EP2783754A1 - Device for breaking up solid material - Google Patents

Abstract

The device (1) has container (2) for receiving solid materials (4). A pressure wave generator (10) is connected to voltage source (16) through plate-shaped electric conductors (14), to generate pressure waves in the liquid. The electric conductors are set with top side (28) and bottom side (30). The top side of electric conductor is set to face bottom side of other electric conductor. The electric conductors are wrapped by electrically insulating material e.g. ceramic material, glass-fiber reinforced plastic or epoxy resin.

Description

The invention relates to a device for comminuting solids, the device comprising a container for receiving the solids, a voltage source for generating a voltage and a pressure wave generator, which is connected via two electrical conductors to the voltage source and is arranged in a liquid, which is in the container to create pressure waves.

Such a device is for example from the DE 195 43 914 C1 known. The solids to be crushed are introduced into the container of the device, which is filled with a liquid or is subsequently filled. In this fluid pressure waves can be generated by the pressure wave generator, which propagate in the liquid and meet the charged solids. As a result, they are mechanically crushed. With such a device, it is possible to reduce the solids to the extent that they are present in nanoparticles. The pressure wave generator often has two protruding into the liquid electrodes. In the DE 195 43 914 C1 For example, a receiving basket in which the solids are placed is used as one of the electrodes. Between these two electrodes, a voltage is applied which is so high that breakdown occurs. Thus, an arc arises within the liquid which, due to the hydroelectric effect, leads to shock waves which propagate in the liquid.

Such systems are operated pulsed, so that abut the electrodes short voltage spikes, which cause the arc. In addition to high voltages and large currents are needed, so that the energy consumption is relatively high. From the prior art, therefore, some attempts are known to make generic devices more efficient and to achieve better efficiency. From the DE 195 34 232 C2 For example, it is known to tune the shape of the voltage spikes to the respective material, so that the arc is not generated or not only in the liquid, but at least in the solid itself to be crushed. As a result, shock waves are triggered in the solids or solid fragments along internal discharge paths through which the individual solids explode. However, this results in a very precise knowledge of the materials and an individual adjustment of the voltage peaks on the respective materials. This leads to an increased tax expense, so that more complicated and complex control mechanisms must be provided. This makes the apparatus design complex and thus expensive.

From the US 5,758,831 a device is known in which the container has an interior which is formed elliptical. This ellipse, which describes the contour of the interior, has two foci, with the material to be crushed near one focal point, and the two electrodes positioned to form the arc at the second focal point of the ellipse. However, this has the consequence that the two electrodes must be positioned relatively accurately to ensure that the arc is generated at the desired location. In addition, it is not possible to change the distance, for example, of the electrodes from the material to be comminuted in order to be able to respond to changed material properties or size distributions in the solids to be comminuted.

Similar devices are known from medical technology, with which, for example, kidney stones can be smashed. As an example, be here on the DE 197 18 513 C2 and the EP 590 177 B1 directed.

The present invention has for its object to improve a generic device according to the preamble of claim 1 so that it has a better efficiency.

The invention achieves the stated object in that the electrical conductors are plate-shaped, each having an upper side and an upper side opposite the underside and are arranged so that the upper side of an electrical conductor faces the underside of the other electrical conductor.

The invention is based on the finding that particularly strong pressure waves can be generated, for example, by a generated arc when the voltage peak sent by the electrical conductors to the pressure wave generator has as steep flanks as possible. This is achieved in particular by the fact that the device and in particular the electrical conductors are formed as low induction. Such considerations are not known from the prior art.

