US2669976A - Apparatus for generating vapor - Google Patents

Description

5 Sheets-Sheet l Filed April 29, 1949 INVENTOR /Y/iW/-e/sc/f ATTQRN EQ APRARATUS FOR GENERATING VAPOR Filed April 29, 1949 5 sheets-sheet 2 INVENTGR f7; er/N Fe/.scm

ATTORNEY Feb. 23, 1954 M. FRlscH 2,669,976

APPARATUS FOR` GENERATING VAPOR FiledApril 29, 1949 5 Sheets-Sheet 5 FebQzs, 1954 Filed April 29, 1949 M. FRlscH- 2,669,976

APPARATUS Foa GENERATING vAPoR 5 Sheets-Sheet 4 AAA Lm ffy.

BY Q/WMM ATTORNE A en. 23, 1954 M. FRISCH APPARATUS Ho?, GENERATING VAPOR 5 Sheets-Sheet 5 Filed April 29, 1949 W m A m m L m m WG @INN @t WU A [nwH m C r #sms w mwmrm G E A W M W n w 5 W. v w a R. H /M/ MA 2.a 5 B 0 0 JM. D wm IIL /'B O O Fig. 7 is an enlarged fragmentary sectional view of the upper part of Fig. 4;

Fig. B is a View similar to Fig. 6 but taken on the line 8 8 0f Fig. 4;

Fig. 9 is a View similar to Fig. 8 but of anotherV embodiment of the invention;

Fig. 10 is a perspective view of the steam and water drum of the primary section of the present invention with parts thereof broken away, and

Fig. 11 is a chart showing a group of curves which illustrate graphically operating characteristics of the steam generator of the present invention.

Like characters of reference refer to the same or similar parts throughout the several views.

Referring to the drawings, Figs. 1-3, the steam generator of the present invention comprises a setting I having therein a combustion chamber I I` with a front wall I2, a rear wall I3 and opposite side walls I4 and I5. The front wall I2 is inclined inwardly at the opposite ends thereof to form a roof portion I6 at the top thereof and a bottom portion I 'I at the bottom thereof. Rear wall I3 is inclined inwardly at the top thereof toward chamber I I at an elevation lower than side wall I2 to thereby form another roof portion I8 which roof portion extends upwardly to a point short of roof I6 thereby forming a gas outlet I9 at the top and rear of chamber II. Wall I3`, like' wall I2, has an inclined bottom 25, the bottom portions I1 and 20 of front and rear walls I2 and I3 respectively thereby forming a hopper bottom to chamber I I.

The primary high duty heat absorbing section of the vapor generator of the present invention comprises an upper steam and water drum 2| disposed above roof portion I which drum has water wall riser connecting tubes 22 in communication therewith and extending downwardly to connect with header 23. vOpposite side walls I4 and I5 are lined respectively with water wall tubes 24 and 25. The tubes 24 communicate at the top thereof with header 23, while the tubes 25 are incommunication at the upper end thereof with a header 25 similar to header 23. VRiser tubes 2'I are connected with header 25 and drum 2l, as shown in Fig. 2. Front wall I2, including roof I6 and bottom portion II, is lined with water wall riser tubes 28, while rearward wall I3, including roof portion I8 and bottom 2D, is lined with water wall riser tubes 29, the tubes 29 extending across outlet I9 at the top thereof and communicating with drum 2 I. The lower end of tubes 28 and 29 communicates respectively with headers 3l) and 3| adjacent the bottom of portions I'I and 25. A plurality of downcomer tubes 32 are connected at one end thereof with the lowermost portion of drum 2I and at the opposite end thereof with downcomer ,header 33. Main downcomer conduits 34 and 34' (Figs. 2 and 3), adjacent the outer side of side walls I4 and I5 respectively, connect at the top thereof with header 33 and extend downwardly to a point below and centrally of bottom portions I'I and 20, as Ashown in Fig. l. Downcomer conduits 34 and 34' are in communication at the lower end thereof with header 30 through tubes 35 and with some of riser tubes 28 through conduits 35 and with header 3l through conduits 3l' and some of water wall tubes 29 through conduits 38. At the lower end thereof, downcomers 34 and 34 each communicate with lower transverse headers which lower headers are respectively adjacent the bottom of side walls I4 and I5. Water wall tubes 24 and water wall tubes 25, which line wall I4 and wall I5 respectively, communicate with transverse headers 4D disposed adjacent to and above headers 39. Headers 40 in turn communicate through tubes 4I with the adjacent transverse header 39. Transverse headers 39 are in communication with header 3l through a plurality of tubes 42, while header 30 and transverse headers 39 communicate with one another through a plurality of tubes 43.

