EP2658656B1 - Solid bowl screw centrifuge having an overflow weir - Google Patents

Description

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

Solid bowl centrifuges are known in various embodiments.

So revealed the DE 102 03 652 B4 a solid bowl screw centrifuge with a device for discharging clarified liquid from a drum having a drum cover with a passage to which a throttle device, in particular a throttle plate, is assigned, whose distance from the passage is variable. In this case, the passage further nozzles are assigned to the outlet of the clarified liquid, which are aligned for energy saving inclined to the radial direction through the drum axis.

Nozzles on solid bowl centrifuges and their effect of energy saving with a corresponding orientation inclined to the drum axis are further from the DE 39 04 151 A1 known.

The publication " Patent Abstracts of Japan, number 11179236 A discloses, in contrast, that passage openings in the drum cover, which are each partially closed by a weir plate, which form an overflow weir, baffles can be assigned, which give the liquid emerging from the drum a spin, the recoil effect occurring is to be used to save energy. The baffles are attached to the outside of the overflow weir, for example to the weir plates. They are for example formed as flat sheets, which are aligned parallel to the drum rotation axis, wherein the plane in which lie the flat sheets, the drum axis does not intersect and approximately at an angle of about 45 ° with the radially extending straight line, which in each case by the drum rotation axis and the respective passage opening extends.

It is also known - so from the US 2004/0072668 A1 or the WO 2008/138345 A1 - Instead of an overflow weir on the weir plate of the passage opening to assign a housing, in which case the overflow weir or a nozzle are formed in a sloping side of the housing at the passage opening. However, these constructions have the disadvantage that on the outside of the drum cover co-rotating, relatively complicated shaped liquid chambers are formed, which form part of the rotating system, so that in the fluid chambers nor the clarification or Separation process continues. This separation process can result in unwanted deposits in the chambers, which bring cleaning problems and unbalance problems with it.

The technological background in terms of claim 1 nor the JP 2009 136790 A , the JP 56 129842 U and with respect to claim 14 the DE 38 22 983 A1 called, the latter font sections revealed obliquely inclined to the axis of rotation drain holes in the drum cover, which should direct a liquid phase from the outside in the drum further inward to a drain weir.

Starting from this prior art, the object of the invention is to provide a solid shell screw centrifuge optimized with regard to energy saving, which can also be regarded as advantageous from a hygienic point of view.

The invention solves this problem by the subject matter of claims 1 and 13.

Below are some special advantages of the claimed and described embodiments together.

First, a main advantage of the different embodiments with drainage channels is explained. Liquids with fibrous solids may, in a complicated designed passage opening to the problem that the fibers get stuck on exit from the housing in certain areas, so provided for receiving the weir plate grooves. This can happen especially during shutdowns, when the liquid ring collapses suddenly due to small centrifugal forces but constant gravitational force and the drum empties spontaneously. Especially in housings as a device for the discharge of liquid, as have been variously proposed in the prior art, product deposits can easily form, since a near-surface layer flow is formed, which can not rinse the central regions of the housing of solids. Due to the open design of the drainage channels, the o.g. Disadvantages avoided.

According to the proposed new means for discharging liquid from the centrifuge drum deposits are also avoided because the liquid flows over the entire liquid cross-section and thus also near the wall of the outlet and so can entrain solid particles. This is an advantage from a sanitary point of view but also constructive in terms of the reduced risk of the formation of potential imbalances made of non-rotationally symmetric deposited solid. Such uneven solid deposits may form, among other things, when the centrifuge is stopped and are flushed out of the random standstill position of the rotor solids by the collapsing liquid ring unbalanced or even the solid itself flows out of the outlet elements asymmetrically.

The variants of the invention with the open drainage channel is also advantageous in that the present invention leaves the overflow weir directly to the weir plates on the drum cover and only the liquid, which has already left the rotating system on the overflow weir, is deflected in the circumferential direction. After emerging from the drum, no clearing effect can occur any more, but the entire outgoing liquid jet is deflected by the deflector in the circumferential direction.

