Method and apparatus for measuring filtrate content in a screw press

Abstract

The present invention relates to a screw press (1) for separating a filtrate from a feed material. The screw press (1) comprises: A sensor mechanism (9) comprising a sensor (7) for measuring the filtrate content is arranged in the discharge area (4) of the screw press (1), whereby the feed material can flow towards and / or around the sensor (7), which can be measured simply, quickly and accurately.

Description

[Technical Field]

[0001] The present invention relates to a screw press for separating filtrate from a feed material, the screw press comprising a feed zone, a dewatering zone, and a discharge zone, In this case, the feed material can be fed to the screw press via a feed area, the dewatering zone includes a pressure screw rotatable about a rotation axis and disposed within the filter drum, and rotation of the pressure screw can transport the feed material from the feed zone through the dewatering zone to the discharge zone; In this case, the feed material is guided in a dewatering region between the filter drum and the pressure screw, and passes through the filter drum from which the filtrate can be separated.

[0002] The present invention also relates to a method for separating a filtrate from a feed material, In this method, a feed material is fed to the screw press of the present invention through a feed zone; filtrate is separated from the feed material in a dewatering zone between a press screw rotating about a rotation axis and a filter drum; The feed material is then compressed between the feed and discharge regions, and the filtrate is discharged through a filter drum.

[0003] Additionally, the present invention relates to the use of a sensor in a screw press to measure the filtrate content in a feed material. [Background technology]

[0004] Typically, a screw press, such as a fiber screw or pulp screw, is used to separate the filtrate from the feed material, where the feed material comprises a solid phase (solids) and a liquid phase (filtrate). Here, the filtrate content indicates the ratio of the liquid phase (filtrate) to the feed material. Dewatering separates the filtrate from the feed material, thus reducing the filtrate content in the feed material. In this case, the feed material is fed to a screw press via a feeding zone. In the dewatering zone, the feed material is dewatered, and the dewatering zone includes a filter drum and a pressure screw rotatable about a rotation axis. Typically, the filter drum is perforated so that the filtrate extruded from the feed material can be discharged or separated through the filter drum. The function of the pressure screw is, on the one hand, to transport the feed material from the feeding zone to the discharge zone, and, on the other hand, to gradually compress the feed material and allow the filtrate to be separated through the filter drum.

[0005] The feedstock may have significantly different properties, for example, due to variations in the filtrate content in the feed zone, differences in dewaterability, or differences in the solid phase composition or structure. In this case, it is important that a specific filtrate content can be set in the screw press and continuously maintained during operation. Otherwise, subsequent processes will not operate optimally. Often, this is determined / detected by sampling the filtrate content at the screw press discharge at discrete time intervals, which means manually sampling, evaluating, and analyzing the samples. This is time-consuming and only provides information about the screw press operation at the time of sampling, with some delay. Time discrepancies are problematic because, for example, the filtrate content cannot be optimally adjusted during that time, and therefore effective chemical dosing cannot be achieved, or the filtrate content in the discharge zone fluctuates, adversely affecting subsequent processes, such as combustion.

[0006] Patent document 1 describes an apparatus for separating components of a liquid containing solids, in which the inner shell surface of the outlet nozzle configured as a pressure zone is provided with at least one raised protrusion in the form of a claw that opposes the discharge movement of the solid cake, in which case the at least one claw may be provided with a sensor or can be a sensor itself, thus making it possible to measure various values ​​at the outlet nozzle of the apparatus, for example the moisture content.

[0007] US Patent No. 5,949,999 describes an apparatus and method for adjusting the dry matter content of a solid cake using a sensor present in or on the outlet nozzle to determine the moisture content or pressure of the solid cake.

