EP1249662B1 - Steam generator - Google Patents

Abstract

A steam generator for converting water to steam by the transfer of heat from a heating medium includes two or more water/steam circuits. Each water/steam circuit has at least one evaporator for transferring the heat from the heating medium to the water. A single water/steam drum receives steam or water and steam from the evaporators. A descending pipe has at least one bypass, from which the supply pipes of the respective water/steam circuits branch off, and a venturi device in the area of the bypass. The inlet opening of the supply pipe of at least one water/steam circuit is disposed in the area of diffuser-shaped outlet of the venturi device such that the supply pipe section acts as a dynamic compression pipe in order to increase the pressure of the working medium in this circuit. STEAM GENERATOR

Description

The invention relates to a steam generator, in particular a heat recovery steam generator or boiler for heating with hot exhaust gases.

Such steam generators are predominantly with hot exhaust gases from energetic and / or process equipment and often consist of several water-side strands or circuits that are not just about different geometries but also have very different heat absorption. For this Basically, it is often necessary to divide the circulation of water into individual strands or circuits z. B. with the help of throttle elements.

For steam generators with a forced circulation is known to be the distribution of Water circulation on individual water-side strands with the help of orifices, the at the entrance to the individual Heizflächenschlangen or strands are installed, controlled (La Mont System). The pressure difference between the individual pipe strands and the Throttle diaphragms is caused here must be generated by means of a circulation pump and be overcome.

A steam generator having the features of the preamble of claim 1 shows document EP-A-0 051 078.

The control of the amount of circulated water in a steam generator with a Natural circulation system is a more difficult problem because of these steam generators in the Usually no sufficient pressure difference for the installation of orifices available stands. The available pressure difference in the individual pipe strands or circuits is by the heating intensity, the height difference and the pressure loss in the individual Strands intended. The installation of throttle nozzles or orifices to improve the Water distribution is based here, the amount of water in the well-circulating strands to choke in the weakly circulating strands the water circulation over a increase lower friction pressure loss in the common fall and risers. The total amount of circulation in the system is thus often disadvantageously greatly reduced, for the strand concerned, i. the weakly circulating strand only a moderate Improvement can be achieved.

It is an object of the invention to provide a steam generator in which the Circulating water volumes are distributed more effectively in the individual strands or circuits can significantly affect the overall circulating water flow in the system.

The above object is solved by the features of claim 1.

Advantageous embodiments of the invention can be found in the dependent claims.

• Verteilung der Wasserumlaufmengen je Strang bzw. Kreislauf entsprechend den Anforderungen durch Druckerhöhung in dem Strang bzw. den Strängen, in dem bzw. denen eine Umlaufmengenerhöhung erforderlich oder gewünscht ist, ohne einen zusätzlichen Reibungsdruckverlust in dem Strang zu verursachen, der ohne Druckerhöhung auskommt, d.h. durch diese Maßnahme kann
  • a) fehlender Auftrieb in einem Strang oder mehreren Strängen kompensiert werden,
  • b) ein eigener hoher Druckverlust eines Stranges besser überwunden und somit mehr bzw. weitestgehend den anderen Strängen angeglichen werden,
  • c) eine Verdampfer-Einrichtung innerhalb eines Dampferzeugers, die einen höheren Kühlbedarf aufweist, wie z.B. eine End- oder Rohrplatte eines Rauchrohrkessels, mit einer höheren Kühlwassermenge beaufschlagt werden,
• Bewerkstelligung der Druckerhöhung in dem Strang bzw. den Strängen, in dem bzw. denen eine Umlaufmengenerhöhung erforderlich ist, ohne eine zusätzliche Pumpe vorzusehen.

The inventive solution creates a steam generator which has the following advantages:

• Distribution of circulating water per line according to the requirements of pressure increase in the strand (s) in which a circulation amount increase is required or desired without causing an additional friction pressure loss in the strand that does not require pressure increase, ie this measure can
  • a) lack of buoyancy in one strand or multiple strands can be compensated
  • b) better overcome its own high pressure loss of one strand and thus be more or more closely aligned with the other strands,
  • c) an evaporator device within a steam generator, which has a higher cooling requirement, such as an end or tube plate of a smoke tube boiler, are charged with a higher amount of cooling water,
• Achieving the pressure increase in the strand or strands, in which or an increase in circulation is required without providing an additional pump.

