From DE 198 57 751 Al a modular filter is known which comprises an inlet for unfiltered material and an outlet for the filtrate as well as at least one filter module, wherein the filter module is comprised of filter cells and drainage support bodies stacked alternatingly. The filter cells and drainage support bodies have at least one central opening forming a central channel. The inflow of the unfiltered material into the interior of the filter cells is realized via this central channel. The filtrate flows out toward the outlet of the modular filter via drainage channels within the drainage support bodies.

When arranging several filter modules within a filter housing, parallel flow occurs through the filter modules and, in this way, one filter stage is provided in one filter housing.

The invention has the object to provide a modular filter of the aforementioned kind in which several filter stages can be realized.

This object is solved by a modular filter having the features of claim 1.

By arranging several filter stages in a modular filter container, the required constructive space is reduced in comparison to the arrangement of each filter stage in a separate modular filter container. The connecting lines between the individual filter stages are no longer required. In this way, the pressure loss related to the connecting line as well as the material loss caused by the dead space in the connecting lines, which particularly in the case of valuable substances increases the costs for the filtration, are eliminated. The arrangement of several filter stages in a single modular filter container simplifies cleaning. Moreover, the expenditure for the validation of the filter, particularly in the pharmaceutical field, is lowered because the expenditure depends on the number of modular filters and not on the number of filter stages. The modular system enables a great flexibility so that the filter stages can be individually adapted to the requirements of the filtration task. A commercially available container can be used as the modular filter container so that expensive investments are not required.

Expediently, the modular filter has at least one partition plate which separates chambers that are not directly sequentially arranged in the flow path from one another with regard to fluid flow. The partition plate is particularly arranged perpendicularly to the longitudinal axis of the central channel and separates two sections of the central channel with regard to fluid flow. As a result of the separation of the chambers in the central channel, seals at the housing wall are no longer needed which seals wear quickly and make handling more difficult. The separation of the chambers in the central channel utilizes already present sealing surfaces on the filter modules and does require any particular features in regard to the container wall so that no special modular filter containers are required.

At least one deflection plate can be provided which realizes a fluid flow connection from the exterior area of a filter module to the interior area of an adjoining filter module, wherein the interior area is the area enclosing the central channel of the filter module and the exterior area is the area of the filter module which is separated from the interior area by filter material. In this way, it is possible to realize flow within the filter modules sequentially in the same direction, from the interior to the exterior or vice versa.

Expediently, at least one intermediate plate is provided which is arranged between two filter modules and extends transversely to the longitudinal axis of the central channel. The intermediate plate serves as a support for the filter modules. On the upper container side a head plate can be provided which is arranged directly underneath the upper container side which is provided with an opening.

In the area of the upper container side, especially a venting channel is provided which enables a fluid flow connection between the interior of the modular filter container, in particular, between an upper chamber arranged on the container wall and the exterior side of the container. Expediently, an adapter plate is arranged on the container bottom which has a central opening which opens into the opening provided within the container bottom. An outlet can be provided which is connected with a chamber, into which neither the opening arranged in the upper container side nor the opening provided within the container bottom opens, and which is arranged particularly in the container bottom. Expediently, the opening arranged at the upper container side opens into the central channel of the neighboring module or modules. Moreover, it may be provided that the opening in the container bottom is connected to the central channel.

Expediently, flow from the interior area to the exterior area is realized in at least one of the filter modules.

The substances which have been removed by filtration are collected in this way within the interior area of a filter module and can be removed in a simple way from the modular filter container together with the filter module.

It can be provided that at least one filter module is a filter module for prefiltration and at least one filter module is a filter module for sterile filtration, wherein the filter module for sterile filtration is arranged expediently in the flow path downstream of the module for prefiltration. In particular, at least one filter module is a filled module. It is provided that the filled module is filled with adsorbent material. The adsorbent material can be, at least partially, activated charcoal and, in particular, an additional filter module arranged in the modular filter container can be in the form of a filter module for layer filtration.

At least a partial filling with diatomite can be provided for the filled module, wherein, in particular, one filled module is provided for prefiltration and at least one filled module is provided for fine filtration.

Particularly in the case of filtration of valuable substances, it can be expedient that at least one filter module has an encapsulation.

