HUE029835T2 - Forced-flow steam generator for burning dry brown coal - Google Patents

Description

i'GECEÎEFL«»m STEAM GENERATOR for burning dry brown GOAL·

The invention relates to a once-through steam generátor fer htittiing dry brown eö# Witimöfíhé alti of recycled flue gas in its combustion chamber, the ottee-ahrongh steam generator having a combustion chamber, a flue gas pass which adjoins ihe upper end of said combustion chamber, and enclosure walls which etiefoss Οκοη, the enclosure waits being formed from tube walls, the tubes of which conduct the working «ledmm water/steam, the combustion chamber having at least one humer, and heating surfaces being arranged in the flue gas pass.

Once-ihrough steam generators are known from the publication ‘Äftwerksteehnih*4 power plant feöbnpioggl, Springer-Verlag, 2nd edition ÎM^ ehiapter 4.4.2.4 Forced flow (pages 171 to 174 ), Prof. Dr.-lag, IC&ä Strauß, ami are used in: power plauts io generate electric by bunting, for exmnphvfowil fools. In a oneë-thïôngh steam waits or enotosnre walls which form the soufonstion

Chamber or the gas flue leads, in confmst m a natural «foam generatet with only partial evaporation of the water/steam mixture conducted in the circulation, to an evaporation of the ilow os-working medium in the lubes of tbe mb©wafis or enclosum walls in a single ibrougbllow. A once·· through steam generator which is fired With dry brown coal (DBC) or a power plant winch, is configured with said steam potential to increaseThe degree of efficiency over a once- tough steam generator which is fired conventionally with raw brown coal (RBC) or a power plant which is configurai! with said steam genetatof^ fiefo, fee BBC is produced in an enetpetieahv favorable manner írom MIC in a process which takes place before the combustion,; As a result of the reduced water content oft>BC compared Λ RBC, the calorific vaine and -the heat guantily fo be transferred thereby in the eoinbustion Cliathber of the steam generator rise considerably. In accordance wi|b theasb properties of the MC or the DBC, the combustion chamber has te fee designed itt such a way that a ilpal combustion chamber femperatuto in the range ton 95Ö to '1150*0 is set by the heat absorption of the eiKîi^ôie''Walla'''of'^riE^lmstioa:'éhaÂer,.ïie· mediunnside steam temperature which results on account of the hegi^^iptidft.of'teimdfeaurawa&ds pivotal tor the material selection df ifeeduhe walls which arc used as enclosure walls rube connection. In oneetihtmtgb sieata generators with high, supercritical steam parameters, a defmed part of flue gases has to be recycled into the combustion diamber (Hue gas recirculation) when firing :DB£ in ordar to reduce the heat afcsorpifon of the enclosure walls m the combustion chamber, in order titatftiteiiigMy loaded parts (obtirpte winding anti perpendicular bote) of the enclosure walls which are configured as tube walls can he formed tom ihe special materials T23 (a material which is approved by the ASME (American Society of Mechanical Engineers}}, 124{?Gt-MoVTiBiO-iO) or oilier materials wife a sifelfer «hemieÖieopijx^tiotFÄsIt all: belong to tlm category of mtidlfled, heat-resistant 2.2S-2Â% clwominm steels. ffisse materials have: the advantage that they am especially suitable lor high steam parameters and that they can he welded; wifomn thermal post-treatment, and therefore the production of the enclosure walls or tube walls and their assembly on the construction site can he carried out «.imply. The material T23 is listed, for example, in the YdTÖV material sheet 511/2, edition 06.2001 and the material T24 is listed, for example, in the standard specification sheef DIN EN 10216-2, edition October 2007. Iß the ease of the use of floe gas recirculation.. a Hue gas rceircniation system with a flue gas recirculation faß is necessary. The cc-nvcctam heating surfaces which are used are in some esrcam stancea larger than if no ihre gas rceircuiatioa is used, The flue gas recirculation system and the additional heating surfaces represent high investment costs, in a futth« disadVMiSipoits way, the ilye |;#ir^ircyta^k§ystetn increases the internal elec irk consurnpfion of ihc porter plant and increases the limning operating . etas.