In an advantageous embodiment of the invention, the Venturi nozzle device by a in the Downstream of the water / steam cycle used venturi formed. Through this Measure, it is easy, the downpipe with a commercially available, standardized nozzle, For example, a Venturi nozzle according to EN ISO 5167-1, form.

An advantageous embodiment of the invention is that the venturi device by formed as a Venturi tube downpipe is formed. This is the Venturi device completely integrated in the downpipe and may possibly from the same Material and made from one piece.

Preferably, the steam generator according to the invention is operated in natural circulation. there can be one or more water / steam cycles, the one or more different Reason one opposite to another or further circuits weaker Have water circulation, be operated with an increased water circulation, without on having to resort to additional pumps, the investment, operating and Demand maintenance costs.

It is also advantageous to the steam generator according to the invention in forced circulation operate. It can be one or more water / steam cycles, or the different reasons one over another or further circuits have weaker water circulation, be operated with an increased water circulation.

In an advantageous embodiment of the invention, the ratio of the inner diameter d the venturi device at its narrowest cross-section to the inner diameter D. the downpipe between 1.0 and 0.01. This training ensures that adjusts the effect of an increased water circulation amount in the cycle, whose Inlet opening is located in the diffuser-shaped outlet of the venturi device.

Below are embodiments of the invention with reference to the drawings and the Description explained in more detail.

Fig. 1

schematisch dargestellt einen Abhitzedampferzeuger in Form eines Rauchrohrkessels in Seitenansicht und teilweise im Längsschnitt,

Fig. 2

eine Abzweigung an der Fallleitung des Dampferzeugers gemäß Einzelheit A der Figur 1 mit zwei Strangleitungen,

Fig. 3

wie Figur 2, jedoch alternative Ausführung,

Fig. 4

wie Figur 2, jedoch alternative Ausführung mit mehr als zwei Strang- bzw. Kreislaufleitungen,

Fig. 5

wie Figur 4, jedoch alternative Ausführung,

Fig. 6

Schnitt B-B gemäß der Figur 5,

Fig. 7

schematisch dargestellt einen Abhitzedampferzeuger in Form eines Wasserrohrkessels im Längsschnitt.

It shows:

Fig. 1

schematically shows a heat recovery steam generator in the form of a flue tube boiler in side view and partly in longitudinal section,

Fig. 2

a branch at the downpipe of the steam generator according to detail A of FIG. 1 with two branch lines,

Fig. 3

like Figure 2, but alternative design,

Fig. 4

like Figure 2, but alternative design with more than two strand or circulation lines,

Fig. 5

like Figure 4, but alternative embodiment,

Fig. 6

Section BB according to FIG. 5,

Fig. 7

schematically shows a heat recovery steam generator in the form of a water tube boiler in longitudinal section.

Figure 1 shows a steam generator 1, which is designed as a flue tube boiler and a Depicting heat recovery steam generator. The steam generator 1 essentially comprises a vertically arranged water space 29, the side by a jacket 27 and above and is bounded below by end or tube plates 23, 24. The water room 29 is from at least one bundle of flue pipes 30 passes through, which between the end plates 23 and 24 are arranged gas-tight and extend substantially vertically. The warming up the water in the water space 29 required heating medium or hot exhaust gas is fed via an inlet 21 and the gas inlet chamber 22 to the steam generator 1. From the inlet chamber 22, the heating gas enters the through the water chamber 29th leading flue pipes 30 and thereby gives heat to the water in the room 29 located Water off. Subsequently, the cooled heating medium passes over the Gas outlet chamber 25 to the outlet 26, from where it via lines not shown can be supplied to further process steps. According to Figure 1, the hot exhaust gas passed from top to bottom through the steam generator 1. This can vary depending on Requests also made from bottom to top. The water room 29 together with the smoke tube bundle 30 and the two tube plates 23, 24 form the evaporator device 4 of the first water / steam cycle 2.

The steam generator 1 according to FIG. 1 has two water / steam circuits or strands 2, 3 on. From the water / steam drum 6, which via a line, not shown Feed water is supplied, the water passes through a common downpipe 7, the leads away from the drum 6 and is formed substantially vertically, and on the Branch 8 in the two water / steam circuits 2, 3. The branch of the 8th wegführenden line 9 of the first circuit 2 leads the water through the in immediately adjacent the lower end plate 24 located entrance 15 into the water space 29th one. The result of the warming and the resulting buoyancy upwards flowing water or steam is in the region of the upper end plate 23 through the outlet 16 discharged from the water chamber 29 and the strand line 9 and riser 19 fed to the drum 6. Already generated steam can from the drum 6 via a Line 28 a superheater (not shown) in the steam generator 1 or another Purpose to be supplied. The unevaporated water is from the drum 6 again Circuits 2, 3 supplied via the downcomer 7.

