EP1393001A2

EP1393001A2 - Steam generator

Info

Publication number: EP1393001A2
Application number: EP02729915A
Authority: EP
Inventors: Joachim Franke; Rudolf Kral
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2001-06-08
Filing date: 2002-05-27
Publication date: 2004-03-03
Also published as: SK287649B6; JP4443216B2; PL199124B1; RU2004100240A; CA2449652A1; US6868807B2; CN1526059A; CN1289853C; WO2002101292A2; WO2002101292A3; SK16062003A3; CA2449652C; KR100718357B1; PL367197A1; CZ20033530A3; JP2004529310A; DE10127830A1; DE10127830B4; US20040149239A1; KR20040011530A

Abstract

The invention relates to a steam generator (1, 1', 1"), in which a continuous heating surface (8, 10, 12) is located in a fuel gas channel (6) that can be traversed in an approximately horizontal fuel gas direction (x). Said continuous heating surface comprises a number of steam generator pipes (22, 50, 60) that are connected in parallel (W) for the passage of a flow medium and is designed in such a way that a steam generator pipe (22, 50, 60), which is heated to a greater extent than another steam generator pipe (22, 50, 60) of the same continuous heating surface (8, 10, 12), has a higher throughput of the flow medium (W) than the other steam generator pipe (22, 50, 60). The aim of the invention is to produce a low-cost steam generator with a particularly high level of mechanical stability, even when subjected to different thermal stresses. To achieve this, the or each steam generator pipe (22, 50, 60) has a respective downpipe section (34, 52, 62, 64), which is approximately vertical and through which the flow medium (W) can flow downwards and a respective riser pipe section (36, 54, 66, 68) connected downstream of the downpipe on the flow medium side, which is approximately vertical and through which the flow medium (W) can flow upwards.

Description

description

steam generator

The invention relates to a steam generator, in which a continuous heating surface is arranged in a heating gas duct through which the heating gas can flow in an approximately horizontal direction and which comprises a number of steam generator tubes connected in parallel to the flow through a flow medium, and which is designed in such a way that one in comparison to another Steam generator tube of the same once-through heating surface of a multi-heated steam generator tube has a higher throughput of the flow medium than the other steam generator tube.

In a gas and steam turbine system, the heat contained in the relaxed working fluid or heating gas from the gas turbine is used to generate steam for the steam turbine. The heat transfer takes place in a waste heat steam generator connected downstream of the gas turbine, in which a number of heating surfaces for water preheating, steam generation and steam superheating are usually arranged. The heating surfaces are connected to the water-steam cycle of the steam turbine. The water-steam cycle usually comprises several, e.g. three, pressure levels, each pressure level having an evaporator heating surface.

For the steam generator downstream of the gas turbine as the heat recovery steam generator, several alternative design concepts come into consideration, namely the design as a continuous steam generator or the design as a circulation steam generator. In a once-through steam generator, the heating of steam generator pipes provided as evaporator pipes leads to an evaporation of the flow medium in the steam generator pipes in a single pass. In contrast, in a natural or forced circulation steam generator, the water circulated is only partially evaporated when it is passed through the evaporator tubes. The water that has not evaporated after the steam generated has been separated off, it is fed back to the same evaporator tubes for further evaporation.

In contrast to a natural or forced circulation steam _{generator, a continuous steam generator is} not subject to any pressure limitation, so that live steam pressures well above the critical pressure of water (P _Krι »221 bar) - where there are only slight differences in density between liquid-like and steam-like medium - are possible are. A high live steam pressure favors a high thermal efficiency and thus low CO ₂ emissions from a fossil-fired power plant. In addition, a continuous steam generator has a simple construction in comparison to a circulation steam generator and can therefore be produced with particularly little effort. The use of a steam generator designed according to the continuous flow principle as waste heat steam generator of a gas and steam turbine system is therefore particularly favorable in order to achieve a high overall efficiency of the gas and steam turbine system with a simple construction.

A heat recovery steam generator in a horizontal design offers particular advantages in terms of manufacturing effort, but also with regard to required maintenance work, in which the heating medium or heating gas, that is to say the exhaust gas from the gas turbine, is guided through the steam generator in an approximately horizontal flow direction. In the case of a continuous-flow steam generator in a horizontal design, however, the steam generator pipes of a heating surface can be subjected to a very different heating depending on their positioning. Especially when connected to a common collector on the output side

Steam generator tubes can lead to different heating of individual steam generator tubes leading to a merging of steam streams with widely differing steam parameters and thus to undesired losses in efficiency, in particular to a comparatively reduced effectiveness of the heating surface concerned and a reduced steam generation as a result. Different heating of neighboring Steam generator tubes can also lead to damage to the steam generator tubes or the collector, particularly in the mouth area of collectors. The use of a continuous-flow steam generator designed as a waste heat steam generator for a gas turbine, which is desirable per se, can thus cause considerable problems with regard to a sufficiently stabilized flow guidance.

A steam generator is known from EP 0944 801 B1, which is suitable for a horizontal design and also has the advantages of a continuous steam generator. For this purpose, the known steam generator is designed with regard to its continuous heating surface in such a way that a steam generator tube which is more heated in comparison to a further steam generator tube of the same continuous heating surface has a higher throughput of the flow medium in comparison to the further steam generator tube. The continuous heating surface of the known steam generator thus shows in the type of flow characteristic of a natural circulation evaporator heating surface (natural circulation characteristic) when different heating of individual steam generator pipes occurs, a self-stabilizing behavior which, without the need for external influence, leads to an adaptation of the outlet-side temperatures even on differently heated, parallel flow medium switched steam generator pipes leads. However, the known steam generator is comparatively complex in terms of construction, in particular with regard to the water and / or steam side distribution of the flow medium. In addition, problematic differential expansions can occur between adjacent evaporator tubes, which can lead to inadmissible thermal stresses and thus damage to tubes and collectors.

