US2602595A - Fluid impact pulverizer - Google Patents

Description

July 8, 1952 w. A. THOMAS 2,602,595

FLUID IMPACT PULVERIZER Filed Dec. 29, 1945 2. SHEETS- SHEET 2 INVENTO'R Patented July 8, 1952y FLUID INEPAC'I PULVERIZER William lA. Thomas., Pittsburgh, Pa., assignonte .Blew-Knox C.ompa,ny,Pittsburgh,Pa., acorporationof New Jersey rApplication December 29, 1945, SerialLNo'.-6?7,82,0.`

' 6V Claims. (Cl. 2211-939) This invention .relatesA to. apparatus gior-pulverizing solidsyby impact: .of particles with. veach other while traveling at;high. speed,.and to-means for. separating. and removing. the particles which Y2 Supplying nulverzedcoalier eembustioa ineluding` my invention;

Figure 2 is an elevation partly broken Aaway showing the pulverizer yof my invention with 4a have been reduced; toxthe. desired neness', and 5. portion in.centralvertical.-section; returning the;oversize:.particlesgfor further grind- Figure 3 is a vertical section taken-.along the ing, plane of line .III- IIIof-Figure 2;!

Impact grinders orfpulverizersV utilizing a gas vFigurei isa horizontal'section takenalongthe under pressure asamotive zuidihave: been known` plane of line IV-IV of Figuref; heretofore but havebe'enLsubject tocertain'limil0 Figure 5 is a portion of Figure 3 to enlarged tations. Itis the. objeetofzmyninvention to: proscale.; and l vide improved impact...-pulverizing apparatusof Figure .fi-isv a.. p ar tia1. horizontalsection.taken simple construction, capablegofeffecting the along theplaneof linefVI-VI of Figure. 5. desired pulverizationJ withaminimunrconsump- 4Referring in',d'etail to the drawingathe inventionof :steam andl other Adesirable operating char.- 15. tionis particularly .useful inithe xpulverization. of

acteristics such as fpreliminaryrrern'oval of dust or iinesfrom thematerialtoi-be.pulverized,;uniformity in the neness oiftheproductat various rates of feed, and .the ability. to .grindmaterialhaving a considerable moisture. content, as readilyv as relatively. dry material.

. In a preferred.embodiment,.theinventioncomprises a closed. vessel, conveniently a f cylindrical tank, withits axis-vertical, apair; ofiopposed gasjet injectors infthe lowerpportionthereot and a feederthereabove'for. delivering `solidmaterial to be reduced in: theform Ioii coarse :particles Vor small'lumps for pnlverizaton byzimpact. Above the .feeding means I provide a. classifier chamber having a vcircumferential inlet opening. Guide venes spaced aroundthe nnenins: impart; e tengentia'l Velocity component` to -thelentering gas stream entraning solidpafrticles of-.various sizes. An outlet pipeextending centrally; i-nto the classifier.. permits the escapeofanarticleswhich have been reduced suiiiciently Vin sizeto iloa-t in .the outiiowinggas. The lower portion ofthe classieris-in the form cfa hopper for collecting over,- size particles Aand returning, them tothe-entering stream ofsolid material.` iniportantfea-ture ofthe invention is theprovision-Y of a positive downward force on vthe. oversizel particles which tends to insure eiectiveseparation. thereof from the liner iioating particles.

