Patent Application
20080128348
The invention relates to a membrane module for the separation of substances, especially by crosscurrent filtration, comprising a housing and at least one self-supporting, replaceable filter cartridge mounted in it and with semipermeable filter tubes extending longitudinally that are embedded at their ends in a cast body (potting).
Such a membrane module is known from WO 2000/040325 A1 (Blum, Heggemann GmbH). This publication is expressly referenced in order to supplement the disclosure.
Furthermore, a filter cartridge consisting of a filter-tube bundle but not provided for crosscurrent filtration is known from German patent DE 35 13 789 C2 (Kronsbein).
If the pottings in accordance with the above-cited international patent application are sealed with their outer ends directly on the inside of the housing, e.g. with O-rings, it is possible when certain fluids and certain solvents contained in them are used for the seals to adhere on the outside of the pottings and on the inside of the housing. The filter cartridge can then be removed from the housing only by damaging these seals and the filter cartridge since it is very difficult to loosen this adhesion on site without damaging the O-rings and the filter cartridge.
Furthermore, it is not possible in the case of the filter cartridges in accordance with the cited international patent application that the filter-tube bundles are prefabricated with pottings on their ends, stored and replaced only later as required, which replacement should take place as simply and rapidly as possible.
The invention therefore has the basic task of solving these problems in a membrane module of the initially cited type. At the same time, the other requirements cited in the international patent application should also be met. In particular, a mounting and unmounting of the cartridge including all sealing elements into and out of the housing should be possible from only one end with only the one end of the housing having to be opened. Furthermore, the membranes should be able to be used at low temperatures, e.g.—40° C. as well as at high temperatures, e.g. approximately 400° C.
Furthermore, the membrane module and the filter cartridge should protect the membranes against sudden pressure changes.
The invention solves this task with the features of claim 1.
The holder preferably fixes the end rings positively to the pottings by means of projections and recesses.
It is furthermore suggested that the holder be designed as an intermediate tube forming the outer jacket of the cartridge and formed in turn of several shells that are longitudinally divided and connected to each other, in particular of two semicylindrical half shells that in particular have openings for letting out the permeate.
The longitudinally divided shells are preferably fastened together in a detachable manner, especially with tension bands, to the end rings and the pottings.
The advantage of the longitudinally divided intermediate tube that is detachably connected to the end rings and pottings is the possibility of being able to unmount a defective filter cartridge in a simple and rapid manner in order to replace the defective filter-tube bundle and its pottings with a new filter-tube bundle.
The pottings are preferably sealed against the end rings. In particular, the holder also fixes the end rings relative to each other.
This way, the pottings are no longer sealed directly against the housing but rather only against the ring-shaped end caps. The end caps themselves are sealed against the inside of the housing.
The end rings and the holder preferably are made of metal. If the filter cartridge must be replaced, it can be readily withdrawn along with the end rings and the holder from the housing. If the seals have adhered between the end caps and the housing, it is not a problem if the seals are damaged during replacement. The metallic sealing surfaces can be readily cleaned on site and a new seal attached. However it is important that the pottings mounted inside the end caps can be removed undamaged from the housing. Seals that may be adhered between the pottings and the end caps can be loosened later in a workshop with the suitable tools present there and without time constraint without any damage occurring to the pottings and to the filter tubes. Also, a more rapid mounting of the filter cartridge is possible due to the compact design with the front-end metallic end caps.
As has already been explained, the end rings are preferably sealed against the housing.
In a further advantageous embodiment an inlet tube and/or outlet tube is provided inside the cartridge, the length of which tube(s) can be automatically changed like a compensator and whose ends are connected to the pottings in an axially non-shiftable manner. The inlet and outlet tube preferably each comprise at least two tube sections that can slide partially into one another in a telescoping manner and/or comprise at least one longitudinally extensible and shortenable compensating coupling.
In order to achieve large production throughputs that are typical for industrial applications, instead of the individual modules it is advantageous to use a system with very many, e.g. up to approximately 20 filter cartridges, each one with individual filter-tube bundles. It is therefore suggested that the housing have several seats, one for each filter cartridge.
The filter cartridges can have a common permeate chamber located outside of the filter tubes. However, in this instance the filter-tube bundles cannot be individually turned off or turned on. Turning off would be advantageous if individual filter-tube bundles are no longer fully effective during operation or if they are damaged. A common inlet tube connected to the interiors of the filter tubes is preferably provided. Seats that are not being used can be detachably closed, that is, “set blind.” In order that the inner chamber, that is, the permeate chamber, can be heated, e.g. by product vapor, it is furthermore advantageous if the inner chamber of the housing comprises a heat exchanger, that is, internal tubing that is possibly provided with ribs.
