DE102005027509A1 - Filer to separate solid particles in suspension from fluid has filter elements located at boundary between two vortex systems - Google Patents

Abstract

A filter for a suspended mixture of solids and fluids has a housing (2) rotating around a central axis (1) with a tangential inlet (10). The incoming suspension is subject to a combination of tangential and axial forces. A secondary vortex (25) is formed at the core, with the same tangential direction but a reversed axial component. The housing incorporates a filter assembly (12) with a number of filter elements (13) located at the boundary between the primary (24) and secondary vortices (24), and facilitate interaction between the two (24, 25).

Description

The The invention relates to a device for filtering fluid-solid mixtures according to the generic term of claim 1 and a filter element according to the preamble of patent claim 24.

Of the Field of application of the invention extends over the entire field of Membrane filtration and thus covers both the micro- as well Ultra- as well as nanofiltration. Even in the field of reverse osmosis the implementation of the invention is possible.

The The basic principle of the filtration is to pass the fluid-solid mixture to be filtered on a filter surface, the openings or pores are matched to the fluid-solid mixture, that at least one component from the mixture unhindered the filter surface flow through can, while the remaining Components of the filter surface retained become. Driving force for the flow the filter surface is the pressure difference between the area in front of the filter surface and the Area behind it.

at the static filtration becomes the fluid-solid mixture to be filtered guided under pressure into the filter area in front of the filter surface, from where it passes through the filter as a result of the transmembrane pressure as a filtrate. This will collect larger particles on the filter surface and form a filter cake. This process is also called covering layer formation or blocking. The consequence is a reduced filter performance, although compensated to a certain extent by an increase in transmembrane pressure can be. The maximum applicable pressure is, however, of the Type of mixture to be filtered and mechanical strength the filter is limited.

Sinks the filter performance due to topcoat formation below a certain Limit, must be static Filter at regular intervals by backwashing and / or cleaning the filter surfaces of Blockages are freed. This affects as a result of the interruption the filtration operation disadvantageous and drives by the so associated maintenance costs the operating costs in the amount.

Around reducing the tendency to block is as a cross-flow filtration Also already known, on the pressure side, an overflow parallel to the filter surfaces produce. In this case, directed parallel to the filter surface shear forces, the the at the filter surface remove adhering particles wholly or at least partially. Of the The advantage of cross-flow filtration is above all in the longer service life the filter elements. The disadvantage, however, prove the large volumes the fluid-solid mixture, to generate the overflow in the Circulation must be pumped and thus cause a high energy demand.

A Further development of known filter systems represents the dynamic Filtration is in which an overflow of the filter surfaces by a movement of the filter relative to the mixture to be filtered is achieved. This can be done, for example, by rotating filter elements inside the filter housing be achieved. This makes it possible with low transmembrane pressure and low pump power sufficient strong flow over the filter surfaces to keep them largely free from blocking. However, the rotating mechanism requires a complex and thus expensive construction of the filter device. In addition, the moved against necessary and pressurized seals against Machine parts is always a latent vulnerability in the system.

From the DE 199 146 74 A1 a filter is known which has a rotationally symmetrical about a longitudinal axis housing in the form of a cylinder or cone. A coaxial with the longitudinal axis extending dip tube penetrates the lid of the housing and ends at a sufficient distance from the housing bottom, wherein the opening out of the housing upper part serves as an overflow nozzle. The dip tube is peripherally surrounded by a cylindrical filter element, in the filtrate the filtrate is collected and passed through another outlet from the filter.

The Charging this filter is tangential in the upper area to the housing periphery, causing between the housing wall and the dip tube around the longitudinal axis circulating primary vertebrae with constant sense of rotation and a downward axial Movement component arises. In the bottom area of the housing finds a reversal of the axial component of motion, so that in the dip tube an upward flowing secondary vortex with the same sense of rotation. The dip tube thus provides a spatial Separation between the primary vertebra and the secondary vortex representing an interaction between primary vertebrae and secondary vertebrae Completely in derogation. The filter element surrounding the dip tube is located thus exclusively in the sphere of action of the primary vertebra and becomes exclusive from the outside to flows through radially inside. The concentrated mixture is withdrawn from the filter housing via the overflow nozzle and can be fed to the inlet, for example, for re-filtration.

