WO2022268307A1

WO2022268307A1 - Method and device for filtering beer

Info

Publication number: WO2022268307A1
Application number: PCT/EP2021/067097
Authority: WO
Inventors: Andreas HIPPEL; Jörg Zacharias; Knut STELLE
Original assignee: Krones Ag
Priority date: 2021-06-23
Filing date: 2021-06-23
Publication date: 2022-12-29

Abstract

The invention relates to a device and a method for filtering beer using at least one pack of modules with a plurality of modules each for crossflow filtration, wherein, during a filtering cycle, in a pack (3) of modules at least temporarily the transmembrane pressure in at least one module (1) is controlled and at the same time the filtrate flow is controlled in at least one module (1).

Description

Method and device for filtering beer

The invention relates to a method and a device for filtering beer according to the preamble of claims 1 and 13.

Filtration is one of the key processes in brewery operations. In addition to technological requirements, economic requirements such as long filter service lives, low operating costs and easy-to-use systems also play a major role.

With cross-flow beer membrane filtration, the transmembrane pressure in the individual modules increases over time because the filter membranes become clogged over time. The modules filter up to a maximum transmembrane pressure TMD, which is set in such a way that the modules are not damaged. When the maximum transmembrane pressure is reached, a filtration cycle is ended and the membranes are cleaned before a new cycle can be run. There can also be one or more intermediate cleanings within a cycle to delay clogging of the membranes, during which, for example, the direction of flow through the module is reversed. In beer membrane filtration, the filtrate flow is usually regulated.

FIG. 6 shows a diagram in which the transmembrane pressure is shown as a function of time. FIG. 6 is an internal development from which the present invention proceeds. Here, for example, there is a module package 3 with three modules 1ai, 1a ₂ and 1a ₃ . As can be seen from the diagram, the increase in the transmembrane pressure as a function of time is not the same for the series-connected modules 1ai, 1a ₂ and 1a ₃ . While the transmembrane pressure increase for the modules 1ai, 1a ₂ is essentially the same, with the transmembrane pressure of the first module being slightly greater than that of the second module, the transmembrane pressure of the third module increases more slowly. This means that the modules are subject to different loads. As can be seen from the diagram, an intermediate cleaning is carried out after a predetermined time, here at a time of two hours. Then the filtration is started again. The filtration cycle lasts until one of the modules has reached the maximum transmembrane pressure. The transmembrane pressures at the end of the filtration cycle or interval of the different modules differ significantly. Here, the first module first reaches the maximum transmembrane pressure. Despite the end of filtration initiated by the first module, the third and second module could be used for longer in order to increase the amount of filtration per cycle. Proceeding from this, the object of the present invention is to provide a method and a device that increase the filtration quantity per filtration cycle in a simple manner.

According to the invention, this object is achieved by the features of claims 1 and 13.

The method according to the invention is used for filtering beer using at least one module package, each with a plurality of modules for cross-flow filtration. Such a module can be a membrane module through which unfiltrate flows in a cross-flow circuit and filtrate can be discharged. A module package includes several modules. It is also possible for several such module packages to be arranged in a filter unit.

As the membrane surfaces become clogged over time and the transmembrane pressure increases, the beer is filtered in filtration cycles. Preferably, a filtration cycle begins at the beginning of filtration and ends after all modules have reached a maximum transmembrane pressure limit. After the filtration cycle, cleaning takes place, e.g. with a cleaning agent, and a new filtration cycle begins until the next cleaning. According to the present invention, during a filtration cycle in a module package, the transmembrane pressure is at least temporarily regulated in at least one module and the filtrate flow is simultaneously regulated in at least one module.

The filtration process can thus be individually adjusted, which means that the filtration volume per filtration cycle can be increased. In particular, by adapting the control, it can be achieved that at the end of the filtration cycle all modules have reached the maximum possible transmembrane pressure limit and are maximally exhausted. The individual control means a longer service life, ie a longer filtration cycle or a higher filtrate flow can be achieved, which increases the total amount of filtrate per filtration cycle and saves overall consumption costs, especially cleaning costs and time. With different states of the membranes, be it due to cleaning states or contamination states, aging processes or differences in flow, not all modules could be used to the full. This can be improved by the combined filtrate flow transmembrane pressure control, so that all membranes in a module package can be pushed to the full performance limit. In addition, compared to a pure transmembrane pressure control, the membrane cannot be extremely overrun, which could result in excessive filtration flows. The type of control can thus be adapted to the corresponding module. According to the present invention, the modules of a module package can be arranged in series in a non-filtrate line and non-filtrate can be circulated through the modules. For example, if the transmembrane pressure in the individual modules increases at different rates due to the position of the modules, the control can be adjusted in such a way that the service life and/or the filtrate flow increases.

