US2732183A - hammond - Google Patents

Description

Jan. 24, 1956 w. E. HAMMOND SUPPORTING ROTOR INDEPENDENTLY OF HOUSING IN AIR PREHEATERS Filed May 22, 1951 2 Sheets-Sheet l fir I R TORY "4 I 0 C76! AIR 32 PREHEATER THERAL 954mm,

5 h INVENTO. I g E Wl/lmm E. l/ammona L-\ g3 in BE BY M W 65 3% i ITO/FIVE) United States Patent '0 SUPPORTING ROTOR INDEPENDENTLY OF HOUSING IN AIR PREHEATERS William E. Hammond, Wellsville, N. Y., assignor to The Air Preheater Corporation, New York, N. Y.

Application May 22, 1951, Serial No. 227,677

12 Claims. (Cl. 257-6) The present invention relates to regenerative air preheaters of the rotary type and particularly to improvements in the construction, mounting and support of the rotor and stationary housing that encloses it so as to re duce or eliminate the effects of mechanical and thermal distortion.

In such air preheaters a rotor carries heat transfer plates, usually metallic, which when positioned in the gas passage absorb heat that is imparted to air when the rotor is turned to dispose the plates in the air passage. The rotor is enclosed in a housing to which the gas and air ducts are connected and this housing is provided with end plates that have apertures alined with the gas and air passages through the rotor. Circumferential seals are provided to preclude by-passing of gas and air through the space between the rotor and the housing and radial seals to prevent mingling of the gas and air streams are provided on the partitions that divide the rotor into compartments that contain heat transfer material. All of these seals on the rotor engage the end plates or adjacent parts of the housing. To permit turning of the rotor certain clearances are required and heretofore these clearances have been based upon calculations of deflections imposed solely on the rotor due to its being subjected to fluids at difierent temperatures as it rotates. Consequently deflections of the housing due to mechanical loads, the method of its mounting, and thermal expansion all serve to modify the presumed clearances.

Both the housing and the connecting plate between the end plates and ducts are flexible and will'distort under the action of the various forces. Further, the rigidity along the axis of the pair of diametrically located supporting members adjacent the gas and air ducts called duct feet is not the same as that along the axis of similar supporting members positioned at right angles thereto and known as beam feet because aligning with a supporting beam. Consequently, the deflections along each axis differ as a function of the sectional rigidity and load distribution thus producing distortion of the housing. In addition to this, the structural steel on' which the duct feet rest has a rigidity along this axis of support that is different from that of the structural steel along the axes of the other supports or beam feet. Furthermore, the thermal expansions of the upper and lower end plates are not the same because of temperature differences so that a force couple is applied which also tends to defiectthe housing.

In the so-called inverted type of heater in which the gas flows downwardly and the air upwardly so that the top is hottest, the thermal forces act to raise the duct side of the housing and are assisted by the reactions at the duct feet, which are in the same direction and so'further the distortion. The result of deflections of this nature in an inverted heater is to decrease the vertical clearance between the seals at the cold end of the heater in the regions where the ducts are connected and to increase the vertical gases flow upwardly and the air flow is downwardly so that the top end is colder, the thermal force couple acts to lower the duct side of the housing which is now resisted by the reaction at the duct feet. Thus, the reaction forces tend to restrain the distortion and maintain it at a low magnitude.

With present heaters the Weight of the rotor is transferred to the upper end plate and then through the housing to the supporting feet that rest on the steel work. Where a transverse beam is located on the upper end plate in between the ducts to suspend the rotor, the load is transmitted diagonally through the housing from the beam to the duct feet located in the positions of the ducts.

The present invention contemplates independent supporting of the rotor and of the housing. The rotor is suspended directly on the structural steel so that the housing is not required to carry any rotor load. At the same time the weight of the housing is carried on the supporting structure at the same point of the application as the rotor load, consequently deflections of the supporting beam do not aflect the seal clearances between the rotor and housing because the efiects of deflection of the beam are necessarily the same with respect to both. This supporting arrangement permits the housing itself to be of relatively light construction as only a wrapper sheet is required so that it may serve its fundamental function of confining and guiding the fluids. The end plates of the housing are also supported so that radial expansion may occur and the structure between the upper and lower end plates of the housing is arranged so that it assumes a temperature close to that of the rotor, thus reducing any relative motion between the rotor and the end plates.

