Draw plate for the production of membranes of an organic material

The invention relates to an extrusion plate for the production of membranes of an organic material including at least one longitudinal passageway. This extrusion plate includes an annular body (1) provided with a cylindrical cavity into which opens at least one radial fluid conduit (5), an upper ferule (3) adapted to be inserted into the cavity of the body and comprising at least one hollow needle (8) extending in the extension of said insert and a longitudinal centering fluid feed conduit (9), and a lower insert (4) adapted to be inserted into the cavity of the body and having a bore (6) defining an extrusion chamber around the needles (8). The upper (3) and lower (4) inserts are in abutment at assembly faces at the level of which open the fluid conduits (5), and a fluid passage (7) is provided on these opposing faces in continuity with the passages (5), for communicating with the extrusion chamber.

This invention relates to a drawplate or extrusion plate for the production 
of membranes of an organic material, comprising at least one longitudinal 
passageway. It also applies in particular to extrusion plates for the 
production of membranes comprising a plurality of separate longitudinal 
passageways. 
BACKGROUND AND OBJECTS OF THE INVENTION 
Numerous extrusion plates are currently known for the production either of 
hollow fibers or membranes comprising a plurality of separate longitudinal 
passages. Such extrusion plates are especially described in the U.S. Pat. 
No(s). A-3,081,490 and A-3,075,242 (hollow fibers), German patent 
A-3,022,313; Swiss patent A-516,985 and U.S. Pat. No. A-2,965,925 
(membranes provided with a plurality of passageways) and comprising at 
least one needle on the interior of which is introduced a centering fluid, 
and an interstitial volume around that (or those) needles in which a 
polymeric solution flows. While these extrusion plates present their own 
particular qualities, they all have some common disadvantages. They are 
all of a rather high cost either by reason of the complexity of their 
constituent elements, or by reason of a high number of such constituent 
elements needed for their production. Further, the time of duration of the 
fluids on the interior of these extrusion plates is generally long and 
produces heat exchange between the fluids which leads to the formation of 
a particular, predefined structure of the polymeric material. Finally, 
these extrusion plates have dead zones which makes their cleaning 
difficult and generally requires dismantling them for cleaning. These dead 
zones constitute further spaces in which air pockets may form during 
extrusion of the membrane. 
The present invention seeks to overcome these disadvantages of known 
extrusion plates and has as the primary objective to provide an extrusion 
plate produced from a reduced number of pieces each having a simple 
structure. 
Another object of the invention is to provide an extrusion plate able to be 
cleaned without disassembly. 
Another object is to provide an extrusion plate in which the time of 
duration of fluids therein is as short as possible. 
Another object is to provide an extrusion plate having no dead zones in the 
direction of fluid flow. 
DESCRIPTION OF THE INVENTION 
To this effect, the invention relates to an extrusion plate for the 
production of membranes of an organic material comprising at least one 
longitudinal passageway, characterized in that it comprises: 
an annular body having a cavity of a generally cylindrical shape and 
provided with at least one fluid passageway opening radially into said 
cavity, 
an upper insert body comprising: 
at least one upper portion of a section conjugate with that of the cavity 
of the body for insertion into said cavity, 
at least one hollow needle extending in the extension of said insert, 
a longitudinal centering fluid feeding passageway passing through said 
insert and communicating with each needle, 
a lower insert of a shape conjugate with that of the cavity of the body for 
insertion into said cavity, said lower insert having a bore adapted to 
define around the needles an extrusion chamber of a cross-section 
conjugate with that of the membrane to be produced, 
the lower and upper insert bodies being in face to face abutting 
relationship one against the other, 
each fluid passageway being arranged in the annular body in such a manner 
as to empty at the level of the opposing faces of the upper and lower 
inserts, 
a fluid passage being arranged on said opposing faces in continuity with 
each of the fluid passageways for communicating with the extrusion 
chamber. 
The time of duration of the polymeric solution on the interior of this 
extrusion plate is thus extremely short because it is introduced 
practically directly into the extrusion chamber around the needles through 
the intermediary the fluid passages. The heat exchange between polymeric 
solution and centering fluid being thereby reduced to a minimum, this 
extrusion plate permits fabricating membranes of which the structure of 
the polymeric material is well defined. 