From the US 5,758,831 On the contrary, it is known to conduct the electrical conductors together to the pressure wave generator. For this purpose, a single coaxial cable is used, wherein the core or the inner conductor forms the first electrical conductor and the outer conductor or the shield forms the second electrical conductor. Now, if a voltage and current spike is sent through such a cable, for example, to generate an arc between two electrodes, strong magnetic fields and inductions occur which prevent a rapid transmission of the current with the applied voltage. Therefore, the invention proposes to form the electrical conductor plate-shaped. This means that the respective electrical conductors in a first direction perpendicular to the current flow direction a clear greater extent than in a second direction, which is perpendicular to the first direction and in the current flow direction. The electrical conductors have an upper side, a lower side and two side surfaces, wherein the upper side and the lower side are larger than the side surfaces. The respective surfaces need not be flat, but may be curved or curved. Such electrical conductors, which may be made of copper, for example, lead to a significant reduction in the current density and thus to a reduction in the magnetic fields in the outer space in comparison to the previously used coaxial cables, which have a significantly smaller cross-sectional area for the respective electrical conductors the electrical conductors around. In addition, the magnetic fields of the two electrical conductors for the case that they are traversed by current, hardly influence each other when the two electrical conductors are arranged together so that an upper side of the one conductor facing the underside of the other conductor is.

As a result of the configuration of the two electrical conductors according to the invention, the inductances in the system are consequently minimized so that there is little or no displacement of the current peak relative to the voltage peak. This results in a particularly steep increase of the current pulse, so that a particularly advantageous arc and thus a particularly strong pressure wave can be generated.

The pressure wave generator therefore preferably has two electrodes projecting into the liquid. Of these, one is connected to the first electrical conductor and the other to the second electrical conductor, so that the circuit closes at the moment where an arc is generated between the two electrodes. This leads in the liquid to a sudden evaporation of a part of the liquid and thus to a sudden volume increase. As a result, a first pressure wave is generated. Upon later collapse of the cavities thus produced, another Pressure wave generated so that two pressure waves of opposite sign propagate in the liquid and meet the shredded solids.

As has been found advantageous if the two electrical conductors are parallel to each other. This results in a particularly homogeneous formation of the individual magnetic fields and thus the lowest possible influence on the current flow in the electrical conductors by the magnetic fields of the other conductor. In addition, it is a structurally simple and thus advantageous embodiment of the device.

The two electrical conductors are advantageously encased in an electrically insulating material. Particularly preferably, the two conductors are wrapped together in this material. The material can be present for example in prefabricated moldings, in which the two electrical conductors are inserted, for example. The moldings can then be connected to each other, for example, glued, screwed or riveted to ensure the most secure attachment of the moldings to each other. This secure attachment is necessary to accommodate the forces caused by the large currents and voltages can. The electrical conductors are completely surrounded in this state by the insulating material, of course, an electrical contact continues to be possible.

Preferably, the two electrical conductors are cast in the electrically insulating material. As a result, a particularly secure connection between the insulating material and the conductor is ensured and a precise production of any required molded parts made of the electrically insulating material is unnecessary. This reduces the manufacturing effort and at the same time increases the quality of the electrical insulation.

The electrically insulating material is advantageously a ceramic material, a glass fiber reinforced plastic or an epoxy resin. Of course, combinations of these materials are possible. In particular, the glass fiber reinforced plastic is characterized by easy processability, good customization options to the particular shape of the electrical conductor and a low weight. On the other hand, epoxy or liquid ceramics can be used to pour the conductors into the material to achieve the advantages already mentioned.

The pressure wave generator is advantageously switchable by a switching element that is designed as a thyratron. A thyratron is known as a high-power switch of the prior art and can be used in particular when large electrical currents and / or electrical voltages must be used. This is the case in particular for the design of the device with two electrodes, in which an arc has to be generated in the liquid. Particularly in these cases, electrically insulating materials are advantageous in which the electrical conductors can be cast in order that the sometimes considerable current forces which can occur in the electrical conductors can be absorbed. Thus, it is particularly possible to achieve very low insulation distances between the two electrical conductors, so that the system can be structurally compact. Experiments have shown that a distance between the two plate-shaped electrical conductors of five millimeters at a capacitor voltage of 15,000 volts is sufficient.

