US2609185A

US2609185A - Method and apparatus for increasing fluidity of material

Info

Publication number: US2609185A
Application number: US170995A
Authority: US
Inventors: Eisner Johannes
Original assignee: FLSmidth and Co AS
Current assignee: FLSmidth and Co AS
Priority date: 1949-07-04
Filing date: 1950-06-29
Publication date: 1952-09-02
Anticipated expiration: 1969-09-02

Description

J. EISNER Sept. 2, 1952 METHOD AND APPARATUS FOR INCREASING FLUIDITY OF MATERIAL Filed June 29, 1950 INVENTOR RM 5 M 5? 2 W M Patented Sept. 2, 1952 UNITED ,STAT

ES PATENT OFFICE f Mn'rnon AND APPARATUS FOR INCREASIN j FLUIDITY OF MATERIAL to ES. Smidth & C0.

rationof New Jersey 7 "Application June 29, 1950, Serial No. 17 0,995 i I In Great Britain July 4-, 1949- This invention relates to the treatment of materials having a low degree of natural fluidity can best be accomplished by introducing air into the body of material and at the same time agitating the body by stirring. Of course, most powdered materials, such as cement,'contain a quantity of occluded air, and in some cases stirring of them alone, that is without the addition ofair, is sufficient to increase their fluidity to a point at which they are readily flowable.

Heretofore, rotary stirrers which have been employed for stirring a body of material in a container to increase its fluidity have required a large starting torque, the need for such a torque diminishing as the fluidity of the material increases due to the stirring. Hence, the stirrers must be driven from sources of power much greater than are necessary to maintain a stirrer in operation after it has been started, or in the alternative, the stirrers must be maintained in operation from the :time thematerial enters the container, and cannot be permitted to stop while there is still a substantial amount of material in the container. This diiflculty has been largely overcome by the method and apparatusof this invention and the starting torque required is decreased in some cases by more than half.

According to the, method of the invention, the fluidity of a body ofzmaterial .is increased by agitating only a portion of the body until the fluidity of that portion hasbeen substantially increased, and then, while continuing to agitate-that portion, agitating another portion until its fluidity has likewise been substantially. increased; and repeating these operations until the fluidity of substantially the Whole body of material has been increased; If 'sufiicient occluded'air to permit substantially increased fluidity is not contained by the body of material, as is oftentthe case,

1a Qlaims. (o1. 259 243 includes a novel rotatable stirring means, and WhendesirabIe, means in combination with the stirring means for injecting compressed air into the body of material. The stirring means comprises a rotatable shaft and a plurality of stirring arms mounted onthe shaft, each arm having at least a portion which is swingable outwardly from the shaft whereby vthe distance of its outer end from the shaft may be varied. Such stirring means is thereby capable of agitating'portions of varyingsize of a body of material in which it is located. I I 7 Several forms of apparatus by which. the method of thisinvention may be carried out will be more specifically described in connectionwit the accompanying drawing in which:

Fig. 1 is a sectional'view of one form of apparatus, I 1 a Fig; 2 is'a section on line 2-2 of Fig. 1,

Fig. 3 is a partial plan view of a modified form of stirring arm, i I r Fig. 4-. is ase'ction on line 4-4 of Fig. 3, and y g Figs. '5 and 6 are, respectively, elevationand plan views of another modified form of stirring arm.

y clnsFig. 1 is'illustrated'a container Iil; having a substantially conical bottom I [:and supported by a frame [2. 'Material, such as dry cement, may be fed into the container through a pipe I3 and may be withdrawn from the container through an outlet (not'shown). in bottom H. A plurality of compressed air inlets M are mounted'in bottom II and are provided with compressed-air through pipes I5, amanifold l6 and a pipe H connecting manifold I6 to a source (not shown)-. The number of. inlets I4 is great enough. so that compressed air may .be injected substantially throughout the cross-sectional-area of a body of material in containerv I0. "If desirable, means may be provided for selectively opening and closing inlets I 4'whereby air may be provided to pertions of the body of material of varying size.

A shaft 18, supported in bearings l9 and 20 located at opposite ends of the container, extends centrally through the container and may be rotated from a source of power, such as an electrio motor (not sho-wn),-through driveishaftfl and gears 22 and23. A plurality of spaced stirring arms 24 are pivotally' secured toshaft 18 by collars 25 having yokes 26, each yoke receiving the inner end of an arm 24 which is-s ecured to it by a pin 27. Each arm 24 is received, outwardlyof its inner-end, between a pair of rods 28, which are parallel toshaft i8, and a pair of cross bars 23 supported between the rods. Rods 28 are supported by pistons 30 contained in cylinders 3| which are secured to shaft l8 by brackets 32 outside the upper end of container l0. Cylinders 3| may be providedwith compressed ai'r'below pistons 30 through an inlet pipe 33, hollow, upper end 34 of shaft l8; andpipes connecting the cylinders with hollow end 34 ofshaft l8. Acover plate 36 closes the opening in the upper end of container H] through which shaft l8 and rods 28 pass. I

