US3079991A - Rotor construction for rotary regenerative heat exchanger - Google Patents

Description

s ETAL 3,079,991 TIoN FOR ROTARY E HEAT EXCHANGER i ed July 17, 1959 March 5, 1963 J'fyff en... f e

United States Patent ice 3,979,991 Patented Mar. 5, 1963 3,079 991 ROTGR CNSTRUCTIN FOR ROTARY REGEN- ERATVE HEAT EXCHANGER Ted C. Evans and Charles A. Lyle, Welisville, NSY., as-

signors, by mesne assignments, to Combustion Engineermg, Ine., a corporation of Delaware Filed July 17, 1959, Ser. No. 827,774 1 Claim. (Cl. 165-7) This invention relates to rotary regenerative heat exchange apparatus and particularly lto an arrangement that substantially precludes its thermal distortion during periods of normal operation.

' In rotary regenerative heat exchange apparatus a cylindrical rotor having sectoral compartments provided by radial partitions or diaphragms that connect a central rotor post to a concentric rotor shell is adapted to carry a mass of regenerative heat exchange material. The rotor is adapted for rotation in such a manner that the heat exchange material is rst exposed to a heating iiuid to `absorb heat therefrom, and as the rotor is turned about its axis, the heat exchange material is then disposed in a passageway for a fluid to be heated'where the heat absorbed by the heat exchange material is imparted to the uid owing therethrough.

During operation such apparatus is continuously subjected to varying degrees of temperature whereby variations of thermal expansion resulting therefrom produce a warping and twisting of the rotor and its surrounding housing that generally precludes an efficient sealing of one fluid from another.

This invention is directed to a rotary regenerative heat exchanger having a structural arrangement such that temperature variations thereof induce substantially constant expansion or contraction that results in -a minimum of distortion.

The heat exchange apparatus particularly referred to in this application comprises an improvement to the type generally described in U.S. Patent 2,680,008, issued June l, 1954 to Per Hilmer Karlsson. In this patent the heat exchange element of a rotary regenerative heat exchanger is arranged in axially disposed banks in such a manner that fluid flowing through the heat exchange material is required to ow in a radial direction to make possible the use of a heat exchange element having a large surface area and a relatively shallow depth.

Such -an arrangement directs the heating fluid and the fluid to be heated across each partition in a manner such that the hottest fluid contacts one end of the partition and the coldest uid contacts the other. The resulting temperature ditferential at opposite ends of a metallic partition produces a variation of expansion that induces severe deformation of vthe partitions and connecting housing structure to greatly reduce its operating efficiency.

The present invention is directed to an improvement of the above described apparatus having a particular structure that directs hot duid on one side of a metallic partition Iand cold uid on the side laterally opposite whereby the temperature of the partition tends to approach a mean between the temperature of the heating fluid and the lluid to be heated that is approximately uniform throughout the partition. Thus, while each partition is free to expander contract, with normal variations of temperature, the expansion will be uniform and not subject to distortion.

The invention will be more clearly described with reference to the embodiment Ithereof shown by way or" example in the accompanying diagrammatic drawing in which:

FIGURE 1 is a partial top View of the heat exchanger utilizing the invention.

FIGURE 2 is an axial section of the rotary regenerative heat exchanger as seen from line 2-2 of FIGURE 1.

FIGURE 3 is a diagrammatic representation of thermal distortion in a rotor partition having a temperature gradient running from end -to end.

FIGURE 4 is a diagrammatic representation of the even expansion of a rotor partition according to this invention wherein opposite sides of the same partition are subjected to opposite extremes of temperature.

In the drawing numeral 10 designates the cylindrical shell of a rotor divided into sector shaped compartments 11 by radial partitions 12 that connect to an axially central rotor post 14 which is driven by a gearing arrangement 16 and dri-ving means (not illustrated) that turns the rotor slowly about its axis. The sector shapedcompartments 11 are adapted to contain regenerative heat transfer material 24 which first absorbs heat from a heating uid entering the regenerator through a duct 18 from a combustor or other source and is discharged through an outlet 22 after havingl passed through the bank of perforate heat Itransfer material 24. As the rotor turns slowly about its axis the heated material 2 4 is transported into a stream of the Huid to be heated that is admitted through duct 26. After passing over the heated material 24 and absorbing heat therefrom, the stream of heated iluid is conveyed through duct 28 to any predetermined place of use.

