EP1901849B1 - Three-phase solid bowl screw centrifuge and method of controlling the separating process - Google Patents

Description

The invention relates to a three-phase solid bowl screw centrifuge (three-phase decanter) according to the preamble of claim 1. The prior art, the DE 27 07 111 A1 , the US 3,623,656 , the WO 03/074185A1 , the DE 195 00 600 C1 , the DE 102 23 802 A1 , the DE 38 22 983 A1 , the WO 02/062483 A1 and the DE 26 17 692 Algenannt.

The US 3,623,656 shows a three-phase decanter, with the two liquid phases and a solid phase are derived from the drum. The liquid outlets can be adjusted by a conversion of the machine when the machine stops.

The WO 03/074185A1 shows a three-phase decanter, with the two liquid phases and a solid phase are derived from the drum also. With a weir, the flow rate of the heavier liquid phase can be adjusted.

The DE 38 22 983 A1 shows a three-phase decanter, with the two liquid phases and a solid phase are derived from the drum also, wherein one liquid phase is discharged through a weir and the other through a paring disc.

The DE 195 00 600 C1 and the DE 102 23 802 A1 show two-phase decanter, in which the liquid is discharged from a chamber by means of a paring disc.

The WO 02/062483 A1 shows a method of operating a solid bowl centrifuge.

The DE 26 17 692 A1 discloses a solid bowl centrifuge with multiple disc paces made up of separator plates and multiple screw sections.

Conversion parts are generally available for adapting to the respective product properties or for adapting the process to the respective conditions in the case of three-phase separating decanters.

For example, in the process of extracting olive oil in a three-phase process, if the product characteristics of the olive change from the beginning to the end of the harvest, it may be necessary to stop the processing, remove the rotor, and install other regulators and / or regulating tubes. This is time consuming and costly.

It has already been proposed to control the heavier phase by means of a non-rotating throttle disc arranged outside the drum and to discharge the lighter phase with a paring disc. Although this construction has proven itself, it requires at least the use of a sliding throttle plate from a constructive point of view.

On the other hand, by varying the throttling on the paring disc alone, the process is not sufficiently adjustable to the product properties to avoid rebuilding.

The invention has the object of reducing the design effort to create a slightly changed in itself product properties adaptable three-phase decanter. The invention solves this problem by the subject matter of claim 1.

Advantageous embodiments can be found in the dependent claims.

There may also be provided an inlet and a discharge for fluid in and out of the chamber.

By changing the pressure in the annular chamber - possibly in conjunction with a throttling of the paring disc - the separation zone can be easily moved in the drum, which also leads to a change in the liquid level. One by changing the characteristics of the product otherwise actually Required conversion can be omitted by utilizing the given control range usually. The design effort to create the annular chamber is low.

Preferably, the annular chamber as means for changing the pressure in the annular chamber on a fluid line for supplying a fluid, in particular a gas in the annular chamber.

The overflow for the other phase can be realized by radial discharge pipes, which pass through the drum shell or lid.

This basic structure can be realized in particular in two variants: in one, the heavier liquid phase is diverted through the discharge tube and the lighter one through the paring disc and the other the lighter liquid phase through the discharge tube and the heavier one through the paring disc. Both variants allow a good control of the process, but lead to different control characteristics. It is also a method for operating a three-phase solid bowl screw centrifuge conceivable in which the regulation of the separation process in the drum in the simplest way by changing the pressure in the annular chamber as a control variable. This variant is preferred because a simple and good control of the separation process is possible.

Alternatively, it is also conceivable that the regulation of the separation process takes place in the drum by changing the rotational speed of the drum as a manipulated variable.

Particularly preferably, the regulation of the separation process in the drum takes place as a controlled variable as a function of the concentration in the solid phase or in one or both of the liquid phases derived.

The invention is also particularly suitable for phase separation in the recovery of hydrometals such as e.g. Cobalt, nickel, copper.

