EP3700678A1 - Method for processing a flowable product and centrifuge - Google Patents

Abstract

A method for processing a flowable product (P) with a centrifuge, in particular a separator, with a vertical axis of rotation (D) with a rotatable centrifuge drum (1) in which a disc package (11) is arranged, at least one product outlet (13) for discharging at least a liquid phase (LP) and at least one solids discharge opening (10) for discharging a solid phase (SP), characterized by the following steps: a) pretreating the flowable product (P) so that particles in this product are increasingly attracted by electrically charged components; a) supplying the flowable product (P) to the plate package (11); b) generating an electric charge on the plates of the plate package (11) and c) depositing the charged particles from the flowable product (P) within the plate package (11) under the influence of electrostatic attraction forces and a centrifugal field and a centrifuge.

Description

 Process for processing a flowable product and centrifuge

The invention relates to a method for processing a flowable product according to the preamble of claim 1 and a centrifuge, in particular a separator, according to the preamble of claim 9.

DE 10 2006 022 156 A1 discloses a method and a device for the treatment of liquids, in which an incoming flowable product is separated in a centrifuge into two liquid phases and a solid phase. For this purpose, the product, for example a contaminated lubricating oil, is separated into two partial streams, which are conducted past a positive or a negative electrode. In this case, the particles which are contained in the first partial flow are positively charged and the particles of the second partial flow are negatively charged. Before introducing the liquid into the centrifuge, both partial streams are combined in a collection tank, whereby the positively charged particles and the negatively charged particles conglomerate to form larger particle dressings due to the mutual electrostatic attraction. These conglomerates are then easier to separate from the liquid in the centrifugal field. SU 5 51 036 discloses a centrifuge which enables electrostatic charging of particles within a non-continuous centrifuge. For this purpose, an electrode is arranged in an inlet chamber on the axis of rotation of the centrifuge. After electrostatic charging of the particles, they are passed on to a drum space in which the particles are deposited in solid collecting pockets. The clarified liquid is then removed from the centrifuge. The solid collecting pockets are embedded in the wall of the centrifuge. However, unlike a conventional centrifuge with a disc pack, continuous operation is not possible with this centrifuge because the collection bags must be emptied at regular intervals.

It is the object of the present invention, starting from the state of the art, to provide a method for processing a flowable product and to provide a centrifuge which allows an alternative approach for a better separation of particles. The invention achieves this object by a method having the features of claim 1 and a centrifuge having the features of claim 8.

According to the invention, a method for processing a flowable product with a centrifuge, in particular a separator with a vertical axis of rotation, with a rotatable centrifuge drum in which a plate package, at least one product outlet and at least one solids discharge opening is arranged, comprises the following steps:

 a) pretreatment of the flowable product so that particles in this product are increasingly attracted by electrically charged components;

 b) supplying the flowable product to the disk pack;

 c) generating an electric charge on the plates of the plate package and

 d) depositing the charged particles from the flowable product within the plate package (and thus under the influence of electrostatic attractive forces and a centrifugal field).

Through the targeted use of electrostatic forces in the disk gaps in the centrifugal field of a centrifuge, a better separation behavior of particles on the plates of the disk package is achieved in a simple manner. In addition, the already deposited particles remain adhered to the underside of the plate, so that a crossing of the particle and the product feed stream is prevented at the Telleraußendurchmesser and thus also that already deposited particles a second (or third, ...) times can get into the disk package.

Advantageous embodiments of the method according to the invention are the subject of the dependent claims.

In order to enable the action of the charged electric particles over a wide range, it is advantageous if they are generated on the plates of the plate package by a surface charge.

Particularly preferably, the electric field between the plates of the plate package and the remaining part of the centrifuge insulated therefrom is generated by impressing a charge starting from a DC voltage source.

In this case, the transmission of the positive or negative charge from the outside to a component of the centrifuge can take place, wherein one pole of the DC voltage source Le is contacted with an outer wall of this component and this component consists of electrically conductive material. After charge transfer, this charge is transferred or transferred to the plate package of the centrifuge. The pretreatment of step a) is preferably carried out outside the drum. The pretreatment is also preferably carried out in such a way that the particles are attracted to the charge of the plate package.

