US2471995A

US2471995A - Adjustable circumferential seal for preheaters

Info

Publication number: US2471995A
Application number: US770086A
Authority: US
Inventors: William D Yerrick; John C Vickland
Original assignee: Air Preheater Co Inc
Current assignee: Alstom Power Inc
Priority date: 1947-08-22
Filing date: 1947-08-22
Publication date: 1949-05-31
Anticipated expiration: 1966-05-31

Description

EXAMINER May 31, 1949. w. D. YERRICK ETAL ADJUSTABLE CIRCUMFERENTIAL SEAL FOR PREHEATERS Filed Aug. 22, 1947 2 Sheets-Sheet 2 INVENTOR.

012 Yerrm Jada 6 l ri/wrd Patented May 31, 1949 UNITED STATES PATENT OFFICE ADJUSTABLE CIRCUMFERENTIAL SEAL FOR PREHEATERS Application August 22, 1947, Serial No. 770,086

11 Claims. 1

The present invention relates to heat exchangers and particularly to improved circumferential seals for use between the rotor and enclosing housing of rotary regenerative air preheaters or like apparatus.

In a rotary regenerative heater of the Ljungstrom type a cylindrical rotor has compartments carrying metallic heat transfer plates which that as the rotor turns are first exposed to the heating gases and then disposed in the air passage to impart the absorbed heat to the air. The rotor is surrounded by a housing having end or sector plates formed with openings to provide for the flow of gas and air and in order to preclude the flow of gas or air through the clearance space between the rotor and housing without passing over the heat transfer material it is customary to provide the rotor with circumferential seals that bear against the sector plates or other stationary parts,

The present invention contemplates improved circumferential sealing devices of novel forms which will best be understood upon consideration of the following detailed description of several illustrative embodiments thereof when read in conjunction with the accompanying drawings in which:

Figure 1 is a sectional elevational view in diagrammatic form of a rotary regenerative air preheater embodying the present invention;

Figure 2 is a plan view corresponding to Figure 1;

Figures 3 and 4 are enlarged sectional elevational views showing the detailed construction of components of two types of the sealing devices;

Figure 5 is an enlarged fragmentary plan view showing the relation between the parts of the circumferential seal that are carried respectively between the rotor and the housing; and

Figure 6 is an elevational view corresponding to Figures 4 and 5 as viewed on the line 8-6 in the former figure.

In the drawings the numeral l designates the cylindrical shell of a rotor which is divided into sector shaped compartments by radial partitions ll connecting it with the rotor post 12 which is driven by a motor and reduction gearing l3 to turn the rotor slowly about its axis. The rotor compartments contain regenerative heat transfer material in the form of metallic plates ll which first absorb heat from hot gases entering the preheater through a duct l from a boiler or other source to be discharged after passing over the heat transfer plates I! through an outlet duct It to which an induced draft fan (not shown) is connected. As the rotor turns slowly about its axis, the heated plates H are moved into the stream of air admitted through the duct l'l to which a forced draft fan (not shown) is connected. After passing over the plates l4 and absorbing heat therefrom the stream of air is conveyed to the boiler furnace or other place of use through duct I8. A housing 20 enclosing the rotor I0 is provided at either end opposite the latter with end or sector plates 2| which are apertured at 22 and 23 to permit streams of gas and air to enter and leave the preheater.

In order that the streams of gas and air may not by-pass the heat transfer surface H by flowing in the annular clearance space 24 between the rotor shell l0 and the housing 20 it is customary to provide circumferential seals on the shell ll which wipe against the sector plates 2| or allied parts so as to seal ofi the space 24 at both ends of the rotor. In accordance with the present invention the rotor is provided at or close to each edge thereof with a metalligsealing ring--25 (Figures 3 and 4) boltem the outer face of the rotor shell l0. These circumferential sealing rings at the top and bottom edges of the rotor are preferably made up of a number of segmental sections 25A (Fig. 5) which are bevelled or rabbeted at their ends so as to overlap and form a, complete ring w e maintaining a. lateral seal between segments. They are made up of chrome plated metallic strips of arcuate form short enough to pass through an access port 26 (Fig. 2) located in the rotor housing so that they may be installed initially and removed for replacement from the exterior of the preheater. Bearing against these sealing rings that move with the rotor are other stationary sealing strips or shoes 21 of alloy material which are also segmental in form (Fig. 5) and bear also against the sector plate 2| or an annular ring 28 attached thereto adjacent the end flange 29.