As shown, chamber I I is fired through an opening 44 in side wall I3 by a burner 55 which re ceives air for combustion through air conduit 45.

A low duty secondary steam generating section which is subjected to relatively low rates of heat absorption by combustion gases flowing in convection heat exchange relationship therewith is positioned rearwardly of wall I3 of the primary section and in the path' of flow of gases passingl from furnace chamber I I through outlet I9 to iiue 4l, as will hereinafter be fully described. The secondary section comprises an upper steam and water drum 4S of smaller diameter than drum EI and a lower water drum 49 positioned below drum 48 in spaced relationship thereto and in substantial vertical alignment therewith. Drums 48 and 49 are in communication with one another through a forward tube bank 50 and a rearward tube bank 5I. The banks 50 and 5I each comprise a plurality of riser tubes, while drum d8 communicates with lower drum 49 through downcomers 48', positioned outside and closely adjacent to walls I4 and I5 respectively. The secondary section is blown-down through blowdown connection 49 which communicates with lower drum 49. The upper portions of drums 2I and 48 are in communication with one another through steam circulating tubes 52.

Feed for the secondary section is supplied by continuous blow-down from the primary section by means of a plurality of conduits 'IIl which are in communication at one end thereof with the lower portion of drum 2l and at the opposite end thereof with headers ll, which headers project downwardly from opposite ends of drum 42 outwardly respectively of side walls I4 and I5.

As shown, a forward superheater section 53 and a rearward superheater section 54 are positioned in the space between gas outlet I9 and tube bank 5U. Rearward superheater section 54 is connected at the inlet thereof with superheater inlet header 55 by conduit 56 and at the outlet 5'I thereof, which outlet is in communication with intermediate superheater header 58. superheater section 53 is in communication at the inlet 59 thereof with intermediate header 5B and at the outlet thereof with outlet header 6B. Outlet 60 has an off-take pipe 6I which supplies steam to a turbinev or any other point of use, while inlet header 55 communicates with drum 2| through saturated steam outlet conduit 52. superheater headers 55, 58 and 60 are supported from a grinder 63 by hangers 64. superheater section 54 is positioned in a passage 65 separated from the main passage between outlet I9 and flue 41 by baies 66 and 61. Passage 65 has superheat con-l trol dampers 68 positined in openings |69 in the Si.l upper of seiepesse te ceetecl. the .et eases ever superheetin etten. .5.1.

Air. peesiiiethieeeh intese. ceiidcttle islieetee by arieh' heeteit-lzfiniwhieheeses cwingfthte conduit 4l andi ein pessimethitciiehA echelle.; et flew ih indirect heeft exelielieeteletienshin with one another.

Steern. niiet to pessime from the Stettinv geen crater in the eteseiit liivesf-itice,` tteetee te eliminate mec'hanicallizenteeieeel moistwce eet-1 tying.- eissel-vecl chemicelst. mecheeice sus: pendent tine particles ef solid me.t.t.e1 condense es. solids elle-.comm de dieliletl. the steam which have beccme etifstellieeet. Such treatment is. eccelle..lelisl-ied.Y bsfeepeiretiisaeelit eetl. irl d-rlirey 2.! cf the. primer@ sectiene s. mete: eerticuletls'l irl Figs ete le incl .fve.. steam drum per-titieriedte fermsteemreceivl .ne chambers adjacent. the lhiievperiphery eff; the

bye. pertitiort wh h1 ceieptlsee. side.. elet-.es

1.3A and 1:4; spaced. isere theinneeee ehery et the drum. et the eppcsite sides thereet end. en: tend; .longitudinally ef seid.. @tu tc. peints. sheet ci. the. opposite.- enes theifeel elle `letelecllt spaced relationship to one another. le and le eech. lieve upper hertzien l5,v end.Y lli respectively which. extends inwardly ci; the Luni enel ere seciilfed te the; letieituii; fillyhis bers, 'll and t8 tesinecth/eier.y bylcelts; le. end. 8,3.. The bets .ll end. 'I3l ere secliieti, te the l periphery et the. etten. ley Welding (Fie- 7).. Pettit/ien. plates.` 1.3; end 1:4y elec lieve ieWeidl-y in.- clilied. betteln. port et erle e2 inclined. ih-Y tzerdly trom. .the peripheral.. sliiiece ef the diete and. in. spaced. relation: .ip therete.. l tem vertices. ere simile... to the. tcp ee. and, le and ere. secured; te leneitiieiiielly exten-df.. ine meuntine memlcets 83: elle. e4.. :espectively- A. partition plete 8.5. ef: substantially 'the seme length es: plates 13 .end lilV extends tudinelly 0f: the drum 'sneced relationship with` the ner periphery thereof et. the betteln, the -eppesite sides; ci platev l8.5 hei-ne secured, te member-s 8.3 and 8:4 respectivelsf..

