US2228981A - Steam generator - Google Patents

Description

Jan. 14, 1941. 'r a s-n 2,228,981

STEAM GENERATOR Filed 001:. 12, 1938 5 sheets sheet l ZNVENT OR.

7725mm 5 Sfz'Z/man ATTORNEY.

Jan. 14, 1941. sTlLLMAN 2,228,981

swam GENERATOR Filed Oct. 12, 1938 5 Sheets-Sheet 2 Fi .1 F

IN VENTOR.

Thomas B. Szfz'Z/marz ATTORNEY.

an, 14,, 1941. T. B. STILLMAN STEAM GENERATOR Filed 001;. 12., 19:58

5 Sheets-Sheet 3 INVENTOR.

T'roRNEY.

Jam. 14, 1941.

T. B. STILLMAN $228,981

STEAM GENERATOR Filed Oct. 12,1938 5 Sheets-Sheet 4 UUUU w F n H INVENTOR.

Thomas .5. Sizf/man ATTORNEY.

Jan. 1941; T. B. STILLMAN 2,228,981

STEAM GENERATOR Filed Oct. 12, 193B 5 Sheets-Sheet 5 onooo manna cacao INVENTOR.

Thomds B. SEN/man STEAM GENERATOR Thomas B. Stillman, South Orange, N. 1., assignor to The Babcock at Wilcox Company, Newark, N. 1., a corporation of New Jersey Application October 12, 1938, Serial No. 234,526 1 '15 Claims.

The present invehtion relates to the construction and arrangementof internal baflle systems for a steam and water drum of a water tube steam boiler, and, more particularly, a steam boiler hav- 5 ing a multiplicity of steam generating tubes discharging directly into the water space of the drum.

With the small diameter high capacity steam and water drums used in three drum express type 1D marine boilers, for example-,it has been found extremely difficult to carry a water level above the center line of the drum without danger of substantial moisture carryover in the outgoing steam. This is due to a tendency for the steam to and water discharged from the tubes to flow up through the water locally and violently disturb the water surface. When such boilers are employed, the feed water supply to the boiler is ordinarily manually controlled by a water tender.

20 Rapid and substantial fluctuations in the drum water level which occur when turbulent conditlons are present in the water, render the water tending operations difficult.

In such boilers, various arrangements of sub- 25 merged bafiles have been suggested for reducing turbulence of the water in the steam and water drum by attempting to effect uniform liberation of the steam over the area of the water surface. One such bafile arrangement which has met with 30 fair success is shown in the Donald Patent 1,884,614 as a submerged V-shaped perforated baflle in the path of discharge of the generating tubes having the highest rate of steam generation. With high water levels and increasing steaming 35 capacities, the Donald arrangement has been found to be inadequate to maintain a substantially dry steam discharge and steady water level conditions.

The main object of my invention is the provi- 40 sion of an improved construction and arrangement of a submerged bafile system for a steam and water drum of a steam boiler of the character described, the operation of which is characterized by the maintenance of a substantially 45 dry steam discharge and steady water levels in the drum under high capacity operation, even with high water levels in the drum.

The various features of novelty which characterize my invention are pointed out with particu- 50 larity 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 55 drawings and descriptive matter in which I have I Cl. 122-491) illustrated and described preferred embodiments of my invention.

f the drawings: Fig. 1 is a sectional elevation of a three drum express type marine boiler having a steam and water drum baflle system constructed in accordance with my invention;

Fig. 2 is an enlarged view of the steam and water drum of Fig. 1;

Fig. 3 is an enlarged view of the feed pipe shown in Fig. 2;

Fig. 4 is an enlarged view of the dry pipe shown in Fig. 2;

Fig. 5 is a. horizontal section taken on the line 5-4 of Fig. 2;

Fig. 6 is a vertical section taken on the line B-6 of Fig. 2;

Fig. 7 is a plan view of the V-shaped baffle taken on the line l--'l of Fig. 2;

Fig. 8 is a view similar to Fig. 2 illustrating a modified construction; and

Figs. 9 and 10 are full size sectional views taken on the lines 99 and Ill-IO respectively of Fig. 8.

