US2252071A

US2252071A - Steam generator

Info

Publication number: US2252071A
Application number: US163362A
Authority: US
Inventors: Cecil H Gay
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1937-09-11
Filing date: 1937-09-11
Publication date: 1941-08-12
Anticipated expiration: 1958-08-12

Description

Aug. 12, 1941. c. H. GAY

STEAM GENERATOR Filed Sept. l1, 1937 4 Sheets-Sheet l K O @w w cm/ H. 6

m O m Aug. l2` 141. c. H. GAY

- STEAM GENERATOR Filed Sept. 11, -1957 4 Sheets-Sheet 2 1 N VENT OR,

ATTORNEY.

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STEAM GENERATOR Filed Sept. ll, 1,937 4 Sheets-Sheet 3 1 34 IIIIIIIHIII IIIII 4.9

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C66/' H. Gay

Patented Aug. l2, 194i orties STEAM GENERATOR Cecil lill. Gray, Akron, Qhio, assignor to 'Ehe Babcock & Wilcox Company, Newark, N. J., a corporation of New Jersey Application September 1l, i937, Seriai No. 163,362

13 Claims.

spaced tubes which serves as a slag screen and Y also to reduce the heating gas temperature to a value at which the desired superheat can be effected without exposing the superheater tubes to unsafe gas temperatures. The heating gases entering the first generating tube bank will be normally above 2000o F. and while the gas temperature is lowered by the heat absorption of this tube bank, the gases on contacting with the superheater tubes will be at a temperature approaching the maximum temperature which the superheater tubes are designed to withstand. The high steam generating capacity and high superheat temperature for which such units are designed require a large amount of convection heated steam superheating surface in a high temperature heating zone. The problem of supporting such superheating surface has been found to present substantial difficulties. problem is especially difficult where the superheating surface is formed by vertically looped tubes pendantly supported. In such superheat- 4ers the tubes tend to expand and contract under varying temperature conditions and it is important that the designed tube spacing be maintained under such conditions to secure the designed superheating effect.

The main object of my invention is the provision of an improved construction and arrangement of a vapor superheater in a vapor generating unit of the character described. A further and more specific object is the provision of an improved construction and arrangement of l the supporting means for a pendant type steam superheater in a steam boiler of the Stirling type.

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 specic objects attained by its use, reference should be had to the accompanying draw- -i i This V ings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Of the drawings:

Fig. 1 is a Sectional elevation 0f the upper portion of a steam generating unit embodying the invention;

Fig. 2 is an enlarged view of a portion of Fig. 1;

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 2;

Fig. 4. 'is an enlarged view of a portion of Fig. 2;

Figs. 5 and 6 are sectional views taken on the lines 5 5 and -6 of Fig. 4 respectively; and

Fig. 7 is a View similar to Fig. 2 illustrating a modiiicati'on.

In Figs, l to 6 of the drawings the invention is illustrated as incorporated in a steam generating unit having a steam boiler of the Stirling type. The steam generating unit comprises a furnace I0 of substantially rectangular horizontal cross-section and substantial height and adapted to be fired by coal, oil or gas in any suitable manner. The walls of the furnace are lined with vertical water tubes iI connected into the boiler circulation system in a well known manner. The steam boiler comprises front and rear upper steam and water drums I2 and I3 respectively, spaced apart in the upper part of the setting and hung from the external steelwork Id, and a lower water drum I5 connected to the upper drums I2 and I3 by front and rear banks of water tubes I6 and I i respectively. The drums I Z and I3 are interconnected below their normal water lines by rows of water circulator tubes I8. The drums are also connected by steam circulators I 9 for conducting steam from the front drum to the rear drum. The rear drum is shown with suitable steam washing and separating devices located therein.

As indicated in Figs. 1 and 2, the front tube bank I6 contains three rows of tubes, alternate tubes in the two front rows being bent out of alignment with the remaining tubes to form a slag screen. The lower inclined portions of the third tube row have studs projecting into their intertube spaces and covered with refractory to form a baffle 20 extending upwardly from the lower drum I5. A steam superheater 25 of the pendant type occupies substantiallyall of the space between the banks of tubes I 5 and I1. With the described arrangement high temperature heating gases are generated in the furnace Iii, passing upwardly therethrough into contact with the front tube bank I6, thence around the upper end of the baffle 2E!, and rearwardly across the superheater and rear tube bank I1 to a heating gas outlet 2fl. The gas outlet 24 may be connected to a suitable economizer and/or an air heater, and thence to a stack connection.