Steam condensing chambers 86 and gl are' formed adieeent the unpetx leert ef .plates te end i6. end between seid. -pletes4 end. the periph: ery ef drum 2:( et. epnesite sides efl the difetti. by metal parti-tien. members 8.8 ene 8.9... The .e

tion members Sli ere secured et. ene. eed t ereef t0 Partition 'l5 helen7 the inclined .per thezeef and extend trenetersely ef.: the drum te the in,.- ner per-ileherev therecf and upwardly ehm-f. seid ihr-.1er .periphery t0 e peint adjacent mem-ber H thereafter te ier-eject; inwardly, thence upwardly .ehe secured. te the member ll les belt le. pertitien member 89 is similer to. the partities member 88. end. is lsecueecl at ene. .eee thereof to :partition IG enel. at the appesi-te :end te ymenllcei 13 hy belt ell. in. this manner., steam condensing i chambers 36 end el eee termed, which. chambers extend leheitudhielly et the drum adjacent ep. posit@ sides theizeet so that the chambers a and A37! neeeve steam -rom drflllll 481-1of the seeondgry sectien through tehes. 152. These lccnfleneiee The eletes eee . het eeliet ce eetheetes ice .tee te @tutti 2.1. theeueh. e e

12e ef erf-tese eeedelts. el .elle eeexteiitll s th t elleeesee .elle eeetliet iii e few ch extends longitudinally et. eeft., ieii pletes stehe le. As shown .leise Oneeste :side lele-tes il!! and. e. rel plete 1.0.3 eri/d the perte tions 13 end Vlil. t. .iii the eeeesite end plete of sete. ieesee. The seneretiiie heises ere substan- :section ene have. a steam iitletslet e4 et crieI side. theieef adjacent the .ii e te lll. through which steam s. 90 and. 9i .enters the lcaXes el! ane. vely lil-eee is injected 'iii-te heices te e cl. lill! teiieentielly thereof through so vthat 4eaeh bex receives iedeteriiiined fifeetfien .et ,tige getale e '-13 xes. .3S nenni te@ have .teem eutlets lsl. .eed lll leespectively-et the een h .le :steilen :messes inte spaces l vlzhe sneees ,Ille .end the -uieper spoietton ef elitimeei l. threiieh dryers H2 tane il lf3. which esshewh erect tlie tl/Pe- Eeeh fctfthese emprise .a plurality ofy laterally. ad in, ang llong-rtuelingliy. extending :rows -eaeht of which has a mlunality of :uertiafly extending '-harliz'on'- tally spaced V-shaped plates which Vare"posi tioned in said row with the apex edge of one plate within the area bounded by the next adjacent plate in the row. The separating boxes 99 and are open at the bottom thereof and in communication with the lower portion of chamber As shown in Fig. 8, the boxes 99 and |00 have a circular liner ||4, while in Fig. 9 the box isof a rectangular cross section without a liner.v

Feed water is projected from off- takes 91 and 98 into condensing chambers 86 and 81 respectively through outlet nozzles and H6, said water impinging on hooked-shaped baiile plates ||1 and ||8. The baille plates extend longitudinally of chambers 85 and 81 andare so positioned as to direct the feed water downwardly into the chambers. Water from condensing chambers 05 and 81 iiows into chamber from the ends of said condensing chambers.

` In operation, steam is generated in the primary high duty section of the steam generator of the present invention through the circulation of water from chamber in drum 2| downwardly through openings in partition 85, through passage |2| into downcomer tubes 32, thence into header 33 thereafter to pass into main downcomer conduits 34 and 34. From main downcomer conduits 34' and 34', the 'feed water flows into headers 30 and 3| through tubes 35 and conduits 31 respectively and from headers 30 and 3| into lower transverse header 39 through the plurality of tubes 42 and y43 and from header 39 to transverse header 40 through tubes 4|. From transverse header 40, feed water enters water wall tubes 24 and 25. Water wall tubes 28 and 29 receive feed water from downcomers 34 and 34 through conduits 36 and 38 respectively'and also from headers 30 and 3|.

Steam is generated in the tubes 24, '25, 28 and 29 respectively by the passage of gases of combustion in chamber in indirect-heat exchange relationship with said tubes.A The mixture of steam and water from these tubes enters chambers 90 and 9| of drum 2|, said mixture from water wall tubes 28 and 29 flowing directly to chamber 90, while the steamv and water mixture from tubes 24 and 25 passes into upper headers 23 thence to chamber 9| through tubes 22 and into chamber 90 through tubes 22.