The invention will be best understood upon consideration of the following detailed description of illustrative embodiments thereof when read in conjunction with the accompanying drawings in which:

Figure 1 is an elevational view illustrating the conventional manner of mounting a rotary preheater in a boiler installation.

Figures 2 and 3 are diagrammatic views illustrating the relation of the rotor and housing of an inverted vertical heater with downward gas flow when cold and under operating conditions, respectively.

Figures 4 and 5 are similar diagrammatic views showing the relation of rotor and housing in a vertical heater with upward gas flow.

Figure 6 is an axial section or elevational view of a rotary air preheater constructed and supported in accordance with the present invention. 7

Fig. 7 is a plan view on the line 7-7 of Figure 6.

Figure 8 is a broken-away and fragmentary view showing the-tying connections between the upper and lower end plates as viewed along the line 8-8 in Figure 7.

Figure 9 is an enlarged sectional view showing a special mounting of the end plate.

Figure 10 is a sectional view on the line 1010 in Figure7and Figure 11 is a broken-awayaxial section similar to Figure 1 showing a heater resting on the beam support rather than suspended therefrom.

In Figures 6 to 10 of the drawings the numeral 10 designates a rotor having a cylindrical shell 11 divided into sector shaped compartments by radial partitions 12 (Fig. 7) connecting it with the rotor post 13 which is driven by a motor and reduction gearing 14 to turn the rotor slowly about its axis. The rotor compartments contain regenerative heat transfer material in the form of closely spaced metallic plates 15 which first absorb heat from hot gases entering the preheater through a duct 16 from a boiler or other source to be discharged after passing over the heat transfer plates through an outlet duct 17 (see Fig. l also) to which an induced draft fan is connected. As the rotor turns slowly about its axis, the heated plates 15 are moved into the stream of air admitted through the duct 18 to which a forced draft fan is connected and after passing over the plates 15 and absorbing heat therefrom the stream of air conveyed to the boiler furnace or other place of use through duct 19.

A housing 20 enclosing the rotor it) is provided at either end opposite the latter with upper and lower end or sector plates 21, 22 which are apertured at 23 and 24- (Fig. l) in circumferentially spaced locations to admit and discharge streams of gas and air flowing through the rotor. In order that the streams of gas and air .3 not commingle, the end plates 21, 22 have impel-for portions 25 located between the gas and air openings that are at least equal to but usually somewhat greater in circumferential extent than one rotor compartment for engagement by radial seals 26 to isolate or block off at least one compartment when it is in a position between the gas and air passages. In order that the streams of gas and air may not by-pass the heat transfer surface 15 by flowing axially in the annular clearance space 27 between the rotor shell 11 and the housing 20 it is customary to provide circumferential seals indicated diagrammatically at 28 on the shell 11 which wipe against confronting parts of the end plates 21, 22 or allied parts so as to seal ofl? the space 27.

conventionally the air preheater is supported as illustrated in Figure l on the structural steel scaffolding 30 of a boiler 31. Support or duct feet 32 connected to the rotor housing 21 rest on the beams 33 carried by the scaffolding 30 and diametrically located beam feet" i are also provided at 34 on the housing.

In an inverted vertical heater having downward gas flow as indicated in Fig. 2, the rotor 10 when heated becomes dished in convex fashion as shown in Fig. 3 be cause of the temperature differentials between its upper (hot) and lower (cold) ends. The housing 20 also distorts since the upper end plate is hotter than the lower end plate so that in effect the housing diameter decreases at the top of the housing and the duct feet 32 lift up. The duct foot reactions being in the same direction as the thermal deflection increase the deflection of the housing and the interference between housing and rotor as well as open up clearances between the seals and the end plates.

With a vertical heater in which gas flow is upward as indicated in Fig. 4 the rotor 10 becomes dished in concave fashion because it is hotter at the bottom than the top. The lower end plate being subjected to higher temperattu'es than the upper end plate increases in effective diameter and the duct feet move downward due to the thermal reaction and the duct feet reactions oppose the thermal reaction as indicated in Fig. 5 and tend to reduce the net housing-rotor interference.