aim this constructive filter training is a tangential overflow of the cylindrical filter element to achieve high speed to slow down the process of topcoat formation or whole to avoid. The authoritative Disadvantage of this filter is the arrangement of a dip tube between outer and internal vortex. This results in two spatially completely separate from each other separate vortex systems without any mutual influence. Such vortex systems are very unstable, with the disadvantage a strongly fluctuating filter throughput. In addition, has the on the cylindrical filter surface adjoining laminar overflow only limited potential to solve blockages, so Although a cover layer formation delayed, but not completely prevented can be.

In front In this context, the object of the invention is to provide a To provide a device for filtering fluid-solid mixtures, the with minimal energetic and operational effort of a Cover layer formation efficiently counteracts. Further task of Invention it is a for to develop such a device suitable filter element.

These Tasks are achieved by a device having the features of the claim 1 and a filter element with the features of claim 24 solved.

advantageous Further developments emerge from the subclaims.

Of the The basic idea of the invention is, by creating a primary vortex and secondary vertebrae in a rotationally symmetrical housing a zone highly turbulent flow conditions to create and this to avoid a topcoat on the filter surfaces exploit. Unlike the filter described above, in which an interfering of the primary vertebra with the secondary vertebrae is found to be disadvantageous, the invention is based on a Interaction between the outer primary vertebra and the inner secondary vortex. This interaction is made possible through a filter unit, in which a flow exchange of a vortex on the other hand is possible. According to the invention finds this exchange in which by the mutual distance between instead of the filter elements created space.

By in a filter according to the invention adjusting pronounced Differential speed between the primary vortex and the secondary vortex as well as their opposite axial directions of movement is in the transition region of the created a zone of extreme turbulence in both vortices. In combination with the arrangement of the filter surfaces in this zone, a cover layer formation is efficiently counteracted, by getting on the filter surface settling particles are released immediately.

It the merit of the invention recognizes these relationships and won To have merged findings in the invention.

There the filter surfaces are kept free of blockages, arise first greater Advantage of the invention first the very high filter life. These allow the operator Inventive filter device a reduced maintenance and therefore more economical filtration operation.

There the filter surfaces remain free from blocking, a lower transmembrane pressure is sufficient for Operation of a filter according to the invention. This has the advantage that even pressure-sensitive substances with a Device according to the invention can be filtered. In addition leads a lower operating pressure to a lower energy consumption.

One inventive filter is characterized by an evenly uniform loading of the filter surfaces the fluid-solid mixture. As a result, a pressure gradient in the overflow of the filter surfaces avoided. This causes a constant high degree of turbulence and equal permanent transmembrane pressure and thus evenly high Filter throughput the entire filter surface.

Of the for the Operation of a filter according to the invention required pump pressure is limited on the generation of a potential vortex in the filter housing. This Pressure is opposite the cross-flow filtration is low, so too due to this Fact an economical operation with low energy consumption possible is.

The constructive design of a filter according to the invention is completely without moving parts. This results in a simple construction, the cost-effective can be produced. Since pressure-resistant seals moved against Parts are omitted, which experience has shown are often the cause of breakdowns, a filter according to the invention is characterized through an increased Operational safety known filter devices.

As a result of the prevailing swirling flows particles with a higher density than the fluid are already carried out in the primary vortex due to the force of the flight, where they fall down on the housing wall. In this respect, a deposition of particles already takes place before they reach the filter surface, where they may be the top layer education could contribute. On the other hand, lighter particle particles can enter the secondary vortex, where they are in part driven radially outward along the filter surfaces by the action of a force of flying force. They collide with particles on the filter surfaces and dissolve them, which helps to prevent the formation of a cover layer.

A advantageous embodiment the invention provides annular disk-shaped filter elements, the in axial distance coaxial and plane parallel in the filter housing with radial distance to the housing wall are arranged. This results in the filter unit only minor disturbances of the vertebral system at a maximum possible interaction between the primary vertebra and secondary vertebrae. In addition, by ring-shaped Filter elements a relatively large filter area in the provided turbulent zone and thus the effect of the invention optimally used.

