Method for controlling or regulating the operation of a centrifuge

Abstract

A method for controlling or regulating the operation of a centrifuge, wherein the centrifuge is a separator with a rotor rotatable about a vertical axis of rotation, which has a rotatable drum (1) in which a separation agent such as a separating plate assembly is arranged, in particular for clarifying an incoming free-flowing suspension into a liquid phase and a solid phase or for separating an incoming free-flowing suspension into different liquid phases and optionally a solid phase in the drum (1), wherein the separated liquid and / or solid phases are discharged from the drum, and wherein, when controlling or regulating the operation of the centrifuge with a control or regulating device (9), the rotational speed of the rotor is adjusted as a function of at least one existing and / or to be maintained operating parameter of the centrifugal processing.

Description

[0001] The invention relates to a method for controlling or regulating the operation of a centrifuge according to the preamble of claim 1.

[0002] Separators are centrifuges used for the mechanical separation of liquid-liquid, liquid-solid, and / or liquid-liquid-solid mixtures. An introduction is provided by Prof. Werner H. Stahl in "INDUSTRIE-ZENTRIFUGEN, Band II, Chap. 5 und 6, 1. Ausgabe 2004".

[0003] The invention aims to further optimize the control and / or regulation of the operation of such centrifuges designed as separators.

[0004] The invention achieves this goal through the subject matter of claim 1.

[0005] A method is thus created for controlling or regulating the operation of a centrifuge, wherein the centrifuge is a separator with a rotor rotatable about a vertical axis of rotation, which has a rotatable drum in which a separation agent such as a separating plate assembly is arranged during continuous centrifugal processing of a product, in particular during the clarification of an incoming free-flowing suspension into a liquid phase and a solid phase or during the separation of an incoming free-flowing suspension into different liquid phases and optionally a solid phase in the drum, wherein the separated liquid and / or solid phases are discharged from the drum, in which the rotational speed of the rotor is set as a function of at least one existing and / or to be maintained operating parameter of the centrifugal processing by means of a control or regulating device.

[0006] In this way, the control and / or regulation of the operation of such separators is further optimized. This makes it possible to improve the operation of the centrifuge. According to embodiments of the invention, by setting suitable speeds—in particular, by setting lower speeds than the maximum adjustable speed—energy consumption can be reduced. According to these embodiments of the invention, this results in, in particular, an increase in the efficiency of the centrifugal separation process and / or a reduction in operating costs.

[0007] The invention is particularly advantageous for use in centrifuges with rotors whose drive comprises at least one electric motor or several electric motors, which is / are controlled using suitable power electronics, such as a frequency converter, and which is / are connected to the control or regulation device of the centrifuge.

[0008] According to an advantageous embodiment, the method according to claim 1 for controlling the operation of the centrifuge is designed such that at least one operating parameter of the centrifuge is to be maintained when controlling the operation of the centrifuge; with at least the following steps: a) at least one operating parameter to be maintained during the centrifugal processing of the suspension is defined, b) in particular, a rotor speed is determined from pre-stored values ​​and / or on the basis of a model using a control device, with which it is possible to maintain the operating parameter(s) exactly or within specified limits, and c) the rotor speed determined in step b) is set using the control device.

[0009] And according to another advantageous embodiment, the method according to claim 1 for controlling the operation of the centrifuge is designed such that an operating parameter of the centrifuge is to be maintained during the control of the operation of the centrifuge; with at least the following steps: a) at least one operating parameter to be maintained during the centrifugal processing of the product is defined and this operating parameter or a related operating parameter is determined during operation, i.e. during rotation of the centrifuge rotor, in particular measured with a sensor device, b) the data determined in step a) are compared with target data using the control device, whereby at least one rotational speed of the rotor is determined as a manipulated variable using the control device based on this comparison, and c) the rotational speed determined in step b) is set using the control device.

[0010] According to the invention, at least the rotational speed of the drum is defined and set by means of a suitable control or regulation unit and depending on operating parameters or specifications that the operator of the centrifuge can define and determine, so that it becomes optimally possible to respond to process engineering and, if applicable, commercial requirements.

[0011] Following further training, it may then be provided that in step a) several operating parameters to be observed during the centrifugal processing of the product are defined and, if necessary, determined, and that these are jointly included in the determination and setting of steps b) and c).

[0012] The invention can be implemented in practice in a variety of ways.

[0013] Thus, the operating parameter of step a) can be set to determine the clarification surface load, and then the inflow rate of the incoming suspension can be determined, and depending on the inflow rate in step b), a rotational speed of the rotor can be determined, and in step c) the rotational speed of the rotor can be adjusted so that the clarification surface load remains constant.

