STIRRING DEVICE, STIRRING SYSTEM AND METHOD FOR OPERATING A STIRRING SYSTEM

Description

State of the art

[0001] The invention relates to a stirrer according to the preamble of claim 1, a stirring system according to claim 8 and a method for operating a stirring system according to claim 10.

[0002] Agitators are already known from the prior art, for example DE 10 2013 104 788 A1, in which an agitator shaft is supported by at least one agitator bearing. Particularly with very long agitator shafts, it can be advantageous to support the shaft in a mixing vessel via an additional intermediate bearing. This intermediate bearing is generally designed as a sliding bearing to absorb radial forces and comprises a first bearing bushing, which is rigidly connected to a bearing housing, and a second bearing bushing, which is connected to the agitator shaft. The bearing bushings have running surfaces that are in contact with each other during operation.Since the intermediate bearing is located within the medium being stirred during operation, which, depending on the application, may also have corrosive and / or abrasive properties and high temperatures, the materials used for the intermediate bearing are subject to particularly high demands. These materials must be designed to withstand the expected increased erosion and / or corrosion stresses as well as the corresponding operating temperatures. Depending on the application, bearing bushings are currently used whose running surfaces are made of glass fiber-reinforced polytetrafluoroethylene (PTFE) and / or stainless steel, which, for abrasive conditions, can be coated with a hard layer, for example, of chromium oxide or tungsten carbide. For elevated operating temperatures and / or corrosive environments, bearing bushings with running surfaces made of carbon and / or graphite are predominantly used.For extreme conditions, such as stirring highly concentrated gypsum suspensions, the running surfaces can be made of materials like silicon carbide. A disadvantage of all currently known intermediate bearings for supporting agitator shafts in mixing tanks is that they are not designed for dry running. Therefore, when the agitator is first commissioned, if there is no hydrodynamic lubrication between the running surfaces by the medium, plastic bearing bushings must initially be used. These must then be replaced with bearing bushings made of the aforementioned materials before actual operation, resulting in considerable additional effort and thus higher costs during commissioning. Furthermore, conventional intermediate bearings exhibit high wear due to their material properties, which reduces service life and increases the effort required for maintenance and repair.Furthermore, conventional intermediate bearings for high-temperature applications with carbon and / or graphite bearing surfaces can only withstand very low surface pressures, which necessitates a large bearing height to withstand the resulting surface pressures. This, in turn, leads to significantly higher costs for the other components of the intermediate bearing, such as the bearing housing, which are often made of chemically resistant and therefore expensive materials, such as titanium.

[0003] The object of the invention is, in particular, to provide a generic device with advantageous efficiency characteristics. This object is achieved according to the invention by the features of claims 1, 8, and 9, while advantageous embodiments and further developments of the invention can be found in the dependent claims. Advantages of the invention

[0004] The invention relates to an agitator with at least one intermediate bearing, which is provided for supporting an agitator shaft within a mixing vessel and which has a first bearing element and a second bearing element, which in an operating state is rotatable relative to the first bearing element about a bearing axis and is in contact with the first bearing element.

[0005] It is proposed that at least one of the bearing elements contains polycrystalline diamond.

[0006] Such a design advantageously allows for the provision of an agitator with improved efficiency. In particular, it enables the provision of an agitator with exceptionally high mechanical strength and excellent chemical resistance, thereby achieving advantageously long service lives and low-maintenance operation. Furthermore, due to the very high mechanical strength of polycrystalline diamond, an intermediate bearing with a reduced overall height compared to previously known intermediate bearings can be advantageously provided.This can advantageously improve material efficiency, in particular by allowing other components of the intermediate storage, such as a bearing housing, which in an operating state come into contact with media located inside a stirred tank and therefore must be made of chemically particularly resistant and thus sometimes very expensive materials, such as titanium, to be dimensioned accordingly smaller.