It is also advantageous that the chosen constructions also avoid that the liquid contained in the housing exert too high unwanted additional centrifugal forces on the drum. In particular, the outlet or discharge channels can not fill with liquid, it forms only a relatively thin layer of liquid that exerts relatively little additional forces.

By extending one or both of the elements "bottom wall" and "one or both side walls" with the above-described inclination towards the center of rotation, it can be ensured that the deviation of the liquid outflow from the ideal tangential direction is minimized.

The inclined passage openings in the end-face drum wall combined with a weir plate without outlet element or with a weir plate which has a "grooved" contour and in particular the embedded in the drum wall insert have the advantage that the required space in the axial direction for the rotor relative is small. This makes it possible to minimize the use of material for the rotor, the frame carrying the rotor and the housing surrounding the rotor. In addition, the storage distance is shortened, which can be due to the improved machine dynamics properties achieve higher speeds of the centrifuge, as the speed-limiting natural frequencies shift to higher values.

The design with an insert embedded in the drum wall offers the advantage that adjustments of the inner contour to product properties and also to operating parameters, such as, for example, the throughput capacity are possible without changing the drum wall. The inserts can also be easily exchanged.

Further advantageous embodiments can be found in the remaining subclaims.

Fig. 1

eine schematische Ansicht einer bekannten Vollmantel-Schneckenzentrifuge; und

Fig. 2 - 14

verschiedene Ansichten, Schnitte Darstellungen und Ausgestaltungen von Einrichtungen zum Ableiten von Flüssigkeit aus einer Zentrifugentrommel, ausgebildet an einem Trommeldeckel einer Zentrifugentrommel.

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

Fig. 1

a schematic view of a known solid bowl screw centrifuge; and

Fig. 2-14

various views, sections representations and embodiments of means for discharging liquid from a centrifuge drum formed on a drum lid of a centrifuge drum.

The figures below is partially associated with a schematic representation of a coordinate system in the center of which the axis of rotation D of a centrifuge drum is located and in which the arrow U indicates the direction of rotation of a centrifuge drum. The line D 'denotes a parallel to the axis of rotation D and the arrow R the radial direction perpendicular to the axis of rotation D.

Fig. 1 should first clarify the basic structure of a solid bowl centrifuge. The drive together with control, a hood and other for the expert obvious elements are not shown here.

Fig. 1 shows a solid bowl screw centrifuge 1 with a preferably horizontal axis of rotation D rotatable drum 3, in which a likewise rotatable screw 5 is arranged. The drum 3 and the screw 5 each have a substantially cylindrical portion and a conically tapered portion here.

An axially extending centric inlet pipe 7 serves to supply the centrifuged material via a distributor 9 into the centrifugal space 11 between the screw 5 and the drum 3.

If, for example, a muddy slurry is fed into the centrifuge, coarser solid particles settle on the drum wall. Further inward, a liquid phase forms.

The screw 5 rotates at a slightly lower or greater speed than the drum 3 and conveys the ejected solid to the conical portion out of the drum 3 to the solids discharge 13th

The liquid, in contrast, flows to the larger drum diameter at the rear end of the cylindrical portion of the drum 3 and is discharged through a weir having passage openings 15 in a drum cover 17, each passage opening 15 is associated with a weir plate 19, which here radially adjustable on the outside the drum lid is attached. The inner radial edge of the weir plate thus defines an overflow edge and thus also the actual weir or overflow weir 21. The passage opening 15 and the weir plate 19 with the overflow weir 21 form in Fig. 1 each in their interaction a "means 23 for the discharge of liquid from the centrifuge drum" from. It is preferably provided to provide not only one of these devices 23 on the drum cover, but to distribute at least one radius in each case several of these devices in the circumferential direction.

Advantageously, all the above variants are advantageously supplemented by a radial adjustability of the weir plates 19. This adjustability can also be achieved, for example, simply via hole patterns 37 (see FIG Fig. 5 ) with selectable radial holes or bores on the weir plate and corresponding bores on the drum cover and bolts or the like. Realized to thereby allow easy adjustment of the liquid level diameter in the drum. The hole patterns are for simplicity only in Fig. 5 illustrated, but preferably provided in all versions.