It has proven to be advantageous if a distance between the two electrodes is preferably infinitely adjustable. By the distance, on the one hand, the length of the generated arc and on the other hand, the voltage and current required for this purpose are set. The smaller the arc, the smaller the expansions of the generated pressure waves. This may be particularly advantageous in the event that small solid components continue to be crushed. In this way, it is possible to act in a focused manner on the respective workpiece while at the same time reducing the energy required.

In a particularly preferred embodiment of the device, the position of the electrodes in the container is adjustable. In this way it is possible to react to the particular conditions of the solids to be comminuted and, for example, the distance between the electrodes and the arc to be generated between them and the solids to be comminuted be adjusted. The pressure waves generated by the arc decrease in their intensity with the distance from the arc from square, so that an efficient and effective crushing the smallest possible distance from the arc is desirable. By a displacement of the electrodes within the container, the position of the arc can be adjusted freely, so that the best possible position is achievable relative to the solids to be crushed.

Of course, other possibilities of pressure wave generation are conceivable. The pressure wave generator can advantageously also have, for example, a pulsed laser, by means of which shock or pressure waves can likewise be generated in the liquid. Of course, other ways known in the art are also useful in a device according to one embodiment of the present invention.

With the device, it is possible to reduce solids to nanoparticle size, which may have an extension of a few tens of nanometers. In order to prevent these particles settle to the bottom of the container and so can take a large and thus unfavorable distance from, for example, the electrodes of the pressure wave generator, a swirling device may be present, which circulates the liquid and thus the solids present in the liquid. In this way ensures that all solids are moved and can be brought into the most favorable distance to the generated arc or the pressure waves generated in any other way. In addition, it is possible to operate the device, for example, in continuous operation and so for example by a sieve at the bottom of the container to dissipate the solids components which have a sufficiently small size and at the same time introduce fresh material and fresh solids to be crushed into the container. The duration, strength and frequency of the individual pressure waves generated by the pressure wave generator depends not only on the solids to be comminuted but also on the size distribution of the solids before and, of course, also after comminution.

In particular, in the event that the pressure waves are generated by an electric arc, in addition to the pressure waves and electrical and magnetic fields act on the materials to be crushed. If such an electrohydraulic pulse encounters, for example, an elastomer in a liquid medium, its glass transition temperature drops by up to 20 degrees, depending on the consistency of the elastomer. This means that materials whose glass transition temperature is in a range just above the temperature of the liquid used need not be embrittled before comminution with the device. An additional use of liquid nitrogen or similar embrittlement is therefore eliminated. Thus, the comminution of these elastomers, which are otherwise not to be comminuted without additional embrittlement by mechanical impulse effects, is possible.

The container advantageously has an inlet and a discharge line through which the liquid can be filled into or removed from the container. It has also been found to be advantageous if different liquids can optionally be introduced into or removed from the container at different temperatures and pressures through this inlet and outlet. So does the device For example, a feeder for supplying liquid CO2 in the container. For this purpose, the said supply line is used. For example, the liquid CO2 is under a pressure of 70 bar, so that the solids which are to be comminuted by the device are permanently exposed to this pressure. As a result, process oils and other, in particular, liquid substances are pressed out of the solids, for example.

The device also advantageously has a pressure relief device, through which the container can be vented or relaxed so that the pressure at which the carbon dioxide is reduced. As a result, the carbon dioxide enters the gaseous phase. If the solids are contaminated solids, components extracted from the liquid CO2, and especially toxic and hazardous substances, can be removed in a gaseous manner with the carbon dioxide from the container and then extracted from the CO2. The carbon dioxide can be purified and reused. Again, the device has suitable facilities.

By transferring the liquid carbon dioxide in the gaseous phase, it also leads to a strong cooling of the temperature within the container and thus also the temperature of the solids. This is particularly advantageous for the further comminution of elastomers or other plastics which are embrittled by the strong cooling and thus become accessible to mechanical fragmentation.