While my invention is applicable to various types of steam boilers having a submerged connection of th steam generating tubes into a steam and water drum, it is particularly designed for and especially useful in three drum express type marine boilers, such as shown in Fig. 1. The steam boiler illustrated has a horizontally arranged steam and water drum ill connected to a pair of laterally offset parallel lower water drums H and I2 by oppositely inclined banks of water tubes l3 and II respectively. The inverted V- shaped chamber therebetween is divided by a vertical partition 15 into separate furnaces l6 and ll. The partition includes a row of water tubes l8 connected to the drums Ill and H. The tube bank I3 is divided into a pair of spaced tube groups and the space therebetween utilized for 4 the installation of a steam superheater 19. Each furnace is heated by a separate group of fuel burners, diagrammatically indicated at 2B, in one of its end walls and the heating gases after traversing the corresponding tube bank pass across an extended surface economizer 21 to the stack. With this construction, only the furnace I1 is used in starting-up and the furnace l8 operated when there is an adequate flow of steam through the superheater. Control of the firing or combustion in the furnace I 6 is used to regulate superheat temperatures, and that in furnace H to regulate the generation of steam.

As shown in Figs. 2 and 3, feed water is supplied to the steam and water drum through a submerged feed pipe 25 entering through one end of the drum and capped at its other end. Holes 26 along the upper side of the feed pipe provide a distribution of the feed water along the length of the drum. A dry pipe 21 extends along adjacent the top of the drum with holes 28 in its upper side for the passage of steam. The dry pipe is connected to a central steam outlet 29 and a safety valve connection 30.

In the boiler described, the designed water level in the steam and water drum is at the horizontal center line of the drum. As shown in Figs. 1 and 2, all of the tubes in the tube banks l3 and [4 enter the drum below this level.

With furnaces l6 and H in operation, most of the steam will be generated in the portions of the tube banks nearest the furnaces and the tubes in the outer portions of the tube banks will serve as downcomers, supplemented by groups of downcomers 3| at the ends of the tube banks. The submerged discharge of a multiplicity of high velocity streams of steam and water upward through the water along the longitudinal central part of the drum tends to effect a highly turbulent condition in the water space of the drum with a high exit velocity of the steam leaving the water space mainly above the tubes nearest the furnace. Such conditions contribute to entrainment of water by the steam leaving the water space and the production of wet steam with a relatively high solid content. With the drum baflle system of I my invention, a substantially uniform liberation of steam at a reduced water exit velocity across the entire water surface is effected.

My improved drum bafile system is divided as shown in Fig. 1, into three parts, a lower V-shamd bafiie Ml, a pair of wing baflles 5t, and a horizontal center baiile 60. The V-shaped bafie 60 is formed by two oppositely inclined perforated steel plates ll having upturned flanged inner edges 52 connected together along the vertical center line of the drum. The baffle plates E-l are supported at an acute angle to the horizontal, approximately 20, superjacent the feed pipe 25. The V-bafiile is supported by correspondingly bent plates carried by the feed pipe, which in turn is sup ported at longitudinally spaced points by recessed bars 46 suspended from angle members d5 lay hanger bolts 66. The angle members 35 extend across the drum at about its water line and are carried by bent plates il welded to the drum wall. The hanger bolts 46 are surrounded by spacer sleeves 68 and extend downwardly through the baflie plates M to hold the feed pipe and thereby the V-baiiie fixed in position with the apex of the baiile approximately half way down below the designed water level.

Each of the wing bafiies 58 is formed by per= forated steel plates 5i connected to one side wall of the drum at the designed water level and sloping downwardly to a point below the water level and in approximate vertical alignment with the corresponding outer edge of the V-bafile. The baflie plates 55 have flanged edge portions to permit their connection to one another and to the supporting angle members at. The wing bames terminate short of the full length of the V-bafile and spaces therebeneath are closed at their ends by perforated vertical angle plates 52. The plates 52 partly surround the upper ends of the downcomers 3| and function to separate steam from the water in the drum flowing to the downcomers 3|.

The horizontal center bafiie 60 is formed by perforated flat steel plate sections 6| having upturned flanged edge portions connected to adjacent plates and to the angle members 45 and inner edge portions of the wing baflles 50. The center baiile is arranged below the designed water level, slightly below the inner edges of the wing battles, and extends slightly beyond the ends of the V-baflle. The hanger bolts 46 and sleeves 48 extend through the corresponding plate sections 6|. The sides of the space below the center baille beyond the ends of the wing bames are closed by perforated bent sections of the end plates 52.

The perforations in the baille plates 4|, BI, 52 and GI illustrated are formed by holes V in diameter staggered throughout the plate area and totaling about 25% of the plate area.

