US3429513A - Combination agitator and chopper for intake of slurry pump - Google Patents

Description

D. J. GRIBBLE Feb. 25, 1969 COMBINATION AGITATOR AND CHOPPER FOR INTAKE OF SLURRY PUMP Sheet I of 2 Filed Nov. 14. 1966 Donald josep/z Gnfi/e BY INVENTOR Feb. 25, 1969 D. J. GRIBBLE COMBINATION AGiTATOR AND CHOPPER FOR INTAKE OF 'SLURRY PUMP I Sheet i of 2 Filed Nov. 14, 1966 0054/4 Jbsepfi Gribble INVENTOR /v United States Patent Ofiice 3,429,513 Patented Feb. 25, 1969 3,429,513 COMBINATION AGITATOR AND CHOPPER FOR INTAKE F SLURRY PUMP Donald J. Gribble, Windsor, Calif., assignor to Agpro, Inc., Santa Rosa, Calif., a corporation of California Filed Nov. 14, 1966, Ser. No. 594,207 US. Cl. 24146 Int. Cl. B02c 18/10, 18/40 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to slurry processing apparatus, and more specifically to a slurry agitator and cutter means adapted to operate in conjunction with each other to maintain the agitator and its drive means free of accumulations of solids and to divide solids contained within the slurry.

ln systems wherein a mixture of liquid and solids is processed, such mixture being otherwise known as a slurry, it is frequently necessary to provide a storage region for the slurry until it may be used. A slurry requires circulation or other means of agitation to maintain its solids in suspension and may need treatment to reduce the size of large solids contained in the slurry. Agitation may be produced by a propeller rotated through a motor-driven drive shaft, however, difficulties may arise in the use of such an agitator where the slurry contains solids which tend to accumulate on the agitator. This is especially a problem where the slurry contains fibrous, stringy, or other flexible materials which have a tendency to wrap around a rotating propeller and shaft. The undesirable accumulation of these materials on the propeller and shaft decreases the efiiciency of the agitator, and may result in undue wear of the parts within the system.

A general object of this invention is to provide novel means for preventing the accumulation of solids on a slurry agitator and its drive means.

In furtherance of this objective, it is an object to provide apparatus for handling slurries which comprise the combination of a motor-driven rotating shaft, an agitator attached to and rotating with the drive shaft, and cutter means adjacent the agitator adapted to maintain both the agitator and drive shaft free of solid materials which otherwise might collect thereon.

More particularly, it is an object of this invention to provide novel means for maintaining an agitator and its drive shaft free of collections of solid materials which includes a cutter element adjacent the agitator and drive shaft, attached to and rotatable with the shaft and agitator, and a stationary cutter element providing with he first-mentioned cutter element a shearing action for cutting up solids.

Often slurry processing systems also incorporate a distribution pump with an intake for the pump submerged within the slurry. Where the mixture contains solids of appreciable size, damage may occur to the pump if such solids are drawn into it. Screens may be provided at the intake to prevent this, however, such screens are subject to the accumulation thereon of solids suspended in the slurry which plug the pump intake and reduce the working efiiciency of the system.

A further object of this invention, therefore, is to provide novel cutter means at a slurry distribution pump intake, adapted to reduce the size of solids suspended in the slurry prior to the slurry entering the pump.

This invention further contemplates the provision of easing structure at the intake of a slurry distribution pump, with chambers through which slurry flows to enter the pump, and a check valve controlling flow between the chambers permitting flow of slurry toward the pump while inhibiting reverse flow. This reduces pump priming problems.

The apparatus of this invention is relatively simple in construction, and as a consequence, is inexpensively produced. It provides trouble free organization for preventing the accumulations of solids on a slurry agitator and its drive means, and for simultaneously dividing large solids within a slurry.

These and other objects and advantages are attained by the invention, and the same is described hereinbelow in conjunction with the accompanying drawings, wherein:

FIG. 1 is a cross-sectional elevation view of slurry treatment apparatus including a storage tank having defined storage chambers therein, a propeller-type agitator, a pump, and motors positioned on a deck above the storage tank which drive the pump and agitator;

FIG. 2 is a top plan view of the apparatus shown in FIG. 1, further illustrating the storage tank, motors and P p;

FIG. 3 is a side elevation view of the propeller-type agitator and associated structure shown in FIG. 1, drawn on a slightly larger scale and with portions of a casing in the structure broken away;

FIG. 4 is a view taken along the line 44 in FIG. 3, showing in plan one of a pair of cutter elements provided in the structure; and

FIG. 5 is a view taken along line 55 in FIG. 3, showing in plan a propeller in the agitator and another of the pair of cutter elements in the structure.

