Patent Publication Number: US-8979476-B2

Title: Wear reduction device for rotary solids handling equipment

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATION 
     This application claims benefit to patent application Ser. No. 61/366,319, filed 21 Jul. 2010, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a pump or pumping assembly, arrangement or combination; and more particularly, to an improvement to an impeller and suction liner combination used therein. 
     2. Description of Related Art 
     In pumps used for solids handling, the primary cause of reduced life and premature failure is recirculation from the outer diameter of the impeller to the suction of the impeller. The solids in the flow abrade and erode the impeller and suction liner, reducing their ability to seal and increasing the severity of the problem as additional wear occurs. 
     SUMMARY OF THE INVENTION 
     According to some embodiments, the present invention may take the form of apparatus, such as a pump or pumping assembly, arrangement or combination for solids handling, comprising a suction liner in combination with an impeller. The suction liner has a suction liner spiral design. The impeller has forward curved impeller suction side pump out vanes. The suction liner spiral design and the forward curved impeller suction side pump out vanes are configured to handle solids so as to exclude abrasive solids from an impeller/suction side liner gap by increasing the resistance to slurry flow from a high pressure area at the periphery of the impeller, and expel the solids which do manage to enter the impeller/suction side liner gap by guiding the solids away from a suction eye of the impeller, so that abrasive erosion is substantially prevented to significantly reduce wear and a tight clearance is substantially maintained at the impeller/suction side liner gap between the impeller and the suction liner, which substantially prevents degradation of pump performance through excessive leakage. 
     According to some embodiments of the present invention, the suction liner spiral design and the forward curved impeller suction side pump out vanes are configured to handle solids substantially have a weight concentration (Cw)&lt;about 40% and/or a solids size distribution &lt;about 200 microns. 
     According to some embodiments, the present invention may also include one or more of the following features: 
     The suction liner spiral design may be configured with at least one of the following: one spiral or at least two overlapping spirals. 
     Each overlapping spiral may be configured to start at an outer periphery of an inner rim of the spiral liner and end at an outer rim or periphery of the suction liner. 
     Each overlapping spiral may be configured to start at an outer periphery of the inner rim of the spiral liner and end at an intermediate location between the inner rim and the outer rim or periphery of the suction liner. 
     The two overlapping spirals may be configured to start at opposite sides of an outer periphery of the inner rim and end at opposite sides of the outer rim or periphery. 
     The impeller may be configured with an inner rim and an outer rim or periphery, and the forward curved impeller suction side pump out vanes may extend from the inner rim and end at the outer rim or periphery. 
     The forward curved impeller suction side pump out vanes may also be spaced equidistantly about the impeller face. 
     The suction liner spiral design may be configured with an outside diameter that is dimensioned relative to a suction liner outside diameter based at least partly on a percentage of best efficiency flow pumped by the pump. 
     The dimension of the outside diameter of the suction liner spiral design relative to the pump liner outside diameter may be inversely related to the change in the percentage of the best efficiency flow pumped by the pump. 
     The dimension of the outside diameter of the suction liner spiral design relative to the pump liner outside diameter may be reduced if the percentage of the best efficiency flow pumped by the pump is increased. 
     The dimension of the outside diameter of the suction liner spiral design relative to the pump liner outside diameter may be increased if the percentage of the best efficiency flow pumped by the pump is decreased. 
     The present invention disclosed herein assists in moving solids away from the area in question and thereby improving both the service lifespan and efficiency of a pump or pumping assembly, arrangement or combination. This technology is an improvement of the technology disclosed in an earlier filed patent application no. WO 2005/038260 A1, corresponding to U.S. Pat. No. 7,766,605, assigned to the assignee of the instant patent application. 
     For example, experimentation has indicated that forward curved pump out vanes have a wear reducing effect in some situations, as do relationships between the spiral design, pump out vane design, solids size distribution, and solids concentration by volume or weight:
         For Cw&lt;about 40%, forward curved pump out vanes combined with a spiral-equipped suction liner reduce wear significantly.   For solids with D 80 &lt;about 200 microns, forward curved pump out vanes combined with a spiral-equipped suction liner also reduce wear significantly, where the parameter D 80  is understood to be essentially the screen opening size that about 80% of the slurry&#39;s particles will pass through.   For Cw&gt;about 50%, back curved pump out vanes combined with a spiral-equipped suction liner reduce wear significantly.   As the percentage (%) of best efficiency flow pumped by the pump changes (e.g. from a range of about 50% to 80% of Q BEP ), reducing the outside diameter of the spiral relative to the outside diameter of the suction liner reduces suction liner wear.       

