EP2368638A1 - Method and device for cold milling - Google Patents

Method and device for cold milling Download PDF

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Publication number
EP2368638A1
EP2368638A1 EP11159022A EP11159022A EP2368638A1 EP 2368638 A1 EP2368638 A1 EP 2368638A1 EP 11159022 A EP11159022 A EP 11159022A EP 11159022 A EP11159022 A EP 11159022A EP 2368638 A1 EP2368638 A1 EP 2368638A1
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EP
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Prior art keywords
grinder
refrigerant
cryogenic refrigerant
temperature
grinding
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EP11159022A
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German (de)
French (fr)
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EP2368638B1 (en
Inventor
Oliver Dietrich
Thomas Böckler
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Messer Group GmbH
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Messer Group GmbH
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Priority to PL11159022T priority Critical patent/PL2368638T3/en
Priority to RS20190281A priority patent/RS58531B1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C19/00—Other disintegrating devices or methods
    • B02C19/18—Use of auxiliary physical effects, e.g. ultrasonics, irradiation, for disintegrating
    • B02C19/186—Use of cold or heat for disintegrating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
    • B02C23/18—Adding fluid, other than for crushing or disintegrating by fluid energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C2201/00—Codes relating to disintegrating devices adapted for specific materials
    • B02C2201/04—Codes relating to disintegrating devices adapted for specific materials for used tyres

