US3786868A

US3786868A - Self-compensating sector plate

Info

Publication number: US3786868A
Application number: US00246957A
Authority: US
Inventors: H Finnemore
Original assignee: Air Preheater Co Inc
Current assignee: Alstom Power Inc
Priority date: 1972-04-24
Filing date: 1972-04-24
Publication date: 1974-01-22
Anticipated expiration: 1991-01-22
Also published as: DE2320374C3; FR2181945A1; FR2181945B1; DE2320374B2; DE2320374A1

Abstract

A rotary regenerative heat exchanger having a rotor comprised of heat absorbent material that is alternately exposed to a hot and a cold fluid in order that heat absorbed from the hot fluid may in turn be transferred to the cold fluid. The rotor is surrounded by a housing including a sector plate at opposite ends of the rotor that separates the several fluids. A pivoted mounting means maintains the sector plate at an optimum distance from the rotor whereby fluid leakage from the rotor will be reduced to a minimum throughout a wide range of temperature variation and thermal expansion.

Description

atent 91 .nite States Finnemore Jan. 22, 1974 I SELF-COMPENSATING SECTOR PLATE [75] lnventor: Harlan E. Finnemore, Wellsville,

[73] Assignee: The Air Preheater Company, Inc., Wellsville, NY.

22 Filed: Apr. 24, 1972 211 Appl. No.: 246,957

[52] US. Cl. 165/9 [51] Int. Cl. F28d 19/04 [58] Field of Search 165/9 [5 6] References Cited UNITED STATES PATENTS 2,873,952 2/l959 Mudersbach et ah; l65/9 3,010,703 ll/l96l Bellows et al l65/9 Primary ExaminerAlbert W. Davis, Jr. Attorney, Agent, or Firm-Wayne H. Lang 5 7] ABSTRACT v A rotary regenerative heat exchanger having a rotor comprised of heat absorbent material that is alternately exposed to a hot and a cold fluid in order that heat absorbed from the hot fluid may in turn be transferred to the cold fluid. The rotor is surrounded by a housing including a sector plate at opposite ends of the rotor that separates the several fluids. A pivoted mounting means maintains the sector plate at an optimum distance from the rotor whereby fluid leakage from the rotor will be reduced to a minimum throughout a wide range of temperature variation and thermal expansion.

6 Claims, 3 Drawing Figures 1 SELF-COMPENSATING SECTOR PLATE BACKGROUND OF THE INVENTION .In rotary regenerative heat exchange apparatus a mass of heat absorbent element commonly comprised of packed element plates is positioned in a hot gas passageway to absorb heat from hot gases passing therethrough. After the plates become heated in the hot gas stream they are moved into a cool air passageway where the heated plates transmit their heat to cooler air or other gases passing therethrough.

The heat absorbent element is carried in a rotatable rotor that is surrounded by a fixed cylindrical housing including selector plates at the ends thereof that separate the hot gas from the cooler air. To prevent mingling of the two fluids, the end edges of the rotor are usually provided with flexible sealing members that extend to the adjacent surface of the surrounding rotor housing to resiliently accommodate a limited degree of thermal expansion and contraction that accompanies normal thermal variations within the rotor.

Under certain conditions, however, the temperature of the heat exchanger may rise rapidly so that the limit of allowable thermal expansion is exceeded. When this limit is exceeded the relatively movable parts of the rotor and the rotor housing also expand rapidly and are moved into direct interference one with the other so as tocause excessive abrasion and binding of the parts. Such wear may necessitate shutdown of the apparatus and repair of the sealing members before normal operation is resumed.

SUMMARY OF THE INVENTION In accordance with my invention, I therefore propose to'provide a unique linkage between the housing and the sector plate of a rotary regenerative heat exchanger whereby excessive changes in temperature and the thermal expansion due to said changes will cause the sector plate to remain at a predetermined distance from both the inboard and the outboard ends of the adjacent surface of the rotor whereby there will be no interference therebetween, abrasion of the sealing member will be maintained at a minimum, and there will be a minimum of luid leakage.

BRIEF DESCRIPTION OF THE DRAWING With reference to the drawing:

FIG. 1 is a cross-section of a rotary regenerative heat exchanger embodying an invention,

FIG. 2 is an enlarged cross-sectional view showing the details of the self-compensating sector plate, and

FIG. 3 is a diagrammatic representation of a rotary regenerative air preheater having rotor turn-down.

When rotated, the heat absorbent material carried by the rotor is alternately positioned in a hot gas stream and a cool air stream in order that heat from the hot gas is transferred to the cool air through the intermediary of the heat absorbent material. The hot gas enters the heat exchanger through an inlet duct 22 and is discharged, after traversing the heat exchanger material, through an outlet duct 24. The air in turn enters the heat exchanger through an inlet duct 26 and is discharged through an outlet duct 28 to which an induced draft fan is usually connected. After passing over the hot heat absorbent material 16 and absorbing heat therefrom, the stream of heated air is conveyed to its place of ultimate use.

A cylindrical housing 32 encloses the rotor in spaced relation thereto to provide an annular space 34 therebetween, while sector plates 36 at opposite ends of the rotor are provided with spaced apertures that admit and discharge the streams of hot gas and cooler air. In order that streams of gas and air do not bypass the rotor it is customary to position flexible circumferential seals on an end edge of the rotor shell 10 to confront the adjacent surface of the housing in a sealing relationship.