[0008] Patent document 3 describes a screw press separator equipped with a sensor that detects the stress caused by solid material on at least one component of the screw press separator, in order to control the dry matter content of the solid material leaving the screw press separator during operation. Patent document 2 (DE102017115080A1) discloses a method for adjusting the dry matter content of a solid cake and an apparatus for separating solid-containing liquid components. Accordingly, the power consumption of a drive device is taken as a measure of the moisture content of the produced solid cake, and / or the moisture content or pressure of the solid cake determined by at least one sensor is used as a measure for feeding the solid cake. Patent document 4 (EP1873123A1) discloses a sludge thickener, in which a tank is configured to contain thickened sludge and the tank is equipped with a power sensor for determining the sludge concentration. In this case, the power sensor comprises a rotatable cylinder immersed in the thickened sludge, and the sludge concentration is inferred from changes in power consumption.

[0009] However, the filtrate content is not measured directly but is estimated via correlated variables (pressure or pressure-induced stresses on machine parts). Finally, since many disturbing variables nowadays affect dewaterability, the filtrate content determined in this way serves only as a guide. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] German Utility Model No. 202017105625 [Patent Document 2] German Patent Application Publication No. 102017115080 [Patent Document 3] German Utility Model No. 202012008077 [Patent Document 4] European Patent Application Publication No. 1873123 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is a simple, fast and accurate determination of filtrate content. [Means for solving the problem]

[0012] According to the present invention, this is achieved by arranging a sensor mechanism including a sensor for measuring the filtrate content in the discharge area, allowing the feed material to flow toward and / or around the sensor. After compression of the feed material in the dewatering area, the feed material is sent to the discharge area, where it is released in the discharge area, i.e., the pressure in the discharge area is reduced relative to the dewatering area. Surprisingly, it has been found that arranging the measuring device in the discharge area is more advantageous than arranging it in the dewatering area. Thus, an incorrect filtrate content is often determined by arranging the measuring device in the dewatering area. In contrast, the inventive arrangement in the discharge area leads to reliable measurement results. In this case, the inventive arrangement of the sensor in the discharge area makes it possible to measure the filtrate content at a relatively constant pressure, since the feed material is decompressed in the discharge area (e.g., to ambient pressure or to the pressure level of a subsequent process step). However, different pressures are applied in the dewatering area due to the operation of the screw press. According to the present invention, a sensor for measuring the filtrate content is used. Advantageously, the sensor for measuring the filtrate content is based on measuring the dielectric constant of the feed material. In accordance with the present invention, the feed material flows over and / or around the sensor. The flow of the feed material over and / or around the sensor has the effect of exerting a force on the sensor that corresponds to the pressure exerted by the feed material on the sensor. In accordance with the present invention, the filtrate content in the feed material can be measured continuously, i.e., in-line.

[0013] According to the present invention, the screw press is characterized in that the pressure acting on the sensor from the feed material can be compensated via a sensor mechanism, in which the sensor mechanism includes a guide, and the sensor that compensates for the pressure acting on the sensor from the feed material can be moved via the guide in the discharge area. Typically, the feed material to be dewatered is a non-Newtonian fluid. Surprisingly, it has now been discovered that the dielectric constant is pressure-dependent. To avoid misidentification of the dielectric constant, and thus the filtrate content, the sensor is preferably part of the sensor mechanism, in which case the pressure of the feed material acting on the sensor can be compensated by the sensor mechanism, and a constant pressure (set pressure) acting on the sensor can be achieved via the compensation. In this way, the pressure acting on the sensor can be kept constant, i.e., at the target pressure level, and the influence of pressure deviations on the dielectric constant can be avoided, allowing for accurate measurement of the filtrate content.

[0014] Surprisingly, compensation for the pressure acting on the sensor is possible because the sensor is movable within the discharge area via a guide of the sensor mechanism, which allows the sensor to move along the guide within the discharge area to avoid pressures that deviate from the target pressure and to be positioned within the discharge area in accordance with the target pressure.

[0015] In one advantageous embodiment, the guide of the sensor mechanism allows the sensor to be moved in a plane, with the rotation axis of the pressure screw forming a normal to this plane. In another advantageous embodiment, for example, the distance of the sensor to the rotation axis of the pressure screw can be changed by moving the sensor along the guide.