The invention is therefore based on the object of specifying a steam generator of the type mentioned above which can be produced with particularly little effort and which can also be used with different thermal stress has a particularly high mechanical stability.

This object is achieved according to the invention in that one or each of the steam generator tubes each comprises an approximately vertically arranged downpipe section through which the flow medium can flow in the downward direction and an approximately vertically arranged riser pipe section downstream of the flow medium side and through which the flow medium can flow in the upward direction.

The invention is based on the consideration that, in a steam generator that can be produced with particularly low assembly and production expenditure, for a particularly stable and, in particular, insensitive to differences in thermal stress, the design principle of a natural circulation characteristic used in the known steam generator for a continuous heating surface is consistently expanded and should be further improved. The continuous heating surface should be designed for an application with a comparatively low mass flow density with a comparatively lower friction pressure loss.

In order to support the natural circulation characteristics of the throughflow which are effective in this design, the steam generator tubes of the once-through heating surface are each divided into at least two segments (of parallel tubes), the first segment comprising all pieces of downpipe and flowing through in the downward direction. Accordingly, the second segment includes all riser pipe sections and is flowed through in the upward direction. In the downpipe sections of the first segment, the contribution of the geodetic pressure, ie essentially the weight of the water column, thus acts in the direction of the intended flow and favors this through a positive contribution to the pressure change along the flow path, ie through pressure gain. The contribution of geodetic pressure only acts in the second segment or riser section. against the intended direction of flow and thus makes a contribution to pressure loss. In total, however, the two geodetic pressure contributions can almost cancel each other out; it is even conceivable that the flow-promoting geodetic pressure contribution in the first segment or downpipe section exceeds the flow-inhibiting geodetic pressure contribution in the second segment or riser pipe section, so that, like in natural circulation systems, there is an overall flow-maintaining or flow-promoting pressure contribution.

The downpipe section of each steam generator pipe in the heating gas channel is expediently arranged behind the riser pipe section assigned to it in the heating gas direction. In other words, the steam generator tubes are expediently positioned spatially in the heating gas duct in such a way that the first segment or downpipe section, viewed on the flow medium side, is arranged downstream of the second segment or riser section, on the flue gas side, seen from the flow medium side. With such an arrangement, each riser pipe section is thus exposed to a comparatively stronger heating by the heating gas than the downcomer pipe section assigned to it of the same steam generator pipe. This means that the relative proportion of steam in the flow medium in the riser section significantly exceeds the relative proportion of steam in the flow medium in the down pipe section, so that the geodetic pressure contribution, essentially given by the weight of the water-steam column in the respective pipe section, is significantly higher in the down pipe section than in the one assigned to it riser piece.

A particularly simple construction of the once-through heating surface, on the one hand, and a particularly low mechanical load on the once-through heating surface, even with different thermal pressures, on the other hand, can be achieved by, in a further or alternative advantageous embodiment, the downpipe piece of one or each steam generator pipe with the riser pipe piece assigned to it on the flow medium side via an overflow piece connected is. With such a design cυ CO M t \ 5 F ¹

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weakly preheated flow medium flowing out of the downpipe pieces.

In the case of the comparatively strongly heated riser pipe sections, the overall flow-promoting geodetic pressure contribution by the upstream down pipe section is particularly large, so that a particularly strong additional supply of flow medium from the assigned down pipe section takes place automatically. In this case, the automatic additional feeding from the assigned downpipe piece takes place especially for highly heated pipes, so that the desired natural circulation characteristics are particularly enhanced.

In order to provide the flow-promoting geodetic pressure contribution in the respective steam generator tube, the respective steam generator tube can be designed in such a way that it comprises only one downpipe piece and only one riser pipe piece downstream of this on the flow medium side. A particularly high degree of flexibility in adapting the heat absorption capacity of the flow medium flowing through the steam generator tube to the temperature profile of the heating gas flowing through the heating gas channel can, however, be achieved in that a number of the steam generator tubes each comprise a plurality of downpipe and riser pipe sections alternately connected in series on the flow medium side. Each of these steam generator tubes, viewed in the direction of flow of the flow medium, initially has a first downpipe piece, which, after a suitable deflection, preferably via an overflow piece, is followed by a first riser pipe piece designed to flow through the flow medium in the upward direction. This is followed, preferably also after a suitable deflection via an overflow piece arranged inside the heating gas duct, by a second downpipe piece designed for the throughflow of the flow medium in the downward direction. A second piece of riser pipe is then connected to the second piece of downpipe. Furthermore co co MM

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Φ P- tr FF Φ 3 d rt φ ti 03 Fö tr PJ PJ 3 K tr d • d FF F- F d vQ F 01 S rt 01 Ό iQ F- 01 s: Φ PJ F φ F Ω F • d es φ F- PJ Hi s: d Hl

Φ φ rt Φ. HI Φ PJ 01 OJ tr Φ d P- 03 tr φ Hi DJ F F- d Ω φ Q 03 d • PJ d CΛ φ φ 03 tr rt Φ d INI X d Ω d rt ^ qd Φ 01 Hi N rt tr F PJ F- DJ s: d o. Tr P- ö et F F- φ F- ^ Q d pj: EV d: Φ F 03 F- ιq Φ "3 N i 01 M Φ tr F- d F- FN d ö FP, 03 α F? 03 Ω 03 ^ N d DJ F φ Φ 1 Φ rt F-