The away from the branch 8 leading line 10 of the second water / steam cycle 3 according to the figures 1 to 3 according to the invention is designed such that the Inlet opening 14 of the strand line 10 just behind the narrowest cross section of Venturi nozzle means 11, 12, i. in the region of the diffuser-shaped outlet 39, and in arranged the center of the downpipe 7 and the strand line 10 is formed as a pitot tube. In the case of axial continuation of the stranded line 9 according to FIG. 2, the stranded line 10 becomes expediently carried away substantially perpendicular to the line 9. The inventive arrangement causes by the Venturi nozzle device 11, 12th built up dynamic pressure of the flowing liquid, a pressure increase at the inlet 14 of the second circuit 3 and the strand line 10, in which the water flow targeted to a higher level should be set. The venturi device 11, 12 is made either from a streamlined shaped Normventuridüse 11, for example DIN EN ISO 5167-1 with a given diameter (Figure 2) or one as Venturi tube 12 shaped downpipe 7 (Figure 3), in which in the cross-sectional widening the static pressure of the fluid is recovered. With the help of the venturi device 11, 12, the flow velocity and thus the back pressure before as a pitot tube trained strand line 10 increases. In the diffuser 39 of the Venturi nozzle device 11, 12, the high flow rate is reduced again, with the static pressure increases. The increased dynamic pressure at the inlet 14 into the second water / steam cycle 3 is thus only by converting the kinetic energy of the flowing medium in the Down line 7 generated without an additional friction pressure loss by throttling in first water / steam circuit 2 or in the inlet 13 to cause the line 9.

The inventive arrangement thus takes place in the second circuit 3 a Pressure increase instead, without using an additional pump. In the present example The buoyancy of the natural circulation system is thus optimally for the Setting the desired water distribution within the water / steam circuits 2, 3 exploited the steam generator 1. The now in the second cycle 3 increased Amount of water is through the strand line 10 so in the water space 29 of the Steam generator 1 introduced that the conduit 10 centrally with respect to the tube plate 23rd and in the immediate vicinity below the tube plate 23 opens and the water inevitably from below against the entering of the inlet chamber 22 heating medium particularly heated tube plate 23 is passed. By this measure, the as thermally endangered tube plate 23 are cooled safely and steam production in the Steam generator 1 maintained without failures or more frequent maintenance intervals become.

After the outlet of the water from the strand line 10 of the second circuit 3 in the Water chamber 29 through the water chamber inlet 17 and, if necessary, partial evaporation flows the water / vapor mixture together with the water / vapor mixture of the first Circuit 2 through the water chamber outlet 16, 18 via the branch line 9 and Riser 19 in the drum 6. The evaporator device 5 of the second circuit. 3 essentially comprises the water space 29 and the upper tube plate 23.

However, the strand line 10 of the second circuit 3 can also be used according to FIG. 3, i. in axial direction of the downcomer 7 away from the Venturi nozzle device 11, 12 become. In this case, the strand line 9 of the first water / steam cycle 2 in the rule led away perpendicular to the downpipe 7.

In the steam generator acc. Figure 1 thus the two circuits 2, 3 in Water space 29 merged and by means of a common outlet 16, 18 a common outlet line 9/10, 19/20 of the drum 6 supplied. It is, however possible, when not merging the two circuits 2, 3 (that is, the circuits 2, 3 each have separate evaporator devices 4, 5) over the respective circuits separate outlets 16, 18 and strand lines and risers 9, 19 and 10, 20 of the To feed drum 6.

In the case of more than two circulations within a steam generator 1, according to FIG. 4 two or more branches 8, each in the flow direction one behind the other arranged in the downpipe 7 and each with a venturi nozzle device 11, 12 is formed are arranged in the downpipe 7. FIG. 4 shows, in addition to the two circuits 2, 3 a third water / steam circuit 31, which as well as the second circuit 3 a Increased circulation of water experiences. The working medium passes through the inlet opening 37 in the region of the diffuser 39 at the second branch 8 in the third branch line 32 a and is a third evaporator 33 is supplied to subsequently over the Strand line 32 again to the drum 6 to be supplied.

