US2449582A

US2449582A - Pulsating pneumatic stratifier

Info

Publication number: US2449582A
Application number: US608793A
Authority: US
Inventors: Brusset Joan Albert
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-08-03
Filing date: 1945-08-03
Publication date: 1948-09-21
Anticipated expiration: 1965-09-21

Description

Sept. 21, 1948.

Filed Au 5, 1945 J. A. BRUSSET PULSATING PNEUMATIC STRATIFIER 3 Sheets-Sheet 1 Sept. 21, 1948. J. A. BRu'ssET 2,449,582

PULSATING PNEUMATIC STRATIFIER Filed Aug. 3, 1945 3 Sheets-Sheet 2- Sept. 21, 1948.

Filed Aug. I5, 1945 [661mm mdPressares J. A. BRUSSET PULSATING PNEUMATIC STRATIFIER 3 Sheets-Sheet 3 POIhfQfEQVerQa/ Vacuum-Jig 6150" W W M Patented Sept. 21,1948

uurrep mm PATENT orrice amass- I ,mflmmfl WT: Application AIM I, 1.45, N0- ma.

This invention relates to improvements in process and apparatus for classifying and separating mixtures of particles of material oi dlflerent speeiiic gravities and particularly to improvements in the apparatus and process described and claimed in my prior United States Patents Nos.

2,241,842, granted m is, 1941, and 2,353,548,

granted July 11, 1944,

In United States Patent No. 2,353,543 there was described and claimed an apparatus for classiiying and separating a mixture of solid particles of diiferent specific gravities. in which apparatus two. pervious reciprocating inclined stepped decks. as supports for two beds oi the mixture to be separated. were mounted within a closed compartment. the decks preferably being stepped with the steps facing the higher ends thereof, and there were provided means ior establishing successively vacuum and pressure conditions above the decks and means for imparting differential reciprocating motion to the decks in timed relation to the establishment oi vacuum and pressure conditions thereabove. The speciilc means for establishing vacuum and pressure conditions disclosed inPatent No. 2,353,548 comprised a doubleacting oscillating wing piston working in a semicylindrical shell forming a part of the aforesaid compartment. said wing piston being associated with appropriate means ior imparting thereto oscillatory movement the extent of which was variable at the will of the operator whereby to control and/or modify the degree of partial vacuum created by'the wing piston or vane.

It is both expensive and diflicult to construct a wing piston or vane, oi thesort disclosed in Patent No. 2,353,543, sturdy enough to withstand 200 to 300 reversals per minute. in which range of speeds the vane has to operate when the separatory device of the patent is operating at or near its maximum. Moreover, the vacuum-and-pressure construction of the patented device gave a s Clalms. wl. roe-40s) a sharp cut-oi! at the point of reversal in. general establishing successively vacuum and pressure I illustrate a preferred embodiment fixed 1-to1 ratio of periods oi vacuum and pressure, whereas it is in many cases desirable to be able to protract the partial vacuum condition, e. g., to modify the ratio to, say, 2 or 3 time units oi the partial vacuum condition per 1 unit of the pressure condition. Also. the shape of the pulsation elected by the wing or vane oi the patented device leit something to be desired, in that the partial vacuum increased very rapidly at the start of the vacuum stroke but flattened out as the stroke reached the point of reversal and air leaked through the deck and-the bed supported thereon, whereas a gradually rising vacuum with gives a pulsation more to be desired.

It is the general object oi the present invention to simplify and simultaneously to improve the construction of the apparatus described and claimed in Patent No. 2,353,548. One specific obiect oi the invention is to provide a simpler and less expensive, yet more embacious, means ior conditions above the reciprocating pervious deck. Another inventive object is to improve the shape of the pulsation both as to the vacuum stroke and as to the pressure stroke. A iurther inventive object is to provide vacuum-pressure means yielding a longer period of vacuum condition with respect to the period of pressure condition. Still other objects of the invention are to provide ior improved synchronization of the deck motion with the pulsation created by the vacuum-pressure device; to provide a more positive feed of material to the apparatus; to provide a single deck (instead of the pair necessary in the construction of the patented apparatus) having an improved design; and to provide positive relief valve means for controlling the degree of pressure condition.

