US2563489A - Superheater boiler - Google Patents

Description

1951 w. H. ROWAND 2,563,489

SUPERHEATER BOILER Filed Aug. 25, 1 945 43 2 Sheets-Sheet .1

I Q3861 4/ 727 45 3x0 o fi u o U gs sooass 9 z4- P3 8a /3 70a 00 O/(DOOGnnOOnOOO 000000000 noooooo 0000 000000000 "000000 0000 0 W WW INVENTOR -W1'// H. Eon and BY ATTORNEY Patented Aug. 7, 1951 SUPERHEATER BOILER Will H. Rowand, Madison, N. J., assignor to The Babcock & Wilcox Company, Rockleigh, N. J a corporation of New Jersey Application August 25, 1945, Serial No. 612,647

3 Glaims. l

The present invention relates to the construction of a Water tube boiler including a steam superheater, and particularly to a construction affording flexibility in the modification of gas flow characteristics as a means for attaining the desired degree of superheat under predetermined operating conditions.

When boiler operation is affected as the result of a change in fuel, for example, or of other changed conditions, it often becomes necessary to efiect a change in heat absorption by the superheater, particularly when the steam-using apparatus imposes limitations with respect to the temperature of superheated steam to be supplied. In an existing installation, the alteration in heat absorption can generally be accomplished by adding or removing superheating tube surface, but each such operation is a troublesome and often an unduly expensive procedure which cannot be reversed without corresponding disadvantages. A second method of attaining modification of the degree of superheating in an existing installation is through provision of means for altering the effectiveness of the superheater heat absorbing surface. Both methods have been utilized in the past, and it is the latter method with which the present invention is more directly concerned in that my invention has for an objective the means whereby the practice of such a method is facilitated.

With respect to certain types of boilers, such as those having upright lengths of tubes extending between and connected to upper and lower drums, my invention further contemplates the use of a gas directing balile suitably positioned in relation to a superheater located between such drums as a means for attaining adjustment of heat absorption by the superheater without the requirement of a change in the extent of superheater heat absorbing surface.

1 My invention also contemplates a boiler havin selected boiler tube portions arranged to support a baflle in gas directing relationship to adjacent superheater surface.

3 Another object of my invention is the provision of boiler tubes having portions arranged in gas shielding relationship to an upper boiler drum and adapted to support a baflle in gas directing relationship to adjacent superheater tubes.

An additional object is the provision, in a boiler having horizontally spaced groups of upright tubes, of a novel arrangement of tubes in one of the groups to serve as a support for a baflle disposed in gas directing relationship to a superheater located between the groups.

A further object of my invention is the provision of a readily modifiable baflle structure positioned in operative relationship to a superheater and defining a portion of the gas flow passage in which the superheater is located.

Still another object is the provision of a baflle arranged in gas directing relationship to a superheater and formed of removable and replaceable sections enabling adjustment of heat absorption by the superheater whose area of exposure to the gases is maintained constant.

Among other objects is the provision of a superheater positioned in a heating gas pass formed between upper and lower boiler drums together with a sectional baflle aliording adjustment of the proportion of heating gases directed over the superheater.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Fig. 1 of the drawings is a sectional elevation of an integral furnace type of boiler illustrating an embodiment of my invention;

Fig. 2 is a horizontal plan section of the boiler shown in Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view showing an element of my invention, taken along line 3-3 of Fig. 1; 4 a

Fig. 4 is a sectional elevation of a boiler, similar to Fig. 1, illustrating a modification of my invention; and

Fig. 5 is a fragmentary horizontal plan view of Fig. 4, in section along line 55.

In detail, and referring first to Figs. 1 and 2, the boiler shown is of the two-drum integral furnace type, having a boiler tube space arranged laterally of the combustion chamber and providing for heating gas flow through the space in a plurality of passes, the boiler having a setting of substantially rectangular horizontal cross section defined by upright front and rear wall l0 and [2 respectively, together with upright side walls l3 and M, the latter bein extended over the top of the setting to form the roof l5. Interiorly of the setting is an upright wall or partition I 6 dividing the space within the setting into a combustion chamber l "l and a laterally adjoining boiler space l8. Burners l9 of any suitable type forv the kind of fuel to be burned are installed in association with the front wall is to provide a source of heating gases. The dividing wall it extends from the front wall IE] to a location spaced from the rear wall [2 whereby a passage 2! is provided as an outlet for heating gases passing from the combustion chamber ll into the boiler space l'8. Transverse baflles '23 and 2 extending partially across the boiler space [8 provide serially connected gas passes 25, 26 and 21 through which a substantially horizontal flow of heating gases is maintained from the combustion chamber ll. The spent gases are discharged from the setting through an outlet, not shown, suitably from the final pass 21 at a location closely adjacent the front wall It.

