Patent Abstract:
The invention relates to a method for conveying a solid ( 2 ) in a conveying medium ( 15 ), said solid ( 2 ) being delivered to a container ( 5 ) with outlet ( 7 ). The solid ( 2 ) is in this case dispersed in the transport liquid ( 15 ) without the aid of any mechanically driven parts and is introduced into the conduit ( 4 ).

Full Description:
BACKGROUND OF THE INVENTION 
     (1) Field Of The Invention 
     The invention relates to a method of conveying a solid in a conveying medium ( 15 ) in which the solid is delivered to a container having an outlet ( 7 ) and the conveying medium that flows into the container generates a downwardly rotating current ( 17 ) so that the solid is delivered by the conveying medium to the outlet. More particularly the invention provides for the delivery of a solid in a conveying medium into a container having an outlet so that the downwardly rotating current provides a spiral trajectory directed sharply downward to the outlet of the container. 
     (2) Description of Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98 
     It is known, for example from DE 197 55 732 C2, to transport a dispersion of granules and water through a conduit. To produce a dispersion of solid and liquid, it is known to first introduce the solid into a container filled with liquid and to mix it with the liquid using a mechanical stirrer. The mixture of solid and liquid is then drawn off from the bottom of the container. This is done using a centrifugal pump, which pumps the solid/liquid mixture from its axial inlet opening to the tangential outlet opening and into the conduit. 
     A disadvantage of this method is that the solid is subjected to mechanical stresses, both by the stirrer arranged in the container and by the pump, and these stresses lead to undesired attrition of the solid and/or to damage of sensitive solid particles. This method has a particularly disadvantageous effect on a solid whose specific weight is less than the specific weight of the liquid which is being used to transport the solid, because the solid of lower specific weight tends, as in a centrifuge, to accumulate at the center of the impeller of the centrifugal pump. The efficiency of the pump deteriorates as a result, because the solid has to be forced away from the center of the impeller. Moreover, the solid is subjected to particularly high mechanical stresses because the individual particles of solid which accumulate at the center of the pump rub against one another. In the container too, the solid of lower specific weight is subjected to increased stress because the mechanical stirrer forces it toward the discharge opening at the bottom counter to the lifting force. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to develop a method in which the solid is dispersed in the transport liquid and introduced into the conduit without the aid of mechanically driven parts, and which method requires minimum maintenance and in particular allows solids of lower specific weight to be conveyed hydraulically without high mechanical stresses. 
     Starting from the features of the method of conveying a solid in a conveying medium delivered to a container with an outlet this object is achieved, according to the invention, by the generation of a downwardly rotating current so that the solid is delivered to the outlet by the conveying medium. Advantageous and preferred developments include the method of utilizing the medium to generate the rotating current to flow tangentially as much as possible and delivering the solid through a metering device and utilizing solids of greater, lesser and equal density to the conveying medium and other objects and advantages as will become apparent to those skilled in the art. 
     In this method, the conveying medium, for example water, flowing into the container designed as a sender container generates a downwardly rotating current, and the solid is delivered by the conveying medium to the outlet. With the conveying medium being carried in a spiral trajectory directed sharply downward to the outlet, the solid which impinges on the conveying medium is entrained by said conveying medium and leaves the sender container together with the conveying medium and passes into a conduit. No mechanism of movement is needed in the sender container in order to produce this kind of current, and, accordingly, there is no contact causing attrition and stresses between the individual particles of the solid and moving mechanical components, for example a stirrer or an impeller of a pump. 
     By generating the current using a conveying medium which flows in tangentially to the greatest possible extent, it is possible to generate the current in the container without structural space being needed for this purpose in the container. 
     Feeding the solid into the container via a metering device allows conveying medium and solid to be exactly adapted to each other and, by this means, it is possible to obtain a ratio of liquid to solid, in the mixture of solid and liquid, which is optimum for hydraulic delivery. 
     In an advantageous embodiment of the subject of the invention, it is possible to convey solids whose density is less than or greater than or approximately the same as the density of the conveying medium. In this way, a very wide variety of solids can be conveyed with just one method, and the method does not have to be modified to convey a solid of different density. 
     By generating a current with a pumping action, the mechanical pump for maintaining the circulation of the conveying medium can be arranged at a location where it only has to convey pure conveying medium. Thus, irrespective of the solid which is to be conveyed, the pump can be optimized for conveying a specific conveying medium. 
     Because the conveying medium present in the sender container is driven by the conveying medium which flows anew into the sender container, the direction of rotation of the conveying medium in the sender container can be generated and maintained solely by the flow energy of the inflowing conveying medium. 
     The subject of the invention also proposes delivering the stream of conveying medium to an outlet along a spiral trajectory of an in particular rotationally symmetrical and in particular tapering sender container. A kind of cyclone thus develops in the container, which cyclone, in contrast to a cyclone separator, has only one outlet. In other words, the flow-generated rotation of the conveying medium in the container results in the formation of a vortex which flows off into one outlet. 
     In an advantageous embodiment of the subject of the invention, the sender container is designed tapering toward the outlet. The conical design of the sender container favors the formation of a flow of liquid along a narrowing spiral trajectory, because this flow of liquid is guided by the container wall. 
