Abstract:
A feed device for a high-pressure roller press for the high-pressure comminution of material to be ground, the feed device feeding the material to be ground in a controlled manner into the roller nip between two rollers of the high-pressure roller press. The feed device has at least two rotary valves, the position of which is variable independently of each other. In a refinement of the invention, the feed device also has a shaft which is variable in height above the roller nip. By means of the rotary valves which are variable independently of each other and by means of the height-variable shaft, the feeding behavior of the feed device can be varied during the starting of the high-pressure roller press and during the operation of the high-pressure roller press in order thereby to prevent the high-pressure roller press from vibrating and to ensure optimum operation of the high-pressure roller press.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a feed device for a high-pressure roller press for the high-pressure comminution of grinding stock, said feed device delivering the grinding stock in a controlled manner into the roller nip between two rollers of the high-pressure roller press. 
         [0002]    For the comminution of brittle grinding stock, Schönert in 1977 proposed in German Auslegeschrift DE 27 08 053 not to comminute the grinding stock in traditional fashion, but firstly, through the application of high pressure in a roller nip, to press the grinding stock into flakes, whereupon the structure of the grinding stock ruptures. In a further step, the flakes emerging from the roller nip can be broken down into their individual component parts using comparatively little energy. The high-pressure pressing in the roller nip and the subsequent disagglomeration of the pressed flakes demands less energy for the comminution per unit of mass of grinding stock than does a conventional grinding process. Through this type of comminution, high grinding finenesses are attainable, for which purpose a circulation of the grinding stock is necessary. Since the roller nip, however, is wider than the greatest extent of the comminuted grinding stock, it is important to charge the roller nip such that, at the same time, a specific quantity of the grinding stock passes through the roller nip. If the roller nip is charged with too small a quantity per unit of time, then in the extreme case the grinding stock is no longer comminuted at all or the high-pressure roller press acts similarly to a crusher. If, on the other hand, too large a quantity is poured onto the roller nip, it can happen that the high-pressure roller press is overloaded and starts to vibrate. Upon the vibration, the roller nip gets larger and smaller in terms of resonance frequency and also the circulation speed varies with resonance frequency, since, in the event of an overload, the rollers of the high-pressure roller press are repeatedly braked by the excess of grinding stock and re-accelerated by the drive motors. In the case of high-pressure comminution in the roller nip, care must therefore be taken to ensure that the roller nip is supplied with grinding stock in suitable measure. The actual feed quantity is heavily dependent, however, on the nature of the grinding stock. The noteworthy parameters to which regard should be paid are the grain size distribution, the mean grain size and the evenness of the available stream of grinding stock onto the roller nip. For the delivery onto the roller nip, the grinding stock or ‘feed material’ must be fed evenly into the roller nip from above. 
         [0003]    The type of material charging has a significant influence on the smooth running of the high-pressure roller press. In order to improve the feed conditions and ensure an even distribution of the drive power to the drive motors of the high-pressure roller press, the working of a feed device above the roller nip is therefore being steadily improved. 
         [0004]    German Offenlegungsschrift DE 34 38 310 A1 discloses a device for evening out the delivery of feed material via a feed gate into a comminuting machine, wherein the feed material is repeatedly redirected. 
         [0005]    In German Offenlegungsschrift DE 40 06 971 A1, a feed device for filling granular solids into a comminuting machine is disclosed, wherein a pipe resonator is disposed between a hopper and the comminuting machine. 
         [0006]    Finally, German Offenlegungsschrift DE 196 32 29 76 A1 discloses a feed device which divides the feed material into two fractions by means of a screen and delivers the fractions from different sides onto the roller nip of a high-pressure roller press. 
       SUMMARY OF THE INVENTION 
       [0007]    The object of the invention is to improve the function of the feed device in terms of the feed characteristics of the high-pressure roller press in its entirety and in terms of an even distribution of the drive power to different drive motors of the high-pressure roller press. 
         [0008]    The object of the invention is achieved by virtue of the fact that the feed device has at least two rotary valves, the position of which can be varied independently of one another. 
         [0009]    Through the presence of at least two rotary valves, the feed device according to the invention allows adaptation to the varying requirements associated with the changing material properties of the feed material. It is thus possible to open and close the two rotary valves in symmetry in order thus to deliver a specific average total quantity per unit of time to the high-pressure roller press. Apart from this pure metering function, as a result of uniform opening around the center point of the feed device centrally above the roller nip of the high-pressure roller press, it is also possible to set the two rotary valves such that the center of opening between the at least two rotary valves is not arranged over the center of the roller nip, but is laterally offset thereto. It is hereby possible to vary not only the feed quantity, but also the exact delivery location. Specifically when the high-pressure roller press is started, this adjustment facility makes it easier to quickly reach the optimal operating state of the high-pressure roller press. 