Especially in the extraction of hydrometals such as cobalt, nickel, copper, the formation of emulsions in the extraction can not be avoided. The extraction and the emulsion consist of three phases, an organic phase, aqueous phase and solids. The open settling tanks of the extraction are susceptible to contamination from the air. These different dust concentrations lead to a density difference of the individual phases in the emulsion. Here, the decanter according to the invention provides a remedy.

To meet these dynamic process requirements, the separation diameter within the decanter can be adjusted online by applying pressure to the annulus. This separates the emulsion cleanly into the three phases. The use of a centrifuge according to the invention in emulsion separation in the recovery of hydrometals such as e.g. Cobalt, nickel, copper thus offers considerable advantages.

Fig. 1

eine Schnittansicht einer ersten erfindungsgemäßen Dreiphasen-Vollmantel-Schneckenzentrifuge;

Fig. 2

eine schematisierte Schnittansicht eines Teilbereiches der Vollmantel-Zentrifuge aus Fig. 1 in einem ersten Betriebszustand;

Fig. 3

eine schematisierte Schnittansicht eines Teilbereiches der Vollmantel-Zentrifuge aus Fig. 1 in einem zweiten Betriebszustand;

Fig. 4

ein Diagramm zur Veranschaulichung des Betriebsverhaltens und der Regelbarkeit von Trenn- und Klärprozessen mit der erfindungsgemäßen Vollmantel-Zentrifuge aus Fig. 1;

Fig. 5

eine Schnittansicht einer zweiten erfindungsgemäßen Dreiphasen-Vollmantel-Schneckenzentrifuge;

Fig. 6

eine schematisierte Schnittansicht eines Teilbereiches der Vollmantel-Zentrifuge aus Fig. 5 in einem ersten Betriebszustand;

Fig. 7

eine schematisierte Schnittansicht eines Teilbereiches der Vollmantel-Zentrifuge aus Fig. 5 in einem zweiten Betriebszustand;

Fig. 8

ein Diagramm zur Veranschaulichung des Betriebsverhaltens und der Regelbarkeit von Trenn- und Klärprozessen mit der erfindungsgemäßen Vollmantel-Zentrifuge aus Fig. 5.

The invention will be described in more detail below with reference to the drawing with reference to exemplary embodiments. It shows:

Fig. 1

a sectional view of a first three-phase solid bowl screw centrifuge according to the invention;

Fig. 2

a schematic sectional view of a portion of the solid bowl centrifuge Fig. 1 in a first operating state;

Fig. 3

a schematic sectional view of a portion of the solid bowl centrifuge Fig. 1 in a second operating state;

Fig. 4

a diagram illustrating the performance and the controllability of separation and clarification processes with the solid bowl centrifuge according to the invention Fig. 1 ;

Fig. 5

a sectional view of a second three-phase solid bowl screw centrifuge according to the invention;

Fig. 6

a schematic sectional view of a portion of the solid bowl centrifuge Fig. 5 in a first operating state;

Fig. 7

a schematic sectional view of a portion of the solid bowl centrifuge Fig. 5 in a second operating state;

Fig. 8

a diagram illustrating the performance and the controllability of separation and clarification processes with the solid bowl centrifuge according to the invention Fig. 5 ,

Fig. 1 and 5 show parts of three-phase solid bowl screw centrifuges, which has a rotatably mounted (bearing 17) drum 1 - here with a horizontal axis of rotation - and arranged in the drum 1 rotatable screw 2 with a screw body 3, on which a rotating screw blade 4 is arranged. In operation, the drum 1 and the screw 2 rotate at different speeds n, m about the same axis of rotation (at the diameter D ₀ ). Between drum 1 and screw body 3, a bearing 16 is arranged. The second bearing of the screw is located on the solid side (not shown here).

At its one end, both the drum 1 and the screw 2, e.g. conical. At the tapered end of the drum 1, a Feststoffaustrag 24 for the transported by the screw to this end of the drum 1 solid phase S is arranged, whereas two separable from each other in the centrifugal liquid phases LL and HL - a lighter and a heavier liquid phase - in the opposite cylindrical end of the drum 1, which is closed by a drum cover 5, are derived from the drum 1.

