EP1383607B1 - Solid bowl spiral centrifuge and a method for obtaining oil using a solid bowl spiral centrifuge - Google Patents

Abstract

The invention relates to a solid bowl spiral centrifuge comprising the following: a drum (3) which delimits the outer periphery of a centrifugal chamber (17) and a spiral (5) that is arranged in the drum (3), whereby segregation elements (19) project into at least some sections of the centrifugal chamber (17), said elements extending inwards from the internal periphery of the drum (3) and the spiral (5) also extending over the region of the segregation elements (19). The centrifuge is used in a method for obtaining oil from fruits or seeds. According to said method, the oil is separated as a liquid phase directly from a second mixed phase of water and solids in a two-phase cut, whereby said phases traverse the spiral region in the solid bowl centrifuge, which contains cavities (27) in the spiral blade (9) and the segregation elements (19) that extend inwards from the drum (3).

Description

The invention relates to a solid bowl screw centrifuge according to the preamble of claim 1. Such a centrifuge is from the DE-A-2627265.

A method that has proven particularly useful in olive oil production is from EP 0 557 758. In this method, a two-phase separation carried out, in which the oil directly from a solid / water mixture is separated. The efficiency of this known method is already very strong Good. Nevertheless, it is desirable to reduce the residual oil content in the pomace again, to further 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 Solid bowl screw centrifuge whose features are specified in claim 1.

According to the invention, segregation elements protrude into the centrifugal space at least in sections into, which from the inner circumference of the drum from inside extend and the worm blade also covers the area of the segregation elements.

The thus equipped solid bowl screw centrifuge is particularly suitable - but not only - for use in a process for oil extraction from fruits and seeds and for better drainage and / or de-oiling of organic porridge Materials (e.g., porridge, pulp mash, animal tissues such as Fish, egg, adipose tissue cells).

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 will thus fill the machine so far that it reaches the oil separation zone (about 10, 20 ... to a maximum of 40 to 50 mm outside the screw body) filled with solid suspensions. In general, only so little water is in the Orujomasse, that no or only a very small layer of free water formed between the oil and the solid suspension. Here is the solid dry outside than inside or in other words, is the dry matter content Drum side much higher than the dry matter content towards the inside out.

The segregation elements are rigidly connected to the drum and have the same Rotation speed as the drum up. In operation, the rotates Snail i.allg. slightly faster than the drum (e.g., 10 - 20rpm). This results a solid transport towards the cone, where the solid with the water as Suspension is discharged. Since the e.g. rod or needle-like segregation elements have the lower speed of the drum, mix They the pulp, which improves the oil release.

Another particular advantage of the invention is the fact that the segregation elements The invention also easily with existing solid bowl centrifuges can be retrofitted.

At its outer periphery is the worm blade with recesses provided (either one or more windows per screw flight or one extending over one or more complete flights, recess, i.e. the width of the screw is smaller in the area of the recesses). Especially through the combination of recesses and segregation elements becomes the efficiency of oil production increased again. According to the invention, these are Recesses designed such that in the axial direction channels in the Train snail leaf. It is also conceivable, the snail leaf at his Outer circumference a continuous recess over several axial having staggered segregation elements.

The idea of stirring elements is known per se in solid bowl centrifuges (see the non-generic DE PS 33 01 099 C2). There was on one Snail completely omitted (picture 1 of the patent) or she was only in the area next to provided the stirring elements (Figure 2 of the patent). In addition, there are the Stirring elements basically for conveying effect in the conical region. In contrast For this purpose, the invention provides a solid bowl screw centrifuge, both the advantages of a centrifuge with screw in terms of the solids discharge by the screw as well as the stirring elements combined, which through the interplay of the recesses in the screw and the segregation elements becomes possible.

Preferably, the segregation elements are rod-shaped and have a substantially cylindrical or angular cross-section on. Rejuvenate after a variant the segregation elements from the inside of the drum inside out. The taper of the segregation causes the kneading effect increases towards the outside. After further variants are the segregation elements rectangular, trapezoidal, rounded and / or extending from the drum inner wall formed at least partially tapering and / or widening towards the inside.

Preferably, the segregation elements protrude so far into the centrifugal space in that they in the processing of a centrifugal oil for recovery enforce the essential section of the solid / water phase. After a variant Remains between the segregation elements and the screw body Distance of 25-80%, preferably 30-60%, preferably 50-60% of the width of the sluice room (pond depth T).

