US2677899A

US2677899A - Jacketed steam drier

Info

Publication number: US2677899A
Application number: US226698A
Authority: US
Inventors: Paul E Ohlson; Edward A Hodge
Original assignee: Pusey & Jones Corp
Current assignee: Pusey & Jones Corp
Priority date: 1951-05-16
Filing date: 1951-05-16
Publication date: 1954-05-11
Anticipated expiration: 1971-05-11
Also published as: USRE24024E; FR1099656A; GB755270A

Description

P. E. oHLsoN ET Al. 2,677,899 JACKETED STEAM DRIER 2 Shetsr-Sheet l May 1l, 1.954

Filed May 16, 1951 May 11, 1954 P. E. oHLsoN ET AL JACKETED STEAM DRIER 2 sheets-sheet 2 Filed May 16, 1951 4. 1. I. .n i a IN VEN TOR5 Pda] E.' san EJWrJoa/ge BYf ATTORNEYS Patented May 11, 1954 tn.; Dei., assign patetica Delaware Wilmiesien Applicationrmay is, 1951, ...serrati ivo. assises .11 CL: .34a-:13.9.:

The present invention relates to,steam ja0kelind. driers `of the type used :in paper `mills, food processing plants, `industrial'A chemicalinanuf,acturing plants, andthe lik Driersofthe 4kind. which are improved by the present nventionare to be .distinguished from heavy cast v iran ldriers in..which the entire interiors. of the cylindrical' drurnsrare filled ,with steam, since jacketeddriers conventionally .have .their interiors open', tu .the atmosphere and comprise a pairof concentric, steel cylinders, providing aclosed space. theref between, into .which relatively high.4 pressure steam is delivered,.and from whichlcondensateis removed.Y

A primaryobject ofthe present inventionis to provide. means. for increasing the. rate of heat transfer .from the exterior surface .of a .steel jacketed 'drierto the material being dried. .i

"I'o this-end,-..an important objeotofnthe invente tion is to increase `the ,..velocityibsteam,.flott through the jacket space inthedrien Such in? creased .velocityl of steam now. exerts. a scouring" action upon the innerlsurface oi.. the outer cylin-n der.. and effectively. .prevents the, formatiomota lrn or layer of condensate .n...said ..-surface,. which,. in conventional practice. acts as-ansin'f. sulating layer and reduces therate o.heat.trans. fer romthev steam .tothe cylinder. i Thesconrng action', effected by. the improvements of thefpres;

ent inventioiralso. effectively removesairand: o

non-.condensable-.gasesfrom: .the .jacket space',A thereby.` 'further rate;

lt has been .standard .practice .in the: .j acketed" drier artto! space the. inner. and `outer`fcylindrs substantially two inches.' apart, lregardles's" of the diameter of. the drier, which lniay vary .from ,36: inches to 144" inches; Thisrelativelyilarge.jacket space results. in numerousnisadvantages Avvhiclfi have' not been appreciated or understood 'inthe prior art. The velocity of steam llovv iLthe jacket .space isinsuicient -to eiiect the desifed scouring actiorard theremovalof` cndesatef air; and nonwon'densable gases. 'A'ccodingljeat low. speed, the condensate puddles badlynear the bottom v`ofl the. drier, thereby interfering with? heat .transfer'and increasingthe power required torotate the drier. ta high!' s'peed,` thecondensaterims'lin a film around the entire inner surface ofthe: outer cylinder and intereeSPWth heatv transfer. Air

venting. and low" rate' of stean'lw.-

No attempt inhthe past liasbeenmadeto conimproving. the (heat transfer..

h and nqn-condensable gases:4 remain in the jacket space because of-v such a manner as to. effectmaximum. heat transA fer... No` ,means have. been providedto eiect even and uniform distribution `of steamflojy over. theentire inner surfaceof the. drier.

The. purpose of the present invention .is to overs, come all of. .the foregoing defects; to ,produce a suiiciently .high velocity of steamow. to scour air, water, and .incondensablegases; to effect even `and /uniform distribution. `of A`steaniafiow4 withinA the-jacket space;A and to control thequality oi?` theisteam Within the jacket to effeCtmaXi.- mum.. heat transfer.

