US2692761A

US2692761A - Selective operating mechanism for air preheater by-passing dampers

Info

Publication number: US2692761A
Application number: US320536A
Authority: US
Inventors: Waitkns Joseph
Original assignee: Air Preheater Co Inc
Current assignee: Alstom Power Inc
Priority date: 1952-11-14
Filing date: 1952-11-14
Publication date: 1954-10-26
Anticipated expiration: 1971-10-26

Description

1 Oct. 26, 1954 Q J w n-Kus 2,692,761

SELECTIVE OPER NG MECHANISM FOR AIR PREHEATER -PASSING DAMPERS Filed Nov. 14, 1952 4 Sheets-Sheet 1 F I From forced To induced g- Draft Fan Draft Fun Air 1 Q 1 20 22 23 i f INVENTOR Joseph Wuitkus Oct. 26, 1954 w us 2,692,761

J. SELECTIVE OPERATING MECHANISM FOR AIR PREHEATER BY-PASSING DAMPERS Filed Nov. 14, 1952 4 Sheets-Sheet 2 Fig. 5.

NEY

Fig. 4.

' Oct. 26, 1954 J. WAITKUS 2,692,761 SELECTIVE OPERATING MECHAN FOR AIR PREHEATER BY-PASSING D ERS Filed Nov. 14, 1952 4 Sheets-Sheet 3 INVENTOR Joseph Woitkus Oct. 26, 1954 J. WAITKUS SELECTIVE OPERATING MECHANISM FOR AIR PREHEATER BY-PASSING DAMPERS Filed Nov. 14, 1952 4 Sheets-Sheet 4 Fig. IO.

ATT6BNEY Patented Oct. 26, 1954 SELECTIVE OPERATING DIEGHANISM FOR AIR PREHEATER -Bit-PASSING DAMPERS Joseph Waitkus, Wellsville, N. Y., assignor to The Air Preheater Corporation, New York, N. Y.

Application November 14, 1952, Serial No. 320,536

(01. ESL-6) 7 Claims.

The present invention relates to regenerative heat exchange apparatus of the rotary type and particularly to an improvement in dampers that control the lay-passing of one or both of the fluids that flow through the apparatus.

A regenerative heat exchanger of the rotary type comprises a rotor that carries heat transfer material, such as metal plates, that are first contacted by hot gases to absorb heat and are then moved to position in an air stream to impart the heat thereto. In the operation of such heat exchange apparatus it is sometimes necessary to by-pass part of the stream of air around the heat exchange material in the rotor, for example to avoid cooling the plates to a temperature that might induce corrosion of the plates or clogging of the spaces therebetween. In other situations it may be desirable to by-pass part of the stream of gases. Heretofore, by-pass dampers have been provided in the duct work associated with the gas or air sides of the preheater. Such by-passes involve the provision of additional by-pass duets with dampers therein in addition to the normal inlet and outlet ducts for the gas and air; which adds to the cost of the preheater.

The present invention contemplates the provision of by-pass dampers for either the gas or air passages of a rotary preheater with these by-passes built into the structure of the heater itself. The invention further provides for the selective and automatic operation of the dampers in the built-in by-passes so as to enable the by-passing of various amounts of gas or air.

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

Figure 1 is a sectional elevational view of a regenerative air preheater of the rotary type embodying built-in by-passes in accordance with the'present invention.

Figure 2 is a transverse sectional view as seen on the line 2-2 in Figure 4 showing the parts of the damper operating mechanism on the rotor and enclosing housing.

Figure 3 is a fragmentary view on an enlarged scale showing a portion of the preheater and illustrating the built-in by-pass dampers and operating means therefor.

Figure 4 is an elevational view as seen on line 4- 3 in Figure 3 and illustrates a single damper actuator in association with one of the operating stations. Figure 4a is a similar view illus- 2 trating the same damper in partially opened position.