Advantageously, in a module package, the filtrate flow is first regulated in all modules and then switched from filtrate flow regulation to transmembrane pressure regulation in at least one module. In particular, depending on the membrane pressure of a corresponding module, either the filtrate flow can continue to be regulated or a switch can be made to transmembrane pressure regulation.

This means that when a certain transmembrane pressure limit for a module is reached, in particular a maximum transmembrane pressure limit, the module is not switched off or bypassed as in the prior art, but it continues to be operated, but then via a transmembrane pressure control. This ensures that the transmembrane pressure limit is not exceeded and the module is not damaged. Advantageously, the module then remains in operation until the end of the filtration of the entire package and can thus be used effectively. The maximum transmembrane pressure limit for the modules is set in such a way that the modules are not damaged. The transmembrane pressure limit is specified according to the manufacturer's specifications, up to which a module may be loaded, i.e. <= the maximum transmembrane pressure. In this way, the amount of filtrate in a filtration cycle can be significantly increased, since all modules are operated until the maximum transmembrane pressure is reached.

According to a preferred exemplary embodiment, the modules are switched from filtrate flow control to transmembrane pressure control one after the other as soon as the respective module has reached the transmembrane pressure limit value. When the last module in a module pack has reached the transmembrane pressure limit, either cleaning can be used, carried out or started, or filtration continues for a certain period of time if capacity is still required. It can then continue to be filtered until at least one module has reached a predetermined limit, e.g decreases over time). According to a further embodiment of the present invention, if the difference between the transmembrane pressure of a module and the transmembrane pressure of a further module, which at the same time has a higher, in particular the highest, transmembrane pressure in the package, is greater than or equal to a predetermined differential value Dr, at one of the two modules can be switched from filtrate flow control to transmembrane pressure control, with the setpoint of the transmembrane control corresponding in particular to the transmembrane pressure of the module at which the filtrate flow is further controlled. This means that the transmembrane pressures can be adapted to each other from a certain deviation.

In general, at least one module is switched to transmembrane control if the differential value Dr or a correlating value is exceeded - whereby, for example, the pressure difference does not necessarily have to be determined to determine the conversion, but also the time or filtered quantity at which a certain difference value of the pressures is reached, can be determined empirically and after this time or filtered amount the control is switched. Alternatively, the trigger for this can also be that the gradients of the TMD gradient/time/filtered quantity have a different gradient, so that the more rapidly increasing module has a steeper/higher gradient, for example. This value can also be used individually or in addition to the decision-making process. This means that if there is a certain deviation in the gradient of individual modules, the control can be switched to transmembrane pressure control.

Since the setpoint of the transmembrane control corresponds to the transmembrane pressure of the module at which the filtrate flow is regulated, i.e. the module that has the highest transmembrane pressure, for example, the filtrate flow-controlled module assumes a so-called master function for at least one other module, i.e. it gives the setpoint before, which increases as a function of time or filtered quantity. The target value of the transmembrane pressure control thus follows the current transmembrane pressure of the filtrate flow-controlled module.

For example, in at least one module of a package, the transmembrane pressure can be regulated to a target value that is greater than its transmembrane pressure when switching to transmembrane pressure regulation and, in particular, corresponds to the transmembrane pressure of the filtrate flow-controlled module with the highest transmembrane pressure. The aim is therefore that all modules are exhausted at the end of the filtration at a maximum transmembrane pressure. In this embodiment, the filtration flow will increase so that temporarily a higher output, i.e. a higher filtration quantity per time occurs. A flow limitation upwards is optionally possible.

According to a further exemplary embodiment, the transmembrane pressure can be adjusted differently, with at least one module of a package having the transmembrane pressure regulated to a setpoint which becomes smaller than a transmembrane pressure when switching to transmembrane pressure regulation and in particular the transmembrane pressure of the filtrate flow-regulated module with the lowest corresponds to transmembrane pressure. This means that the filtrate flow-controlled module with the lowest transmembrane pressure has a master function for one or more modules, i.e. it specifies the setpoint. Here, too, a flow limiter, e.g. below, is optionally possible in order to find a sensible end.

According to one embodiment, the filtrate flow control of modules undergoing filtration can be adjusted by controlling with flow increase rates in specified flow ranges and per filtered quantity or time and adding a transmembrane pressure as a target value/conductance.

When switching to the controlled and limited filtrate flow control, which is based on transmembrane pressure, the addition of a transmembrane pressure as a target value is used to control the flow with corresponding flow increase rates (+/-hl/h) to a target value.