After the carbon dioxide has been removed from the container, for example, water can be introduced as a new liquid via the supply line. In this liquid are then generated by the pressure wave generator for crushing necessary pressure waves. The crushed and crushed solids can subsequently as in any other device described herein, for example by ultrafine sieves, in the continuous Procedure the container be withdrawn.

• Figur 1 - die schematische Ansicht einer Vorrichtung gemäß einem ersten Ausführungsbeispiel der vorliegenden Erfindung
• Figur 2 - die schematische Darstellung aus Figur 1, in der die Druck wellen erzeugt werden,
• Figur 3 - die Darstellung eines Teils einer Vorrichtung gemäß einem Ausführungsbeispiel der vorliegenden Erfindung,
• Figur 4 - die Darstellung eines weiteren Ausschnittes einer Vorrichtung gemäß einem Ausführungsbeispiel der vorliegenden Erfindung und
• Figur 5 - eine weitere Darstellung einer Vorrichtung gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.

With the aid of a drawing, an embodiment of the present invention will be explained in more detail below. It shows:

• FIG. 1 - The schematic view of an apparatus according to a first embodiment of the present invention
• FIG. 2 - The schematic representation of FIG. 1 in which the pressure waves are generated,
• FIG. 3 the representation of a part of a device according to an embodiment of the present invention,
• FIG. 4 - The representation of another section of a device according to an embodiment of the present invention and
• FIG. 5 - Another illustration of a device according to an embodiment of the present invention.

FIG. 1 shows a device 1 according to a first embodiment of the present invention. It has a container 2, in which in the in FIG. 1 shown embodiment to crushing solids 4 are located. The container 2 can be closed by a cover 6, in which there is an opening 8, through which a pressure wave generator 10 projects into the container 2. This has two electrodes 12 whose distance from each other via an adjustment device, which in FIG. 1 not shown, can be adjusted.

The pressure wave generator 10 is connected by two electrical conductors 14 with a Voltage source 16 connected. The electrical conductors 14 are represented by parallel double lines. They are plate-shaped and in FIG. 1 shown in a side view, so that the electrical conductors 14 in a direction perpendicular to the plane of a significantly greater extent than those in FIG. 1 shown extension from top to bottom. The representation of the electrical conductors 14 has been chosen to illustrate that only a very small distance must be maintained between the two electrical conductors 14 in order to prevent a flashover of an electrical spark between the two electrical conductors. Preferably, the electrical conductors 14 are cast in an electrically insulating compound.

In the course of the electrical conductors 14, a switching element 18 is inserted, which may be formed for example in the form of a thyratron. By the switching element 18, the electrical voltage is conducted from the voltage source 16 to the electrodes 12, between which then the arc is formed.

The voltage source 16 is preferably connected to a plurality of capacitors, which apply the voltage required for the arc. In addition to the voltage source 16 is an operating device 20, in which, for example, the desired voltages and currents are adjustable and readable via display elements 22. In addition, for example, a distance of the two electrodes 12 from one another or a position of the electrodes 12 relative to the introduced solids 4 can be set.

FIG. 2 shows the device 1 from FIG. 1 in which the switching element 18 has forwarded the electrical voltage generated by the voltage source 16 to the electrodes 12. This creates an arc 24 through which the in FIG. 2 schematically indicated pressure waves 26 are generated. The solids 4, which are located in the container 2, are crushed by these pressure waves 26.

One recognizes both in FIG. 1 as well as in FIG. 2 in that the two electrical conductors 14 are arranged such that an upper side 28 of the lower electrical conductor 14 in the figures faces an underside 30 of the upper electrical conductor 14 in the figures.

FIG. 3 shows a section of the device 1 according to another embodiment of the present invention. The central switching element 18 is shown in the form of a thyratron, which is surrounded by the plate-shaped electrical conductors 14. Each of the two electrical conductors 14 has an upper side 28 and a lower side 30, wherein the two electrical conductors 14 are arranged such that the upper side 28 of the lower electrical conductor 14 faces the underside 30 of the upper electrical conductor 14.

