Solid Bowl Screw Centrifuge

Abstract

To provide a solid bowl screw centrifugal separator capable of preventing resonance without passing a rotor's first resonance frequency and of operating at relatively high speed.SOLUTION: A solid bowl screw centrifugal separator has a housing 100 and a rotor 200 rotatable inside a housing. The solid bowl screw centrifuge includes: a rotatable drum 210 which has a cylindrical shape part 211 having a rotary shaft D and length L1 and a conical shape part 212 having length L2, and has length LT (=L1+L2); a liquid discharge part 217 arranged in the cylindrical shape part of the drum; a solid discharge part 218 arranged in the conical shape part of the drum; a screw 230 which is arranged in the drum, is rotatable at differential speed relative to the rotary drum, and forms a rotor together with the drum; two drum bearings 221, 222 (an arrangement interval LL) supporting the drum; and a screw bearing 236 supporting a screw. The interval LL between the drum bearings is below length LT of the drum.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention relates to a solid bowl screw centrifuge according to the preamble of claim 1. [Background technology]

[0002] From European Patent 0 107 470 and US Patent 4 504 262, decanters (solid bowl scoops) It is known to support the drum of a centrifugal separator with a spring. The spring is a coil. The drum bearing is configured as a spring and is aligned radially to the axis of rotation. A threaded bolt passing through the coil spring provides elastic support between the bearing housing of the drum bearing and a support ring, respectively, which is arranged concentrically with the bearing housing and is fixed or connected to the machine frame. In this way, it should be possible to set operating speeds above the main resonant frequencies of the system and therefore to achieve higher drum speeds than in decanters with conventional bearing configurations.

[0003] Bearing arrangements which are suitable for relatively short drums and which are arranged in a suspended rather than supported arrangement are shown in German Patent Publication No. 26 06 589, German Patent Publication No. 31 34 633 and German Utility Model Publication No. 66 09 011. German Patent Publication No. 22 57 513 describes a tubular centrifuge with a cylindrical drum shell. A drum is shown which is conical in cross section only on the inside. US Patent Application Publication No. 2003 / 00325401 is mentioned as background.

[0004] A typical solid bowl screw centrifuge is described in DE 10 2007 042 549. This solid bowl screw centrifuge has a drum with a horizontal axis of rotation and a rotor with a screw disposed within the drum that can rotate at differential speeds relative to the rotating drum. Bearings or bearing arrangements for supporting the drum are provided at the two axial ends of the drum, and spring elements are provided for resiliently supporting the drum on the machine frame or base, at least two of the spring elements supporting the drum being located at each of the two axial ends of the drum, the spring elements being aligned vertically or approximately vertically. The ratio between the length of the rotor or drum and the diameter of the rotor or drum is preferably greater than 2, preferably 2. 5, in particular 3. It is also provided that the spring element is configured as a combination of a spring element and a damping element. This configuration is advantageous in that the ratio of the length of the rotor or bowl to the diameter of the rotor or bowl is preferably greater than 2, preferably greater than 2.5, in particular greater than 3. This is particularly suitable for small solid bowl screw centrifuges because it allows the drum to be operated at operating speeds above the fundamental resonant frequency (rotor natural mode) of the system. Summary of the Invention [Problem to be solved by the invention]

[0005] This design has proven itself. However, there is a further need to improve in a simple manner the design of solid bowl screw centrifuges so that they can generally be operated at relatively high speeds, but without having to go through the first resonant frequency of the rotor. A solution to this problem is the object of the present invention. [Means for solving the problem]

[0006] The present invention solves this object by the subject matter of claim 1. Thus, a solid bowl screw centrifuge is created having a housing and a rotor rotatably mounted within the housing, which has at least the following characteristics: a rotatable drum having an axis of rotation which, when added together, gives the length L of the drum; T Painting The present invention relates to a drum having a cylindrical portion having a length L1 and a conical portion having a length L2, at least one liquid discharge portion disposed in the cylindrical portion of the drum, at least one solid discharge portion disposed in the conical portion of the drum, a screw disposed in the drum and rotatable at a differential speed with respect to the rotatable drum and forming a rotor together with the drum, and a screw having a distance L L The housing includes a plurality of drum bearings for supporting the drum within the housing, and at least one screw bearing for supporting the screw within the drum, the distance L between the drum bearings being spaced apart by 100 mm. L is the length of the drum L T is less than.