Figure 5 is a vertical sectional elevation on line 55 of Figure 4 showing the component parts of the damper operating mechanism in operating relationship.

Figure 6 is a perspective vieW showing the damper operating mechanism at one station.

Figures 7 to 9 are schematic views showing the rotor in relation to an end plate and illustrating various fluid flow conditions; in Figure '7 all dampers are closed and there is no by-passing of either gas or air; in Figure 8 with all dampers opened there occurs a maximum lay-passing of air and gas, respectively; and in Figure 9 some of both the gas or air are by-passed, but not a maximum of either.

Figures 10a to 10 are developed or schematic views of the damper operating mechanism illustrating the several stages of operation as a damper opens and closes.

In Figure l the numeral Ill designates a cylindrical rotor comprising a circular shell l2 connected by radially extending partitions M (Figures 2 and 3) to a rotor post It: which is driven' by a motor it through reduction gearing. The rotor It is enclosedwithin a housing Hi provided with end plates 24], 2| that are formed with circumferentially spaced

apertures

22, 23 for the passage of streams of hot gas and the air to be heated to and through the rotor. Conventionally the rotor It] carries heat absorbing material in the wedge-shaped compartments formed between the radially extending partitions M; such material, for example, being in theiorm of metallic plates 24 spaced to form vertical passages through the rotor. In addition to the radial partitions l4 the rotor has circumierentially alined transverse partitions or diaphragms 28 which further subdivide the Wedge-shaped compartments into a series of chambers. Imperferate portions 21, 23 (Figures 7 to 9) between the gas and

air openings

22, 23 in the endv plates 24), 2| are engaged by radial seals (not shown) on the partitions Hi to preclude cross-flow of air to the gas passage while circumferential seals 29 (Figures 1 and 5) on the edges of rotor shell l2 engage parts ofthe

end plates

28, 2| to prevent by-passing of the rotor in through the annular space 3 1 between it and the housing 58.

In accordance with the present invention, the rotor I0 is filled with the heat transfer plates 24 except for the chambers 30 that form an annular band adjacent the shell l2 at the perimeter of the rotor. The chambers 30 in this outer band are utilized to form the gas and air bypasses around the rotor, or specifically around the heat transfer plates 24 carried in the other compartments, and dampers are provided to control the flow of by-passed gas or air through these by-pass chambers. Each of the chambers 30 is provided at one end, for example at the top or air inlet and .gas outlet ends thereof, with individual dampers 32 mounted for rotation about the horizontal axes that extend radially through the chambers centrally of the width thereof. The end portion of the shaft 33 for each damper projects outwardly through the rotor shell l2 into the space 34 between it and housing l8 and is provided with a pinion 35 by which the damper may be turned from open to closed position and vice versa. The shaft 33 also has a locking block 36 which maintains the damper in these extreme positions, as will be described later. On the inner wall of the housing plate Hi there are provided vertical guides 40 (Figures 4, '5 and 6) for a number of sliding supports 4| each of which carries a toothed rack segment 42 mounted in radial location for movement vertically into and out of position for engagement with any damper pinion 35 that registers therewith as the pinions traverse the circle of rotation with the rotor. A plurality of these rack assemblies are provided on the air side of the preheater at the circumferential location of the air passage 2-2. In the form chosen for illustration there are nine of these assemblies functioning for the eight chambers that may be disposed at any one time within the circumferential ambit of the air openings 22 of the

end plates

20, 2|. If desired the dampers may also be operated 'to create a gas by--pass and for this purpose the drawings show eleven stations on the gas side; at these and at the nine stations on the air side, the pinions '35 of the dampers may be momentarily engaged with the racks "42 to open or close dampers 32 for eight chambers on the air side-and ten on the gas side, there being one more operating station in each instance than the maximum number of chambers it is desired to expose at one time because both opening and closing operations are involved.

