US2068077A - Pneumatic drying device - Google Patents

Description

Jan. 19, 1937. P. RoslN ET AL 2,068,077

PNEUMATIC DRYING DEVICE Filed Aug. ll, 1953 Sheets-Sheet l Fig. 1.

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WVM/'70H5 P aal 7170s am Enc/z dmmlef' Jan.191937. P.Ros|- ETAL I 2,068,077

PNEUMATIC DRYING DEVICE l Filed Aug. 11, 193s r 4 sheets-sheet 2` Pa Z Pos E'r'cz Femm @f 'BY ATTRA/EY Jan. 19,1937. v

P. RoslN ET AL PNEUMATIC DRYING DEVICE Filed Aug.l 11,419.33 4 Sheets-Sheet 5 /A/vf/vroR'S Eaa Pou' Jan. 19, 1937. R Roem ET AL 2,068,077

PNEUMATIC DRYING DEvIcE- Filed Aug. 11, 195s 4 sheets-Sheet 4 Fig, 4.

14 11X\ /jl l Patented Jan. .19, 1937 PNEUMATIC DRYING DEVICE Paul Rosin and Erich Rannnler, Dresden, Germany; said Rammler assgnor to said Rosin Application August 11,

1933, Serial No. 684,642

Germany August 27,1932

3Claims.

This invention relates `to pneumatic drying devices.

` f It is known that when material with granules l:of various sizes is dried the finer granules are 5 dried faster than the coarser ones, so that granvules of' different size leave the drying device.

with a correspondingly dijerent degree of remaining moisture. This disconformity in the degree of drying is the greater,-the more the granulesdiifer in size, the smaller their heat `conductivity and the higher their resistance to 'diusiom This disconformity is often very detrimental to the use ofthe material for its intended purposes, and occurs, as isy well known, for instance, in steam drying devices used in the manufacture of brown-coal briquettes. It occurs, however, even more in pneumatic drying devices, due to the `drying being restricted to a period of a vfew seconds only.

.If the ydrying operation lis carried out in a vice can be inserted, and the larger particles can thus be crushed several times and kept in circulation until they'are' dried to the same degree as the vfiner fractions, owing to the extension of the drying period and to the reduction in size combined therewith.

' Such intermediate crushing, however, is not in all cases fpossiblef It is, therefore, an object y of the invention to providefor the drying of all granule sizes to the same extent even'in those pneumatic drying devices wherein no intermey diate crushing is provided. This V`is achieved, .according to the invention, by resolving the con- A` single fan only is then required to suck or force the heating gases through the system. Or 56 alternatively, if itdesired to obtain the indiyidual granulel size sseparately, a separate `cyclone device isarranged behind theair sifter of each branch, thewaste gases coming from` the individualfbranches'being removed either by circulation system, a grading and crushing de duit to a system of parallel or series-connected one commonA fan or by several fans. If the (ci. ca -34) branches are not interconnected in parallel but in series, only the last mentioned arrangement is possible.' If, in this case, .it is not desired to obtain the fractions separately, a helical collecting conveyer or other suitable conveying device can be provided underneath the cyclone devices. y v

A In this way, the drying period for the larger particles can be increased according to their size, to a multiple as compared with the smaller particles, by arranging a corresponding number of drying stages. If, for instance, material of, say, 0 to 10 mms. size is to be dried, the -Whole material first passes through the first branch,4 and the wind vsifter arranged in the latter may separate out, for instance, particles of 2 to 10 mms. and pass them on to the second drying branch whilst the particles of 0 to 2 mms. are conveyed directly to the cyclone separator. The particles of 2 to 10 mms. are then dried further by fresh heating gases; in the second branch is arranged another air sifter for separating out the granules' of, say, 5 to l0 mms.

which are passed to the third drying branch,`

whilst the particles of 2 to 5 mms. areconveyed to the cyclone device. After passing through the' third drying branch in which they are. again brought into contact with fresh heating '.gases, the particles of more than v5` mms. size eventually also reach the cyclone device. Thus, whilst the particles of Onto 2 mms. Ionly pass the i'lrst drying stage, those of 2- to 5 mms. 4are treated'in two, and those of 5 to 10 mms.

even in three drying stages.

between the freat` heating gases and the ma- Ite'rial to be treated, the drying process is carried out very fast and in a comparatively short conduit system. The distribution vof the material to the branches, both as regards quantity and granule size,` can be made variable with the aid of control members in the air. sifters.

The drying process can also be inuenced `by introducing the heating gases at variable-temperatures into the several drying branches, for instance, by the addition of controllable quantities of cold air or waste gases in the Vindividual parallel conduit branches; this is of special value in the-treatment of material whichv is sensitive tovtemperature. On the other hand; fresh heat- Owing to the great difference in temperaturev` ing gases can be added'in each branch in the case of` series-connection tdraise the temperature. l

The'invention will be best understood by reterence-tothe accompanying forming a from their respective cyclone ldevices through- 'part' of this speciiication and in which air-locksl I6, I6', IB" and carried oir separately.

Fig.. 1 is a diagrammatic view of one fnn of Waste gas conduits provided with throttle valves apparatus embodying the invention; I5 connect the cyclone separators witha come Fig. 2 asimilarV view of another form of the m'on suction pip 4 leading to the fan 6. 5 same; L ^Fig. 4 showsan arrangement in which the Fig. 3 a similar view of another form of `the branch conduits .are series-connected: The pre- Ysameiand liminary drying is.` carrie'd out at` the highest" Fig.'4 a similar view of still another form of stage of temperature. In the sitter II, the me- C' the same. diuni and large material is separated and fed 10 means of a fan 6 arranged at the end'oi the three parallel drying branches consisting of serrotary chamberdrum III,- to the drying semen- V Y tine v2, whilst the heating gases escape the 7 e when and e feeding device la to tne'nnsi -drying serpentine 3, whilstftheimedium products branch conduit can be controlled by means of 60 turned from the cyclone or dust separatonenter the p ipes.

