Solid bowl screw centrifuge

Abstract

The invention relates to a solid bowl screw centrifuge (1) for processing a suspension Su in a centrifugal field, comprising at least the following: a rotatable drum (200) having an axis of rotation (D), b) an inlet pipe (206) which projects into the drum (200) and is concentric with respect to the axis of rotation D and through which the suspension Su to be processed can be conducted into a separating chamber (210) of the drum (200), c) at least one liquid outlet (204) for discharging a liquid phase Fl, d) at least one solids discharge (205) for discharging a solid phase Fe which is still flowable, and e) a screw (300) which is mounted in the drum (200) and can be rotated relative to the rotatable drum (200) at a differential rotational speed. The solid bowl screw centrifuge is characterized in that f) the liquid phase Fl is discharged out of the drum (200) by means of a discharge element which is located, at least in the region of the inlet thereof and preferably in its entirety, radially inwards relative to an inner ring (317) of a bearing of a first screw bearing unit (306) and radially inwards relative to an inner ring (209) of a bearing of a first drum bearing unit (207).

Description

[0001] Solid bowl screw centrifuge

[0002] The invention relates to a solid bowl screw centrifuge.

[0003] A solid-bowl screw centrifuge, also called a decanter, can be used to separate a solid phase from a flowable suspension. Optionally, the suspension, once cleared of solids, can be separated into different liquid phases in a design with two liquid outlets.

[0004] Solid bowl screw centrifuges are very well suited to processing comparatively high solid concentrations in the feed stream, are comparatively robust, achieve very good separation results, and ensure effective drying of the solid phase. In this context, the solid phase is understood to be a solid that has been dehydrated as much as possible, although in practice this often still contains so much residual moisture that it behaves like sludge.

[0005] Known solid bowl screw centrifuges with a frame that is not rotatable or does not rotate during operation have a rotatable or rotating rotor, which in turn has a bowl and therein a screw that can rotate at a speed different from that of the bowl.

[0006] The decanter centrifuge thus comprises a rotating system, which includes, among other things, the solid bowl and the screw, which in turn contains a processing or separation chamber. The centrifugal force acting in the rotating system is used to separate the incoming suspension into phases with different densities. The difference in speed between the two main components involved in the separation process—the bowl and the screw—ensures that the separated solid phase is conveyed out of the separation chamber in a targeted manner.

[0007] Solid bowl screw centrifuges are used to separate media in a wide variety of applications, such as clarification of sludge, extraction of oils and juices from fruit and vegetables, dewatering of various mixtures, etc.

[0008] The heavy and light phases in the feed suspension are separated from each other within the rotating system and fed to different processes. The light liquid phase is displaced by the heavy solid phase in the drum and discharged freely, for example, through an opening in the drum lid of the cylindrical part of the drum. The solid phase is discharged by the screw in the conveying direction via solids discharge openings in the conical part of the drum.

[0009] Since the exit of both phases from the rotating drum is associated with a significant loss of kinetic energy, the aim is to place the radius of the exit openings close to the axis of rotation, since this is where the energy loss is lowest.

[0010] Various solutions have become known from the state of the art.

[0011] DE 102019 126 325 A1 discloses a prior art in which the solid phase of a solid-bowl screw centrifuge is discharged as close as possible to the rotational axis of the bowl. The liquid phase is discharged radially within the inner ring of the bowl bearing.

[0012] DE10 2023 116 567 and EP 2 866 945 B1 each disclose a solid bowl screw centrifuge in which the liquid phase is discharged on the liquid side by a gripper or a stationary impeller disc that is stationary during operation of the centrifuge, i.e. under pressure and with energy loss.

[0013] The screw hub of the solid-bowl screw centrifuge according to EP 3476 488 A1 consists of spoke-like plates. The screw flight is mounted on the upper edges of these plates. The lower edges of the plates are positioned close to the rotation axis, but do not touch the stationary inlet pipe. This creates a decanter with a very deep pond or pool.

[0014] The object of the invention is to create a solid bowl screw centrifuge in which the energy loss due to liquid discharge is very low.

[0015] This object is achieved by the subject matter according to claim 1.

