Patent Abstract:
A device for producing granules has a water-cooled granulating mechanism for producing plastics material granules. A discharge line arranged downstream of the granulating mechanism discharges a starting mixture flow and a granule heat exchanger arranged downstream of the discharge line controls the temperature of the mixture containing the plastics material granules and cooling water using parallel fluid passages. The granule heat exchanger has an inlet and an outlet for a transmission heat exchanger medium. A drying mechanism arranged downstream of the granule heat exchanger dries the plastics material granules. The device also may have an energy recovery mechanism arranged downstream of the discharge line for recovering energy from a recovery cooling water flow, containing at least a part of the cooling water of the starting mixture flow. The device uses waste heat, transmitted to the cooling water to increase the performance of the device and improve the energy efficiency thereof.

Full Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of German Patent Application, Serial No. 10 2011 004 429.9, filed Feb. 18, 2011, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to a device for producing granules made of polymeric materials. 
       BACKGROUND OF THE INVENTION 
       [0003]    A device of this type is known from EP 1 522 395 A2, DE 43 37 205 A1, DE 198 24 788 A1 and DE 10 2008 023 046 A. 
       SUMMARY OF THE INVENTION 
       [0004]    An object of the present invention is to use waste heat, which is transmitted in the granulating mechanism to the cooling water, to increase the performance of the device or to improve its energy efficiency. 
         [0005]    This object is achieved according to the invention, in accordance with a first aspect, by a device for producing granules made of polymeric materials with a water-cooled granulating mechanism for producing plastics material granules, with a discharge line arranged downstream of the granulating mechanism for discharging a starting mixture flow containing the plastics material granules and cooling water, with a granule heat exchanger arranged downstream of the discharge line for controlling the temperature of a temperature control mixture flow, containing the plastics material granules and at least a part of the cooling water, wherein the granule heat exchanger has an inlet for a transmission heat exchanger medium and an outlet for a transmission heat exchanger medium, and with a drying mechanism arranged downstream of the granule heat exchanger for drying the plastics material granules, wherein the granule heat exchanger has a plurality of fluid passages running in parallel, in other words not in series, for the temperature mixture flow, and, in accordance with a second aspect, by a device for producing granules made of polymeric materials with a water-cooled granulating mechanism for producing plastics material granules, with a discharge line arranged downstream of the granulating mechanism for discharging a starting mixture flow, containing the plastics material granules and cooling water, and with an energy recovery mechanism, which is arranged downstream of the discharge line, for recovering energy from a recovery cooling water flow, containing at least a part of the cooling water of the starting mixture flow, wherein the energy recovery mechanism comprises at least one ORC circuit for an ORC circuit medium comprising an ORC turbine, an ORC evaporator in the ORC circuit before the ORC turbine, and an ORC condenser in the ORC circuit after the ORC-turbine. 
         [0006]    It was recognized according to the invention that a heat exchanger for controlling the temperature of a plastics material granule/cooling water mixture flow can be used to improve the quality of the granule production process. The granule heat exchanger can cool or heat the temperature control mixture flow. The device can be designed in such a way that the granule heat exchanger can optionally cool or heat in a controlled manner. 
         [0007]    Cooling with the granule heat exchanger can, for example, avoid the formation of vacuoles, as the cooling water can be guided at a higher temperature through the granulating mechanism. This can contribute to a more flexible influencing of a cooling speed and therefore of a shrinking behavior of the granules. A formation of crystalline and amorphous structures in the plastics material granules produced can either be forced in a targeted manner by specifying a cooling speed or else avoided if a structure formation of this type is undesired. By cooling using the granule heat exchanger, a soft plastics material product can be cooled in order to improve its pneumatic conveying behavior during pneumatic conveyance used in the granule conveying path after the device with regard to loss of pressure and with regard to granule abrasion. The heating of the transmission heat carrier medium taking place in the cooling granule heat exchanger can be used to preheat a plastics material powder or plastics material granules, which are fed to an extruder of the granulating mechanism as starting products. The heat transmitted in the cooling granule heat exchanger to the transmission heat carrier medium can be used with the aid of an absorption refrigerating machine to produce cold water. 
         [0008]    If the granule heat exchanger is used to heat the temperature control mixture flow, the latter can be used to degas or deodorize hydrocarbons and residue monomers or other volatile materials. The heating of the plastics material granules can be used to improve or accelerate a degassing, for example of polyolefins such as, for example, PP, HDPE (High Density Polyethylene), LLDPE (Linear Low Density Polyethylene), LDPE (Low Density Polyethylene), LDPE with a vinyl acetate fraction or else other comonomers. The heating of the temperature control mixture flow with the granule heat exchanger can also be used to crystallize PET, in particular in the form of chips. The cooling of the plastics material granules with the granule heat exchanger can be used to heat a downstream hydraulic conveyance of the plastics material granules. The hydraulic medium of the hydraulic conveyance is heated here using the waste heat of the temperature control mixture flow in the granule heat exchanger. Heat losses of the hydraulic conveyance can be compensated by this. 
         [0009]    The granule heat exchanger can be configured as a tube bundle heat exchanger. The tubes of the tube bundle may run straight or else in a U-shape. The tubes may have a typical internal diameter that is 5 to 15 times as large as the typical diameter of the granule grains produced. Tubes with a non-round cross-section may also be used as heat exchanger tubes. The tubes may, for example, have a rectangular cross-section. The granule heat exchanger may also be configured as a plate heat exchanger. An example of a plate heat exchanger of this type is given in EP 0 444 338 B1. In the configuration as a plate heat exchanger, the transmission heat exchanger medium can flow in the plates of the plate heat exchanger and the temperature control mixture flow can flow between the plates of the plate heat exchanger. 
