EP1480754B1 - Three-phase solid-wall helical centrifuge, solid-wall helical centrifuge and method for operation of a three-phase solid-wall helical centrifuge - Google Patents

Abstract

The invention relates to a three-phase solid-wall helical centrifuge and method for operation of a three-phase solid-wall helical centrifuge with a first internal weir (15), relative to the drum longitudinal axis, for drawing off a first light liquid phase (L1) and a second external weir (17), for drawing off a second heavier liquid phase (L2) from the spinning drum (3), characterised in that the second weir (17) comprises a through opening (37) provided with a throttling device (35) the separation of which from the through opening (37) may be altered.

Description

The invention relates to a three-phase solid bowl screw centrifuge according to the preamble of claim 1 and a method for operating such a three-phase solid bowl screw centrifuge according to the preamble of claim 12.

From the EP 0 733 646 B1 is a three-phase solid bowl screw centrifuge known in which a heavy liquid phase of grain adhesive and fine starch and a light liquid phase of water and soluble components are discharged from the centrifugal space. In this case, the heavy liquid phase is digested via a peeling system, while the water of the further lighter liquid phase is discharged via a further separation system, in particular a second peeling system. Alternatively, the lighter liquid phase over weeds may leave the solid bowl screw centrifuge in free fall. Between an adjustable peeling disk of the first peeling system and the centrifuge drum, a high difference in the relative speed is set.

This prior art has several problems. The two peeling systems together are relatively expensive. In addition, there are products which are only partially processable with peeling discs, e.g. because they put the two peeling discs. But the main problem is that with the two peeling discs a controllability of the two phases in terms of flow rates, especially the heavier phase is given only limited.

The invention has over this prior art of EP 0 733 646 B1 the task of further developing the three-phase solid bowl screw centrifuge so that in a simple and low-maintenance manner a precise setting of the discharge amount of the heavier liquid phase can be realized. It is also intended to provide an advantageous and simple method of operating this three-phase solid bowl screw centrifuge.

The state of the art is still the DE 41 30 759 A1 called. In the document, a two-phase solid bowl screw centrifuge is presented, which has closable emptying openings in the outer drum shell of a closing member.

From the WO 97/20634 It is also known to assign a Vollmantel-Schneckenenzentrifuge a control computer.

The invention achieves this goal with respect to the three-phase solid bowl snail centrifuge by the subject-matter of claim 1 and with respect to the method by the subject-matter of claim 12.

With regard to the three-phase centrifuge it is provided that the second weir for discharging the heavy liquid phase has a passage, which is associated with a throttle device whose distance from the passage is variable.

With regard to the method, a first lighter liquid phase is drained via a first, inner weir and a second, heavier liquid phase via a second, outer weir, wherein to vary the amount of draining heavier liquid phase, the distance of a throttle means to a passage of the second weir changes becomes.

Preferably, the throttle device is designed as a stationary during operation of the centrifuge, and preferably as a throttle plate, which does not rotate with the drum and is radially adjustable relative to the outlet.

Although a throttle device of this kind is in principle already out of the DE 43 20 265 A1 known. The disclosed in this document solid bowl screw centrifuge is provided at the liquid outlet side with a weir, which has a passage which may be formed by a plurality of outgoing from the inner diameter of the weir grooves or openings provided in the walls of the weir. The passage is assigned during rotation of the drum relative to this stationary throttle plate, which is axially displaceable via a threaded bushing. By turning the threaded bush, the distance between the weir and the throttle plate can be changed. As a result, the outflow cross section, which has an effect on the liquid level in the centrifuge, changes for the liquid draining from the centrifugal drum.

This effect plays within the scope of the invention, however, no or only a negligible role. Rather, it is contrary to expectations, with the throttle device in a simple manner to make only a setting of the discharge amount of the second liquid phase in a three-phase centrifuge. It is conceivable, however, also form the inner weir, for example, in the manner of this document, ie to make the distance of a throttle device to a passage of the second weir changeable.

With the invention, it is therefore possible to regulate the discharge amount of the heavy liquid phase in a particularly simple manner by adjusting the throttle device, e.g. depending on the decanter inlet quantity and / or the torque of the worm and / or the differential rotational speed between the worm and the drum and / or the motor current. This regulation is carried out in particular automatically and preferably with a control computer assigned to the centrifuge.