In accordance with the present invention as shown in Figures 6 to ll, :1 main supporting beam 35 is mounted the boiler structural work 39 between the beams 33 and from this horizontal main beam the rotor 10 and housing 20 are independently supported. The rotor it) is suspended from the supporting beam 35 at or near its mid-point through a conventional support bearing 36 associated with the upper end of the rotor shaft 37. At its lower end the rotor shaft 37 extends into a guide bearing 38.

Attached to the under side of the horizontal beam 35 is a circular cantilever or spider beam 40 having a support column 41 through which the rotor shaft 37 extends, the column being connected by radial ribs 42 to the circular part 43 of beam 40. The beam 46 replaces the conventional connecting plate structure which ordinarily is located between the ducts 17, 18 and the end plate 21 and is connected to both ducts and end plate. The beam 40 forms a cantilever support to which the annular flange portions 44 of the upper end plate 21 are fastened. The lower end plate 22 is suspended from the cantilever beam 40 through the upper end plate 21 by means of the su port columns 45 which are pinned at their upper and lower ends to lugs 46 on the two end plates so as to permit relative movement between these end plates, particularly in a radial direction. A second but lighter circular beam or spider 47 attached to the lower end plate 22 carries the guide bearing 38 for the shaft 37 of rotor 153". In Figure 9 the housing 48 proper for the rotor comprises a thin sheet of metal wrapped around the rotor between the end plates 21, 22 in a location radially outside of the support columns 45 so that these supporting columns are subjected to the same gas and air temperature conditions as the rotor 10 and the end plates 21, 22 of the housing 20.

With the construction described above, the rotor 11 is supported and suspended at the center through the bearing 36 that rests on the horizontal support beam 35. The housing is independently supported by connection to the beam 35 through the center support column 41 of the cantilever beam 40 with the result that all expansions of the rotor 19 and housing 20 are directed in the same direction so that the differentials of expansion be tween the rotor and the housing are minimized. Since the support columns 45 that connect the upper and lower end plates 21, 22 are pivotally connected to these 1 .rts, no stresses are introduced by the expansion differential between the upper and lower end plates which are at the hot and the cold end, respectively, of the heater. This pin mounting is capable of accommodating differences in expansion between the hot and cold ends of the heater without introducing force couples or high concentrations which tend to lift the heater in the regions where the end plates are connected to the gas and air ducts 16-19.

In Figures 7, 9 and 10 the upper end plate 21 is shown supported by a separate suspension independently of the direct support of the housing 20 from the upper support spider 40. Where the radial ribs 42 that extend from the spider hub or support column 41 cross imperforate parts 25 of the upper end plate 21, they are welded to it. The perimeter of end plate 21 is alined with a flange 50 of beam 40 which is in turn attached to a. flange 51 on the housing as is usual with connecting plates. The clearance 52 (Fig. 9) between the upper end plate designated 21 in Figure 7 and the flange 59 which heretofore has been part of the plate permits the upper end plate 21 to expand and contract in a radial direction independently of the housing 20. A sectorial bafile plate 53 (Figs. 7 and 9) welded to the spider ring 43 overlaps the alined ends of the edges of the sector plate 21 at its perimeter and the inner edge of the circular flange 5t) and covers gap 52. Between the outer ends of the radial ribs 42 and the circular ring 43 of the spider 4t expan sion tubes 54 are provided which are semi-circular in shape and of relatively light material which will flex upon radial outward movement of those ribs 42 that are welded to the sector plate 21.

in Figure 11 the entire preheater is mounted above the support beam 35, the lower cantilever beam 47 being directly attached to the exchanger support beam 35 by bolting of a flange 55 at the lower end of the support column 41 to the support beam 35. Here the support bearing 36 for the rotor shaft 37 is mounted on the under side of the main support beam 35 and the guide bearing 38 is at the upper end and is mounted on a plate 56 apertured for passage of the rotor shaft 37 and connected to the hub 41 of the upper circular spider 40.

What I claim is:

1. In apparatus having a cylindrical rotor turning with a vertical rotor shaft and carrying material for contact by hot and relatively cool fluids and a housing surrounding the rotor and provided with end plates formed at opposite sides of the rotor axis with apertures for the admission to and the'discharge-from the rotor of said fluids; a horizontally mounted structural member extending transversely of the housing in a central location and in vertically spaced relation with respect thereto; connecting means between a central portion of said housing and said structural means for the support of the housing thereby; and a support bearing for said rotor shaft carried by said structural means for separately supporting said rotor independently of said housing.

