EP2326427B1 - Centrifuge having a selfdischarging bowl - Google Patents

Description

The invention relates to a centrifuge with a self-cleaning centrifugal drum according to the preamble of claim 1.

A centrifuge with a self-cleaning centrifugal drum is from the DE-OS 19 09 996 known. Further developed constructions show the DE 32 08 808 A1 , the DE 32 40 093 A1 , the DE 35 09 139 C1 , the DE 35 24 731 C1 and the DE 36 07 526 A1 , With the known - known under the name Hydrostop - solutions can be particularly precise control part discharges, but it is in each case relatively expensive constructions.

It is also known to control piston valves for the temporary opening of a closing chamber by means of a metering device arranged outside the drum. The emptying behavior of such constructions, however, is not always optimal despite the metering devices, since no very large opening stroke of the piston valve is achieved (see FIG. 3). In addition, the dosing devices used require an increased cost.

In this respect, it is desirable to have a fast and also large opening stroke of the spool valve in order to enable a good and uniform discharge of solids even when processing less free-flowing solids.

The state of the art in addition to its DE 30 12 108 A1 and the EP 0 706 829 Both named according to the preamble of claim 1.

Against this background, the object of the invention is to create a centrifuge optimized with regard to its emptying behavior with simple structural means.

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

The construction according to the invention achieves an optimized emptying behavior with simple constructional means, which is in particular due to a rapidly initiated and relatively large evacuation stroke and a rapidly initiated one Signs closing, which leads to a rapid reduction of Austragsspalthöhe.

Advantageous embodiments of the invention can be found in the dependent claims.

Fig. 1

einen Schnitt durch einen Teilbereich einer erfindungsgemäßen Schleudertrommel;

Fig. 2

ein Diagramm, welches den Hub des Kolbenschiebers über die Zeit mit einer Schleudertrommel nach Art der Fig. 1 darstellt;

Fig. 3

ein Diagramm, welches den Hub des Kolbenschiebers über die Zeit mit einer bekannten Schleudertrommel darstellt; und

Fig. 4

eine schematisch schnittartig dargestellte, weitere erfindungsgemäße Schleudertrommel.

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

Fig. 1

a section through a portion of a centrifugal drum according to the invention;

Fig. 2

a diagram showing the stroke of the piston valve over time with a centrifugal drum in the manner of Fig. 1 represents;

Fig. 3

a diagram illustrating the stroke of the spool valve over time with a known centrifugal drum; and

Fig. 4

a schematically illustrated in section, another centrifugal drum according to the invention.

A processed material to be processed - a solid-liquid mixture - is through a central inlet 22 (see insofar as the schematically illustrated construction of Fig. 4 ) is supplied to a rotatable drum 1 of a (plate) separator with a vertical axis of rotation, which has a centrifugal space 2, which is divided into a separation space 3 and a solid space 4.

The solid space 4 is on one side - down here - limited by an axially movable piston slide 5, which releases or closes during its axial movements in the drum shell 6 ejection openings 7 for the solids.

Between the piston slide 5 and the drum shell 6 and the drum base is acted upon with a closing fluid lock chamber 8 is formed.

In the closing chamber 8 10 closing liquid can be introduced through an injection chamber 9 and a supply line. This closing fluid can be switched by one or more leads 11, in which one or more piston valves 12 are discharged from the drum 1, to which the piston valve 12 is acted upon by opening water, which is passed through an injection chamber 13 for opening water and a supply line 14 to the piston valve 12. The function of such a piston valve 12 is known per se in the field of self-draining separators.

To perform a drain opening water is injected, which moves the valve piston 16 of the spool valve 12, so that the closing water from the closing water opening 15 via the bore 11 and the valve 12 can drain.

Depending on the duration of the opening water addition or depending on the amount of opening water (supplied via a metering or a timing of the opening of the supply valve) empties the closing chamber 8 wholly or partially and the spool 5 moves through the pressure force in the separation chamber 3, which by the product in the Drum and the centrifugal action is generated, down and opens the drum. 1

Opening water and closing water are sprayed by means of control water supply lines 22a, b through two separate water supply lines into the injection chambers 13 and 9, respectively, into the drum.

When no more opening water is supplied, the valve piston moves outward (by the centrifugal force) and closes the bore 11. When the opening force is finally smaller than the closing force in the closing chamber 8, in which closing water is injected, the spool 5 moves up again , which closes the drum 1.

According to the invention, the closing chamber height, that is to say the distance between the inner wall of the drum and the spool in the region of the closing chamber 8, is kept relatively low, preferably the height is 0.3 mm to 5 mm, in particular 0.5 to 1.5 mm.

As a result, the volume of closed water is kept low. The height of the chamber significantly affects the rate of evacuation.

In order nevertheless to obtain a relatively large discharge stroke and to arrive at a rapid opening operation at the beginning of the emptying and a fast closing operation towards the end of emptying, but a defined increment of the lock chamber 8 is set to a predetermined diameter of the lock chamber. Preferably, the height of the closing chamber 8 multiplies in the region of this step jump, preferably the height of the closing chamber 8 in the region of the recesses 17 is three to fifteen times the gap height of the closing chamber 8 in the area adjacent to or outside of the recesses 17, in particular 3 to 20 mm, more preferably 5 to 12 mm, in particular 10 mm.

Preferably, this increment is introduced in the region of the lower part of the piston slide. This reversal range of the angle of the spool is usually - viewed from the outside diameter of the spool - between one third and two thirds of its radius.