[0016] A similarly preferred embodiment of the screw press is characterized in that a compensation force can be applied to the sensor via a guide, where the compensation force counteracts the force resulting from the pressure acting on the sensor. Preferably, the compensation force is applied to the sensor via a guide, where the compensation force is directed opposite to the force corresponding to the pressure of the feed material acting on the sensor. In force equilibrium, i.e., when the compensation force and the force from the pressure of the feed material are equal, the sensor does not move. If there is a difference between the compensation force and the force from the pressure of the feed material, the sensor moves along the guide in the direction of the larger force.

[0017] An advantageous embodiment applies a constant compensation force to the sensor, in which case the sensor is movable within a range of movement via a guide of the sensor mechanism, and the compensation force applied to the sensor is constant over at least a portion of the range of movement.

[0018] A particularly preferred embodiment is characterized in that the sensor mechanism includes a spring, where the spring acts pneumatically, hydraulically, electrically, or magnetically, and a compensation force can be applied to the sensor via the spring. Advantageously, the compensation force can be applied via a spring that acts pneumatically, hydraulically, electrically, or magnetically. The pneumatic or hydraulic spring can be realized by a pneumatically or hydraulically actuated cylinder. The compensation force acts on the sensor depending on the air pressure or oil pressure in the cylinder.

[0019] In particular, it is advantageous to apply a compensation force to the sensor via a magnetic spring, where the compensation force is constant. Such a magnetically acting spring allows a constant force action over a certain area and therefore can apply a constant force action to the sensor over at least a part of its range of movement. Such a magnetically acting spring is provided as an industrial constant force spring. Magnetically acting springs have the advantage over pneumatic, hydraulic, or electrically acting springs that no auxiliary systems (e.g., air pressure, hydraulics, etc.) are required.

[0020] Another preferred embodiment of the screw press is characterized in that, when the compensation force prevails, the sensor is movable along the guide against the force resulting from the pressure acting on the sensor, and when the force resulting from the pressure acting on the sensor prevails, the sensor is movable along the guide in the direction of the force resulting from the pressure. Surprisingly, the resulting force due to the pressure acting on the sensor varies depending on the sensor's position in the discharge area. Advantageously, the guide allows the sensor to be positioned such that the distance of the sensor from the axis of rotation is variable along the guide. Then, for example, when the sensor is moved along the guide by a larger resulting force against a smaller, constant compensation force, the distance of the sensor from the axis of rotation changes. According to the invention, as the distance of the sensor from the axis of rotation changes, the resulting force approaches a constant compensation force in magnitude. Conversely, for example, when the sensor is moved along the guide against a smaller resulting force by a larger, constant compensation force, the distance between the sensor and the axis of rotation also changes. As the distance of the sensor from the axis of rotation changes, the resulting force approaches again a compensation force that is constant in magnitude, according to the invention. This self-adjustment leads to a positioning of the sensor, in which the pressure acting on the sensor is compensated.

[0021] It is also an object of the present invention to provide a method for separating filtrate from a feedstock with a simple, rapid, and accurate measurement of the filtrate content.

[0022] According to the invention, this is achieved by measuring the filtrate content of the feed material in the discharge region, where the feed material flows toward and / or around a sensor that measures the filtrate content. In the drainage region, decompression of the feed material is performed after compression of the feed material in the dewatering region. It is surprisingly advantageous to perform the measurement of the filtrate content in the discharge region rather than in the dewatering region. According to the invention, the feed material flows toward and / or around a sensor for measuring the filtrate content, where the sensor for measuring the filtrate content is based on measuring the dielectric constant of the feed material.