The steam and water entering chambers 90 and 9| is centrifuged and some of the steam is condensed in separating boxes 99 and |00 respectively, the steam entering the boxes through slots |04 therein. Feed water from feed water pipe 96 flows into boxes 99 and |00 through slots |04 therein, said feed water flowing from feed pipe 95 through off-takes 91 and nozzles |05 into boxes 99 and into boxes |00 through off-takes 98 and nozzles |06. Steam and water mixture from chamber 90 together with feed water from nozzles |05 flows into boxes 99 tangentially thereof while steam and 'water mixture from chamber 9| with feed water from nozzles |06 passes into boxes |00 tangentially thereof .thereby whirlingor centrifuging the mixture and the feed water. The feed water is heated to saturation by being brought into direct heat exchange relationship with the steam and water mixture and the condensation of part of the steam. Centrifuging or whirling of the steam and water mixture together with the feed water also separates the :steam and the water andthe-'en- -trained -moisture and any entrained substance of higher specific gravity than the steam :from

8 saidsteam. vThe separated steam, which is of lighter specific gravity than the feed water and any entrained moisture or substance, flows upwardly from the center of boxes 99 and |00 through steam outlets |01 and |08 respectively. The separated steam from boxes 99 enters space |09 and the steam is directed by inwardly 'inclined portion 15 of plate 13 towards chevron dryer ||2 through which the steam passes and is dried by flowing through the spaces between the plurality of plates comprising the dryer. The separated water from boxes 99 passes downwardly along inwardly inclined portion 8| of plate 13 into chamber and the moisture separated from the steam in dryer ||2 also flows downwardly into said chamber. The separated steam from boxes |00 ows upwardly therefrom through outlets |08 and is directed by inclined portion 18 of partition plate 14 into chevron dryer I 3, while the separated water flows downwardly from boxes |00 into chamber Since chambers 9| and 90 are in communication with one another through lower passage 92, the steam from one of said chambers may pass tothe other chamber. f

When circular liners are used in boxes 99 and |00, as shown in Figs. 4, 6 and 8, the mixture of steam and water and the feed water is guided in a circular path by the liner ||4. However, when a square box is used, as shown in Fig. 9, steam free water is forced into the corners of the boxes and drained to the chamber l along said corners without re-entraining steam because of the increased pressure which results from the conversion of the velocity head of the whirling water into a static head in the corners. The separated steam passes to the whirling core of the mixture of feed water and steam and water and leaves the boxes through openings |01 or |08.

By treating the steam and water mixture and the feed water in boxes 99 and |00 as hereinabove described, dry steam only enters chamber l I and heated feed water passes into said chamber thereafter to flow into downcomers 32, 34, 34 and 10.

yThe primary section is continuously blowndown to the secondary section through downcomers 10, the blow-down entering headers 1| which communicate with upper drum 48 of the secondary,` section. From drum 48 the feed water, which is highly concentrated, flows downwardly to lower drum 49 through downcomers 48. Forward tube bank 50 and rearward tube bank 5|, which comprise riser tubes, receive feed from drum 49, steam being generated in said banks by the passage of gases in convection heat exchange relationship with the tubes thereof. The gases prior to flowing over banks 50 and 5| pass through gas outlet 9 over the upper portion ofvtubes 29 thence in convection heat exchange relationship with superheater section 59. If superheater control dampers 68 are opened, as shown in Fig. 1, gases will pass upwardly in passage 65 over superheater section 54 thence through openings 69 thereafter to ow downwardly prior to passing over banks 50 and 5|. The secondary section is blown-down through blow-down connection' 49. Steamgenerated in the secondary section flows from drum 48 through steam circulating tubes 52 into condensing chambers 86 and 81. Steam from tubes 52 is condensed by passing in direct heat exchange relationship with the remaining portion of the feed'water flowing from off- takes 91 and 98 into theV condensing chambers' through nozzles ||5 9 and 'H6 respectively. The feed water from nozzles H and lH6 is ldirected Adownwardlyin a sheet in front of the outlets of tubes 52. 7Be cause of the high heat transfer rates through the direct contact of the feed water-sheets and the steam from the secondary rdrum, the steam will be completely condensed and the vaporized silica or other solute contained in the steamiwill go back into solution .in the condensate. 4Corrdensate from the chambers 18E and "87 drains downwardly into the feed water 'in -fchamber H i.