Further details, novelfeatures and advantages of the invention will be explained during the fol!- lowing -complete description.,whih refers tothe accompanying drawings illustrating a preferred embodiment of the inventionand a typcaL systeniin which it is..adapted. tolserveviaapparatus for supplyingr pulverize'dcoal to a, furnace.- Jfor combustion. i v i Y In the drawings:

Figure 11 is a. diagrammatic. elevaaenwitn la portion ingsection showing 4et.Grilliplete system. Afor coalv for combustionalthough. it is-by no means limited to this specific @application It. will rbe described in detail, howevenl with .refe-rence. to such application. .As showninFigure 1,-the pulverizer indicated generallyfat l0. is adapted to receive coal .from a storage hopper .H by means of. a screw conveyor ,l2 which dischargesinto thev inletof a feeding mechanism .|3. .Thefeeding vmechanism is preferably ofthe injectortype dis.-

closed in detail and claimed in .my copending application, Serial No. 637,319, filed December 29, 19.45, Patent No. v 1420;388 for Apparatus Afor FeedingGranular. Materialnto a Fluid Stream. Pulverized coal .produced by my inventionnows through a delivery- PipeMito as eparator lv5fof known Aconstructioneiective to separate mostfo'f the coal from the vrnotixrefluid,usually.superheated steam. 'Ifhe- `coal falls into @burner-*i6 which is supplied with l air yfor Ocombustion-byfa blower H throughfiinpipe i8. v-'Ih u elandwair are ,1i-red inicia furnace. Greiner ce i9. 'Steam disehareedibv thefseeeraiorl iOWS through e einen with eels/a smellfrertin 2f-ib@ Coal: into the. combustion .space l 9 .Referring .HOW-1119K@ BatilllalyiOLFgllfS .2 throush for. a detailed description Qf; the .m11- verizer` il), it will be s een that. it comprises. ai. cylindrical tank having 5.a vside wall l,y a bottoml` 22 and a top er cavern. elisir .ef .ocpeeedieietors Haare. disposed inthe tank at.-a levelsoinewhat. above` the.bottorngZZ.v Each injector coinprises a. nozzle 325 connected y to. .a suitable source of motive fluid, such 1assuperheated. steam,. andA athroatl. v'llrienozzle v isinQuilted radially on the side. wa11pf-the taakwhuetne throat.v earried by. a strut: 2lv extendingv upwardly. from`the bottom. 22. shownrlthe. twoinjecto'rslare. axially alinedl and s ,paced slightlyapartA Va result, lthey areadapted:tofdischarge-jets ofsteain and solid particles entrained therewith into direct or head-on collision.

The feeding means I3, as previously stated, is of the injector type and includes a Venturi throat 28 and a nozzle 29 connected to a suitable source of gas under pressure such as superheated steam. In accordancewith well-known principles, the injector servestodischarge intfthe interior of the pulverizer I a jet of steam entraining solid particles drawn in through the inlet indicated at 30 in Figure 1. In the particular example being described, the solid material is coal which has been initially reduced to particles of approximately 1/2 in diameter. The feeding means I3 has an outlet or mouth 3|.` Coal discharged therefrom strikes a concave deflector plate 32 mounted on the sidewall 2| striking the defiector the coal particles rebound and fall downwardly with some fragmentation and the resulting particles are, after a certain amount of eddying and helter-skelter circulation, entrained by the steam jets delivered to the injectors 24 by the nozzles- 25. As shown in the drawings, the axis of the feeding mechanism I3 lies in a vertical plane normal to the vertical plane through the axes of the injectors 24. The injectors, as already stated, discharge jets of steam and particles into direct collision whereupon further fragmentation of the particles occurs.

Any dust or similar fine particles accompanying the coal delivered into the pulverizer by the feeding means I3 are floated upwardly by the general movement of the steam within the pulverizer in that direction.' `Such material needs no further grinding and, because of its fineness, floats readily upward and is thus effectively separated from the larger particles which are drawnjinto the injectors as just explained. Additional fine particles produced by the collision of ycoarser particlesjin the space between the discharge en ds of the injectors 24 also float upwardly in the ascendingmass of steam. Coarser particles may accumulate on the bottom of the pulverizer but 'are agitated by the jets from injector 28, 29 and eventually are again drawn into the steam jets'of the' injectors 24 and subjected to vfurther impact. Thus all the material delivered to the pulverizer is progressively reduced to a fineness such that it can escape by notation in the upwardly moving steam.