According to the invention, for example, in a solid bowl centrifuge on the type of Fig. 1 the drum cover and / or the at least one device 23 for the discharge of liquid from the centrifuge drum by a corresponding device 23 'of Fig. 2 to 14 be replaced.

First, the embodiments of the Fig. 2 to 4 described.

The 3 and 4 show plan views of two different devices 23 'and Fig. 2 shows a section through a corresponding device 23 '. These are in each case modified devices 23 'for discharging liquid from a centrifuge drum, which in turn comprise one or more passage openings (s) 15 in a drum cover 17 at a certain radius outside the axis of rotation D and in each case one the associated passage opening 15 completely or partially covering weir plate 19.

The devices 23 'further each have a discharge channel 25, which is formed on the respective weir plate 19 and / or formed integrally therewith.

The weir plate 19 of Fig. 2 to 4 is preferably directly outside the drum cover 17 aligned parallel to the drum cover 17 at.

The weir plates 19 of Fig. 2 In each case, towards the rotation center D, a material recess 27, which further releases the passage opening 15 "again" radially further outward, is provided.

As a result, the weir 21 is placed in this area on a further outward at the bottom of the recess radius R27.

The material recess 27 on the outside of the weir plate 19 preferably merges into the discharge channel 25 in alignment. It thus forms the beginning of the discharge channel 25 itself.

The discharge channel 25 can (see Fig. 5 ) consist only of the material recess 27 when the weir plate 19 is sufficiently thick and the material recess accordingly in an inclination angle γ (see Fig. 6 ) is aligned with the direction of rotation U. Preferably, however, the material recess is lengthened by a groove element 29 extending the weir plate on its side facing away from the drum 1.

The discharge channel 25 is designed to be open at least on its radially inward-pointing side and preferably also on its end remote from the weir plate 19.

The discharge channel has lateral deflection walls 31a, 31b, which may be flat or curved.

The cross section of the discharge channel 25 - see, for example Fig. 2 - can be designed in different ways. It is essential that the discharge channel 25 is radially open inwards towards the axis of rotation D, preferably completely (in particular in the direction of flow of the exiting liquid). Especially the completely inwardly open design is insensitive to contamination, the Contamination tendency can be further reduced by rounding off corner areas of the discharge channel 25.

The cross section of the discharge channel 25 can be correspondingly angular ( Fig. 3 ) or rather rounded ( Fig. 4 ). The cross-section can be constant over the length of the discharge channel or change.

To FIGS. 5 and 6 the drainage channel 25 is formed on structurally particularly simple and cost-effective and again insensitive to contamination only in that the weir plates 19 each have no elongated channel member 29 but that only the material recess 27 is provided on the weir plate whose side walls 31a, 31b in the circumferential direction not are axially aligned but opposite to the direction of rotation obliquely or bent, so as to deflect the exiting flow against the rotational direction. The weir plates 19 of FIGS. 5 and 6 Due to their configuration, for the sake of simplicity, they are also referred to below as "grooved" weir plates 19.

In the devices for the discharge of liquid 23 'of Fig. 2 to 4 with "square" or "rounded" discharge channel 25, this is thus "inside and outside" of the weir plate 19, in the "grooved" weir plate 19 of FIGS. 5 and 6 on the other hand, the discharge channel 25 is designed exclusively "inside" the weir plate 19.

The overflow weir 21 of the embodiments according to the Fig. 2 to 6 is located at the inlet of the liquid in the material recess 27 of the weir plate 19, which thus determines the diameter of the liquid level in the drum.

After the Fig. 2 to 6 the bottom wall 35 of the channel 25 runs in a straight line in the tangential direction.

The liquid outlet of the grooves is at an angle β to the rotation axis D with β> 0 ° and β preferably> = 20 ° and by an angle γ relative to the rotational direction U tilted. For the angle γ, the following applies preferably: γ> = 0 ° and γ <90 ° and particularly preferably: γ> = 0 ° and γ <30 °. This embodiment is preferred.