     It is advantageous if the conveying medium present as a liquid flows into the container, via a delivery nozzle, approximately parallel to the wall of the container and approximately perpendicular to a container axis. This ensures that the flow of liquid seen as a whole follows the wall of the container like an annular peripheral layer and is guided by said wall. The angle of inclination of the spiral trajectory can be influenced by the angle which the delivery nozzle forms with a plane extending perpendicular to the longitudinal axis of the container. 
     According to a particular embodiment of the method according to the invention, the solid, which for example can be granules of plastic, is introduced into the sender container via a star feeder. In this way, it is also possible to work using a sender container in whose interior the pressure is elevated in relation to the ambient pressure. 
     According to the invention, it is further provided for the solid to be delivered to the container in an area through which the conveying medium does not flow. To this end, it suffices for the container to have a simple opening through which solid is delivered. 
     It is particularly advantageous to deliver the solid specifically to a hollow cone which is formed by the conveying medium moving on a spiral trajectory, because the entire jacket surface of the hollow cone is available as a delivery surface for the solid and the solid is conveyed from the conical jacket surface to the outlet or to the container axis. 
     In a particular embodiment of the subject of the invention, the solid is delivered as a solid/liquid mixture to the conveying medium. In this way it is possible also to convey solids which are already present as a solid/liquid mixture. 
     In a preferred embodiment, the device according to the invention has a container which narrows toward the outlet and comprises a delivery nozzle for a liquid conveying medium, which nozzle is oriented substantially perpendicular to a main axis of the container and parallel to the container wall. With a delivery nozzle arranged in this way, it is easily possible to produce a flow of liquid running on a spiral trajectory along the container wall to the outlet. 
     In a further advantageous embodiment of the device, a plurality of delivery nozzles are arranged on the container wall and preferably lie in a plane perpendicular to the longitudinal axis of the container. In this way it is possible to have larger quantities of liquid flowing into the container, which quantities of liquid are guided by the container wall and combine to form a common, suctioning spiral flow. 
     It is also advantageous to define the profile of the current in the sender container by changing the cross section of admission. In this way, the delivery installation can be adjusted for conveying different solids. 
     In a modification of the invention, the level of the conveying medium in the sender container is adjusted by means of a gas pressure regulator. In this way it is possible to influence the filling level in the container and ensure that the conveying medium does not rise into the metering unit arranged above the container. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Further details of the invention are described with reference to the drawing which shows diagrammatic views of illustrative embodiments. In the drawing: 
         FIG. 1  shows a diagrammatic view of an installation for hydraulic conveying, 
         FIG. 2  shows a diagrammatic cross section of a sender container, 
         FIG. 3  shows a diagrammatic cross section of a further sender container, 
         FIG. 4  shows a cross section, along the line IV—IV, through the sender container shown in  FIG. 3 , 
         FIG. 5  shows a cross section through a further sender container, 
         FIG. 6  shows a cross section through a sender container with an adjustable cross section of admission. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a diagrammatic view of an installation  1  for hydraulic conveying of solid  2 . The installation  1  consists principally of two reservoirs  3  which are connected to one another via a conduit  4 , one reservoir  3  being designed as the container  5 , and the other reservoir  3  being designed as a receiver container  6 . The container  5  opens into the conduit  4  via an outlet  7 . This conduit  4  opens into the receiver container  6  via an inlet  8 . The container  5  is connected to the receiver container  6  via a delivery line  9  in which motor-driven pumps  10  are arranged. An admission line  12  opening into a container lid  11  also connects the container  5  to a storage container  13  in which the solid  2  is held in readiness. The solid  2  is delivered to the container  5  via a metering device  14 . Conveying medium  15  present in the admission line  9  is conveyed with the aid of the pumps  10  in arrow direction x 1  and passed into the conveying medium  15  located in the container  5  via a nozzle  16  which is arranged tangentially with respect to the container  5  of round cross section. The introduction of the conveying medium  15  into the container  5  creates a current  17  in the latter, which current rotates about a container axis  18  to the outlet  7 , said outlet  7  being arranged in a conically tapering base  19  of the container  5 . The solid  2  which is of lower specific weight than the conveying medium  15  is shaken by the metering device  14  through a free space  20  and onto the conveying medium  15  located in the container  5  and is guided by the current  17 , as in a centrifuge, toward the container axis  18 , and drawn in arrow direction x 2  to the outlet  7  of the container  5 . 
     The solid  2  leaves the outlet  7 , together with the conveying medium  15 , as a solid/liquid mixture  21  which has been generated in the current  17  and passes through the conduit  4  in arrow direction X 3 . The solid/liquid mixture  21  passes through the inlet  8  into the receiver container  6  which is designed as a separator  22 . In the separator  22 , the solid/liquid mixture  21  is divided into solid  2  and conveying medium  15 . The solid  2  leaves the separator  22  by way of a pipe  23 . The conveying medium  15  passes into the delivery line  9  in which is it conveyed back to the container  5  by means of the pumps  10  and in this way moves in a conveying medium circulation  24 . 
