DK158201B - Flat membrane-filter device - Google Patents

Description

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DK 158201 B

The invention relates to a flat membrane filter apparatus of the kind set forth in the preamble of claim 1, with which dissolved and also partially suspended substances of real and colloidal solutions can be separated by ultrafiltration, reversosmosis and the like.

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In known flat membrane filter apparatus, fluid flows are produced by various means at the membrane surfaces of the filter discs to prevent the formation of inhibitory cover layers on the membranes and a concentration increase in the vicinity of the membrane.

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From DE Publication 25 45 482 a flat membrane filter apparatus of the specified kind is known in which the individual annular filter discs are attached to the container wall at their circumference and are held by means of outer spacers at predetermined intermediate distances. In the central interior is a rotating shaft to which discs are attached, which are arranged in the spaces between the filter discs. In each of the rough surfaces of these discs, curved radial grooves extend, which, like the impeller in a centrifugal pump, produce a centripetal force or pressure towards the inner disc edge, with which, due to the rotation of the discs, the centrifugal force is approximately equalized. In this way, the pressure of the fluid supplied to the container is kept approximately uniform in all surface areas of the filter discs 11, thereby avoiding a uniform filtration effect and damage to the filter elements or membranes. In order to equalize the bias from the larger turbulences in the radially outer regions of the rotating discs, the thickness of these discs continuously decreases in the outward direction, so that the height of the free slots increases accordingly. With this known apparatus, not only the small number of filter discs in relation to the dimensions, but also the reduction of the relative velocity from the outer disc edge towards the disc center, an undesirable current vortex length and the problems caused by the rotation of the rotating disc package, are a disadvantage, however. .

35 in DE Publication 28 14 924 discloses a rotary file therapy apparatus in which a container is disposed in a container as in a membrane press.

DK 158201 B

designed sTcive package. In spite of the procedural technical advantages obtained under certain circumstances, the complicated design of this apparatus cannot compensate for the failure of a circulation pump.

DD patent specification 114 205 describes an ultrafiltration apparatus in which pressurized joint chambers are placed in a pressure vessel which is actuated by means of compressed air and / or a circulating pump with the liquid to be separated. In the plate package are vortex rings with nozzle-like inlet channels, which, however, require separate inlet connections. However, the nozzle rays used to produce the desired eddy flow destroy near the nozzles the separating active layers of the membranes and lead to premature failure of the filter discs in permanent operation. Furthermore, the full effect of the vortex polarization can only be achieved under certain conditions. In the formation of a vortex flow by means of nozzles, an unfavorable cross-sectional relationship exists between the nozzle bore and the vortex chamber, so that a nozzle must be produced at a substantially greater velocity than that which manifests as tangential component at the outer edge of the vortex chamber. This results in large frictional losses and additional energy losses by destroying the velocity difference at the current fusion near the nozzle as far as possible. A further reduction of the tangential component is caused by the vortex flow conditional on a meridian component, which at the outer edge of the vortex chamber must be equal to a tangential cross-sectional expansion, so that the increasing distance 25 from the nozzle decreases accordingly, thereby deteriorating the boundary conditions of the vortex flow. These disadvantages can also not be remedied by applying more nozzles to each chamber, as the velocity difference at the outer edge can be reduced thereby, but where the rotating amount at the same cross section increases in the same ratio, or the ratio of the cross section of the vortex chamber to correspondingly reduced nozzle diameter becomes even more unfavorable and the solids capacity of the filter apparatus is significantly reduced.

It is an object of the invention to provide a flat membrane filter apparatus where the disadvantages of the prior art are removed and the

DK 158201 B

- 3 - a more favorable relationship between filter capacity and energy supply is achieved, as well as increased solids capacity.

SUMMARY OF THE INVENTION The object of the invention is to provide a flat membrane filter apparatus of the specified kind, in which large filter effects are obtained by means of a broadly variable, equalized vortex flow, so that both energy peaks and sub-polarized surface parts as well as local overloads of the membranes are avoided.

10 This task is solved by the properties specified in the characterizing part of claim 1.

The filter apparatus according to the invention enables a reduction in energy losses and a reduced sensitivity to solids loads. 15 completely offset edge flows can be obtained. The coriolis and centripetal forces, as well as the fluid friction, are taken into account in such a way that an approximately constant flow rate is already ensured at small circulation lengths in a turbulence that reaches the total surface, whereby the energy demand is further reduced because eddy flow, where c ^ r = constant, occurring radial pressure differences can be substantially reduced.

According to the invention, the rotary component formed in the form of a stirrer produces in all slots the peripheral speed necessary for a vortex flow, whereby the necessary meridian components can be produced by a circulating pump.

