Abstract:
A component assembly is provided for converting a conventional centrifugal pump, of the vortex impeller type for example, to a different type of centrifugal pump, such as a spiral impeller pump. The component assembly enables a resident centrifugal pump to be converted to a more efficient or appropriate type of industrial pump when conditions or application processing requirements change, and avoids the need to entirely replace an installed pump for a new type of pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a non-provisional application claiming priority to provisional patent application Ser. No. 60/475,104 filed Jun. 2, 2003. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     This invention relates to centrifugal pumps of the industrial type and specifically relates to providing an assembly of components for converting a centrifugal pump having a vortex-type impeller to a centrifugal pump having a spiral-type impeller for expanding the usefulness of the pump and increasing pump operation.  
         [0004]     2. Description of Related Art  
         [0005]     Centrifugal pumps are used in many industries to pump either clear water or slurries, the latter of which contain both fluid and solid components. The solids content of slurries vary in type and size, but all slurries are abrasive to some degree on the components of the pump. Therefore, centrifugal pumps are structured with varying abilities to withstand the varying degrees of abrasiveness of slurries. Pumps are consequently selected for their ability to process slurries of a given abrasiveness.  
         [0006]     A centrifugal pump of the vortex type is one example of a slurry pump that is particularly constructed to process very abrasive slurries. The impeller of a vortex pump is made of very hard metal materials to withstand highly abrasive types of slurries. The impeller is particularly shaped to receive the influent slurry so that the solids content is processed by the impeller in a manner that reduces the impact of the solids on the impeller, thereby lessening the degradation of the impeller. The impeller may be configured with recessed areas between the impeller vanes which further contribute to the ability to process the slurry while lessening the impact of the solids on the impeller. Such impellers are known as recessed vortex impellers.  
         [0007]     While vortex impellers are well-suited for their intended purpose, it is a natural consequence of the construction of vortex impellers, especially recessed vortex impellers, that certain pump efficiency is sacrificed due to the fact that the impeller is recessed from the main flow path of the fluid entering the pump. Occasions arise where the nature of the slurry being processed in a given installation changes, such as in a municipal waste facility. While the vortex centrifugal pump that is installed in the facility may still be operational, the fact that a vortex pump is less efficient than other types of centrifugal pumps becomes problematic to the optimal operation of the plant. In many instances, the vortex pump may be shut down and the installation modified to bypass the vortex pump in favor of processing the influent in a more efficient manner.  
         [0008]     Thus, it would be beneficial in processing industries to provide a means by which a less efficient vortex centrifugal pump may be converted to a more efficient type of centrifugal pump responsive to a change in the type of slurries being processed, and in doing so employ the same pump casing and drive system of the existing vortex centrifugal pump to avoid having to replace the entire pump or having to modify the entire installation, both of which are extremely costly to plant operation.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     In accordance with the present invention, a components assembly is provided for replacing the vortex-type impeller and related elements of a vortex-type centrifugal pump to convert the centrifugal pump to a more efficient type of pump, such as a spiral impeller-type centrifugal pump, using the same pump casing, drive assembly and seal assembly of the existing centrifugal pump. The components assembly of the present invention is adaptable for use in converting virtually any centrifugal pump of one impeller type to a centrifugal pump of a different impeller type, but is described herein by way of example only with respect to converting a vortex impeller pump to a spiral impeller pump.  
         [0010]     The component assembly of the present invention generally comprises a new and different type of impeller that is selected to replace the current impeller of the centrifugal pump for improved or application-adapted operation. The component assembly also includes a back plate for positioning between the new impeller and the drive side casing of the pump casing to adapt the new impeller to the pump casing. A back plate may not always be necessary in that the new impeller may be configured especially to be adapted to an existing pump casing.  
         [0011]     The component assembly of the present invention also may comprise a suction cover that is adapted to the new and different type of impeller of the component assembly. The suction cover is configured for attachment to the existing pump casing. The component assembly may not necessarily include a new suction cover if the original suction cover of the pump can be used and/or adapted to the new type of impeller that is installed in the existing pump casing. It may require a special designing of the new impeller to accommodate the existing suction cover, however.  
         [0012]     The back plate and suction cover of the component assembly of the present invention are particularly structured and configured for attachment to the existing pump casing of the centrifugal pump. That is, they are structured with attachment points for securement, usually by means of bolts or pins, to the pump casing.  