To maintain the dampers '35 in either open or closed position a locking rail 66 is mounted on the housing 18 and extends circumferentially around the rotor L in aipos'i'tion alined with the lockingb'locks 36 on the damper operating shafts 33 so as to-n'orma'lly engage these blocks as they move with the rotor 'andthus prevent'turning of shafts 33 thereby holding the dampers in closed or 'open position. The locking rails 48 include movable sections 4 8 provided at each damper operatingstation'and mounted on the slide blocks 4] along with the toothed gear segments 42 so that when one of the latter is moved down into position (Figure all for operating the dampers the related rail section 4'8 is moved down out of locking position 'to free the passing damper shaft 33 for rotation since the related locking block 36 can no longer contact the movable section 48 as it passes the station'of the latter because the section "48 has'been'retra'cted to provide room to turn the'blo'ck 36 and 'thus'it's shaft 33 and damper 32 also. Each slide block 42 is provided with an operating rod 5i! connected at one end to a pivoted operating lever "52 extendlng'throu'gh the rotor housin'gfor "operation from the exterior'of 'the 'preheater so th'atthe damper actuating mechanisms may be "selectively operated in various icombinations.

Assuming, for example, that less than maximum by-passing of air is desired; this involves the movement to open position of a number of the dampers associated with the eight chambers that may be exposed at one time to the air stream due to being included within the ambit of the air opening 22, but less than all of the eight at one time. in the diagrams of Figures 10a to 10) it is assumed that the air Joy-pass is to constitute six chambers of the eight possible; hence, as the chambers 30 enter the air passage all of the dampers 32 must be controlled so that six remain open atone time while the rotor ill traverses the air passage.

When it is determined (as by observation or automatic signal) that the position of the rotor I0 is such that all of the pinions 32 are located intermediate the stations of the racks t2 so as not to be engaged with or opposite the latter (Figure 10a), the rack segment 62B at the 2nd operating station on the air side is moved to effective position (downwardly in Figures 4 to 6 and 10) while at the same time the related movable locking rail section 48B follows this movement and becomes inoperative to engage the locking blocks 36 as they pass. .It will be noted in Figure 10a that having passed the 1st station the locking block 36A for damper 32A rides upon the fixed locking rail segment 46A and the pinion 35A is held against rotation. Observe that all of the locking blocks 35Q to 36X for all dampers shown in advance of 32A are in engagement with fixed segments of rail 46 and thus the related pinions and dampers are held against rotation.

When the adjacent movable locking rail section- 28B was rendered inoperative it was retracted to a position in which clearance was provided (Figure 4a) for permitting rotation-of the square locking block 35A along with the damper shaft 33 and dampertZ. In Figure 1% the pinion-38A may be seen to be engaged with the rack lia? and is being turned thereby to open damper 32A. Note also that for all dampers in advance of 32A which -is being turned by rack 4:25 the related racks 42C to #21 are :in the up position where they do not engage the pinions 35 and the latter and the related dampers are held against turning by the railsegmentslac to 481 engaging the blocks 36. Upon progressing-past the 2nd-station the locking block 36A engages the locking rail section 460 (Figure lilo) to retain the related damper 32A in open position.

In traveling past the-3rd,. 4-th,-5th,'6th and a'lth stations (the last four of which :are omitted to simplify Figure 10) where the racks 42 are ineffective-the locking block "3 3A en-gages the movable-rail sections -48C, Minute. (Ei-gures lilcand 10d) in crossing the spaces between fixed rail sections '43 so that the damper 32 A remains held in open position. When observation through :a Window in the housing It, or a suitable-signal, indicates that the pinion 5.43 for damper :32A is between the 'l'th and 8th stations Figure :iOcZ) the rack 42H at the latter station is moved to effective position and the rail section 43H out of locking .relation. At this time the pinions 35B to for five dampers "following 35A for the damper 32A have been actuated in turn upon passing and engaging the-rack 42B .at the 12nd station.

