EP1337343B1 - Screw for a screw-type solid bowl centrifuge and method for producing oil using such a screw-type solid bowl centrifuge - Google Patents

Abstract

The invention relates to a screw for a screw-type solid bowl centrifuge that is characterized in that additional leaf segments (29) are disposed in some sections of the conveyor path (7) between adjacent spirals (x, x+1, ). The screw leaf (5), in the area of the screw leaf segments (29), is preferably provided with recesses (27) that are adapted to allow the material to be extracted (S) to pass between adjacent spirals (x, x+1, ). The screw according to the invention is especially suitable for use in a method for producing oil from fruit and seeds and for better dehydrating and/or deoiling mashes of organic materials (for example mashed seeds, fruit pulp, animal tissues such as fish, egg, fatty tissue cells).

Description

The invention relates to a screw for a solid bowl screw centrifuge according to the preamble of claim 1 and a method for oil extraction with a solid bowl centrifuge.

A method that has proven particularly useful in olive oil production is from EP 0 557 758. In this method, a two-phase separation performed, in which the oil directly from a solid / water mixture is separated.

The efficiency of this known method is already very good in itself.

Nevertheless, it is desirable to reduce the residual oil content in the pomace again, to increase the profitability of oil production.

The solution of this problem both constructively and procedurally Regard, the object of the invention.

The invention solves this problem on the one hand by a particularly advantageous Worm whose features are specified in claim 1. It also dissolves it a particularly advantageous method for oil extraction, the features in the claim 35 are indicated.

According to claim 1, a screw is provided for a solid bowl centrifuge, the sections in the conveyor track between adjacent Schnekkengängen has additional space segments. Furthermore, the screw blade is preferable provided with recesses which are formed such that a Flow through the material to be centrifuged between adjacent flights possible is.

With regard to the method of oil extraction has also been found to be particularly advantageous Turned out when the oil is again in a liquid phase as a liquid phase Two-phase separation step from a second mixed phase of water and solids is separated, with the seeds or crushed fruits such as olives or Avocados first into a solid bowl centrifuge through a separation zone be guided with one or more flights, in which the Schneckenblatt preferably formed free of recesses, wherein in the conveying path area preferably no blade segments in the conveyor track between the screw flights are formed. Then, in the separation zone, another screw area go through, are formed in the recesses in the screw blade and Leaf segments are in the conveyor track. Then the solids and the Water past a baffle plate from the separation zone into the conical section promoted the snail.

• wobei die zerkleinerten Früchte wie Oliven oder Avocados oder Saaten zunächst in einer Vollmantelschneckenzentrifuge durch eine Trennzone mit einer oder mehreren Schneckengängengeleitet wird, in dem das Schneckenblatt vorzugsweise aussparungsfrei ausgebildet ist, wobei im Förderbahnbereich zwischen den Schneckengängen vorzugsweise keine Blattsegmente in der Förderbahn ausgebildet sind,
• woraufhin in der Trennzone ein Schneckenbereich durchlaufen wird, in dem die Aussparungen im Schneckenblatt und die Blattsegmente in der Förderbahn ausgebildet sind,
• woraufhin die drei Phasen aus der Zentrifuge geleitet/gefördert werden.

With the screw according to the invention, the three-phase oil recovery can be improved, which is occasionally still used. The oil is separated as a liquid phase in a three-phase separation section of a second phase - essentially of water - and a third - essentially solids - separated,

• wherein the minced fruits such as olives or avocados or seeds are first passed in a solid bowl screw centrifuge through a separation zone with one or more flights in which the screw blade is preferably free of recesses, preferably in the conveying path between the screw flights no blade segments are formed in the conveyor track,
• whereupon in the separation zone a screw section is passed, in which the recesses in the screw blade and the blade segments are formed in the conveyor track,
• whereupon the three phases are passed / conveyed from the centrifuge.

By the screw according to the invention, the economy of oil production can be considerably increase. In this respect, in particular to the in the figure description referenced experiments, whose results in the figures 4 and 5 are shown. A particular advantage of the invention is to be seen in that the screw also easily retrofit existing centrifuges leaves. The screw according to the invention is particularly suitable for use in a process for oil extraction from fruits and seeds and for better drainage and / or de-oiling pulp from organic materials (e.g. Pulp mash, animal tissues such as fish, egg, gout cells).