It has been shown to be a stable vortex system with pronounced turbulence zone is achieved with filter elements with a ratio of disk radius to Radius of the central opening in a range between 2: 1 to 5: 1 Distance between the filter elements between 2 mm and 5 mm lie. A filter unit preferably has between 30 and 50 such annular disc-shaped Filter elements. To stabilize the vertebral system may further in the inlet and / or in the overflow and / or underflow nozzle a Control valve for controlling the pressure conditions in the device according to the invention be provided.

The filter housing preferably has the shape of a simple to produce Hollow cylinder. Likewise conceivable is an embodiment in the form of a hollow cone, which tapers towards the floor. In this way can be achieved be that the decreasing downwards as a result of the filtrate Mixture quantity with constant peripheral speed in the primary vortex flows.

Further a development of the invention is preferred in which at least the bottom of the case hollow cone is formed around a collecting space for the housing circumference to form downward sinking solid particles. advantageously, owns the housing in the bottom area a solids removal around the accumulated solid particles there remove it cyclically or continuously from the filter.

in the Area of the bottom of the housing can also arranged flow control be on the one hand to promote the formation of the secondary vortex. On the other hand, this can be achieved by being located on the ground Solid particles not due to the existing flow conditions agitate and promote topcoat formation.

At the End of the secondary vortex is preferably arranged an overflow nozzle, which allows a deduction of the concentrated fluid-solid mixture. It proves to be advantageous, the overflow nozzle in the axial direction adjustable train to a direct flow from the inlet to the overflow nozzle. For this reason, it is preferred that the overflow nozzle in the form of a dip tube at least to the uppermost annular disk-shaped filter element respectively.

From It is particularly advantageous if the concentrated fluid-solid mixture after leaving of the filter housing is returned to the inlet. In this way, only one of the filtrate must be appropriate Amount of fluid-solid mixture additionally into the filter housing be passed, whereby the volumes to be pumped are minimized.

One Inventive filter element is characterized by its areal Shape with central opening out. This makes it possible a filter element with its surface almost plane parallel to Primary- and secondary vertebrae to arrange with the advantage of hardly disturbing the vortex flow. The a substantially two-dimensional shape of the filter element also allows the provision of relatively large filter surfaces its top and / or bottom. By the possibility filter elements according to the invention due to their shape with a close distance to be able to fit together plane-parallel arises a compact, supreme powerful and streamlined Filter package.

The openings in the area of the filter surfaces to Deduction of the filtrate are in an advantageous embodiment of the invention so arranged for Filtrate accumulating filtrate everywhere as short as possible to the openings result. So finds a uniform admission all filtrate channels instead.

Especially preferred is an embodiment with three openings, at the same time for receiving the rod-shaped holder for clamping the Filter elements to serve a filter pack. This allows a tension-free attachment of the individual filter elements within a filter pack.

The invention will be explained in more detail with reference to an embodiment shown in the drawings. Without limiting itself to the embodiment relates to the Filtra tion of liquids from which, for example, bacteria are to be removed.

It demonstrate

1 a vertical section through a device according to the invention along the in 2 illustrated line II,

2 a horizontal section through the in 1 and 4 shown device along the local line II-II,

3 a plan view of a filter element according to the invention and

4 a vertical section through a further embodiment of the invention.

From the 1 and 2 the more detailed structure of a device according to the invention can be seen. You see an axis 1 to a housing 2 is arranged rotationally symmetrical. The housing 2 essentially consists of an upper cylindrical section 3 and a lower cone-shaped portion 4 together. The cylindrical section 3 is above by means of a lid 5 closed in the area of the axis 1 a concentric opening 6 has. The opening 6 serves to carry out a cylindrical dip tube 7 which has the function of an overflow nozzle. By suitable means, such as a thread, the dip tube 7 in the axial direction relative to the lid 5 arranged adjustable. The section 4 of the housing 2 tapers conically downwards and has a tubular solids discharge at its low point 8th into which a regulatory organ 9 is integrated.

Below the lid 5 you see an enema 10 , About the loading of the device according to the invention with the fluid-solid mixture 11 he follows. The enema 10 opens tangentially into the cylindrical housing section 3 one. The cylindrical housing section 3 serves to hold a filter unit 12 essentially comprising a plurality of annular disk-shaped filter elements 13 includes, as in 3 is shown in more detail.

