EP2772310A2 - Method for processing combustible products with a separator assembly - Google Patents

Abstract

The method involves utilizing a rotatable drum (1), which is arranged in a cap space (6). A rotatable drive spindle (3) is placed related to a rotation of a vertical axis (D). A drive chamber (15) is provided with multiple components of a separator drive (23). Negative pressure is generated as low as possible during processing of the cap space and a driver space, and ignition of residual gases is exicited by a separator. An explosion boundary is used as a command variable for control of the negative pressure. An independent claim is also included for a method for operating of a separator.

Description

The invention relates to a method for processing combustible products with a Separatoranordnung.

When processing combustible products with a Separatoranordnung, it is possible that form explosive gases or gas mixtures. These arise in particular by outgassing volatile constituents of a combustible product and mixing with existing atmospheric oxygen in the separator arrangement. It is therefore necessary to design the separator arrangement in such a way that it meets the legal requirements for explosion protection, which requires that components of the system be designed accordingly and / or the risk of explosion reduced by the supply of inert gas, which u.U. caused significant additional costs.

The invention has the task of simplifying the processing of such products against this background.

The invention solves this problem by the subject matter of claim 1.

Advantageous embodiments of the invention can be found in the dependent claims.

Thereafter, in the method according to the invention (claim 1), the ambient space during the centrifugal separation and / or clearing of the hood and / or - after an advantageous alternative or possibly also training - the drive space set under negative pressure to the environment. This prevents a processing of combustible products by reducing the oxygen content in the hood space and / or in the drive space that an explosion occurs at all or that an explosion is triggered, which assumes a damaging or endangering level. Although it is known per se to generate explosion protection generally in containers a negative pressure. In a method for processing a combustible product in a continuous operation on a separator, however, this effect has not been used, although after the recognition of the invention in the continuous processing either in the ambient space the hood and / or generate in the drive space sufficient negative pressure to meet the requirements for explosion protection, in particular, if preferably and advantageously in the hood space and / or in the drive space, a negative pressure is generated, which is so low that for that too processing product at the air pressure generated by negative pressure below the expected explosive limit in air at this air pressure. In this context, it makes sense to use the corresponding value of the explosion limit as a reference variable for a regulation of the negative pressure.

Dome space refers to the space of a centrifuge in which the drum rotates and in which thus the product to be separated is processed. Preferably, the drum is suitable for discharging a solid, so that by opening a piston valve, the solid is discharged discontinuously or, alternatively, can be discharged continuously by means of nozzles.

In order to keep the value of the negative pressure in this way at the respectively suitable value, pressure monitoring in the region (s) in which a negative pressure is generated is expedient and advantageous.

It is also conceivable first to fill the area to be evacuated with inert gas and then to generate a negative pressure. In this way, the risk of explosion is reduced again. In addition, filling with inert gas makes sense in the event of an error, that is, in the event of an unforeseen increase in pressure, as a safety measure.

For this time-limited inertization preferably no permanent inert gas supply is used, but an inert gas supply from a bottle is used.

It is also conceivable and advantageous to fill the hood space with an inert gas for explosion protection and to generate a negative pressure in the drive space. In this way it is particularly easy to achieve explosion protection in the hood space with the inert gas, whereas it seems less sensible to fill the drive space with inert gas. There, it makes more sense and advantageous to generate a negative pressure to achieve a good explosion protection in a simple manner, especially in the drive room in terms of there in the rule he electrical equipment. For the electrical equipment are preferably no additional explosion protection applied, eg intrinsically safe components, equipment with increased safety or flameproof enclosure. The negative pressure in the Separatorräumen is preferably monitored by measurements and / or controlled or regulated. When the negative pressure rises above a limit value, in particular above 0.25 bar or above 0.3 bar, or before the separator is shut down (or continuously during the centrifugal separation only in the hood space), an inert gas is achieved until the atmospheric pressure is reached, in particular supplied to a pressure of at least 50 mbar above atmospheric pressure. Preferably, however, a pressure of 0.5 bar above atmospheric pressure is not exceeded.