According to one embodiment of the invention, the rotating component is combined with a conveying device such that the circumferential velocity as well as the meridian rich components of the conveying stream are directly utilized for the vortex generation and a separate circulation pump may lapse. Particularly for smaller volumes of circulation, the transport device may be designed as an injector disc attached to the disk package or container, where a negative pressure around the rotary component is utilized to transport the depolarizing fluid from the through inner channel to the outer annulus.

DK 158201B

- 4 - Conveniently, three spacer rings according to the invention are preferably arranged in the vicinity of the inner diameter of the discs so that their inner space aligns with the transverse bores of the filter discs. Clamping bolts, longitudinally grooved or flattened, are according to 5 an embodiment of the invention passed through these transverse bores and spacer rings and mounted with a flange on an end surface of the container so that the filter discs and spacer rings are tightened together. The per-meat assembled in the porous portion of the filter disc is guided through the perforated space of the filter discs into the transverse bores or axial passages of the clamping bolts, the spacer rings being pressed against plates inserted in the filter discs around the transverse bores, which equalize the flow cross section for the porous disc resting surface, which is reduced by means of clamping pressure, by means of ducts or bores.

The crude solution to be filtered is passed under pressure into the container of the flat membrane filter apparatus, so that a driving force for a fluid flow through the membranes is created. Herein, the dissolved substances are retained by the membranes, while the solvent referred to as permeate flows into the porous material embedded between the membranes and the filter discs 20 and flows parallel to the filter discs towards the liquid-permeable plate and is passed through the grooves or discharges in the clamping bolts of the container. end wall.

The grooves or discharges on the clamping bolts preferably result in a tightly covered ring groove such that the permeate is removed from the container 25 via an outlet plug connected to the ring groove.

In the design with only a rotating component in the outer annulus, the crude solution of a circulation pump is transported via preferably tangential inlet bores into the container and accelerated by the rotary component designed as a stirrer in the circumferential direction so that in the annulus between the container wall and filter skid current, at a speed corresponding to the stirring speed. The circumferential velocity component is overlaid by a meridian component resulting from the transport flow such that the liquid is pressed radially inward through the gap spaces from the periphery of the filter discs.

DK 158201 B

ne. Hereby, the radial motion produces tangential acceleration forces which are equivalent to the opposite frictional forces such that the magnitude of the circumferential velocity in the annular space is maintained over the total disc surfaces until the inlet into the central inner channel.

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By combining the agitator with a further impeller or disc-shaped injector, additional energy benefits can be obtained by lapsing the outer perimeter elements and by directly utilizing the perimeter components already formed during the liquid transport. In this variant, the liquid is fed directly from the inner duct to the inlet opening of the conveyor so that a circulation flow occurs within the container and an external circulation pump can lapse. Also in these designs, the required filtration pressure is adjusted by means of compressed air.

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The invention is explained in the following by means of an exemplary embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section through a flat membrane filter apparatus with 20 agitators; FIG. 2 shows a cross section of a flat membrane filter unit with stirrer; FIG. 3 is a detailed longitudinal section through the disk package of the flat membrane filter apparatus; and FIG. 4 is a longitudinal section through a flat diaphragm f in an apparatus where the stirrer is combined with a radial conveyor impeller.

FIG. 1 shows a flat membrane filter apparatus, in which the filter discs 1 are clamped by three clamping and permeate removal bolts 2, 30, which are provided with a longitudinal groove, mounted on the lower end surface of the container 3 with a flange in which the three spacer rings 4 are inserted. between each disc pair provides a slot 5, 6 which is determined in accordance with the height of the spacer rings 4 and which is open at the outer and inner disc radius. Below, the filter discs 1 of 35 are coated in a manner known per se with a porous material 7 and one thereon - 6 -

DK 158201 B

adjacent semipermeable membrane 8 or other filter means and is sealed at the edges sealingly to the filter disk 1 by suitable means. Thereby, in the flat membrane filter apparatus, two separate fluid spaces are formed, the permeate space being connected to the ring groove of the end flange 59 and to the outlet nozzle 10, and where the concentrate space communicates via the preferably tangential inlet bores 11 and the outlet nozzles 12 with the circulation pump not shown in the drawing.

The embodiment of FIG. 1, the stirrer variant shown in Fig. 1 consists of a finger stirrer 13 rotatably mounted in the container bottom flange and sealed against the fluid pressure and a single or group drive known in the drawing. Occasionally, however, a design as a magnetic stirrer may also be advantageous.

15 With small flat membrane filter units, advantages can also be obtained of a stirrer driven only by tangent in the total flowing concentrate, although in this case it only compensates for speed differences at the periphery of the filter discs 1.