PJ d Φ O: Φ Φ DJ d d d CΛ rt PJ P- rt> V Ω PJ Φ α 03 01 d Φ 03

SF φ iQ 01 3 d 01 3 P- F d F rt 03 d Φ F tr F ¹ ddd rt P. Ω vq d XF Φ o PJ Φ d iQ Ό d Ω iQ Ω F d FO: N PJ M ιq F d φ Φ tr φ d F- dd EV d α d Φ α Hi tr tr O: • 3 d HF Φ Ω <q 3 F PJ F P- F F- PJ rt rt d Φ 3 υq F PJ Φ N 3 3 dd 3 rt OF tr • d F ¹ . Φ d

DJ Φ P- F DJ 01 F 3 F d P- F- DJ d F PJ d F- φ tr F Φ φ Q rt <l α F Ω

<Q F et 3 O • d N <! rt d d O F iQ d rt F 0 F F PJ Φ o DJ Φ tr φ F- N PJ d φ tr Fi Φ φ d Fi ιq tr F- 01 P- Φ 03 tr P- N DJ 01 rt F 3 Φ d

DJ 03 d tr F P. F Φ d F <3 J 03 01 d Hi Φ d rt F φ P- rt rt »rt • d F & dd rt <! = ^> d P- F <q <! Φ Φ F- rt O: 01: φ φ dd Φ Hi Φ o

Hl P- Φ DJ: 3 d NN φ pu: φ FF d F tr F rt Ω NFF tu F- rt σ F Ω s: EV FF 3 d Φ F 01 F iQ P- 03 O: Φ P- F- EV 3 s, rt tr Φ F ^> d DJ tr

DJ rt PJ 01 d F 01 iQ F ¹ PJ rt 3 Hi Φ F- d F- φ φ DJ P- F- t F 3 V d P- PJ: 03 d Φ iQ O P- Φ 3 PJ rt P- F 3 d rt P- ddd PJ tr • d Φ 3

P- 03 01 Hi P- F- Φ tr iQ Φ P- • d tr Φ ddd 1 ιq Φ α Hl F- Hi F- Φ rr 01 P. Ω 3 d FF Φ F- Ω Fi F- P- Φ d Φ <5 Φ P- rt d φ tr tr

Φ P- d tr Φ F 03 F Ω tr Φ tr F "Φ F Hl F- o o O Φ Φ Φ Φ F Φ F

F N vQ F J 3 3 O tr 01 F F- Φ P- F 01 s: Φ d P- F F P- oi F d N d Φ

F d φ Ω F Φ tr Φ SI 03 s; d rt tr Ω rt Pi: P- Φ Φ rt d φ s: PJ Φ Fi F

Φ t-r PJ tr <! F F Φ s: Φ PJ = Φ tr σ Φ F d 3 F Φ d Φ F d d O Φ

F- Φ σ 03 EV F φ 01 N F- Φ P- d rt F- Φ F d rt Φ F- φ P- F- υq

Ω 3 d rt rt tr F F- 01 F- 03 P- Φ N dd 03 3 F- 3 rt N CΛ oi PJ φ ιq ^ tr FF Φ φ iQ F- Φ Φ 03 Φ Ω dr Ω CΛ F d φ Φ d Ω φ iQ F φ PJ tr 3 Ω O: F tr 3 Φ tr "Φ SI EV Φ H- tr 03 oi tr Φ

PJ P- tr 3 F- Φ Φ tr Φ d rt PJ tr ao Ω P- S F tr Φ DJ DJ tr DJ d F- "

F rt 01 rt 01 F- P- <! DJ F- iQ F- P- <! 03 Φ 3 tr Φ 03 φ F- rt F ¹ Φ <! PJ F rt Φ rt N Ω Φ F d Φ Φ rt F- φ 03 P- φ rt 03 ≤ rt 03 d N rt P- Φ 01 Ω O tr F d μ. rt tr F • * Φ FO Φ F Φ rt dd Φ D>: d rt • Hr d NF tr tr

F- Φ O: E φ 01 ^ q μ. F F> FF rt d 3 F Fi Φ Φ d tq s: iQ F d 03 3 CΛ d 2, F ¹ 0, ≥! d P- Φ tq PJ 03 J iQ rt P- tr d ιq PJ Φ & φ 1

P- od Φ υq Φ φ F- DJ iQ iQ F Φ 3 Pi: iQ 03 01 q Φ Φ 01 d tr 01 φ dd Ώ Φ ö F- P- φ rt Φ Φ DJ F • dd Φ rt F φ d F EV 01 μ. Ω d

3 P- iQ 3 s: PJ 01 Ω d d F tr PJ Fi d = 01 d F F- d DJ φ Φ rt tr d

Φ Φ Pi: 3 Φ tr tr F Φ Φ Φ r FO: Ω F- dd F- frt N PJ P- α. F P <d tr • d Φ d *> g F ¹ φ F Φ u Ω 3 tr dd iQ d rt • φ F ¹

PJ 03 Φ rt F Hi tr N p- 3 Φ DJ 01 tr F PJ tr d rt 01 03 F- P- rt CΛ

01 F Φ Φ O: d F "03 01 P- tr ^<<Φ 3 03 dd ⁱ Q N tr vq ö J Φ rt Φ iQ F tr PJ tr Φ 01 F- 03 F P Ό rt iQ φ Φ d ds : PJ 3 rt Φ