Surface blow-off operations can be effected through a horizontally arranged perforated blowoff pipe 10 extending longitudinally of the drum just above the center baflle 60. The pipe III is supported from the angle members 45 by U- bolts l|.-

The drum battle system described has been found to be highly effective for its intended purposes. In one test installation having 4360 sq. ft. of boiler heating surface and a drum pressure of 600 lbs. per sq. in., it was found that when generating 154,596 lbs. of steam per hr. (143% rated capacity) corresponding to 54.5 cu. ft. of steam per minute per sq. ft. of drum water surface, the moisture in the outgoing steam was less than of 1%. Under full power conditions it was found possible to carry' a water level within 1 from the top of the gauge glass with less than 0.6 of 1% moisture in the delivered steam.

In operation, the high velocity streams of steam and water entering the drum impinge upon the feed pipe 25 and V-baiiie to which causes them to be dispersed throughout the width of the drum. Some of the streams are deflected towards the sides of the drum by the inclined arrangement of the V-baffle plates and these streams are obstructed and broken up by the wing baffles 58 before leaving the water space. in view of the low location of the V-bafile and the high velocity steam discharge, some of the streams will pass through the V-baffie perforations at a high velocity and these streams are later obstructed dispersed by the center bafiie. The various submerged batfles thus cooperate to provide a substantially uniform flow of steam from all of the liberating surface of the drum above the con nected tubes in spite of its relatively localized admission to the bottom of the drum. At the same time the larger steam bubbles are broken up and the water separated from the steam.

In Figs. 8-10 is illustrated a modified bafile construction also particularly adapted for use in steam boilers of the type described. In the modi fled construction, the amount of perforated bafile area in the drum I6 is substantially increased and arranged as hereinafter described. The perforated bafiie area of the lower V-shaped baiiie 4B is increased by the addition of, perforated plates 80 and below and above respectively each section thereof. While the plates M are constructed with diameter perforations totaling about 25% of the plate area, it has been found desirable to make the plates 39 and ill with perforations in diameter and totaling about 20% of the plate area. their extent and arranged in contact with the underside of the plates 4| to reduce the effective flow area through the plates 45. The plates 8! have their edge portions similarly bent to form a shallow dish-shaped structure and arranged with The plates 86 are made fiat throughout their bent edge portions in contact with the corresponding plate lH. The perforated body of each plate 8| is held in the spaced relation with the plate 4| described and the plates 40,280 and 8| 5 held assembled by any suitable means, such as the bolts 82. Perforated plates 90 similar in construction to the plates 8| are arranged at opposite sides of each wing baiile plate 5| and each center bafiie plate 6|. The modified baiile construction described has been found to result in a lower moisture content of the steam delivered under similar boiler load and water level conditions than the baffle construction shown in Figs. 17, even with a high solid concentration in the boiler water.

While in accordance with the provisions of the statutes 1 have illustrated and described herein the best forms of the invention now known to 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.

This application is a continuation in part of my prior application Serial No. 169,080, filed Oct. 15, 1937. r

I claim:

i. In a vapor generator, a liquid and vapor 3a drum having vapor generating tubes connected to the lower part thereof, a submerged V-shaped perforated baiiie extending in an upright position across the path of discharge from said vapor generating tubes and having its side edges spaced from the corresponding sides of said drum, and a horizontally arranged baille structure extending across saiddruin above said V-baifle and comprising a plurality of vertically spaced perforate bailles, the total flow area through the uppermost baiiie being 4a less than the total flow area through the sub- ;iacent battle.

2. In a vapor generator, a horizontally arranged liquid and vapor drum having vapor generating tubes connected to the lower part thereof at op- 4d posite sides of the vertical axial plane of said drum,

a submerged V-shaped perforated plate bailie extending in an upright position across the path of discharge from said vapor generating tubes and having its side edges spaced from the correspondliil ing sides of said drum, and a horizontally arranged baffle structure extending across said drum above said V-baflie andcomprising a plurality of norrnally submerged vertically spaced perforated plates, the total flow area through the uppermost 5% plate being less than the total flow area through the subjacent plate.

3. In a steam generator, a horizontally arranged steam and water drum having steam generating tubes connected to the lower part thereof, a sub- Bll merged v shaped perforated baiiie extending in an upright position across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, a pair of wing baffles above and extending 65 across the spaces between said V-bafile and drum wall, and a horizontally arranged baflie extending across said drum above said V-baflle.