[0007] The term "agitator device" shall be understood to mean at least a part and / or an assembly, in particular a subassembly, of an agitator system, especially a reactor. The agitator device may also comprise the entire agitator system.

[0008] The intermediate bearing is designed to support the agitator shaft within a mixing vessel and comprises a first bearing element, a second bearing element, and a bearing housing. The intermediate bearing may also include further components. In the operating state, the second bearing element is rotatable about its bearing axis relative to the first bearing element, the bearing axis preferably being parallel to an axis of rotation of the agitator shaft and particularly preferably coincident with the axis of rotation of the agitator shaft. Preferably, the first bearing element is designed as a stationary bearing element and is connected to the bearing housing, particularly in a rotationally fixed manner. The first bearing element could be materially bonded to the bearing housing, for example, by welding.Preferably, the first bearing element is positively and / or non-positively connected, and in particular detachably, to the bearing housing, for example via a screw connection and / or a tongue-and-groove connection and / or a key and / or fastening pins and / or the like. Preferably, the second bearing element is designed as a movable bearing element and is connected to the agitator shaft in the assembled state of the agitator device. The second bearing element could be materially bonded to the agitator shaft in the assembled state, for example, welded to the agitator shaft. Preferably, the second bearing element is positively and / or non-positively connected, and in particular detachably, to the agitator shaft in the assembled state. It would be conceivable, for example, that the second bearing element could be shrunk onto the agitator shaft and thereby non-positively connected to it.Particularly preferably, the intermediate bearing for a positive-locking and / or force-locking connection of the second bearing element to the agitator shaft comprises a shaft sleeve, wherein, in the assembled state, the second bearing element rests with a first side axially in the direction of the agitator shaft against a shoulder of the agitator shaft, and the shaft sleeve connects to the second bearing element on a second side opposite the first side axially in the direction of the agitator shaft, holding the second bearing element in position axially. The shaft sleeve is preferably connected to the bearing housing, for example by means of a screw connection or the like. The first bearing element comprises a first base body and at least one first contact element, preferably a plurality of first contact elements. The second bearing element comprises a second base body and at least one second contact element, preferably a plurality of second contact elements.The first contact element of the first bearing element and the second contact element of the second bearing element are designed to perform a relative movement, in particular a rotational movement about the bearing axis, with respect to each other during operation and to be in contact with each other at least temporarily. The first bearing element, in particular the at least one first contact element of the first bearing element, and the second bearing element, in particular the at least one second contact element of the second bearing element, can be in contact directly or indirectly during operation, i.e., in the case of hydrostatic or hydrodynamic lubrication, via a lubricating film of lubricant.The contact elements of the respective bearing elements could be formed integrally with the respective base body of the bearing element and, for example, form part of a surface of the respective base body and / or be applied as a coating to the respective base body. "Integral" is understood to mean at least a materially bonded connection, for example, by a welding process, an adhesive bonding process, an injection molding process, a coating process, and / or another process that would appear appropriate to a person skilled in the art, and / or advantageously formed in one piece, such as by being manufactured from a single casting and, advantageously, from a single blank. Preferably, the respective contact elements are formed separately from the respective base body and firmly connected to the respective base body, for example, by being pressed into corresponding recesses in the base body by means of a form-fit and / or force-fit connection.The first bearing element and / or the second bearing element comprise polycrystalline diamond and could, in particular, be made entirely of polycrystalline diamond. Preferably, however, the first base body of the first bearing element and / or the second base body of the second bearing element is made of a material other than polycrystalline diamond, for example, a metal and / or a metal alloy, such as stainless steel, titanium, or Hastelloy, preferably titanium. Preferably, the at least one first contact element of the first bearing element and / or the at least one second contact element of the second bearing element is made of polycrystalline diamond. "Polycrystalline diamond" (PCD) refers to...In this document, PCD refers to a synthetically produced material, in particular by means of a sintering process at high pressure and high temperature, which has a metal matrix, for example made of cobalt, in which an intergrown structure of, in particular synthetically produced, diamond particles is arranged.