As inert gases preferably instrument air, nitrogen, helium or carbon dioxide are used.

Although it is already known that in various applications of separators, so in particular in the field of medical or food technology or in the field of milk processing centrifuge drums are arranged and operated in a space having a relative to the environment a negative pressure. Purely by way of example is in the extent to the EP 1 119 416 B1 directed. The separator assembly shown in this document and its used in practice counterpart have a separator drum for liquid / liquid / solid separation with a vertical axis of rotation, which is arranged in a sealed container or hood space, in which a vacuum with a pump can be generated against the environment. The separator drum has an inlet pipe and one or more peeling disks for discharging the one or more liquid phase (s), as well as solids discharge openings for the continuous or intermittent discharge of solids. However, it has hitherto not been recognized that by means of negative pressure, a particularly advantageous processing of a product which possibly develops flammable gases during operation is also possible. An Intergaszufuhr, at least a continuous supply of inert gas, is no longer necessary.

According to the invention, a negative pressure according to the specification of claims 1 or 2 relative to the environment is preferably also in the components of the drive device - in particular motor, clutch, spindle, bearing and / or other drive components - containing space entirely or at least in a partial area generated in order to exclude the danger of explosion also in the drive space or at least to decrease enough. The drive components can be used in this case in standard design, that is in non-explosion-proof design. For example, a motor does not have to be used as a pressure-tight encapsulated type.

For this purpose, the drive space area is evacuated with a pump or other vacuum generating device and / or it is connected to the (hood) space which surrounds the drum, so that a pump or a corresponding device, which optionally complementary in this room creates a vacuum, even in the drive space "with" can create a vacuum. Although the hood space, in which the drum is arranged, is placed under negative pressure to the environment, a reduction of the risk of explosion - accompanied by an energy saving - can be achieved here as well. A sealed embodiment of the drum is not preferred.

Particularly advantageous is a preferred variant of the method in which in each of the hood space and the drive space, a negative pressure is generated and in which the negative pressure in the hood space and the drive space at least temporarily or permanently during the centrifugal clearing and / or separation during operation is different. Thus, the negative pressure in the drive chamber can be constant, during which the underpressure in the hood space is changed during operation as a function of the current or expected operating state, for example, before draining with a piston valve is increased in order to achieve a particularly stable operation. The reverse variant with constant pressure in the hood space or varying pressure in the hood space is conceivable. Finally, in both areas of operation, the pressure can be changed if they are in pressure-compensating connection.

In addition, the negative pressure in the two areas may also be permanently different in operation, if this nevertheless satisfies the explosion protection. Especially in the latter case, it is advantageous if a blocking chamber is provided, in particular, with two axially spaced sealing ring arrangements and a chamber formed between them, which is preferably filled with a fluid such as an inert gas (and thus filled during operation) and preferably between the drive space and the hood space is formed. Preferably, the two Rooms drive room and hood space hereby separated and sealed from each other. The barrier chamber is then preferably inserted between the rotating spindle and a fixed drive cover.

It is also advantageous, if a pressure-tight encapsulated drive motor is used.

According to a variant which also forms an independent invention, it is particularly advantageous to provide a vacuum connection on a particularly large radius in the hood space, since here the drum rotation has a supporting effect on the generation of the vacuum. Preferably, both the drum and the hood space are partially conical.

A variant for a vacuum connection may be a connection via a bore in the spindle. In this case, the free end of the spindle is guided down through the sealed frame wall and via sealed connections, the connection to a vacuum system. The hole in the spindle ends in the area below the drum in the hood area. The implementation of the spindle through the frame wall is also sealed by means of sliding elements.

As liquid drains in the drum are usual peeling discs. But it is also a seal / isolation of the gripper / drum by means of a dip disk conceivable. The sealing by means of immersion disk takes place by immersing a stationary disk in a rotating liquid level, so that a liquid seal is formed to the environment on one side of the disk in relation to the other side of the disk. As the liquid medium, both a clarified liquid phase and a separately introduced neutral phase are suitable, e.g. Water. In this case, the product areas and the area of the immersion disk are separated from each other.