A housing 32 encloses the rotor and is provided at either end opposite the latter with end or sector plates 34 which are apertured as at 36 in alignment with ducts 18-22 and 26-28. In order that the streams of heating uid and the fiuid to be heated may be maintained in completely different duets, sealing means are provided at the `ends of the rotor to wipe against the sector plates of other fixed pants of the rotor housing.

Since the heating fluid and the fluid to be heated are usually directed through the heat exchanger in a counterow arrangement, the inlet for the heating duid and the outlet for the heated uid lie at adjacent ends of the rotor While the outlet for the cooled heating uid and the inlet for the uid to be heated lie at the same end of the rotor. Thus the rotor is divided into two basic temperature zones, the one which lies adjacent the inlet for the heating fluid being termed the hot end While that adjacent the inlet for the liuid to be heated is termed the cold end of the rotor. The radial partitions being part of the rotor are thereby subjected t-o a temperature differential that effect an expansion 'at the hot end in the manner illustrated in FIGURE 3. A Series of such partitions formed into a rotor and similarly expanded by variations of temperature produces a serious degree of rotor distort-ion that precludes eicient rotor operation.

In accordance with the present invention the heat transfer material is supported in axially disposed banks intermediate the rotor shell and rotor post whereby laterally adjacent banks of material together form a composite annular mass of element concentric with the rotor axis. The annular bank of heat transfer material 24 is provided with a multitude of radially disposed perforations in order that huid flowing between inlet and outlet ports is directed through the heat transfer material in a radial direction and in order that fluid will ow in radial opposite directions while traversing adjacent sectoral compartments, axial passageways 42 and 44 are provided with closure plates 46 at alternate ends thereof in the manner illustrated by FIGURE 2 of the drawing. By this arrangement, uid entering a radial outer passageway 4Z flows axially until it is turned radially inward through the bank of heat exchange material to the inner passageway 44. Here the fluid is again directed iaxially to continue its ow to the exhaust duct. Conversely, uid en- 3 ytering Ia radial inner-passageway 44 ows axially until it is directed radially outward through the bank of heat exchange material to passageway 42 where it again is Vdirected axially to the exhaust duct. t Thus while fluid isll'owing radially outward through the'bank of -heat exchange material in one sectoralv corujpartrnent, it is 'owing through thebanks of-e1ement in Y -[the adjacentcompartments lin a yradially opposite direction in such a manner that opposite vsides .of each partition are subjected `to opposite extremesof temperature. Thus the1` partitions tend to1 arrive at. a mean between fthe aver- Yagetemperature of the heatingfluid and Vthetfluid to be heated. Under theseconditions thediaphragms will ex- :pand evenlywith they increase of temperature inthe man- 4,11er.illustratedin FIGURE 4, therewill be no variable expansion a or. distortion, and sealing. surfaces will retain their .original clearance settings.

While this inventionthas been described with reference .to embodimentiillustrated :in the drawing, it is evident `:that numerouschangestmay be made Awithout departing .fromthe spiritof the invention. It is therefore intended that allnmatter contained .in the above description or lnhowninthe accompanying `drawings shall be interpreted .as illustrative and Tnotiinla limiting sense.

`lWhat we claim-is: t

-Rotaryregenerative ,heat exchange apparatus or .the ilike lhavinga :rotor including a cylindrical rotor shell -dividedfinto sectoral compartments by partitions that extend radially. from .the rotor shell to an axiaIly central i rotor post, and a housing surrounding the rotor shell pro` vided at opposite ends with paired inlet and outlet ducts for the ow of a heating fluid and a fluid to be heated to and through the rotor; axially extending banks of perforate heat exchange material disposed similarly between partitions of adjacent compartments Ito provide a composite annular mass of heatexvchange material concentric with the rotor taxis;taxia1 flow passageways adjacent the. radial inner and outer Jsidesv of /thebanksrof heat-exchange -materialproviding radial inner and outerr'passageways for the flow ofiuid toand fromthebanks of heat exchange material; and closure means positioned at alternate ends'iof laterally adjacent passageways and at alternate ends `of the radially inner and outer passageways adapted to ,direct uid ow in radially `opposite directions through banks of: elementlying inla'terally .ad-

jacent compartments whereby laterally opposite sides of the radial partitions are subjected .to oppositeextremes of iluid temperature.

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