If the transmembrane pressure increases too much depending on the filtered quantity (outside the permitted TMD increase range), the increase in filtrate flow decreases or remains constant or decreases to the original value with a continuously strong increase in transmembrane pressure and vice versa.

Irrespective of this, from a certain filtered quantity or time, the TMD of that module can be taken as the master, which has the highest or lowest value, or the mean value of all modules that are in the TMD or filtrate flow range.

According to a further exemplary embodiment, the target value of the module switched to transmembrane pressure regulation is an average value of the transmembrane pressures of the filtrate flow regulated modules. The modules can be adjusted so that they are also fully exhausted at the end of the filtration cycle. The overall output is therefore very variable. The minimum and maximum filtrate flows can then behave relatively evenly, i.e have only a small range of fluctuation. In the case of membrane packs with a number of >=3, this is a potentially strong characteristic.

The mean is determined from the moduli that are within a given range of transmembrane pressure or filtrate flux to treat outliers separately.

According to a preferred embodiment, at least two module packs are arranged in parallel, with the two module packs having a common unfiltrate inlet and a common unfiltrate outlet, wherein if the module packs each have n modules at n locations in a row, the modules at the same nth location in the respective Pa ket are regulated in such a way that the regulation have the same controlled variable, in particular the same setpoint (where n is a whole natural number). This is due in particular to the fact that the respective modules of the packages, which are arranged at the same point, also have a common filtrate outlet in which a pressure or the flow can then be measured and a control valve for adjusting the filtrate flow or the transmembrane pressure is arranged can be. For example, several module packages can be controlled simultaneously in a simple manner. For example, the filtrate flow values and/or transmembrane pressure values for modules that are arranged at the same nth point in the n module packages can be averaged, for example, so that there is a switchover from filtrate control to transmembrane pressure control when the respective average value is a corresponding one size. As an alternative to this, the filtrate flow values and/or transmembrane pressure values for modules that are arranged at the same nth position of the n module packages can be determined in each case, in which case there is a switchover from filtrate flow control to transmembrane pressure control if, for example, at least one module (of the modules connected to are arranged at the same point or connected together) has a value that has a corresponding size.

A device, in particular for carrying out the method, has at least one module package, each with a plurality of modules for cross-flow filtration. Furthermore, the device has a control device that can switch at least one module from filtrate flow control to transmembrane pressure control during a filtration cycle.

By combining both control options in one filtration cycle, the filtration process can be ideally adapted to the respective module conditions, such as module position, module age, etc., which means that the filtration volume per filtration cycle can be significantly increased. In addition, due to the possibility of targeted switching between transmembrane pressure control and volume flow control, the requirements of the filtration process when starting up and shutting down the filter system can be taken into account. For example, the filtration can be divided into 4 main phases. As a rule, it is particularly favorable to structure these phases as follows:

1. When starting up the filtration, it is particularly important to protect the membranes from excessively high filtrate flows and too rapid contamination (i.e. from being “overrun”). For example, it is advantageous to start with very low transmembrane pressures (e.g. with 0.05 bar) at the beginning of the filtration and thus to start with a transmembrane pressure control in order to start the filtration in order to avoid excessive volume flows (max. 10hl/h or max. 50l /(m ² h)) through the membrane to avoid. These TMDs can then be increased gently until a preset nominal flow rate (eg 7.5hl/h) is reached. At the same time, it makes sense to also monitor the maximum filtrate volume flow and to secure it with a limit value.

2. At this point it switches to filtrate flow control. In this phase, the membrane filter then runs as described in the exemplary embodiments (FIGS. 3 to 6). The volume flow of the individual filtrate lines is regulated until corresponding deviations in the TMD are reached. Then the control of the individual packages is changed.

3. Then at least 1 module is switched from filtrate flow control to transmembrane pressure control according to Figures (3 to 6) and filtered until the end of the cycle. When determining the end point of filtration, it is quite appropriate to determine this point in time using two important points: a. On the one hand, it should be linked to a minimum amount of filtrate that makes sense in terms of costs. This has to be calculated with a filtration time quantity balance. b. On the other hand, it is important to consider the point at which a membrane is subjected to too much stress and can only be cleaned again with excessive cleaning effort. This is determined based on the necessary cleaning time and recovered filtrate volume flow and service life in the subsequent filtration.

4. When shutting down the system, it must be ensured that the maximum filtrate volume flow (e.g. again less than 10hl/h) and also the maximum transmembrane pressure (e.g. <1.2 bar) are not exceeded even when the system is extended and squeezing out with e.g. CO2 or deaerated water allowed to. These values can be stored in the controller as limit values. This is advantageous because the increasing dilution of the beer due to the escaping water reduces the overall viscosity (as a result of dilution effects) and the filtrate volume flows increase as a result while the pressure levels remain the same, which could damage the membrane.