The pretreatment in step a) can take place according to a first advantageous variant of the invention by an electrostatic charging of the particles, for example outside the centrifuge. In this case, the product to be processed is passed past a positively or negatively charged electrode, whereby particles, for example solid particles, are charged to the electrode prior to entry into the centrifuge. This electrode is preferably arranged outside the drum. It is also conceivable, however, to integrate them into the inlet of the drum.

During deposition, these charged particles are increasingly attracted to the plate surface by the electrostatically charged plates, where they deposit and then adhere.

The pretreatment in step a) can be carried out according to an alternative variant of the invention but also by adding a ferrofluid, in order to achieve the above-mentioned effect.

After the particles have been deposited in step d), it is advantageously possible for the electric field to be switched off and / or discharged on the disk package, so that the deposited particles more easily slip off the surface of the disk into the solids.

During the polarity reversal or the switching off of the electric field, the degree of separation decreases by a few percent. Therefore, in order to advantageously avoid unnecessary polarity reversal or switch-off, the deposition can be monitored, for example by a probe on a product outlet of the liquid phase or liquid phase. If the proportion of solids exceeds a predetermined value, the deposition on the plate is insufficient. By monitoring the deposition, the process can be adapted to the respective product. Alternatively, the feed can be closed during the polarity reversal or switching off of the electric field.

According to the invention, a centrifuge, in particular a separator, a centrifuge drum, in particular a continuously operable separator drum with a vertical axis of rotation, in which a disc package is arranged, wherein the centrifuge drum at least one product feed for supplying a product to be processed, a disc pack for phase separation and at least an outlet for draining a liquid phase and a drain for discharging at least one further phase, in particular a liquid phase or a solid phase. The centrifuge also has at least one means for generating an electric charge on the plates of the plate package or in plate columns of the plate package. In a separator with electrostatically charged plates, particles are deposited in the region of a centrifuge, at which the deposition usually takes place without the additional influence of electrostatics. When a product containing charged particles is processed by the centrifuge, the deposition rate of these charged particles is improved, and crossing of the already deposited particles with the product feed stream is prevented.

Advantageous embodiments of the centrifuge according to the invention are the subject of the dependent claims.

To generate an electrical charge on the plates of a plate package, a suitable DC voltage source can be used, wherein the height of the generated voltage is preferably adjustable. In this case, a positive pole is present at one point of the separator and a negative pole at another point of the separator. One of the poles is conductively connected to the plate package. In this case, the disk pack is electrically insulated from the outer wall of the centrifuge drum by a coating or other non-conductive material, so that it can not come to a short circuit due to contact of the two components.

A suitable voltage level for such a DC voltage source is in the range between 5000 and 20,000 volts. In order to allow easy operation, the means for generating an electric charge on the plates of the plate package is preferably arranged outside the centrifuge drum. In an advantageous embodiment, a first pole of the DC voltage source can be arranged with positive or negative charge on the outer wall of a pump element of the centrifuge, which is connected to the plate package. For this purpose, the pole only has to be attached to the pump element, further design adjustments of the centrifuge drum are not necessary. This is advantageous, since thus an already existing centrifuge can still be retrofitted.

The invention will be described in more detail with reference to an embodiment with reference to a drawing. It shows:

1 is a partial sectional view of a separator drum in a hermetically sealed design.

A rotatable Separatortrommel 1 with vertical axis of rotation D is set to a rotary spindle 2, which is driven by a direct drive or by a belt drive, not shown here.

The rotary spindle 2 is conically shaped along an upper circumferential region and fastened with a fastening means 6 on the drum base 20.

A product inlet 4 is adjoined by a product inlet pipe 5 which rotates during operation and which is aligned concentrically with the axis of rotation D. From the product feed tube 5, the product P passes into a manifold 7 having manifold bores or fins from which the flowable product is e.g. can emerge in the radial direction in the interior of the separator drum 1. It is also conceivable (not shown here) to direct the product from the distributor into at least one rising channel in the plate package.