[0007] In the conical section having length L2, the drum is configured conically inwardly and outwardly (with respect to the drum shell). Starting with the cylindrical portion of the conical section, the drum diameter decreases as the distance from the outer and inner cylindrical portions increases, resulting in a conical shape. The rotation axis is aligned horizontally, however, the rotation axis can be oriented in another direction, such as vertically.

[0008] This configuration has the advantage that, due to the advantageous arrangement of the drum bearings according to the invention with reduced axial spacing, the first resonant frequency limiting the speed of the drum occurs only at higher speeds than in the case of a larger axial spacing of the bearings. Thus, a solid bowl screw centrifuge configured in this way can be operated at higher / higher speeds and therefore is less susceptible to the disadvantage of drum bearings of conventional configurations. Advantageously, this achieves higher separation performance compared to a solid bowl screw centrifuge of comparable volume equipped with a bearing. The bearings directly adjacent in the axial direction are functionally considered as a single bearing for this application.

[0009] According to the claims, drum bearings are arranged as radial connections between the drum and the housing or between parts rigidly connected to the housing, between elements "drum" and "frame" or "housing" that allow relative rotation.

[0010] In a variation of the preferred embodiment of the present invention, one or both drum bearings and / or At least one or possibly both screw bearings are arranged in the axial region between the solids discharge and the liquid discharge of the drum. The solid bowl screw centrifuge can thus also be advantageously operated at high rotational speeds, since the first resonance frequency of the drum, which normally limits the rotational speed, occurs only at relatively high rotational speeds due to the advantageous arrangement of the drum bearing according to the invention. Furthermore, the drum shaft part configured as axial offset and configured as bearing seat may possibly be dispensed with. This also results in a simplified manufacture of the drum hub and thus of the drum.

[0011] Advantageously improving the performance of solid bowl screw centrifuges is also achieved by axially extending the drum of a solid bowl screw centrifuge with a predefined arrangement of this kind having a drum with a defined radius and with a defined distance between the bearings, resulting in a solid bowl screw centrifuge with a larger volume than was possible with the prior art. g numbers of 5000g-7000g can be easily achieved. The ratio of the length of the drum to the maximum inner diameter of the drum (also called "lambda") can be increased. (I).

[0012] In a further preferred embodiment variant of the invention, and independently of further inventive steps, one or both of the drum bearings and / or at least one screw bearing are Directly adjacent to the area of ​​the liquid discharge and / or solid discharge of the drum. Now, the distances A1 and / or A2 are the distances between the respective axial ends of the drum and the respective drum bearings. and / or preferably between the positions of the drum length L T 0% to 35% of It may preferably be between 0% and 25%, and in this way the advantages of the invention are advantageously achieved, particularly at 25%.

[0013] In a variation of another preferred embodiment of the invention, one of the drum bearings may be located radially outwardly on the drum or drum cover. One of the drum bearings is provided to be arranged radially outwardly on the conical portion of the drum. According to a further development or alternative configuration, it may also be provided that one of the drum bearings is arranged radially outwardly on the cylindrical portion of the drum.

[0014] Also, the drum bearings located radially outward on the conical portion of the drum advantageously have a smaller inner diameter than the cylindrical portion of the drum, thereby reducing bearing stresses and bearing costs, and reducing bearing maintenance or replacement. Furthermore, it can alternatively or optionally be provided that one of the drum bearings can be arranged axially outwards directly on the drum cover. All of these are in accordance with claims 1 and / or 2. Or the invention of claim 2 is an advantageous position that can be advantageously implemented in each case or in combination with each other.

[0015] The drum bearing can be configured in different ways. For example, it may be advantageous to configure the drum bearing as a magnetic bearing. This creates an advantageous self-centering drum bearing under load, which is also particularly suitable for placement on a relatively large radius on a conical or cylindrical section.