The filter elements 13 consist essentially of a double-walled annular disc, which has a Filtratraum inside 16 houses. At least one side, preferably both the top and bottom of the filter elements 13 are permeable and thus form filter surfaces 14 out. In the center of the filter elements 13 you see a central circular opening 15 , As a result, each annular disk-shaped filter element 13 an outer edge 17 and an inner edge 18 on which the filtrate room 16 Seal in the radial direction and limit. Furthermore, in 3 three eccentric in the filter surfaces 14 arranged openings 19 shown which the filter element 13 penetrate and to the edge of the Filtratraum 16 is open.

A variety of such filter elements 13 is combined into a filter pack and into the housing 2 used. The filter elements take 13 a coaxial to the axis 1 lying position, in which they maintain a radial distance to the inner wall of the housing 2 plane-parallel and one above the other at axial mutual distance. The fixation of the filter elements 13 in the case 2 in this position happens via rod-shaped holder 20 that are inside the eccentric openings 19 through all filter elements 13 until over the lid 5 of the housing 2 extend beyond.

The radial wall distance of the filter elements 13 to the housing 2 is among other things the diameter of the filter elements 13 and the volume flow rate of the device. By a suitable choice of the radial wall distance, a laminar fluid flow can be achieved in the circumferential outer region of the primary vortex with the advantage of only low pressure losses. Without being limited thereto, a radial distance in the range of 10 to 30 mm, preferably approximately 20 mm, has proven itself during operation of a device according to the invention.

Between the individual filter elements 13 and the top filter element 13 and the lid 5 are the eccentric openings 19 circumferential spacers 21 interposed, which at the same time a sealing function against the filter elements 13 exercise. In this way arise in the area of eccentric openings 19 with the axis 1 axially parallel filtrate channels 22 , made up of spacers 21 and the openings 19 in the filter elements 13 , The filtrate channels 22 lead to the area of the lid 5 out of the case 2 and pass the filtrate (arrow 23 ) in a collecting container, not shown.

Furthermore, it is off 1 seen that the dip tube 7 so far in the case 2 is inserted that the lower end of the dip tube 7 with the top of the top filter element 13 flush. This allows the fluid-solid mixture 11 not directly from the inlet 10 in the from the dip tube 7 get formed upper jet.

The operation of the device according to the invention is explained as follows. About the enema 10 becomes the case 2 with sufficient pressure with a fluid-solid mixture 11 applied. Due to the tangential arrangement of the inlet 10 is doing in the circumferential area of the housing 2 initiated a circulating flow, which in the following as Pri märwirbel 24 referred to as. The primary vertebra 24 thus has a tangential component of movement due to the continuous feed through the inlet 10 is superimposed by an axially downward movement component.

In the ground-level area of the housing 2 If the vertical movement component is reversed while the direction of rotation remains the same, it forms around the axis in the core area 1 a secondary vortex 25 in the one of the centric openings 15 the filter elements 13 created space axially upwards in the housing 2 rises and this finally through the overflow nozzle in the form of the dip tube 7 as a concentrated fluid-solid mixture 26 leaves.

Both vertebrae 24 and 25 represent a potential vortex, so the tangential flow velocity decreases with decreasing distance to the axis 1 , ie in the direction of the filter surfaces 14 , increases.

Heavier in the fluid-solid mixture 11 contained particles are due to the primary vortex 24 prevailing centrifugal forces are carried radially outward, where they attach to the inner wall of the housing 2 slowly sink down and into the conical housing section 4 reach. About the solids removal 8th These solid particles are removed continuously or cyclically from the device according to the invention. Lighter particles can enter the secondary vortex 25 arrive, with which they the housing 2 over the dip tube 7 leave again. Part of these particles, however, is due to the secondary vortex 25 prevailing centrifugal forces in the cavity between the individual filter elements 13 carried to the outside and thereby enters the area of the primary vertebra 24 , The accompanying radial acceleration of the particles is sufficient, so that these too up to the inner wall of the housing 2 get where they gravitationally down in the solids removal 8th decline.

