US 3228592 A
Description (OCR text may contain errors)
L. SHAPIRO Jan. 11, 1966 NON-SPILLING FEED MEANS FOR VERTICAL CENTRIFUGE Filed NOV. 18, 1963 2 Sheets-Sheet 1 ImmunununuuunununununnunmnnnnnnnnnnugJ I HMI ATTORNFY NON-SPILLING FEED MEANS FOR VERTICAL CENTRIFUGE Filed NOV. 18, 1963 L. SHAPIRO Jan. 11, 1966 2 Sheets-Sheet 2 l m w k INVENTOR. LEONARD HAPIRO ATTORNEY United States Patent 3,228,592 NON-SPILLING FEED MEANS FOR VERTICAL CENTRIFUGE Leonard Shapiro, Upper Darby, Pa., assignor to Pennsalt Chemicals Corporation, a corporation of Pennsylvania Filed Nov. 18, 1963, Ser. No. 324,546 4 Claims. (Cl. 2337) This invention relates to centrifuges. More specifically this invention relates to a centrifuge of the suspended type in which feed is delivered to the centrifuge through a conduit extending upwardly through a central opening in the bottom of the bowl. Still more specifically this invention deals with means in such a centrifuge for preventing escape of feed mixture down along the feed tube to the outside of the bowl.
In a large number of centrifugal separating operations there is a demand for operation of the centrifuge under pressure conditions isolated from the atmosphere. Pressure conditions are maintained, for instance, in the centrifugal separation of the desirable insoluble form of polypropylene from the undesirable soluble form of the polymer in hexane solution. This operation is desirably carried out at temperatures above the atmospheric boiling point of hexane; or alternatively, the operation may be performed under a blanket of nitrogen to keep out air which might support an explosion. As another example in the purification of titanium trichloride it is necessary that the sludge be centrifugally removed in inert gases at pressures in excess of 100 pounds per square inch. Otherwise the process stream will react with its surrounding gas and evolve hydrogen chloride gas to the considerable loss in product yield. The contact of atmospheric water vapor would also degrade the product. Similarly in the clarification of fruit juices it is desired to centrifuge in an isolated atmosphere to avoid the oxidizing which could cause degradation in flavor of the juice.
For a number of reasons it has been found that centrifuges of the suspended type more readily lend themselves to pressure operation than horizontal machines or machines in which the shaft driving mechanism are below the machine. The suspended machine, for instance, requires that only one set of support bearings be sealed from the atmosphere rather than two as with the horizontal machine. In the suspended machine the upper end of the shaft usually projects upward out into the atmosphere and there is a resulting upward force acting on the bottom of the centrifugal bowl tending in operation to relieve the downward force due to the weight of the bowl on the bearings. The reverse is true with the pressure centrifuge which is supported from underneath.
conventionally, the suspended continuous operation machine has been supplied with feed mixture by a stationary feed tube extending upward through a central opening in the bottom of the bowl. To permit ready disassembly and reassembly the opening in the bottom of the bowl has been made large enough to amply accommodate the tube. Loss of feed mixture down along the outside of the tube to the exterior of the bowl has been avoided by restricting the opening in the upper end of the tube and aiming the feed jet at a downwardly facing deflection plate mounted in the bowl. Hitting the deflection plate the feed has been thrown radially outward into the bowl or at least into a feed receiving pocket leading to the bowl. An example of such structure is disclosed in the U.S. Patent 3,061,181 which issued October 30, 1962 on an application filed by F. P. Gooch.
While centrifuges fed in the manner above described have been completely satisfactory for most applications, the present invention relates to an improvement thereon and is especially directed to operations in which the feed mixture rate or pressure is subjected to an occasional slack condition. With some above described centrifuges at the occasion of such a drop in volume or pressure the jet issuing from the restricted end of the feed tube has not impinged on the deflection plate and the feed mixture has simply spilled down the outside of the feed tube to the outside of the centrifuge. In some structures this has resulted in the contamination of the solids discharge with feed mixture.