Referring now to the drawings and first of all more particularly to FIGS. 1 and 2, at 10 is shown generally a storage tank in which may be stored a mixture of liquids and solids, also referred to herein as a slurry.

Tank 10 includes the usual side walls, such as the ones shown at 12, and a floor made up of sloping floor portions 14, 16, and 18. Covering the top of the tank is a platform 20 and decking 22.

The interior of the tank is divided into at least a pair of chambers, shown at 24 and 26, by a pair of vertical Walls 28 and 30. Wall 28 which may be a concrete wall extends between the sides of the tank but terminates short of these sides to provide a flow path for slurry around the ends of the wall. Wall 30, which is generally at right angles to wall 28 and is shown joining the left end of the wall in FIGS. 1 and 2, is formed from a series of planks 32 fastened to uprights 34. Chamber 24 extends to the right of wall 30 in FIG. 1 and is bounded along its base by floor portion 18. Chamber 26 extends to the left of wall 30 and thence to the far side of wall 28 in FIG. 1 and is bounded by floor portions 14, 16.

Mounted on platform 20 above the storage tank is a pump 40 utilized in withdrawing slurry from the tank. The pump is driven by energizing a motor 42 which has its output shaft 44 connected by belts 46 to pump shaft 48. Fluid is exhausted from the pump through discharge conduit 50. The slurry is supplied the pump intake 52 through an elongated conduit 54 which extends downwardly into the storage tank and which has its upper end connected by pipe structure 56 to the pump intake.

Adjacent the base of the storage tank is a propellertype agitator, generally shown at 58, which, as will become more fully apparent, is operated to produce circulation of the slurry and, through such circulation, slurry agitation. The agitator is rotated under power through a power-driven drive shaft 60 which extends downwardly into the storage tank through a pipe 62. Drive shaft 60 is rotated under power by energizing a motor 64 mounted on the platform adjacent motor 42. Connecting the output shaft 66 of motor 64 and the upper end of drive shaft 60 are belts 68 trained over suitable pulleys secured to the output shaft and drive shaft respectively.

As is best seen in FIG. 1, the propeller-type agitator is mounted within the confines of a cylindrical shroud or duct 70. Such shroud, which is open at opposite ends, is supported adjacent the base of the tank on a platform 72 which extends between the base of wall and the left margin of floor portion 18 in FIG. 1. The interior of shroud 70 provides a flow path for slurry from chamber 26 through the shroud into chamber 24.

Referring now more particularly to FIGS. 3, 4, and 5, suitably fastened to the base of pipe 62, which encases drive shaft 60, and conduit 54, providing for the feed of slurry to the pump, is casing structure 76. This includes a substantially cylindrical portion 76a concentric with conduit 54 and a substantially cylindrical portion 76b concentric with pipe 62. Casing wall 80 closing off a part of cylindrical portion 76b is provided with an opening, shown at 82, permitting slurry within the chamber defined within cylindrical portion 76b to pass into the chamber defined within the interior of cylindrical portion 76a. A check valve, more specifically a flapper valve 84, hinged to the casing structure at 86 swings upwardly to the position shown in FIG. 3 to accommodate slurry flow upwardly into the latter of these two chambers. Slurry flow in the reverse direction, however, is inhibited by the valve dropping downwardly to close off opening 82.

Propeller-type agitator 58 comprises a propeller 90 which is nonrotatably secured to the base of drive shaft 60 through suitably securing the hub 92 of the propeller to an end portion of the drive shaft protruding below casing structure 76. As contemplated herein, with operation of the agitator the slurry is simultaneously subjected to a chopping action effective to divide solids in the slurry, whereby entanglement of solid material on the drive shaft is inhibited and the material supplied the pump is in such form as to be easily handled by the pump.

To this end it will be noted that secured to shaft 60 directly adjacent propeller 90 is an elongated cutter element, more specifically a bar, shown at 94. Shaft 60 extends through the bar at a point located midway between its ends. Each longitudinal edge of the bar is sharpened as by beveling the edge on the underside of the bar along its length. The bar fits within a suitably recessed region extending along the trailing edges of the agitator propeller so that the top face of the bar is flush with the trailing edges where such edges extend outwardly on the propeller blades from the ends of the bar.

Superimposed over bar 94 is another cutter element comprising what is referred to herein as shear plate 96. Such shear plate includes an annnular expanse 96a encircling the drive shaft, and integral with this expanse arms 96b, which extend radially of shaft 60. Projecting outwardly from the annular expanse, at approximately the location of the arms, are projections 960. The shear plate rests on bar 94, and projections 960 are received within notches 98 formed in the casing structure, with the shear plate in this manner prevented from rotating with rotation of shaft 60.