As a result of the pressure with which the fluid-solid mixture 11 in the case 2 is introduced, creates a pressure gradient opposite the Filtraträumen 16 the filter elements 13 , This pressure gradient, also referred to as transmembrane pressure, causes penetration of the filtrate 23 over the filter surfaces 14 in the filtrate room 16 where it is above the filtrate channels 22 out of the case 2 to be led. The associated tendency to cover layer formation on the filter surfaces 14 is due to the highly turbulent flow conditions in the transition region between the primary vortex 24 and the secondary vortex 25 counteracted. The resulting shear forces dissolve particles from the filter surfaces 14 , This effect is supported by those in the secondary vortex 25 entrained solid particles which, as described above, are carried by centrifugal force radially outwards.

4 shows a training in the 1 to 3 described invention. For this reason, the same reference numerals are used for the same features and, to avoid repetition, reference is made to what has been said there.

Unlike the ones in the 1 to 3 illustrated embodiments of the invention, the training according to 4 a return of the concentrated fluid-solid mixture 26 from the overflow nozzle into the inlet 10 in front. For this purpose, the dip tube 7 over a line 27 with the enema 10 connected. An intermediate circuit in this pump 28 provides the necessary pressure to feed the device according to the invention.

To compensate for the loss of the fluid-solid mixture 11 by the amount of withdrawn filtrate 23 is another line 29 to the line 27 connected, via the new, to be filtered fluid-solid mixture 11 from the pump 30 into the circulation and thus the enema 10 is pumped.

1

axis

2

casing

3

cylindrical section

4

Cone-shaped section

5

cover

6

Opening in cover

7

dip tube

8th

Solid deduction

9

Regulator

10

enema

11

Fluid-solid mixture

12

filter unit

13

filter element

14

filter area

15

Central opening in filter element

16

filtrate

17

Outer edge filter element

18

Inner Edge filter element

19

Eccentric opening filter element

20

Rod-shaped holder

21

spacer

22

filtrate

23

filtrate

24

primary Swirls

25

secondary vortex

26

Aufkonzentriertes Fluid-solid mixture

27

management

28

pump

29

management

30

pump

Claims (28)

