DE102008004858A1 - Tempering the nozzle plate of an underwater pelletizer - Google Patents

Abstract

The invention relates to a system for tempering plastic to be extruded into a water chamber of an underwater granulator, comprising a nozzle plate (2) with melt channels (4, 5) penetrating the nozzle plate (2) for the passage of plastic and a cavity (6, 7, 8 ), which is adapted to receive a tempering fluid for tempering the nozzle plate (2). The system comprises a heating device (9, 10) which is set up and arranged at least during operation of the system adjacent to the cavity (6, 7, 8) in order to be heated in the cavity (6, 7, 8) by means of the heating device (9, 10). 8) to temper tempering fluid and at least partially evaporate. Moreover, the invention relates to a system associated nozzle plate (2) and a method for tempering in a water chamber of an underwater granulator to be extruded plastic using the system described. If appropriate, the heating device (9, 10) can also be dispensed with if the heat of the plastic to be extruded is used to evaporate the tempering fluid and is sufficient.

Description

The The invention relates to a nozzle plate and a nozzle plate comprehensive system and a method for controlling the temperature of plastic, through the nozzle plate into a water chamber an underwater pelletizer is extruded. The system or the Nozzle plate comprise a cavity for receiving a tempering for tempering the nozzle plate set is.

At the Operation of an underwater granulator, the plastic in one Melted extruder and through the nozzles one on the Extruder head mounted nozzle plate in one with water flushed through chamber extruded. For the production of granules become the extruded strands through the nozzles directly on the nozzle plate by a rotating knife cut off. This happens underwater in the chamber, causing the granules solidified immediately. However, the nozzle plate is adjacent to the water chamber and is thus also cooled by the water. This unwanted effect has the consequence that the nozzles kicking plastic too cold and can "freeze" in the nozzles. To counteract this effect to act, must the nozzle plate or through the melt channels and nozzles of the nozzle plate passing plastic tempered, in particular heated. This is generally done through a tempering medium, which is passed through the nozzle plate is, or by an electric heating of the nozzle plate.

In the WO 2007/079839 A1 Such a heated nozzle plate is described. The molten plastic is conveyed through melt channels in a plate mounted on the extruder head to the nozzle plate. This plate thus forms a back wall for the nozzle plate. It is interspersed with lines for a temperature control medium. Through an inlet and outlet in the nozzle plate, these lines of the rear wall are connected to corresponding lines in the nozzle plate in order to be able to pass through these lines a liquid or steam-moderate temperature control medium through the nozzle plate. Shut-off valves are mounted outside the rear wall in order to be able to interrupt the flow of the tempering medium when, for example, the nozzle plate is detached from the rear wall for cleaning.

at This arrangement lead the lines for the Temperature control both through the nozzle plate and through the back wall, with the nozzle plate on the extruder head is mounted. Therefore, care must be taken when mounting that seals the connections for the pipes meet each other. Before loosening the nozzle plate the current of the temperature control medium must be interrupted and if necessary Drained still in the nozzle plate existing tempering become.

task The present invention is therefore, the tempering of plastic, passing through a nozzle plate into a water chamber an underwater pelletizer is extruded, easier to design.

These Task is through a system, a nozzle plate and a Process according to the independent claims solved. In dependent claims are advantageous developments and refinements of the invention specified.

One Inventive system for tempering, to be extruded into a water chamber of an underwater granulator Plastic comprises the nozzle plate with the melt channels penetrating it for the passage of plastic and one arranged in this Cavity, for receiving a tempering for tempering the nozzle plate is set up. On the other hand, that includes System also has a heater which is set up and at least during operation of the system adjacent to the cavity is arranged to by means of the heater in the cavity to heat contained tempering fluid and at least partially closed evaporate. In operation, the cavity is thus closed, allowing vaporization of the tempering fluid within the cavity by means of the heater is possible.

Of the Advantage of this arrangement is in the simple heating of the melt channels and nozzles of urgent plastic. The vapor of the tempering fluid passes easily into every corner of the Cavity, even if it has a complicated geometry. Transport steam and liquid flows Heat quickly to the colder places Cavity. There the steam condenses and flows back to a reservoir in the cavity. To the colder areas of the cavity then passes immediately again hot steam and heated this further. By the Condensing the steam and flowing back in the reservoir creates a closed circuit within the Cavity and there is no external treatment of the tempering fluid necessary.

