Method for determining the extent of contamination inside a drum of a separator, and separator

Abstract

The invention relates to a method for determining the extent of contamination inside a drum (2) of a separator (1), said method comprising at least the following steps: A) providing a value for a maximum internal volume of the drum (2); B) metrologically determining the currently available free drum volume of the drum (2); C) comparing the values from steps A and B and determining the extent of contamination inside the drum (2) and / or generating a control command; wherein the method comprising steps A-C is carried out while the separator is rotating. The invention also relates to a separator (1).

Description

[0001] The present invention relates to a method for determining the extent of soiling or adhesion within a drum of a separator.

[0002] When operating a disc centrifuge, deposits can form inside the drum. These deposits can occur in both the sludge chamber and the disc stack. This is a normal process. The deposits may be unevenly distributed within the drum, leading to vibrations that can be monitored using measuring instruments.

[0003] However, they can also be distributed very evenly within the drum. The difficulty then lies in the fact that these deposits cannot be easily seen or detected from the outside. To determine the amount of deposits inside the drum, it must be opened, which is a considerable undertaking.

[0004] In both cases, the deposits reduce the free volume in the drum, which can lead to less efficient separation or clarification in the separator, or necessitate shortening the emptying intervals for ejecting the separated solid or sludge phase. In the context of this invention, emptying refers to the opening of discharge valves in the drum wall, allowing parts of the drum contents (partial emptying) or even the entire drum contents (full emptying) to be ejected while the separator is operating, i.e., while the drum is rotating. Separators of this type are referred to as self-emptying separators.

[0005] For separators, the maintenance interval must be correspondingly short to remove deposits that cannot be removed by emptying (e.g., deposits in the disc stack). This manual cleaning is time-consuming and reduces the separator's availability. Therefore, it must be performed early enough to prevent the drum from becoming too heavily soiled. For safety reasons, the maintenance interval is deliberately kept short, which is, however, economically inefficient.

[0006] It is desirable for the drum interior to be continuously or at least regularly inspected for deposits. This ensures the separator's process function, improves operational reliability, and increases availability.

[0007] Accumulations of deposits in the drum can be dangerous for the operation of the centrifuge if they cause an imbalance of the drum.

[0008] Currently, there is no monitoring of the free volume in the drum. Only a few centrifuges are capable of detecting a completely full solids chamber. Therefore, it is not yet possible to take early and appropriate measures when the free drum volume is reduced by deposits.

[0009] WO 2018 / 177 711 A1 discloses a method for operating a separator by determining a volume balance VAP = VKP + VF, which shifts when clumping, blockages or adhesions are present in the disc pack. This is done by means of a flow measurement.

[0010] This document does not, however, disclose how the free volume of a drum can be determined. The free volume of the drum is not determined because no suitable sensor is disclosed that would indicate when the drum is completely full. Measuring the inlet flow rate is insufficient (page 7, last section) because there is no criterion for when the drum is completely full and the measurement should therefore be stopped.

[0011] German patent DE 42 04 805 A1 discloses a method for determining the free volume of a drum. For this purpose, the drum is stopped and its contents are drained into a measuring vessel. The patent does not disclose the application of the method to a disc separator. Disc stacks are used to increase the effective clarification area. However, a volume determination with the drum stationary is distorted by the additional discs in the drum, since liquid remains on the stationary disc stack in the form of droplets. This volume of the droplets remaining in the drum affects the accuracy of the determination of the free drum volume, as the droplets are incorrectly considered as deposits in the calculation. In this case, Vdeposit = Vsolid + Vdroplets.

[0012] The amount of adhering liquid is also not reproducible, as this depends heavily on the degree of soiling of the plates.

[0013] Furthermore, the present invention relates to a separator commonly referred to as a self-emptying separator. This means that emptying occurs at a high G-force. The adhering solids are deposits in the drum that are not removed by a solids discharge mechanism, e.g., nozzles.

[0014] WO 2009 / 010 630 A1 only discloses the determination and metering of the volume of supplied displacement water. Although there is a pressure sensor in the drum's outlet, the use of this sensor to determine the drum volume is not disclosed in this context.