In the form shown in Figure 3 each sealing shoe 21 is pressed against the sealing ring 25 on the rotor and also against the surface 30 on the annulus 28 attached to the underside of a sector plate at the end of the housing 20 by a spring loaded pin 3| projecting through a mounting plate 32 therefor attached to the housing 20 and bearing at 38 against the shoes 21. The compression and hence the force of the springs 38 may be adjusted by means of cap nuts 34 threadedly engaging the pin guide 35. These segments 21 also may be mounted or removed through the access port 28 (Fig. 2). A spring loaded pin 3| is provided for each of the individual segmental shoe sections 21 that make up a stationary seal ing ring that encircles and bears against the ring 25 that travels with the rotor. The shoes 21 are provided with pockets 39 in which the ends of the spring loaded pins 3| seat with their ends in contact with the bases 38 of pockets 39. Pocket 39 also serves to prevent sealing shoes 21 from turning with the rotor in either direction while under friction load.

When a sealing shoe 21 is to be installed, the cap nuts 34 are backed off to release the sp g pressure on the pin 3| and the latter are partially retracted. The rotor is turned until the required circumferential portion thereof opposite which the shoe is to be stationed is in alinement with the access port 26. The sealing shoe 21 is then inserted through the port 26 and temporarily attached to the rotor by a bolt extending through a bolt hole 36 in the shoe and into a threaded bolt hole 31 in the rotor sealing ring 25. The rotor may then be turned and successive shoes of what is to be the stationary ring mounted thereon. The cap nuts 34 may then be turned down to bring the spring loaded pins 3| into the pockets 39 in contact with surfaces 38 of the shoe sections 21. Upon opening the doors of other access ports 40 adjacent each pin 3| and in alinement with the location of the bolts holding the segment shoes 21 to the rotor the bolts may be removed so that the shoes 21 become independent of the rotor. The shoes 21 at the top edge of the rotor are now supported by their pins 3| while those at the bottom rest on the sector plate ring 28. The cap nuts 34 may then be turned down further to provide the desired pressure with which the shoes 21 are individually held against the wear surface 4| of the rotor sealing ring 25 and the wear surface 30 in the sector plate or housing.

When it is desired to remove a shoe which appears to have worn in the form of Fig. 3, one follows the reverse of the procedure of installation as described in the preceding paragraph.

In the form shown in Figure 4 the sealing face of each shoe 21 is pressed against the rotor ring 25 by lever 42 having its upper end 43 bearing against the surface 48 on shoe 21 and its lower end connected by a link and pivot to a rod 44 which is under the action of a spring 45 mounted between a washer 46 thereon and an adjustable nut or wheel 41 threaded to the rod.

As appears in Figure 6 the lower end of lever 42 is offset and its pivot shaft 50 is journalled in the side walls 52 of a cup-like depression 53 in the face of mounting plate 54 for the lever and related parts. To mount the plates or housings 54, openings are formed at intervals circumferentially of the rotor housing. The lever 42 is mounted behind plate 54 and attached to the outer end of its pivot pin 50 so that a simple journal packing 55 prevents leakage. This avoids the complications that would he introduced if the lever 42 were extended through an elongated slot the end wall 55 of the depression 53. Plate 54 has an extension 51 which provides a shelflike support 58 for the sealing shoe 21 when the latter is located at the top edge of the rotor. Shelf 58 of extension 51 also serves to prevent shoes 21 from turning with the rotor in either direction while under friction load by means of lugs on shoes 21. These lugs are indicated in Figure 6. The plate 54 is mounted by bolts 60 extending through elongated apertures 6| therein into tapped holes 62 in the housing 20 so that the 4 plates 54 with shelves 58 and hence the shoes 21 may be vertically adjusted from the exterior of the housing.

When the preheater is in operation the rotor l0 carries with it the segments 25A that make up the sealing ring 25 which as the rotor turns wipe against the stationary sealing shoes 21 that are pressed against the sealing rings on the rotor through the action of the springs 33 (Fig. 3) or 45 (Fig. 4).