As. a, ,resultof shopexperimentation and theoretical calculationsit has been determined that a steamifiow. .velocityupon. .theintroductiong of the steam into .the jacket. space, .of feetper minute. and a discharge. vvelocity vof-v lovvvi,qualityy steam and condensate .of` 7 feet per minute 4or more is necessary. toproduce the desired scouring action and tto. `eiiectvproper. removal ofcondensate, air,. and non-condensable gases.

The objects.of; the .present invention .are,..aci, complished',., as explained, .in connection. .with .the illustrativev embodiments described .be1ow,.. by .decreasing the radial dimension .of the steam' space between the `outer. and .inner cylinders, .to sub.-U stantially 34,' of an inch, more or` less, depending uponlthe diameter. fof. the drier by. dividing: fthe jacket space intoa .pluralityof longitudinally extending compartments steam atfhighl velocity. to. the compartment. atA la plurality.. of. .points 4through openings of accurately .determined areas.; and by providing means foron .1315@ 3 0f Figure. 1.5

-Figure' 4 is an'V enlarged fragmentary section stearddelivey and c'nder'isatev rnovalninfstriif mentalities; and

Figure 5is' a` fragmentary axialvsection` on an enlarged sca-le' With'jcejtainpartls broken avvay.J

A parof' hollow journals' l (i andi I, v`intercnby .delivering theV leading ends ofthe y removing 10W quality steam and .condensate adjacent the trailing ends of. the

nected by a central shaft I2 may be supported in conventional manner by suitable bearings, represented diagrammatically at I3 and I4. The journals carry end plates or heads I5 and I6, which may have openings I1 therein so that the interior of the drier is open to atmosphere. Secured to the outer margins of the two heads are a pair of inner and outer steel cylinders I8 and IS, disposed in closely spaced concentric relation and spaced apart by end rings and 2I, to which they are welded, to provide a closed jacket space 22.

As indicated in Figure 5,the heads may be reinforced by radial webs 23, extending from the inner cylinder I8 to a supporting ring 24, secured to the journal II in any appropriate manner, as by bolts extending through a flange 26 integral with or mounted upon the journal.

The space 22 between the inner and outer cylinders is divided into a plurality of longitudinally extending compartments, by a plurality of stainless, spring steel vanes 3u, having their inner portions 3| welded to the outer surface of the inner cylinder I8 and their outer edge portions 32 bearing against the inner surface of the outer cylinder I9 with spring pressure. As indicated by the arrows in Figures 2 and 4, the Vanes are Apitched forwardly and outwardly in the direction of rotation of the drier. Moreover, they extend longitudinally in angular relation to axial sections of the cylinder so that condensate engaged by their leading faces tends to iiow, under the influence of inertia, gravity, and centrifugal force, toward their trailing ends.

The inner cylinder I8 is provided with a plurality of rows of apertures 33, one row being disposed adjacent the leading faces of each of the vanes 30, at the trailing end of each compartment in the space 22. These apertures provide means for the discharge of condensate, lowquality steam, air, and non-condensable gases from the several compartments; and such now is facilitated by the scooping action of the varies.

The inner cylinder I8 is also provided with a plurality of rows of openings 35, disposed in parallel relation to the apertures 33 with one row positioned behind each vane and near the leading end of each compartment in the space 22. As hereinafter explained, steam fiows through these openings into the several compartments. In order to prevent the direct impingement of the steam upon the inner surface of the outer cylinder, at points in alignment with the openings, and to effect a uniform dispersal of the steam, the openings 35 are fitted with nipples 36, having closed, circular outer ends, constituting bales 31 and laterally directed, slotted openings 38 and 39, so that the steam is directed laterally, as distinguished from radially, into the jacket space 22.

Upon the inner surface of the inner cylinder, in alignment with each row of apertures .'23, there is an outwardly facing trough 40, consisting of a U-shaped sheet metal strip welded to the cylinder I8 and disposed longitudinally in angular relation to axial sections of the drier, in the same manner as the vanes and the rows of apertures. Accordingly, condensate flowing inwardly through the apertures 33 into the troughs tends to flow longitudinally toward the trailing ends of the troughs or, in other words, toward the left in Figure 1.

