Solid bowl screw centrifuge

Abstract

Disclosed is a solid bowl screw centrifuge for clarifying a fed suspension Su in a centrifugal field of a solid phase Fe, having a housing and a rotor (200) rotatably mounted in the housing, wherein the inner diameter of a feed pipe (400) initially increases in the axial direction towards the conical section of a screw (230) in the direction of flow, such that a first feed pipe section (402) is formed, in which a centrifugal pre-separation of a part of the solid phase Fe from the suspension Su occurs, wherein first means (403) are available, through which a first portion Su' with a higher solids content compared to the suspension Su can be introduced into the centrifugal chamber (216) in the radial direction, and wherein a second feed pipe section (405) also adjoins the first feed pipe section (402) axially in the direction of flow, through which the remaining second portion Su" of the suspension Su that is not discharged through the first means (403) and has a lower solids content compared with the suspension Su is guided further axially through the feed pipe (400), wherein second means (406) are provided, through which the remaining second portion Su" of the suspension Su can be introduced into the centrifugal chamber (216) in the radial direction.

Description

[0001] Solid bowl screw centrifuge

[0002] The invention relates to a solid bowl screw centrifuge according to the preamble of claim 1.

[0003] A solid-bowl screw centrifuge—also known as a decanter in technical terms—can separate a solid phase from a suspension. Optionally, the suspension, once cleared of solids, can be separated into different liquid phases in a design with two liquid outlets. Solid-bowl screw centrifuges are ideally suited to processing relatively high solid concentrations in the feed stream, are comparatively robust, achieve excellent separation results, and ensure effective drying of the solids.

[0004] Known solid-bowl screw centrifuges with a frame that is non-rotatable or non-rotating during operation have a rotatable or rotating rotor, which in turn has a bowl and a screw that rotates at a speed different from that of the bowl. For the discharge of the solids, essentially radially aligned solids discharge openings are provided in a conical section of the bowl.

[0005] Some suspensions or products to be separated or clarified by centrifugal separation - for example, those to which a flocculant has been added - are shear-sensitive and require very gentle acceleration and handling in a solid-bowl screw centrifuge to achieve the desired sedimentation and clear separation.

[0006] In many cases, the suspension to be clarified or separated - also called product - is fed into the solid bowl screw centrifuge via a stationary inlet pipe, which guides the suspension axially / laminarly into a distribution chamber, where it is then accelerated and deflected to then enter the separation chamber of the solid bowl screw centrifuge radially.

[0007] In the distribution chamber, the suspension is subjected to high acceleration in a very turbulent environment. This can lead to high shear forces in the suspension and, particularly in the case of polymer-supported flocculation of the suspension, reduce the efficient separation, as the bond between the flocculant and the solid to be separated is broken again. From DE 28 22 533, it is known that the incoming product is fed from a stationary inlet pipe into a rotating distribution chamber, the outlets of which, however, do not reach into the separation chamber of the solid-bowl screw centrifuge, in which the liquid phase separated from the suspension collects, which is also referred to in technical terms as a "pond" or "pool" (see DE 2522 533, Figure 1a). A supply line for a flocculant can be arranged in the stationary inlet pipe.

[0008] EP 0 099 267 discloses a distribution chamber for solid-bowl screw centrifuges. This chamber is equipped with feed sleeves whose outlet openings end in the "pool," i.e., extend into the separation chamber of the solid-bowl screw centrifuge, where the liquid phase separated from the suspension collects (see EP 0 099 267, Fig. 5). The feed pipe does not rotate.

[0009] EP 1 225 981 discloses a distribution chamber for solid-bowl screw centrifuges. These are equipped with feed sleeves whose outlet openings end in the "pool," i.e., extend into the separation chamber of the solid-bowl screw centrifuge, where the liquid phase separated from the suspension collects (see EP 1 225 981, Fig. 1). The feed pipe rotates at the screw speed.

[0010] A disadvantage of the state-of-the-art solutions is the not always optimal introduction of the suspension into the distribution chamber and finally into the separation chamber, which entails the risk of turbulent flow in the distribution chamber and the occurrence of shear forces in the suspension cannot be completely ruled out, so that the micro- or macro-flocs of the solid phase created by the addition of the flocculant are destroyed by the shear forces, thus resulting in unsatisfactory solid separation.

[0011] The state of the art should therefore be optimized with regard to the clarification properties, for example in the case where a suspension Su of solids to which a flocculant has been added is to be clarified.

[0012] The solution to this problem is the object of the invention.

[0013] The invention solves this problem by the subject matter of claim 1.

