US2179741A - Crown sheet protection - Google Patents

Description

Nov. 14, 1939. G HAWLEY 2,179,741

' cnowfi SHEET PROTECTION Filed April 12, 1937 2 Sheets-Sheet 1 Gnome/ s P CfiarlesGHaw Zey Nov. 14, .1939. c. G. HAWLEY CROWN SHEET PROTECTION Filed April 12, 1937 2 Sheets-Sheet 2 Patented Nov. 14, 1939 UNITED STATES PATENT OFFICE CROWN SHEET PROTECTION Company, Cleveland, Ohio Ohio, a corporation of Application April 12, 1937, Serial No. 136,487

4 Claims.

In part, this is a divisional application based upon my allowed application Serial Number 82,953, filed June 1, 1936, and in part, is a continuation or an extension of that application.

A common danger attending the operation of locomotive boilers is that the steaming water in a locomotive may fall below the level of part or all of the firebox crown sheet. When that Occurs, the crown sheet is exposed, overheated and weakened and in that condition is almost certain to be detached from the crown bolts, ruptured, and, blown down into the firebox; resulting in a violent explosion.

The object of this invention is to prevent the extensive disengagement of crown sheet and staybolts under such conditions, and to limit such disengagement to a small area of the high part of the crown sheet. Under those conditions only a few staybolt holes will be opened and the steam allowed to escape slowly, without material damage to the firebox or boiler.

A further object of this invention is to add to the heating surface of the firebox and increase its efficiency.

Briefly, the invention consists in providing one or more water circulating and steaming tubes which rise within the firebox and terminate in the crown sheet, opening therethrough. Combined therewith, are spreader heads of novel construction and which function to distribute water upon the top of the crown sheet, particularly when the water in the boiler sinks to a dangerous level; i. e., to a level which bares any considerable part of the crown sheet. These and other features of the invention will be readily understood on reference to the accompanying drawings.

In said drawings Fig. 1 is a diagrammatic vertical, longitudinal section of the firebox end of a locomotive boiler, constructed and operating in accordance with the present invention; Fig. 2 is a vertical cross section thereof on the line 22' of Fig. 1; Fig. 3 illustrates a modified arrangement of the invention; Fig. 4 is a plan view taken from Fig. 3, the boiler shell being broken away to disclose the top or crown sheet of the firebox; Fig. 5 is an enlarged sectional detail illustrating the novel method and means for attaching a thin walled water circulating tube to a fire sheet; Fig. 6 is an enlarged transverse elevation of a spreader head of novel construction, as employed with a centrally positioned circulating tube; Fig. 7 is a vertical section thereof on the line 1'l of Fig. 6'; Fig. 8 is a plan view of such central spreader; Fig. 9 is like unto Fig. 6 but illustrates the spreader head as adapted for use at one side of the firebox crown sheet; Fig. 10 is a sectional view thereof on the line ill-40 of Fig. 9; and Fig. 11 is a plan View taken from Figs. 9 and 10.

This invention is specially concerned with the prevention of disaster when the level of the boiler water falls or sinks below the top of the firebox. Such disaster is prevented by spraying or wetting all but a limited part of the then exposed area of the crown sheet. In that limited part, the crown sheet is allowed to overheat and tosag or blow down from a few of the crown bolts, affording openings through which the steam in the boiler may slowly and safely escape. Thus an explosion is avoided. I-Iereunder the said limited part of the crown sheet is definitely located and the connections of the crown bolts belonging thereto are of a kind to permit an overheated sheet to sag as indicated by the dotted lines, 2, appearing in Figs. 1 and 3.

It is to be understood that the invention pro- 20 vides this safety feature by means of special spreader heads, I-I, arranged upon the crown sheet, 3, and adapted to Widely spread thereon streams of water which are derived from steamgenerating tubes, T, resembling arch tubes and which traverse the interior of the firebox. As will be made plain, these devices utilize the expulsive force of the steam from such tubes and are arranged to leave only a selected portion of the crown sheet to overheat. 0

The fire sheets of a locomotive firebox are tightly joined throughout and comprise a back sheet 4, side sheets 4', 4', the crown sheet 3, a throat sheet 5 and a flue sheet. As shown in Fig. 1, the crown and side sheets may be extended 35 and with a bottom sheet 6, may constitute a socalled combustion chamber, C. In such cases the flue sheet, marked l, is positioned well forward of the throat sheet 5. In contrast, a plain firebox is typified by a flue sheet 8, which is an upward extension of thethroat sheet as well shownin Fig. 3. During operation the fire is maintained in the space defined by these sheets and the gases depart by way of the fiues 9.

The pressure vessel or boiler shell, which con- 45 tains the firebox, is characterized by a cylindrical shell or barrel portion Ill, terminating in a front flue sheet (not shown) At its rear end, the boiler shell takes the form of, but is larger than, the enclosed firebox. That portion of the shell comprises a' boiler head H, a wrapper plate presenting fiat sides l2 and a curved top' l3. The shell portion is completed by an outside throat plate M, which joins the lower part of the boiler barrel Ill. The vertical sheets identified are united at the bottom, as by the rectangular frame I5, called a mud ring or foundation ring.

