Method and device for measuring filtrate content in a screw press

Abstract

The invention relates to a screw press (1) for separating a filtrate from a feed. The invention is characterized in that a sensor device (9) comprising a sensor (7) for measuring the filtrate content is arranged in the discharge area (4), wherein the feed flows against and / or around the sensor (7). In this way, the filtrate content can be measured simply, quickly and accurately.

Description

Technical Field

[0001] This invention relates to a screw press for separating filtrate from feed, comprising a feeding zone, a dehydration zone, and a discharge zone, wherein the feed is fed into the screw press through the feeding zone, the dehydration zone includes a pressing screw rotatably arranged in a filter cylinder about a rotating axis, and the feed is fed from the feeding zone through the dehydration zone into the discharge zone by the rotation of the pressing screw, wherein the feed is guided between the filter cylinder and the pressing screw in the dehydration zone, and the filtrate is separated through the filter cylinder.

[0002] The present invention also relates to a method for separating filtrate from feed, wherein the feed is fed into a screw press according to the invention through a feed zone, and the filtrate is separated from the feed in a dehydration zone between a pressing screw rotating about a rotating axis and a filter cartridge, wherein the feed is compressed between a feed zone and a discharge zone, and the filtrate is discharged through the filter cartridge.

[0003] The present invention also relates to the use of a sensor for measuring the filtrate content of feed in a screw press. Background Technology

[0004] Screw presses are commonly used to separate filtrate from feed, such as in fiber screw presses or pulp screw presses. The feed consists of a solid phase (solids) and a liquid phase (filtrate). Filtrate content indicates the proportion of the liquid phase (filtrate) in the feed. The filtrate is separated from the feed by dewatering, thereby reducing the filtrate content in the feed. In this process, the feed is fed into the screw press through the feed zone. In the dewatering zone, the feed is dewatered, and this zone includes a filter cartridge and a press screw rotating around a rotating shaft. The filter cartridge typically has perforations so that the filtrate pressed from the feed can be discharged or separated through the filter cartridge. The function of the press screw is twofold: firstly, to transport the feed from the feed zone to the discharge zone, and secondly, to compress the feed in an increasingly forceful manner, enabling the filtrate to be separated through the filter cartridge.

[0005] Feed materials often exhibit highly variable characteristics, such as fluctuating filtrate content in the feed zone, varying dehydration properties, or different compressibility due to variations in the composition or structure of the solid phase. Crucially, the screw press must be able to set a specific filtrate content and maintain it consistently throughout operation. Only in this way can subsequent processes operate optimally. This is typically achieved by sampling the filtrate content at discontinuous time intervals in the screw press discharge zone, which involves manual sampling, evaluation, and analysis. This is time-consuming and provides only a certain delay in the screw press's operating information at the time of sampling. These temporal variations are problematic; for example, the filtrate content may not be optimized during this period, preventing effective stoichiometry, or the filtrate content in the discharge zone may fluctuate, potentially disrupting subsequent processes such as combustion.

[0006] DE 202017105625 U1 describes an apparatus for separating components of a liquid containing solids, wherein the inner surface of the outlet nozzle, formed as a pressing zone, has at least one protruding protrusion, shaped like a sporn, that obstructs the discharge movement of the solid cake. The at least one protrusion may have a sensor or be a sensor itself, thus allowing various values, such as moisture content, to be measured at the outlet nozzle of the apparatus.

[0007] DE 102017115080 A1 describes an apparatus and method for adjusting the dry matter content of a solid cake, wherein a sensor is located inside or on the outlet nozzle for determining the moisture content or pressure of the solid cake.

[0008] DE 20 2012 008 077 U1 describes a screw press separator whose sensors are used to detect stress in at least one component of the screw press separator due to solid matter. This is for controlling the dry matter content of the solids flowing out of the screw press separator during operation.

[0009] DE 10 2017 115080A1 discloses a method for adjusting the dry matter content of a solid cake and an apparatus for separating liquid components containing solids. Therefore, it discloses using the power consumption of the driving device as a measure of the moisture content of the produced solid cake, and / or using the moisture content or pressure of the solid cake determined by at least one sensor as a measure of the discharged solid cake.

[0010] EP1873123A1 discloses a sludge thickener in which a tank is configured to contain concentrated sludge, the tank including a power sensor for determining the sludge concentration. The power sensor includes a rotatable cylinder immersed in the concentrated sludge, wherein the sludge concentration is inferred from changes in power consumption.