[0015] Detecting a dirty drum, including a platter pack that is at least partially dirty, is currently not possible or at least not precise.

[0016] The state of the art only includes measures such as additional emptying when vibrations of the drum occur or when the turbidity value of the clear phase increases (in the clarifier).

[0017] Other methods specify emptying intervals that are fixed and can only be shortened, not lengthened. The free drum volume is not monitored.

[0018] EP 2170520 discloses a system for optimizing the quantity of a displacement fluid in a separator. This displacement fluid is intended to displace the valuable phase from the drum before emptying the sludge phase.

[0019] For this to work, the displacing liquid must be heavier than the valuable phase, but lighter than the sludge phase. Even if the emptying is imprecise – i.e., too large – product loss of the valuable phase can be minimized, since it has been displaced from the drum.

[0020] The amount of displaced fluid, e.g., water, is adjusted based on its pressure. Specifically, the volumetric flow rate of the introduced water is measured using a Venturi nozzle. Thus, the volume is calculated from pressure differences and the properties of the water, although the volume of the water itself is not directly determined.

[0021] Based on the aforementioned problem, the object of the present invention is to provide a method for determining the extent of contamination, which can be carried out without manual disassembly of the separator.

[0022] The present invention solves the aforementioned problem by means of a method having the features of claim 1.

[0023] A method according to the invention for determining the extent of contamination within a drum of a centrifugal separator comprises at least the following steps: A. Provision of a value for the maximum internal volume of the drum; this value can be the so-called technical drum internal volume, which represents a theoretically calculated, design-related value. Alternatively, the value can also be determined after maintenance, including manual cleaning of the drum interior, by subsequent filling as a reference value established by measurement. B. Measurement-based determination of the currently available free drum volume; the currently available free drum volume represents the drum volume after one or more production cycles in which deposits have accumulated inside the drum. C. Comparison of the values ​​from steps A and B and determination of the extent of contamination inside the drum and / or generation of a control command.

[0024] In step C, the level of contamination is determined by comparing the values ​​provided in steps A and B. The extent of the contamination can then be displayed to the user. Alternatively, a control command, such as stopping the separator or initiating intensive cleaning, can be generated to reduce the level of contamination.

[0025] This also shows that, for carrying out the inventive method for determining the extent of contamination, the separator does not need to be stopped, but can be operated continuously, i.e., with the drum rotating. Interruptions to the drum's rotation are not required. This applies to steps AC of the method, but preferably also to all further variants of the method described below.

[0026] Particularly in light of DE 42 04 805 A1, the separator does not need to be brought to a standstill. The shutdown and start-up times of the separator are therefore completely eliminated. As already explained with regard to DE 42 04 805 A1, measuring in the rotating system avoids the disadvantage of an undefined amount of residual liquid remaining in the stationary drum when measuring the outflowing liquid.

[0027] Determining the extent of pollution can either include a specific value or simply a comparison with a limit value for a maximum acceptable level of pollution, at which no action needs to be taken.

[0028] The aforementioned method allows for an extension of the maintenance periods and the cycles of manual emptying of a centrifugal separator.

[0029] This increases the separator's availability, as opening and manually cleaning the drum is only necessary when it has accumulated a significant amount of deposits. Preventive cleaning is no longer required.

[0030] If the amount of deposits in the drum and thus the reduced free volume is known, the emptying intervals can be dynamically adjusted, since, for example, the sludge chamber volume can be calculated according to the deposits.

[0031] When we refer to the emptying interval here, we always mean manual emptying by opening the separator, a manually started function for what would otherwise be automatic emptying, or an automatically started emptying step. Emptying can also be understood as partial or total emptying.

[0032] Fewer emptying operations also mean reduced disposal costs for the solids and fewer losses during the displacement phase and, if applicable, the valuable phase. Another way to reduce deposits is to adjust the emptying method. A single emptying operation is performed by default, but this can be performed twice, or twice with an intermediate rinse, depending on the degree of deposits. These measures also improve deposit reduction. This, too, can be configured by generating the aforementioned control command.

[0033] Further advantageous embodiments of the method according to the invention are the subject of the dependent claims.

