EP2620600A1 - Verfahren zum Betreiben einer Dampfkraftanlage - Google Patents

Verfahren zum Betreiben einer Dampfkraftanlage Download PDF

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Publication number
EP2620600A1
EP2620600A1 EP12152436.7A EP12152436A EP2620600A1 EP 2620600 A1 EP2620600 A1 EP 2620600A1 EP 12152436 A EP12152436 A EP 12152436A EP 2620600 A1 EP2620600 A1 EP 2620600A1
Authority
EP
European Patent Office
Prior art keywords
steam
turbine
sealing
power plant
shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP12152436.7A
Other languages
German (de)
English (en)
French (fr)
Inventor
Tobias Hogen
Bernd Leu
Norbert Pieper
Michael Wechsung
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Priority to EP12152436.7A priority Critical patent/EP2620600A1/de
Publication of EP2620600A1 publication Critical patent/EP2620600A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/02—Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type
    • F01D11/04—Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type using sealing fluid, e.g. steam
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/08—Cooling; Heating; Heat-insulation
    • F01D25/12—Cooling

Definitions

  • the invention relates to a method for operating a steam power plant with a steam turbine, in which a seal area is applied to a shaft of the steam turbine with sealing steam to avoid air ingress, wherein the sealing steam is taken as tapping steam in the steam power plant. It also relates to a steam turbine.
  • the thermal energy of steam in a steam turbine is used to generate electricity.
  • the steam required to operate the steam turbine is generated in a steam boiler from previously purified and treated water. By further heating the steam in the superheater, the temperature and the specific volume of the steam increase. From the steam boiler, the steam flows via pipelines into the steam turbine, where it delivers part of its previously absorbed energy as kinetic energy to the turbine.
  • a generator is coupled, which converts the mechanical power into electrical power. Thereafter, the expanded and cooled vapor flows into the condenser where it condenses by heat transfer to the environment and collects as liquid water at the lowest point of the condenser.
  • condensate pumps and preheaters through the water is temporarily stored in a feedwater tank and then fed via the feed pump to the boiler again.
  • Steam boilers are usually fired with conventional fuels such as oil, natural gas, hard coal or lignite. There are also power plants whose main task is waste incineration. In addition, the steam boilers of large power plants also become thermal Disposal of liquid, combustible or non-combustible, wastes such as oil-water mixtures used.
  • the first turbine part on the steam side is called a high-pressure turbine, which after the intermediate superheat the following turbine as a medium-pressure turbine and the adjoining turbines as low-pressure turbines. If all the sub-turbines are arranged on one branch, usually between one and three low-pressure turbines are used, depending on the plant output and cooling water temperatures.
  • the low-pressure turbines are often sealed in the shaft by means of sealing steam.
  • the continuous flow of the sealing steam prevents a collapse of ambient air in the shaft sealing regions of the respective turbine.
  • the required for the evaporation of the low-pressure turbine sealing steam is usually removed during load operation from the shaft sealing areas of the high and medium pressure turbine.
  • the sealing steam is removed from the circuit at a suitable position (usually before reheating) and for starting operations, sealing steam is supplied from an external source (eg auxiliary boiler).
  • the axial fixation of the shaft is typically done in a thrust bearing.
  • different partial displacements occur between the rotor and the inner housing of the respective sub-turbine, in particular in the axial direction, in the case of several sub-turbines.
  • the shifts are getting bigger, the farther the individual turbine part is removed from the thrust bearing.
  • the absolute displacement of the shaft in operation can have values up to about 80 mm.
  • the described shaft displacement acts to limit the efficiency.
  • the displacement which means a relative displacement of the housing and shaft of the respective turbine to compensate by appropriate radial clearance between the conical final stage blades and inner casing of the turbine parts.
  • the resulting radial gaps allow passage of vapor without release of thermal energy, so that the efficiency decreases with increasing gap size.
  • the degree of relative displacement between shaft and housing also determines the required distance between the guide and blade rings. This can lead to fewer steps being able to be accommodated for the blading given the axial space available for the blading. Since in this case the enthalpy gradient is increased per stage, this also has a negative impact on the expansion efficiency.
  • the permissible absolute displacement of the shaft is determined by the specifications of the generator, which is typically furthest from the axial bearing on the shaft. It is individually different. Since the displacement increases as described above, the farther the generator is away from the thrust bearing, the maximum permissible absolute displacement of the shaft in the generator limits the maximum distance of the generator from the thrust bearing and thus the available axial space. However, this limits the number of possible sub-turbines and pressure stages between thrust bearing and generator and thus the efficiency of the steam power plant, unless it an alternative arrangement would be provided, but would result in a more complex system planning.
  • the invention is therefore based on the object to provide a method for operating a steam power plant and a steam turbine, which allow a particularly high efficiency with relatively little expensive technical means.
  • This object is achieved according to the invention by cooling the sealing vapor between removal and application of the sealing area.
  • the invention is based on the consideration that a particularly high efficiency would be achievable with a reduction of the radial gaps, for which purpose the displacement of the shaft during operation should be minimized.
  • the radial displacement of the shaft is caused by the axial expansion during operation, which in turn is caused by high thermal load.
