US 3323464 A
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Description (OCR text may contain errors)
June 6, 1967 A. BENTON ETAL 3,323,464
ROTARY PUMP FOR PUMPING VISCOUS SLURRY Filed Dec. 50, 1965 2 Sheets-Sheet 2 INVENTORS.
Low; 4). BEA/TOM gaaser M ZAMae-RF Arrows? United States Patent 3,323,464 ROTARY PUMP FOR PUMPING VISCOUS SLURRY Louis Arnett Benton, Middlesex, and Robert Morrison Lambert, North Piainfield, N.J., assignors to Johns- Manville Corporation, New York, N.Y., a corporation of New York Filed Dec. 30, 1965, Ser. No. 517,710 3 Claims. (Cl. 103-103) This invention relates generally to rotary pumps and more specifically to rotary pumps adapted to pump relatively viscous slurries containing fibrous materials.
In certain so-called wet process textile operations it is often desired to pump slurries of fibrous materials, such as asbestos, rayon, etc. in a manner in which the integrity of the fibers is preserved. One of the disadvantages of a great many slurry pumps, particularly those of the multi-vane type, is that the solid constituents of the slurry are sheared as they come into contact with the stationary wall defining the pump body cavity. Additionally, the impeller vanes in such pumps are such that they cause fibers to be entangled and/or to rope. As a consequence, such pumps require considerable cleaning and maintenance and are considered to be inefiicient for pumping fibrous slurries.
Accordingly, a primary object of the present invention is to provide an improved pump which overcomes the disadvantages of the slurry pumps described above.
Another object of this invention is to provide an improved pump which is especially adapted to pump relatively viscous slurries containing increased amounts of fibrous material.
Briefly, a slurry pump of the character described and constructed in accordance with the instant invention comprises: a pump casing defining a central cavity for encasing a rotary impeller and a tangential discharge outlet, with the rotary impeller having an essentially radial central passage chamber and radial discharge ports defined by a pair of sidewalls and bridging members bridging the sidewalls of the impeller, whereby the slurry being pumped is substantially confined within the chamber and out of major contact with the surfaces defining the central cavity of the casing. In essence, the impeller defines a rotating cage having two generally diametrically opposite doors (discharge ports) which alternately present material for discharge to the discharge outlet of the pump casing. The passage chamber is substantially clear of any protuberances or encumbrances on which the fibers may be caught or entangled. The bridging members essentially define chords across the circle generated by the sidewalls of the impeller to contribute to the radial flow of the material through and from the passage. In preferred embodiments, the bridging members are laterally spaced a distance which corresponds substantially to the diameter of the inlet opening into the passage chamber, which distance is less than the length of the chord formed by each of the bridging members.
Further objects and advantages of the present invention will be apparent in view of the specification set forth hereinafter.
In the drawing, wherein like numerals designate like parts:
FIG. 1 is a cross-sectional elevational view of a pump constructed in accordance with this invention;
FIG. 2 is a cross-sectional elevational transverse view taken along line 2-2 in FIG. 1;
FIG. 3 is an isometric view of the rotary impeller employed in the pump shown in FIGS. 1 and 2; and
FIG. 4 is a front view, partially broken away, of an alternate form of rotary impeller.
In the embodiment of the invention illustrated in FIGS. 1 and 2, the pump, generally designated by the numeral 10,
includes sidewalls 12 and 14 and the peripheral wall 16 forming a stationary casing 18. The casing 18 defines a central cavity 20 for enclosing the rotary impeller 22. The impeller 22 is supported on rotatable shaft 24 and is secured for rotational movement therewith by suitable means, such as key member 28 extending through hub portion 30.
The rotary impeller 22 comprises a pair of parallel and spaced sidewall members 32 and 34 which are in planes normal to a plane extending through the axis of rotation 26 of the impeller 22. The sidewall members 32 and 34 may be considered to define respective parts of the front face 33 and the rear face 35 of the impeller 22. The sidewall members 32 and 34 are bridged by bridging members 36 and 38 and together therewith define a central passage chamber 40 for confining the slurry to be pumped within the impeller 22. As can be seen in FIG. 3, the terminal edges 42 and 44 of bridging members 36 and 38 together with the arcuate portions 46 and 48 of sidewalls 32 and 34 respectively, intermediate the bridging members 36 and 38, define outlet ports 50 and 52 from chamber 40. The bridging members 36 and 38 also serve as guides for guiding the slurry through the chamber 40 and toward the outlet ports 50 and 52. The sidewall member 32 defines an inlet port 54 for introducing the slurry to be pumped into chamber 40.
In a preferred embodiment, as illustrated in FIGS. 1 and 2, the sidewall members 32 and 34 are discs which form full circles and thus contribute to the dynamic balance of the impeller 22. However, in a less preferred embodiment, the peripheral arcuate portions, or area segments ABC and ABC', may be omitted. An important aspect of this invention is that of defining a passage chamber 40 within the impeller 22 in an arrangement whereby contact of the slurry, as it is rotated by the impeller 22, with the walls 12, 14, and 16, is minimized. Consequently, in preferred embodiments, the bridging members 36 and 38 form chords AC and AC across the circles generated by the rotation of the sidewalls, which chords are of a length greater than the lateral spacing S between the bridging members 36 and 38. In other words, the chords AC and AC' are at least as long as and preferably longer than the outlet port dimensions which are transverse to the axis of rotation. Such an arrangement also imparts an essentially radial motion to the slurry as it discharges from the impeller. This deters tangling of the fibers and choking or blocking of the pump.