The steam superheater 25 comprises a horizontally arranged inlet header 26 connected along its length to tlile top of the drum i3 by aseries of tubes 27. A superheater outlet header 28 is arranged adjacent the inlet header 26 and both of the headers supported upon transversely spaced beams 29 extending between and supported by the drums l2 and i3.

rI'he headers

26 and 28 are connected by a series of substantially parallel steam superheating tubes 39, each formed in a flat multiple-looped coil, with the coils in lateral spaced alignment and providing parallel steam flow paths between the inlet and outlet headers. Each of the tubes 3G includes Ya series of vertical tube legs 3l interconnected in series at their upper and lower ends by looped portions 32. The tube legs 3l are proportioned in length in accordance with the available space above the baffle 25J, so that the rearmost tube legs are of the greatest length. Each of the tube coils is divided into spaced iront and rear sections to facilitate the inspection and cleaning of the superheater tubes. The upper looped portions 32 are positioned adjacent the water circulator tubes i3. In the space therebetween is arranged upper and lower horizontally extending serially connected tube legs 33 and 313 respectively. Each tube leg 33 is extended upwardly and connected to the inlet header 2b, while the corresponding tube leg 34 is connected to the corresponding rearrnost vertical tube leg 3|. The foremost tube leg 3| is extendedupwardly and connected to the outlet header 28. With this arrangement steam from thedrum i3 passes through the tubes 21 to the header 25, thence serially through the horizontal tube legsf33 and 3d, and thence serially through the vertical tube legs 3l to-the header 2B, so that the flow of steam through the superheater will be generally counter to the iiow of heating gases across the superheater tubes, whereby maximum superheat temperatures are obtained.

Thesuperheater tube coils are supported from the beams 2.9by hanger rods 2S detachably connected to cross-beams lil supported from the beams 29. As shown in Figs. 3 to 5, each rod Ml hasY a pair of eye plates l2 welded to its lower end and through which a bolt #53 extends to provide a pivotaxis for a pair of toggle collars M loosely mounted on a pair of adjacent tube legs 33. As shown, only two hanger supports are required for each pair of adjacent superheater tube coils. Each pair of

tube legs

33 and 34 is interconnected to form a supporting beam for the remaining portion of the superheater tube coil by collar members 46 loosely mounted on the tube leg 33, and each having a projecting lower plate portion 4l welded to the tube leg 35. Each of the collar members 46 is provided with lateral bosses 48 having flattened ends engaging corresponding bosses on adjacent tube legs 33 to maintain the side-by-side tube coils in spaced relation. The supporting beam deiined by the

tube legs

33 and 34 and connecting members llt carries the remaining portion of the superheater tube coil through plates l welded to the lower portion of the tube leg 34 and the top of ea-ch of the adjacent upper looped portions 32 of the vertical tube legs 3l. The tube legs 3l of each coil are held in spaced relation by split clamps D connecting adjacent tube legs. The tube legs 33 are movable axially relative to the collars i4 and 45, so that relative movement of the tube legs 33 and 36 is possible in operation under differential temperature conditions.

The superheater headers and hanger connections are protected from the heating gas iiow across the superheater by refractory mounted on the Water circulators I8 and forming a roof section 55 extending between the drums IZ and I3. Protection is also afforded the collar members 44 and 4S by a row ol' tile E mounted on the tube legs 3ft and closing the spaces therebetween to form a roof section subjacent the roof section 55, the space between the front end of the tile 56 andV the roof section 55 being closed by special tile members 5l carried by the tube legs 33. With this construction the superheater supporting provisions will contribute substantially to the support and maintenance of the roof section between the upper drums.

The described construction provides a simple and highly effective support for the superheater, with only a relatively few external supporting attachments. The number of external supports required depends partly upon the number of tube legs arranged horizontally and utilized in the supporting beam for the remaining portion of the superheating coil. The expensive hung arch construction usually required for the roof section between the upper drums can thus be eliminated. The individual symmetrical suspension support of each of the looped portions 32 substantially eliminates distortion of the superheater coils during operation. The construction also provides a convenient arrangement for positioning the superheater headers at any desired location between the upper drums without requiring the use of excessively long external superheater tube extensions or the support of the tube coils from the superheater headers.