According to a preferred embodiment, the modules of a module package are arranged in series in a non-filtrate line and non-filtrate can be circulated through the modules. Filtrate can be discharged in a respective filtrate line of the corresponding module, with the filtrate flow being measured in the filtrate line. The transmembrane pressure is determined, for example, on the basis of a pressure measurement in the common unfiltrate line before and after the module package and a pressure measurement in the respective filtrate lines. This means that to measure the transmembrane pressure, only two pressure sensors must be provided in the unfiltrate feed line common to all modules and one pressure sensor in the respective filtrate lines. It is also possible that, in order to determine the transmembrane pressure for each module, the pressure is determined immediately before and after the module in the unfiltrate line. The actuator for controlling the filtrate flow or the transmembrane pressure can be a control valve, which is then arranged in the respective filtrate line.

If, as described above, there are several parallel module packages that have a common unfiltrate inlet, with each module at the same position, i.e. at the same nth point, having a common filtrate outlet, one actuator, in particular a control valve for the modules that have a common filtrate outlet and also a pressure sensor and a flow meter. The present invention is explained in more detail below with reference to the following figures. FIG. 1 shows, roughly diagrammatically, a device according to the present invention.

FIG. 2 shows a further exemplary embodiment of a device according to the present invention.

FIG. 3 shows a diagram showing the transmembrane pressure as a function of time for an exemplary embodiment of the method according to the invention.

FIG. 4 shows a diagram showing the transmembrane pressure as a function of time for a further exemplary embodiment.

FIG. 5 shows a diagram showing the transmembrane pressure as a function of time for a further exemplary embodiment.

FIG. 6 shows a diagram showing the transmembrane pressure as a function of time.

FIG. 1 shows an embodiment of a device according to the present invention.

According to this exemplary embodiment, the device can have a plurality, that is to say n, module packages 3a, 3b, 3n, which are arranged side by side in parallel. Here each module package 3a, 3b, 3n has six modules for cross-flow filtration. Here, the first module package 3a has the module 1ai at its first place, followed by the modules 1a ₂ , 1a ₃ , 1a ₄ , 1a ₅ , 1a ₆ , 1a _n (module 1a _n is not shown). Parallel to this, the module package 3b is provided with the first module 1bi, followed by the modules 1b ₂ , 1b ₃ , 1b ₄ , 1bs, 1b ₆ , 1b _n (module 1b _n is not shown). The modules in a module pack 3a, 3b, 3n are arranged in series in the unfiltrate line 4, the module packs 3a, 3b, 3n having a common unfiltrate inlet 5 and being supplied with unfiltrate, for example via a pump 12. Even if not shown, a non-filtrate buffer tank can be arranged in front of the pump 12, for example. The non-filtrate from the last modules 1a ₆ , 1b ₆ (1a _n ; 1 b _n ) is combined again in a common non-filtrate line 4 and fed directly back to the modules 1 supplied -. The Unfilt rate is passed through the individual modules 1 in a cycle as shown by the arrow. The filtrate leaves the individual modules 1 in cross-flow and is discharged via a respective filtrate line 8, with the filtrate from modules which are arranged at the same n-th point being fed into a common filtrate line 8 ₁ , 8 ₂ , 8 ₃ , 8 ₄ , 8 ₅ , 8 _d , 8 _n open out.

Finally, in each of the filtrate lines ₈ there is a control valve 10i to _10n , here 10i to 106, via which the transmembrane pressure in a respective module or the filtrate flow through the module can be adjusted. In addition, in the respective filtrate Line 8 _n , here 8 ₁ to 8e, corresponding flow meters 11 _n , here 11 ₁ to 11 ₆ are arranged in order to measure the filtrate flow, that is, the corresponding actual value of the volume flow. Finally, in each of the filtrate lines 8 _n , here 8 ₁ to 8 _d , there is also a pressure sensor 9i to 9 _n , here 9i to 9b for measuring the pressure in the respective filtrate lines 8. Furthermore, in the unfiltrate line 4 there is a pressure sensor 90 after the module package (So in the return) and a pressure sensor 91 in front of the module package (here, for example, after the pump 12) is provided. By forming the difference between the mean value of the measured pressures in the unfiltrate line 4 and the filtrate line 8, for example, the respective transmembrane pressure (TMD) for a module can be determined at the corresponding nth point. This means that for the transmembrane pressure TMD _n at point n, the following approximately applies:

TMDn — ((Psensor91 Psensor9o)/riModule_in_Series)/2 — Psensor9n

This approximation has proved sufficient for the present invention. The pressure loss in the modules is not taken into account here, but it can be calculated. In principle, the pressure before and after each individual module in the unfiltrate line can also be determined and calculated from this mean value minus the pressure in the corresponding filtrate line. However, this entails an increased outlay in terms of apparatus.