As has already beet? meet toned aboie, natural circulation and forced circulation steam generators are also known m addition to the once-rhrough steam generators, in these known recirculation or circuíátíon steam generators with snhcriiical aieant ptuameiers, only a defined quantity ofibesfcan be: absofoedfey site evaporator of the steam generatoiy Said quantity of heat is defined by the operatiitg pressuiw of the plant . As a result o f the properties of thé fuel (ash composition, fusion properties of the ash), the quantity of heat to he transferred from the combustion in the firing chamber or in the Combustion Chaniher cart be higher titan that winch can be absorbed by the evaporator. Plafeo heating surfaces have then been used in circulation steam generators, in order to litnit the quantity of heat to he iransfcmxi to the evaporator and'ox to etnit tlte excess quantity of heat to the platen heating surface, la. contrast to the ostorai circulation and forced the heat absorption is not limited in a ottee-tinongh Steam generator in its evaporator, situ» ihe hiedimh temperature at the evaporator rattler is already superheated during once-through operation and (fee level ofÉe Shpetfeeatittg can bo fixed variably, f ite associated temperature level of the »team or the correspondhtg design temperature in the enelösuré wáiia is controlled by a sniiafeie material selection and, if £>BC is burnt, by suitable Ihre gas reeiretthttibh ihtö the combustion chamber, f)bi?timent liS 5l4fe$?8 .áiscloses'4'-4f^Öb.geoe^r:h9bd!^ÍWÉé;iprfbr art, ft is then an ...object of tire invention to provide a once-through steam generator for burning dry brow·', coal in which oueerfhrdugh steam generator thé Ste^datidÖÉii :di<%d*mstaps-dfb «VoMdé of in which ohee-through steam gsaeratbts if dry hrawivoeal is feiirfrafe, the use of flue gas recirculation is avoided and the medium temperature in the enclosure walls or the tube walls Is nőt itxéréased in comparison wish tho once-Shrough steam generator lired by raw brOwu coal

The abovernentioned object is adué ved by ihc entirety of the features of Paient Claim 1.

Advantageous hé gathered Írom the suix;Mms>

The solution according to the invention provides a once-through steam generator for bunting thy brown coali. which ones-through steam generator has the following advantages; avoidance of Hue gas recirculation atxh associated with this, an itnprovemeni in the steam generator depBébf éffîciéftôÿ thd Iggf Ü&amp; fluegas air preheater;: redneiion of investment costs and operating costs: for the reduction of the eonyeCtiott heating surfhce sjge in comparison with an embodiiaertt with Hue gas recirculation.

One advantageous embodiutextf provides tfiat she platen heating surface which epvera part of the bpclciit^wv'alls.|ö.:i^:#|^<öf the combustion: cbajnber is arfsmgéd betweetr thé upper edge of the upperrsmsf burner bibi foe lower edge: of the lowermost hetifing surface, M-. èifesult of this measure, a defined region of the combustion charabor is covered by way of a plafon heating suriacOv at which regien a latf é part of the fes&amp;t weald otherwise pass out of the oOmbustion clraidber medium tetppcrature in ihe enclosure wall ataá fete witil tempétaturé tfeereof in such: à way ihat a flue gas recirculation system would haver© be used in order to«duce the wall temperature.

In one advantageous reftneatent of the invention, at least pan of the exiclosure walls is formed fem one of the materials T.23, T24 or another material witha similar chexmeaf eotaposititm, Hexe, aiieasr ihatpaft oi the enclpspre walls is configured with. thmtwUy loaded hifi# or mote highly than the remixing part of the 6gÄüp^Ä.^^ten8b''r2|y.^4i^8t^#et: materiai wiidt a similar ehemicai coinposition are high-quality materials which are commercially available ami satisfy the desired reqttirements or on which no thermal pspheahrtexh lias to be carried out after they have beers welded;

One advantageous embodiment of the ixsygMinn provides for the platen heating sorlap 10 he lorated or produced horn martensitic materials wddx a 5-1234 chromium proportion, austpitie xnaterials Ψ aiekehhased alloys. This ensures that, with regard to tlte temperatures, the requitements made of the platen heairng surface which lies exposedin the combustion chamber are satisfied, lx is advantageous that, the platen heatitrg snrfoce is eondgared m a superheater tettiftgxsätfätte' 'öt<&amp; reheater hetiting surface, the platen hpting; sarfap is ^dt®fag.'m't»poxat«d' pfSeíptíly into the watetesteam circuit of the onee-ihrough steam geíintaior or into the watexfsteam cirexht of a power plant which comprises a once-through stemh generator of dûs type.

One advantageous embodiment provides that the platen heating; surface is setmiged parallel to the enclosure wall Tl# achieves a stteation where the platen heating awfte«· Í8* the enclosure wall and affords as small as possible an action surface for ash or cinder from the combustion chamber.

One expedient embodiment provides that the platen: heating sitrfaee is arranged such that ft hears agaiîiSi the enolosxire wall, dhis Psures {flat the enclosure wall Is covered as satisfactorily as possible by (he platen heating surface and the to thé eplosure wall:

Exemplary embodiments of the invention are described in greater detail below using the description and the drawing, in winch: :1%. 1 diagrammatically shows a lo.ug}^38iÄ,socti.©äi.fl*ß»Ä;'Ä^«*Ötrö*®fe'i^Wf«S8«rator accord mg to the invention. and tig. 2 shows the same as figure !, hat in an a he mauve embodiment.