[0034] The measurement of the currently available free drum volume can preferably be carried out by the following steps: I. Providing a self-emptying separator; II. Filling the drum and determining the volume of liquid required to fill the drum, which corresponds to the currently available free drum volume.

[0035] Unlike a manually emptied separator, a self-emptying separator may still contain deposits or adhering material inside the drum, reducing the maximum internal drum volume to the currently available free drum volume. Filling is preferably carried out by completely filling the drum up to a line at the product outlet for the heavier liquid phase. This ensures that the entire drum, as well as the rotatable and non-rotatable parts of the inlet and outlet systems within the drum volume, are filled. This allows for a comprehensive assessment of the extent of deposits or contamination.

[0036] The filling status of the drum can then be advantageously measured using a sensor on the separator. Preferably, at least one or more pressure sensors and / or one or more limit switches are suitable for this purpose, e.g., capacitive limit switches or conductivity limit switches, which detect when a certain fill level is reached by a change in conductivity. Other limit switches are based on ultrasound. Since the speed of sound in water is significantly higher than in air, a change in the medium can be detected at the position of the limit switch. Optical limit switches are also conceivable.

[0037] The pressure sensor or limit switch can preferably be arranged at the outlet of a liquid phase, in particular at the outlet of the heavier liquid phase, of the separator.

[0038] Before determining the free drum internal volume, an automatic cleaning sequence, e.g. a CIP and / or SIP cleaning, can optionally be initiated without disassembling the separator.

[0039] Furthermore, it is advantageous, especially for the use of a pressure sensor, if the separator at the outlet of the liquid phase, and downstream of the sensor in terms of flow, has a valve which is closed during the filling of the drum and which is opened when the sensor detects that the drum is filled.

[0040] The liquid introduced to fill the drum is preferably displacement water, wherein a first displacement water inlet of the separator for filling the drum and a product inlet of the separator open into a common inlet pipe. The inlet pipe can be arranged parallel and, in particular, concentrically to the axis of rotation of the separator.

[0041] A control water inlet for actuating a solids emptying of the separator may also be provided.

[0042] The determination of the volume required to fill the drum is carried out by a measuring device to determine an inlet volume and in particular by a flow meter.

[0043] This measuring device is preferably located in or on the displacement water inlet.

[0044] The control signal generated in step C is preferably used to initiate an output, e.g., a warning message, by an output unit. This can be a light signal (alarm lamp), a display output, or an acoustic signal.

[0045] Alternatively or additionally, the control signal can trigger an immediate action on the separator's operation, in particular an emergency stop or an adjustment of the operating program, e.g., the cleaning sequence. Adjusting the duration or frequency of partial emptying of the drum is also possible.

[0046] As already explained, a value for the maximum internal volume of the drum can be provided by a reference measurement when the drum's condition is known, particularly after manual emptying and / or maintenance.

[0047] Alternatively or additionally, the provision of a value for a maximum internal volume of the drum can be done by providing a value for a technical drum volume as a value for the design-related maximum internal volume of the drum.

[0048] Steps I and II of the aforementioned procedure can be repeated several times, but at least twice, for reasons of redundancy.

[0049] Further advantages, features, and details of the invention will become apparent from the following description, in which an embodiment of the invention is explained in more detail with reference to the accompanying drawings. Those skilled in the art will expediently consider the features disclosed in the drawing, the description, and the claims individually and combine them into meaningful further combinations. In particular, there are numerous possibilities for modifying and developing these features within the scope of the present invention. The drawings show: Fig. 1 a perspective view of a separator; Fig. 2 a sectional view of the separator for carrying out the method according to the invention; and Fig. 3 a schematic representation of the process sequence according to the invention.

[0050] The in theFig. 1 and 2 The illustrated embodiment shows a separator 1 with a rotatably mounted drum 2, which has a technical drum volume. The technical drum volume is a theoretical value resulting from the design specifications of the separator 1.