         [0010]    A bypass line, which bridges the granule heat exchanger between the granulating mechanism and the drying mechanism, ensures reliable operation of the device. A quantity control unit may be provided to specify a fluid quantity distribution between the granule heat exchanger and the bypass line. The quantity control unit can be realized by a deflector, by controllable valves, on the one hand, after a branch of the bypass line and before the granule heat exchanger and, on the other hand, in the bypass line, or can also be realized by at least one squeeze valve at one of the two aforementioned valve positions. 
         [0011]    A conveying direction counter to an effect of gravity, in which the temperature control mixture flow is conveyed through the fluid passages, is particularly suitable in granules, the specific weight of which is less than that of the cooling water. 
         [0012]    A conveying direction in the direction of gravity, in which the temperature control mixture flow is conveyed through the fluid passages under the influence of gravity, is particularly suitable in granulates, the specific weight of which is higher than that of the cooling water. The conveying direction in the direction of gravity allows a counter-flow of the transmission heat carrier medium of the granule heat exchanger counter to a direction of gravity, so that the transmission heat carrier medium within the granule heat exchanger can be evaporated. This possibility of evaporation may be advantageous for specific applications of the granule heat exchanger. 
         [0013]    A concentrating mechanism, the entry of which is fed by the discharge line and which has a first exit for a cooling water flow and a second exit for the temperature control mixture flow, wherein the first exit of the concentrating mechanism has a fluid connection to a return line for the cooling water to the granulating mechanism, the second exit of the concentrating mechanism has a fluid connection to the granule heat exchanger, increases the efficiency of a heat transmission between the plastics material granules and the transmission heat carrier medium in the granule heat exchanger. A temperature influence on the plastics material granules can therefore be increased, assuming a given design of the granule heat exchanger. 
         [0014]    An integration of the concentrating mechanism at the entry of the granule heat exchanger is compact and leads to low heat losses. The concentrating mechanism may be arranged in the region of an expansion portion of a container wall of the granule heat exchanger. An annular line at the entry of the granule heat exchanger may be a component of the concentrating mechanism. The annular line can be separated from the interior of the expansion portion by a retaining sieve. 
         [0015]    A cooling water heat exchanger arranged in the return line between the concentrating mechanism and the granulating mechanism can be used to control the temperature of the cooling water. If necessary, the cooling water can be cooled using the cooling water heat exchanger. The energy, which is absorbed by a transmission heat exchanger medium of the cooling water heat exchanger, can be recovered. 
         [0016]    A connection of the granule heat exchanger, in which the inlet of the granule heat exchanger for the transmission heat exchanger medium has a fluid connection to a separation line, which is arranged downstream of the drying mechanism, for separated cooling water, and in which the outlet of the granule heat exchanger for the transmission heat exchanger medium has a fluid connection to a return line for the cooling water to the granulating mechanism, to a separator line after the drying mechanism of the device can be used to heat the temperature control mixture flow in the granule heat exchanger. In this case, the cooling water itself is used as the transmission heat exchanger medium of the granule heat exchanger. An arrangement of this type is particularly advantageous when using the granule heat exchanger to degas or deodorize the plastics material granules. 
         [0017]    According to the second aspect of the invention it was recognized that an ORC circuit (Organic Rankine Cycle) is a particularly advantageous variant for using the heat contained in the recovery cooling water flow. The recovery cooling water flow may be the temperature control mixture flow already mentioned above, containing the plastics material granules and at least a part of the cooling water and/or a cooling water flow after a separation of cooling water from the starting mixture flow and/or the starting mixture flow itself. The energy recovery mechanism reduces the energy consumption of the total system. A pump may be arranged in the ORC system. This pump may be used to compress the organic medium. The ORC circuit may be designed in such a way that no condensation of the ORC circuit medium takes place in the ORC turbine. The ORC turbine may work as an expansion turbine. 
         [0018]    As an alternative to an ORC circuit, a heat carrier medium circuit with a heat carrier medium or heat exchanger medium based on a salt solution may be used. In general, the temperature control mixture flow can be used to expel a refrigerant, for example water or NH 3 , from a sorption agent, which may be, for example, lithium bromide, an ionic liquid or else water. 
         [0019]    A two-stage ORC evaporator of the organic medium, in which the ORC evaporator has an ORC evaporator unit in the ORC circuit before the ORC turbine and an ORC preheater unit in the ORC circuit before the ORC evaporator unit, the ORC evaporator unit and/or the ORC preheater unit being configured as a heat exchanger with the recovery cooling water flow, is particularly well adapted to the requirements of the ORC circuit medium. 
         [0020]    A restrictor may be arranged between the ORC preheater unit and the ORC evaporator unit. 
         [0021]    A design, comprising an ORC cooler in the ORC circuit between the ORC turbine and the ORC condenser for emitting heat from the ORC circuit medium to a transmission heat exchanger medium, and comprising an ORC preliminary preheater in the ORC circuit between the ORC condenser and the ORC evaporator for emitting heat from the transmission heat exchanger medium to the ORC circuit medium, uses the heat contained in the ORC circuit medium at the exit of the ORC turbine for preliminary preheating of the ORC circuit medium after the condensation and therefore increases the efficiency of the ORC circuit. 
         [0022]    A concentrating mechanism, the entry of which is fed by the discharge line and which has a first exit for a cooling water flow and a second exit for a mixture flow, containing plastics material granules and cooling water with a higher granule fraction than the starting mixture flow, the first exit ( 49 ) of the concentrating mechanism having a fluid connection to the ORC evaporator, leads to the possibility of using separately the thermal energy, which, on the one hand, is contained in the cooling water flow, which is guided away via the first exit, and which, on the other hand, is guided away in the mixture flow via the second exit. 
         [0023]    A possible use of the energy of the mixture flow is produced by the configuration, in which the ORC preheater unit has a fluid connection to the second exit of the concentrating mechanism. 