[0016] Accordingly, a solid bowl screw centrifuge for processing a suspension Su in a centrifugal field is created, which has at least the following: a rotatable drum with a rotational axis, an inlet pipe projecting into the drum and arranged concentrically to the rotational axis, through which the suspension Su to be processed can be guided into a separation space of the drum, at least one liquid outlet for the discharge of a liquid phase, at least one solids discharge for the discharge of a still flowable solid phase or sludge phase, and a screw arranged in the drum which can be rotated at a differential speed relative to the rotatable drum.It is further provided that the discharge of the liquid phase Fl from the drum takes place through a discharge element which is arranged, at least in the region of its inlet, preferably completely, both radially inward to an inner ring of a bearing of a first screw bearing unit, and preferably also radially inward to an inner ring of a bearing of a first drum bearing unit.

[0017] This creates a solid bowl screw centrifuge in which the energy loss of the liquid discharge through the outlet of the liquid phase near the axis of rotation is very low, since in particular the entry of the liquid phase from the centrifugal chamber into the discharge element and preferably the entire discharge takes place on a very small radius, i.e. on a radius which is smaller than the radius of the inner ring of a bearing of a first screw bearing unit, whereby such a centrifuge operates particularly energy-efficiently.

[0018] According to a particularly preferred embodiment of the invention, the discharge element can rotate at the screw speed during operation of the solid-bowl screw centrifuge. The rotating discharge element advantageously results in little turbulence in the flow of the liquid phase Fl to be discharged, particularly when the inlet pipe also rotates at the screw speed during operation of the solid-bowl screw centrifuge, thereby further advantageously minimizing energy losses.

[0019] Alternatively, according to a further, particularly preferred embodiment of the invention, the discharge element can be stationary during operation of the solid-bowl screw centrifuge. This creates a discharge element that is structurally simple to implement.

[0020] According to a further preferred embodiment of the invention, the discharge element is a drain pipe. This results in the use of a discharge element that is structurally simple, fluidically advantageous, easy to manufacture, and thus cost-effective.

[0021] According to a particularly preferred embodiment of the invention, the screw comprises a screw flight formed externally on a screw hub and projecting radially or substantially radially from the latter. It can then further advantageously be provided that the screw hub comprises, circumferentially distributed in a cylindrical screw hub section, a plurality of guide elements extending radially (in a plane and substantially or precisely in the axial direction) and aligned in a beam-like manner. With such a design, the subject matter of the characterizing part of claim 1 can be readily and easily implemented.

[0022] According to a further preferred embodiment of the invention, the liquid phase Fl can be guided out of the drum coaxially with the inlet pipe and along the inlet pipe. This results in the smallest possible radius for the liquid discharge, so that as little energy as possible is lost from the rotating system of the solid-bowl screw centrifuge during the liquid discharge.

[0023] Furthermore, according to a further particularly preferred embodiment of the invention, it can be provided that the inlet pipe is arranged coaxially to the rotating screw hub.

[0024] According to a particularly preferred embodiment of the invention, the screw can be composed of two segments. It can then have a first, cylindrical screw segment comprising a cylindrical screw hub section and a cylindrical screw helix section, as well as a conical second screw segment connected to the first screw segment, which comprises a conical screw hub section and a conical screw helix section. Such a two-part screw results in cost advantages for the production of the individual parts and the entire screw due to the resulting smaller dimensions.

[0025] According to a further particularly preferred embodiment of the invention, it can be provided that a replaceable immersion disk is arranged in the transition region between and particularly preferably at a joint between a cylindrical part and a conical part of the screw, which is split here, wherein it can further be provided that the immersion disk is preferably clamped there. Immersion disks with different outer diameters can be provided. These can thus be easily assembled and thus changed. The replaceable immersion disk allows the properties of the screw to be advantageously adapted quickly and easily to a respective application, which can be necessary, for example, if the composition of the suspension fed in and to be clarified changes with regard to the proportions of liquid phase and solid phase.