[0051] This technical drum volume is determined by the dimensions of the internal volume 12 of the drum 2, as well as by the structures arranged within the internal volume 12, such as the dimensions and number of plates in a plate stack 3 and their spacing. Furthermore, the size of the technical drum volume is influenced by, among other things, the design of one or more inlet areas 4, distributor areas 5, separating plates 6, peeling chambers 7, peeling discs 8, discharge areas 9, and the like.

[0052] The aforementioned list is by no means exhaustive. Depending on the design, individual components listed above may be omitted or replaced by other components without altering the overall principle described below.

[0053] The free drum volume is therefore a theoretically calculated value, without any contamination within drum 2 or other types of deposits.

[0054] The separator 1 also has a product inlet 10 and a displacement water inlet 11, which lead into a common inlet pipe 13, which in turn forms at least part of an inlet area 4 in the inner volume 12 of the drum 2.

[0055] Furthermore, separator 1 has a first outlet 14 for a light liquid phase, a second outlet 15 for a heavy liquid phase, and a solids outlet 16 as part of a solids discharge system. Separator 1 is clearly designed as a three-phase separator.

[0056] However, the following principle can also be applied to a two-phase separator, e.g. a clarification separator.

[0057] The in Fig. 1 and 2 The separator 1 shown has a pressure sensor 23 and 24 at the first and second outlets 14 and 15 of the liquid phases, respectively. These pressure sensors 23 and 24 typically enable process monitoring during the separation of a light and a heavy phase, such as the purification of water contained in oil.

[0058] However, within the scope of the present invention, it is also possible to determine a so-called control volume using the aforementioned sensors.

[0059] Furthermore, the separator 1 has a control water inlet 22, which is intended for controlling the solids discharge or emptying, e.g., by hydraulically actuated linear displacement of a piston valve as part of a solids emptying system. A water inlet 28 of the separator 1 branches into the two aforementioned water inlets 11 and 22. As already mentioned, the inlets 11 and 22 can also be connected to the separator separately. Therefore, there is no limitation to the configuration described.

[0060] The supply of the amount of displacement water to the first displacement water inlet 11 or to the second displacement water inlet 22 is controlled by a valve arrangement 29, in Fig. 2Specifically, it is controlled by two valves 17 and 18. These can preferably be solenoid valves. Of course, the two valves 17 and 18 can also be combined in a multi-way valve, so that the valve arrangement 29 can also comprise only one valve.

[0061] The quantity and / or volume of displacement water supplied through the displacement water inlet 11 is determined by a suitable measuring device 19, preferably a flow meter. This device can be arranged, in particular, in the displacement water inlet 11.

[0062] The second process 15 for the heavy phase preferably also has a valve 20, preferably a solenoid valve.

[0063] The measured values ​​determined by the measuring device 19, as well as the measured values ​​of the pressure sensors 23 or 24, can be transmitted to a control and / or evaluation unit 21, which then controls the valves 17 and 18 for the control and displacement water and the valve 20 for the heavy phase.

[0064] The aim of measuring the flow rate of displaced water and the associated valve control is to determine a control volume, which defines the volume currently available in the drum.

[0065] A measurement taken from a so-called control measurement yields this control volume and can then be compared with a target value representing the actual free volume (e.g., calculated from the geometry or determined through experiments). The free drum volume (technical drum volume) depends on the machine type (drum size, number and spacing of the plates, etc.) and is stored in the machine control system. This comparison is then significant for determining the degree of contamination of the drum.

[0066] Determining this control volume requires several steps, as described in Fig. 3 As shown, in a first step 101, the product feed into drum 2 is interrupted.

[0067] Then, in a second step, the drum is completely emptied. This emptying can be done, for example, through the solids discharge openings, which are then closed again.

[0068] Then, in step 103, valve 18 is opened and displaced water is fed into drum 2 via the displacement water inlet 11. The volume of introduced displaced water is measured by the measuring device 19 until the drum is completely filled.

[0069] The complete filling of drum 2 can be determined in step 104 by the pressure sensor 24 in the outlet 15 of the heavy liquid phase. The additional valve 20 in said outlet 15 of the heavy liquid phase is closed at least immediately before the drum is filled with displacement water. When the drum is completely full, this pressure sensor 24 detects the presence of the heavy phase, in this case the displacement water. In a clarifier separator, the pressure sensor would be located in the outlet of the liquid phase.

