US2576036A - Yankee drier - Google Patents

Description

Nov. 20, 1 1 H. M. OSTERTAG ET AL YANKEE DRIER Original Fi1ed Sept. 21, 1944 3 SheetsSheet l H. M. OSTERTAG ET AL Nov. 20, 1951 YANKEE DRIER 3 Sheecs-Sheet 2 Original Filed Sept. 21, 1944 Nov. 20, 1 1 H. M. OSTERTAG ET AL YANKEE DRIER 3 Sheets-Sheet 3 Original Filed Sept. 21, 1944 Patented Nov. 20, 1951 YANKEE DRIER Harry M. Ostertag, Drexel Bill, and John B. Masshard, Chester, Pa., assignors to Scott Paper Company, Chester, Pa., a corporation ci Pennsylvania Original application September 21, 1944, Serial No. 555,146. Divided and this application November 30, 1945, Serial No. 631,886

11 Claims. 1

. A primary object of this invention is to provide a Yankee drier capable of operating safely at steam pressures materially in excess of these heretofore found practicable.

To this prmary end the invention contemplates a novel structural design calculated to eliminate the critical points of failure and to avoid in large part the hazards existing in driers of conventional form and responsible for the inability of those driers to operate With reasonable safety at higher steam pressures.

Another and more specific object of the invention is to provide improved and readily accessible meansfor distribution of steam within the drier and for removal of condensate.

The invention resides further in certain structural details and devises hereinafter described and illustrated in the attached drawings where- Fig. 1 is a longitudinal sectional view of a drier made in accordance With the invention, said section being taken on the line ll of Fig. 2;

Fig. 2 is a sectional view on the line 22, Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view illustrating certain details of structure;-

Fig. 4 is a view in perspective of one of the elements of the structure;

Fig. 5 is a sectional view on the line 55, Fig. 1, and

Fig. 6 is a line diagram;illustrating graphically the inter-relation of certain elements of the structure, as hereinafter more fully set forth.

The conventional Yankee drier consists of a cylindrioal cast iron shell mounted on journals through the medium of dished heads, said shell and heads forming together a cylindrioal drum. Steam is introduced through the journals to the interior of the cylinder subjecting the entire internal area to full steam pressure. Condensate is removed by scoops which operate either as dippers or, in the blow-through type of removal, as intake nozzles.

This type of construction possesses certain un desirable characteristics. (1) The pressure acting on the heads produces stresses and deflections of the heads which are transmitted through the rim bolts or studs to the shell; (2) Accumu lation of condensate may occur in the large insmall number of relatively spaced scoops tends to result in the creation of local hot spots in the shell where the exhaust steam sweeps the drier surface, With resultant uneven drying of the paper; (5) There are points of critical weakness. While some failures of Yankee driers have occurred in the head, the majority are in the outer shell, and these latter failures almost invariably occur at the edges of the shell and usuallyat a rim boit or stud.

All of the foregoing factors have contributed to a necessity for employing relatively low steam pressures. As previously set forth, the present invention provides a drier structure which, by eliminating the aforedescribed hazards and areas of critical weakness, permits the safe use of materially higher steam pressures within the drier than have heretofore been found practical. The invention also corrects in substantial degree the several faults above enumerated of the prior conventional type of drier.

With reference to the drawings, the improved drier consists of an outer cylindrioal shell I of cast iron, which metal provides the best creping surface, and an inner shell 2 which is made of steel so as to meet the standard specifications for unfired pressure vessels. These shells are spaced apart through the medium of hollow rims 3 and 4, one at each end, which serve also as annular steam chambers. The rims and shells are concentrically mounted, through the medium of spokes 5, upon a central axle 6, said axle comprising journal elements 1 and 8, from which the said spokes radiate, and an intermediate hollow shait 9 which extends between and unites the said journals. Steam is introduced through the journal 1 by way of a pipe 1 l which is secured to the outer end of the journal through the medium of a fiange [2 and screws l3, as hereinafter more specifically described. From the journal member l, steam passes through a port I4 to the hollow shaft 9, thence through the spokes 5 at both ends of the structure to the rims 3 and 4, and from these hollow rims through apertures l5 and l6 to the space I 1 between the shells I and 2. As shown in Fig. 2, the apertures l5 are uniformly spaced in annular series around the inner side of the rim 3, and the apertures 16 are correspondingly arranged in the rim 4.

