US3385605A - Wall box seal assembly - Google Patents

Description

T. J. HYLBERT ETAL WALL BOX SEAL ASSEMBLY Filed April 4, 1966 3 Sheets-Sheet y 1968 'r. J. HYLBERT ETAL 3,385,605

WALL BOX SEAL ASSEMBLY 3 Sheets-Sheet 2 Filed April 4, 1966 y 1968 T. J. HYLBER T ETAL 3,385,605

WALL BOX SEAL ASSEMBLY 3 Sheets-Sheet 3 Filed April 4} 1 966 7%077r4s J? 2 :54

United States Patent 3,385,605 WALL BOX SEAL ASSEMBLY Thomas J. Hylbert and John E. Clark, Lancaster, Ohio, assignors to Diamond Power Specialty Corporation, a corporation of Ohio Filed Apr. 4, 1966, Ser. No. 539,964 7 Claims. (til. 27770) ABSTRACT (PF THE DISCLOSURE A wall box sealing assembly for an opening in the wall of a heat exchanger apparatus consisting of a housing with longitudinally spaced apart end walls and a collar through which a tubular element is adapted to extend disposed in sealing sliding relationship between the end walls and formed with air nozzles therethrough for discharging a pressurized fluid supplied to the chamber around the periphery of the tubular element and toward the interior of the heat exchanger apparatus.

The present invention broadly relates to sealing devices and more particularly to an improved sealing device adapted for use in the walls of positive-pressure heat exchanger apparatus. More specifically, the present invention is directed to an improved wall box sealing assembly of the type adapted to accommodate the lance tube of boiler cleaning apparatus such as retractable soot blowers or the like.

In order to maintain optimum thermal efficiency of modern high capacity steam boilers, it is necessary to provide a plurality of cleaning apparatuses or soot blowers, as they are conventionally referred to, which are mounted exteriorly of the walls of the boiler and which are adapted to be periodically actuated for effecting a removal of soot, slag or other extraneous deposits from the heat exchanger surfaces. Soot blower apparatuses conventionally employed for such purposes comprise a retractable lance tube which is formed in the forward end portion thereof with one or more nozzles through which a pressurized cleaning medium such as steam or air, for example, is dis charged and is effective upon impingement on the heat exchanger surfaces to effect a dislodgement of the slag deposits thereon. The lance tubes of such soot blowers during the period between cleaning cycles are normally disposed in an inoperative or retracted position in which the nozzle end portion thereof is retracted within the wall box so as to shield the lance tube from the hot combustion gases within the interior of the boiler. During the initiation of a cleaning cycle, the lance tube is projected from the inoperative position into the interior of the heat exchanger apparatus and conventionally is rotated during its translatory movement whereby the cleaning medium is discharged from the nozzles in the form of a helical blowing pattern.

Due to the increased size of modern high-capacity steam boilers, a substantial increase has occurred in the length of the lance tubes of long retracting type soot blowers in order to provide adequate coverage of the heat exchanger surfaces. Lance tubes of such increased length have been found to deflect due to the gravitational forces imposed thereon such that alignment problems are encountered between the peripheral surface of the lance tube and the wall box assembly through which the lance tube passes in Patented May 28, 1968 aligned relationship therewith. The lance tube deflection has accordingly occasioned a problem of providing adequate sealing of the lance tube within the wall box to prevent inadvertent escape of the hot combustion gases from the interior of the boiler to the surrounding atmosphere.

In addition, wall box assemblies of the types heretofore known are of a rather cumbersome construction comprising a plurality of individual assembled components and conventionally incorporate two chambers formed with nozzles for alternatively discharging a sealing air when the lance tube is disposed in the wall box and an aspirating air for sealing the wall box when the lance tube is removed during periodic service of the soot blower. There has, accordingly, been a long felt heretofore unfilled need for an improved wall box seal assembly which is of a substantially simpler construction and which provides adequate sealing of the lance tube and the wall box in spite of the deflection of the lance tube during the course of its travel into and out of the interior of 'a heat exchanger apparatus.

Accordingly, the principal object of the present invention is to provide an improved wall box seal assembly which overcomes the problems and disadvantages associated with wall box assemblies of the types heretofore known.

Another object of the present invention is to provide an improved wall box assembly incorporating a floating seal member which is adapted to move and compensate for movement of the lance tube as the result of the deilection thereof during the course of its projecting and retracting travel maintaining an appropriate seal during all moved positions of the lance tube thereby preventing the escape of hot combustion gases from the interior of the boiler.

Still another object of the present invention is to provide an improved wall box seal assembly which incorporates only one chamber and a series of nozzles in communication therewith which serves to both seal the lance tube when the soot blower is mounted in the wall port as well as sealing the wall port by discharging a high pressure aspirator air at such times that the lance tube is removed from the Wall box.