It can be seen that the electrical conductors 14 are located to the left and right of the switching element 18, wherein the electrical conductor 14, which forms the upper electrical conductor 14 on the right side, forms the lower electrical conductor on the left side. In between, these two components are connected by columnar conductor elements 32. The connection between the other two electrically conductive components, which form the second electrical conductor 14, takes place through the switching element 18.

FIG. 4 shows a further section of a device 1. It can be seen again the switching element 18 and the two electrical conductors 14. Am in FIG. 4 Right end of the two electrical conductors 14 is in each case a contact element 34, at the lower ends of which there is an electrical lead 36 which leads to the electrodes 12 which are contained in the container 2 shown.

As well in FIG. 3 as well as in FIG. 4 It can be seen that the distance between the two electrical conductors 14 is formed from each other relatively small relative to their extent in the remaining spatial directions. This is possible due to the special geometric configuration of the electrical conductors 14. In the Figures 3 and 4 the electrical conductors 14 are not yet embedded in an insulating material.

FIG. 5 whereas the device is shown in FIGS Figures 3 and 4 wherein the electrical conductors 14 are enclosed in an electrically insulating material 38. The insulating material 38 is in FIG. 5 shown embodiment in the form of rail elements, which are wrapped around the electrical conductors 14 and connected to a plurality of connecting elements 40, which may be formed, for example, as screws.

Of course, it is also possible to use an electrically insulating material 38, which can be processed, for example, in the liquid state and pour the electrical conductors 14 into this material.

The electrical leads 36 extend from in FIG. 5 right end of the electrical conductors 14 down into the container 2 of the device first

LIST OF REFERENCE NUMBERS

1

contraption

2

container

4

solids

6

cover

8th

opening

10

Pressure wave generator

12

electrodes

14

Electric conductors

16

voltage source

18

switching element

20

control unit

22

display element

24

Electric arc

26

pressure waves

28

top

30

bottom

32

conductor element

34

contact element

36

Electrical supply

38

Electrically insulating material

40

connecting element

Claims (10)

Device (1) for comminuting solids (4), wherein the device (1)
a container (2) for receiving the solids (4),
a voltage source (16) for generating an electrical voltage and
a pressure wave generator (10), the
via two electrical conductors (14) to the voltage source (16) is connected, and
is arranged to generate pressure waves (26) in a liquid which is located in the container (2),
characterized in that the electrical conductors (14)
are plate-shaped,
each have an upper side (28) and one of the upper side (28) opposite underside (30) and
are arranged so that the upper side (28) of an electrical conductor (14) faces the underside (30) of the other electrical conductor (14). Device (1) according to claim 1, characterized in that the pressure wave generator (10) has two protruding into the liquid electrode (12). Device (1) according to claim 1 or 2, characterized in that the two electrical conductors (14) extend parallel to one another. Device (1) according to claim 1, 2 or 3, characterized in that the two electrical conductors (14) are sheathed in particular in an electrically insulating material. Device (1) according to claim 4, characterized in that the electrical conductors (14) are cast in the electrically insulating material. Device (1) according to claim 4 or 5, characterized in that the electrically insulating material is a ceramic material, a glass fiber reinforced plastic or an epoxy resin. Device (1) according to one of the preceding claims, characterized in that the pressure wave generator (10) by a switching element (18) is switchable, which is designed as a thyratron. Device (1) according to one of claims 2 to 7, characterized in that a distance of the two electrodes (12) from each other is preferably infinitely adjustable. Device (1) according to one of claims 2 to 8, characterized in that a position of the electrodes (12) in the container (2) is adjustable. Device (1) according to one of the preceding claims, characterized in that the pressure wave generator (10) comprises a pulsed laser.

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