         [0010]    In one embodiment of the invention it is provided that the rotary valves are disposed on a shaft which is variable in height above the roller nip. The height-variability of the shaft, and hence also of the rotary valves, allows the bulk material cone leaving the feed device to be altered, within the limits of the natural bulk material cone that is predefined by the material properties of the feed material, on the one hand, by the mechanical movement of the bulk material cone from below and, on the other hand, by the rotating rollers of the high-pressure roller press. This variation facility, too, offers operating staff the opportunity to configure the optimal bulk material cone over the roller nip, so that a low-vibration operation with minimum possible energy consumption is possible. 
         [0011]    In order to protect the shaft from excessive abrasion by ores or by non-comminuted cement clinker, in a further embodiment of the invention it is provided that the shaft is provided with an exchangeable inner lining as an abrasion protection. If the abrasion protection is eroded during operation, then the inner lining, which the lining and shaft lie one inside the other like two stacked together shafts, can be exchanged with comparatively little effort, and thus the shaft, which in addition to its shaft function must also deflect mechanical forces, can be protected from destruction. 
         [0012]    According to the invention, the rotary valves are adjustable by means of a hydraulic system. Although it is also possible to choose another type of drive, hydraulic operation has proved advantageous because it is robust enough to withstand the rough conditions associated with the grinding of brittle material. It is here provided that the hydraulic system acts on one side upon the rotary valve, and with the other side of the telescopic hydraulic system upon the shaft, which shaft can be varied in height above the roller nip. Insofar as the supply lines for the hydraulic systems are long enough and flexible, it is possible to raise and lower the shaft which is variable in height above the roller nip, in which case the hydraulic systems for the opening and closure of the rotary valves travel along with the shaft. 
         [0013]    According to the invention, the position of the shaft which is variable in height above the roller nip is adjusted via a further hydraulic system, in which case it has proved advantageous if at least one hydraulic system is respectively disposed on two opposite sides of the shaft. These hydraulic systems raise the entire shaft, on which there is arranged a funnel-shaped plate and into which conveyor belts or other conveying devices deposit the feed material. When the shaft which is variable in height above the roller nip is raised or relowered, the entire hopper, together with its content, the feed material present in the hopper, is thus raised or relowered. In addition to the lowering and raising of the whole of the hopper arrangement, it is also possible for the shaft to be telescopically configured and for the hopper not to travel along with the shaft. In this case, the telescopic shaft collapses and extends according to the direction in which the shaft is moving, but it has proved more advantageous if specifically this telescopic arrangement of the shaft is dispensed with. Abrasive feed material can too easily gather in the telescopic attachment and disturb the telescopic function. 
         [0014]    In one embodiment of the invention, it is provided that the shaft which is variable in height above the roller nip is adjustable in height above the roller nip via a hydraulic system, wherein the hydraulic system, on the one hand, acts upon a rack system which receives the shaft which is variable in height above the roller nip, and, on the other hand, acts upon the shaft which is variable in height above the roller nip. 
         [0015]    The hydraulic systems for raising and lowering the systems act, on the one hand, as closely as possible upon the shaft itself and, on the other hand, as closely as possible upon a vertical strut of a rack system within which the shaft moves up and down, in order to avoid buckling of the shaft in the rack system under mechanical load. According to the existing interspace between the shaft and the rack system, the hydraulic system is thus aligned almost vertically or at a slight vertical angle. 