In accordance with the present invention such a condition is avoided by having an accelerator element mounted in the bowl extending downward into the upper end of the feed tube and causing a rotation of the mixture at the upper end of the feed tube whereby the feed mixture is projected outwardly from the rim of the tube into the feed pocket or into the bowl itself. Under the improvement this outward projection of feed mixture is assured and is not sensitive to the volume or pressure of the feed. Hence it is ideally suited for continuous operation in which there is an occasional drop in the feed mixture rate or pressure.
.At the same time under the present invention there is no interference with the normal operation of the centrifuge; nor is the assembly and reassembly of the machine made more complicated.
Other objects and features of the invention will be apparent to those skilled in the art upon a reading of the following specification of which the drawings are a part and in which is represented a preferred embodiment of the invention.
In the drawings FIGURE 1 is an elevational view with portions broken away of a centrifuge embodying the invention;
FIGURE 2 is an enlarged sectional view of the area of FIGURE 1 with which the invention is primarily concerned; and
FIGURE 3 is an upward plan view of the accelerator means of FIGURE 2.
Briefly, the invention relates to a centrifuge comprising a centrifuge bowl having a vertical axis and a central opening in its lower end, a feed mixture tube extending upward into the opening and presenting inside the bowl an upwardly facing open end defined by a peripheral rim, feed mixture accelerator means mounted inside the bowl for rotation relative to the rim, the accelerator means extending downward into the rim to cause rotation of the feed mixture in the upper end of the feed tube and consequent outward projection of feed mixture from the rim of the feed tube into the bowl and to thereby prevent spilling of feed mixture down the outside of the tube when the feed pressure drops.
Referring more specifically to the drawings, a centrifuge embodying the invention is shown in FIGURE 1 and generally designated 10. It comprises a casing 12 in which is supported by suitable bearing suspension a centrifuge rotor or bowl 14 having an upwardly extending drive shaft terminating in a pulley 16 to which suitable power means (not shown) may be attached. The casing is preferably pressure-tight and the mounting may be in accordance with the above-mentioned patent or as described in the pending application Serial No. 299,511, filed August 2, 1963 by Karl G. Reed. A liquid discharge port (not shown) is provided at the upper end of the rotor or bowl 14. Suitable collectors take off the effluent and remove it from the casing. The solids discharge port 18 is inward of the liquid discharge port and from it solids may be discharged from the centrifuge to a receiving trough (not shown) mounted at the lower end of the casing 12. From the trough the solids may be removed for further processing if desired or necessary. Moving the solids in the bowl toward the solids discharge port 18 is the screw conveyor 20 which as explained in the Gooch patent may be driven through a suitable gear box connected to the rotor. The gearing is such that the conveyor 20 rotates in the same direction but at a speed slightly different from that of the bowl to effect the downward scrolling of the solids.
As shown in FIGURE 1 the bowl 14 is provided with a central opening 22 in its lower end. Extending upward through the opening is the feed tube 24 supported stationarily in the casing by spider 26. The feed tube 24 may be provided if desired with a conventional rinse passage 28 segregated from the portion carrying the feed mixture. A rinse nozzle 30 may project the small quantity of rinse outward into a suitable rinse receiving pocket 32 from which it is dispersed into the bowl.
Attention is now focused on the area of the invention as shown in FIGURE 2. The feed tube 24 comprises a head 34 preferably of two-piece construction and presenting an outwardly diverging mouth 36 terminating in a circular rim 38. The lower end of the head is formed with an outward peripheral rib 40 to help guide the relative movement of the centrifuge bowl and the feed tube during assembly.
The interior of the screw conveyor 20 presents a generally cup-shaped insert 42 partially defining a feed mixture receiving pocket. The insert having a central opening 44 at its lower end to permit upward passage of the tube head. Radial vanes 46 help assure rotation of the liquid in the pocket. A replaceable conveyor feed passage sleeve 48 extends through an opening in the wall of the insert 42 and through an opening in the Wall of the conveyor 20 to permit outward passage of the feed mixture into the bowl. Closing the upper end of the feed mixture receiving pocket is the plate 50 which presents on its lower face a downwardly directed accelerator means in the form of substantially triangular vanes 52. In the preferred embodiment three vanes spaced 120 apart (FIGURE 3) comprise the accelerator means. The angular edges of the vanes are broken as shown to provide greater clearance. As shown the pointed end of the accelerator means extend downwardly into the diverging mouth of the feed mixture tube 24 below the level of the rim 38. To assure its rotation the plate 50 is slotted and keyed as at 54 to the conveyor 20. Suitable seals are provided in the assembly as shown to avoid undesired leakage.