         [0013]     In some pump conversions, depending on the type of new impeller being installed in the existing pump casing, the component assembly of the present invention may also include an impeller adapter member, or impeller flange, to adapt the new impeller to the back plate of the component assembly or to the existing pump casing of the pump. An impeller adapter member may not always be required to effect the conversion, however.  
         [0014]     The component assembly of the present invention allows an existing centrifugal pump in an installation to be converted to a more efficient type of pump without having to remove and replace the entire pump from the installation, and allows the existing pump to have continued use in the installation rather than having to modify the installation to avoid use of the less efficient vortex pump, which substantially affects plant operation and cost efficiencies. The present invention also allows the use of existing piping dimensions which advantageously effects operation and cost efficiencies. These and other advantages of the present invention are described further in the detailed description of the drawings.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0015]     In the drawings, which illustrate what is currently considered to be the best mode for carrying out the invention:  
         [0016]      FIG. 1  is a longitudinal cross section of a conventional vortex-type centrifugal pump;  
         [0017]      FIG. 2  is an exploded view of the main components of a conventional vortex-type centrifugal pump;  
         [0018]      FIG. 3  is an exploded view of the elements of the conversion assembly of the present invention providing conversion of the centrifugal pump from a vortex impeller to a spiral impeller; and  
         [0019]      FIG. 4  is a longitudinal cross section of a centrifugal pump as shown in  FIG. 3  that has been converted by means of the present invention to a spiral impeller pump. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]      FIGS. 1 and 2  illustrate the general structural elements of a centrifugal pump  10  of the prior art, and in particular, a centrifugal pump  10  of the type having a vortex impeller. The vortex pump  10  generally comprises a drive side casing  12  and a volute casing  14  which is bolted on to the drive side casing  12 . The drive side casing  12  includes a bearing housing  16  and a pedestal portion  18  having feet  20  for anchoring the drive side casing  12  to a surface, such as a floor. The bearing housing  16  houses a forward bearing assembly  26  and a rear bearing assembly  28  which support a drive shaft  30  extending through the drive side casing  12 . The drive shaft  30  also extends through a seal assembly  32  that is located in or near the end plate  34  of the drive side casing  12 .  
         [0021]     The vortex centrifugal pump  10  further comprises a wear plate  36  that registers against and is bolted to the drive side casing  12 , as best shown in  FIG. 1 . The wear plate  36 , as best shown in  FIG. 2 , is bowl-shaped to receive the back side  38  of the impeller  40 . The wear plate  36  is formed with a central opening  42  through which the terminal end  44  of the drive shaft  30  extends. The impeller  40  is also formed with a central opening  46  into which the terminal end  44  of the drive shaft  30  is received. As best seen in  FIG. 1 , the impeller  40  is secured to the drive shaft  30  by a threaded bolt  48  that is threadingly received in the terminal end  44  of the drive shaft  30 .  
         [0022]     The vortex pump  10  also comprises a suction side cover  50  that bolts on to the volute casing  14 . The suction side cover  50  has a centrally formed opening that defines the inlet  52  of the pump  10 . It can be seen that slurry entering the pump  10  through the inlet  52  encounters the rotating vortex impeller  40  and is conveyed to the volute  54  of the pump  10 , and then exits through the outlet  56  of the pump  10 .  
         [0023]     The component assembly  60  of the present invention is shown in  FIG. 3 , which is an exploded perspective view of a reconfigured centrifugal pump  62 . The component assembly  60  may generally comprise a back plate  64 , an impeller adapter  67 , a new and differently configured impeller, shown here as a spiral-type impeller  68 , and a newly configured suction side cover  70 . In all other respects, the reconfigured centrifugal pump  62  is comprised of the same elements of the existing pump (i.e., drive side casing  12 , volute casing  14 , drive shaft  30 , etc.) as noted by the use of the same reference numerals to designate parts.  
         [0024]     As best seen in  FIG. 4 , the back plate  64  of the component assembly is sized to be received in the circumferential drive side opening  72  of the volute casing  14  and to register against, and be bolted to, the end plate  34  of the drive side casing  12 . The back plate  64  is formed with a centrally-positioned opening  74  through which the terminal end  44  of the drive shaft  30  extends. The back plate  64  is provided to facilitate adaptation of the new impeller  68  to the existing pump casing  12 ,  14 . However, a back plate  64  may not be required in all applications, especially where the new impeller may be particularly designed for placement in an existing pump of known configuration.  
