US2332508A - Steam generator - Google Patents

Description

Oct. 26, 1943. G. H.. DANIELS STEAM GENERATOR Filed Sept. 7, 1938 N 0)."; I Vi I WW. Georg Patented Oct. 26,1943 I I V I UNITED [STATES e-A'r STEAM GENERATOR George H. Daniels, Westfield,.N. J-., assignor to Q I The Babcock & Wilcox Company, N ewark, N. J., acorporation of New Jersey Application September 7, 1938Q'SerialNo. 228,747

' r -2 Claims. (or. 122-473 The present invention relates to the construction and operation of steam generating units, and more particularly, to water tube steam boilers particularly designed for and especially -useful in marine installations.

Steam generating installations in the marine field are characterized by relative lowspace, weight, headroom andother limitations, all contributing towards an extremely compact'lightweight generator design without sacrifice: of efficiency requiring a minimum of special construction of the surroundingship structure. The recent trend in this field towards units adapted to generate high pressure high temperature" steam with relatively high superheat temperatures controllable over a wide range, even to zero superheat, has substantially increased the probe lems of design and construction. One-such unit involves the use of a separately fired auxiliary furnace chamber in the same setting for regulably heating the steam superheating surface. To reduce the space requirements of'the unit and ship adaptation to it and to more cffectively utilize the heating gasesfro'r'r'i the aux-,

furnace through the main furnace chamber tends to interfere with the combustion infthe'main' furnace chamber due to the consequent introduction of a substantial amount of relatively cold inert gases therein.

, The main object of my invention is the provision of an improved construction of a steam generating unitof the general type described which is particularly characterized by its compactness, effective superheat control over awide range, advantageous" -combustion conditions -in' are connected to external inclined headers?! both the main and auxiliary furnaces, and highoverall efficiency. g

The various features'of novelty which characterize my invention are pointed out with par-.

ticularity in the claims annexed to and forming a part of this specification. For a better under standing of the invention, its operating advantages and specific objects attained'by' its use,

reference should be had to; the accompanying drawing and descriptive matter-in which I have illustrated and described a preferred b g ment of my invention. 1 4 v I Of the drawing:

Fig. 1 is a partly diagrammatic sectional elevation of a steam generatijngunit' constructed in accordance with-my invention; and

Fig. 2 is a section'taken on the linZ-Z of Fig. 1. I. g r

The steam generating unit illustrated "co prisesa setting ill enclosing a relatively wide bank of inclined steam generatingtubes Il ex. tending between a lower'waterdrum i2and an upper steamjand water drum l3 laterally offset from and of substantially larger diameter than the drum [2. At the opposite'side of the setting is arranged a bank of inclined steam generating tubes l lextending between thedrum i3 and a lower Water drum [5. The tube "banlgs'yil and M define, therebetween an A-shaped space closed at its endsby the vertical end walls'of'the setting, and extending downwardly to a refractory bottom pan [6 below the levelof the drums l2 and 15. The setting is provided'with a single heating'gas outlet flue I l at the outer side of the tube bank 'I l, i. e. the side opposite the 'A-shaped space, and adjacent to the steam and water drum 53. A bank'of economizei' or air heater i8 is positioned in'the outlet flue ll.

Inaccordance with my invention the tube bank 54 is divided into three'spaced groups of water tubes I4 M and M The group l t contains only a relatively few rows of tubes at the inner side of the bank andserves as a waterscreenfor a superheater hereinafter described. The tubes M are of larger diameter than thetube's' It? or M and'are,arrangedin a single row intermediateithose groups. "The tubes l l also serve as. supports for an' inclined bank of U- shaped steam superheating tubes 29 extending transversely of theltube bank I4 in the lowerportion of the space between the tube groups M and M The ends of thew-shaped superheater'tubes and'22; with the header 2! arrangedfto' receive saturated steam from the steam and water drum i3 through pipes-23. The tubesf i lare" of some,-

what l'."-sh'ape,- and arranged toextend along and support the correspondingside'w'all 'of'th'e setting Hl. The tube group M also has only a few rows and is arranged withthe longer legs of the tubes substantially spaced from the superheatentubes 20. I

' The A-shaped space between thatube banks H and I4 serves' as'the combu's'tionspaceofthe unit,"and isfplefiablY divided i lito a ln lilr fur nace chamber 25 and an auxiliary furnace chamber 26 by a row of tubes 21 extending from a header 28 to the drum l3. The header 28 is arranged along the bottom l6 below the steam and water drum l3 and connected by supply tubes 29 to the drum IS. The tubes 21 are bent laterally at an intermediate point towards the tubes l4 and extend upwardly along the inner side of the same from a point adjacent the upper end of superheater tubes 20. The tubes 21 are fully studded, as shown in Fig. 2, for a portion of their length and the studs covered and intertube spaces 7 header 28 to the tube bank It at a point adjacent I the upper end of the superheater. A metallic baffle 32 extends laterally from the upper end of the partition across the tubes M and N along the upper end of the superheater tube group, ter minating at the outer side of the superheater. The main furnace chamber is fired by a group of fluid fuel burners 35 arranged to discharge longitudinally thereof through corresponding burner ports 36 located in one of the end walls of the setting. The auxiliary furnace chamber 26 is fired by similarly arrangedindependently operable fluid fuel burners 31 through burner ports 38. The burners 31 can be operated as desired to control the superheat temperatures over a relatively wide range, either automatically or manually, suitable automatic mechanism for this purpose being well known. As an alternative the boiler can be operated to produce saturated steam and without superheating it by using the mai furnace chamber 25, and not using the auxiliary furnace chamber 26.