Further, this extrusion plate is composed of three primary pieces, to a 
maximum of four as will be seen below, of a simple structure, from 
identical raw starting blanks, permitting notably the production of 
membranes having different arrangements and numbers of passageways. 
According to a preferred embodiment, the fluid passageways of the annular 
body and the fluid passageway provided on the opposing faces of the lower 
and upper inserts are adapted to define a section of fluid passageway 
decreasing in the direction of flow of said fluid. 
The cross-section of the polymeric material passageway is therefor 
constantly decreasing in the direction of flow of this material, which 
goes in the direction of an increasing loss of load. For this reason, this 
extrusion plate has no dead space susceptible of causing the creation of 
air pockets. Further, it has no inaccessible zone preventing proper 
cleaning without disassembly. 
For these reasons, the lower portion of the upper insert may advantageously 
have an external cross-section adapted to be for fitted into the cavity of 
the annular body. Thus, this upper insert is not removable, which avoids 
any risk of bending or breaking of the needles during any eventual 
disassembly operation. 
Further, the lower insert itself advantageously has an external 
cross-section adapted to be forcefully inserted into the cavity of the 
annular body. The two inserts are thus precisely centered one with respect 
to the other and this mounting requires neither sealing gaskets nor 
supplementary securing elements. 
According to another characteristic of the invention, each fluid passage 
arranged on the opposing faces of the lower and upper inserts is comprised 
of a groove provided in the face of one of said inserts in continuity with 
a fluid passage of the annular body. 
Two preferred embodiments are provided for the production of the needles. 
Thus, these needles may, in the first case, be formed out of the mass of 
the upper insert. The extrusion plate may also comprise: 
an upper insert comprising at least one longitudinal bore traversing and 
opening into the longitudinal passageway for feeding the centering fluid, 
a needle lodged in each bore in such a manner as to form a lower portion 
extending partially into the extension of the upper insert and an opposite 
upper extremity, opening into the centering fluid feed passage, said upper 
extremity being secured by brazing or bonding in said feed passage. 
Finally, this extrusion plate may be utilized for the production of a 
hollow fiber and comprise a single needle. It may also permit the 
production of membranes provided with several separate longitudinal 
passageways and comprise: 
either several needles aligned in the prolongation of the upper insert and 
a lower insert provided with a bore having a rectangular cross-section 
defining around said needles an extrusion chamber of a rectangular 
cross-section of lesser width with respect to its length, 
or several needles arranged concentrically with respect to the longitudinal 
axis of said extrusion plate, and a lower insert provided with a bore of a 
circular cross-section defining around said needles an extrusion chamber 
with a cylindrical cross-section.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The extrusion plates shown in the drawings are intended for the production 
of membranes provided with a plurality of separate longitudinal 
passageways. They comprise principally three elements: an annular body 1 
having a cavity 2 of a generally cylindrical shape and upper and lower 
inserts 3, 4 inserted into the cavity 2 of the annular body 1 and being in 
face to face abutment against each other at the opposing faces 3a, 4a. 
In the description which follows, the same reference characters are used to 
designate the equivalent elements of the three types of extrusion plates 
described. 
In the first place, the extrusion plate shown in FIGS. 1 to 7 is intended 
for the production of cylindrical membranes provided with seven separate 
longitudinal passageways. 
The annular body 1 of this extrusion plate has a generally cylindrical 
external shape and comprises a longitudinal central cavity 2, itself of a 
cylindrical shape. 
Further, two diametrically opposed fluid conduits are 5 are arranged 
radially in the wall of this annular body 1, in such a manner as to open 
into the cavity 2. These conduits 5 comprise a first, threaded portion 5a 
opening out of the peripheral wall of the body 1 and adapted to permit the 
attachment of fluid inlet conduits having a conjugate threaded 
connections, and a second portion 5b of lesser cross-section opening into 
the cavity 2. 
The lower insert 4 also has a cylindrical external shape conjugate with 
that of the cavity 2 of the annular body 1 to be able to be inserted 
therein by force fit. 
This lower insert 4 comprises a longitudinal bore 6 provided with a 
chamfered shoulder 6c dividing it into two bores of different diameters: 
an upper bore 6a of a greater diameter emptying at the level of the 
assembly face 4a of the insert 4, and a lower bore 5b of a diameter 
conjugate with that of the membrane to be produced, emptying at the level 
of the lower face of this insert 4. 
