SE190801C1

SE190801C1 -

Info

Publication number: SE190801C1
Authority: SE
Publication date: 1964-01-01

Description

Uppfinnare: F Fikenscher Prioritet begard !rein den 10 december 1957 (Porbundsrepublikezz Tyskland) FOreliggande uppfinning avser flerstegs regenerativluftforvarmare, som I och for uppnaendet av hoga lufttemperaturer vid samtidig kraftig rokgaskylning genom mellankopplin:g av tvd eller flera extra rokgaskylare aro uppdelade i tvâ eller flera steg. Sadana luftforvarmare ha hitintills utformats sá, att varmevaxlarkropparna rotera runt en horisontell eller vertikal axel, under det att de erforderliga anslutningshuvarna for rOkgasen och luften avensom de extra rokgaskylarna sta stilla. Derma utformning har den avsevarda nackdelen, att den fororsakar svara och kostnadskravande konstruktioner for de tunga, roterande varmevaxlarkropparnas lagring, och dessutom kraves speciella tatningsanordningar mellan de extra rokgaskylarna och de angr5.nsande varmevaxlarkropparna i de framfor- eller efterkopplade lultforvarmarstegen. Inventor: F Fikenscher Priority requested on December 10, 1957 (Porbundsrepublikezz Germany) The present invention relates to multi-stage regenerative air preheaters, which in order to achieve high air temperatures at simultaneous heavy flue gas cooling by interconnecting two or more additional flue gas coolers in several or several parts. step. Such air preheaters have heretofore been designed so that the heat exchanger bodies rotate about a horizontal or vertical axis, while the required connection hoods for the flue gas and the air as well as the extra flue gas coolers stand still. This design has the considerable disadvantage that it causes heavy and costly constructions for the storage of the heavy, rotating heat exchanger bodies, and in addition special sealing devices are required between the extra flue gas coolers and the adjacent heat exchanger bodies in the front or rear coupled luntforvar.

Genom fOreliggande uppfinning undanrojas dessa nackdelar och skapas en vasentligt enklare och tillforlitligare konstruktion, som dessutom tillater ett tillfalligt onskat extra luftuttag eller rokgastillforande Indian luftfOrvarmarens steg, och luftforvarmaren enligt uppfinningen utmarkes i huvudsak darav, att den extra rokgaskylaren Sr anordn:ad ororlig eller ovridbar i forhallande till varmevaxlarkropparna i luftforvarmaren och att genomstrommas av ett extra, foretradesvis flytande kylmedel — lampligen matarvatten — vars ternperatur nara overensstammer med den temperatur, vid vilken den delforvarmda luften genomstrOmmar denna extra rOkgaskylare. The present invention obviates these disadvantages and creates a substantially simpler and more reliable construction, which in addition allows a randomly desired extra air outlet or flue gas supplying step of the Indian air preheater, and the air preheater according to the invention is mainly distinguished by the fact that the extra flue gas cooler Sr. to the heat exchanger bodies in the air preheater and to be permeated by an additional, preferably liquid coolant - suitably feed water - whose temperature closely corresponds to the temperature at which the partially preheated air flows through this extra flue gas cooler.

Uppfinningen kommer att fOrklaras narmare nedan med hEnvisning till fig. 1-6 ph de bifogade ritningarna. Gemensamt for alla de olika nedan beskrivna utforingsformerna Sr Dupl. kl. 13 b: 2/02 att varje inbordes rorelse mellan luftforvarmarstegens varmevaxlarkroppar och de extra rOkgaskylarna undgas och all en icke Onskyard uppvarmning eller avkylning av de dessa rokgaskylare passerande luftmangderna forhindras darigenom, att temperaturen pa det de ifragavarande extra ,rokgaskylarna genomstrommande kylmedlet anpassas efter och narmas till den temperatur, som den fOrbistrOmmande, redan delvis forvarmda luften sjalv uppvisar. The invention will be explained in more detail below with reference to Figs. 1-6 ph the accompanying drawings. Common to all the different embodiments described below Sr Dupl. at 13 b: 2/02 that the movement of each inboard between the heat exchanger bodies of the air preheater stages and the auxiliary flue gas coolers is avoided and that any non-cloudy heating or cooling of the air volumes passing through these flue gas coolers is prevented by adjusting the temperature of the auxiliary radiators. to the temperature which the preheated, already partially preheated air itself exhibits.

