US2429976A - Vapor generator - Google Patents

Description

Nov. 4., 1947.y

E` G. BAILEY VAPOR GENERATOR Filed March 22, 1944 n I5 Sheets-Sheet 1 A TTORNE Y INVENTOR. ETV/'I7 G Bai/ey Nov. .4, 1-947. E. s. BAILEY VAPOR GENERATOR Filed maren 22, r1944 5 Sheets-Sheet 2 o ooo 00000 ooo OOO

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l VAPOR QENERATOR y Filed March 22, 1944 3 Sheets-Sheet 3 x l l x l l l l l l l l INVENToR. y Ervin G Bai/ey BY A II'ORNE Y Patented Nov. 1947 rviniG. Bailey, Easton, Pa., assgrno'r to The Babcock & Wilcox Company, Rockleigh, N. J., a corporation of New Jersey f Application March 22,1944,4 Serial No. 527,545

The present invention relates to the construction and operation of vapor generating units, and more particularly, to `water tube steam boilers particularly designed for and especially useful in marine installations and including independently fired main and auxiliary furnaceY chambers having a lcommonfheating gas -outlet at the `opposite side of a main bank of steam generating tubes, and a group of steam superheating tubes located whollyor partly between the main and auxiliary furnace chambers and separated from the main furnace chamber by one or more rows of steam generating tubes and/or a partition extending upwardly fora portion of the height of the superheating surface, to shield the same from flame radiation from the main furnace chamber. With this `construction and Yarrangement of the parts, in normal operation the main or saturated furnace is iired at a predetermined rate depending upon the desired rate of steam generation, Vwhile the auxiliary or fsuperheater furnace is fired `at a predetermined rate depending upon the rate of steam generation and the desired final steam temperature.' Y Y During starting-up periods and periods when only saturated or substantially `saturated'final steam temperaturesrare desired, the main fur- Y bank I3-and fired by a group of fluid fuel burnersVA 2| mounted inburner ports 22 inthe frontV nace burners aloneare operated and little or no steam may yulivi/through the superheater. The protection of the 'superheater' duringy such operating periods is particularly important to avoid excessive superheater tube metal temperatures and consequently damaging or yleakage of the superheater tubes. f

The. general object of this inventionfis the provisionof a steam `boiler construction of the character described with improved provisions for protecting the superheater tubes from overheating, particularly when the'main furnace alone is red, without materially ailecting ,the other operating results when both the main'and auxiliary furnaces are in operation.

The various featuresI of novelty whichcharacterize my invention"r are pointed out with particularity inthe claims annexed toV and forming apart of this specification. For ,a better understanding of the invention, its operating advantages and specic objects attained by its use, i

reference shouldbe had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

rOf the drawings:

Fig. 1 is a partly diagrammatic elevation takenk f onthe line .I--I ofFig. 3 offa steam generating von the drum II. Varranged in staggered;rows at opposite sides of 5 Claims. (c1. 122-473) unit ,constructed in accordance with :ny-invention;

Fig. 2 is an enlarged' line 2-2 of Fig. k1;

Y Fig. 3 is an enlarged vertical section taken on the line 3--301 Fig. 1; and

Fig. 4 is an enlargedl plan section taken on the v line 4 4 of Fig. ,1.

Y In the drawings, If have illustrated the invention'as incorporated infa steam generating unit of the type shown in U. S.Patent No. 2,332,534,

and comprising a settingV I0 of rectangular hori-l zontal cross-section, a steam and water drum II,

and a laterally offset lower water drum l2`connected to thedrum rII by an inclined bank of steam generating tubes I3. The tube bank I3extends the full length of the setting between the refractory front wall I4 and rear wall I5 thereof. A heating gas outlet flue economi'zer I9 is'arranged at the outer side of the tube bank. The main 'or saturated furnace chamber "Zlllis located at the inner side of the tube Wan Mi Av secondv water drum or header 25 is located direc'tlybelow the steam drum II and connected` thereto bytransversely spaced groups of ver- Y Y ticallyextending 'steam generating 'tubes26, 21 andj28, The front tubes 21 serve as supports for nes'tedrowsv ofv horizontally arranged' U-shaped superheater tubes 3,0 having their Vends extending through'a metal protecting plate 29 and connec'ted to external vertical inlet and outlet headers 3lv and 32 respectively. The header 3| is Vcon'nectedto a main steam outlet 33 onV the drum Il. Aseparate outlet'34 for withdrawing saturated steam from the -unit is also provided The water tubes 26 and28 are the superheater and extending the full length of the setting.