A classifier 33 in the upper portion of the tank comprises-fa cylindrical chamber open at the top. The Achamber is supported from the cover 23 on hangers 34 so that the upper edge of the chamber is spaced a substantial distance below the top of the tank, leaving a circumferential opening or inlet for steam and floating particles of coal orv other solids. An outlet 35 extends centrally through the top 23 and downwardly intol the chamber 33 terminating at a level below the upper edge thereof. This outlet is connected to delivery pipe I4. vertically disposed guide vanes 3E are hinged at their outer edges in a ring 3'| securedl to the top of the chamber 33 and a plate 38 secured tothe cover 23. A ring 39 having radial slots 4|] rests on the upper edges of the vanes 36. The vanes have projections 4| extending upwardly from` their inner edges into the slots 49. Thus by slight angular movement of the ring 39, the angular position of all the vanes may be simultaneously adjusted. To permit such adjustment, an actuating shaft 42 having a` handle V43 Aisv secured to of the tank. On'

one of the vanes and extends upwardly through the cover 23.

The vanes 36 are adjusted to impart a tangential velocity component to the steam and coal particles owing upwardly through the space between the chamber 33 and the tank wall 2| and inwardly into the former. 'Ihis creates a vortex in the chamber'from the center of which steam and fine particles oating therein ascend through the outlet 35 and flow through the pipe I4 to the separator I5. Coarser particles which arrive in the chamber 33 are thrown outwardly by centrifugal force and thus removed from the steam ascending into the outlet 35. These coarser particles travel around inside the chamber 33 and fall gradually into a hopper 44 therebelow. The lower end of the hopper is connected to a branch opening 45 in the outlet 3| of the feeding mechanism and thus returns the coarser particles to. the entering stream of solid for further grinding by repeated impact as previously described. The jet of steam and solid material delivered by the feeding means I3 creates a positive down draft through the chamber 33 and hopper 44 and thus prevents any tendency of the rising steam to pass through the classifier in the reverse direction.

It will be apparent from the foregoing that the invention provides a pulverizer having numerous advantages-over similar devices known heretofore. The apparatus-is simple and compact and requires no particularr attention during operation. The continuouscirculation of solid material repeatedly through` theropposed injectors causes it to be progressively reduced in size until it is fine enough toiioat inthe outgoing steam. The separation of the fine particles takes place in two stagesfthe'first occurring as the material is initially fed into the tank. Any fines accumulated with the larger particles are immediately floated upwardly .along with those resulting from repeated impact'sof previously fed particles. This preliminary dedusting of the entering material increases Vthe total output since it removes from 'the zone of active pulverizing that portion of the entering material. which is already fine enough to Vrequire no further grinding. The second stage of'separation, of course, takes place in the classifier chamber 33, the finer particles ascending from the center of the vortex with the outgoing steam and the larger particles being thrown against the' Wall of chamber 33 and drawn downwardly into the hopper 44 and thence to the entering stream of 'fresh material.

Y The invention vhas the further advantage that the operating rate maybe varied without materially affecting the iinenesvs ofthe product. The volume of material'ground vmay be varied by changing the rate of feed and without altering the amount of steam. The steam consumption per pound of solid ground is such that the operating cost is not excessive. The apparatus is capable of grinding fuel 4with'as much as 10% moisture. This was impossible with previous de- 1 which are thrown to the outskirts of the central vortex in the chamber andthe ffm'er, therefore, f

are the 'particlesijwhichactually,escape. The apparatus exhibits a satisfactorily low rate of wear despite the abrasivequality of the material being pulverized.

