Beer filter

A filter device and a method for the filtration of beer, where, for an improved and simplified filtration, the filter includes a nonfiltrate chamber having a nonfiltrate inlet and a nonfiltrate outlet, wherein the nonfiltrate flows into the nonfiltrate chamber substantially tangentially to the walls thereof, and the bottom of the nonfiltrate chamber is constructed at least partially as a filter. The filter also includes a filtrate chamber underneath the bottom, and a filtrate outlet.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority of International Patent Application No. PCT/EP2008/000793 filed on Jan. 31, 2008, which claims priority of European Patent Application No. 07004460.7 filed Mar. 5, 2007. The entire text of the priority application is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a filter device, in particular for the filtration of beer, and a corresponding method.

BACKGROUND

During the manufacture of beer, the yeast cells and other solids contained in the beer must be removed. Such substances must be separated off so that they do not separate off by themselves over the time and make the beer turbid. As the yeast has a particle size of about 5 to 10 μm, it is necessary to use so-called microfilters that work, for example, within a range of 10-1 to 10-2 μm. Up to now, the beer has mainly been filtered by means of precoat filters, e.g. by means of filter cartridges. With such precoat filters, up to now diatomite is mainly used as filter aid. Due to the toxicity of diatomite and the problems of disposing of the same, one is looking for alternatives to this technology. For example, crossflow filter modules offer one alternative, however, they only have a small filter capacity and moreover get clogged very quickly.

SUMMARY OF THE DISCLOSURE

Starting from this, the object underlying the present disclosure is to provide an improved filter device, in particular for the filtration of beer, as well as a corresponding method by which beer can be filtered in a simple and efficient as well as environmentally safe manner.

By the nonfiltrate to be filtered being introduced into the nonfiltrate chamber tangentially to the wall of the nonfiltrate chamber, a rotating flow can annually form along the wall and make the contents of the nonfiltrate chamber rotate over the bottom that is at least partially designed as a filter. Towards the center, the speed of this flow decreases, so that the nonfiltrate can there leave the nonfiltrate chamber again via the nonfiltrate outlet, resulting in a continuous flow through the nonfiltrate chamber.

The nonfiltrate supplied tangentially under pressure, preferably via a pump, is forced to form a helical circulating flow directed downwards, like in a hydrocyclone. By the throttle effect in the lower part of the nonfiltrate chamber, portions of the external swirl are constantly deflected to an internal turbulent flow directed upwards. The nonfiltrate flowing over the bottom passes through the filter or the filter sections, is thus filtered and can then leave the filter device.

Due to the centrifugal force in the nonfiltrate chamber, larger and heavier particles collect at the inner walls of the nonfiltrate chamber and sink downwards to the center of the bottom. Microfiltration is then accomplished via the filter or the filter sections embodied in the bottom of the nonfiltrate chamber. A compact filter design is thus formed that permits simple and efficient filtration. That means, only one filter device is required for coarse and fine filtration.

Advantageously, the nonfiltrate outlet is arranged essentially in the center of the upper side of the nonfiltrate chamber as here the nonfiltrate rises upwards due to the internal swirl.

Advantageously, the nonfiltrate outlet comprises an outlet pipe of which the cross-sectional area diminishes towards the top. By the diminution of the cross-section of the outlet pipe, the flow rate of the nonfiltrate is increased towards the top whereby the nonfiltrate can be efficiently removed.

Advantageously, the filter disk is a microfilter disk that filters out particles within a range of >10-1 to 10-2 μm, in particular within a range of >0.2 to 1.8 μm. Thus, the filter according to the disclosure can reliably filter out yeasts and solids.

Preferably, the microfilter is designed as microfilter disk and preferably formed of a disk or plate perforated by means of a laser. Such a plate has sufficient stability, can be easily fabricated and permits pore sizes within a μm range with at the same time large free screen surfaces.

Such a filter can be either embodied to be self-supporting or rest on a support, where the support can be embodied as backing fabric, in particular as metallic fabric or a wide-meshed grid extending three-dimensionally, where the grid openings of the support are essentially larger than the pore size of the filter to ensure optimal flow and stability.

