US3602485A

US3602485A - Flocculation apparatus

Info

Publication number: US3602485A
Application number: US786070A
Authority: US
Inventors: Philip Edgerton
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1968-12-23
Filing date: 1968-12-23
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31

Abstract

Rotary paddles of a mixing apparatus are driven by a crank mechanism through a pivoting lever that swings about a yieldable fulcrum, the arrangement being such that the paddles are moved with a varying velocity in a circular path through the liquid being mixed.

Description

United States Patent I Philip Edgerton Hollcong, Pa. 786,070

Dec. 23, 1968 Aug. 31, 1971 FMC Corporation San Jose, Calif.

lnventor Appl. No. Filed Patented Assignee FLOCCULATION APPARATUS 4 Claims, 4 Drawing Figs.

US. Cl

Field of Search References Cited UNITED STATES PATENTS 1,432,358 10/1922 Podhajny 259/109 1,699,916 1/1929 Platin 259/109 2,081,850 5/1937 Darby 259/110 Primary Examiner-Robert W. Jenkins Attorneys-F. W. Anderson and C. E. Tripp ABSTRACT: Rotary paddles of a mixing apparatus are driven by a crank mechanism through a pivoting lever that swings about a yieldable fulcrum, the arrangement being such that the paddles are moved with a varying velocity in a circular path through the liquid being mixed.

PATENTEU M1831 l97| INVENTOR. PHILIP EOGERTON BYJU. W

AT TORN E YS FLOCCULATION APPARATUS BACKGROUND OF THE INVENTION In the treatment of sewage and the like by chemical flocculation, the rapid thorough mixing of chemicals with raw water, sewage or industrial liquids is followed by a gentle, slow mixing to produce a maximum size floc. It has been found that it is advantageous to move the mixture with a circular rolling movement to keep the floc in suspension, and it has also been found that the growth of floc is dependent upon relative movement between the paddles and the mixture. Reciprocating and oscillating mixers have been proposed but, while they do attain a degree of relative movement between the paddles and the mixture, they do not maintain a continuous roll velocity that is effective to keep the floc in suspension. Accordingly, with reciprocating and oscillating mixers the solid material tends to settle out and become deposited on the bottom of the mixing tank rather than moving along toward a desired discharge station. Accordingly, it is an object of the present invention to provide a novel mixing apparatus that is effective to move a mixture of liquids and solid material in such a manner that the solids are maintained in suspension while the elements of the mixing mechanism move relative to the mixture to promote flocculation.

SUMMARY OF THE PRESENT INVENTION A mixing mechanism, comprising a pair of rotary paddle assemblies keyed to a horizontal shaft, is disposed in an elongated tank, submerged in a mixture of raw water, chemical and sewage. The horizontal shaft is driven from a variable speed drive unit, that is mounted at the top of one end wall of the tank, through a drive mechanism which consists of an upper crank connected to the rotary output shaft of the drive unit, a lower crank keyed to the horizontal mixer shaft, and a drive lever connected between the cranks.

Rotation of the upper crank in one direction effects rotation of the lower crank in the opposite direction due to the provision of a fulcrum unit that is mounted in fixed position in the tank adjacent the drive lever. The fulcrum unit comprises a pair of rollers that bear against opposite sides of the drive lever to provide pivot points for the lever as it responds to the movement of the upper crank. Each roller is mounted to move laterally relative to the lever to accommodate lateral movement of the central portion of the lever as it transmits the motion of the upper crank to the lower crank.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic side elevation of the mixing apparatus of the present invention shown in operating position in a tank.

FIG. 2 is a diagrammatic vertical section taken on line 2-2 of FIG. 1.

FIG. 3 is an enlarged diagrammatic view of a portion of FIG. 2, particularly showing the operation of the rollers of the fulcrum unit.