CΛ Φ Ό Φ P- N Φ Φ F- dd Φ d F- rt Φ Φ FI F 01 ^ q 03 03 F Φ Φ tr Ό F- rt FJ F- 01 Φ F F- d Hi dd P. 3 Φ P - d φ O: 3 rt o Ω F- Φ HI 03 ^ q φ P- J d et rt F 3 φ P d H EV d F- Φ

^• d3 d Φ d Φ Ω ι 1 3 Φ 1

F- d Φ φ 1 d φ F tr 01 φ 1 ^ Q 1 P ^, F ¹ 1 F 3 Φ F F- 1 1 1 rt 3 DJ 1 Φ J F- 1 1 F 1 d 1 1 1 II

large piece is connected directly to the downpipe piece assigned to it and without the intermediary of a complex collector or distributor system. The steam generator thus has a comparatively low system complexity with a particularly stable flow behavior. In addition, both the downpipe section and the downstream pipe section of each steam generator pipe can each be attached in a hanging construction in the area of the housing cover of the heating gas duct, with a free longitudinal expansion in the lower area being permitted in each case. Such longitudinal expansions caused by thermal effects are now compensated for by the overflow piece connecting the respective riser pipe piece to the down pipe piece, so that no stresses occur due to thermal effects.

Embodiments of the invention are explained in more detail with reference to a drawing. In it show:

Figures 1, 2 and 3 each in a simplified representation in longitudinal section of a steam generator in a horizontal construction.

Identical parts are provided with the same reference symbols in all figures.

The steam generator 1, 1 1 * according to FIGS. 1, 2 and 3 is connected in the manner of a heat recovery steam generator downstream of a gas turbine, not shown. The steam generator 1, l ^λ , 1 each has a peripheral wall 2, which forms a heating gas duct 6 for the exhaust gas from the gas turbine, through which the heating gas direction x can be flowed, in an approximately horizontal direction indicated by the arrows 4. In the heating gas channel 6, a number of heating surfaces designed according to the continuous principle, also referred to as continuous heating surfaces 8, 10 and 12, is arranged. In the exemplary embodiments according to FIGS. 1, 2 and 3, only one continuous heating surface 8, 10 and 12 is shown, but a larger number of continuous heating surfaces can also be provided. The evaporator system formed from the continuous heating surfaces 8, 10 or 12 can be acted upon with flow medium W, which evaporates once through the respective continuous heating surface 8, 10 or 12 and after exiting the continuous heating surface 8, 10 or 12 dissipated as steam D and superheater heating surfaces are usually supplied for further superheating. The evaporator system formed from the respective continuous heating surface 8, 10 or 12 is in each case connected to the water-steam circuit of a steam turbine, not shown in detail. In addition to the respective evaporator system, a number of further heating surfaces 20, each indicated schematically in FIGS. 1 to 3, are connected in the water-steam circuit of the steam turbine. The heating surfaces 20 can be, for example, superheaters, medium pressure evaporators, low pressure evaporators and / or preheaters.

The continuous heating surface 8 of the steam generator 1 according to FIG. 1, in the manner of a tube bundle, comprises a plurality of steam generator tubes 22 connected in parallel to the flow through the flow medium W. In this case, a plurality of steam generator tubes 22 are arranged side by side as seen in the heating gas direction x. Only one of the steam generator tubes 22 arranged next to one another in this way is visible. The steam generator tubes 22 arranged side by side in this way are each connected upstream of a common distributor 26 and a common outlet header 28 on the flow medium side. The distributors 26 are in turn connected on the input side to a main distributor 30, the outlet collectors 28 being connected on the output side to a common main collector 32.

The continuous heating surface 8 is designed such that it is suitable for feeding the steam generator tubes 22 with a comparatively low mass flow density, the steam generator tubes 22 having a natural circulation characteristic. With this natural circulation characteristic one compares to ω co ho N) F ¹ P>

Cπ 0 Cπ O Cπ 0 Cπ

Hi P- PJ ö 01 EV 01> Hi P- F- ιq Hl 03 ö 03 3 03 t 01 3 Hi CΛ 3 Ω EV ιq Hi Φ φ O ddd et PJ 0 F "d: 01 03 P = rt P rt d Ω) rt d Φ d tr O Φ F ¹ F "F-

P- M F EP F F d d rt F rt et 01 tr d = 01 d: d tr d d p: tq d φ d 01 Φ p: d

01 ιq Ω φ Ω dd P_ Φ EV F Ω Ω iQ P Φ Ω ιq Ω 3 ιq F 03 F- Ω Φ φ φ tr F tr EV Φ F CJ. P d? R CΛ? V 03 F ¹ F- EV 01 tr Φ ω N rt CΛ Ω tr 3 d tr rt F- F d J 01 Φ dd rt 3 rt d 3 Φ d 3 d F rt tr φ

F. Φ DJ DJ F- d Φ J 01 O P- P q co Φ CO φ Φ ω φ rt φ 03 d F Ξ

PJ: P- d <! 01 rt O H 03 j- »F- c p. rt P, ^ P. co rt EV O: N 00 Φ d H d tr Hi Φ tr d F- tα P- Ω 01 tr ιQ μ- Φ Φ P- d P- Φ rt 3 d F-

