Liquid purification or separation – With repair or assembling means
Patent
1998-09-10
2000-07-04
Drodge, Joseph W.
Liquid purification or separation
With repair or assembling means
21032179, 21032188, 2103232, 210541, 96 8, B01D 6306, B01D 6904
Patent
active
060833904
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a system for membrane filtration by the cross-flow process, having a number of membrane modules, each including one membrane tube or a bundle of a plurality of membrane tubes, whose walls have the function of separation membranes, and a tubular module housing for receiving the membrane tubes, delivering a medium to be filtered as a retentate and removing the filtrate in the form of permeate, wherein each membrane module has one connecting flange for delivering and removing the retentate and at least one further connecting opening for removing the permeate.
Such membrane modules as known as components of cross- flow filtration systems. Cross-flow filtration is a pressure filtration process. The product to be filtered flows at a predetermined speed crosswise to the straight-through direction and along the surface of the filter or of the filtration membrane. The crosswise flow largely prevents solids from becoming deposited on the surfaces of the filters and thereby makes long-term operation possible without plugging up of the filters.
Such membrane modules are often embodied as so-called tube or capillary modules, in which one or more capillary tubules or tubes are combined into a bundlelike unit. The separating membrane is applied to the inside wall or outside wall of the tubes, depending on the model. In one version, 19 membrane tubules with an inside diameter of one-half inch are combined into a bundle. A retentate flows at a predetermined pressure through these 19tubules simultaneously and in parallel. After passing through the filter membranes, the permeate flows out via two connections to each membrane module.
Since the specific filtration capacity in terms of surface area of known membranes is relatively low, to achieve greater, more practical filtration capacities a number of modules are connected together both in series and parallel in one group. If the number of modules connected in series is low, then the modules are connected directly to one another longitudinally in numbers of up to four. The retentate connections are usually so solid that the group is supported via these lines. In that case, no further support elements are present. The permeate lines then have no load-bearing function.
Such arrangements are commercially practical only if membrane tubes with small diameters up to approximately 4 mm, so-called capillary tubes, are used. The membranes used are usually of ceramic and in terms of separation performance are in the field of microfiltration with separation limits of from 5 nm to 100 nm. The membrane modules then have a high proportion of membrane surface area per unit of volume of the module. However, in comparison with modules of other designs, they have disadvantages in terms of process technology; because of the small membrane tube diameters, the tubes readily become plugged up with solids.
If the number of series-connected modules is high, and up to 16 modules per series are known, then they are joined together via 180.degree. elbows. If the group includes only five series run simultaneously in parallel, then 80 modules have to be disposed as compactly as possible in one unit. To that end, the individual modules are supported on bearing arms, and the numerous connections are made on the retentate and permeate sides. The following problems then arise: needed per membrane module. In a system with approximately 200 modules, these connections and bearing points lead to high system costs and thus reduce the economy of the system. thus parts subject to wear, and they must be replaced at certain time intervals. The expense for assembly and disassembly is enormous, because of the large number of connections. collective line via flexible, transparent hoses. The large number of connecting points, as well as air bubbles, are detrimental to hygienic conditions.
It is therefore the object of the invention largely to eliminate the problems addressed above.
According to the invention, this object is attained in a system of the type defined at the outset in that each membr
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patent: 5470469 (1995-11-01), Eckman
Bucher-Guyer AG
Drodge Joseph W.
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