Embodiments of the invention will be explained in the following with the aid of the drawing. It is shown in: Fig. 1 in a schematic illustration a modular filter with partition plates and a first flow direction; Fig. 2 the modular filter of Fig. 1 with a second flow direction; Fig. 3 a schematic illustration of a modular filter with deflection plates.

Fig. 1 shows a modular filter 1 in which four filter modules 25, 26, 27,28 are arranged above one another in a modular filter container 2. The modular filter container 2 comprises a pot-shaped container housing 3 and a container bottom 4 arranged at the open end of the container housing 3 and forming the underside of the modular filter 1. The container housing 3 and the container bottom 4 are connected by connecting means 5, for example, with clamping screws, in a pressure-tight way. At the center of the container bottom 4 an opening 7 is arranged which is configured as a line connector and, depending on the flow direction, can serve as an inlet for the unfiltered material or an outlet for the filtrate.

At the upper container side 17 of the modular filter 1, a container socket 10 is formed on the container housing 3.

It is penetrated by a projection of a head plate 11 which is arranged in the modular filter housing 2 directly underneath the upper container side 17 perpendicularly to the longitudinal axis of the container. The head plate 11 comprises a central opening 6 which is embodied as a line connector and which can serve as an inlet or an outlet.

Underneath the head plate 11, four filter modules 25,26, 27,28 are arranged. The filter modules 25,26, 27,28 are comprised of stacked, disk-shaped filter cells, substantially comprised of filter material, and of drainage support bodies. The filter modules, depending on the filtration task, can be comprised of different filter materials and can be filled with filtering aids. The filter cells and drainage support bodies have a central opening forming a central channel 16, 16', wherein the longitudinal axis of the central channel 16, 16'is at the same time the longitudinal axis of the container housing 3. A central channel section 21 is arranged on the upper side of each filter module 25,26, 27,28, and a central channel section 22 is provided on the underside of each filter module 25, 26,27, 28. The central channel sections 21 and 22 project in the direction of the central longitudinal axis of the channel past the section of the filter modules 25,26, 27, 28 comprising the filter cells. The central channel section 21 has an enlarged diameter and a shoulder 23 at the upper edge of the filter module.

Between the filter modules 25 and 26 and the filter modules 27 and 28 an intermediate plate 14 is arranged, respectively, which supports the filter modules 25,26, 27,28. In this connection, the section 22 of the central channel 16, 16'of a filter module 25,27 arranged above an intermediate plate 14 and the upper section 21 of the central channel 16, 16'of a filter module 26,28 arranged underneath an intermediate plate 14 project into an opening in the intermediate plate 14, wherein the lower central channel section 22 of the upper filter module 25,27 is arranged within the upper central channel section 21 of the lower filter module 26,28 and rests on the shoulder 23.

The two filter modules 25 and 27 are connected in this way with one of the two filter modules 26 and 28, respectively, in a fluid flow connection via the central channel sections 21 and 22.

The interior areas of the filter modules 25 and 26 comprising the central channel 16 form a first chamber 18 ; between the exterior area of the filter modules 25,26, 27, 28 and the modular filter container 2 a second chamber 19 is formed; and the two filter modules 27 and 28 form a third chamber 20. In the head plate 11 a vent 8 is provided which connects in fluid flow connection the second chamber 19 with the exterior side of the modular filter container 2 and is embodied, for example, as a channel which extends along the top side of the head plate 11 and exits at the container socket 10. Between the first chamber 18 and the third chamber 20, a partition plate 13 is arranged within the central channel 16, 16'. It separates the fluid flow connection of the section of the central channel 16 formed by the two upper filter modules 25 and 26 from the section of the central channel 16'formed by the two lower filter modules 27 and 28. In this connection, the central channel section 22 of the filter module 26 projects into a groove provided at the top side of the partition plate 13 and the central channel section 21 of the filter module 27 into a groove on its bottom side. On the top side of the partition plate 13, a guide 45 is centrally arranged and guides and centers the filter module 26 on the interior side of the central channel section 22. On the container bottom 4 an adapter plate 12 is arranged which has a central opening which provides a connection between the lower filter module 28 and the opening 7 in the container bottom 4, wherein the adapter plate at the same time seals the second chamber 19 relative to the opening 7.