According to a further exemplary embodiment, the outlay on equipment can be reduced even further by generally dispensing with the pressure sensors. All that is required for this is a sensor for determining the crossflow volume flow. The pressure losses can then be determined using known fluid mechanics equations. Absolute values of pressures can also be calculated at necessary measurement positions such as the inlet of the membrane modules, the outlet of the membrane modules and also at intermediate positions. They can be determined from the sum of the pressure losses up to these positions. Only the pressure pv _ordmck in front of the crossflow needs to be known using a sensor in order to be able to determine the outlet pressure level. For example, the pressure at the inlet of the membrane modules is the sum of the upstream pressure and the pressure loss up to the inlet of the membrane modules:

PPosition membrane module inlet ^— Padmission pressure Apvmembrane inlet

The pressure at the membrane module outlet and the total pressure loss of the crossflow circuit can also be determined in an analogous manner, and consequently also the pressure loss between the membrane module inlet and the membrane module outlet. The total sum of the pressure loss of the entire crossflow circuit can be calculated as the sum of all section pressure losses of the individual pipeline sections of the crossflow circuit and the sum of the pressure loss coefficients of all installations, bends and other resistances in the line.

It represents the necessary pressure increase of the crossflow pump:

Furthermore, this approach requires the calculation of the flow velocities at the corresponding positions of the pipe sections, which is determined using the simplified form of the continuity equation at the corresponding positions.

With the help of the Reynolds number, the form of flow is determined, which results in laminar or turbulent depending on the density and dynamic viscosity of the pumped fluid (e.g. beer) and the corresponding pipe friction coefficient and representative diameter of the pipe.

In the literature, there are usage formulas for this that lead to good correlation.

Furthermore, the device has a control device 7, which is shown only schematically, and into which measured values for the measured pressure values in the filtrate lines 8n and the _unfiltrate line 4 can be passed. Furthermore, the flow rates measured by the flow meter 11 _n per unit of time can also be fed to the controller 7 . The controller 7 can, for example, control both the control valves 10i to _10n and the pump 12, for example. During a filtration cycle, the control device 7 can control the actuators, i.e. the control valves _10n , in such a way that the filtrate flow serves as the controlled variable, with the filtrate flow being the volume flow, i.e. a specific volume per time, for example in 15 hl/h is used. The control device 7 can also regulate the transmembrane pressure via the respective actuator _10n as a control variable, with the respective actual value for the transmembrane pressure for the respective modules 1n being measured here via the sensors 90, 91 and _9n and as described above can be calculated. As will be explained in more detail below, the control device 7 can switch from filtrate flow regulation to transmembrane pressure regulation for the individual modules 1n, in particular as a function of the transmembrane pressure determined for the respective module 1n.

The exemplary embodiment shown in FIG. 1 was described using two module packages 3a, 3b. However, n module packages can be provided which are connected to a common unfiltrate line 4, in particular 1 to 5, in particular 1 to 3. The advantage of this connection is that for the respective modules, i.e. those on the same n ten Place are arranged, only one actuator 10, a pressure sensor 9 and a flow meter 11 must be provided, since the filtrate flows into a common filtrate line 8. In the exemplary embodiment shown in FIG. 1, a module package comprises 6 modules, although the invention is not intended to be limited thereto. Advantageously, for example, two to 10 modules 1 can be arranged in a module package 3 and arranged in series in the unfiltrate line 4 . FIG. 2 shows an exemplary embodiment which corresponds to the exemplary embodiment shown in FIG. 1, with the exception that here the number of modules n per module package is n=3.

Conventional membrane modules are suitable for the invention, in particular membrane modules in which many hollow-fiber membranes are bundled to form a membrane module.

Ceramics and plastics are particularly suitable as diaphragm material, advantageously polyethersulfone. The mean pore diameter is, for example, 0.2 μm-0.8 μm, in particular 0.45 μm. The filtering surface per module is, for example, in a range of 1 m ² - 50 m ² , in particular 13 m ² per module 1. The membrane bundle is housed in a pressure pipe made of stainless steel, which has at least one unfiltrate inlet and one unfiltrate outlet as well as one filtrate outlet, in such a way that the unfiltrate can be filtered in crossflow.

The method according to the invention is explained in more detail below with reference to the exemplary embodiment shown in FIG.