Finally, the assembly face 4a of the insert 4 comprises two radial aligned 
grooves 7 emptying respectively into the upper portion 6a of the bore 6 
and at the level of the peripheral wall of this insert. These grooves 7 
are arranged to come into alignment with the portions 5b of the fluid 
conduits 5 of the annular body 1 when the lower insert 4 is inserted into 
the cavity 2 of this body 1. 
The upper insert 3 comprises itself an upper portion 3b of a cylindrical 
external shape adapted to be force fit into the cavity 2 of the annular 
body 1. This upper portion 3b has a lower assembly face 3a which comes 
into abutment on the assembly face 4a of the lower insert 4. 
In the extension of this upper portion 3b extends a lower portion 3c of a 
shape conjugate with that of the bore 6 of the lower insert 4, adapted to 
define with the internal wall of this bore 6 an annular fluid passage 
communicating with the annular fluid passage. 
finally, the upper insert comprises a longitudinal passageway 9 for feeding 
the needles 8 with a centering fluid. This passageway 9 comprises two 
portions of different diameters separated by a shoulder: an upper threaded 
portion 9a emptying at the level of the upper face of the upper insert 3 
and adapted to permit the connection of a centering fluid inlet passageway 
provided with a conjugate threaded ferrule, and a lower portion 9b of a 
lesser diameter communicating with the needles 8. 
The extrusion plate shown in FIGS. 8 to 18 is intended for the production 
of planar membranes provided with seven separate and aligned longitudinal 
passageways. 
The body 1 of this extrusion plate is also of a generally cylindrical shape 
and comprises two radial fluid conduits 5 emptying into a cavity 2. This 
cylindrical cavity 2 has a lower, chamfered extremity portion. 
The wall of this body 1 is provided with four threaded longitudinal blind 
openings 10 and a through opening 11. 
The lower insert 4 comprises also a generally cylindrical external shape 
conjugate with that of the cavity 2 of the body 1 for being inserted by 
force into the latter. This lower insert comprises also a frontal wall 12 
presented in the form of a plate adapted to come into placement against 
the lower face of the body 1. 
This frontal wall 12 is provided with four openings 13 conjugate with the 
threaded openings 10 of the body 1 to permit assembly of these two pieces 
by means of securing screws, and one opening 14 opposite the transverse 
opening 11 of this body. Also, it comprises two threaded openings 15 
intended to permit withdrawal by means of a tool provided having a 
conjugate thread. 
As is shown in FIGS. 8 and 9, an annular seal 16 housed in the chamfered 
extremity of the bore 2 of the body 1 assures the seal between this body 1 
and the lower insert 4. 
In the extension of this upper portion 3b extends a lower portion 3c of a 
shape conjugate with that of the bore 6 of the lower insert 4, adapted to 
define with the internal wall of this bore 6 an annular fluid passage 
communicating with the grooves 7. 
The lower extremity of this portion 3c is also pierced with longitudinal 
bores 17, seven in number, each of which houses a needle 8 arranged to 
extend partially into the extension of the upper insert 3 in such a manner 
as to define an interstitial volume communicating with the annular fluid 
passage, at the level of the rectangular cross-section bore 6b of the 
lower insert 4. Each of these needles 8 is secured by brazing or 
soldering. 
The upper insert 3 comprises a longitudinal passageway 9 for feeding the 
needles 8 with a centering fluid. This passageway 9 comprises two portions 
of different diameters separated by a shoulder: an upper threaded portion 
9a opening at the level of the upper face of the upper insert 3 and 
adapted to permit the connection of an inlet passageway for the centering 
fluid provided with a conjugate threaded connection, and a lower portion 
9b of a rectangular cross-section communicating with the needles 8. 
Finally, this upper insert 3 comprises a frontal face 18 adapted to come 
into contact on the upper face of the body 1. This front face 18 has an 
opening 19 adapted to position it with respect to the respective openings 
11 and 14 of the annular body 1 and of the lower insert 4 in such a manner 
as to permit indexing the position of these three pieces by means of a 
centering pin 20. 
The extrusion plate shown in FIGS. 19 to 29 is intended for the production 
of cylindrical membranes provided with nineteen separate longitudinal 
passageways. 
The body 1 of this extrusion plate is of a cylindrical external shape and 
comprises four radial fluid conduits 5 opening into a cavity 2. This 
cylindrical cavity 2 has a chamfered lower extremity portion. 