To remove condensate and reduce the thickness of water film on the shell, exhaust steam is evacuated frcm the chamber Il by way of a plurality of nozzles l8. These nozzles project from pipes l9, a plurality of which extend longitudinally in the interior of the steam chamber H and are connected at one end through pipes 21 and 22 and ports 20 With the interior of the journal 8. Exhaust steam discharges through the journal and through a pipe 23 secured within the latter. The nozzles I3 have their outer ends l8by arranged in close proximity to the inner surface of the outer shel1 l 50 as to restrict the openings through which the steam must pass in entering the nozzles, and preferably the outer ends of the nozzles are formed, as shown in Fig. 4;, with lugs [30L which preclude approach of the ends of the nozzle to the inner surface ofthe s'hell'to an extent reducing said openings beyond a predeter mined minimum. By reason citheserestfictions;

the steam enters the nozzles at high velocity and sweeps the water from area2s of the inner surface of the outer shell adjacent to the nozzle ;tips. Since the exhaust steam can enter the n'ozales from all directions approximately in the plane of the drier surface the aforesaid sweeping action is effective over a circular area surrounding each nozzle. The nozzles are closely spaced so that the combined area thus sweptmay in aggregate cover substantiaily the entire inner surface of the shell. The exhaustingsteam carries with it the condensate which is Similarly exhausted through the journal 3 and pipe 23 as described.

Opposite the outer end of each *of the spokes 5 is a tie rod.'24. 'These rods are secured under of the boss 4l. Suitable packing 44 is inserted between the said outer end of the boss 4l and the bottom of the.recess in the cap 36' so as to seal the opening 43. A corresponding connection, sec

Fig. 1, is estabiished between the pipe l9 and the rim 3 with the exception that in this case the L fitting 39 is replaced by a terminal cap 45 which fits into the packing recess on the inner side of the cap 33 and into which the screw 42 is threaded as described. By tightening the screws 42 at the opposite ends of the pipe I!) the latter is placed under tension between the rims 3 and 4.

In the present instance the fittings 45 are pro vided .Withprojecting bosses 45 which can be utilized in applying or rem0ving the terminal cap .to the pipe [9.

Since the pressure component carried by the tie rods'and pipes is reiatively small, it may be desirable in some instances to eliminate the tie rods and to remove the tensile stress from the pipes. In such event the pressure forces may be carried by one of the shells and the rigidity cf the head structure.

tension, by means of nuts 25 and 26 at the re g): spective ends thereof, in the outer walls of the and 4, which apertures correspond to the aper- 7 opening around the pipe "2|. The rim 3 is simituresl5 and 15 previously described. These rods, in conjunction with the pipes l9, act under tension to carry the relatively small component of the pressure of the steam in the chamber I! The outer which tends topseparate the rims. shell 1 is stifened by inwardly projectng intethrough outwardly extending Ilanges 32 on the said rims and through :the fianges 29 and are -threaded into a segmentedretaining ring 33, the

segments of said ring seating against the inner faces of the fianges 29 as best illustrated in Fig. 3.

The manner in whichthe nozzle pipes or'manifolds l.9 may be secured under tension in the rims 3 and 4., isbest shownin Fig. 3. The outer walls .of the rims are provided with a series of uniformly spaced elongated apertures 34which are located respectivciy approximately mid-way between the points wherethespokes join the rim. The location and arrangement of these apertures 34 is well illustrated in Fig. 2. The apertures are dimensioned and positioned *so that the respective pipes i'3 With their n0zzles may *be inserted therethrough into the chamber H, and for this purpose corresponding apertures 35 are provided in the inner Walls of :the said rims. The apertures 34 are norma;ily closed by cover cle- As shown most clearly in Fig. 3 the outer ends of the pipes 2l are threaded into the respective fittings 39, and the inner peripherai wall of the rim 4 is provided with a series -of apertures for passage of the said pipes 2i into the interior of the rim. Each of these opening's;which are designated in Figure 3 by the referencenumeral 41, is provided with a stufing box indicated generally by the reference numeral 48 which seais the larly provided with series of openings corresponding to the opehings 41 and to the ports 2!) which receive the pipes 22, said openings and ports being desighated by the same reference numerals, but in the rim 3 these openings are normally closed by means of suitable caps 49 and screwed to the rim.