On the worm body 2, a baffle plate 18 may for example be arranged on the worm body 3 in the transition region to the tapering section.

An inlet pipe 19 here extends, for example, from the cylindrical end of the drum 1 into the drum 1. It opens into a distributor 20, via which the product is passed into the drum 1.

The drum cover 5 has a plurality of the drum cover axially penetrating openings or openings 21, 22. Preferably, between four and eight such openings on a circle of a predetermined diameter circumferentially distributed in the drum cover 5 are formed.

A portion of these openings - hereinafter referred to as first openings 21 - is formed in the manner of one-sided closed recesses (or in the manner of blind holes) and serves to drain the heavier liquid phase HL and a portion of these openings - hereinafter referred to as second openings 22 - serves to discharge the lighter liquid phase LL.

To realize this, a part of the openings - the first openings 21 - a scheidetellerähnliches Scheidewehr 6 upstream, which is configured and arranged such that on the outer radius of this cutting gun 6 in all intended operating conditions, only the heavy phase is derived. The second openings 22, however, have no such divider.

In that regard, the constructions of the same Fig. 1 and 5 ,

To Fig. 1 and 5 On the other hand, the regions of the decanter 1 arranged downstream of the first and second openings are quasi "interchanged" or the separating rifle is located in front of the openings leading to the paring disc 9.

This will be explained in more detail below.

To Fig. 1 the heavier - radially outward-collecting - liquid phase on the cutting head 6 on the drum cover in each case in an adjoining the cutting head 6 over part of the circumference of the cutting head 6 discharge chamber 7 - here formed by the openings 21 itself - passed. In the discharge spaces 7 each projecting the drum shell passing discharge pipes 8, wherein the inner radius to which the respective discharge pipe 8 extends, also miter the drain radius for the heavier liquid phase HL.

This discharge radius for the heavier phase HL is not variable during operation or during a running process, but it can be changed or set at a standstill of the drum 1 by exchanging the discharge tube 8 and the tube against one with a different length.

The derivative of the lighter liquid phase LL, however, takes place after passing through the second openings 22 by means of a paring disc 9, which is arranged in a peel chamber 10 upstream of the drum shell, which connects axially to the drum interior and whose inner diameter is equal to or - preferably - smaller than that Inner diameter of the drum 1 in its cylindrical portion. The light liquid phase LL is discharged through this peeling disk 9 and a subsequent discharge channel 23 from the drum.

The peeling disk 9 are connected to the interior of the drum - see also Figs. 2 and 3 - in the peeling chamber 10 axially upstream two regulating disks 11, 12 of the same inner diameter, which extend radially from outside to inside and between which a siphon disk 13 dives extends in the peeling chamber 10 from the inner periphery thereof to the outside and whose outer diameter is at a larger radius relative to the rotational axis D of the drum 1 than the inner diameter of the two Regulierscheiben 11, 12th

The regulating blade 11 facing the cutting-edge gun provides an overflow diameter for the easy liquid phase LL.

Between the siphon disc 13 and the peeling disc 9 as the axial delimitations, the inner radius of the lighter liquid phase in this axial region and the inner shell or the inner wall of the peeling chamber 10 in this area, an annular chamber 14 thus forms during operation.

In this annular chamber 14 opens a fluid supply line 15 through which a fluid, e.g. a gas can be passed into the annular chamber 14.

It is thus possible to change the pressure in the annular chamber 14, which also causes a change in the radius of the lighter liquid phase and thus reacts on the separation diameter in the drum 1. Thus, it is possible in a simple manner, these two sizes - pond depth (inner radius drum minus the radius at the line D mirror level, eg in Fig. 3 ) and separation zone between light and heavy phase - to influence or change during operation only by changing the pressure in the annular chamber 14.

By choosing the diameter of the Regulierscheiben 11, 12 or by their replacement, the overflow diameter of the lighter phase can be preset.