By an advantageous sealed Separatorsanordnung and the monitoring of the negative pressure, it is possible to turn off the vacuum generating means after reaching the set limit value for the negative pressure and turn on again after exceeding the limit value. As described above, before initiating emptying of the solids space of a separator drum closable with spool valve, the vacuum generating means can be activated and / or Inert gas can be added. After reaching the predetermined limits for the vacuum after completion of the Entleerungsvorgangs the vacuum generating means can be turned off again. This allows further optimization of the consumption of inert gas and energy.

Particularly advantageous is the use of a fluid, especially oil or water cooled engine.

• Ölumlaufpumpe im Vakuumbereich
• Ölbehälter im Vakuumbereich,
• Wärmetauscher (für Ölkreislauf) im Vakuumbereich

It also appears advantageous to arrange the oil lubrication system, in particular a circulation lubrication system, in the vacuum region, in particular with one or more of the following features:

• Oil circulation pump in the vacuum range
• Oil tank in the vacuum area,
• Heat exchanger (for oil circuit) in the vacuum range

Also advantageous is a cooling fluid supply through the drum (according to the type of DE 19922237 ).

In operation, a negative pressure is generated which is below atmospheric pressure, in particular of 0.2 bar or less.

In addition, it is particularly advantageous if a negative pressure is generated during operation, which is in particular 0.1 bar or less, in particular less than 50 mbar. Since the pressure in an explosion typically increases to ten times the prevailing pressure before the explosion, such a pressure increase would be harmless.

It is also conceivable if the value of the negative pressure is changed in any case in the hood space with the drum during operation depending on the operating condition. Thus, for example, before, during or after a change in the operating state, a change in the negative pressure take place. In this case, the change in the operating state, which takes place before, during or after the change in the negative pressure, be a solids discharge. For example, the negative pressure when starting or braking the drum can be changed. He could also be slightly increased shortly before or at least during emptying, so that no adverse effects due to the high negative pressure occur during the solids discharge

The invention is particularly suitable for a Separatoranordnung with a separator with a drum with a vertical axis of rotation, which is mounted on a rotatable drive spindle and surrounded by a hood, the drums a drum diameter greater than 500 mm, in particular 800 mm, most preferably greater than 900 mm and / or speeds, for example greater than 8000 rpm, 5000 rpm, 4000 rpm in operation.

Preferably, the peripheral speed at the drum outer diameter is at least 100 m / s or more.

The surface of the drum is further preferably 0.5m ² to 5m ² , especially 1-3.5m ² , so that the effect of supporting the generation of negative pressure has a particularly advantageous effect.

Further advantageous embodiments are specified in the remaining subclaims.

Fig. 1

eine schematische Darstellung einer ersten Separatoranordnung mit einem im Schnitt dargestellten Antriebsraum;

Fig. 2

eine schematische Darstellung einer zweiten Separatoranordnung mit einem im Schnitt dargestellten Antriebsraum; und

Fig. 3

eine schematische Darstellung einer dritten Separatoranordnung mit einem im Schnitt dargestellten Antriebsraum.

The invention will be described in more detail with reference to the drawing with reference to an embodiment. Show it:

Fig. 1

a schematic representation of a first separator assembly with a drive space shown in section;

Fig. 2

a schematic representation of a second separator assembly with a drive space shown in section; and

Fig. 3

a schematic representation of a third separator arrangement with a drive space shown in section.

Fig. 1 shows an embodiment of a separator 1 for carrying out the method according to the invention.

With the separator assembly 1, a flammable and in operation possibly flammable gases developing product P is processed or processed.

The product to be processed may be a product to be clarified or separated into different phases (with different density) and, if appropriate, also to be clarified. In this respect, a product mixture of several substances is to be regarded as a product. A preferred application is the separator assembly 1 in such a preparation of an alcoholic product, such as a beverage, or for example in the processing or production of fuels.