Definitions

  • the invention relates to a method for cold milling, in which a feed material is ground in a grinder and cooled before or during the milling process with a liquid cryogenic refrigerant.
  • the invention further relates to a corresponding device.
  • Particularly difficult to grind products are materials with rubber-elastic, viscoelastic or plastic properties and / or materials that have a high agglomeration readiness of the ground particles for various reasons, such as engineering plastics, waxes, pharmaceuticals or certain natural products. Since the properties mentioned hinder reliable comminution, these materials are embrittled during the so-called cold grinding before the grinding process, for example in a vortex screw cooler by means of a cryogenic refrigerant and then metered fed to the mill. The problem with this is that during the grinding process heat is introduced to a considerable extent in the cold millbase. This makes the more noticeable the smaller the particle size. Namely, the smaller the particles are, the higher the mass-specific energy expenditure required for the grinding.
  • cooling of the feedstock by means of a cryogenic refrigerant present in the liquid state is much more advantageous.
  • the liquid nitrogen is used as the refrigerant is, for example, from DE 10 2007 051 548 A1 known.
  • the heat transfer is in this case so good that within the particles ofoptionguts a large temperature difference between the rapidly cooled outer surface and the still-warm core occurs, which in turn favors the comminution of the particles.
  • this method is particularly suitable to realize even when grinding plastic, viscoelastic and rubber-elastic materials easily particle sizes of less than 10 microns, especially 1 to 3 microns, with the addition of additives (substances that re-agglomeration of the ground Avoiding ponds following the grinding process) can be dispensed with.
  • additives substances that re-agglomeration of the ground Avoiding ponds following the grinding process
  • cryogenic liquefied refrigerant is passed with boiling temperature through the appropriate supply lines. A portion of the refrigerant will therefore evaporate due to the unavoidable heat input through the walls of the leads already in the feed to the grinder and thus affect the cooling effect.
  • the object of the present invention is therefore to provide a method and a device for cold grinding of grinding stock with the aid of a liquefied cryogenic refrigerant, which enables reliable control of the cooling and is also economical and efficient in use.
  • the liquid cryogenic refrigerant (the terms “liquid” and “liquefied” cryogenic refrigerant are used below) is subcooled during its supply to the grinder, ie brought to a temperature below its boiling point
  • the reduced evolution of gas within the supply line leads to a uniform flow of refrigerant into the grinder, which can be well regulated Cryogenic refrigerants are also still in the supercooled state within the grinder, as a result of which the feed material is in contact with the liquefied cryogenic refrigerant for a longer period of time
  • Refrigerant has a temperature well below the boiling temperature at the respective pressure conditions in the supply line.
  • the supercooling takes place, for example, by thermal contact with a refrigerant corresponding to lower temperature.
  • a mill with grinding media is used, in which the millbase is placed with the grinding media in a grinding container and grated against each other and against the container wall under the movement of the grinding media.
  • mills are ball, rod, vibratory, agitator, Rhackskskugel- or planetary mills.
  • impact mills such as hammer, pin, universal and air jet mills, as well as friction mills, such as rotor and long-gap mills, and granulators are used.
  • the direct contact of the feed with the liquefied cryogenic refrigerant allows a very good heat transfer from the feed to the refrigerant.
  • the at least predominantly registered in the solid or liquid state refrigerant vaporizes upon thermal contact with the feed material or the grinding media and is then removed or used to cool a grinding unit downstream classification unit, such as a filter or a classifier to re-agglomeration in the Classification to stop.
  • a grinding unit downstream classification unit such as a filter or a classifier to re-agglomeration in the Classification to stop.
  • An advantageous development of the invention provides that the flow rate and / or the temperature of the cryogenic refrigerant to be supplied to the grinder as a function of one or more measured in the grinder parameter (s), in particular the temperature of the grind, is regulated , Even with a low flow rate, the heat input via the walls of the supply line can be easily compensated and / or ensured in this way by a correspondingly higher subcooling, that the refrigerant is introduced in the still supercooled state in the grinder and / or one of the grinder upstream cooling device.
  • the temperature difference, by which the refrigerant, which was previously at its boiling point, is cooled, is calculated according to the requirement that cryogenic refrigerants, when supplied to the grinder or pre-cooler preceded by the grinder, are at least substantially in the liquid state and / or still in the supercooled state is entered in the grinder or the pre-cooler. Therefore, the temperature difference to the boiling point after the supercooling is preferably at least 2K, preferably at least 5K, particularly preferably at least 10K.
  • the preferred cryogenic refrigerant used is liquid nitrogen.
  • the supercooling is carried out, for example, by thermal contact with a cryogenic refrigerant having a lower boiling point, for example, with a bath of liquid nitrogen, in which a low temperature is achieved by lowering the pressure.
  • a nitrogen bath is provided in which a pressure of 1000 mbar, which sets a temperature of 77 K in the nitrogen bath; a pressure reduction of the nitrogen bath to 100 to 200 mbar even leads to a cooling to 60 K to 66 K.
  • the brought into thermal contact with this nitrogen bath liquid nitrogen in the supply line can be easily cooled to a temperature of for example 78 K to 80 K.
  • the object of the invention is also achieved by a device for finely grinding ground material, which is equipped with a grinder, a task unit for supplying the feed to the grinder and a supply line for a liquefied cryogenic refrigerant, and which is characterized in that the supply line means for subcooling the liquefied cryogenic refrigerant flowing through the supply line.
  • the means for supercooling prevents the occurrence of boiling gas bubbles in the supply line due to the unavoidable heat input even with well-insulated pipes and thus stabilizes the inflow of the liquefied cryogenic refrigerant to the grinder.
  • the supply line preferably leads into the grinding device and / or into a cooling device connected upstream of the grinding device;
  • the liquefied cryogenic refrigerant thus serves both for pre-cooling of the feedstock and for cooling during the milling process.
  • the only drawing ( Fig. 1 ) shows a schematic view of a device according to the invention for cold grinding.
  • the device 1 illustrated in the drawing comprises a grinder 2 and a cooling unit 3 arranged upstream of the grinder 2.
  • the grinder 2 is, for example, an impact mill, in which the feed material inside a grinding container 2 is comminuted by means of rotating pin disks.
  • the cooling unit 3 comprises, for example, a vortex worm cooler, in the input via a feed hopper 4 feed material is brought into direct contact with a liquefied cryogenic refrigerant.
  • the device 1 comprises a tank 5 for a cryogenic liquefied cryogenic refrigerant.
  • a cryogenic liquefied cryogenic refrigerant As "liquefied cold-liquefied” here is understood a gas whose liquid state is maintained by that its storage temperature is maintained by technical measures such as cooling and / or insulation.
  • the tank 5 is fluidly connected via a thermally insulated supply line 6 to the cooling unit 3; another, also thermally insulated supply line 8 at a branch 7 from the supply line 6 establishes a flow connection between the tank 5 and the grinder 2 forth.
  • the presence of both leads 6,8 is by no means required within the scope of the invention; he can also be a supply of the cryogenic liquefied refrigerant either in the cooling unit 3 or in the grinder 2 done.
  • the supply of liquefied cryogenic refrigerant from the tank 5 to the cooling unit 3 or the grinding device 2 can be controlled by operating quantity control valves 9, 10.
  • a gas-tight metering unit 12 is arranged.
  • Another gas-tight material lock 13 is located at the outlet of the grinder 2.
  • evaporated cryogenic refrigerant is removed via a gas discharge line 14.
  • a device 15 for subcooling the liquefied cryogenic refrigerant is arranged.
  • the device 15 is, for example, a chiller or a heat exchanger.
  • the device 15 comprises a bath of the same refrigerant as that stored in the tank 5, but whose temperature has been lowered by lowering the pressure and is thus able to cool the refrigerant passed through the supply line 6 to a temperature below its boiling point.
  • a computer unit 16 is connected to sensors, not shown here, for example, the temperature in the grinder 2 inside the grinder 2 and with the flow control valves 9, 10, the metering unit 12, the material lock 13 and the device 15 in data communication.
  • the feed material is fed via the feed hopper 4 of the cooling unit 3 and brought there in direct contact with the supplied via feed line 6 liquefied cryogenic refrigerant.
  • Refrigerant in the cooling unit 3 is at least partially still in the liquefied state, there is a particularly good heat transfer from the feed to the refrigerant.
  • the refrigerant evaporated in the cooling process is removed via the gas discharge line 14.
  • the pre-cooled feed then passes into the grinder 2 and is ground there.
  • Refrigerant can also be supplied via the supply line 7 in order to dissipate the process heat arising during the grinding and to keep the millbase at a low temperature during the grinding.
  • the ground material is then removed via the material lock 13 from the device 1 and, for example, filled into a transport container, not shown here.
  • the control of the inflow of refrigerant is carried out by means of the computer unit 16.
  • one or more parameters in the grinder are detected continuously or at predetermined intervals, for example, the temperature in the grinder 2 or the grain size of the milled Guts. From this, according to a predetermined program, a value for the influx of refrigerant through the supply lines 6 and / or 7 is calculated and the mass flow valves 9, 10 are controlled accordingly. For example, if the temperature in the grinder 2 drops below a predetermined value, the flow control valves 9, 10 are throttled or completely closed.
  • the refrigerant is subcooled by means of the device 15, ie to one Temperature is at least 2 to 10 K below its boiling point.
  • the refrigerant reaches the cooling unit 3 or the grinder 2 at least substantially in the liquid state.
  • the refrigerant may initially be in the supercooled state, with the result that the refrigerant is in the cooling process for a longer period of time in the liquid state and thus a very efficient cooling of the ground material to, for example, 120 to 100 K or less effected.
  • the regrind even with chemically active substances or substances with plastic or elastic properties, can be reliably ground to particle sizes below 500 microns.
  • the subcooling by means of the computer unit 16 is controlled and the temperature of the refrigerant in the supply line 6,7 in a wide range, for example, be varied to values between 80 K and 92 K. In this way, the grinder 2 or the cooling unit 3 is not supplied with superfluous gas even with different flow rates of supplied refrigerant.
  • the power consumption of the device 1 is lowered overall and the Mahlgut micsatz antique is increased.
  • the temperature of the liquid nitrogen in the supply line is lowered to a value of, for example, about 85 K.
  • the liquid nitrogen additionally reaches the cooling unit 3 or at a temperature of approximately 87 K, ie significantly below its boiling point of the grinder 2.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Disintegrating Or Milling (AREA)

Abstract

The method involves milling the feedstock in a milling unit (2) and cooling the feedstock with a liquid cryogenic cooling agent before or during the milling process. The liquid cryogenic cooling agent is undercooled to a temperature below its boiling point before its delivery to the milling unit. The liquid nitrogen is used as a cryogenic cooling agent. An independent claim is also included for a device for fine milling of the mill material.

Description

Die Erfindung betrifft ein Verfahren zum Kaltmahlen, bei dem ein Aufgabegut in einer Mahleinrichtung gemahlen und vor oder während des Mahlvorgangs mit einem flüssigen kryogenen Kältemittel gekühlt wird. Die Erfindung betrifft ferner eine entsprechende Vorrichtung.The invention relates to a method for cold milling, in which a feed material is ground in a grinder and cooled before or during the milling process with a liquid cryogenic refrigerant. The invention further relates to a corresponding device.