[0016] In another advantageous embodiment of the invention, the drum bearing is configured as a roller bearing. This is advantageous for making the drum bearing arrangement easy to construct and install and cost-effective. The drum bearing can be configured as a ceramic bearing, in particular a duplex ceramic bearing. This is easy to construct and install and then produces an advantageous low-wear drum bearing arrangement that is particularly suitable for installation on a relatively large radius on a conical or cylindrical section. Further advantageous configurations of the invention are found in the dependent claims. [Brief description of the drawings]

[0017] In the following, the invention is explained in more detail by means of exemplary embodiments and with reference to the drawings. [Figure 1] 1 shows a side view of a different solid bowl screw centrifuge according to the present invention, which is shown diagrammatically. [Diagram 2] 1 shows a side view of a different solid bowl screw centrifuge according to the present invention, which is shown diagrammatically. [Diagram 3] 1 shows a side view of a different solid bowl screw centrifuge according to the present invention, which is shown diagrammatically. [Figure 4] FIG. 1 shows a side view of a fourth schematic diagram of a solid bowl screw centrifuge according to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] FIG. 1 shows a solid bowl screw centrifuge having a frame that is non-rotatable or does not rotate during operation, preferably a housing 100, and a rotor 200 that is rotatable or does rotate during operation. The rotor 200 comprises a rotating drum 210 with a horizontal axis of rotation D, which may also be oriented differently in space, in particular in the vertical direction. The rotor 200 also comprises a screw 230 arranged in the drum 210, the axis of rotation of which coincides with the axis of rotation of the drum 210. The screw 230 rotates the drum 210 during operation. , can be rotated at different speeds relative to

[0019] The drum 210 has a cylindrical portion 211 having a length L1 and an axially adjacent conical portion 212 having a length L2. The cylindrical portion 211 is closed by a generally radially extending drum cover 213. At the conical portion 212 having a length L2, the drum is inner and outer of a cone (relative to the drum shell). The screw 230 here also has a cylindrical portion 231 and an axially adjacent conical portion 232. The cylindrical portion 231 and the conical portion 232 are disposed inside the drum 210.

[0020] A supply pipe 214, which here runs concentrically with the axis of rotation, projects into the drum 210 and opens into a distributor 215 through which the suspension Su to be treated can be supplied radially into the centrifugal chamber 216 of the drum 210. The supply pipe 214 is guided into the drum 210 from the side of the cylindrical part 211 of the drum or from the side of the conical part 212 of the drum.

[0021] In or on the drum cover 213, one or more liquid discharges 217 are formed. These can be formed in different ways, for example as openings in the drum cover 213 with a kind of overflow weir, or in other ways, for example as peeling disks. At the end of the conical part 212, at least one solids discharge 218 is formed. In principle, the drum 210 is configured as a solid bowl drum. At least one liquid phase FI is then purified from the solid Fe in the rotating drum 210. The at least one liquid phase emerges from the liquid discharge 217 at the drum cover 213. Meanwhile, the solids are conveyed by the screw 230 in the direction of the solid discharge 218 and are discharged from the drum 210 at the solid discharge 218.

[0022] FIG. 4 shows a solid bowl screw centrifuge in which a first drum shaft section 220 is axially connected to the drum cover 213 or actual drum 210 and is non-rotatably connected to the drum 210, and a second drum shaft section 219 is axially adjacent to the drum conical section 212 and is also non-rotatably connected to the drum 210. The first screw shaft portion 234 is axially adjacent to the cylindrical portion 231 of the screw 230 and non-rotatably connected to the screw 230, and the second screw shaft portion 233 is axially adjacent to the conical portion 232 of the drum and also non-rotatably connected to the screw 230.

[0023] The rotor 200 is driven by a drive unit having one or two motors (not shown here). The drive 300 is followed by at least one gear unit 310 on which two pulleys 320, 330 are shown here diagrammatically, indicating that the gear unit 310 has at least two interfaces to feed the torque of the motor or motors respectively into the gear unit 310 to drive the drum and the screw. Alternatively (not shown here), the rotor can be driven by a hydraulic motor, so no gears are required, or it is also possible to use a different gearbox and completely or partially eliminate the pulleys, driving the rotor by a combination of electric and hydraulic motors.