At the latter end, each trough is connected to a radial pipe 4I having its inner end connected toan axial pipe 42, extending through the jour- 4 nal II and bearing I4, to a suitable condensat collecting trap and return steam line, not shown.

Adjacent each trough 40 is a second trough 45, which may consist of an L-section sheet metal strip, welded to the U-section strip 40 and to the inner surface of the inner drum I8, as illustrated in Figure 4. Each trough 45 encloses the associated row of openings 35 and nipples 36. At the right hand or leading end, each trough 45 is in communication with a radial steam delivery pipe 46, extending into the interior 41 of the right hand journal I0, to which is connected a steam supply pipe 48.

In many cases, particularly where the length of the drier exceeds the circumferential dimension, it'has been found highly advantageous to divide the space 22 into a plurality of separate compartments' by positioning circumferential rings in the jacket space. For instance, the entire space may be divided into four compartments or chambers, longitudinally of the drum and each of these compartments again divided by the fins or vanes 30. One circumferentially extending ring may be positioned midway between the end rings 20 and 2|, and two other circumferential rings midway between the first mentioned one and the end rings. Such an arrangement Vprevents a direct longitudinal flow from the steam inlets to the outlets; results in a more uniform, circumferential flow of steam 1n the several compartments, and provides an improved and more thorough scouring action for the removal of air and non-condensable gases. This arrangement has been found to be of importance and to produce highly advantageous results in elongated driers, such as those having a 60-inch diameter and a 23S-inch length.

In the operation of the apparatus of the present invention, high quality steam at relatively high pressure, in the neighborhood of 125 pounds per square inch is delivered through pipes 48 and 46 to the interior of the longitudinally extending distributing troughs 45, from which it flows through the nipples 36 into the several compartments, into which the space 22 is divided by the vanes 30. The high quality steam is distributed uniformly and evenly throughout the compartments vand gives up its latent heat to the outer cylinder I9, which results in a reduction in the quality of the steam, considerable condensation on the inner surface of the outer drum, and a high velocity steam flow. The low quality steam flows from the space 22, inwardly through apertures 33 into the trough 40, with a relatively high velocity flow, which results in a scouring action within the space 22, tending to drive condensate, air, and non-condensable gases toward the trailing end of each compartment. The vanes 30 exert a scooping action on the condensate and force it to flow through the apertures 33 into the trough 40.

Because of the angular disposition of the troughs 40, from end to end, the condensate, through the influence of centrifugal force, inertia, and gravity is caused to flow longitudinally in each trough toward the trailing end thereof, where the condensate is received by the radial pipes 46 for flow through the interior of the journal II, and for discharge through the pipe 42.

In order that the quality of the steam may be reduced from substantially when it is introduced, to substantially 10%, when it is discharged through the apertures 33, to produce a. high velocity flow and to give up a major portion of its latent heat, it has been found that.

Y:minedi direction,

the. total crossiseotional .area of .ftheaportures Should equal; approximately 0f` thctotal crossesectional area of f. thel steam space 22. Moreover, in -order that thev yeloctyof fthe .flow ofsteam .in the spaceibe high, the .radial ,dimension thereof shouldfbe small.-

Experiments and theoretical. Calculations have demonstrated that a drierirl accordance, with. .the present inventio c, using steam, pressures. of be.- twccn-125 and 18,0 poundsfper. Squareinohre.- Sultsin an increase-of heat transferof between 2.2%y and 2.9%.v 215..;...00Innared withnriorstoam iaoketed. driers. operatingy .et similarpressure. but not provided with the improvements .of Ythe present invention..

Itfmust be.. understoodthat theinvention isfnpt limited` to Athe.details oitconstruction shown in tlicaccompanyine.drawingsanddescribed above, as Vmany,modifications. will occur .to those skilled in theartifrom a consideration of this ,disclosura f Theinvention includes allrmodiiications ycomme within thefscone of the. appended claims and-:their equivalents.