Als besonders schwer mahlbare Produkte gelten Materialien mit gummielastischen, viskoelastischen oder plastischen Eigenschaften und/oder Materialien, die aus unterschiedlichen Gründen eine hohen Agglomerationsbereitschaft der gemahlenen Partikel aufweisen, wie technische Kunststoffe, Wachse, Pharmazeutika oder bestimmte Naturstoffe. Da die genannten Eigenschaften eine zuverlässige Zerkleinerung behindern, werden diese Materialen beim so genannten Kaltmahlen vor dem Mahlvorgang beispielsweise in einem Wirbelschneckenkühler mittels eines kryogenen Kältemittels versprödet und anschließend dosiert der Mühle zugeführt. Problematisch dabei ist, dass beim Mahlvorgang Wärme im beträchtlichen Umfang in das kalte Mahlgut eingetragen wird. Dies macht sich umso stärker bemerkbar, je geringer die Teilchengröße ist. Je kleiner nämlich die Partikel sind, desto höher ist der massenspezifische Energieaufwand, der für die Mahlung erforderlich ist. Unterhalb einer - materialabhängigen - Teilchengröße von wenigen Mikrometern neigen die bereits gemahlenen Partikel dazu, sich zu neuen Agglomeraten zusammenfügen. Die beim Mahlen auftretenden hohen Temperaturen können so zu einem Zusammensintern der Teilchen führen mit der Folge, dass die Agglomerate eine vergleichbare Festigkeit zum ursprünglichen Aufgabegut aufweisen. In der DE 2 516 764 A1 wird daher eine Mahlgutkühlung beschrieben, bei der das Mahlgut auch in der Mühle selbst mit einem Kaltgasstrom, beispielsweise einem Strom aus kaltem Stickstoffgas, beaufschlagt wird. Problematisch bei derartigen Kühlverfahren, die mit Gas als Kältemittel arbeiten ist jedoch, dass zwischen dem Aufgabegut und dem gasförmigen Kältemittel nur eine sehr schlechte Wärmeübertragung erfolgt, was zur Folge hat, dass eine große Menge an gasförmigem Kältemittel zur Verfügung gestellt werden muss.Particularly difficult to grind products are materials with rubber-elastic, viscoelastic or plastic properties and / or materials that have a high agglomeration readiness of the ground particles for various reasons, such as engineering plastics, waxes, pharmaceuticals or certain natural products. Since the properties mentioned hinder reliable comminution, these materials are embrittled during the so-called cold grinding before the grinding process, for example in a vortex screw cooler by means of a cryogenic refrigerant and then metered fed to the mill. The problem with this is that during the grinding process heat is introduced to a considerable extent in the cold millbase. This makes the more noticeable the smaller the particle size. Namely, the smaller the particles are, the higher the mass-specific energy expenditure required for the grinding. Below a material-dependent particle size of a few micrometers, the already ground particles tend to combine to form new agglomerates. The high temperatures occurring during grinding can thus lead to sintering together of the particles with the result that the agglomerates have a comparable strength to the original feedstock. In the DE 2 516 764 A1 Therefore, a Mahlgutkühlung is described, in which the millbase itself in the mill with a cold gas stream, for example, a stream of cold nitrogen gas, is applied. However, a problem with such cooling methods using gas as the refrigerant is that only very poor heat transfer takes place between the feedstock and the gaseous refrigerant, with the result that a large amount of gaseous refrigerant must be made available.

Im Hinblick auf die Wärmeleitung weitaus vorteilhafter gestaltet sich eine Kühlung des Aufgabeguts mittels eines im flüssigen Zustand vorliegenden kryogenen Kältemittels. Ein derartiges Verfahren, bei dem insbesondere flüssiger Stickstoff als Kältemittel zum Einsatz kommt, ist beispielsweise aus der DE 10 2007 051 548 A1 bekannt. Die Wärmeübertragung ist hierbei so gut, dass innerhalb der Teilchen des Aufgabeguts eine große Temperaturdifferenz zwischen der schnell abgekühlten Außenoberfläche und dem noch warmen Kern auftritt, die wiederum die Zerkleinerung der Teilchen begünstigt. Aus diesem Grunde ist dieses Verfahren besonders geeignet, um auch beim Mahlen von plastischen, viskoelastischen und gummielastischen Werkstoffen problemlos Korngrößen von unter 10 µm, insbesondere 1 bis 3 µm realisieren, wobei auf die Zugabe von Additiven (Substanzen, die eine Re-Agglomeration der gemahlenen Teichen im Anschluss an den Mahlprozess verhindern sollen) verzichtet werden kann. Problematisch dabei ist jedoch, dass tiefkalt verflüssigtes Kältemittel mit Siedetemperatur durch die entsprechenden Zuleitungen geführt wird. Ein Teil des Kältemittels wird daher durch den unvermeidlichen Wärmeeintrag über die Wände der Zuleitungen bereits bei der Zuführung zur Mahleinrichtung verdampfen und somit die Kühlwirkung beeinträchtigen. Insbesondere dann, wenn die Zuführung des Kältemittels mittels eines Ventils geregelt wird, das im Rahmen der Regelung für eine gewisse Zeit die Zuführung des Kältemittels vollständig unterbindet, bildet sich stromauf zum Ventil eine Gasblase in der Zuleitung aus, die auch nach vollständigem Öffnen des Ventils für eine gewisse Zeitdauer eine nur unzureichende Kühlung des Aufgabeguts bewirkt. Infolge der Unkenntnis über die tatsächliche Größe der Gasblase kann es dadurch zu einem Überschwingen des Regelkreises bis hin zu einer positiven Rückkopplung kommen, wodurch eine Regelung des Systems gänzlich verunmöglicht wird.With regard to the heat conduction, cooling of the feedstock by means of a cryogenic refrigerant present in the liquid state is much more advantageous. Such a method, in particular, the liquid nitrogen is used as the refrigerant is, for example, from DE 10 2007 051 548 A1 known. The heat transfer is in this case so good that within the particles of Aufgabeguts a large temperature difference between the rapidly cooled outer surface and the still-warm core occurs, which in turn favors the comminution of the particles. For this reason, this method is particularly suitable to realize even when grinding plastic, viscoelastic and rubber-elastic materials easily particle sizes of less than 10 microns, especially 1 to 3 microns, with the addition of additives (substances that re-agglomeration of the ground Avoiding ponds following the grinding process) can be dispensed with. The problem here is that cryogenic liquefied refrigerant is passed with boiling temperature through the appropriate supply lines. A portion of the refrigerant will therefore evaporate due to the unavoidable heat input through the walls of the leads already in the feed to the grinder and thus affect the cooling effect. In particular, when the supply of the refrigerant is controlled by means of a valve which completely suppresses the supply of the refrigerant for a certain time, forms upstream of the valve, a gas bubble in the supply line, which also after complete opening of the valve for a certain amount of time causes only insufficient cooling of the feed. As a result of ignorance of the actual size of the gas bubble, this can lead to an overshoot of the control loop to a positive feedback, whereby a regulation of the system is completely impossible.

