Method for separating a liquid mixture in a centrifugal separator

Abstract

The present invention provides a method (100) for separating a liquid mixture in a centrifuge (1). The centrifuge (1) includes: a centrifuge barrel (10) arranged to rotate about a rotation axis (X) and in which the separation of a liquid mixture occurs; a frame (2) defining an enclosing space (3) which is sealed relative to the periphery of the frame (2), and the centrifuge barrel (10) is arranged in the enclosing space; a drive unit (4) configured to rotate the centrifuge barrel (10) relative to the frame (2) about the rotation axis (X), wherein the centrifuge barrel (10) further includes an inlet (11) for receiving the liquid mixture to be separated, at least one liquid outlet (12) for discharging the separated liquid phase, and a sludge outlet (14) for discharging the separated sludge phase into the enclosing space (3); and a container (20) connected to the enclosing space (3) and arranged to collect the separated sludge phase discharged from the centrifuge barrel (10). The method (100) includes the following steps: a) supplying (101) a liquid feed mixture to be separated to the inlet (11) of a centrifuge barrel (10); b) separating (102) the liquid feed mixture into at least one separated liquid phase and a separated sludge phase; c) removing (103) gas from the enclosing space (3) to obtain a pressure below atmospheric pressure in the enclosing space (3); d) discharging (104) the separated sludge phase into the enclosing space (3); e) collecting (105) the sludge phase in the container (20); f) removing (106) the sludge phase from the container (20); and g) after step f) injecting (107) liquid into the container (20) to reduce the level of foam present in the container (20).

Description

Technical Field

[0001] This invention relates to the field of centrifugal separators, and more particularly to a method for separating liquid mixtures in a centrifugal separator. Background Technology

[0002] Centrifuges are generally used for the separation of liquids and / or the separation of solids from liquids. During operation, the liquid mixture to be separated is introduced into a rotating drum, with heavier particles or denser liquids (typically water) accumulating at the periphery of the drum, while less dense liquids accumulate closer to the central axis of rotation. This allows the separated portions to be collected, for example, by means of separate outlets located at the periphery and near the axis of rotation.

[0003] To overcome the problem of high energy consumption during centrifugal separator operation, as known for example from WO10101524, a pressure below atmospheric pressure is generated around the rotating centrifuge barrel during operation. The removal of gases due to this sub-atmospheric pressure reduces frictional losses during operation.

[0004] However, many centrifuges are arranged such that the separated sludge phase is intermittently discharged into the space surrounding the centrifuge barrel. This can cause problems because the components in the discharged sludge may be affected by low pressure. For example, when separating liquid mixtures containing dissolved gases such as carbon dioxide (CO2), low pressure can promote foaming in the separated sludge. This can negatively impact the entire separator, as foaming can cause a variety of operational problems within the separator.

[0005] Therefore, there is a need in the art for improved methods of operating centrifuges at pressures below atmospheric pressure when processing liquid mixtures containing dissolved gases. Summary of the Invention

[0006] The objective of this invention is to overcome, at least in part, one or more limitations of the prior art. In particular, the objective is to provide a method for separating a liquid mixture containing dissolved gases using a centrifugal separator.

[0007] As a first aspect of the present invention, a method for separating a liquid mixture in a centrifuge is provided, wherein the centrifuge comprises

[0008] A centrifuge barrel arranged to rotate about an axis of rotation (X), within which the separation of a liquid mixture occurs.

[0009] A frame defines an enclosing space that is sealed relative to the periphery of the frame, and the centrifuge cylinder is arranged within this enclosing space.

[0010] A drive unit configured to rotate the centrifuge barrel relative to the frame about a rotation axis (X), wherein the centrifuge barrel further includes an inlet for receiving a liquid mixture to be separated, at least one liquid outlet for discharging the separated liquid phase, and a sludge outlet for discharging the separated sludge phase into an enclosing space.

[0011] A container, connected to the surrounding space and arranged to collect the separated sludge phase discharged from the centrifuge barrel,

[0012] The method includes the following steps:

[0013] a) The liquid feed mixture to be separated is supplied to the inlet of the centrifuge barrel.

[0014] b) Separate the liquid feed mixture into at least one separate liquid phase and a separate sludge phase.

[0015] c) Remove gas from the enclosing space to obtain a pressure below atmospheric pressure in the enclosing space.

[0016] d) Discharge the separated sludge phase into the enclosing space.

[0017] e) Collect the sludge phase in the container.

[0018] f) Remove the sludge phase from the container.