The boiler includes upper and lower drums 28 and 29, respectively, having their longitudinal axes in a common vertical plane, the drums being connected by a bank of upright boiler tubes 31 disposed Within the boiler space is substantially throughout the length thereof between front and rear walls ii] and [2. The boiler bank tubes are suitably arranged in parallel rows extending longitudinally of the boiler'drums 2B and29, preferably with the tubes in the first pass larger in diameter and more widely spaced than the tubes in either of the succeeding passes 26 and Other tubes connected to the boiler drums '28 and '29 include the fioor cooling tub-es 32 extending from the lower drum 29 to the side wall header '34, the side wall and roof tubes 83a extending from the header S4 to the upper drum '28, and the front and rear wall tubes I'Da and [2a, respectively, through upper and lower headers 35 and 36, and through riser and make- up tubes 35a and 36a, respectively.

In the first pass 25, the tubes of the boiler bank 3| are divided horizontally into front and rear tube groups 31 and $8 defining a superheater space 39 'therebetween, the tubes in each of these groups having the major portions of their lengths vertically disposed and having their end portions suitably bent as shown for connection to the drums in circumferentially spaced rows. Certain tubes 31a of the front group 3'! may be arranged in staggered relation as shown to form a known pattern of slag screen across the entrance 2| into the first pass 25. The rear group 38 ineludes several rows of tub-es 38h spaced from the side wall l4, and. a single row of tubes 38b spaced along the wall l4.

A superheater 4| disposed within the space 39 comprises a series of vertically extending inner and outer tube loops Ma, formed as U-tubes and arranged forwardly of the vertical plane containing the centerlines of drums Z8 and 29, the loops 41a having their ends connected to inlet and outlet headers 42 and 43, respectively, arranged in horizontally spaced relation at different elevations, the rearwardly disposed inlet header 42 at the higher elevation being connected to the upper boiler drum 28 through tubes 45 which extend downwardly along the side wall 54 between the spaced boiler tubes 3%. The superheater 4i may be suitably supported by known means not shown, interposed between the headers 42, 43 and the lower bottom-supported boiler drum 29, a baffle 46 extending from the drum 29 and across the superheater tube loops 4 la to protect the headers 42 and 43 from the hot gases entering the first pass 25, the bafile 46 also defining the lower boundary of the passage available for gas flow overthe superheater tubes 41a.

suitably connected to the drums The baflle it includes a lower portion 45a extending upwardly and forwardly along the inner row of boiler tubes 31, and an upper intermediate portion stb inclined upwardly and rearwardly across superheater tubes above the lower header 43, the baflle terminating in an upper portion 460 extending across superheater tubes above the up- ;per header 42.

On the basis of the construction thu far de-' scribed, the height of the total available gas flow space through pass 25 at the location of the superheater is measured between the uppermost portion of baflle 15 and the under surface of drum 28. The space between the uppermost loop ends of the superheater and drum 28 is thus available for the bypass of a certain proportion of the gases particularly for minimum superheat temperatures. However, when higher superheat temperatures are required, a bafrle ii? is installed within the bypass space, as embodied in the present disclosure, to block o-fi any desired portion of the total available bypass area and thus enable higher predetermined degrees of superheat to be obtained. In the form shown, the bafiie 6? extends downwardly from the drum 28 to a predetermined level adjacentthe uppermost loop ends Where only a relatively small space 48 remains in order that superheat temperatures approaching the maximum maybe obtained.

The bypass baffle 4'5 i preferably supported entirely on tubes of the boiler and for this purpose, in the form shown in Fig. 1, two rows of tubes 380 of the rear group 38 are bent forwardly and upwardly in a reverse curve above the upper end of the superheater to enter the lower forward quadrant of drum 28 adjacent the rows of tubes forming the front group 3i, the portion of each'tube 380 between bends being horizontally inclined.