[0014] According to this advantageous variant, the rotational speed is adjusted depending on the inflow volume, which can be determined, for example, by measuring the inflow flow rate or by other means, so that the treatment surface loading remains constant (this applies under constant product conditions in the inflow). This is because the following applies: Treatment surface loading = Inflow volume / equivalent treatment area = constant. For example, with half the inflow volume, this means: 0.5 inflow volume / 0.5 equivalent treatment area = constant. Since the equivalent treatment area is proportional to n 2< (Σ T ∼ n 2< * D 4< so), the rotational speed must be reduced to 0.707 * n (half the inflow → rotational speed * 0.707). Any resulting reduction in energy consumption can be determined using the formulas given below under i) and ii).

[0015] According to another advantageous embodiment of the invention, the operating parameter of step a) is a desired separation efficiency, and the turbidity of a clarified product phase is determined. The data determined in step a) are then forwarded to the control device, which compares the measured data with target data. Based on this comparison, the control device determines the rotor speed in step b) as the manipulated variable. In step c), this rotor speed is set using the control device. The turbidity of the clarified phase serves as an indicator for the separation efficiency, and its value can be determined using a turbidity meter. If the separation efficiency is too high, the drum speed can be reduced until a predetermined limit for the separation efficiency is reached. Any resulting...The associated reduction in energy consumption can be determined using the formulas shown below under i) and ii).

[0016] According to another advantageous embodiment of the invention, the operating parameter of step a) is a desired separation efficiency, and in step b) a particle distribution in the incoming product is determined. Depending on the determined particle distribution, the rotor speed is adjusted to achieve the desired separation efficiency precisely or within predetermined limits. A predefined relationship between particle distribution and drum speed can be used to determine which drum speed is required for which particle distribution. The particle distribution in the incoming product can be detected online by a suitable sensor. The corresponding measured value is assigned to a setpoint speed for the separator drum in a suitable control unit. Using suitable power electronics, the drum speed is adjusted based on this setpoint speed.The energy consumption of the drum drive can be optimized via this speed control "particle distribution / drum speed".

[0017] It is also possible that, in a variant of the invention, the operating parameter to be defined is the shear sensitivity of the incoming product, and that the rotor speed is adjusted depending on the shear sensitivity of the incoming product. Certain products, such as plant or animal cells, are sensitive to shear. This occurs in centrifuges particularly during product acceleration (e.g., transition from the feed line to the disc stack) and during discharge (e.g., transition of the solid from the discharge openings of the drum into the solids catcher). Reducing the drum speed reduces the shear stress on the product. The appropriate speed for this can be determined, for example, by a predefined "product / drum speed" mapping, specifying which drum speed is required for which product.

[0018] It is also possible to implement a variant of the invention in which the operating parameter is a fill level of a feed tank associated with the centrifuge, from which the suspension to be processed is fed to the centrifuge in the feed, and in which a rotational speed of the rotor is determined and set depending on the fill level and, if applicable, one or more operating parameters.

[0019] For example, a predefined assignment of "settling time and fill level in the tank" can determine the drum speed at which the separation process is started and how the drum speed can be reduced as the fill level and solids content decrease.

[0020] According to another version of the invention, it is also conceivable that the operating parameter is the energy consumption of the centrifuge drive, which is determined during centrifugal processing, and that the rotational speed is set so that a predetermined energy consumption is not exceeded. The current electricity price per kWh can also be used as a parameter for setting the rotor speed, either with or exclusively.

[0021] Overall, the invention makes it possible, through clever control and / or regulation strategies, to improve the operation of the centrifuge by appropriately adjusting the rotational speed depending on one or more definable operating parameters. In this way, the energy consumption of the separators can be optimally controlled or regulated according to various embodiments. This, in turn, leads to an increase in the efficiency of the centrifugal separation process and a reduction in operating costs.

[0022] The control and / or regulation can be optimized using artificial intelligence methods.