[0019] g) After step f), liquid is sprayed into the container to reduce the level of foam present in the container.

[0020] Steps a)-g) do not necessarily need to be performed in the sequence described above, and some steps can be performed simultaneously. As an example, step c) for removing gas can be performed during all other steps, i.e., before the supply of the liquid feed mixture in step a).

[0021] The centrifuge can be a stacked disc centrifuge, such as that disclosed in US20210107014. The centrifuge is arranged to discharge a sludge phase (i.e., a separated sludge phase that may also contain some liquid) into the space surrounding the centrifuge barrel. This can be performed by continuously discharging the sludge phase (i.e., the sludge outlet can be arranged to continuously discharge the sludge phase during operation) or by intermittently discharging the sludge phase (where the sludge outlet can be in the form of a set of ports arranged to open intermittently during operation). The centrifuge can be arranged to empty part of the contents of the barrel during such intermittent discharge (partial discharge) or to empty all the contents of the centrifuge barrel during intermittent discharge (complete discharge).

[0022] The first aspect of this invention is based on the insight that foaming, particularly in containers used to collect the discharged sludge phase, occurs when the separator is operated at pressures below atmospheric pressure. Such foaming can negatively impact the sludge pump used to remove solids from the container. For example, foam in the container may not be removed by the sludge pump, which may therefore run for unnecessarily long periods. Foaming can also occur, for example, in brewery processes, such as when beer is processed in a centrifuge. Beer foaming is caused by the generation of bubbles from released carbon dioxide (CO2), and because the solubility of CO2 is a function of the liquid's temperature and pressure, as well as the amount of dissolved CO2, operating the centrifuge barrel at pressures below atmospheric pressure will increase foaming of the discharged sludge.

[0023] Therefore, foam in the collection container may activate the high-level switch, which will cause the solids pump to activate and, in many cases, end with triggering a high-level alarm. This can lead to production interruptions due to the high-level alarm, as well as dry running of the solids pump, which significantly reduces the life of the pump stator.

[0024] In summary, the inventors recognized that foaming in the container negatively impacts centrifuge performance, reducing overall capacity and increasing maintenance costs. By actively spraying the container with liquid after removing discharged sludge, foaming can be significantly reduced, thus decreasing the risk of false alarms for high liquid levels in the container. Furthermore, such spraying helps keep any level sensors clean and further provides wetness for the sludge pump. With the spraying performed according to the method of the invention, centrifuge operation can be maintained for extended periods, with a reduction in the amount of false high liquid level detections in the container.

[0025] Step a) of supplying the liquid feed mixture to the centrifuge barrel can be performed via a stationary inlet pipe (which extends from the top into the centrifuge barrel) or via a rotating mandrel (to which the centrifuge barrel is attached, such as via the bottom of the centrifuge barrel). Step a) can be performed while the centrifuge barrel is rotating.

[0026] The separation step b) occurs inside the centrifuge barrel, such as in a stack of separation discs arranged in the centrifuge barrel.

[0027] Step c) to remove the gas can be performed before or during the rotation of the centrifuge barrel, for example by means of a vacuum pump connected (directly or indirectly) to the surrounding space. This thus provides a pressure below atmospheric pressure in the space within the frame surrounding the centrifuge barrel. The space can be sealed relative to its surroundings by means of, for example, mechanical or liquid seals.

[0028] As discussed above, step d) of discharging the sludge phase can be performed continuously or intermittently.

[0029] Step e) of collecting the silt phase can be performed simultaneously with the discharge of the silt phase into the enclosing space.

[0030] In an embodiment of the first aspect, step f) is performed using a sludge pump. Such a sludge pump can therefore be connected to a container.

[0031] The liquid used for spraying into the container can be an aqueous liquid, such as water.

[0032] In an embodiment of the first aspect, step g) includes spraying liquid from the top of the container into the container. Therefore, the container may include a spray nozzle disposed at the top of the container. The container may therefore include sidewalls and a top wall, and step g) may include spraying liquid from the top wall.

[0033] In an embodiment of the first aspect, step g) includes spraying the liquid with jet droplets larger than mist.

[0034] Larger jet droplets than mist can be droplets with a size greater than 60 micrometers.

[0035] As an example, step g) may include spraying liquid using at least one spray nozzle configured to spray droplets larger than a mist. The spray nozzle may be configured to clean a storage tank of several cubic meters. One or more spray nozzles used may be arranged to clean a storage tank having a volume larger than the container's volume. Therefore, step g) may include spraying a larger volume of liquid into the container.