The diameter of the nonfiltrate chamber can diminish towards the bottom, or else the bottom of the nonfiltrate chamber can be arched. The diameter of the filtrate chamber, too, can diminish towards the bottom, or the bottom can be arched.

Together, the nonfiltrate and filtrate chambers can form an essentially wok-like shape. If the diameter of the filtrate chamber slightly diminishes towards the bottom, there will be a throttle effect of the circulating flow that facilitates the upward flow in the center of the nonfiltrate chamber.

Advantageously, the nonfiltrate outlet is connected to a return conduit conducting the nonfiltrate in the circuit back to the filtrate chamber and/or to a buffer/feeder tank.

Thus, the nonfiltrate discharged from the nonfiltrate chamber can be again supplied to the filtration, where a continuous flow over the bottom, i.e. over the filter, is possible.

According to a preferred embodiment, the filtrate outlet comprises a circular conduit connected to the filtrate chamber via several openings. This permits a steady removal of the filtrate.

Furthermore, the filter device comprises means that vibrate the bottom preferably in a pulsed manner. The bottom or the filter, respectively, can be vibrated either during the complete filter procedure or else at intervals. The excitation prevents a clogging of the pores of the filter or of the surface of the filter.

Advantageously, the filter device comprises a movably rotating brush on the bottom of the nonfiltrate chamber for cleaning purposes. This can prevent the surface of the filter from clogging completely. The brush can also loosen deposits which can then be removed through the nonfiltrate outlet by a backwash procedure. The brush can be moved by a magnet passing outside, as in an aquarium, or by a drive shaft. The brush can also be driven by a magnet as in a magnetic levitation train.

According to a preferred embodiment, at least one opening is embodied in the bottom of the nonfiltrate chamber in which a corresponding filter disk is arranged. Such a filter bottom can be very easily prepared, and several small filter disks can be also integrated in the bottom. In particular if the bottom does not have a flat design, it is advantageous to arrange several filter disks with smaller dimensions in the bottom. A bottom embodied in this way also has a greater stability. Then, filter materials that cannot be fabricated with a large surface can be used.

According to a further preferred embodiment, the filtrate chamber is arranged underneath the nonfiltrate chamber and also extends laterally around the filtrate chamber. Such an arrangement is particularly space-saving and compact as here the nonfiltrate chamber can be arranged more or less in the filtrate chamber.

Advantageously, the walls of the nonfiltrate chamber are at least partially embodied as a bellow. This has the advantage that vibrations generated by the means that vibrate the bottom of the nonfiltrate chamber can be absorbed.

The means that vibrate the bottom of the nonfiltrate chamber can preferably comprise a vibrating shaft extending in a sleeve through the filtrate chamber and knocking on the bottom. The sleeve can be arranged at one end at the wall or the bottom of the nonfiltrate chamber, and at the other end at the wall or the bottom of the filtrate chamber and be at least in sections embodied as a bellow. This solution allows the vibrating shaft to vibrate the bottom of the nonfiltrate chamber without contacting the liquid in the nonfiltrate chamber. In the process, vibrations are efficiently absorbed by the bellow in the sleeve.

It is advantageous for the outlet pipe as well as the nonfiltrate inlet to be arranged to be height adjustable. Thus, the height of the outlet pipe as well as the height of the nonfiltrate inlet can be adjusted to a corresponding filtering process.

Advantageously, a pressure control valve is arranged in the filtrate outlet so that the pressure in the filtrate chamber can be adjusted.

Preferably, the pressure in the filtrate chamber and in the nonfiltrate chamber are kept above the saturated vapor pressure of CO2, so that no CO2 outgases. Here, the pressure must be adjusted such that the pressure in the nonfiltrate chamber is higher than the pressure in the filtrate chamber, so that the nonfiltrate can pass through the filter. For a sufficient rotating flow to form, the nonfiltrate is preferably introduced tangentially at a speed of 1 to 10 m/s, where in a feed conduit speeds of up to about 6 m/s prevail, and directly at the inlet into the nonfiltrate chamber, speeds of up to about 10 m/s occur.

It is advantageous to provide a filter system with several filter devices that are arranged in series or in parallel to each other to increase the filter capacity.