Enligt fig. 1-4 sta: luftforvarmarstegens varmevaxlarkroppar 1, 2 och 3 och de extra rokgaskylarna 4 och 5 stilla, sa att deras egenvikt, vilken utgOr den storsta delen av a:n15.ggningens hela massa, tillsammans med de yttre kaporna 6, 7, 8 och anslutningskanalerna 9, 10 for ragasen samt kanalerna 11; 12 och 13 for luften stodjes pa eiikelt, i och fOr sig kant shit pa anlaggningens icke visade fundament. According to Figs. 1-4, the heat exchanger bodies 1, 2 and 3 of the air preheater stages and the additional flue gas coolers 4 and 5 stand still, so that their dead weight, which constitutes the largest part of the whole mass of the air conditioning, together with the outer caps 6 7, 8 and the connection channels 9, 10 for the gas and the channels 11; 12 and 13 for the air stood on eiikelt, in and for themselves edge shit on the plant's not shown foundation.

I forhallande till dessa fast anordnade delar rora sig endast de vid vardera anden belagna luftanslutningshuvarna 14 och 15 respektive den extra luftuttagshuven 16 tillsammans med de tillhorande, pvarmevaxlarkropparnas 1 och 2 resp. 1 och 3 andytor 17 glidande tatningsanordningarna 18. De roterande lufthuvarna 14, 15 resp. 16 aro fastforbundna med varandra medelgt en gemensam axel 19, sit att deras synkrona rotation sakerstalles. De tillhOrande drivanordningarna och delvis Sven de erforderliga lagren for denna axel overensstamma med redan tidigare kanda anordningar och ha darfor utelamnats pa ritningarna. In relation to these fixedly arranged parts, only the air connection hoods 14 and 15 located at each duct move, respectively, the additional air outlet hood 16 together with the associated, heat exchanger bodies 1 and 2 and 2, respectively. 1 and 3 and surfaces 17 sliding sealing devices 18. The rotating air hoods 14, 15 and 15, respectively. 16 are fixedly connected to each other by means of a common shaft 19, so that their synchronous rotation is stopped. The associated drive devices and partly the necessary bearings for this shaft correspond to already known devices and have therefore been omitted from the drawings.

Mellan de roterande luftanslutningshuvarna 14, 15 resp. 16 och de tillhorande, fast anordnade anslutningskanalerna 11, 12 resp. 13 2— — ha naturligtvis i och for sig kända, glidande tatningsmanschetter 23, 24 resp. 25 eller dy- likt anordnats. Pa ritningarna ha anslutnings- huvarna for luften fOr Overskadlighetens skull visats utforda i en del; pa i och fOr sig kant salt kan man emellertid aven anyanda sig av tvillingutforanden, som besta av tva varandra diametralt motstaende och med varandra forbundna delhuvar av en motsvarande mindre storlek. Between the rotating air connection hoods 14, 15 resp. 16 and the associated, fixedly arranged connection channels 11, 12 and 12, respectively. 13 2— - have, of course, per se known, sliding sealing cuffs 23, 24 resp. 25 or similarly arranged. In the drawings, the connecting hoods for the air for the sake of clarity have been shown to be challenging in part; However, in and of itself edge salt, one can also use twin designs, which consist of two diametrically opposed and interconnected sub-hoods of a correspondingly smaller size.

