US2579607A - Continuous drier - Google Patents

Description

1951 L. J. OSHAUGHNESSY ,579,607

CONTINUOUS DRIER 4 Sheets-Sheet 1 Filed March 10, 1948 mm W TWZ G U Kw Dec. 25, 1951 L. J. O'SHAUGHNESSY CONTINUOUS DRIER 4 Sheets-Sheet 2 Filed March 10, 1948 III IIIIIL NVENTOR LJ. O'SHAUGHHESSY L3 4 6;

-r-r s Dec. 25, 1951 L. J. O'SHAUGHNESSY ,6

CONTINUOUS DRIER 4 Sheets-Sheet 3 Filed March 10, 1948 INVENTOK a z, 1 u, A r H T A l L. J. O'SHAUGHNESSY' 2,579,,607

Dec. 25, 1951 CONTINUOUS DRIER 4 Sheets-Sheet 4 Filed March 10, 1948 mvamorz L-JDSHAUGHNESSY Patented Dec. 25, 1951 2,579,607 CONTINUOUS DRIER Leo J. OShaughnessy South Porcupine,

Ontario, Canada Application March 10, 1948, Serial No. 14,050

13 Claims.

This invention relates to a method and ap-.

paratus for drying granular materials.

Hitherto materials such as crushed rock, sand or crushed ore have usually been dried in rotary driers or in driers which required the use of heavy moving mechanical parts, and a substantial proportion of the cost of drying such materials has been attributable to' the power consumption necessary to drive such parts. Previously known stationary driers have been subject to a number of serious disadvantages, including a non-adaptability to continuous processing, a tendency towards cakingintheproduct, inaccessibility of pipe joints and valves for maintenance purposes and lack of eflicient heat recovery means to render the process economical.

It is the object of the present invention to provide a continuous drier for granular materials which will operate efficiently without heavy moving mechanical parts. p

It is another object of the invention to provide an improved continuous method for drying suchmaterials having a high thermal low processing cost. a i

It is a further object of the invention to pro-' vide a continuous method for drying granular materials in which large lumps are continually broken down on passage through a drying chamefficiency and her to produce a uniform, d y, free-flowing product.

It is a still further object of the inventionto provide a continuous drier for granular materials which requires a minimum of maintenance and in which parts which require regular serv icing are easily accessible and do not come in contact with materials being processed.

Various other objects and advantages of the invention will be apparent from the following detailed specification, taken in conjunction with the accompanying drawings.

In. the drawings- Figure 1 shows a partly cut-away isometric projection of a drier according to the invention illustrating the general arrangement of parts.

Figure 2 is a partly sectional side view of the same drier.

Figure 3 is a detail showing the general method of mounting the pipes and forming the chamber wall.

Figure 4 is a fragmentary detail of one element of the side wall of the drying chamber.

Figure 5 is a side view partly in section of the drier shown in Figure 1 and substantially at right angles to the view shown in Figure 2.

Figure 6 is an enlarged detail of the chute doors in the feed chute and hopper shown in Figure 5..

F gure 7 is a flow diagram indicating the path followed by the drying air in its passage through the drier.

Figure 8 is a fragmentary plan view of one form of vibrating means used in connection with the screens in the drying chamber.

7 Figure 9 is a side view of the vibrating meansshownin Figure 8 taken along theline 9-9.

Figure 10 is a fragmentary detail showing the. method of mounting the rocking bars in the vi-.

brating means.

Figure 11 is a fragmentary detail of a quick closing valve used as an alternative form ofvibrating means. i i s. Figure 12 shows diagrammatically an alterna tive arrangement of screens in the drying cham-.

ber. i

In all of the drawings non-essential structure is either not shown or is shown diagrammaticah ly in order to avoid confusion and preserve sun-.-

plicity.

Referring now more specifically to the draw-. ings, in the embodiment shown a drieraccording to the invention consists of a drying chamberD in which are situated a plurality of heating. members I 0, which are substantially horizontal and so arranged in rows asto provide a plural-;

ity of sloping passageways H between the rows.

Positioned among the heating members ID are one or a number of foraminous members such as screens or grids l2 which may be horizontal shown, or in any one of a number of difierent: arrangements depending on the results desired...

The grids or screensas will be described later. l2 are accessible through suitable hatches such as those shown at I21; and l 2b.