[0026] According to a further particularly preferred embodiment of the invention, the guide elements can be fastened in the axial direction to cross disks or to a screw hub cover, wherein the cross disks divide at least the cylindrical screw hub section in the axial direction into a plurality of chamber-like, cylindrical sections, through which the circumferentially distributed guide elements extend, extending radially in a radial direction. Due to the chamber-like design of the screw hub with the guide elements arranged radially in the chambers, a conventional distribution chamber can be omitted, resulting in a particularly low-turbulence transition of the suspension into the separation chamber of the centrifuge and reducing unfavorable shearing of the particles in the suspension.

[0027] Furthermore, according to another preferred embodiment of the invention, the transverse discs can have a plurality of openings, so that the suspension to be separated and its phases can flow unhindered in the radial and, in particular, axial directions in the cylindrical screw hub section. This also advantageously eliminates the need for a conventional distribution chamber.

[0028] According to a further preferred embodiment of the invention, the screw flight can be secured in the region of the cylindrical screw hub section on the upper edges of the guide elements or radially outwardly on the guide elements, thereby forming gaps between the guide elements and the screw flight, so that the suspension introduced into the inlet pipe or the phase separated or clarified therefrom can flow radially outward or inward. This also results in advantageous transfer of the suspension in this region.

[0029] Furthermore, according to a further, particularly preferred embodiment of the invention, a respective lower edge of the guide elements can extend radially close to the rotational axis D, wherein the respective lower edge does not touch the inlet pipe, thereby creating a stationary inlet pipe during operation of the solid-bowl screw centrifuge. This results in a further structurally advantageous embodiment of the solid-bowl screw centrifuge.

[0030] Alternatively, according to a further, particularly preferred embodiment of the invention, the respective lower edge of at least some of the guide elements extends, at least in places, to the inlet pipe or is connected to the inlet pipe, resulting in an inlet pipe that rotates during operation of the solid-bowl screw centrifuge. As a result, the inlet pipe is directly or indirectly connected in a rotationally fixed manner to the inner ring of the first screw bearing unit. Since the inlet pipe and the liquid phase to be discharged rotate in the same direction, a particularly advantageous, uniform discharge of the liquid phase from the rotating bowl is achieved.

[0031] It is also advantageous if the respective guide element is flat and arranged radially in a radial direction. This provides a simple and cost-effective manufacturing option and a statically advantageous arrangement of the guide elements.

[0032] Alternatively, the guide elements can also be formed from profiles with, for example, a V-shaped cross-section with straight or concave flanks, with the narrower side (lower edge) of the profile facing axially inward and the wider side (upper edge) facing axially outward. This can significantly increase the torsional rigidity of the screw.

[0033] Alternatively, according to a further, particularly preferred embodiment of the invention, the respective guide element can be curved in a turbine blade-like manner. The curved shape of the respective guide element influences the acceleration of the supplied suspension Su into the drum—also depending on the selected direction of rotation of these guide elements—which can reduce unfavorable shearing of the particles in the suspension.

[0034] Furthermore, according to a further, particularly preferred embodiment of the invention, the counterpressure for the liquid phase Fl can be varied by changing the inner diameter d of a drain pipe for the liquid phase Fl. This provides a structurally simple way of varying the counterpressure for the liquid phase.

[0035] Further advantageous embodiments of the invention can be found in the remaining subclaims.

[0036] The invention will be described in more detail below using several exemplary embodiments with reference to the drawings. The invention is not limited to these exemplary embodiments, but can also be implemented in other ways, either literally or in other equivalent ways.

[0037] It shows:

[0038] Figure 1: in a) a schematic longitudinal section of a solid-bowl screw centrifuge according to the invention; in b) an enlarged detail of the solid-bowl screw centrifuge from Fig. 1a;

[0039] Figure 2: in a) a section through a cylindrical segment of a drum of the solid-bowl screw centrifuge from Fig. 1a; in b) a section through the cylindrical segment of the drum of a variant of the embodiment of the solid-bowl screw centrifuge from Fig. 1a; in c) and in d) each show design variants of profiles of guide elements;

[0040] Figure 3: a schematic longitudinal section of another embodiment of the solid bowl screw centrifuge from Fig. 1a;

[0041] Figure 4: a schematic longitudinal section of another embodiment of the solid bowl screw centrifuge from Fig. 1a.