l. In a steam generator, a horizontally arranged steam and water drum having steam generating tubes connected to the lower part thereof, a submerged V-shaped perforated baffle extending in an upright position across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said 7 drum, a pair of submerged perforated wing baiiles above and extending'across the spaces between said V-baflle and drum wall, and a horizontally arranged submerged perforated ballie extending across said drum above said V-baille and between said wing baflles. 5 5. In a steam generator, a horizontally arranged steam and water drum having steam generating tubes connected to the lower part thereof, a submerged V-shaped perforated haiile extending in an upright positi'on across the path of discharge 10 from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, a pair of submerged perforated wing bailles above and extending across the spaces between said V-baffle and drum wall, perforated end 15 plates closing said spaces adjacent the ends of said said wing baffles. 20 I 6. In a steam generator, a horizontally arranged steam and water drum having steam generating tubes connected to the lower part thereof, a submerged shallow V-shaped perforated baiile extending in an upright position across the path of 25 discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, a pair of oppositely inclined submerged perforated wing baffies above and ex-- tending across the spaces between said v-baflle and drum wall, and a horizontally arranged submerged perforated sectional baiiie extending across said drum above said V-baflle and between said wing baflies. I

'7. In a steam generator, a horizontally arranged steam and water drum having steam generating tubes connected to the lower part thereof, a submerged V-shaped perforated baflle extending across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, a feed pipe extending longitudinally of said drum below said V-baffle, and means for supporting said V-baffle from said feed pipe.

8. In a steam generator, a horizontally arranged 4,5 steam and water drum having steam generating tubes connected to the lower part thereof, a submerged V-shaped perforated baflie extending across the path of discharge from said steam generating tubes and having its side edges spaced 5d from the corresponding sides of said drum, a feed pipe extending longitudinally of said drum below said V-baille, means for supporting said V-baflle from said feed pipe, supporting members extending across said drum above said V-baflle, and means for supporting said feed pipe from said supporting members.

9. In a steam generator, a horizontally arranged steam and water drum having steam generating tubes connected to the lower part thereof at opposite sides of the vertical axial plane of said drum, a submerged V-shaped perforated baiile extending across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, .a feed pipe extending longitudinally of said drum below said V-bafile, means for supporting said V-baiiie from said feed pipe, and means for supporting said feed pipe including supporting members extending across said drum above said V-baffie, cross-bars receiving said feed pipe, and hanger bolts extending from said supporting members through said V-baflle to said cross-bars.

10. In a vapor generator having a liquid'and vapor drum and vapor generating tubes connected to the lower part thereof, a submerged v-shaped baiile extending in an upright position across the path of discharge from said vapor generating tubes and having its side edges spaced from the corresponding sides of said drum, and a horizontally arranged submerged bailie extending across said drum above said V-baille, each of said bailles comprising a plurality of superposed perforated plates of different total flow areas.

11. In a vapor generator having a horizontally arranged liquid and vapor drum and vapor generating tubes connected to the lower part thereof at opposite sides of the vertical axial plane of said drum, a submerged V-shaped baffle extending in an upright position across the path of discharge from said vapor generating tubes and having its side edges spaced from the corresponding sides of said drum, and a horizontally arranged submerged baiile extending entirely across said drum above said V-bailie, each of said bames comprising a plurality of superposed perforated plates with the perforations in adjacent plates of substantially, different size.

12. In a steam generator having a horizontally arranged steam and water drum and steam generating tubes connected to the lower part thereof, a submerged V-shaped baille extending in an upright position across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, a pair of submerged wing bailles above and extending across the spaces between said V-baille and drum wall, a horizontally arranged submerged central baflle extending across said drum above said V-baflle and between and supported from said wing baflles, and each of said bailles comprising a plurality of superposed vertically spaced perforated plates with the perforations in adjacent plates of substantially different size and substantially the same total flow area.

13. In a steam generator having a horizontally arranged steam and water drum and steam generating tubes connected to the lower part thereof, asubmerged V-shaped baiile extending in an upright position across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, and a pair of submerged wing bailles above and extending across the spaces between said V-baflle and drum wall, each of said wing bailles comprising a plurality of superposed vertically spaced perforated plates.

14. In a steam generator having a horizontally arranged steam and water drum and steam generating tubes connected to the lower part thereof, a submerged V+shaped baflle extending man upright position across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, said bailie comprising a plurality of superposed perforated plates with the perforations in adjacent plates of substantially different size.

15. In a steam generator having a horizontally arranged steam and water drum and steam generating tubes connected to the lower part thereof, a submerged shallow V-shaped perforated baflle extending in an upright position across the path of discharge from said steam generating tubes and having its side edges spaced from the corresponding sides of said drum, said baiile comprising an intermediate perforated plate and a pair of perforated baille members at the upper and lower sides of said plate, said upper baiiie member being arranged in spaced relation and said lower baflle member in contact with said intermediate plate.

THOMAS B. STIILMAN.

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