With the invention, however, can be compensated by the control of the heavy liquid phase in a particularly simple manner fluctuations in the composition of the incoming product. This is particularly advantageous for natural products, as often changes in these products, the composition of the ingredients such as starch, glue, mucilage (pentosans), etc.

While an adjustment of the differential speed during operation of the centrifuge is known per se, in order to change the discharge amount of the heavy liquid amount, e.g. When using nozzles, the centrifuge are stopped and another nozzle can be used. Even when using a second peeling system for the heavier liquid phase, a variation of the discharge amount of the heavy liquid phase was limited. This variation can now be done in a simpler and more accurate manner and in particular also directly during the operation of the centrifuge.

This has significant advantages in operation since it is precisely the three-phase technique which aims to separate the heavy liquid phase ingredients (e.g., glue, fine starch) from the light phase ingredients (e.g., mucilage, pentosans). Since satisfactory automatic control of the heavier liquid phase has not yet been possible, too many ingredients of one (e.g., the light) liquid phase have come into the other (e.g., heavier liquid phase) with a change in product nature during operation. This is avoided with the invention.

Particularly advantageous is the invention and the given with it controllability of the heavy liquid phase in the processing of products in which the carrier liquid does not have large differences in density (in contrast to the example of water / oil), so that often forms no significant separation zone.

The DE 100 21 983 A1 suggests a pivotable, nichtmitrotierenden throttle plate for a two-phase centrifuge, which on the principle of the throttle disc of DE 43 20 265 A1 is based, in addition, to provide the throttle plate with an annular groove, which is referred to as "Ringtasse".

After a less preferred variants, which is structurally complex, it is also conceivable that the throttle device is designed as a co-rotating with the drum throttle device, in particular throttle plate, whose distance from the passage is adjustable. From the EP 0 586 382 B1 . Fig. 5 In a three-phase centrifuge with two liquid phases to be derived, it is known to assign the inner weir a co-rotating, inflatable dam. An inflatable or inflatable dam is for this purpose also from the DE 199 62 645 A1 known.

The invention further provides, according to a further, independently considered thought of a solid bowl screw centrifuge with at least one weir for discharging a liquid phase from the centrifugal drum, wherein the at least one weir has a passage, which is associated with a throttle device whose distance or position relative is variable to the passage, wherein the throttle device comprises a throttle ring which is so movable, in particular displaceable, guided over a radially outwardly directed passage opening of the passage that is adjustable by adjusting the position of the throttle ring relative to the passage opening of the outlet cross section at the passage opening.

This arrangement with the displaceable throttle ring (especially also a cylindrical, sleeve-like part) over the one or more substantially radially outwardly directed passage opening (s) is suitable both for the derivation of the heavier phase from a three-phase centrifuge and for controlling the liquid level in one Two-phase centrifuge with a single drain.

It is particularly advantageous that the throttle ring, a particularly compact - especially short in the direction of the drum longitudinal axis - design of a throttle device is realized.

The throttle ring is advantageously formed as in operation relative to the rotating drum stationary part. This embodiment is structurally particularly simple.

Alternatively, it is also conceivable for a less optimal, as structurally complex embodiment, that the throttle ring is designed as a part rotating in operation with the drum.

Further advantageous embodiments can be found in the remaining subclaims.

Preferably, the discharge amount of the heavy liquid phase is automatically controlled.

Figur 1

eine erfindungsgemäße Vollmantel-Schneckenzentrifuge;

Figur 2

den Bereich des Wehres der Vollmantel-Schneckenzentrifuge aus Figur 1;

Figur 3

den Bereich des Wehres einer zweiten erfindungsgemäßen Vollmantel- Schneckenzentrifuge;

Figur 4

den Bereich des Wehres einer dritten erfindungsgemäßen Vollmantel- Schneckenzentrifuge und

Figur 5

den Bereich des Wehres einer vierten erfindungsgemäßen Vollmantel- Schneckenzentrifuge.

