Liquid purification or separation – With repair or assembling means
Reexamination Certificate
1998-09-25
2001-03-06
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
With repair or assembling means
C055S521000, C096S004000, C210S321840, C210S321860
Reexamination Certificate
active
06197191
ABSTRACT:
The invention concerns an apparatus for filtering and separating flow media, in particular for sea water desalination and water purification by reverse osmosis and ultrafiltration as set forth in the classifying portion of claim
1
.
In practice apparatuses of that kind are referred to as modules. In that respect hollow fiber modules, spiral winding modules and plate modules are known. For example DE 37 15 183 C2 discloses a plate module which corresponds to an apparatus of the kind set forth in the opening part of this specification. The essential difference between the individual modules lies in their structure, in particular in the position and the design of the filter device in the module and the capability of filtering or separating a raw or untreated water with a degree of contamination or fouling (Solid Density Index (SDI)) without the risk of blockage. In that respect the known plate modules involve the lowest level of risk of a blockage. It is therefore possible to forego preliminary purification involving the addition of chemicals. The SDI-value in the plate module can be at a maximum up to 20. The disadvantage of a plate module is inter alia individual production of the membrane plates and a very high proportion of waste in terms of membrane material. Furthermore due to a large number of changes in direction plate modules suffer from higher pressure drops and a lower ratio in respect of filter element surface area to module volume, in comparison with hollow fiber and spiral winding modules. Finally the production processes for same, in particular also because of the above-mentioned high proportion of waste in terms of filter element material, are comparatively expensive so that the production costs for plate modules of that kind are also high.
In comparison therewith the hollow fiber and spiral winding modules have a high ratio of filter element surface area to module volume and can be produced at low cost. However, an SDI-value of only between 1 and 3 is possible for hollow fiber modules and an SDI-value of between 3 and 5 is possible for spiral winding modules. Therefore preliminary cleaning by the addition of chemicals is necessary when using such modules.
SU-A-1 790 985 discloses an apparatus for filtering and separating flow media wherein a flat filter element is provided in a housing. That filter element is arranged in a meander configuration in the housing, forming a plurality of flow channels for the flow medium to be filtered. In that arrangement the flow channels extend in a straight line. In the known apparatus therefore the filter element is not used in the direction-changing regions of its meander configuration so that overall large parts of that filter element cannot be used for the filtration procedure.
The object of the present invention is to provide an apparatus of the kind set forth in the opening part of this specification, which can be inexpensively produced with a high level of efficiency in regard to separation and filter effectiveness.
The foregoing object is attained by the features of claim
1
. The proposed structure permits only one single flat or surface filter element being required per apparatus or module. That makes it possible for the production costs of an apparatus of that kind to be quite considerably reduced as the operations which are necessary in connection with known apparatuses such as cutting to size the individual flat surface elements intended for a module and arranging them in the housing can be eliminated. Furthermore the flat element is put to more effective use as the filtering or separation process can take place uninterruptedly along the flow path of the flow medium to be treated. Filtration or separation can be effected even in the regions of the change in direction of the flow medium to be treated.
The arrangement of the flat filter element which extends in a meander-like configuration can be such that the flow medium to be treated is disposed along the flat filter element which is arranged in a meander shape, only on one surface side of the element, that is to say there is only a single flow channel or duct. In order to make better use of the flat filter element of a meander configuration however it can also be arranged in such a way that the flow medium to be treated flows along both sides thereof, that is to say there are two flow channels.
The orientation of the flat filter element extending in a meander configuration, in the housing, can be freely selected. In particular the region of the change in direction can be adapted to the respective circumstances involved. A particularly simple structure for the apparatus overall can be achieved if the flat filter element which extends in a meander configuration is accommodated in the housing substantially perpendicularly to the longitudinal axis of the housing, with the surfaces of the element extending in at least approximately mutually parallel relationship.
Furthermore, for the purposes of better stabilisation of the meander arrangement of the flat filter element and for the formation of the flow channel or channels, there can be provided in succession a plurality of carrier plates which form a spacing between them and which extend in substantially mutually parallel relationship. This carrier plates accommodate between them the flat filter element which is arranged in a meander configuration.
So that the change in direction of the flat filter element which is arranged in a meander configuration can occur in a uniform fashion and so that the filter element is supported in that situation, a carrier plate can be provided at one end edge with a direction-changing means for the flat filter element which is disposed in a meander configuration. In that arrangement, the direction-changing means can be such that it defines a direction-changing radius, which is large in relation to the plate thickness, for the flat filter element which is arranged in a meander configuration.
The direction-changing means may be formed for example by at least one direction-changing body which is provided at the end edge and which projects beyond the plate surface. So that the flow of the flow medium is disturbed as little as possible, it can further be provided that disposed along the end edge are a plurality of direction-changing bodies which are preferably arranged at equal spacings and which can be comparatively small, depending on the size of the carrier plate or the length of the end edge.
In order to be able to discharge the permeate from the apparatus, provided in the center of each carrier plate is an opening substantially perpendicular to the plane of the plate and which serves for the permeate discharge. So that the flow of the flow medium to be treated through the opening is disturbed as little as possible, it can further be provided that the opening is of an elliptical cross-section as considered in the plane of the plate.
That opening can be used at the same time for the arrangement of a clamping or tightening device which presses against each other the pack comprising the flat filter element arranged in a meander configuration and the optionally provided carrier plates. That clamping device can be formed by two respective flange elements which are tightened towards each other by way of a clamping bolt with an optionally provided screwthread and a nut. The opening can serve to receive the clamping bolt, while a guide ring can be provided in the opening, the inside diameter of the guide ring approximately corresponding to the ellipse along the shorter main axis.
So that the flow medium to be treated cannot flow on its way through the one flow channel in between the carrier plate and a flat or surface side of the flat filter element arranged in a meander configuration, it can further be provided that, at least at one of the two surface sides of the carrier plate, the opening has an edge which projects beyond the plane of that carrier plate and which completely surrounds the opening. In that case, the edge can be of such a configuration that it passes through the flat filter element
Altera Law Group LLC
Drodge Joseph W.
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