Alternatively, it is also conceivable that the angle γ is less than 0 °, for example, less than -30 ° (not shown), even if this occurs an exit of the liquid phase in the direction of the drum cover itself.

However, it is also conceivable that the depth of the channel (s) 25 changes (in particular with respect to the plane corresponding to Fig. 2 ; not shown). The FIGS. 7 and 8 show further embodiments of outlet elements, which have a radially inwardly open discharge channel 25.

To FIGS. 7 and 8 By way of example, it is provided that the gutter element 29 of the discharge channel has a shape running concentrically on a circular arc section with a constant radius. Therefore, in particular, the bottom wall 35, in whole or in sections, has a rounded shape, in particular concentric with the center of rotation.

While the Fig. 2 to 8 Embodiments relate to which in any case wholly open drainage channels 25 in a weir plate 19 and preferably in an axial groove-like extension - channel element 29 - the weir plate 19 are formed, it is also conceivable to redirect the liquid flowing out of the drum 1 in the circumferential direction in that the drum cover itself has passage openings 15 which do not extend in the axial direction, but which are inclined relative to the longitudinal axis D of the drum by an angle β. The passage openings 15 are thus, for example, although cylindrical in itself, but oriented obliquely to the axis of rotation, wherein the angle δ between the axis of rotation D and the central axis of the passage openings 15 in any case in sections greater than 0 ° and smaller than 90 °.

Preferably, the angle of inclination δ is: δ> = 20 ° and δ <= 60 ° ( FIGS. 9 and 10 ). Alternatively, the passage opening can also be curved in itself. Mixed forms of the described embodiments are readily feasible.

Each of the "inclined" passage openings 15 is preferably covered by a corresponding weir plate 19 up to a predetermined radius. In this case, this covering weir plate 19 each have a "straight" overflow edge or weir edge 21, which is on a predetermined, preferably by means of hole patterns or the like. Adjustable radius.
It is also conceivable, the "inclined" passage openings with weir plates 19 in the manner of Fig. 2 to 8 to combine, ie with weir plates having a kind of discharge channel 25, at least in the form of a groove contour, in order to achieve such a particularly advantageous discharge behavior.

So show the FIGS. 11 and 12 Versions with inclined passage openings 15 in the front-side drum wall 17 and weir plates 19, a "grooved" beveled contour of the type Fig. 6 or 7 exhibit.
Fig. 13 further shows an embodiment, which advantageously the inclined passage openings 15 in the end-side drum wall 17 in each case with one of the weir plates 19 with a channel element 29 in the manner of Fig. 2 or 3 combined.

The Fig. 14 also illustrates the ability to insert into the openings 15 of the drum cover inserts 41, for example, threaded inserts which are screwed into screw holes of the drum cover 17, these inserts can be used even in axial bores of the drum cover and then in turn may have holes 43 which are inclined are aligned to the drum axis D and D '.

Fig. 14 shows a variant in which parallel to the longitudinal axis D of the drum extending bores 43 are formed in the end-side drum wall, which are each provided with an insert 41 having a bore 43 in the interior, whose central axis relative to the rotational direction U of the drum by an angle δ: δ> = preferably 15 ° and δ <= preferably 75 ° inclined ( Fig. 14 )

The inserts 41 in the drum wall or in the drum cover can be configured in various ways.

Thus, the axial extent of the insert 41 of the axial thickness of the drum wall and the axial thickness of the drum cover correspond ( Fig. 14 ).

It is also theoretically possible to implement a variant of the insert 41, in which this - for example -. with a plate-like flange portion or the like. - Projecting beyond the end face of the drum (not shown). Also conceivable is an insert 41 in the drum wall - as described above, with a Abspritzkante (not shown).