By heating the vfeed water `to -'saturation through condensing steam therewith in iboxe's $9 and mi) prior to the entry-of feed water into the downcomers, it is possible to maintain subcooling in the downcomers t'o a minimum. 'This is graphically illustrated in the *upper portion rfoi the `chart shown in Fig. 11, 'wherein the uppermost curve of the chart illustrates 'theftotal foirculation within drum 2l of the primary section, while the upper dot-land'd'a'sh -line and the y dotted line therebelow illustrate fthe lmaximum subcooling in the downcomersof the 'primary section and the 'anticipated 'subcooling vtherein respectively.

The lower Aportion of the chart of Fig. 1l graphically illustratesrelationships between the total output of the boiler of the present invention to the steam `actually generated therein, total feed to the boiler, which includes fa 15% allowance Afor blow-down, =to the feed required vrto condense the v'steam from the v'secondary section and the '-feed actually-supplied to the condensing compartments, the steam fgenerated by r"the -secondary 'section and fthe fstea'm required vlte 'heat all 'the feed to thevcondensing'sectiontof'saturation temperature. Referring 'to the chart, vthe line A indicates 4the total evaporation of the steam i-ge'ne'rator of the 'present invention, -While the dotted line B indicatesst'eam from-drum 718, while the distance between #lines A and B, for example, line C, .designates thels'team actually generated in the steamfgen'erator. yllliine lDindicates Ithe total feed waterifedit'o -thefb'oiler including %val1owance for blow-down, Whil'elineE designates the feed to vcondensingfchampers$6 and 81. The vertical distance between lines-l2) and for example, line-Rindicate's' thefffeedu'sed in boxes @9 and H10. lLine"G-@illustratesltheieed required to condense steam from drum "48, while the space between lineslE and G, A'for example, line H, shows excesslfeed--t'ofcondensinglehambers 8S and 81. Line II `shows the vsteam required 'to heat'the feed .water'usedin vcondensing chambers 86'and 8l to saturation, lwhile -the fspa'c'e between lines I'and B, `ior example, lineJ, illustrates-the excess steam required `.toiheatithe lfeed Awaterhused in the condensersto saturation..

`'Although the `.invention has `been Idisclosed vas applied to the generation 'of jsteam, Av1it fis -not limited thereto vbut .is fcapable Yof application to the generation yof vapors generally.

From the foregoing, zit 'will "be lperceived 'that by utilizing Vthe method and apparatus "o'f the present invention, v.puresteam Athatzis, steam free of dissolved or Lvaporizedlsolutes is `producedTand concentration 'of ydissolved solids `-in 'Ith'e lboil'r water of a steam'generator 'is controlled. I'Also, sub-cooling of the downcomersof steam-generator embodyingthepresent inventionzisaprevent'ed. -It will .be understood 'that vchanges may she made in 1 the form, location and "relative "arrangementof the several rparts of the rapparatusdisclosed, and Vin Vthe 'sequence /of the :steps 1- of the method disclosed, Without departing'. from lthe 10 principles ofthe invention. Accordingly, the'invention is not -to be limitedexcepting by the scope of `the appended claims.

What is `claimed is:

l. -A steam .generator lhaving a setting withav combustion chamber therein, means for producing Aa stream 'of products of combustion for firing the apparatus, the Achamber having a 'gas outlet opening, 'a primary steam generating section comprising fan-upper steam and water drum, down'conrer `tubes in 'communication with said drum 'to lreceive water therefrom, riser tubes in heat exchange relationship with said stream ofpr'oducts of combustion nowing to said outlet opening, lthe riser tubes being in communication with 'fthefdowncom'er `tubes to receive water therefromandwithithe -s'a'id drum fto discharge a mixture :of ysteam and `water thereinto, said 'setting havingfagas outlet, a secondary steam generating section fhaving la circulatory circuit separate from theSci'rculatory circuit lof 'said -primary section, said vsecondary section being disposed in heat exchange yrelationship with gases of combustion 'flowing '-fromfsa'id 'gas -outlet opening toi said gas outlet, yconduit means connecting the WatersDaCe of the-steam and water-drum-of the primary section and ithe Waterspace 'of the upper ydrum 'o'f the secondary section, steam condensingimeans disposedin-sai'd steam and water drum, 'means for conducting the steam generated in the secondary section to said condensing means, means for conducting feedwater'to said steam and 'water drum, 7means for passing y'at least fa portion of 'said v`feed Water -to the condensing fmeans for iusefas 4a *condensing medium, means fior yconducting 'the "condensing medium and the -fcondensate ffrom the ycondenser to saidy downcom'ersiout 'of contact withthe steam generatedin theprimar-y section, a usable steam offtake forreceiving steamgenerated in said steam generator, fthe oitake 'being in communication Withtne 's't'e'amiand water drum of the primary sectionfs'o-as to receive said 'usable steam therefrom, @and blow'downfmea'ns for the steam'generator associated "with said secondary'section.