In an advantageous embodiment of the invention, the cavity of the nozzle plate for receiving the tempering medium is formed as a closed within the nozzle plate cavity. As a result, no inlets and outlets for the temperature control through the extruder head or through lying outside of the nozzle plate lines for filling the cavity with tempering fluid are needed. Rather, the tempering fluid is introduced once into the cavity and can then always remain therein. Since the nozzle plate requires no fluid connections, it can gewech without further manipulation or for cleaning and reassembly. A conclusion or opening possibly existing valves is eliminated.

The does not exclude that the nozzle plate a Can have closure, with a filling and discharge opening the cavity is closed, z. For example the case that the tempering must be replaced or the delivery of the nozzle plate takes place without tempering fluid.

The System may include heaters of different arrangement. It is for the heating and evaporation of the tempering fluid required that the heater adjacent at least during operation is arranged to the cavity. If the heater is a part of the system separate from the nozzle plate, d. H. the nozzle plate itself contains no heating device and therefore does not need any connections for it, it can be advantageous in the rear wall, on which the nozzle plate is fixed during operation of the system, be inte grated. It is on it to ensure that the heater is in operation adjacent to the Cavity is arranged in the nozzle plate.

In A particular embodiment of the invention is the heating device formed as an integral part of the nozzle plate. This allows the heater very close to the cavity come close, and thus is a favorable heat transfer between the heater and the tempering allows.

It Different types of heaters can be used become. The use of an electrical resistance heater is advantageous. These comprises in an advantageous embodiment of the invention at least a heating cartridge. This represents a simple and proven option The heating is preferably the heating cartridges in the area the reservoir arranged closer together than otherwise Area of the cavity.

The However, the invention is not based on the use of an electrical resistance heater limited. Also conceivable is an inductive heating device. In this case, a first part of the heating device adjacent to or be located within the cavity and has none direct electrical contact to a power supply. The current is replaced by a second part in the first part instead induced, which is arranged outside the nozzle plate is. This second part can be mounted on the extruder head, for example or part of the rear wall and is with mounted nozzle plate arranged sufficiently close to the part of the heater in the nozzle plate, to achieve the inductive effect.

When another possible embodiment of the heater is a heat exchanger into consideration. It leads a line with a heated tempering fluid in the vicinity the cavity past the nozzle plate and heated thereby the tempering fluid contained in the cavity. Also in this variant can be complicated lines in the nozzle plate be waived.

Especially advantageous is a modified variant, no additional heating required is. Instead, the heating of the tempering takes place alone through the heated plastic in the extruder head. Here to extend a part of the cavity of the nozzle plate - preferably at least the reservoir - to the vicinity of the melt channels the extruder head or the rear wall mounted on the extruder head, to have as long a route as possible the heat is released from the plastic to the tempering fluid can be. The evaporated tempering fluid then heats again the plastic in the remote melt channels and nozzles in the nozzle plate or holds the area encompassing the melt channels and nozzles the nozzle plate to temperature.

Becomes used an electric heater, which is an integral part the nozzle plate is, so is an electrical connection between this heater and an external power supply needed. It is advantageous if the electrical Connection automatically when mounting the nozzle plate the extruder head is made. This can be done by means of a suitable Push or slide connection on the nozzle plate and the rear wall, at which the nozzle plate is fixed, can be realized. There is a power supply line from the back the nozzle plate from the heater in the nozzle plate out. In this way, the power supply of the heater takes place easy and reliable, because the connection is automatic is produced when mounting the nozzle plate.

Around an effective heating of the tempering fluid in the cavity To achieve, it is also advantageous, the heater so to arrange that a part of the cavity to at least extends around a portion of the heater. Particularly advantageous can it should be when the heater is in at least part of the cavity protrudes. As a result, the tempering fluid is in direct contact with the heater, and heating can thus be even more effective respectively.

It is particularly advantageous if the cavity of the nozzle plate is filled with a tempering fluid in such a way that at room temperature there is a liquid phase of the tempering fluid (reservoir) in the cavity. By partially filling at room temperature with liquid tempering fluid is achieved that can form a saturated vapor phase of the tempering when heating. Since the cavity in the nozzle plate can have a complicated geometry, the vaporous phase reaches areas of the cavity which are difficult to access within the nozzle plate more easily and faster than a liquid phase and thus heats the entire cavity uniformly.

