51 38 49 510 315
C and C ).
417 519
Furthermore, in the example illustrated in figure 3A, the thickness of
each of the filtration zones Z to Z and of the peripheral zone Zp are not all
identical. In the example illustrated, for each of the filtration zones, the
centripetal points (i.e. the points closest to the center A) of each channel of
one and the same filtration crown are located over a circle, the center of
which is the center of the support, this circle corresponding to the inner
envelope of the filtration crown in question. Similarly, for each of the
filtration zones, the centrifugal points (i.e. the points closest to the periphery
1 of the support) of each channel of one and the same filtration crown are
located over a circle, the center of which is the center of the support, this
circle corresponding to the outer envelope of the filtration crown in question.
Thus, the outer envelope and inner envelope delimiting each porous zone are
two concentric circles and each porous zone is therefore of constant
thickness. The distance (corresponding to the thickness e of the porous
zone Z ) separating the channel central C from the neighboring filtration
0 01
crown, namely the filtration crown F , is smaller than the distance
(corresponding to the thickness e of the porous zone Z ) separating the
z4 4
last filtration crown F from the neighboring filtration crown in the direction
of the center of the support, namely the fourth filtration crown F . This
increase in the thickness of at least some of the porous zones on moving
away from the central axis of the support is carried out in order to minimize
the effect of the pressure exerted by the retentate, or by hydraulic accidents
caused by the operation of the installation such as fluid hammers. For this, in
the example illustrated, starting from the third porous zone Z , if two
successive porous zones are considered, the ratio between the mean
thickness of the outermost porous zone to the mean thickness of the closest
porous zone, on moving toward the center of the support, is always greater
than 1. In the example illustrated in figure 3A, the porous zones Z , Z and
Z have an identical thickness. Starting from the porous zone Z , the mean
thickness of the filtration zones increases on moving toward the periphery 1
of the support. The e /e and e /e thickness ratios are between 1.14
Z3 Z2 Z4 Z3
and 1.17.
So as to further reinforce the mechanical strength of the filtration
element, it is possible to make provision, as in the example illustrated in
figure 3A, for the peripheral zone Zp separating the last filtration crowns F
from the outer surface 1 of the support 1 to also be greater than the mean
thickness of the porous zone Z . Nevertheless, according to one variant that
is not preferred, provision could also be made for this peripheral porous zone
Zp to have a thickness identical to the thickness of the porous zone Z . In
the example illustrated in figure 3A, the mean thickness of the peripheral
zone Zp corresponds to around 1.13 × the mean thickness of the porous
zone Z
Figure 3B is identical in every respect to figure 3A, except that a
rotation of an angle of 7.5° with respect to the longitudinal axis A has been
applied to the row 4 crown. Figure 3B illustrates another embodiment of
the invention in which there is alignment between at least one axis X of a
channel of the row 5 crown, an axis Y of an adjacent flow and connection
path of the crown of lower row 4 and the axis of an adjacent channel X of
the crown of lower row 3. Indeed, in the example illustrated, there is strict
alignment:
- between the axis X of the channel C of the row 5 crown F
526 526 5
closest to the periphery 1 of the support 1, the axis Y of the
1 423
adjacent flow and connection path P adjacent of the crown F of
423 4
lower row 4, and the axis X of the channel C of the crown F of
321 321 3
lower row 3, and
- between the axis X of the channel C of the crown F of row 5, the
58 58 5
axis Y of the adjacent flow and connection path P of the crown F
47 47 4
of lower row 4, and the axis X of the channel C of the crown F of
37 37 3
lower row 3, and
- between the axis X of the channel C of the crown F of row 5,
517 517 5
the axis Y of the adjacent flow and connection path P of the
415 415
crown F of lower row 4, and the axis X of the channel C of the
4 314 314
crown F of lower row 3.
In the example illustrated, there is also alignment between the adjacent
axes Y of various flow and connection paths P of crowns 3, 4 and 5: at the
paths P , P and P the axes Y , Y and Y are aligned. There is
317 419 521 317 419 521
also alignment of the axes Y , Y , Y at the paths P , P and P , and
53 43 33 53 43 33
also of the axes Y , Y and Y at the paths P , P and P .
512 411 311 512 411 311
The transverse cross section of the support 1 also has an axis of symmetry
B ’’.
A study was carried out with Abaqus software in order to evaluate the
stress fields that exist within the support, when a stress corresponding to a
pressure of 100 MPa is imposed in each of the channels. The maximum
stress calculated for figure 3A is 56.1 MPa, and 56.2 MPa for figure 3B.
