Method for operating a centrifuge and an arrangement comprising a centrifuge and a gas reservoir

Abstract

A method for operating a centrifuge (1), wherein the centrifuge has an inlet pipe (4) and a rotatably mounted drum (2) with a vertical axis of rotation, and wherein the centrifuge has at least one grab chamber (5) for draining clarified or separated liquid, and wherein the centrifuge (1) has a barrier chamber (7) above the grab chamber (5) with a barrier disc (9) projecting into the barrier chamber, wherein during operation of the centrifuge a barrier gas (13), which is heavier than air, is located in the barrier chamber and which is introduced into the barrier chamber through a channel (11) which opens into the barrier chamber (7), and an arrangement comprising a centrifuge (1) and a gas reservoir (30) for a barrier gas.

Description

[0001] The present invention relates to a method for operating a centrifuge according to the preamble of claim 1 and an arrangement comprising a centrifuge and a gas reservoir according to the preamble of claim 6.

[0002] Centrifuges with a locking function above a gripper are known from the prior art. In a typical centrifuge drum, there is a chamber in the head into which a stationary locking disc protrudes. The chamber is either filled discontinuously with water from the outside via pulses or directly through a channel in the locking disc. In this case, the pressure is kept constant via the locking disc, similar to a gripper filling the chamber backwards. The locking disc is immersed in the water ring and thus seals the gripper and drum chamber from the space outside the drum, preventing any product in the drum from coming into contact with the oxygen-rich atmosphere.

[0003] Relevant prior art in this regard includes DE 2 737 463 C2 and DE 196 31 226 C2. A challenge here is to keep the barrier chamber constantly filled, which can be achieved, for example, by controlled overflow. Furthermore, a barrier fluid that does not contain oxygen (e.g., degassed water) must be used, as there are products in which even very small traces of oxygen are negative. Furthermore, the barrier fluid must be prevented from running downwards into the product.

[0004] The state of the art is still DE 10 2011 052 142 A1, in which a barrier gas is fed directly into the gripper chamber(s) (not the barrier chamber) and can then mix with the product.

[0005] This also applies to DE 696 796, where this mixing is even desired.

[0006] DE 81 30 833 U1 discloses that gas pressure can cause a displacement of the liquid column on the top and bottom of the barrier disc, with the effect of a better seal and reduced overspray.

[0007] DE 20 2007 009 212 discloses the use of gas pressure to shift the separation zone. This requires an incompressible medium so that a fluid communication the barrier fluid and the fluid in the separation chamber of the drum.

[0008] Furthermore, processes are known in which the entire drum, or even the entire centrifuge, is flooded with N2 or CO2 (e.g., GB 252 521). However, this procedure requires a comparatively large amount of inert gas. Furthermore, there is a certain risk to employees in the event of a leak, as CO2 is a respiratory poison.

[0009] For separators that process a product that changes its properties when it comes into contact with oxygen, the drum must be sealed from the environment in such a way that the product does not come into contact with the oxygen-containing ambient atmosphere.

[0010] Based on the above-described prior art, it is the object of the present invention to provide a method for operating a centrifuge which has an improved sealing of the product in the centrifuge drum against the oxygen-rich environment.

[0011] The present invention solves the problem by a method having the features of claim 1.

[0012] A method according to the invention is used to operate a centrifuge. This operation can be part of a process step in beverage processing. The primary goal here is to prevent biological degradation and oxidation, which, among other things, affect the color and taste of the beverage. However, the method can also be used in synthetic chemistry, for example, for reactions and reaction products that must be kept under protective gas.

[0013] The centrifuge has an inlet pipe and a rotatable drum with a vertical axis of rotation.

[0014] The centrifuge has, in a manner known per se, at least one gripper chamber for draining clarified or separated liquid.

[0015] Above the gripper chamber, the centrifuge has a locking chamber with a locking disc extending into it. This design has been known for a long time and can be found in detail in DE 196 31 226 A1, to which reference is made in the context of the present invention.