[0036] Step g) may include spraying liquid using a spray nozzle that provides an umbrella-shaped spray pattern.

[0037] Therefore, the first method does not involve any step of spraying the liquid mist into the container.

[0038] In an embodiment of the first aspect, the container is a hydrocyclone. The hydrocyclone can therefore be arranged to aggregate and slow down the sludge phase.

[0039] The container can therefore be arranged to collect sludge and any liquid discharged from the sludge outlet. The container can be further connected to a sludge pump, or to further remove sludge and liquid present in the container.

[0040] In embodiments of the first aspect, the liquid feed mixture includes dissolved gases, such as CO2. As an example, the liquid mixture could be a liquid mixture used in beer processing. The method of the first aspect can therefore be used for beer clarification and / or the recovery of excess yeast from beer.

[0041] In an embodiment of the first aspect, step g) includes receiving information that there is still substance present in the container after step f) has been performed.

[0042] Therefore, step g) of spraying the liquid can be performed only if there is an indication that material remains in the container after the sludge has been removed, for example, by a sludge pump. This information can be received, for example, from a level sensor in the container and thus strongly indicates the presence of foam in the container. Therefore, as an example, the information can be received from a level switch arranged in the container.

[0043] Furthermore, step g) of spraying the liquid can be performed after emptying the container but before further discharge of sludge from the centrifuge barrel begins. Therefore, in the embodiment of the first aspect, step g) is performed before further discharge of the separated sludge phase begins.

[0044] However, the liquid may also be sprayed into the container during other steps of the method. As an example, before discharge, i.e. before step d), the container may be sprayed with liquid to keep the surface of the container wet, and also during the collection of sludge in the container, i.e. during step e), to keep the sludge wet and easier to pump by the sludge pump.

[0045] Therefore, in an embodiment of the first aspect, step d) includes spraying liquid into a container prior to the discharge of the separated sludge phase.

[0046] In another embodiment, step e) may therefore include spraying liquid into a container to wet the sludge phase after collecting it.

[0047] As defined by the method, step g) can therefore be a step of injecting liquid into the container, which is outside the normal discharge sequence; that is, the liquid injection in step g) can be activated based on a high liquid level switch in the container.

[0048] In an embodiment, step g) is terminated, that is, the liquid stops before further discharge begins (i.e., before another discharge of the separated sludge phase occurs).

[0049] The method is useful when the centrifuge drum is operated at a pressure below atmospheric pressure (i.e., when there is a pressure below atmospheric pressure in the surrounding space outside the drum). This surrounding space can be in direct contact with the container, such that there is also a pressure below atmospheric pressure in the container during centrifuge operation (i.e., during the separation of liquid mixtures in the centrifuge). This means that, in the embodiment of the first aspect, step c) also involves removing gas to obtain a pressure below atmospheric pressure in the container.

[0050] As a second aspect of the invention, a centrifugal separator is provided that can be used in the method of the first aspect. The centrifugal separator is arranged for separating at least one liquid phase and a sludge phase from a liquid feed mixture, including…

[0051] A centrifuge barrel arranged to rotate about an axis of rotation (X), within which the separation of a liquid mixture occurs.

[0052] A frame defines an enclosing space that is sealed relative to the periphery of the frame, and the centrifuge cylinder is arranged within this enclosing space.

[0053] A drive unit configured to rotate the centrifuge barrel relative to the frame about a rotation axis (X), wherein the centrifuge barrel further includes an inlet for receiving a liquid mixture to be separated, at least one liquid outlet for discharging the separated liquid phase, and a sludge outlet for discharging the separated sludge phase into an enclosing space.

[0054] A container, connected to the surrounding space and arranged to collect the separated sludge phase discharged from the centrifuge barrel,

[0055] A pump assembly, arranged to remove gas to achieve a pressure below atmospheric pressure in the enclosed space,

[0056] A spraying device for spraying liquid into the container.

[0057] A sludge pump, used to remove sludge from the container.

[0058] A control unit configured to begin spraying liquid into the container after sludge has been removed from the container to reduce the level of foam present in the container.

[0059] This aspect generally presents the same or corresponding advantages as the former aspect. The effects and features of this second aspect are largely similar to those described above in conjunction with the first aspect. The embodiments mentioned with respect to the first aspect are largely compatible with the second aspect.

[0060] Centrifuges are used to separate liquid feed mixtures. The liquid feed mixture can be an aqueous liquid or an oily liquid. As an example, a centrifuge can be used to separate solids and one or two liquids from a liquid feed mixture. The liquid mixture can be, for example, a pharmaceutical mixture or a food product such as beer, juice, or other beverages.