[0070] If necessary, the drum volume can be measured multiple times to compensate for measurement errors using statistical methods. The aforementioned measurements, or one of them, are performed while the separator is running, i.e., with the drum rotating.

[0071] As an alternative to pressure measurement, a complete fill can also be detected by a variety of other sensors. Conductivity measurement is a suitable option here, as it can detect a change in the conductivity of the medium at a given fill level and thus indicate the fill state. Particularly preferred within the scope of the present invention are the use of so-called limit switches, which can also be based on different physical measuring principles. Capacitive limit switches, vibronic limit switches, and the like are known examples.

[0072] It is also possible to use two different measurement methods, e.g. in series, to compensate for measurement errors.

[0073] Furthermore, the accuracy of the aforementioned measurements of the volume of the displaced water can be further improved by taking the temperature of the displaced water into account.

[0074] In a fifth step 105, a comparison of the control volume with the technical drum volume as a theoretical maximum value can be carried out.

[0075] If the deviation between the currently measured free volume of the drum or the determined control volume exceeds a certain limit, which can be preset in the control system, the control system can either suggest necessary measures or automatically initiate appropriate steps. A comparative value can also be determined taking into account the theoretical technical drum volume, so that the degree of contamination is more easily quantifiable for the user.

[0076] If the determined value of the control volume or a value derived from it exceeds a predetermined limit, adjustments can be made to the operation of the drum in the production cycle.

[0077] Then, in a sixth step (106), the drum 2 is emptied of the displaced water. Specifically, the emptying takes place in Fig. 2via the solids outlet 16 or, if the separator is to be refilled with product immediately, also via a diversion pipe 25, which leads into the solids collection area 26 of a separator hood 27.

[0078] Contamination can therefore be detected by determining the difference between the technical drum volume and the control volume.

[0079] Control volume or free drum volume are used synonymously in the context of this application.

[0080] If this difference exceeds a certain value (warning value), the control system can react accordingly in a seventh step (107) and generate a control signal. This control signal can initiate an output, such as a warning, or trigger an immediate action on the separator's operation. Various warning threshold levels are conceivable, at which messages or warnings are issued, or even the machine is stopped.

[0081] These measures can include, for example, repeated emptying of the sludge phase, reduction of the feed rate, and / or shutdown of the centrifuge. This can prevent separator malfunctions, damage to the separator, or insufficient centrifugal separation of the product.

[0082] Regular or irregular reference measurements provide a reference volume and can be carried out, for example, during maintenance (e.g., maintenance interval 4000 h) or at another time.

[0083] This reference measurement can also be compared or calculated against the control volumes, from which a degree of contamination and, in particular, a temporal trend towards the accumulation of a degree of contamination can be derived. Furthermore, external influences such as temperature or product properties of the respective products being processed can be included in the determination of the free drum volume.

[0084] After maintenance, for example, it can be assumed that the separator drum has been completely cleaned. A measurement of the drum volume after maintenance (reference volume) can also be evaluated.

[0085] If the difference between the technical drum volume and the reference volume exceeds a certain value, it can be concluded, for example, that the cleaning is insufficient.

[0086] If this difference is negative, other errors can be inferred. For example, fewer plates than intended. During further operation of the separator, the difference between the reference volume and the control volume can also be used to determine the degree of contamination.

[0087] Combinations (average or similar) of the two measurements (technical drum volume minus control volume and reference volume minus control volume) are also conceivable.

[0088] It can therefore be said that the measurement allows for both process-related (contamination) and mechanical conclusions.

[0089] Possible and preferred measuring devices for determining the quantity or volume of the displaced water are preferably flow meters within the scope of the present invention.

[0090] Suitable measuring devices, especially for determining the volume of displaced water, are Impeller flow meters, swashplate flow meters (water meters), inductive flow meters (IDM), mass flow meters such as Coriolis flow meters (advantageous because they measure quite independently of air inclusions in the liquid), eddy current flow meters (measuring principle: Kármán vortex street) or vortex measurement, as well as caloric flow meters; flow meters based on the sound transit-time difference method, often referred to as ultrasonic flow meters.