[0014] Accordingly, a solid bowl screw centrifuge is provided, designed for clarifying an incoming suspension Su in a centrifugal field from a solid phase Fe, for this purpose provided with a housing and a rotor rotatably mounted in the housing, wherein the rotor has at least the following: with a housing and a rotor rotatably mounted in the housing, which has at least the following:

[0015] - a rotatable drum with a rotation axis, the drum having a cylindrical section and a conical section,

[0016] - an inlet pipe extending into the drum and arranged concentrically to the axis of rotation D, through which the suspension Su to be processed can be fed into a centrifugal chamber of the drum,

[0017] - at least one liquid outlet arranged in the cylindrical section of the drum and

[0018] - at least one solids discharge arranged in the conical section of the drum,

[0019] - a screw arranged in the drum, which can rotate relative to the rotating drum at a differential speed, the drum and the screw together forming the rotor,

[0020] - the inlet pipe rotates during operation of the solid bowl screw centrifuge, and

[0021] - wherein the inner diameter of the inlet pipe initially increases in the axial direction towards the conical section of the screw in the flow direction in such a way that a first inlet pipe section is formed in which a centrifugal pre-separation of a part of the solid phase Fe from the suspension takes place, wherein first means are provided by which a first portion Su' of the suspension with a higher solids content compared to the suspension Su can be introduced into the centrifugal chamber in the radial direction, and

[0022] - wherein the first inlet pipe section is further adjoined axially in the flow direction by a second inlet pipe section, through which the remaining second portion Su" of the suspension Su, not discharged by the first means, with a lower solids content compared to the suspension Su close to the axis of rotation of the inlet pipe, is guided axially further through the inlet pipe, wherein second means are provided by which the remaining second portion Su" of the suspension can be introduced into the centrifugal chamber in the radial direction.

[0023] Due to the centrifugal acceleration near the axis of rotation, a pre-separation of a portion of the solid phase can already occur in the rotating inlet pipe in the first inlet pipe section with a radially expanding diameter under a relatively low effect of shear forces due to the still relatively small radius - compared to the average radius of the centrifuge chamber and the shear forces occurring there. Due to the minimal effect of shear forces in the suspension, an added flocculant can act as intended so that micro- or macro-flocs of the solid phase formed by the flocculant are not destroyed by shear forces, thus resulting in very good solids separation. The first agents then introduce a corresponding first portion Su' of the suspension with a higher solids content compared to the supplied suspension Su in a radial direction into the centrifuge chamber.At another point of the rotating inlet pipe, the remaining second portion Su" of the suspension is then introduced into the centrifugal chamber in a radial direction by the second means.

[0024] It is preferably provided that the maximum inner diameter of the inlet pipe in the first inlet pipe section is larger than the inner diameter of the second inlet pipe section.

[0025] In a particularly preferred embodiment of the invention, the inner diameter of the inlet pipe in the first inlet pipe section increases continuously over its axial length. This allows for pre-separation of the solid phase with particularly minimal shear forces on the solid phase in the inlet pipe using simple structural means.

[0026] In another particularly preferred embodiment of the invention, the first inlet pipe section forms an inner cone. This allows a continuous expansion of the inner diameter of the inlet pipe to be achieved using simple structural means that are equally easy to implement in terms of manufacturing technology.

[0027] Alternatively, in a further preferred embodiment of the invention, the first inlet pipe section can also be provided in the shape of an inner paraboloid. This also allows a continuous expansion of the inner diameter of the inlet pipe to be achieved using simple structural means that are equally easy to implement in terms of manufacturing technology.

[0028] In a further particularly preferred embodiment of the invention, the first means by which a first portion Su' of the suspension Su can be introduced radially into the centrifuge chamber can be designed as at least one first feed sleeve extending radially from the first inlet pipe section into the centrifuge chamber. This enables a gentle introduction of the first portion Su' of the suspension Su into the centrifuge chamber using structurally simple means that are equally easy to implement in terms of manufacturing technology.

[0029] Furthermore, in a further particularly preferred embodiment of the invention, the respective first feed sleeve forms an outlet nozzle through which the first portion Su' of the suspension Su is fed into the centrifuge chamber at a first radius R1. The first radius R1, at which the respective first feed sleeve opens into the centrifuge chamber, is selected such that the discharge of the first portion Su' of the suspension Su into the corresponding solids-bearing layer in the centrifuge chamber is advantageously enabled without turbulence occurring during introduction that could disrupt other phases. The first radius can preferably be larger than the mean radius of the centrifuge chamber in the cylindrical section.

[0030] In a further particularly preferred embodiment of the invention, it is provided that during operation in the region of the outlet nozzle, such a counterpressure acts that a further portion Su" of the suspension Su flows further downstream, close to the axis of rotation D of the inlet pipe, into the second inlet pipe section of smaller diameter. In this way, the suspension Su is already divided in the inlet pipe into a portion Su' with a higher solids content and a portion Su" with a lower solids content compared to the solids content of the suspension Su to be clarified.