The auxiliary or suprheater furnace chamber 4l) is located at the outer side of the tube rows 28 and fired by a group of fluid fuel burners 43 Vmounted in burner ports Min the front wall I4.

rZlhe outer side wall of the furnacey chamber 40 has Va rowV of water tubes'll extending from a bottom header 42 to the steam drum II. Downcomer tubes 5 I, 52' and 53 connect the water space of theV drumL II to the drums I2 and 25, and 1 header 42 respectively. Short lcurved tube baffles v55 on the innermost row of tubes'28 close the l spaces betweenfthe upper and lower ends of the superheater tube bank andthe adjacent drums plan sectiontaken on the I8 containing an` and direct the flow of heating gases from the auxiliary furnace across the superheater tubes.

While the staggered rows of tubes 26 provide a tubular screen between the main furnace 20 and the superheater tubes 30, absorbing much of the heat radiation from that furnace chamber while permitting heating gas flow through the tube rows from the auxiliary furnace 40, additional protection is necessary to prevent the superheater tubes from being overheated, particularly when the main furnace alone is fired and saturated steam is withdrawn from the drum Il. In such installations it is customary to use high grade heat resistant alloy` steel tubes for the superheater elements in View of the high temperatures to which such tubes are exposed in normal operation. As shown in said U. S. Patent 2,232,534, a partition or baffle 56 extends upwardly from the drum or header 25, being formed by metallic studs 51 welded along the length of the innermost row 26EL of the tubes 26 and a suitable refractorymaterial, such as plastic chrome ore, closing the intertube portions of the tubes. Stud plates 58 are welded along the outer sides of thetubes 2lia to aid in retaining the refractory material in position. The partition 56 has the studs and refractory material covering the inner face of the tubes throughout the forward portion of its length, while the remaining portion hasv studs and refractory material in the intertube spaces only, as shown in Fig. 3, thus providing a refractory-faced construction in the forward portion of the partition and alternately tube surface and refractory in the rear portion.

Heretofore, the partition has been constructed to terminate throughout its length short of the upper drum II at approximately the level of the center line of the uppermost burner 2 I, leaving a passage thereabove across which unstudded portions of the partition tubes 26a extended and through which the heating gases from the auxiliary furnace 40 flowed across the upper part `of the main furnace 20 and tube bank I3 to the heating gas outlet I8. water tubes 26- and superheater tubes 30 forms a flow equalization spacewhich aids in maintaining a substantially uniform heating gas ow from The space between thel @rating temperatures throughout the operating range of the unit without materially affecting the other operating results. The provisions for this purpose include the extension of predetermined rear portions of the partition 56 upwardly towards the steam and water drum II. As shown in Figs. 2-4, the stud, stud plate and refractory construction on the six rearmost tubes 26a is continued upwardly to the lower side of the drum II to form an upward imperforate partition extension 56a. Similar upward partition extensions 5'5b and 56c are formed between the seventh and eighth and between the ninth and tenth tubes 26e respectively. With this construction unobstructed gas flow passages will remain between the upper portions of the tubes 26"L from the front wall I4 for a major portion of the length of the partition 56 and similar gas flow passages will be present between the sixth and seventh and bethe auxiliary furnace chamber 40 over the length and height of the superheater tube bank.

It has been foundA that when the fuel burners 2l in the main furnace 20 alone are operated and saturated steam withdrawn through the auxiliary steam outlet 34,' the superheater tube metal temperatures, particularly in the superheater tube portions above the level of the partition 56 and adjacent the superheater header protection plate 29 in the rear wall I5, tendto rise above a safe operating temperature, even when the superheater elements are made of high grade heat resistant alloy metal. It is believed that this overheating of the-superheater elements is due to a high temperature gas flow from the rear portion of the main furnace 20 across the water tubes 26 and 28 and superheater tubes 30 into the auxiliary furnace 40, probably due'to a mushrooming effect induced by the impingement of products of combustion from the fuel burners 2| on the opposite portion of the rear wall I5. Thesegases tend to return to the furnace chamber 20 across the forward portion of the water tubes 28 and 26 and superheater tubes 30, forming in effect adoughnut circuit of the heating gases.