[0009] In this document, "at least substantially" means that a deviation from a specified value is less than 25%, preferably less than 10%, and particularly preferably less than 5% of the specified value.

[0010] In this document, numerical prefixes such as "first" and "second" serve solely to distinguish between objects and / or to indicate relationships between objects, and do not imply a total number or ranking of the objects. In particular, a "second object" does not necessarily imply the existence of a "first object".

[0011] The term "intended" should be understood to mean specifically designed and / or equipped. The fact that an object is intended for a specific function should be understood to mean that the object fulfills and / or performs this specific function in at least one application and / or operating state.

[0012] The first bearing element or the second bearing element could be designed without polycrystalline diamond. For example, it would be conceivable that the first contact element of the first bearing element or the second contact element of the second bearing element is made of the same material as the respective base body of the respective bearing element. It would also be conceivable that the first contact element of the first bearing element or the second contact element of the second bearing element is made of a material other than polycrystalline diamond, for example, polytetrafluoroethylene (PTFE) and / or tungsten carbide and / or chromium oxide and / or silicon carbide and / or boron nitride and / or another material that would appear suitable to a person skilled in the art. In an advantageous embodiment, however, it is proposed that both bearing elements comprise polycrystalline diamond.This allows for the advantageous provision of an intermediate bearing with particularly high mechanical load-bearing capacity. This, in turn, further increases the efficiency of the agitator device and achieves a particularly long service life for the intermediate bearing. Preferably, the at least one first contact element of the first bearing element and the at least one second contact element of the second bearing element are each made of polycrystalline diamond.

[0013] Furthermore, it is proposed that the intermediate bearing be designed for dry running. Such a design can further improve efficiency. In particular, simplified and rapid commissioning of a mixing system with an agitator device can be achieved if the intermediate bearing is designed for dry running, since the intermediate bearing can be commissioned in dry running conditions, without hydrostatic or hydrodynamic lubrication between the bearing elements. This eliminates the otherwise necessary use and subsequent replacement of plastic bearing bushings during commissioning. In dry running conditions, the at least one first contact element of the first bearing element and the at least one second contact element of the second bearing element are in direct mechanical contact, at least temporarily, meaning without a lubricating film between the first and second contact elements.Furthermore, the intermediate bearing is designed for wet operation, with a lubricating film present between the contact elements. Preferably, the intermediate bearing is designed as a hydrodynamic sliding bearing, wherein, during operation, a lubricating film is formed between the first contact element of the first bearing element and the second contact element of the second bearing element by a medium located within the mixing vessel. Alternatively, it is also conceivable that the intermediate bearing is designed as a hydrostatic sliding bearing and has at least one lubrication circuit with a pump for supplying a lubricant different from the medium in the mixing vessel into a bearing gap between the first and second bearing elements.

[0014] Furthermore, it is proposed that the coefficient of friction between the first and second bearing elements in dry running is at most 0.08. This advantageously enables dry running with particularly low frictional wear. A particularly reliable and durable intermediate bearing can thus be provided. In particular, the coefficient of friction between the first and second bearing elements in dry running is at most 0.07, advantageously at most 0.06, particularly advantageously at most 0.05, preferably at most 0.04, and most preferably at most 0.03. In wet running with hydrodynamic lubrication, the coefficient of friction between the first and second bearing elements is negligibly low and is particularly at most 0.002.

[0015] Furthermore, it is proposed that the first and second bearing elements have a compressive strength of at least 5.0 GPa. Such a design advantageously provides an intermediate bearing that can withstand particularly high surface pressures, thereby significantly reducing the overall height of the intermediate bearing compared to conventional intermediate bearings for high-temperature applications with carbon and / or graphite contact elements. This also results in further advantageous material and thus cost savings, particularly since the intermediate bearing can be dimensioned smaller overall, thus reducing material costs for other components of the intermediate bearing, such as the bearing housing.The first bearing element and the second bearing element have, in particular, a compressive strength of at least 5.5 GPa, advantageously of at least 6 GPa, particularly advantageously of at least 6.5 GPa, preferably of at least 7.0 GPa and particularly preferably of at least 7.5 GPa.