[0024] The gear unit 310 rotates the drum 210 on the one hand and the screw 230 on the other hand. For this purpose, the gear unit 310 has two output shafts: a first output shaft is non-rotatably connected to the first drum shaft section 220 or directly to the drum 210, and a second output shaft is directly or indirectly connected to the first screw shaft section 234. It is non-rotatably connected or directly connected to the screw 230 . The drum and shaft parts are rotatably supported by two drum bearings 221, 222, respectively, arranged axially in the direction of the rotation axis. The term "bearing" should not be defined too narrowly in this respect. Each of the drum bearings 221, 222 can consist of one or more single bearings, which are arranged axially directly next to each other and can in each case be considered functionally as one single bearing. The drum bearings 221, 222 can also be configured as various types of bearings, such as roller bearings, in particular ceramic bearings, duplex ceramic bearings, magnetic bearings or plain bearings.

[0025] The drum bearings 221 and 222 are connected to the drum 210. housing Between 100 or housing Since the drum 210 is disposed in a portion connected to the housing 100. This also applies to all the variants described below and covered by the claims. The drum bearings 221, 222 are housing Between 100 and housing It is preferable that the electrodes are arranged radially on the portion connected to the Meanwhile, the screw bearings 235, 236 are disposed radially between the screw 230 and the drum 210 so that the screw 230 can rotate relative to the drum 210. The screw bearings 235, 236 are preferably disposed radially between the drum 210 and the screw 230.

[0026] In a possible variant embodiment (not shown), one of the screw bearings 235 in the region of the solids discharge 218 can be omitted. In this case, it is known that the rotating screw is self-centering, for example from the vertical arrangement of the decanter.

[0027] According to the prior art shown in FIG. 4, the drum bearings 221, 222 are arranged in an axial area L T 4, for example, they are disposed between the solid discharge section 218 and the axial end of the housing 100 adjacent to the solid discharge section, and between the liquid discharge section 217 and the axial end of the housing 100 adjacent to the liquid discharge section. Thus, the distance L L is the length L of the drum 210, which is the sum of the length L1 of the cylindrical portion 211 of the drum 210 and the length L2 of the conical portion 212 of the drum 210. T Longer than.

[0028] This means that the two drum bearings 221, 222 are spaced apart from each other by the length L of the drum 210. T 4, the screw bearings 235, 236 are also arranged axially outside the axial region of the drum 210, and the axial region is between the solid discharge portion 218 and the liquid discharge portion 217 of the drum 210. This means that the two screw bearings 235, 236 are also arranged axially outside the axial region of the drum 210 and the screw 230, as shown in FIG. T This means that the axial spacing is relatively large with respect to the

[0029] Here, the invention takes a different route: one or both of the drum bearings 221, 222 are arranged in the axial region located between the solids discharge portion 218 and the liquid discharge portion 217 of the drum 210, or in the axial region located between the liquid discharge portion 217 and / or the solids discharge portion 218 of the drum 210. The drum bearings 221, 222 are then positioned radially outward of the drum 210, or positioned radially or axially outward of the drum cover 213.

[0030] If one of the drum bearings 221, 222 is located in the axial region between the solid discharge portion 218 and the liquid discharge portion 217 of the drum 210, the other of these respective bearings One of the bearings - the other of the drum bearings 221, 222 - can be located outside this axial region. However, in the context of the present invention, both bearings - both drum bearings It is also possible to provide the rings 221, 222- outside the axial region or in the regions mentioned above (FIG. 3). Cut.

[0031] In this way, it has been shown that, with the rotor geometry unchanged, the first resonant frequency of the rotor can be increased and therefore the drum speed can be further increased. Different variations of this teaching are shown in Figures 1 to 3. In Figures 1 to 3, the length of the drum 210 is L T The distance between the drum bearings 221 and 222 is L L In FIG. 4, in a prior art solid bowl screw centrifuge, L T <L L It is.

[0032] 1 shows an embodiment of the invention in which a first drum bearing 221 is assigned to the conical part 212 of the drum 210. The first drum bearing 221 is axially spaced from the solids discharge part 218 in the direction of the cylindrical part 211 of the drum 210. The other of the drum bearings 222 "other end of the drum" is outside this axial part. The first drum bearing 221 is therefore arranged between the solids discharge 218 and the liquid discharge 217 in the region of the conical part 212 of the drum 210 on the conical part. The drum shaft part 219 in the region of the conical part 212 of the drum 210 is therefore also dispensed with. The length of the drum 210 is now longer than the distance between the drum bearings 221, 222, and therefore L T >L L It is.