[0023] According to the present invention, the method is characterized in that the sensor mechanism can compensate for the pressure acting on the sensor from the feed material, whereby the sensor is moved through a guide of the sensor mechanism in the discharge area to compensate for the pressure acting on the sensor from the feed material. Surprisingly, this means that the pressure acting on the sensor varies depending on the position of the sensor in the discharge space. In this way, compensation for the pressure acting on the sensor is made possible by positioning the sensor in the discharge area according to the target pressure, avoiding pressure deviations from the target pressure along the guide. This arrangement achieves a constant pressure (target pressure) acting on the sensor, thereby avoiding pressure effects on the dielectric constant.

[0024] Another preferred embodiment of the method is characterized in that a compensation force is applied to the sensor via a guide, whereby the compensation force acts against the force from the pressure acting on the sensor. If there is a difference between the compensation force and the force from the feed material pressure, the sensor moves along the guide in the direction of the greater force. As the sensor moves within the discharge space, the pressure acting on the sensor also changes, whereby the sensor is positioned in the discharge area according to the target pressure or according to the balance of the forces acting on the sensor from the compensation force and the force from the feed material pressure.

[0025] An advantageous embodiment of the method is characterized in that a constant compensation force is applied to the sensor.

[0026] An equally advantageous embodiment of the method is characterized in that the compensation force is applied to the sensor via a spring of the sensor mechanism, the spring acting pneumatically, hydraulically, electrically or magnetically. Advantageously, the pneumatically, hydraulically, electrically or magnetically acting spring allows the compensation force to be applied to the sensor over at least part of its range of movement.

[0027] An advantageous embodiment of the method is characterized in that a constant compensation force is applied to the sensor via a magnetic spring, which is particularly advantageous since it allows applying a constant compensation force to the sensor over at least a portion of the guide, independently of a secondary system (hydraulic, pneumatic, ...).

[0028] An advantageous embodiment of this method is characterized in that, when the compensation force prevails, the sensor is moved along the guide against the force resulting from the pressure acting on the sensor, and when the force resulting from the pressure acting on the sensor prevails, the sensor is moved along the guide in the direction of the force resulting from the pressure. Advantageously, the guide allows the sensor to be positioned such that the distance of the sensor from the axis of rotation is variable along the guide. For example, when the sensor is moved along the guide with a larger resulting force against a smaller, constant compensation force, the resulting force approaches a constant compensation force in magnitude. Conversely, for example, when the sensor is moved along the guide with a larger constant compensation force against a smaller resulting force from the pressure, the resulting force also approaches a constant compensation force in magnitude. This self-adjustment leads to a positioning of the sensor in which the pressure acting on the sensor is compensated.

[0029] Equally advantageous is the use of a sensor for measuring the filtrate content in the feed material in the screw press according to the invention, wherein the sensor is arranged in a sensor arrangement and the feed material flows towards and / or around the sensor. According to the present invention , used in conjunction with compensation of the pressure acting on the sensor, whereby the sensor, which compensates for the pressure acting on the sensor from the feed material, is moved through guides in the sensor mechanism in the discharge area.

[0030] The invention will now be described, by way of example only, with reference to the drawings in which: [Brief explanation of the drawings]

[0031] [Figure 1]FIG. 1 shows a screw press according to the present invention. [Figure 2] FIG. 2 shows in detail the discharge area of ​​a screw press according to the invention. [Figure 3] FIG. 3 shows an advantageous sensor arrangement. [Figure 4] FIG. 4 shows an advantageous sensor arrangement in the discharge area of ​​a screw press. [Figure 5] FIG. 5 shows an advantageous sensor arrangement in the discharge area of ​​a screw press, viewed in the direction of the axis of rotation. DETAILED DESCRIPTION OF THE INVENTION