Hereinafter, embodiments will be described with reference to the drawings. It shows:

FIG. 1

a solid shell screw centrifuge according to the invention;

FIG. 2

the area of the weir of the solid bowl centrifuge FIG. 1 ;

FIG. 3

the area of the weir of a second solid bowl screw centrifuge according to the invention;

FIG. 4

the area of the weir of a third solid bowl screw centrifuge according to the invention and

FIG. 5

the range of the weir of a fourth inventive solid bowl screw centrifuge.

FIG. 1 shows a three-phase solid bowl screw centrifuge 1 with a drum 3, in which a 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.

For example, if 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 promotes the ejected solid to the conical portion out of the drum 3 to the solids discharge 13. The liquid, however, flows to the larger drum diameter at the rear end of the cylindrical portion of the drum 3 and is there by a first inner - ie Weir 15 and an outer second weir 17, which are closer to the axis of rotation, are derived in two separate liquid phases L1 and L2.

The area of Weirs 15 and 17 is in Fig. 2 shown enlarged.

To FIG. 2 The first inner, ie the weir closer to the axis of rotation 15, has a passage 19 in an axial cover 21 of the drum 3, to which a paring disc 23 is arranged downstream in the outflow direction.

The paring disc 23 is arranged in an inner annular space 25 of a ring piece 27 with a cylindrical projection 29, wherein the discharge of the liquid through the paring disc 23 in a channel 33 between the inner circumference of a likewise cylindrical projection 31 of the paring disc 23 and the outer circumference of the inlet tube 7 takes place ,

Here, the inner edge of the passage 19 in the radial direction of the cover 21 is offset radially inwardly relative to the inner circumference of the centrifugal space or relative to the outer circumference of the screw body.

By the peeling disk 23, the first liquid phase is advantageously discharged under pressure. By adjusting the first weir can - within certain limits - additionally adjust the liquid level (throttling). A control method for decanters describes the EP 0 868 215 B1 , The use of peeling disk-like discharge organs (peeling head) in decanters is in principle from the DE 33 44 432 known, but not in the chosen combination of features with adjustable outer weirs.

The derivation of the second liquid phase L2 is carried out by the further weir 17, which has an adjustable throttle device 35, which is arranged downstream of a further radially outwardly in the cover 21 passage 37 which penetrates both the lid 21 and the ring member 27 axially.

The adjustable throttle device 35 has a throttle plate 39 whose distance from the passage 29, for example, in the DE 43 20 265 A1 described manner is variable with a variety of drive devices.

To Fig. 1 the throttle disk 39 is attached to one end of at least one bolt 41, which is here exemplarily axially displaceable by a motor 43 (also conceivable by hand), so that the distance between the stationary in operation throttle disk 39 and the at least one (or more) Passage 37 by axial movement, in particular by an axial displacement (also feasible by pivoting) of the throttle plate 39 is variable relative to the rotating drum 3 in operation.

It should be emphasized that differently than after the doctrine of DE 43 20 265A1 Here, the throttle device surprisingly not for adjusting the liquid level in the drum but primarily for adjusting the discharge amount of the second liquid phase L2 is used.

The embodiment of FIG. 3 largely corresponds to the FIG. 1 and 2 However, the first weir 15 is not assigned to a paring disc, but it is designed as a simple adjustable overflow weir and has only the (in cross section, for example by a flap) adjustable, not visible here) passage 19 in the lid 21, of which the first liquid phase L1 free - and not under pressure - expires, so that if necessary, a pump for discharging the first liquid phase L 1 is provided.

The embodiment of FIG. 4 is different from that of FIG. 3 in that the throttle disk 51 is indeed axially adjustable, but co-rotates with the drum. Unlike in the embodiment of FIG. 2 Here, the drive (not shown) for axially adjusting the throttle slide 51 rotate relative to its holder 45 with the drum 3, which is the design effort and in particular the maintenance of the embodiment of the FIG. 2 significantly increased, but the possibility to control the heavy liquid phase obtained obese. For axial displacement of the throttle disk 51, for example, a spring and / or hydraulic system (not shown) can be used.