We claim:

1- A.; drier comprising ari-air of concentric. closely spaced, inner and outer` cylinders ,mountdffor rotation in a predetermined direotionarid hayi-ngtheinteriorof the-,inner cylinder open to theatmosphere, eas-tightisealins moans closing the ends, of thespace between the cylinders, a

plurality. of vanosfcxtendine lorlsitudiiially from end to end ;of,. the-,cylinders .and dividing .the space therebetween into a. plurality ofi` longitudinal compartments, the innercylinder having a row of openings .behind ,each oil-said vanesand a row of-aprerturesaheadf each vane, means for de liveringsteam througheach row-.off openings to said compartments adjacent the. lea-ding en-ds thereof and trough meansv cabried bythe inner Sur-face. of theinner-cylinder rtepisttiine'v with the rows of aperturesfor collecting condensate and low quality steam iiowing through the apertures in the inner.. cylinder,

2. A drier comprisingy a. pair. oi.,- concentric, closely spaced inne'r and`outer steel cylinders of substantially equal wall'thickness mountedv for rotation about their common axis` in adpredeter gas-tight sealing means closing the ends of the space between the cylind`ers,`a

plurality offvanes extending longitudinally lfrom y end to end ofthe cylinders; dividing the space therebetween, into, al pluralityof.` longitudinally extending compartments, said vanes being. for.- wardlyandoutwardly pitched from thelinner to the outer cylinder, the`inner cylinder having a row of" openings behindv each of said vanes and a row of aperturesaheadof each. vane, means for delivering, bien quality irish pressure Steam throueneaonrow. of openings tothesaid Space and trough means carried by the inner surface of the inner cylinder registering with the rows of apertures for collecting condensate and low quality steam owing from said space through said apertures.,

3. A drier comprising a pair of concentric, closely spaced inner and outer steel cylinders of substantially equal wall thickness mounted for rotation about their common axis in a predetermined direction, gas-tight sealing means closing the ends of the space between the cylinders, a plurality of vanes extending longitudinally from end to end of the cylinders, dividing the space therebetween into a plurality of longitudinally extending compartments, said vanes being secured to the outer surface of the inner cylinder ends thereof, the

and: projecting outwardly.. in. forwardly. pitched relation.v into Contact. with `the inner. surfacerof theouter .,cylinder, means jfor. delivering steam .t0 said vcompartments vbehindeach oifsaidI ,-vanes, said innercylinder haring a ,rowofapertures .adjacent the .leading face ofeach vane. for the in,- ward Aiiow .of :low` quaIitysteam yand condensate. and a plurality of .trolls S 011 .the ,inner` surfa e of. the inner. cylinder registering with,` said :rows of. apertures` for collecting the inwardlynowing condensate and flow lquality steam.

4. A. drier. comprising. av pair` of concentric, closely spaced inner and outerstcel, cylindersof substantially. equal wall-,thickness mounted for rotation. abouttheir. common. ,axis` in a .predetcr mineddirection, gaseti htsealingmeans closing `the ,ends of the.. pacebetween ,the cylinders,v a plurality .of vanes extending longitudinally. vrfrom end.. to` end of the `vcylinders dividing the, space therebetween. into, a plurality.. ofv longitudinally extending compartments, said vanes bengse.- cured`to the outer ,surface of .the inner cylinder and projecting .outwardly in forwardly pitched re.- lationinto contact with the innersurface of,-the outer 'cylinderl and; disposed longitudinally, in angular .relationlto axial sections ,ofv Vthe cylinders, whereby longitudinal .flow is imparted ,fto,conden;,n sate engaging the vanes,y means. for. delivering steam to the compartmentsadjacent. the. leading inner` cylinder having a row .of .aperturesadjacentthe trailing .end .or each compartment opposite; the. .leading ,face of the asso,- elated.l vane for the inward now.. of condensate, andanoutwardly facingtrough secured to, the

" inner surface ofthe inner cylinder, enclosing each .row of apertures `tcl-.receive said-condensate.