Aufgabe der vorliegenden Erfindung ist daher, ein Verfahren sowie eine Vorrichtung zum Kaltmahlen von Mahlgut unter Zuhilfenahme eines verflüssigten kryogenen Kältemittels zu schaffen, das eine zuverlässige Regelung der Kühlung ermöglicht und darüber hinaus sparsam und effizient im Einsatz ist.The object of the present invention is therefore to provide a method and a device for cold grinding of grinding stock with the aid of a liquefied cryogenic refrigerant, which enables reliable control of the cooling and is also economical and efficient in use.

Gelöst ist diese Aufgabe bei einem Verfahren der eingangs genannten Art dadurch, dass das kryogene Kältemittel vor seiner Zuführung an die Mahleinrichtung auf eine Temperatur unter seinen Siedepunkt unterkühlt wird.This problem is solved in a method of the type mentioned above in that the cryogenic refrigerant is subcooled to a temperature below its boiling point before it is fed to the grinder.

Erfindungsgemäß wird also das flüssige kryogene Kältemittel (die Ausdrücke "flüssiges" und "verflüssigtes" kryogenes Kältemittel" werden im Folgenden synonym gebraucht) während seiner Zuführung zur Mahleinrichtung unterkühlt, also auf eine Temperatur unterhalb seiner Siedetemperatur gebracht. Durch die Unterkühlung wird Kältemittel, das bereits in die Gasphase übergegangen ist, wieder verflüssigt und das Kältemittel gelangt zumindest weitgehend im verflüssigtem Zustand in die Mahleinrichtung. Die verringerte Gasentwicklung innerhalb der Zuleitung führt zu einem gleichmäßigen Zustrom an Kältemittel in die Mahleinrichtung, der gut geregelt werden kann. Zudem befindet sich bevorzugt das verflüssigte kryogene Kältemittel auch innerhalb der Mahleinrichtung noch im unterkühlten Zustand, wodurch das Aufgabegut länger mit dem verflüssigten kryogenen Kältemittel in Kontakt steht. Als "unterkühlt" soll hier ein Zustand bezeichnet werden, bei dem das flüssige kryogene Kältemittel eine Temperatur deutlich unterhalb der Siedetemperatur bei den jeweiligen Druckverhältnissen in der Zuleitung aufweist. Die Unterkühlung erfolgt dabei beispielsweise durch thermischen Kontakt mit einem Kälteträger entsprechend niedrigerer Temperatur.According to the invention, therefore, the liquid cryogenic refrigerant (the terms "liquid" and "liquefied" cryogenic refrigerant are used below) is subcooled during its supply to the grinder, ie brought to a temperature below its boiling point The reduced evolution of gas within the supply line leads to a uniform flow of refrigerant into the grinder, which can be well regulated Cryogenic refrigerants are also still in the supercooled state within the grinder, as a result of which the feed material is in contact with the liquefied cryogenic refrigerant for a longer period of time Refrigerant has a temperature well below the boiling temperature at the respective pressure conditions in the supply line. The supercooling takes place, for example, by thermal contact with a refrigerant corresponding to lower temperature.

Als Mühle kommt beispielsweise eine Mühle mit Mahlkörpern zum Einsatz, bei der das Mahlgut mit den Mahlkörpern in einen Mahlbehälter gegeben und unter der Bewegung der Mahlkörper gegeneinander sowie gegen die Behälterwand zerrieben wird. Beispiele für derartige Mühlen sind Kugel-, Stab-, Schwing-, Rührwerk-, Rührwerkskugel- oder Planetenmühlen. Darüber hinaus kommen Prallmühlen, wie zum Beispiel Hammer-, Stift-, Universal- und Luftstrahlmühlen, sowie Friktionsmühlen, wie Rotor- und Langspaltmühlen, und Schneidmühlen zum Einsatz. Der direkte Kontakt des Aufgabeguts mit dem verflüssigten kryogenen Kältemittel ermöglicht eine sehr gute Wärmeübertragung vom Aufgabegut auf das Kältemittel. Der insbesondere bei Mahlgut mit elastischen oder plastischen Eigenschaften hochproblematische Wärmeeintrag durch das Mahlen wird also während des Mahlvorgangs laufend kompensiert und kann somit gut kontrolliert werden. Der direkte Kontakt des Aufgabeguts mit dem flüssigen kryogenen Kältemittel im Mahlbehälter und/oder im Produktkühler führt zu einer sehr raschen Kühlung des Aufgabeguts. Die dadurch hervorgerufenen inneren Spannungen mindern die Festigkeit der Aufgabeteilchen und begünstigen dadurch wiederum den Zerkleinerungsprozess. Beim erfindungsgemäßen Verfahren lassen sich mit einem verhältnismäßig geringen apparativen Aufwand auch beim Mahlen von plastischern, viskoelastischen und gummielastischen Werkstoffen problemlos Korngrößen von unter 500 µm erreichen. Das zumindest überwiegend im festen oder flüssigen Zustand eingetragene Kältemittel verdampft beim thermischen Kontakt mit dem Aufgabegut bzw. dem Mahlkörpern und wird anschließend abgeführt oder zur Kühlung einer dem Mahlbehälter nachgeordneten Klassierungseinheit, etwa ein Filter oder ein Sichter, eingesetzt, um eine Re-Agglomeration bei der Klassierung zu unterbinden.As a mill, for example, a mill with grinding media is used, in which the millbase is placed with the grinding media in a grinding container and grated against each other and against the container wall under the movement of the grinding media. Examples of such mills are ball, rod, vibratory, agitator, Rührskskugel- or planetary mills. In addition, impact mills, such as hammer, pin, universal and air jet mills, as well as friction mills, such as rotor and long-gap mills, and granulators are used. The direct contact of the feed with the liquefied cryogenic refrigerant allows a very good heat transfer from the feed to the refrigerant. The highly problematic heat input due to milling, in particular in the case of ground material having elastic or plastic properties, is thus continuously compensated during the grinding process and can thus be well controlled. The direct contact of the feed with the liquid cryogenic refrigerant in the grinding container and / or in the product cooler leads to a very rapid cooling of the feed. The resulting internal stresses reduce the strength of the Aufgabeteilchen and thereby in turn favor the crushing process. In the method according to the invention can be with a relative Low equipment cost even when grinding plastischern, viscoelastic and rubber-elastic materials easily reach particle sizes of less than 500 microns. The at least predominantly registered in the solid or liquid state refrigerant vaporizes upon thermal contact with the feed material or the grinding media and is then removed or used to cool a grinding unit downstream classification unit, such as a filter or a classifier to re-agglomeration in the Classification to stop.