In accordance with the present invention, the inner shell 2 is mounted on the rims 3 and 4 through the mediu'm of fioating joints designated generally by the reference numeral 51. One part of the joint is formed by a fiangelike annular projection 52 having its outer face 35 inclined to the axis of the roll. The other part ofthe joint is'formed by an inturned flarige 54 at*the end of the inner shell 2, the inner faces 55 of the fianges 54 being inclined in conormity With the face 53 of the flange 52 and seating upon the latter. The joint between the faces 53 and 55 is sealedby a flexible sealing ring 56 which is secured at the inner end of the joint with its inner and outer peripheral edges secured by screws 51 and 58 to the flanges 52 and 54 respectively.

This sealbeing flexible is a character to afiord limited relative movement between the rims and monts 33 which are secured against the outer Walls -of the rims .by screws .31, and each of the caps 3(ihas on its inner face a ;projecting annular wal1 '38 which forms a .recess on the inside of the cap functioning for a purpose hercinafter -described. 1Each of the pipes 19 has at the inner shell. 7

The locus of a point on the end of the inner she1l moving as a result -of thermal expansion is a line theyslope of which is determined bythe relation of'the diameter of the shell to its length. Byproper determination of this locus, it *is pos' sible to design the joint 51 so that expansion of the shell and rims wili not open the joint i. e.

.. so that the surfaces 53 and 55 will remain in one end an L fitting 39 which is attached by .threads to the pipe outer end a .projecting boss 4l which fits into the aforesaid .recess embraced bythewafll 33 on the 19 and which has at its associated cap 36 as previously set fort-h. A

, screw 42 passes through an aperture 43 in the cap 35 and through the aforesaid recess and is threaded .into a tapped hole in the outer face rate of heating and resultant expansion; and that the entire structure with the exception of the outer shell is subjected to substantiafly full steam pressure and temperature. The outer shell, while subjected to full steam pressure will be cooled by the application of the wet web.

The axial expansion of the steei inner shell may be expressed as follows:

a=L C(T2-T) where e:.=axial expansion L=length of shell C=coeificient of expansion for stee1 T=room temperature, and

Tz=operating temperature. The radial expansion of the shell will be:

Cr=RXC(TQT) where R=radius of the shell.

It may be assumed that one-hait of the axial expansion will occur at each end of the shell. The

said slope will, therefore, be the ratio of the expansion or where ais the angle of the locus, neglecting radial deflection due to pressure, and D is the mean diameter of the shell. The equation is iilustrated geometrically in Fig. 6 wherein alpha corresponds to the angle formed between the surfaces 53, 55

(as shown in Fig. 3) and the rotary axis of the drier.

The central journal 1, the hollow shaft 9, the

spokes 5, and the rims 3 and 4 may be practically considered as a unitary structure since ail are straining the expansion and with consequent The flexible seal 56 will avoidance of stresses. prevent the escape of any small quantity of steam which might find its way through the joint.

With further reference to the pipes I9, it will be noted that by reason of the fact that all connections are external or readily accessible, the

pipes may be installed and as readily rcmoved without affecting the rest of the structure. In the assembly operation, the nozzles, pipe, terminal fitting 45, and L 39 may be assembled and then inserted between the shell through one cf the cpenings 34. This sub-assembly after insertion is rotated through an angle 01 90 to the final position and the packing and coverplates installed and secured. The pipe 2| is then inserted through the aperture 41 and threaded into the L after which the packing is inserted and the gland drawn tight. Finally the S pipe 22 is installed between the nipple and the hub casting and is bolted fast to complete the connection. Dismantling may be quickly accomplished by reversing this procedure and may be accomplished without waiting for the drier to cool.