[0042] Several exemplary embodiments are described in the following description of the figures. Individual features of these exemplary embodiments can also be combined with exemplary embodiments not shown and are also suitable as advantageous embodiments of the subject matter described in one or more of the main and subclaims.

[0043] The terms used below, such as “top”, “bottom”, “right”, “left”, “horizontal”, “vertical”, “radial”, “axial”, “inside” or “outside” refer to the respective representation of the figures.

[0044] Fig. 1a shows a solid-bowl screw centrifuge 1—also called a decanter—for processing a product in the form of a suspension Su in a centrifugal field. The decanter has a frame that is non-rotatable or non-rotating during operation—which can preferably be designed as a type of housing—and a rotor 100 that is rotatable or rotating during operation.

[0045] In Fig. 1a, the rotor 100 has a rotatable drum 200 with a horizontal axis of rotation D. However, the axis of rotation D can also be oriented differently, in particular vertically, in space. The drum 200 is preferably designed as a solid-bowl drum. In the drum 200 rotating during operation of the solid-bowl screw centrifuge 1, an incoming suspension Su is separated into at least one liquid phase Fl and one solid phase Fe, or the suspension Su is clarified from solids Fe. In this context, the solid phase Fe is understood to be a solid that has been dehydrated as far as possible, but in practice often still contains so much residual moisture that it behaves like sludge and is therefore still flowable.

[0046] The rotor 100 also has a screw 300 arranged in the drum 200, the axis of rotation of which coincides with the axis of rotation D of the drum 200.

[0047] The drum 200 has a cylindrical drum section 201 and preferably has a conical drum section 202 axially adjoining thereto. The cylindrical section 201 is closed off here by a substantially radially extending drum cover 203. In the conical section 202, the drum 200 is preferably conical on the inside and outside (relative to the drum shell).

[0048] One or more liquid outlets 204 may be formed in or on the drum cover 203 or at the cylindrical end of the drum toward this drum cover 203. These may be configured in various ways, such as openings in the drum cover 203 that function as a type of overflow weir, or may be implemented in other ways.

[0049] At least one solids discharge 205 is formed as an extension of the conical section 202 of the drum 200. An inlet pipe 206, arranged concentrically to the rotational axis D, extends into the drum 200.

[0050] The inlet pipe 206 can - as shown in Fig. 1 a - either be led into the drum 200 from the side of the cylindrical drum section 201 or it can be led into the drum 200 from the side of the conical drum section 202.

[0051] The screw 300 here also has a cylindrical screw section 301 and an axially adjoining conical screw section 302. It is arranged within the drum 200. During operation, the screw 300 can be rotated at a speed different from that of the drum 200.

[0052] The solids Fe deposited on the inner wall of the drum during operation are transported by the screw conveyor 300 toward the solids discharge 205, where they are ejected from the drum 200. The drives for rotating the screw conveyor 300 and the drum 200 can be designed as electric motors and have one or more gears. However, other designs, such as hydraulic drives, are also conceivable.

[0053] The screw 300 further comprises a screw flight 303, which is arranged and formed externally on a screw hub 304 and can protrude radially or substantially radially therefrom. The screw hub 304 has—analogous to the drum 200—a cylindrical screw hub section 305 and a conical screw hub section 306 axially adjoining it.

[0054] The screw flight 303 can have a progressive or degressive pitch. The pitch can be linear or non-linear. Thus, sections with different pitches can also be provided. Depending on the pitch direction of the screw flight 303, the screw 300 rotates faster or slower than the drum (with the same direction of rotation) to create a conveying effect in the direction of solids discharge.

[0055] The rotor 100 has at least a first drum bearing unit 207 and may have a second drum bearing unit 208. The drum bearing units 207, 208 are arranged radially between the frame and the drum 200 and thus allow the drum 200 to rotate relative to the stationary frame. The first drum bearing unit 207 is arranged on the side of the drum cover 203, while the second drum bearing unit 208 is arranged on the side of the solids discharge 205. The two drum bearing units 207, 208 are designed such that they can absorb both axial and radial forces (relative to the rotational axis D of the drum 200) of the drum 200. In particular, radial bearings and axial bearings can also be combined in the respective drum bearing unit 207, 208.