Eine vorteilhafte Weiterbildung der Erfindung sieht vor, dass der Mengenstrom und/oder die Temperatur des der Mahleinrichtung zuzuführenden kryogenen Kältemittels in Abhängigkeit von einem oder in Abhängigkeit von einem oder mehreren in der Mahleinrichtung gemessenen Parameter(n), insbesondere der Temperatur des Mahlguts, geregelt wird. Selbst bei einem geringen Mengenstrom kann auf diese Weise durch eine entsprechend stärkere Unterkühlung der Wärmeeintrag über die Wände der Zuleitung problemlos kompensiert und/oder gewährleistet werden, dass das Kältemittel im noch unterkühlten Zustand in die Mahleinrichtung und/oder einer der Mahleinrichtung vorgeschalteten Kühleinrichtung eingebracht wird.An advantageous development of the invention provides that the flow rate and / or the temperature of the cryogenic refrigerant to be supplied to the grinder as a function of one or more measured in the grinder parameter (s), in particular the temperature of the grind, is regulated , Even with a low flow rate, the heat input via the walls of the supply line can be easily compensated and / or ensured in this way by a correspondingly higher subcooling, that the refrigerant is introduced in the still supercooled state in the grinder and / or one of the grinder upstream cooling device.

Die Temperaturdifferenz, um die das zuvor auf seiner Siedetemperatur vorliegende Kältemittel abgekühlt wird, bemisst sich nach der Forderung, dass kryogene Kältemittel bei seiner Zuführung an die Mahleinrichtung oder einer der Mahleinrichtung vorgeschalteten Vorkühleinrichtung zumindest noch weitgehend im flüssigen Zustand vorliegt und/oder im noch unterkühlten Zustand in die Mahleinrichtung bzw. die Vorkühleinrichtung eingetragen wird. Bevorzugt beträgt daher die Temperaturdifferenz zum Siedepunkt nach der Unterkühlung mindestens 2K, bevorzugt mindestens 5K, besonders bevorzugt mindestens 10K.The temperature difference, by which the refrigerant, which was previously at its boiling point, is cooled, is calculated according to the requirement that cryogenic refrigerants, when supplied to the grinder or pre-cooler preceded by the grinder, are at least substantially in the liquid state and / or still in the supercooled state is entered in the grinder or the pre-cooler. Therefore, the temperature difference to the boiling point after the supercooling is preferably at least 2K, preferably at least 5K, particularly preferably at least 10K.

Als bevorzugtes kryogenes Kältemittel kommt flüssiger Stickstoff zum Einsatz. Die Unterkühlung erfolgt beispielsweise durch thermischen Kontakt mit einem kryogenen Kältemittel, das einen niedrigeren Siedepunkt aufweist, z.B. mit einem Bad aus flüssigem Stickstoff, in dem durch Druckerniedrigung eine tiefe Temperatur erreicht wird. Beispielsweise wird ein Stickstoffbad bereitgestellt, in dem ein Druck von 1000 mbar aufrecht erhalten wird, wodurch sich in dem Stickstoffbad eine Temperatur von 77 K einstellt; eine Druckerniedrigung des Stickstoffbads auf 100 bis 200 mbar führt gar zu einer Abkühlung auf 60 K bis 66 K. Der mit diesem Stickstoffbad in thermischen Kontakt gebrachte flüssige Stickstoff in der Zuleitung kann so problemlos auf eine Temperatur von beispielsweise 78 K bis 80 K gekühlt werden.The preferred cryogenic refrigerant used is liquid nitrogen. The supercooling is carried out, for example, by thermal contact with a cryogenic refrigerant having a lower boiling point, for example, with a bath of liquid nitrogen, in which a low temperature is achieved by lowering the pressure. For example, a nitrogen bath is provided in which a pressure of 1000 mbar, which sets a temperature of 77 K in the nitrogen bath; a pressure reduction of the nitrogen bath to 100 to 200 mbar even leads to a cooling to 60 K to 66 K. The brought into thermal contact with this nitrogen bath liquid nitrogen in the supply line can be easily cooled to a temperature of for example 78 K to 80 K.

Die Aufgabe der Erfindung wird auch durch eine Vorrichtung zum Feinmahlen von Mahlgut gelöst, die mit einer Mahleinrichtung, einer Aufgabeeinheit zum Zuführen des Aufgabeguts zur Mahleinrichtung und einer Zuführleitung für ein verflüssigtes kryogenes Kältemittel ausgerüstet ist, und die dadurch gekennzeichnet ist, dass der Zuführleitung eine Einrichtung zum Unterkühlen des durch die Zuführleitung strömenden verflüssigten kryogenen Kältemittels zugeordnet ist. Die Einrichtung zum Unterkühlen verhindert das Auftreten von Siedegasblasen in der Zuleitung aufgrund des selbst bei gut isolierten Leitungen unvermeidlichen Wärmeeintrags und verstetigt damit den Zustrom des verflüssigten kryogenen Kältemittels an die Mahleinrichtung.The object of the invention is also achieved by a device for finely grinding ground material, which is equipped with a grinder, a task unit for supplying the feed to the grinder and a supply line for a liquefied cryogenic refrigerant, and which is characterized in that the supply line means for subcooling the liquefied cryogenic refrigerant flowing through the supply line. The means for supercooling prevents the occurrence of boiling gas bubbles in the supply line due to the unavoidable heat input even with well-insulated pipes and thus stabilizes the inflow of the liquefied cryogenic refrigerant to the grinder.

Bevorzugt mündet dabei die Zuführleitung in die Mahleinrichtung und/oder in eine der Mahleinrichtung vorgeschaltete Kühleinrichtung ein; in diesem Falle dient das verflüssigte kryogene Kältemittel also sowohl zur Vorkühlung des Aufgabeguts als auch zum Kühlen während des Mahlprozesses.In this case, the supply line preferably leads into the grinding device and / or into a cooling device connected upstream of the grinding device; In this case, the liquefied cryogenic refrigerant thus serves both for pre-cooling of the feedstock and for cooling during the milling process.

Anhand der Zeichnung soll nachfolgend ein Ausführungsbeispiel der Erfindung näher erläutert werden.Reference to the drawing, an embodiment of the invention will be explained in more detail below.

Die einzige Zeichnung (Fig. 1) zeigt in schematischer Ansicht eine erfindungsgemäße Vorrichtung zum Kaltmahlen.The only drawing ( Fig. 1 ) shows a schematic view of a device according to the invention for cold grinding.