If the pressure in the annular chamber 14 is increased, the liquid level in the interior of the drum rises to the center (pond depth). Analogously, the separation zone diameter pushes further outwards (compare Fig. 2 and 3 ).

Thus, the layer thickness of the lighter phase (dashed vertically) becomes larger and the outflow velocity smaller (longer sedimentation time). The degree of clarification of the lighter phase is thus increased or better.

As the separation zone moves outwards, the degree of clarification of the heavier phase (horizontally dashed) tends to be worse. The crossed hatching indicates a mixed phase or separation zone region.

The drain pressure of the lighter phase (peeler pressure) can be largely varied independently of the chamber pressure.

For example, as the heavy phase (or mixed phase) concentration increases, the pressure in the annular chamber 14 is increased to further shift the separation zone in the interior of the drum to a larger radius. This usually causes a greater layer thickness and a better degree of clarification of the lighter phase or a better phase separation.

The trend behavior described above is also the diagram of Fig. 4 refer to.

In the diagram, the diameters of the sequence for the light and heavy liquid phase are entered and the mirror level D_Spiegelstand in the drum 1 and the separation diameter D_Trenn depending on the pressure in the annular chamber fourteenth

The diagram of FIG. 4 shows the behavior at a constant speed. The liquid filling in the drum 1 is not constant due to the change in pressure. D in each case the diameter in the drum on both sides of the axis of rotation is designated. The diameter D_tubes (diameter of discharge pipes) and D_Scheidewehr are kept constant during operation, although they are per se changeable (by replacement). Constant are also the inner diameter of the drum and the inner diameter of the solids discharge, which are usually not changeable by conversion. The diameter on which the separation zone lies (separation diameter) increases with the pressure. The liquid level D_Spiegelstand, however, decreases inversely proportional to the pressure.

Fig. 2 and 3 show the conditions in the drum schematically at two different pressures.

It is also possible to predetermine a pressure in the annular chamber 14 during operation and then to achieve a change in the separation diameter in the drum solely by changing the drum speed. This change in the speed can be done, for example, depending on a concentration measurement of the product inlet or outlet.

However, the control range is smaller in this type of control and can only be used if a change in the drum speed during operation is permitted at all. The diameter of the separation zone then increases with the speed (not shown here).

Another embodiment shows Fig. 5 , Here, the heavier liquid phase is discharged via the regulating disk arrangement and the peeling disk 9, and the lighter liquid phase via the discharge pipe 8, which is achieved in that the dividing disk-like separating gun is arranged in each case in front of the continuous, second openings 26 open on both sides. The separating rifle 6 thus directs the heavy liquid phase HL to the paring disc, whereas the light phase is discharged into the blind-hole-like or at one end closed first openings 25 via the discharge tubes 8.

In the annular chamber 14, the pressure thus acts on the heavier liquid phase.

When the pressure in the annular chamber 14 is increased in the embodiment, on the drum side of the siphon disk 13, the inner diameter of the heavier phase shifts toward the center, and the separation zone diameter shifts further toward the inside. As a result, the layer thickness of the lighter phase LL becomes smaller and the outflow velocity increases. The degree of clarification of the lighter phase is thus reduced. Fig. 6 shows the state of higher pressure and Fig. 7 the state after a pressure drop in the annular chamber 14th

By contrast, as the separation zone moves inward, the degree of clarification of the heavier phase becomes better.

As a control variable, for example - preferably - the concentration distribution of any of the derived phases is used.

For example, as the pressure of the heavy liquid phase in the light increases, the pressure is reduced to further shift the separation zone in the interior of the drum to a larger radiance. This usually causes a greater layer thickness and a better degree of clarification of the lighter phase.

The corresponding control behavior is illustrated Fig. 8 using an example analogous to Fig. 4 , In turn, the different diameters depending on the pressure in the annular chamber 14 are worn.