Within the context of the invention, as illustrated in figures 1A, 2, 3A
and 3B, the filtration zones may correspond exclusively to a single central
channel C and to crowns of channels as defined within the context of the
invention and distributed concentrically with respect to the central axis of the
support. Nevertheless, various variations may be provided. In particular, the
single central channel may be eliminated or replaced by a set of channels
arranged as petals starting from the central axis A of the support 1. Or
alternatively, when the support comprises more than three filtration crowns,
provision may be made for the three crowns closest to the periphery of the
support not to be overlapped whereas the others closer to the center of the
support are overlapped. Provision may also be made for all the crowns
present not to be overlapped, as in the examples illustrated.
Advantageously, provision will be made, for all the channels, including
the central channel, irrespective of the two channels taken in pairs, for the
ratio between their hydraulic diameters to be within the interval 0.75-1.25, or
even within the interval 0.95-1.05 and/or for the ratio between their
transverse cross-sectional surface areas to be within the interval 0.75-1.25,
or even within the interval 0.95-1.05.
Similarly, within the context of the invention, as illustrated in figures
1A, 2, 3A and 3B, the channels of the various crowns are advantageously
arranged at regular and identical intervals over their respective crown, but
other configurations could also be provided. Furthermore, it’ll be noted that
when all the channels are identical within one and the same crown, which is
the case in figures 1A, 2, 3A and 3B, they are all positioned in an identical
manner over the crown, taking into account the requirements in terms of
symmetry of the channels and of the flow and connection paths.
According to another feature illustrated in the various exemplary
embodiments of the invention, the flow dividers P have, preferably, within
one and the same crown, substantially identical thicknesses. According to
one embodiment, in particular illustrated in figures 1A, 2, 3A and 3B,
provision is made for the width of the flow paths P made between two
neighboring channels of a crown to be constant over their entire length. This
width is also identical from one filtration crown to the next. Indeed, the
applicant has observed that the width variations of the paths for transporting
the permeate, as described in patent applications WO 93 07959 in the name
of CERASIV and EP 0 780 148 in the name of CORNING, inevitably reveal
points of small width which systematically constitute points of weakness with
regard to the mechanical stresses undergone by the filtration element. The
use of paths for transporting the permeate toward the periphery that are of
constant width makes it possible to optimize the mechanical characteristics of
the filtration element. Indeed, if a transport path of constant width and a
transport path having a width that increases from the center toward the
periphery of the support are compared, while keeping the cross section and
the number of channels which define these paths constant, the smallest
width of the variable-width path is smaller than the width of the constant-
width path and this point of smaller width thus becomes a point of
mechanical weakness. The choice of a flow path of constant thickness also
makes it possible to obtain a better manufacturing efficiency since the
extrusion pressures are more uniform.
The width of a flow path can be defined in the following manner: within
each crown, the channels have noncircular cross sections. In the examples
illustrated, the channels of the crowns are of trapezoidal shape. They have
one wall that faces the periphery 1 of the support (referred to as the outer
wall), one wall that faces the center A of the support (referred to as the
inner wall), and two side walls connect the inner wall and the outer wall.
Usually, the side walls are connected to the inner and outer walls by fillets.
In certain cases, the inner wall could be replaced by a fillet connecting the
two side walls R. A radial wall consists of a straight line segment connected
by fillets to the inner and outer walls of the channel that it delimits. The
width of a flow path is understood to be the width of the path over the part
corresponding to these straight line segments which is located between the
fillets.
Claims (46)
1. A filtration element for filtering a fluid medium comprising a rigid porous support of cylindrical shape having a longitudinal central axis and comprising a plurality of channels for the circulation of the fluid medium to be filtered with a view to recovering a filtrate at the periphery of the support, which channels are made in the support parallel to its central axis, said channels defining filtration crowns, of at least three in number, in each of which: - the channels have a noncircular transverse cross section, the transverse cross section of each channel having an axis of symmetry that passes through the center of the support, - two neighboring channels are separated by flow and connection paths, said flow and connection paths having an axis of symmetry that passes through the center of the support, - the ratios between the hydraulic diameters of any two channels of the filtration crowns are all within the interval 0.75-1.25, said filtration crowns being distributed concentrically and separated from one another by a continuous porous zone, without overlap between two adjacent crowns, and at the three crowns closest to the periphery of the support, known as row n, n-1 and n-2 crowns, there is at least a substantial alignment of 3 adjacent axes among the axes of the flow and connection paths and the axes of the channels, which promotes the mechanical strength of the support, wherein when the filtration element has more than three filtration crowns, there is at least one crown among the three crowns closest to the periphery of the support, known as row n, n-1 and n-2 crowns, the number of channels of which is not a multiple of the number of channels of the crown closest to the center of the support, known as row 1 crown.
2. The filtration element as claimed in claim 1, in which the ratios between the hydraulic diameters of any two channels of the filtration crowns are all within the interval 0.95-1.05.