Figure 3 shows an embodiment according to the present invention. The diagram shows the transmembrane pressure as a function of time. As can be seen from Figure 3, the modules 1 start at time to (beginning of the filtration cycle) with the filtration, with Un filtrate first being divided via the unfiltrate inlet 5 and the pump 12 to the respective module packages 3a, b and the modules 1 of the respective package flows through in series and the unfiltrate is recirculated back to the unfiltrate inlet 5. The filtrate flow in the filtrate lines 81, 82, 83 is measured continuously via the flow meters 11 ₁ , 11 ₂ , 11 ₃ . The control device 7 records the measured values and regulates the respective actuator, here the control valve 10i, I O2 , I O3 , to a predetermined volume flow, for example in a range from 3 hl/h to 10 hl/h. At the same time, the transmembrane pressure for the individual modules 1 is determined by the control device 7 via the pressure sensors 9 1 , 9 ₂ , 9 ₃ and the pressure sensors 91 , 90 . As can be seen from Figure 3, since the modules are filtrate flow controlled, the transmembrane pressure in the individual modules increases continuously. in the present exemplary embodiment, the transmembrane pressure of the modules 1ai, 1a ₂ and 1bi, 1b ₂ increases faster than the transmembrane pressure of the modules 1a ₃ , 1b ₃ .

The flow setpoint is here, for example, in a range of 4 hl/h - 8 hl/h.

At a point in time ti (which can be preset in the controller), an intermediate cleaning is initiated. The intermediate cleaning is therefore initiated at this point in time ti, because the service life can be extended in this way. Here, for example, the flow direction of the unfiltrate in the modules is reversed directly without the unfiltrate, e.g. beer, having to be pushed out. In the exemplary embodiments shown here, two such intermediate cleanings are carried out, but it is also possible to carry out several intermediate cleanings or none at all.

The filtration then starts again, with the transmembrane pressure of the first two modules again increasing faster than the transmembrane pressure of the third module. At time t2, an intermediate cleaning is carried out again. After the intermediate cleaning at t2, another filtration follows, where the transmembrane pressure of the first two modules rises steeply while the transmembrane pressure of the third module rises less sharply. As can be seen in FIG. 3, the respective first module 1ai, 1bi is the first module to reach the maximum transmembrane limit (see arrow 1) at a point in time t ₃ , which is designed in such a way that the module is not damaged during filtration, for example is in a range of 1.0 bar - 1.5 bar. Normally this module would now stop the filtration of all modules or the module would be bypassed.

According to the present invention, however, the filtrate flow control for the respective module 1ai, 1bi is switched by the control unit 7 to transmembrane pressure control, with the setpoint for the control being in particular the maximum transmembrane pressure. The actuator here is the control valve 10i _.

The respective second module 1a ₂ , 1b ₂ reaches the maximum transmembrane pressure limit (see arrow 2) at a point in time U as the second module. Instead of terminating the filtration with this module, the system switches from filtrate flow control to transmembrane pressure control, with the target value corresponding in particular to the maximum transmembrane pressure. The actuator here is the control valve IO2.

The last, here the third module(s) 1a ₃ and 1b _3, only reach the maximum transmembrane pressure (see arrow 3) at a point in time ts, whereby there are then several possibilities how to proceed. Either, when the last module reaches the transmembrane limit, the filtration stops and the filtration cycle ends. However, it is also possible, please include, that if capacity is still required, all modules continue to be operated up to a point in time te, as shown by arrow 4, with the transmembrane pressure then being regulated in all modules and the Target value is preferably the maximum transmembrane pressure, since the yield is greatest here. The present invention now makes it possible that, although modules of a package have already reached the maximum transmembrane pressure, they can still be used until the end of the filtration cycle, and the remaining modules can also be operated until the maximum transmembrane pressure limit is reached, so that the Yield is increased overall.

After the end of the filtration cycle, the device is cleaned and is available for a new filtration cycle.

FIG. 4 shows a further exemplary embodiment according to the present invention, which is also explained using the device as shown in FIG. As in the previously described embodiment, the filtration begins at time t o , with all modules being controlled according to the filtrate flow. After a time x at time ti, the result is that the difference Dr between the transmembrane pressure of the third module 1a ₃ , 1b ₃ and the first module 1ai, 1bi is greater than a predetermined difference limit value. The control device 7 can determine this either by comparing the transmembrane pressures determined by measurement, but it can also be set for a specific time or filtered quantity that has been determined empirically and at which a corresponding Dr results. Or an increase in the gradient over time of the transmembrane pressure can determine the onset, or another value corresponding to the transmembrane pressure difference is determined, which is used to determine that the control must be switched over. Then the third module 1a ₃ , 1b ₃ is switched over by the control device 7 to transmembrane pressure regulation. The module 1a ₃ , 1b ₃ is regulated to a transmembrane pressure that is greater than the transmembrane pressure during the changeover and in particular to the transmembrane pressure of the filtrate flow-controlled module 1ai, 1bi with the highest transmembrane pressure. In the exemplary embodiment shown here, the third module would then be regulated to this transmembrane pressure, as can be seen from the dashed line in FIG. It is advantageous if the setpoint is switched to the transmembrane pressure of the module with the highest transmembrane pressure, since this module then assumes a master function and the control follows this master module means that the setpoint of the transmembrane pressure-controlled modules adapts with increasing transmembrane pressure of the master module. This results in the master module, which one/all other modules can use as orientation. Thus, all modules at the end of the filtration are exhausted at the same time at the maximum transmembrane pressure. This regulation will increase the total flow during filtration, so that there will be a higher output at times. An upward flow limitation of the membrane when switching to transmembrane pressure control is optionally possible in order to prevent damage to the membranes, eg to 8 hl/h - 15 hl/h. It is possible that the filtrate flow is gradually increased when switching to a transmembrane pressure control, which leads to a control delay but protects the membrane, since the flow is not suddenly increased.