         [0024]    An ORC circuit medium, having an evaporation enthalpy in the range between 0 and 2600 kJ/kg and/or a heat capacity in the range between 0 and 6 kJ/kgK, has proven to be well adapted to the requirements of an ORC circuit for the energy recovery mechanism in the device. A high heat capacity of the ORC circuit medium reduces the required circulating quantity of the circuit medium and thereby reduces the required overall size of the components in the energy recovery mechanism. The high heat capacity of the ORC circuit medium, if present, in the preheater, removes a correspondingly high heat fraction from the cooling water or from the mixture flow. The ORC circuit medium may have a dry, retrograde expansion behavior, i.e. a saturated steam curve with a positive gradient beyond a critical point in the T/S graph of the ORC circuit medium. The ORC circuit medium can be operated in a temperature range between 10° C. and 120° C. and in a pressure range between 1 bar and 16 bar. R245fa, isobutane or isobutene may be used as the ORC circuit medium. 
         [0025]    A bypass line, which bridges the energy recovery mechanism between the granulating mechanism and a drying mechanism, ensures reliable operation of the device with the energy recovery mechanism. 
         [0026]    The above-described features regarding the two aspects of the device can also be realized in any combination with one another. 
         [0027]    Embodiments of the invention will be described in more detail below with the aid of the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  schematically shows a general plan of a device for producing granules made of polymeric materials, in other words a plastics material granulating system; 
           [0029]      FIG. 2  shows, in a view similar to  FIG. 1 , a general plan of an alternative plastics material granulating system; 
           [0030]      FIG. 3  shows, in a view similar to  FIG. 1 , a general plan of an alternative plastics material granulating system; 
           [0031]      FIG. 4  shows an embodiment of a concentrating mechanism, which can be used as an alternative to a concentrating mechanism which is shown in  FIG. 3 ; 
           [0032]      FIG. 5  shows, in a view similar to  FIG. 1 , a general plan of an alternative plastics material granulating system; 
           [0033]      FIG. 6  shows, in a view similar to  FIG. 1 , a general plan of an alternative plastics material granulating system; and 
           [0034]      FIG. 7 to 9  in a view similar to  FIG. 1 , in each case, shows a general plan of alternative plastics material granulating systems. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]      FIG. 1  shows a first configuration of a device  1  for producing granules made of polymeric materials. The device  1  is also called a plastics material granulating system. 
         [0036]    The device  1  has an extruder  2  for producing a polymer melt. A melt pump can also be provided as an alternative to an extruder. 
         [0037]    A perforated plate  3 , through which the polymer melt is pressed, is arranged at the exit of the extruder  2 . A cutting mechanism  4  is arranged in the conveying path of the polymer melt directly behind the perforated plate  3 . The cutting mechanism  3  cuts the individual polymer strands formed in the perforated plate  3  into individual granule grains. The cutting process takes place in a granulating hood  5 , through which cooling water is guided to cool the cut granules, said cooling water also being called granulating water. The extruder  2 , the perforated plate  3 , the cutting mechanism  4  and the granulating hood  5  are components of a water-cooled granulating mechanism  6  for producing the plastics material granules. A discharge line  7 , which has a fluid connection to an exit of the granulating hood  5 , is arranged downstream of the granulating hood  5  in the conveying path of the cooling water. The discharge line  7  is used to discharge a starting mixture flow from the granulating hood  5 , which flow contains the plastics material granules produced and the cooling water guided through the granulating hood  5 . 
         [0038]    A bypass branch  8  is arranged in the further conveying path of the discharge line  7 . The discharge line  7  branches there into a heat exchanger feed line  9  and into a bypass line  10 . The heat exchanger feed line  9  has a fluid connection to the granule heat exchanger  11 . The latter is used to control the temperature of a temperature control mixture flow, containing the plastics material granules produced and at least a part of the cooling water. A quantity control unit is used to specify a fluid quantity distribution between the granule heat exchanger  11  and the bypass line  10 . A water volume flow in the bypass line  10  can be measured by a throughflow sensor  11   a . The quantity control unit can be realized as an adaptable deflector unit at the site of the bypass branch  8 . As an alternative, the quantity control unit can be realized by controllable valves or shut off members  12 ,  13 , for example in the form of flaps or slides. The shut off member  12  is arranged in the conveying path of the temperature control mixture flow between the bypass branch  8  and the granule heat exchanger  11 . The shut off member  13  is arranged in the bypass line  10  after the bypass branch  8 . In a further variant, the quantity control unit can be realized by a squeeze valve either at the site of the shut off member  12  or at the site of the shut off member  13 . A regulating unit  13   a  can have a control or signal connection with the shut off members  12 ,  13  of the squeeze valve. This connection is not shown in the drawing. The regulating unit  13   a  also has a signal connection, in a manner also not shown, with the throughflow sensor  11   a . In the regulating unit  13   a , an actual throughflow value through the bypass line  10 , which is measured by the throughflow sensor  11   a , is compared with a predetermined desired throughflow value and, if the deviation exceeds a predetermined tolerance value, is regulated by activating the deflector unit, the shut off members  12 ,  13  or the squeeze valve to the desired value. 
         [0039]    The granule heat exchanger  11  is used for heat exchange between the temperature control mixture flow and an ORC (Organic Rankine Cycle) circuit medium. The ORC circuit medium is a transmission heat exchanger medium for heat transmission in the granule heat exchanger  11 . The granule heat exchanger  11  is configured as a tube bundle heat exchanger. The temperature control mixture flow is conveyed from bottom to top, in other words counter to an effect of gravity, by heat exchanger tubes  14  that run straight, of the tube bundle. The heat exchanger tubes  14 , of the granule heat exchanger  11  are a plurality of fluid passages running in parallel, in other words not in series, for the temperature control mixture flow. 