- by straight upwardpipes `and the placed above which necessitates, or course, I o'ngis carried out only in a rising airstream sothat,`

I with separate cyclone devices. Here again, the heating gas is sucked by .1the ian 8 from the .channel 1, through the 65 if; l B the wind sifters 8 and I .I are arranged at the 7o lowing stages 2 and-'i respectively; ,In-.-

manner, for instance, by change of cross section'-` second-'the1 serpentine bends of Fige 1 whichincur waste o i energy are. here rated fmateriei raus. 'through the' tubes" s Iand In Fig. 1, the heating gases are sucked, by into the conduit 2 wherein the drying lecon.-

vvtinuedat a medium temperature by means of system from a heating gas channel l, through` the same heating gas stream asbefore which has, however, meanwhile been freed fromthe pentines, I, 2 and 3, and are then conveyed in common throughthe conduit 4 to a separator 5 such as a cyclone separator, from where they are forced into theo'pen air by thev Ian 6, if necessary, through a dust separator. vThe material to'be'dried is fed into the .upward portion Loi' the flrst drying serpentine by means 'of asuitable feeding device I'l and passes through .the

tubes I, I andI" forming the serpentine. An air sitter, 8 is arranged at the lowest point of this serpentine', i. e., between the pipes I and I". In this air sitter the larger particles which are still wet are separated" out .in well known.

In the sifter 8, the large material is separated and fed into the conduit 3 wherein the drying process is nisled at a low temperature by the heating gases vwhichw have beenfreed from the medium material in the A'cyclone device 5b. 'I 'l'ie 2 gases now convey the large `particles -to the cyclone deviceI 5c, wherefrom they reach the dust separator and fan 6. The-fractions, separatedout, like in Fig; 3, in separate cyclone devices I6', I8", can either be removed separatelyor ,re-united by means of a conveyer screw vwhich collects and mixes the material.

If the parts are suitably arranged, the dryin deviceoccupies ve'ryflittle room so that all con- -30 duits can have one common insulation. Also, the wind sitters caribe combined in onecasing with separating walls. The pipes I, 2, and 3 may have diierent diameters corresponding to- "the expected distribution oil therdrying output. 'I'he speed of theheating gases` in the individual pipe branches can be controlled by throttle v alves i5, such as shown in Figs. 1 to 3. The wind sitters 8 and II may be constructed in any and direction, andthen fall`through a shrt pipe 9 and over a further feeding de'vie such as a n ner particles through the pipe I..

The remaining material then passes through the pipes 2, 2' and 2 another air siiter II "is interposed betweerri.r and 2" which4 separates the largest particles and feeds them through are carried of! through the lpipe 2".-

In cases` where the nature ofv the material allows of moderate crushing, the ieedingmeans III and I3 can be replaced by crushing devices; with a view to..accelerating the drying Process" we cm3.; by enlarging thefsurtaceoi thematerial. d 1. Drying apparatus comprising two drying 45 'Ihe heatinggas temperature in the individual conduits; means for causing a current of drying gases through' each of said conduits; means for introducingcomminuted. material into one of said conduits at the beginning of the. eirectiveI current'therein; separating means atthe dis-'(50J charge end of said one conduitflrranged to sep-'1 Y areV repla'ceilA arate out and remove'from`-urther ,drying in;- air sitters@ iluence the smaller"partic1es`which have reached a' predetermined degree of dryness; and means for collecting-fand .delivering, the larger fsepa- v 5,6 ratedlwetter particles vto ithejother conduit. A

2. apparatus comprising a'plurality of Vdrying conduits; means for causing Lcurrent f drying through'y eaclr or said` conduits; i, means for introducing comminuted material into theiiirst 'of i said series oi.' conduitsv at the beginof the effective current therein; separating means at the Adischarge en'd yof each oi said .cgnduits except the last ,of the'series arranged to separate out-and remove from further drying 5 inuence the smaller particles-"which have.l reached a predetermined degree 6I driimess;L and means or collecting the separated wetter particies from each conduit except thelast and .de-y livering them same to the 'next' conduit of Lthe 70 series.4 "fyww, 3. j apparatus comprising afseries or dryingjconduitsy means for introducing com- Aing faces for the direction of. v

stream andwith: tunnels for the escapinggas, or simply as widened parts in thejpipes;

circular sets of adjustable slots I4 or the like through which cold air; or the waste gasesire\- In Fig. 2,l theserpenti'ne' vpipes er connectingjtubes 9.anjd I2.4 '1'his\arrange ment Vhas 'a double advantage; `rst, the drying ff o to the relative velocity between the gases and t e material. the drying is accelerated, and f with. Fig. 34 shows an example -o1' an arrangement pipe' branches I,' Zand ds ofthepipe branches I and 2, and the sepa.-

stead, Nhowever, of one common cyclone device; three separate cyclone " devices 5a, 5b,` 51care arranged behind the wind enters a; and the conduit 3 respectivelypto separate the iine,'me dium and Llarge particles. These. are 'removed :tine dried particles in the cyclone separator 5a. 15

sa, sb, dndsedna ejected by the een anims is, Y

suitable way, for instance, as boxes with reflect- .40

minute`d"-'-material of diierently sized pax-tides into the iirst conduit ohthe series' adjat m inlet, means for supplying a continuous current of drying gases to the inlet of each drying conduit for conveying the material therethrough and drying it while being conveyed, means at the outlet of each conduit except the last for separating out and discharging all particles above a predetermined size, each of said separating means being progressively capable 'of passing larger particles of the material, means

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