Examples of gases or gas mixtures which may arise from the following substance groups by exceeding the flash point: Aliphatic hydrocarbons, such as alkanes, such as propane, alkenes, alkynes; Alcohols, such as methanol, ethanol; Solvents, such as acetone, toluene, n-hexane, benzene, etc. The invention is particularly suitable for the processing of products, in the processing of one or more of these gases may arise.

Whenever the product temperature to be processed is above the flash point, the gases and vapors that can form an explosive mixture with oxygen (from the air) form. Examples of these areas are: substance Flash point ethanol 12 ° C Methyl alcohol (methanol) 11 ° C isopropanol 12 ° C n-hexane -22 ° C Diesel fuel > 55 ° C biodiesel 180 ° C 1-butanol 34 ° C

Depending on the substance content in the product, different flash points result: For example, the flash point for 5% ethanol in water is 81 ° C. The flash point for 50% ethanol in water is 24 ° C. Lowering the pressure causes the flashpoint to drop again.

Thus, it is possible to calculate the flash point for respective current conditions, for example by means of Raoult's laws known to the person skilled in the art, which will therefore not be discussed in more detail here, which then enters into the regulation of the process.

As a result, the necessary negative pressure at a known separation temperature for a mixture of substances can be determined exactly and approached by means of control device in operation and comply to avoid an explosive atmosphere.

The separator assembly 1 has a separator with a vertical axis of rotation D, which includes a rotatable drum 2, which is mounted on a rotatable drive spindle 3.

The product feed of the product P which can be processed or processed in continuous operation and which develops flammable gases is preferably carried out from above through a feed pipe 4 (not shown in detail here).

This structure is preferred. But it is also a hanging drum with a drive above the drum feasible. The supply of the product through the spindle is conceivable.

The drum 2 is here designed to separate the product P to be processed into at least one liquid phase L or several liquid phases and a solid phase S. It points here like the drum of the EP 1 119 416 B1 or the pendant used in practice in the interior, preferably a separation plate stack of separation plates (not visible here).

The liquid phases L are discharged from the drum 2 via liquid outlets, in particular peeling disks in the manner of a centripetal pump. The derivative of the solid phase S, however, takes place either discontinuously at discontinuously closable solids discharge openings 5 in the drum shell or continuously through nozzles in the drum shell.

The use of a liquid-controlled piston valve in particular appears advantageous.

The drum 2 is inserted in a sealed against the environment hood space 6.

This hood space 6 is here by a hood 7, which is fixed to a foundation - here a machine frame 8 - a cover 9 below the drum, which is fixed to the hood 7 and limited to a spindle housing 10, which is penetrated by the drive spindle 3, set.

In this case, preferably between adjacent elements such as between the hood 7 and the machine frame 8 and between the cover 9 and the hood 7 and between the cover 9 and the spindle housing 10 and between the spindle housing (fixed) and the drive spindle 3 (which is in operation rotates) suitable seals arranged to realize a sealed construction.

In the hood 7, a solids catcher 11 is further formed, which serves to discharge solids emerging from the drum from the hood space by a solids discharge 12.

To the hood space 6 is further connected to a vacuum port 13, a pump 14 a (or other means for lowering the pressure in the hood space 6 relative to the environment), with which in the hood space 6, a negative pressure relative to the environment U outside of the hood space 6 can be generated ,

Preferably, this vacuum port 13 is formed at a position which is relative to the rotation axis D at a relatively large radius Rp, in particular at a radius which is equal to or greater than the largest radius R _{T of} the drum second

By operating at reduced pressure, in particular at a negative pressure, which is preferably more than 0.9 bar lower than the ambient pressure in the environment U, the flammable gas evolving product can be safely processed.

Preferably, at least the hood space 6, in which the drum 2 is arranged and optionally and preferably also a drive space 15, in which one or more components of a Separatorantriebs 16 are arranged so sealed designed so that in turn with at least one further pump 14b or also with the pump 14 a, a negative pressure, in particular a negative pressure of more than 0.2 bar, compared to the ambient pressure in the environment U can be generated or generated in operation, which is so dimensioned that the risk of explosion is negligible.