As can be seen from Figure 4, an intermediate cleaning takes place at the time tz, after which the filtration is resumed and since Dr is greater than the differential limit value Dr (which does not have to be the case in other exemplary embodiments), the third module 1a ₃ , 1 b ₃ is further transmembrane pressure-controlled while the other two modules 1ai, 1 bi, 1a ₂ , 1 b ₂ continue to be regulated for the filtrate flow. Intermediate cleaning is then carried out again at time t ₄ . In the next interval, the transmembrane pressure difference between the second and first modules is now also greater than a predetermined differential value Dr, so that the second module or the second modules 1a ₂ , 1b ₂ then also follow the master module 1ai, 1bi and, as previously described, transmembrane pressure be managed. This takes place, for example, until the master module 1ai has reached the maximum transmembrane pressure limit. Then the other modules also reach the maximum transmembrane pressure limit due to the regulation and are also exhausted to the maximum, so that the filtration cycle can be ended.

FIG. 5 shows a further exemplary embodiment according to the present invention, which is also explained in more detail with reference to the device as shown in FIG. As in the exemplary embodiment in FIG. 4, all modules are initially regulated according to the filtrate flow until, after a time x, the transmembrane pressure difference Dr between the module with the lowest transmembrane pressure and the respective transmembrane pressures of the other modules is greater than a differential value Dr. In this exemplary embodiment in FIG. 5, the difference Dr between the first and second modules and the transmembrane pressure of the third modules is greater than the transmembrane pressure limit value Dr. The modules 1ai, 1bi and 1a ₂ , 1 b ₂ are now switched to a transmembrane pressure control, with the target value of the control preferably corresponding to the transmembrane pressure of the module with the lowest transmemb randruck, here the third modules 1a ₃ , 1b ₃ . The third modules 1a ₃ , 1b ₃ further regulate ter the filtrate flow. The target value of the transmembrane pressure control for the first and second modules then changes according to the current values of the transmembrane pressure of the master module, that is to say here the third modules 1a ₃ , 1b ₃ . At time ti, an intermediate cleaning is carried out, after which the filtration after the intermediate cleaning starts, for example, at a lower transmembrane pressure than before the intermediate cleaning. The transmeme fire pressures then rise again during filtration. Since here too Dr between the third modules and the other modules is greater than a certain differential limit value Dr, regulation continues accordingly, which means that the third modules 1a ₃ , 1b ₃ continue to be regulated with regard to the filtrate flow, while the first two modules 1ai , 1bi, 1a ₂ , 1b ₂ can be further controlled by transmembrane pressure and follow the transmembrane pressure of the third module with their set point. The modules are also maximally exhausted at the end of filtration at the maximum transmembrane pressure reached. In this exemplary embodiment according to FIG. 5, the total flow of the membrane filtration will drop, so that a lower output is temporarily produced. Conversely, the filtration is significantly extended, i.e. the filtration cycle lasts longer, so that a larger total amount of filtrate can be obtained in the filtration cycle. In this exemplary embodiment, a high filtrate flow can initially be started, which can then be lowered successively (advantageously not suddenly) by the regulation when switching to transmembrane pressure regulation. It is not possible to overrun the membranes of the modules by controlling the transmembrane pressure too high.

According to a further exemplary embodiment, it is possible that when the difference between the transmembrane pressure of two modules exceeds a specific differential value Dr, switch to transmembrane pressure regulation and use a mean transmembrane pressure of the filtrate-regulated modules as the desired value. Any number of modules or module pairs can be adjusted and the filtration cycle can be exhausted to the maximum. There are then not such large flux fluctuations when the control is switched over.