2.,-'A steam generator having a setting witha combustion fcha'mber '.therein, "means for producing astr'eam .of products of combustion for ringltheappara'tusjthe chamber having a gasoutlet opening, 1a primary steam generating sectionacomprising an upper steam and water drum, downcomer tubes in communicationV with saidf drum tolireceive vwater therefrom, riser tubes'in heatexchange relationship with said stream ofy products :of combustion flowing to said outlet opening, theriser tubes being in communication with the idowncomertubes to receive water therefrom'andwith'the Isaidldrum tcm-discharge a mixture Vof :steam :and :Water thereinto, 4said setting havinga 'gas outlet, a'secondary steam generating sectionlaving ari-upper drum, a lower drum positioned vbeneath rand in spaced relationshipy with.-thesecondary upper drum, downcomer tubes in communication vlwith said secondary lupper drum y and 'with :said lower drum therebeneath, a'

pluralityof riser tubes in communication-'at'the oppositefendsthereofwith said upper and lower drums respectively, said *riser tubes being positioned in the :path fof .gases of combustion "nowing'rfromsaidigas outlet` opening to said gas outlet, fsteam -ircondensing lmeans l'disposedl in 'the steam :and '-Water fdrum "of the primary section, means Ifor conducting the steam generated ,in the secondarysection to -saidcondensing means;

means 'for f conducting "feed water to" said" pri-a mary section steam and water drum, means forpassing at least a portion of said feed Water to the-condensing means for use as a condensing medium, means for conducting the condensing medium and the condensate from the condenser to said downcomers out of contact with the steam generated in theprimary section, conduit means connecting the water space of said steam and water drum of the primary section and the water space of the upper drum of the secondary section, a usable steam offtake for receiving steam generated in said steam generator, the offtake being in communication with the steam and water drum of the primary section so as to receive said usable steam therefrom, and blowdown means for the steam generator associated with the lower drum of the secondary section.

3. The steam generator of claim 2 wherein steam and water treating means is associated with said primary steam generating section, said treating means being constructed and arranged to bring steam and feed water into heat exchange relationship with one another and thereafter separate the steam and water, the treatingl means receiving water and steam from said primary steam generating section, the steam treating means also communicating with the steam offtake so that separated steam passes from the treating means thereto and with said primary section so that separated water passes thereto.

4. A steam generator having a setting with a combustion chamber therein, means for producing a stream of products of combustion for firing the apparatus, the chamber having a gas` outlet-opening, a primary steam generating section comprising an upper steam and water drum, downcomer tubes in communication with said drum to receive water therefrom, riser tubes in heat exchange relationship with said stream of products of combustion flowing to said outlet opening, the riser tubes being in communication with the downcomer tubes to receive water therefrom and with the said drum to discharge a mixture of steam and water thereinto, said setting having a gas outlet, a seconda-ry steam generating section having an upper drum, a lower drum positioned beneath and in spaced relationship with the secondary section upper drum, downcomer tubes in communication with said secondary section upper drum and with said lower drum therebeneath, a plurality of riser tubes in communication at the opposite ends thereof with said upper and lower drums respectively of the secondary section, said riser tubes section to said condensing means, steam and water centrifuging means in the steam and water drum of the primary section, said steam and water centrifuging means being constructed and arranged to separate steam and water from a mixture thereof by centrifugal force, means for conducting feed water to said primary section. steam and water drum, means for passing a por. tion of said feed Awater to said centrifuging:

means prior to passage thereof to the circulatory circuit of said primary section and for passing another Dertien Pf ihefeeawater tothe condensing means for use` as a condensing medium, the centrifuging means being in communication with the circulatory circuit of the primary section so as to receive the mixture of steam and Water generated therein and to return separated water thereto, a usable steam offtake for receiving steam generated in said ,steam generator in communication with the steam and water drum of the primary section and through,

which separated steam from said centrifuging means is withdrawn from the primary circuit, drying means in the path of iiow of the separated steam from the centrifuging means to the lastmentioned means, means for conducting the condensing medium and the condensate from the condenser to said primary section out of contact with the steam generated in the primary section, conduit means connecting the water space of the steam and water drum of the primary section and the water space of the upper drum of the secondary section, and blow-down means for the steam generator associated with the lower drum of the secondary section.