The drive space 15 is here limited to a drive housing 17, which according to the task, in the drive chamber 15, a negative pressure relative to the environment U to produce again in accordance with sealed design is executed. These are after Fig. 1 between elements of the drive housing 17 in turn suitable seals 18 are formed.

Here, the drive space 15 is bounded by the machine frame 8, as well as closure plates 19, close the openings of the machine frame. At the top, it is bounded by the cover 9 below the drum 2 and the single or multi-part spindle housing 10.

The pump 14 b can be connected to a vacuum port 20 of the drive chamber 15.

In the drive chamber 15, one or more or even all elements of the Separatorantriebs 16 are housed. Only the drive spindle 3 protrudes Fig. 1 out of the drive room with its upper end in the hood space.

Preferably, the spindle bearing is wholly or partially - here both a neck bearing 21 a and a Fußlager 21b - arranged in the negative pressure area. But it is also conceivable that one (in particular the neck bearing 21 a) or both bearings 21 a, b do not belong to this negative pressure range.

The spindle housing 10 rests on the machine frame 8 in a flange area supported by elastic elements 40.

Also preferably arranged in the vacuum region, the drive motor 22 is arranged, which is formed here directly in the axial extension of the drive spindle 3, so that a so-called direct drive for the drum 2 is formed.

The rotor 22a is here attached directly to the drive spindle 3 and the stator 22b is in a motor housing 23, which in turn is fixed to the side facing away from the hood space 6 side of the machine frame 8. Especially such a direct drive is preferably accommodated in the drive space, wherein the electric drive motor 22 but also between the bearings 21 a, b could be arranged (the latter variant not shown here). It is also conceivable to accommodate the drive motor in the negative pressure region of the drive chamber 15, which is connected via a coupling with the drive spindle 3 (also not shown here). It is also conceivable the use of a flameproof motor. In this case, it may be sufficient to generate only the hood space a negative pressure.

In the drive chamber 15, a lubrication system 24 is also arranged, which serves for lubrication of the spindle bearing 21 and / or for the lubrication of components on the engine.

The lubrication system here has a lubricant circuit, which the elements oil reservoir 25, pump 26, supply line 27a, b to the spindle bearing 21, oil collection container 28 which is rotatably connected to the spindle and in which a due to the cup-like design in a radius Oil level is formed, a peeling member 29, which discharges the oil in the collecting container, and a return line 27c, d in the oil tank 25 has. Here, all of these elements of the lubrication system are advantageous and compact in the vacuum region, i. in the drive room, housed. A possibly existing pump motor is in this case also designed as a flameproof motor. (if only the hood area is operated with negative pressure) The drive space can be opened in this case to the environment.

In the drive space also discharge and supply lines 30, 31, 32, 33 of one or more coolant circuits open, here once for the engine 22 and once for the lubrication system 24th

In the machine frame, one or more passage openings 34, 35, 36, 37 are further formed, which ensure that within the drive space 15 as possible no pressure gradients arise.

Since in the drive chamber 15 relative to the environment also a negative pressure is generated, the risk of explosion can be reduced here. It will also be achieved in rotating parts in the drive compartment energy savings during operation.

It should also be mentioned that the entire separator or the machine frame is supported on elastic foot elements 38 on a lost property 39.

To Fig. 2 the hood space 6 and the drive space 15 are not sealed against each other. Here, the example and simply achieved in that the cover 9 below the drum 2 is not radially sealed inside the spindle housing 10 but that between these elements, a gap 42 is formed, which ensures a pressure equalization between the hood space 6 and the drive space 15. In this case, no seal, eg no mechanical seal is needed.

In this way, if necessary, even with only a single pump 14a, the negative pressure in both chambers 6, 15 can be generated simultaneously. But it can also be provided several pumps.

Overall is also after Fig. 2 containing both the area within the hood 7 together with the drive space 15 with one or more especially rotatable drive components, so sealed relative to the environment U of the hood 7, that it is possible, this area with a pump 14a, b, the air / gas the area between the hood 7 and the drum 2 and / or the drive space 15 can pump to put under negative pressure relative to the environment U.