[0016] According to the invention, however, in contrast to the aforementioned prior art, a sealing gas, which is heavier than air, is present in the sealing chamber instead of a sealing liquid during operation of the centrifuge. Unlike completely flooding the centrifuge with inert gas, in the process according to the invention the sealing gas is introduced into the sealing chamber through a channel that opens into the sealing chamber.

[0017] The seal gas can be introduced before commissioning and, in particular, during operation. For example, it may be necessary to continuously or temporarily introduce additional seal gas during centrifuge operation if the centrifuge's rotation speed increases.

[0018] The use of barrier gas leads to a significant structural simplification of the centrifuge design and ensures low gas consumption compared to other processes.

[0019] Advantageous embodiments of the invention are the subject of the subclaims.

[0020] It is advantageous if the barrier gas is CO2 and / or an inert gas, especially a noble gas. Argon is considered a preferred noble gas. In the case of CO2, a further advantage is that the gas is available in large quantities and is frequently used by the food and beverage industry in other contexts.

[0021] The supply of barrier gas can be adjusted during centrifuge operation depending on the rotation speed of the drum. Since gas is compressible, the volume within the barrier chamber can decrease as the drum's G-force increases. Therefore, it is advantageous to add barrier gas as the rotation speed increases to prevent failure of the barrier function.

[0022] Alternatively or in addition to the preceding control, it is advantageous if the centrifuge has a sensor for detecting CO 2 , in particular in MEMS design, wherein a supply of sealing gas takes place depending on measurement data determined by the sensor.

[0023] Furthermore, the containment chamber can have a lower wall and an upper wall, with "lower" and "upper" defined by the Earth's gravitational field. The walls are part of the drum and define the upper and lower boundaries of the containment chamber.

[0024] The walls extend radially from the outside to the inside toward the inlet pipe. They can preferably run parallel to each other and perpendicular to the drum's axis of rotation.

[0025] However, the walls do not reach the inlet pipe, but end beforehand, forming a gap between the respective wall and the inlet pipe.

[0026] The minimum distance between the rotation axis and the lower wall is smaller than the minimum distance between the rotation axis and the upper wall, so that the upper wall forms an overflow edge over which the barrier gas can flow away, for example in the case that the barrier chamber is filled with barrier gas.

[0027] Furthermore, the invention relates to an arrangement comprising a centrifuge and a gas reservoir with a sealing gas which is heavier than air, wherein the centrifuge has an inlet pipe and a rotatably mounted drum with a vertical axis of rotation and wherein the centrifuge has a gripper chamber for discharging clarified liquid.

[0028] Above the gripper chamber there is a locking chamber with a locking disc extending into the locking chamber. The centrifuge also has a channel which opens into the locking chamber.

[0029] In contrast to the prior art, the arrangement has a supply line for introducing sealing gas into the sealing chamber, which extends between the gas reservoir and the channel. Through this supply line, sealing gas can be directed via the channel into the sealing chamber.

[0030] Preferred embodiments of the arrangement according to the invention are the subject of the subclaims.

[0031] The arrangement can comprise a control unit equipped to carry out the aforementioned method according to the invention. For this purpose, the control unit can, in particular, control a control element arranged on the aforementioned supply line or, if appropriate, on the duct.

[0032] The channel can preferably be arranged in the inlet pipe, in particular parallel to the drum's rotational axis. A corresponding pipe thickness must be provided in the area of ​​the channel.

[0033] Furthermore, the centrifuge can have a hood enclosing the drum, wherein the hood has a gas outlet, preferably a valve for releasing gas in the event of excess pressure. Alternatively, the hood can also have a leak.

[0034] The channel can open into an area outside the hood of the centrifuge so that the supply line for the sealing gas can be connected from the outside, which has advantages when replacing the gas reservoir, e.g. a gas cylinder.