DETAILED DESCRIPTION

FIG. 1shows, in a schematic representation, a cross-section through a filter device1according to the present disclosure that is intended to make clear the principle of the disclosure. The filter1comprises a nonfiltrate chamber2into which nonfiltrate is pumped via a nonfiltrate inlet7, e.g. from a buffer/feeder tank17, by means of a pump20(cf. e.g.FIG. 5). The inlet7is designed such that the liquid flows in essentially tangentially to the lateral wall2aof the nonfiltrate chamber2. Here, for example an inlet pipe can extend essentially tangentially to the wall2a, or else an inlet element (not shown) can be for example provided at the inner surface of the wall2aand deflect the nonfiltrate flow such that it flows essentially tangentially to the wall2a, such that this results in a rotating circulating flow, comparable to a hydrocyclone. The tangential inlet is not discussed in greater detail here, as such inlets are known in particular in connection with whirlpools and hydrocyclones. For the construction of the nonfiltrate inlet, it is only essential that the flow flows against the inner wall of the nonfiltrate chamber such that a flow is formed annularly along the wall that makes the contents of the nonfiltrate chamber rotate. It is also possible to design the inlet such that the entering filtrate is fanned out in the vertical direction upwards. Here, the inlet then comprises e.g. an inlet element with several openings arranged one upon the other or a slot.

The nonfiltrate chamber comprises a round cross-sectional area, the diameter of the nonfiltrate chamber here being larger than its height. The bottom of the nonfiltrate chamber2is at least partially embodied as filter4and here comprises the filter disk4. In the filter device1, the bottom14separates the nonfiltrate chamber2from the filtrate chamber3arranged underneath the bottom14, here the filter disk4.

The nonfiltrate chamber2furthermore comprises a nonfiltrate outlet5starting at the upper side2bof the nonfiltrate chamber2. The nonfiltrate outlet5is arranged in the center of the upper side2b. The nonfiltrate outlet5is embodied as outlet pipe the cross-sectional area of which diminishes from the upper side2bof the nonfiltrate chamber towards the top. The nonfiltrate outlet5ends in a conduit22in which a control valve8is arranged, so that the flow of the nonfiltrate as well as the pressure in the nonfiltrate chamber can be adjusted or controlled. In this embodiment, the diameter of the nonfiltrate chamber diminishes downwards, i.e. in the direction of the filter disk4. The diameter of the filtrate chamber3, too, diminishes towards the bottom. The nonfiltrate chamber2and the filtrate chamber3can thus together have the shape, for example, of a wok.

The filtrate chamber3comprises at least one filtrate outlet6that is connected to the filtrate chamber3via at least one opening16to discharge the filtrate via a filtrate discharge23. In the filtrate discharge23, too, a control valve9is provided to adjust the flow of the filtrate whereby the pressure in the filtrate chamber can be adjusted or controlled, respectively.

In this embodiment, the height of the nonfiltrate chamber diminishes from the outer wall2atowards the nonfiltrate outlet5.

The filter disk4is preferably a microfilter disk that filters out particles of a size of >10-1 to 10-2 μm, advantageously particles of a size of >0.2 to 1.8 μm.

It is possible for the microfilter disk to comprise a photolithographically generated grid10as can be seen in particular inFIGS. 2a, b, c.

FIG. 2ashows a plan view onto the circular filter disk4,FIG. 2bshowing an enlargement of section A. As can be clearly seen inFIG. 2b, the grid10comprises pores11through which the nonfiltrate passes and is filtered in the process.FIG. 2cshows an enlarged section of a section along line I-I inFIG. 2a. Here, it becomes clear that the grid10is applied onto a support, i.e. a support disk12having a greater thickness than the photolithographically generated grid10. The support12or the support disk12is for example embodied as backing fabric, in particular as metallic fabric. It can also be embodied as three-dimensionally extending wide-meshed grid of which the grid size is larger than that of the grid10, so that the filtrate can easily pass through it. The support12imparts sufficient stability to the photolithographically generated grid10.

