y 1968 G. D. WILLIAMSON, JR 3,384,026
PUMP APPARATUS Filed Aug. 16, 1966 2 Sheets-Sheet 2 866 EFF(%) ems/e5 H. P.
TQTAL HEAO (F7) CA INVENTOR.
G/(QERT 0. WI L/AMS 0/1608,
A TTORIVEY United States Patent 3,384,026 PUMP APPARATUS Gilbert D. Williamson, Jr., Verona, N.J., assignor to International Telephone and Telegraph Corporation, a corporation of Delaware Filed Aug. 16, 1966, Ser. No. 572,782 9 Claims. (Cl. 103103) ABSTRACT OF THE DISCLOSURE An improved trash pump is provided having a casing and impeller configuration which cooperate to produce an eddy type secondary flow in the impeller periphery which is conducive to higher discharge pressure in the maximum flow range, thereby improving the overall efficiency of the pump.
This invention relates generally to pump apparatus, and more particularly to trash handling centrifugal vane flow pumps.
It is well known, that centrifugal pumps for handling particulate matter, sludges, and slurrys must necessarily embody an unobstructed passage through the pump in order to handle objects capable of passing through the pump suction intake. As such, these pumps must depart from good conventional pump design which results in a lower discharge pressure, lowered air handling ability, and lowered overall efiiciency. This requires therefore a pump configuration with the highest possible overall etficiency and yet, be capable of handling objects which pass through the pump suction inlet.
With this in mind, an object of this invention is to provide an improved trash pump having a casing and impeller configuration conducive to higher discharge pressure in the maximum flow range, thereby improving the overall efficiency of the pump.
Another object of this invention is to contour and warp the impeller blades so that the discharge stream from the impeller periphery is concentrated radially toward the contour of the casing wall, producing an eddy type secondary flow in the impeller chamber.
A further object of this invention is to provide a casing about the impeller periphery arranged to induce a regenerative liquid flow about the impeller periphery.
Yet another object of this invention is to position the impeller within the casing so that the liquid leaving the impeller periphery is concentrated and directed against a combined cylindrical and radial wall arranged to induce a regenerative eddy within the casing perimeter and a portion of the impeller chamber.
A still further object of this invention is to provide a pump for handling particulate matter and having a passage through the casing and the impeller vane capable of handling any solid that will pass through the suction intake.
And, yet another object of this invention is to generate turbulent eddys at the impeller periphery thereby increasing the air handling ability of the pump.
In general a centrifugal pump embodies a casing having an axial intake and a tangential discharge, and a rotatable impeller cooperating within the casing. A feature of this invention is that the casing has a cylindrical portion substantially larger in diameter than the impeller and in axial alignment with substantially 0.4 to 0.7 of the axial width of the warped impeller vanes, the cylindrical portion opening into a larger arcuate section forming the perimeter of the casing, and the arcuate section being symmetrical about a transverse center-line and having an interior radius equal to or larger than the radius of the axial intake.
A feature of this invention is that the impeller vanes have a double curvature, or are warped. In addition to being curved away from the direction of rotation, as in normal radial vane centrifugal pump impellers, the vane surfaces are generated by lines inclined to the axis of rotation. This inclination is into the direction of rotation and is a maximum at the impeller outside diameter and minimal at the hub.
Another feature of this invention is that the impeller warped vane axial width is substantially equal to 0.75 to 1.0 of the diameter of the axial intake, and is spaced in said casing with the forward vane edge extending into the transverse arcuate section substantially 0.5 to 0.85 of the interior radius of the arcuate section.
A further feature of this invention is that the casing and impeller configuration coperate to produce an eddy type secondary flow at the impeller periphery which is conducive to higher discharge pressures in the maximum flow range, thereby improving the overall efficiency of the pump.
The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:
FIGURE 1 shows the end view of the pump casing according to the invention;
FIGURE 2 shows a cross section of the pump according to the invention taken along line 22 of FIGURE 1;
FIGURES 3a through 3d illustrate a typical impeller according to the invention; and
FIGURE 4 is a conventional H-Q-E pump curve showing the relative improvement in head, quantity, and efiiciency obtained through the novel arrangement and configuration of the invention.
Referring to FIGURE 1, the end view of the pump according to the invention shows a circumferential casing 10, an axial suction intake 11, and a tangential discharge outlet 12. The impeller 13, shown in phantom lines, rotates in the direction indicated by arrow 14. Intake 11 and outlet 12 have a diameter so as to permit solids of substantial spherical shape and having a radius R or less to pass through the intake and outlet. The warped vanes 15 curve away from the direction of rotation, and the space between the warped vanes 15 exceeds the diameter of intake 11 and outlet 12. With reference to FIGURE 3c the inclination of vanes 15 to impeller shroud 22 is indicated by 0 This inclination is into the direction of rotation and is minimal at the hub 16 of impeller 13 and maximum at the periphery of the impeller.
Referring additionally to FIGURE 2, the configuration of casing 10 comprises a cylindrical section 17, and a smoothly contoured radius 18 approaching and leading into the casing perimeter 19 which is arcuate in section, and at a constant radius originating at the intersection of transverse center-line 20 and the axis of intake 11. The interior of arcuate section 19, is equal to or greater than radius R of the pump suction axial intake 11.
Warped vanes 15 on impeller 13 have an axial width AW substantially equal to 0.75 to 1.0 of the diameter of the axial intake measured from the forward edge 21 to shroud 22. Rearward of shroud 22 are pump out vanes 23 which reduce stuffing box pressure, axial thrust on bearings, and prevent clogging. The pump out vanes may be used or omitted as dictated by the particular design. An alternate construction which may be used in lieu of pump out vanes is to remove portions of shroud 22 between warped vanes 15.
The forward edge 21 of warped vanes 15 projects substantially less than and no greater than transverse centerline 20 of pump casing 10. In a preferred embodiment, the forward edge 21 extends into the transverse arcuate section substantially 0.5 to 0.85 of the radius of the arcuate section 19, this positioning of the impeller in relation to the pump casing configuration creates a regenerative eddy.
Since warped vanes slope forward into the direction of rotation (flow), they thereby direct the impeller discharge stream 24 against the cylindrical portion 17 of casing 10. This causes a pressure differential resulting in a fluid eddy 25 circulating through the arcuate section 19 of casing 10, and returning through the clearance space 26 forward of the impeller and toward the axis of the impeller 13. The flow will again be into the warped vanes 15 where the fluid eddy can be reactivated by the rotating impeller. Because casing 10 is substantially a circle having its center coincident with the impeller center, the solids and regenerative eddies may continue in a circular path within the casing for one or more revolutions before subsequent discharge through the outlet 12.
The improved efficiency of this configuration and the resulting buildup in discharge head and quantity of discharge, have been proven in the laboratory with relative values shown on the curves illustrated in FIGURE 4 hereafter described. The behavior of fluids in passages of different sizes are not alike, therefore, the dimensions of this configuration will vary with different size pumps. The range specified in this description was established by laboratory tests of 3", 4" and 6" pumps.
Referring now to FIGURE 4, a graph has been plotted for a standard solids handling centrifugal pump with a partially recessed semiopen impeller with radial vanes and the improved configuration as represented by this invention. The capacity of the pump in gallons per minute has been plotted against the total head in feet, brake horsepower, and efliciency. Curves 27 represent the brake horsepower, the solid line being for the standard design, and the dashed line being for the improved design according to the invention. Curves 28 represent efficiency and curves 29 represent total head, the standard design again being the solid lines and the improved version the dash lines. At a flow rate of 700 gallons per minute, it can be seen from the curves 28 that the efliciency has improved from 35 percent to 45 percent. In addition the brake horsepower required is less, and the total head has improved a significant amount. It is evident from the graph that the improvement in efl'lciency of this pump is significant throughout the entire working range of the pump.
Referring again to FIGURE 2, shaft 30 extends through bearing housing assembly 31 and packing plate 32. The tapered end of shaft 30 is attached to the impeller by means of Woodruff Key 33 and a self-locking impeller nut 34. Impeller 13 has a steel insert 35 for preferred mounting on the tapered end of shaft 30. The packing plate is adapted to mount to casing 1t] and is sealed by means of O ring seal 36, and the deep stufling box 37 which contains six rows of graphite impregnated asbestos packing. Also associated with the sealing problem is lantern ring 38, a connection for packing seal (water or grease) 39, and a split packing gland 40 for ease of repacking. Sleeve 41 prevents shaft 30 from scoring and is sealed by O ring 42 against leakage, the sleeve being attached to shaft 30 by means of sleeve drive pin 43.
Included on shaft 30 is a slinger 44, to sling any leakage and facilitate draining through drain hole 45 i hearing housing 31. Shaft 30 is rotatably mounted and retained in housing 31 by means of ball bearings 46, spacers 47, and snap rings 48. The larger diameter 49 of shaft 30 reduces vibration associated with the pump, and holes 50 are provided for anchoring housing 31 to a proper mounting surface.
Arrow 51 indicates the back pull-out design of this pump wherein the impeller 13, packing plate 32, and hearing housing assembly 31 are removable for ease of repacking or repairing without disturbing the remainder of the piping associated with the pump. After repair or work as desired, the unit is again replaced by pushing in direction indicated by arrow 51 and attaching a suitable drive unit to the extension of shaft 30.
Referring to FIGURE 3a through 3d, FIGURE 3a is a section view of the impeller according to the invention, FIGURE 3b is an end view showing the warped vanes of the impeller, FIGURE 3c is a partial view of the Warped vane, and FIGURE 3a is an end view of the pump out vanes of the impeller.
As can be seen in FIGURE 3a, impeller 13 comprises warped vanes 15, shroud 22, and the pump out vanes 23. The forward edge 21 of warped vanes 15 are straight and then incline at an angle 61, approximately 30, to hub 16. Shroud 22 contains a steel insert 35 slotted for a Woodruif Keyway 52. The width of the pump out vanes are approximately one tenth the width of the warped vanes 15.
FIGURE 3b in a preferred embodiment, shows the contour and warpage of three vanes 15. The warpage is in the direction of rotation and maximum at the periphery of the impeller. This maximum warpage is at an angle 02, approximately 70, with the vane 15 and shroud 22, as shown in FIGURE 3c. Since, as known to one skilled in the art the pressure on the leading face of the vane is greater in the direction of flow than the lagging face of the vane, this angle of warpage prevents excessive bypassing of the slurry.
FIGURE 3d shows six pump out vanes 23, these vanes are perpendicular with shroud 22, and contoured away from the direction of rotation as in conventional pump design.
In operation, the impeller having warped vanes sloping forward in relation to the impeller rotation, directs the impeller discharge stream against the cylindrical portion of the casing which causes a pressure differential resulting in a fluid eddy circulating through the arcuate section of the casing and returning through the clearance space forward of the impeller towards the axis of the impeller, to flow into the impeller where the fluid eddy is again activated by the rotation of the impeller. The operation due to this configuration results in an improved efficiency and quantity of discharge as shown by laboratory tests and analysis. This novel pump design as described herein presents a significant improvement over the state of the art as presently practiced.
While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention, as set forth in the objects thereof and in the accompanying claims.
1. Pump apparatus comprising:
a casing defining an impeller chamber having an axial intake opening and a tangential discharge opening;
a rotatable impeller having a plurality of warped vanes on one face of a shroud forming the body of said impeller, said impeller being centrally mounted in said chamber about the axis of said intake opening, and said warped vanes are generated by lines inclined to the axis of rotation, such that the inclination is into the direction of rotation and is a minimum near said impeller center and maximum at said impeller periphery; and means for mounting said casing and impeller, whereby said casing configuration cooper ates with said warped vanes to produce a regenerative eddy in said impeller chamber.
2. Apparatus according to claim 1, wherein said casing has a cylindrical portion larger in diameter than said impeller and in axial alignment with substantially one-half of the axial width of said warped impeller vanes.
3. Apparatus according to claim 2, wherein said cylindrical portion opens into a larger arcuate section forming the perimeter of said casing, said arcuate section being symmetrical about a transverse center-line and having a minimal interior radius equal to the radius of said axial intake, and the junction of said cylindrical annular portion with said arcuate annular section is smoothly contoured.
4. Apparatus according to claim 3, wherein the forward edge of said warped impeller vanes extend into said transverse arcuate section substantially two-thirds of the radius of said arcuate section, thereby providing sufiicient space forward of said impeller to create said regenerative eddy.
5. Apparatus according to claim 4, in which the axial width of said warped vanes is substantially equal to seveneighths of the diameter of said axial intake opening.
6. Apparatus according to claim 1 wherein said impeller further includes a multiplicity of pump out vanes, said pump vanes being perpendicularly mounted on the other face of said shroud and contoured away from the direction of rotation, whereby said pump out vanes cooperate with said casing configuration to prevent clogging.
7. Apparatus according to claim 1, wherein said mounting means comprises:
a shaft for mounting said impeller;
a packing plate for mounting said casing, said plate having means for sealing said chamber and said shaft to prevent leakage; and
a housing assembly being adapted to mount said packing plate and having means for rotatably mounting said shaft, whereby said impeller shaft, packing plate, and housing assembly are removable without disturbing piping connections to said casing.
8. Apparatus according to claim 7, wherein said casing has a cylindrical portion larger in diameter than said impeller and in substantial alignment with one-half of the axial width of said warped impeller vanes; said cylindrical portion opening into a larger arcuate section forming the perimeter of said casing, said arcuate section being symmetrical about a transverse center-line and having a minimal interior radius equal to the radius of said axial intake; and the junction of said cylindrical annular portion with said arcuate section is smoothly contoured, such that said casing configuration cooperates with said impeller to produce said regenerative eddy in said im- References Cited UNITED STATES PATENTS 918,559 4/1909 Landis 230-134.45 2,201,947 5/1940 Valentine 103-115 2,456,128 12/1948 Kessler 103--115 2,635,548 4/1953 Brawley.
3,130,678 4/1964 Chenault s 103-415 1,763,595 6/1930 Paatsch 103-115 3,167,021 1/1965 Sence. 3,171,357 3/1965 Eggcr. 3,190,226 6/1965 Judd 103-115 HENRY F. RADUAZO, Primary Examiner.