Upon reaching the 8th station where (the-rack 42H has been lowered to effective positiontthe pinion 35A is engaged (Figure .106) turning the damper 32A rough a half revolution in the same direction as at the 2nd station and the damper 32Anow closes. When the rotor turns to carry pinion 35A beyond the 8th station its locking block engages fixed rail segment 46H (Figure 10f) and is held in closed position. As the rotor continues to turn the damper 32A will remain closed as its chamber to passes the imperforate part 2'5 of the end plate that separates air passage 22 from gas passage 23, which last it traverses in closed position (provided no stations on the gas side are rendered operative) and it eventually returns to the air passage. The 1st station therein is passed without incident but at the 2nd station the rack 4213 again opens the damper 32A and dampers 3213 to 32H.

As the rotor turns, the pinions 35 associated with each of the dampers 32 for the various chambers of the rotor becomes engaged in turn with the operative 2nd gear rack c213 and riding along the rack is turned between

stations

2 and 3 to move the related damper from closed to open position. As each pinion 35, carried along with the rotor Ill, moves beyond the effective station the related locking block 36 again engages the locking rail 46 in section %C and the pinion cannot be turned to move the damper. Inasmuch as partial by-passing is desired, all of the racks at other stations between the 2nd and 8th remain inoperative. At the 8th station the rack segment hEH (Figure 10d) is moved into operative position just before the first damper to be opened reaches it so that as various pinions 35 pass by they will be engaged (Figure lile) and turned to rotate their dampers back to closed position. In the meantime because the intermediate operating stations and their apparatus are inoperative, the dampers for six of the eight of the chambers confronting the air openings in the end plates are in open position as the chambers traverse the air passage so that air is bypassed through six chambers at one time (Figure 9). In the example given, six dampers are opened in succession providing the cross-sectional area afforded by six chambers for the flow of air around the rotor. As the seventh, eighth, ninth, tenth and other dampers open, the first, second, etc., close. When the gas pass is reached the dampers stay closed, unless stations there are put into operation, and on full rotation of the rotor the first damper opens again as the cycle repeats.

It is possible to open the chamber dampers as they become alined with the air passage and then close them upon leaving the latter thus providing a full by-pass of eight chambers (Figure 8). Any lesser number may be operated generally as described above. With all racks d2 inoperative all dampers are closed so there is no by-passing of air or of gas (Figure '7). Partial by-passing is brought about for example by moving the rack 42A at the first station into operating relation and if it is desired to have four or five chambers, counting from the leading edge of the air aperture in open position, then the racks 42E, 12E at the fifth or sixth stations are rendered effective to close the dampers as they pass. The intermediate racks have no effect upon the dampers because they are up out of position for engagement by the pinions and the dampers remain open because of engagement of the locking blocks 36 with the locking rail at as they pass through the intermediate stations. The same is true of the dampers as they pass stations beyond the fifth or sixth because these operating

racks

42G, 42H, 421 are out of action and thus the dampers, having been opened as they enter the air passage operating position to and closed in passing the remain closed in traversing air passage. It is also possible to have some of the dampers adjacent either the leading or trailing edges of the air passage closed; that is to say, that dampers are opened when the chambers become alined, for example, with the central pore tion of the air passage. This is done for exam ple by rendering the first two racks MA, 423,

inoperative while moving the rack 32C at the.

third station into position to open the dampers. When three chambers are to constitute the bypass, the third following station is rendered effective by movement of its rack (e. g. t2?) to close the dampers as the pinions engage the rack in passing by. Thus, any

number of chambers may be utilized to constitute the by-pass. Further, the location which the bypass assumes between the extreme circumferential margins of the air aperture is determined by the selective operation of racks at corresponding stations.