The wall of this body is provided with four longitudinal threaded openings 
10. 
The lower insert 4 has the shape of a sleeve comprising a peripheral 
cylindrical wall 21 conjugate with the cavity 2 of the body 1 to be 
inserted by force into this latter. This lower insert comprises a front 
wall 12 having the shape of a plate adapted to be placed against the lower 
face of the body 1. 
This front wall 12 is provided with four openings 13 conjugate with the 
threaded openings 10 of the body for the assembly of these tow pieces by 
means of securing screws 22, and an opening 14. 
As is shown in FIGS. 20 and 21, an O-ring seal 16 housed in the chamfered 
extremity of the bore 2 of the body 1 assures the seal between this body 1 
and the lower insert 4. 
This lower insert 4 comprises a longitudinal bore 6 defined by the annular 
peripheral wall 21 and opening at the level of the front face 12 of the 
insert through a cylindrical bore 6b of a diameter corresponding with that 
of the membrane to be produced. 
The upper edge of the peripheral wall 21 serves as the assembly face 4a and 
comprises four notches 23 determining fluid passages communicating with 
the fluid conduits 5 of the annular body 1. 
On the interior of the bore 6 is provided an intermediate plate 24 of a 
diameter conjugate with this bore and comprising opposite lower bore 6b a 
plurality of fluid passages 25 arranged concentrically and having an 
elongated, rounded shape. Each of these fluid passages 25 is intended to 
house two needles 8 and to determine therearound an interstitial volume. 
The upper insert 3 comprises an upper portion 3b of a cylindrical shape 
adapted to be inserted forcibly into the cavity 2 of the annular body 1. 
This upper portion 3 comprises an assembly face 3a in abutment with the 
upper ends of the peripheral wall 21 of the lower insert. 
This upper insert 3 comprises four plugs 26 having the shape of sectors of 
a circle and are arranged in such a manner as to define between them fluid 
passages 26a in communication with the notches 23 of the peripheral wall 
21 in such a manner as to lead this fluid toward a central zone of the 
conjugate circular section of this bore 6b of the lower insert 4. 
The upper insert 3 is pierced with longitudinal bores 17, nineteen in 
number, arranged in such a manner as to open at the level of the assembly 
face 3a, in the aforementioned central zone. Each of these bores 17 is 
adapted to house a needle 8 arranged to be partially extended in the 
extension of the upper insert 3, in such a manner as to traverse a fluid 
passage 25 of the intermediate plate 24 and be extended into the bore 6b 
of the lower insert 4. The securing of these needles 8 is obtained by 
brazing or soldering. 
The assembly of needles 8 thus determines in this bore 6b an interstitial 
volume communicating with the fluid conduits 5 of the annular body 1 
through the intermediary of the fluid passages 25 of the intermediate 
plate 24. 
The upper insert 3 comprises a longitudinal passageway 9 for feeding a 
centering fluid. This passageway 9 is threaded for connection of the inlet 
conduits for the centering fluid and communicates with the needles 8. 
Finally, this upper insert 3 comprises a blind opening 19 arranged to be 
positioned opposite the opening 14 of the lower insert 4 in such a manner 
as to permit indexing the position of these pieces by means of an indexing 
pin 20 housed in said openings 14, 19 and traversing a third opening 27 
provided in the intermediate plate 24. 
The operation of these three extrusion plates is identical. The centering 
fluid is fed into the feed conduit 9 of the upper insert 3 by means of a 
conduit connected to this insert, and then flows to the interior of the 
needles. 
The polymeric solution is introduced into the fluid conduits 5 by means of 
conduits connected to the annular body 1 and flows in the fluid passages 
arranged between the assembly faces 3a, 4a of the lower insert 4 and the 
upper insert 3 until in the bore 6b where is it distributed among the 
needles 8. 
It should be noted, however, that the extrusion plate for the production of 
membranes comprising nineteen passageways comprises an intermediate plate 
24 dividing the bore 6 of the lower insert into two compartments: an 
upstream compartment into which open the fluid passages, and a downstream 
compartment corresponding to the bore 6b and constituting the outlet 
chamber of the extrudate. 
The role of this plate 24, used for extrusion plates comprising a sizeable 
number of needles 8, is to create an adjustable loss of load according the 
thickness of the plate, permitting assuring a homogeneous distribution of 
the polymeric solution among the needles 8.