In the interior of the separator drum 1, the incoming product flows into the plate gap between conical plates of a plate package 1 1 spaced apart from one another by axially intermediate spacers.

In the plate columns clarification of the product (and possibly also a separation into two or more liquid phases) takes place by solid particles of the flowable product deposited on the undersides of the plates, which can emerge from there into a Feststoffsammeiraum 8. From there, the solid phase SP is discharged here discontinuously in the radial direction via solids discharge openings 10 from the separator drum 1, which can be opened and closed via a piston slide 9. The liquid phase LP is passed to a pump element 1 2 and discharged from there through a product outlet 1 3.

A better separation of solid particles in the disk columns of a Teller package is made possible in the present case by applying the plate package 1 1 with an electric charge. This also means that already deposited particles stick to the underside of the plate.

For this purpose, an outer wall 1 8 of the separator drum 1 or an outer wall 1 9 of the pump element 1 2 via a respective electrical line 1 5a and 1 5b connected to a positive and a negative pole of a DC voltage source 14.

A well accessible from the outside component, here the outer wall 1 9 of the pump element 12, consists of an electrically-conductive material and is conductively connected to the plate package, so this is positively or negatively charged depending on the connection to the DC voltage source. Another component, such as the actual separator drum 1 is polarized in the opposite direction. In order to avoid a short circuit, the plate package 1 1 is insulated from the inner wall of the separator drum 1, here by one or more non-conductive material layers 1 6, 1 7 above and below the plate package 1 first The distributor 7 is also insulated by an upper material layer 1 7 and a lower material layer 21.

In addition, the drum base 20 may also be insulated from the rotary spindle 2 by an electrically non-conductive material layer 22.

The product inlet pipe 5 and the manifold 7 are preferably made of an electrically non-conductive material or have a non-conductive coating, so that preferably already charged before entering the drum parts not settle or unload here already on the components. In the following, the mode of operation of the separator of FIG. 1 will be explained in more detail by means of a method for processing, in particular for clarification, of a flowable product. In addition, a pretreatment in the manner of step a) of claim 1. According to a variant of this pre-treatment, the product is first passed before entering the rotating separator drum to a negative or positive charged electrode of a DC voltage source, so that the solid particles in the product charge electrically. This electrode can also be arranged alternatively in the product feed 4 or in the feed pipe 5. The loading of the solid particles can also be done elsewhere before the entry of the product flow in the plate gap of the plate package 1 1. A suitable voltage level for such a DC voltage source is in the range between 5000 and 20,000 volts.

If the charging of the solid particles takes place prior to the entry of the flowable product stream into the separator, it is advantageous if the product supply pipe 5 and the distributor 7 consist of non-conductive material or are coated with non-conductive material, so that the deposition preferably takes place only in the disk package.

After the product has entered the drum 1, it enters the plate column of the plate pack 1 1. In this case, the charge of the particles of the product is opposite to the charge of the plates, so that the plate exerts an electrostatic attraction on the charged particles, which collect increasingly on the plates. The plate column therefore continue to grow over time.

By reversing or switching off the DC voltage source 14, there is then a repulsion of the accumulated particles, in particular of the solid particles, from the plate surface and a transport of the solid particles into the Feststoffsammeiraum 8 (preferably with interrupted feed).

As already explained, the plate package increases with time. It is therefore advantageous if this is suitably monitored during operation (for example based on the inflow quantity or the outflow quantity) and if, depending on the monitoring or periodically at predetermined time intervals, the plate package is reversed and, if appropriate, the drum is emptied rinse out the attached particles. For this purpose, the DC voltage source is preferably on connected the control system of the centrifuge (not shown here).

FIG. 1 shows a separator which allows a solid-liquid separation. However, the method can also be applied analogously to three-phase separators. As an alternative to the design of a separator in which the separator drum 1 is mounted on a rotary spindle 2, the deposition of solids on a charged plate package in other designs, e.g. be used with hanging drums.

The inventive method and the centrifuge are suitable for a wide variety of products, but in particular for the purification of a contaminated oil. It should also be noted that although the embodiment is preferred as a hermetically sealed machine with rotating inlet pipe and an instructive pump element, in which the product is pumped through the machine, it is not mandatory.