The operation of dampers to provide a maximum or partial by-pass for gas is exactly the same as for air and is effected by means of operating mechanism in stations adjacent the gas apertures 23 of the end plates 29, 2 l. When both air and gas by-pass arrangements are installed, the chamber dampers opening upon alinement with the air passage and, closing before or when leaving the latter, would remain closed until again alined with the air passage; provided the mechanisms on the gas side of the apparatus remain completely inoperative. However, if some gas also is to be by-passed, the dampers having closed on exiting from the air passage open again upon entering the gas passage, or at a desired location therein, and subsequently close on exiting from the gas pass to be again opened when in the operating cycle they return to the air passage. It is deemed unnecessary to attempt to describe all possible operating combinations because the general manner of operation will be apparent from the foregoing examples.

It will be seen that the by-pass is built into the preheater itself. The arrangement also provides great flexibility in allowing various volumes of air or gas to be by-passed due to the selective operation of the dampers for a number of rotor chambers which constitute a large or small bypass or as desired.

What I claim is:

1. In apparatus having a cylindrical rotor divided by radial partitions into a plurality of wedge shaped compartments for carrying material to be subjected to contact by gaseous fluids; circumferentially aligned transverse partitions in each of said compartments forming similarly located chambers spaced in an annular band around the rotor; a housing surrounding the rotor and provided with end plates formed with aligned circumferentially spaced openings for the separated flow of said fluids to and through the rotor; individual dampers adjustable between open and closed positions for controlling fluid flow through said chambers; operating means connected to and carried by said dampers for moving them from open to closed position and vice versa; and stationary means fixedly mounted on the housing in circumferentially spaced relation around the rotor for actuating said operating means to selectively open and close said dampers.

2. In an air preheater having a cylindrical rotor divided by radial partitions into a plurality of wedge-shaped compartments for carrying heat fourth or fifth station, the remainder of the accavcr transfer material to be subjected to contact by heating gases and air or-other fluid to be heated; circumferentially aligned transverse "partitions in each of said compartments segregating from said compartments a number of chambers spaced around the rotor and disposed in corresponding locations in said compartments; a housing surrounding the rotor and provided with end plates formed with aligned circumferentially spaced openings for the separate flow of a heating gas and air to be heated to and through the rotor: individual dampers adjacent the inner periphery of the rotor shell adjustable between open and closed positions for controlling fluid flow through said chambers; operating means connected to and carried by said dampers -for moving them from open to closed position and vice versa; and stationary means fixedly mounted on the housing in circ-u feren'tially spaced relation around the rotor for actuating said operating :means to selectively open and close said dampers.

3. Damper control apparatus as recited in claim 2 wherein each damper is mounted for rotation with a shaft extending axially of said chamber and projecting'at one end into the space between the rotor and housing; a pinion fixed to said end of said shaft; toothed racks engageab'le with said pinion mounted on the inner -1z eri-phery of the housing between-1 said rotor and housing in predetermined spaced relation circumferentially of the rotor in locations opposite the air and gas openings; and individual means for moving said racks into position for engagement by said pinion, sai means being selectively operable to cause successive opening and closing movements of the related damper in predetermined circumferential positions taken up by-eac'hcha-m- 8 her during turning of the rotor through the arc" opposite one of said openings.

4. Damper operating apparatus as recited in claim 3 wherein locking means are provided for positions.

'5.'Da1nper operating apparatus as recited in claim 4 wherein means are provided for releasing the locking means for each damper prior to engagement of the related pinion with racks selectively operated to open and close said damper.

6. Damper operating apparatus as recited in claim 5 wherein said locking means include; a locking block mounted adjacent the pinion on the shaft of each damper; an arcuate stationary locking rail positioned to normally engage all said blocks during turning of the rotor so as to prevent operation of said dampers; and movable sections included ineach rail axially aligned with said pinion operating racks and movable to posi tions to interrupt the arcuate continuity of said rail so as to unlock each pinion for operation -by a rack that has been selectively adjusted to actuate the damper operating means.

7'. Damper operating means as recited in claim 6 wherein said movable rail-sections are moved to unlocking positions simultaneously with the movement 'of related racks to operative position.

References Cited the file of this patent UNITED STATES PATENTS