Mounted on wall 80 of the casing structure above expanse 96a at approximately the point where each arm 96b joins with the expanse is a travel limiting stud 100. In FIG. 3 only two of such studs are shown as the other one has been removed from the drawing. These studs limit the upward travel permitted the shear plate with respect to bar 94, and obviously with adjustments made in the position of these studs the amount of free travel permitted the shear plate may be changed.

Describing now how the apparatus described may be operated to produce agitation of the slurry and chopping up of solids in the slurry, motor 64 is operated to produce rotation of drive shaft and the propeller-type agitator which is at the base of the shaft. With rotation of the agitator, slurry (which typically might be at the level indicated at 102) is caused to circulate within the tank with such passing from chamber 26 and through shroud into chamber 24, thence to return to chamber 26 by flowing around the right end of wall 28 in FIG. 1. With such circulation solids in the slurry tend to be maintained in suspension. When it is desired to remove slurry from the tank, pump 40 which constitutes a distribution pump in the apparatus is operated through energizing of motor 42. With energizing of the pump a low pressure condition results in conduit 54 and slurry is drawn into the conduit through casing structure 76, with such slurry then traveling to pump intake 52. Valve 84 opens to accommodate slurry fiow through aperture or opening 82. Slurry on flowing into the casing structure passes through openings defined in the shear plate between the arms 96b of the shear plate. Solids in such slurry are subjected to a shearing action as the ends of bar 94 move in repeated shearing strokes across the lower faces of arms 96b.

To stop the distribution of slurry the pump is stopped. Valve 84 closes to hold a column of the slurry in conduit 54. Slurry fiow into the casing structure stops. The propeller-type agitator then functions only to produce circulation within the storage tank.

The apparatus of the invention has been found to constitute a practical answer to the problem involved in handling slurry which otherwise would tend to produce fouling of the propeller-type agitator and damage to the pump if permitted to flow into the pump.

While an embodiment of the invention has been described, variations and modifications are possible without departing from the invention. It is desired to cover all such modifications as would be apparent to one skilled in the art, and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. Slurry processing apparatus comprising a powerdriven rotatable shaft, an agitator mounted on said shaft for rotation with the shaft and operable on such rotation to produce a flow of slurry in a path extending along the shaft toward one end of the shaft, cutter means including a cutter element mounted on said shaft toward said one end of the shaft from the agitator in the flow path of said slurry movable with the shaft, operable on movement to divide solids in the slurry, casing structure mounted adjacent said cutter means defining a chamber receiving slurry flowing in said path and past the cutter means, and conduit means connecting with said chamber for channeling slur-ry from said chamber.

2. The apparatus of claim 1, wherein said cutter means further comprises a shear plate which encircles the shaft and said shear plate has spaced-apart cutter arms extending radially outwardly from the shaft, each of said arms including a cutting edge, said cutter element moving in a shearing stroke over said cutting edges on rotation of said shaft.

3. The apparatus of claim 1 which further comprises a pump for pumping the slurry, and wherein the intake of said pump is connected to said conduit means to be supplied slurry through said conduit means.

4. Slurry processing apparatus comprising a duct, 9. power-driven rotatable shaft and a propeller mounted on said shaft for rotation with the shaft, said propeller on rotation of the shaft producing a flow of slurry in a path extending through the duct in a direction generally paralleling the axis of the shaft, casing structure spaced along the axis of said shaft from said propeller and inwardly of the sides of the duct whereby a passage is provided for slurry flow through the duct and around the outside of the casing structure, said casing structure defining a chamher for receiving a portion only of the slurry flowing in said path through said duct, cutter means including a cutting element mounted on said shaft adjacent the propeller operable on rotation of the shaft to divide solids in the slurry received in said chamber, and conduit means connecting with said chamber for channeling slurry from said chamber.

5. The apparatus of claim 4, wherein the propeller is mounted on one end of the shaft and the flow of slurry produced by the propeller is from said one end toward the shafts opposite end, the casing structure encircles the shaft and is located toward the shafts opposite end from the shafts said one end, and said cutter means is located toward the casing structure from the propeller.

a pump for pumping slurry, and wherein the intake of said pump is connected to said conduit means to be supplied slurry by the conduit means.

References Cited UNITED STATES PATENTS 357,686 2/1887 Nacke 241-46 1,763,379 6/1930 Thurm et a1 24198 2,485,368 10/1949 Dodge 24146 3,318,248 5/1967 Rembold 241-46 GERALD A. DOST, Primary Examiner.

US. Cl. X.R.

6. The apparatus of claim 4 which further comprises 15 257

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