Fig. 1 -visor den enklaste utfOringsformen av uppfinningsforemalet med tva luftforvarmarsteg 1 och 2 och en extra rokgaskylare 4, vars kylmedel — lampligen matarvatten — tillfores genom ledningen 21 och uttages ge- nom ledningen 22. Liksom vid de sedan Hinge kanda regenerativluftforvarmarna av den sa kallade LjungstrOmtypen ãr aven vid upp- finningsforemalet det cylindriska totalrummet och flerstegsluftforvarmarens varmevaxlarkroppar uppdelade medelst ett flertal, exempelvis till 25, radiellt anordnade, cirkeltvarsnittet jamnt uppdelande mellanplatar 28 i ett motsvarande antal sektorrum av narmelsevis triangelformat eller trapetsformat tvarsnitt. Dessa sektorrum maste straeka sig utan avbrott fran den forsta till den sista andytan av hela luftforvarmaren, dvs. utmed dess hela langd, och dela darmed aven den extra rokgaskylaren 4 resp. 5 pa motsvarande satt. Fig. 1 shows the simplest embodiment of the invention with two air preheater stages 1 and 2 and an extra flue gas cooler 4, whose coolant - suitably feed water - is supplied through line 21 and taken out through line 22. As with the regenerative air preheaters then known as Hinge In the form of the invention, the Ljungstrom type is also the cylindrical overall space and the heat exchanger bodies of the multi-stage air preheater are divided by means of a plurality, for example into radially arranged, circular cross-section evenly dividing intermediate plates 28 into a corresponding number of sector-shaped triangular-shaped triangular shapes. These sector spaces must extend without interruption from the first to the last end surface of the entire air preheater, ie. along its entire length, and thereby also divide the extra flue gas cooler 4 resp. 5 pa correspondingly sat.

I och for uppnaendet av en jamn, kontinuerlig kylning av ragasen och till undvikandet av den lake onskvarda varmevaxlingen mellan det extra kylmedlet och den forbistrOmmande luften maste den extra rokgaskylaren 4 varasa utformad, aft for varje tillfalle i vart och ett av de enskilda sektorrummen uppratthalles samma temperaturmedelyarde pa det extra kylmedlet. For det nyssnamnda andamdlet kan man t. ex. anvanda en koncentriskt runt axeln i flera vary framdragen, flat spiralrorsslinga; av vars lindningsvarv varje sektordelrum tilldelas var sitt likadant delstycke, varvid spiralen i och for temperaturutjamningen är sd utford, att dess vary i ett tvarsnittsplan aro framdra.gna i en riktning medan den i ett dammed parallellt plan är utf5rd med lika manga vary, som framdragits i den motsatta riktningen. In order to achieve an even, continuous cooling of the raga gas and to avoid the lake-like heat exchange between the extra coolant and the by-passing air, the extra flue gas cooler 4 must be designed, for each case in each of the individual sector rooms the same temperature medium on the extra coolant. For the newly mentioned item, one can e.g. apply a concentric around the shaft in several vary drawn, flat spiral tube loop; of which winding turns each sector subdivision is assigned its own sub-part, the spiral in and for the temperature equalization being so challenged that its vary in a cross-sectional plane are drawn in one direction while in a dammed parallel plane it is made with as many variables as drawn in the opposite direction.

Under forutsattning av att de appfylla de ovan omtalade betingelserna kan man naturligtvis aven anvanda sig av andra, i och for sig kanda rOrformer och roranordnanden. For alla sektorrummen likadant utformade rorelementldmpligen med var sina tvâ skilda kylmedelsgenomstromningsvagar — kunna Oxen an.vandas, varvid den ena vagen for alla delsektorer aro kopplade i tur och ordning, den ena efter den andra i en riktning runt axeln, medan den andra vagen for alla delsektorer aro kopplade den ena efter den :andra i motsatt riktning runt axeln. Provided that they comply with the conditions mentioned above, it is of course also possible to use other, per se known rorforms and rudder devices. For all sector compartments, rudder elements are similarly designed, each with its own two separate coolant flow paths - Taurus can be used, one path for all sub-sectors being connected in turn, one after the other in a direction around the axis, while the other path for all sub-sectors aro connected one after the other: others in opposite directions around the axis.