[0011] However, in this method, the filtrate content is not measured directly, but estimated through relevant variables—pressure or stress caused by pressure in mechanical components. Since many confounding variables ultimately affect dehydration, the filtrate content determined in this way can only serve as a guideline. Summary of the Invention

[0012] The purpose of this invention is to provide a simple, rapid, and accurate method for measuring the content of filtrate.

[0013] According to the invention, the object is achieved by arranging a sensor device including a sensor for measuring filtrate content in the discharge zone, wherein the feed flows toward and / or around the sensor. After the feed is compressed in the dehydration zone, it is fed into the discharge zone, where the feed is depressurized, that is, the pressure in the discharge zone is lower than that in the dehydration zone. Surprisingly, it has been found that placing the measuring device in the discharge zone is more advantageous than placing it in the dehydration zone. Therefore, using a measuring device placed in the dehydration zone often yields inaccurate filtrate content readings. Conversely, according to the invention, placing the measuring device in the discharge zone provides reliable measurement results.

[0014] According to the invention, the arrangement of the sensor in the discharge zone allows for the measurement of filtrate content under relatively stable pressure because the feed is depressurized in the discharge zone (e.g., reduced to ambient pressure or to the pressure level of subsequent process steps). Conversely, depending on the operation of the screw press, varying pressures occur in the dewatering zone. According to the invention, the sensor is used to measure the filtrate content. Advantageously, the measurement of filtrate content is based on the measurement of the dielectric constant of the feed. According to the invention, the feed flows toward and / or around the sensor. The effect of the feed flowing toward and / or around the sensor is that the feed exerts a force on the sensor corresponding to the pressure exerted on the sensor by the feed. According to the invention, the filtrate content in the feed can be measured continuously, i.e., in-line.

[0015] According to the present invention, the screw press is characterized in that the pressure acting on the sensor by the feed material can be compensated by a sensor device, wherein the sensor device includes a guide through which the sensor can move in the discharge zone to compensate for the pressure acting on the sensor by the feed material. Typically, the feed material to be dehydrated is a non-Newtonian fluid. Surprisingly, it has now been found that the dielectric constant is related to pressure. To avoid misinterpretation of the dielectric constant, and thus misinterpretation of the filtrate content, the sensor is preferably part of the sensor device, wherein the feed pressure acting on the sensor can be compensated by the sensor device, thereby achieving a constant pressure (rated pressure) acting on the sensor. In this way, the pressure acting on the sensor can be kept constant, i.e., maintained at the rated pressure level, avoiding the influence of pressure deviation on the dielectric constant, and the filtrate content can be accurately measured by measuring the dielectric constant.

[0016] Surprisingly, the pressure acting on the sensor can be compensated for by moving the sensor in the discharge zone via a guide on the sensor assembly. This mobility allows the sensor to avoid pressure deviations from its rated pressure along the guide and to be positioned within the discharge zone according to the rated pressure.

[0017] In one advantageous embodiment, the sensor device guide allows the sensor to move in a plane, wherein the rotation axis of the press screw forms a normal to the plane. In another advantageous embodiment, for example, the distance between the sensor and the rotation axis of the press screw can be changed by moving the sensor along the guide.

[0018] Another advantageous feature of the screw press design is that a compensating force can be applied to the sensor via a guide, wherein this compensating force is opposite to the force generated by the pressure acting on the sensor. Advantageously, the compensating force is applied to the sensor via the guide, where the compensating force is in the opposite direction to the force corresponding to the feed pressure acting on the sensor. In a state of force equilibrium, that is, when the compensating force and the force from the feed pressure are equal, the sensor will not move. If there is a difference between the compensating force and the force from the feed pressure, the sensor will move along the guide in the direction of the larger force.

[0019] In an advantageous embodiment, a constant compensation force is applied to the sensor. In this case, the sensor can move within a range of travel via a guide of the sensor device, wherein the compensation force applied to the sensor is constant, at least in a portion of the range of travel.

[0020] A particularly advantageous embodiment features a sensor device including a spring, wherein the spring acts pneumatically, hydraulically, electrically, or magnetically, and a compensating force can be applied to the sensor via the spring. Advantageously, the compensating force can be applied using a spring that acts pneumatically, hydraulically, electrically, or magnetically. The pneumatic or hydraulic spring can be made using a cylinder that acts pneumatically or hydraulically. The compensating force acting on the sensor is achieved based on the pneumatic or hydraulic pressure within the cylinder.