5. Steam generating apparatus comprising a plurality of separate steam generating sections, each section having a complete circulatory circuit, iiring means for producing a stream of products of combustion, said apparatus having a combustion gas outlet, the sections and the gas outlet being so disposed in relationship to one another that the products of combustion fiowing to the gas outlet pass in heat exchange relationship with a lirst of said sections prior to flowing in heat exchange relationship with another section, steam condensing means, means for supplying feed water required for all sections to said first section, means for passing at least a portion of said feed water to the condensing means for use as a condensing medium means for conducting the condensing medium and the condensate from the condenser to said iirst section out of contact with the steam generated in the rst section, means for feeding water from the circulatory circuit of the first steam generating section to said other section, means for conducting the steam generated in the other section to said condensing means, a usable steam offtake for receiving steam generated in said steam generating apparatus, the offtake being in communication with said rst section so as to receive said usable steam therefrom, and blowdown means for the steam generating apparatus associated with said other circuit.

6. Steam generating apparatus comprising a plurality of separate steam generating sections, each section having a complete circulatory circuit, firing means for producing a stream of products of combustion, said apparatus having a combustion gas outlet, the sections and the gas outlet being so disposed in relationship to one'another that the products of combustion owing to the gas outlet pass in heat exchange relationship with a first of said sections prior toowig in heat exchange relationship with another section, steam condensing means so constructed and arranged as to completely condense steam by passage thereof in direct heat exchange relationship with water, means for supplying all feed Water required for al1 sections to said rst section, means for passing at least a portion of said feed water to the condensing means for use as a condensing medium means for conducting the condensing medium and the condensate from the condenser to said rst section out of contact with acca-,eee

for' feeding water fromv the circulatory circuit 0f the rst steam generating section to said otherV section, means for conducting steam generated in the other section to saidy condensing means, a usable steam oiftake for. receiving steam generated in said steam generating apparatus, the oftake being in communication` with saidl first section so as to receive saidl usable'v steam there? from, and blow-down means for the steam generating apparatus associated With sai-dV othersection.

7. Steam generating apparatus comprising aplurality of separate steam generating sections, each section having a complete circulatory circuit, ring means for producing a stream of products of combustion, said apparatus having av combustion gas outlet, the sections and the gas' outlet being so disposed in relationshipto one another that the products of combustion owing to the gas outlet pass in heat exchange relationship with a iirst of said sections prior to flowing in heat exchange relationship with another section, steam condensing means, steam and Water treating means constructed and arranged to bring steam and Water into. heat exchange relationship and thereafter separate said steam and Water, means for supplying feed Water required for al1 sections to said first section, means for passing a portion of said feed water to said steam and Water treating means prior to passage thereof to the circulatory circuit of said rst section and for passing another portion of thefeed Water to the condensing means for use as a `condensing medium,l the steam treating means being in communication with the circulatory circuit of the first section so as to receive the mixture cf steam and Water generated therein and to return separated Water thereto, means for conducting the condensingA medium and the condensate from the condenser to said iirstJ section out of contact with the steam generatedl in the rst section, means for feeding water from the circulatory circuit of the first steam generating section to said other section, means for conducting the steam generated in said other section to said condensing means, a usable steam oitake for receiving steam generated in said steam generating apparatus, the oftake being in communication with said rst section so as to receive the separated steam from said treating means, and blow-down means `for the steam generating apparatus associated with said other section.

8. Steam generating apparatus comprising a plurality of separate steam generating sections, each section having a complete circulatory circuit, firing means for producing a stream I" products of combustion, said apparatus having a combustion gas outlet, the sections and the gas outlet being so disposed in relationship to one another that the products of combustion flowing to the gas outlet pass in heat exchange relationship With a first of said sections prior to owing in heat exchange relationship with another section, steam condensing means, steam and Water centrifuging means constructed and arranged to separate steam and Water from a mixture thereof by centrifugal force, means for supplying all the feed Water required for all sections to said first section, means for passing a portion of said feed Water to said centrifuging means prior to passage thereof to the circulatory circuit of said iirst section and for passing another portion of the feed Water to the condensing means for use as a condensing medium, the cencombustion gas outlet,

trifuging means being in communiotiorr. with' the circulatory circuit of the' first sctiirs its' tov receive' the mixture of steam andwater generated therein and toireturziseparated water' thereto, means for conducting the condensing medium andthe condensateifroii the condenser to. said rstsecti'on out of contact with the stan'i generatedvr in the' iir'stsection, means for feedingY waterv from the circulatory circuit' of the first steam generating section to said other section,v means for conducting the? steam' generated the other sectiony tosaid condensing means,- a` usabie steam oiftake forr receiving steam'generf atedin said steam generating-apparatus, thefofftake being in communicationwitli said first secition so as tol receive the separatedy steamI from said. steam andw'ater centriiging means, and bioW-'down means for then steam generating apr paratus associated with said other section;