It has been found to be particularly advantageous in the context of the invention, a Combination of recesses and blade segments provide, wherein the blade segments and the recesses are preferably formed in the axial direction are that the recesses each in the axial direction (and / or angled or zig-zag to the central axis y) form extending channels in which the Leaf segments are standing.

It is also particularly advantageous if the blade segments and the recesses are formed only in the cylindrical portion of the screw body and when in the conical section of the screw, especially in the two-phase separation a baffle plate is provided.

Although from the prior art already Vollmantel-screw centrifuges known in which recesses are provided in the screw blade, such. out DE 41 32 593 A1. From US-A-5 222 935 it is known to save out gauze leaf segments.

According to the invention, however, the provision of such recesses is not sufficient for a notable increase in efficiency. A particularly advantageous increase in efficiency Rather, can be achieved only by the fact that in addition to the recesses in particular in the middle of the front track between adjacent flights the additional leaf segments are placed.

Although it is already known to form leaf-segment-like screw threads, for example from WO 97/23295. However, these leaf segments extend into the conical section, which is unfavorable according to the invention is. Furthermore, they are on the circumference of the screw body in its entire area distributed, which has also proved to be of little benefit. In addition, will be not about additional leaf segments in the conveyor track between the flights placed, but the leaf segments themselves form the screw flights out. Even with this screw can be no satisfactory economy reach the olive oil production.

It is particularly advantageous if the additional blade segments in the conveyor track are formed so that they are in the range of solids or the solids but preferably an outer region of e.g. 25 mm is not reached by the leaf segments, since in this area already relative completely de-oiled and permanently discharged solids are present.

Measurement results show that the screw according to the invention about 1 to 1.5% less Oil in the discharged solids sludge leaves. In a campaign of olive oil production This is quite a financial advantage of about DM 300,000, - to 500,000, - per machine.

It is particularly advantageous if the kneading screw in the area of the moist Orujos acts, because in particular here a special Entölung by the additional Leaf segments is reached.

With the invention, a solids slurry, preferably via a rectangular tube, in the drum is fed. The rectangular tube must be so long that the incoming, protected to be centrifuged by the oil layer is brought to this subsequently not remix.

In the filled machine, the separation zone is quite close to the screw body a (10, 20 ..., to 40 to 50 mm distance). The fresh oil is as clean Phase only 20 to 30 mm outside the slug body recognize. Here There is a clean dividing line.

The introduced solid as part of the supplied suspension is thus the machine Fill so far that this up to the oil separation zone (about 10, 20 ... to a maximum of 40 to 50 mm outside the screw body) is filled with solid suspensions. As a rule, only so little water is in the Orujomasse that no or only a very small layer of free water between the oil and the solid suspension is trained. The solid is drier on the outside than inside In other words, the dry matter content on the drum side is much higher than the dry matter content towards the interior.

In the area of the recesses and leaf segments experiences the solid suspension especially in the kneading area of the leaf segments just like the oil and the between them lying emulsion from the screw body to the radial end three axial Speeds.

So there is a normal speed in the area of the wall remnants. In the area of the recesses, however, the axial velocity is substantially zero. In contrast, the speed is in the range of the actual Blade segments in the conveyor up to five times the normal speed be. This causes the viscoelastic sludge in the area of standing Solid layer deformed, in particular compressed and relaxed.

In the area of the leading leaf segments, the solid additionally becomes axially pressed together. He is then relaxed in the area of the recesses. It results thus an effect of pressure increases and relaxation. Essentially in the relaxation area the oil release takes place, which is thus more effective than without the additional relaxation zones.

Preferably, the worm body has a cylindrical in its rear region Section and in its adjoining front area one substantially conically uniform or uneven - e.g. stepped - tapered section on, with the recesses and leaf segments exclusively are formed in the region of the cylindrical portion.

Preferably, the screw body in the cylindrical portion initially at least one helix, which is free of recesses and free of leaf segments is formed, which is followed by further worm threads, which with the Recesses and leaf segments are provided.

It is also conceivable that preferably in the first flight optional Oil drain channels are formed.