In accordance with my invention, the described undesirable heating gas flow can be reduced to an extent affording safe superheater tube metal op;VVV

tween the eighth and ninth tubes 26a from the rear wall I5. The resultant partition construction provides successive increases in the amount of shielding surface for the superheater tubes towards the rear of the main furnace chamber. The exact amount of partition area employed will vary'with the main furnace chamber dimensions. the location and maximum rate of operation of the fuel burners 2|, and designed operating con.

ditions, but in all cases the maximum height over which the partition extends will be at or adjacent to the rear walll.

It is necessary to proportion the stud and stud plate lengths along the rear side of the tube 26a nearest the rear wall I5 to provide a clearance space between the rear end of both the`parti tion 56 and extension 56a and the rear wall I5,l

permitting relative expansion of these parts. The setting of the unit tends to bulge outwardly when the boiler is in operation, thus increasing the size of the clearance space 60. To minimize heating gas flow through the clearance space 60, the rear wall I5 is provided with a refractory corbel 62 along the outer side of the partition and its extension 56a for the entire height of those parts. f

Boilers of the construction described having the described partition construction have been tested with the main or saturated furnace burners alone in operation at capacities up to 68,000 lb. of saturated steam per hour without any portion of the superheater elements exceeding a safe tube metal operating temperature. The vertical extension of the rear portion of the partition acts to minimize mushrooming 'of the heating gases impinging on the rear wall into the space occupied by thesuperheater while not materially affecting the other operating results when either the main or auxiliary furnace burners are operated separately or together. The effect of this partition extension construction 0n the-final superheated steam temperature, air pressure requirements and combustion efficiency under such conditions was found to be negligible.

I claim:

1. A steam generator comprising a setting having front and rear Walls, an upper steam and water drum, a lower water drum, a bank of steam generating tubes connecting said upper and lower drums, a second lower water drum, a group of spaced water tubes connecting the upper drum to said second water drum, a main furnace chamber between said tube bank and 4 said tube group, fuel burning means arranged to effect a flow of heating gases rearwardly of said mainfurnace chamber, a group of spaced superandere' heater tubes adjacent 'the outer side of said tube group, an auxiliary furnacechamber laterally adjoining the outer side of said superheater tubes, means for firing said auxiliary furnaceA lchamber, said superheater tubes being arranged vdirectly in the path of the heating gases'leav-y ing said auxiliary furnace chamber so as toireceive heat mainly byconvection, a single heating gas outlet flue at the outer side of said tube bank and arranged to receive all of the heating gases flowing from both of said furnace charnbers, said flue being so located that the heating.

gases from said auxiliaryfurnace chamber flow across said superheater tubes and substantially all the tubes of said group, through'said main furnace chamber and across saidtube bank before entering'said yflue, and means forrningra4N partition at the superheater side vof said Vmain heater tubes, means for independently firing said auxiliary furnace chamber, said superheater tubes being arranged directly in thepath of the heating/f gases leaving said auxiliary furnace chamber so vas to receive heat mainly by convection, a lsingle heating gas outlet flue at the outer side ofsaid tube bank and arranged to receive all of Vthe heating gases flowing from both of said furnace-chambers, said ue being so located that the heating gases from said auxiliary furnace cham'berflowzacross said superheater tubes 'i andsubstantially all of the tubes of said tube furnace chamber extending substantially ,theY

full length thereof, the portion of said partition `adjacent said rear wall extending upwardly from approximately said secondwater drum to saidgy 'upper drum and arranged to obstruct heating gas ,j

flow from said main furnace chamber across ad'- jacent tubes of said tube group and towards said superheater tubes. l 1,.

2V. A steam generator comprising a setting having front and rear walls, an upper steam and water drum, a lower water drum, a bank of steam generating tubes connecting said upper and lower drums, a second lower water drum, a groupv of spaced water tubes connecting the upperdrum to said second water drum, a main furnace chamber between said tube bank' and said tube group, fuel burning means arranged to effect a flow of heating gases rearwardly of said'main vfurnace chamber, a group of spacedjsuperheater tubes adjacent the outer side of said tube group, an auxiliary furnace chamber laterally adjoining the outer side of said superheater tubes, means for firing said auxiliary furnace chamber, said superheater tubes being arranged directly in the path. of the heating gases leaving said auxiliary furnace chamber so as to receive heat mainly by convection, a single heating gas outlet flue at the outer side of said tube bank and arranged to receive all of the'heating gases flowing from both of said furnace chambers, said flue being so located that the heating gases from said auxiliary furnacechamber flow across said superheater tubesand substantially all of the tubes of Vsaid tube group, through said main fur-A `nace chamber and across said tube bank before entering said flue, and means forming a partition at the superheater side of and extending longigrouppthroughl said mainfurnace chamber and across said'jtubebankbefore :entering said flue, and meansj'including tubes ofsaid tube group forminga'fflui'dl'cooled v'partition vat the supertudinally substantially the full length of said f main furnace chamber, the forward section of said partition being arranged to direct the heating gas flow from said auxiliary furnacechamber across the upper part of said main furnace chamber, and the rear portion of said partition adjacent said rear wall being extended upwardly a sub-i stantial distance towards said upper drum and arranged t0 obstruct any heating gas flow from said main furnace chamber across the adjacent tubes of said tube group and towards said superheater tubes.