In order to also be able to turn the filter-tube bundles off individually it is advantageous in certain instances if each seat for the filter cartridges comprises its own inlet tube provided with appropriate turn-off valves.
The essential elements of the invention are the following:
The following are also important:
Three illustrated embodiments of the invention are discussed in detail in the following with reference made to the drawings.
In all figures the same reference numerals have the same meaning and are therefore discussed only once, if necessary.
The filter cartridge is mounted in a cylindrical housing 1 whose diameter is shown oversize in
Both pottings 3, 4 and 5, 6 are furthermore connected to an inlet/outlet tube 11 that is also embedded in the cast body and is made of two tube sections that can be partially pushed into one another in a telescopic manner as is indicated in
The pottings are fixed to each other with the end rings by two semicylindrical half shells 12 and 13 made by longitudinally cutting a tube. Radially inwardly extending projections 14, 15, 16, and 17 serve for this purpose, with the projections 16 and 17 engaged in respective circumferential grooves 18 and 19 of the end rings 7 and 8. When the half shells 12 and 13 are fitted together, two tension bands 20 and 21 engaged in respective circumferential grooves 27 and 28 and hold them firmly but detachably in position.
During assembly the filter cartridge is pushed from the left into the housing. The filter cartridge is then sealed against the outside by seals 22 and 23 fitted between the end rings 7 and 8 and the housing 1. A circumferential shoulder 24 on the outside end of front-end ring 7 serves as a stop that established the desired insertion depth of the filter cartridge into the housing 1.
During operation the feed flows from the left into the front-end ring 7, thence through the passages of the filter tubes 2 to the right end in
The end rings 7 and 8, inlet-and outlet tube 11, half shells 12 and 13 and tension bands 20 and 21 are made of metal. The pottings 3, 4 and 5, 6 are thermoplastic plastic cast bodies. All customary membrane types can be used as the filter tubes 2.
For installation, the two closed metallic end rings 7 and 8 fitted from both ends over the necks 5 and 6 of the pottings. The two semicylindrical half shells 12 and 13 are then fitted from both sides around the filter-tube bundle with the pottings. The half shells are formed with two grooves 16 and 17 that engage in respective grooves 18 and 19 of the end rings 7 and 8. The two tension bands 20 and 21 are then fitted into the grooves 27 and 28 of the half shells 12 and 13 in order to fix the half shells firmly to the filter-tube bundle and the pottings.
The second embodiment according to
The filter tubes as well as the inlet-and outlet tube are not shown in
The pottings are fixed to each other with the end rings by two semicylindrical half shells 12 and 13 produced by longitudinally dividing a short tube. Flanges 38 and 39 of the half shells 12 and 13 are secured by screws to corresponding flanges of end rings 7 and 8, are used for this purpose.
During assembly the filter cartridge is pushed from the left into the housing. The filter cartridge is then sealed outwardly by seals 22 and 23 fitted between the end rings 7 and 8 and the housing 1. A flange 37 of the end ring 7 and front end 40 of the end ring 8 serve with screwed-on stop rings 29 and 30 to fix the filter cartridge in housing 1.
For mounting the two closed metallic end rings 7 and 8 fitted from both ends onto the pottings. The two semicylindrical half shells 12 and 13 are fitted from both ends around the filter-tube bundle with the pottings and screwed onto flanges 38 and 39 with the inner end surfaces of end rings 7 and 8 in order to fix the half shells firmly to the filter-tube bundle and to the pottings.
All seals, which preferably consist of rubber and are designed as O-rings and seal the filter cartridge against the outside, rest between end rings 7 and 8 and housing 1 but do not touch the pottings. No seal that contacts the pottings makes contact with the housing 1, so that adhering of the pottings due to the solvent in the feed used during operation when the filter cartridge is removed does not cause any problems. As has already been explained, the filter cartridge can be mounted from one end, here on the left.
In a corresponding manner a housing can be provided with several seats for filter cartridges, e.g. for 3, 7, 19 or 55 cartridges (
Furthermore, in the individual module according to
In the multi-module according to
A comparison of a cartridge with a single filter-tube bundle (
A: End ring 8 (retentate end) for individual filter-tube bundle and front plate 36 (retentate end) for several filter-tube bundles—the outside diameter of the retentate end ring and/or of the retentate front plate is 229 mm in this example.
B: End ring 7 (feed end) for individual filter-tube bundle and front plate 36 (feed end) for several filter-tube bundles: It should be considered here that the front feed ring has a somewhat smaller diameter (see
C: Spacer casing (half shells 13, 14): It should be considered here that as a supplement to the above comments the spacer casing can also be tubular (
D: Seal 9, 10 between potting and end ring and front plate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 007 705.6 | Feb 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP06/01467 | 2/17/2006 | WO | 00 | 1/4/2008 |