[0016] Furthermore, it is proposed that the first and second bearing elements have a thermal conductivity of at least 400 W / mK. This advantageously allows for particularly good heat dissipation. It is advantageous, especially during starting and stopping of the agitator shaft's rotation and during dry running, to reduce, and preferably minimize, the probability of unwanted local friction welding between the contact elements of the first and second bearing elements, which leads to scoring and abrasion. This further improves the service life of the intermediate bearing and enables particularly efficient operation. The first and second bearing elements have a thermal conductivity of at least 425 W / mK, advantageously at least 450 W / mK, particularly advantageously at least 475 W / mK, preferably at least 500 W / mK, and most preferably at least 525 W / mK.

[0017] Furthermore, it is proposed that the intermediate storage unit exhibits a heat resistance of at least 250°C. This advantageously enables the provision of an agitator device for reliable use in high-temperature applications, for example, for carrying out stirring processes and / or chemical reactions at high temperatures. The intermediate storage unit, in particular, exhibits a heat resistance of at least 260°C, advantageously at least 270°C, particularly advantageously at least 280°C, preferably at least 290°C, and most preferably at least 300°C. The term "heat resistance" here and in the following refers to the resistance of an object, in particular a material and / or component, to temperature effects and is characterized by a temperature below which the temperature-dependent properties of the object change only insignificantly and only within the tolerances permissible for the respective application of the object.

[0018] Furthermore, it is proposed that the intermediate bearing be designed as a radial bearing, wherein the first bearing element is a stationary outer ring and the second bearing element is a movable inner ring. Such a design advantageously provides a reliable intermediate bearing for absorbing radial forces using particularly simple technical means. Alternatively, the intermediate bearing could also be designed as a radial and axial bearing, wherein the first bearing element could have at least one first radial contact element for absorbing radial forces and at least one first axial contact element arranged perpendicular to the first radial contact element for absorbing axial forces, and the second bearing element could have at least one second radial contact element for absorbing radial forces and at least one second axial contact element arranged perpendicular to the second radial contact element.

[0019] The invention further relates to a stirring system, in particular a reactor, comprising a stirred tank and an agitator arranged in the stirred tank according to one of the previously described embodiments. Such a stirring system is characterized in particular by the aforementioned advantageous properties of the agitator. In addition to the stirred tank and the agitator, the stirring system may include further units and / or elements. Preferably, the stirring system comprises an agitator that includes the agitator and, furthermore, but not limited thereto, the agitator shaft, a drive unit with a drive motor for driving the agitator shaft, and at least one stirring element arranged on the agitator shaft.

[0020] The invention further relates to a method for operating the previously described stirring system, wherein the stirring vessel is filled with a corrosive and / or abrasive medium. By means of such a method, reliable operation of the stirring system can advantageously be achieved even under particularly high demands on mechanical and / or chemical resilience, especially under increased erosion and / or corrosion stress, of the stirring system, and in particular of the stirring device.The method for operating the stirring system can be used, but is not limited to, for example in the production of terephthalic acid, where acetic acid is used as a solvent in the corrosive medium, or in the processing of ores, for example for the hydrometallurgical extraction of zinc, nickel or copper using sulfuric acid, where the medium may be abrasive in addition to corrosive properties due to suspended ore particles.

[0021] Furthermore, it is proposed that the medium have a temperature of at least 180°C. This advantageously enables reliable operation of the stirring system even under high demands on the temperature resistance of the stirring system, particularly the agitator assembly. Preferably, the medium has a temperature between 190°C and 210°C. However, the medium can also have temperatures higher than 210°C. For example, in the production of terephthalic acid, it may be necessary to remove acetic acid and dissolve the crude terephthalic acid in water at temperatures of approximately 250°C.