In operation the feed mixture is supplied through the tube 24 to the upper end thereof. The accelerator means comprising vanes 52 being immersed in the mixture in the mouth 36 will cause a rotary motion of the feed in the upper end of the tube at the speed of the conveyor. As the feed advances centrifugal force will project the rotating liquid outwardly over the circular rim 38. The feed will be received in the receiving pocket partially defined by the insert 42 and will pass through sleeve 48 out into the bowl. The outward projection of the feed mixture from the rim 38 is not dependent on the feed rate or on the pressure or rate of feed, and should the rate slack off for a period the continued outward projection of the rate that remains will preclude spillage of feed down the tube 24.
One of the benefits of the present improvement is that since distribution is not dependent on the impact of a jet of feed mixture against a deflector plate there need be no restriction in the end of the feed mixture tube. Consequently feed pressure need not be so high. Further by commencing the rotation of the feed mixture at the axis of the centrifuge rather than the wall of the feed receiving pocket, acceleration is more gradual and shear forces tending to break up flocculated particles and delay their sedimentation are no so great. Other advantages will be apparent.
It should be understood that this invention has been described in connection with a worm type or continuous solids discharge. centrifuge since it was conceived and perfected in connection with such a machine. However it is adapted for use in suspended centrifuges of all types including the conventional disc stack centrifuge which may be operated as a separator or clarifier or both. Its application to other forms of centrifuges is envisioned.
Therefore, it is to be understood that the above particular description is by way of illustration and not of limitation, and that changes, omissions, additions, substitutions, and/ or other modifications may be made without departing from the spirit of the invention. Accordingly,
it is intended that the patent shall cover, by suitable expression in the claims, the various features of patentable novelty that reside in the invention.
1. A centrifuge comprising a centrifuge bowl having vertical axis of rotation and a central opening in its lower end, a feed mixture tube extending upward into the opening and presenting inside the bowl an upwardly facing open end defined by a peripheral rim, feed mixture accelerator means mounted inside the bowl for rotation relative to the rim, the accelerator means comprising at least one accelerator vane having sides extending from above the level of the rim substantially vertically downward into the rim to cause rotation of the feed mixture in the upper end of the feed mixture tube and consequent outward projection of feed mixture from the rim of the feed mixture tube into the bowl, and to thereby prevent spilling of feed mixture down the outside of the tube when the feed pressure drops.
2. A centrifuge as described in claim 1 wherein the accelerator means is pointed and comprises three vanes disposed at with respect to each other.
3. A centrifuge as described in claim 1 in which the centrifuge is provided with a screw conveyor mounted for rotation in the bowl and the accelerator means is mounted on the screw conveyor.
4. In a centrifuge comprising a centrifuge bowl having a vertical axis and a central opening in its lower end, a stationary feed mixture tube extending upward into the opening and presenting inside the bowl an upwardly facing open discharge end defined by a peripheral rim; the improvement of accelerator means mounted inside the bowl for rotation relative to the rim and comprising at least one accelerator vane having sides extending from above the level of the rim substantially vertically downward into the feed mixture tube to a level below the rim to cause rotation of the feed mixture in the upper end of the feed mixtuer tube with consequent outward projection of feed mixture at the level of the rim.
References Cited by the Examiner UNITED STATES PATENTS 952,653 3/1910 Trent. 1,563,491 12/1925 Hoyle 233-7 1,780,655 11/1930 Nyrop 233-7 2,083,809 6/1937 Asch 23328 I 2,108,098 2/1938 Bergner 233-45 2,138,468 11/1938 Ayres 233l4 3,073,516 l/l963 Glasson 23328 References Cited by the Applicant UNITED STATES PATENTS 2,881,974 4/1959 Ruf.
MARTIN P. SCHWADRON, Acting Primary Examiner. HENRY T. KL NKSIEK, Examiner.