DE102023101425A1 - Membrane device with controllable flow control and corresponding process - Google Patents

Abstract

The invention relates to a membrane device with controllable flow guidance, with a membrane unit which has a semipermeable membrane and at least one first and at least one second flow-through chambers separated from one another by the semipermeable membrane, wherein at least one of the first and/or second chambers is assigned a line arrangement which has an inlet for feeding the respective chamber with a process fluid and an outlet for discharging the process fluid from the respective chamber, wherein the line arrangement has a valve group which is set up to take up a first valve circuit in which the process fluid is introduced into the membrane unit on a first side of the first or second chamber, and is set up to take up a second valve circuit in which the process fluid is introduced into the membrane unit on a second side of the first or second chamber which differs from the first side. The invention further relates to a corresponding method,

Description

The invention is based on a membrane device with at least one membrane unit, which has a semipermeable membrane and at least one first and at least one second flow-through chambers separated from one another by the membrane, wherein at least one of the first and/or second chambers is assigned a line arrangement which has an inlet for feeding the respective chamber with a process fluid and an outlet for discharging the process fluid from the respective chamber. The invention further relates to a corresponding method.

Membrane processes include forward osmosis, reverse osmosis and their intermediate forms such as pressure-retarded forward osmosis or osmotically assisted reverse osmosis, whose driving force is generated by an osmotic-hydraulic pressure gradient, microfiltration, ultrafiltration and nanofiltration, whose driving potential is generated by a pressure difference, perfusion, vapor permeation and gas permeation, whose driving force is generated by a partial pressure difference, dialysis, electrodialysis or bipolar electrodialysis, whose driving force is generated by an electrical potential difference and dialysis and diffusion dialysis, whose driving force is generated by a concentration difference.

Furthermore, membrane processes include all processes in which two fluids are brought into contact by means of a membrane.

In particular, the present invention solves a problem of forward osmosis. Forward osmosis is a process that can extract water from another material stream, the feed, using a highly osmotic draw solution, thereby dewatering and concentrating it. The forward osmosis process is considered promising and is currently at the end of the development phase. Many researchers and developers are currently working on bringing the forward osmosis process into the application phase so that it can be used commercially in industry.

An existing problem with forward osmosis and membrane processes in general is that the membrane is in continuous contact with fouling agents contained in the process solutions during operation. These accumulate on and in the membrane and lead to internal and external fouling. The initial area of a membrane section in a module is particularly affected by fouling, whereas the end area of the membrane is affected by scaling. Furthermore, solids contained in the process solutions can form a covering layer at the membrane inlet, particularly on the front surface of hollow fiber membranes, which are currently the standard forward osmosis membranes on the market, which means that the subsequent capillaries are no longer flowed through and are therefore technically ineffective. The fouling and the formation of a covering layer lead to a steady decline in the performance of the membrane and thus a reduction in its service life.

It is known that recurring cleaning routines can restore some of the membrane performance. The use of chemicals can remove the reversible fouling and the covering layer from the membrane. Another method is flushing at high overflow velocities so that the mechanical forces that occur remove the external fouling layers. These cleaning routines require a suspension of production, which significantly reduces plant availability and thus the economic efficiency of the process.

It is therefore the object of the present invention to provide a device or a method in which the membrane of a membrane device can be cleaned during production operation, which enables greater environmental protection and requires lower costs.

The problem is solved with the features of the independent claims. Advantageous embodiments are specified in the dependent claims.

Accordingly, it is provided that the line arrangement has a valve group which is designed to assume a first valve circuit in which the process fluid is introduced into the membrane unit on a first side of the first or second chamber, and is designed to assume a second valve circuit in which the process fluid is introduced into the membrane unit on a second side of the first or second chamber deviating from the first side.

The membrane unit can have at least two chambers, each of which has two sides, so that the membrane unit can have, for example, four sides, on which a process fluid can flow into or out of the membrane unit. The valve group can comprise a plurality of valves. The introduction of the process fluid on different sides can comprise the introduction on different sides of the same chamber. This allows the flow direction of the respective chamber to be changed. The introduction of the process fluid on different sides can further include introduction into different chambers. This makes it possible to swap the functions of the chambers. For example, in the first valve circuit, the first chamber can be used to pass the feed and the second chamber to pass the draw solution; after switching to the second valve circuit, the first chamber can then be used to pass the draw solution and the second chamber to pass the feed. A plurality of line arrangements with respective valve groups can be provided. This means that the functions described above can also be combined, so that the flow direction can be switched independently in each of the chambers and, moreover, different process solutions can flow into the chambers. It is understood that the membrane unit can also consist of several modules operated in series, parallel or in a combination thereof, which are connected to one another within a cascade/module connection to produce the desired membrane area. Furthermore, it is understood that the semipermeable membrane can also be formed by a hollow fiber membrane, a spiral wound membrane or a plate membrane, etc., which can have a plurality of chambers due to their design.