         [0016]    Since the shaft is raised and relowered within the rack system by the hydraulic system, it is advantageous if the shaft is supported by a linear bearing within the rack system and, when raised and relowered, slides up and down within the linear bearing. The linear bearing consists in its simplest form of a U-profile, which is disposed on the shaft with its opening facing outward and in which a horizontal stay reaching from the rack system to the linear bearing engages; the stay is here fixedly connected to the rack system. The converse arrangement, too, is possible, in which the stay is fastened to the shaft and engages in a linear bearing on the rack system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The invention is explained in greater detail with reference to the following figures, wherein: 
           [0018]      FIG. 1  shows a high-pressure roller press with mounted feed device according to the present invention, 
           [0019]      FIG. 2  shows the feed device according to the invention, 
           [0020]      FIG. 3  shows a side view of the feed device, 
           [0021]      FIG. 4  shows a lower part of the shaft of the feed device as a detail, 
           [0022]      FIG. 5  shows the high-pressure roller press according to  FIG. 1 , with mounted rack system of the feed device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    In  FIG. 1  there is configured a high-pressure roller press  100 , on which a feed device  200  according to the present invention is mounted. The high-pressure roller press  100  has two rollers  101  and  102 , in this view the roller  102  being for the most part concealed, and the two rollers  101  and  102  form a roller nip  103  through which the feed material  104  (not represented here) passes, wherein the feed material  104 , during passage through the roller nip  103 , is comminuted by the high pressure prevailing therein. In order to be able to absorb the high forces which arise in the course of the high-pressure comminution, the rollers  101  and  102  are mounted in large-sized bearings  110 ,  111 ,  112  and in the bearing  113  (visible in  FIG. 5 ) which in  FIG. 1  is concealed by the drawing view, and the bearings  110 ,  111 ,  112  and  113  are for their part accommodated in a machine frame  120 , which slidingly fixes the four bearings  110 ,  111 ,  112  and  113 . Slidingly fixes means that the two rollers  101  and  102  are horizontally movable in order to be able to evade passages of non-comminutable material through the roller nip  103 . For the sliding mounting, depending on the embodiment of the high-pressure roller press  100 , either both rollers  101  and  102  are realized as loose rollers or one of the rollers  101  and  102  is a fixed roller and the respective other roller is a loose roller, the loose roller being arranged such that it is movable within the machine frame  120  relative to the fixed roller. For the high-pressure comminution, it is provided that the rollers  101  and  102  rotate in opposite directions, in this example the front roller  101  having the rotational direction indicated by the arrow  123  and the second roller  102 , corresponding thereto, having an opposite rotational direction. In order that the rollers  101  and  102  have no slip and do not grind together and thus rapidly suffer heavy wear, but instead only press, it is provided that the rollers  101  and  102  rotate as far as possible at the same, but oppositely directed rotation speed without relative slip. 
         [0024]    The feed device  200  is fixed to the upper crossbeams  121  and  122  with the aid of a rack system  201 , the rack system  201  forming a cage containing a shaft  202  which is variable in height above the roller nip  103 . The shaft  202  is here mounted in linear bearings  210 ,  211 ,  212  and  213  and is connected to the rack system  201  by hydraulic rams  220 ,  221 ,  222  and a hydraulic ram  223  which in this view is concealed. In order to raise the shaft  202 , the hydraulic rams  220 ,  221 ,  222  and  223  extend telescopically and thus lift the shaft  202  clear of the rack system  201 . In one embodiment of the invention, it is provided that on top of the shaft  202  is arranged a larger hopper, into which conveyor belts or other conveyors pour feed material  104 , which feed material is delivered by the feed device  200  evenly onto the roller nip  103 . In addition to varying the height of the shaft  202  above the roller nip  103 , it is also possible to vary the opening of the shaft  202  down to the roller nip  103  by means of two rotary valves  230  and  231 . 
         [0025]    The feed device  200  is represented in  FIG. 2  as a single structure and is illustrated in greater detail. The rack system  201 , within which is accommodated a shaft  202  which is variable in height above the roller nip  103 , is clearly apparent, the shaft  202  being connected to the rack system  201  by hydraulic rams  220 ,  221 ,  222  and  223 . In order to avoid buckling of the shaft  202  under the load of a hopper (not illustrated) mounted on the shaft  202 , the various hydraulic rams  220 ,  221 ,  222  and  223  are each supported on a vertical strut  240 ,  241 ,  242  and  243  and act upon the shaft  202  in its immediate vicinity. The hereby diagonal arrangement of the hydraulic rams  240 ,  241 ,  242  and  243  can be clearly seen in  FIG. 2 . In order to stabilize the vertical path of the shaft  202 , the shaft  202  is mounted in linear bearings  210 ,  211 ,  212 ,  213  with four horizontal stays  250 ,  251 ,  252  and  253 , which are fastened to the shaft  202 , engaging respectively in one of the linear bearings  210 ,  211 ,  212 ,  213 . Beneath the mounting in four linear bearings  210 ,  211 ,  212 ,  213 , the shaft  202  is mounted with further stays  254 ,  255 ,  257  and with the stay  256  which in this drawing is concealed, in lower linear bearings  214 ,  215 ,  217 , and in the linear bearing  216  which in this drawing is concealed, whereof only the linear bearings  215  and  217  which are facing forward to the right are visible in  FIG. 2 . Conversely to the above-described combination of linear bearings  210 ,  211 ,  212 ,  213  and stays  250 ,  251 ,  252  and  253 , the corresponding lower stays  254 ,  255 ,  257  and the non-visible stay  256  are fastened to the shaft  202  and the lower linear bearings  214 ,  215 ,  217  and  218  are supported on the vertical struts  240 ,  241 ,  242  and  243 . 