[0061] The frame of the centrifuge is the non-rotating (stationary) part. The centrifuge barrel of the separator can be arranged to rotate about a vertical axis of rotation, that is, the axis of rotation (X) can extend vertically. The centrifuge barrel is typically supported by a mandrel (i.e., the axis of rotation) and can therefore be mounted to rotate with the mandrel. Thus, the centrifuge may include a mandrel that can rotate about the axis of rotation (X). The centrifuge can be arranged such that the centrifuge barrel is supported by the mandrel at one end of it (such as at the bottom or top end of the mandrel).

[0062] The drive component may include an electric motor having a rotor and a stator. The rotor may be fixedly connected to the rotating part (such as to a spindle). Advantageously, the rotor of the electric motor may be disposed on or fixed to the spindle of the rotating part. Alternatively, the drive component may be disposed next to the spindle and the rotating part may be rotated by a suitable transmission device (such as a belt or gear transmission device).

[0063] The centrifuge barrel is surrounded by a rotor wall, enclosing a separation space. This separation space (where the separation of the fluid mixture occurs) may include separation components (such as a stack of separation discs). The separation discs may be, for example, metallic. Furthermore, the separation discs may be truncated conical separation discs, i.e., having a separation surface with a truncated conical portion forming the separation disc. The separation discs may be arranged coaxially about a rotation axis (X) at a distance from each other, such that a passage is formed between every two adjacent separation discs.

[0064] As used herein, the term "axial" refers to a direction parallel to the axis of rotation (X). Therefore, relative terms such as "above," "upper," "top," "lower," "below," and "bottom" refer to relative positions along the axis of rotation (X). Correspondingly, the term "radial" refers to a direction extending radially from the axis of rotation (X). "Radially inner position" therefore refers to a position closer to the axis of rotation (X) than "radially outer position."

[0065] The centrifuge also includes an inlet for the liquid mixture to be separated (liquid feed mixture). This inlet can be arranged to receive the liquid feed mixture and is centrally located within the centrifuge barrel, thus at the axis of rotation (X). The centrifuge barrel can be arranged to be supplied from the bottom, such as via a mandrel, such that the liquid feed mixture is conveyed from the bottom of the separator to the inlet. However, the centrifuge barrel can also be arranged to be supplied from the top, such as via a stationary inlet pipe extending into the barrel.

[0066] In addition, one or two liquid outlets may be arranged at the top or bottom of the centrifuge. Sludge outlets may include a set of nozzles for continuous sludge discharge during operation, or in the form of a set of intermittently open outlets. Therefore, the centrifuge barrel may include a set of radial sludge outlets in the form of intermittently open outlets at its outer periphery. The intermittently open outlets may be equidistantly spaced around the axis of rotation (X).

[0067] The container can be a hydrocyclone for receiving the discharged sludge phase. The hydrocyclone can be arranged to reduce the velocity of the discharged sludge.

[0068] The pump device is used to remove gas from the enclosed space. In an embodiment, the pump device is also arranged to remove gas from the container to also obtain a pressure below atmospheric pressure within the container.

[0069] Pumping devices may include liquid ring pumps, vane pumps, jet pumps, diaphragm pumps, piston pumps, scroll pumps, screw pumps, or combinations thereof. Pumping devices may also be vacuum sources or negative pressure sources. Pre-charged water liquid ring pumps are suitable for pumping gases mixed with water. Alternatively, vane pumps can be used to achieve pressures below the primary vapor pressure of water. Jet pumps also make it possible to use existing liquid flows in the system (e.g., flows of the fluid used for centrifugal separation at the inlet or outlet) as a means of generating the negative pressure.

[0070] According to an embodiment of the invention, the pump device is arranged to remove both gaseous and liquid materials from a space surrounding a rotor, the liquid material including a medium supplied to the space, a sludge phase discharged from a separation space to the space, condensate, a cleaning agent, or a combination thereof.

[0071] Pump units can be arranged to remove media, such as gases and / or liquids, from the enclosing space surrounding the centrifuge barrel, either continuously or intermittently.

[0072] The pressure below atmospheric pressure can be 1-50 kPa (preferably 2-10 kPa). The pump unit can be further arranged to adjust the pressure in the space during operation based on some operating conditions of the centrifugal separator.

[0073] The spraying device may include at least one spray nozzle. The at least one spray nozzle may be arranged to spray droplets larger than a mist. The spraying device may be arranged at the top of the container and configured to spray downwards into the container.