In FIG. 4 is shown a modified form of impeller. The bridging or guide members 136 and 133 are modified, in that they are slightly curved. However, the members 136 and 138 still basically define chords and'together with the sidewalls 32 and 34 define essentially radial discharge ports 150 and 152 for chamber at peripheralarcuate portions of the sidewalls 32 and 34.
In preferred embodiments of the invention, the terminal edges of the bridging or guide members are closely adjacent the circular wall 16 or casing 118 to deter any substantial amount of fibrous slurry from passing therebetween and becoming entangled with other edges. Also, essentially there are no leading edges of an impeller vane, as commonly known, to catch or entangle the fibers of the slurry or to create undue turbulence within the slurry being pumped. The esentially closed construction provides an arrangement wherein the moving fibers are mostly in contact with the moving surfaces of the impeller sidewalls and of the bridging guide members, as opposed to any stationary surfaces of a pump casing, and thus minimizes any shearing action. The essentially radial motion through passage chamber defined by the chord forming bridging members deters the violent mechanical forces generated by the usual radial type impeller vanes and which forces cause dewatering or segregation of fibrous slurries.
Slurries containing 8% solids (fibers), by weight, and at pressures up to 25 psi. have been efiiciently pumped, without presence of entanglement of the fibers, with pumps embodying the features of the present invention. In contrast, centrifgual pumps which have been heretofore available are only capable of pumping slurries which contain, as an average, 3 to 4% solids. Some pumps have been capable of pumping 6% solid slurries, but the solid contents in these slurries were not predominantly fiber.
In some instances, some increase in contact between the solid particles of a pumped slurry and stationary portions of the pump may be tolerated. In such cases, as for example, when pumping slurries containing cellulosic fibers, one or the other of the impeller sidewall members 32 and 34 may be omitted. However, if a sidewall is omitted, it is preferred that the sidewall member 32 be omitted. Since sidewall member 32 defines the inlet port 54, its omission will result in less of an increase of exposed stationary surface area than the omission of sidewall member 34. While the members 36 and 38, in such arrangements, no longer bridge between two sidewall members of the impeller, they do bridge the lateral space between the remaining sidewall of the impeller and a side wall of the pump casing.
In the preferred embodiments of the invention, the impeller 22 has been disclosed in the drawings as comprising relatively thin bridging members 36 and 38. However, it will be understood that the impeller 22 may be fabricated as a single casting and that arcu-ate portions ABC and ABC may be completely filled. An important aspect of this invention is that a central passage chamber 41), for confining the slurry and minimizing contact of the slurry being pumped with stationary portions of the pump, be defined.
While specific embodiments of the present invention have been set forth and described in detail herein, it will be understood that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.
What we claim is:
1. In a liquid slurry pump adapted to pump viscous slurries:
(a) a stationary casing including a peripheral wall portion and defining a central cavity enclosing a rotary impeller,
(b) said impeller having front and rear faces, an axis of rotation, and comprising a central passage chamber defined by a pair of transverse sidewall members and bridging members interconnecting said sidewall members,
() said chamber having an inlet which is coaxial with said axis of rotation and a pair of outlets which are generally diametrically opposite about said axis of rotation, and
((1) each of said bridge members forming a chord extending substantially across the circular portion of said cavity and closely adjacent to said peripheral wall portion to substantially deter passage of the solids of said slurry between said bridging members and said peripheral wall portion, and said front and rear faces of said impeller each having at least a portion closely adjacent to their respective sidewall portion of said casing to deter passage of said solids therebetween.
2. A slurry pump adapted to pump fibrous slurries,
which pump comprises:
(a) a stationary casing including a generally cylindrical central cavity defined by a pair of sidewalls and a peripheral Wall, said casing defining a discharge outlet, and a rotary impeller, having front and rear faces and an axis of rotation, and being encased by said casing and comprising:
(1) a pair of parallel sidewall members traversing said axis of rotation,
(2) spaced apart and generally parallel bridging members bridging said sidewall members,
(3) each of said bridging members forming a chord extending substantially across the circular portion of said cavity,
(4) each of said bridging members also having its terminal portions closely adjacent to said peripheral wall to substantially deter passage of the fibers of said slurry between said terminal portions and said peripheral wall, and said front and rear faces of said impeller each being closely adjacent to a respective sidewall portion of said casing to deter passage of said fibers therebetween,
(5) one of said sidewall members defining an inlet which is coaxial with the axis of rotation of said impeller.
3. In a liquid slurry pump adapted to pump viscous slurries,
(a) a casing including a side wall portion and a peripheral wall defining a central cavity having a circular portion and enclosing a rotary impeller,
(b) said impeller having front and rear faces, an axis of rotation and comprising a central passage chamber defined by a transverse sidewall member and spaced-apart bridging members extending across and being secured to said sidewall member,
(c) each of said bridging members forming a chord extending substantially across the circular portion of said cavity and having its terminal portions closely adjacent to said peripheral wall to substantially deter passage of the solids of said slurry therebetween, and said front and rear faces of said impeller being closely adjacent to a respective sidewall portion to deter passage of said solids therebetween.
References Cited UNITED STATES PATENTS 1,577,110 3/1926 Collins 230-127 FOREIGN PATENTS 507,182 12/1951 Belgium. 155,134 1883 France. 954,669 12/1956 Germany. 240,387 10/1925 Great Britain. 247,106 2/ 1926 Great Britain. 102,102 11/ 1923 Switzerland.
DONLEY J. STOCKING, Primary Examiner.
HENRY F. RAD-UAZO, Examiner,