Preferably, the recesses have a remaining portion of the screw blade on the circumference of the screw body.

Preferably, the leaf segments - based on one or more flights - Evenly or unevenly distributed on the circumference of the screw body.

Preferably, the area of the recesses is about 25-60%, in particular 40 - 50% of the worm gear area.

Preferably, the recesses in the screw blades are designed such that they project radially beyond at least the area of the solid zone (for example 70-95%, preferably 70-100% of the screw blade height).

In particular, the height of the leaf segments is about 0 - 30% lower than that Screw blade height.

Preferably, the blade segments are designed as rectangular plates conceivable are also trapezoidal, rounded and / or from the snail body outwardly tapering or widening shaped elements.

Particularly advantageous embodiments of the invention are the remaining dependent claims refer to.

Fig. 1

eine perspektivische Darstellung einer erfindungsgemäßen Schnecke für eine Vollmantel-Schneckenzentrifuge;

Fig. 2a

eine Draufsicht auf einen Abschnitt einer Schnecke;

Fig. 2b

einen Schnitt längs der Linie A-A aus Fig. 2a;

Fig. 3

eine Vollmantelschneckenzentrifuge nach der Erfindung;

Fig. 4 und 5

Diagramme, welche die Restölgehalte im Trester bei der Olivenölgewinnung mit Vollmantel-Schneckenzentrifugen im Zweiphasen-Trennver-fahren unter Einsatz von Schnecken nach der Erfindung und von Schnecken nach dem Stand der Technik vergleichen; und

Fig. 6a,b

die Geschwindigkeitsprofile in einem Schneckengang im Bereich der Aussparungen und Blattsegmente.

Embodiments will be described in more detail with reference to the drawing. It shows:

Fig. 1

a perspective view of a screw according to the invention for a solid bowl screw centrifuge;

Fig. 2a

a plan view of a portion of a screw;

Fig. 2b

a section along the line AA of Fig. 2a;

Fig. 3

a solid bowl screw centrifuge according to the invention;

4 and 5

Charts comparing the residual oil levels in the pomace in the olive oil recovery with solid bowl centrifuges in the two-phase separation process using screws according to the invention and of screws according to the prior art; and

Fig. 6a, b

the velocity profiles in a helix in the area of the recesses and leaf segments.

The dimensions of the description relate by way of example to preferred embodiments.

Fig. 1 shows a screw 1 for a solid bowl screw centrifuge, wherein the Screw a worm body 3 and here a worm body 3 several times surrounding worm blade 5, which has a plurality of flights (x, x + 1, x + 2, etc.).

Between the worm threads x, x + 1, ... is a conveyor track 7 for Fördem / transport formed to be processed centrifuged.

The screw body 3 has in its rear in Fig. 1 area a cylindrical Section 9 and in his in Fig. 1 adjoining the front area a conically tapering section 11.

In the transition region between the cylindrical portion 9 and the conical Section 11 here is a (congestion) disc 13 placed on the screw body 3.

This has proven particularly in the two-phase separation. In a three-phase separation it is not required in the phases of oil, water and solids.

The function of this solid bowl centrifuge, the remaining essential Components of FIG. 3 are as follows.

The centrifuged material S is through the centrally disposed, adjustable inlet pipe 14th in an inlet chamber 15 and from there through openings 17 in the drum space 19 with the screw 1 and the screw 1 surrounding drum 21 passed. Preferably, these Einlaufkammem 15 and openings 17 (or special Distributor) in the embodiment of Fig. 1 at the rear end of the cylindrical Section 3 arranged.

In the drum chamber 19, the centrifuged material S is accelerated to the operating speed. By the action of gravity, the solid particles settle in the shortest possible time Time off at the drum wall.

The screw 1 rotates at a speed slightly lower or higher than the drum 21 and promotes the ejected solid F to the conical section 11 out of the drum 21 for solids 23.

On the other hand, the liquid L flows toward the larger drum diameter at the rear End of the drum 21 and is derived there (overflow 25).

The worm 1 of Figure 1 points from its second flight (X + 1) to its fifth flight (X + 4) recesses 27 in the screw on.

These recesses 27 are formed in the embodiment of FIG. 1 such that in the axial direction from the second to the fifth screw blade forming extending axial channels K. A single helix with Recesses 27 and blade segments 29 is in a simplified embodiment also conceivable.