     In slurries with a greater percentage (%) concentration by weight or volume, prevention of all suction side leakage is paramount. The designs disclosed herein act to exclude abrasive solids from the impeller/suction side liner gap by increasing the resistance to slurry flow from the high pressure area at the impeller periphery. The designs disclosed herein also expel solids which do manage to enter the gap by guiding them away from the suction eye of the impeller. By both expelling and excluding solids, abrasive erosion is substantially prevented and a tight clearance is substantially maintained at the gap between the impeller and suction side liner, which substantially prevents degradation of pump performance through excessive leakage. 
     These and other features, aspects, and advantages of embodiments of the invention will become apparent with reference to the following description in conjunction with the accompanying drawing. It is to be understood, however, that the drawing is designed solely for the purposes of illustration and not as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings, which are not necessarily to scale, include the following Figures: 
         FIG. 1  is a perspective view of part of a pump or pumping assembly, arrangement or combination having an impeller (shown in cross-section) and a suction liner, according to some embodiments of the present invention. 
         FIG. 2   a  is a plan view of a suction liner spiral design for about 50% best efficiency point (BEP) operation according to some embodiments of the present invention. 
         FIG. 2   b  is a plan view of a suction liner spiral design for about 80% BEP operation according to some embodiments of the present invention. 
         FIG. 3   a  is a plan view of forward curved impeller suction side pump out vanes according to some embodiments of the present invention. 
         FIG. 3   b  is a plan view of rear curved impeller suction side pump out vanes according to some embodiments of the present invention. 
         FIG. 4  is a cross-sectional view of part of a pump or pumping assembly, arrangement or combination having an impeller and a suction liner, according to some embodiments of the present invention. 
     
    
    
     In the following description of the exemplary embodiment, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration an embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized, as structural and operational changes may be made without departing from the scope of the present invention. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows part of an impeller and suction liner combination generally indicated as  10  having an impeller  12  having an impeller face  120 , a suction liner  14  having a suction liner face  140  and a shaft  16  arranged in the impeller  12 , according to some embodiments of the present invention. Embodiments of suction liners  14 ′,  14 ″ are shown in greater detail in  FIGS. 2   a  and  2   b , each having a suction liner face  140 ′,  140 ″ with a suction liner spiral design generally indicated by arrows  144 ,  146 . Embodiments of impellers  12 ′,  12 ″ are shown in greater detail in  FIGS. 3   a  and  3   b , each having respective impeller faces  120 ′,  120 ″ with forward curved impeller suction side pump out vanes  122  or rearward curved impeller suction side pump out vanes  124 ). Embodiments are also envisioned in which the impeller has straight impeller suction side pump out vanes within the spirit of the present invention. The combination is configured to form part of a pump or pumping assembly, arrangement or combination shown in  FIG. 4 . 
     According to some embodiments of the present invention, the suction liner spiral designs  142  ( FIG. 1 ),  144  ( FIG. 2   a ), and  146  ( FIG. 2   b ), and the forward curved impeller suction side pump out vanes  122  are configured to handle solids, e.g., substantially having a weight concentration (Cw)&lt;about 40% and/or a solids size distribution &lt;about 200 microns, so as to exclude abrasive solids from an impeller/suction side liner gap by increasing the resistance to slurry flow from a high pressure area at the periphery of the impeller, and expel the solids which do manage to enter the impeller/suction side liner gap by guiding the solids away from a suction eye of the impeller, so that abrasive erosion is substantially prevented to significantly reduce wear and a tight clearance is substantially maintained at the impeller/suction side liner gap between the impeller and the suction liner, which prevents degradation of pump performance through excessive leakage. 
     FIGS.  2   a ,  2   b    
       FIG. 2   a  shows a suction liner spiral design generally indicated by the arrow  144  for about 50% best efficiency point (BEP) operation according to some embodiments of the present invention, where the suction liner spiral design  144  includes two overlapping spirals  144   a  and  144   b.    
       FIG. 2   b  shows a suction liner spiral design generally indicated by the arrow  146  for about 80% best efficiency point (BEP) operation according to some embodiments of the present invention, where the suction liner spiral design  146  includes two overlapping spirals  146   a  and  146   b.    
     In  FIGS. 2   a  and  2   b , the suction liners  14 ′,  14 ″ each have an inner rim R I  and an outer rim or periphery R O . In  FIG. 2   a , each overlapping spiral  144   a ,  144   b  is configured to start at an outer periphery P 1  of the inner rim R I  and end at the outer rim or periphery R O . In  FIG. 2   b , each overlapping spiral  146   a ,  146   b  is configured to start at an outer periphery P 2  of the inner rim R I  and end at a respective intermediate location IL 1 , IL 2  between the inner rim R I  and the outer rim or periphery R O . 
     In  FIG. 2   a , the two overlapping spirals  144   a ,  144   b  are configured to start at substantially diametrically opposite sides S 1 , S 2  of the inner rim R I  and end at substantially diametrically opposite sides S 1 ′, S 2 ′ of the outer rim or periphery R O . Similarly, in  FIG. 2   b , the two overlapping spirals  146   a ,  146   b  are configured to start at substantially diametrically opposite sides S 1 , S 2  of the inner rim R I  and end at opposite intermediate locations IL 1 , IL 2 . The suction liner spiral designs in  FIGS. 2   a ,  2   b  are shown by way of example, and the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned having a different number of spirals, or a different spiral configuration, within the spirit of the present invention. 
     In mathematics, a spiral is generally understood to be a curve which emanates from a central point, getting progressively farther away as it revolves around the point. The spirals shown in  FIGS. 2   a  and  2   b  are shown by way of example as spirals that may be used in order to implement the present invention. However, embodiments are envisioned using other types or kinds of spirals either now known or later developed in the future, and designed within the spirit of the present invention without undue experimentation, including using a single spiral that may include a single curve which emanates from a central point, and get progressively farther away as it revolves around the point, or using more than two spirals that may include three curves which each emanate from a central point, and get progressively farther away as it revolves around the point. The scope of the invention is also intended to include using one or more spirals that get progressively farther away from the central point more quickly or less quickly than the curves shown in  FIGS. 2   a ,  2   b , as well as using one or more spirals that get progressively farther away from the central point having more revolutions or less revolutions about the central point than the curves shown in  FIGS. 2   a ,  2   b . Moreover, the scope of the invention is not intended to be limited to the number of spirals used in the spiral design. For example, embodiments are envisioned using one spiral, or at least two overlapping spirals, such as three or four overlapping spirals within the scope and spirit of the present invention. 
     FIGS.  3   a ,  3   b    
     In  FIG. 3   a , the impeller  12 ′ is configured with an inner rim r i  and an outer rim or periphery r o , and the forward curved impeller suction side pump out vanes  122   a ,  122   b ,  122   c , . . . ,  122   l  extend from an outer periphery p 1  of the inner rim r i  and end at the outer rim or periphery r o . The forward curved impeller suction side pump out vanes  122   a ,  122   b ,  122   c , . . . ,  122   l  are shown spaced equidistantly about the impeller face  120 ′. 
     In  FIG. 3   a , the forward curved impeller suction side pump out vanes  122   a ,  122   b ,  122   c , . . . ,  122   l  are shown by way of example and the scope of the invention is not intended to be limited to the same. For example, embodiments are envisioned having a different number of vanes, such as fewer than 12 vanes or greater than 12 vanes. Embodiments are also envisioned using other types or kinds of curves either now known or later developed in the future, and designed without undue experimentation within the spirit of the present invention. 
     Alternatively, and by way of comparison, for Cw&gt;about 50%, the impeller  12 ″ may be used having an impeller face  120 ″ with five (5) back curved pump out vanes  124  (see  FIG. 3   b ) combined with a spiral-equipped suction liner, consistent with that disclosed herein, may also reduce wear significantly, according to some embodiments of the present invention. Moreover, the scope of the invention is not intended to be limited to the number or shape of pump out vanes used. For example, embodiments are envisioned using less than five pump out vanes, or more than five pump out vanes, such as two, or three or four pump out vanes, as well as six, or seven, or eight pump out vanes, within the scope and spirit of the present invention and embodiments are also envisioned using pump out vanes having a different shape than that shown in  FIG. 3   a.    
     In  FIG. 3   b , the impeller  12 ″ is configured with an inner rim r i  and an outer rim or periphery r o , and the five (5) back curved pump out vanes  124  extend from an outer periphery p 2  of the inner rim r i  and end at the outer rim or periphery r o . The five (5) rear curved pump out vanes  124  are shown spaced equidistantly about the impeller face  120 ″, although the scope of the invention is not intended to be limited to any particular relationship between the respective rear curved pump out vanes  124 . Moreover, the scope of the invention is not intended to be limited to the number or shape of back pump out vanes used. For example, embodiments are envisioned using less than five back pump out vanes, or more than five back pump out vanes, such as two, or three or four back pump out vanes, as well as six, or seven, or eight back pump out vanes, within the scope and spirit of the present invention and embodiments are also envisioned using back pump out vanes having a different shape than that shown in  FIG. 3   b.    
     FIG.  4   
       FIG. 4  shows part of a pump or pumping assembly, arrangement or combination generally indicated as  5  having the impeller  12 , the suction liner  14  and the shaft  16 , that are arranged according to some embodiments of the present invention. The impeller  12  is arranged inside a pump liner or volute  7 . In operation, a motor (not shown) rotates the impeller  12  in relation to the suction liner in order to pump a fluid containing the solids. Embodiments are also envisioned in which a double casing design may be used, e.g., such that expensive hard metal parts are contained within an outer casing of less expensive material, e.g., cast ductile iron. Embodiment are also envisioned in which rubber liners may be used, and the scope of the invention is intended to include an implementation using the same. 
     The Shaft/Impeller Arrangement 
     The arrangement between the shaft  16  and the impeller  12  is described in provisional patent application Ser. No. 61/365,947, filed 20 Jul. 2010, which was subsequently filed as regular utility application Ser. No. 13/186,647, filed on 20 Jul. 2011, claiming benefit to the earlier filed provisional application, both applications are hereby incorporated by reference in their entirety. 
     Scope of the Invention 
     Although described in the context of particular embodiments, it will be apparent to those skilled in the art that a number of modifications and various changes to these teachings may occur. Thus, while the invention has been particularly shown and described with respect to one or more preferred embodiments thereof, it will be understood by those skilled in the art that certain modifications or changes, in form and shape, may be made therein without departing from the scope and spirit of the invention as set forth above.