[0021] A particular advantage is that a compensating force is applied to the sensor via a magnetic spring, where the compensating force remains constant. This magnetic spring allows for a constant force within a certain region, thus providing a constant force on the sensor at least within a portion of its travel range. Such magnetic springs are supplied as constant force springs for industrial use. Compared to pneumatic, hydraulic, or electric springs, magnetic springs have the advantage of not requiring auxiliary systems (such as pneumatic or hydraulic devices).

[0022] Another advantageous embodiment of the screw press features a sensor that, when the compensating force dominates, can move along the guide against the force generated by the pressure acting on the sensor; and when the force generated by the pressure acting on the sensor dominates, the sensor can move along the guide in the direction of the force generated by the pressure. Surprisingly, the force generated by the pressure acting on the sensor varies with the sensor's position in the discharge zone. Advantageously, the guide allows the sensor to be positioned, wherein the distance between the sensor and the rotating shaft is variable along the guide. For example, if the sensor moves along the guide against a smaller, constant compensating force by a larger force, the distance between the sensor and the rotating shaft changes. According to the invention, when the distance between the sensor and the rotating shaft changes, the generated force is close in magnitude to the constant compensating force. Conversely, if the sensor moves along the guide against a smaller force by a larger constant compensating force, the distance between the sensor and the rotating shaft also changes. According to the invention, as the distance between the sensor and the rotating shaft changes, the generated force again approaches the constant compensating force in magnitude. This self-adjustment results in the positioning of the sensor, compensating for the pressure acting on the sensor.

[0023] The present invention also aims to provide a method for separating filtrate from feed, and a simple, timely and accurate method for measuring filtrate content.

[0024] According to the invention, this is achieved by measuring the filtrate content of the feed in the discharge zone, wherein the feed flows toward and / or around a sensor used to measure the filtrate content. After compression of the feed in the dehydration zone, depressurization is performed in the discharge zone. Unexpectedly, measuring the filtrate content in the discharge zone, rather than in the dehydration zone, has advantages. According to the invention, the feed flows toward and / or around a sensor used to measure the filtrate content, wherein the sensor for measuring the filtrate content is based on a measurement of the dielectric constant of the feed.

[0025] According to the invention, the method is characterized in that the sensor device allows compensation for the pressure acting on the sensor by the feed, wherein the sensor moves in the discharge zone via a guide of the sensor device to compensate for the pressure acting on the sensor by the feed. Surprisingly, the pressure acting on the sensor varies with the sensor's positioning in the discharge zone. Therefore, compensation for the pressure acting on the sensor is achieved by the sensor avoiding pressures deviating from the rated pressure along the guide and positioning itself in the discharge zone according to the rated pressure. Positioning in this way achieves a constant pressure (rated pressure) acting on the sensor, thereby avoiding any effect of pressure on the dielectric constant.

[0026] A similarly advantageous embodiment of this method features a compensating force applied to the sensor via a guide, wherein this compensating force is opposite to the force generated by the pressure acting on the sensor. If a difference exists between the compensating force and the force from the feed pressure, the sensor will move along the guide in the direction of the larger force. As the sensor moves in the discharge zone, the pressure acting on the sensor also changes, wherein the sensor is positioned in the discharge zone according to the rated pressure, or according to the balance between the compensating force acting on the sensor and the force from the feed pressure.

[0027] An advantageous implementation of this method is characterized by applying a constant compensation force to the sensor.

[0028] A similarly advantageous embodiment of this method is characterized in that the compensating force is applied to the sensor via a spring in the sensor device, which acts pneumatically, hydraulically, electrically, or magnetically. A spring acting pneumatically, hydraulically, electrically, or magnetically advantageously allows a compensating force to be applied to the sensor within at least a portion of its travel range.

[0029] An advantageous embodiment of this method is characterized by applying a constant compensating force to the sensor via a magnetic spring. The magnetic spring is particularly advantageous because it allows a constant compensating force to be applied to the sensor within at least a portion of the guide, without relying on auxiliary systems (hydraulic devices, pneumatic devices, etc.).