The sealing arrangements described above provide more efiicient circumferential sealing devices for the rotors and housings of heat exchange apparatus of this type for high temperature and high pressure use. The stationary sealing shoes are free tamggjnward agdcutward to accommodate changes in rotor diameter'due to expansion and contraction when the rotor is in service. They also may be individually adjusted to afford the desired sealing contact. The sealing segments may readily be removed and replaced from the exterior of the heater. All these segments may further be adjusted from the exterior of the heater while it is in operation.

What we claim is:

1. In a regenerative air preheater or the like having a rotor made up of a cylindrical shell joined to a rotor post by radial partitions forming compartments that carry heat transfer material, and a housing surrounding the rotor and provided opposite the ends of the latter with sector plates formed with apertures for the flow of heating gases and air to and through the rotor; a sealing ring mounted on the outer surface of the rotor shell at or closely adjacent each end edge thereof groups of sealing shoes of arcuate form mounted in the housing outwardly of the rotor shell close to said sector plate, the shoes of each group together forming a stationary sealing ring of circular shape disposed opposite one of the sealing rings on the rotor; and spring biased means engaging said arcuate shoes and acting to maintain them in contact with the sealing rings carried by the rotor and with the adjacent portions of said sector plates.

2. Circumferential sealing means as recited in claim 1 wherein the sealing rings on the rotor are made up of separable arcuate segments individually fastened to the rotor and the side wall of the housing is provided with normally closed access opening large enough to permit withdrawal of a segment.

3. Circumferential sealing means as recited in claim 1 wherein the individual stationary arcuate shoes are provided with bolt holes alignable with corresponding bolt holes in the rotor whereby a stationary shoe may temporarily be attached to the rotor by a bolt to be carried to its station on turning the rotor; and individual access doors for said stationary sealing shoes located at their stations and through which the bolts for attaching a shoe to the rotor may be withdrawn.

4. Circumferential sealing means as recited in claim 1 wherein adjustable means individual to each sealing shoe are provided for regulating the force applied by said spring means in maintaining the respective shoes in contact with said sealing rings and sector plates.

5. Circumferential sealing means as recited in claim 4 wherein said adjusting means for each arcuate shoe project through the side wall of the housing to permit regulation from the exterior of the preheater.

6. Circumferential sealing means as recited in claim 1 wherein an individual spring pressed pin EXAMINER or plunger maintains each sealing shoe in contact with the adjacent sealing ring and sector plate.

7. Circumferential sealing means as recited in claim 1 wherein each sealing shoe is engaged by a pivoted lever acted on by a spring to maintain the shoes in contact with said sealing rings.

8. Circumferential sealing means as recited in claim 1 wherein each arcuate sealing shoe is mounted between the adjacent sector plate and a member vertically adjustable in the side wall of said housing.

9. Circumferential sealing means as recited in claim 8 wherein the spring biased lever for each sealing shoe is carried by said member.

10. In regenerative apparatus having a rotor that carries material to be contacted by gaseous fluids, and a housing surrounding the rotor and provided with inlets and outlets for admitting fluids for circulation through the rotor, the rotor and housing constituting moving and stationary parts respectively; cooperating fluid seals mounted between the rotor and housing adjacent said inlets and outlets for confining the flow of fluids topaths through the rotor and obviating flow in the space between the rotor and housing comprising; a ring providing a smooth sealing surface on one of said parts; a plurality of sealing shoes of sector shape together forming an annular sealing member mounted on the other of said parts in. a position opposite the sealing surface on said first part; and means for biasing said shoes toward and maintaining them in sealing contact with said ring.

11. In regenerative apparatus having a rotor that carries material to be contacted by gaseous fluids, and a housing surrounding the rotor and provided with inlet and outlet connections for admitting fluids for circulation through the rotor, cooperating fluid seals mounted between the rotor and housing adjacent said connections for confining the flow of fluids to paths through the rotor and obviating flow in the space between the rotor and housing comprising; a metallic ring providing a smooth sealing surface on said rotor; a plurality of metallic sealing shoes of sector shape together forming an annular sealing member supported in the housing in a position opposite the sealing surface of the ring on said rotor; and means for applying variable pressure to said shoes in directions for maintaining them in sealing contact with said ring.

WILLIAM D. YERRICK. JOHN C. VICKLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,652 025 Ljungstrom Dec. 6, 1927 7 2,347,829 Karlsson et al May 2, 1944 FOREIGN PATENTS Number Country Date 460,703 Germany Dec. 13, 1925 500,682 Great Britain Feb. 14, 1939