It is also possible, according to the figure 5 instead of a line in the region of Venturi nozzle device 11, 12 a plurality of strand lines 10, 32, 35 for a plurality of circuits 3, 31, 34 to arrange. As a result, in the circuits 3, 31, 34 the Water circulation increased. In this case, the inlet openings 14, 37, 38 of the Strand lines 10, 32, 35 also in the region of the diffuser 39 of the Venturi nozzle means 11, 12 arranged such that the three inlet openings 14, 37, 38 together in the middle of the downpipe to a uniform volume distribution to achieve the individual strands 10, 32, 35. The strand leads 10, 32, 35 lead in each case substantially perpendicularly away from the downpipe 7.

FIG. 7 shows a further variant of a steam generator 1 according to the invention Steam generator acc. Fig. 7 is also a heat recovery steam generator, but not a smoke tube boiler, but a water tube boiler. Of the Steam generator 1 has a substantially vertical throttle cable 40, which in the is formed essentially of water-cooled pipe walls and the Evaporator 4 of the first water / steam cycle 2 of two existing Circuits forms. The working fluid is water from the drum 6 over the Downpipe 7 and through the inlet opening 13 of the strand 9 of the Evaporator 4 is supplied here partially evaporated and subsequently over the strand line 9 fed back to the drum 6.

The working medium of the second circuit 3 is at the junction 8 through the Inlet opening 14 of the strand line 10 and then the evaporator 5, the designed as contact heating surfaces and arranged in the throttle cable 40, fed. After partial evaporation of the water, the working medium passes through the Strand line 10 back into the drum 6. According to the invention, the water circulation in second water / steam circuit 3 through the Venturi nozzle means 11, 12 at the Branch 8 of the downpipe 7 increases. The heating medium or hot exhaust gas passes over the inlet 21 below in the throttle cable 40 of the steam generator 1 and flows through the throttle cable 40 from bottom to top, before it 26 further process steps supplied at the outlet becomes. When flowing through the throttle cable, the heating medium gives heat to the Pipe walls and touch heating surfaces, i. to the evaporator devices 4 and 5 from.

If the device according to the invention in a steam generator 1 with forced circulation used (not shown), then the Venturi nozzle device 11, 12th expediently arranged downstream of the circulation pump, in the downpipe. 7 is arranged. The downpipe 7 is exactly the upstream of the forced circulation Circulation pump a suction line and downstream a pressure line as well as the Riser 19, 20. By the venturi device 11, 12 is the forced circulation as when the natural circulation, the water circulation amount of the second circuit 3 increases.

As Venturidüseneinrichtungen 11, 12, as already mentioned above, venturi 11th or classic Venturi tubes 12, as for example in the flow measurement of Fluids are used with throttle devices according to DIN EN ISO 5167-1, be used. The Venturi nozzle devices 11, 12 point in Flow direction of the fluid or the working fluid water seen a Inlet cone, a cylindrical neck part with inner diameter d (narrowest cross-section), and a diffuser 39, wherein instead of the inlet cone and an inlet rounding according to the venturi nozzle according to DIN EN ISO 5167-1 is possible and the closest Cross-section forming neck part may not be cylindrical. The openings for the Flow measurement in the neck can be omitted inevitably. However, it can be any others, deviating from this standard, a narrowing part and a diffuser part containing Venturi nozzle device are used. To ensure the increased Water circulation in the water / steam circuits 2, 3, 31, 34, in which an increased Circulation amount is desired, the ratio of the inner diameter d of Venturi nozzle device 11, 12 at their narrowest cross-section to the inner diameter D. the downpipe 7 between 1.0 and 0.01.