[0023] According to the invention, the rotor speed is often reduced compared to an adjustable maximum speed. This deviates from the tradition of operating separators at the highest possible speeds to achieve high throughput rates with good separation or clarification. According to Prof. Werner H. Stahl (so), there are different types of liquid discharge from the rotating system in separators, which can influence energy consumption: Open separators, in which a liquid phase is discharged via a free overflow; semi-closed separators, in which the liquid phase is discharged via a peeling element, also known as a gripper; hermetic separators, in which the inlets and outlets are mechanically sealed (e.g., using a mechanical seal); when a liquid mixture is separated, a second liquid phase is also discharged, either openly, semi-closedly, or hermetically; the type of solids discharge also influences energy consumption. Stahl distinguishes the following types: • Discontinuous operation (manual emptying of the solids, e.g., solid-bowl separators) • Fully continuous operation (continuous solids discharge, e.g., nozzle separators) • Quasi-continuous operation (e.g., self-emptying separators)

[0024] In a centrifuge, the rotational speed is a crucial factor determining energy consumption. Intelligent, demand-based speed control of the drum, or the entire rotor (comprising the drum and any other rotating components such as the drive spindle), aims to achieve a very good, ideally optimal, compromise between energy consumption and efficiency.

[0025] It is therefore possible, within the scope of the invention, to identify and examine in more detail essential factors that influence the energy consumption of its separator.

[0026] After that, the frictional power of the rotor and the hydraulic power at the fluid outlet from the rotating system account for the majority (> 90%) of the energy requirement.

[0027] A separator series typically consists of separators of different sizes that share a geometric similarity. Therefore, all geometric relationships of separators can be reduced to a characteristic dimension. In this document, this characteristic dimension is the rotor diameter. The following principles then apply, among others: i) The frictional power PR of the rotor is proportional to the cube of the rotational speed n and the fifth power of the rotor diameter D. (PR ~ n 3< * D 5< ). ii) The hydraulic power P FI at the fluid outlet is proportional to the square of the rotational speed n and the square of the rotor diameter D. (P FI ~ n 2< * D 2< ), provided the flow rate Q is constant. If it is not, it also enters the proportionality relationship. (P FI ~ n 2< * D 2< * Q) iii) The equivalent clarification area Σ T is proportional to the square of the rotational speed n and the fourth power of the rotor diameter D. (Σ T ~ n 2< * D 4< ).

[0028] The equivalent treatment area is a value that describes the performance of a separator by comparing it to the capacity of a static settling tank. Therefore, if a separator has an equivalent treatment area of ​​100,000 m², it is as efficient as a static settling tank with the same surface area. While this value is not directly related to energy consumption, it determines the throughput, which in turn influences the hydraulic component of energy consumption.

[0029] Further advantageous embodiments of the invention are specified in the remaining dependent claims.

[0030] The invention is described in more detail below with reference to the drawing and an exemplary embodiment. Fig. 1 shows a schematic representation of a separator for the centrifugal processing of a product.

[0031] Fig. 1shows a schematic representation of a separator for the centrifugal processing of a product, in particular for clarifying a product from solids (or for concentrating such a phase) and / or for separating a product into different liquid phases.

[0032] The in Fig. 1The separator shown has a rotor with a rotatable drum 1 (shown here only schematically) with a preferably vertical axis of rotation. The drum has a drive spindle 2, which also forms part of the rotor and can be driven by a motor 3 via a drive connection (also not shown here). A feed line 4 leads into the drum 1. At least one liquid phase (or, in other designs with two outlets, two liquid phases of different densities) and optionally one (usually just barely flowable) solid phase can be discharged from the drum through one or more outlets 5 and optionally solid discharge openings 6. Preferably controllable (and preferably throttleable) valves are provided in the feed line 4 and the outlet(s) 5 (not shown here). A separation agent, in particular a disc stack 7 consisting of stacked and preferably conical separating discs, is arranged in the rotatable drum 2.

[0033] The rotatable drum 1 and preferably the drive / motor 3 are attached to a machine frame 8.

[0034] The respective drive of the separator, in particular according to the type of Fig. 1 Each of the motors 3 can be controlled via a control and / or regulation unit 9. The latter typically comprises a control computer with one or more input and output devices, a microprocessor, and memory. This memory can be located locally at the centrifuge. However, it can also be connected to a remote data storage device, such as cloud storage.

[0035] The control and / or regulating device 9 can be equipped with a suitable control and / or regulating program that runs on it. One or more sensors can be connected to it directly or indirectly, with which one or more operating parameters can be determined.

[0036] During operation, i.e., while the drum 1 is rotating, an operating parameter such as turbidity is measured by a sensor. This measurement takes place continuously or at intervals. The data measured by the sensor is transmitted to the control unit, where it is evaluated. The rotor speed is then used as a manipulated variable for control purposes. Using the control unit 9, the rotational speed (at least one manipulated variable) is used to influence the operation of the centrifuge in such a way as to achieve the desired behavior.