[0035] The arrangement can further comprise a flow meter for determining the supplied volume or mass flow of barrier gas. A suitable flow meter can be, for example, a thermal flow meter. With such measuring devices, it is also possible, e.g. based on thermal conductivity or thermal diffusivity, to detect a change in medium from barrier gas to air. The thermal conductivity of air under standard conditions is, for example, 0.0262 W / (m*K) and of CO2 under standard conditions 0.0168 W / (m*K) and is thus significantly lower. The same applies to argon. If such a flow meter is placed in the area of ​​the aforementioned overflow edge, it is possible to monitor whether a sufficient amount of CO2 is present as barrier gas in the barrier chamber and, at the same time, to determine the amount of barrier gas flowing out into the hood and thus control the inflow flow.

[0036] The aforementioned arrangement has particular advantages in beverage processing and / or in the chemical synthesis of a compound, particularly a pharmaceutical product, under protective gas. Further advantages, features, and details of the invention will emerge from the following description, in which an exemplary embodiment of the invention is explained in more detail with reference to the drawing. Those skilled in the art will expediently consider the features disclosed in the drawing, the description, and the claims individually and combine them into useful further combinations.

[0037] It shows: Fig. 1 is a schematic representation of a variant of a centrifuge as part of an arrangement according to the invention for carrying out the method according to the invention; and Fig. 2 is a detailed representation of the head region of the centrifuge drum of the Fig. 1Fig. 3 a representation of a further embodiment of a centrifuge for carrying out the method according to the invention with the addition of an optional hydrohermetic seal.

[0038] Fig. 1 shows an embodiment of a centrifuge 1 in the form of a disc centrifuge and Fig. 2 shows a detailed view of centrifuge 1 of the Fig.1 in vertical section in the head area of ​​the centrifuge drum 2.

[0039] Further in Fig. 2 schematically shows a gas reservoir 30 which is part of an arrangement according to the invention.

[0040] The centrifuge 1 has a centrifuge drum 2 rotatably mounted on or on a spindle 23, or a centrifuge drum 2 with a rotatably mounted spindle 23, each with a vertical axis of rotation 3. Furthermore, the centrifuge has a piston slide 22 and several discharge openings 20. A housing or hood 21 is arranged around the centrifuge 1.

[0041] The centrifuge 1 has a centrally arranged, stationary inlet pipe 4, through which a product can be fed into a distribution chamber 24 within the drum 2. In the head area, the centrifuge has a chamber 5, e.g., a gripper chamber, in which a fixed gripper 8 is mounted.

[0042] The clarified product is discharged through the discharge pipe 17 through one or more discharge channels 25 within the gripper 8.

[0043] Above the chamber 5, a barrier chamber 7 is provided, which rotates with the centrifugal drum 2. A barrier disc 9 extends into the barrier chamber 7, which rotates with the centrifugal drum 2 and is connected to the inlet pipe 4 and thus fixed in position.

[0044] A barrier medium is fed into the barrier chamber 7 through a channel 11 and a bore 12 branching off from this channel 11. This barrier medium is pressed radially outward against the wall of the barrier chamber 7 due to centrifugal forces as the drum rotates.

[0045] Furthermore, the centrifuge has an overflow edge 15 between the inlet pipe 4 and a wall 14 defining the top of the barrier chamber 7. A wall 19 defining the bottom of the barrier chamber 7 is also provided.

[0046] The special feature of the present invention is the use of gas 13 as a barrier medium to prevent the penetration of oxygen from the atmosphere.

[0047] Thus, according to the concept of the present invention, instead of a sealing liquid, a sealing gas 13, such as CO2, is supplied from the gas reservoir 30 via the supply line 31 and via the channel 11, which is in Fig. 1The CO2 is arranged above the barrier disc, but can also be arranged in the barrier disc 9, and is filled into the barrier chamber 7. Since CO2 is heavier than air, it is thrown outward in the rotating barrier chamber, and air is displaced from the barrier chamber. This creates an effective barrier against further penetration of air, and thus also oxygen, into the drum.

[0048] In Fig. 2 In addition, a control element 32, e.g. a valve, is shown, which can be controlled via a control unit 40 so that the gas supply can be controlled.