         [0026]    At the lower opening of the shaft  202  are located the two rotary valves  230  and  231 , which are opened and closed independently of each other by hydraulic rams  260  escorting the shaft  202 , and by the hydraulic ram  261  which corresponds thereto and which in this view is concealed. For this, the hydraulic rams  260  and  261  act with one end upon the shaft  202  and with respectively another end of the hydraulic ram  260  and  261  upon the rotary valves  230  and  231 . The fact that the two hydraulic rams  260  and  261  can be extended and retracted independently of each other allows the position of the two rotary valves  230  and  231  to be adjusted such that the center of the opening between the two rotary valves  230  and  231  is located directly above the roller nip  103  in the state installed in a high-pressure roller press  100 . This adjustability leaves enough clearance for a high-pressure roller press  100  equipped with this feed device  200  to be operated without vibrations in an optimal operating state. 
         [0027]    In order to avoid excessively rapid wearing by abrasion, it is envisaged to provide the shaft  202  with an inner lining  203  which is inserted in the shaft  202  and fastened to the flange  204 . A respectively corresponding abrasion protection  232  and  233  is present on the inner sides of the rotary valves  230  and  231  in order to protect the rotary valves  230  and  231 , exposed to considerable abrasive forces, from premature wearing. 
         [0028]    In  FIG. 3 , the shaft  202  inserted in the rack system  201  is represented in a side view, from which the working of the hydraulic rams  220 ,  221  and the concealed hydraulic rams  222  and  223  for the raising and lowering of the entire shaft  202 , on the one hand, and the working of the hydraulic rams  260  and  261  for the opening and closing of the rotary valves  230  and  231 , on the other hand, is more clearly apparent. By virtue of the side view, it can clearly be seen in  FIG. 3  that the center of the opening between the two rotary valves  230  and  231 , depending on the position of the rotary valves  230  and  231 , can also be located alongside the center ( 103 ′) above the roller nip  103 . It is here provided that the rotary valves  230 ,  231 , when symmetrically positioned, deliver the grinding stock  104  centrally above the roller nip  103  onto the high-pressure roller press  100  and, when non-symmetrically positioned, deliver the grinding stock  104  outside the center ( 103 ′) above the roller nip  103  onto the high-pressure roller press  100 . 
         [0029]    In  FIG. 4 , a lower part of the shaft  202  is represented, which here is illustrated without hydraulic rams  220 ,  221 ,  222  and  223  and without hydraulic rams  260  and  261 . The mounting of the rotary valves  230  and  231  in the bearings  234  and  235  and the configuration of the end faces  236  and  237  of the two rotary valves  230  and  231  serves to ensure that the rotary valves  230  and  231 , given a position in which the opening between the two rotary valves  230  and  231  is located outside the center above the roller nip  103 , do not block each other. 
         [0030]    The rack system  201  can be separated from the shaft  202  by detachment of the hydraulic rams  220 ,  221 ,  222  and  223  from the rack system  201 . In  FIG. 5 , the rack system  201  which has thus been separated is represented without moving elements and in  FIG. 5  is portrayed as fitted into the machine frame  120  of a high-pressure roller press. Following fitting of the rack system  201 , which is aligned exactly centrally over the roller nip  103  of the high-pressure roller press, the shaft  202  is hung in the rack system  201 , in which the hydraulic rams  220 ,  221 ,  222  and  223  connect the shaft  202  to the rack system  201  and support said shaft. 
         [0031]    As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art. 
       REFERENCE SYMBOL LIST 
       [0000]    
       
           100  high-pressure roller press 
           101  roller 
           102  roller 
           103  roller nip 
           104  feed material 
           110  bearing 
           111  bearing 
           112  bearing 
           113  bearing 
           120  machine frame 
           121  crossbeam 
           122  crossbeam 
           123  rotational direction 
           200  feed device 
           201  rack system 
           202  shaft 
           261  hydraulic ram 
           203  inner lining 
           204  flange 
           204 ′ flange 
           210  linear bearing 
           211  linear bearing 
           212  linear bearing 
           213  linear bearing 
           214  linear bearing 
           215  linear bearing 
           216  linear bearing 
           217  linear bearing 
           220  hydraulic ram 
           221  hydraulic ram 
           222  hydraulic ram 
           223  hydraulic ram 
           230  rotary valve 
           231  rotary valve 
           232  abrasion protection 
           233  abrasion protection 
           234  bearing 
           235  bearing 
           236  end face 
           237  end face 
           240  strut 
           241  strut 
           242  strut 
           243  strut 
           250  stay 
           251  stay 
           252  stay 
           253  stay 
           254  stay 
           255  stay 
           256  stay 
           257  stay 
           260  hydraulic ram