[0031] It is also provided in a further particularly preferred embodiment of the invention that the second means, through which the other portion Su" of the suspension Su can be introduced radially into the centrifuge chamber, are designed as at least one second feed sleeve extending radially from the inlet pipe into the centrifuge chamber. This enables a gentle introduction of the other portion Su" of the suspension Su into the centrifuge chamber using structurally simple means that are equally easy to implement in terms of manufacturing technology.

[0032] Furthermore, in a further particularly preferred embodiment of the invention, it is provided that the respective second feed sleeve forms an outlet nozzle through which the other portion Su" of the suspension Su is fed into the centrifuge chamber at a radius R2. A second radius R2, at which the respective second feed sleeve opens into the centrifuge chamber, is selected such that the discharge of the other portion Su" of the suspension Su into the corresponding layer in the centrifuge chamber, which essentially consists of the liquid phase, advantageously takes place without major turbulence occurring during the introduction, which could disturb other phases.

[0033] The second radius can be selected to be smaller than the mean radius in the cylindrical section of the centrifuge chamber. The second radius is therefore preferably smaller than the first radius. The difference between the two radii at which the respective feed sleeves open into the centrifuge chamber enables the discharge of particles or heavy / light liquid phases (F1) into the corresponding layer in the centrifuge chamber without causing significant turbulence during introduction, which could disrupt other phases.

[0034] In a further particularly preferred embodiment of the invention, it is provided that the introduction of the first portion Su' of the suspension Su by the first means takes place closer to the liquid discharge than the introduction of the remaining portion Su" of the suspension Su by the second means.

[0035] For example, it can be provided that the Su' portion is introduced into the centrifuge chamber so close to the drum lid that the solid phase Fe contained therein has to travel a long distance within the centrifuge chamber before leaving the drum at the solids discharge. This ensures that the solid phase of the suspension Su', introduced through the first feed sleeve, has a maximum residence time in the centrifuge chamber before being discharged from the drum. This advantageously results in an optimized separation efficiency.

[0036] In a further particularly preferred embodiment of the invention, it can be provided that the introduction of the other portion Su" of the suspension Su into the centrifuge chamber takes place relatively close to the conical section of the drum, so that the liquid phase Fl contained therein must travel a relatively long distance in the centrifuge chamber until it finally leaves the drum at the liquid outlet. This provides the liquid phase of the suspension Su" introduced through the second feed sleeve with a maximum residence time in the centrifuge chamber before being discharged from the drum. This advantageously results in an optimized separation efficiency.

[0037] The object is also achieved by the following method: A method for the centrifugal clarification of a suspension Su, so that a solid phase Fe and at least one liquid phase Fl are formed, in a provided solid bowl screw centrifuge according to one of the preceding claims, wherein a.the suspension Su is fed into the centrifugal chamber of the solid bowl screw centrifuge through an inlet pipe which rotates during operation of the solid bowl screw centrifuge, wherein the inner diameter of the inlet pipe initially increases in the axial direction towards the conical section of the screw in the flow direction in such a way that a first inlet pipe section is formed in which a centrifugal pre-separation of a part of the solid phase Fe from the suspension Su takes place, wherein first means are provided by which a first portion Su' of the suspension with a higher solids content compared to the suspension Su is introduced into the centrifugal chamber in the radial direction, and b.wherein the first inlet pipe section is further adjoined axially in the direction of flow by a second inlet pipe section, through which the remaining second portion Su" of the suspension Su, not discharged by the first means, with a lower solids content compared to Su, is guided further axially through the inlet pipe close to the axis of rotation of the inlet pipe, wherein second means are provided by which the remaining second portion Su" of the suspension is introduced into the centrifuge chamber in the radial direction, and c. whereupon a further clarification of the two suspension portions takes place in the centrifuge chamber.

[0038] Further advantageous embodiments of the invention can be found in the subclaims.

[0039] The invention is described in more detail below with reference to exemplary embodiments and the drawings. Features described in connection with these exemplary embodiments can also be used in other—not shown—embodiments of the invention and are therefore also usable as features in claims. They show:

[0040] Figure 1: a schematic sectional view of a rotor of a solid bowl screw centrifuge according to the invention;

[0041] Figure 2: an enlargement of a section of Fig. 1 ; and

[0042] Figure 3: A schematic sectional view of a prior art solid-bowl screw centrifuge. The following description of the figures describes one or more embodiments of a solid-bowl screw centrifuge. Individual or multiple features of these embodiments can also be used in other embodiments not shown, which are encompassed by the claims.

[0043] First, the solid bowl screw centrifuge of Fig. 3 of the prior art will be described, which is modified and further developed according to the invention in Figs. 1 and 2.

[0044] Fig. 3 shows a solid bowl screw centrifuge for processing a suspension Su in a centrifugal field with a frame 100 which is non-rotatable or non-rotating during operation - which can be designed as a type of housing - and a rotor 200 which is rotatable or rotating during operation.