The modified construction illustrated in Fig. 7 differs from that shown in Figs. 1 to 6 by a change in location of the inlet and

outlet headers

25 and 28, the omission of the beams 29 and water circulators I8 between the drums, and the support of the superheater tube coils and associated roof section directly from the external steelwork Id. This construction not only provides an effective support for the superheater coils but also is effective in maintaining a cool and 4permanent roof in a very hot zone.

While in accordance with the provisions of the statutes I have illustrated and described herein the best forms of my invention now known t0 me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

I claim:

1. In a steam boiler, a steam superheater comprising a steam superheating tube having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and upper and lower horizontally arranged serially connected tube legs extending across the upper ends of said vertical tube legs, means for supporting said upper tube leg from an external support at longitudinally spaced points, means connecting said upper and lower tube legs to form a horizontal beam structure, and means for connecting the upper looped portions of said vertical tube legs to said lower tube leg.

2. .Ina steam boiler, a steam superheater comprising a plurality fof steam superheating tubes arranged side-by-side and forming parallel steam flow paths, each of said tubes having a series of vertically arranged tube legs serially connected at their upper' and lower ends by looped portions and upper and lower horizontally arranged serially connected tube legs extending across the upper ends of said vertical tube legs, means for supporting'said upper tube leg from an external support at longitudinally spaced points, means connecting said upper and lower tube legs to form a horizontal beam structure, and means for separately connecting each of said upper looped portions of said vertical tube legs to said lower tube leg.

3. In a steam boiler, a steam superheater comprising inlet and outlet headers, a plurality of steam superheating tubes arranged side-by-side and forming parallel steam flow paths between said headers, each of said tubes having a series ofvertically arranged tube legs serially connected at their upper and lower ends by looped portions and upper and lower horizontally arranged serially connected tube legs extending across the upperends of said vertical tube legs, means for supporting said upper tube leg from an external support "at" longitudinally spaced points, means connecting said'upper and lower tube legs to form a horizontal beam structure permitting relative longitudinal movement of said tube legs, and 'means for permanently connecting the upper looped portions of said Vertical tube legs to said lower tube leg.

4. In a steam boiler, a steam superheater comprising inlet and outlet headers, a plurality of steam superheating tubes arranged side-by-side and forming parallel steam flow paths between said headers, each of said tubes having a series of vertically arranged tube legs` serially connected at their upper and lower ends by looped portions and upper and lower horizontally arranged serially connected tube legs extending across the upper ends of said vertical tube legs, means for supporting said upper tube leg from an external support at longitudinally spaced points, means connecting said upper and lower tube legs to form a horizontal beam structure permitting relative longitudinal movement of said tube legs, said last mentioned means having provisions for spacing adjacent tubes, means for permanently connecting the upper looped portions of said vertical tube legs to said lower tube leg, and means for holding said vertical tube legs in spaced relation.

5. In a steam boiler, front and rear horizontally arranged steam and water drums, a vertically extending tube bank having its upper ends connected to said front drum, a roof section extending between said drums, a steam superheater comprising inlet and outlet headers, a plurality of multiple-looped steam superheating tubes vertically arranged Side-by-side at the rear of said tube bank and forming parallel steam ilow paths between said headers, supporting steelwork above said roof, and common means for supporting said roof section and pendently supporting said superheater from said steelwork.

6. In a steam boiler, front and rear horizontally arranged steam and water drums, a tube bank having its upper ends connected to said front drum, a steam superheater comprising inlet and outlet headers, a plurality of steam superheating tubes arranged side-by-side at the rear of said tube bank and forming parallel steam flow paths between said headers, each of said tubes having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and upper and lower horizontally arranged serially connected tube legs extending across the upper ends of said vertical tube legs, supporting steelwork above said superheater, means for supporting said upper tube leg from said supporting steelwork at longitudinallyspaced points, means connectingsaid upper and lower tube legs to form a horizontal beam structure, and means for connecting the upper looped portions of said vertical tube legs to said lower tube leg.