Feed chute I3 is positioned above the drying chamber D in position to discharge material to be dried into the chamber through the chutedis-a charge ports l4 and 15 which are separated the angle member l6 which has its apex in the form of a knife-edge I! pointing upwardly to aid. in breaking down large lumps of feed material. The chute doors l8 and I9 are formed from sheet. material with a hooked end 20 which is adapted;- to rest on a support member 2| as shown in. Fig-.

ure 6 in such a way that gravity will normally cause the doors I8 and shown by the dotted lines to allow passage of the product. The preferred means comprise a hopper 22 which discharges through a row of exhaust:

ports and chute doors 23 similar in construction to those on the feed chute l3, and designed to. prevent any substantial entry of air fromtheatmosphere directly into the drying chamber from below.

l9 to assume a closed position, but when material passing down the chute I 3 is thrown outwardly by the angle member 16- the doors will be forced to an open position as:

Above the drying chamber D is an air conditio'ning chamber F which is open to the atmosphere or other air supply through the air. ports 24 and Z5 positionedon eitherside of'the drier. Inside the air conditioning chamber, which is isolated from the drying chamber by partition 26,,

are a series of baiiles 21 designed and arranged to cause the air entering through the ports 24'and enclosed space H between the inner compartment walls and the outer walls, The enclosed space H communicates at its upper end to the air conditioning chamber F through the outlet at 28; and at its lower end with the bottom of the drying chamberzD throu h the ports. 34 and 35. Passing completely through the air conditionin chamber, through the partition 26, and a top partition '29 are a series of tubes 30' which connect.

the drying chamber D to an outlet manifold G which discharges into an exhaust stack 3|.

Circulation ofair through the drier followsthe plan shown diagrammatically in Figure '7. Cold air from the atmosphere enters the air ports 24 and 25-, is'warmed as it passes up and around the tubesjfi which are heated by the hot exhaust gases, and then passes into the enclosed space H through the outlet 28 down through the space E into the bottom of the drying chamber D where it is heated by the heating members Ill, performs its drying function and rises through tubes 30 through outlet manifold G up exhaust stack 3|. The drying chamber D may be built up in any desired manner, but a particularly simple and eflicient manner which is preferred according to the invention is as follows:

The two ends 40 and 4| of the drying-chamber D are framed by suitable an le supports Ma.

Fitting in the angle supports 4hr are removable angle irons 4-2 and as shown in Figure 3,*which have a series of elongated holes 44 at uniformly spaced apart intervals. The holes 44 are adapted to receive and hold in place the ends of a series of specially designed bars 45 which have web portions 46 with heating pipe mounting holes '41 formed therein. The heating elements or pipes lfl rest on the upper extremity of one su'ch bar 45 and are secured in position by the web portion 48 of the next higher bar 45. Y

The drying chamber D is separated from the enclosed space housing the pipe fittin s and connections by the bars 45 and their webs 46. The ends of the heating elements Ill may be connected in series, or parallel, or preferably a combinationof series and parallel arrangements completely externally to the drying chamber D and enclosed by removable housing covers 4'6 and 48which also house heating medium headers 49 and 50. The

covers 41 and 4B are suitably secured at top and bottom to the frame members of the drying chamber ends 40 and 4| and at either side to the outer walls 32 and 33 of the enclosed space H.

Suitable header valves 5! and 52 are supplied to control flow of a heating medium such ashot gas, hot water or steam, and accessibility is achieved through removable hatches (not shown).

The action of the dryer on material being dried is as follows:

Moist granular material is fed into the feed.

chute l3, falls down the chute, and is divided on knife-edgell'into-two portions which force the chute doors l8 and l9 to an open position and descend into the drying chamber D. The knife- "as it descends and losing some moisture to the drying air which is rising through the drying chamber D. a r

l The moist warm material comes substantially to rest on'the first grid or screen l2, where its progress is retarded due to the binding action of its moisture content, which prevents the material from falling through the foraminations. The warm drying air passing up through the drying chamber, however, permeates the foraminations and locally dries the material causing it' locally to fall away from the foraminations when the binding action of the moisture is locally re duced. The conditions of moisture content for any'giv en size and type of material'at the time of falling away are largely governed by the size of the foraminations, and the larger these are. the wetter-the materials which will fall away. As the material locally falls away over the :whole area of the grid or screen, the bulk of the material will settle and the process repeats itself, only the material which has reached a certain state ofdryness passing the grid or screen.

Subsequent screens or grids may have smaller foraminations or finer mesh to ensure a higherdegreeof dryness of the material at-it progresses down the drying chamber.

When it is desirable to pass material through one or more of the screens or grids before it has reached a certain state of dryness vibrations are imparted to the screens or grids and the flow through the foraminations is increased.

One arrangement for imparting vibrations to the screens or grids I2 is illustrated in Figures 8,9 and 10. ported by a series of rocker bars '60 which are themselves supported on supporting members 61 which are suitably supported from the frame of 7 similar ball and socket means 65 to each individual rocking bar 60. The vibrator bar '64 terminates in a vibrator box shown diagrammatically at 66 which is provided either with a small electric motor having an eccentrically weighted fly- 7 wheeler some'other suitable vibrating means.