[0045] The rotor 200 has a rotatable drum 210 with a horizontal axis of rotation D. However, the axis of rotation D can also be oriented differently in space, particularly vertically. The rotor 200 also includes a screw 230 arranged in the drum 210, the axis of rotation of which coincides with the axis of rotation D of the drum 210.

[0046] The drum 210 has a cylindrical section 211 with a length L1 and an axially adjoining conical section 212 with a length L2. The cylindrical section 211 is closed here by a substantially radially extending drum cover 213. In the conical section 212 with the length L2, the drum 210 is preferably conical on the inside and outside (relative to the drum shell).

[0047] The screw 230 also has a cylindrical section 231 and an axially adjoining conical section 232. It is arranged within the drum 210. During operation, the screw 230 can be rotated at a speed different from that of the drum 210.

[0048] An inlet pipe 214 extends into the drum 210. This inlet pipe is arranged concentrically to the axis of rotation D here and is preferably stationary during operation of the solid-bowl screw centrifuge. This inlet pipe opens into a distribution chamber 215 through which a suspension Su to be processed can be guided radially into a centrifugal chamber 216 of the drum 210. The inlet pipe 214 can either be led into the drum 210 from the side of the cylindrical drum section 211 or it can be led into the drum 210 from the side of the conical drum section 212. The distribution chamber 215 is arranged here in the drum 210 in the cylindrical drum section 210 and is positioned in the axial direction shortly before the end of the cylindrical drum section 210, to which the conical drum section 212 adjoins.

[0049] One or more liquid outlets 217 can be formed in or on the drum cover 213. These can be designed in various ways, such as openings in the drum cover 213 that function as a kind of overflow weir, or in other ways, such as a peeling disc.

[0050] At least one solids discharge 218 is formed in the conical section 212, in particular in the end region of the conical section 212.

[0051] The drum 210 is designed as a solid-shell drum. In the rotating drum 210, at least one liquid phase Fl is clarified from solids Fe. The at least one liquid phase Fl exits the liquid outlet 217 at the drum cover 213. The solids Fe, however, are transported by the screw 230 toward the solids discharge 218 and ejected from the drum 210 there. It is also conceivable that a supplementary separation into two liquid phases also occurs if appropriate outlets are provided for these liquid phases.

[0052] A first drum shaft section 220, which is connected in a rotationally fixed manner to the drum 210, can be axially connected to the drum cover 213 or to the actual drum 210, and a second drum shaft section 219, which is also connected in a rotationally fixed manner to the drum 210, can be axially connected to the conical drum section 212.

[0053] A first worm shaft section 234, which can be connected to the worm 230 in a rotationally fixed manner, is axially connected to the cylindrical section 231 of the worm 230. The conical section 232 is mounted on a bearing 235. This bearing 235 can be mounted on a second worm shaft section 233.

[0054] A drive device, which may include one or two motors, is used to drive the rotor 200. At least one gear 310 can be connected downstream of the drive device 300. Two pulleys 320, 330 are schematically shown here, indicating that the gear 310 can have at least two interfaces for feeding a respective torque from the motor(s) into the gear 310 to drive the drum 210 and the worm 230. Alternatively (not shown here), the rotor 200 can also be driven in another way.

[0055] According to Fig. 3, the gear 310 rotates the drum 210 on the one hand and the worm 230 on the other. For this purpose, the gear 310 can have two output shafts. The first output shaft can be non-rotatably coupled to the first drum shaft section 220 or directly coupled to the drum 210. The second output shaft, on the other hand, can be non-rotatably coupled directly or indirectly to the first worm shaft section 234 or directly to the worm 230.

[0056] The drum 210 can be rotatably mounted by two drum bearings 221, 222 arranged axially offset 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 individual bearings, which are then arranged axially directly adjacent to one another, so that they can each be considered functionally as a single bearing.

[0057] The drum bearings 221, 222 can advantageously be arranged between the drum 210 and the frame 100 or one or more elements connected to the frame so that the drum 210 can be rotated relative to the frame 100. This also applies to all other variants shown. The drum bearings 221, 222 are preferably arranged radially between the drum 210 and the frame 100 or one or more elements connected to the frame.

[0058] The screw bearings 235, 236, however, can be arranged radially between the screw 230 and the drum 210, so that the screw 230 can be rotatable relative to the drum 210.

[0059] In a possible design variant (not shown), one of the screw bearings 235 in the area of ​​the solids discharge 218 can be omitted. This can be provided, for example, with a vertical arrangement of the decanter.

[0060] One or even both drum bearings 221, 222 can be arranged within the axial region located between the solids discharge 218 and the liquid outlet 217 of the drum 210 or directly adjacent to a region of the liquid outlet 217 and / or a solids discharge 218 of the drum 210. The drum bearings 221, 222 are then positioned radially outward on the drum 210 or radially or axially outward on or on the drum cover 213. If one of the drum bearings 221, 222 is arranged within the axial region located between the solids discharge 218 and the liquid discharge 217 of the drum 210, the other of these bearings—the other of the drum bearings 221, 222—can be arranged outside this axial region.