According to a particularly preferred embodiment, the microfilter disk is formed of a disk or plate perforated by means of a laser, as can be taken in particular fromFIGS. 11aand11b. The filter disk4comprises pores11having a hole width within a range of for example 0.2-1.8 μm. Such a hole width is suited, for example, for the filtration of beer. For filtering tensides and spores, the hole width should be within a range of ≦0.01 μm. The pores11are generated by means of a laser. For this, for example a 0.3-1 mm thick CrNi steel sheet or a correspondingly thick teflon plate is suited as filter disk material. These materials are CIP/SIP capable which is in particular required in beer brewing or else in the pharmaceutical industry. As can be taken in particular fromFIG. 11bwhich shows an enlarged partial section along line A-A inFIG. 11a, the pores11have a smaller cross-section on the upper side than on the lower side which is due to the manufacture. Here, the lower side corresponds to the side from which the pores are generated by means of a laser as indicated by arrow L. The hole width stated above refers to the smaller hole width at the upper side. The filter disk4is arranged in the filter device such that the side of the pores11having the smaller diameter faces the nonfiltrate chamber, and the side having the larger pore diameter faces the nonfiltrate chamber. Such an arrangement permits a slower clogging of the pores.

The filter disk4perforated by means of a laser as illustrated in connection withFIGS. 11aand11bcan be either embodied to be self-supporting, or it can also be arranged on a corresponding support12as the above-described photolithographically generated filter disk4does.

The filter disk4can extend across the whole bottom14of the nonfiltrate chamber, as is represented inFIG. 2a. However, it is also possible to only partially embody the filter bottom14as filter. As can be taken, for example, fromFIG. 15, it is possible to only embody an external ring of the bottom14as filter4or as filter disk4, respectively. The central area which is essentially situated under the nonfiltrate outlet is not embodied as filter and comprises a section essentially impermeable to the nonfiltrate. As can be seen inFIGS. 13 and 14, in the bottom14of the nonfiltrate chamber2, several openings can be provided into which corresponding filter disks4a, b, c, . . .4nare inserted. The filter disks can then be round, as can be taken fromFIG. 14, however, they can also have any other shape, e.g. an oval or polygonal shape, as can be taken, for example, fromFIG. 13. Then, the junctions between the bottom14and the filter disks4a-4nare sealed.

To prevent a clogging of the filter disk4, the filter1according to the disclosure preferably comprises means25to vibrate the filter disk4. Preferably, the means25vibrate the filter disk4in a pulsed manner. Such means can comprise, for example, a vibrating head arranged at the outer wall of the filter, preferably at the same level as the filter disk4, which transmits the vibrations to the filter disk4. The filter1according to the disclosure can also comprise a mechanical vibrator that pushes directly or indirectly against the bottom or the filter4in a pulsed manner. Thus, fouling in the pores/channels and at the surface of the micro-screens can be prevented efficiently. Here, the filter can be vibrated during the complete filtration or else at intervals.

FIG. 3shows another embodiment of the present disclosure where the outlet6comprises a circular conduit15connected to the filtrate chamber3via several openings16. Here, the circular conduit16is arranged at the bottom of the filtrate chamber3. However, it can also laterally adjoin the nonfiltrate chamber3or be arranged to adjoin the nonfiltrate chamber laterally and at the bottom. The circular conduit15, however, then preferably comprises several openings via which the filtrate is conducted into the filtrate discharge23.

Below, the functional principle of the filter according to the disclosure will be illustrated more in detail. As is represented inFIG. 1by arrow U1, nonfiltrate is supplied from a buffer/feeder tank17via a conduit19(cf. e.g.FIG. 5) essentially tangentially via the nonfiltrate inlet7, so that the nonfiltrate tangentially flows to the side wall2aof the nonfiltrate chamber2. The nonfiltrate is pumped in with a pump20(cf.FIG. 5) at a high speed of about 1-10 m/s. As represented by the arrows, at the inner wall of the nonfiltrate chamber2, the nonfiltrate is forced to an external annular circulating flow directed downwards (in the area14a) that makes the contents of the nonfiltrate chamber rotate over the bottom14, here the filter disk4. In the process, the flow rate including its load decreases towards the center of the nonfiltrate chamber. By a throttle effect in the lower part, portions of the external flow, i.e. the external swirl, are constantly deflected to a turbulent flow U2directed upwards inside. The area14bwhere an upwards flow is formed is shown as white surface inFIG. 1. Thus, the nonfiltrate can leave the nonfiltrate chamber2in the central area of the nonfiltrate chamber2via the nonfiltrate outlet5. The diminution of the cross-section of the nonfiltrate outlet5facilitates the discharge. The course of the flow can be seen even better inFIG. 12.