It is essential in the previous exemplary embodiments, which were described in FIGS. 4 and 5 and previously, that if the transmembrane pressure of the individual modules is too far apart, i.e. the transmembrane pressure difference is greater than a certain value Dr, at least one module or the modules which are connected to the same filtrate outlet, are transmembrane pressure controlled and the setpoint for the transmembrane pressure control is adjusted in such a way that the difference to the other transmembrane pressures of the other modules is reduced. This already brings an advantage.

Claims

Expectations

1. A method for filtering beer using at least one module package (3) each having a plurality of modules (1) for crossflow filtration, characterized in that during a filtration cycle in a module package (3) at least temporarily in at least one module (1) the Transmembrane pressure is regulated and at the same time the filtrate flow is regulated in at least one module (1).

2. The method according to claim 1, characterized in that the modules (1) of a module package (3) are arranged in series in an unfiltrate line (4) and unfiltrate is circulated through the modules (1).

3. The method according to claim 1 or 2, characterized in that in a module package (3) the filtrate flow is first controlled in all modules (1) and then switched from filtrate flow control to transmembrane pressure control in at least one module (1).

4 Method according to at least one of Claims 1 to 3, characterized in that the filtrate flow is first regulated in all modules (1) of a module package (3), with either the filtrate flow or the transmembrane pressure being regulated as a function of the transmembrane pressure of the respective module will.

5. The method as claimed in claim 4, characterized in that when a module (1) has reached a transmembrane pressure limit value, this module (1) is switched over from filtrate flow regulation to transmembrane pressure regulation.

6. The method according to claim 5, characterized in that the modules (1) are switched over from filtrate flow control to transmembrane pressure control as soon as the respective module (1) has reached the transmembrane pressure limit.

7. The method according to claim 6, characterized in that in the case of transmembrane pressure control, the target value corresponds to the transmembrane pressure limit and preferably the transmembrane pressure limit corresponds to a maximum transmembrane limit which the module must not exceed during the entire filtration process.

8. The method according to claim 4, characterized in that if the difference between the transmembrane pressure of a module (1) and the transmembrane pressure of another module (1) which at the same time has a higher or the highest transmembrane pressure in the module package > a differential value Dr is when one of the two modules switches from filtrate flow control to transmembrane pressure control, with the setpoint of the transmembrane control corresponding in particular to the transmembrane pressure of the module at which the filtrate flow is controlled.

9. The method according to at least claim 8, characterized in that in at least one module (1) of a package (3) the transmembrane pressure is regulated to a target value which is greater than its transmembrane pressure when switching to transmembrane pressure regulation and which in particular corresponds to the transmembrane pressure of the filtrate flow controlled module (1) with the highest transmembrane pressure.

10. The method according to claim 8, characterized in that in at least one module (1) of a package (3), the transmembrane pressure is regulated to a target value which is lower than its transmembrane pressure when switching to transmembrane pressure regulation and in particular the transmembrane pressure of the filtrate flow-regulated Mo module corresponds to the lowest transmembrane pressure.

11. The method according to claim 8, characterized in that the target value of the module switched to transmembrane pressure control corresponds to a mean value of the transmembrane pressures of the filtrate flow-controlled modules.

12. The method according to at least one of claims 1 to 11, characterized in that at least two module packages (3a, 3b) are arranged in parallel and the two module packages (3a, 3b) have a common unfiltrate inlet (5) and a common unfiltrate outlet 6, wherein , if the module packages (3a, 3b) each have n modules at n positions in a row, the modules that are arranged at the same nth position in the respective package (3) are controlled in such a way that the controls have the same controlled variable, in particular the same target value.

13. Device, in particular for carrying out the method with at least one module package (3a, 3b), each with a plurality of modules (1) for crossflow filtration, with a control device (7) which, during a filtration cycle, controls at least one module (1) from a Filtrate flow control can switch to a transmembrane pressure control.

14. Device according to claim 13, characterized in that the modules (1) of a module package (3) are arranged in series in a non-filtrate line (4) and non-filtrate is circulated through the modules (1) and filtrate in a respective filtrate line

(8) is derived, with the filtrate flow being measured in the respective filtrate line (8) by means of a flow meter (11) and the transmembrane pressure being monitored by means of pressure sensors (9, 90,91) in the unfiltrate line (4) and the respective filtrate line (8). will.

15. The apparatus of claim 13 or 14, characterized in that the actuator

(9) a control valve (10) in the filtrate line (8) for controlling the filtrate flow or the transmembrane pressure.

16. The method according to at least one of claims 1-12, characterized in that a filtration cycle begins with the beginning of the filtration and ends after all modules have reached a maximum transmembrane pressure limit and/or a minimum filtrate flow limit and/or a minimum total filtrate flow.