US3525575A - Turbine - Google Patents

Turbine Download PDF

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Publication number
US3525575A
US3525575A US729789A US3525575DA US3525575A US 3525575 A US3525575 A US 3525575A US 729789 A US729789 A US 729789A US 3525575D A US3525575D A US 3525575DA US 3525575 A US3525575 A US 3525575A
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United States
Prior art keywords
turbine
steam
rotor
thermal stresses
casing
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.)
Expired - Lifetime
Application number
US729789A
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English (en)
Inventor
Karl Steinack
Robert Ehrich
Walter Zorner
Jurgen Freyer
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Licentia Patent Verwaltungs GmbH
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Licentia Patent Verwaltungs GmbH
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    • 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
    • F01D11/001—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between stator blade and rotor
    • 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
    • F01D1/00—Non-positive-displacement machines or engines, e.g. steam turbines
    • F01D1/02—Non-positive-displacement machines or engines, e.g. steam turbines with stationary working-fluid guiding means and bladed or like rotor, e.g. multi-bladed impulse steam turbines
    • F01D1/04—Non-positive-displacement machines or engines, e.g. steam turbines with stationary working-fluid guiding means and bladed or like rotor, e.g. multi-bladed impulse steam turbines traversed by the working-fluid substantially axially
    • 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
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/02—Blade-carrying members, e.g. rotors
    • F01D5/06—Rotors for more than one axial stage, e.g. of drum or multiple disc type; Details thereof, e.g. shafts, shaft connections