[0056] Analogously, the screw 300 can also be rotatably mounted relative to the drum 200 in at least a first screw bearing unit 307 and optionally in a second screw bearing unit 308. The screw bearing units 307, 308 are arranged in the radial direction between the drum 200 and the screw 300 and thus allow the screw 300 to rotate relative to the drum 200 at a different speed than the drum 200 or in the opposite direction of rotation. The first screw bearing unit 307 is arranged on the side of the drum cover 203, while the second screw bearing unit 308 is arranged on the side of the solids discharge 205. The two screw bearing units 307, 308 are designed such that they can absorb both axially and radially acting forces (relative to the rotational axis D of the screw 300) of the screw 300. In particular, radial bearings and axial bearings can also be combined in a worm bearing unit 307, 308.

[0057] Furthermore, it is provided that the functions of the solid-bowl screw centrifuge 1 are controlled or regulated by a control device (not shown here). For this purpose, the control device is equipped with a corresponding computer program that executes the necessary computational operations and control commands and can be operatively connected to corresponding sensors and actuators and, if necessary, other elements of the solid-bowl screw centrifuge 1.

[0058] The screw hub 304 in its embodiment according to the invention has on its cylindrical screw hub section 305 a plurality of guide elements 309 which extend circumferentially in the radial and axial direction and are thus arranged in a quasi-radial manner (see Fig. 2a and Fig. 2b).

[0059] The guide elements 309 are preferably made of sheet metal. The screw flight 303 can be attached in the region of the cylindrical screw hub section 305 only to the upper edges 310 of the guide elements 309 or radially outwardly to the guide elements 309. This creates gaps 311 between the guide elements 309 and the screw flight 303, so that the suspension Su introduced into the inlet pipe 206 or the phases Fl, Fe separated or clarified therefrom can flow radially outwards or inwards. An otherwise usual, separate distribution chamber through which the inflowing suspension Su flows from the screw hub 304 into a separation chamber 210 between an outer diameter of the screw hub 304 and the inner diameter of the drum 200 can thus be omitted.

[0060] The guide elements 309 each have a lower edge 312 on their radially inner side. The respective lower edge 312 of the guide elements 309 extends radially up to close to the axis of rotation D, but does not touch the inlet pipe 206, whereby a stationary inlet pipe 206 can be realized during operation of the solid bowl screw centrifuge 1. Suspension flowing from the inlet pipe is guided radially outwards between the guide elements 309 into the separation chamber 210. There, the suspension Su separates into the solid phase Fe and the liquid phase Fl, which then initially flows in the direction of the bowl cover 203, while the solid phase Fe is transported by the screw flight 303 to the solids discharge 205. Alternatively, the guide elements 309 can also be made of profiles with, for example, a V-shaped cross-section with straight or concave flanks (see Fig. 2c and Fig.2d), with the narrower side (lower edge 312) of the profile facing axially inward and the wider side (upper edge 310) facing axially outward. This can significantly increase the torsional rigidity of the screw 300. To reduce the screw weight, the profile of the guide elements 309 can also be designed as a hollow profile.

[0061] The selected design also results in a solid-bowl screw centrifuge with a large maximum pond depth. The maximum pond depth is defined as the distance between the inner wall of the drum 200 and the largest diameter d of the liquid outlet 204 in the radial direction relative to the drum 200.

[0062] The respective guide element 309 can be fastened in the axial direction to axially spaced transverse discs 313 and towards the cylindrical end of the drum 200 to a screw hub cover 314 which is also in the form of a transverse disc (see also Fig. 2a and Fig. 2b, which show this in more detail).

[0063] The axially spaced transverse discs 313 thus divide at least the cylindrical screw hub section 305 in the axial direction in a quasi "bulkhead-like" manner into a plurality of chamber-like, cylindrical sections 315, through which guide elements 309 extend, each arranged circumferentially distributed and oriented radially and axially in a beam-like manner in cross-section.