In this apparatus the stirring arms are normally in the position shown inFig. 1. When it is desired to withdraw material from container l0, compressed air is usually first injected into the material through inlets I4 after which the stirring means i actuated with the stirring arms in the positions shown. When the inner'portion stirring arm comprising two

parts

48 and 49, part .48 being keyed to shaft l8 and part 49 being pivotably secured to the outer end of part 48 by a of the body of material, that is that portion of the body capable of being stirred by the arms 24 in the position shown; has become sufficiently fluid, compressed air is' admitted gradually to cylinders 3| thereby raising pistons 30 and rods 28. Thus stirring arms 24 are pivoted upwardly about pins 21 and progressively larger portions of the body of material are affected by the stirring arms and have their fluidity increased until the arms reach the dotted line positions at which point'substantially the whole body of material within the container is being agitated. If desired, when the proper degree of fluidity of the material is reached the stirring apparatus may be shut off, and the supplying of air to cylinders 3| discontinued, and the increased fluidity of the material maintained solely by the continued injection of air through inlets I4. When the stirring apparatus is thus shut off, arms 24 descend, under their own weight, to their original positions to be ready for subsequent use.

The admission of compressed airto cylinders 3| may,'if desired, be initiated automatically, when the fluidity of the initially stirred portion of the material has reached the desired degree, by incorporating in the driving means for shaft l8 means for admitting air to inlet pipe 33 responsive to the decrease in power consumption of the driving means incident to an increase in material fluidity. Furthermore, the compressed air supplied to cylinders 3| may be supplied from the same source as that supplied to inlets |4, whereby if the supply to inlets I4 is interrupted the supply to cylinders 3| is interrupted, and arms 24 may descend to their lower position so that stirring may be begun again immediately when compressed air is again available. Also inlet pipe'33 may be provided with a valve operated in response to the operation of the driving means for the stirring apparatus, whereby if the driving means fails, the supply of air to cylinders 3| is shut off and the arms 24 are allowed to descend. In Figs. 3 and 4, a'modified-stirring arm is shown and comprises a part 40 adapted to be fixedly secured to shaft I3 and carrying on its outer end a drum 4| secured to it by a weld 42. Asecond part 43 of the arm is pivotably secured to drum 4| by a bolt 44 which extends'through the druin at a right angle to the longitudinal extent of the arm. A spring 45 surrounds drum 4| and has one end 46 enteringa hole in the wall of the drum andits other end 41 secured to part 43. Spring 45 urges part 43 toward its solid line position in abutment with part 40 as shown in Fig. 3. When the arm is rotated by shaft |8 in the direction indicated by the arrow in Fig. 3, the

initial resistance of the material being stirred is' great enough to cause part 43 to be moved to the dotted line position against the action of spring 45, but as the fluidity of the material increases due to stirring, spring 45 causes part 43 to pivot outwardly toward'the solid line position thereby bolt 50. Stops 5| and 52 are provided on part 48 adjacent bolt 50 to limit the movement of part 49. In theoperation of a stirring apparatus employing this type of stirring arm, shaft I8 is first rotated in a counter-clockwise direction as indicated by arrow 53 in Fig. 6; The resistance of the material being stirred causes part 49 of the arm to assume the dotted line position against stop 52 and thus the effective length of the stirring arm is the length of part 48. When the fluidity of the portion of the body of material thus being agitated has increased to the desired degree the rotation of shaft I8 is reversed to a clockwise direction as indicated by arrow 54. This reversal causes part 49 of the arm to be pivoted outwardly to the solid line position against stop 5|. The effective stirring length of the arm is thus increased and a larger portion of-the body of material is agitated.

' The various stirring arms described may be of any desired cross-sectional size or shape and, for instance, may resemble propeller blades so as to produce vertical currents in the container, whereby effective mixing of horizontal layers of material in the container may be ensured.

I claim:

l. A method of increasing the fluidity of a body of material which comprises injecting compressed air into a portion of the body of material, agitating said portion of the body until its fluidity is substantially increased, and progressively repeating said steps of air injection and agitation with additional portions of the body of material surrounding the portions of the body previously agitated until thefiuidity of substantially the whole body is increased.

2. A method of increasing the fluidity of a body of material which comprises injecting compressed air into a portion of the body of material, agitating said portion of the body until its fiuidityis substantially increased, and, then while continuingthe air injection into and the agitation' of said portion, progressively injecting air into additional portions of said body of material surrounding the portions of the body previously agitated and progressively agitating said additional portions until the fluidity of substantially the whole body is increased.

3. Apparatus for increasing the fluidity of a body of material which comprises means for injecting compressed air into the body, and rotatable means for stirring said body, said rotatable means including a rotatable shaft and a plurality of stirring arms mounted on said shaft, each stirring arm comprising two parts one of which parts is secured at one end to the rotatable shaft and'extends outwardly therefrom a substantial distance to stir a substantial portion of the body of material when rotated by the shaft, the other of said parts being pivotably secured to the outer end of said first part and being movable from an inner position in which it is angularly disposed with respect to said first part to an outer position in which it forms an outwardly extending extension of said first part.