- Other objects and advantages of the invention will be disclosed in or be apparent from a con-- sideration of the following detailed description oi the separation of coal from refuse and with reference to the accompanying drawingswhich of the invention. In the drawings:

Fig. 1 is a side elevation oithe apparatus, with parts in section;

Fig. 2 is an end elevation, with parts in section. on line2--Ioi Fig. i;

Fig. 3 is a iragmenta' y view of the upper part of the apparatus illustrated in Fig. 1, showing the relative positions of vane and cylindrical sleeve valve at one instant in the pressure stroke; and

Fig. 4 is a chart shoring in two graphs values of the vacuum and back pressure portions of the pulsations produced in the apparatus of the present invention and in the apparatus disclosed in Patent No. 2,353,543.

Referring more particularly to the drawings. ll indicates a horizontally elongated housing at least the upper and central portions oi which are surrounded by enclosure I l. Housing II is somewhat constricted intermediate its mid-portion and its top, and its top portion is in the form of two equal-radius half-cylinders it, l5 spaced Pal at their upper edges it, I! to provide a relatively wide slot opening at the top of the housing. In this upper, open, end of housing II are arranged an elongated rotatable cylindrical sleeve member I. and a vane member 20 having the same radius as sleeve i0, which sleeve I! and vane 20 are substantially as long as is housing II and have a radius very slightly less than that of the half-cylinders ll. ll. Coacting sleeve ll and vane 20 are mounted on shafts 2b", which latter are journaled, in the end walls of housing II, as indicated at 28, 24, for rotation in substantially the same horizontal plane and are so positioned with respect to each other and to half-cylinders I4, I! as to function somewhat as a "gear pump" within the latter. That is to say, during that part of each full revolution-of members II and 20 when the solid segment of vane member 20 is adiacent half-cylinder ll said members I and are so positioned with respect to eachother and to half-cylinders I4 and" as substantially to seal the slot'opening II, I! against downward passage or air to space 2, while simultaneously vane member II is sweeping trapped air outwardly through slot opening II, II into space U. The positioning of members I0 and II illustrated in Fig. 2 represents the end of this stage of operation. indicates a drive pulley mounted on shaft 2i 'and connected by a suitable belt to the drive 'pulleyof an electric motor 00 for rotating sleeve l0, and '20 indicates a gear wheel (likewise mounted on shaft Ii) meshing with a like gear wheel mounted on shaft I2, for rotating vane 20 at "aspeed,"say 200-300 R. P. M., identical with the speed of rotation of sleeve is but in an opposite direction (as shown by the arrows in Fig. 2).

As shown in Fig. 2, sleeve i. has an open segment amounting to about 120, while vane 20 is provided with a sdlld segment amounting to a little less than 90. II and 20 are so mounted on their shafts that the motion of the one is synchronlzed with that of the other, to the end that vane 20 "meshes," as illustrated in Fig. 3, into the open segment of sleeve is for aportion of each revolution,

The lower portion of housing I0 is formed into a pair of inverted pyramidal dust hoppers 80, 3| open at their bases. Hoppers 30, ii are closed at their apices by star extractors I2, 33. The hopper adjacent the'high end of the deck is for the collection of mixed dusts of the heavier and lighter components of the mixture beingtreated,

while the hopper adjacent the low end of the deck is for the collection of relatively clean dust of the lighter component ofthe mixture.

represents an inclined pervious deck mounted, for oscillatory movement in its own general plane, on toggle members ll, ll, supported within housing It). Preferably, deck 30 is formed of perforated sheet material-with perforations of, say. from 16 to 30 mesh-of stepped formation providing slanting faces upwardly inclined toward-the high end of the deck (i. e., the left hand end in Fig. 1) and steep, substantially vertical shoulders joining the upper and lower edges of adjacent slantingfaces. The deck may, as shown in Fig. 1, extend in a single plane; preferably, however, it is so constructed that aportion (e. g., about a third) ofthe high end thereof is slightly bent or concaved upwardly from the general plane of the deck, whereby to provide a steeper climb for refuse at thevend of its travel and hence a cleaner separation. oscillatory movement is imparted to deck 30, from motor N, through eccentric drive ll mounted outside of housing l0 as long as the two bases of dust hoppers II, II

taken together. Beyond either end of deck ll, housing II is provided with two substantially vertical delivery chutes, the one, II, at the high end of the deck, being for the delivery of refuse,

and the other, II, at the low end of the deck,

being for the delivery of clean coal. Chutes II and" are open at their upper ends and are closed at their lower ends by star extractors If, ll, respectively.

I! represents a substantially horizontal screw conveyor communicating between raw material hopper N an'd'the interior of housing I I above deck 30 for delivering a stream of raw material to the deck ata locus intermediate its ends.