         [0040]    As an alternative to a straight course, the heat exchanger tubes  14  can also have a course bent in a U shape. The heat exchanger tubes  14  can have a diameter that is four to ten times as large as the typical diameter of the granule grains produced. Instead of a tube bundle heat exchanger the granule heat exchanger  11  can also be configured as a plate heat exchanger in the manner, for example, of EP 0 444 338 B1, which also has a plurality of fluid passages running in parallel for the temperature mixture flow. 
         [0041]    In the upper region of a cylindrical heat exchanger container  15  of the granule heat exchanger  11 , in which the tube bundle is arranged, an inlet  16  for the ORC circuit medium opens into the heat exchanger container  15 . The inlet  16  is a component of an ORC circuit  17  of an energy recovery mechanism  18  for recovering energy from a recovery cooling water flow, which contains at least a part of the cooling water of the starting mixture flow. In the example of  FIG. 1 , the recovery cooling water flow is identical to the starting mixture flow when the by pass line  10  is closed. 
         [0042]    An outlet  19  of the ORC circuit  17  opens out in the lower region of the heat exchanger container  15  from the latter. A restrictor  20  is arranged downstream from the outlet  19  in the conveying direction of the ORC circuit medium. The restrictor  20  keeps the ORC circuit medium in the granule heat exchanger  11  under a pressure that is sufficient for the ORC circuit medium in the granule heat exchanger  11  to not evaporate. An evaporator unit  21  is arranged downstream of the restrictor  20  in the conveying path of the ORC circuit medium in the ORC circuit  17 . The evaporator unit  21  has an evaporator container and, in addition to the granule heat exchanger  11 , which forms an ORC preheater unit, is a component of an ORC evaporator. An ORC turbine  22  is arranged downstream of the evaporator unit  21  in the conveying path of the ORC circuit medium in the ORC circuit  17 . The ORC turbine  22  has a mechanical connection to a generator  23 . The generator  23  feeds the current produced into a current network. An ORC condenser  24  is arranged downstream of the ORC turbine  22  in the conveying path of the ORC circuit medium in the ORC circuit  17 . An ORC pump  25  for the circulating conveyance of the ORC circuit medium in the ORC circuit  17  is arranged downstream of the ORC condenser  24  in the conveying path of the ORC circuit  17 . 
         [0043]    The ORC circuit medium has an evaporation enthalpy in the range between 0 and 2600 kJ/kg and a heat capacity in the range between 0 and 6 kJ/kgK. The ORC circuit medium may have a dry, in other words retrograde, expansion behavior. The ORC circuit medium thus has a saturated steam curve with positive gradients in the T/S graph of the circuit medium. The T/S graph in this case gives the dependency between the absolute temperature T and the entropy S of the circuit medium. The ORC circuit  17  is operated in a temperature range between 10° C. and 120° C. and in a pressure range between 1 bar and 16 bar. R245fa and isobutane or isobutene are used as the ORC circuit medium. 
         [0044]    In the region of an inlet-side expansion portion  26  of the heat exchanger container  15  between the heat exchanger feed line  9  and the tube bundle, a retaining sieve  27 , with which plastics material agglomerates can be retained, is arranged in the flow path of the temperature control mixture flow. 
         [0045]    A heat exchanger discharge line  28 , which has a fluid connection with the tube bundle of the granule heat exchanger  11  via a constriction portion  29  of the heat exchanger container  15 , unites with the bypass line  10  via a bypass mouth  30 . The bypass line  10  thus bridges the granule heat exchanger  11  between the granulating mechanism  6  and a downstream drying mechanism  31  for drying the plastics material granules. Arranged at the entry of the drying mechanism  31  in a mixture flow line  32  running after the bypass mouth  30  for the temperature mixture flow, is an agglomerate separator  33 . Arranged downstream thereof in the mixture flow line  32  is a granule water separator  34  with a dryer  35  arranged downstream in the conveying path of the plastics material granules. Arranged downstream of the dryer  35  in the granule conveying path, is a sieve machine  36  for sieving the dried plastics material granules. A granule container  37  in the form of a storage silo is arranged downstream of the sieve machine  36  in the conveying path of the granules. A delivery member in the form of a cellular wheel sluice  38  is arranged on the delivery side below the granule container  37 . A conveying path  39  of an otherwise not shown pneumatic conveying system is arranged downstream of the cellular wheel sluice  38 . Using the pneumatic conveying system, the produced and dried plastics material granules can be fed to a target site. 
         [0046]    The cooling water separated in the granule-water separator  34  leaves the latter via a cooling water line  40 . A sieve mechanism  41  is arranged therein in the further conveying path of the cooling water. Arranged downstream of the sieve mechanism  41  in the conveying path of the cooling water is a cooling water tank  42 . A conveying pump  43  for the circulating circuit conveyance of the cooling water is arranged downstream of the cooling water tank  42  in the conveying path of the cooling water. A cooling water heat exchanger  44  is arranged downstream of the conveying pump  43  in the conveying path of the cooling water. From the cooling water heat exchanger  44 , the cooling water is fed to the granulating hood  5  again via a feed line  45 . Using the cooling water heat exchanger  44 , the cooling water before the granulating hood  5  is brought to a predetermined granulating temperature. The cooling water temperature at the entry into the granulating hood  5  is typically 40° C. to 70° C. The cooling water is heated by heat exchange with the hotter granule grains, which are produced in the granulating mechanism  6 , typically by 5K to 20K. 
         [0047]    A temperature sensor T may be connected to the feed line  45 . Said temperature sensor can measure an actual temperature of the cooling water at the entry of the granulating hood  5 . 