2. In apparatus having a cylindrical rotor turning with a vertical shaft and carrying material for contact by hot and relatively cool fluids and a housing surrounding the rotor and provided with end plates formed at opposite sides of the rotor axis with apertures alined with supply and discharge ducts for said fluids for the admission to and the discharge from the rotor of said fluids; a horizontal structural beam mounted to extend transversely of the housing in a central location and in vertically spaced relation with respect thereto; horizontally spaced members supporting said beam; connecting means between the central portion of said housing and said beam for the support of said housing thereby; and a support bearing for said shaft carried by said beam for separately supporting said rotor.

3. In apparatus having a cylindrical rotor turning with a vertical shaft and carrying material for contact by hot gases and relatively cool fluids and a housing surrounding the rotor and provided with end plates formed at opposite sides of the rotor axis with apertures for the admission to and the discharge from the rotor of said fluids; a structural beam extending transversely above the housing in a plane normal to the axis of rotation of said rotor; horizontally spaced means supporting said beam; means connecting said housing to said beam in a central location between said supports for suspending said housing from said beam; and a support bearing for said shaft mounted on the central portion of said beam for separately suspending said rotor directly therefrom independently of said housing.

4. In apparatus having a cylindrical rotor turning with a vertical shaft and carrying material for contact by hot and relatively cool fluids and a housing surrounding the rotor and provided with end plates formed at opposite sides of the rotor axis with apertures for the admission to and the discharge from the rotor of said fluids; a structural beam mounted to extend across the housing in a central location beneath the latter; means attaching said housing to a central portion of said beam for supporting said housing upon said beam; and a support bearing for said shaft carried by said beam for separately supporting said rotor directly thereon.

5. An air preheater structure as recited in claim 2 wherein the housing is connected at one end to said fluid ducts by a transition piece comprising a circular beam annularly attached at the perimeter thereof to said housing and joined by webs to a member attached to a portion of said structural beam located centrally between the said support members therefor.

6. An air preheater structure as recited in claim 2 wherein the housing is connected at one end to said fluid ducts by a transition piece comprising a circular beam annularly attached at the perimeter thereof to said housing and joined by radial ribs to a central collar surrounding said shaft and attached to said structural beam.

7. In an air preheater or the like having a rotor turning with a vertical shaft and carrying material contacted by hot and relatively cool fluids: a beam extending in a central position transversely of said rotor; horizontally spaced members supporting said beam; a supporting bearing for said shaft carried on said beam for supporting said rotor; housing end plates mounted in confronting relation to the ends of the rotor and formed with apertures at opposite sides of the rotor axis for the flow of fluids to and from the rotor; duct connecting plate assemblies attached to said end plates at either '6 end of the rotor; means attaching the connecting plate assembly at one end of the rotor to said beam in a central position between the support members therefor for supporting said housing; support columns extending between said sector plates opposite the sides of the rotor; means securing each column at or adjacent its ends to said sector plates; and a relatively thin, light weight wrapper sheet positioned radially outward of said columns and extending around the rotor between said sector plates and together with the latter forming a housing enclosing said rotor.

8. In an air preheater or the like having a rotor turning with a vertical shaft and carrying material contacted by hot and relatively cool gaseous fluids: a beam ex tending in a central position transversely above said rotor; a supporting bearing for said shaft on said beam for suspending said rotor directly therefrom; housing end plates mounted in confronting relation to the ends of the rotor and formed with apertures at opposite sides of the rotor axis for the flow of fluids to and from the rotor; duct connecting plate assemblies attached to said end plates; means attaching a central portion of the connecting assembly plate at the-upper end of the rotor. to said beam for supporting and suspending said housing from said beam; support columns extending between said end plates opposite the sides of the rotor; means pivotally connecting each column at or adjacent its ends to said end plates; a wrapper sheet extending around the rotor between said end plates and together with the latter forming a housing enclosing .said rotor.