[0091] With mass flow meters, for example, it is possible to calculate the volume from the mass if the density of the measuring medium is known.

[0092] If the separator is used in a continuous processing process of a product, a device according to the invention can comprise the separator and a buffer tank which collects the volume of the product to be processed during the determination of the degree of contamination or the free drum volume.

[0093] Alternatively, two identical separators can be operated in parallel next to each other, which are controlled in such a way that only one determination of the degree of contamination is ever carried out at a time.

[0094] A particularly noteworthy aspect of the present invention is the determination of the free drum volume of a separator between or during production.

[0095] This increases plant availability, as no unnecessary intermediate cleaning is required. This also reduces operating costs. Reference sign

[0096] 1 Separator 2 Drum 3 Disc Pack 4 Inlet Area 5 Distributor Area 6 Separating Disc 7 Peeling Chamber 8 Peeling Disc 9 Discharge Area 10 Product Inlet 11 First Displacement Water Inlet 12 Internal Volume 13 Inlet Pipe 14 First Outlet 15 Second Outlet 16 Solids Outlet 17 Valve 18 Valve 19 Measuring Device 20 Valve 21 Control and / or Evaluation Unit 22 Control Water Inlet 23 Pressure Sensor 24 Pressure Sensor 25 Diversion Pipe 26 Solids Collection Area 27 Separator Hood 28 Water Inlet 29 Valve Arrangement 101 First Step (Interruption) 102 Second Step (Emptying) 103 Third Step (Valve - Displacement Water - Open) 104 Fourth Step (Complete Filling) 105 Fifth Step (Comparison) 106 sixth step (emptying of the displacement water) 107 seventh step (generation of a control signal)

Claims

1. A method for determining the extent of contamination within a drum (2) of a separator (1), comprising the following steps: A Providing a value for the maximum internal volume of the drum (2); B Measuring the currently available free volume of the drum (2); C Comparing the values from steps A and B and determining the extent of contamination within the drum (2) and / or generating a control command, characterized by the method comprising steps A to C being performed while the separator is in operation.

2. The method according to claim 1, characterized in that the measurement of the currently available free drum volume is performed in the following steps: I. Providing a self-emptying separator (1), II. Filling the drum (2) and determining the volume of liquid required to fill the drum (2), which corresponds to the currently available free drum volume of the drum (2).

3. Method according to claim 2, characterized in that the filling status of the drum (2) is measured using a sensor of the separator.

4. A method according to any of the preceding claims, characterized in that the sensor is a pressure sensor (23, 24) and / or a limit switch, which is preferably arranged at the outlet of a liquid phase (14, 15), in particular at the outlet (15) of the heavier liquid phase, of the separator (1).

5. A method according to any of the preceding claims, characterized in that the liquid introduced to fill the drum is displacement water, wherein a displacement water inlet (11) of the separator (1) for filling the drum (2) and a product inlet (10) of the separator (1) open into a common inlet pipe (13).

6. A method according to any of the preceding claims, characterized in that the volume required to fill the drum (2) is determined by a measuring device (19) for determining an inlet volume, in particular by a flow meter.

7. A method according to any of the preceding claims, characterized in that the measuring device is arranged in or on the displacement water inlet (11).

8. A method according to any of the preceding claims, characterized in that the generated control signal initiates an output at an output unit, preferably a warning, and / or performs an immediate action on the operation of the separator, in particular initiates an emptying and / or an emergency stop.

9. A method according to any of the preceding claims, characterized in that the provision of a value for a maximum internal volume of the drum (2) is performed by a reference measurement under known conditions of the drum, in particular after a manual emptying and / or maintenance of the separator (1).

10. A method according to any of the preceding claims, characterized in that the provision of a value for a maximum internal volume of the drum (2) is performed by providing a value for a technical drum volume as the value for the structurally determined maximum internal volume of the drum (2).

11. A method according to any of the preceding claims, characterized in that steps I and II are repeated at least twice.

12. A method according to any of the preceding claims, characterized in that at least steps B and C, preferably the entire method, are carried out without disassembling the separator, in particular the drum.

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