Definitions

  • the present invention relates to an axial-flow turbine and, more particularly, to a steam turbine which can be quick-started for use as an auxiliary to meet the need for additional power during peak loads.
  • Thermal stresses are developed in the structural components of a steam turbine as a result of sudden changes in the temperature of the Working medium, which results from the working medium coming into contact with the structural components. Moreover, the structural components themselves develop temperature gradients between the portion of the component which came into direct contact with the working medium, and portions of the component which are relatively distant from the working medium. Thus, thermal stresses that occur are directly related to the thickness of the walls of the turbine components. The thicker the Walls are, the greater will be the gradient in temperature within the component. From this it follows that thermal stresses are relatively small when the walls of the components are not very thick and when such walls are heated on both sides. In contrast, the thermal stresses are relatively high when the walls are thick and are heated only on one side. For example, thermal stresses occur when a thick-walled turbine casing is suddenly heated in its interior by a working medium such as steam. Under such conditions, extremely high thermal stresses are developed in the turbine casing.
  • thermal stresses must be taken into consideration when designing steam turbines.
  • a particularly critical operational time for steam turbines is dur- 3,525,575 Patented Aug. 25, 1970 ing starting and stopping, especially, from a relatively cold state.
  • thermal stresses which are created in the structural components must not exceed certain critical values.
  • Certain structural components, for example, the casing and rotor, are more critical than others and in designing the steam turbine particular attention must be paid to providing that these components are capable of sustaining the thermal stresses that occur.
  • the parts of the rotor which are located in the early stages of a turbine are subjected to relatively greater thermal stresses, since temperatures in the rotor core lag considerably behind temperatures nearer the rotor periphery.
  • An examination of cracking due to thermal stresses in steam turbine rotors has led to the discovery that those parts of the rotor which have grooves or recesses are particularly susceptible to thermal cracking.
  • Such grooves are provided, for instance, in external seal mountings, in interstage seals and mountings therefor, as well as, mounting grooves for rotor blades or buckets provided on the rotor discs.
  • the rotors of steam turbines are particularly susceptible to thermal cracking, especially auxiliary turbines used during peak loads. Such steam turbines are started and stopped quite frequently and experience great variations in stress.
  • the present invention accomplishes this object by locating interstage seals, i.e., seals provided between consecutive turbine stages, radially away from the rotor shaft.
  • a sealing means is provided having an inwardly directed circumferential surface which is spaced from the rotor shaft.
  • the rotor shaft has rotor discs located in the turbine stages.
  • a circumferential surface is provided on an annular shoulder means carried by and arranged alongside of at least one of the rotor discs on the rotor shaft and axially aligned with the circumferential surface of the sealing means.
  • the circumferential surfaces of the sealing means and annular shoulder coact with each other to seal the space between consecutive turbine stages, radially away from the rotor the rotor shaft with grooves for a sealing surface which will correspond to the sealing ring of the stator assembly. Thermal stresses which would concentrate at such grooves in the rotor shaft and would affect the operation of the turbine are thereby avoided.
  • the fact that the temperature of the working medium is different along different axial regions of the turbine is taken advantage of to reduce thermal stresses in the rotor shaft.
  • the rotor shaft is constructed as a hollow member, having a wall thickness which is thinner in hotter regions of the turbine than in cooler regions thereof.
  • the single figure is a partial sectional view of a steam turbine engine arrangement, according to the present invention.
  • the steam then fiows along the inner surface of the steam-tight inner casing member 4 and is divided into two streams of relatively equal size which are oppositely directed with respect to each other.
  • the inner casing member 4 in addition to being steam-tight, is expandable when heated with reference to the inner casing member 3 which is provided radially outwardly therefrom.
  • the inner casing member 4 is provided the capability of expanding when heated by means of a piston ring bushing 6 provided in the casing member 4 mounting means, which is connected to casing member 3.
  • the turbine early stage or inlet stator vanes have support members 10 which extend from casing members 2, 3 and 4, respectively.
  • the support members 1() ⁇ are provided sealing means in the form of a ring 11 on their radially inner peripheries.
  • the sealing means 11 includes an inwardly directed circumferential surface which is spaced from shaft 1 and is arranged between two consecutive turbine stages.
  • annular shoulder means 12 are carried by and arranged axially alongside of rotor discs 13.
  • the annular shoulder means 12 have outer circumferential surfaces which are in axial alignment with the circumferential surface of the sealing means 11.
  • the rotor shaft 1 is constructed as a hollow member having a wall thickness which varies from a relatively lesser thickness in hotter regions to a relatively greater thickness in cooler regions of the turbine.
  • the interstage seal arrangement provided by the present invention makes it possible to have a rotor shaft with a continuous, uninterrupted, smooth surface which is free of grooves and which is therefore much less susceptible to thermal stresses and their detrimental effects.
  • the labyrinths, characteristic of interstage seals of steam turbines are thus removed from the rotor shaft surface and, instead, are provided remote from the rotor shaft 1, on the shoulders 12 of discs 13 where detrimental thermal stresses do not develop.
  • This arrangement virtually eliminates the limitations placed on the starting time required for steam turbines, by forces exerted on the rotor shaft as a result of unduly high thermal stresses.
  • the susceptibility of the rotor shaft to cracking, as a result of being continuously subjected to thermal stresses during operation is reduced. Hence, greater variations in load conditions are made possible without cracking developing in the rotor during starting and stopping operations.
  • the thermal stresses that result from starting and stopping operations are kept at relatively equal magnitudes in all temperature regions of the turbine. It is possible to construct the rotor shaft of varying thickness due to relatively smaller centrifugal forces being realized in the vicinity of the early turbine stages than in later stages thereof. This is due to relatively shorter rotor blade lengths at the hotter early stages than in the cooler later stages of the turbine. If the rotor shaft were constructed to have a constant thickness or cross section, during starting and stopping operations, the greatest thermal stresses would occur in the steam inlet or early stage end of the turbine. In starting and stopping operations, steam temperatures do not change quite as much in the later turbine stages, as they do in the early turbine stages. Therefore, thermal stresses that occur in the later stages are considerably smaller than those occurring in the early stages of the turbine.
  • a quick-starting, axial-flow multiple-stage turbine comprising, in combination:
  • sealing means arranged between two consecutive stages and fastened to the radially inward circumference of said support member, said sealing means having an inwardly directed circumferential surface which is spaced from the outer circumferential surface of said shaft; and Y (e) annular shoulder means carried by and arranged axially alongside of at least one of said discs and having an outer circumferential surface which is in axial alignment with said circumferential surface of said sealing means, said circumferential surfaces of said sealing means and of said shoulder means coacting with each other for sealing the space between the two consecutive stages.
  • 2,786,625 2,823,891 References Cited 3,018,085 UNITED STATES PATENTS 5 gg-ggg 2,367,134 1/1945 Mierley. 2,649,315 8/1953 Ipsen.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
US729789A 1967-05-16 1968-05-16 Turbine Expired - Lifetime US3525575A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEL0056509 1967-05-16