In addition, the spool has here on its underside in its inner and outer edge region circumferential free rotations 20, 21 for better acceptance and for better removal of the closing water.

The invention can be realized, for example, in a simple manner in that recesses 17 are introduced into the side of the piston slide 6 facing the closing chamber at a certain diameter, for example two or more cutouts distributed around the circumference. The recesses 17 lead to an optimized emptying behavior, as exemplified in Fig. 2 is shown.

Like from the Fig. 2 can be seen results from the narrow gap in the inner radial region of the lock chamber 8 in the selected exemplary design for a drum 1, which has a slope angle α of 15 °, at the beginning of the emptying a significantly increased discharge stroke and a faster opening operation.

In addition, results from the gap widening in the region of the recesses 17 - which may be designed, for example, as recesses - an automatic and at the beginning of the closing process very fast closing behavior, except for a small residual gap.

By a suitable design - or variation - of the closing gap and the recesses 17 thus the emptying characteristic with respect. The emptying speed and the emptying amount can be adjusted specifically.

The recesses 17 also increase the insensitivity to valve timing variations, so that even a metering piston, which serves to adjust and control of partial discharges, can be dispensed with, which reduces the cost of construction over known solutions.

The cutouts 17 are designed depending on the nature of the product to be processed and the emptying (Teilentleerungsmenge) to be carried out, which can be done for example empirically by means of experiments until a characteristic of the type Fig. 2 with a relatively large, fast to a maximum value increasing opening stroke and a relatively fast stopping the emptying results.

Once determined characteristic of the opening path and the Teilentleerungsmenge is achieved reproducibly. Desired changes can be achieved by adjusting the recess 17 and its volume.

The spool of the Fig. 1 has starting from a radius R17 in the region of the cutouts radially inwardly and outwardly double conical shape, wherein the cutouts 17 are formed in the transition region 17 between the two conical regions 18 and 19 by way of example as two variants.

It would also be conceivable to provide only one cutout and to form this as a circumferential annular groove. For reasons of stability and in terms of a particularly optimal emptying sharp characteristic, it is advantageous to leave between the circumferentially distributed cutouts 17 and areas of the piston valve, in which the wall thickness of the piston valve is not weakened by the one or more recesses 17.

If the cutout (s) 17 in the piston valve is located farther out or, so increases the discharge of the solid at the partial emptying. If the position is further inside, the discharge volume decreases with the same valve opening time.

The comparison of the emptying characteristics as shown in Fig. 2 and 3 was carried out by way of example with a separator of the type MSD 300 of the Applicant. The lifting height of 100% refers to the mechanically realizable possibility of movement of the piston slide between the drum cover and the drum base. The time base of, for example, 1 sec refers to the control of the upstream solenoid valve for supplying the opening water.

reference numeral

drum

1

centrifugal chamber

2

separating space

3

Solid space

4

spool

5

drum shell

6

ejection openings

7

closing chamber

8th

Injection chamber

9

supply

10

derivations

11

piston valves

12

Injection chamber

13

channel

14

Closing water opening

15

plunger

16

recess

17

conical areas

18, 19

Scope of free spins

20, 21

Control water supply

22a, b

Claims (10)

1. A centrifuge, comprising a self-emptying centrifuge drum, in the drum shell (6) of which discharge openings (7) are formed, said openings originating from a solids chamber (4) and being closable by way of an axially movable piston slide (5), wherein a closing chamber (8) to which closing fluid can be applied is associated with the piston slide (5), which closing chamber can be discharged by actuating one or several hydraulic valves (12) by means of opening fluid, wherein the closing chamber (8) comprises at least one or several recesses (17), in the region of which the closing chamber (8) has a greater closing chamber height than in the remaining area thereof outside of the recesses (17), wherein the piston slide (5) has a double conical shape radially to the inside and to the outside, characterized in that the recesses are formed as milled-out portions formed in the transitional region between the two conical regions (18 and 19).
2. A centrifuge according to claim 1, characterized in that the recesses (17) are formed as cavities in the side of the piston slide (5) which faces the closing chamber (8).
3. A centrifuge according to claim 1 or 2, characterized in that the hydraulic valves are formed as piston valves (12).
4. A centrifuge according to claim 2, characterized in that the one or several recesses (17) are introduced in a circumferentially distributed manner on a specific diameter into the side of the piston slide (6) facing the closing chamber.
5. A centrifuge according to one of the preceding claims 2 or 4, characterized in that the milled-out portions (17) are introduced in a circumferentially distributed manner into the side of the piston slide facing the closing chamber.
6. A centrifuge according to one of the preceding claims 1 to 3, characterized in that the at least one recess (17) is formed as a circumferential annular groove.
7. A centrifuge according to one of the preceding claims, characterized in that the closing chamber height, i.e. the distance between the inner wall of the drum and the piston slide, amounts to 0.3 to 5 mm in the region of the closing chamber (8).
8. A centrifuge according to one of the preceding claims, characterized in that the closing chamber height, i.e. the distance between the inner wall of the drum and the piston slide, amounts to 0.5 to 1.5 mm in the region of the closing chamber (8).
9. A centrifuge according to claim 8, characterized in that the closing chamber height, i.e. the distance between the inner wall of the drum and the piston slide, amounts to 3 to 20 mm, especially 5 to 12 mm, in the region of the recesses (8).
10. A centrifuge according to one of the preceding claims, characterized in that in the region of the recesses (17) the height of the closing chamber (8) is 3 to 15 times the height of the closing chamber (8) in the region adjacent to the recesses (17).

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