In the container bottom 4 a further opening 9 is arranged which is displaced radially outwardly relative to the opening 7 and connects the second chamber 19 in a fluid flow connection with the exterior side of the modular filter container 2. The opening 9 serves for completely emptying the container 2 and is also embodied as a line connector.

The interior area of the filter modules 25,26, 27,28 is sealed relative to the exterior area at sealing locations 15. The sealing locations 15 are arranged between an upper central channel section 21 and a lower central channel section 22 of the stacked filter modules 26 and 27. At the filter module 25, which is arranged directly underneath the head plate 11, the sealing location 15 is arranged in the section of the head plate surrounding the central channel section 21. Correspondingly, a sealing location 15 is arranged, respectively, within the area of the partition plate 13 surrounding the central channel sections 21 and 22. Also, a sealing location 15 is arranged between the central channel section 22 of the filter module 28 and the area of the adapter plate 12 surrounding it. The sealing surfaces 15 can also be arranged on an end face of the filter modules 25,26, 27,28. This can be advantageous when the filter modules 25,26, 27,28 have no central channel sections 21 and 22.

The arrows 24 illustrate the flow direction of a fluid through the modular filter 1 in Fig. 1. The opening 6, which is embodied as a line connector, forms the inlet through which the unfiltered material flows into the first chamber 18 which is formed by the two filter modules 25 and 26. From here, it flows through the filter cells of the filter modules 25 and 26 into the second chamber 19 and passes through the first filtration stage. This intermediate filtrate which represents an intermediate stage of the final filtrate can be removed via the opening 9, for example, for monitoring purposes. The intermediate filtrate flows through the filter cells of the filter modules 27 and 28 into the third chamber 20 and in this way passes through the second filtration stage. The final filtrate in the third chamber exits the modular filter 1 through the opening 7 which is embodied as a line connector and serves as an outlet. In this arrangement the filter modules 25 and 26 have a flow direction from the interior to the exterior, and the filter modules 27 and 28 have a flow direction from the exterior to the interior.

In Fig. 2 the modular filter 1 of Fig. 1 is illustrated with a second possible flow path which is illustrated by the arrows 29, wherein in Figs. 1 and 2 identical reference numerals identify identical parts. The unfiltered material flows through the opening 7, which functions as an inlet and is provided in the container bottom 4, into the chamber 20, flows from the chamber 20 through the filter cells of the filter modules 27 and 28 into the chamber 19 and passes through the first filtration stage in this way and generates an intermediate filtrate which can be removed through the opening 9. The intermediate filtrate flows through the filter cells of the filter modules 25 and 26 into the chamber 18 from where it exits the modular filter container 2 as the final filtrate through the opening 6 which serves as an outlet. In this flow direction, the modules 25 and 26 have a fluid flow direction from the exterior to the interior and the filter modules 27 and 28 have a flow direction from the interior to the exterior.

In Fig. 3 an arrangement of three filter modules 31,32, 33 is illustrated. The filter modules 31,32, 33 have an encapsulation 34 which is comprised of a flexible, expandable material and encapsulates the exterior area of the filter modules 31,32, 33 relative to the surroundings so that each filter module 31,32, 33 comprises an interior chamber and an exterior chamber, wherein the inner chamber is the chamber surrounding the central channel 16, 16', 16"and the exterior chamber is formed by the exterior side of the filter cells and the encapsulation 34. The encapsulation 34 can be embodied, for example, as a film bag. Between the filter modules 31 and 32 and the filter modules 32 and 33, a deflection plate 37 is arranged, respectively, which supports the filter modules 31,32, 33. The exterior surfaces of the deflection plate 37, extending perpendicularly to the longitudinal axis of the modular filter container 2, are concave in order to provide a good support surfaces for the encapsulation 34. The annular gap 39 which is formed between the container housing 3 and the deflection plate 37 is so narrow that the encapsulation 34 cannot curve significantly into the annular gap 39 so that damage to the encapsulation 34 is prevented. The deflection plate 37 has deflection channels which form a fluid flow connection 38 with the annular gap arranged underneath the filter module 31 between the exterior chamber of the filter module 31 and the inner chamber of the filter module 32. In the modular filter container 2 a total of four chambers are formed, wherein a first chamber 35 is formed by the inner chamber of the filter module 31; the second chamber 36 by the outer chamber of the filter module 31, the fluid flow connection 38 formed by the deflection channels, and the interior chamber of the filter module 32 ; the third chamber 43 by the exterior chamber of the filter module 32 and the inner chamber of the filter module 33 ; and the fourth chamber by the exterior chamber of the filter module 33.