3. A steam generator comprising a setting hav` ing front and rear walls, an upperfsteam and water drum, a, lower water drum, a bank of steam generating tubes connecting said upper and lower drums, a second lower water drum, a group of spaced water tubes connecting the upper drinn heater gside vof andl extending longitudinally substantially thefuu Iengrh'of said mainrumace f chamber, the Yforward section of said partitionV extending upwardly for part of the length of the tubes in said tube group and arranged to direct the heating gas flow from said auxiliary furnace chamber across the upper part of said main fur-v nace chamber and to4 shield said superheater tubes from flame radiation from said main furnace chamber, and the portion of said partition adjacent said rear wall being extended upwardly to said upper drum and arranged to obstruct heating gas flow from said main furnace cham-` ber across the adjacent tubes of said tube group and towards said superheater tubes.

4. A steam generator comprising a setting having front and rear walls, an upper steam and water drum, a lower water drum, a bank of steam generating tubes connecting said upper and lower drums, a second lower water drum, a group of spaced water tubes connecting the upper drum to said second water drum, a main furnace chamber between said tube bank and said tube group, fuel burning means arranged to effect a ow of heating gases rearwardly of said main furnace chamber, a group of spaced superheater tubes adjacent the outer side of said tube group',

an auxiliary furnace chamber laterally Aadjoining'the outer side of said superheater tubes, means for firing said auxiliary furnace chamber, said superheater tubes being arranged directly in the path of the heating gases leaving said auxiliary furnace chamber so as to receive heat mainly by convection, a single heating gas outlet Vflue at the outer side of said tube bank and arranged to receive all of the heating gases flowing from both of said furnace chambers, said ue being so located that the heating gases, from said auxiliary furnace chamber flow across said superheater tubes and substantially all of the tubes of said ,tube group, through said main y furnace chamber and across said tube bank before entering said ue, and means forming a partition at Vthe superheater side of said main furnace chamber extending substantially the full f length thereof, the portion of said partition adto said second water drum, a main furnace chaml .iacentsaid rear wall extending upwardly from approximately said second water drum to said upper drum, and a corbel on saidrear Wall atthe outer side of said partition and cooperating therewith to obstruct heating gas flow from said main furnace chamber across the adjacent tn bes of said tube group and towards said superheater tubes.

5. A steam generator comprising a setting having front and rear walls, an upper steam and water drum, a lower water drum, a bank of steam generating tubes connecting said upper and lower drums, a second lower water drum, a group of spaced water tubes connecting the upper drum to said second water drum, a main furnace chamber between said tube bank and said tube group, fuel burning means arranged to effect a ow of heating gases rearwardly of said main furnace chamber, a group of spaced superheater tubes adjacent the outer side of said tube group, an auxiliary furnace chamber laterally adjoining the outer side of said superheater tubes, means for firing said auxiliary furnace chamber, said superheater tube group extending substantially the entire length of said auxiliary furnace chamber and arranged directly in the path of the heating gases therefrom so as to receive heat mainly by convection, a single heating gas outlet ue at the outer side of said tube bank and arranged to receive `all of the heating gases owing from both of said furnace chambers, said flue being so located that the heating gases from said auxiliary furnace chamber flow across said superheater tubes and substantially all the tubes of said tube REFERENCES CITED The following references are of record in the le of this patent: b

Y UNITED STATES PATENTS Name Date Schoenfeld May 2, 1944 Rooney Oct. 26, 1943 Jacobus Feb. 3, 1942 Colven Oct. 25, 1921 Kuhner May 16, 1939 FOREIGN PATENTS Country Date Great Britain July 16, 1941 Number Number

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