[0022] The agitator device and agitator system according to the invention are not to be limited to the applications and embodiments described above. In particular, the agitator device and / or the agitator system according to the invention may, to achieve a functionality described herein, comprise a different number of individual elements, components, and units than that specified herein. Drawings

[0023] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0024] They show: Fig. 1 a stirring system with a mixing vessel and a stirring device arranged therein in a schematic representation, Fig. 2 the stirring device with an intermediate bearing in a schematic perspective view, Fig. 3 the intermediate bearing in a schematic sectional view, Fig. 4 a first bearing element and a second bearing element of the intermediate bearing in a schematic exploded view and Fig. 5 a schematic process flow diagram of a method for operating the stirring system. Description of the exemplary embodiment

[0025] Fig. 1Figure 3 shows a stirring system 30. The stirring system 30 is designed as a reactor, specifically a stirred reactor. In this case, the stirring system 30 is intended, for example, for the production of terephthalic acid, a precursor of polyesters such as polyethylene terephthalate (PET). However, in addition to the production of terephthalic acid, the stirring system 30 can also be used for other applications, such as the hydrometallurgical processing of ores.

[0026] The stirring system 30 includes a stirred tank 16. The stirred tank 16 is designed to hold at least one medium 32. For the production of terephthalic acid, the medium in the stirred tank 16 can, for example, comprise para-xylene and acetic acid as a solvent.

[0027] The stirring system 30 comprises an agitator 34 with a stirring shaft 14, a drive unit 54 for driving the stirring shaft 14, and stirring elements 36 arranged thereon for mixing the medium 32. In an operating state of the stirring system 30, the drive unit 34 drives the stirring shaft 14 to a rotary movement about a stirring axis 56.

[0028] The stirring system 30 comprises a stirring device 10. The stirring device 10 is arranged in the stirring vessel 16.

[0029] The agitator device 10 comprises at least one intermediate bearing 12. The intermediate bearing 12 is provided for supporting the agitator shaft 14 within the agitator vessel 16. The intermediate bearing 12 is connected to the agitator vessel 16 via fastening struts 58.

[0030] Figure 2Figure 1 shows the agitator device 10 with the intermediate bearing 12 in a schematic perspective view. The intermediate bearing 12 has a bearing housing 38. The intermediate bearing 12 has a shaft sleeve 48 which partially surrounds the agitator shaft 14 in a mounted state of the agitator device 10, specifically radially along a section of the agitator shaft 14 running below the bearing housing 38. The shaft sleeve 48 is detachably connected to the bearing housing 38 by means of screw connections.

[0031] Figure 3 shows a schematic sectional view through intermediate storage facility 12. The section plane of the [unclear text] in the Figure 3 The section view shown runs parallel to a bearing axis 22 of the intermediate bearing 12. In this case, the bearing axis 22 is identical to the agitator axis 56 (see figure). Figure 1) of the agitator shaft 14. The intermediate bearing 12 has a first bearing element 18 and a second bearing element 20. In an operating state of the agitator device 10, the second bearing element 20 is rotatable about the bearing axis 22 relative to the first bearing element 18. In this operating state, the second bearing element 20 is in contact with the first bearing element 18.

[0032] At least one of the bearing elements 18, 20 contains polycrystalline diamond. In the present case, both bearing elements 18, 20 contain polycrystalline diamond.

[0033] In this case, the intermediate bearing 12 is designed as a radial bearing. The first bearing element 18 is designed as a stationary outer ring 24. This first bearing element 18, designed as a stationary outer ring 24, is rotationally fixed to the bearing housing 38 in the circumferential direction about the bearing axis 22 via fastening pins 40. The second bearing element 20 is designed as a movable inner ring 26. The second bearing element 20, designed as a movable inner ring 26, is arranged within the first bearing element 18, designed as a stationary outer ring 24, in a direction perpendicular to the bearing axis 22.