It is also possible here to predetermine a pressure in the annular chamber 14 during operation and then to achieve a change in the separation diameter in the drum solely by changing the drum speed. This change in the speed can be done, for example, depending on a concentration measurement of the product inlet or outlet.

However, the control range is smaller in this type of control and can only be used if a change in the drum speed during operation is permitted at all. <B> reference numerals </ b> drum 1 slug 2 screw body 3 screw blade 4 drum lid 5 vagina military 6 derivation room 7 drain pipe 8th peeling disc 9 peeling chamber 10 regulating rings 11, 12 siphon 13 annular chamber 14 fluid supply lines 15 camp 16, 17 baffle plate 18 inlet pipe 19 distributor 20 openings 21, 22 Waterway 23 solids outlet 24 openings 25, 26 liquid phases LL, HL Solid phase S speeds n, m

Claims (7)

1. Three-phase solid bowl screw centrifuge having

   a. a rotatable drum (1) and a screw (2) arranged in the drum (1),

   b. at one axial end of the drum (1), at least one solid material discharge and, at its other axial end, at least two or more liquid outlets for liquid phases of different densities - a lighter liquid phase (LL) and a heavier liquid phase (HL),

   c. one liquid outlet having a skimmer disk (9) arranged in a skimmer chamber (10), and the other liquid outlet being constructed in the fashion of an overflow,

   characterized in that

   d. two regulating disks (11, 12), preferably of an identical inside diameter, being disposed in front of the skimmer disk (9), which extend radially from the outside toward the inside and between which a siphon disk (13) dips which extends in the skimmer chamber (10) from its interior circumference toward the exterior,

   e. so that, between the siphon disk (13) and the skimmer disk (9) as axial boundaries, the inside radius of the lighter liquid phase in this axial area and the inside shell in the skimmer chamber (10), an annual chamber (14) is formed during the operation,

   f. into which annular chamber (14) at least one fluid pipe leads for changing the pressure in the annular chamber, by way of which fluid pipe the pressure in the annular chamber can be changed, in order to change the separating zone and/or the pool depth in the drum,

   g. wherein first and second axial openings (21, 22; 25, 26) are provided in the drum lid and wherein a separating-plate-type separating weir being assigned to the first or the second openings,

   h. and wherein a design of the separating weir (6) is provided in such a way that the heavier liquid phase can be guided by way of the separating-plate-type separating weir (6) into at least one discharge space (7) in which at least one discharge pipe (8) penetrating the drum shell is inserted as the overflow.
2. Three-phase solid bowl screw centrifuge according to Claim 1, characterized in that some of the openings - the first or second openings (21, 22; 25, 26) - are constructed like a pocket hole closed at one axial end in the fashion of a chamber.
3. Three-phase solid bowl screw centrifuge according to one of the preceding claims, characterized by an arrangement of the separating weir such that the lighter liquid phase is guided to the skimmer disk (9) during the operation.
4. Three-phase solid bowl screw centrifuge according to one of the preceding claims, characterized by an arrangement of the separating weir (6) such that the lighter liquid phase can be guided into the discharge space (7), in which a discharge pipe (8) penetrating the drum shell is inserted as an overflow.
5. Three-phase solid bowl screw centrifuge according to one of the preceding claims, characterized by an arrangement of the separating weir such that the heavier liquid phase is guided to the skimmer disk (9) during the operation.
6. Three-phase solid bowl screw centrifuge according to one of the preceding claims, characterized in that the skimmer disk (9) is arranged in the skimmer chamber (10) which axially adjoins the drum interior and whose inside diameter is equal to or preferably smaller than the inside diameter of the drum (1) in its cylindrical area, and in that the two regulating disks (11, 12) and the siphon disk (13) are disposed in front of the skimmer disk (9) in the skimmer chamber (10).
7. Three-phase solid bowl screw centrifuge according to one of the preceding claims, characterized in that several, particularly four to eight, first and second openings (21, 22) are arranged in the drum lid on an imaginary circle and distributed along the circumference, one of the separating weirs being assigned to each second opening.

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