FIG. 4 is a fragmentary diagrammatic showing of a second embodiment of the mechanism of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT In FIG. I the reference numeral 10 indicates generally a concrete tank having an inlet opening 12 formed at the upper end of one wall, a-discharge opening 14 at the upper end of an opposite wall, and a pair of

fixed piers

16 and 17, supported from the floor of the tank and projecting up into the mixing chamber defined by the walls of the tank. Three

wooden baffle units

18, 20 and 22 are mounted in fixed position to extend transversely across the tank from one sidewall to the other.

A generally horizontal shaft 24 is rotatably journaled in

bushings

26, 27 and 28 that are mounted respectively on the pier 16, the pier 17, and on a bracket 30 supported from the tank wall. Two

paddle assemblies

31 and 32 are keyed to the shaft 24 in 90, out-of-phase relation. Each paddle assembly comprises a pair of metal arms 34 that are mounted at spaced intervals along the shaft 24, each of the arms 34 including

members

34a and 34b (FIG. 2)' that project in opposite directions from a fabricated square hub 36 which is secured to I the shaft 24 for rotation therewith. A plurality of wooden paddles are secured between each pair of arms 34.

The shaft 24 is driven from a motor driven speed reducer 40 (FIG 1) which has an output shaft 41 to which an upper crank 42 is keyed. A pivot lever 44 that is rectangular in cross section, is pivotally connected at its upper end to the upper crank by a pin 45; and at its lower end it is pivoted by means of a pin 46 to a lower crank 47 that is keyed to the horizontal mixer shaft 24.

Referring to FIG. 3 it will be noted that, as indicated by direction arrows, when upper crank 42 rotates counterclockwise, the lower crank 47 and shaft 24 rotate clockwise. This reversal is effected with the aid of a fulcrum assembly 50 through which the pivot lever 44 passes. The assembly 50 comprises a housing 52 that is open at the top and bottom and is secured, as by bolts, to the end wall of the tank directly below the drive unit 40. The fulcrum assembly provides a pair of

fulcrum rollers

54 and 55 that are rotatably mounted on

bellcrank assemblies

56 and 57 respectively and are in the plane of the fiat pivot lever 44 in position to contact the side edges of the lever. Each bellcrank assembly includes a pair of

spaced levers

58 and 59 that are pivoted on a short shaft 60 that extends horizontally between the sidewalls of the housing 52, each lever being provided with a flat contact plate 62 along the edge of one of its arms. The contact plates 62 of the two bellcrank assemblies are in the path of movement of a pair of rollers 65 (FIG. 1) that are rotatably mounted on opposite faces of the pivot lever 44. A stop member 67 is secured to the

levers

58 and 59 of the bellcrank assembly 56 and is effective to engage a fixed abutment 68 of the housing 52 for the important purpose of limiting the clockwise rotation of the bellcrank which must at all times extend into the path-of the roller 65, and has its weight distributed to pivot to that position, but must be prevented from interfering with the operation of bellcrank 57.

In FIG. 3 an operating position of the mixer drive mechanism is illustrated wherein the upper crank 42 and the lower crank 47 have reached a lower dead center position and the pivot lever is in a substantially vertical position. It will be noted that the rollers 65 have engaged the contact plates 62 of bellcrank assembly 57 and are exerting a force tending to pivot the bellcrank counterclockwise to bring the fulcrum roller 55 into contact with the side edge of the pivot lever 44 and to hold it tightly against the lever as the cranks move through the dead center position. Thus, the roller 55 acts as a fulcrum and the movement of the upper end of the lever 44 causes the lever to pivot clockwise about roller 55 and thereby positively move the lower end of the lever 44 clockwise. As a result, the lower crank 47 and mixer shaft 24 rotate clockwise. The reverse action takes place when the rollers 65 move upwardly and engage the contact plates 62 of bellcrank assembly 56.

Since paddles 35 move continuously in a circular path, the mixture is moved with a continuous rolling action that keeps the solid material in suspension. Further, it should be noted that, while the upper crank 42 rotates with constant angular velocity, the lower crank 47 rotates at a variable speed which is a minimum at upper dead center and maximum at lower dead center. Therefore, the mixer shaft 24 rotates at a variable speed and the blades 35 are continuously changing their velocity relative to the mixture, resulting in a shearing action that promotes flocculation.