[0074] At least one spray nozzle may be a single-axis spraying device, such as a spray nozzle with a rotating spray head. At least one spray nozzle may be arranged such that liquid is discharged from a rotating spherical spray head through a defined number of orifices (e.g., slots, holes, and / or orifices of any arbitrary shape). This may differ from a spray nozzle in which liquid is discharged from a rotating open structure disk without defined orifices.

[0075] The nozzles can be arranged to spray droplets larger than mist, with a size greater than 60 micrometers. The nozzles can also be arranged for 360-degree spraying.

[0076] The sludge pump may be equipped with a check valve to prevent sludge from flowing into the container via the pump.

[0077] The control unit may include any suitable type of programmable logic circuitry, processor circuitry, or microcomputer, such as circuitry for digital signal processing (digital signal processor, DSP), central processing unit (CPU), processing unit, processing circuitry, processor, application-specific integrated circuit (ASIC), microprocessor, or other processing logic capable of interpreting and executing instructions. Therefore, the control unit may include a processor and input / output interfaces for communicating with the spraying device and, for example, for indicating the level of sludge in a container.

[0078] Therefore, in an embodiment of the first aspect, the centrifuge further includes a level switch disposed in the container, wherein the control unit is configured to receive an input from the level switch after sludge has been removed from the container, and to begin spraying liquid into the container if the input from the level switch indicates that there is still material present in the container. Attached Figure Description

[0079] The foregoing and additional objectives, features, and advantages of the present invention will be better understood from the following illustrative and non-limiting detailed description, with reference to the accompanying drawings. In the drawings, similar reference numerals will be used for similar elements unless otherwise stated.

[0080] Figure 1 A schematic diagram of a centrifugal separator according to an embodiment of the present invention is shown.

[0081] Figure 2 A flowchart illustrating a method for separating liquid mixtures in a centrifugal separator is shown. Detailed Implementation

[0082] The method and centrifuge according to this disclosure will be further illustrated in the following description with reference to the accompanying drawings.

[0083] Figure 1 A cross-section of an embodiment of a centrifugal separator 1 is shown, which is arranged to separate a sludge phase, a heavy liquid phase, and a light liquid phase from a liquid feed mixture.

[0084] Centrifuge 1 includes a centrifuge barrel 10 arranged to rotate about a rotation axis (X) by means of a spindle 7. The spindle 7 is supported in a frame 2 of the centrifuge in bottom bearings 5 ​​and top bearings 6. The centrifuge barrel 10 forms a separation chamber within itself, in which the centrifugal separation of the liquid feed mixture occurs during operation. The separation space within the centrifuge barrel 10 is provided with a stack of truncated conical separation discs to achieve efficient separation of the liquid feed mixture.

[0085] In this example, the mandrel 7 is a hollow mandrel for introducing the liquid feed mixture into the inlet 11 of the centrifuge barrel 10. The centrifuge barrel 10 also includes a liquid outlet 12 for discharging the separated light liquid phase and a liquid outlet 13 for discharging the separated heavy liquid phase. The light liquid outlet 12 is arranged at a smaller radius than the heavy liquid outlet 13. There are also stationary outlet pipes 12a and 13a, the stationary outlet pipe 12a being connected to the light liquid outlet 12 for receiving the separated light liquid phase, and the stationary outlet pipe 13a being connected to the heavy liquid outlet 13 for receiving the separated heavy liquid phase.

[0086] The centrifuge barrel 10 also includes a sludge outlet 14 for discharging the separated sludge phase into an enclosing space 3, which is sealed relative to the periphery of the frame 2, within which the centrifuge barrel 10 is arranged. The sludge outlet 14 takes the form of a set of intermittently openable sludge outlets arranged at the outer periphery of the centrifuge barrel 10 for discharging sludge from a radially outer portion of the separation space into the enclosing space 3. As is known in the art, such intermittent discharge can be performed by an axially movable operating slide disposed within the centrifuge barrel 10.

[0087] The centrifuge 1 also includes a drive motor 4 configured to rotate the centrifuge drum 10 relative to the frame 2 about a rotation axis (X). The drive motor 4 is directly connected to the spindle 7. However, the drive motor may also be connected to the spindle 7 via a transmission device in the form of a worm gear, which includes a pinion and elements connected to the spindle to receive the drive torque. The transmission device may alternatively take the form of a propeller shaft, a drive belt, etc.