Particularly preferably, the recesses are further formed such that in the area of the recesses on the worm body in each case a remaining portion of the Screw blade remains on the circumference of the screw body, preferably has a radial extent, which at least the radial extent of the oil and / or emulsion phase in the oil recovery corresponds.

Particularly preferably, the screw and the drum have a cylindrical section and in adjoining tapered section, with the recesses and segregation elements exclusively in the area of cylindrical Sections are formed.

According to a further variant, the recesses are formed on the screw in such a way, that in the axial direction at least one over several flights away extending axial channel and / or to the center axis of the Snail angled canal and / or a zig-zag-shaped canal trains. Especially In particular, it is advantageous if the recesses are designed in such a way that that in the circumferential direction in the radial direction at a mehrgängigen Snail form channels in the snail blade, through which the pins at Turning the screw can pass.

Preferably, at least one, preferably two to, per screw flight six recesses formed in the screw blade and per revolution of the conveyor track protrudes at least one, preferably two to six segregation elements in this into it. Also, a recess may due to the relative rotation between Drum and screw already suffice to allow the passage of several pins too allow. Preferably, symmetrical arrangements are chosen, e.g. only one Pin per flight, on four consecutive flights each offset by 90 ° to each other or, for example, four pins per screw, each at Offset 90 ° to each other on the circumference.

In practice, it has proven useful when three to seven flights of the centrifuge provided with the segregation elements and recesses.

The invention also provides a process for oil extraction from fruits or Seeds in which the oil as a liquid phase directly in a two-phase separation cut separated from a second mixed phase of water and solids, wherein in the solid bowl screw centrifuge pass through a screw area is, in the recesses in the snail blade and from drum inside extending segregation elements are formed in the conveyor track.

The invention is also suitable for clarifying structurally poor, i. fine Compressible sludge with small solid particles (for clarification of heavy liquids to be clarified, e.g. Fruit mash or sewage, structureless pulp, Seed porridge or seedless olive porridge, oil production from fruits or seeds).

Particularly advantageous embodiments of the invention are the rest Subclaims refer.

Fig. 1

einen Schnitt durch einen Abschnitt einer erfindungsgemäßen Vollmantel-Schneckenzentrifuge; und

Fig.2a-d

verschiedene Prinzipskizzen, welche die Verhältnisse in einer erfindungsgemäßen Vollmantel-Schneckenzentrifuge bei der Ölgewinnung im Zwei-Phasenverfahren veranschaulichen sollen; und

Fig. 3

eine Tabelle, welche die Effizienz erfindungsgemäßen Zentrifuge mit einem Vergleichsdekanter verdeutlicht.

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

Fig. 1

a section through a portion of a solid bowl screw centrifuge according to the invention; and

2a-d

various schematic diagrams which are intended to illustrate the conditions in a solid shell screw centrifuge according to the invention in the oil recovery in the two-phase process; and

Fig. 3

a table illustrating the efficiency of the centrifuge according to the invention with a Vergleichsdekanter.

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

Fig. 1 shows a solid bowl screw centrifuge 1 with a drum 3, in the a screw 5 is arranged. The drum 3 and the screw 5 each have a substantially cylindrical portion 3a, 5a and here conical tapered section 3b, 5b.

The worm 5 has a worm body 7 and here a worm body 7 multiply surrounding screw blade 9, which has multiple flights (9a, 9b, 9c, etc.). Between the flights 9a, 9b, 9c, ... is Furthermore, a conveyor track 11 for conveying / transporting a centrifuged material to be processed educated.

On the drum inner wall is an optional rail-like structure of grooves 12 or grooves provided to improve the solids transport.

Preferably in the transition region between the cylindrical portion and the conical section of the screw 5 may not shown here (congestion) disc be placed on the screw body 7. This particular has proven in the two-phase separation. In a three-phase separation in the Phases of oil, water and solids is not essential.

An axially extending centric inlet pipe 13 serves to supply the Spent material S via a here to the inlet pipe 13 vertical distributor 15 in the centrifugal space 17 between the screw 5 and the drum 3rd

The function of this solid bowl centrifuge is as follows:

The centrifuged material S is exemplified here by the centrally arranged inlet pipe 13 in the manifold 15 and from there into the centrifugal chamber 17 and passed during accelerates this process to the operating speed.