         [0048]    By means of the granule heat exchanger  11 , an efficient preheating of the ORC circuit medium for the subsequent evaporation thereof in the evaporator unit  21  is ensured. The ORC circuit medium is preheated in the granule heat exchanger  11  in the cross counter flow. The current produced using the energy recovery mechanism  18  can be fed back into a supply network. As a result, a net current consumption of the overall system is correspondingly reduced. The current produced using the energy recovery mechanism  18  can be used, at least in part, to operate components of the plastics material granulating system, for example to operate the conveying pump  43 , to operate a drive M of the cutting mechanism  4  or to operate the extruder  2 . The cellular wheel sluice  38  can also be operated by the energy produced by the energy recovery mechanism  18 . 
         [0049]    When starting up the plastics material granulating system, the heat exchanger feed line  9  is closed and the starting mixture flow is firstly guided via the bypass line  10 . The granule heat exchanger  11  can also be bridged via the bypass line  10  during operation of the system by corresponding adaptation. 
         [0050]    A mesh size of the retaining sieve  27  is smaller than an internal diameter of the heat exchanger tubes  14 . 
         [0051]      FIG. 2  shows an alternative configuration of a device  46  for producing granules made of polymeric materials, which can be used instead of the device  1 . Components and function, which correspond to those which have already been described above with reference to  FIG. 1 , have the same reference numerals and will not be discussed again in detail. 
         [0052]    In contrast to the conveyance of the temperature control mixture flow through the granule heat exchanger counter to the effect of gravity in the configuration according to  FIG. 1 , the conveyance of the temperature control mixture flow through the granule heat exchanger  11  in the configuration according to  FIG. 2  takes place under the influence of gravity through the fluid passages, in other words through the heat exchanger tubes  14 . In comparison to the arrangement according to  FIG. 1 , the granule heat exchanger  11  in the configuration according to  FIG. 2  is thus arranged overhead. Accordingly, the inlet  16  for the ORC circuit medium is also arranged in the lower region of the heat exchanger container  15  and the outlet  19  is arranged in the upper region of the heat exchanger container  15 . The granule heat exchanger  11  according to  FIG. 2  can operate both as an ORC preheater unit and as an ORC evaporator unit. In the ORC circuit  17  according to  FIG. 2 , the granule heat exchanger  11  is simultaneously an ORC evaporator. The restrictor  20  in the ORC circuit  17  according to  FIG. 1  can be dispensed with in the ORC circuit according to  FIG. 2 . The ORC evaporator unit  21  is also dispensed with in the ORC circuit  17  according to  FIG. 2 . 
         [0053]    As an alternative to the arrangement possibilities of the granule heat exchanger  11  according to  FIGS. 1 and 2 , the granule heat exchanger  11  can also be configured with heat exchanger tubes  14  running horizontally or in a U shape or heat exchanger plates, which in each case predetermine a plurality of fluid passages running in parallel for the temperature control mixture flow. 
         [0054]      FIG. 3  shows an alternative configuration of a device  47  for producing granules made of polymeric materials, which can be used instead of the device  1 . Components and functions, which correspond to those that have already been described above with reference to  FIG. 1 , have the same reference numerals and will not be discussed again in detail. 
         [0055]    In  FIG. 3 , the ORC circuit  17 , which, in the device  47  according to  FIG. 3 , can be configured precisely as in the device according to  FIG. 1 , is omitted. 
         [0056]    In the device  47 , a concentrating mechanism  48  is arranged in the conveying path of the temperature control mixture flow after the bypass branch  8 . If the heat exchanger feed line  9  is at least partially open, a mixture flow entry of the concentrating mechanism  48  is fed by the discharge line  7 . The concentrating mechanism  48  may be designed in the manner of that described in DE 100 61 892 C1. 
         [0057]    The concentrating mechanism  48  has a first exit  49  for the further conveyance of a cooling water separated from the temperature control mixture flow in the concentrating mechanism  48  and a second exit  50  for the further conveyance of the concentrated temperature control mixture flow, which contains the produced plastics material granules and the non-separated part of the cooling water and is fed to the granule heat exchanger  11 . 
         [0058]    The first exit  49  of the concentrating mechanism  48 , in other words the cooling water exit, has a fluid connection via an outlet tube line  51  and a cooling water mouth  52  to a cooling water line  40  between the granule-water separator  34  and the sieve mechanism  41 . A further cooling water heat exchanger  53  is arranged in the outlet tube line  51 . The outlet tube line  51  is a return line for the cooling water to the granulating mechanism  6 . Comparably to the regulating of the cooling water flow in the bypass line  10 , the volume flow in the outlet tube line  51  can also be regulated with the aid of a corresponding throughflow sensor in the outlet tube line  51  and corresponding adjusting fittings at the site of the concentrating mechanism  48  or shut off members in the exits  49 ,  50 . 
         [0059]    The concentrating mechanism  48  may alternatively also be integrated at the entry of the granule heat exchanger  11  into the latter. A configuration of this type of a concentrating mechanism  54 , which can be used instead of the concentrating mechanism  48 , is shown in  FIG. 4 . The concentrating mechanism  54  is arranged in the region of the expansion portion  26  and a lower portion  55  of the heat exchanger container  15  of the granule heat exchanger  11 . Arranged spaced apart from an inner wall of the expansion portion  26  and of the lower portion  55  of the heat exchanger container  15  is a retaining sieve  56 . This separates an annular line  57  for the cooling water separated in the concentrating mechanism  54  from the interior  58  of the heat exchanger container  15 , so that the granules cannot enter the annular line  57 . The annular line  57  has a fluid connection via a plurality of connecting line portions  59  with the outlet tube line  51 . A part of the cooling water of the starting mixture flow is separated via the outlet tube line  51 . The remainder of the cooling water remains in the temperature control mixture flow. The temperature control mixture flow thus concentrated can be more strongly cooled in the granule heat exchanger  11 . The cooling water separated in the outlet tube line  51  can be cooled using the cooling water heat exchanger  53 . 