[0061] It can be provided that the drum bearings 221, 222 for supporting the drum 210 in the housing 100 are spaced apart by a distance LL, wherein the distance LL of the drum bearings 210 from one another is smaller than the axial length LT of the drum.

[0062] The solids discharge 218 can be designed such that the openings of the solids discharge 218 are aligned radially or substantially in the radial direction of the drum 210.

[0063] The solids discharge 218 in the prior art solid-bowl screw centrifuge shown in Fig. 3 is designed such that the openings 224 of the solids discharge 218 are aligned axially or substantially in the axial direction of the drum 210. They are also preferably located within the smallest diameter of the conical region 212 of the drum 210.

[0064] During operation, solids in the rotating drum 210 are first conveyed from a suspension Su rotating radially outward in the drum 210 from the cylindrical region into the conical region 212 of the drum 210 and from there further conveyed or pushed radially inward to the solids discharge 218.

[0065] For this purpose, a solids discharge drum cover 223 adjoins the conical section of the drum 210 in the axial direction, axially closing off the conical section 212 of the drum 210. The solids discharge drum cover 223 can be conical in its entirety or in sections. The solids discharge 218 can be designed in such a way that the openings 224 of the solids discharge 218 are aligned axially or substantially in the axial direction of the drum 210.

[0066] The solids discharge drum lid 223 can have one or more, for example, four, openings 224, which form the solids discharge 218. These can be designed as window-like, circumferentially closed openings in the conical section of the solids discharge drum lid 223. This prior art design has proven successful in practice, but it should be optimized with regard to its clarification properties, for example, in the case where a suspension Su of solids to which a flocculant has been added is to be clarified.

[0067] The flocculant serves to form larger microflocs or even larger macroflocs from the solid components of the suspension Su. These flocculants can be easily separated from the suspension Su by the clarification or separation process in the solid bowl screw centrifuge. Problems arise when turbulent flow occurs in the distribution chamber of the solid bowl screw centrifuge, and the microflocs or macroflocs are destroyed by the occurrence of corresponding shear forces in the suspension Su.

[0068] Figures 1 and 2 each show the rotor 200 of an exemplary solid-bowl screw centrifuge according to the invention. This can be constructed, for example, in the manner shown in Figure 3, except for the design of the inlet pipe, but can also have a different type of bearing or a different type of drive.

[0069] The rotor 200 of the solid-bowl screw centrifuge also has a rotatable bowl 210 with a horizontal axis of rotation D. However, the axis of rotation D can also be oriented differently in space, particularly vertically. The rotor 200 also includes a screw 230 arranged in the bowl 210, the axis of rotation of which coincides with the axis of rotation D of the bowl 210.

[0070] The drum 210 also has a cylindrical section 211 with a length L1 and an axially adjoining conical section 212 with a length L2. The cylindrical section 211 is closed here by a drum cover 213. In the conical section 212 with the length L2, the drum 210 is preferably conical on the inside and outside (relative to the drum shell).

[0071] The screw 230 also has a cylindrical section 231 and an axially adjoining conical section 232. It is arranged within the drum 210. During operation, the screw 230 can be rotated at a speed different from that of the drum 210.

[0072] One or more liquid outlets 217 can also be formed in or on the drum cover 213. These can be designed in various ways, such as openings in the drum cover 213 that function as a kind of overflow weir, or in another way, such as a paring disc.

[0073] At the end of the conical section 212 of the drum 210, at least one solids discharge 218 is also formed.

[0074] The drum 210 is also designed as a solid-shell drum. In the rotating drum 210, at least one liquid phase Fl is clarified from solids Fe. The at least one liquid phase Fl exits the liquid outlet 217 at the drum cover 213. The solid phase Fe, on the other hand, is transported by the screw 230 toward the solids discharge 218 and ejected from the drum 210 there.

[0075] An inlet pipe 400 extends into the drum 210. This inlet pipe is arranged concentrically to the rotational axis D and rotates during operation of the solid-bowl screw centrifuge, or rotates with the drum 210 or the screw, through which a suspension Su to be processed can be fed into the centrifugal chamber 216 of the drum 210. The inlet pipe 400 can either be guided into the drum 210 from the side of the cylindrical drum section 211 or it can be guided into the drum 210 from the side of the conical drum section 212.

[0076] The inlet pipe 400 can also assume the function of the screw shaft or form this function. It is rotatably mounted in the bowl 210. The screw 230 can be assembled, e.g., welded, from the screw shaft with the inlet pipe 400 and a screw flight. Alternatively, a one-piece screw 230 with the screw shaft and the inlet pipe 400 located in the screw shaft is also possible. In this respect, the inlet pipe 400 rotates at the screw speed during operation of the solid-bowl screw centrifuge.