Particularly advantageous is the combination of the insert 41 in the drum wall in the manner of Fig. 14 in combination with a device 23 'after Fig. 2 to 5 , So with a weir plate according to one of the preceding Fig. 1 to 13 , <B> reference numerals </ b> Solid bowl centrifuge 1 drum 3 slug 5 inlet pipe 7 distributor 9 centrifugal chamber 11 solids 13 Passage openings 15 drum lid 17 weir plate 19 Overflow weir 21 Device for the discharge of liquid 23, 23 ' drain gutter 25 material recess 27 An element 29 baffles 31a, 31b bottom wall 35 hole patterns 37 Calls 41 drilling 43 outside 45 radius R27 radial direction R direction of rotation U axis of rotation D Parallel to D D ' tilt angle α, β, δ, γ directions x, y

Claims (16)

1. Solid-bowl screw centrifuge having at least one device (23') for the discharge of clarified liquid from a rotatable drum (3),

   a. wherein the device (23') has at least one or more passage openings (15) in a drum cover (17),

   b. wherein the at least one passage opening (15) is assigned in each case one weir plate (19) which, at its radial inner edge, has and forms in each case one overflow weir (21),

   characterized in that

   c. the weir plate (19) has a material recess which forms at least a part of a discharge channel (25) or a complete discharge channel (25),

   d. wherein the discharge channel (25) is designed such that it diverts the flow emerging from the drum counter to a direction of rotation and at an angle β > 0° and β <= 90° with respect to the axis of rotation and not in the direction of the drum cover.
2. Solid-bowl screw centrifuge according to Claim 1, characterized in that, at the outer side (45), averted from the interior of the drum, of the weir plate (19), the material recess (27) transitions preferably in a flush manner into a channel element (29) which is attached to or integrally formed on the weir plate, such that the discharge channel (25) is formed from the material recess (27) and the channel element (29).
3. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the discharge channel (25) is of open form at least on its radially inwardly pointing side.
4. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the discharge channel (25) is of open form at its end averted from the weir plate (19).
5. Solid-bowl screw centrifuge according to one or more of the preceding claims, characterized in that the channel element (29) is of open form entirely or in sections in a radially inward direction.
6. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the discharge channel (25) has lateral diverting walls (31a, 31b) which are oriented such that the flow emerging from the drum is inclined at the angle γ with respect to the direction of rotation or plane of rotation (U).
7. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the cross section of the discharge channel (25) is of polygonal or rounded design.
8. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the discharge channel (25) has a base wall (35) which runs rectilinearly in a tangential direction (U).
9. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the weir plate (19), at its side averted from the drum cover, does not have an elongated channel element (29) rather has merely the material recess (27), the side walls (31a, 31b) of which are oriented not axially but rather obliquely or in a curved manner with respect to the direction of rotation (U) or plane of rotation in order to thus divert the emerging flow somewhat or entirely in the direction of rotation or plane of rotation, such that the weir plates have a grooved form.
10. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the liquid outlet of the discharge channel (25) is oriented so as to be inclined by an angle γ relative to the plane of rotation.
11. Solid-bowl screw centrifuge according to Claim 10, characterized in that, for the angle γ, the following applies: γ >= 0° and γ < 90°.
12. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the base wall (35, 35') of the discharge channel (25) has, over its entire length or in sections, a rounded form running in particular concentrically with respect to the centre of rotation.
13. Solid-bowl screw centrifuge according to one of the preceding claims or according to the preamble of Claim 1, characterized in that the drum cover (17) has one or more passage openings (15) which are in each case oriented so as to be inclined by an angle δ with respect to the longitudinal axis (D) of the drum (1) in the circumferential direction or circumferential plane for the purposes of diverting emerging liquid counter to the direction of rotation, which angle is, at least in sections or preferably entirely, greater than 0° and smaller than 90° and for which angle in particular the following applies: δ >= 20° and δ<= 60°.
14. Solid-bowl screw centrifuge according to Claim 13, characterized in that each of the inclined passage openings (15) is partially covered by a corresponding weir plate (19).
15. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that, into the one or more passage openings (15), there is inserted in each case one insert (41), the inner contour of which is oriented so as to be inclined by an angle δ with respect to the axis of rotation (D) of the drum.
16. Solid-bowl screw centrifuge according to one of the preceding Claims 13 to 15, characterized in that the angle δ is equal to the angle β.

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