[0034] The agitator shaft 14 has a shoulder 42. Above the shoulder 42, the agitator shaft 14 has a first shaft diameter 44. Below the shoulder 42, the agitator shaft 14 has a second shaft diameter 46, which is smaller than the first shaft diameter 44. In the assembled state, the second bearing element 20, designed as a movable inner ring 26, rests with its upper surface against the shoulder 42. In the assembled state, the second bearing element 20 is attached to the agitator shaft 14 in the axial direction of the bearing axis 22 by means of the shaft sleeve 48. A difference between an outer diameter and an inner diameter of the movable inner ring 26 corresponds at least substantially to a difference between the first shaft diameter 44 and the second shaft diameter 46 of the agitator shaft 14. An inner diameter of the stationary outer ring 24 corresponds at least substantially to the first shaft diameter 44 of the agitator shaft 14.

[0035] Figure 4 Figure 1 shows the first bearing element 18 and the second bearing element 20 of the intermediate bearing 12 in a schematic exploded view. The first bearing element 18, designed as a stationary outer ring 24, has a first base body 60. The first bearing element 18, designed as a stationary outer ring 24, has at least one first contact element 62. In this case, the first bearing element 18 has a plurality of first contact elements 62. The first contact elements 62 are arranged at regular intervals along a circumferential direction on an inner surface of the first base body 62.

[0036] The second bearing element 20, designed as a movable inner ring 26, has a second base body 64. The second bearing element 20, designed as a movable inner ring 26, has at least one second contact element 66. In this case, the second bearing element 20 has a plurality of second contact elements 66. The second contact elements 66 are arranged at regular intervals on an outer surface of the second base body 64.

[0037] Of the objects that appear multiple times in the figures, only one is marked with a reference symbol.

[0038] The first base body 60 of the first bearing element 18 and the second base body 64 of the second bearing element 20 are each made of a metal and / or a metal alloy, in this case titanium. The first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20 are each made of polycrystalline diamond. The first contact elements 62 are pressed into corresponding recesses in the first base body 60 by means of a positive and / or non-positive connection. The second contact elements 66 are also pressed into corresponding recesses in the second base body 64 by means of a positive and / or non-positive connection.

[0039] In the operating state of the agitator device 10, the first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20 are in contact with each other, wherein the second contact elements 66 of the second bearing element 20, designed as a movable inner ring 26, rotate about the bearing axis 22 relative to the first contact elements 62 of the stationary outer ring 24 (see figure). Figure 3 ) be moved.

[0040] The intermediate bearing 12 is designed for dry running. During dry running, the first bearing element 18 and the second bearing element 20, specifically the first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20, are in direct contact, and solid friction exists between the first contact elements 62 and the second contact elements 66. During dry running, the coefficient of friction between the first bearing element 18 and the second bearing element 20, specifically between the first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20, is at most 0.08.

[0041] The intermediate bearing 12 is also designed for wet operation. In wet operation, the intermediate bearing is hydrodynamically lubricated by the medium 32 located in the agitated vessel 16 (see figure). Figure 1In wet running conditions, a hydrodynamic lubricating film forms between the first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20. In wet running conditions, the coefficient of friction between the first bearing element 18 and the second bearing element 20, specifically between the first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20, is at most 0.002.

[0042] The first bearing element 18 and the second bearing element 20 each have a compressive strength of at least 5 GPa. In this case, the first bearing element 18 and the second bearing element 20 each have a compressive strength between 6.9 GPa and 7.6 GPa. This ensures reliable absorption of radial forces acting on the agitator shaft 14 by the intermediate bearing 12 during operation.