3 d Φ tr d Φ d <J Φ PJ tr Φ P- F d 01 3 d P. 3 d H F- d 3 3 rt

P- d & Φ 01 rt P- 03 σι F- PO 3 • _^ H 3 P Hi 3 <ld φ φ

F- Φ F- o 0 Φ EV N 01 01 tr tr ^ 3 tr P 03 Φ Φ iQ s: tr F

Ω F- PJ 03 N. d FO: <q P- ^ q * d Φ F SI PPJ Φ 03 01 dd 01 Φ F φ tr Φ d Fi φ P <tr d PJ P, PJ φ P- F- 01 d N P- 03 φ ~> 3 F- tr d

01 ffi P * F Φ PJ d 01 F- 03 Hi Φ rt F- d H s: p- rt F- S Φ rt Φ

P- Φ p. φ PJ: FF ¹ Φ φ 03 d = F ¹ : d: dp: F Φ d Φ et d P- Φ tr α d 3 F- F- Ω tr Φ tr d tr tr Ω tr O F- P- CJ. P- 3 rt P- F Φ P

Φ N tr Φ d F P- F 03 Φ EV Φ tr rt Φ ^ q Hi rt d Φ F- α ^ d 01 vq φ rt Hi P- F φ F- rt P- F d F F Φ S d

P- P Φ 3 d N M * d

Φ DJ Φ PJ F d P. F- Ω Φ d CO Hi d 03 d ≤ P Φ P- 03 F ¹ 03 rt Hi

F P- 01 00 F- F Φ Φ tr PJ d P. φ s: rt p: d 01 d 03 d ö Φ φ

PJ EV Φ 01 rt σ d F- p: d: CΛ F d rt SI P 01 F

3 d PJ <i tr Cb P- P- PJ P- d P- F <! Ω Φ rt p: ö ^ u P N

P: F- iQ d O Φ tα tr P- F P- 03 rt Φ EV iQ 01 tr P Φ P- d P * d α Φ tr 03 Φ PJ F F- d Φ Φ Φ Φ 01 N Φ CJ: rt 01 F 3 F Φ 3 P- P- Hi d Hi P d

Φ et 01 F ¹ ^ q Ω P- F rt d tr F et co Φ F- F • d tr φ Hi Φ 3 cq

Ω 01 Φ tr ^ N 1 tn <! Φ F ci φ 3 F- P- J ^ d Ω d Hi Φ tr • F Ό Φ

P- P- tr oi Φ PJ ^ q rt 0 φ H tr F P- Ω EV rt tr Φ α Φ NF φ φ F ¹ σi Φ d F ¹ PJ F Ω FF ^{1 '} F Φ 01 rt tr P 01 rt F <qd 03 α Φ φ F

FF o tr -> 01 O: tr Φ d pj: F rt rt F ¹ rt dd N φ F 0 3 d FO

01 iQ φ o EV 3 • d d d d 03 F α d F 3 d Φ Φ 03 Ω d <q N tr

^ d H 01 Φ d F iQ J 01 iQ iQ 3 rt O: Φ d P O: Hl ^ q F d Ω tr P- Φ Φ F

PJ d φ Hi = d = d et PJ d F 3 3 iQ d 3 P et uq tr φ P- F d rt dd: 01 dd PJ d: rt d P- F- O: oi LP d 01 P- φ PPF Φ F uq ro s: φ φ P. 01 F ¹ Ω et iQ d Ω 3 rt P- Φ d 01 d EV FF ¹ d 03 03 0 φ)

F i: d F F- Φ rt 01 EV Φ tr 03 d: tr d O iQ rt FPF rt Fi tr F o 03 rt dd F- Φ P- ^ Φ rt Ω 3 FF 01 Ω F "0 Φ tr N 3 FF tr 03 H Φ ιq cy> J-. Φ P- d: EV Ω 3 CJ. Tr tr rt Φ d P- 0 Φ

F Φ d d 01 Φ PJ O 01 ιq Ω N IT d φ Φ 01 P F Φ F- <J rt N> tr F

01 F rt o F- 01 ^ qdd ^ EV ω d 03 Φ P- a. rt d N Φ N) F 03 rt ds: CJ: d φ Φ Ω d Λ F F- Φ co iQ rt rt P- Φ F υq N CΛ Hl F tr Φ d: d DJ: tr> Φ P- Hl tr d et! X φ F Φ d 01 O: Φ IV) Φ F ^{1 1} Φ tr N>

Ω q 01 φ. d d: F F P> P- F- <0 O: 01 3 O ιq p: p>: 03 O: M tr

EV 03 01 F H tr DJ O: φ d Φ F a 01 u 0 F 3 Ω 03 0 tr φ

Φ 01 φ 01 α d F d iQ 3 d F d F & d 01 P P P- φ Φ tr 01 d φ Φ d

PJ F rt F- rt rr EP Φ d P- d Φ tr d P d Φ 3 F d F d φ P- F F-

PJ ad F Φ §: PJ φ F d Ω d F d Φ F F- • d Φ Φ rt IQ Φ φ d ö d 3 _j d O: 01 p: 01 03 F F- iQ tr> q tr d rt Φ rt Hi 01 rt ü Φ 00 Φ F d Φ d uq IQ 3 φ 01 01 φ tr d 01 rt P φ 03 <i F- Φ Φ d • 01 d F

Φ φ 03 oi 01 P- PJ uq> Q C Φ d 0 U3 F ^ d 03 F N S | ö Ω

O F 03 rt EV Φ PJ d H, d 3 d tr d CΛ 3 N P ^ Ω M s: φ φ d P- tr

F PJ d: DJ F d tr d = Φ PJ F h rt d Φ H tr 3 Φ F- P- F 3 F ¹

<j Ω dd 01 ιq F EP Ω P Φ CΛ P d H <! F ¹ P- 01 d Ω P do 3 _j EV dd α F- 01 01 tr Φ HF ¹ F- rt Ω υq FOP φ Φ Hi tr <d