[0088] The enclosing space 3 is sealed relative to the periphery of the frame by means of the upper seal 15 and the lower seal 16. The frame 3 thus defines the space 3, which houses the centrifuge barrel 10, and the space 3 is hermetically sealed relative to the periphery of the frame. The upper seal 15 may be an outlet seal that seals the liquid outlet relative to the periphery. If the centrifuge is arranged with a stationary inlet pipe extending from the top into the centrifuge barrel, the upper seal 15 may also be a seal that seals the inlet relative to the periphery.

[0089] The upper seal 15 can be, for example, a mechanical seal or a liquid seal. Furthermore, the upper seal 15 can be a gas seal, a liquid seal, a labyrinth seal, or a combination thereof. The lower seal 16 can also be a mechanical seal or a liquid seal. Furthermore, the lower seal 16 can be a gas seal, a liquid seal, a labyrinth seal, or a combination thereof.

[0090] One or both of the upper seal 15 and the lower seal 16 may be an airtight seal.

[0091] The centrifuge further includes a pump assembly 26 for removing gas from the enclosing space 3, which takes the form of a water-filled liquid ring pump (or, alternatively, a sheet pump). In this example, the pump assembly is directly connected to the frame 3, but (by way of example) it may also be connected to the container 20 discussed below.

[0092] The centrifuge also includes a container 20 connected to the surrounding space 3. The container 20 is in the form of a hydrocyclone and is arranged to collect the separated sludge phase discharged from the centrifuge barrel 10. The container 20 is further connected to a discharge device 25 in the form of a sludge pump for discharging the sludge and liquid present in the container 20. The sludge pump is equipped with a check valve to prevent flow into the container 20 via the sludge pump.

[0093] The container 20 also includes a spraying device in the form of spray nozzles 21a, 21b for spraying liquids (such as water) into the container 20. As an example, the container may include at least two (such as at least three) spray nozzles. The spray nozzles 21a, 21b are in the form of spray nozzles with rotating spray heads and are configured to spray droplets larger than mist into the container 20.

[0094] As indicated by arrow 31, the injection of liquid into container 20 is controlled by control unit 30. Control unit 30 is configured to initiate injection with nozzles 21a, 21b after sludge has been removed from container 20 to reduce the liquid level of foam present in container 20. However, control unit can also be configured to inject liquid into the container before and after sludge phase discharge to both wet the inner surface of container 20 and the discharged sludge.

[0095] A level switch 22 is also arranged in the container 20. This level switch 22 may include, for example, one or more sensors for indicating the level of sludge or material in the container 20. The control unit 30 is further configured to continuously (or, for example, after sludge has been removed from the container (20)) receive input from the level switch 22. Based on this input, the control unit 30 is configured to begin injecting liquid into the container 20 if the input from the level switch 22 indicates that material remains in the container 20 after the sludge pump 25 has removed the sludge.

[0096] Therefore, the control unit 30 may include, for example, a computing unit that can take the form of virtually any suitable type of programmable logic circuitry, processor circuitry, or microcomputer, such as circuitry for digital signal processing (digital signal processor, DSP), central processing unit (CPU), processing unit, processing circuitry, processor, application-specific integrated circuit (ASIC), microprocessor, or other processing logic capable of interpreting and executing instructions. The computing unit may represent a processing circuitry that includes multiple processing circuits, such as any, some, or all of those mentioned above. The control unit 30 may also include a memory unit that provides the computing unit with, for example, stored program code and / or stored data (which the computing unit requires to enable it to perform calculations). The computing unit may also be adapted to store portions or final results of calculations in the memory unit. The memory unit may include physical means for storing data or programs (i.e., sequences of instructions) on a temporary or permanent basis.

[0097] Depend on Figure 2 The flowchart in the document further illustrates the method of the present invention. Figure 1 During operation of the separator, the centrifuge barrel 10 is rotated by torque transmitted from the drive motor 4 to the spindle. A vacuum pump 26 pumps gas out of the surrounding space 3 outside the centrifuge barrel 10, thereby maintaining a pressure of, for example, 1-50 kPa (such as 2-10 kPa) within the surrounding space 3. Because the container 20 is in communication with the surrounding space 3, the pump also maintains a pressure below atmospheric pressure within the container 20. The liquid mixture to be separated is brought through inlet 11 into the separation space within the centrifuge barrel 10 and between conical separation discs adapted to the separation space. The liquid mixture is a liquid mixture comprising dissolved gases (such as dissolved CO2).