In between the worm threads (X, ...) of the screw blade 5 trained Conveyor track 7, however, additional leaf segments 29 are arranged here as Metal strips are formed here from the outer periphery of the Schnekkenkörpers 3 outwardly widening trapezoidal shape.

Advantageously and in a simple and cost-effective manner, these leaf segments 29 formed by the Blattabschnitte- or segments, which separated during the separation of material for forming the recesses 27 be placed in the conveyor track 7 and welded there.

The separation of the leaf sections or segments can either take place in such a way that that the screw blade 5 is separated to the circumference of the screw body 3 becomes. Alternatively, however, a remaining portion 30 of the screw blade 5 on The circumference of the screw body 3 stop. Is the removal essentially radially to the drum and screw axis y, resulting trapezoidal Leaf segments 29.

With such a combination of recesses 27 and "intermediate" blade segments 29 in the conveyor track 7, the efficiency of various of increase centrifugal separation processes surprisingly significantly.

• das Öl als Flüssigkeitsphase direkt in einem Zweiphasen-Trennschritt von einer zweiten Mischphase aus Wasser und Feststoffen abgetrennt wird,
• wobei die zerkleinerten Früchte wie Oliven oder Avocados zunächst in einer Vollmantelschneckenzentrifuge durch eine Trennzone mit einem oder mehreren Schneckengängen X, ... geleitet wird, in dem das Schneckenblatt 5 keine Aussparungen 27 aufweist und in dem keine Blattsegmente 29 in der Förderbahn ausgebildet sind
• woraufhin in der Trennzone ein zweiter Schneckenbereich durchlaufen wird, in dem die Aussparungen 27 im Schneckenblatt 5 und die Blattsegmenten 29 in der Förderbahn 7 ausgebildet sind,
• woraufhin die Feststoffe und das Wasser an einer Stauscheibe 13 vorbei aus der Trennzone in den konischen Abschnitt der Schnecke 1 gefördert werden.

In particular, the screw formation has proven with recesses 27 and 29 in the field of olive oil production. In the extraction of olive oil, a two-phase separation, in which the oil is separated directly from a mixture of solids and water, has proven particularly useful. Such a method is described in EP 557 758. The efficiency of this already excellent process can be significantly increased by the screw 1 of the invention again. It has proven to be particularly advantageous if

• the oil as liquid phase is separated from a second mixed phase of water and solids directly in a two-phase separation step,
• wherein the minced fruit such as olives or avocados is first passed in a solid bowl centrifuge through a separation zone with one or more flights X, ..., in which the screw blade 5 has no recesses 27 and in which no leaf segments 29 are formed in the conveyor track
• whereupon in the separation zone, a second screw region is traversed, in which the recesses 27 in the screw blade 5 and the blade segments 29 are formed in the conveyor track 7,
• whereupon the solids and the water are conveyed past a baffle plate 13 from the separation zone into the conical section of the screw 1.

The advantages of this method are clear from FIGS. 4 and 5.

Fig. 4 shows comparisons of improving the efficiency of oil recovery in dependence from the throughput. Fig. 5 further illustrates that in olive oil production with a screw 1 according to the invention the residual oil content in the pomace could be reduced by up to 2 or even 2.5%. The economy The oil production is so compared to the already excellent result of Two-phase separation a) oil and b) water / solid again considerably increased. The conversion or replacement of the conventional screw against the invention It will pay for itself within a short time.

Fig. 6a, b show the velocity profiles in a helix in the area the recesses and leaf segments. In Fig. 6a it is clear that "in the shade" of the leaf segment, the velocity of the particles increases from the inside to the outside. At the upper edge of the leaf segment, the maximum value is reached, which According to Fig. 6b at the upper leaf segment edge again substantially constant is.

Different dimensions and orientations and arrangements of the recesses 27 and the blade segments 29 have proven particularly useful in practice. By varying these parameters, the mixing effects between the Worm threads vary, which directly influences the efficiency of the separation process Has. These parameters will be described below with reference to FIGS. 1 and 2 described in more detail.

First, the preferred location of the recesses and segment described in more detail.