[0032] FIG. 1 shows a screw press according to the present invention. The screw press 1 includes a feed zone 2, a dewatering zone 3, and a discharge zone 4. The dewatering zone 3 includes a pressure screw 6 rotatably arranged within a filter drum 5 about a rotation axis 13. The pressure screw 6 may, for example, include a spiral blade arranged on a shaft. The space between the filter drum 5 and the pressure screw 6 gradually narrows toward the discharge zone 4. The feed material is fed to the screw press 1 via the feed zone 2, whereupon the filtrate passes through the filter drum 5 and is separated from the feed material in the dewatering zone 3. For this purpose, the filter drum 5 has openings, e.g., perforations. Due to the rotation of the pressure screw 6 within the filter drum 5, the feed material is fed from the feed zone 2 through the dewatering zone 3 to the discharge zone 4, whereupon the feed material in the dewatering zone 3 is gradually compressed toward the discharge zone 4. The feed material enters the discharge region 4 through an annular gap 16 formed between the filter drum 5 and the pressure screw 6, which conveys the feed material discharged from the dewatering region 3 to the counterpressure unit 14. The counterpressure unit 14 is, for example, circular, and when viewed in the direction of rotation 13, the annular ring of the counterpressure unit 14 can be aligned at least with the annular gap 16 between the filter drum 5 and the pressure screw 6. The feed material is deflected radially outward in the counterpressure unit 14, and the feed material also has a circumferential velocity component corresponding to the rotation of the pressure screw 6. As the counterpressure unit 14 deflects the feed material, its pressure is released in the discharge region 4. The counterpressure unit 14 thus allows the pressure on the conveyed material to increase in the dewatering region 3, and as the counterpressure unit 14 deflects the conveyed material, the pressure in the conveyed material decreases. According to the present invention, the sensor mechanism 9 including the sensor 7 is arranged in the discharge area 4 (not shown in FIG. 1 ) so that the feed material can flow towards the sensor 7 and / or so that the feed material can flow around the sensor 7.

[0033] FIG. 2 shows in detail the discharge region of the screw press according to the present invention. In the dewatering region 3, the feed material is compressed toward the discharge region 4. The feed material is guided into the gap region between the filter drum 5 and the pressure screw 6, which then transports the feed material through a gap 16 from the dewatering region 3 toward the counterpressure unit 14. In this case, the pressure screw 6 may, for example, consist of a shaft and spiral blades. The feed material enters the discharge region 4 through the annular gap 16 formed between the filter drum 5 and the pressure screw 6. The feed material is deflected radially outward between the wall 15 of the discharge region 4 and the counterpressure unit 14, whereupon it also experiences a peripheral velocity component corresponding to the rotation of the pressure screw 6. The deflection of the feed material in the counterpressure unit 14 releases pressure from the discharge region 4.

[0034] FIG. 3 shows an advantageous sensor arrangement. According to the invention, the sensor arrangement 9 comprises a sensor 7 for measuring the filtrate content of the feed material. Advantageously, the measurement of the filtrate content is based on measuring the dielectric constant of the feed material. Advantageously, the sensor arrangement 9 further comprises a guide 10 and a spring 12. In this case, the sensor 7 is connected to the spring 12 via the guide 10, whereby the sensor 7 is movable via the guide 10. The pressure acting on the sensor 7 by the feed material, or the resulting force, is transmitted via the guide 10 to the spring 12, whereby the spring 12 transmits a compensation force to the guide 10. In this case, the compensation force of the spring 12 and the force resulting from the feed material on the guide 10 are directed in opposite directions, corresponding to an opposing action (action = reaction). When the compensation force prevails, the sensor 7 moves across the guide 10 against the force resulting from the pressure acting on the sensor 7, or when the force resulting from the pressure acting on the sensor 7 prevails, the sensor 7 moves along the guide 10 in the direction of the resulting force. As long as the balance between the resulting force and the compensation force is maintained, there is no further movement of the sensor. In this way, the sensor mechanism 9 allows compensation of the resulting force acting on the sensor 7 from the feed material. Advantageously, the spring 12 can apply a constant compensation force to the sensor 7. Since the sensor 7 is movable via a guide within the range of movement 11, a constant compensation force can be applied to the sensor 7 via the spring 12 over at least a portion of the range of movement 11. Advantageously, the spring 12 acts pneumatically, hydraulically, electrically, or magnetically. Using a magnetically acting spring 12, a constant force effect on the sensor 7 can be achieved over a range or at least over a partial range of the range of movement 11. Such a magnetically acting spring 12 can be provided, for example, as an industrial constant force spring and has the advantage over pneumatic, hydraulically, or electrically acting springs, since no auxiliary systems (e.g., pneumatic, hydraulic, etc.) are required.