         [0060]    A line path of the discharge line  7  between the granulating hood  5  and the concentrating mechanism  48  or  54  is short and is, for example, only a few meters. 
         [0061]    A heat exchanger power can be regulated by means of a control mechanism S, which has a signal connection to the temperature sensor T and the cooling water heat exchanger  44  and optionally with the cooling water heat exchanger  53  in such a way that the actual temperature of the cooling water at the entry of the granulating hood  5  coincides with a predetermined desired temperature within also predetermined limits. 
         [0062]    A numerical example for the operation of the device  47  as a plastics material granulating system for polyolefins will be given below. A mass flow of 50 t/h polyolefin granules is granulated. An entry temperature of the granulating water into the granulating hood  5  is 80° C. A cooling water quantity transported in the cooling water circuit is 500 m 3 /h. In the starting mixture flow, the cooling water contained there is heated, by cooling the hot granules, to a temperature of about 95° C. The starting mixture flow is divided in the concentrating mechanism  48  or  54  into a cooling water part flow of 250 m 3 /h with a temperature of 95° C., which is conveyed onward via the outlet tube line  51 , and into the temperature control mixture flow also of 250 m 3 /h cooling water, which is fed to the granule heat exchanger  11 . The temperature control mixture flow emits heat to the ORC circuit medium. As a result, the temperature control mixture flow is cooled to a temperature of 65° C. During the subsequent drying of the plastics material granules contained in the temperature control mixture flow, the latter one dried more gently because of the cooling. Less abrasion or dust is generated during the drying. In the cooling water tank  42 , the two cooling water part flows at 65° C. (separated in the granule water separator  34  or in the drying mechanism  31 ) and 95° C. (separated in the concentrating mechanism  48  or  54 ) are mixed producing a cooling water temperature of about 80° C. A temperature control of the cooling water using the cooling water heat exchanger  53  in the outlet tube line  51  is not necessary, so this cooling water heat exchanger  53  can also be dispensed with. Any residual temperature differences can be compensated by means of the cooling water heat exchanger  44 . 
         [0063]    A further numerical example in the operation of the device  47  as a plastics material granulating system will be described below during PC (polycarbonate) hot granulation. In this case, the cooling water enters the granulating hood  5  at a temperature of about 90° C. On leaving the granulating hood  5 , the temperature control mixture flow has a temperature of 110° C. In the concentrating mechanism  48  or  54 , the starting mixture flow is divided into an outlet cooling water flow through the outlet tube line  51 , in which about half of the entire cooling water flow is conveyed, and into the temperature control mixture flow with the other half of the cooling water flow. In the granule heat exchanger  11 , the temperature control mixture flow is cooled to about 70° C. The overheated cooling water flow is guided under geodetic excess pressure in the cooling water circuit. 
         [0064]    In the cooling water tank  42 , the two part flows at the temperatures of 70° C. and 110° C. mix to form a mean temperature of 90° C., which corresponds to the required temperature at the entry of the granulating hood  5 . 
         [0065]    In the granule heat exchanger  11 , assuming a corresponding length of the heat exchanger tubes  14 , a steam bubble formation can be avoided via the static water pressure even with an excess heating of the cooling water. 
         [0066]    Instead of an ORC circuit  17 , an energy recovery can also be realized by using a further heat exchanger for heating the cooling water if cooling water heating is required in the cooling water circuit, depending on the plastics material production process. The heating of the transmission heat exchanger medium in the granule heat exchanger  11  can also be used to operate a heat pump. 
         [0067]    The cooling water heat exchanger  53  in the outlet tube line  51  can also be dispensed with in the PC heat granulation. 
         [0068]    The operation of the device  47  will be described below using the example of the production of LDPE (Low Density Polyethylene) granules. The cooling water in this case enters the granulating hood  5  with a flow of 500 m 3 /h and a temperature of 60° C. At the exit of the granulating hood  5 , the starting mixture flow has a temperature of about 75° C. In the concentrating mechanism  48  or  54 , the starting mixture flow is divided into the temperature control mixture flow with 150 m 3 /h cooling water and into the outlet cooling water flow in the outlet tube line  51  with a flow of 350 m 3 /h cooling water. The temperature control mixture flow is heated to a temperature of 90° C. in the granule heat exchanger  11 . 
         [0069]      FIG. 5  shows an alternative configuration of a device  60  for producing granules made of polymeric materials, which can be used instead of the device  1 . Components and functions, which correspond to those which have already been described above with reference to  FIG. 1 , have the same reference numerals and will not be discussed again in detail. 
         [0070]    The ORC circuit is dispensed with in the device  60 . The cooling water itself is used as the transmission heat exchanger medium, which exchanges its heat in the granule heat exchanger  11  with the temperature control mixture flow. The inlet  16  for the transmission heat exchanger medium has a fluid connection with the cooling water line  40  at the exit of the granule-water separator  34 . Arranged in a feed line  61  for the transmission heat exchanger medium between the exit of the granule-water separator  34  and the inlet  16  in the conveying path of the cooling water is firstly a cooling water intermediate container  62  and, in the further conveying path, a preheat exchanger  63  for heating the cooling water before the inlet  16 . 
         [0071]    The outlet  19  for the transmission heat exchanger medium has a fluid connection via a return line  64  with the portion of the cooling water line  40  to the cooling water tank  42 . The cooling water mouth  52  of the discharge tube line  51  is also arranged in this portion. 