The entire power supply of the engine and the oil supply of the drive (motor) is also after Fig. 2 in the closed drive space 15th

To Fig. 3 on the other hand, no circulation lubrication or no lubricant circulation within the drive space 15 is arranged. The lubricating oil supply and removal takes place in this case via an externally (outside the drive space) installed lubricating oil unit (not shown here).

All separator arrangement of Fig. 1 to 3 also meet the highest energy saving requirements.

It is particularly advantageous to emphasize again that in Fig. 1-3 in each case the pump 14a is arranged to generate the low pressure by suction on a large, in particular the largest radius / diameter of the hood 7.

In particular, the suction takes place at a radius of the hood 7, which is based on the axis of rotation on a radius which is greater than 80%, in particular more than 100%, of the largest drum radius. In this case, the support by the drum differential pressure effect in particular has an advantageous effect.

Also conceivable is / alternatively a vacuum connection to a (not shown here) solid container, which is connected downstream of the discharge line 12.

Also advantageous is one or another vacuum connection in the control water drainage area below the drum (not shown here).

Equally advantageous and structurally simple would be one or a further vacuum connection through the spindle 3 into the drive space 15 (for example a bore in machines with an external oil aggregate).

Further advantageous is a sealed / insulated embodiment of the peeling discs by means of a dip disk. Further advantageous is the use of a hermetic gripper / pump combination (not shown).

Particularly advantageous is a use of a fluid, especially oil or water cooled motor, since the cooling effect is reduced by air by the negative pressure in the drive chamber.

The separator arrangement in the manner of Fig. 1 On the one hand meets energy saving requirements. In addition, the processing of combustible products is prevented by a reduction in the oxygen content in the hood and / or in the drive compartment that an explosion occurs or that an explosion is triggered, which assumes a harmful or hazardous level.

It is also advantageous that in Fig. 1 the pump (14a) is designed to generate the back pressure by suction on a large, in particular the largest diameter of the hood. In particular, the suction takes place at a diameter of the hood, which is based on the axis of rotation on a larger radius than the largest drum radius. In this case, the support by the drum differential pressure effect in particular has an advantageous effect.

Also advantageous is one or another vacuum connection to the pump 14b in the drive space or on a (not shown here solid fuel tank in the center with an "extension tube" of large diameter to "keep clean the vacuum port.

Also advantageous is one or another vacuum port on the pump 14b in the drive space or on a port in the control water drainage area below the drum (also not shown).

Finally, it should be noted that not all products produce an equally high explosion pressure. This can be used in the determination and adjustment of the negative pressure. The one or more vacuum chambers to be set under negative pressure - in particular the hood space and / or the drive space - are designed such that they can temporarily absorb or tolerate a certain overpressure. For example, this pressure can be 0.5 bar, in particular 1 bar. The level of negative pressure can then be chosen and controlled so that it does not exceed 0.5 bar, in particular 1 bar minus the substance-specific explosion pressure. The upper limit as non-harmful pressure of claim 1 for the structure of a separator which is not designed as a pressure device would be defined accordingly, for example as 0.5 bar or 1 bar overpressure, depending on the design of the Separierräume. The maximum occurring explosion pressure of an explosive mixture can - especially depending on the temperature and pressure - determined in the experiment or calculated or possibly looked up in tables. Alternatively to a determination of the negative pressure, z. B. 0.1 or 0.05 bar, then the minimum negative pressure can be determined according to the properties of the processed Separierproduktes as explained above.

reference numeral

axis of rotation

D

liquid phases

L, L1, L2

Surroundings

U

radius

Rp, RT

separator arrangement

1

drum

2

drive spindle

3

product

P

supply pipe

4

solids discharge

5

hood space

6

Hood

7

machine frame

8th

cover

9

spindle housing

10

Solid scavengers

11

derivation

12

connection

13

pump

14a, b

drive space

15

separator drive

16

Antriebsumhausung

17

seals

18

locking plates

19

connection

20

neck bearing

21a

step bearing

21b

drive motor

22

rotor

22a

stator

22b

lubrication system

24

oilcontainer

25

pump

26

supply

27

Oil collector

28

paring element

29

Outgoing and incoming lines

30, 31, 32, 33

Through openings

34, 35, 36, 37

foot elements

38

Lost and Found

39

Elastic elements

40

gap

42

Claims (21)