9. Steam generating apparatus compris-ing a plurality of separatey steam generating: Sections', each section having a complete circuiaftory'f cire cuit, firing means for producing a stream of products of combustion, said'a'pparatus having a g the sections and the'gas outlet' being so disposed in relationship to one? another that the products-'of combustion iiewing' to the gas outlet pass in heat' exchangereiationr ship with a first of saidsect-ionsp or te"ficvviiig'v in heatexchange relationship wit anotl'ierY sec# tion, steaml condensing mean-ssc constructed `a`iid arranged that steam and Water" iiv'v direct' heat exchange relationship With one another,` steam and Water treating'means'constructed a arranged to bring steamamrwater into neat er; change relationship and thereafter-'separate said steam and Water,` means'jfor suppl'ying`r all the? feed Water required @for allsection's tosaidiigirst" section, means for pass-ingfaportion of saidf Water to' said st'eani and "rater treating prior to passage thereof t6" the" circlatoiylciicit' of said first section and for passing another portion of the feed water to the condensing means for use as a condensing medium, the steam treating means being in communication with the circulatory circuit of the first section so as to receive the mixture of steam and water generated therein and to return separated Water thereto, means for conducting the condensing medium and the condensate from the condenser to said first section out of contact with the steam generated in the rst section, means for feeding Water from the circulatory circuit of the first steam generating section to said other section, means for conducting the steam generated in the other section to said condensing means, a usable steam oitake for receiving steam generated in said steam generating apparatus, the offtake being in communication with said first section so as to receive the separated steam from said treating means, and blow-down means for the steam generating apparatus associated with said other section.

10. The steam generator of claim 8 wherein drying means is arranged in the path of flow of the separated steam from the water and steam centrifuging means to the usable steam oitake to provide the latter With dried steam.

11. A steam generator comprising a setting having a combustion gas outlet, a plurality of steam generating sections in the setting each having a complete circulatory circuit, ring means, the firing means, the steam generating sections and gas outlet being so arranged in relationship to one another that gases of combustion flowing to the outlet pass in heat exchange with one lof said sections prior 'to ilowing inV heat exchange relationship with another section, means for conducting water from said one section to said other section, a steam offtake for said `steam generator in communication with said one section only, blowdown means connected to a concentrated water containing portion of said other section, steam condensing means in said one section, and means for conducting the steam generated in the other section to said condensing means, said condensing means being constructed and arranged to condense all of said steam conducted thereto by said condensing means by passing it in heat exchange relationship with at least part of the feed water for the steam generator and adding the resulting condensate to the Water of said one section byconducting it out of contact with the steam generated therein to a water containing portion thereof.

12. A steam generator comprising a setting having a combustion gas outlet, a primary steam generating section having a complete circulatory circuit comprising an upper steam and water drum with downcomer and riser tubes in communication therewith, the downcomer tubes communicating with the drum to receive water therefrom and the riser tubes communicating with the drum to discharge steam thereinto, a secondary steam generating section having a complete circulatory circuit separate from the primary section, firing means, the firing means, steam generating sections and gas outlet being so arranged in relationship to p one another that gases of combustion flowing to the outletl pass in heat exchange relationship with the primary section prior to owing in a heat exchange relationship with the secondary section, a steam oiitake for said steam generator in communication with said primary section only, means for conducting water from the primary section to said secondary section, blowdown means connected to a concen- 16 trated water containing portion of said secondary section, Vand means comprising a heat exchanger for condensing all of the steam generated in said secondary section by passing it in heat exchange relationship with at least part of the feed Water for the steam generator and adding the resulting condensate to the Water of said primary section by conducting it out of contact with the steam generated therein to a Water containing portion thereof.

13. The steam generator of claim 12 wherein the heat exchanger comprises a condenser disposed in the steam and water drum, said condenser being so constructed and arranged that steamand water ilow in direct heat exchange relationship with one another and the steam is completely condensed.

14. The steam generator of claim 13 wherein the riser tubes are disposed in radiant heat exchange relationship with the gases of combustion and the secondary section comprises an economizer disposed in convection heat exchange relationship with said gases of combustion. l

MARTIN FRISCH.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,904,473 Kerr Apr. 18, 1933 1,940,607 Ryan Dec. 19, 1933 2,067,080 Frankel Jan. 5, 1937 2,191,671 Kuhner Feb. 27, 1940 2,232,265 Place Feb. 18, 1941 2,289,969 Kerr July 14, 1942 2,290,882 Keenan July 28, 1942 2,294,501 Junkins Sept. 1, 1942 2,315,226 Rohlin Mar. 30, 1943 2,384,511 Wagmann Sept. 1l, 1945 2,413,717 Kerr Jan. 7, 1947 2,472,101 Frisch June 7, 1949

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