[0098] Heavier components in the liquid mixture (e.g., sludge particles and / or heavy phase) move radially outward between the separation discs and accumulate in the sludge phase outlet 14. Sludge is intermittently emptied from the separation space through the open sludge outlet 14, thus sludge and a certain amount of fluid are discharged from the separation space by centrifugal force. Sludge discharge can also occur continuously, in which case the sludge outlet 14 takes the form of an open nozzle, and a certain flow rate of sludge and / or heavy phase is continuously discharged by centrifugal force. Sludge discharged from the separation space via the sludge outlet 14 is transported from the surrounding space 3 to the connected container 20, where sludge accumulates and is pumped out by the sludge pump 25. The separated light liquid phase moves radially inward between the separation discs and is discharged via the light liquid phase outlet 12 to the stationary outlet pipe 12a, while the separated heavy liquid phase is discharged via the heavy liquid phase outlet 13 to the stationary outlet pipe 13a. Therefore, as Figure 2 The method shown includes the following steps:

[0099] a) The liquid feed mixture to be separated is supplied from 101 to the inlet 11 of the centrifuge barrel 10.

[0100] b) Separate the liquid feed mixture 102 into at least one separated liquid phase and a separated sludge phase.

[0101] c) Remove 103 gas from the enclosing space 3 to obtain a pressure below atmospheric pressure in the enclosing space 3 and in the container 20.

[0102] d) Discharge the separated sludge phase 104 into the surrounding space 3 and discharge the separated liquid phase 111.

[0103] e) Collect 105 sludge phase in container 20, and

[0104] f) Remove 106 sludge phase from container 20.

[0105] Liquid can be sprayed into container 20 via spray nozzles 21a and 21b to wet the inner surface of container 20 before discharge in step d). Additionally, when sludge has been collected in container 20, further liquid spraying can be performed by spray nozzles 21a and 21b. Therefore, method 100 may include spraying liquid 109 into container 20 before discharging the separated sludge phase, and spraying liquid 110 into container 20 after collecting the sludge phase. Thus, the method may include a discharge spray sequence at discharge, which includes spraying liquid shortly before and / or during the discharge of the sludge phase and spraying liquid into container 20 when the sludge has been collected. Such a spray sequence may be initiated by control unit 30, which may therefore be connected to the control system of the entire centrifuge 1 or form part of the control system of the entire centrifuge 1.

[0106] The sub-atmospheric pressure in container 20 can cause foaming due to bubbles generated from the released carbon dioxide (CO2) discharged from the sludge phase. This is because the solubility of CO2 is a function of the liquid's temperature and pressure, as well as the amount of dissolved CO2. The foam in container 20 can activate a high-level switch 22, and in response, a method includes an additional step g) of injecting liquid 107 into container 20 after step f) is performed. This additional liquid injection (which is therefore outside the discharge injection sequence) is to lower the level of the foam present in container 20. Thus, such step g) is performed to begin further discharge of the separated sludge phase, i.e., before beginning the further discharge injection sequence.

[0107] The additional injection in step g) can also be activated by the control unit based on input from the level switch 22. Therefore, step g) includes receiving information that there is still substance (foam) in container 20 after step f) is performed, and then injecting liquid 107 into container 20 after step f) to reduce the level of foam present in container 20.

[0108] Therefore, the control unit 30 is configured as follows

[0109] - Before discharge, the liquid is sprayed into the container 20 via spray nozzles 21a and 21b.

[0110] - Once the sludge has been collected in the container, liquid is sprayed into the container 20 via spray nozzles 21a and 21b.

[0111] - Receive input from level switch 20 indicating that there is still material in the container after the sludge has been removed, and

[0112] -Based on the input received from the level switch 22, additional liquid injection is initiated via injection nozzles 21a, 21b to reduce foam in container 20.

[0113] The control unit 30 can be further configured to control the discharge of the sludge phase from the centrifuge drum 10. The discharge can be controlled via an operating water module (OWM, not shown) as known in the art. Therefore, the control unit 30 can be further configured to...

[0114] - Begin discharging the sludge phase from centrifuge barrel 10.

[0115] This invention is not limited to the disclosed embodiments, but can be varied and modified within the scope of the claims set forth below. The invention is not limited to the orientation of the rotation axis (X) disclosed in the figures. The term "centrifuge" also includes centrifuges having a substantially horizontally oriented rotation axis. In the foregoing, the inventive concept has been described primarily with reference to a limited number of examples. However, as will be readily apparent to those skilled in the art, other examples besides those disclosed above are equally possible within the scope of the inventive concept as defined by the appended claims.