[0077] The bearings for the worm 230, or more precisely the worm shaft, can in turn be provided with a first worm bearing 235 and a second worm bearing 236. The first worm bearing 235 and the second worm bearing 236 are each arranged radially between the worm 230 and the drum 210, so that the worm 230 is rotatable relative to the drum 210. The first worm bearing 235 and the second worm bearing 236 are each designed as rolling bearings. The respective rolling bearing can be single-row or multi-row. Combinations of several rolling bearings per bearing point are also possible. The first worm bearing 235 is positioned here in the axial direction shortly before the end of the cylindrical drum section 210, to which the conical drum section 212 adjoins. In a possible design variant (not shown), one of the screw bearings 235 in the area of ​​the solids discharge 218 can be omitted. This can, for example,be provided for a vertical arrangement of the decanter.

[0078] The second screw bearing 236 is arranged here in the axial direction in the region of the drum cover 213 between the drum shaft section 234, which here projects axially into the drum 210 in the direction of the conical drum section 212, and the screw shaft with the inlet pipe 400.

[0079] An inner ring of the second screw bearing 236 can be placed on a shoulder 237 of the drum cover 213, while an outer ring of the second screw bearing 236 is inserted into a bore 401 of the screw shaft section 234 arranged coaxially to the rotational axis D of the inlet pipe 400.

[0080] The inner diameter of the inlet pipe 400 is not constant. Rather, the inner diameter initially increases, in particular continuously, in a first section in the axial direction from the inlet to the conical section 232 of the screw 230. Thus, a first inlet pipe section 402 with an increasing diameter is formed. This first inlet pipe section 402 forms an inner cone. It is also possible for the first inlet pipe section 402 to have an inner paraboloid or another geometry with an inner diameter that continuously increases in the axial direction toward the conical section 232 of the screw 230.

[0081] Through this widening, in particular through a continuous widening of the inlet pipe 400 in the area of ​​the first inlet pipe section 402, a rotating annular space is created in which the centrifugal forces can already cause an initial centrifugal separation, a type of "pre-clarification". As a result, heavier fractions of the supplied suspension Su collect on the inside of the outer wall of the conical first inlet pipe section 402 due to the forces acting on the suspension Su in the rotating inlet pipe 400. In this way, a certain pre-separation / pre-clarification of the solid phase Fe advantageously already takes place in the inlet pipe 400 and from the supplied suspension Su, a partial stream Su' with a higher solids content compared to the solids content of the suspension Su and a partial stream Su" with a lower solids content is formed. The conical inlet pipe section can be provided - preferably on its inner circumference - with one or more entrainment elements such asThe ribs can be provided so that the incoming suspension can be more easily accelerated to the speed of the inlet pipe. The ribs can, for example, extend essentially radially inward from the inner diameter of the conical inlet pipe section and can also run axially.

[0082] In the region of the largest diameter of the first inlet pipe section 402, first means 403 are provided through which the partial flow Su' can be introduced radially into the centrifuge chamber 216. The first means 403 is designed here as at least one first feed sleeve 403. The respective first feed sleeve 403 extends substantially radially from the region of the largest diameter of the first inlet pipe section 402 into the centrifuge chamber 216 and can form an outlet nozzle 404. The respective first feed sleeve 403 guides the partial flow Su' into the centrifuge chamber 216 at a suitable first radius R1 through the respective first feed sleeve 403. The outlet nozzle 404 can preferably have a smaller diameter, but also the same diameter, as the remaining feed sleeve 403.

[0083] Due to the "early" axial introduction of the partial flow Su' into the centrifuge chamber 216, the solid phase Fe contained in this partial flow must travel a relatively long axial path to the solids discharge 218, thereby achieving good further separation. The term "early" means that the introduction of the pre-separated solid phase Fe into the centrifuge chamber 216 occurs axially in the X direction with respect to the coordinate system in Fig. 1, relatively close to the drum cover 213, so that the solid phase Fe must travel a relatively long path in the centrifuge chamber 216 until it finally leaves the drum 210 as solid phase Fe at the solids discharge 218.

[0084] By suitably dimensioning the diameter of the outlet nozzle 404, a sufficient back pressure is generated such that the partial flow Su" of the suspension Su can flow radially further inward or close to the axis of rotation D of the inlet pipe 400 further downstream into a second inlet pipe section 405 viewed axially in the direction X, wherein second means 406 are provided through which the remaining portion Su" of the suspension Su can be introduced in the radial direction into the centrifugal chamber 216.

[0085] The second inlet pipe section 405 does not have a continuously increasing diameter, but can be provided with a constant diameter. This diameter is smaller than the largest diameter of the first inlet pipe section. Alternatively, the second inlet pipe section 405 can also be designed with a continuously increasing diameter. It is also possible for the inlet pipe 400 to have more than two inlet pipe sections 402, 405 that are fluidically connected to one another.