The device according to the invention allows the flow direction of the process streams to be changed immediately during operation without having to shut down the pumps. The full production capacity is therefore maintained. The abrupt reversal of the flow direction means that the cover layer at the entrance to the membrane bundle is now removed by the process solution that comes from the lumen of the capillaries. Furthermore, the constant impulse of switching leads to the external fouling of the membrane being reduced and is not only limited to the beginning of the membrane section, but is equally distributed between the beginning and the end.

A further advantage of the invention is the extended service life, i.e. the service life of the membrane before it has to be replaced with a new membrane.

Another advantage of the invention is the improved environmental protection, which results from the reduced membrane consumption as well as the reduction in cleaning chemicals. The lower material costs and the conversely increased production time therefore make the invention significantly more economical.

It can be provided that the process fluid flows out of the membrane unit from the side of the respective chamber opposite the inflow side. Of course, the intended separation processes take place via the semi-permeable membrane as it flows through.

It can be provided that in the first valve circuit the respective chamber is flowed through in a first direction, and in the second valve circuit the respective chamber is flowed through in a second direction, opposite to the first.

Furthermore, it is conceivable that the valve group separates a first region of the line arrangement on the inlet or outlet side, which has a constant flow direction, from a second region of the line arrangement on the membrane unit side, which has an alternating flow direction.

The inlet can be fluidically connected to the first side of the chamber via a first valve of the valve group and to the second side of the chamber via a second valve. The outlet can be fluidically connected to the first side of the chamber via a third valve of the valve group and to the second side of the chamber via a fourth valve.

It can be provided that in the first valve circuit the first and the fourth valve of the first valve group are opened and the second and the third valve of the first valve group are closed, and wherein in the second valve circuit the second and the third valve of the first valve group are opened and the first and fourth valve of the first valve group are closed.

Furthermore, it can be provided that in the first valve circuit a first process fluid is passed through the first chamber and a second process fluid is passed through the second chamber, and in the second valve circuit the first process fluid is passed through the second chamber and the second process fluid is passed through the first chamber.

Furthermore, it is conceivable that both of the chambers have at least one inlet and one outlet, wherein at least one of the first and/or second chambers is assigned a first line arrangement with a first valve group, in which in the first valve circuit the respective chamber is flowed through in a first direction, and in the second valve circuit the respective chamber is flowed through in a second direction opposite to the first, and wherein the first and the second chambers are assigned a second line arrangement which is fluidically connected to the inlets and the outlets and which has a second valve group, in which in the first valve valve circuit the flow passes through the first chamber and in the second valve circuit the flow passes through the second chamber.

The first process fluid can be introduced into the second line arrangement through a first inlet and the second process fluid through a second inlet of the second line arrangement. In addition, the first process fluid can be discharged from the second line arrangement through a first outlet and the second process fluid through a second outlet of the second line arrangement.

Furthermore, the first inlet can be fluidically connected to the second chamber via a first valve of the second valve group and the second inlet can be fluidically connected to the first chamber via a fourth valve of the second valve group. In addition, the first inlet can be fluidically connected to the first chamber via a second valve of the second valve group and the second inlet can be fluidically connected to the second chamber via a third valve of the second valve group.

Furthermore, the first outlet can be fluidically connected to the first chamber via a sixth valve of the second valve group and the second outlet can be fluidically connected to the second chamber via a seventh valve of the second valve group. Furthermore, the first outlet can be fluidically connected to the second chamber via an eighth valve of the second valve group and the second outlet can be fluidically connected to the first chamber via a fifth valve of the second valve group.

It is conceivable that in the first valve circuit of the second valve group the second valve and the third valve are opened and the first valve and the fourth valve are closed. It is also conceivable that in the second valve circuit of the second valve group the first valve and the fourth valve are opened and the second valve and the third valve are closed.

Furthermore, in the first or second valve circuit of the second valve group, the sixth and seventh valves may be opened and the fifth and eighth valves may be closed. Alternatively, the sixth and seventh valves may be closed and the fifth and eighth valves may be opened.