Die in der Zeichnung dargestellte Vorrichtung 1 umfasst eine Mahleinrichtung 2 und eine der Mahleinrichtung 2 vorgeschaltete Kühleinheit 3. Bei der Mahleinrichtung 2 handelt es sich beispielsweise um eine Prallmühle, bei der das Aufgabegut im Innern eines Mahlbehälters 2 mittels rotierender Stiftscheiben zerkleinert werden. Die Kühleinheit 3 umfasst beispielsweise einen Wirbelschneckenkühler, in den das über einen Aufgabetrichter 4 eingegebene Aufgabegut mit einem verflüssigten kryogenen Kältemittel in direkten Kontakt gebracht wird.The device 1 illustrated in the drawing comprises a grinder 2 and a cooling unit 3 arranged upstream of the grinder 2. The grinder 2 is, for example, an impact mill, in which the feed material inside a grinding container 2 is comminuted by means of rotating pin disks. The cooling unit 3 comprises, for example, a vortex worm cooler, in the input via a feed hopper 4 feed material is brought into direct contact with a liquefied cryogenic refrigerant.

Weiterhin umfasst die Vorrichtung 1 einen Tank 5 für ein tiefkalt verflüssigtes kryogenes Kältemittel. Als "tiefkalt verflüssigt" wird hier ein Gas verstanden, dessen flüssiger Zustand dadurch erhalten bleibt, dass seine Lagertemperatur durch technische Maßnahmen wie Kühlung und/oder Isolation gehalten wird. Der Tank 5 ist über eine thermisch isolierte Zuleitung 6 mit der Kühleinheit 3 strömungsverbunden; eine weitere, an einer Abzweigung 7 von der Zuleitung 6 ausgehende ebenfalls thermisch isolierte Zuleitung 8 stellt eine Strömungsverbindung zwischen Tank 5 und der Mahleinrichtung 2 her. Das Vorhandensein beider Zuleitungen 6,8 ist im Rahmen der Erfindung keineswegs erforderlich; er kann auch eine Zuleitung des tiefkalt verflüssigten Kältemittels entweder in die Kühleinheit 3 oder in die Mahleinrichtung 2 erfolgen. Die Zufuhr von verflüssigtem kryogenen Kältemittel aus dem Tank 5 zur Kühleinheit 3 bzw. der Mahleinrichtung 2 kann durch Betätigung von Mengenregelventilen 9, 10 gesteuert werden. Am Eingang der Kühleinheit 3 ist eine gasdichte Dosiereinheit 12 angeordnet. Eine weitere gasdichte Materialschleuse 13 befindet sich am Ausgang der Mahleinrichtung 2. In der Kühleinheit 3 und der Mahleinrichtung 3 verdampftes kryogenes Kältemittel wird über eine Gasableitung 14 abgeführt. In der Zuleitung 6 ist eine Einrichtung 15 zum Unterkühlen des verflüssigten kryogenen Kältemittels angeordnet. Bei der Einrichtung 15 handelt es sich beispielsweise um eine Kältemaschine oder um einen Wärmetauscher. Beispielsweise umfasst die Einrichtung 15 ein Bad des gleichen Kältemittels wie das im Tank 5 gespeicherte, dessen Temperatur jedoch durch Druckerniedrigung herabgesetzt wurde und somit imstande ist, das durch die Zuleitung 6 geführte Kältemittel auf eine Temperatur unterhalb seines Siedepunktes zu kühlen. Eine Rechnereinheit 16 steht mit hier nicht gezeigten, beispielsweise die Temperatur in der Mahleinrichtung 2 detektierenden Sensoren im Innern der Mahleinrichtung 2 sowie mit den Mengenregelventilen 9, 10, der Dosiereinheit 12, der Materialschleuse 13 und der Einrichtung 15 in Datenverbindung.Furthermore, the device 1 comprises a tank 5 for a cryogenic liquefied cryogenic refrigerant. As "liquefied cold-liquefied" here is understood a gas whose liquid state is maintained by that its storage temperature is maintained by technical measures such as cooling and / or insulation. The tank 5 is fluidly connected via a thermally insulated supply line 6 to the cooling unit 3; another, also thermally insulated supply line 8 at a branch 7 from the supply line 6 establishes a flow connection between the tank 5 and the grinder 2 forth. The presence of both leads 6,8 is by no means required within the scope of the invention; he can also be a supply of the cryogenic liquefied refrigerant either in the cooling unit 3 or in the grinder 2 done. The supply of liquefied cryogenic refrigerant from the tank 5 to the cooling unit 3 or the grinding device 2 can be controlled by operating quantity control valves 9, 10. At the entrance of the cooling unit 3, a gas-tight metering unit 12 is arranged. Another gas-tight material lock 13 is located at the outlet of the grinder 2. In the cooling unit 3 and the grinder 3 evaporated cryogenic refrigerant is removed via a gas discharge line 14. In the supply line 6, a device 15 for subcooling the liquefied cryogenic refrigerant is arranged. The device 15 is, for example, a chiller or a heat exchanger. For example, the device 15 comprises a bath of the same refrigerant as that stored in the tank 5, but whose temperature has been lowered by lowering the pressure and is thus able to cool the refrigerant passed through the supply line 6 to a temperature below its boiling point. A computer unit 16 is connected to sensors, not shown here, for example, the temperature in the grinder 2 inside the grinder 2 and with the flow control valves 9, 10, the metering unit 12, the material lock 13 and the device 15 in data communication.

Beim Einsatz der Vorrichtung 1 wird das Aufgabegut über den Aufgabetrichter 4 der Kühleinheit 3 zugeführt und dort in direkten Kontakt mit dem über Zuleitung 6 herangeführten verflüssigten kryogenen Kältemittel gebracht. Dadurch, dass das Kältemittel in der Kühleinheit 3 zumindest teilweise noch im verflüssigten Zustand vorliegt, erfolgt eine besonders gute Wärmeübertragung vom Aufgabegut auf das Kältemittel. Das beim Kühlprozess verdampfte Kältemittel wird über die Gasableitung 14 abgeführt. Das vorgekühlte Aufgabegut gelangt anschließend in die Mahleinrichtung 2 und wird dort gemahlen. Über die Zuleitung 7 kann auch hier Kältemittel zugeführt werden, um die beim Mahlen entstehende Prozesswärme abzuführen und das Mahlgut während des Mahlens auf eine niedrige Temperatur zu halten. Das gemahlene Gut wird anschließend über die Materialschleuse 13 aus der Vorrichtung 1 abgeführt und beispielsweise in einen hier nicht gezeigten Transportbehälter befüllt.When using the device 1, the feed material is fed via the feed hopper 4 of the cooling unit 3 and brought there in direct contact with the supplied via feed line 6 liquefied cryogenic refrigerant. By doing that Refrigerant in the cooling unit 3 is at least partially still in the liquefied state, there is a particularly good heat transfer from the feed to the refrigerant. The refrigerant evaporated in the cooling process is removed via the gas discharge line 14. The pre-cooled feed then passes into the grinder 2 and is ground there. Refrigerant can also be supplied via the supply line 7 in order to dissipate the process heat arising during the grinding and to keep the millbase at a low temperature during the grinding. The ground material is then removed via the material lock 13 from the device 1 and, for example, filled into a transport container, not shown here.