An alternative method of producing vibrations in the drying chamber is by means of a quick closing valve connected to the exhaust header 50 and operated intermittently to produce vibra- V tions from the shockeffect created by the sudden stopping and starting of the flow of heating medium in the pipes I0. A suitable arrangement is illustrated in Figure 11 and consists essentially of a valve seat 10 situated in the exhaust manifold G. A valve'head H attached to a'valve stem 12 is adapted to cooperate with the valve seat 10. A cam head, 13 is screwed on to the opposite end of, the valve stem and secured in position by a lock nut I4. Also screwed on to the opposite end of the valve stem 12 is a guide piece 15 which is adapted to slide up and down in the guideway 16 as the valve is operated.

In this case the screens are sup 5. A compression spring 11 extends between a fixed bushing 18 and the guide piece 15 and continually urges the valve'stem 12 in a downward direction. A smallwheel 19, adaptedto rotate in the direction of the arrow, is mounted 1 on the shaft 80 which ishoused in bearings 8| in fixed position as shown at the bottom end of the guide-'- ways 16 below the valve stem 12. l a l A series of cam shaped lugs 82 is mounted on the periphery .of the wheel 19 and as the wheel turns these successively engage the 'cam head 13 forcing the valve stem 12 in an upward direction, unseating the valve H, and allowing heating medium to flow through the valve. As the wheel continues to operate, however, the cam 82 suddenly disengages the cam head 73 and the spring 11 reasserts itself to seat the valve head 1|. The heating medium flow is brought to a stop abruptly causing the whole drying chainber to shake. The rapid succession of similar operations as successive cam shaped lugs 82 en gage the cam head produces constant vibrating throughout the chamber. Very little power expenditure is necessary to operate a vibrator of this nature and a small electric used to rotate the wheel 19. A i

The dry material is finally collected in the hopper 22 and discharged through the chute doors 23.

Various arrangements of screens and grids may be employed to vary the effects produced.

For instance, sloping screens may be used to carry on a partial separation of particle sizes simultaneously with the drying action or combinations of sloping and horizontal screens, or

curved screens may be employed to produce different results. Where the material has a tendency to cake, some such arrangement of screens as shown in Figure 12 is desirable so that the material is subjected to a continual tumbling action as it descends among the heating members in and partially through the sloping grids. It is a simple matter to change the arrangement of the grids or screens and a matter of mere mechanical skill to adapt the arrangement to produce the most emcient results for any given material.

Added heat economy may be provided if .desired by coating the outside of, the entire apparatus with asbestos insulating compound;

What I claim as my invention is:

l. A continuous drier for granular materials comprising a drying chamber, means for Supplying material to be dried to said chamber,;dried material collecting and delivering means'be-low said chamber, means forproviding an upward motor may be along and partially all r her for causing air to bers being arranged in sloping rows to providesloping passageways between said rows, and foraminous means positioned among said heating members to retard the descent of material being dried until a certain condition of dryness of said material has been achieved, said means for providing an upward flow of pre-conditioned air through the drying chamber comprises an airconditioning chamber positioned above said drying chamber, air intake means communicating said air-conditioning chamber to a source of air, bailie means within said air-conditioning chamfollow a tortuous path therethrough, a plurality of tubes communicating. the drying chamber to an exhaust stack arrangement above said air-conditioning chamber, said tubes passing through said air-conditioning chamber to exchange heat with air flowing therethrough, and means communicating the top of flow of lore-conditioned air through said drying chamber, a plurality of substantially horizontal substantially parallel spaced apart heating members traversing said chamber, said heating members being arranged in sloping rows to provide sloping passageways between said rows, and means for retarding the descent of all the material being dried until a certain condition of local dryness has been achieved therein comprising aforaminoas sheet positioned adjacent said heating members and forming a drying boundary extending across said chamber.

2. A continuous drier for granular materials comprising a drying chamber, means for supplying material to be dried to said chamber, dried material collecting and delivering means below said chamber, means for providing an upward flow of pre-oonditioned air through said drying chamber, a plurality of substantially horizontal the said air-conditioning chamber to the bottom of the said drying chamber, said means including an air conducting passageway formed externally to the said drying chamber and said air-conditioning chamber.

3. A continuous drier for granular materials as defined in claim 2 in which the means communicating the top of the air-conditioning chamber to the bottom of the drying chamber consists of an air passageway formed outside and substantially surrounding both of said chambers, said passageway being defined on its inner side by the walls of the said chambers and on its outer side by an outer wall spaced apart from said walls of said chambers.