Around an evaporation of the tempering fluid even at lower temperatures To reach, it is advantageous if the partially filled with tempering fluid Cavity is at room temperature under reduced pressure. in this respect It is advantageous if the cavity as a closed Cavity is formed in the nozzle plate. Such Nozzle plate can then before even under delivery Vacuum filled with a tempering fluid and sealed become. In operation then arises due to the high operating temperatures by partial evaporation of the tempering a positive pressure in the cavity.

At the Heating the tempering fluid sets a thermodynamic equilibrium one. The heater heats the tempering fluid and evaporates it at least partially. It condenses on the colder Make the inner surfaces of the cavity and collect as a liquid phase. For this purpose, part of the Cavity set up as a reservoir. It is advantageous if the liquid phase of the tempering fluid between 150 ° C. and 330 ° C filling the cavity above 0%. It is particularly advantageous if the liquid phase of Temperingfluids between 150 ° C and 330 ° C the cavity between 40% and 10%. This ensures that that in operation always a liquid and a vapor Phase of the tempering fluid are in the cavity and the vapor phase is thus saturated. from that results in a particularly fast and even Tempering the through the melt channels and nozzles passing plastic. It is for example when cleaning the Nozzle plate also temperatures up to 450 ° C possible.

For example, a mixture of diphenyl and diphenyl ether proves to be a particularly suitable tempering fluid. This thermal treatment is also marketed under the brand Diphyl ^®.

Around to achieve a homogeneous heating of the plastic, is a special embodiment of the cavity of advantage in which the cavity is a relative to the melt channels radially outer region and a rela tive to the Melting channels radially inner region comprises. There the melt channels and the nozzles in the nozzle plate are arranged annularly, the melt channels and nozzles in the nozzle plate so from two sides heated.

Around an even better heating of the melt channels in the nozzle plate and thus to reach the plastic, it can be further advantageous the melt channels through the cavity through to lead. As a result, the melt channels are directly from Surrounding tempering fluid.

At the Heating the tempering fluid in the cavity by means of Heating device arises, as mentioned, in the cavity an overpressure. Too much pressure in the cavity To avoid the nozzle plate, it is advantageous to the cavity to be provided with a pressure relief valve.

following the invention is based on an embodiment below Referring to the accompanying drawings in more detail described. Show it:

1a a nozzle plate fixed to a rear wall with heating means integrated in the nozzle plate (section II in FIG 3 )

1b an enlargement of the threaded plug 1a .

2 the nozzle plate off 1 in another cross section (section II-II in 3 )

3 a section through the nozzle plate 1 and 2 orthogonal to the nozzle direction,

4 a nozzle plate fixed to a rear wall with heater integrated in the rear wall,

5 a fixed to a rear wall nozzle plate without additional heater, and

6 an attached with a back wall nozzle plate with extended cavity.

In 1a is a nozzle plate 2 an underwater pelletizer shown on a back wall 1 is fixed (fasteners not shown). The back wall 1 is in turn mounted on an extruder head. The back wall 1 is with melt channels 3 intersperses the molten plastic from the extruder through melt channels 4 in the nozzle plate 2 to the nozzles 5 conduct. The plastic is then through the nozzles 5 pressed into the water chamber of an underwater granulator, not shown, where the extruded strands are pelletized by means of a rotating knife. As described above, the nozzle plate 2 tempered, in particular heated, since the water in the water chamber, the nozzle plate 2 cools and the plastic in the melt channels 4 and nozzles 5 otherwise it could freeze. For this purpose, the nozzle plate 2 with a cavity 6 . 7 . 8th Mistake. This extends in the embodiment according to 1 relative to the melt channels 4 . 5 both radially outside 6 . 7 as well as radially inside 8th , One in the cavity 6 . 7 . 8th contained tempering fluid is heated cartridges 9 . 10 heated so that it at least partially evaporates. The lower area 7 the cavity 6 . 7 . 8th serves as a reservoir for collecting the condensed tempering fluid.

The filling of the cavity 6 . 7 . 8th carried out in vacuo at room temperature (20 ° C). The tempering fluid is completely degassed, ie this contains no dissolved air. Since the filling takes place in vacuum - below the vapor pressure of the tempering fluid - is after closing the cavity 6 . 7 . 8th already evaporate a part of the tempering. With increasing temperature - during heating - further volume fractions of the tempering fluid will evaporate and the pressure in the cavity 6 . 7 . 8th goes up too. Again, there is a balance between the liquid and vapor phases in the cavity 6 . 7 . 8th one.