Φ F Φ vQ EV F- P- iQ Ω et 03 3 ιq F tr Φ 0 3 d F 01 P 01 φ Hi rt N Φ d tr O φ d tr PJ: φ FFO: F tr Hl 03 rt 01 Ω PF tr d F P- d 03 01 F- d tr F- tα> OO 1 φ FF 01 tr rt F P- tr rt i Φ u ω F- Φ 1 tr 01 F- F ¹ d Φ d tr tr 1 O 1 rt Φ Φ O: 1 Φ N F-

01 01 φ co F Φ rt rt P- Φ F- 03 FF tr F P- d 1 d N o 1 F 1 • rt Ω N 1 1 1 FO: N 1 1 01 tr 1 1 1

that the mobility of the heating pipe pieces with regard to thermal expansion remains unimpeded.

As can be seen in FIG. 1, each steam generator tube 22 of the continuous heating surface 8 has an almost U-shaped shape, the legs of the U being formed by the downpipe piece 34 and the riser pipe piece 36 and the connecting bend by the transfer piece 38. In the case of a steam generator tube 22 of this type, the geodetic pressure contribution of the flow medium W in the area of the downpipe piece 34 - in contrast to the area of the riser pipe piece 36 - produces a flow-promoting and not a flow-inhibiting pressure contribution. In other words: the water column located in the downpipe section 34 with unevaporated flow medium W “pushes” the throughflow of the respective steam generator tube 22 instead of hindering it. As a result, the steam generator tube 22 overall has a comparatively low pressure loss.

In the approximately U-shaped construction, each steam generator tube 22 is suspended or fastened to the ceiling of the heating gas duct 6 in the entry area of its downpipe piece 34 and in the exit area of its riser pipe piece 36 in the manner of a hanging construction. In contrast, the spatially lower ends of the respective downpipe piece 34 and the respective riser pipe piece 36, which are connected to one another by their overflow piece 38, are not spatially fixed directly in the heating gas channel 6. Length extensions of these segments of the steam generator tubes can thus be tolerated without risk of damage, the respective overflow piece 38 acting as an expansion bend. This arrangement of the steam generator tubes 22 is thus mechanically particularly flexible and insensitive to differential stresses with regard to thermal stresses that occur.

An overheating of a steam generator tube 22, in particular in its riser tube section 36, initially leads there to o co M

Cπ o Cπ Cπ Cπ

oo to co P ¹ F ¹

Cπ o Cπ o cπ O Cπ

& 01 3 PL Hi σ oi EV P- P ¹ K PL uq <l PL ü uq 03 α Φ oi P. <P- H, Φ <to P CΛ d co

P- rt d F- PP • d P ¹ P d Φ P Φ O Φ F Φ rt P φ P ^J F- φ & Φ dd P- φ to d rt Φ σi φ d: dd H 3 P- et d ω F dd Φ F dd OF 3 F ¹ Ω d uq F tr d F CΛ F

Ω uq 3 • d Φ Φ d tr d • d p- rt rt Ω O: ^• dd tr F ¹ PL F φ tr X uq O: Φ P-

EV 01 01 Hi F ¹ F Φ rt! Λ Ω Φ F ¹ EV p: 3 Hi P P- rt tα φ Φ F- rt P φ φ 3 F d μ. Φ α oi φ d 01 to <! o tr F- F- tr rr rt Φ Ω d ¹ P F- d Φ S F- * dd tr φ d φ Φ Φ F uq P o cn Φ tr oi Ω φ F- Φ F tr F P- d Ω rt 01 P, 01 rt 01 F d O: tr

01 P- F- N φ rt d F F x tr tr P- 03 03 INI Ω Ω • d tr 01 Φ P tr Φ Φ i: uq tr φ

^ Cπ rt d Φ 3 P- et F Φ P rt Ω Φ tr tr rt d • d tr F d d uq 03 rt 01

P CΛ F- d pj: <l Φ Φ Φ φ P- Hi 0 F tr <l d d 01 d F! Λ Φ tr rt 3 Φ O

H rt uq ^ uq EP FX P- F- 01 rt tr P Φ Φ uq ω P 01 P uq Φ φ F- Φ uq φ φ dd FP Φ d Φ φ P * t φ Φ u F φ P ¹ d φ a Ω F- tr Φ P- d tu α

F P O: M F ^ d 3 F- Φ Φ 03 F α F φ Hi F- jü P tr tr> Φ uq Φ P- Φ

O Ω 3 Φ P ¹ F F- Hi PP ¹ F d tr Φ 01 P. FP 03 uq Φ d φ Φ Φ o P- Φ 01 ≥; F 01 F tr tr d XFO uq P d 01 o F- rt Φ d 3 dd Φ φ F d EV N d Φ P 3 »d Φ

F uq d φ O tr d oi Ω co p. tr d Φ 03 Ω d P ¹ d Φ FF p, <l P dd: rt Φ 3

01 φ u P- tr FF 01 tr Φ o Φ Φ -> F- EV Hi • _^ uq d CJ. o P * d tr F- d SI P- rt 01 01 P ¹ F Φ et P- 01 d uq d tr φ 03 α co φ <d uq φ d F 01 S