Publications (1)

Publication Number Publication Date
US3525575A true US3525575A (en) 1970-08-25

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US729789A Expired - Lifetime US3525575A (en) 1967-05-16 1968-05-16 Turbine

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US (1) US3525575A (cs)
BE (1) BE714459A (cs)
CH (1) CH461537A (cs)
DE (1) DE1551193A1 (cs)
FR (1) FR1565824A (cs)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849023A (en) * 1973-06-28 1974-11-19 Gen Electric Stator assembly
US20080050222A1 (en) * 2006-08-23 2008-02-28 General Electric Company Singlet welded nozzle hybrid design for a turbine
US20080078477A1 (en) * 2006-09-29 2008-04-03 General Electric Company Varying fluence as a function of thickness during laser shock peening
US11585277B2 (en) * 2020-09-17 2023-02-21 Raytheon Technologies Corporation Stiffened rotor shaft for a gas turbine engine

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2367134A (en) * 1943-05-29 1945-01-09 Westinghouse Electric & Mfg Co Steam chest construction
US2649315A (en) * 1951-03-10 1953-08-18 Gen Electric High-temperature expansion joint
US2762559A (en) * 1954-09-23 1956-09-11 Westinghouse Electric Corp Axial flow compressor with axially adjustable rotor
US2786625A (en) * 1950-08-01 1957-03-26 Rolls Royce Turbo-machines
US2823891A (en) * 1953-05-20 1958-02-18 Westinghouse Electric Corp Steam turbine
US3018085A (en) * 1957-03-25 1962-01-23 Gen Motors Corp Floating labyrinth seal
US3047268A (en) * 1960-03-14 1962-07-31 Stanley L Leavitt Blade retention device
US3303997A (en) * 1965-04-21 1967-02-14 United Aircraft Corp Compressor air seal

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2367134A (en) * 1943-05-29 1945-01-09 Westinghouse Electric & Mfg Co Steam chest construction
US2786625A (en) * 1950-08-01 1957-03-26 Rolls Royce Turbo-machines
US2649315A (en) * 1951-03-10 1953-08-18 Gen Electric High-temperature expansion joint
US2823891A (en) * 1953-05-20 1958-02-18 Westinghouse Electric Corp Steam turbine
US2762559A (en) * 1954-09-23 1956-09-11 Westinghouse Electric Corp Axial flow compressor with axially adjustable rotor
US3018085A (en) * 1957-03-25 1962-01-23 Gen Motors Corp Floating labyrinth seal
US3047268A (en) * 1960-03-14 1962-07-31 Stanley L Leavitt Blade retention device
US3303997A (en) * 1965-04-21 1967-02-14 United Aircraft Corp Compressor air seal

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849023A (en) * 1973-06-28 1974-11-19 Gen Electric Stator assembly
US20080050222A1 (en) * 2006-08-23 2008-02-28 General Electric Company Singlet welded nozzle hybrid design for a turbine
US20080078477A1 (en) * 2006-09-29 2008-04-03 General Electric Company Varying fluence as a function of thickness during laser shock peening
US7736450B2 (en) * 2006-09-29 2010-06-15 General Electric Company Varying fluence as a function of thickness during laser shock peening
US20100226780A1 (en) * 2006-09-29 2010-09-09 Mark Samuel Bailey Varying fluence as a function of thickness during laser shock peening
US7942641B2 (en) 2006-09-29 2011-05-17 General Electric Company Varying fluence as a function of thickness during laser shock peening
US11585277B2 (en) * 2020-09-17 2023-02-21 Raytheon Technologies Corporation Stiffened rotor shaft for a gas turbine engine

Also Published As

Publication number Publication date
FR1565824A (cs) 1969-05-02
CH461537A (de) 1968-08-31
BE714459A (cs) 1968-09-16
DE1551193A1 (de) 1970-03-12

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