Die Regelung des Zuflusses an Kältemittel erfolgt mittels der Rechnereinheit 16. In der Rechnereinheit 16 wird laufend oder in vorgegebenen Zeitabständen ein oder mehrere Parameter in der Mahleinrichtung erfasst, beispielsweise die Temperatur in der Mahleinrichtung 2 oder die Korngröße des gemahlenen Guts. Hieraus wird nach einem vorgegebenem Programm ein Wert für den Zustrom an Kältemittel durch die Zuleitungen 6 und/oder 7 berechnet und die Mengenstromventile 9, 10 entsprechend angesteuert. Unterschreitet beispielsweise die Temperatur in der Mahleinrichtung 2 einen vorgegebenen Wert, werden die Mengenstromventile 9, 10 gedrosselt oder vollständig geschlossen. Um sicherzustellen, dass das Kältemittel nicht bereits in den Zuleitungen 6,7 teilweise verdampft und im gasförmigen Zustand - und somit für die Wärmeübertragung nachteilig - die Kühleinheit 3 bzw. die Mahleinrichtung 2 erreicht, wird das Kältemittel mittels der Einrichtung 15 unterkühlt, d.h. auf eine Temperatur gebracht, die mindestens 2 bis 10 K unterhalb seiner Siedetemperatur liegt. Dadurch erreicht das Kältemittel die Kühleinheit 3 bzw. die Mahleinrichtung 2 zumindest weitgehend im flüssigen Zustand. Auch innerhalb der Kühleinheit 3 bzw. der Mahleinrichtung 2 kann sich das Kältemittel zunächst noch im unterkühlten Zustand befinden, mit der Folge, dass das Kältemittel beim Kühlprozess für eine längere Zeitdauer im flüssigen Zustand befindet und somit eine sehr effiziente Kühlung des Mahlguts auf beispielsweise 120 bis 100 K oder darunter bewirkt. Aufgrund der starken Kühlung kann das Mahlgut, auch bei chemisch aktiven Stoffen oder Stoffen mit plastischen oder elastischen Eigenschaften, zuverlässig auch auf Korngrößen unterhalb von 500 µm gemahlen werden. Im Ausführungsbeispiel kann auch die Unterkühlung mittels der Rechnereinheit 16 gesteuert und die Temperatur des Kältemittels in den Zuleitung 6,7 in einem weiten Bereich, beispielsweise auf Werte zwischen 80 K und 92 K variiert werden. Auf diese Weise wird die Mahleinrichtung 2 bzw. die Kühleinheit 3 auch bei unterschiedlichen Mengenströmen an zugeführtem Kältemittel nicht mit überflüssigem Gas beaufschlagt. Der Stromverbrauch der Vorrichtung 1 wird insgesamt gesenkt und die Mahlgutdurchsatzleistung wird gesteigert.The control of the inflow of refrigerant is carried out by means of the computer unit 16. In the computer unit 16, one or more parameters in the grinder are detected continuously or at predetermined intervals, for example, the temperature in the grinder 2 or the grain size of the milled Guts. From this, according to a predetermined program, a value for the influx of refrigerant through the supply lines 6 and / or 7 is calculated and the mass flow valves 9, 10 are controlled accordingly. For example, if the temperature in the grinder 2 drops below a predetermined value, the flow control valves 9, 10 are throttled or completely closed. To ensure that the refrigerant is not already partially evaporated in the supply lines 6, 7 and reaches the cooling unit 3 or the grinding device 2 in the gaseous state - and thus disadvantageous for the heat transfer - the refrigerant is subcooled by means of the device 15, ie to one Temperature is at least 2 to 10 K below its boiling point. As a result, the refrigerant reaches the cooling unit 3 or the grinder 2 at least substantially in the liquid state. Even within the cooling unit 3 or the grinding device 2, the refrigerant may initially be in the supercooled state, with the result that the refrigerant is in the cooling process for a longer period of time in the liquid state and thus a very efficient cooling of the ground material to, for example, 120 to 100 K or less effected. Due to the strong cooling, the regrind, even with chemically active substances or substances with plastic or elastic properties, can be reliably ground to particle sizes below 500 microns. In the exemplary embodiment, the subcooling by means of the computer unit 16 is controlled and the temperature of the refrigerant in the supply line 6,7 in a wide range, for example, be varied to values between 80 K and 92 K. In this way, the grinder 2 or the cooling unit 3 is not supplied with superfluous gas even with different flow rates of supplied refrigerant. The power consumption of the device 1 is lowered overall and the Mahlgutdurchsatzleistung is increased.

