Title of Invention

"A APPARATUS FOR PREPARATION OF ASYMMETRIC MEMBRANES FOR GAS SEPARATION"

Abstract This invention relates to an apparatus for preparation of asymmetric membrane for gas separation comprising a casting chamber (2) and quenching chamber (3) mounted on a frame (1) said casting chamber (2) has provision for steam exposure of membrane, inspection windows (10,10,10) at the top and steam channels with a number of ports/holes (31) opening to the two sides of quenching chamber (3); a coagulation chamber (28) mounted on frame (26) having inspection windows (4,4) with lid (20) and connected to quenching chamber (3) through safety guard (29); a conveyer belt (24) for the transverse movement of a glass plate (25) from casting chamber (2) to quenching chamber (3) for preparation of the membrane; rollers (23,23), motor (11) and transmission belt (12) for moving the conveyer belt, a control panel (7) to control the motion of the belt housed in safety guard (29); hopper (5) to pour polymer on glass plate (25) and wiper (6) to ensure uniform thickness of the membrane as well as to ensure uniform spreading of the polymer; leveling screws (8,8) for frame (1) and leveling screws (27,27) for frame (26).
Full Text FIELD OF INVENTION
This invention relates to an apparatus for the preparation of asymmetric membranes for gas separation such as separation of oxygen from air.
PRIOR ART
Asymmetric membranes are used for reverse osmosis (RO) and gas separation (GS) applications. An asymmetric membrane has two layers; one- dense top layer which functions as a selective mass transfer matrix supported on a second porous sublayer structure. Fabrication of these membranes requires controlled fabrication parameters for the incorporation of typical structural features necessary for gas separation membranes. Normally three operations are needed to prepare the membrane, first, pouring of polymer solution and spreading it to a uniform thickness, second exposure of the same solution to a controlled atmosphere of steam and third to stabilize the structure.
One of the apparatus known in the art as per US Patent - 6,390,468 comprises of a table with marked area having raised boundary where-in the polymer is spread manually with a glass rod.
A disadvantage of the above apparatus is that it does not incorporate pouring hopper to pour polymer in uniform manner.
Another disadvantage of the above apparatus is that the thickness of the casting solution cannot be adjusted.
Yet another disadvantage of the above apparatus is that the spreading of polymer solution is done manually.
Further disadvantage of the above apparatus is that the apparatus cannot incorporate asymmetric structure in the membranes.
Another apparatus known in the art as per US Patent- 04902422 comprises of a Teflon coated glass plate where-in the polymer is spread manually using a Gardner knife with a gap of 250 micron on to the coated glass plate.
A disadvantage of the above apparatus is that the gap between Gardner knife and coated glass plate is fixed.
Another disadvantage of the above apparatus is that the spreading of polymer solution is done manually.
Further disadvantage of the above apparatus is that the apparatus cannot be used to make long membranes.
OBJECTS OF PRESENT INVENTION
The primary object of the present invention is to provide an apparatus for making asymmetric membrane for gas separation, in a reproducible manner.
Another object of the present invention is to provide an apparatus for making asymmetric membrances from polymer solution either under ambient conditions or under controlled environment.
Still another object of the present invention is to provide an apparatus for making asymmetric membrane having arrangement for pouring and spreading of the polymer solution.
Yet another object of the present invention is to provide an apparatus, which enables control over the casting thickness of the membrane.
Further object of the present invention is to provide an apparatus which facilities formation of dense top layer by providing controllable input of steam.
Yet further object of the present invention is to provide an apparatus, which facilities stabilization of porous sub-structure beneath the top dense layer.
Still further object of the present invention is to provide an apparatus for casting membrane of mixed matrix having inorganic and organic constituents.
Even further object of the present invention is to provide an apparatus for casting dense membranes of various dimensions.
DESCRIPTION OF INVENTION
According to this invention, there is provided an apparatus for preparation of asymmetric membrane for gas separation comprising:
- a casting chamber (2) and quenching chamber (3) mounted on a frame (1) said casting chamber (2) has provision for steam exposure of membrane, inspection windows (10,10,10) at the top and steam channels with a number of ports/holes (31) opening to the two sides of quenching chamber (3);

- a coagulation chamber (28) mounted on frame (26) having inspection windows (4,4) with lid (20) and connected to quenching chamber (3) through safety guard (29);
- a conveyer belt (24) for the transverse movement of a glass plate (25) from casting chamber (2) to quenching chamber (3) for preparation of the membrane;
- rollers (23,23), motor (11) and transmission belt (12) for moving the conveyer belt, a control panel (7) to control the motion of the belt housed in safety guard (29);
- hopper (5) to pour polymer on glass plate (25) and wiper (6) to ensure uniform thickness of the membrane as well as to ensure uniform spreading of the polymer;
- leveling screws (8,8) for frame (1) and leveling screws (27,27) for frame (26).
In the apparatus of the present invention, the polymer solution is spread on a glass plate with the help of a hopper and a wiper. The glass plate resting on an endless circulating conveyer belt is made to move from casting chamber with the help of rollers.