[0035] FIG. 4 shows an advantageous sensor arrangement in the discharge region of a screw press. The pressure screw 6 is shown rotatably about a rotation axis 13, extending from the dewatering region 3 to the discharge region 4. The conveyed material is fed to the discharge region 4 through a gap 16 between the filter drum 5 (not shown) and the pressure screw 6, or through a gap 16 between the wall 15 of the discharge region 4 and the pressure screw 6. The sensor arrangement 9 can be fixed to the wall 15 of the discharge region. The sensor arrangement 9 includes a sensor 7, a guide 10, and a spring 12, where the guide 10 allows the sensor 7 to move within a range of movement 11. The feed material can flow against the sensor 7 and / or around the sensor 7. In this case, the feed material is guided from the dewatering region 3 into the discharge region 4 and turns radially outward between the wall 15 of the discharge region 4 and the counterpressure unit 14, whereupon the feed material also has a peripheral velocity component corresponding to the rotation of the pressure screw 6. Advantageously, seen in the axial direction, i.e. in the direction of the rotation axis 13, the sensor 7 is arranged between the wall 15 of the discharge area 4 and the counterpressure unit 14, with the feed material flowing against and / or around the sensor 7 after having been deflected in the counterpressure unit. When the sensor 7 moves within the range of movement 11 of the guide 10 in the discharge area 4, it is advantageously possible to position the sensor 7 inside and / or outside the gap 16 between the wall 15 of the discharge area 4 and the pressure screw 6, so that the feed material can flow appropriately against and / or around the sensor 7.

[0036] 5 shows an advantageous sensor arrangement in the discharge area of ​​a screw press, viewed in the direction of the rotation axis. Here, the pressure screw 6 is shown diagrammatically, extending into the discharge area 4. The conveyed material is fed to the discharge area 4 via a gap 16 between the filter drum 5 (not shown) and the pressure screw 6, or via a gap 16 between a wall 15 of the discharge area 4 and the pressure screw 6. The sensor arrangement 9 is fixed to the wall 15 of the discharge area 4 and comprises a sensor 7, a guide 10, and a spring 12, with the guide 10 enabling the sensor 7 to move within a range of movement 11. The feed material flows against and / or around the sensor 7. When the sensor 7 moves within the range of movement 11 of the guide 10 in the discharge area 4, it is advantageously possible to position the sensor 7 inside and / or outside the gap 16 between the wall 15 of the discharge area 4 and the pressure screw 6, thereby allowing the feed material to flow properly to and / or around the sensor 7.

[0037] The present invention offers several advantages. It allows for a simple, rapid, and accurate measurement of the filtrate content of feedstock processed in a screw press. By accurately determining the filtrate content, the operation of the screw press can be adjusted to achieve a constant filtrate content, and the usual influencing parameters (press screw speed, counterpressure device pressure, etc.) can be automatically controlled and set to the desired filtrate content. A precisely adjusted filtrate content after the screw press is advantageous for subsequent processes, as the optimum operating point can be set. [Explanation of symbols]

[0038] 1. Screw press 2 Supply area 3 Dehydration area 4 Emission area 5 filter drum 6 Pressing screw 7 Sensors 8 Axial Direction 9 Sensor mechanism 10 Guide 11. Moving Range 12 Spring 13 Rotation axis 14 Opposed pressure unit 15 Wall 16 Gap