To FIG. 5 the passage 37 (with any cross-section) in the ring piece 27 is guided axially outward, wherein instead of a throttle plate, a preferred throttle ring 47th is provided, which is axially displaceably guided over the radially outwardly directed passage opening 49 (again by means of an arrangement of axially adjustable bolt 41 and motor 43). This is by adjusting the position of the throttle ring - which must not be cylindrical but may have another shape eg with bevelled or chamfered inner circumference - relative to the passage opening 49, the cross section of the passage opening 49 more or less released and changed the flow rate of the second liquid phase L2 ,

LIST OF REFERENCE NUMBERS

Solid bowl centrifuge 1 drum 3 slug 5 inlet pipe 7 distributor 9 centrifugal chamber 11 solids 13 weir 15 weir 17 Passage 19 cover 21 peeling disc 23 annulus 25 banjo 27 approach 29 Passage 29 approach 31 channel 33 throttling device 35 passage 37 throttle disc 39 bolt 41 engine 43 bracket 45 throttle ring 47 Port 49 throttle disc 51 Port 53 liquid phase L1 liquid phase L2

Claims (12)

1. Three-phase solid-wall helical centrifuge, with a first weir (15), internal in relation to the drum longitudinal axis, for discharging a first, lighter liquid phase (L1) out of the centrifugal drum (3) and with a second, outer weir (17) for discharging a second, heavier liquid phase (L2) out of the said centrifugal drum (3), characterized in that

   a) the second weir (17) has a passage (37) which is assigned a throttle device (35), of which the distance from the passage (37) is variable,

   b) the centrifuge is assigned a control computer which is designed for regulating the outlet quantity of the heavy liquid phase by computer control as a result of the setting of the throttle device.
2. Three-phase solid-wall helical centrifuge according to Claim 1, characterized in that regulation takes place automatically as a function of the decanter inflow quantity and/or of the torque of the helix and/or of the differential rotational speed between the helix and drum and/or of the motor current.
3. Three-phase solid-wall helical centrifuge according to Claim 1 or 2, characterized in that the throttle device (35) has a throttle disc (39) which is adjustable in relation to the passage (37) and which is designed as a part which is stationary when the centrifuge is in operation.
4. Three-phase solid-wall helical centrifuge according to Claim 3, characterized in that the distance of the throttle disc (39) from the passage (37) is variable as a result of the axial displacement of the throttle disc (39) in relation to the passage (37) .
5. Three-phase solid-wall helical centrifuge according to Claim 1 or 2, characterized in that the throttle device (35) has a throttle device, in particular a throttle disc (51), which corotates with the drum (3) and of which the distance from the passage (37) is adjustable.
6. Three-phase solid-wall helical centrifuge according to one of the preceding claims, characterized in that the throttle device has a throttle ring (47) which is guided movably, in particular displaceably, via a radially outward-directed passage orifice (53) of the passage (37).
7. Three-phase solid-wall helical centrifuge according to one of the preceding claims, characterized in that the first weir (15) lying nearer the axis of rotation of the drum (3) has an inner passage (19) in an axial cover (21) of the drum (3).
8. Three-phase solid-wall helical centrifuge according to one of the preceding claims, characterized in that the cross section of the inner and/or outer passage (19, 37) is variable.
9. Three-phase solid-wall helical centrifuge according to one of the preceding claims, characterized in that the passage (19) is followed in the outflow direction by a skimming disc (23) or by a throttle device, of which the distance from the passage (19) is variable.
10. Method for operating a three-phase solid-wall helical centrifuge according to one of Claims 1 to 9, in which a first, lighter liquid phase (L1) is discharged via a first, inner weir (15) and a second, heavier liquid phase is discharged via a second, outer weir (17), characterized in that, to vary the quantity of the heavier liquid phase (L2) running out, the distance of a throttle device (35) from a passage (37) of the second weir (17) is varied, the centrifuge being assigned a control computer which is used for regulating the outflow quantity of the heavy liquid phase by computer control as a result of the setting of the throttle device.
11. Method according to Claim 10, characterized in that the outlet quantity of the heavy liquid phase is regulated automatically.
12. Method according to Claim 11, characterized in that the outlet quantity of the heavy liquid phase is regulated as a function of the decanter inflow quantity and/or of the torque of the helix and/or as a function of the differential rotational speed between the helix and the drum and/or as a function of the motor current.

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