For example, if an olive porridge is fed into the centrifuge, sit down at the Drum wall coarser solid particles from. Further inward form a dispersion phase of water, oil and fine solids and further inside essentially an oil phase.

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 3b out of the drum 3 to (not shown here, known per se) Solids. In contrast, the liquid flows to the larger drum diameter at the rear end of the cylindrical portion 3a of the drum 3. For example with the help of a baffle plate and by appropriate adjustment of the processes However, it is also possible to operate the solid bowl screw centrifuge such that when processing a fruit pulp from olives or e.g. Avocado the oil to Liquid discharge and a mixed water / solid phase for solids discharge be led out of the drum 3. The oil phase i.allg. still impurities, e.g. by particulates which are e.g. in one of the solid bowl centrifuge downstream separator can be separated.

An essential goal of the constructive development of solid bowl centrifuges for oil extraction lies in the increase in efficiency or in an increase in the oil yield and - associated with this - in the reduction the residual oil content in the solid / water phase.

This increase in efficiency is achieved by moving away from the drum wall from segregation elements 19 inwards into the centrifugal space 17 extend. These segregation elements are in the present case as a bolt 21st with a bolt head 2 1 a, an adjoining threaded portion 21b and an adjoining smooth cylindrical portion 21 c formed. The bolts pass through holes 23 in the jacket 25 of the drum 3 from the outside, so that the bolt heads 21a come to rest on the outside of the drum wall, wherein the threaded portion 21b in a corresponding internal thread of the bores 23 is screwed. The rod-shaped portion 21 c is radially or obliquely inwards in the drum. He has here an extension or height h of about 2/3 of the Centrifugal space width (pond depth T). The radial extent should preferably be dimensioned so that he still in the processing of a centrifugal mean dispersion phase substantially interspersed, but not up to the oil phase extends into it.

The advantageous effect of the segregation elements 19 is optimized by recesses 27 in the snail leaf. These recesses 27 are in the embodiment 1 formed such that in the axial direction of the second form extending to the fifth screw blade extending axial channels K.

The separation of the leaf sections or segments can either take place in such a way that that the screw blade 9 is separated to the circumference of the screw body 7 becomes. Alternatively and particularly advantageously, however, a remaining portion 29 of the Schneckenblattes 9 remain on the circumference of the screw body 7, which should have a radial extent, which of the radial extent of the oil and Emulsion phase corresponds.

With such a combination of recesses 27 and segregation elements 19 in the conveyor track 7, the efficiency of various centrifugal Significantly increase separation processes.

In particular, the screw formation has recesses 27 and segregation elements 19 proven in the field of oil extraction. Especially proven already had a two-phase separation in olive oil production, in which the oil is separated directly from a solid / water mixture. Such a thing Process is described in EP 557 758. The efficiency of this in itself already excellent process can be through the screw 1 of the invention again increase significantly. It has proved to be particularly advantageous when the oil as a liquid phase directly in a two-phase separation step of a second Mixed phase of water and solids is separated, the crushed Fruits such as olives or avocados first in a Vollmantelschneckenzentrifuge through a separation zone with one or more flights 9a, ... passed is in which the screw blade 9 has no recesses 27 and in where no segregation elements 19 are formed in the conveyor track, whereupon in the separation zone, a second area is traversed, in which the recesses 27 in the screw blade 5 and the segregation elements 19 on the drum inner wall are formed, whereupon the solids and the water at a Baffle plate 30 outside passing out of the separation zone in the preferably conical tapered section of the snail are promoted.

Below is the preferred location of the recesses and segregation elements described in more detail.

Advantageously, the screw 1 - in Fig. 1 from the rear inlet zone after viewed from the front towards the conical section - at first some winding turns up, in the area of the worm blade 9 each continuous or free of recesses is trained. Preferably, at least one or two flights are formed throughout. There are no additional segregation elements in this area 19 provided in the conveyor track 11.

This zone is followed by a few flights 9a, ..., which with the Recesses 27 are provided and in the interstices or in their conveyor tracks 7 each at least one or more of the segregation elements 19 protrude.

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 30 is arranged. In the conical area, the snail should preferably be formed free of recesses.

Per screw flight, at least one, preferably 2 to 6, in particular 3 to 5, most preferably 4 recess (s) 27 formed. Corresponding It is recommended, per screw thread in the conveyor track and at least one, preferably 2 to 12 segregating element (s) 19 provided on the drum inner wall. Preferably, the segregation elements 19 are uniformly around the circumference of the worm body 3 distributed (imbalance avoidance). The diameter of the rod-shaped Demixing elements is e.g. in the range of 2 to 25 mm.