0 Ω 3 01 01 to Φ d d P. Φ P Φ F • d tϋ P t X Φ N F d φ d P

Ω tr φ et Cπ PL P- Φ d α to P d Ω F- 03 ^ d O

P Φ 01 • tr rt φ "» d tr • M φ F d Φ tr 3 F d EP

EV P φ 0 O Φ d P. d φ P- uq ü F F- P "Φ f-> Hi uq φ

Φ F ¹ F- P- Ω PF 01 α 3 P- uq F uq EV F Hi P- F ¹ FP d Ooi PO rt dd EV P- N rt F P. • d tr Φ ü φ P 3 rt F " dd P- O: ä φ Φ EV od F ¹ PL d:

Cπ Φ 3 φ dd σ Φ o Φ Fi d F Φ 03 uq φ ^ φ P 01 uq EP * d FFP d Fi uq Φ tr t et oi Cπ PP * 03 d Φ d oi 01 Ω d O P- F rt φ Φ Fi tr P * Ω rt 01 Φ

K I φ φ 3 oi F uq rt tr tr PL rt EV PL tr P F d F Φ O:? D Φ tr. F

CJ- F- SI φ F- F- • d tr Φ F- N 01 Φ P P Φ P Φ Φ 3 O: rt F tr Φ d F P 01

Φ 03 tr P dd Hi PP ¹ tr Φ α F ¹ d tr d F Φ 3 H Φ N rt F- d φ F Φ rt

X rt • d F d Φ φ Φ F φ d d F <tr rt Φ d t rt Φ φ d Φ Φ tr rt 3 P d X Φ

Φ. P N Hl 3 F F- Φ uq d Φ Φ 03 F <! it-. Φ d 3 d d Φ Φ EV φ P-

P- F P ö N d d φ Ω F EV rt rt Φ P- O F PL • d? T uq F £ rt uq F- uq

F "ü P tr Φ φ d φ P. F F EV P- P φ F F- Φ F Φ Φ 0 φ LSI <! 01 P Φ F F" rt

01 P- F ¹ P ¹ μ. FF d φ F- 01 <! P dd O: rt F uq tr F tr F d O Ω EP F d F- φ F "03 03 Ω uq F Ω φ Φ 3 d 3 uq φ Φ d ^ d PFH, d tr Φ F- d uq

3 φ <J φ rt tr φ tr s: P ¹ F • d N d Φ PL 03 oi d F rt X od P- 01 φ 01

F- CJ od Φ FF et Φ F ¹ Hi Φ X d 03 d φ o P F- d F- tr tr σ φ Φ rt do rt tr dd P Φ d F- dd Φ oi Φ uq rt F tr d tr 01 FFFFP P- P- F- α

Φ ιq d F ¹ uq d F ¹ P 01 F F- Oi Φ Ω Φ P. tr Ω s: EV F ¹ d EV F- CΛ α α F Φ Φ P. CΛ Hi _^ Φ uq 01 Ω rt 01 P rt tr tr d Φ p: tr Φ d to <J ^• d F- Φ et P

Φ 01 01 P- φ Φ tr tr φ d Φ φ Φ F d P. F d t o Hi Ω 01 P. 01 Φ 01

F rt Ω d 3 uq Φ F- tr N P 43 03 d a rt Φ 3 01 uq P rt uq ^ d Φ tr φ Φ φ P- 03

F tr P 3 F- 3 P to d ^ d 3 a Φ F- F- 3 Φ F Φ ¹ FF uq

F- O: P d φ ISt F uq F- oi Φ Φ <! Φ d tu tr uq • d 01 oi CΛ NF tr FN tr 3 F ¹ P. φ d Hi Φ uq N d uq Φ d 03 Φ O Hi Φ φ o rt Φ 01 α 01 O dd 01 rt φ PL rt d P 0 O dd rt d F PL rt P rt 3 <! F- F- F d tu rt P o tr 01

Φ rt Φ FO p: 01 d FFFF ¹ d P. Φ F tr F oo F- d tr PL O: uq Φ 03 M 3 F DJ: dd = rt Ω J. Ω Hi 01 uq P, Φ Fi uq P d O: s: P- uq d 03 01 01 P 3 φ tr rt • d F- 01 rt

Ω Φ N tr Φ tr 0 uq φ d P ¹ uq 0 03 3 3 p: Φ Φ rt φ rt oi d F Φ P rt rt N

N EV dd X Φ tr φ 01 Φ φ F * d Ό uq d F tr d P- rt rt 01 d F F- tr Φ 0 F ¹ d Φ F 03 Φ F tr O rt N dd Hi φ d rt 03. φ 01 N p: uq o N F- F tr Ω F- uq CΛ rt F- P ¹ d P- tr Φ X • Φ d Φ o uq 03> d FO rt rt P oi tr d F ¹ Φ? V Ω φ Cn rt σ FF od P d F- F- EV F PL 03 d 3. P- d 3 F d P- φ 01 01 tr

0 er. Φ d O: 01 uq P H 03 ü d rt 03 p: Hl P, d F- F- uq Fi Φ φ uq ω d o

F * »F- F 3 01 Φ et <! Ω P Φ P Φ rt O: d EV d rt ö uq d F- uq d o d

P. uq Ω d Φ P- tr et Φ Φ tr N d tr uq F- FF rt PL Φ φ F F- P Φ Φ α cy> od 0 F tr d tr φ Φ rt F Φ d tr 3 03 PL Ω F- tr F p- dd to d FF Φ o φ tr O 01 uq Φ F P- 01 et d <ip: φ Ω Φ tr P- <l F- dd 3 to Hi Φ FF 3 tr rt Φ t rt 03 d Φ 1 Φ Φ F- Φ dd tr F 1 Φ F- d F- φ PL do 01 P-