motor and transmission belt controlled by an electrical panel to enter quenching chamber where the steam environment is provided. In the quenching chamber, formation of dense top layer is facilitated due to the convective evaporation of solvents. The quenched membrane is then allowed to enter the coagulation chamber. The dipping of the nascent membrane supported on the glass plate into the non-solvent liquid, is facilitated by the upward movement of the tray. The movement of the tray is facilitated by a synchronous motor controlled by an electric control panel. In the coagulation chamber the structure of the membrane is stabilized.
The formed membrane using the above apparatus has an asymmetric structure, which consists of a top dense layer supported by a porous sublayer. The formed membranes have capacity to enrich atmospheric oxygen to various levels. For example, polysulfone asymmetric membrane prepared by this apparatus, could enrich oxygen upto 40%. This apparatus can also be utilized for preparation of dense and porous asymmetric membranes for various separation applications like micro-filtration, ultra-filtration and reverse osmosis.
DESCRIPTION OF FIGURES
The present invention will now be illustrated with the help of accompanying drawings, which illustrate an embodiment of the present invention. It is to be noted that the principles and features of the invention may be incorporated in different embodiments without departing from the scope of present invention.
In the accompanying drawings:-
Fig 1 - shows the isometric view of the overall setup of the apparatus
Fig 2 - shows the front view of casting and quenching chambers
Fig 2 A - shows the top view of casting and quenching chambers
Fig 3 . - shows the front view of coagulation chamber
Fig 3 A - shows the top view of coagulation chamber

DESCRIPTION OF INVENTION WITH REFERENCE TO;
Referring to Fig 1, the apparatus comprises of two rectangular parallelepiped shaped sturdy cast iron frames (1 & 26). Frame (1) supports casting chamber (2) and quenching chamber (3) and frame (26) supports coagulation chamber (28). Quenching chamber (3) has a safety guard (29), which butts into the coagulation chamber (28). The cast iron frame (1) has four leveling screws like (8,8). The polymer solution is spread on glass plate (25) to cast the membrane. The control panels (7, 19) help in controlling the casting, quenching and coagulation processes during the membrane casting. The top of the quenching chamber (3) has three inspection windows (10, 10, 10) fitted with lids to observe formation of dense top layer during quenching of spread polymer solution. Windows (4,4) facilitate observation of coagulation process. Leveling screws like (8,8 and 27,27) are used to level the apparatus.
Referring to figures 2 and 2A, the polymer solution is poured on glass plate (25) with the help of stainless steel hopper (5). The glass plate (25) resting on conveyer belt (24) moves with the help of motor (1 1), rollers (23,23) and transmission belt (12). The movement, speed and direction of the conveyer belt (24) are facilitated by an electric motor (1 1) and set of rollers (23,23). The safety guard (29) covers the motor (1 1) and transmission belt (12). The conveyer belt (24) is made of synthetic fibre and rubber composite. The rollers (23,23) are made of compressed aluminium. The wiper (6) made of stainless steel spreads the polymer solution when the glass plate kept underneath the wiper (6), moves with a predetermined speed controlled by the electric control panel (7). The wiper (6) has a special design so that the polymer solution does not stick to its surface. The thickness of the cast solution is adjusted with the help of wiper (6) by moving it up and down. As soon as the polymer spread is complete the glass plate (25) is made to enter the quenching chamber (3). The quenching chamber has laterally mounted steam compartments (9,9) running parallel to the glass plate (25), with number of ports/holes (31) opening in to the quenching chamber (3). These ports provide inlet to the steam drawn from an external source. In the quenching chamber the spread
polymer solution is exposed to water vapour (non-solvent/precipitant) in the form of steam until a dense and thin top layer of polymer is precipitated. The glass plate (25) with spread polymer solution is kept in quenching chamber (3) by stopping the forward movement of the conveyer belt (24) with the help of control panel (7). The formation of dense layer is monitored with the help of inspection windows (10,10,10). The movement and speed of glass plate through the casting chamber (2) to the quenching chamber (3) and then to the coagulation chamber (28) is controlled by panel (7).
Referring to figure 2, 3 and 3A the glass plate (25) carrying the spread polymer solution in the form of a nascent membrane enters the coagulation chamber (28) with the help of the conveyer belt (24) which pushes the glass plate (25) into the coagulation chamber (28) and makes it to rest on stainless steel support (22) with the help of a guide (21), The glass plate along with the nascent polymer film is then dipped in to a nonsolvent liquid contained in tray (18) with the help of traversing system (14). Here the membrane structure is stabilized. The traversing system (14) facilitates movement of steel tray (18) up and down with the help of a synchronous motor (13), an electrical control panel (19), driving belt (15), pulley (16) and bearing (17). The coagulation chamber can be closed with the help of a top lid (20). The traversing system (14) is supported by a metallic frame (30).
It is to be understood that the present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such modifications, changes, adaptations are intended to be within the scope of the present invention which is further set forth under the following claims:-