The concentrate flowing through the inlet bores 11 in the container through the circulation pump 11 is accelerated in the circumferential direction by means of the stirrer 13 and / or equalized velocity, whereby an appropriate choice between the magnitude of the circumferential velocity and the transported amount at each point of the gap spaces limited by file -25 the discs 1, keep the perimeter component thus produced constant.

FIG. 2 illustrates a velocity image which can be produced by the embodiment of the invention obtainable above the membrane surface already at relatively small meridian velocities cm. The embodiment 30 further shows the cross-section of the blades 14 which are at an angle a so that a slip between the tubes is formed - and the concentrate movement, which enables a tube drive without downshifting with a drive and also produces a radial transport pressure. A further advantage is that the angle of incidence α is easily adjustable with the stirrer blades 14, which are pivotally attached about the longitudinal axis of the stirrer 13, to the requirements.

DK 158201B

- 7 - without changing the rpm of the stirrer 13. Furthermore, at larger flat membrane filter units, different angles of incidence α over the length of the stirring blades 14 can be obtained by stirring blades 14 which are spatially curved, of which a different differential pressure conditional on the flowing concentrate 5 between the outer and inner disc radius is offset.

FIG. 3 shows a detailed length section through the disk package of the flat membrane filter apparatus, with further explanation of the permeation method of the permeate from the porous material 7 embedded between the filter disk 1 and the membrane 8. The reduced cross-sectional area of the porous material 7 decreases in the area around the spacings 4 with the clamping pressure from the clamping bolts 7, taking into account the holes 15 inserted on both sides of the filter disc 1, the hole 15 flowing through the bores into the plates. 15 encloses cavity 16, from which it flows into the longitudinal grooves in the clamping bolt 2 to the ring groove in the end flange 9.

FIG. 4 shows a longitudinal section through a flat membrane filter apparatus, 20 in which the stirrer 13 differs from a design according to FIG. 1, is combined with a radial conveyor impeller 17 such that the concentrate used for depolarizing circulates only within the flat membrane filtration apparatus. The conveyor impeller 17, among other things, directly produces both the circumferential component cu required for the vortex flow and the simultaneously required meridian velocity cm, while the stirring blades 14 associated with the impeller impeller 17 maintain the circumferential velocity thus obtained over the entire height of the disc package. Stirring blades 14 formed in accordance with FIG. 2, which is set at a certain angle a, is advantageous here, so that the circumferential velocity u 30 of the conveyor impeller 17 can be set greater than the circumferential component cu of the vortex flow. For large flat membrane filter devices, stirring blades, which are further spatially curved, become advantageous, while they can be completely eliminated when there is only a small number of discs, so that for transport and swirling only a transport impeller 17 is required for cooling the depolarizing liquid. is the container 3 - 8 -

DK 158201 B

preferably provided with a cooling jacket, but a circuit with an outlet plug 12 according to FIG. 1 and a further preferably inlet plug inserted in the opposite end wall, which circuit may contain a parallel cooling apparatus.

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Claims (7)

A flat membrane filter apparatus for ultrafiltration, reverse osmosis and the like, consisting of a cylindrical container (3) with a drain (10, 12) for both the permeate and the concentrate, of a stack of annular filter discs with internal permeate space arranged by means of spacers - 5 predetermined spaces in the container and delimiting radially inner and outer open gap spaces, and of a rotating component of the container which produces a turbulence in the gap spaces at the active disc surfaces of the filter discs, characterized in that the rotating component (13, 14) is arranged in an annular space (5) 10 between the filter discs (1) and the container wall (3) and produces in the gap spaces a flow directed towards the axially through inner space (6) and that in the form of spacer rings (4) between the spacers (1) provided by spacers via transverse bores in the filter discs (1) communicate with the permeate spaces (16) of the filter discs (1). 15 Filter apparatus according to claim 1, characterized in that the rotating component (13) has several curved blades which can be adjusted at different angles α with respect to the flow direction. Filter apparatus according to claim 1 or 2, characterized in that clamping bolts (2) with axial permeate channels are provided in the transverse bores of the filter discs (1) and in the flushing spacer rings (4). Filter apparatus according to claim 3, characterized in that at least one plate (15) having permeate channels (16) leading from the filter disc (1) is coated with a porous material (7). porous coating for the cross bore. Filter apparatus according to any one of the preceding claims, characterized in that a transport device (17) is further arranged in the container (3) which produces a circulating backflow of the concentrate within the container (3) from the through-going interior space (6). ) to the outer annulus (5). - 10 - DK 158201 B Filter apparatus according to claim 5, characterized in that the conveying device comprises a paddle wheel (17), which is fixed with radial vanes, which is fixedly connected to the rotating coponent (13, 14) and is arranged in a space at the end of the filter disc package. 5 Filter apparatus according to any one of claims 1-4, characterized in that tangential inlet nozzles (11) are fixed to the container (3) which open into the outer annulus (5).