LIST OF REFERENCE NUMBERS

1

Dampferzeuger

2

Wasser/Dampf-Kreislauf 1

3

Wasser/Dampf-Kreislauf 2

4

Verdampfer-Einrichtung, Kreislauf 1

5

Verdampfer-Einrichtung, Kreislauf 2

6

Wasser/Dampf-Trommel

7

Fallleitung

8

Abzweigung

9

Strangleitung Kreislauf 1

10

Strangleitung Kreislauf 2

11

Venturidüse

12

Venturirohr

13

Eintrittsöffnung der Strangleitung 1

14

Eintrittsöffnung der Strangleitung 2

15

Wasserkammer-Eintritt Kreislauf 1

16

Wasserkammer-Austritt Kreislauf 1

17

Wasserkammer-Eintritt Kreislauf 2

18

Wasserkammer-Austritt Kreislauf 2

19

Steigleitung Kreislauf 1

20

Steigleitung Kreislauf 2

21

Eintritt heißes Abgas bzw. Rauchgas

22

Gaseintrittskammer

23

Wasserkammer - End- bzw. Rohrplatte, Gaseintritt

24

Wasserkammer - End- bzw. Rohrplatte, Gasaustritt

25

Gasaustrittskammer

26

Austritt kaltes Abgas bzw. Rauchgas

27

Mantel

28

Leitung zwischen Trommel und Überhitzer

29

Wasserraum

30

Rauchrohrbündel

31

Wasser/Dampf-Kreislauf 3

32

Strangleitung Kreislauf 3

33

Verdampfer-Einrichtung, Kreislauf 3

34

Wasser/Dampf-Kreislauf 4

35

Strangleitung Kreislauf 4

36

Verdampfer-Einrichtung, Kreislauf 4

37

Eintrittsöffnung der Strangleitung 3

38

Eintrittsöffnung der Strangleitung 4

39

Diffusorförmiger Austritt aus der Venturidüseneinrichtung

40

Gaszug

41

1

steam generator

2

Water / steam cycle 1

3

Water / steam cycle 2

4

Evaporator device, circuit 1

5

Evaporator device, circuit 2

6

Water / steam drum

7

penstock

8th

diversion

9

Catenary Circuit 1

10

Line circuit circulation 2

11

venturi

12

venturi

13

Entry opening of the strand line 1

14

Inlet opening of the strand line 2

15

Water chamber inlet circuit 1

16

Water chamber outlet circuit 1

17

Water chamber entry circuit 2

18

Water chamber outlet circuit 2

19

Riser circuit 1

20

Riser circuit 2

21

Admission hot exhaust gas or flue gas

22

Gas inlet chamber

23

Water chamber - end or tube plate, gas inlet

24

Water chamber - end or tube plate, gas outlet

25

Gas outlet chamber

26

Outlet cold exhaust gas or flue gas

27

coat

28

Cable between drum and superheater

29

water space

30

Smoke tube bundles

31

Water / steam circuit 3

32

Catenary circuit 3

33

Evaporator device, circuit 3

34

Water / steam cycle 4

35

Line circuit circulation 4

36

Evaporator device, circuit 4

37

Entry opening of the strand line 3

38

Inlet opening of the strand line 4

39

Diffuser-shaped outlet from the venturi device

40

throttle cable

41

Claims (6)

1. Steam generator (1) in particular for heating by means of hot exhaust gases, having two or more water/steam circuits (2, 3, 31, 34), in which each water/steam circuit (2, 3, 31, 34) has at least one evaporator (4, 5, 33, 36) to receive the heat from the heating medium, and the water/steam circuits (2, 3, 31, 34) have at least one water/steam drum (6) and one downcomer pipe (7) in common,
   having at least one branch (8) in the downcomer pipe (7), from which the pipe sections (9, 10, 32, 35) of the respective water/steam circuits (2, 3, 31, 34) branch off, characterized in that
   the downcomer pipe (7) is embodied with a venturi device (11, 12) in the area of the branch (8),
   and that the inlet opening (14, 37, 38) of the pipe section (10, 32, 35) of at least one water/steam circuit (3, 31, 34) is disposed in the area of diffuser-shaped outlet (39) of the venturi device (11, 12), and the pipe section (10, 32, 35) is embodied as a dynamic pressure pipe in order to increase the pressure of the working medium in this circuit (3, 31, 34).
2. The steam generator of claim 1, wherein the venturi device comprises a venturi nozzle (11) inserted in the downcomer pipe (7).
3. The steam generator of claim 1, wherein the venturi device comprises a downcomer pipe (7) embodied as a venturi pipe (12),
4. The steam generator of one of claims 1 to 3, wherein the steam generator (1) can be operated in natural circulation mode.
5. The steam generator of one of claims 1 to 3, wherein the steam generator (1) can be operated in forced circulation mode.
6. The steam generator of one of claim 1 to 5, wherein the ratio of the inside diameter d of the venturi device (11, 12) at its narrowest crossed section to the inside diameter D of the downcomer pipe (7) lies between 1.0 and 0.01.

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