     According to an alternative embodiment which is not shown, provision is made for the receiver container to be designed as a receiver/sender container, in which case the conveying medium is at least partially removed from the solid in an upper part of the container, and, in a lower part of the container, a flow of liquid is formed by inflowing conveying medium, analogously to the sender container, and the solid or the solid/liquid mixture can be pumped into a further container via this flow of liquid. Of course, the separation of the suspension and the further conveying can also take place in separate containers. Large conveying distances can thus be achieved by arranging sender and receiver containers in succession. If appropriate, intermediate reservoirs can also be provided. 
       FIG. 2  shows a diagrammatic cross section of a container  5  which serves as a dispersing container. A level  25  of a conveying medium  15  present in the container  5  is maintained substantially constant by a gas pressure regulator  26 . If the level  25  of the conveying medium  15  rises above a filling level H 1 , the pressure in a free space  20  of the container is then increased by means of the gas pressure regulator  26 , so that continued flow of conveying medium  15  from a delivery line  9  through a nozzle  16  into the container  5  is at least partly prevented. The free space  20  is acted upon by gas via a gas line  27  and via a control valve  28  which is assigned to the gas line  27  and is regulated by the gas pressure regulator  26 . If the level  25  of the conveying medium  15  drops below a filling level H 2 , the pressure in a free space  20  of the container  5  is then reduced by means of the gas pressure regulator  26 , so that there is less resistance to the conveying medium  15  flowing from the delivery line  9 . 
       FIG. 3  shows a diagrammatic cross section of a further container  5 . Arrows  29  indicate the typical profile of a current  17  generated by a conveying medium  15  passing tangentially from a delivery line  9  into the container  5  via a nozzle  16 . The conveying medium  15  flows from one container wall  30  toward a container axis  18 , at the same time moving in an arrow direction x 2  toward an outlet  7  of the container  5 . Thus, the conveying medium  15  has an axial component of velocity V A  and a radial component of velocity V R . By means of the current  17 , the conveying medium  15  forms, on one surface  15 ′, a cone-shaped funnel  38  by which the solid  2  impinging on the surface  15 ′ is already guided to the container axis  18  or in the direction of the outlet  7 . 
       FIG. 4  shows a diagrammatic cross section of the container  5  shown in  FIG. 3 , with an arrow  31  symbolizing the current  17  formed in this container  5 . The conveying medium  15  delivered via the delivery line  9  and through the nozzle  16  flows on a spiral trajectory  32  along the container wall  30  toward the outlet  7  and thus has a tangential component of velocity V T . The conveying medium  15  and the solid  2  have axial, radial and tangential components of velocity V A , V R , V T , with the velocity increasing toward the outlet  7 . 
       FIG. 5  shows a diagrammatic cross section of a further container  5 . In said container  5 , there are three nozzles  16  through  16 ″ which are arranged at the same height on a container wall  30 . The nozzles  16  through  16 ″ generate jets  33  through  33 ″ which run on spiral trajectories  32  through  32 ″ in the direction of a container axis  18  or spiral axis  18 ′ (indicated by an arrow end  34 ) to an outlet  7 . 
       FIG. 6  shows a cross section of a container  5  with a delivery line  9  which has a nozzle  16  with a variable cross section of admission A. The cross section of admission A can be adjusted by a flap  35  which can turn about a hinge  36  in arrow directions  37 . Depending on the difference in density between solid  2  and conveying medium  15 , the components of velocity V A , V R , V T  can be varied by the configuration of the cross section of admission A. 
     The illustrative embodiments have been described on the assumption that the conveying medium used is water and that the material to be conveyed is plastic granules which are lighter than or about equally as light as water. 
     The invention is not limited to the illustrative embodiments shown or described. Instead, it includes developments of the invention within the scope of the patent claims. In particular, the invention also provides for solid to be conveyed which has a heavier specific weight than the conveying medium. In this case, the rotating current ensures that the solid is moving in rotation before it passes through the outlet of the container, by which means blockages are effectively counteracted. 
     In a further alternative embodiment which is not shown, the spiral current is formed in a pipe, preferably by guide plates, and the solid is delivered to the rotating flow of liquid by way of, for example, a conduit or a star feeder. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  installation 
           2  solid 
           3  reservoir 
           4  conduit 
           5  container 
           6  receiver container 
           7  outlet 
           8  inlet 
           9  delivery line 
           10  pump 
           11  container lid 
           12  delivery line 
           13  storage reservoir 
           14  metering device 
           15  conveying medium 
           15 ′ surface 
           16  nozzle 
           17  current 
           18  container axis 
           19  base 
           20  free space 
           21  solid/liquid mixture 
           22  separator 
           23  pipe 
           24  conveying medium circuit 
           25  level 
           26  gas pressure regulator 
           27  gas line 
           28  control valve 
           29  arrow 
           30  container wall 
           31  arrow 
           32  spiral trajectory 
           33  jet 
           34  arrow end 
           35  flap 
           36  hinge 
           37  arrow direction 
           38  funnel

Technology Classification (CPC): 1