LIST OF REFERENCE NUMBERS

1 separator drum

 2 rotary spindle

 4 product feed

 5 product inlet pipe

 6 fasteners

 7 distributors

 8 solid sam mel m

 9 piston valve

 10 solids discharge opening

1 1 plate pack

 12 pump element

 13 product flow

 14 DC voltage source

 15a, b power lines

 1 6 non-conductive material layers

17 non-conductive material layers

18 outer wall separator drum

19 outer wall pump element

20 drum base

 21 non-conductive material layers

22 non-conductive material layers

D rotation axis

 SP solid phase

 LP liquid phase

 P product

Claims

claims 1 . Process for processing a flowable product (P) with a centrifuge, in particular a separator, with a vertical axis of rotation (D) with a preferably continuously rotatable centrifuge drum (1), in which a plate package (11) is arranged, at least one product outlet (13 ) for discharging at least one liquid phase (LP) and at least one solids discharge opening (10) for discharging a solid phase (SP), characterized by the following steps  a) pretreatment of the flowable product (P), so that particles in this product are increasingly attracted by electrically charged components;  b) supplying the flowable product (P) in the plate package (1 1);  c) charging the plates of the plate package (1 1); and  d) deposition of the charged particles of the flowable product (P) within the plate package (1 1). 2. The method according to claim 1, characterized in that the generation of the electrical charge to the disk package (1 1) by applying a pole of a DC voltage source (14) directly to the disk package (1 1) or to a conductively connected to the disk package part of Centrifuge drum takes place. 3. The method according to claim 2, characterized in that the plate package (1 1) is charged or polarized opposite to the charge of the particles of the product. 4. The method according to any one of the preceding claims, characterized in that the plate package (1 1) reversed or separated from the DC voltage source. 5. The method according to claim 4, characterized in that the polarity reversal or switching off of the electric field takes place periodically or as a function of the clarification behavior in the plate package (1 1). 6. The method according to any one of the preceding claims, characterized in that the pretreatment of step a) is carried out by an electrical charging of particles of the flowable product (P). 7. The method according to any one of the preceding claims, characterized in that the pretreatment in step a) before the introduction of the product into the rotating drum (1 1) takes place. 8. Centrifuge, in particular separator with a Separatortrommel, in particular a Separatortrommel (1) with a vertical axis of rotation (D), in which a plate package (1 1) is arranged, wherein the Separatortrommel (1) at least one product feed tube (5) for supplying a processing product, a plate package (1 1) for phase separation and at least one outlet (13) for discharging a liquid phase and a discharge (10) for deriving at least one further phase, in particular a liquid phase or a solid phase, characterized in that the centrifuge for carrying an electric charge on the plates of the plate package (1 1) is designed. 9. Centrifuge according to claim 8, characterized in that by means of a DC voltage source (14) an electric charge is placed on the plate of a plate package. 10. Centrifuge according to one of the preceding claims 8 or 9, characterized in that the plate package (1 1) by means of insulating layers (1 6.17) from the distributor manifold (7 and the inner wall of the centrifuge drum (1) is electrically isolated. 1 1. Centrifuge according to one of the preceding claims 8 to 10, characterized in that a to the product inlet (4) adjacent product inlet pipe (5), a rotary spindle attachment (6), a rotary spindle (2) and / or a rotary spindles consist of an electrically non-conductive material or with an electrically non-conductive material (21, 22) are coated. 12. Centrifuge according to one of the preceding claims 8 to 1 1, characterized in that the means for generating an electric charge on the plates of the plate package (1 1) outside the centrifuge drum (2) is arranged. 13. Centrifuge according to one of the preceding claims 8 - 12, characterized in that a first pole of the DC voltage source (14) a component of the centrifuge is connected, which is conductively connected to the plate package (1 1). 14. A centrifuge according to claim 13, characterized in that the second pole of the DC voltage source (14) is connected to a non-electrically connected to the disc package drum part. 15. Centrifuge according to claim 14, characterized in that it is designed as a hermetically closed construction.