[0033] It is possible to configure the conical portion to be very long in the axial direction and to configure the diameter of the drum, on which the solids discharge is located, to be relatively small. The ratio of the diameter of the drum, on which the solids discharge is located, to the maximum inner diameter of the drum may be between 0.4 and 0.3. This may be advantageous for keeping low or reducing the energy losses caused by the discharge of the solids. Furthermore (see above) see definition), relatively high values ​​of "λ" can be achieved.

[0034] 2 shows an embodiment variant of the invention in which a first drum bearing 221 is assigned to the conical part 212 of the drum 210, which is similar to the embodiment variant according to FIG. 1, and which is spaced axially from the solids discharge part 218 in the direction of the cylindrical part 211 of the drum 210. The drum bearing 221 is thus arranged between the solids discharge part 218 and the liquid discharge part 217, in the region of the conical part 212 of the drum 210.

[0035] The other drum bearing 222 is here assigned to the cylindrical part 211 of the drum 210 or arranged externally on it. The drum bearing 222 is directly axially adjacent to the region of the liquid discharge part 217 of the drum 210. The drum shaft part 219 in the region of the conical part 212 of the drum 210 and the drum shaft part 220 in the region of the cylindrical part 211 of the drum 210 can therefore be omitted here. The length of the drum 210 is also here longer than the distance between the drum bearings 221, 222, so that here too L T >L LIt is.

[0036] Figure 3 shows an embodiment variant of the invention in which the first drum bearing 221 is again arranged radially outwardly on the conical part 212 of the drum 210. Again, similar to the embodiment variant according to figure 1, the first drum bearing 221 is spaced axially away from the solids discharge part 218 in the direction of the cylindrical part 211 of the drum 210. The first drum bearing 221 is thus again located in the region of the conical part 212 of the drum 210, between the solids discharge part 218 and the liquid discharge part 217, and the second drum bearing 222 is then located on the cylindrical part 211 of the drum 210. Here, the second drum bearing 222 is axially rotated from the liquid discharge part 217 in the direction of the conical part 212 of the drum 210. It is thus possible to dispense with the drum shaft portion 220 in the region of the cylindrical portion 211 of the drum 210 and the drum shaft portion 219 in the region of the conical portion 212 of the drum 210. The length of the drum 210 is now greater than the distance between the drum bearings 221, 222, and therefore L T >L L It is.

[0037] 1 to 3, there is a distance A1 and / or A2 between each end of the drum 210 and the respective position of the drum bearings 221 and / or 222. The distances A1 and / or A2 between the liquid discharge section 217 and the solid discharge section 218 are each spaced apart in the direction of the drum 210. T It is preferably 0% to 35%, and particularly preferably 0% to 25%.

[0038] The drum bearings 221 and 222 are disposed at positions within the axial range between the solid discharge portion 218 and the liquid discharge portion 217, so that the distance L between the drum bearings 221 and 222 is Lis advantageously shorter and the first natural vibration of the drum 210 occurs only at higher speeds than with the prior art bearing arrangement (see FIG. 4). Due to the higher operating speeds that are possible, the separation efficiency achievable with the solid bowl screw centrifuge according to the invention is advantageously increased compared to a solid bowl screw centrifuge of the same volume according to the prior art.

[0039] The description of the arrangement of the drum bearings 221, 222 according to Figures 1 to 3 should by no means be understood as final. Rather, other advantageous arrangements of the drum bearings 221, 222 are also conceivable within the scope of the claims. However, the axial distance L between the drum bearings 221, 222 L is the length L of the drum 210 T must be shorter than [Explanation of symbols]