Fig. 2 visar en utforingsform fOr speciellt hOga lufttemperaturer, exempelvis en sadan, som erfordras speciellt vid smaltkammarpannor for branslen med mycket hog staggflyt- punkt, ringa innehall av flyktiga bestandsdelar eller aven med stor vatten- och askhalt. Harvid minskas luftforvarmarytan speciellt det hogre temperaturomradet darigenom, att stallet for de hittills omtalade tva luftforvarmarstegen nu anordnas tre sadana steg, namligen ett »hetare» steg 3, ett pmellansteg» 1 och ett »kallarev steg 2, varvid den extra ri3kgaskylaren 5 mellan det hetare steget 3 oak mellansteget 1 kyles medelst hetangan eller medelst pannans ingvattenblandning och darmed tjanar sasom angoverhettare resp. forangningsupphettningsyta. Kylmedlet tillfores genom ledningen 26 och bortfOres genom ledningen 27. Den andra extra rokgaskylaren 4 mellan mellansteget 1 och det kallare luftforvarmarsteget 2 genomstrommas liksom i utf8ringsformen enligt fig. 1 av matarvatten och tjanar alltsa sasom ekonomiser. Anordningen I ovrigt motsvarar anordningen enligt fig. 1. Fig. 2 shows an embodiment for particularly high air temperatures, for example one which is required especially in narrow chamber boilers for the industry with a very high stag pour point, low content of volatile constituents or even with a high water and ash content. In this case, the air preheater surface, in particular the higher temperature range, is reduced in that the stable for the two air preheater stages mentioned so far now arranges three such stages, namely a "hotter" stage 3, an intermediate stage "1" and a "cold reef stage 2", the extra flue gas cooler 5 between the hotter step 3 and intermediate step 1 are cooled by means of the hot water or by means of the boiler's water mixture and thus serve as heaters resp. evaporation heating surface. The coolant is supplied through the line 26 and removed through the line 27. The second extra flue gas cooler 4 between the intermediate stage 1 and the colder air preheater stage 2 is flowed through as in the embodiment according to Fig. 1 by feed water and thus serves as economists. The device I otherwise corresponds to the device according to Fig. 1.

Fig. 3 visar en fig. 1 motsvarande anlaggning, varvid emellertid en del av den i det kallare luftfervarmarsteget redan delf orvarmda luften omedelbart uttages fran luftforvarmaren och med hogre tryck men lagre temperatur an vid huvudutloppet 15-12 tillfores exempelvis branslekrossen i och for torkning, siktning och transport av branslet, som malts eller skall males. Fig. 3 shows a plant corresponding to Fig. 1, however, a part of the air already partially heated in the colder air heater stage is immediately taken out of the air preheater and with higher pressure but lower temperature than at the main outlet 15-12 is fed, for example, the fuel crusher for drying. screening and transport of the industry, which is ground or is to be ground.

Sedan denna luft lamnat luftforvarmarsteget 2, instrommar den i den axeln 19 omslutande luftuttagshuven 16 (istallet for i den extra rokgaskylaren 4 och det foljande luftforvarmarsteget 1), som medelst axeln 19 vrides runt i samma riktning och med samma varytal som lufLinloppshuven 14 och huvudluftutloppshuven 15. Luftutloppshuven 16 fortsatter i rorform uppat, intill dess att den gar igenom huvudluftutloppshuven 15 och medelst den exempelvis manschettforma.de tatningen 25 mynnar i den fast anordnade utloppskanalen 13. De luftfOrvarmarstegets 1 varmevaxlarkropp och rokgaskylaren 4 innehallande rummen aro medelst ett fast anordnat, den rorformade luftutloppshuven 16 omslutande ror tillslutna gentemot denna liksom luftf8rvarmarstegets 2 varmevaxlarkropp aro tillsluten. gentemot den genomgaende axeln 19. After this air has left the air preheater stage 2, the air outlet hood 16 enclosing in the shaft 19 flows in (instead of the extra flue gas cooler 4 and the following air preheater stage 1), which by means of the shaft 19 is rotated in the same direction and with the same speed as the air outlet hood 14 and the main air outlet 15. The air outlet hood 16 continues in a rudder shape upwards, until it passes through the main air outlet hood 15 and by means of, for example, the cuff-shaped socket 25 opens into the fixedly arranged outlet duct 13. The heat exchanger stage 1 of the air heater stage 1 and the flue gas cooler 4 containing the space the air outlet hood 16 enclosing tubes are closed opposite it as well as the heat exchanger body of the air heater stage 2 are closed. opposite the through shaft 19.