Operation lofthe apparatus `results in the building up of only a small y accumulation of partlygground material inA the. bottom of vthe-tank and this is. promptly disposed of 'when the input of A solidmaterial is discontinued.v The amountV of thisaccumulation, furthermore, does not build upas therate of operation is increased. v It will b e .understood that c :hanges inthe con,- stniction illustrated and described may be made within the, .s,cope of my invention. Instead of l-lyng 01.1, the je? f nQQmDg; material-t0 Vpm" C1119? ,llf'tyQWldaftihpllgh theasse heeren a Seperate .Steam viet inieeier may 'be erhployed. Qn the other hand, the hopper .may vbe constructed to deliver adjacent -the inlets ofthe injectors 2d, les a further alternative provision af-heli'cal flight'or vane may Ybe mounted inthe hopper ontheclassifier. Other modiications metil alsbe made Asuch as utilizing the reduction-inpressure at the inlets oi 4the injectors to ydraw infreshmaterial, instead of providing the'separate feeding y means shown at i3. The internal shape-offthe thro'at'slZ-l of the injectors may be varied but that illustrated has proved toV be hignlxelective.

It will be understood that the aforementioned modiiications as well as other changes in the details of construction are contemplated within the scope of the following claims. Y

I claim:

l. In an impact pulverizer for solid particles, in combination, a closed chamber, a pair of horizontally extending injectors having open-ended throats with both of their ends opening directly in said chamber, nozzle means for injecting a gaseous fluid under pressure through said injectors, said pair of injectors being coaxial and in opposed relation to one another across an unobstructed impact zone to force said particles to collide, means for withdrawing gaseous fluid and nner particles from said chamber at a vertically spaced zone above the injectors, means for injecting a stream of solids and gas directly into said chamber between said withdrawal means and said injectors, .said injection being directed at a downward angle to a horizontal `plane through the axes of said injectors and suiciently near the plane of the injectors to assist in maintaining a circulation of the solids in said chamber.

2. In an impact pulverizer for solid particles, in combination, a closed chamber, a pair of horizontally extending injectors having open-ended throats with both of their ends opening directly in said chamber, nozzle means for injecting a gaseous fluid under pressure through said injectors, said pair of injectors being coaxial and in opposed relation to one another across an unobstructed impact zone to force said particles to collide, means for withdrawing gaseous fluid and finer particles from said chamber at a vertically spaced .zone above the'injectors, means for injecting a stream of solids and gas directly into said chamber between said withdrawal means and said injectors, said injection being directed at a downward angle to a horizontal plane through the axes of said injectors and suiciently near the plane of the injectors to assist in maintaining a circulation of the solids in said chamber, the interception of said angle with said plane being outside said impact zone.

3;-, .11j-an impact ,pulverzergfer Solid particles; ineembinetienie closed: chamber e reir ef herizon-tally extending i,njectors-A having open-ended throats with Vboth-V ottheir ends opening` directly insaidjcharnber.. I'nozzle means for injecting a easeeue .'.flurrunder pressure through. seid injecters, .Said pair Qf; inieetors beiney .coaxial vand in o pposedrelation to one Vanother acrossI an un- Qbstruetedimpeet zonel teioree Sa'df particles te er)A de, aelaeeervesselmeuntedfin seid chambe, v-.senferelly eboveaid injectors. means for withdrawing gaseous-iluidand finer particles from sai d ehamber through said classifier vvessel,v said classiiieryessel having a lower portion forming e-,heperhevine a'diseheree opening emptying lntofsaid'chamber? to; return the coarser portions of said nner particles to said injectors, and means for injecting afstream of solids and gas directly intosaid chamber betweenfsaid classifier vessel and said ,injectorsvsaid injection being directed at a `downward,'angle to .a horizontal plane through the axesof said injectorsand suiciently near the plane of vtheinjectors to-assist in maintaining a Circulation 0i the ysolide in Seid chamberfl; lim-animpactpulverizer fornsolid particles,