Claims

1. A method (100) for separating a liquid mixture in a centrifuge (1), wherein, The centrifuge (1) includes Centrifuge barrel (10), the centrifuge barrel (10) is arranged to rotate about a rotation axis (X), and the separation of liquid mixtures occurs in the centrifuge barrel (10). A frame (2) defines an enclosing space (3), which is sealed relative to the periphery of the frame (2), and the centrifuge cylinder (10) is arranged within the enclosing space (3). A drive component (4) is configured to rotate the centrifuge barrel (10) relative to the frame (2) about the axis of rotation (X), wherein the centrifuge barrel (10) further includes an inlet (11) for receiving the liquid mixture to be separated, at least one liquid outlet (12) for discharging the separated liquid phase, and a sludge outlet (14) for discharging the separated sludge phase into the enclosing space (3). Container (20), which is connected to the enclosing space (3) and arranged to collect the separated sludge phase discharged from the centrifuge barrel (10), The method (100) includes the following steps: a) The liquid feed mixture to be separated is supplied to the inlet (11) of the centrifuge barrel (10). b) Separating the liquid feed mixture into at least one separate liquid phase and a separate sludge phase. c) Remove gas from the enclosing space (3) to obtain a pressure below atmospheric pressure in the enclosing space (3). d) Discharge the separated sludge phase into the enclosing space (3), e) Collect the sludge phase in the container (20), f) Remove the sludge phase from the container (20), g) After step f), liquid is sprayed into the container (20) to reduce the liquid level of the foam present in the container (20).

2. The method (100) according to claim 1, wherein, Step g) includes spraying the liquid from the top of the container (20) into the container (20).

3. The method (100) according to claim 1 or 2, wherein, Step g) involves spraying the liquid with jets larger than a mist.

4. The method (100) according to claim 1 or 2, wherein, The container (20) is a hydrocyclone.

5. The method (100) according to claim 1 or 2, wherein, The liquid feed mixture includes dissolved gas.

6. The method (100) according to claim 5, wherein, The liquid feed mixture includes dissolved CO2.

7. The method (100) according to claim 5, wherein, The liquid mixture is a liquid mixture used in beer processing.

8. The method (100) according to claim 1 or 2, wherein, Step g) includes receiving information that there is still substance in the container (20) after step f) has been performed.

9. The method (100) according to claim 8, wherein, The information is received from a level switch (22) arranged in the container (20).

10. The method (100) according to claim 1 or 2, wherein, Step g) is performed before proceeding with further discharge of the separated sludge phase.

11. The method (100) according to claim 1 or 2, wherein, Step d) includes spraying liquid into the container (20) prior to the discharge of the separated sludge phase.

12. The method (100) according to claim 1 or 2, wherein, Step e) includes spraying liquid into the container (20) to wet the sludge phase after collecting the sludge phase.

13. The method (100) according to claim 1 or 2, wherein, Step c) also involves removing the gas to obtain a pressure below atmospheric pressure in the container (20).

14. The method (100) according to claim 1 or 2, wherein, Step f) is performed using a sludge pump (25).

15. A centrifugal separator (1) for separating at least one liquid phase and a sludge phase from a liquid feed mixture, comprising: Centrifuge barrel (10), the centrifuge barrel (10) is arranged to rotate about a rotation axis (X), and the separation of liquid mixtures occurs in the centrifuge barrel (10). A frame (2) defines an enclosing space (3), which is sealed relative to the periphery of the frame (2), and the centrifuge cylinder (10) is arranged within the enclosing space (3). A drive component (4) configured to rotate the centrifuge cylinder (10) relative to the frame (2) about the axis of rotation (X), wherein, The centrifuge barrel (10) further includes an inlet (11) for receiving the liquid mixture to be separated, at least one liquid outlet (12) for discharging the separated liquid phase, and a sludge outlet (14) for discharging the separated sludge phase into the enclosing space (3). Container (20), which is connected to the enclosing space (3) and arranged to collect the separated sludge phase discharged from the centrifuge barrel (10), A pump assembly (26) is arranged to remove gas to obtain a pressure below atmospheric pressure in the enclosing space (3). The spraying devices (21a, 21b) are used to spray liquid into the container (20). A sludge pump (25) for removing sludge from the container (20). A control unit (30) is configured to begin spraying liquid into the container (20) after the sludge has been removed from the container (20) to reduce the level of foam present in the container (20).

16. The centrifuge (1) according to claim 15, further comprising a level switch (22) disposed in the container (20), wherein, The control unit (30) is configured to receive an input from the level switch (22) after the sludge has been removed from the container (20), and to begin spraying liquid into the container (20) if the input from the level switch (22) indicates that there is still substance in the container (20).

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