  • the thermal load should be reduced. This can be achieved, in particular, in the shaft seal areas, which are sealed with hot barrier vapor.
  • a reduction of the thermal load can be achieved here by reducing the temperature of the sealing steam. This can be achieved by cooling the sealing vapor between removal and pressurization of the sealing area.
  • a multiple reheat is carried out in a steam cycle of the steam power plant, d. H.
  • a first intermediate superheating is carried out in the steam boiler, the steam is introduced into a first medium-pressure turbine where it is decompressed and then overheated a second time in the steam boiler. Thereafter, it is introduced into a second medium-pressure turbine. If necessary, this process can be continued.
  • a steam power plant is advantageously operated with the described method.
  • the steam turbine is designed as a low-pressure turbine.
  • a shaft seal by means of sealing steam is often required, since here is due to the low pressures to prevent air ingress.
  • the described cooling offers special advantages.
  • a steam power plant comprises in an advantageous embodiment of such a steam turbine.
  • the steam power plant in this case comprises a steam cycle, which is designed for multiple reheating.
  • the cooling described here also offers particular advantages.
  • the housing of the steam turbine is connected to a further housing of another steam turbine via a push rod.
  • the displacement of the housing can be reduced, for. B. by connecting the medium-pressure outer housing with the low pressure inner housing. The efficiency-relevant relative displacement of shaft and housing is thereby further reduced.
  • the advantages achieved by the invention are in particular that a smaller thermal load of the shaft is achieved by the cooling of the sealing steam and the relative displacements between the shaft and housing and the absolute displacement of the rotor is reduced in particular at the low-pressure turbines.
  • This makes it possible to remain in the allowable for the generator range of absolute shaft displacement even in systems with multiple reheater and to avoid additional thermodynamic losses due to higher distances between blades and blades and larger radial clearance over the tapered conical freestanding power amplifiers. It can also be avoided under certain circumstances that the usual arrangement of the individual turbine sections must be changed.
  • FIG. 1 shows schematically a part of a steam power plant with a shaft together with a graphical representation of the shaft displacement.
  • FIG shows in the upper part schematically a fragmentary view of a steam turbine 1.
  • This has a high-pressure turbine 2, a medium-pressure turbine 4 and three low-pressure turbines 6.
  • the medium and low-pressure turbines 4, 6 are configured in each case double-flow.
  • the turbines 2, 4, 6 are arranged in the order mentioned from left to right on a common shaft 8, ie the rotor.
  • the shaft 8 is movably mounted between high-pressure turbine 2 and medium-pressure turbine 4 in a thrust bearing 10. At the high-pressure turbine 2 end facing away from the shaft 8, a generator 12 is arranged.
  • the turbines 2, 4, 6 each have an inner housing 14 and an outer housing 16. The feeding of the turbines with steam and the entire steam cycle with steam boiler and condenser are not shown.
  • the low-pressure turbines 6 each have a sealing vapor introduction device 18 in a sealing region on the outlet side of the vapor. This prevents air ingress.
  • the sealing steam is taken from the steam inlet and outlet side of the high-pressure turbine 2 and steam outlet side of the medium-pressure turbine 4 at a plurality of steam extraction devices 20 and supplied via a sealing steam line 22 to the sealing steam introduction means 18.
  • a cooling device 24 is arranged in the sealing steam line 22 between the sealing steam introduction device 18 and the steam extraction device 20.
  • the inner housing 16 of the low-pressure turbines 6 are connected to each other and to the outer housing 16 of the medium-pressure turbine 4 via push rods 26.
  • a further medium-pressure turbine is arranged on the shaft 8 in addition to the medium-pressure turbine 6, wherein the steam line system is designed for a double reheat.
  • the steam is taken from the high-pressure turbine 2, superheated and fed to the medium-pressure turbine 4.
  • the medium-pressure turbine 4 In the illustration of FIG it is then supplied to the low-pressure turbines 6.
  • he is again superheated and fed to the other medium-pressure turbine and then passed into the low-pressure turbines 6.
  • the displacement of the shaft 8 during operation and the displacement of the inner housing 14 and thus also the relative displacement of shaft 8 and inner housing 14 to each other are shown graphically in the lower part of FIG.
  • the abscissa indicates the axial location on the shaft 8 and is therefore shown in the same length for the representation of the steam power plant 1 in FIG with.
  • the ordinate indicates the displacement.
  • Curve 28 indicates the absolute displacement of the inner casings 16, curve 30 the absolute displacement of the shaft 8 without cooler 24 and curve 32 the absolute displacement of the shaft 8 with cooler 24.
  • the difference 34 of curve 30 and 28 thus shows the relative displacement of the shaft 8 and inner housing 16 without cooling device 24, the difference 36 of curve 32 and 28, the relative displacement of shaft 8 and inner housing 16 with cooling device 24th
  • the origin of the coordinate system is placed in the area of the axial bearing 10.
  • the displacement is zero, the curves 28, 30, 32 intersect the abscissa.
  • the curve 32 is always below the curve 30, d. H. with cooling of the sealing steam, the displacement of the shaft 8 is lower.
  • the relative displacement is also lower, so that a lower radial clearance is necessary and the efficiency of the steam power plant 1 can be increased. In the embodiment not shown, this allows a greater distance between generator 12 and thrust bearing 10, so that the insertion of a further medium-pressure turbine on the shaft 8 is possible in the first place.
EP12152436.7A 2012-01-25 2012-01-25 Verfahren zum Betreiben einer Dampfkraftanlage Withdrawn EP2620600A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP12152436.7A EP2620600A1 (de) 2012-01-25 2012-01-25 Verfahren zum Betreiben einer Dampfkraftanlage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP12152436.7A EP2620600A1 (de) 2012-01-25 2012-01-25 Verfahren zum Betreiben einer Dampfkraftanlage