5.. A drierl comprising a pair of concentric, closely spacedinner. vand outer lsteel cylinders of substantially equal. wall thickness, mounted.. for

their commonl axis, in. a. predetcimined direction, gas-tight. sealing meansolos.- ing theends Iofithespace betweenthe cylinders, a plurality of vanes extending longitudinally. from end to. end of'. the cylinders .dividing the. space therebetween.. intoa pluralityof longitudinally extending. compartments, said vanes being. se.- lc uredto theouter surface of the. inner. cylinder ksate engaging the vanes, means for delivering steamto the compartments adjacent theleading ends thereof; the inner cylinder` having a. row. of apertures adjacent the trailing endl of each compartment opposite.` the leading face of the asso:- ciated vane for the inward flow of condensate, and an O utwardly facing trough secured to. the innersurface ofthe inner cylinder,

the cylinders, whereby longitudinal flow is imparted to the concondensate received Papertures of reduced total cross-sectional area as compared to said openings extending through the inner cylinder adjacent the trailing end of each compartment, a plurality of pairs of adjacent troughs extending longitudinally along the inner surface of the inner cylinder with one trough of each pair embracing the openings of one compartment and the adjacent trough of each pair embracing the apertures of the compartment ahead thereof in the direction of rotation of the drier, means for delivering steam to the first trough and means for removing condensate from the second trough.

'7. A drier in accordance with claim 6 in which the means for dividing the space between the cylinders into said compartments comprises a plurality of longitudinally extending varies se- -cured to the outer surface of the inner cylinder, vprojecting outwardly in forwardly pitched relation and contacting the inner surface of the outer cylinder.

8. A drier in accordance with claim 7 charac- `terized in that the vanes and the troughs are disposed in angular relation to axial sections of the cylinder, whereby longitudinal flow is imparted to condensate engaging the vanes and to in the second trough, said drier being further characterized by the inclusion of means for removing condensate from the trailing end of the second trough of each pair.

9. In a jacketed drier of the type having an open interior and concentric inner and outer cylinders dening a closed annular' steam space therebetween, a central shaft, journal means therefor, means for delivering steam to said space through one journal and means for removing condensate through the other journal, the improvement in the steam delivery and condensate removal means which comprises a plurality of forwardly and outwardly pitched vanes, secured to the outer surface of the inner cylinder making contact with the outer cylinder and dividing said space into a plurality of longitudinal compartments, a row of openings extending through the inner cylinder behind each vane, a row of apertures extending through the inner cylinder adjacent the leading face of each vane, means for delivering steam to all of the openings, a trough on the inner surface of the inner cylinder enclosing each row of apertures, and means connecting each trough to the condensate removal means extending through said other journal.

l0. In a jacketed drier of the type having an open interior and concentric inner and outer cylinders dening a closed annular steam space therebetween, a central shaft, journal means therefor, means for delivering steam to said space through one journal and means for removing condensate through the other journal, the improvement in the steam delivery and condensate removal means which comprises a plurality of forwardly and outwardly pitched varies, secured to the outer surface of the inner cylinder making contact with the outer cylinder and dividing said space into a plurality of longitudinal compartments, a row of openings extending through the inner cylinder behind each vane, a row of apertures extending through the inner cylinder adjacent the leading face of each vane, a trough on the inner surface of the inner cylinder enclosing each row of openings, and means connecting each trough to the means for delivering steam through the rst mentioned journal.

11. In a jacketed drier of the type having an open interior and concentric inner and outer cylinders defining a closed annular steam space therebetween, a central shaft, journal means therefor, means for delivering steam lto said space through one journal and means for removing condensate through the other journal, the improvement in the steam delivery and condensate removal means which comprises a plurality of forwardly and outwardly pitched vanes, secured to the outer surface of the inner cylinder making contact with the outer cylinder and dividing said space into a plurality of longitudinal compartments, a row of openings extending through the inner cylinder behind each vane, a row of apertures extending through the inner cylinder adjacent the leading face of each vane, a trough on the inner surface of the inner cylinder enclosing each row of openings, means connecting each trough to the means for delivering steam through the first mentioned journal, a second trough positioned adjacent each of the rst mentioned troughs on the inner surface of the cylinder enclosing each row of apertures and means connecting each of the second mentioned troughs to the condensate removal means extending through the second journal.

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES Trade Journal, Industrial Development January 20, 1949, pages 16 and 17.

Paper Section,