The cavity 6 . 7 . 8th is designed so that the vapor arising from the tempering fluid flows in a vacuum against gravity and first all walls of the cavity 6 . 7 . 8th evenly wetted, since the heat flowing out is relatively small - the free surfaces of the nozzle plate 2 are only in contact with the ambient air. Only when the cutting surface of the nozzle plate 2 Water comes, more heat flows out of the nozzle plate 2 The heat flow now causes a very large temperature difference between the cutting surface and the surface of the cavity 6 . 7 . 8th , which is very close to the cutting surface. The heat is transferred from the hot steam to the localized cold surface of the cavity 6 . 7 . 8th transferred, thus also arises within the cavity 6 . 7 . 8th in the steam a temperature difference. The temperature difference in the steam causes a difference in density and thus creates a flow in the steam - towards the cold surfaces. In addition, the vapor on the cold surface cools down to the extent that it condenses and forms liquid on the cold surface. The liquid flows through gravity in the cavity 6 . 7 . 8th down to where the reservoir is 7 located.

Due to the constant heating of the reservoir 7 In turn, the part of the tempering fluid is vaporized, which for maintaining the equilibrium between the vapor and liquid phase in the cavity 6 . 7 . 8th at the appropriate temperature is required.

As the heating cartridges 9 . 10 in the nozzle plate 2 integrated, they are connected by electrical connections 11 . 12 powered on the back (shown schematically). It is a sliding connection, so that the electrical connection in each case automatically when mounting the nozzle plate 2 on the back wall 1 is made by placing contacts on the heating cartridges 9 . 10 on mating contacts of the rear wall 1 come to the plant. The cavity also has a threaded plug 15 , which is a filling and discharge opening of the cavity 6 . 7 . 8th closes. This is how in 1b shown enlarged, sealed accordingly and provided with a pressure relief valve.

The cleaning of the nozzle plate 2 by heating to 450 ° C. In this case, the melt of the plastic decomposes and can be removed mechanically. The tempering fluid is unaffected by this temperature and can be in the cavity 6 . 7 . 8th remain.

2 shows the on the back wall 1 attached nozzle plate 2 out 1 in another cutting plane. It's the connections 13 . 14 between the radially inner part 8th the cavity and the radially outer part 6 the cavity. The trained as a reservoir lower area 7 of the external part 6 the cavity is not visible in this section.

The connections 13 . 14 are also out 3 clear. It concerns with 3 around a section through the nozzle plate 2 the same design as in 1 and 2 orthogonal to the nozzle direction. In addition to the arrangement of the already described elements of the nozzle plate 2 , such as B. the nozzles 5 , is the arrangement of the cavity 6 . 7 . 8th shown more clearly. The lower area 7 the cavity 6 . 7 . 8th forms the reservoir in which this is in the outer part 6 and inner part 8th collects condensed tempering fluid. To ensure effective evaporation of the tempering fluid are at the lower reservoir area 7 the nozzle plate 2 more heating cartridges 10 attached as the rest of the outer part 6 the nozzle plate 2 ,

4 shows another embodiment of the invention. Here, the heater is in the form of heating cartridges 9 . 10 not in the nozzle plate 2 but in the back wall 1 integrated. So that the heating cartridges 9 . 10 anyway in the vicinity of the cavity 6 . 7 rich, are the heating cartridges 9 . 10 in protrusions of the back wall 1 integrated. The nozzle plate 2 has in this case corresponding recesses into which the projections of the rear wall 1 engage in mounting.

5 shows an embodiment of the invention in which no additional heating device is required, but the tempering fluid is evaporated solely by the hot plastic, which passes through the rear wall 1 and the nozzle plate 2 flows. To ensure adequate heating and thus evaporation of the tempering, he the cavity stretches 6 . 7 on the longest possible route along the melt channels 3 in the back wall. The back wall 2 is thicker than usual for this purpose. Because the melt channels 3 mostly in the back wall 1 and the cavity 6 . 7 completely in the nozzle plate 1 are included, the nozzle plate 2 and the back wall 1 designed so that they interlock. Because the cavity 6 . 7 and the melt channels 3 are arranged close to each other on a relatively long distance, heat transfer from the plastic to the Tempe rierfluid is possible. The tempering fluid heated in this way heats the melt channels 4 . 5 which is also adjacent to the cavity 6 . 7 . 8th are arranged.