The space within housing I! above and adjacent deck II is called herein "2," while that within the confines of half-cyiinders I4 and l! is called Q and that below deck II is called "W." The space between the upper and midportions of housing II and enclosure ii is called herein U." Communication between space U and space W is afforded by a plurality of relief valves "V spaced along the lower part of housing [0 on either side of the latter. Each of relief valves V is composed of (a) a duct 00 'let into the "wall of housing II and laterally extending into space W and presenting in the latter an orifice", and (b) a weighted plate 02, of a size to close orifice 0i, pivoted as at 03 to housing It. Plate 02 is so weighted as to be forced away from orifice 0| when the pressure in space U exceeds some predetermined value (less than 0.50 lb./sq.

in. in all cases, and about 0.25 lb./sq. in. on the average).

when vane 20, upon rotation, approaches the constriction in the upper portion of housing II it, in conjunction with sleeve member ll, traps air in space Q, and upon continued rotation forces at least part of the same through the relatively wide slot ll, l1 and out of housing ll into space U, thereby creatinga partial vacuum or "vacuum condition" in space Z and a corresponding pressure condition in space U. Still further rotation of parts 20 and ll-to the meshed position illustrated in Fig. 3-opens the slot i0, i1, permitting i'iow of air from space U into space Z. The slot remains open until such time as the solid front of sleeve 20, in its continued rotation, ap-

proaches half-cylinder I. By this time sleevehas assumed a position to close the remainder of the passage. A relatively wide slot or port at ll, I1 is desirable in order that air may travel back and forth therethrough with a minimum of lamination.

The synchronized motions of parts I! and 20 and the position of slot opening ii, i! assure, for the size of sleeve is as illustrated, in space Z a vacuum period of two-thirds and a pressure period of one-third of each full revolution (onethird being the ratio of to 360). The period of vacuum conditions lasts as long as it takes sleeve II to rotate by 240, the latter being the width of its blank segment which blocks passage of air between spaces U and Z, during which portion of afull revolution member 20 simultaneously is functioning to force trapped air out of space Q by way of the slot opening l0, l1, into space U, while the back-pressure period corresponds to the 120 rotation during which the empty segment of It faces shaft 22 and member 2! simultaneously is in a position remote from halfcyllnder l5, as shown in Fig. 3, thus affording a large unrestricted passageway, beneath slot opening ll, ll, for the inrush of air from space U into space Z said movement of air being effected by the momentarily existing differential in air pressures between spaces U and Z. Such relative durations of the vacuum andback-pressure periods of the pulsation can, of course, be modified by changing the length of the full segment of sleeve I! (with a compensating change in length of the solid segment of vane 20), the theoretical maximum ratio being 3- (for vacuum) to-l (for back pressure), and the actual maximum ratio being slightly less than 3-to-1. If so desired, the ratio could, of course, be modified in the reverse direction.

For a given apparatus of fixed dimensions, the absolute value of the vacuum producible in space Z above deck .38 is variable by changing the R. P. M. of parts l9 and 20; when they rotate faster there is less time for the leakage of air through deck 38 and the bed of material thereon to reduce the theoretical vacuum which should be created in space Z.

In each pulsation the "vacuum period" is the active period: during the same the stratified clean coal layer (that is to say, the lighter component of the mixture) tends to be lifted away from the refuse (or heavier component) layer, which latter tends to remain in contact with the deck, The so-stratified refuse moves "backward" up the sloping deck following the impulses of the latter, while the clean coal layer moves "forward and downward in counterfiow to the refuse. During the .pressure period the clean coal is pressed on top of the bed of refuse and travels with the latter: the useful role of this period consists mainly in forcing fine dust (raised during the vacuum period) back down into the bed, in order to maintain the bed in air-tight condition. It will be seen, from this exposition, that the pressure period need not be long, as a relatively short blast of back-pressure suffices to press the dust back into the bed; also, that any increase in the relative duration of the vacuum period of the pulsation increases the time per hour devoted to (a) separation of clean coal from refuse and (b) movement of the separated products, in opposite directions, to their respective discharge points. As was noted hereinbefore, I can by means of the present invention prolong the vacuum period-the back-pressure period being constantup to 3-to-1 and hence can increase the throughput per square foot of deck up to an amount 50% greater than that attainable in the construction described and claimed in Patent No. 2,353,543.