Ftgure [ diagranunaucaliy shows a onee*ihxough stsitm generator 1 (the designation means the generation of the steam within the steam generator in one pass) of tower design, that is fe s^ the tube walls 5 (as enclosure walls 41 and all the heating surlaces 7 are accommodated on or in a single vertical ps flue. The vertical gas Hue which ín főnixed or delimited by gastiglxt enclosure wails 4 contains, in its lower region, the combustion chamber 2 and the flue gas pass 3 which adjoins above said combiamon chamber 2. The combustion chamber 2 terminates to the bottom as a rule with a combustion chamber hopper and reaches upward as far as the lowexrnost beating surface 7. One or mote huraers 6 for hdfitíhg dty arranged in the lower region of Site combustion chamber 2. The burners 6 can be arranged cither it! the corners (coniex burners) or in the'Walls (wall burners) of the combustion chamber 2, The various heating siblhees 7 are arranged as convection heaong surfaces in the fine gas pass 3. Said heating surfaces 7 are as a ruleeconomizer heatixtg smdaces, superheater heating surfaces and reheater heating surfaces. The flue gas pass 3 tet^dihaies -»1 .tfer fop: with a ceiliîîg and has a Hue gas outlet jl laterally at its upper end.

According to the invention^ the once-through .steam generator Thati at least one platenheahng surfaces which covet« part ot the enclosure walls 4 in the region of the combustion.Phaiöfeer 2 and the suxfaeecside: SiXe

Of whlPh iS: defined SUbh that die:feat ahsofeion of the enclosure wafts 4 and, η* a consequence,:their tmperature are reduced to a value Â?h pçrwifeik« :soa%«f»îioa of the enclosure .wÉh4?.fe«|t •rssdstarít 2.23-2.5%: efeoimunt steels 'Which de not require say tfer.mal : p^t-treataerli «fer they have been pmeessed Using welding technology, In other words, the platen heating surface R. which cuvera the endos»«; wall 4 in ehambërd with a predefined surface· safe size, absorbs so much heat from the camfestion efember 2' that Öle ;heai absorption of the enclosure waif 4 is reduced as a consequence of the opyerhtgplii gucitf a way that the maximum medium temperature at the enclosure wall 4 remains:heiew a value which allows the use of modified, keabigsistabt 2.25-2.5% diromintn steels which dovfedTeqhfe.sajy· thermal post-treatment after they have beer: processed using weldsng technology. They Can be, farsample, the : materials 123 (a material which is approved by the ASMi·. (American' Society of Mechanical Itsgineers}). 124 • 17C'rMoVTiB10-10} or another material with a. .similar chemical composition which can cover steam lemjiasrattifes vi|)-fd:'^ppró3dmafely 3Ö0*§1Ö°C and which are listed, for example, in tfe brochure 'The T2.VT34 Book,: Hew Grades lor WaterwalSs and Superfiesters: from Vallourec <&amp; Mannesmana Tubes” (brochure· about modified, feat-resistani 2.25-2.5'"» chromium steelshJis a result of the reduction in the: medium temperature in the enclosure wall 4 by means of theplatsn heating surface 8 which, is arranged according to the invention, the use of flue gas recirculation systems: esn be dispensed with, which systems otherwise conduct cooler flue gu» into the combustion chamber 2 and therefore reduce the temperatures whin« the eotnbustion chamber 2 and, as a consequence, also the medium temperám ie in the enclosure wall 4.

These abovenrerttioned hip-guaiuy materials which do not require any tferoral post-treatment after they lave been processed using welding technology eatt either be used everywhere osr the enclosure waft 4 or, aeeordtng to one enmrnereiaily rtidre advatiisgeOes variant, at least at those parts of the enclosure walls 4 where the high thermal leading: makes it necessary, ifey are, for example, the regions at tire burners (> and directly above the homers 6 within the combustion chamber 2. In order to reduce the investment eösts In ctnnparison with thc^afev&amp;m^fion^'b^ript^ft^maf^ridMe^r^uli.tyrmaten'als« smhas i6Mo3 or }3CrMo45. are nsM at those parts of the enelosurewalls 4 where tfe ftretrbal loading is lower, such its in the lower part of the combustion chamber 2 (below the burners 6 inolufetfg eombnëtion chamfer hopper) with medium temperatures of approximately < 400-46()°C in the tube wafts. Said materials likewise. dr> not require any thermal post-is-eaü»eutÄer they fevefeeupmeessed using weiding&amp;chudlogy.