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

The advantageous effect of the invention can be after an interpretation attempt describe as follows.

In the cylindrical part of the drum 3 are through the drum wall through the Demixing 19 screwed into the drum 3, in the interior, ie extend the centrifugal space of the drum 3. The segregation elements 19 are thus rigidly connected to the drum 3 and thus have the same rotational speed like the drum 3. The screw 5 rotates at 10 to 20 rpm faster than the drum 3. This results in a transport of solids in the direction Cone, where the solid is discharged with the water as a suspension.

The recesses 27 in the screw 5 cause that in the region of the recesses (Recesses 27) no solids transport at the screw speed in the direction of the cone. So there is a relative speed the solids in the region of the recesses 27, a part of the slurry flows quasi backward. On the other hand, the segregation elements protrude into the region of the recesses 27 into it, whereby the backflow is accelerated because the segregation elements have the drum speed lower than that Screw speed is. This causes a mixing of the middle phase the solid rice, whereby the oil release improves and thus the segregation and thus the phase separation is facilitated (see Figure 2a).

The olive pulp to be separated consists (FIG. 2b) of an oil phase (light phase I, Flow direction of the arrows in Fig. 2c, upper figure), a heavy, quasi oil-free solid phase (III, dotted solid sediment in Fig. 2c, bottom figure) with broken pieces of meat and de facto oil-free pulp particles, which is why one can speak of a suspension, and a middle phase II (flow direction the arrows in Fig. 2c, middle figure), a dispersion of the liquids Water and oil (small amounts of residual oil) and pulp particles, if they are not destroyed, they may have trapped water and oil. Due to different proportions of water, oil and solid particles sets the dispersion phase II from a further inner thinner dispersion phase IIa and relative to this outermost, thicker dispersion phase IIb together (Figure 2b).

The segregation elements 19 are of such a length that they enter the dispersion phase II protrude. So they do not disturb the inside formed on the snail body Zone I from the separated oil (see Figure 2c). They do not bother the outside, quasi oil-free thick, deposited suspension on the inside of the drum wall, So the zone III, since they are the same speed as the drum. 3 exhibit.

In the dispersion phase II, the segregation elements 19 interfere in combination with the recesses 27, however, the "normal" transport speed of Pulp. This makes sense insofar as the solid bowl centrifuge only the can separate free oil as a continuous phase, and not that trapped in the cells, as it is in the specific heavier, the thick suspension (IIb) out Cores and pulp on the inner edge of the drum is present. This free oil is in the dispersion phase (IIa) located.

In addition, must, viewed radially, the oil in the direction of the screw body, so moving inwards, since it is specifically lighter than the water. The same thing applies to the free water, which is specifically lighter than the solid, and thus is also moved inwards. Seen in the radial direction so you have a Solid-liquid phase separation in addition to liquid-liquid phase separation (Water-oil).

It is known from filtration technology that the solid-liquid separation only then is successful if the heap has a sufficient porosity, so if channels exist in the heap through which the fluid can flow. It is also known that the oil with the decanter centrifuge only as a continuous phase can be obtained when the oil droplets in the mass, the porridge, greater than 30 microns are, otherwise they do not coalesce.

However, only the thick dispersion phase and partly the thin ones contain Dispersion phase quasi a structureless solid, which is a sufficient solid-liquid separation barely allowed. With the segregation elements 19 is now made the structure inhomogeneous, which facilitates the separation of the fluids becomes.

Furthermore, the segregation elements 19 preferably also protrude into the region of the thin Dispersion into it. This gives the possibility that even smaller oil droplets coincide with equal or larger, resulting in more oil can coalesce. So disturb the segregation elements 19 practically the laminar Flow in the light and in the heavy dispersion phase, causing the oil separation improved from the thin dispersion phase.