Advantageously, the screw 1 - in Fig. 1 from the rear inlet zone forward looking at the conical section - at first some turns x-1, x, x + 1 on, in the area of the screw blade 5 each continuous or free of recesses is trained. Preferably, at least one or two flights are x continuously formed. In this area are also no additional Leaf segments 29 provided in the conveyor track 7.

This zone is followed by some worm threads x + 2, ... x + 5, which with the recesses 27 are provided and in the interstices or in the Conveyor tracks 7 each formed the blade segments 29 or erected (welded) are.

This zone extends maximally to the beginning of the conical section 11th the screw 1. In the transition region from the cylindrical to the conical region Furthermore, the baffle plate 13 is arranged. In the conical area, the snail should be formed free of recesses, also in the conveyor track 7 and no additional Leaf segments 29 are arranged.

Per screw flight are preferably 2 to 6, especially 3 to 5, especially preferably 4 recesses 27 formed.

Accordingly, it is also recommended, preferably per worm gear in the conveyor track 2 to 6, especially 3 to 5, most preferably 4 leaf segments 29 to provide.

Preferably, the blade segments 29 are uniformly on the circumference of the screw body 3 distributed.

The worm threads x are relative to the central axis or to the axis of symmetry y Screw 1 each arranged at an angle or close to the central axis one Angle α on. The amount of the angle α (measured at the bottom of the Schnekkenblattes 5), is preferably between 60 and 85 °, in particular at 75 to 80 °.

Preferably, however, the blade segments close with the symmetry axis y a Angle δ one smaller than α. Preferably, δ is between 40 and 70 °, in particular 50 to 55 °. In the last flight in front of the baffle plate 13 recommends on the other hand, the blade segments 29 are substantially parallel to the To align the worm blade 5 (maximum difference angle between α and δ preferably about 10 - 11 °).

Preferably, the surface of the recesses is about 50 ° of the checkered surface.

In practice, it has also proved to be advantageous, the angle size δ specify that the width of the distance d (in the axial extension of the Seen edges) between the leaf segment edge and the recess edge 27th at 0 to 5mm, especially at 2 to 3 mm (at the upper edge of the segment). at a trapezoidal shape of the leaf segments varies the size of the stretches "d" of Slug body 3 to the outside, according to Fig. 1, "d" to the outside, for example greater.

Furthermore, it is advantageous if the angular size (δ) is determined by the fact that the Width of the distance (a) - viewed in orthogonal extension of the edges - between the blade longitudinal edge and the recess edge 27 at 0 to 28%, in particular at 15 to 25% of the distance of a pair of flights - preferably considered at the base of the snail (inside), depending on the shape - lies.

According to a variant of the invention, it is recommended that the blade segment 29 in such a way to arrange the conveyor track 7 that its central axis M (in the plan view of FIG. 2a) exactly in the middle of the conveyor track 7 and preferably also in the middle of the Connecting line of the connecting line of the bisectors of the recesses 27 is located (crossing point of the opposite Aussparungsränder).

Alternatively, it is also possible to slightly oppose the midpoint of the leaf segments to shift this ideal situation.

Especially important for the efficiency of the invention is the height h of the Blade segments (measured from the outer circumference of the screw body 3).

Here it has proved to be particularly advantageous if the height h of Blade segments 29 is selected such that it extends into the region of the solid zone extend. Accordingly, the screw blades 5 should have recesses 27, which project radially beyond at least the region of the solid zone.

This is explained as follows. In the centrifugal separation, the solids are stored relatively far out in the drum. The blade segments (paddle) are not enough at least into this solid zone, their efficiency remains low. Just by the mixing action of the recesses 27 and blade segments 29 in this area the efficiency of centrifugal separation in oil production is significantly increased.