A further object of the present invention is to provide an improved wall box seal assembly which is of a simple and compact construction, which consists of a minimum of individual assemblable components thereby greatly facilitating service and maintenance thereof, which incorporates a floating seal assembly greatly facilitating alignment between the seal assembly and the lance tube, and which is of simple and economical manufacture and installation.

The foregoing and other objects and advantages of the present invention are achieved by a wall box seal assembly comprising a hollow housing including a pair of spaced-apart end walls formed with axially aligned ports therethrough for receiving a tubular cleaning element such as a lance tube which is adapted to extend therethrough. A plate is disposed in slidable overlying relationship against the inner surface of the rearward one of the end walls and is formed with an aperture therethrough defining an annular edge adapted to be disposed in sliding sealing relationship around the lance tube. A collar which includes an annular wall preferably of a tapered construction and having a diameter at its forward end portion to encircle the lance tube is disposed between the plate and the inner surface of the other end wall in floating and sliding sealing relationship therebetween. The collar in combination with the plate and the housing define a chamber which is adapted to encircle the lance tube to which a pressurized fluid such as air, for example, is supplied and which in turn is discharged through a plurality of nozzles or ports disposed in circumferentially spaced relationship around the annular wall of the collar and is adapted to be discharged forwardly between the clearance gap formed by the collar and the lance tube. At such times when the lance tube is withdrawn from the wall port for periodic service and inspection, a higher pressure air is adapted to be supplied to the chamber which in turn is discharged in the form of a conical pattern forming an air screen or shield to prevent escape of combustion gases through the wall port to the exterior of the heat exchanger apparatus. It will also be understood that while the wall box seal assembly is described with particular applicability to soot blower apparatus, the present invention is equally applicable for sealing any one of a variety of cylindrical probes or cleaning elements which are adapted to be periodically inserted within the interior of a heat exchanger apparatus.

Other objects and advantages of the present invention will become apparent upon a reading of the following description taken in conjunction with the following drawings, wherein:

FIGURE 1 is a fragmentary side elevational view partly in section and partly in schematic illustrating a wall box seal assembly constructed in accordance with the preferred embodiments of the present invention mounted exteriorly of a wall of a furnace;

FIG. 2 is an enlarged longitudinal vertical sectional view of the wall box seal assembly as shown in FIG- URE 1;

FIG. 3 is an end elevational view of the outermost or rearward end of the wall box seal assembly shown in FIGURE 1;

FIG. 4 is a elevational view of the inner or forward end of the wall box seal assembly shown in FIGURE 1, and

FIG. 5 is a transverse vertical sectional view of the annular collar movably mounted within the wall box seal assembly as shown in FIGURE 2 and taken along the line 5-5 thereof.

Referring now in detail to the drawings and as may be best seen in FIGURE 1, a typical installation of a wall box seal assembly is illustrated including a furnace wall having water wall tubes 12 mounted along the inner combustion side thereof and formed with a port or opening 14 in which a sleeve 16 is mounted. A housing 18 is rigidly secured such as by means of welding to the outer or rearward end of the sleeve 16 and through which a lance tube indicated at 20 is adapted to extend. The lance tube 20, as shown in FIGURE 1, is in the inoperative or retracted position wherein a nozzle 22 in the forward end portion thereof through which a suitable blowing media is adapted to be discharged during a cleaning cycle is disposed within the protective confines of the housing 18. In this way, the lance tube and the nozzle therein are shielded from the hot combustion gases and radiant heat present within the interior of the furnace.

The housing 18 as best seen in FIGURES 1 and 2, is of a generally circular configuration and is formed as shown in FIGURE 3 with a pair of bosses 24 on the sides thereof in which pivot pins 26 (FIGURE 1) are adapted to be disposed for pivotally securing the forward sup porting framework of a soot blower indicated in phantom at 28 in FIGURE 1, whereby the lance tube 20 is maintained in appropriate axial alignment with the wall port. The housing 18 is formed along its lower portion with a threaded aperture 30, as best seen in FIGURE 2, into which a suitable supply pipe 32, as shown in FIGURE 1,

is adapted to be connected for supplying a pressurized fluid to the interior of the housing.