[0043] The intermediate bearing 12 has a heat resistance of at least 250°C. The first bearing element 18 and the second bearing element 20, and in particular the first contact elements 62 of the first bearing element 18 and the second contact elements 66 of the second bearing element 20, each have a thermal conductivity of at least 400 W / mK. In this case, the first contact elements 62 of the first bearing element 18 and the second contact elements 66 each have a thermal conductivity of 543 W / mK.Due to the high thermal conductivities, good and rapid heat dissipation of frictional heat can be achieved in the operating state, particularly when starting and stopping the agitator shaft 14 and during dry running, thus reducing, preferably minimizing, the probability of unwanted local friction welding between the contact elements 62, 66 of the first bearing element 18 and the second bearing element 20, which would lead to scoring and abrasion and thus to premature wear.

[0044] Figure 5Figure 1 shows a schematic process flow diagram of a process for operating the stirring system 30, wherein the stirred tank 16 is filled with a corrosive and / or abrasive medium 32 and wherein the medium 32 has a temperature of at least 180°C. The process comprises at least two process steps. In a first process step 50 of the process, the stirring system 30 is put into operation, wherein the stirred tank 16 is filled with the corrosive and / or abrasive medium 32 and the medium is heated to a temperature of at least 180°C. In this case, the medium 32 is heated to a temperature between 190°C and 210°C. In the production of terephthalic acid, the corrosive and / or abrasive medium 32 can, for example, be acetic acid. In a second process step 52, the medium 32 is stirred in the stirred tank 16 by means of the agitators 36.For example, to produce terephthalic acid, para-xylene is continuously stirred with atmospheric oxygen in acetic acid as a solvent at approximately 15 bar and catalytically oxidized until terephthalic acid precipitates in solid form. Reference sign

[0045] 10 Agitator device 12 Intermediate bearing 14 Agitator shaft 16 Agitator container 18 First bearing element 20 Second bearing element 22 Bearing axle 24 Stationary outer ring 26 Movable inner ring 30 Agitation system 32 Medium 34 Agitator 36 Agitator element 38 Bearing housing 40 Mounting pin 42 Shaft shoulder 44 First shaft diameter 46 Second shaft diameter 48 Shaft sleeve 50 First process step 52 Second process step 54 Drive unit 56 Agitator axle 58 Mounting strut 60 First base body 62 First contact element 64 Second base body 66 Second contact element

Claims

1. Agitator, with an agitator shaft (14) and with at least one intermediate bearing (12) supporting the agitator shaft (14) within an agitation tank (16) and having a first bearing element (18) and a second bearing element (20) which, in an operating state, is rotatable relative to the first bearing element (18) around a bearing axis (22) and is in contact with the first bearing element (18), characterized in that at least one of the bearing elements (18, 20) comprises polycrystalline diamond, wherein the intermediate bearing (12) is configured as a radial bearing, and wherein the first bearing element (18) is configured as a stationary outer ring (24) and the second bearing element (20) is configured as a movable inner ring (26).

2. Agitator as claimed in claim 1, characterized in that both bearing elements (18, 20) have polycrystalline diamond.

3. Agitator as claimed in claim 1 or 2, characterized in that the intermediate bearing (12) is designed for dry running.

4. Agitator as claimed in claim 3, characterized in that a coefficient of friction between the first bearing element (18) and the second bearing element (20) during dry running is at most 0.08.

5. Agitator as claimed in any one of the preceding claims, characterized in that the first bearing element (18) and the second bearing element (20) have a compressive strength of at least 5 GPa.

6. Agitator as claimed in any one of the preceding claims, characterized in that the first bearing element (18) and the second bearing element (20) have a thermal conductivity of at least 400 W / mK.

7. Agitator as claimed in any one of the preceding claims, characterized in that the intermediate bearing (12) has a heat resistance of at least 250°C.

8. Agitation system (30), in particular reactor, having an agitation tank (16) and having an agitator as claimed in any one of the preceding claims arranged in the agitation tank (16).

9. Method for operating an agitation system (30) as claimed in claim 8, wherein the agitation tank (28) is filled with a corrosive and / or abrasive medium (32).

10. Method as claimed in claim 9, characterized in that the medium (32) is at a temperature of at least 180°C.