Beispiel: Im vakuumisolierten Tank 5 werde flüssiger Stickstoff bei einem Tankdruck von ca. 7,8 bar bei Siedetemperatur gelagert. Für den Mahlprozess soll 5 kW Wärmeleistung durch Flüssigstickstoff abgeführt werden, entsprechend einem Flüssigstickstoffbedarf von 55 kg/h. Bei einer Gesamtlänge der vakuumisolierten Zuleitungen 6, 7 von 50 m und einem angenommenen Wärmeeintrag von 1 W/m in die Zuleitungen 6, 7 beträgt der gesamte Wärmeeintrag über die Zuleitung 50 W. Dadurch verdampfen - ohne Unterkühlung - 1,12 kg Stickstoff (entsprechend einem Masseanteil von 2 %) bereits in der Zuleitung, was einem Volumenanteil von ca. 30,5 Vol.-% entspricht. Durch die erfindungsgemäße Unterkühlung mittels der Einrichtung 15 wird die Temperatur des flüssigen Stickstoffs in der Zuleitung auf einen Wert von beispielsweise ca. 85 K gesenkt. Dadurch kann nicht nur die gesamte in die Zuleitungen 6,7 eingetragene Wärme vom flüssigen Stickstoff aufgenommen werden ohne dass dieser verdampft, sondern der flüssige Stickstoff gelangt darüber hinaus mit einer Temperatur von ca. 87 K, also deutlich unter seiner Siedetemperatur, zur Kühleinheit 3 bzw. der Mahleinrichtung 2. Example: In the vacuum-insulated tank 5 liquid nitrogen is stored at a tank pressure of about 7.8 bar at boiling temperature. For the grinding process, 5 kW heat output should be dissipated by liquid nitrogen, corresponding to a liquid nitrogen requirement of 55 kg / h. With a total length of the vacuum-insulated supply lines 6, 7 of 50 m and an assumed heat input of 1 W / m in the supply lines 6, 7, the total heat input through the supply line 50 W. This evaporate - without hypothermia - 1.12 kg of nitrogen (corresponding a mass fraction of 2%) already in the supply line, which corresponds to a volume fraction of about 30.5 vol .-%. Due to the supercooling according to the invention by means of the device 15, the temperature of the liquid nitrogen in the supply line is lowered to a value of, for example, about 85 K. As a result, not only the entire heat introduced into the supply lines 6, 7 can be taken up by the liquid nitrogen without it evaporating, but the liquid nitrogen additionally reaches the cooling unit 3 or at a temperature of approximately 87 K, ie significantly below its boiling point of the grinder 2.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

1.1.
Vorrichtungcontraption
2.Second
Mahleinrichtunggrinder
3.Third
Kühleinheitcooling unit
4.4th
Aufgabetrichterhopper
5.5th
Tanktank
6.6th
Zuleitungsupply
7.7th
Abzweigungdiversion
8.8th.
Zuleitungsupply
9.9th
Mengenregelventil (in Zuleitung 6)Flow control valve (in supply line 6)
10.10th
Mengenregelventil (in Zuleitung 8)Flow control valve (in supply line 8)
11.11th
--
12.12th
Dosiereinheitdosing
13.13th
Materialschleusematerial lock
14.14th
Gasableitunggas discharge
15.15th
Einrichtung zum UnterkühlenDevice for subcooling
16.16th
Rechnereinheitcomputer unit

Claims (6)

Verfahren zum Kaltmahlen, bei dem ein Aufgabegut in einer Mahleinrichtung (2) gemahlen und vor oder während des Mahlvorgangs mit einem flüssigen kryogenen Kältemittel gekühlt wird,
dadurch gekennzeichnet,
dass das flüssige kryogene Kältemittel vor seiner Zuführung an die Mahleinrichtung (2) auf eine Temperatur unterhalb seines Siedepunkt unterkühlt wird.Method for cold milling, in which a feed material is ground in a grinder (2) and cooled before or during the grinding process with a liquid cryogenic refrigerant,
characterized,
that the liquid cryogenic refrigerant is subcooled to a temperature below its boiling point before it is fed to the grinder (2). Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Mengenstrom und/oder die Temperatur des der Mahleinrichtung (2) zuzuführenden kryogenen Kältemittels in Abhängigkeit von einem oder mehreren in der Mahleinrichtung (2) gemessenen Parameter/n, insbesondere der Temperatur des Mahlguts geregelt wird.Method according to one of the preceding claims, characterized in that the flow rate and / or the temperature of the grinder (2) to be supplied cryogenic refrigerant depending on one or more in the grinder (2) measured parameter / n, in particular the temperature of the grind regulated becomes. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das verflüssigte kryogene Kältemittel um eine Temperatur von mindestens 5 K, bevorzugt mindestens 10 K, unterkühlt wird.Method according to one of the preceding claims, characterized in that the liquefied cryogenic refrigerant is undercooled by a temperature of at least 5 K, preferably at least 10 K. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass als kryogenes Kältemittel flüssiger Stickstoff eingesetzt wird.A method according to claim 1 or 2, characterized in that liquid nitrogen is used as the cryogenic refrigerant. Vorrichtung zum Feinmahlen von Mahlgut, mit einer Mahleinrichtung (2), einer Aufgabeeinheit (4) zum Zuführen des Aufgabeguts zur Mahleinrichtung (2) und einer Zuführleitung (6,7) für ein verflüssigtes kryogenes Kältemittel, dadurch gekennzeichnet,
dass der Zuführleitung (6,7) eine Einrichtung (15) zum Unterkühlen des durch die Zuführleitung (6,7) strömenden verflüssigten kryogenen Kältemittels zugeordnet ist.Apparatus for fine grinding of ground material, comprising a grinding device (2), a feed unit (4) for feeding the feed to the grinding device (2) and a feed line (6, 7) for a liquefied cryogenic refrigerant, characterized
in that the feed line (6, 7) is assigned a device (15) for subcooling the liquefied cryogenic refrigerant flowing through the feed line (6, 7). Vorrichtung nach Anspruch 5, dadurch gekennzeichnet, dass die Zuführleitung (6,7) in die Mahleinrichtung (2) und/oder in eine der Mahleinrichtung vorgeschaltete Kühleinrichtung (3) einmündet.Apparatus according to claim 5, characterized in that the feed line (6,7) opens into the grinder (2) and / or in one of the grinder upstream cooling device (3).
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Publication number Priority date Publication date Assignee Title
CN103913027A (en) * 2014-04-11 2014-07-09 莱阳市贵合机械有限公司 Ultrafine grinder liquid nitrogen cooling device
CN107029840A (en) * 2017-03-16 2017-08-11 广州合成材料研究院有限公司 A kind of method of laboratory Freezing smashing
EP3594554A1 (en) 2018-07-11 2020-01-15 Messer Group GmbH Device for supercooling of liquefied gases

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DE2516764A1 (en) 1975-04-16 1976-10-28 Linde Ag COLD GRINDING PROCESS
DE102007051548A1 (en) 2007-10-29 2009-06-18 Siemens Ag Method for measuring cardiac perfusion in a patient and CT system for performing this method

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Publication number Priority date Publication date Assignee Title
CN103913027A (en) * 2014-04-11 2014-07-09 莱阳市贵合机械有限公司 Ultrafine grinder liquid nitrogen cooling device
CN107029840A (en) * 2017-03-16 2017-08-11 广州合成材料研究院有限公司 A kind of method of laboratory Freezing smashing
EP3594554A1 (en) 2018-07-11 2020-01-15 Messer Group GmbH Device for supercooling of liquefied gases
DE102018005503A1 (en) 2018-07-11 2020-01-16 Messer Group Gmbh Device for supercooling liquefied gases

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EP2368638B1 (en) 2018-12-05
HUE042560T2 (en) 2019-07-29

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