[0049] Mixing with the product flow in the gripper chamber 5 below the barrier chamber occurs little or not at all. If it does occur, it has no negative impact on the product, unlike oxygen. CO2 is also typically used in the beverage industry. As an alternative to CO2, other gases that are heavier than air can be used, displacing the air, and thus the oxygen in the air. Ideally, this should be an inert gas such as argon.

[0050] Since gases, unlike liquids, are compressible, it can be assumed that the gas volume within the barrier chamber decreases with increasing speed of drum 2. Therefore, the gas supply during drum operation can be dependent on the speed or alternatively, it can be detected.

[0051] In the first case, empirical values ​​are used, which are stored in the form of a data set in the data memory of the control unit 40. At increased rotation speeds, more gas is supplied. If too much gas is supplied, it can flow over the overflow edge 15 into the space of the hood 21. The hood 21 does not need to be completely sealed.

[0052] Optionally, a valve 16, e.g. a spring-loaded pressure relief valve, can be arranged in the hood 21, through which the air / CO 2 mixture can be discharged in the event of excess pressure.

[0053] In the alternative or additional variant, a gas sensor, in particular a CO2 sensor, can be arranged in the area of ​​the blocking disc 9 and / or in the area of ​​the overflow edge 14. This sensor can monitor the spread of CO2 at different speeds. For example, if no CO2 is detected at sensor 18, more CO2 must be introduced into the blocking chamber 7. This control is carried out, for example, by the control unit 40, which accordingly activates the control element.

[0054] In the case of position 18', CO2 can be detected escaping from the overflow gap due to an excessive supply of CO2. In this case, the supply of gas 13 must be reduced.

[0055] Miniaturized gas sensors (e.g., MEMS sensors) have been commercially available for some time, for example, as so-called "smart nose" sensors or based on infrared sensors, and can be used for the aforementioned purpose. It is also possible to equip a prototype with the sensors to determine the required inlet flow rate at a given speed. This data can then be stored as a data set for controlling the gas inlet flow rate depending on the speed in a data storage device for series products.

[0056] A separator or a centrifuge according to the invention is preferably suitable for all processing operations in which the exclusion of oxygen is advantageous in order to avoid undesirable oxidation processes.

[0057] This is especially true during the processing of beverages, such as fruit juices or beer. For example, vitamin C from citrus fruits or other fruits and vegetables reacts with oxygen. Other natural products are also oxidized, thereby changing their color and flavor.

[0058] Another area of ​​application is oxygen-sensitive reactions, which can occur, for example, in chemical synthesis, for example, in pharmaceutical products. Typically, this application involves a variety of reactions under protective gas. Argon, in particular, can be used instead of CO2 due to its chemical inertness.

[0059] Fig. 3 shows a further embodiment of a centrifuge 1' for carrying out a method according to the invention and in the form of an arrangement according to the invention. A control unit and corresponding sensors can be used analogously to Fig. 1 and 2 to be available.

[0060] The centrifuge 1' of the Fig. 3 has an addition to the variant of the Fig. 1 and 2 with an optional hydrohermetic seal 26, which is arranged between the barrier chamber 7 and the gripper chamber 5. The hydrohermetic seal 26 is not mandatory, but is a suitable additional sealing option in some applications.

[0061] The hydrohermetic seal comprises a liquid-loaded barrier chamber 27 and a barrier disc 28 which projects into the liquid 29 of the barrier chamber.

[0062] Through a separate inlet 33, liquid 29, preferably in the form of degassed or sterile water, can be fed into the barrier chamber 27 in order to easily prevent oxygen absorption at the gripper 8. Reference symbol

[0063] 1 Centrifuge 2 Drum or centrifuge drum 3 Rotary axis 4 Inlet pipe 5 Gripper chamber 7 Sealing chamber 8 Gripper 9 Sealing disc 11 Channel 12 Bore 13 Sealing gas 14 Wall 15 Overflow edge 16 Valve 17 Discharge pipe 18 Sensor 18 Sensor 19 Wall 20 Discharge opening 21 Hood 22 Piston valve 23 Spindle 24 Distributor chamber 25 Discharge channel 26 Hydrohermetic seal 27 Sealing chamber 28 Sealing disc 29 Liquid 30 Gas reservoir 31 Supply line 32 Control element 33 Inlet - sealing liquid 40 Control unit