[0086] The second means 406, through which the other portion Su" of the suspension Su can be introduced in the radial direction into the centrifuge chamber 216, is designed here as at least one second feed sleeve 406, which extends from the second inlet pipe section essentially in the radial direction into the centrifuge chamber 216. It can form an outlet nozzle 407. The other portion Su" of the suspension Su is guided into the centrifuge chamber 216 through the respective second feed sleeve 406 at a suitable second radius R2.

[0087] This second portion Su" of the suspension Su may contain some, particularly relatively light, solid particles and essentially the liquid phase Fl.

[0088] The radius R2, over which the other portion Su" of the suspension Su is introduced into the centrifugal chamber 216, is preferably smaller than the radius R1, over which the first portion Su' of the suspension Su is introduced into the centrifugal chamber 216.

[0089] Due to the axially relatively “late” introduction of the other second portion Su” of the suspension Su into the centrifuge chamber 216, the liquid phase Fl contained therein has to travel a relatively long way “back” to the liquid outlet 217, which also optimizes the clarification process.

[0090] The term “late” means that the introduction of the other portion Su” of the suspension Su into the centrifuge chamber 216 takes place relatively close to the conical section 212 of the drum 210, so that the liquid phase of the suspension Su” introduced through the second feed sleeve has to travel a relatively long distance in the centrifuge chamber 216 until it finally leaves the drum 210 at the liquid outlet 217 as the liquid phase Fl.

[0091] The inventive design of the inlet pipe 400 results in a number of advantages:

[0092] In the area of ​​increasing radius, a preliminary separation of the solid phase Fe can already occur in the inlet pipe due to centrifugal forces, but with a relatively low impact of shear forces. This is because the centrifugal forces close to the rotation axis in the first inlet pipe section are still relatively small compared to the shear forces occurring in the centrifugal chamber.

[0093] In particular, a larger portion of the solid phase Fe can already be discharged from the first inlet pipe section 402 into the centrifuge chamber 216 with the first portion Su' of the suspension Su. Since the respective feed sleeve 403 forms an outlet nozzle 404, at which a counterpressure is generated during operation, another portion Su" of the suspension Su will flow further into the second inlet pipe section 402. The inlet into the second inlet pipe section 402 has a smaller diameter than the largest diameter of the first inlet pipe section, from which a first portion of the suspension is fed into the drum.

[0094] The respective radius R1, R2, at which the respective feed sleeves 403, 406 open into the centrifuge chamber 216 as the first and second feed means for the respective suspension Su' and Su", enables the discharge of particles (or heavy / light liquid phases Fl) into the corresponding layer in the centrifuge chamber 216 without causing major turbulence during the introduction, which would disturb other phases.

[0095] Each phase of the suspension Su receives an optimized residence time in the centrifuge chamber 216 before it is discharged from the drum 210.

[0096] Further inlet pipe sections or pre-separation stages can be provided in the inlet pipe 400 and thus added up to a final stage in which the remaining product (mainly the remaining liquid phase Fl) is discharged into the centrifuge chamber 216 through feed sleeves without nozzles and thus without counterpressure.

