US3194301A - Radial flow rotary regenerative heater - Google Patents

Description

July 13, 1965 A. KQVATS 3,194,301

v RADIAL FLOW ROTARY REGENERATIVE HEATER Filed Nov.. 27, 196s -2 sheets-sheet 1 l .34 3l 45 INVENTO M A/vopf Kon/A 7.5

32 o 2' BY ,M ma, EZ 4 l z; ATTORNEY July 13, 1955 A. KovATs 3,194,301

RADIAL FLw ROTARY REGENERATIVE HEATER Filed Nov. 27, 1963 2 Sheets-Sheet 2 y I @W4 INVENTOR AND/P- Kl/A 7'5' ATTORNEY United States Patent O 3,194,301 RADIAL FLOW RUTARY REGENERA'IIVE HEATER Andre Kovats, Livingston, NJ., assigner to Foster Wheeler Corporation, New York, NX., a corporation of New York Filed Nov. 27, 1963, Ser. No. 326,401 3 Claims. (Cl. 16S- 7) This application is a continuation-inpart of U.S. patent application Serial No. 211,325, filed July 20, 1962, now abandoned.y

This invention relates to preheaters and particularly to radial flow rotary regenerative preheaters.

In preheaters which are most commonly used for heating combustion air for use in a furnace with the flue gases from the furnace, it has been standard practice for the hot and cold fluids to be fed in and out of a rotating matrix to transfer heat from the hot tluid to the cold fluid. A crossow design is most commonly used in which the cold fluid is passed across one side of the matrix through a straight duct in one direction while the hot huid is passed in the opposite direction through a straight duct across the other side of the matrix. As the matrix rotates about, the heat picked up by the matrix from the hot fluid is conveyed by thel rotating matrix to the cold fluid. In preheaters prior to this invention, as far as is known, the inlet cross-sectional area and the outlet crosssectional area of each of the ducts are equal. As is wellknown, when a fluid is heated, it expands thereby increasing its specific volume. Likewise, when a gas is cooled, it contracts with a resulting decrease in specific volume. Obviously in a preheater, changes in the specic volume of both fluids is continuously taking place. The result of changing specific volumes of both the hot fluid and the cold fluid in preheaters prior to this invention has been that as the tluids pass through a preheater, the velocity of llow of the uids is constantly changing. Such changes in velocity result in large energy losses requiring that the fans used to force the iiuids through the preheaters have added capacity.

By way of this invention, the outer surface of a ringshaped rotary matrix of a preheater can be divided into sectors representing equal arcs on the outside cylindrical surface. The same sectors result in equal arcs on the inside cylindrical surface. Obviously, the length of the arc on the inner surface is not as long as the arc on the outer surface, meaning that the sectors of the ring-shaped matrix converge toward the center ofl the cylindrical matrix. By diverging the top and bottom of the matrix toward the center, it is possible to compensate the decrease in dimension in one plane by an increase in dimension in the perpendicular plane,l thereby maintaining a constant cross-sectional area of passageway through each section of the matrix. In this way, as the tluid flows through the matrix and into the inner chamber within the matrix, it tlows through a passageway encompassing a number of sections, each section having a constant crosssectional area from the outer surface to the inner surface. By passing the fluid back through the matrix at an angle rather than at a straight line, it is also possible to use either a larger number of sections on the matrix or a smaller number, thereby either increasing or decreasing the cross-section area through the matrix depending upon the change in specific volume of the fluid. In this way the area through which the uid passes when it leaves the matrix may be made proportional to the change in specic volume of the iiuid caused by the quantity of heat either added to a removal from the fluid. If the fluid is cooled, -a smaller cross-sectional area is provided for the outlet pass through the matrix as compared to the inlet Mice pass through the matrix. if the uid is heated, a larger cross-sectional area is provided. In this way an approximately constant velocity yflow is provided for the fluids resulting in reduced iiow losses and increased efliciency.

Another source of loss in air preheaters has been the escape of fluids from around the matrix of the -preheater. By means of circumferential seals and radial seals which expand and contract with the expansion and contraction and movement of the rotating air preheater, it is possible to overcome such losses.