'7. In a steam boiler, a `pair of horizontally arranged steam and water drums, a plurality of tube banks having their upper ends connected to said drums, a roof extending 'between said drums, a steam superheater comprising inlet and outlet headers, a plurality of steam superheating tubes arranged side-by-side between said tube banks and forming parallel Vsteam flow paths between said headers, each of said tubes having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and upper and low-er horizontally arranged serially connected tube legs extending Vacross the upper ends of said vertical tube legs, a supporting beam extending between and carried by said drums above said roof, means for supporting said upper tube leg from said supporting beam at longitudinally spaced points, means connecting said upper and lower tube legs to form a horizontal beam structure supporting said roof and permitting relative longitudinal movement of said tube legs, and means for separately connecting each of said upper looped portions to said lower tube leg.

8. In a steam boiler, a pair of horizontally arranged steam and water drums, a plurality of spaced tube banks having their upper ends connected to said drums, a steam superheater comprising a plurality of steam superheating tubes arranged sideby-side in the space between said tub-e banks, each of said tubes having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and a horizontally arranged serially connected tube leg extending across the upper ends of said vertical tube legs, means for supporting each of said superheater tubes independently of its ends comprising an external support above said superheater, means for supporting said horizontal tube leg at points spaced longitudinally thereof from said external support, and means for connecting upper looped portions of said vertical tube legs to said horizontal tube leg.

9. In a steam boiler, a pair of horizontally arranged steam and water drums, a plurality of spaced tube banks having their upper ends connected to said drums, a roof extending between said drums, a steam superheater comprising inlet and outlet headers above said roof, a plurality of steam superheating tubes arranged side-by-side in the space between said tube banks and forming parallel steam flow paths between said headers, each of said tubes having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and a horizontally arranged serially connected tube leg extending across the upper ends of said vertical tube legs, a supporting beam carried by said drums above said roof and supporting said headers, means for supporting each of said superheater tubes independently of its connections to said headers comprising hanger means for supporting said horizontal tube leg at points spaced longitudinally thereof from said supporting beam, and means for connecting upper looped portions of said vertical tube legs to said horizontal tube leg.

10. In a fluid heater, a pair of horizontally extending parallel uid heating tubes, and means for supporting said tubes in transversely spaced relation comprising a support above said tubes, a hanger rod carried by said support, a pair of collar members loosely mounted on said tubes and having a common pivot connection to the lower end of said hanger rod, and additional collar members similarly mounted on said tubes and having contacting bosses arranged to maintain.

said tubes in transversely spaced relation.

11. In a fluid heater, a pair of parallel U- shaped fluid heating tubes having upper and lower horizontally extending leg portions, means for supporting said tubes, a collar member loosely mounted onifeach of said upper leg portions and having a boss thereon arranged in abutting contact with a boss on the collar member of the other tube to maintain said tubes in transversely spaced relation, each of said collar members having a projecting plate portion Welded to the corresponding lower leg portion.

12. In a steam boiler, a steam superheater comprising inlet and outlet headers, a plurality of steam superheating tubes arranged side-byside and having their opposite ends connected to said headers, each of said tubes having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and a horizontally arranged tube leg extending across the upper ends of and serially connected to said vertical tube legs, a supporting structure above said superheater, means for supporting each of said superheater tubes independently of its connections to said headers comprising hanger means carried by said supporting structure and connected to said horizontally arranged tube leg at longitudinally spaced points, and means for supporting the upper looped portions of said vertical tube legs from said horizontally arranged tube leg.

13. In a steam boiler, a steam superheater comprising inlet and outlet headers, a pair of steam superheating tubes arranged side-by-side and having their opposite ends connected to said headers, each of said tubes 'having a series of vertically arranged tube legs serially connected at their upper and lower ends by looped portions and a horizontally arranged tube leg extending across the upper ends of and serially connected to said vertical tube legs, an external support above said superheater, means for supporting said superheater tubes independently of their connections to said headers comprising hanger rods carried by said external support, means forming a pivot connection between each of said horizontally arranged tube legs and the lower end of said hanger rods at longitudinally spaced points and permitting movement of said tubes about an axis parallel to the axes of said horizontally arranged tube legs, and means for connecting the upper looped portions of said vertical tube legs to the corresponding horizontally arranged tube leg.

CECIL H. GAY.'A