In 6 another embodiment of the invention is shown. Here includes the cavity 6 . 7 . 8th a larger area of the nozzle plate 2 , The melt channels 4 . 5 lead through the cavity 6 . 7 . 8th through and are so completely surrounded by the tempering fluid. To make the heating even more effective, the heating cartridges protrude 9 . 10 into the cavity 6 . 7 . 8th into it. Due to the direct contact of the melt channels 4 . 5 and the heating cartridges 9 . 10 With the tempering thus a very effective heating is possible.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• WO 2007/079839 A1 [0003]

Claims (42)

A system for tempering plastic to be extruded into a water chamber of an underwater granulator, comprising a nozzle plate ( 2 ) with the nozzle plate ( 2 ) penetrating melt channels ( 4 . 5 ) for the passage of plastic and a cavity ( 6 . 7 . 8th ), for receiving a tempering fluid for tempering the nozzle plate ( 2 ), characterized by a heating device ( 9 . 10 ) which are set up and at least in operation of the system adjacent to the cavity ( 6 . 7 . 8th ) is arranged to be heated by means of the heating device ( 9 . 10 ) in the cavity ( 6 . 7 . 8th ) tempering and at least partially evaporate. System according to claim 1, characterized in that the cavity ( 6 . 7 . 8th ) as one within the nozzle plate ( 2 ) completed cavity is formed. System according to claim 1 or 2, characterized in that the heating device ( 9 . 10 ) is an electric heater. System according to claim 3, characterized in that the heating device ( 9 . 10 ) comprises at least one heating cartridge. System according to claim 4, characterized in that at a first area ( 7 ) of the cavity ( 6 . 7 . 8th ), which in operation of the system, a lower portion of the cavity ( 6 . 7 . 8th ), relatively more heating cartridges are arranged than in a second area ( 6 ) of the cavity ( 6 . 7 . 8th ). System according to one of claims 1 to 5, characterized in that the heating device ( 9 . 10 ) one of the nozzle plate ( 2 ) is a separate part of the system. System according to claim 6, characterized in that the heating device ( 9 . 10 ) in a back wall ( 1 ), on which the nozzle plate ( 2 ) is fixed in the operation of the system is integrated. System according to one of claims 1 to 5, characterized in that the heating device ( 9 . 10 ) Part of the nozzle plate ( 2 ). System according to claim 8, characterized in that the heating device ( 9 . 10 ) in the nozzle plate ( 2 ) a power supply line from a back of the nozzle plate ( 2 ) leads out. System according to claim 8 or 9, characterized by a plug-in or sliding connection ( 11 . 12 ) for automatically establishing an electrical connection between the heating device ( 9 . 10 ) in the nozzle plate ( 2 ) and an external power supply on a rear wall ( 1 ), on which the nozzle plate ( 2 ) is mounted during operation of the system. System according to one of claims 1 to 10, characterized in that a part of the cavity ( 6 . 7 . 8th ) around at least part of the heating device ( 9 . 10 ) extends around. System according to claim 11, characterized in that the heating device ( 9 . 10 ) in at least a part of the cavity ( 6 . 7 . 8th ) protrudes. System according to one of claims 1 to 12, characterized in that a liquid phase of the tempering fluid, the cavity ( 6 . 7 . 8th ) partially filled at room temperature. System according to claim 13, characterized in that the cavity ( 6 . 7 . 8th ) is at room temperature under reduced pressure. System according to claim 13 or 14, characterized in that the liquid phase of the tempering at temperatures between 150 ° C and 330 ° C, the cavity ( 6 . 7 . 8th ) above 0%. System according to claim 15, characterized in that the liquid phase of the tempering at temperatures between 150 ° C and 330 ° C, the cavity ( 6 . 7 . 8th ) between 40% and 10%. System according to one of claims 1 to 16, characterized characterized in that the tempering fluid is a diphenyl / diphenyl ether mixture is. System according to one of claims 1 to 17, characterized in that the cavity ( 6 . 7 . 8th ) both relative to the melt channels ( 4 . 5 ) radially outer part ( 6 . 7 ) as well as relative to the melt channels ( 4 . 5 ) radially inner part ( 8th ). System according to one of claims 1 to 18, characterized in that the melt channels ( 4 . 5 ) through the cavity ( 6 . 7 . 8th ) through it. System according to one of claims 1 to 19, characterized in that the cavity ( 6 . 7 . 