4. Apparatus for increasing the fluidity of a body of material which comprises a container for saidbody of material, means for injecting compressed air into the bottom of the container, and

rotatable means supported substantially centrally in the container for stirring the material, the rotatable means including a rotatable shaft and a plurality of stirring arms mounted on said shaft, each stirring arm comprising two parts one of said parts being movable with respect to the other of said parts to effect adjustment of the overall length of the arm.

5. Apparatus forincreasing the fluidity of a body of material which comprises a container for the body of material, rotatable means supported substantially centrally in the container for stirring the material, said rotatable means including a rotatable shaft and a plurality of stirring arms mounted on the shaft, each stirring arm comprising two parts one of which parts is secured at one end to the rotatable shaft and extends outwardly therefrom a substantial distance to stir a substantial portion of the body of material when rotated by the shaft, the other of said parts being pivotably secured to the outer end of said first part and being movable from an inner position in which it is angularly disposed with respect to said first part to an outer position in which it forms an outwardly extending extension of said first part, means for rotating said shaft, and a plurality of compressed air inlets located in the bottom of the container and being adapted to be opened for injection of compressed air over an area corresponding to the cross-sectional area being swept by the stirring arms at any instant.

6. In an apparatus for increasing the fluidity of a body of material, rotatable stirring means comprising a rotatable. shaft and a plurality of stirring arms mounted on the shaft, each stirring arm comprising two parts one of which parts is secured at one end to the rotatable shaft .and extends outwardly therefrom a susbtantial distance to stir a substantial portion of the body of material when rotated by the shaft, the other of said parts'being pivotably secured to the outer end of said first part and being movable from an inner position in which it is angularly disposed with respect to said first part to an outer position in which it forms an outwardly extending extension of said first part.

7. A method of increasing the fluidity of a body of material which comprises agitating a substantially cylindrical portion of the body coaxial with the body and extending substantially throughout the length of the body, and, after the fluidity of said portion has been increased, and while continuing to agitate said portion, agitating an additional annular portion of the body surrounding the cylindrical portion thereof previously agitated.

8. A method of increasing the fluidity of a body of material according to claim 7 which includes the step of continuously injecting compressed air into the body of material.

9. A method of increasing the fluidity of a body of material which comprises agitating a substantially cylindrical portion of the body co axial with the body and extending substantially throughout the length of the body, and after the fluidity of said cylindrical portion has been increased progressively agitating additional annular portions of the body surrounding the portions thereof previously agitated.

10. A method of increasing the fluidity of a body of material which comprises injecting compressed air into a cylindrical portion of the body coaxial with the body and extending substan- 6 tially throughout the length of the body, agitating said cylindrical portion of the body until its fluidity is substantially increased, and, then while continuing the air injection into and the agitation of said cylindrical portion, injecting air into an additional annular portion of the body surrounding said cylindrical portion and agitating said annular portion until its fluidity is substantially increased.

11. In an apparatus for increasing the fluidity of a body of material, rotatable stirring means comprising a rotatable shaft, a plurality of stirring arms secured to the shaft, each of said arms comprising a first part fixedly secured to the shaft and a second part pivotably secured to the outer end of the first part and movable to increase or decrease the effective length of the composite arm, and spring means incorporated in the pivot connection of the two parts of each arm, said spring means urging the second part toward its outermost position at which the effective length of the composite arm is greatest.

12. In an apparatus for increasing the fluidity of a body of material, rotatable stirring means comprising a rotatable shaft, a plurality of stirring arms mounted on the shaft, each stirring arm comprising two parts one of which parts is secured at one end to the rotatable shaft and extends outwardly therefrom a substantial distance to stir a substantial portion of the body of material when rotated by the shaft, the other of said parts being pivotably secured to the outer end of said first part and being movable from an inner position in which it is angularly disposed with respect to said first part to an outer position in which it forms an outwardly extending extension of said first part, and a pair of stops mounted on the first part of each arm to limit the pivotal movement of the second part.

13. Apparatus according to claim 12- in which the pivot connection between the two parts of each arm permits free angular movement therebetween and confines such angular movement to the plane surface described by rotation of said first part of each arm, and in which the stop on said first part limiting pivotal movement of said movable part toward said shaft is so positioned on said first part that upon rotation of the composite arm in the body of material in the direction of the displacement of said movable part from its extended position said movable part will be moved by said material toward its extended position. whereby during rotation of the shaft in one direction the second part of each arm assumes its limiting outward position and during rotation of the shaft in the opposite direction said movable part assumes its limiting inward position.

JOHANNES EISNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 609,270 Flaherty Aug. 16, 1398 655,552 Gorton Aug. 7, 1900 697,579 Wehmeier et a1. Apr. 15, 1902 1,218,623 Brillhart Mar. 13, 1917 1,615,386 Jackson Jan. 25, 1927 1,616,547 Pontoppidan Feb. 8, 1927 2,292,897 Nielsen Aug. 11, 1942