Φ FFF 3 1 d F- PL F- 01 F uq rt φ d 03 P. I d si P- tr rt Φ d 1 θ: φ d P- 1 Φ rt 1 F- 03 dd φ F F- 1 1 φ 3 uq Φ 1 03 φ 1

A plurality of riser pipe pieces 54 are connected, are in turn guided in the exemplary embodiment within the heating gas channel 6 and held in a perforated plate 58. If necessary, however, they can also be laid outside the heating gas channel 6. In the exemplary embodiment according to FIG. 2, each downpipe section 52 is followed by 2 riser pipe sections 54 connected in parallel on the flow medium side. The pipes used have the same dimensions, so that the free flow cross section for the flow medium W in the riser pipe pieces 54 connected in parallel is twice as large as the flow cross section in the down pipe piece 52 upstream of them together. Alternatively, such a limitation of the frictional pressure loss in the down pipe pieces 52 if necessary, can also be achieved by suitable dimensioning, in particular by choosing a comparatively smaller diameter.

The steam generator 1 * in the exemplary embodiment according to FIG. 3 comprises a continuous heating surface 12, which is also designed for a comparatively low loss of friction pressure and is therefore particularly suitable for ensuring a natural circulation characteristic with a comparatively low mass flow density. However, the flow heating surface 12 of the steam generator l ^λ is also particularly adapted to the temperature profile of the heating gas flowing through the heating gas channel 6 with regard to its heat absorption capacity. For this purpose, each of the steam generator tubes 60 forming the pass-through surface 12 each includes a plurality — in the exemplary embodiment two — of downpipe pieces 62, 64 and riser pipe pieces 66, 68 connected alternately in series on the flow medium side

The direction of flow of the flow medium W, seen in the first downpipe section 62, is in each case connected via an overflow section 70 to the first riser section 66 connected downstream of it. This is in turn connected on the output side via an overflow piece 72 to the second downpipe piece 64 connected downstream. The second downpipe piece 64 is connected to the second riser piece 66 via an overflow piece 74. The Overflow pieces 70, 72, 74 are in turn guided within the heating gas channel 6 and fastened in the floor or ceiling area of the heating gas channel 6 via a perforated plate 76, 78 and 80, respectively.

Claims

claims

1. Steam generator (1, l ^λ , l ^λ ), in which a continuous heating surface (8, 10, 12) is arranged in a heating gas channel (6) through which the heating gas channel (x) can flow in approximately horizontal direction (W) comprises steam generator tubes (22, 50, 60) connected in parallel, and which is designed in such a way that, compared to a further steam generator tube (22, 50, 60), the same continuous heating surface (8, 10, 12) is more heated

Steam generator tube (22, 50, 60) has a higher throughput of the flow medium (W) compared to the other steam generator tube (22, 50, 60), characterized in that one or each steam generator tube (22, 50, 60) each has an approximately vertically arranged, comprises a down pipe section (34, 52, 62, 64) through which the flow medium (W) ^'can flow in the downward direction and an approximately vertically arranged riser pipe section (36, 54, 66, 68) arranged downstream of this on the flow medium side and through which the flow medium (W) flows in the upward direction ,

2. Steam generator (1, 1 1 ^ΛΛ ) according to claim 1, ^wherein the downpipe ^piece (34, 52, 62, 64) of the respective steam generator tube (22, 50, 60) in the heating gas channel (6) seen in the heating gas direction (x) is arranged behind the riser pipe section (36, 54, 66, 68) assigned to it.

3. steam generator (1, l ^λ , 1 *) according to claim 1 or 2, wherein the downpipe piece (34, 52, 62, 64) of each or each steam generator pipe (22, 50, 60) with the associated riser pipe piece ( 36, 54, 66, 68) is connected on the flow medium side via an overflow piece (38, 70, 72, 74).

4. steam generator (1, l ^λ , 1 ") according to claim 3, wherein the respective overflow piece (31, 70, 72, 74) is arranged within the heating gas channel (6).

5. Steam generator (1, l ^λ , 1 *) according to any one of claims 1 to

4, in which one or each steam generator tube (22, 50, 60), in the manner of a forked version, has in each case a plurality of common downpipe pieces (34, 52, 62, 64) connected downstream on the flow medium side for flow through the flow medium (W) includes riser pipe pieces (36, 54, 66, 68) connected in parallel.

6. Steam generator (1, 1 1 ^N ) according to one of claims 1 to

5, in which the riser pipe and downpipe pieces (36, 54, 66, 68 and 34, 52, 62, 64) of several steam generator pipes (22, 50, 60) in the heating gas channel (6) are positioned relative to one another in such a way that one in the heating gas direction (x) seen down pipe section (34, 52, 62, 64) lying comparatively far back is associated with a riser pipe section (36, 54, 66, 68) lying comparatively far forward seen in the heating gas direction (x).

7. steam generator (1, l, 1 *) according to any one of claims 1 to

6, in which a number of the steam generator tubes (22, 50, 60) each comprise a plurality of downpipe and riser tube pieces (36, 54, 66, 68 and 34, 52, 62, 64) which are alternately connected in series on the flow medium side.

8. steam generator (1, 1 ^Λ , l ^Nλ ) according to any one of claims 1 to

7, in which a throttle device (42) is connected upstream of the downpipe section (36, 54, 66, 68) of each or each steam generator tube (22, 50, 60) on the flow medium side in the connecting line from the main distributor.

9. Steam generator according to one of claims 1 to 8, the gas gas side upstream of a gas turbine.