8th ) is provided with a pressure relief valve. System according to one of claims 1 to 20, characterized in that the nozzle plate ( 2 ) has a closure with which a filling and discharge opening of the cavity ( 6 . 7 . 8th ) is closable. Nozzle plate with the nozzle plate ( 2 ) penetrating melt channels ( 4 . 5 ) for the passage of plastic and with a cavity ( 6 . 7 . 8th ), for receiving a tempering fluid for tempering the nozzle plate ( 2 ), in particular for A system according to any one of claims 1 to 21, characterized in that the cavity ( 6 . 7 . 8th ) as one within the nozzle plate ( 2 ) Completed cavity is formed. Nozzle plate according to claim 22, characterized in that in the cavity ( 6 . 7 . 8th ) a tempering fluid is contained, the liquid phase of the cavity ( 6 . 7 . 8th ) partially filled at room temperature. Nozzle plate according to claim 23, characterized in that the cavity ( 6 . 7 . 8th ) is at room temperature under reduced pressure. Nozzle plate according to claim 23 or 24, characterized in that a liquid. Phase of the tempering fluid at temperatures between 150 ° C and 330 ° C the cavity ( 6 . 7 . 8th ) above 0%. Nozzle plate according to claim 25, characterized in that the liquid phase of the tempering fluid at temperatures between 150 ° C and 330 ° C, the cavity ( 6 . 7 . 8th ) between 40% and 10%. Nozzle plate according to one of Claims 22 to 26, characterized in that the temperature control fluid used is a diphenyl / diphenyl ether mixture in the cavity ( 6 . 7 . 8th ) is included. Nozzle plate according to one of claims 22 to 27, characterized in that the cavity ( 6 . 7 . 8th ) is provided with a pressure relief valve. Nozzle plate according to one of claims 22 to 28, characterized in that the nozzle plate ( 2 ) has a closure with which a filling and discharge opening of the cavity ( 6 . 7 . 8th ) is closable. Nozzle plate according to one of claims 22 to 29, characterized in that in the nozzle plate ( 2 ) a heating device ( 9 . 10 ) which is set up and adjacent to the cavity ( 6 . 7 . 8th ) is arranged to be heated by means of the heating device ( 9 . 10 ) in the cavity ( 6 . 7 . 8th ) to temper tempering fluid and at least partially evaporate to ver. Nozzle plate according to claim 30, characterized in that the heating device ( 9 . 10 ) is an electric heater. Nozzle plate according to claim 30 to 31, characterized in that the heating device ( 9 . 10 ) comprises at least one heating cartridge. Nozzle plate according to claim 32, characterized in that at a first area ( 7 ) of the cavity ( 6 . 7 . 8th ) are arranged relatively more cartridge heaters than in a second area ( 6 ) of the cavity ( 6 . 7 . 8th ). Nozzle plate according to one of claims 31 to 33, characterized in that the heating device ( 9 . 10 ) in the nozzle plate ( 2 ) a power supply line from a back of the nozzle plate ( 2 ) leads out. Nozzle plate according to one of claims 30 to 34, characterized by a plug-in or sliding connection ( 11 . 12 ) for automatically establishing an electrical connection between the heating device ( 9 . 10 ) in the nozzle plate ( 2 ) and an external power supply on a rear wall ( 1 ), on which the nozzle plate ( 2 ) is mounted during operation of the system. Nozzle plate according to one of claims 30 to 35, characterized in that a part of the cavity ( 6 . 7 . 8th ) around part of the heater ( 9 . 10 ) extends around. Nozzle plate according to claim 36, characterized in that the heating device ( 9 . 10 ) in at least a part of the cavity ( 6 . 7 . 8th ) protrudes. Nozzle plate according to one of claims 22 to 37, characterized in that the cavity ( 6 . 7 . 8th ) one relative to the melt channels ( 4 . 5 ) radially outer part ( 6 . 7 ) and a relative to the melt channels ( 4 . 5 ) radially inner part ( 8th ). Nozzle plate according to one of claims 22 to 38, characterized in that the melt channels ( 4 . 5 ) through the cavity ( 6 . 7 . 8th ) through it. A method for tempering plastic to be extruded into a water chamber of an underwater granulator using a system according to any one of claims 1 to 21 and / or a nozzle plate according to any one of claims 22 to 39, comprising the step of heating one in the cavity ( 6 . 7 . 8th ) Temperierfluids at least until partial evaporation of the tempering. Method according to claim 40, characterized in that that the tempering fluid at a temperature between 150 ° C. and 450 ° C is maintained. Method according to claim 40 or 41, characterized that the evaporation of the tempering by means of heat of the to be extruded plastic without additional heating he follows.