In a vertical inverted heat exchanger of the type here illustrated, the inlet for the hot or heating fluid is illustrated as being at the upper end of the rotor while the inlet for the cooler fluid to be heated is at the lower end of the rotor. Thus, the lower end of the rotor adjacent the inlet for the cool fluid is termed the cold end while that adjacent the hot gas inlet is termed the hot end of the rotor. It will be immediately apparent that the cold end of the rotor is subjected to less thermal distortion than the hot end that lies in the zone of maximum temperature variation.

Thus, the maximum thermal expansion of the rotor occurs at the top or hot" end of the rotor, and in response to this thermal gradient, the rotor assumes a shape similar tothat of an inverted dish shown by FIG. 3 and commonly known as rotor turn-down. The result of a phenomenon of this nature is to decrease the vertical clearance between the rotor and the surrounding rotor housing at the cold" end of the heater and to increase the vertical seal clearance at the hot" end of the heater sufficient to substantially increase fluid leakage between the relatively movable parts.

Inasmuch as the lower support bearing 17 is fixed to supporting structure and the upper guide bearing is axially movable, the upper guide bearing 18 moves up wardly in response to an increase of temperature. Simultaneously, the outer periphery of the rotor moves downwardly in the opposite direction in response to rotor turn-down. Therefore, my invention provides a pivotal support for the hot-end sector plate that is adapted to follow the radial inboard ends of the sector plate axially in the same direction as the thermal expansion of the rotor post, while the outboard end thereof is adapted to move oppositely to compensate for the turn-down at the rotor shell.

According, I provide a primary support 42 or tracking arrangement for the inboard end of the hot end sector plate. The support 42 depends from the housing for the guide bearing 18 or similar structure that moves axially in response to axial expansion and contraction of the rotor whereby the inboard end of the sector plate 36 will rise or fall in response to thermal expansion of the rotor.

A pivotal fulcrum is mounted for axial movement on the fixed rotor housing and is adapted to pivotally support the hot end sector plate at a pivot point 46 intermediate the inboard and outboard ends of the sector peate 36. Inasmuch as the rotor housing is maintained at a nearly constant temperature, it is not subjected to excessive thermal expansion and the fulcrum remains substantially fixed with respect to the adjacent sector plate 36 while the inboard end thereof moves up or down in accordance with the expansion of the rotor. Thus the sector plate is analagous to a lever whereby the outboard end thereof comprises its unsupported end. Thus an axial force applied at the inner end 42 of the sector plate about pivot 56 produces movement at the outboard end thereof opposite to that at the inboard end and in an amount dependent upon the ratio of the lever arms 47. and 49. The pivot 46 is provided with a radially adjustable mounting 45 that permits radial movement of the pivot 46 to effect a change in length of the

lever arms

47 and 49. Turning adjustment means 44 that bears against plate 50 moves thepivot 46 for plate 36 axially to achieve a predetermined clearance with respect to the adjacent rotor. Therefore, the outer end of the sector plate may be made to move axially the distance required to conform to the turndown at the outer periphery of the rotor so that an optimum sealing relationship continuously exists.

The sector plate 40 at the cold end of the heat exchanger is subjected to relatively little thermal variation and it may be pr-e-set on stationary brackets 52 in accordance with present standards so that it remains fixed throughout its period of operation. However, inasmuch as rotor turn-down at the cold end actually decreases the clearance space between the rotor and the sector plate, there will be closer tolerances and an improved sealing relationship.

While this invention has been described with reference to the arrangement illustrated in the drawing, it is evident that various changes may be made without departing from the spirit of the invention.

It is therefore intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and limited only by the terms of the following claims.

I claim:

1. A rotary regenerative heat exchanger having a rotor including a central rotor post and concentric rotor shell spaced therefrom to provide an annular space therebetween, a mass of heat absorbent material carried in the annular space between the rotor post and the rotor shell, a housing surrounding the rotor is spaced relation including inlet and outlet ducts at opposite ends thereof for a heating fluid and a fluid to be heated, bearing means supporting one end of the rotor adapted to remain at a fixed distance therefrom, a guide bearing at the opposite end of the rotor adapted to move axially according to the thermal expansion of the rotor, means for rotating the rotor about its axis, a pivotal sector plate intermediate an end of the rotor housing and adjacent end of the rotor including imperforate portions between spaced apertures that separate the heating fluid from the fluid to be heated, means movable in accordance with the axial expansion of the rotor adapted to support the sector plate at a point adjacent the inboard end of the rotor, and a fulcrum intermediate the rotor post and the rotor shell pivotally supporting the sector plate whereby axial expansion and contraction of the rotor post will similarly move the inboard end of the sector plate and oppositely move the outboard end of the sector plate.

2. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the means supporting the inboard end of the sector plate comprises the housing for the guide bearing that moves axially according to the thermal expansion of the rotor post.

3. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the pivotal sector plate is located at the end of the rotor adjacent the inlet for the heating fluid.

4. Rotary regenerative heat exchange apparatus as defined in claim 1 wherein the fulcrum pivotally supporting the sector plate lies more nearly adjacent to the rotor post than to the outboard end of the sector plate.

5. Rotary regenerative heat exchange apparatus as defined in claim 1 including radially movable means supporting the fulcrum whereby radial movement thereof willvary the ratio of distance between the fulcrum and the inboard and outboard ends of the sector plate and thus vary the axial movement of the outboard end of the sector plate.

6. Rotary regenerative heat exchange apparatus as defined in claim 5 including an axially movable means supporting the pivotal fulcrum.

Claims

5. Rotary regenerative heat exchange apparatus as defined in claim 1 including radially movable means supporting the fulcrum whereby radial movement thereof will vary the ratio of distance between the fulcrum and the inboard and outboard ends of the sector plate and thus vary the axial movement of the outboard end of the sector plate.