Istallet for att uttaga en. annu icke till hogsta temperatur uppvarmd delluftmangd genom den rorformiga kapan 16 omedelbart after det kallare luftforvarmarsteget 2 enligt fig. 3 oak 4 foreligger enligt uppfinningen aven mojligheten att enligt fig. 3. och 4a genom en liknande men dock nagot andrad kapa 16' infora en del av den heta rokgasen, som pa i och for sig kant satt dessfOrinnan avgrenats fran den gasmangd, vilken skall tillfOras genom huvudinloppsstutsen och exempelvis kylts pa annat satt, direkt i luftforvarmarsteget 2. Darigenom kan man vid en lamp-hg dimensionering likaledes undvika en otill.. — —3 laten minskning air det for varmeoverforingen mellan rokgaserna och luften i luftforvdrmaren i sin helhet erforderliga temperaturfallet mellan dessa hada medier. Instead of taking one. If the partial air volume not heated to the highest temperature through the tubular hood 16 immediately after the colder air preheater stage 2 according to Fig. 3 is also 4, according to the invention it is also possible to insert a part according to Figs. 3 and 4a through a similar but somewhat different hood 16 '. of the hot flue gas, which on its own edge sat before it was branched off from the amount of gas which is to be supplied through the main inlet nozzle and, for example, cooled in another way, directly in the air preheater stage 2. In this way, a lamp-high dimensioning can also be avoided. The temperature drop required for the heat transfer between the flue gases and the air in the air heater as a whole requires the temperature drop between these hot media.

Sasom framgar air fig. 3a och 4a maste den inre genomloppsoppningen for den nagot forandrade kapan 16' naturligtvis mynna i den for varje tillfalle av rokgaserna genomstrommade sektorn av den stillastaende matarkroppen 1, 4, 2, dvs. vara c:a 1800 forskjuten i forhallande till oppningarna 14 och 15. Darvid är aven den roterande kapan 16' forbunden med ett stillastaende air 13', som framleder den ovan namnda, aygrenade och mellankylda delen av rokgasen till genomstromningsoppningen 51. As can be seen in Figures 3a and 4a, the inner passage opening for the slightly altered hood 16 'must of course open into the sector of the stationary feed body 1, 4, 2, which has flowed through for each case of the flue gases, i.e. be approximately 1800 offset in relation to the openings 14 and 15. In this case, the rotating hood 16 'is also connected to a stationary air 13', which conducts the above-mentioned, branched and intercooled part of the flue gas to the flow-through opening 51.

Fig. 4 är en forenklad, fig. 3 motsvarande planvy, som visar anordnandet av den roterande huvudluftutloppshuven 15 och den kencentriskt med denna respektive inuti densamma anbragta luftuttagshuven 16. Bada huvarna aro utformade med luftgenomstromningsoppningar 30 och 31, som bada omslutas av pa de tillhorande, stillastaende andytorna 17 glidande eller slapande tatningsramar 18. I fig. 4 visas Oxen anordnandet air de ovan omtalade radiella mellanplatarna 28, som stracka sig genom hela rummet for luftforvarmaren inklusive varmevaxlarkropparna och de extra rokgaskylarna 4 resp. 5. Fig. 4 is a simplified plan view corresponding to Fig. 3, showing the arrangement of the rotating main air outlet hood 15 and the air outlet hood 16 arranged centrally therewith, respectively. Both hoods are formed with air flow openings 30 and 31, which are both enclosed by the associated , the stationary face surfaces 17 are sliding or sliding sealing frames 18. Fig. 4 shows the ox arranging the radial intermediate plates 28 mentioned above, which extend through the entire space of the air preheater, including the heat exchanger bodies and the extra flue gas coolers 4 and 6, respectively. 5.