[0030] An advantageous embodiment of this method is characterized by the fact that, when the compensating force dominates, the sensor can move along the guide against the direction of the force generated by the pressure acting on the sensor; and when the force generated by the pressure acting on the sensor dominates, the sensor can move along the guide in the direction of the force generated by the pressure. Advantageously, the guide allows the sensor to be positioned such that the distance between the sensor and the axis of rotation is variable along the guide. For example, if the sensor moves along the guide against a smaller constant compensating force by a larger force generated by the pressure, the magnitude of the resulting force will approach the constant compensating force. Conversely, if the sensor moves along the guide against a smaller force generated by the pressure by a larger constant compensating force, the resulting force will also approach the magnitude of the constant compensating force. This self-adjustment results in dynamic positioning of the sensor, compensating for the pressure acting on the sensor.

[0031] The use of a sensor for measuring the filtrate content of the feed in the screw press according to the invention is also advantageous, wherein the sensor is arranged in a sensor device, with the feed flowing toward and / or around the sensor. According to the invention, the pressure acting on the sensor is compensated during use, wherein the sensor for compensating the pressure acting on the sensor by the feed moves in the discharge zone via a guide of the sensor device. Attached Figure Description

[0032] The invention will now be described with reference to the examples in the accompanying drawings.

[0033] Figure 1 A screw press according to the present invention is shown.

[0034] Figure 2 A detailed view of the discharge zone of the screw press according to the present invention is shown.

[0035] Figure 3 An advantageous sensor device is shown.

[0036] Figure 4 The advantageous sensor device in the discharge zone of the screw press is shown.

[0037] Figure 5 The diagram shows an advantageous sensor device in the discharge zone of the screw press as viewed from the direction of the rotation axis. Detailed Implementation

[0038] Figure 1 A screw press according to the present invention is shown. The screw press 1 includes a feed zone 2, a dewatering zone 3, and a discharge zone 4. The dewatering zone 3 includes a pressing screw 6 rotatably arranged about a rotation axis 13 in a filter cylinder 5. For example, the pressing screw 6 may include a helix arranged on the axis. The space between the filter cylinder 5 and the pressing screw 6 narrows in the direction of the discharge zone 4. The feed enters the screw press 1 through the feed zone 2, where the filtrate is separated from the feed in the dewatering zone 3 by the filter cylinder 5. For this purpose, the filter cylinder 5 has an opening, for example, a perforation. Due to the rotation of the pressing screw 6 in the filter cylinder 5, the feed is fed from the feed zone 2 through the dewatering zone 3 into the discharge zone 4, where the feed is compressed in the dewatering zone 3 in a progressively stronger manner along the direction of the discharge zone 4. The feed enters the discharge zone 4 through an annular gap 16 formed between the filter cylinder 5 and the pressing screw 6, where the pressing screw 6 conveys the feed from the dewatering zone 3 to the counter-pressure unit 14. The backpressure unit 14 is constructed, for example, to be circular, wherein, viewed from the rotation direction 13, the annulus of the backpressure unit 14 can at least overlap with the gap 16 between the filter cartridge 5 and the pressing screw 6. The feed is radially deflected outward at the backpressure unit 14, wherein the feed also has a velocity component in the circumferential direction corresponding to the rotation of the pressing screw 6. Due to the deflection of the feed at the backpressure unit 14, a pressure reduction occurs in the discharge zone 4. Therefore, the backpressure unit 14 causes the feed to establish pressure in the dewatering zone 3, and a pressure reduction occurs when the feed is deflected at the backpressure unit 14. According to the invention, a sensor 7 (in...) Figure 1 The sensor device 9 (not shown) is arranged in the discharge zone 4, where the feed can flow toward and / or around the sensor 7.

[0039] Figure 2 The discharge zone of the screw press according to the invention is shown in detail. In the dewatering zone 3, the feed is compressed in the direction of the discharge zone 4, wherein the feed is guided in the gap area between the filter cylinder 5 and the pressing screw 6, which conveys the feed from the dewatering zone 3 to the counter-pressure unit 14 through the gap 16. In this case, the pressing screw 6 includes, for example, a shaft and a helical spiral. The feed enters the discharge zone 4 through the gap 16 formed between the filter cylinder 5 and the pressing screw 6. The feed is radially deflected outward between the wall 15 of the discharge zone 4 and the counter-pressure unit 14, wherein the feed also has a circumferential velocity component corresponding to the rotation of the pressing screw 6. By deflecting the feed at the counter-pressure unit 14, pressure reduction of the feed is achieved in the discharge zone 4.