In practice, the height h is selected about 30 mm lower than the Schneckenblatt height k. The worm blade closes with the peripheral wall of the worm body 3 according to FIG. 2b further includes an angle γ. This is preferably smaller as the angle β, which the blade segment 29 encloses with the screw body 3.

reference numeral

slug

1

screw body

3

screw blade

5

screw flights

x, x + 1, x + 2, and so on.

conveyor track

7

cylindrical section

9

rejuvenating section

11

disc

13

centrifuged

S

inlet pipe

14

inlet chamber

15

openings

17

drum space

19

drum

21

solid fuel

F

solids

23

overflow

25

recesses

27

channels

K

leaf segments

29

remaining sections

30

angle

α, β, δ, γ

segment height

H

Screw blade height

k

Drum and screw axis

y

distances

d

Claims (36)

1. Screw for a solid-bowl screw-type centrifuge, having the following:

   a screw body,

   at least one screw blade which surrounds the screw body several times and forms several screw spirals (x, x+1),

   a delivery path for conveying material to be centrifuged being formed between the screw spirals,

   characterized in that

   additional blade segments (29) are arranged in the delivery path (7) in sections between adjacent screw spirals (x, x+1, ...),

   in the area of the screw blade segments (29), the screw blade (5) is provided with recesses (27) which are formed such that the material (S) to be centrifuged can flow through between adjacent screw spirals (x, x+1, ...).
2. Screw according to Claim 1, characterized in that, in its rearward area, the screw body (3) has a cylindrical section (9) and, in its adjoining forward area, has a section (11) which tapers essentially conically uniformly or nonuniformly, the recesses (27) and the blade segments (29) being formed only in the area of the cylindrical section (9).
3. Screw according to Claim 1 or 2, characterized in that, in the cylindrical section (9), the screw body first has at least one screw spiral which is formed without recesses and blade segments, and which is followed by additional screw spirals (X, X+1 ... ) which are provided with the recesses (27) and blade segments (29).
4. Screw according to Claim 3, characterized in that optional oil drainage ducts are formed preferably in the first screw spiral (X).
5. Screw according to Claim 3 or 4, characterized in that the section with the recesses (27) and the blade segments (29) extends to the conically tapering section (11) but not into it.
6. Screw according to one of the preceding claims, characterized in that, at the beginning of the conically tapering section (11), a retarding disc (13) is placed on the screw body (3).
7. Screw according to one of the preceding claims, characterized in that the inlet of the screw is formed at the rearward end of the cylindrical section (9).
8. Screw according to one of the preceding claims, characterized in that the recesses (27) are formed on the screw (1) in such a way as to form, in the axial direction, at least one axial duct (K) which extends over several screw spirals (x+1, ...) and/or a duct which is angular with respect to the centre axis of the screw (1) and/or a zigzag-type duct.
9. Screw according to one of the preceding claims, characterized in that the blade segments (29) are formed in that, when material is cut off for forming the recesses (27), the resulting blade sections are placed as blade segments (29) in the delivery path (7) and are fastened there.
10. Screw according to one of the preceding claims, characterized in that the recesses have a residual section (30) of the screw blade (5) on the circumference of the screw body (3).
11. Screw according to one of the preceding claims, characterized in that two to six recesses (27) are formed for each screw spiral.
12. Screw according to one of the preceding claims, characterized in that three to five recesses (27) are formed for each screw spiral.
13. Screw according to one of the preceding claims, characterized in that two to six blade segments (29) are provided for each screw spiral in the delivery path.
14. Screw according to one of the preceding claims, characterized in that three to five blade segments (29) are provided for each screw spiral in the delivery path (7).
15. Screw according to one of the preceding claims, characterized in that, relative to one or more screw spirals, the blade segments (29) are uniformly distributed on the circumference of the screw body (3).
16. Screw according to one of the preceding claims, characterized in that, relative to one or more screw spirals, the blade segments (29) are non-uniformly distributed on the circumference of the screw body (3).
17. Screw according to one of the preceding claims, characterized in that, relative to the centre axis (Y) of the screw (1), the screw spirals (X) are arranged at an angle to form an angle (α) with this centre axis, the magnitude of the angle (α) preferably being between 60 and 85, particularly at 75° to 80°, the blade segments enclosing an angle (δ), which is smaller than (α), with the axis (Y) .
18. Screw according to one of the preceding claims, characterized in that that angle (δ) is between 40 and 70°.
19. Screw according to one of the preceding claims, characterized in that the angle (δ) is at 45 to 60°.
20. Screw according to one of the preceding claims,. characterized in that, in the last screw spiral in front of the retarding disc (13), the blade segments (29) are aligned essentially parallel to the screw blade (5) and have a maximal differential angle with respect to the angle (α) of 10 to 11°.
21. Screw according to one of the preceding claims, characterized in that the area of the recesses (27) amounts to approximately 25 to 60% of the screw spiral area.
22. Screw according to one of the preceding claims, characterized in that the area of the recesses (27) amounts to approximately 40 to 50% of the screw spiral area.
23. Screw according to one of the preceding claims, characterized in that the angle size (δ) is defined such that the width of the distance (d)- viewed in an axial extension of the edges - between the longitudinal blade edge and the edge of the recess (27) is >=0.
24. Screw according to one of the preceding claims, characterized in that the distance d - viewed from the screw body (3)- varies with increasing height of the blade segment (29) and particularly becomes smaller.
25. Screw according to one of the preceding claims, characterized in that the angle size (δ) is defined such that the width of the distance (a) - viewed in the orthogonal extension of the edges - between the longitudinal edge of the blade and the edge (27) of the recess amounts to 0 to 28%, particularly to 15 to 25%, of the distance of a pair of screw spirals, preferably viewed at the low end of the screw, as a function of the shape.
26. Screw according to one of the preceding claims, characterized in that the blade segment (29) is arranged in the delivery path (7) such that its centre axis (M) is situated precisely in the centre of the delivery path (7) as well as in the centre of the connection line of the apothem of the recesses (27).
27. Screw according to one of the preceding claims, characterized in that the centre point of the blade segments (29) is slightly shifted with respect to the centre of the delivery path and/or the centre of the connection line of the apothem of the recess (27).
28. Screw according to one of the preceding claims, characterized in that the height (h) of the blade segments (29), viewed from the circumference of the screw body (3), is selected such that the blade segments (29) extend into the area of the solids zone during the centrifugal separation.
29. Screw according to one of the preceding claims, characterized in that the recesses (27) in the screw blades (5) are formed such that they radially project at least over the area of the solids zone.
30. Screw according to one of the preceding claims, characterized in that the height (h) of the blade segments (29) is approximately 0-30% less than the height (k) of the screw blade.
31. Screw according to one of the preceding claims, characterized in that the radial extent of the recesses amounts to 70-95%, preferably 70-100%, of the height (k) of the screw blade.
32. Screw according to one of the preceding claims, characterized in that the blade segments (29) are formed as rectangular metal plates.
33. Screw according to one of the preceding claims, characterized in that the blade segments (29) are formed as rectangular, trapezoidal, rounded elements and/or elements shaped to taper or widen from the screw body toward the outside.
34. Screw according to one of the preceding claims, characterized in that the screw blade (5) encloses an angle (y) with the circumferential wall of the screw body (3), which angle (γ) is smaller than the angle (β) which the blade segment (29) encloses with the screw body (3).
35. Method for extracting oil from fruit or seeds, characterized in that the oil is directly separated as a liquid phase in a two-phase separating step from a second mixing phase of water and solids,