Fig. 5 visar en utforingsform av luftforvarmaren, varvid varmevaxlarkropparna 101 och 102 tillsammans med den extra roligask3r1aren 104 Oro roterbart anordnade medan dare-mot luftinloppshuven 114, luftutloppshuven 115 avensom rokgasinloppshuven 109 och -utloppshuven 110 aro fast anordnade. Lager och drivanordningar for de tyngre, roterande massorna ha icke visats enar de aro av i och for sig kant slag. Aven i detta fall stracka sig de radiellt anordnade mellanplatarna 128 igenom hela del roterande luftfarvarmaraggregatet. Fig. 5 shows an embodiment of the air preheater, in which the heat exchanger bodies 101 and 102 together with the auxiliary screwdriver 104 are rotatably arranged while the air inlet hood 114, the air outlet hood 115 and the flue gas inlet hood 109 and the outlet hood 110 are fixedly arranged. Bearings and drive devices for the heavier, rotating masses have not been shown to be of the per se edge type. Also in this case, the radially arranged intermediate plates 128 extend through the entire part of the rotating air dye assembly.

Sfirskilt skall framhallas den kraftiga axeln 119 med invandiga kanalerna, som Over de schematiskt visade packboxarna 141 och 142 forbinda den extra r5kgaskylaren 104 med inloppsledningen 121 och utloppsledningen 122 for kylmedlet. The strong shaft 119 with the internal channels must be emphasized separately, which via the schematically shown stuffing boxes 141 and 142 connect the additional flue gas cooler 104 to the inlet line 121 and the outlet line 122 for the coolant.

I fig. 6 visas en kombinerad packbox med anslutningar 121 och 122 for kylmedlets tillforsel och bortforsel. Denna erfordrar endast en hogtryckstatning 150. Anslutningen till axeln är utford medelst tva tillsammans med axeln roterande, koncentriskt hopskjutna och med varandra fast forbundna ror 151 och 152, varvid kylmedlet strommar till kylaren genom ringrummet mellan roren och lamnar kylaren genom .det inre roret 151. Mellon samlingshuvarna 153 och 154 for tillforseln och bortforseln erfordras endast en lagtryckspackbox 155. Fig. 6 shows a combined stuffing box with connections 121 and 122 for the supply and removal of the coolant. This requires only a high pressure feed 150. The connection to the shaft is challenged by means of two rotor 151 and 152 rotating, concentrically pushed and interconnected together with the shaft, the coolant flowing to the cooler through the annulus between the tubes and leaving the radiator through the inner tube 151. Between the collection hoods 153 and 154 for the supply and removal, only a low-pressure packing box 155 is required.

Vid praktisk panndrift, speciellt vid anlaggningar med smaltkammareldstader, foreligger ofta kravet att varmlufttemperaturen skall hallas pa det for normal- resp. gransbelastning bestamda vardet eller hojas Over delta varde da den vertikala belastningen endast uppgar till en brakdel av normalhelastningen. I delta fall minskar varmlufttemperaturen redan i och for sig normalt och a den andra sidan rusar tandningen lattare nedat vid lag belastning och sanker brannkammartemperaturen, varigenom vid smaltkammareldstader uppkommer en Rad risk for »infrysning» av smaltkammaren och slaggutloppsoppningen. Med hjalp av luftforvarmaren enligt uppfinningen kan man minska den extra rokgaskylningen och darigenom Oka luftuppvarmningen i det kallare luftforvarmarsteget pa foljande salt: F5r det forsta kan man minska kylmedelsmangden i den extra rokgaskylaren, dvs. minska den denna rokgaskylare genomstrommande mangden matarvatten, exempelvis genom en tillfallig minskning air vattenmatningen till pannan, t. ex. medelst en drosselventil eller den i varje handelse forekommande matarvattensventilen eller under formedling av en. reglerbar forbiledning (med en forbiledningsventil), vilken ledning leder en del av den tillforda matarvattenmangden forbi den extra roligaskylaren. In practical boiler operation, especially in systems with smelting chamber fireplaces, there is often a requirement that the hot air temperature must be kept at that for normal resp. boundary load determined value or hojas Over delta value as the vertical load only amounts to a fraction of the normal load. In some cases, the hot air temperature already decreases normally and on the other hand the ignition slows down more slowly at low load and lowers the fire chamber temperature, whereby in narrow chamber fireplaces there is a number of risks of "freezing" of the narrow chamber and slag outlet opening. With the help of the air preheater according to the invention, the extra flue gas cooling can be reduced and thereby increase the air heating in the colder air preheater stage on the following salt: First, the amount of coolant in the extra flue gas cooler can be reduced, ie. reduce the amount of feed water flowing through this flue gas cooler, for example by a temporary reduction in the air supply to the boiler, e.g. by means of a choke valve or the feed water valve present in each transaction or during the mediation of a. adjustable bypass (with a bypass valve), which line directs part of the supplied feed water past the extra noise cooler.