Fig. 3 illustrates that with the decanter according to the invention a better yield in the olive oil production in the two-phase technique is achievable, namely at the same or even higher throughputs.

reference numeral

Solid bowl centrifuge

1

drum

3

cylindrical section

3a

conically tapered section

3b

slug

5

cylindrical section

5a

conical section

5b

screw body

7

screw blade

9

screw flights

9a, 9b, 9c, ...

conveyor track

11

axial grooves

12

inlet pipe

13

distributor

15

centrifugal chamber

17

Entmischungselemente

19

bolt

21 1

bolt head

21a

threaded portion

21b

rod-like area

21 c

drilling

23

coat

25

recesses

27

remainder section

29

baffle plate

30

centrifuged

S

pond depth

T

height

H

channels

K

oil

I

dispersion phase

II, IIa, IIb

Solids suspension

III

Claims (21)

1. Solid-bowl screw centrifuge, which includes the following:

   a drum (3) which delimits the outer circumference of a centrifuging space (17), and

   a screw (5) which is arranged in the drum (3) and has a screw body (7) and a screw blade (9) which surrounds the screw body a number of times, forms a plurality of screw spirals (9a, 9b, ...) and delimits a conveying path (11) for a material that is to be processed by centrifuging,

   at least sections of elements (19) which extend inwards from the inner circumference of the drum (3) projecting into the centrifuging space (17), with the screw blade (9) covering the region of the elements (19),

   and the screw blade (9) being provided on its outer circumference with cutouts (27) through which the elements (9) move during rotation of the screw (5) and the drum (3),

   the elements (19) being segregation elements,

   characterized in that

   the cutouts (27) are designed in such a manner that at least one passage which extends over a plurality of screw spirals (9a, 9b, ...) is formed in the axial direction in the screw blade (9).
2. Solid-bowl screw centrifuge according to Claim 1, characterized in that the cutouts (27) are formed in such a manner on the screw (5) that at least one axial passage (K) which extends over a plurality of screw spirals (x + 1, ...) and/or at least one passage which is angled with respect to the centre axis of the screw (1) and extends over a plurality of screw spirals (9a, 9b, ...) and/or at least one zigzag-like passage is formed in the axial direction.
3. Solid-bowl screw centrifuge according to Claim 1 or 2, characterized in that the segregation elements (19) are in rod or bar form with a substantially cylindrical or polygonal cross section.
4. Solid-bowl screw centrifuge according to Claim 1, 2 or 3, characterized in that the segregation elements (19) narrow in the inward direction.
5. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the segregation elements (19) are designed in rectangular form, in the shape of a trapezium, in rounded form and/or so as to widen and/or narrow at least in sections.
6. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the segregation elements (19) pass from the outside through bores (23) in the bowl (25) of the drum (3).
7. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the segregation elements (19) are designed as bolts (21) having a bolt head (21a), preferably an adjoining threaded region (21b) and a rod-like bolt region (21c).
8. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the segregation elements (19) project sufficiently far into the centrifuging space (17) for them, during processing of a material that is to be centrifuged in order to obtain oil, to substantially pass through a solid phase and a dispersion phase comprising water and oil but not an inner oil phase.
9. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that there is a distance of 25 - 80% of the width of the centrifuging space (pool depth T) between the segregation elements (19) and the screw body (7).
10. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that there is a distance of 30 - 60% of the width of the centrifuging space between the segregation elements (19) and the screw body (7).
11. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that there is a distance of 50 - 60% of the width of the centrifuging space between the segregation elements (19) and the screw body (7).
12. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the screw blade (9), on its outer circumference, has a continuous cutout over one or more axially offset segregation elements.
13. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the cutouts (27) are formed in such a manner that in each case a residual portion (29) of the screw blade (9) remains on the circumference of the screw body (7) in the region of the cutouts on the screw body (7).
14. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the residual portions (29) have a radial extent which corresponds at least to the radial extent of the inner oil phase during the production of oil.
15. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the drum (3) and the screw (5) each have a cylindrical portion (5a) and a narrowing portion, the cutouts (27) and segregation elements (19) being formed exclusively in the region of the cylindrical portions (3a, 5a).
16. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that in the case of a multi-spiral screw, the cutouts (27) are formed in such a manner that passages are formed in the screw blade (9) in the circumferential direction.
17. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that at least one cutout (27), preferably 2 to 6 cutouts, per screw spiral is/are formed in the screw blade.
18. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that at least one, preferably 2 to 12, segregation elements project from the drum (3) per revolution of the conveying path (11).
19. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the segregation elements (19) - based on one or more helices - are distributed uniformly over the inner circumference of the drum (3).
20. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that at least two, preferably directly successive, screw spirals of the centrifuge are provided with the segregation elements (19) and cutouts (27).
21. Solid-bowl screw centrifuge according to one of the preceding claims, characterized in that the screw body (7) is provided with a diaphragm plate (30).

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