With the described construction the steam generating unit is started up with only main furnace chamber burners 35 in use. The heating gases generated by the fuel burning in suspension flow transversely of the tube bank I I to the gas outlet flue ll, passing over the economize; tubes is before leaving the unit. During the starting-up period the fluid-cooled partition 3! forms an effective radiant heat shield between the main furnace chamber and the auxiliary furnace chamber and its associated parts, particularly the superheater tubes 29. With steamflowing through the superheater tubes, the auxiliary furnace chamber burners 31 are put into operation. The heating gases generated in the auxiliary furnace chamber flow upwardly across the screen tubes i4 and superheater tubes 29, the flow path in this section being defined by the setting walls, the partition 3!, and bafile 32,, Aiter leaving the superheater tubes 20 the gases flow around the upper end of the baffle 32 while contacting with the tubes H. The space between the superheater tubes and tubes [4 serves as a gas flow equalization and turning space, permitting a reversal in direction of the gas flow with a relatively low pressure drop. The gases on rounding the bafiie 32 flow across the upper portions of the tubes M I la, and 2'1. The heating gases from the auxiliary furnace chamber then flow across the upper portion of the main furnace h m nd upper part of the tube bank, Ii to the gas outletfiue i1.

The described flow path of the auxiliary furnace gases insures an efficient use of the heat values thereof, and a minimum interference thereby with the combustion conditions-in the main furnace chamber. The described steam generating unit with its integrally arranged innd single,

gas outlet provides an extremely compact structure having relatively low floor space and head room requirements. The construction and arrangement of the main and auxiliary furnace chambers permits the maintenance therein of combustion conditions contributing to a high thermal eificiency of the unit. The arrangement of the auxiliary furnace chamber and its associated parts insures effective control of superheat conditions over a wide range and with a I high upper limit.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form 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.

I claim:

1. A steam generator comprising a setting, an upper steam and water drum, a pair of spaced lower water drums, a bank of inclined steam generating tubes connecting said upper drum to one of said lower drums, a group of steam generating screen tubes connecting the upper drum to the other of said water drums, a vertically arranged partition arranged to divide the space between said tube bank and said screen tube group into a main furnace chamber and a laterally adjoining auxiliary furnace chamber, the portion of said group of screen tubes extending throughout one side of said auxiliary furnace chamber being unobstructed, means for firing said main furnace chamber, a group of superheater tubes extending along the outer side of said unobstructed portion of said screen tube group and of said auxiliary furnace chamber, means for independently firing said auxiliary furnace chamber, 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 furnace chamber flow over said unobstructed screen tube group portion, superheater tubes. and tube bank and across said main furnace chamber before entering said flue, and said partition terminating below said upper drum and arranged to direct the heating gas flow from said auxiliary furnace chamber over said superheater tubes and into the upper part of said main furnace chamber and to shield said super-heater tubes from flame radiation from said main furnace chamber.

2. A steam generator comprising a setting, an upper steam and water drum, a pair of spaced lower water drums at substantially the same level, a bank of inclined steam generating tubes connecting said upper drum to one of said lower drums, a group of inclined steam generating screen tubes connecting the upper drum to the other of said water drums, a vertically arranged fluid cooled partition arranged to divide the space between said tube bank and said screen tube group into a main furnace chamber and a laterally adjoining auxiliary furnace chamber, the portion of said group of screen tubes ex tending throughout one side of said auxiliary furnace chamber being unobstructed, means for firing said main furnace chamber, a group of horizontally arranged superheater tubes extendn e .n .i1w Pa e s P s n b t cted.

portion of said screen tube group and of sald auxiliary furnace chamber, means for independently firing said auxiliary furnace chamber, a

single heating gas outlet fiueat the outer side of said tube bank and arranged to receive all a of the'heating gases flowing from both offsaid furnace chambers; said flue being so located that the heating gases from said auxiliary furnace chamber flow over said unobstructed screen tube group portion, superheater tubes-and tube bank 1 2,332,508 a 3 and across said main furnace chamber beforeentering said flue, and said fluid-cooled partition terminating below said upper drum and arranged to direct the heating gas flow from said auxiliary furnace chamber over said superheater tubes and into the upper part of said main furnace cham-s I her and to shield said superheater' tubes from flame radiation from said main furnace chamber. s

GEORGE H. DANIELS.

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