[0064] The transverse discs 313 each have a plurality of openings 316, preferably distributed circumferentially, so that the suspension Su to be separated and its phases Fl, Fe can flow unhindered in the radial and in particular also axial direction in the cylindrical screw hub section 305.

[0065] The respective guide element 309 can be flat and oriented radially, as shown in Fig. 2a, or alternatively, curved like a turbine blade, as shown in Fig. 2b. The curved shape of the respective guide element 309, depending on the selected direction of rotation of these guide elements 309, influences the acceleration of the supplied suspension Su into the drum 200 and reduces unfavorable shearing of the particles in the suspension Su. Fig. 1b shows an enlarged detail of the solid-bowl screw centrifuge 1 from Fig. 1a. This enlarged detail shows an area with the cylindrical drum section 201, the cylindrical screw section 305, the first drum bearing unit 207, the first screw bearing unit 307, as well as the drum cover 203 and the screw hub cover 314.

[0066] In this Fig. 1b, it is clearly visible that the discharge of the liquid phase Fl from the drum 200 takes place through a discharge element whose inlet from the centrifugal chamber is arranged radially inward to an inner ring 317 of a bearing of the first screw bearing unit 307, and preferably also radially inward to an inner ring 209 of a bearing of the first drum bearing unit 207. In the preferred embodiments illustrated, the discharge element even extends entirely on a smaller radius than the inner radii of these two bearings.

[0067] The discharge element is designed here as an outlet pipe 101. The outlet pipe 101 is arranged coaxially to the central inlet pipe 206. It can be fastened in a rotationally fixed manner, for example radially on the inside, to the screw hub cover 314, which is aligned radially here. It rotates here with the screw 300 during operation of the solid bowl screw centrifuge 1. According to an advantageous embodiment, it can be relatively short axially and extend in the centrifugal chamber in the bowl only up to or just behind the screw hub cover 314. Furthermore, the inner ring 317 of the screw bearing can be formed axially on the screw hub cover 314, for example on a somewhat larger radius, or a cylindrical extension on which this inner ring 317 sits. The discharge of the corresponding liquid phase thus takes place with a relatively low energy loss. This is common to the various embodiments in the figures.

[0068] Alternatively, the discharge element can also be designed to be stationary and connected to the frame (see Fig. 4) and sealed with a sealing element to the rotating screw hub cover 314. Also according to Fig. 4, it is provided that the discharge of the liquid phase Fl from the drum 200 takes place through a discharge element whose inlet from the centrifugal chamber is arranged radially inward to an inner ring 317 of a bearing of the first screw bearing unit 307, and preferably also radially inward to an inner ring 209 of a bearing of the first drum bearing unit 207. In the preferred embodiments illustrated, the discharge element even extends entirely on a smaller radius than the inner radii of these two bearings. The discharge of the corresponding liquid phase thus also takes place here with a relatively low energy loss.

[0069] The discharge pipe 101 extends axially through the screw hub cover 314 and the drum cover 203 from the interior or separation chamber 210 to the outside of the rotating system. The liquid phase Fl, flowing radially inward near the screw hub cover 314, then flows axially into the discharge pipe 101 and through it out of the drum 200.

[0070] In this way, during operation of the solid bowl screw centrifuge 1, the liquid phase Fl is discharged from the separation chamber 210 coaxially to the central inlet pipe 206, which is arranged coaxially to the rotating screw hub 304, as well as completely radially inward to the first screw bearing 307 and completely radially inward to the first drum bearing 207.

[0071] This discharge element, which extends only up to a very small radius and is arranged almost centrally and coaxially with the inlet pipe 206, realizes a structurally simple and energetically favorable way of discharging the liquid phase Fl from the rotating drum 200. By omitting a paring disc and the almost central discharge of the liquid phase Fl on a very small radius, an advantageous reduction in the energy requirement of the solid bowl screw centrifuge 1 according to the invention is also achieved compared to the prior art.

[0072] By changing the inner diameter d of the outlet pipe 101 for the liquid phase Fl, the counterpressure for the liquid phase Fl can be changed and thus the separation zone in the separation chamber 210 of the solid bowl screw centrifuge 1 can be influenced.