The 'baiile 4i is retained between the two rows of tubes 380 at their upper ends and in this position acts to shield the rearward lower portion of drum 28 from direct impingement by the hot products of combustion flowing rearwardly in the space beneath the drum. The upper ends of tubes 38c may in themselves serve as a shield or screen for the rearward lower portion of drum 23 under conditions when the baffle 41 might be omitted or when the baffle is narrow so as to extendonly a short distance downwardly from the drum. The baffle 41 conforms in general to the curvature of the forward row of tubes 380 against which it rests so as to present a surface to the approaching gases which is practically self-cleaning, that is, a surface on which there is little tendency for any solid products of combustion to accumulate, due to its upper end portion being generally vertically disposed and its lower end portion being generally inclined downwardly toward the side wall l4. Moreover, with the bafile il position ed rearwardly of at least one row of tubes 380, the forward sides of the tubes in that row in the zone of the baffie are in contact with hot gases and thus are effective as boiler heating surface.

As indicated in Fig. 3, the baffle 41 is suitably formed of separate rectangular tile sections such as 41a, 41b and Mo installed in horizontally extending'rows between the two adjacent rows of boiler tubes 380, the lowermost row of tile 41c resting against bracket or stop'members {iii-which are individually welded or otherwise secured to successive tubes 380 in one row. Alternate known forms of stop means 49 may be used if desired, such as C-clamps which may be bolted about tubes 380.

Each tile section 47a, 47b or 410 is preferably made long enoughto span two inter tube spaces so that the joints 5| between successive tile sections occur at every alternate tube in the row, whereby the ends of each tile are supported on alternate tubes while the central portion of each tile is supported on an intermediate tube. For example, each tile section would have a length of twelve inches for tubes 38c spaced on six-inch centers, and a length of twenty-four inches for tubes 38c spaced on twelve-inch centers, the edges of adjoining tile sections being beveled or otherwise companionately shaped to provide substantially gas tight joints 52 trans versely of the tube lengths 380.

Should a longer or shorter extension of baffle '41 be desired, in order to alter the extent of the gas bypass area 48, the change may be readily effected by increasing or decreasing the number of tile sections 41a, 41?), etc., or by substituting one or more tile sections of different dimension as measured longitudinally of the supporting tubes 380. If the baffie 4'! is to be made narrower, the change in width may be made from either end, although preferably the upper end will remain incontact with the upper drum 28 and any alteration in width made at the lower end. It will be understood that stops 49 may be relocated as necessary to suit the new dimension of battle. Due to the formation of the row of bafile supporting tubes 380, the lowermost tile 410 are supported on a downwardly inclined portion of the row and thus are held in contact with their supporting tubes by gravity.

In a boiler such as described, the boiler tubes in groups 3'! and 38 are suitably of three inches outside diameter, and except for tubes 31a are uniformly spaced at six-inch centers in rows extending longitudinally of the drums 28 and 29, the tubes 31a being spaced at twelve-inch centers to provide the staggered arrangement. The tubes 38a and 381) being aligned in rows transversely of the drums 28 and 29 provide the necessary intervening spaces to enable the superheater inlet tubes 45 to be installed between tubes 38b adjacent the side wall l4 and between tubes 38a to enter the inlet header 42. The superheater tubes 4m are suitably of one-and-one-half or two inches outside diameter and arranged at center-to-center spacings of two-and-one-half inches in successive longitudinal rows.

In the modification illustrated in Figs. 4 and 5, the boiler and furnace arrangement is generally the same as that shown in Figs. 1 and 2, and accordingly for convenience and clarity the same reference characters are utilized to identify identical or closely similar parts. In the modified form, a seven-loop superheater BI is shown of considerably greater capacity and heating surface than the two-loop superheater M of the previously described embodiment; in this instance, the superheater having portions of its heating surface at both sides of the common vertical plane containing the longitudinal axes of the upper and lower boiler drums 28 and 29. The loops bla, formed as U-tubes and arranged in groups of four to provide the superheater inlet section, are connected at their opposite ends to inlet header 42 and intermediate header 62, while the loops or U-tubes tlb, arranged in groups of three to provide the superheater outlet section, are connected at their opposite ends to intermediate header B2 and outlet header 43. Each group of four inlet loops tile is in a single plane transverse to the drums 28 and 29 and thus successive four-160p groups are in successive parallel planes parallel to the flow of heating gases. The:

groups of outlet loops 6lb are arranged with legs 63 extending from the intermediate header 62 in planes common to the inlet loops Bid, and with legs 64 of the majority of the loops extending toward the outlet header 43 in half the number of planes to provide twice the spacing for legs 3: across. the width of the setting than for legs A baffle 41 similar to that provided in the boiler first described is disposed across the bypass space 48 between the upper end of the superheater BI and the upper drum 28. In the present form of boiler, the boiler tubes constituting the rear group 38 are disposed in a single row along the side wall l4, suitably at uniform six-inch center-to-center spacings, as in Figs. 1 and 2; the rear group 38 including one set of tubes 38b at twelve-inch centers connected to the upper drum 28 rearwardly of the common plane containing the drum axes, and a second set of tubes 38c, also at twelve-inch centers and alternating with tubes 38b, connected to the upper drum 28 forwardly of the common plane adjacent the front group of tubes 31. The tubes 38b and 380 are thus interspersed along the wall I4 and provide intervening spaces in which are disposed the desired number of superheater inlet tubes .5, preferably at six-inch or twelve-inch spacings. The upper end portions of tubes 380 are suitably bent in a, reverse curve, substantially as shown, to afford support for the superheater bypass baffle 41 which may be formed and arranged substantially as described in connection with Fig. 3, the lowermost row of tile sections such as 410 resting against stops 49 secured to individual tubes 380. The major portion of bafile 41 rests on horizontally inclined portions of tubes 38c and thus is held in contact with its supporting tubes by gravity. Any tendency for the uppermost tile sections 41a to tilt away from tubes 380 is opposed by the layer of heat insulating material commonly applied to the upper drum 28 at the location indicated.

I claim:

1. A boiler comprising horizontally disposed upper and lower drums having longitudinal axes in a common plane, upright boiler tubes extending between said drums and having upper and lower ends connected thereto in rows paralleling said plane, said tubes being arranged in horizontally spaced front and rear groups laterally adjacent a heating gas source from which gases are directed horizontally over said tubes in a single pass throughout the major portion of the height of the space between said drums, a superheater having tubes disposed between said front and rear tube groups and positioned in downwardly spaced relation to said upper drum so as to provide a gas bypass space therebetween, said rear tube group including a front set of tubes disposed in at least one row and having upper portions reversely bent over the upper end of said superheater and connected to a lower quadrant of said upper drum forwardly of said plane adjacent the upper portions of tubes of said front group, the remaining tubes of said rear group forming a rear set of tubes having upper portions connected to a lower quadrant of said upper drum rearwardly of said plane, said sets of rear group tubes bein circumferentially separated at said upper drum a distance equal at least to the circumferential width of space occupied by the upper end portions of said front group tubes in a plurality of said rows, and a bafile supported on said row of reversely bent tubes for restricting the flow of heating gases through said bypass space; ,said bafile extending downwardly .from a portion of the space between said front and rear tube groups, the superheater tubes extending up wardly from said headers and having ends connected thereto, said front set of rear group tubes comprising two rows of tubes between which the baffle above the superheater is positioned, and a lower baffle extending upwardly from said lower drum forwardly of the superheater headers to a terminal position above said headers, said bafiies combining to direct said gases toward and across said superheater tubes in said single pass while said lower bafile constitutes a means for shielding said headers from the hot gases enterin said pass.

3. A boiler comprising horizontally disposed upper and lower drums havin longitudinal axes in a common plane, a group of upright boiler tubes connecting said drums in rows paralleling said plane and being arranged forwardly of said plane across the path of heating gases flowing horizontally in a single pass between said drums, means defining a lateral boundary of said gas path comprising an upright setting wall arranged parallel to said drums'in rearwardly spaced relation thereto, a second group of boiler tubes rearwardly spaced from said first named roup and comprising two sets of tubes having intermediate portions in a substantially common row adjacent said upright wall and having the upper tube ends of the respective sets connected to said upper drum in circumferentially separated rows at opposite sides of said common plane, said sets of tubes of said second group being circumferentially separated at said upper drum a distance equal at least to the circumferential width of space occupied by the upper end portions of said forwardly arranged tubes in said rows, a superheater disposed between said groups of boiler tubes and comprising tubular elements confined to elevations below said upper drum, vapor inlet connections from said upper drum to said superheater comprising a row of tubes having portions interspersed with tubes of said second group adjacent said upright wall, one of said sets of tubes of said second group having upper end portions reversely bent over the upper end of said superheater elements and connected to said upper drum adjacent tubes of said first named group, and a bafiie supported on said reversely bent tube portions for directing gases across said superheater elements while restricting the flow of gases through the space separating said elements from said upper drum.

WILL H. ROWAND.

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

UNITED STATES PATENTS Ebbets et al Nov. 9, 1943

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