The enelosure walls 4 whioh arc configured as tube wafts 5 are produced äs a rule from a welded walla # oendncfial; the working medium watefetearn, afe ft being possible for tfem::fe-fe.;toÉBài^i5ÂatsÉæ enclosure walls 4 enfer helically or vertically or trom a combination of helically and vertically. The tubes which are arranged in the enclosure walls 4 are used in the lower and middle part of tfe' as evaporator tubes, that is to say tfe water which Is fed in and pre heated is evaporated in said evaporator tubes. Its the upper part of the combustion chamber 2 which has perpendicular in tfe enedosnts waft 4 can already be connected as a superfeater heating sufifee,

Tfe platen heating sariace 8 itself! which ifeh absorbs part of (he heat fent tfe eprnhusdert chamfer 2, is fortned using suitable materials according to the temperature requirements. Since very high temperatures have to be handled, martensitic 9-12% efepmitm|*ednfehtng steels, austemlie steels or nickel-based alloys have proven to be suitable for tins purpose. They can be, for example, ife mäftefehic materials T9] (XIüCrMoÄb9H). T92 (XI0CiWM<5¥Xb9*2J: or ¥M1|-SHC, the austenitic steels SHEER 304M, H.R3G, $MV204MGut DMV31Ö1K or niekel-based alloys such as Alley 64? (HsCr23Coi2Mo) er Alloy «tárná ÍNiCí23£oF2Mo: mod); The pisién heating surface 3 can consist off individual tubes,, which are arranged clore to. one another and hi parai Id, or of a tube-web-iube construction. The tubes of the platen heating surface 8 run as: a nslú hodMiitálly widnn the heating surface, hut can also run vertically :Ä..p^h:^at^g.:'ts»ffaiS&amp;J is preferably ammgpdphdlel to the enclosure wait 4 and móré preferably so as to hear agahist the latter, This arrangement ensures that the enciosme wall 4 is covered very elfidendy try the ôta» heathrg surhtee S5 and the transmission of heat to the éifeíosttre wail 4 is therefore suppressed as taras possible,: Iig.gre 2 shows one adiraoiagepus: variant of the platen treating suriace: 8 according te life invsmion. Hőre, the enclosure wall 4 and ötbe wall 5. wßieh as ä rule eohislö the hont axsd rear wails and two side Waits of the oncedluough steam generator, are covered partially hy one or more platen heat ing surfaces 8 in the region of the combustion chamber 2, to be precise between the upper edge of the uppemtost bœwtt;S:.*»âÉ»"h>w?gr«%o·' of the lowermost heating surface 7 (the region is markod or denoted by “S" tu ftgute 2), onejiteten heating surfaecX being arranged on each individual tube walk that is to say a total of four, according: .to figure 2, As g result of the: targeted arrangement of the platen heating surface H specifically 1» this ':re|ídö-4if:4g..«.ööíbi*sÖiöh chamhef 2. that region of the enclosure wall 4 or tube wall 5 within the oôtrÉustfeh .chnretb^r.S-'^ifeh-if'boiest as a rule can he covered in a very targeted manner. The platen heating surface 8 can advantageously he used as a snpetheater beating mtr&amp;ce within tfe steam generator 1. However, the use as a reheater heating surfoee is also possible.

Lib I OF DESIGNATIONS: 1 Dnenobreugh steam generator 2 Combustion chamber 3 Flue gas pass 4 Enclosure wall 5 Tube wall 6 Burner 7 Heating surface 8 Fiatén heating surfose 9 Flue gas outlet

Claims (8)

QÙmMiÆMiîê DRIVE BARRIER Ei; 1; the iulary plates (4) are made of tubular walls (5, i are formed by tubes of water / steam nhink; conducting, the burner of the burner P) {collapses and the end-of-line (?) in the gas passage (3) are recessed, (4) a portion of mc egsskamra (2) is covered with at least one compartment (8), with yuan. tegntnM Básantá «item igässyeisek« tô? 2. The steam generator according to claim 1, wherein the funnel (2) is a heating element of the compartment (4} of which comprises four parts of the boundary band (4)). ) is located at the bottom edge ^ 3 *. Claim: A steam generator according to the invention, at least a portion of the fins (4), is formed from one of the 1¾ T24 materials, or a chemical composition of a bicker is formed by another anysgboi. 4 »That his compartments; 9% to 42% irity steels are made of austenitic steels or nickel-based alloys. A steam generator according to at least one of the preceding claims, characterized in that its compartment * has a top surface (B) of a type of a fleece, which is formed by: f. Thrust actuator according to at least one of the claims is formed by an intermediate overheating fleece blade v1. A vapor deposition according to at least one of the preceding claims, characterized in that the heaters of the compartment (8) are dispensed with a parallele (4j). 8 «At least one of the foregoing claims is a jet head blade, the diaphragm blade (8) being a blade gate (4) for a blade.