It is therefore an object of this invention to provide a preheater of improved economy and efficiency.

It is another object of this invention to provide a preheater with approximately constant velocity of ow for each uid passing through the preheater.

It is still another object of this invention to provide a preheater with minimum loss of fluids from around the matrix of the preheater.

It is still a further object of this invention to provide a preheater requiring minimum energy to force the fluids through the preheater.

Other objects and a fuller understanding of the vinvention may be had by referring to the following description and claims, taken in conjunction with the accompanying rawings in which:

FIGURE l is a partly broken plan sectional view of a preheater embodying the present invention and taken along line 1 1 of FIGURE 2.

FIGURE 24 is a vertical section of a preheater taken along line 2-2 of FIGURE l.

FGURE 3 is an venlarged detail illustrating the relationship of a radial seal to the inner and outer surfaces of the revolving matrix.

FIGURE 4 is an enlarged detail illustrating means for engaging a circumferential seal.

FIGURE 5 is an enlarged cross-section taken along the lines 5-5 of FIGURE 4.

FIGURE 6 is an enlarged cross-section taken along the lines 6-6 of FIGURE 4.

Referring now the drawings and more particularly to FIGURE l, the outside housing 2l has a first inlet port 22 which introduces a hot uid such `as tiue gas from a source (not shown). A first outlet port 23 removes the ue gas after it has passed through the air preheater to a stock (not shown) or other suitable place for removal. A second inlet port 2li introduces a cold huid such as combustion air from a source (not shown) to the preheater. Following the heating of the air, it passes through the second outlet port 26 for use for example in a furnace (not shown) or other device, requiring heated air. In a preheater of this type a matrix 27 is used to convey the heat from the hot fluid to the cold liuid. As best seen in FIGURE 2, the matrix 27 is supported by an interior shell 28. The interior shell 28 is mounted on a vertical post 29 by means of bearings itl for rotation. A top 30 and bottom 3l of the interior shell 23 enclose the matrix at these levels. A motor 32 'with a pinion 33 drives a ring gear 34 used to rotate the inner shell 2S and matrix 27 about the vertical axis of the post 29. During the rotation of the matrix 27, heat is extracted from the hot fluid and transferred to the cold fluid.

It is preferable to form the matrix 27 in sector portions 25. In this way a sector portion 25 `can be inserted into the matrix 27 through :an opening (not shown) in the top 30. The matrix 27 is designed in 4the form of a ring having an outer circumferential surface 39 yand an inner circumferential surface 41. Preferably, .the sector porltions 25 are equivalent. Disposed within each sector 25 are regenerative element-s '35.v Each element 36 is placed radially relative to the axis of the post `29 and is composed of a material suitable for storing heat. inner ends Yber 47,.

STOf'theregeherative lelements 36 lief along the inner surface 41. Outer ends 38 CofV the regenerative ele1nents.- 36 lie` along the youter surface G9. `The crossfsectional area formed by-the tvv-o adjacent regenerative .elements 36 andthe top 3d and botto-rn 31 represents -a separa-te;l Y' passageway 2@ for fluid flow. Y

In a plane perpendicular to Vthewcenter'line of the, posta,VY

' 39, as isV best shown in FIGURELeach sector portionZS converges to a smaller' and smallerV distance at-the inner.

" surface 41. The sector'portions 25 :are radially enclosed by Vsheets 42.' As is best shown in FIGURE 2,the't0p Y baffle 36 and bottom baffle 31v of the matrix Z7, however, are conically formed .so -asto diverge farther `and'fartherapart at the inner surface di. In this way as each passagevtfay 2l.) diverges in one plane to a smaller dimension, it converges in a perpendicular plane to a smaller vdirnenvon whethery the j elastic Vseal-sp;areequually:as suitablei.-

sion, thereby maintaining a constant total cross-sectional w Varea at each point ineach passageway 2th. In this way, as I Y a iiuid passes through the matrix 27, there is no change in the velocity of flow. As gases arecooled, they contract and increase in den-V sity 'and therefore have a smaller-.specific volume.V When heated,v gas expands thereby having a larger specific; iV