Publications (1)

Publication Number Publication Date
EP2620600A1 true EP2620600A1 (de) 2013-07-31

Family

ID=45509367

Family Applications (1)

Application Number Title Priority Date Filing Date
EP12152436.7A Withdrawn EP2620600A1 (de) 2012-01-25 2012-01-25 Verfahren zum Betreiben einer Dampfkraftanlage

Country Status (1)

Country Link
EP (1) EP2620600A1 (un)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH242222A (de) * 1944-03-28 1946-04-30 Escher Wyss Maschf Ag Dampf- oder Gasturbine für hohe Arbeitsmitteltemperaturen.
CH449054A (de) * 1966-06-30 1967-12-31 Escher Wyss Ag Verfahren zum thermischen Schutz von Labyrinthdichtungen an Dampfturbinen und Anlage zur Ausführung des Verfahrens
GB1108265A (en) * 1963-12-13 1968-04-03 Ass Elect Ind Improvements relating to steam turbines
DE2934340A1 (de) * 1978-08-25 1980-03-20 Hitachi Ltd Verfahren zum abschalten und wiederanfahren eines kombinierten heizkraftwerks
EP1048823A2 (de) * 1999-04-29 2000-11-02 ABB Alstom Power (Schweiz) AG Sperrdampfeinspeisung
DE102008045655A1 (de) * 2008-09-03 2010-04-15 Siemens Aktiengesellschaft Dampfturbinensystem mit einer Kondensationsdampfturbine mit einer energieeffizienten Sperrdampfversorgung

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH242222A (de) * 1944-03-28 1946-04-30 Escher Wyss Maschf Ag Dampf- oder Gasturbine für hohe Arbeitsmitteltemperaturen.
GB1108265A (en) * 1963-12-13 1968-04-03 Ass Elect Ind Improvements relating to steam turbines
CH449054A (de) * 1966-06-30 1967-12-31 Escher Wyss Ag Verfahren zum thermischen Schutz von Labyrinthdichtungen an Dampfturbinen und Anlage zur Ausführung des Verfahrens
DE2934340A1 (de) * 1978-08-25 1980-03-20 Hitachi Ltd Verfahren zum abschalten und wiederanfahren eines kombinierten heizkraftwerks
EP1048823A2 (de) * 1999-04-29 2000-11-02 ABB Alstom Power (Schweiz) AG Sperrdampfeinspeisung
DE102008045655A1 (de) * 2008-09-03 2010-04-15 Siemens Aktiengesellschaft Dampfturbinensystem mit einer Kondensationsdampfturbine mit einer energieeffizienten Sperrdampfversorgung

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