3. The filtration element as claimed in claim 1 or claim 2, wherein at least one axis of a flow and connection path of the crown closest to the periphery of the support, known as row n crown, is substantially aligned with the axis of an adjacent channel of the crown of lower row n- 1, said axis of the channel itself being substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-2. (8880359_1):SPM
4. The filtration element as claimed in claim 3, wherein, on the one hand, the axis of a flow and connection path of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of an adjacent channel of the crown of lower row n-1, with a tolerance of ±16% of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n-1 crown and, on the other hand, said axis of the channel is itself substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-2, with a tolerance of ±16% of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n-1 crown.
5. The filtration element as claimed in claim 4, wherein the axis of a flow and connection path of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of an adjacent channel of the crown of lower row n-1 with a tolerance of ±10% of the value of the angular sector defined by the two axes of symmetry of the flow and connection path delimiting said channel of the row n-1 crown.
6. The filtration element as claimed in claim 5, wherein the tolerance is ±5%.
7. The filtration element as claimed in any one of claims 4 to 6, wherein the axis of the channel is itself substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-2 with a tolerance of ±10% of the value of the angular sector defined by the two axes of symmetry of the flow and connection path delimiting said channel of the row n-1 crown.
8. The filtration element of claim 7, in which the tolerance is ±5%.
9. The filtration element as claimed in any one of claims 4 to 8, comprising at least four filtration crowns and in that for at least one axis of a flow and connection path of the crown of row n, which is substantially aligned with the axis of an adjacent channel of the crown of lower row n-1, with said axis of the channel itself substantially aligned with the axis (Y ) of an adjacent flow and connection path of the crown of lower row n-2, there is also substantial alignment between said axis of the flow and connection path of the crown of row n-2 and the axis of the adjacent flow and connection path of the crown of row n-3. (8880359_1):SPM
10. The filtration element as claimed in claim 1, wherein the substantial alignment between the axes of the flow and connection paths and the axes of the channels, which promotes the mechanical strength of the support, corresponds to the fact that at least one axis (X ) of a channel of the crown closest to the periphery of the support, known as row n crown, is substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-1, said axis of the flow and connection path being itself substantially aligned with the axis of an adjacent channel of the crown of lower row n-2.
11. The filtration element as claimed in claim 10, wherein, on the one hand, the axis of a channel of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of an adjacent flow and connection path of the crown of lower row n-1, with a tolerance of ±16%, of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n crown and, on the other hand, said axis of the flow and connection path is itself substantially aligned with the axis of an adjacent channel of the crown of lower row n-2, with a tolerance of ±16% of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n-2 crown.
12. The filtration element as claimed in claim 11, wherein the axis of a channel of the crown closest to the periphery of the support, known as row n crown is aligned with the axis of the adjacent flow and connection path of the crown of lower row n-1 with a tolerance of ±10% of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n crown.
13. The filtration element as claimed in claim 12, wherein the tolerance is ±5%.
14. The filtration element as claimed in any one of claims 11 to 13, wherein the axis of the flow and connection path is substantially aligned with the axis of an adjacent channel of the crown of lower row n-2 with a tolerance of ±10% of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n-2 crown.
15. The filtration element as claimed in claim 14, wherein the tolerance is ±5%. (8880359_1):SPM
16. The filtration element as claimed in any one of the preceding claims, wherein at least one axis of a flow and connection path of the crown closest to the periphery of the support, known as row n crown, is substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-1, said axis of the flow and connection path itself being substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-2.
17. The filtration element as claimed in claim 16, wherein, on the one hand, the axis of a flow and connection path of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of an adjacent flow and connection path of the crown of lower row n-1, with a tolerance of ±3° and on the other hand, said axis of the flow and connection path is itself substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-2, with a tolerance of ±3°.
18. The filtration element as claimed in claim 17, wherein the axis of a flow and connection path of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of an adjacent flow and connection path of the crown of lower row n-1 with a tolerance of ±2°.
19. The filtration element as claimed in claim 18, in which the tolerance is ±1°.
20. The filtration element as claimed in any one of claims 17 to 19, in which the axis of the flow and connection path is substantially aligned with the axis of the adjacent row and connection path of the crown of lower row n-2 with a tolerance of ±2°.
21. The filtration element as claimed in claim 20, in which the tolerance is ±1°.
22. The filtration element as claimed in any one of the preceding claims, wherein at least one axis of a channel of the crown closest to the periphery of the support, known as row n crown, is substantially aligned with the axis of an adjacent channel of the crown of lower row n-1, said axis of the channel itself being substantially aligned with the axis of an adjacent channel of the crown of lower row n-2. (8880359_1):SPM
23. The filtration element as claimed in claim 22 wherein, on the one hand, an axis of a channel of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of an adjacent channel of the crown of lower row n-1, with a tolerance of ±16% of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n-1 crown, said axis of the channel of the crown of lower row n-1 itself being substantially aligned with the axis of an adjacent channel of the crown of lower row n-2, with a tolerance of ±16%of the value of the angular sector defined by the two axes of symmetry of the flow and connection paths delimiting said channel of the row n-1 crown.