By the centrifugal force, larger and heavier particles of the nonfiltrate collect at the inner wall2aof the nonfiltrate chamber. The discharged nonfiltrate flow U2, however, is also still loaded with particles and can be again supplied to the nonfiltrate chamber2or a buffer/feeder tank in the cycle via a return conduit22. The speed of the nonfiltrate outlet2and the pressure in the nonfiltrate chamber can be adjusted by means of a control valve8. The nonfiltrate rotating in the nonfiltrate chamber4over the bottom14passes transversely to the bottom through the filter disk4(or the filter disks4a, b, c . . . n) downwards as is represented by the arrows F. The nonfiltrate is thus filtered through the filter disk.

Thus, during filtration, two effects are advantageously combined, namely the centrifugal separation as well as the microfiltration through the filter4. The filtrate in the filtrate chamber3can be supplied to a filtrate discharge23via a corresponding filtrate outlet6. The discharge speed of the filtrate as well as the pressure in the filtrate chamber3can also be adjusted by means of the control valve9.

The pressure in the nonfiltrate chamber2and in the filtrate chamber3is adjusted such that it is above the saturated vapor pressure of CO2, so that no CO2 outgases during the filtration of beer. The pressure in the nonfiltrate chamber and in the filtrate chamber is adjusted by means of the nonfiltrate inlet7and the control valves8and9such that the pressure in the nonfiltrate chamber2is higher than the pressure in the filtrate chamber3.

FIG. 7shows a preferred embodiment of the present disclosure in a perspective representation. The embodiment shown inFIG. 7essentially corresponds to the embodiment shown inFIGS. 1 to 3. The bottom14of the nonfiltrate chamber as well as the filter disks can also be embodied as described in connection withFIGS. 2,3,11and13-15. The functional principle of the embodiment ofFIG. 7also corresponds to the functional principle illustrated in connection withFIG. 1.

FIG. 7shows the outer wall of the essentially hollow-cylindrically embodied filtrate chamber3which in this case has an arched bottom13. The bottom13, however, can also have a flat design. The nonfiltrate chamber3is here pressure-tightly sealed to the top by the cover plate46. The cover plate46comprises at least one inspection glass47a, b. The filter device1here comprises several legs48.

FIG. 8is a plan view onto the filter device represented inFIG. 7.FIG. 9is a section along line A-A inFIG. 8, andFIG. 10is a section along the line inFIG. 8. As can be taken in particular fromFIGS. 9 and 10, here the filtrate chamber3is arranged underneath and laterally around the filtrate chamber2. The walls2aof the nonfiltrate chamber2are also pressure-tightly sealed to the top by the cover plate14. The nonfiltrate chamber2is held in the filtrate chamber3by means of the mountings48that are connected to the wall2aof the nonfiltrate chamber2. The bottom14of the nonfiltrate chamber2is also arched, but it can also have a flat design.

As can be taken fromFIGS. 9 and 10, the nonfiltrate outlet5extends from the upper side of the filter device1into the nonfiltrate chamber2. The nonfiltrate outlet5is here embodied as outlet pipe which comprises a cross-section tapered towards the top at least in the lower area, as also described in connection withFIG. 1. Preferably, the pipe5forming the nonfiltrate outlet is arranged to be height adjustable, so that the distance of the lower edge5aof the outlet pipe to the bottom14is variable. The section of the outlet pipe5tapered towards the top can be arranged to be exchangeable, where sections having different opening angles can be attached. The inlet7is here tangential, also as described in connection withFIG. 1, that means that the nonfiltrate flows in in such a manner that the annular circulating flow is formed. Here, the inlet7comprises an inlet pipe introduced into the nonfiltrate chamber2from the top and comprising an inflow element7alying against the wall2aand conducting the nonfiltrate flow to the wall2a. The inlet7can also be arranged to be height adjustable. The height adjustability of the inlet7and of the nonfiltrate outlet5permits to adapt the inlet and outlet of the nonfiltrate to different processes.