In particular, it can be provided that the first process solution is a feed and the second process solution is a draw solution. The draw solution can be discharged from the chamber through which it flows as a permeate and the feed can be discharged from the chamber through which it flows as a retentate.

Furthermore, a control device for controlling the at least one valve group can be provided, which is each set up for switching, in particular simultaneously, between the first and the second valve circuit.

• Einleiten eines ersten Prozessfluids in eine erste Seite zumindest einer ersten Kammer einer zwei durch eine semipermeable Membran separierte durchströmbare Kammern aufweisende Membraneinheit über eine erste Leitungsanordnung, wobei eine erste Ventilgruppe der ersten Leitungsanordnung zunächst eine erste Ventilschaltung aufweist;

The invention further relates to a method for influencing the flow guidance of a membrane device, in particular for operating a membrane device according to one of the preceding claims, comprising the steps:

• Introducing a first process fluid into a first side of at least a first chamber of a membrane unit having two flow-through chambers separated by a semipermeable membrane via a first line arrangement, wherein a first valve group of the first line arrangement initially has a first valve circuit;

Switching the first valve group from the first valve circuit to a second valve circuit, whereby the first process fluid is introduced into the membrane unit at a second side of the first or at least a second of the chambers, which side differs from the first side;

Discharge of the first process fluid from the side of the respective chamber of the membrane unit opposite the respective inflow side via the first line arrangement.

• Einleiten eines zweiten Prozessfluids in eine erste Seite der zweiten Kammer über eine zweite Leitungsanordnung, wobei eine zweite Ventilgruppe der zweiten Leitungsanordnung zunächst eine erste Ventilschaltung aufweist;

The method may further comprise the steps:

• Introducing a second process fluid into a first side of the second chamber via a second conduit arrangement, wherein a second valve group of the second conduit arrangement initially has a first valve circuit;

Switching the second valve group from the first valve circuit to a second valve circuit, whereby the second process fluid is introduced into the membrane unit at a second side of the first or second chamber deviating from the first side of the second chamber.

• Einleiten des ersten Prozessfluids in die erste Leitungsanordnung und des zweiten Prozessfluids in die zweite Leitungsanordnung über eine dritte Leitungsanordnung, wobei eine dritte Ventilgruppe der dritten Leitungsanordnung zunächst eine erste Ventilschaltung aufweist;

Furthermore, the method may comprise the steps:

• Introducing the first process fluid into the first line arrangement and the second process fluid into the second line arrangement via a third line arrangement, wherein a third valve group of the third line arrangement initially has a first valve circuit;

Switching the third valve group from the first valve circuit to a second valve circuit, whereby the first process fluid flows into the first chamber into the second chamber, and the second process fluid is introduced into the first chamber instead of the second chamber.

• 1 ein Schaltbild einer ersten Ausführungsform der Erfindung;
• 2 ein Schaltbild einer zweiten Ausführungsform der Erfindung;
• 3 ein Schaltbild einer dritten Ausführungsform der Erfindung.

Further details of the invention are explained with reference to the following figures.

• 1 a circuit diagram of a first embodiment of the invention;
• 2 a circuit diagram of a second embodiment of the invention;
• 3 a circuit diagram of a third embodiment of the invention.

1 shows a first embodiment of the membrane device 10 according to the invention. This essentially has a membrane unit 20 with a first and a second flow-through chamber 21, 22, which are separated by a semi-permeable membrane 23. The first chamber has a first inlet/outlet A and a second inlet/outlet B, in the embodiment shown the second chamber 22 has an inlet/outlet C. The membrane device 10 is supplied with a feed which is led via an inlet 31 into the valve group 40 of the first line arrangement 30. There it is led through valve 41 or valve 42, only one of the two being open, to the corresponding inlet A or B of a first chamber 21 of the membrane unit 20, with permeate 8 being discharged from a second chamber 22. The retentate is now directed to valve 44 and valve 42 or valve 43 and 41, depending on the previous valve position, whereby valve 43 or valve 44 is open depending on the previous valve circuit and the retentate can flow out via outlet 32. By means of an automatic control system, the closed valves can now be opened and the open valves closed at the same time, which causes a reversal of the flow direction.