The aforedescribed' drier structure has certain advantageous features which may be summarized as follows:

1. Distortion at the ends of the heated outer shell is resisted by a stiffening ring or flange through which the shell is fastened to a heavy rim section in a manner approaching an integral structure.

2. The bolt arrangement is such that the stresses therein are limited substantially to those 01 drawing up, all the load being carried directly by the rim section.

3. Forces due to weight or external load are transmitted to the journals through the spokes radially in a plane perpendicular to the axis and close to the bearing support, thereby reducing bending moments to a minimum. 4 i. Both end pressure and water load are re duced to a practical minimum by employing a double shell. This reduces stress and deflection in the heads and shell and also reduces the hazard of large volumes of escaping steam should failure occur.

5. Tie rods and the pipes 19 may be used to carry end pressure forces rather than utilizing the outershell and heads thereby further reducing stresses and defiections in the heads and shell.

6. Provision has been made to equalize expansion where possible and to provide an expanding joint between dissimilar metals whereby variatiens in expansion will not produce undue stresses.

7. Steam is introduced between the shells from a large number of apertures to provide uniform distribution and does not impinge on the outer shell, which avoids creation of hot spots.

8. The condensate-removal nozzles are designed and located to produce exhaust steam velocities suficient to sweep a circular area about each nozzle. A number of nozzles are provided so that the area swept by each may overlap the area swept by an adjoining nozzle thus sweeping substantielly the entire shell surface to reduce the water film thickness and increase heat transfer.

9. The condensate removal system has been designed for accessibility and easy removal to reduce operating delays when maintenance is required.

Reference is hereby made to U. S. application Serial No. 555,146 filed Sept. 21, 1944 now Patent No. 2,563,692 of which this application is a division.

We claim:

1. A drier of the rotary cylinder type comprising a cylindrical shell forming the peripheral surface of the drier, means for admitting pressursteam to the interior of the shell, and exhaust conduit means for said steam including a mul tiplCity of exhaust ports distributed over substantially the entire inner surface of said shell, said ports being directd radially toward and in immdiate proximity to the inner surface of said shell so that the steam in passing to said ports will flow at high velocity over and in contact with said surface.

2. A drier, in accordance with claim 1 wherein the said discharee ports are defined by open ended nozzles which project radially from said conduit means into close proximity to the inner surface of said shell.

3. A drier of the rotary cylinder type comprising a cylindrical shell forming the peripheral surface of the drier, end walls for said shell, means for admitting steam to the interior of said shell, a plurality of pipes mounted in said shell and having each a plurality of nozzles, said nozzle and pipes being distributed in substantiallly uni- Iormp;terri thitoughout the interiorof said s11e11 and ,eonstitutingzmeans forex haust f steam and 'aondensate from the latter, and said -nozz1es pro- ,iee1ng toward'the inner surface of said she1l-with their intake openings directed radially toward and in 1oso'proximity to the inner surface of said sha11 whereby the steam diseharged into said opfiflings Wil1 sWeep a substantial -area.of the said inner surface around eachofthe nozzles to thereby-zeffiectively reduce the water film on said surface. 7

' inca drier of the rotary cy1inder type, 1 an enter cy1indriea1 shell, ;an -inner she11 Iadia1lY spaced from the outer .shell 50 as :to provide therebgtwen 'a steam chamber, end wal1s for said ehamberc, :means for admitting steam to said chamber; and exhaust conduit means extending into said chamber through a wall thereof and having a multiplieity o,f ports distributed throughout the chamber for discharge of steam and eondensate from the latter, said ports being diree*fied radially toward-and in immediate proximiyto the :inner surface .of :the outer she1l.

" 5, A drier aoeordance with claim 4wherein means is provided for admitting steam SII1? taneomly to :both ;ends of said chamber.