[0073] In the embodiment of the invention according to Fig. 3, the respective lower edge 312 of at least some of the guide elements 309 extends at least partially to the inlet pipe 206 or is connected to the inlet pipe, resulting in an inlet pipe 206 that rotates during operation of the solid-bowl screw centrifuge 1. Since, in the variant of the also rotating outlet pipe 101, the inlet pipe 206 and the liquid phase Fl to be discharged rotate in the same direction, advantageously less turbulence occurs during the discharge of the liquid phase Fl from the rotating drum 200.

[0074] According to Fig. 1, Fig. 3 and Fig. 4, the screw 300 can each be composed, for example, of two subsections. The screw 300 here has a first, cylindrical screw segment 318, which here essentially comprises the cylindrical screw hub section 305 and a cylindrical screw helix section 303. The screw 300 further has a second, conical screw segment 319, which essentially comprises the conical screw hub section 305 and a conical screw helix section 303. Both segments 318, 319 of the screw 300 are connected to one another in a rotationally fixed manner by suitable connecting means (not shown here, e.g. a screw connection or a weld).

[0075] By dividing the screw 300 into two segments 318, 319 or assemblies in this way, the dimensions of the components to be manufactured for the screw 300 can be smaller than with a conventional, one-piece screw. This results in advantages in the production and assembly of the screw 300.

[0076] A plunger disc 320 can be arranged at a joint between the first, cylindrical segment 318 and the second, conical segment 319 of the two-part screw 300 and, for example, clamped between the two segments 318, 319 of the screw 300. It holds the liquid phase Fl in the cylindrical part of the drum 200 and the screw 300.

[0077] By providing immersion disks 320 with different outer diameters and exchanging them, the properties of the screw 300 can be adapted, which may be necessary if, for example, the composition of the supplied suspension Su to be clarified changes significantly with regard to the proportions of liquid phase Fl and solid phase Fe.

[0078] List of reference symbols

[0079] 1 solid bowl screw centrifuge

[0080] 100 rotors

[0081] 101 drain pipe

[0082] 200 drum

[0083] 201 cylindrical drum section

[0084] 202 conical drum section

[0085] 203 Drum cover

[0086] 204 Fluid drain

[0087] 205 Solids discharge

[0088] 206 Inlet pipe

[0089] 207 first drum bearing unit

[0090] 208 second drum bearing unit

[0091] 209 inner ring

[0092] 210 Separation room

[0093] 300 snail

[0094] 301 cylindrical screw section

[0095] 302 conical screw section

[0096] 303 Snail spiral egg

[0097] 304 Worm hub

[0098] 305 cylindrical worm hub section

[0099] 306 conical worm hub section

[0100] 307 first worm bearing unit

[0101] 308 second worm bearing unit

[0102] 309 guiding elements

[0103] 310 top edge

[0104] 311 space

[0105] 312 bottom edge

[0106] 313 cross-pane

[0107] 314 Worm hub cover

[0108] Section 315

[0109] 316 Opening

[0110] 317 inner ring

[0111] 318 cylindrical screw segment

[0112] 319 conical screw segment

[0113] 320 diving disc

[0114] Su Suspension

[0115] Fe solid phase

[0116] Fl liquid phase

[0117] D axis of rotation d diameter

Claims

Claims 1 . A solid bowl screw centrifuge (1) for processing a suspension Su in a centrifugal field, comprising at least the following: a) a rotatable drum (200) with a rotational axis (D), b) an inlet pipe (206) projecting into the drum (200) and arranged concentrically to the rotational axis (D), through which inlet pipe the suspension Su to be processed can be guided into a separation chamber (210) of the drum (200), c) at least one liquid outlet (204) for the outlet of a liquid phase Fl, d) at least one solids outlet (205) for the discharge of a still flowable solid phase Fe, e) a screw (300) arranged in the drum (200) and rotatable at a differential speed relative to the rotatable drum (200), f) wherein the discharge of the liquid phase Fl from the drum (200) takes place through a discharge element which, at least in the region of its inlet, is arranged both radially inwardly to an inner ring (317) a bearing of a first screw bearing unit (306),and preferably also arranged radially inwardly to an inner ring (209) of a bearing of a first drum bearing unit (207).