2 shows a second embodiment of the membrane device 10 according to the invention. In contrast to the first embodiment of 1 two line arrangements 30, 50 with respective valve groups 40, 60, the first line arrangement 30 being connected to the first chamber 21 of the membrane unit 20 and the second line arrangement 50 being connected to the second chamber 22 of the membrane unit 20. The membrane device 10 is supplied with a feed which is led via an inlet 31 into the valve group 40 of the first line arrangement 30. There it is led through valve 41 or valve 42, only one of the two being open, to the corresponding inlet A or B of a first chamber 21 of the membrane unit 20, with permeate 8 being discharged from a second chamber 22. The retentate is now led to valve 44 and valve 42 or valve 43 and 41 according to the previous valve position, with valve 43 or valve 44 being open according to the previous valve circuit and the retentate being able to drain via outlet 32. By means of an automatic control, the closed valves can now be opened and the open valves closed at the same time, which reverses the flow direction of the feed. The membrane device 10 is also fed with a draw solution, which is fed via the second inlet 51 of the second line arrangement 50 into the second valve group 60. There it is led through valve 61 or valve 62, with only one of the two being open, to the corresponding inlet C or D of the membrane unit 20. After passing through the second chamber 22, the diluted draw solution is now fed to valve 61 and valve 63 or valve 62 and 64, depending on the previous valve position, with valve 63 or valve 64 being open according to the previous valve circuit and the diluted draw solution being able to drain via the outlet 52. By means of an automatic control, the closed valves can now be opened and the open valves closed at the same time, which reverses the flow direction of the draw solution. The valve groups of feed and pull solution can be switched simultaneously and independently of each other.

3 shows a third embodiment of the membrane device 10 according to the invention, which compared to the second embodiment of 2 additionally has a third line arrangement 70 with a third valve group 80, the third line arrangement 70 being fluidically connected to the inlets 31, 51 and outlets 32, 52 of the first and second line arrangements. For example, a feed is supplied to the membrane device 10 via the inlet 71 and is guided into the third valve group 80. There it is guided through valve 81 or valve 82, with only one of the two being open, to the corresponding side of the membrane unit 20, thereby defining the membrane orientation. There it is guided, depending on the membrane orientation, through valve 41 or valve 42, with only one of the two being open, or through valve 61 or valve 62, with only one of the two being open, to the corresponding inlet A, B, C, D of the membrane unit 20. The retentate is now directed to valve 42 and valve 44 or valve 43 and valve 41, or to valve 63 and valve 61 or valve 64 and valve 62, depending on the previous valve position and depending on the membrane orientation, whereby valve 43 or valve 44 or valve 63 or valve 64 is opened according to the previous valve circuit and the retentate can drain through valve 86 or valve 88 via the outlet 72, depending on the membrane orientation.

Furthermore, the embodiment consists of a pulling solution, which is fed, for example, via the inlet 73 of the third line arrangement 70 into the third valve group 80 of the membrane device 10. There it is fed through valve 83 or valve 84, with only one of the two being open, to the corresponding side of the membrane unit, thereby defining the membrane orientation. There it is fed, depending on the membrane orientation, through valve 41 or valve 42, with only one of the two being open, or through valve 61 or valve 62, with only one of the two being open, to the corresponding inlet A, B, C, D of the membrane unit 20. The diluted draw solution is now directed to valve 42 and valve 44 or valve 43 and valve 41, or to valve 63 and valve 61 or valve 64 and valve 62, depending on the previous valve position and the membrane orientation, whereby valve 43 or valve 44 or valve 63 or valve 64 is opened according to the previous valve circuit and the diluted draw solution can flow through valve 86 or valve 88 via the outlet 72, depending on the membrane orientation. The closed valves can now be opened and the open valves closed at the same time by means of an automatic control, which causes a reversal of the flow direction of the draw solution. In addition to the design in 2 An automatic control system can now simultaneously open the closed valves and close the open valves, which not only reverses the flow direction for feed solution and draw solution but also reverses the membrane orientation.

By alternating the flow direction of the mass flows as well as the alternating permeation directions, the production time and plant availability of the process can be significantly increased, thereby increasing the economic efficiency.

The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the realization of the invention both individually and in any combination.