[0097] List of reference symbols

[0098] 200 rotor

[0099] 210 Drum

[0100] 211 cylindrical section

[0101] 212 conical section

[0102] 213 Drum cover

[0103] 216 Spinning room

[0104] 217 Fluid drain

[0105] 218 Solids discharge

[0106] 219 Drum shaft section

[0107] 220 drum shaft section

[0108] 221 drum bearings

[0109] 222 drum bearings

[0110] 223 Solids discharge drum cover

[0111] 224 Opening

[0112] 230 snail

[0113] 231 cylindrical section

[0114] 232 conical section

[0115] 233 Worm shaft section

[0116] 234 Worm shaft section

[0117] 235 worm bearings

[0118] 236 worm bearings

[0119] 237 paragraph

[0120] 300 drive device

[0121] 310 gearbox

[0122] 320 pulley

[0123] 330 pulley

[0124] 400 inlet pipe

[0125] 401 paragraph

[0126] 402 first inlet pipe section

[0127] 403 first feed sleeve

[0128] 404 Outlet nozzle

[0129] 405 second inlet pipe section

[0130] 406 second feed sleeve

[0131] 407 Outlet nozzle D rotation axis

[0132] Li length

[0133] L2 Length LL Distance drum bearing

[0134] Su Suspension

[0135] Su' partial flow of the suspension

[0136] Su“ partial flow of the suspension

[0137] Fe solids Fl liquid phase

[0138] R1 radius

[0139] R2 radius

Claims

Claims: A solid-bowl screw centrifuge for clarifying an incoming suspension Su in a centrifugal field of a solid phase Fe, comprising a housing (100) and a rotor (200) rotatably mounted in the housing (100), the rotor comprising at least the following: a) a rotatable drum (210) with an axis of rotation (D), wherein the drum (210) has a cylindrical section (211) and a conical section (212), b) an inlet pipe (400) projecting into the drum (210) and arranged concentrically to the axis of rotation D, through which the suspension Su to be processed can be directed into a centrifugation chamber (216) of the drum (210), c) at least one liquid outlet (217) arranged in the cylindrical section (211) of the drum (210), and d) at least one solids discharge (218) arranged in the conical section (212) of the drum (210). e) a screw (230) arranged in the drum which is rotatable relative to the rotatable drum (210) at a differential speed,characterized in that f) the inlet pipe (400) rotates with the rotor during operation of the solid-jacket screw centrifuge, g) the inner diameter of the inlet pipe (400) initially increases in the axial direction towards the conical section (232) of the screw (230) in the flow direction such that a first inlet pipe section (402) is formed in which a centrifugal pre-separation of a portion of the solid phase Fe from the suspension Su takes place, wherein first means (403) are provided through which a first proportion of Su' with a higher solids content compared to the suspension Su can be introduced radially into the centrifuge chamber (216), and h) a second inlet pipe section (405) is further connected axially in the flow direction to the first inlet pipe section (402), through which the remaining,The second fraction Su of the suspension Su, which has a lower solids content compared to the suspension Su and is not derived by the first means (403), is further guided axially through the feed pipe (400), wherein second means (406) are provided, through, the remaining second part Su" of the suspension Su can be introduced in a radial direction into the centrifugal chamber (216).

2. Solid-jacket screw centrifuge according to claim 1, characterized in that the inner diameter of the inlet pipe (400) in the first inlet pipe section (402) increases continuously over its axial length.

3. Solid-jacket screw centrifuge according to claim 1 or 2, characterized in that the first inlet pipe section (402) forms an inner cone.

4. Solid-jacket screw centrifuge according to claim 1 or 2, characterized in that the first inlet pipe section (402) forms an inner paraboloid.

5. Solid-jacket screw centrifuge according to one of the preceding claims, characterized in that the first means (403) by which the first portion Su' of the suspension Su can be introduced in a radial direction into the centrifuge chamber (216) are designed as at least one first feed sleeve (403) extending radially from the first feed pipe section (402) into the centrifuge chamber.

6. Solid jacket screw centrifuge according to one of the preceding claims, characterized in that the respective first feed sleeve (403) forms an outlet nozzle (404) through which a first portion Su' of the suspension Su is directed on a first radius (R1 ) into the centrifuge chamber (216).

7. Solid jacket screw centrifuge according to claim 6, characterized in that during operation, a back pressure is generated by the respective outlet nozzle (404) such that the other portion Su" of the suspension Su flows further downstream into the second inlet pipe section (405) near the axis of rotation D of the inlet pipe (400).

8. Solid-jacket screw centrifuge according to one of the preceding claims, characterized in that the second inlet pipe section (405) has a diameter that is smaller than the largest diameter of the first inlet pipe section.

9. Solid-jacket screw centrifuge according to one of the preceding claims, characterized in that the second means (406), through which the other part Su" of the suspension Su can be introduced in a radial direction into the centrifuge chamber (216), are designed as at least a second feed sleeve (406) extending radially into the centrifuge chamber (216).

10. Solid jacket screw centrifuge according to one of the preceding claims, characterized in that the respective feed sleeve (403, 406) forms an outlet nozzle (404, 407).

11. Solid-wall screw centrifuge according to claim 10, characterized in that the radius R2, through which the other part Su" of the suspension Su is introduced into the centrifuge chamber (216), is smaller than the radius R1, through which the first part Su' of the suspension Su with the solid phase Fe separated during the pre-clarification is introduced into the centrifuge chamber (216).

12. Solid-wall screw centrifuge according to one of the preceding claims, characterized in that the first means by which the first part Su' of the suspension Su can be introduced in a radial direction into the centrifuge chamber (216) are formed closer to the drum lid (213) than the second means by which the other part Su" of the suspension Su can be introduced in a radial direction into the centrifuge chamber (216).

13. Solid-wall screw centrifuge according to one of the preceding claims, characterized in that the introduction of the other portion Su" of the suspension Su into the centrifugation chamber (216) by the second means takes place closer to the conical section (212) of the drum (210) than the introduction of the first portion Su" of the suspension Su by the first means 14. Solid-jacket screw centrifuge according to one of the preceding claims, characterized in that the conical feed pipe section (402) - preferably on its inner circumference - is provided with one or more driving elements to assist in accelerating the incoming suspension to the rotational speed of the feed pipe.

15. Solid-jacket screw centrifuge according to claim 14, characterized in that the driving element(s) are designed as one or more ribs.

Images