It should be noted. also that the "shape of the pulsation afforded by the present apparatus is in most cases more to be desired than that afforded by the patented apparatus. The graphs of Fig. 4 show, for the patented apparatus (in solid line) .and for the newly invented improved apparatus (in dotted line), the relative duration and time characteristics of the pulsations with regard to their vacuum and back-pressure components. In the case of the pulsation by the patented apparatus, the vacuum condition first increases very fast; then, as the wing approaches the reversal point the vacuum graph flattens out.

as air leaks through the deck and bed. ,The back-pressure portion of that graph is a little sharper at the conclusion of the pulsation because the bed becomes more and more compact as the pressure condition continues. In distinction to the above, thegraph of the pulsation afforded by the present apparatus shows a .gradually rising vacuum-due to the constant speed of vane 20; then, at the cut-off corresponding to the unsealing of the slot opening, a sharp drop in the value of the vacuum; and a backpressure condition wherein the back-pressure very quickly reaches its'maximum value, dueto the blast of air which rapidly flows from space Uito space Z during the interval represented-in Fig. 3. with reference to the dotted-line graph of the pulsation afforded by the present apparatus, it is noted that the starting point (left-hand end) of the line denoting vacuum condition represents the point in the full revolution of members II 'and 20 when vane 20 is in a-position approxirotation of vane 20 has brought the latter adiacent half-cylinder ll so as to begin to sweep air trapped in the upper part of space Q outwardly through slot I, I1 intospace U. The positions of members i! and 20 illustrated in Fig. 2 correspond to a point on the dotted line graph relatively close to the crest or point of reversal." The portion of the dotted line which is below the horizontal line denotes the relatively brief portion of the full cycle when a maximum of air has rushed from space U through slots I, II! and past meshed parts-l9 and 20 intospace Z.

Accordingly, the vacuum and pressure graphs indicate opposed characteristics for the pulsation of the patented apparatus and for the pulsation of the vacuum jig: that of the latter is, in'practically all cases, more favorable to classification of the materials according to their specific: gravities, as the vacuum gradually rises to maximum value and abruptly falls oif to zero: similarly, the relatively strong back-pressure at the beginning of the back-pressure period strikes the bed while the latter is in a distended position and more efllciently drives the dust down into the bed.

Regarding the role of the relief valves V, it should be noted that control of the pressure condition obtaining in space U to a low value is important, because otherwise the consumption of power would materially increase and heating would develop. Relief valves V can be adjusted I so that pressure in space U does not exceed onehalf or one-fourth lb./sq. in. The function of these valves is made easier by the relatively large volume of space U as compared to the volume of air displaced by vane 20 at each pulsation (the space within U being from 12 to 15 times the volume of air displaced thereinto per pulsation): hence, a fairly constant value of pressure in space U minimizes actuation of relief valves V.

It may be noted that the use of a worm conveyor, feeding raw coal from a surge pin or hopper, assures a more positive feed of the material; also, that use of a single deck, instead of thepair of decks employed in the patented apparatus, makes for a simpler and more economical construction, and more economical maintenance, for i exceeds about 20% it is advisable to use a, differential motion drive (as described andillustrated in Patent No. 2,353,543) in order to facili- Y 'tate the upward and backward travel of the heavy material. In both cases the deck motion must be synchronised with the pulsation. so that the deck travels forward and downward during the sharpest part of the vacuum period, whereby to favor the segregation of the heavy material into the auassa layer adjacent the deck. Synchronization be- As will be understood, by'one skilled in this art. from a consideration of the. foregoing description and of the drawing, the apparatus is susceptible to considerable variation without departing from the concepts of the present invention. For instance, it readily will be appreciated that the cylindrical sleeve vane combination need not be as long as is the compartment, it being necessary only that they be of reasonable length and that they be co-extensive with the slot opening or port in the topiof the compartment. Also. instead of forming the side walls per se of the compartment into two half -cylinders, ,as shown in Figs. 1 and 3, the curved surfaces for co-operation with the cylindrical sleeve and intermeshing rotary vane may be arranged within the compartment adjacent the top of the latter.

Accordingly. the invention is to be construed as broadly as is deflnedin the appended claims. While the apparatus of the present invention has been specifically described with particular reference to the cleaningof coal, it is to be understood that the same is not limited to that speciflc use but rather is applicable generally in the dry separation of mixed solid particles according to their specific gravities, e. g.. in the dry clean.-

- 8 to establishment of said vacuum and pressure conditions.