List of reference symbols

8th

Permeate

10

Membrane device

20

Membrane unit

21

first flow-through chamber

22

second flow chamber

23

semipermeable membrane

30

first line arrangement

31

first entrance

32

first exit

40

first valve group

41

first valve

42

second valve

43

third valve

44

fourth valve

50

second line arrangement

51

second entrance

52

second exit

60

second valve group

61

first valve

62

second valve

63

third valve

64

fourth valve

70

third line arrangement

71

third entrance

72

third exit

73

fourth entrance

74

fourth exit

80

third valve group

81

first valve

82

second valve

83

third valve

84

fourth valve

85

fifth valve

86

sixth valve

87

seventh valve

88

eighth valve

A

first page

B

second page

C

third party

D

fourth page

F

Feed

Z

Train solution

Claims (20)

Membrane device (10) with controllable flow guidance, with at least one membrane unit (20) which has a semipermeable membrane (23) and at least one first and at least one second flow-through chambers (21, 22) separated from one another by the membrane, wherein at least one of the first and/or second chambers (21, 22) is assigned a line arrangement (30, 50, 70) which has an inlet (31, 52, 71, 73) for feeding the respective chamber (21, 22) with a process fluid (F, Z) and an outlet (32, 52, 72, 74) for discharging the process fluid (F, Z) from the respective chamber (21, 22), wherein the line arrangement (30, 50, 70) has a valve group (40, 60, 80) which is designed to take up a first valve circuit in which the process fluid (F, Z) is introduced into the membrane unit (20) on a first side (A, B, C, D) of the first or the second chamber (21, 22), and is designed to take up a second valve circuit in which the process fluid (F, Z) is a second side (A, B, C, D) of the first or second chamber (21, 22) deviating from the first side is introduced into the membrane unit (20). Membrane device (10) according to Claim 1 , wherein the process fluid (F, Z) flows out of the membrane unit (20) from the side (A, B, C, D) of the respective chamber (21, 22) opposite the inflow side (A, B, C, D). Membrane device (10) according to Claim 1 or 2 , wherein in the first valve circuit the respective chamber (21, 22) is flowed through in a first direction, and in the second valve circuit the respective chamber (21, 22) is flowed through in a second direction, opposite to the first. Membrane device (10) according to Claim 3 , wherein the valve group (40, 60) separates an inlet- or outlet-side first region of the line arrangement (30, 50), which has a constant flow direction, from a membrane unit-side second region of the line arrangement (30, 50), which has an alternating flow direction. Membrane device (10) according to Claim 3 or 4 , wherein the inlet (31, 51) is fluidically connectable to the first side (A, B, C, D) of the chamber (21, 22) via a first valve (41, 42, 61, 62) of the valve group (40, 60) and to the second side (A, B, C, D) of the chamber (21, 22) via a second valve (41, 42, 61, 62). Membrane device (10) according to one of the Claims 3 until 5 , wherein the outlet (32, 52) is fluidically connectable to the first side (A, B, C, D) of the chamber (21, 22) via a third valve (43, 44, 63, 64) of the valve group and to the second side (A, B, C, D) of the chamber (21, 22) via a fourth valve (43, 44, 63, 64). Membrane device (10) according to Claim 6 , wherein in the first valve circuit the first (41, 42, 61, 62) and the fourth valve (43, 44, 63, 64) are opened and the second (41, 42, 61, 62) and the third valve (43, 44, 63, 64) are closed, and wherein in the second valve circuit the second (41, 42, 61, 62) and the third valve (43, 44, 63, 64) are opened and the first (41, 42, 61, 62) and fourth valve (43, 44, 63, 64) are closed. Membrane device (10) according to Claim 1 or 2 , wherein in the first valve circuit a first process fluid (F) is passed through the first chamber (21) and a second process fluid (Z) is passed through the second chamber (22), and in the second valve circuit the first process fluid (F) is passed through the second chamber (22) and the second process fluid (Z) is passed through the first chamber (21). Membrane device (10) according to one of the Claims 3 until 7 , wherein both of the chambers have at least one inlet (31, 51) and one outlet (32, 52), wherein at least one of the first and/or second chambers (21, 22) is assigned a first line arrangement (30, 50) with a first valve group (40), in which in the first valve circuit the respective chamber (21, 22) is flowed through in a first direction, and in the second valve circuit the respective chamber (21, 22) is flowed through in a second direction opposite to the first, and wherein the first and the second chamber (21, 22) are assigned a second line arrangement (70) which is fluidically connected to the inlets (31, 51) and the outlets (32, 52) and which has a second valve group (80), in which in the first valve circuit the first chamber (21, 22) is flowed through and in the second valve circuit the second chamber (21, 22) is flowed through. Membrane device (10) according to Claim 8 or 9 , wherein the first process fluid (F) is introduced into the second line arrangement (70) through a first inlet (71, 73) and the second process fluid (Z) through a second inlet (71, 73) of the second line arrangement (70), and the first process fluid (F) is discharged from the second line arrangement (70) through a first outlet (72, 74) and the second process fluid (Z) through a second outlet (72, 74) of the second line arrangement (70). Membrane device (10) according to Claim 10 , wherein the first inlet (71) is fluidically connected to the second chamber (22) via a first valve (81) of the second valve group (80) and the second inlet (73) is fluidically connected to the first chamber (21) via a fourth valve (84) of the second valve group (80), and the first inlet (71) is fluidically connected to the first chamber (21) and the second inlet (73) is fluidically connectable to the second chamber (22) via a third valve (84) of the second valve group (80). Membrane device (10) according to one of the Claims 10 or 11 , wherein the first outlet (72) is fluidically connectable to the first chamber (21) via a sixth valve (86) of the second valve group (80) and the second outlet (74) is fluidically connectable to the second chamber (22) via a seventh valve (87) of the second valve group (80), and the first outlet (72) is fluidically connectable to the second chamber (22) via an eighth valve (88) of the second valve group (80) and the second outlet (74) is fluidically connectable to the first chamber (21) via a fifth valve (85) of the second valve group (80). Membrane device (10) according to Claim 12 , wherein in the first valve circuit of the second valve group (80) the second valve (82) and the third valve (83) are opened and the first valve (81) and the fourth valve (84) are closed, and in the second valve circuit of the second valve group (80) the first valve (81) and the fourth valve (84) are opened and the second valve (82) and the third valve (83) are closed. Membrane device (10) according to Claim 12 or 13 , wherein in the first or second valve circuit of the second valve group (80) the sixth and seventh valves (86, 87) are opened and the fifth and eighth valves (85, 88) are closed, or the sixth and seventh valves (86, 87) are closed and the fifth and eighth valves (85, 88) are open. Membrane device (10) according to one of the preceding claims, wherein the first process solution (F) is a feed and the second process solution (Z) is a draw solution. Membrane device (10) according to Claim 15 , wherein the draw solution (Z) is discharged from the chamber (21, 22) through which it flows as permeate and the feed (F) is discharged from the chamber (21, 22) through which it flows as retentate. Membrane device (10) according to one of the preceding claims, which further comprises a control device for controlling the at least one valve group, which is each set up for switching, in particular simultaneously, between the first and the second valve circuit. Method for influencing the flow guidance of a membrane device (10), in particular for operating a membrane device (10) according to one of the preceding claims, comprising the steps: Introducing a first process fluid (F, Z) into a first side (A, B, C, D) of at least one first chamber (21, 22) of a membrane unit (20) having two flow-through chambers (21, 22) separated by a semipermeable membrane (23) via a first line arrangement (30, 50, 70), wherein a first valve group (40, 60, 80) of the first line arrangement (30, 50, 70) initially has a first valve circuit; Switching the first valve group (40, 60, 80) from the first valve circuit to a second valve circuit, whereby the first process fluid (F, Z) is introduced into the membrane unit (20) on a second side (A, B, C, D) of the first or at least a second of the chambers (21, 22) deviating from the first side; Leading the first process fluid (F, Z) out of the side (A, B, C, D) of the respective chamber (21, 22) of the membrane unit (20) opposite the respective inflow side (A, B, C, D) via the first line arrangement (30, 50, 70). Procedure according to Claim 18 , further comprising the steps of: introducing a second process fluid (F, Z) into a first side (A, B, C, D) of the second chamber (21, 22) via a second line arrangement (30, 50, 70), wherein a second valve group (40, 60, 80) of the second line arrangement (30, 50, 70) initially has a first valve circuit; switching the second valve group (40, 60, 80) from the first valve circuit to a second valve circuit, whereby the second process fluid (F, Z) is introduced into the membrane unit (20) on a second side (A, B, C, D) of the first or second chamber (21, 22) which differs from the first side of the second chamber (21, 22). Procedure according to Claim 19 , further comprising the steps of: introducing the first process fluid into the first line arrangement and the second process fluid into the second line arrangement via a third line arrangement, wherein a third valve group (80) of the third line arrangement (70) initially has a first valve circuit; switching the third valve group (80) from the first valve circuit to a second valve circuit, whereby the first process fluid (F, Z) is introduced into the second chamber (21, 22) instead of into the first chamber (21, 22), and the second process fluid (F, Z) is introduced into the first chamber (21, 22) instead of into the second chamber (21, 22).

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