Man kan amen Oka kylmedelstemperaturen. Vid lagre matarvattentemperatur kan man f8r delta andam51 tanka sig en matarvattenforvarmning, exempelvis medelst turhinutloppsanga, farskanga fran pannan eller andra eventuellt tillgangliga, yttre varmekallor. You can amen Increase the coolant temperature. At lower feed water temperature, it is possible to preheat a feed water preheater, for example by means of a turbine outlet steam, farce steam from the boiler or other possibly available, external heating sources.

Claims

Patent claim:

Multi-stage, cylindrical, flue gas cooling and air heating heat exchanger bodies (1, 2, 3) and in relation to these rotating air connection hoods (14, 15, 16) existing regenerative air preheaters of the Ljungstrona type, wherein between each pair (12, 3L-1) arranged by an extra flue gas cooler (4, 5), characterized in that the extra flue gas cooler (4, 5) is arranged immovable or non-rotatable in relation to the heat exchanger bodies (1, 2, 3) in the air preheater and to be passed through by an extra, preferably liquid refrigerant - suitably feed water - whose temperature closely corresponds to the temperature at which the partially preheated air flows through this extra flue gas cooler.

2. A multi-stage air preheater according to claim 1, characterized in that the heat exchanger bodies (1, 2, 3) through, radially directed sector separators (28) also extend through the additional flue gas coolers (4, 5), so that they axially along the several steps extensive air preheater throughout the sector rooms limo gasatt separated & dm each other.

Multi-stage air preheater according to patent claim 1 or 2, characterized in that the additional flue gas coolers (4, 5) are located inside the cylinder shell surface (7) of the air heater, fill the circular cross-section enclosed by it uniformly and by means of suitable rudder control as well as coolant control in the usual sector, achieve approximately the same average temperature for the additional coolant.

4. A multi-stage air preheater according to any one of claims 1-3, characterized in that an additional air outlet hood (16) is fixedly connected to the rotating air outlet hood (15) from the hottest air preheater stage (1), so as to bypass the hottest stage ( 1) divert part of the air not yet heated to the highest temperature, for example to a coal drying or coal crushing plant.

5. A multi-stage air preheater according to claim 4, characterized in that concentrically inside the rotating air outlet hood. (15) Arrange one with the same rotating and Over the same in the entire air preheater up to the desired extra air outlet stall required and with the same fixedly connected pipe (16), which on the other Sr provided with a required, tapping air outlet hood (18).

Multi-stage air preheater according to claim 8 or 4, for particularly high air temperatures, characterized in that it consists of a hotter stage (3), an intermediate stage (1) and a colder stage (2), wherein it is to the hotter stage (3). adjoining extra raga gas cooler (5) is arranged to be cooled in hot or steam-water mixture, while the adjoining additional flue gas cooler (4), as hitherto, is arranged to be cooled by means of feed water (Fig. 2).

7. A multi-stage air preheater according to claim 4 or 5, cited & Tay, that the additional rotating hood (16) originally intended for the extraction of air is used for supplying additional suitably tempered flue gases from outside and that its flow opening (31 and 51, respectively) corresponding thereto Sr connected to the air preheater of ragas through-flowed partial cross-section and adapted accordingly, while the air cross-section corresponding thereto is closed (fig. 4, 4a).

8. A multi-stage air preheater according to claim 3, characterized in that the heat exchanger bodies (101, 102) of the air preheater are rotatably arranged like the auxiliary raga cooler (104), while the air and raga gas connection hoods (114-115, 109-110) are fixed and the additional coolant is supplied and removed through the geno-drilled air preheater shaft (119), which is equipped with suitable, pressure- and temperature-resistant stuffing boxes (141-142; 150155). Request publications: U.S. Patent Nos. 2,803 43

9.