As shown, the firebox sheets and the boiler shell are spaced apart, thus providing the throat space N5, the side water legs I1, I7 and the back water leg Ill. The crown sheet 3 and the wrapper top [3 are more widely separated and thus afford space for both water and free steam; and normally both firebox and fiues are submerged in boiler water. The space above the water level is termed the steam space, S, and varies with the position of the water level. The water level, otherwise known as the steam disengagement surface (marked WL), is normally maintained well above the crown sheet 3. If through inattention or other fault that level is allowed to fall below the top of the firebox, the latter is bared and becoming overheated is apt to collapse due to the pressure of the steam above it. As will become apparent, a chief function of this invention is to keep the crown sheets sprayed or filmed with boiler water at such times, and to thereby prevent the ripping or the rupture of the crown sheet, it being obvious that the crown sheet cannot become overheated so long as it is covered or filmed with water. I

The fireboxes shown are of the wide type but the invention is applicable to stayed fireboxes of all cross-sectional forms and shapes.

It will be noted that the crown sheets of these fireboxes are inclined, the high point in each case being at the front of the firebox. This is typical of locomotive practice, having to do with keeping all parts of the crown sheet normally covered with water, notwithstanding the surging and tipping movements of the locomotive.

the crown sheet.

and. the adjacent row of spreader heads.

Each spreader head, H, is a hood which is fastened over the open upper end of one of the tubes, T. One end of the hood is open and the head or hood may therefore be positioned to project mixed water and steam lengthwise of the crown sheet. When only crown sheet protection is in question, a plurality of tubes, T, are employed and likewise a plurality of the heads or hoods, H. The tubes are spaced rearwardly from the flue sheet to allow free access to the latter,

in case repairs are required, and all of the heads belonging to those tubes open rearwardly. Currents of water and steam rise through the tubes, T, and are directed rearwardly upon and across And, so, when the water level sinks below the top of the crown sheet, considerable water still continues to fountain upward from the heated tubes, T, and is sprayed or spread upon the crownsheet, keeping wet all .that part thereof which is rearward of the spreader head. Thus, all parts of the crown sheet are kept wetted and thus protected against overheating, except that part of the crown sheet which is between the flue sheet of the firebox The unprotected part may become hot enough to mushroom downward over the heads of the crown bolts, allowing a small part of the crown sheet to bag, as shown by the dotted lines 2. As before explained, the disconnection of the sheet from the staybolts in this manner permits the slow and safe escape of steam from the boiler.

An important incident of the invention is that the described spreader heads and associated means of attaching circulating tubes to a crown sheet as about to be described, provide a safe method of coupling arch supporting tubes, T, to the crown sheet instead of to the back sheet, 4, as illustrated in Fig. 1. The latter method has known disadvantages. The improved method, illustrated in Fig. 3, carries with it the advantage of employing arch tube circulation for the wetting of the rear portion of the crown sheet in case of low water. In such instances, the spreader heads, H, open or face forward, as well represented in Figs. 3 and 4.

The so-called spreader heads, H, hereof are best shown in Figs. 6 to 11. As therein depicted, each of these heads is integrally united with a thin walled water-steaming-and-circulating tube T and with a so-called conforming plate P, which latter facilitates the fastening of the tube end in the crown sheet. The spreader head proper, H, is mounted upon the top of that conforming plate; the plate itself is large enough to contain four crown bolts 20 and to avoid detrimental welding strains is preferably round. It is welded into an opening 3p provided therefor in the crown sheet. The circular butt weld is marked P4. Presently other details will be explained.

These crown sheet protecting tubes T lead from the lower water legs or spaces of the boiler and after traversing the fire space of the firebox pass through the crown sheet 3 thereof. They may be variously positioned in the firebox, should be properly cambered, and may be used to support arch brick B, as illustrated in Fig. 3 or may be used merely to generate fountains of water for the wetting and protection of selected parts of the crown sheet.

It is not safe to weld a thin walled tube into the thicker firebox sheet, yet such a tube must be tightly secured therein. Further, the tube ends must be somewhat flexibly joined to the fire sheets, and must not be detrimentally affected by the welding process used to secure them. Thick walled tubes are impractical, for they lack necessary flexibility and are apt to burn and crack. The requirement is for thin walled tubes, capable of readily transmitting heat to the circulating water. It will also be seen that the spreader H must often be installed in an existing firebox and being larger than the tube, how to get the spreader into position on the crown sheet is not at once apparent. These and like inherent difficulties are solved by this invention as follows, a new article of manufacture being here presented.