Claims

1. Method for operating a centrifuge (1), wherein the centrifuge (1) has an inlet pipe (4) and a rotatably mounted drum (2) with a vertical axis of rotation (3) and wherein the centrifuge (1) has at least one gripper chamber (5) for discharging clarified or separated liquid and wherein the centrifuge (1) has a blocking chamber (7) above the gripper chamber (5) with a blocking disk (9) projecting into the blocking chamber (7), wherein a blocking gas (13), which is heavier than air, is located in the blocking chamber (7) and is introduced into the blocking chamber (7) through a channel (11) that opens into the blocking chamber (7), characterized in that the channel (11) is arranged above the blocking disk (9) or in the blocking disk (9).

2. Method according to claim 1, characterized in that the blocking gas (13) is CO2 and / or an inert gas, in particular a noble gas.

3. Method according to one of the preceding claims 1 or 2, characterized in that a supply of blocking gas (13) during operation of the centrifuge (1) takes place as a function of the rotational speed of the drum (2).

4. Method according to one of the preceding claims, characterized in that the centrifuge (1) has a sensor (18, 18') for detecting CO2, in particular in MEMS design, wherein a supply of blocking gas (13) is carried out as a function of measurement data determined by the sensor (18, 18').

5. Method according to one of the preceding claims, characterized in that the blocking chamber (7) has a lower wall (19) and an upper wall (14), which are part of the drum (2) and which extend radially from the outside inward in the direction of the inlet pipe (4), forming an intermediate space between the respective wall (14, 19) and the inlet pipe (4), wherein the minimum distance between the axis of rotation (3) and the lower wall (19) is smaller than the minimum distance between the axis of rotation (3) and the upper wall (14), so that the upper wall (14) forms an overflow edge (15), over which the blocking gas (13) flows off, in particular when the blocking chamber (7) is filled.

6. Arrangement comprising a centrifuge (1) and a gas reservoir (30) with a blocking gas (13) that is heavier than air, wherein the centrifuge (1) has an inlet pipe (4) and a rotatably mounted drum (2) with a vertical axis of rotation (3), and wherein the centrifuge (1) comprises at least one gripper chamber (5) for discharging clarified or separated liquid and the centrifuge (1) comprises a blocking chamber (7) above the gripper chamber (5) with a blocking disk (9) projecting into the blocking chamber (7), and wherein the centrifuge (1) comprises a channel (11) which opens into the blocking chamber, characterized in that the arrangement comprises a feed line (31) for introducing blocking gas (13) into the blocking chamber (7), which extends between the gas reservoir (30) and the channel (11).

7. Arrangement according to claim 6, characterized in that the arrangement comprises a control unit (40).

8. Arrangement according to claim 6 or 7, characterized in that the channel (11) is arranged in the inlet pipe (4), in particular parallel to the axis of rotation (3) of the drum (2).

9. Arrangement according to one of the preceding claims, characterized in that the centrifuge (1) comprises a hood (21) enclosing the drum (2), wherein the hood (21) comprises a gas outlet, preferably a valve (16) for discharging gas at excess pressure.

10. Arrangement according to one of the preceding claims, characterized in that the channel (11) opens into a region outside the hood (21) of the centrifuge (1).

11. Arrangement according to one of the preceding claims, characterized in that the arrangement comprises a flow meter for determining the supplied volume or mass flow of blocking gas.

12. Arrangement according to one of the preceding claims, characterized in that the centrifuge (1) has a hydrohermetic seal (26).

13. Arrangement according to claim 12, characterized in that the hydrohermetic seal is arranged between the gripper (8) and the blocking chamber (7).

14. Use of the arrangement according to claim 6 in beverage processing and / or in the chemical synthesis of a compound, in particular of a pharmaceutical product, in particular under a protective gas.

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