The filter device moreover comprises a filtrate outlet6arranged in the bottom13of the filtrate chamber3. Reference numeral49designates a vent of the filtrate chamber. The vent can be opened or closed by means of a non-depicted valve.

This filter device1, too, comprises means25to vibrate the bottom14of the nonfiltrate chamber. The means25comprise the vibrating shaft42adjoining the bottom14and making it vibrate. The vibrating shaft42extends through the sleeve or the tube43. The sleeve43is arranged at one end at the bottom of the nonfiltrate chamber2and at the other end at the bottom of the filtrate chamber3. Thus, the vibrating shaft25can reach the bottom14without passing through the filtrate. The sleeve43is at least partially embodied as a bellow44that absorbs the vibrations. Thus, the vibrations are not or only slightly transmitted to the housing of the filtrate chamber3. Similarly, the wall2aof the nonfiltrate chamber2is also at least partially embodied as a bellow40, so that the vibrations of the bottom14are not transmitted to the cover plate46and to the walls of the filtrate chamber3.

In this embodiment, at least the area opposite to the sleeve43is not embodied as filter but is designed to be impermeable to the nonfiltrate, so that no filtrate can flow into the sleeve43. The functional principle of the filter shown inFIG. 7corresponds to the functional principle shown in connection withFIG. 1.

To increase the capacity of the filter, several filter units1a, b, c, can be combined to form one unit21, as represented inFIG. 4. In this case, the individual filters1a, b, care simultaneously supplied with nonfiltrate from the buffer feeder tank17via a conduit19and corresponding pumps20a, b, c. The nonfiltrate that is discharged via the nonfiltrate outlet5is here conducted back to the tank17in a mutual nonfiltrate return conduit22, but it could also be immediately pumped again into the corresponding filters1a, b, cvia the pumps20a, b, c. The filtrate outlets6a, b, c, too, end in a mutual filter discharge23. The buffer/feeder tank17is fed with nonfiltrate via a conduit18.

FIG. 5shows another arrangement essentially corresponding to the arrangement shown inFIG. 4, in which, however, the individual filters1a, b, care arranged one next to the other. InFIG. 5, a water backwash conduit or a CIP/SIP conduit (cleaning in place/sterilizing in place)24a, b, cis shown via which e.g. water can be pumped into the corresponding filter1a, b, cfor cleaning purposes, so that deposits on the filter disk4can be discharged via the nonfiltrate outlet5.

FIG. 6furthermore shows means to clean the filter surface4. Here, for example a brush26is movably arranged on the filter disk surface8. The brush26passes over the surface of the filter4. In this embodiment, the brush26comprises a metallic material in particular at the side facing the nonfiltrate chamber wall2a. A magnet27that is arranged at the outer surface of the wall2ain the area of the filter disk is moved to rotate, as represented by the arrow. The magnet27thus moves the brush26from outside, like in an aquarium or a magnet levitation device.

The brush loosens the impurities on the filter disk4. The brush26can be, for example, also rotatably mounted in the center of the filter disk4.

In the embodiment shown inFIGS. 7 to 10, the brush26can be driven to rotate by a drive shaft50, as can be seen in particular inFIG. 10. The drive shaft50is in this case connected to a non-depicted motor. The drive shaft50here extends through the outlet pipe5. However, the brush could also be driven via a drive shaft that extends through the sleeve43through the bottom14and drives the brush26from the bottom.

The nonfiltrate flow that is removed via the nonfiltrate discharge5can be supported by a non-depicted pump. The filtrate outlet, too, can be supported by a non-depicted pump. On the side of the filtrate, a circulation of the filtrate along the bottom side of the bottom14can be generated by means of a suited flow generation. This provides a transmembrane drop of pressure from the bottom that is constant and well-balanced across the screen surface.

According to the present disclosure, two effects are combined, that is the effect of a hydrocyclone where due to the centrifugal force very large and heavy components are pressed against the wall of the nonfiltrate chamber, as well as the effect of a microfiltration through the filter disk(s)4. Thus, according to the present disclosure, one does not need a combination of a coarse filter and a fine filter, but only one filter unit.

The present filter or the filter method according to the disclosure has been described in connection with the filtration of beer. This type of filter, however, is equally suited, for example, for the filtration in the pharmaceutical field, where e.g. tensides and spores are to be filtered out.