in combination,arclosedgchamber, a .pair of hori-v zontally extending, injectors vhavingopen-.ended throatfsgwth bothfieftheirrends opening directly in said chamber, nozzle means for injecting a gaseous fluid under pressure through said injectors, said vpair of injectors being coaxial and in opposed relation to one another across an unobstructed impact zone to force said particles to collide, a classifier vessel mounted in said chamber generally above said injectors, means for withdrawing gaseous fluid and ner particles from said chamber through said classifier vessel, said classiiier vessel having a lower portion forming a hopper having a discharger opening emptying into said chamber to return the coarser portions of said finer particles to said injectors, and means for injecting a stream of solids and gas directly into said chamber between said classifier vessel and said injectors, said injection being directed at a downward angle to a horizontal plane through the axes of said injectors and sufciently near the plane of the injectors to assist in maintaining a circulation of the solids in said chamber, said hopper being connected to said lastmentioned means to assist in the return of said coarserportions to said injectors.

5. In an impact pulverizer for solid particles, in combination, a closed chamber, a pair of horizontally extending injectors having open-ended throats with both of their ends opening directly in said chamber, nozzle means for injecting a gaseous fluid under pressure through said `injectors, said pair of injectors being coaxial and in opposed relation to one another across an unobstructed impact zone to force said particles to collide, means for withdrawing gaseous iiuid and finer particles from said chamber at a vertically spaced zone above the injectors, an injector-type feeding means having its outlet mouth discharging directly into said chamber immediately adjacent said impact zone between said withdrawal means and said injectors to assist in maintaining a circulation of the solids in said chamber, said feeding means being directed ata downward angle to a horizontal plane throughthe axes oi' said injectors, the axis of said feeding means lying in a vertical plane normal to the plane through the axes of said injectors and substantially eccentric relative thereto.

6. In an impact pulverizer :for solid particles,

7k in combination, a closed' chamber. a pair of horizontally extendinginjectors having open-ended throats withboth of their ends opening directly in saidv chamber, nozzle means for injecting a gaseous iiuid under pressure through said injectors, said pair of injectors being coaxial andin opposed relation to one another across an unobstructed impact zone to force said particles to collide, a Aclassier-vessel mounted in said chamber generally above said injectors, means for withdrawing gaseous iiuid and finer particles from said chamber through said classifier vessel, said classifier vessel having a lower portion torming a hopper having a discharge opening emptying into said chamber to return the coarser portions of said iiner particles to said injectors, means for feeding gas and fresh particles to said chamber between said classifier vessel andsaid injectors, said means being directed at a downward angle-to a horizontal plane through the axes of said injectors and sufiiciently near the plane ofthe injectors to assist in maintaining a circulationof the solids'in said chamber, and gas feeding means to assist in the return of said coarser portions to said injectors and prevent any reversal in the direction of ow'in the lower portion of said classiervvessel. Y

- WILLIAM A. THOMAS.

8. .REFERENCES crrDf The following.references are of record in the le' of this' patent:V

UNITED` STATES isna'risiirrsv Number Name Date 291,367 Luckenbach Jan. 1, 1884 1,058,313 y Luckenbach Apr. 8, 1913 1,325,676 McKelvey Dec. 23, 1914 1,367,635 Sturtevant Feb. 8, 1921 1,614,314 Murray et al. Jan. 11. 1927 1,622,695 Willoughby Mar. 29, 1927 1,702,248 Crites Feb. 19, 1929 1,847,009 Kollbohm Feb. 23, 1932 1,914,282 OToole June 13. 1933 1,935,344 Andrews et al Nov. 14, 1933 1,948,609 Andrews et al Feb. 27, 1934 2,032,827 y Andrews: Mar. 3, 1936 2,055,385 Noack Sept. 22, 1936 2,072,492 Anger Mar. 2, 1937 2,175,457' Dunn Oct. 10, 1939 2,285,429 Frisch June 9, 1942 2,385,508 Hammond Sept. 25, 1945 2,413,420 Stephanof Dec. 31, 1946 2,487,088 Andrews Nov. 8, 1949 FOREIGN PATENTS Number Country Date France Oct. 5, 1936

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