2. Solid bowl screw centrifuge (1) according to claim 1, characterized in that the discharge element is arranged completely both radially inward to an inner ring (317) of a bearing of a first screw bearing unit (306), and radially inward to an inner ring (209) of a bearing of a first drum bearing unit (207).

3. Solid bowl screw centrifuge (1) according to claim 1 or 2, characterized in that the discharge element rotates during operation of the solid bowl screw centrifuge (1).

4. Solid bowl screw centrifuge (1) according to claim 1 or 2, characterized in that the discharge element is stationary during operation of the solid bowl screw centrifuge (1).

5. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the discharge element is a discharge pipe (101).

6. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the screw (300) has a screw flight (303) which is formed externally on a worm hub (304) and projects radially or substantially radially therefrom.

7. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the screw hub (304) has a plurality of guide elements (309) extending in the radial direction and aligned in a beam-like manner, distributed circumferentially in a cylindrical screw hub section (305).

8. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the liquid phase Fl can be guided out of the drum (200) coaxially to the inlet pipe (206) and along the inlet pipe (206).

9. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the drum (200) has a cylindrical drum section (201) and a conical drum section (202).

10. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the screw (300) has a first, cylindrical screw segment (318) which comprises a cylindrical screw hub section (305) and a cylindrical screw helix section (303), and a second, conical screw segment (319) connected to the first screw segment (318) which comprises a conical screw hub section (306) and a conical screw helix section (303).

11. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that a replaceable immersion disc (320) is arranged in a transition region between the cylindrical screw segment (318) and the conical screw segment (319).

12. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the guide elements (309) are fastened in the axial direction to axially spaced transverse discs (313) or to a screw hub cover (314).

13. Solid bowl screw centrifuge (1) according to claim 12, characterized in that the transverse discs (313) divide at least the cylindrical screw hub section (305) in the axial direction in a partition-like manner into a plurality of chamber-like, cylindrical sections (315), through which the guide elements (309) arranged circumferentially and extending in a radial direction.

14. Solid bowl screw centrifuge (1) according to claim 12 or 13, characterized in that the transverse discs (313) have a plurality of preferably circumferentially distributed through openings (316) so that the suspension Su to be separated and its phases Fl, Fe can flow unhindered in the radial and in particular also axial direction in the cylindrical screw hub section (305).

15. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the screw flight (303) is fastened in the region of the cylindrical screw hub section (305) on upper edges (310) of the guide elements (309) or radially outwardly on the guide elements (309), whereby intermediate spaces (311) are formed between the guide elements (309) and the screw flight (303) so that suspension Su introduced into the inlet pipe (206) or the phases Fl, Fe separated or clarified therefrom can flow radially outwards or inwards.

16. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the guide elements (309) each have a lower edge (312) on their radially inner side.

17. Solid bowl screw centrifuge (1) according to claim 16, characterized in that the respective lower edge (312) of the guide elements (309) extends radially up to close to the axis of rotation D, but does not touch the inlet pipe (206) here, whereby an inlet pipe (206) which is stationary here during operation of the solid bowl screw centrifuge (1) is realized.

18. Solid bowl screw centrifuge (1) according to claim 16, characterized in that the respective lower edge (312) of at least some of the guide elements (309) extends at least in places to the inlet pipe (206) or is connected to the inlet pipe, thereby resulting in an inlet pipe (206) rotating during operation of the solid bowl screw centrifuge (1).

19. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the respective guide element (309) is flat and is arranged in a radial direction.

20. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the guide elements (309) are formed from profiles with a V-shaped cross-section with straight or concave flanks, the narrower side of the profile pointing axially inwards and the wider side pointing axially outwards. 21 . Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the respective guide element (309) is curved in the manner of a turbine blade.

22. Solid bowl screw centrifuge (1) according to one of the preceding claims, characterized in that the counterpressure for the liquid phase Fl can be changed by changing the inner diameter d of a discharge pipe (101) for the liquid phase Fl.

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