' 26. -A drier inaccordance with claim 4 wherein the,said disehargeports are defined byepen ended nozzles which project radially from said conduit meang into close proximity to the inner surface of :the outer shell. r

=r.'In a ldrier of the rotary cy1inder type, an enter pylindricalshell, an inner coaxial shel1 supporting usaid she1ls fzor rotation about ;the

.common axis, said.means including a holiow J3}I" nu1ar rimmember .at ;each endzof the sh11s oonnecting the 1atter,x-means operatively assoeiated:with-:said rims for admitting steam to said in each of said pipes,.,a -p1ura1ity of ports in the radially spa ced from the outer shell 50 as to proide"therebetween a chamber for reception et steam, means for admitting steam to said chamber,.a pluraiity ofpipes mounted in said chamber aridhaving each a pluralit of nozzles, said nozz1es and pipes :being distributed in substantially unifrmpatternthroughout the chamber and constituting means for exhaust of steam and condensate irom the latter, and said nozzles projecting toward the outer shell with their intake openjngs directed radia1ly toward and in close proxmity to the inner surface of the shell whereby the steam discharged into said openings W111 swep 'a;substantial area of the said inner surface around each of the nozz1es to thereby effectivel reduce the water 'fi1m on said surface.

8. In a drier of the rotary cylinder type, an outer cylindri al shell, an inner co-axia} shell radiallyspaced from the outer. she1l so as to provide therebetweefla steam chamber, hol1ow an nular rim members at the ends of said chamber, said rim menibers eonnecting the shlls and having ports opening to said chamber, a pair of hol- 1oxv journal elements and ho11ow spokes connecti-ng said journal e1ements with the respective rim members thereby to afiord' passage for steam to said chamber, a series of pipes each supported in said rim membersand extending -axially through said chamber, said pipes being distributed in substantial uniformity about the circumference of the hamber and *each carrying a p1urafity of -nza1es 'pmjecting -outwardly with their open fends direeted :radiauy toward and in close prox. imit to'the inner surfae oi the said outer shell, and a duct extending from each of said pipes to one or said holiow journals for disoharge -through th flatter of steam and condensate from the said Vi.d a:steam -chamber .tne eb twe n. m ans .to.r

outer side of at least one of said rim members, said ports being in alignment With said pipesand providing for insertion of the pipes and -nozzleg through the rim and into said chamber, ,means operative from,thetoutside .of said rims fer detachably secu1*ing the pipes in the rime, and .a detachab1e cover plate}forsaid ports.

10. In a drier of the rotary cylinder type, an outer c'ylindricil shell, an irlner co-axia1 s11e11 radially spaced f romvthe,outer shell so as to provide therebetween a chamber for reception ,of steam, means for admitting stam to said chamb er,;a p:1ura1ity of pipes ;mounted in said chamber; said,pipes having open, ended nozz1es proieeting into*-c1oseproximity to and with the terminal ports confronting the inner surface o f said outer shell, said nozz1es and pipes constituting mean s fgr exhaust of steam,and pondensate from the chamber, and means for :positive1y 1imiting the s paoing of the nozzle tips from the said inner Surface to a predgtermined minimum.

11 In ,a drier of the rotary .oylinder type, an enter cy1indrica1 shell, an inner coaxial shell radiauy spaced fr om the.outer she1l so as to provide therebetween asteam chamber, a rim member at each end of said chamber uniting said shel1s, means for admitting steam ,to said cham- REFERENCES CITE!) Iheofloying references are of record in the -fi1 of thi Patent: r

UN ITED STAIES PATENTS 'Number Name Date .;543,051 Phillips July ;23, 1895 550,988 Mandot Dec. 10, 1895 -1,196,440 Doy 1e Aug. ,29, 1916 1,521,223 Wyld Dee.30, 1924 1,741,101 Dinardo eta1. ---Dec. 24, 1929 2,104,558. Gu%nheim Jan.A, 19.38 2,420,824 ,Hornbostel. et al. May 20, 1947 7 4 FOREIGN PATENTS Number Country Date 1,253 Great Britain Mar. 8, 1883 of 1883 r r 17,564 Great Britain Aug. 21, 1908 --of1908 r 195,975 A, Germany Oct. 13, 1906 618,742

Germany Sept. 1;1935

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