9. In an air preheater or like apparatus having a cylindrical rotor turning with a vertical shaft and carrying material for the transfer of heat between hot and relatively cool fluids and a housing surrounding the rotor and provided with end plates formed at opposite sides of the rotor axis with apertures for the admission to and the discharge of said fluids from the rotor; a horizontal beam fixed to upright structural work at the sides of the preheater assembly and extending in a central position transversely of the preheater; a bearing mounted on said beam and connected to the shaft of the rotor for direct support of the rotor by said beam; a duct connecting piece located between said beam and the preheater housing; and means attaching the central portion of said connecting piece to said beam for separately supporting said housing.

10. In an air preheater or like apparatus having a cylindrical rotor turning with a vertical shaft and carrying material for contact by hot and relatively cool fluids; circular end plates confronting either end of the rotor formed at opposite sides of the rotor axis with alined apertures for fluid flow spaced by intervening imperforate portions; a horizontal beam fixed to upright structural work at the sides of the preheater and extending in a central position transversely of one end of the preheater; a bearing mounted on said beam and connected to the shaft of the rotor for supporting the latter on said beam; a wrapper sheet surrounding the rotor and provided at either end with annular connecting flanges lying in the planes of said end plates opposite the latter in alinement therewith with a narrow annular space intervening between the perimeter of said end plate and the inner periphery of said flange; a spider member between said beam and housing comprising a circular beam attached at the perimeter thereof to one connecting flange of said housing and joined by radial ribs to a central collar surrounding said shaft and attached to said beam; means connecting those of said ribs which cross imperforate portions of the end plate to the latter along their radial edges; arcuate expansion pieces of flexible material located between the distal ends of said last ribs and said circular beam; and means attaching the remaining ribs at their ends to said circular beam.

11. In an air preheater or like apparatus having a cylindrical rotor turning with a vertical shaft and carrying material for contact by hot and relatively cool fluids;

circular end plates confronting either end of the rotor formed at opposite sides of the rotor axis with alined apertures forfiuid flow spaced by intervening imperforate portions; a horizontal beam fixed to upright structural work at the sides of the preheater and extending in a central position transversely of one end of the preheater; a bearing mounted on said beam and connected to the shaft of the rotor for supporting the latter on said beam; a wrapper sheet surrounding the rotor and provided at either end with annular connecting flanges lying in the planes of said end plates opposite the latter in alinement therewith with a narrow annular space intervening between the perimeter of said end plate and the inner periphery of said flange; a spider member between said beam and housing comprising a circular beam attached at the perimeter thereof to one connecting flange of said housing and joined by radial ribs to a central collar surrounding said shaft and attached to said beam; means connecting those of said ribs which cross imperforate portions of the end plate to the latter along their radial edges; arcuate expansion pieces of flexible material located between the distal ends of said last ribs and said circular beam; means attaching the remaining ribs at their ends to said circular beam; and annular baffle plates covering the spaces between said end plates and flanges.

12. In an air preheater or like apparatus having a cylindrical rotor turning with a vertical shaft and carrying heat transfer material by partitions extending radially from a shaft about which the rotor turns and a housing surrounding the rotor and provided with end plates covering the rotor in confronting relation thereto at either end and formed at opposite sides of the rotor axis with aligned apertures for fluid flow; a horizontal beam fixed above the preheater to upright structural work at the sides of the preheater assembly and extending transversely of the preheater in the plane of the rotor axis; a bearing mounted on said beam and associated with the shaft of the rotor for suspending the latter from said beam independently of said housing; annular connecting flanges on said housing lying in the planes of said end plates opposite the latter in alignment therewith with narrow annular spaces intervening between the peripheries of said end plates and the inner perimeters of said flanges; a spider member between said beam and housing comprising a circular beam attached at the perimeter thereof to a connecting flange at the upper end of said housing and joined by radial ribs to a central collar surrounding said shaft and attached to said beam; means connecting those of said ribs which cross the end plates to the latter along their radial edges; flexible expansion pieces of semi-circular extent located between the distal ends of said last ribs and said circular beam; means attaching the remaining ribs at their ends to said circular beam; and sectorial baffle plates covering the spaces between said end plates and flanges in the region of the apertures in said end plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,224,787 Horney Dec. 10, 1940 2,313,081 Ljungstrom Mar. 9, 1943 2,480,277 Yerrick Aug. 30, 1949 2,516,992 Hochmuth Aug. 1, 1950 FOREIGN PATENTS 587,035 Great Britain May 4, 1945 700,760 Germany Dec. 30,1940

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