         [0072]    The temperature control mixture flow leaving the granule heat exchanger  11  enters the drying mechanism  31 . The cooling water separated there is heated in the preheat exchanger  63  to a temperature of 100° C. and is used to heat the LDPE granules produced in the granule heat exchanger  11  to degas the LDPE. In this case, the transmission heat exchanger medium cools to 85° C. The two cooling water heat exchangers  44  and  53  are operated in such a way that the cooling water in the feed line  45  and at the entry of the granulating hood  5  again has the required temperature of 60° C. 
         [0073]    In the device  60 , the granule container  37  is configured a degassing silo. 
         [0074]    The LDPE may have the copolymer ethylene vinyl acetate. The water temperature for granulation in the granulating hood  5  is lowered with the increasing content of ethylene vinyl acetate copolymer. 
         [0075]      FIG. 6  shows an alternative configuration of a device  65  for producing granules made of polymeric materials, which can be used in place of the device  1 . Components and functions, which correspond to those which have already been described above with reference to  FIG. 1 , have the same reference numerals and will not be discussed again in detail. 
         [0076]    A drive motor  66  for the extruder  2  is shown in  FIG. 6 . A feed of powdery starting material for the extrusion in the extruder  2  is indicated schematically by an arrow  67  in  FIG. 6 . 
         [0077]    An ORC evaporator, in the device  65 , apart from the granule heat exchanger  11 , as the ORC preheater unit, also comprises an ORC evaporator unit  68 , which is arranged in the ORC circuit  17  between the granule heat exchanger  11  and the ORC turbine  22 . The ORC evaporator unit  68  is arranged in the outlet tube line  51  of the concentrating mechanism  48 . The ORC evaporator unit  68  has a cooling water entry  69  and a cooling water exit  70 . The ORC evaporator unit  68  is also configured, comparably to the granule heat exchanger mechanism  11 , as a tube bundle heat exchanger with horizontally extending heat exchanger tubes, in which the cooling water is guided back and forth between the cooling water entry  69  and the cooling water exit  70  in a plurality of paths. Other designs of the evaporator unit  68  are also possible. An ORC inlet  72  of the ORC circuit  17  opens into an evaporator container  71  of the ORC evaporator unit  68  on the casing side and an ORC outlet  73  of the ORC circuit  17  opens out therefrom.  FIG. 6  indicates a heat exchanger operation of the ORC evaporator unit  68  in co-current flow. A counter-current flow operation of the heat transmission between the cooling water and the ORC circuit medium in the ORC evaporator unit  68  is also possible. 
         [0078]    Arranged in the ORC circuit  17  between the ORC turbine  22  and the ORC condenser  24  is an ORC cooler  74  for emitting heat from the ORC circuit medium to a further transmission heat exchanger medium, for example to water. Arranged in the ORC circuit  17  between the ORC pump  25  and the granule heat exchanger  11  is an ORC preheater  75  to emit heat from the further transmission heat exchanger medium to the ORC circuit medium. The ORC cooler  74  has a fluid connection with the ORC preheater  75  via a transmission heat exchanger medium circuit  76 , which is shown by dashed lines in  FIG. 6 . 
         [0079]    In the device  65 , the first exit  49  of the concentrating mechanism  48  has a fluid connection with the ORC evaporator unit  68 . The ORC preheating unit, in other words the granule heat exchanger  11 , has a fluid connection with the second exit  50  of the concentrating mechanism  48 . 
         [0080]    As indicated by dashed lines in  FIG. 6 , the device  65  may also have a bypass line  10  between the granulating mechanism  6  and the drying mechanism  31 . 
         [0081]    A numerical example in the production of polyolefin granules with the device  65  will in turn be given below: The cooling water enters the granulating hood  5  at a temperature of 80° C. and a cooling water flow of 500 m 3 /h. The granulating mechanism  6  produces a mass flow of 50 t/h polyolefin granules. The starting mixture flow leaves the granulating hood  5  at a temperature of 93° C. A division of the starting mixture flow takes place in the concentrating mechanism  48  into a cooling water flow in the outlet tube line  51  of 400 m 3 /h and into the temperature control mixture flow with a water fraction of 100 m 3 /h. The temperature control mixture flow consists of a cooling water flow of 100 m 3 /h and a plastics material granule volume flow of 50 m 3 /h to 55 m 3 /h. In the granule heat exchanger  11 , the temperature control mixture flow is cooled to 75° C. In the ORC evaporator unit  68 , the cooling water entering at a temperature of 93° C. is cooled to a temperature of 82° C. In the drying mechanism  31 , the polyolefin granules are separated, so a production of 50 t/h is realized. The cooling water separated in the drying mechanism  31  at a temperature of 75° C. and the cooling water leaving the ORC evaporator unit  68  at a temperature of 82° C. mix to a mixing temperature in the cooling water tank  42  of about 80° C. Basically, further heat exchangers to regulate the cooling water temperature in the device  65  can be dispensed with. Alternatively, it is possible to provide the heat exchangers  44  or  53 , on the one hand, in the feed line  45  and, on the other hand, in the outlet tube line  51  between the ORC evaporator unit  68  and the cooling water tank  42 . This may be used to operate the device  65  without the ORC circuit  17 . 
         [0082]      FIG. 7  shows an alternative configuration of a device  77  for producing granules made of polymeric materials, which can be used instead of the device  1 . Components and functions, which correspond to those which have already been described above with reference to  FIG. 1 , have the same reference numerals and will not be discussed again in detail. The schematic view according to  FIG. 7  differs in the degree of abstraction from that according to  FIG. 1 to 3  and  FIG. 5 ,  6 . 
         [0083]    A shut off valve  78  is also drawn in  FIG. 7  in the outlet tube line  51 . If this is closed, the concentrating mechanism  48  is inactive and the total granule-water flow flows through the granule heat exchanger  11 . 