In FIG. 4 there is disclosed a second embodiment 70 of the present invention wherein a pivot lever 44', which is identical to the pivot 44 of FIG. 2 except that it has no actuating roller similar to the roller 65, is disposed in a tank and driven by upper and lower cranks exactly in the manner that pivot lever 44 is driven. Laterally shiftable fulcrums are provided by a unit 71 including a mounting plate 72 secured to the end wall of the tank, two spaced brackets 73 and 74 fixed to the plate 72 and a pair of

slide rods

76 and 77 that are slidably journaled in the brackets 73 and 74 respectively. Also'included in the unit are a roller 78 rotatably mounted on the bifurcated end of rod 76, a roller 79 similarly mounted on rod 77, and a spring 80 disposed between each bracket and a flange on the associated slide rod to urge the roller on the rod into engagement with the adjacent side face of the pivot lever.

It will be evident that the spring-urged rollers maintain contact with the pivot lever and provide the fulcrum that is necessary to guide the pivot lever in its pivoting and slight lateral shifting movement.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

Iclaim:

1. Apparatus for concentrating floc in a tank comprising mixing members mounted for movement in a circular path in the tank, and means for driving said mixing members at varying speed, said drive means including a driving and a driven crank operatively connected to said mixing members, a pivot lever connected between said cranks, bellcranks mounted for pivotal movement on opposite sides of said lever, each bellcrank carrying a rotatable roller movable into engagement with said lever, to provide a fulcrum for said lever incident to pivoting of said bellcranks, actuating means on said pivot lever for alternately engaging and pivoting said bellcranks, as said lever moves up and down in response to rotation of said driving crank, and abutment means in the path of one of said bellcranks for limiting the pivoting of one of said bellcranks to prevent interference of said bellcranks during movement of said pivot lever.

2. Apparatus according to claim 1 including a housing pivotally mounting said bellcranks and wherein said abutment means is disposed on said housing to be contacted by said one bellcrank.

3. Apparatus for concentrating floc in a tank comprising mixing members mounted for movement in a circular path in the tank, and means for driving said mixing members at varyingspeed, said driving means including a driver crank, a driven crank, a pivot lever pivotally connected to each crank and disposed for generally up and down movement between said cranks and pivoting movement in a predetermined plane, in response to rotation of said driver crank, means connecting said driven crank to said mixing members to move said members in a circular path, pivot control means for said pivot lever for guiding said lever in an orientation such that rotation of said driver crank in one direction causes rotation of said driven crank in an opposite direction, said control means including a pair of fulcrum rollers disposed on opposite sides of said pivot lever in said plane, each roller being located substantially midway between said driver and driven cranks, and spring means urging said rollers for movement in said plane into contact with said lever to provide fulcrums therefor during up and down movement of said lever.

4. Apparatus for concentrating floc in a tank comprising a plurality of paddles mounted for rotation in the tank, and means for moving said paddles in a circular path through a mixture of liquid and solid material in the tank, including means for varying the speed of movement of said paddles between upper and lower limits of speed during movement in said circular path for causing said paddles to move through the mixture at varying speeds with a shearing action, superposed on the circular movement of said mixing members and for moving the mixture with a circular rolling action that keeps said solid material in suspension.

Claims

3. Apparatus for concentrating floc in a tank comprising mixing members mounted for movement in a circular path in the tank, and means for driving said mixing members at varying speed, said driving means including a driver crank, a driven crank, a pivot lever pivotally connected to each crank and disposed for generally up and down movement between said cranks and pivoting movement in a predetermined plane, in response to rotation of said driver crank, means connecting said driven crank to said mixing members to move said members in a circular path, pivot control means for said pivot lever for guiding said lever in an orientation such that rotation of said driver crank in one direction causes rotation of said driven crank in an opposite direction, said control means including a pair of fulcrum rollers disposed on opposite sides of said pivot lever in said plane, each roller being located substantially midway between said driver and driven cranks, and spring means urging said rollers for movement in said plane into contact with said lever to provide fulcrums therefor during up and down movement of said lever.