         [0025]     An impeller adapter  67  may also be provided as part of the component assembly  60  of the present invention to adapt the new type impeller to the existing pump casing  12 ,  14 . The impeller adapter  67  may be configured for use alone or in tandem with a back plate  64  as illustrated. The impeller adapter is shown in  FIG. 4  as an impeller flange  66  which is structured with an axially extending collar  76  that is sized to be received in, and to extend into, the centrally-positioned opening  74  of the back plate  64 . The impeller flange  66  is structured to register against the back plate  64  and to be positioned between the impeller  68  and the back plate  64 . The impeller adapter  67  may be any suitable shape for adaptively securing the new impeller  68  to the existing pump casing  12 ,  14 . The impeller flange  66  is illustrated as having a conically-shaped side  69  that is configured to be received in or against the new impeller  68 .  
         [0026]     The new impeller  68  may, in turn, be secured to the impeller flange  66  by means such as bolts or pins  78 . The impeller flange  66  is also formed with a central opening  80  for receipt of the terminal end  44  of the drive shaft  30  therein. The central opening  80  is axially aligned with a central opening  82  formed in the new impeller  68  through which a threaded bolt  84  is extended to secure the new impeller  68  to the terminal end  44  of the drive shaft  30 .  
         [0027]     The new impeller  68  of the present invention may be virtually any type of impeller that is suitable for use in a centrifugal pump. The new impeller  68  illustrated in  FIGS. 3 and 4  is a spiral-type impeller, by way of example only. A spiral-type impeller  68  is capable of processing mild or slightly abrasive slurries, but is also capable of providing comparatively greater pump efficiencies than a vortex pump. A spiral-type impeller  68  operates in a similar manner, however, to convey slurry entering through the inlet  52  of the pump  62  to the outlet  56  of the pump  62 .  
         [0028]     The component assembly of the present invention may also include a suction side cover  70  which is likewise configured to accommodate the configuration of the new impeller, or spiral-type impeller  68 , as shown in  FIG. 4 . The suction side cover  70  is formed with a central opening  90  which defines the inlet  52  of the pump  62 . The configuration of the suction side cover  70  is not only important to accommodating the shape and size of a new impeller  68 , but may also be important to the proper processing of the slurry from the inlet  52  to the outlet  56  of the pump  62 . However, it may be possible in some applications to use the existing suction side cover of the pump with a new impeller  68  type.  
         [0029]     In converting the existing centrifugal pump  10  from, for example, a vortex impeller type to a spiral impeller type, in accordance with the invention, the old suction side cover  50  is unbolted from the volute casing  14 , the vortex impeller  40  is unbolted from the terminal end  44  of the drive shaft  30  and the impeller  40  is removed from within the wear plate  36 . The wear plate  36  is then unbolted from the drive side casing  12  and is removed. All other components of the pump remain in place, including the drive shaft  30 .  
         [0030]     The back plate  64  of the component assembly  60  of the present invention is then positioned within the circumferential drive side opening  72  of the volute casing  14  and registered against the drive side casing  12 . The back plate  64  is then bolted in place against the drive side casing  12 . The impeller flange  66  is next positioned over the terminal end  44  of the drive shaft  30  with the axially-extending collar  76  positioned through the central opening  74  of the back plate  64 . The spiral impeller  68  is then positioned over the impeller flange  66  and is secured to the terminal end  44  of the drive shaft  30 . The new suction side cover  70  is then positioned against and bolted to the volute casing  14  as shown. The newly configured pump  62  is then ready for operation  
         [0031]     The component assembly of the present invention is provided for configuring an existing centrifugal pump of one type, defined by the type of impeller installed in the pump, to a new type of centrifugal pump having a different type of impeller. The component assembly thereby enables the conversion of an existing centrifugal pump to a new type of pump that can meet changes in pumping applications, or increase pumping efficiencies in a resident installation or pumping application. By enabling the conversion of a resident centrifugal pump to a new type of pump, operation costs are significant reduced since a whole new pump does not need to be installed and the amount of down-time required to provide the installation with a better or more efficient pump is significantly reduced.  
         [0032]     Thus, the component assembly of the present invention can be adapted for use in converting virtually any type of centrifugal pump to a new type of pump. Hence, reference herein to specific details of the invention, particularly as may be illustrated in the drawings is by way of example only and not by way of limitation.