The complete article of manufacture identified Q by this invention comprises; first, the tube T of proper length and form; second, the preferably circular conforming plate P, having a beveled edge P and preferably containing holes P2 for four staybolts 2U and third, the box-like spreader head proper H. Preferably, the lower end of each tube is similarly equipped with a conforming plate or welding patch P. As well shown in Fig. 4, the plate P contains a central opening P which is reamed or tapered to be larger at the bottom than at the top (see lines P). The opening P is just large enough to freely receive the tube T and the taper of the opening permits the plate P to be positioned at any desired angle upon the end of the tube T. Having been so fitted, the end of the tube is flanged (see T2) to fit the top of the plate P, whatever the angular position of the latter. The edge of the flange T2 is then autogenously united with the top or water side of the plate P, as by the peripheral weld T3. Thus the tube and the plate are united upon the water side of the plate and in a manner to preserve a protective flexibility in the joint.

The plate P is conformed or curved to suit the fire sheet to which it is fitted. A round beveled hole 3p is made in the fire sheet 3 and final union is completed by a peripheral fusion weld P l. As stated, each end of the tube may be equipped with a plate P.

Before the plate P is welded in place in the crown sheet it is first provided with the spreader element H. That part is an open bottomed metal box or hoo-d which covers the open end of the tube T and is attached to the top of the plate P by welds h. No attempt is made to attach the lower edges of the box H to the weld flange T2 of the tube, lest the latter be damaged. Instead, the box is shaped to leave a crack or opening 71, directly above one-half of the tube. through which, when in operation, some water is discharged upon the crown sheet to prevent an accumulation of scale back of the spreader head.

Referring to the plan views, Figs. 8 and 11, it will be seen that these heads may be fitted to take fore and aft positions or angular positions upon the curved crown sheet according as it is desired to direct water lengthwise or angularly across that plate. The closed, vertical end it of the box H circles one-half of the tube and from that point the sides 71 flare outward and terminate in substantially parallel parts 71 A cover h is welded upon the side parts 72 and h and it is to be noted that at the discharge end of the box this cover presents a slanting portion h. The latter takes difierent forms according to the position of the head but in every case the lower edge discharge 7138 of the box is presented in a horizontal plane. Hence, the different shapes of the discharge openings, 71 shown by Figs. 6 and 9.

Each spreader head is high enough to permit a tube cleaner to be passed upward through the tube T. A washout plug (not shown) is always provided in the boiler shell opposite the end of each tube, to permit blow down and the insertion of a tube cleaner.

During operation, a vigorous fiow of mixed steam and water ascends through the tube. The purpose of the spreader head is to keep the steam and water in propulsive admixture and to direct 5;, the water as desired across the crown sheet. Now

a box H high enough for the proper use of a tube cleaner and yet normally submerged in boiler water would permit a prompt disengagement of steam from the ascending water; hence, the employrnent of the constricted or slanting end h", as here shown. Obviously, the constriction of the outlet, k of the box in this manner serves to momentarily hood the steam and compel its discharge with the water.

It is desirable and most convenient that the conforming plate be supported by some of the crown bolts 20. The proportions shown permit four bolts to be used in each plate P but it is necessary to pass one or more of the bolts downward through the boxlike part H. To prevent the relief of steam upward around such bolts, the box is provided with one or more steam trapping thimbles, h the operation of which is obvious.

The round opening 3p in the crown sheet 3 is large enough to pass the spreader box when the tube and plate are lifted into position. Having been positioned, the plate P is welded to the fire sheet and thereafter the crown bolts 20 are installed.

From the foregoing description it will be apparent that this invention attains all of the principles and detailed objects which are set forth in the opening of this specification.

I claim:

1. A locomotive boiler and its stayed firebox, in combination with a water-steaming-and-circulating tube opening from the lower part of the boiler, traversing the fire space of the firebox, and, opening through the crown sheet thereof, and a boxlike spreader head upon said sheet and covering the upper end of said tube, said head being of sufiicient height to permit cleaning of the tube and presenting a horizontal discharge opening on one side thereof which is of less height than the height of said head.

2. The new article of manufacture for employment in the combination claimed in claim 1, comprising a thin walled tube, in combination with a weld patch plate of greater thickness and of crown-sheet curvature and to the water side of which said tube is welded and a box-like hooded spreader head, the bottom of which is formed by said water side of said patch plate and said head having a discharge opening in one side and adapted to retard the disengagement of steam, the better to spread water laterally in the plane of the water side of said plate.

3. The article as claimed in claim 2 and having in addition a steam trapping thimble or thimbles in the top of said head for the accommodation of a stay bolt or bolts.

4. A locomotive boiler and its firebox, the latter presenting a stay-bolted crown sheet, in combination with water-steamingand-circulating tubes rising from the lower part of the boiler, traversing said firebox near the forward end of the latter, and passing through said crown sheet, and hooded steam-and-water spreader heads covering the upper ends of said tubes and having openings in their sides positioned to direct water therefrom backward along said crown sheet; as and for the purposes defined.

CHARLES GILBERT HAW'LEY.

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