The forward end portion or right hand side of the housing, as viewed in FIGURE 2, is formed with an inwardly extending end wall 34 having a port 36 therethrough which is of a size so as to provide for clearance between the edges thereof and the periphery of the lance tube 20. The lance tube 20 is shown in phantom in FIG- URE 2 in a horizontal position as well as in a typical angularly deflected position. The inner surface of the end wall 34 is preferably provided with an annular land 38 having a smoothly machined inner surface 40 which is adapted to be disposed in bearing sliding relationship against a forward surface 42 of an annular collar 44. To the rear or outer end portion of the housing 18, an annular cover plate 46 is removably secured such as by means of screws 48. A gasket 50 is disposed between the inner surface of the cover plate and the rearward edge of the housing 18 so as to form a substantially fluid-tight seal therebetween. The cover plate 46 is provided with a port 52 therethrough which is disposed in substantial axial alignment with the port 36 through the forward end wall of the housing and which is of a size substantially greater than the diameter of the lance tube adapted to extend therethrough. The inner surface of the cover plate 46 is preferably formed with an annular land 54 having a smooth machined flat surface 56 against which the outer surface of a seal plate 58 is adapted to be disposed in sliding relationship.

The seal plate 58 is formed with an aperture 60 therethrough which is of a size slightly in excess of the diameter of a lance tube adapted to extend therethrough. The outer surface of the seal plate 58 is formed with an annular groove indicated at 62 which is adapted to receive an annular rib 64 of a seal ring 66 removably secured to the seal plate 58 by means of socket head screws 68. The seal ring 66 is formed with an annular rounded sealing edge 70 which is adapted to be disposed in close sliding and sealing relationship around the periphery of the lance tube 20. In accordance with a preferred embodiment of the present invention, the seal ring 66, as may be best seen in FIGURES 2 and 3, is comprised of a pair of semicircular segments which are adapted to be mounted on the seal plate 58 such that the adjacent ends 71 thereof are disposed in close substantial abutting relationship relative to each other defining therewith a substantially continuous annular sealing edge 70. The foregoing arrangement enables the seal ring 66 to be removed and replaced at such times as it becomes worn to an extent where an excessive escape of pressurized air passes between the sealing edge 70 and the periphery of the lance tube extending therethrough.

The annular collar 44, as best seen in FIGURES 2 and 5, is formed with an annular conically forwardly directed wall 72 which terminates at its forward end and defines a bore or sealing edge 74 of a diameter so as to sealingly encircle the periphery of the lance tube. The outer or rearward end of the annular wall 72 is provided with a smooth surface finish indicated at 76 which is adapted to be disposed in sliding sealing relationship against the inner surface of the seal plate 58.

A plurality of apertures extend through the annular wall 72 of the collar 44 and are disposed at substantially equal circumferentially spaced increments therearound, forming thereby a plurality of anularly oriented nozzles 78. The angular inclination of the nozzles 78 are arranged so as to converge at a point corresponding substantially to the longitudinal axis of the bore through the collar at a point spaced forwardly therefrom as generally indicated at 80 in FIGURE 2.

In accordance with the foregoing arrangement, it will be apparent that the housing in combination with the cover plate 46, seal plate 58, seal ring 66, and annular collar 44 defines an internal chamber 82 which is adapted to encircle the lance tube extending through the Wall box seal assembly. The pressurized fluid supplied through the supply pipe 32 to the interior of the chamber 82 serves to force the outer or rearward-most surface of the seal plate 58 against the flat surface 56 of the annular land 54 maintaining a substantially fluid-tight seal therebetween. At the same time, the fluid pressure within the chamber tends to force the forward surface 42 of the annular collar 44 against the seal surface 40 of the annular land 38, forming a substantially fluid-tight seal therebetween. Accordingly, the relatively close tolerance fit between the rearward end surface 76 of the collar and the inner surface of the seal plate, which is of a magnitude to permit relative sliding movement therebetween, produces a substantially fluid-tight seal thereby directing substantially all of the pressurized fluid out through the nozzles 78 and around the periphery of the lance tube. The pressurized air disposed between the sealing edge 70 of the seal ring 66 and the sealing edge 74 of the collar 44 is controlled so as to be at a pressure greater than that of the pressure within the interior of the furnace thereby preventing escape of the combustion gases from the interior of the furnace out through the wall box. The pressurized fluid discharged through the nozzle 78 escapes between the sealing edge 74 into the interior of the furnace while a portion thereof also escapes between the periphery of the lance tube and the annular sealing edge 70 to the surrounding atmosphere. When the lance tube is in the fully retracted position, as typified by the position shown in FIGURE 1, the pressurized sealing air also serves to cool the nozzle 22 of the lance tube and to prevent the fouling thereof by any combustion deposits coming in contact therewith.

When the lance tube is completely withdrawn from the wall box seal assembly during scheduled service or maintenance of the soot blower, a higher pressure fluid is discharged into the chamber 82 whereupon a conical air stream or shield is formed by the discharge of the air through the nozzle 78 preventing any escape of hot combustion gases out through the open wall box. For this purpose, a low pressure compressor 84 has been schematically illustrated in FIGURE 1, which is connected through a valve 86 to a suitable header 88 which in turn is connected to the supply pipe 32. Similarly, a highpressure compressor 90 is connected through a suitable valve 92 to the header 88 for supplying a higher pressure aspirator air as may be required at such times that the lance tube is withdrawn from the wall port. Alternative suitable mechanisms, such as pressure reducing valves or the like, can be employed for supplying a lowpressure sealing air to the chamber 82, as well as a higher pressure aspirator air in a manner well known in the art.