volume. Y fluid is beingy removed from thematrix as whenV 1t is being introduced into the,rnatrlix,.the, cross-section area of a passageway for flow must be through; the matrix v ifiby If the same.velocity of flow is. to exist when a changing ythe number of Vpassageways 2d throughthe t 4matrix Z7v proportionately to the change inspeciflcV Volume. ArsV is Vshown in FG-.URE ,1,fthe cross-sectional area ,of .the first inletv ductgZrZ-and therfpassageway 2d `associated therewith is substantially larger than Vthe crosssectional area of the iirst outletduct Z3 .and the passage,- Ways 26 associated therewith. ltris obvious, therefore,

that the first .inlet duct and the `rst outlet duct would .l

be used for the hot uid suchy as flue gas. The hot nuev.' Y

' gas .would enter .through the iirst inlet ductY 22 which gis-1 eomparativelylarge at the time `when the flue gas has a very large speciic volume `and low density. rfhe rst inletk duct 22 is associated with; a comparatively large j.

number of passageways Zd'through the matrix 27.V AS,`

the flu'evgasv passesthrough the passageways ,20, it be;`

. comes cooled rand reduces in specific volume. Due toV the decrease in specificgvolume, a smaller cross-sectional area is lrequired to remove the gases through the matrix at the same velocity with`which they were introduced i through .the matrix. For this reason, the first outlet ducty i Z3 also has a `smaller cross-sectional area.

The Isecond inlet duct 24, which introduces cool fluid into the preheaten'has a smaller cross-seotionalVa-rea than that of 'the second Aoutlet duct 26 through Vwhich'the heated fluid is discharged.` Y

The sequence of vinlet and outlet ducts here shown providesfor -a tWo-pass,counterow heatfexchange rela- Y TheV matrix 27' rotates from saidlsecond inlet to said first outlet,

tionshi-p between the hot gas vand the cold gas.

lfrornsaid first outlet ductj to said first inletV duct 22,

from said flrstfinlet duct 2,2 to said secondoutlet duct26 `and from saidsecond outlet duct ,26 vback to said-lirst inlet i ductk 2A Within thev inner surface Ilof `the matrix 27visga chamber 47 vwhich is divided by a partition 28 into -a first Vcompartment:49 and a second compartment Si. As best shown in FGURE'Z, plates 45 secured to shaft 29 pro-A vide, sealing for the Ytop and bottom of the axial. cham- Radial seals 54, as hestshown in FIGURES l and?, are

placed Vbetween the ends of the partitionl @and the inner" i surface 41 and between theroutside housing21 and matrix 27.' The radial seals 54 used in'association with the innerV surface 4d prevent leak-age -about the partition48 while the radial seals Seis-associated with an outer surface 39); Y

ofV thematrix 2.7 prevent leakage betweenrtwo adjacent' ducts Curvedsurfaces 61 with' sliding protrusi-ons 56 are provided on the radialj seals 54 forislidving association n with the; matrix27g. Theshape of .thesurfacel depends Circumferentiallips `63 Vivhich protude Vvfromfthe-,top` 39' and thebottor'r'lilsl of the `shell 28'are`in Slidingycntact Y. with `circurnfrerentialtsealsol; 'The'.circurnferential:seals f 64 are held inslidingcontact with the'lipvwbyme'ansof g springs 65 (FIG. 4) reachingbetween fixed bar Zand 'extension'l73'l The fixed bar72yis'securedto'theshousingg 21; The" spring :65 is mounted on rodhair/mehv sli'd'eablykr V.engages extensionLI Thecircumferentialjseals 64 "asti shown'in FIGURE14fareheld'againsttheoutsidethousing .21 by springs fand 69;' .The rod-Visthreadedto the;V bracket 59.'andthe rod"7 6'V is threadedtothe @bracket 661, Y An extension 77 'on the Yseal 'gdghas anfenlargedslot E9?? to permit tangential movement .of-thef-sealed?` The ro Linnercylindricalsurfacer l Althoughthe invention has beendescribedwitli acertain degree ofiparticularly, it is understoodl that theprese.VV ent disclosure has been made onlyj-bywayiof example;

andthatiuimerous changes 1in. the details of'construction and the combination and garrangerne'irtV ofparts may bere-V l sorted to without departing from the spirit-and '.s'copeof v the invention aslhereinafterrclaimed.`V I Y Y Y What i is vclaimed is:

l. Aregenerativefpreheater.forithefexchangeof-heat, i

betweenV a rst fluid and 'a second uidfcomprising:

Y a ring-shapedY permeable matrix Vhaving .anf inner, sur-l faceY and an puterv ,surfacev with equallyspacedregen Y VVerativeele'ments radially Vplaced between said surrfarfses so as to formaradial passageway between saidV eleai@ ments, said'elements beingdiver'gently shapedso that the; cross-sectionalarea .of the passageway .between two contiguous regenerative elements Vrfe'rnairis'- approximately .constant as the elements radially con-r:v

Y verse, enclosing means -a shaft supporting said.'matrix,v i

ing radial'seals"andcircumferential seals,

a partition withinthe, space idefinedifby said innmerglsur'rfiVv y Y face forseparatiiig said` space-,into arfrs/t compart lment Vand a second Cupartrnenn; i .Y y Y a first .inletgductdefininga crossfsectionalvarea oflpassageway radially-inward *for introducing a'firstuid Y throughsaid `matrix into Vsaid first compartment;

menta passageway radially inward"fergintroducinga secondV Y Y fluid through said matrixY into said .second-'co-mpart-'j ment, 1

a second outlet ,duct defining a` cross-sectionalflarea of passagewayradially` outward forfrenioving said sec- L f' ond uid through said matrix from said second com? v partment', land. 1

' means'forcontinuously rotating said matrix about said supporting shaft sothatsaid matrix AVpasses frornthe inlet ofcone fluid to thcrOutlet oftheother uidif surface lcontactstheinner surface elif. 5 -or the. Vouter surface 39f`of Vthe-matrix 2X7'. {'Spr'ings'd' f' :held within: channels 5 5 force the vsur-face ,61against'the;z i 'Y matrix. The springs elproviderforce for a positive'seal. i wh-ile stillproviding suicienttelasticity tofcompensatejfor g expansion and'ontractionandirregularities'inthe matrix V- ,y Y27. Itis to be understood, however;ithatjothertypes of 1V for. preventing. the' escape v off fluid te the outside atmosphere, said enclosing means includa tirst'outletlduct defining. cross-sectional ,areao'f passaugeway 4radially outward for removing saidiifr'st,I fluidthrough said matrixl from said ir'stQcompartf arseco'nd inletduct fdeiiningV a `xcrosssectional area of?" 2. A regenerative preheater for the exchange of heat between a hot fluid anda cold iiuid comprising:

a ring-shaped permeable matrix having an inner surface and an outersurface with equally-spaced regenerative elements radially placed between said surfaces so as to form a radial passageway between said elements, said elements being divergently shaped so that the cross-sectional area of the passageway between two contiguous regenerative elements remains approximately constant as the elements radially converge,

an outside housing surrounding said matrix,

a shaft supporting said matrix,

a partition within the space defined by said inner surface for separating said space into a first compartment and a second compartment,

a first inlet duct defining a cross-sectional area of passageway radially inward for introducing a hot fiuid through said matrix into said first compartment,

a first outlet duct defining a cross-sectional area of passageway radially outward for removing the hot fluid through said matrix from said first compartment, the first outlet cross-sectional area being sufficientlyrsmaller than the first inlet cross-sectional area to compensate for the decrease in specific Volurne of the hot fluid caused by the cooling effect of the matrix,

a second inlet duct defining a cross-sectional area of passageway radially inward for introducing a cold fluid through said matrix into said second compartment,

a second outlet duct defining a cross-sectional area of passageway radially outward for removing the cold fluid from said second compartment through said matrix, the second outlet cross-sectional area being sufhciently larger than the second inlet cross-sectional area to compensate for the increase in specific volume of the cold uid caused by the heating effect of the matrix,

an inner housing enclosing the top and bottom of said rotating matrix, said inner housing having inner and outer sealing lips,