24. The filtration element as claimed in claim 23, wherein the axis of the channel of the crown closest to the periphery of the support, known as row n crown, is aligned with the axis of the adjacent channel of the crown of lower row n-1, with a tolerance of ±10% of the value of the angular sector defined by the two axes of symmetry of the flow and connection path delimiting the channel of the row n-1 crown.
25. The filtration element as claimed in claim 24, in which the tolerance is ±5%.
26. The filtration element as claimed in any one of claims 23 to 25, wherein the axis of the channel of the crown of lower row n-1 is substantially aligned with the axis of the adjacent channel of the crown of lower row n-2 with a tolerance of ±10% of the value of the angular sector defined by the two axes of symmetry of the flow and connection path delimiting the said channel of the row n-1 crown.
27. The filtration element as claimed in claim 26, wherein the tolerance is ±5%.
28. The filtration element as claimed in any one of the preceding claims, wherein the number of channels per crown is increasing from the row n-2 to n crowns.
29. The filtration element as claimed in any one of the preceding claims, wherein in each of the row n-2 to n crowns all the channels are identical.
30. The filtration element as claimed in any one of the preceding claims, wherein all the ratios between the transverse cross-sectional surface areas of any channels belonging to the filtration crowns are all within the interval 0.75-1.25. (8880359_1):SPM
31. The filtration element as claimed in claim 30, in which the ratios between the transverse cross-sectional surface areas of the channels belonging to the filtration crowns are all within the interval 0.95-1.05.
32. The filtration element as claimed in any one of the preceding claims, wherein the widths of the flow dividers are equal within one and the same crown and are equal from one crown to the next.
33. The filtration element as claimed in any one of the preceding claims, wherein the width of each flow divider is constant over its entire length.
34. The filtration element as claimed in any one of the preceding claims, wherein all the channels of the filtration crowns are delimited by an outer wall, two side walls and fillets and an inner wall, said fillets each having an arc-shaped profile, the radius of which is greater than or equal to 0.3 mm.
35. The filtration element as claimed in claim 34, in which the radius of the arc-shaped profile is in the range extending from 0.3 to 1.5 mm.
36. The filtration element as claimed in any one of the preceding claims, wherein the row n, n-1 and n-2 crowns each have a number of channels that is a multiple of an integer m and in that the number of axes of a flow and connection path of the row n crown, which are substantially aligned with the axis of an adjacent channel of the crown of lower row n-1, with said axis of the channel itself substantially aligned with the axis of an adjacent flow and connection path of the crown of lower row n-2, corresponds to this integer m.
37. The filtration element as claimed in any one of the preceding claims, wherein the channels of one and the same filtration crown are all identical and are spaced an equal distance apart from one another.
38. The filtration element as claimed in any one of the preceding claims, comprising a central channel and in that the filtration crowns are distributed concentrically with respect to the central channel.
39. The filtration element of claim 38, in which the central channel is of a circular shape. (8880359_1):SPM
40. The filtration element as claimed in any one of the preceding claims, wherein the filtration crowns are distributed over concentric circles.
41. The filtration element as claimed in any one of the preceding claims, wherein all the channels of the filtration crowns have a trapezoidal or triangular cross section.
42. The filtration element as claimed in any one of the preceding claims, wherein the support has a circular or polygonal cross section.
43. The filtration element as claimed in any one of the preceding claims, wherein the surface of all the channels is covered with at least one inorganic filtration layer.
44. The filtration element as claimed in any one of the preceding claims, wherein the mean thickness of the porous zone closest to the central axis is less than the mean thickness of the porous zone closest to the periphery of the support and on moving from the central axis of the support toward its periphery, the mean thickness of a porous zone is either identical to the next zone, or smaller.
45. A filtration installation or module comprising a filtration element, as claimed in any one of the preceding claims, in a housing.
46. A filtration element, substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1150277A FR2970422B1 (en) | 2011-01-13 | 2011-01-13 | NEW GEOMETRY OF FILTRATION ELEMENTS |
FR1150277 | 2011-01-13 | ||
PCT/FR2012/050078 WO2012095611A1 (en) | 2011-01-13 | 2012-01-12 | Novel shape of filtering elements |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ613190A NZ613190A (en) | 2014-09-26 |
NZ613190B2 true NZ613190B2 (en) | 2015-01-06 |
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