Device for filtering fluid-solid mixtures ( 11 ), preferably suspensions, with one around an axis ( 1 ) rotationally symmetrical housing ( 2 ) with a tangential into the housing ( 2 ) opening enema ( 10 ), wherein by feeding the device with the fluid-solid mixture ( 11 ) over the inlet ( 10 ) in the circumferential area of the housing ( 2 ) a primary vertebra ( 24 ) with tangential and axial movement components and in the axial core region of the housing ( 2 ) a secondary vortex ( 25 ) is present with the same tangential but reversed axial movement component, characterized in that in the housing ( 2 ) a filter unit ( 12 ) is arranged, a plurality of each a filtrate ( 16 ) having filter elements ( 13 ) spaced apart from each other about the axis ( 1 ) are arranged so that the filter surfaces ( 14 ) of the filter elements ( 13 ) partially or entirely in the transition region between the primary vertebrae ( 24 ) and secondary vertebrae ( 25 ) are arranged and by the distance between the filter elements ( 13 ) an interaction between the primary vertebrae ( 24 ) and the secondary vortex ( 25 ) is possible. Device according to claim 1, characterized in that the filter elements ( 13 ) have annular disk-shaped form, coaxial with the axis ( 1 ) and plane-parallel with axial distance from each other in the housing ( 2 ) are arranged, wherein the outer edge ( 17 ) in the area of the primary vertebra ( 24 ) and the inner edge ( 18 ) in the area of the secondary vortex ( 19 ) lies. Device according to claim 2, characterized in that the outer edge ( 17 ) at a radial distance of 10 to 30 mm, preferably about 20 mm, to the housing ( 2 ) is arranged. Apparatus according to claim 2 or 3, characterized in that the radius of the annular disk-shaped filter element ( 13 ) 2 to 5 times the radius of the central opening ( 15 ) is. Device according to one of claims 2 to 4, characterized in that the axial spacing of the filter elements ( 13 ) is between each other between 2 mm and 10 mm, preferably 3 mm. Device according to one of claims 2 to 5, characterized in that the filter unit ( 12 ) 30 to 50 filter elements ( 13 ) owns. Device according to one of claims 2 to 6, characterized in that the filter unit ( 12 ) at least one, preferably 2 to 6, most preferably 3 rod-shaped holder ( 20 ) which is coaxial within the housing ( 2 ) are arranged and which the filter elements ( 13 ) in their position fix. Device according to claim 7, characterized in that each holder ( 20 ) from a clamping screw with spacers ( 21 ) consists. Device according to claim 7 or 8, characterized in that the holders ( 20 ) the filter elements ( 13 ) in the area of the filter surface ( 14 penetrate). Device according to one of claims 1 to 9, characterized in that the Filtraträume ( 16 ) of the filter elements ( 13 ) via at least one filtrate channel ( 22 ) and connected to a Filtratablauf. Apparatus according to claim 10, characterized in that the filter elements ( 13 ) to form the filtrate channel ( 22 ) in its filter surface ( 14 ) at least one opening ( 19 ) and the openings ( 19 ) of adjacent filter elements ( 13 ) in the axial direction congruent and the distances between adjacent filter elements ( 13 ) around the openings ( 19 ) of cylindrical sealing elements ( 21 ) are bridged. Apparatus according to claim 10 or 11, characterized in that the filter elements ( 13 ) to form the filtrate channel ( 22 ) in its filter surface ( 14 ) at least one opening ( 19 ) and the openings ( 19 ) of adjacent filter elements ( 13 ) in the axial direction congruent and the distances between adjacent filter elements ( 13 ) around the openings ( 19 ) of cylindrical spacers ( 21 ) are bridged. Device according to one of claims 7 to 12, characterized in that the holders ( 20 ) within the filtrate channel ( 22 ) are arranged. Device according to one of claims 1 to 13, characterized in that the filter elements ( 13 ) on both sides filter surfaces ( 14 ) exhibit. Device according to one of claims 1 to 14, characterized in that the filter elements ( 13 ) consist of ceramic, plastic or metal or a combination of these substances. Device according to one of claims 1 to 15, characterized in that the housing ( 2 ) has the shape of a hollow cylinder or hollow cone. Device according to one of claims 1 to 16, characterized in that the bottom of the housing ( 2 ) is formed in a hollow cone shape. Device according to one of claims 1 to 17, characterized in that the housing ( 2 ) at the lowest point a solids removal ( 8th ) having. Device according to one of claims 1 to 18, characterized that arranged in the region of the bottom flow control surfaces are. Device according to one of claims 1 to 19, characterized in that the lid ( 5 ) an overflow nozzle ( 7 ) for the fluid-solid mixture ( 11 ) having. Apparatus according to claim 20, characterized in that the overflow nozzle from a dip tube ( 7 ), which is opposite the housing ( 2 ) is adjustable in the axial direction. Apparatus according to claim 20 or 21, characterized in that the overflow nozzle ( 7 ) to the inlet ( 10 ) connected. Device according to one of claims 20 to 22, characterized in that in the inlet ( 10 ) and / or the overflow nozzle ( 7 ) is arranged a control valve for controlling the pressure conditions. Filter element suitable for use in a device according to one of claims 1 to 23, characterized in that the filter element ( 13 ) is designed as a double-walled annular disk which has a filtrate space ( 16 ) and the upper and / or lower side of the filter surface ( 14 ), wherein in the area of the filter surface ( 14 ) at least one, preferably three openings ( 19 ) to remove the filtrate from the filtrate ( 16 ) is provided. Filter element according to claim 24, characterized in that the openings ( 19 ) the central, inner opening ( 15 ) of the filter element ( 13 ) concentrically and preferably at a uniform distance surrounded with each other. Filter element according to claim 24 or 25, characterized in that the openings ( 19 ) approximately midway between the outer edge ( 17 ) and the inner edge ( 18 ) of the filter element ( 13 ) are arranged. Filter element according to one of claims 24 to 26, characterized in that the radius of the filter element ( 13 ) 2 to 5 times the radius of the central opening ( 15 ) is. Filter element according to one of claims 24 to 27, characterized in that the filter element ( 13 ) consists of ceramic, plastic or metal or a combination of these substances.