plates enclosing the top and bottom of the space defined by the inner surface ci said matrix,

outside radial seals located between each duct to prevent leakage around the matrix within said outside housing,

inside radial seals located at the ends of said partition to prevent leakage about said partition,

inner circumferential seals including bands in sliding relation with said inner scaling lips,

springs for forcing said inner circumferential seals against said lip,

springs for forcing said inner circumferential seals .against said enclosing plates,

outside circumferential seals including bands in sliding yrelation with said outside sealing lips,

springs for forcing said bands against said outside sealings lips,

springs for forcing said outside circumferential seals against said outside housing, and

means for continuously rotating said matrix about said supporting shaft in a direction from said second inlet to said first outlet, from said first outlet to said first inlet, from said first inlet to said second outlet, and from said second outlet back to said first inlet.

3. A regenerative preheater according to claim 2 wherein the first inlet duct and first outlet duct are at an angle to one another and the second inlet duct and second outlet duct1 are at an angle to one another.

References Cited by the Examiner UNITED STATES PATENTS 2,631,870 3/53 Hodson 165-9 FOREIGN PATENTS 982,174 1/ 51 France.

OTHER REFERENCES Daimler-Benz, Germany printed application No. 1,121,-

CHARLES SUKALO, Primary Examiner.

Claims (1)

1. A REGENERATIVE PREHEATER FOR THE EXCHANGE OF HEAT BETWEEN A FIRST FLUID AND A SECOND FLUID COMPRISING: A RING-SHAPED PERMEABLE MATRIX HAVING AN INNER SURFACE AND AN OUTER SURFACE WITH EQUALLY-SPACED REGENERATIVE ELEMENTS RADIALLY PLACED BETWEEN SAID SURFACES SO AS TO FORM A RADIAL PASSAGEWAY BETWEEN SAID ELEMENTS, SAID ELEMETNS BEING DIVERGENTLY SHAPED SO THAT THE CROSS-SECTIONAL AREA OF THE PASSAGEWAY BETWEEN TWO CONTIGUOUS REGENERATIVE ELEMETNS REMAINS APPROXIMATELY CONSTANT AS THE ELEMENTS RADIALLY CONVERGE, ENCLOSING MEANS FOR PREVENTING THE ESCAPE OF FLUID TO THE OUTSIDE ATMOSPHERE, SAID ENCLOSING MEANS INCLUDING RADIAL SEALS AND CIRCUMFERENTIAL SEALS, A SHAFT SUPPORTING SAID MATRIX, A PARTITION WITHIN THE SPACE DEFINED BY SAID INNER SURFACE FOR SEPARATING SAID SPACE INTO A FIRST COMPARTMENT AND A SECOND COMPARTMENT, A FIRST INLET DUCT INWARD FOR INTRODUCING A FIRST FLUID SAGEWEAY RADIALLY INWARD FOR INTRODUCING A FIRST FLUID THROUGH SAID MATRIX INTO SAID FIRST COMPARTMENT, A FIRST OUTLET DUCT DEFINING A CROSS-SECTIONAL AREA OF PAS SAGEWAY RADIALLY OUTWARD FOR REMOVING SAID FIRST FLUID THROUGH SAID MATRIX FROM SAID FIRST COMPARTMENT, A SECOND INLET DUCT DEFINING A CROSS-SECTIONAL AREA OF PASSAGEWEAY RADIALLY INWARD FOR INTRODUCING A SECOND FLUID THROUGH SAID MATRIX FROM SAID FIRST COMPARTMENT, A SECOND OUTLET DUCT DEFINING A CROSS SECTIONAL AREA OF PASSAGEWAY RADIALLY OUTWARD FOR REMOVING SAID SECOND FLUID THROUGH SAID MATRIX FROM SAID SECOND COMPARTMENT, AND MEANS FOR CONTINUOUSLY ROTATING SAID MATRIX ABOUT SAID SUPPORTING SHAFT SO THAT SAID MATRIX PASSES FROM THE INLET OF ONE FLUID TO THE OUTLET OF THE OTHER FLUID.

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