         [0084]    In the device  77 , the granule heat exchanger  11  is operated with a heat exchanger medium in the form of a salt solution guided in a circuit. Suitable heat exchanger media are lithium bromide or ionic liquids. At the entry of the granule heat exchanger  11 , the temperature of the heat exchanger medium, which is fed to the granule heat exchanger  11  via the inlet  16 , is still low. Accordingly, the salt concentration is low. In the granule heat exchanger  11 , the heat exchanger medium absorbs heat from the granule-water flow, in other words from the temperature control mixture flow, and is heated in the granule heat exchanger  11  until it leaves the latter in liquid form via the outlet  19  with a high salt concentration. Owing to the heating of the heat exchanger medium in the granule heat exchanger  11 , a part of the heat exchanger medium evaporates and leaves the granule heat exchanger  11  via a steam outlet  79 . 
         [0085]    The outlet  19  connects the granule heat exchanger  11  to a recuperator  80 . The inlet  16  connects the recuperator  80  to the granule heat exchanger  11 . The steam outlet  79  connects the granule heat exchanger  11  to the condenser  81 . The steam is cooled therein with the aid of cooling water and condenses, the cooling water being fed to the condenser  81  via a cooling water inlet  82  and discharged via a cooling water outlet  83 . The condenser  81  may be loaded with a vacuum and the condensate produced has a very low temperature in the range between 5° C. and 8° C. The condensate is removed from the condenser  81  via a condensate line  84 . The latter can be closed by a shut off valve  85 . The condensate is fed to an evaporator  86  from the condenser  81  via the condensate line  84 . During evaporation, which can take place under negative pressure in the evaporator  86 , the evaporating condensate cools a heat carrier medium, which is fed to the evaporator  86  via an inlet  87  and removed therefrom via an outlet  88 . The heat carrier medium used in the evaporator  86  may in turn be water. The heat carrier medium, at the inlet  87 , has a temperature of 14° C. and, at the outlet  88 , depending on the temperature of the condensate fed to the evaporator  86 , a temperature of, for example, 7° C. The lines  88  and  87  may be part of a cooling water circuit. During the production of cooling water in this circuit with the device  77 , no compressor is necessary. 
         [0086]    The steam removed from the evaporator  86  via a steam line  89  is returned in an absorber  90  into the salt solution heat carrier circuit. The content of the absorber  90  is cooled with cooling water, which is fed to the absorber via an inlet  91  and removed therefrom via an outlet  92 . In the absorber  90 , the salt solution is therefore present in the cold state. To circulate the salt solution in the salt solution heat exchanger circuit, a circulating pump  93  is used. The latter is arranged in a feed line  94 , which connects the absorber  90  to the recuperator  80 . 
         [0087]    A mixing takes place in the recuperator  80  of the cold salt solution fed by the absorber  90  via the feed line  94  with the hot salt solution also fed to the recuperator  80  via the outlet  19 . The salt solution with a mixing temperature, which is higher than the temperature of the salt solution in the feed line  94 , is fed to the granule heat exchanger  11  via the inlet  16 . The recuperator  80  has a fluid connection with the absorber  90  via a salt solution return line  95 . 
         [0088]    The heat of the granule-water flow in the granule heat exchanger  11  is used to remove heat from the heat carrier medium, in other words the salt solution. This removal of heat is used in the device  77  according to  FIG. 7  in an absorption refrigerating system. The refrigerant, in the present example, the water, is ejected in the form of steam from the heat carrier medium, in other words the salt solution. The granule heat exchanger  11  in the device  77  is therefore also called the ejector. 
         [0089]      FIG. 8  shows a further configuration of a device  96  for producing granules made of polymeric materials, which can be used instead of the device  77 . Components and functions, which correspond to those which have already been described above with reference to  FIG. 1 to 7  and, in particular, with reference to  FIG. 7 , have the same reference numerals and will not be discussed again in detail. 
         [0090]    In the configuration according to  FIG. 8 , arranged in the outlet tube line  51  is a preheat exchanger  97 , which may also be a tube bundle heat exchanger. The preheat exchanger  97  absorbs heat from the granulating water, which is guided via the outlet tube line  51  through the preheat exchanger  97 , and emits the latter to the salt solution heat carrier medium, which is fed to the preheat exchanger  97  via a feed line  98  and leaves the preheat exchanger  97  via a discharge line  99 . The feed line  98  connects the recuperator  80  to the preheat exchanger  97 . The discharge line  99  connects the preheat exchanger  97  to the granule heat exchanger  11  and is simultaneously its heat exchanger medium inlet. 
         [0091]    Otherwise, the device  96  corresponds to the device  77 . 
         [0092]      FIG. 8  schematically shows that the outlet tube line  51  does not have to be directly connected to the cooling water tank  42 , but can also open into the cooling water line  40 . 
         [0093]      FIG. 9  shows a further configuration of a device  100  for producing granules made of polymeric materials, which can be used instead of the device  77 . Components and functions, which correspond to those which have already been described above with reference to  FIG. 1 to 8  and, in particular, with reference to  FIGS. 7 and 8 , have the same reference numerals and will not be discussed again in detail. 
         [0094]    In the device  11 , the preheat exchanger and the granule heat exchanger have exchanged roles with regard to the order of heating the salt solution heat carrier medium. The outlet  19  of the granule heat exchanger  11  has a fluid connection with an ejector heat exchanger  101 , which is arranged in the device  100  at the site of the preheat exchanger  97  of the device  96  according to  FIG. 8 , in other words in the outlet tube line  51 . The salt solution heated in the ejector heat exchanger  101  is returned to the recuperator  80  via a return line  102 . A steam outlet  103  connects the ejector heat exchanger  101  to the condenser  81 . 
         [0095]    Otherwise, the device  100  according to  FIG. 9  corresponds to the device  96  according to  FIG. 8 .

Technology Classification (CPC): 8