Method for processing a combustible product which develops explosive gases during processing, in particular a mixture of substances, in continuous operation with a separator arrangement, the separator arrangement comprising at least: a rotatable drum (1) with vertical axis of rotation (D) arranged in a hood space (6) ), which is mounted on a rotatable drive spindle (3), and a drive space (15) containing one, several or all components of a Separatorantriebs (23), characterized in that during processing in one or both areas hood space and drive space Low pressure is generated, which is so low that in operation no or only one of the separator assembly not harmful spark-ignited ignition of the remaining residual gases is possible. A method according to claim 1, characterized in that in the hood space, a negative pressure is generated, which is so low that for the product to be processed at the air pressure generated by negative pressure, the expected explosion limit in air is exceeded. A method according to claim 2, characterized in that the explosion limit is used as a reference variable for a regulation of the negative pressure. Method according to one of the preceding claims, characterized in that the product is clarified with the separator of solids. Method according to one of the preceding claims, characterized in that the product is separated with the separator arrangement in at least two liquid phases of different density. Method according to one of the preceding claims, characterized in that a pressure of 0.1 bar or less than 0.1 bar is generated in the hood space surrounding the drum and possibly the drive space. A method according to claim 6, characterized in that a pressure of less than 50 mbar is generated. Method according to one of the preceding claims, characterized in that the drive space (15) in sealed construction of the drive space (15) is executed and that during operation, a negative pressure in the drive space is generated. Method according to one of the preceding claims, characterized in that the negative pressure with at least one negative pressure generating device, in particular a pump (14a, b, c ..) for generating negative pressure in the sealed drive space (15) relative to the environment (U) outside the Drive space (15) is generated. Method according to one of the preceding claims, characterized in that the hood space (6) and the drive space (17) are sealed relative to each other and that in operation during operation, a different pressure, in particular a different pressure is generated. Method according to one of the preceding claims, characterized in that between the hood space (6) and the drive space (15) with each other at least one connection is formed, so that during operation a pressure equalization between these spaces (6, 15) is realized. Method according to one of the preceding claims, characterized in that the negative pressure in the hood space (6) is changed during operation. Method according to one of the preceding claims, characterized in that in each of the hood space and the drive space, a negative pressure is generated and that the negative pressure in the hood space and the drive space at least temporarily or permanently during the centrifugal clearing and / or separation during operation is different. Method according to one of the preceding claims, characterized in that the negative pressure in the hood space and possibly the drive space is changed during operation as a function of the current or expected operating state. Method according to one of the preceding claims, characterized in that the pressure in the hood space is increased before emptying solids. Method according to one of the preceding claims, characterized in that the pressure in the hood space and optionally in the drive space is lowered before the processing of the product to the negative pressure to be reached. Method according to one of the preceding claims, characterized in that the evacuating area is filled with an inert gas initially or in the case of an error, in particular in the case of an unforeseen pressure increase in the area to be evacuated, and then the negative pressure is generated in order to reduce the risk of explosion. Method according to one of the preceding claims, characterized in that the flash point is calculated and that thereby the necessary negative pressure at a known separation temperature for a product, in particular a mixture is determined, which is approached and maintained by means of control device during operation to an explosive To avoid atmosphere. Method according to one of the preceding claims, characterized in that during the centrifugal separating and / or clarifying the hood space (6) is filled with an inert gas and that in the drive space (15) a negative pressure is generated. Method according to one of the preceding claims, characterized in that a locking chamber in particular with two axially to each other spaced seal ring assemblies and a chamber formed therebetween is formed between the drive space and the hood space, which is preferably filled in operation with a fluid such as an inert gas. Method according to one of the preceding claims, characterized in that a pressure-tight encapsulated drive motor is used.

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