[0040] Figure 3 An advantageous sensor device is shown. According to the invention, the sensor device 9 includes a sensor 7 for measuring the filtrate content in the feed. Advantageously, the measurement of the filtrate content is based on the measurement of the dielectric constant of the feed. Advantageously, the sensor device 9 also includes a guide 10 and a spring 12. Here, the sensor 7 is connected to the spring 12 via the guide 10, wherein the sensor 7 can be moved via the guide 10. The pressure exerted on the sensor 7 by the feed, or the force generated therefrom, is transmitted to the spring 12 via the guide 10, wherein the spring 12 transmits a compensating force to the guide 10. According to the principle of reaction (action = reaction), the compensating force of the spring 12 and the force generated by the feed on the guide 10 are in opposite directions. Therefore, if the compensating force is dominant, the sensor 7 will move via the guide 10 against the force generated by the pressure acting on the sensor 7, or if the force generated by the pressure acting on the sensor 7 is dominant, the sensor 7 will move along the guide 10 in the direction of the generated force. As long as the forces generated and the compensating force are balanced, the sensor will not move further. In this way, sensor device 9 allows compensation for the force generated by the feed action on sensor 7. Advantageously, spring 12 allows a constant compensating force to be applied to sensor 7. Since sensor 7 can move within the travel range 11 via a guide, a constant compensating force can be applied to sensor 7 by spring 12 at least in a portion of the travel range 11. Advantageously, spring 12 acts pneumatically, hydraulically, electrically, or magnetically. Such a magnetically acting spring 12 allows for a constant force to be applied within a region, or at least in a portion of the travel range 11, achieving a constant force on sensor 7. Such a magnetic spring 12 is provided, for example, as a constant force spring for industrial use, and its advantage over pneumatic, hydraulic, or electric springs is that no auxiliary system (e.g., pneumatic, hydraulic, etc.) is required.

[0041] Figure 4An advantageous sensor device for the discharge zone of a screw press is shown. Here, a pressing screw 6, rotatably arranged about a rotation axis 13, is schematically shown, extending from the dewatering zone 3 to the discharge zone 4. The material to be conveyed is fed into the discharge zone 4 through a gap 16 between the filter cartridge 5 (not shown) and the pressing screw 6, or through a gap 16 between the wall 15 of the discharge zone 4 and the pressing screw 6. The sensor device 9 includes a sensor 7, a guide 10, and a spring 12, wherein the guide 10 allows the sensor 7 to move within a stroke range 11. The feed can flow toward and / or around the sensor 7. In this process, the feed is guided from the dewatering zone 3 to the discharge zone 4 and deflected radially outward between the wall 15 of the discharge zone 4 and the back pressure unit 14, wherein the feed also has a circumferential velocity component corresponding to the rotation of the pressing screw 6. Advantageously, when viewed axially, i.e., along the direction of the rotation axis 13, the sensor 7 is located between the wall 15 of the discharge zone 4 and the back pressure unit 14, where the feed flows toward and / or around the sensor 7 after being deflected at the back pressure unit. As the sensor 7 moves within the travel range 11 of the guide 10 in the discharge zone 4, it can advantageously be positioned within and / or outside the gap 16 between the wall 15 of the discharge zone 4 and the pressing screw 6, where the feed can easily flow toward and / or around the sensor 7.

[0042] Figure 5 An advantageous sensor device is shown in view of the discharge zone of a screw press from the direction of the rotation axis. Here, the pressing screw 6 is schematically shown, extending into the discharge zone 4. The material to be conveyed is fed into the discharge zone 4 through the gap 16 between the filter cylinder 5 (not shown) and the pressing screw 6, or through the gap 16 between the wall 15 of the discharge zone 4 and the pressing screw 6. The feed flows toward and / or around the sensor 7. As the sensor 7 moves within the stroke range of the guide 10 in the discharge zone 4, the sensor 7 can advantageously be positioned within and / or outside the gap 16 between the wall 15 of the discharge zone 4 and the pressing screw 6, where the feed can easily flow toward and / or around the sensor 7.

[0043] This invention offers numerous advantages. It allows for the simple, timely, and accurate measurement of the filtrate content of raw materials processed by a screw press. By precisely measuring the filtrate content, the operation of the screw press can be adjusted to achieve a specific filtrate concentration, and commonly influencing parameters (screw speed, back pressure unit, etc.) can be automatically controlled to set the desired filtrate content. The precisely adjusted filtrate content after screw pressing is beneficial for subsequent processes because an optimal operating point can be established.