3. The apparatus defined in claim 1. wherein th vacuum-pressure-establishing means comprises a rotary cylindrical sleeve member Ilan! an open segment of greaterthan 90 but not greater than about 130", an intermes'hing and cooperating rotatable vane having the same radius as. said cylindrical sleeve member and provided with a solid segment of approximately 90; and means for rotating said cylindrical sleeve member and said vane at the same speed but in opposite directions. Y

4. In apparatus'for classifying a mixture of materials according 'to speciflcgravity, a hori- -gzontally elongated housing having a slot opening at the top thereof substantially parallel to the longitudinal axis of thehousing. a substantially gas-tight enclosure surrounding at least the upper portions of said housing, a reciprocating inclined pervious deck mounted in said housing intermediate the top and bottom of the latter. intermeshing oppositely rotatable and interacting vane and sleeve members within said housing adjacent mg of washing plant tailings and similar finely divided lean iron ores, etc. I

- I claim:

1. In apparatus for classifying a mixture of materials according to specific gravity, a horizontally elongated housing having a slot opening at the top thereof substantially parallel to the longitudinal axis of the housing. a reciprocating inclined pervious deck mounted in said housing intermediate the top and bottom of the latter, intermeshing oppositely'rotatable and interacting vane and sleeve members within said housing ad- Jacent to and coextensive with said slot opening and cooperating with the latter to establish successively vacuum and pressure conditions above said deck, and means for imparting reciprocating motion to said deck substantially in the plane thereof in timed relation to establishment of said vacuum and pressure conditions. I

2. In apparatus for classifying a mixture of materials according to specific gravity, a horizon tally elongated housing having a slot opening at the top thereof substantially parallel to the longitudinal axis of the housing, a reciprocating inclined pervious deck mounted in said housing intermediate the top and bottom of the latter, in-- termeshing oppositely rotatable and interacting vane and sleeve members within said housing adjacent to and coextensive with said slot openin! and cooperating with the latter to'establish successively a vacuum condition of relatively long duration and a pressure condition of relatively short duration above said deck, and means for imparting reciprocating motion to said deck subto and coextensive with said slot opening andgcooperating with the latter alternately to cause air to be exhausted from the upper portion of said housing through said slot opening and to be stored under pressure within said enclosure and to permit air under pressure to flow from within said enclosure through said slot opening into the up:- per portion of said housing whereby to establish successively vacuum and pressure conditions above said deck, and means for imparting reciprocating motion to said deck substantially in the plane thereof in timed relation to establishment of said vacuum and pressure conditions.

5. In apparatus for classifying a mixture of materials according to specific gravity. a horizontally elongated housing havinga slot opening at the top thereof substantially parallel to the longitudinal axis of the housing, a substantially gas-tight enclosure surrounding at least the upper portions of said housing, a reciprocating inclined pervious deck mounted in said housing intermediate the top and bottom of the latter. intermeshing oppositely rotatable and interacting vane and sealing members within said housing adjacent to and coextensive with said slot opening and cooperating with'the latter alternately to cause air to be exhausted from the upper portion of said housing through said slot opening and to be stored under pressure within said enclosure and to permit air under pressure to flow from within said enclosure through said slot opening into the upper portion of said housing whereby to establish successively vacuum and pressure condi-' tions above said deck, and means for imparting reciprocating motion to said deck substantially in the plane thereof in timed relation to establishment of said vacuum and pressure conditions.

6. In apparatus for classifying a mixture of materials according to specific gravity, a horizontally elongated housing having a slot opening at the top thereof substantially parallel to the longitudinal axis of the housing. a substantially gastight enclosure surrounding at least th upper portions of said housing, a reciprocating inclined pervious declr mounted in said housing intermediate the top and bottom of th latter, inter-meshing oppositely rotatable and interacting impelling and sealing members within said housing adJa cent to and coextensive with said slot opening and cooperating with the latter alternately to cause atantially in the plane thereof in timed relation 76 air to be exhausted from the upper portion of 9 said housing through said slot opening and to be stored under pressure within said enclosure and to permit air under pressure to flow irom witbin said enlo ure through said slot opening into the upper vportion of said housing wherebyto establish successively vacuum and pressurejponditions above said deck, and means for imiicrtinz reciprocating motion to said deck substantially in the plane thereof in timed-relation toiestablishment of said vacuum and pressure conditions.

JEAN ALBERT BRUBSET.

'nnmnnucns mm The following references are of record in the tile 0! this patent:

UNITED STATES PATENTS Number Number ll 808,429

France Nov. 14, 1936