Claims

1. A screw press (1) for separating filtrate from a feed material, comprising: The screw press (1) comprises a feed zone (2), a dewatering zone (3), and a discharge zone (4), In this case, the feed material can be fed to the screw press (1) via a feed area (2), The dewatering zone (3) comprises a press screw (6) rotatable about a rotation axis (13) and arranged in the filter drum (5); The rotation of the press screw (6) allows the feed material to be conveyed from the feeding zone (2) through the dewatering zone (3) to the discharge zone (4); In this case, the feed material is guided into a dewatering area (3) between a filter drum (5) and a press screw (6), and a filtrate can be separated through the filter drum (5), and a sensor mechanism (9) including a sensor (7) for measuring the filtrate content is arranged in the discharge area (4), In this case, in the screw press (1), the feed material can flow towards and / or around the sensor (7), The pressure acting on the sensor (7) from the feed material can be compensated for via the sensor mechanism (9); In this case, the sensor mechanism (9) is provided with a guide (10), and the sensor (7) is movable within the discharge area (4) via the guide (10) to compensate for the pressure acting on the sensor (7) from the feed material.

2. 2. The screw press (1) according to claim 1, characterized in that a compensating force can be applied to the sensor (7) via the guide (10), wherein the compensating force counteracts the force resulting from the pressure acting on the sensor (7).

3. 3. The screw press (1) according to claim 2, characterized in that a constant compensation force can be applied to the sensor (7).

4. The sensor mechanism (9) comprises a spring (12); 4. The screw press (1) according to claim 2 or 3, characterized in that the spring (12) acts pneumatically, hydraulically, electrically or magnetically and can apply a compensating force to the sensor (7) via the spring (12).

5. A compensation force can be applied to the sensor (7) via a magnetic spring (12), 3. The screw press (1) according to claim 2, wherein the compensation force is constant.

6. 6. The screw press (1) according to claim 2, wherein, when the compensation force prevails, the sensor (7) is movable along the guide (10) in a direction counter to the force resulting from the pressure acting on the sensor (7), and when the force resulting from the pressure acting on the sensor (7) prevails, the sensor (7) is movable along the guide (10) in the direction of the force resulting from the pressure.

7. 1. A method for separating a filtrate from a feed material, comprising: In this method, the feed material is fed to the screw press (1) according to any one of claims 1 to 6 via a feed zone (2), The filtrate is separated from the feed material in a dewatering zone (3) between a press screw (6) rotating about a rotation axis (13) and a filter drum (5); In this case, the feed material is compressed between the feed area (2) and the discharge area (4), and the filtrate is discharged through a filter drum (5), and a measurement of the filtrate content of the feed material is carried out in the discharge area (4), The feed material then flows towards and / or around a sensor (7) for measuring the filtrate content, in which The sensor mechanism (9) is capable of compensating for pressure acting on the sensor (7) from the feed material; The method is characterized in that the sensor (7) is moved within the discharge area (4) via a guide (10) of the sensor mechanism (9) in order to compensate for the pressure acting on the sensor (7) from the feed material.

8. A compensation force is applied to the sensor (7) via a guide (10), 8. The method according to claim 7, wherein the compensation force counteracts the force resulting from the pressure acting on the sensor (7).

9. 9. A method according to claim 8, characterized in that a constant compensation force is applied to the sensor (7).

10. A compensation force is applied to the sensor (7) via the spring (12) of the sensor mechanism (9), 10. A method according to claim 8 or 9, characterized in that the spring (12) is pneumatically, hydraulically, electrically or magnetically acting.

11. 9. The method according to claim 8, characterized in that a constant compensation force is applied to the sensor (7) via a magnetic spring (12).

12. 12. The method according to claim 8, wherein, when the compensation force prevails, the sensor (7) is moved along the guide (10) in a direction counter to the force resulting from the pressure acting on the sensor (7), and when the force resulting from the pressure acting on the sensor (7) prevails, the sensor (7) is moved along the guide (10) in the direction of the force resulting from the pressure.

13. Use of a sensor (7) for measuring the filtrate content of a feed material in a screw press (1) according to any one of claims 1 to 6, comprising: Use characterized in that the sensor (7) is arranged in a sensor arrangement (9) and the feed material flows against and / or around the sensor (7).

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