[0044] List of reference numerals

[0045] (1) Screw press

[0046] (2) Feeding area

[0047] (3) Dehydration zone

[0048] (4) Discharge area

[0049] (5) Filter cartridge

[0050] (6) Press screw

[0051] (7) Sensor

[0052] (8) Axial

[0053] (9) Sensor device

[0054] (10) Guide

[0055] (11) Travel range

[0056] (12) Spring

[0057] (13) Rotation axis

[0058] (14) Back pressure unit

[0059] (15)Wall

[0060] (16) Gap

Claims

1. A screw press (1) for separating filtrate from a feed, the screw press comprising a feed zone (2), a dehydration zone (3), and a discharge zone (4), wherein, The feed can be fed into the screw press (1) through the feed zone (2). The dewatering zone (3) includes a pressing screw (6) arranged to rotate around a rotation axis (13) in a filter cylinder (5). Through the rotation of the pressing screw (6), the feed can be sent from the feed zone (2) to the discharge zone (4) via the dewatering zone (3). In the dewatering zone (3), the feed is guided between the filter cylinder (5) and the pressing screw (6), and the filtrate can be separated through the filter cylinder (5) and has a measuring function for filtrate. The sensor device (9) of the liquid content sensor (7) is arranged in the discharge zone (4), wherein the feed can flow toward and / or around the sensor (7), characterized in that the sensor device (9) can compensate for the pressure exerted on the sensor (7) by the feed, wherein the sensor device (9) includes a guide (10), and the sensor (7) can move in the discharge zone (4) by the guide (10) to compensate for the pressure exerted on the sensor (7) by the feed.

2. The screw press (1) according to claim 1, characterized in that, The guide (10) can apply a compensating force to the sensor (7), wherein the compensating force is opposite to the force generated by the pressure acting on the sensor (7).

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

4. The screw press (1) according to claim 2 or 3, characterized in that, The sensor device (9) includes a spring (12), wherein the spring (12) acts pneumatically, hydraulically, electrically or magnetically, and a compensating force can be applied to the sensor (7) through the spring (12).

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

6. The screw press (1) according to claim 2 or 3, characterized in that, When the compensating force is dominant, the sensor (7) can move along the guide (10) against the force generated by the pressure acting on the sensor (7), and when the force generated by the pressure acting on the sensor (7) is dominant, the sensor (7) can move along the guide (10) in the direction of the force generated by the pressure.

7. A method for separating filtrate from a feed, wherein the feed is fed through a feed zone (2) into a screw press (1) according to any one of claims 1 to 6, and the filtrate is separated from the feed in a dehydration zone (3) between a pressing screw (6) rotating about a rotating shaft (13) and a filter cartridge (5), wherein, The feed is compressed between the feed zone (2) and the discharge zone (4), the filtrate is discharged through the filter cartridge (5), and the filtrate content of the feed is measured in the discharge zone (4), wherein the feed flows toward and / or around the sensor (7) used to measure the filtrate content, characterized in that the sensor device (9) allows compensation for the pressure exerted on the sensor (7) by the feed, and the sensor (7) moves in the discharge zone (4) by the guide (10) of the sensor device (9) to compensate for the pressure exerted on the sensor (7) by the feed.

8. The method according to claim 7, characterized in that, A compensating force can be applied to the sensor (7) via the guide (10), wherein the compensating force is opposite to the force generated by the pressure acting on the sensor (7).

9. The method according to claim 8, characterized in that, It can apply a constant compensation force to the sensor (7).

10. The method according to claim 8 or 9, characterized in that, The compensating force is applied to the sensor (7) through the spring (12) of the sensor device (9), which acts in a pneumatic, hydraulic, electric or magnetic manner.

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

12. The method according to claim 8 or 9, characterized in that, When the compensating force is dominant, the sensor (7) can move along the guide (10) against the force generated by the pressure acting on the sensor (7), and when the force generated by the pressure acting on the sensor (7) is dominant, the sensor (7) can move along the guide (10) in the direction of the force generated by the pressure.

13. An application of a sensor (7) for measuring the filtrate content of the feed in a screw press (1) according to any one of claims 1 to 6, wherein, The sensor (7) is arranged in the sensor device (9), and the feed flows toward and / or around the sensor (7).

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