It will be apparent from the foregoing that a substantial simplification is provided in the construction and servicing of the Wall box assembly comprising the present invention. By virtue of employing the nozzles 78 in the annular collar for both sealing purposes, as well as aspirating purposes, the likelihood of fouling or plugging thereof by extraneous deposits from the combustion chamber is materially reduced as is encountered in other wall box assemblies having two sets of nozzles which are alternately employed and are susceptible to such fouling during periods of non-use. It will also be apparent that by virtue of the construction of the housing, the annular collar 44 and the seal plate and seal ring can be readily interchanged by a simple removal of the cover plate 46 in order to adapt the wall box assembly for accommodating lance tubes of differing diameters. The free, independent movement of the annular collar and of the seal plate also enables self-independent alignment of these two components with the lance tube as is occasioned by a deflection thereof during its movement to and from the projected positions thereby assuring a uniform sealing thereof in all moved positions of the lance tube. Appropriate vertical and lateral shifting movement of the seal plate and of the annular collar is simply achieved in response to the sliding coaction between these components and the periphery of the lance tube extending therethrough. The independent self-aligning characteristics of the seal plate and the annular collar assures continuous sealing of the lance tube within the Wall box assembly and without encountering any binding or any excessive bearing pressures which would otherwise occasion rapid wear of the components disposed in sliding contact therewith.

In accordance with a preferred embodiment of the present invention, in order to provide for still further latitude of the angular deflection of the lance tube, the sleeve 16 extending into the furnace wall is of a generally elliptical configuration as is best seen in FIGURE 4. This elliptical configuration of the sleeve, in combination with the self-aligning characteristics of the seal assembly, enables the use of various different lance tube deflection compensating devices for providing a substantially linear travel of the nozzle end of the lance tube while assuring continuity of the sealing characteristics of the Wall box and avoidance of any physical or mechanical interference therebetween.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A wall box seal assembly adapted for mounting on a port of a heat exchanger apparatus for providing access for a tubular element into the interior thereof comprising a hollow housing including a pair of spacedapart end walls formed with axially aligned ports therethrough, a plate slidably overlying the inner surface of the rearward one of said end walls and formed with an aperture therethrough defining an annular edge adapted to be disposed in sliding sealing relationship around a tubular element, a collar including an annular Wall having a diameter at its forward portion to sealingly encircle a tubular element and being of an enlarged diameter rearwardly thereof defining an annular chamber around a tubular element, said annular wall disposed with the rearward end thereof in sliding sealing relationship against said plate and with the forward end thereof in sliding sealing relationship against the inner surface of the other of said end walls, said collar, said plate and said housing defining in combination an internal chamber for encircling a tubular element extending through said assembly; means for supplying a pressurized fluid to said chamber, said annular wall formed with a plurality of circumferentially spaced nozzle apertures therethrough for discharging the pressurized fluid into said annular chamber around a tubular element and toward the forward end of said collar.

2. The wall box seal assembly as defined in claim 1 further characterized in that said annular edge is defined by a removable seal ring removably secured to said plate.

3. The wall box seal assembly as defined in claim 1 further characterized in that said annular wall of said collar is of :a tapered configuration progressively increasing in diameter from said forward portion thereof toward said rearward end thereof.

4. The wall box seal assembly as defined in claim 1 further characterized in that said nozzle apertures through said collar are angularly inclined so as to discharge the pressurized fluid in a conical pattern converging at a point corresponding substantially to the longitudinal axis of said annular wall and at a point spaced forwardly of said collar.

5. The wall box seal assembly as defined in claim 1 further characterized in that said rearward one of said end walls is removably mounted on said housing.

6. The wall box seal assembly as defined in claim 1 further including a tubular sleeve of a generally oval- References Cited shaned cross section with its major dimension along an UNITED STATES PATENTS upright axls and having its outer end rigldly afiixed to the forward end of said housing. 810,038 1/1906 D enegre 7. The wall box seal assembly as defined in claim 2 5 31004502 10/1961 Hlbner 110 179 further characterized in that said seal ring comprises a 33731521 9/1966 b f 110-479 plurality of arcuate segments adapted to be disposed with 3,142,272 7/1964 Phllhps et a] 110-179 their ends in substantial abutting relationship thereby defining Said annular edge SAMUEL ROTHBERG, Primary Examiner.

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