Between the deflection plate 37 and the portion of the central channel 16, 16', 16"projecting past the filter modules 31,32, 33, a sealing location 40 is provided which seals the interior chamber relative to the exterior chamber. The portions of the central channel 16, 16', 16" projecting past the filter modules 31,32, 33 are configured to have the same diameter as the central channel 16, 16', 16"itself. At a greater radial distance to the longitudinal axis of the container housing 3, a sealing location 41 is arranged which seals the exterior chamber formed by the encapsulation 34 relative to the interior of the container housing 3. For example, sealing rings can be provided at the sealing locations 40 and 41 in order to provide a sealing action.

On the upper container side 17 a head plate 47 is arranged which has a concavely formed underside. Between the head plate 47 and the container housing 3 a narrow annular gap is formed which enables removal of the head plate 47 from the modular filter container 2 and, at the same time, prevents inward curving of the encapsulation 34 into the annular gap. A vent 8 is provided in the head plate 47 which realizes a fluid flow connection between the interior of the modular filter container 2 and the exterior side of the container.

An adapter plate 42 is arranged on the container bottom 4 which has a concave top side and whose deflection channels 38 connect the fourth chamber 44 with the opening 7 provided in the container bottom 4, wherein the opening 7 serves as an outlet for the final filtrate. The adapter plate 42 serves for supporting the filter module 33.

On the topside of the adapter plate 42 and the deflection plates 37 a guide 45 is centrally arranged which guides and centers the filter modules 31,32, 33 arranged at the upper side of the adapter plate 42 and the deflection plates 37 on a section of the inner side of the central channel 16, 16', 16''. On the top side of the adapter plate 42 and the deflection plates 37 and on the underside of the head plate 47 and the deflection plates 37, a guide ring 46 is formed, respectively, which serves for guiding and centering the central channel sections arranged therein as well as for sealing the interior chamber of the filter modules relative to the exterior chamber of the filter modules. The guide ring 46 can also serve as a holding means for a sealing element arranged between it and the central section arranged therein.

The arrows 30 illustrate the flow direction of a fluid through the modular filter 1. The unfiltered material flows through the opening 6, arranged in the upper container side 17 and functioning as an inlet, into the first chamber 35, from there through the filter cells of the filter module 31 into the second chamber 36, wherein a first intermediate filtrate is formed. The first intermediate filtrate flows through the deflection channels 38 in the deflection plate 37 into the central channel of the filter module 32. In the second filtration stage, the fluid flows through the filter cells of the filter module 32 and forms a second intermediate filtrate in the third chamber 43. Via the deflection channels 38 the second intermediate filtrate reaches the interior chamber of the filter module 33 from where it flows through the third filtration stage and exits the modular filter 1 as a final filtrate via the adapter plate 42 and the opening 7 in the container bottom 4 which functions as an outlet. The flow direction of a fluid can also be provided counter to the direction indicated by the arrows 30 in Fig. 3.

The filter modules can be comprised of different filter materials and can be filled with filtering aids. Different combinations of the modules, including combinations of encapsulated with unencapsulated modules, are possible with a corresponding configuration of the partition plates, intermediate plates, deflection plates, head plates, and adapter plates.

One filtration stage used for prefiltration and one filtration stage for sterile filtration can be arranged in the modular filter housing. When utilizing filled modules, a module filled with activated charcoal, in particular, in combination with a filtration stage which has a filter module for layer filtration, can be expedient. Also, other adsorptive materials can be advantageous for filling a module. A filling with diatomite can be expedient for different filtration purposes, in particular, the combination of a module filled with coarse diatomite for prefiltration and a module filled with fine diatomite for fine filtration.