[0037] It is therefore conceivable to send a signal influencing the speed of the drum 1 to the motor 3 or its control, for example a frequency converter or other suitable power electronics, via a cable (or wirelessly) in order to change the speed of the respective motor 3.

[0038] It is also conceivable to include further parameters in the regulation. Reference sign

[0039] drum 1 drive spindle 2 Motor 3 supply line 4 Derivatives 5 Solid material discharge openings 6 Plate package 7 machine frame 8 Control unit 9

Claims

1. A method for controlling or regulating the operation of a centrifuge, wherein the centrifuge is a separator with a rotor rotatable about a vertical axis of rotation, which has a rotatable drum (1) in which a separation agent such as a separating plate assembly is arranged, during a continuous centrifugal processing of a product, in particular during the clarification of an incoming free-flowing suspension into a liquid phase and a solid phase or during the separation of an incoming free-flowing suspension into different liquid phases and optionally a solid phase in the drum (1), wherein the separated liquid and / or solid phases are discharged from the drum, characterized by the fact thatin which the operation of the centrifuge is controlled or regulated by a control or regulating device (9) in which the rotational speed of the rotor is set as a function of at least one existing and / or required operating parameter of the centrifugal processing, .

2. A method according to claim 1 for controlling the operation of the centrifuge, wherein at least one operating parameter of the centrifuge is to be maintained during the control of the operation of the centrifuge; comprising at least the following steps: a) at least one operating parameter to be maintained during the centrifugal processing of the suspension is defined, b) in particular, a rotational speed of the rotor is determined from pre-stored values ​​and / or on the basis of a model by means of a control device, with which it is possible to maintain the operating parameter(s), and c) the rotational speed of the rotor determined in step b) is set using the control device (9).

3. Method according to claim 1 for controlling the operation of the centrifuge, wherein the control of the operation of the centrifuge is intended to ensure that an operating parameter of the centrifuge is maintained; comprising at least the following steps: a) at least one operating parameter to be maintained during the centrifugal processing of the product is defined and this operating parameter or a related operating parameter is determined during operation, i.e., during rotation of the centrifuge rotor, in particular by means of a sensor device, b) the data determined in step a) are compared with target data using the control device (9), wherein at least one rotational speed of the rotor is determined as a manipulated variable using the control device based on this comparison, and c) the rotational speed determined in step b) is set using the control device.

4. Method according to claim 2 or 3, characterized by the fact thatIn step a) several operating parameters to be observed during the centrifugal processing of the product are defined and, if necessary, determined, and these are jointly included in determining and setting steps b) and c).

5. Method according to any of the foregoing claims, characterized by the fact that the operating parameter of step a) is the clarification surface load and the inflow quantity of the incoming suspension is determined, and that in step b) a rotational speed of the rotor is determined as a function of the inflow quantity, and that in step c) the rotational speed of the rotor is set so that the clarification surface load remains constant.

6. Method according to any of the foregoing claims, characterized by the fact thatthe operating parameter of step a) is a desired separation efficiency and that a turbidity of a clarified product phase is determined and that the data determined in step a) are forwarded to the control device, with which the measured data are compared with target data, wherein at least one rotational speed of the rotor in step b) is determined as a manipulated variable using the control device based on this comparison, and wherein in step c) this rotational speed of the rotor is set using the control device.

7. Method according to any of the foregoing claims, characterized by the fact that the operating parameter of step a) is a desired separation efficiency and that in step b) a particle distribution in the incoming product is determined and that, depending on the determined particle distribution, the rotational speed of the rotor is adjusted so that the desired separation efficiency is maintained exactly or within specified limits.

8. Method according to any of the foregoing claims, characterized by the fact that The operating parameter is the shear sensitivity of the incoming product, and the rotational speed of the rotor is adjusted depending on the shear sensitivity of the incoming product.

9. Method according to any of the foregoing claims, characterized by the fact that The operating parameter is the fill level of one of the feed tanks assigned to the centrifuge, from which the suspension to be processed is fed to the centrifuge in the feed, and that, depending on the fill level and possibly one or more operating parameters, a rotational speed of the rotor is determined and set.

10. Method according to any of the foregoing claims, characterized by the fact that The operating parameter is the energy consumption of the centrifuge drive, which is determined during centrifugal processing, and that the rotational speed is set so that a predetermined energy consumption is not exceeded.

11. Method according to any of the foregoing claims, characterized by the fact that the drive of the rotor has at least one or more electric motors which are controlled by means of power electronics and which are connected to the control or regulating device (9, 90) of the centrifuge.

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