    the reduced fruit, such as olives or avocados or seeds, being first guided in a solid-bowl screw-type centrifuge through a separating zone with one or more screw spirals (X ...) in which the screw blade (5) is preferably formed without recesses, preferably no blade segments (29) being formed in the delivery path in the delivery path area between the screw spirals,

    then passing through a screw area in the separating zone, in which screw area the recesses (27) are formed in the screw blade (5) and the blade segments (29) are formed in the delivery path (7),

    then the solids and the water being conveyed past a retarding disc (13) out of the separating zone into the conical section (9) of the screw (1) and the oil being conveyed in the opposite direction out of the screw (1).
36. Method of extracting oil from fruit or seeds, characterized in that the oil is separated as a liquid phase in a three-phase separating step from a second phase - essentially consisting of water - and a third phase - essentially consisting of solids,

    the reduced fruit, such as olives or avocados or seeds, being first guided in a solid-bowl screw-type centrifuge through a separating zone with one or more screw spirals (X ...) in which the screw blade (5) is preferably formed without recesses, preferably no blade segments (29) being formed in the delivery path in the delivery path area between the screw spirals,

    then passing through a screw area in the separating zone, in which screw area the recesses (27) are formed in the screw blade (5) and the blade segments (29) are formed in the delivery path (7),

    then the three phases being guided/conveyed essentially separately out of the centrifuge.

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