WE CLAIM;
1. An apparatus for preparation of asymmetric membrane for gas separation comprising:
- a casting chamber (2) and quenching chamber (3) mounted on a frame (1) said casting chamber (2) has provision for steam exposure of membrane, inspection windows (10,10,10) at the top and steam channels with a number of ports/holes (31) opening to the two sides of quenching chamber (3);
- a coagulation chamber (28) mounted on frame (26) having inspection windows (4,4) with lid (20) and connected to quenching chamber (3) through safety guard (29);
- a conveyer belt (24) for the transverse movement of a glass plate (25) from casting chamber (2) to quenching chamber (3) for preparation of the membrane;
- rollers (23,23), motor (1.1) and transmission belt (12) for moving the conveyer belt, a control panel (7) to control the motion of the belt housed in safety guard (29);
- hopper (5) to pour polymer on glass plate (25) and wiper (6) to ensure uniform thickness of the membrane as well as to ensure uniform spreading of the polymer;
- leveling screws (8,8) for frame (1) and leveling screws (27,27) for frame (26).

2. An apparatus as claimed in claim 1, where said coagulation chamber (28) has stainless steel tray (18) for containing non-solvent.
3. An apparatus as claimed in claim 1, wherein said coagulation chamber (28) has a reciprocating traversing system (14) along the vertical axis which facilities up and down movement for steel tray (18) and comprises a stepper motor (13), driving belt (15), pulley (16) and bearing (17).
4. An apparatus as claimed in claim 1, wherein support (22) supports the glass plate and guide (21) guides the sliding motion of glass plate (25).
5. An apparatus as claimed in claim 1, wherein metallic frame (30) provides vertical support to the traversing system in the coagulation chamber (28).
6. An apparatus for preparation of asymmetric membrane for gas separation substantially as herein described and illustrated.

Documents:

1115-DEL-2002-Abstract-(22-07-2008).pdf

1115-del-2002-abstract.pdf

1115-DEL-2002-Claims-(22-07-2008).pdf

1115-del-2002-claims.pdf

1115-DEL-2002-Correspondence-Others-(09-07-2009).pdf

1115-DEL-2002-Correspondence-Others-(22-07-2008).pdf

1115-del-2002-correspondence-others.pdf

1115-del-2002-correspondence-po.pdf

1115-del-2002-description (complete)-22-07-2008.pdf

1115-del-2002-description (complete).pdf

1115-del-2002-drawings.pdf

1115-DEL-2002-Form-1-(10-07-2009).pdf

1115-del-2002-form-1.pdf

1115-del-2002-form-18.pdf

1115-DEL-2002-Form-2-(22-07-2008).pdf

1115-del-2002-form-2.pdf

1115-DEL-2002-Form-3-(22-07-2008).pdf

1115-del-2002-form-3.pdf

1115-DEL-2002-GPA-(09-07-2009).pdf


Patent Number 248677
Indian Patent Application Number 1115/DEL/2002
PG Journal Number 31/2011
Publication Date 05-Aug-2011
Grant Date 03-Aug-2011
Date of Filing 06-Nov-2002
Name of Patentee THE DIRECTOR GENERAL , DEFENCE RESEARCH & DEVELOPMENT ORGANISATION
Applicant Address DEFENCE RESEARCH & DEVELOPMENT ORGANISATION MINISTRY OF DEFENCE, GOVT.OF INDIA B-341, SENA BHAWAN DHQ P.O. NEW DELHI-110011
Inventors:
# Inventor's Name Inventor's Address
1 PRATIBHA PANDEY DEFENCE RESEARCH & DEVELOPMENT ESTABLISHMENT, JHANSI ROAD, GWALIOR-474002
2 RAM SINGH CHAUHAN DEFENCE RESEARCH & DEVELOPMENT ESTABLISHMENT, JHANSI ROAD, GWALIOR-474002
PCT International Classification Number B01D 53/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA