US 2440317 A
Description (OCR text may contain errors)
p w. H. WELSH 4 1 PUIP IIIPELLER I Filed April 20, 1945 4 Sheets-Sheet 1 'IN V EN TOR.
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ATTORNEY April 27, 1948. wEL$H 2,440,317
' ruur IMPELLER Filed April 20, 1945 4 Sheets-Sheet 3 INVENTOR. W////'am H. Welsh A TTORIVIY Apfil 27, 1948.
FiledApril 20, 1945 w. H. WELSH PUIP IMPELLER INVENTOR. Mmam M e/sh Qo-ZrLpC/LM AT T ORNEI 4 Sheets-Shani; 4
Patented Apr. 27, 1948 UNITED STATES PATENT OFFICE PUMP IMPELLER.
William H. Welsh, New York, N. Y.
Application April 20, 1945, Serial No. 589,445
(Granted under the act of March 3, 1883, as amended April 30, 1928: 370 0. G. 757) 4 Claims.
This invention relates to impellers for centrifugal pumps. In pumping corrosive fluids or slurrys of abrasive material of either a corrosive or non-corrosive nature, ordinary cast-iron impellers wear to the point where replacement is necessary within a few weeks. Slurrys of sand, ore and ashes, for example, are handled commonly by volute centrifugal pumps of simple design. The impellers of such pumps wear, erode and corrode at a high rate, approaching rapidly the point at which loss of efficiency results in exit velocities from the pump so low that suspended solids settle out of the slurry and clog the system. shutdowns caused in such a manner are both long and costly, necessitating separation and cleaning of pump runners and conveyor-line-piping, in addition to replacement of the worn impeller.
The impeller life can be lengthened by casting or otherwise fabricating the entire impeller of a material more resistant to wear and corrosion than cast iron. Such a procedure, however, involves the use of a large quantity of relatively expensive material, replacement of all of which would be necessitated by only localized wear,
An object of this invention is to provide a pump impeller in which the sections most liable to wear are replaceable.
Another object is to provide a pump impeller in which the sections most liable to wear are made of material having high resistance to corrosion and abrasion, the remainder of the impeller being made of common and inexpensive material.
Still another object is to provide a pump impeller in which the sections most liable to wear are replaceable easily and quickly, without disassembling the pump housing.
Further objects and advantages of this invention, as well as its construction, arrangement and operation, will be apparent from the following description and claims in connection with the accompanying drawings, in which:
Fig. 1 is an end view of the assembled impeller of this invention, showing the inlet end; Fig. 2 is the inlet end of the same impeller,
- Fig. 6 is an isometric view of awear plate of the impeller; and
Fig. 7 is anisometric view of a vane insert of the impeller.
In the drawings ll represents an impeller body of ordinary design, such as is used in singleinlet, backward-discharge, volute pumps (Figs. 1 and 3). Impeller body ll consists primarily of two parallel disk-shaped housings, that are spaced and joined by multiple vanes l2 cast integrally with the housings, said vanes forming the sides of the impeller body H. For the purposes of illustration, the number of vanes I2 is shown as 3, although a greater or lesser humwith the seal-plate and gasket removed, partly be! can be utilized, as desired. A single inlet opening I3 is provided in one housingof the impeller body II, and located centrally externally of the opposite housing of impeller body H is hub M, which is threaded internally to receive and engage a power shaft (not shown) by means of which rotary motion is imparted to the impeller.
Bolted or otherwise aifixed to the inner surface of the housing opposite inlet opening I3 is a deflector plate I5. The surface of deflector plate l5 that is not adjacent to impeller body- H is provided with a protuberant boss l6, designed to divert and direct smoothly the flow of the fluid being pumped toward the vanes and periphery of the impeller (Fig. 4). Wear-plates ll, corresponding in number to vanes l2, protect portions of the inner surface of impeller body I l opposite inlet opening 13 that are not protected by deflector plate [5. Wear-plates l'l fit about the edges of deflector plat-e l5 and extend between the vanes l2 (Figs. 2 and 6). Recesses I8 in the housing of the impeller body II opposite the inlet opening l3 receive the ends of vane inserts [9 (Fig. 5). Vane inserts 'l 9, when inserted into recesses I8, form the leading edges of vanes I2. Vane inserts l9 and recesses l8 correspond in numbers to vanes I2. When in place, the outer surfaces of vane inserts l9 are flush with the outer surface of the housing of impeller body H in which is located inlet opening 13, said housing being cut away to receive vane inserts l9. An annular gasket 20, of rubber or similar material, and an annular seal plate 2|, preferably of hardened steel, are bolted to the outer surface of impeller body ll adjacent to inlet opening l3, and serve as retaining means for the vane inserts I 9. In addition, seal-plate 2| acts as a seal against the pump housing (not shown).
In pumping abrasive and corrosive fluids, it has edges of the vanes I2, and on the inside surface of the housing of the impeller body II opposite the inlet opening I3, the leading edges of the vanes I2 wearing at much the greater rate. The
leading edges of vanes I2 erode, corrode and wear back, reducing the efliciency of the pump to the point of uselessness in a short length of time, at the end of which period. the remainder of the impeller, with the exception of the surface opposite the inlet entry, is found to be in substantially its original condition.
In utilizing this invention, impeller body II can be made of ordinary cast iron, or similar inexpensive material. Deflector plate I5, wear plates I1 and vane inserts I9 are made of material highly resistant to corrosion and wear, the choice of material for these parts depending on the type of fluid or slurry the impeller is intended to pump. For example, in pumping a slurry of power-plant ashes in salt water, ordinary cast-iron impellers wear to the point of uselessness within 3 weeks. It has been found that sand-cast white iron or chilled cast iron carrying 4.00 to 6.00% nickel and 1.25 and 2.25% chromium withstands the destructive action of such a slurry for periods as long as year. In utilizing the impeller of this invention for pumping such a salt-water-ash slurry, deflector plate I5, wearplates I1, and vane inserts I9, are made of the resistant material described, or of similar material.
In assembling the impeller of this invention, deflector plate I5 and wear-plates I! are bolted to impeller body II. Vane inserts I9 are then inserted in place, and gasket 20 and seal-plate 2I are bolted to impeller body I I. The pump casing (not shown) is then assembled about the impeller and the power shaft is inserted through the casing into hub l4. After a'period of operation, the impeller can be inspected by removing the runner or line leading to inlet opening I3 and the condition of the impeller observed through inlet opening I3.
When required, vane inserts I9 can be removed and replaced easily and quickly through the aperture in the pump casing made by removing the inlet runner or line. This is accomplished by removing seal-plate 2i and gasket 20 from the impeller body II, withdrawing the Worn vane inserts I9 and replacing them with new ones, and then replacing gasket 2!] and seal-plate 2i. When inspection reveals the necessity, the pump housing can be disassembled, the impeller removed, and deflector plate i5 and wear-plates I1 replaced. By securing deflector plate I5 and wear-plates. H with stud bolts rather than with bolts and nuts, they too may be replaced through inlet opening I3, although the difficulty of so and quickly by disconnecting the inlet runner or line to the pump and removing seal-plate 2| doing may in some cases outweigh the saving of vlabor and time resulting from not disassembling and gasket 20. This represents a saving not only over the cost of a new impeller in its entirety but also a great saving in labor costs and shut-down time. For example, in one'installation it has been found that the vane inserts I9 can be removed and replaced and the pump placed back in operation in one third the time required to disassemble the outer case of the pump and replace the impeller. Furthermore, when in addition to vane inserts I9, deflector plate l5 and wear-plates ll, or any of them, are found to become so worn as to require replacement, they can be replaced in impeller body II, and the impeller body II, the largest and heaviest part of the impeller, can serve for a very long period of time. 1
It is to be understood that various modiflcations and changes can be made in this invention without departing from the spirit and scope thereof as set forth in the claims.
The invention described herein may be manufactured and usedfby or for the Government of body provided with an inlet opening and multiple vanes, replaceable parts lining the inner surface of said impeller body opposite said inlet opening, replaceable inserts constituting the leading edges of said vanes, and an annular sealplate surrounding the inlet opening of said impeller body, said seal-plate constituting the retaining means for said vane inserts and being detachable from the rest of said impeller to permit removal and replacement of said inserts, and said replaceable parts and said replaceable inserts being made of material more highly resistant to wear and erosion than is said impeller body.
2. A pump impeller for pumping fluids of a corrosive and abrasive nature comprising an impeller body provided with an inlet opening and multiple vanes, replaceable parts lining the inner surface of said impeller body opposite said inlet opening, replaceable inserts constituting the leading edges of said vanes, and an annular sealplate surrounding the inlet opening of said impeller body, said seal-plate constituting the retaining means for said vane inserts andbeing detachable from the rest of said impeller to permit removal and replacement of said inserts, said impeller body consisting of cast iron, and said replaceable parts and said replaceable vane inserts consisting of sand-cast white iron containing 4.00 to 6.00% nickel and 1.25 to 2.25% chromium.
3. A pump impeller comprising an impeller body provided with an inlet opening and multiple vanes, and replaceable inserts constituting the leading edges of said vanes, said inserts being p0-.
sitioned at theirends in-recesses in said impeller body and being held from radial motion during rotation of said impeller by the walls of said re-.
4. A pump impeller comprising an impeller body provided with an inlet opening and multiple vanes, and replaceable inserts constituting the mark the end of the useful life of an integral im- 7 peller, even made of resistant material, the vane inserts I9 can be removed and replaced easily leading edges of said vanes, said inserts being nositioned at their ends in recesses in said impeller body and being held from radial motion during 5 r rotation of said impeller by the walls or sold re- Number ceases and being removable axially or said lm-f 807,971 peller through said recesses at one end of sold 978,753 impeller. 1,034,456
' WIILIAM H. WELSH.
REFERENCES CITED 6 vHome Date Skinner Dec. 19, 1905 Hurst Dec. 13, 1910 Hurst Aug. 6, 1912 Exton Jan. 13, 1920 FOREIGN PA'IENI'S Country Date Great Brltaln -1 1899 Great Britain June-16, 1922