[0040] 100 Housing 200 rotors 210 Drums 211 Cylindrical section 212 Cone-shaped part 213 Drum Cover 214 Supply Pipe 215 Distributor 216 Centrifugal chamber 217 Liquid discharge part 218 Solids discharge section 219 Drum shaft part 220 Drum shaft section 221 Drum Bearing 222 Drum Bearing 230 Screw 231 Cylindrical Section 232 Cone-shaped part 233 Screw shaft part 234 Screw shaft part 235 Screw Bearing 236 Screw Bearing 300 Drive Unit 310 Gear Unit 320 Pulley 330 Pulley A1 Distance A2 distance D Rotational Axis L1 length L2 length L L Drum bearing distance L T Drum length Su suspension Fe solid FI liquid phase

Claims

1. The rotor (200) is rotatably mounted within the housing (100), and includes at least a. A drum (210) having a rotation axis (D) and a length L １ A cylindrical portion (211) having a length L ２ and a conical portion (212) having a length L １ and length L ２ When added together, the length L of the drum (210) Ｔ A rotatable drum (210) that provides b. at least one liquid discharge (217) disposed in the cylindrical portion (211) of the drum (210) and at least one solids discharge (218) disposed in the conical portion (212) of the drum; c. a screw (230) disposed within the drum and rotatable at differential speed relative to the rotatable drum (210), said screw (230) forming, together with said drum (210), said rotor (200); d. A drum (210) is supported within the housing (100) at a distance L Ｌ At least two drum bearings (221, 222) arranged at a distance from each other; e. A solid bowl screw centrifuge having at least one screw bearing (236) supporting a screw (230) within a drum (210), f. Distance L between drum bearings (221, 222) for supporting the drum (210) against each other Ｌ is the length L of the drum (210) Ｔ is less than g. One drum bearing (221) is disposed radially outwardly on the conical portion (212) of the drum (210); 2. A solid bowl screw centrifuge, characterized in that the drum bearing (221) arranged radially outwardly on the conical portion (212) of the drum (210) has an inner diameter smaller than that of the cylindrical portion (211) of the drum (210).

2. 2. The solid bowl screw centrifuge of claim 1, wherein one or both of the drum bearings (221, 222) are arranged in an axial region between the solid discharge section (218) and the liquid discharge section (217) of the drum (210).

3. 3. The solid bowl screw centrifuge according to claim 1 or 2, wherein the drum bearings (221, 222) are arranged between the drum (210) and the housing (100) or in a part connected to the housing and / or the at least one screw bearing (236) is arranged between the screw (230) and the drum (210).

4. 4. The solid bowl screw centrifuge of claim 1, wherein one or both drum bearings (221, 222) and / or one or both screw bearings (235, 236) are directly adjacent to the liquid discharge (217) and / or solid discharge (218) areas of the drum (210).

5. Distance A between each axial end of the drum (210) and each axial position of the drum bearings (221) and / or (222) １ And / or A ２ is the length L of the drum (210) Ｔ 5. A solid bowl screw centrifuge as claimed in claim 1, wherein the flow rate is between 0% and 35% of the total flow rate.

6. 6. The solid bowl screw centrifuge according to claim 1, wherein the drum bearings (221, 222) are arranged radially outside on the drum (210) or directly outside on a drum cover (213).

7. 7. The solid bowl screw centrifuge of claim 1, wherein one of the drum bearings (222) is disposed radially outwardly on the cylindrical portion (211) of the drum (210).

8. 8. The solid bowl screw centrifuge according to claim 1, wherein one of said drum bearings (222) is located externally with respect to the axis of rotation of said drum (210) on a drum cover (213) closing the cylindrical part (211) of said drum (210).

9. 9. The solid bowl screw centrifuge according to any one of claims 1 to 8, wherein one or both of said drum bearings (221, 222) are configured as magnetic bearings.

10. 9. The solid bowl screw centrifuge according to any one of the preceding claims, wherein one or both of the drum bearings (221, 222) are configured as roller bearings.

11. 9. The solid bowl screw centrifuge of claim 1, wherein one or both of said drum bearings (221, 222) are configured as ceramic bearings or duplex ceramic bearings.

12. 12. A solid bowl screw centrifuge as claimed in any one of claims 1 to 11, wherein the ratio between the diameter of the drum at the point where the solids discharge is located and the maximum diameter of the drum is between 0.4 and 0.

3.

13. 13. A solid bowl screw centrifuge according to any of the preceding claims, wherein the axis of rotation (D) of the drum is aligned horizontally or vertically.

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