4.A continuous drier for comprising a drying chamber, ing material to be dried to said chamber, dried material collecting and delivering means below said chamber, means for providing an upward flow of chamber, a plurality of substantially horizontal bers traversing said chamber,

sloping passageways between said rows, and foraminous means positioned among said heatingfmembers to retard the descent of material being drieduntil a certain condition of dryness of said material has been achieved, said heating members traversing the drying chamber are tubular and are mounted in sloping rows on specially designed bar members, said bar members having bar portions and web portions, the web portions being formed with a plurality of spaced apart recesses, said recesses being designed when said bar members are in position to receive and hold in position said heating members, the connec tions of said heating members being external to the wall formed by said bar members when in position.

5. A continuous drier as defined in claim 1 in prises at least one screen having a mesh that will not pass damp granular material but will pass dry granular material, and in which said screen is at an angle to the horizontal.

6. A continuous drier for granular materials as defined in claim 1 including vibratingmeans to vibrate the retarding -means in the drying chamber and increase flow of material therethrough.

7. A continuous drier for granular materials comprising a drying chamber, means for supplyfor granular materials which the sheet comgranular materials means for supplyire-conditioned air through said drying cam-w? ing :material -;to :he driedzto said chamber; d e

' sloping passageways between said rowspa'nd fonaminous means positioned amongsaidi heating members to retard the descent of material being dried until-a certain condition of dryness ofsaid material has been achieved, vibrating meanssto vibrate theretarding means in the drying chamber and increase flow and :material therethrough, said vibrating means comprising amounting for the foraminous means consisting of; a plurality of rocking bars reckably mounted at- .either :end to opposite Sides of said dryin chamber, a vibrator bar rockably connected to each of said rocker bars and connected at'one end .to vibrator means mounted on the outside of-thed-rier.

18. ,A continuous drier for granular materials comprising a drying chamber, means forsupp'lying material to be dried to said chamber, dried material collecting and delivering means below said chamber, means for providing an upward flow of pre conditioned air through said drying chamber, a plurality of substantially horizontal substantially parallel spaced apart heating members traversing-said chamber, said heating members being arranged in sloping .rows to provide sloping passageways between said rows, and

foraminous means positioned among said heating members to retard the descent of material being dried until (a certain condition of =dryne'ss of said material has been achieved, vibrating means to vibrate the retarding means .in the drying chamber and increase flow of material therethrough, said vibrating means comprising a quick closing valve mounted near the outlet header of said heating members and adapted to openand close to cause the drying chamber to be intermittently vibrated by the intermittent checking offlowo-f heating medium through said heating members.

9. A continuous drier for granular materials as defined in claim 3 in which the quick closing valve comprises a valve seat in the outlet header, 1 a valve head adapted to cooperate with :saidvalve seat, a valve stem attached to said valve head, spring means continually urging said valve to a closed position, cam means secured to the end of said valve stem and rotatable means for inter mittently displacing said cam means to open said valve.

10. A continuous drier for :granular materials aszdefined in claim 9iin which the rotatable means comprises a power driven jwheel comprising at least one circumferentiallymounted cam shaped lug adaptedon rotation'of said wheel tocoopcrate with the-cam means secured'tothe valve stem :to longitudinally displace the same.

11. A method of continuously drying granular materials lwhichnomprisesfeeding said materials into --a drying chamber, heating said materials and-retarding :fiow of said materials for forami nous means having a mesh that will not pass moistgranular material'but'will pass'dry granular material, exposing said materials to themtion of an updraft of drying air, whereby said permeating foraminations in said f oraniinous meansdocally dries the material in the immediatearea-of saidforaminations causing dried materialito -:f alleaway -therethrough and causing the bulk aoiasai'd material to shift to continually ex-- pose fresh moist material over said foramina tions. 7 r V :12. aalmethod as definedin-claim 11 comprising vibrating "said foraminous means to increase the flow of material therethrough'. V

13. A method of continuously drying granular materials which'comprises feeding said materials into a drying chamber, heating -said materials and retarding flow of said materials by foraminous-means having a mesh that will not pass moist granular material but will pass dry granular material,.:exposing said materials to the-action of an updraft of pro-conditioned air, whereby said air, permeating :foraminations in said foraminous means locally dries the material in the immediate area of said foraminations-causing dried material to fall away therethrou'gh and causing the bulk of said material to shift to continually expose fresh imoist materiatoversaid f oraminations,

and vibrating said foraminous means by intermittently stopping and starting the flow of heat through heating members in the drying chamber."

LEO J: 'OYSHAUGHNESSY.

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

UNITED STATES PATENTS

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