WO2012175328A1

WO2012175328A1 - Steam-turbine system, comprising a steam turbine and a rotational device for the rotational drive of a turbine rotor shaft during the turbine start-up

Info

Publication number: WO2012175328A1
Application number: PCT/EP2012/060565
Authority: WO
Inventors: Frank EIDNER; Ingo GLEISNER; Max HEINRICH; Marco HERKERT; Gustl SCHREIBER
Original assignee: Siemens Aktiengesellschaft
Priority date: 2011-06-20
Filing date: 2012-06-05
Publication date: 2012-12-27

Abstract

The invention relates to a steam-turbine system, comprising a steam turbine (10), with a turbine rotor shaft (12), and an actuable rotational device (16) for the rotational drive of the turbine rotor shaft (12) during an operational start-up of the steam turbine (10). According to the invention, the rotational device (16) is an electric motor, in which the rotor (52) of the electric motor is formed by a shaft section (56) of the turbine rotor shaft (12) and the stator (58) of the electric motor surrounds the rotor (52) on the outer circumference of the latter. This provides a structurally simple, low-wear and reliable option for the rotational drive of the turbine rotor shaft (12) during the turbine start-up.

Description

description

Steam turbine plant, comprising a steam turbine and a rotating device for the rotary drive of a turbine rotor shaft at turbine start

The present invention relates to a steam turbine plant, comprising a steam turbine with a turbine rotor shaft and a controllable rotating device for rotationally driving the turbine rotor shaft at an operating start and / or Betriebsen ^¬ de the steam turbine.

Such steam turbine plants are known from the prior art. The steam turbine is used here for converting energy supplied steam ("live steam") into mechanical

Rotary power of a turbine rotor. The turbine runner is rotatably accommodated for this purpose in a turbine housing through which steam flows and is generally equipped with a large number of rotor blade rings which, in combination with stationary stationary blade rings arranged in mesh therewith, effect the energy conversion. Flow through the turbine housing reduces the pressure and temperature of the steam. The expanded steam is discharged at the end of the flow ^¬ path as "boil-off" and recycled usually by means of a capacitor, at least a condensate pump and egg nens steam heater, and (in a CLOSED ^¬ Senen steam-water circuit) again as fresh steam of the steam turbines ^¬ ne fed. The steam turbine can z. B. in a power plant or an industrial plant for driving an electric Genera ^¬ sector or other rotating-driven work machine (eg., Compressor) may be provided. The term "turbine rotor shaft" as used herein refers to the entirety of turbine runners (within the steam- ^flow turbine housing) and the non-rotatably or drehgekop ^¬ pelt associated with other system components (outside the steam-flow turbine housing). In other words, the turbine rotor ("rotor of the turbine") forms only an axial section of the overall longer turbine rotor shaft, wherein further shaft sections are present outside of the steam-flow turbine housing. The latter Wel ^¬ lenabschnitte are required to supply the rotational power of the turbine rotor a respective use, for example, to drive a pump, a compressor or an electric generator. The latter shaft sections can, for. Example, be integrally connected to the located within the steam-flow turbine housing shaft portion, or be connected by one or more non-rotatable connections (eg., Screwed flange). If a work ^machine to be driven by the steam turbine (eg electrical generator) is not to be operated directly with the rotational speed of the turbine ^runner , then a suitable speed-changing transmission is to be arranged in the drive train formed by the turbine runner shaft. In this case, z. B. a running from the output of the transmission to the working machine to ^¬ drive shaft a rotationally coupled to the turbine rotor Anla ^¬ genkomponente and thus a portion of the "turbine rotor shaft" in the context of the invention.

In the rotary drive train from the steam turbine to the relevant machine can further z. B. a clutch can be seen ^¬ to temporarily interrupt the transmission of rotational power from the turbine rotor to the machine can.

During operation of steam turbine plants of the type of interest here, the turbine rotor rotates at a speed of typically a few thousand rpm. In so-called "gearless machines" corresponds to the speed of the turbine rotor to be supplied by the electric generator power frequency, ie z. 3,000 rpm (for a mains frequency of 50 Hz) or 3,600 rpm (for 60 Hz). In contrast, so-called gear machines regardless of this frequency to be generated be operated electric current. These machines typically have higher speeds, for example in the range of about 4,500 to 7,000 rpm. After a business interruption, z. As for maintenance purposes, it is problematic in the known systems to accomplish a "rapid start of operation" of the steam turbine, ie, starting the turbine runner from standstill (speed = 0) to a desired (rated) speed.

Although this problem is defused by the provided in the generic steam turbine plant controllable "Dreheinrich ^¬ tion", by means of which at a start of operation of the turbine, a torque can be exerted on the turbine rotor shaft. The known embodiments of such

Rotary device disadvantageously, however, often lead to an unfavorable force introduction into the turbine rotor shaft and / or to a complication of the system design. The turning device can except or at an operating start of the steam turbine alternatively or additionally at a

End of operation, ie useful in the "shutdown" of the steam turbine ^¬ used. By using the rotating means for rotating the turbine rotor shaft during shutdown of the steam turbine, a slower Drehzahlverrin ^¬ delay and thus a more uniform cooling of the turbine ^¬ rotor (rotor of the turbine) is ensured advantageous. The turbine rotor can here z. B. be further rotated for some time even after completion of the steam supply to the turbine to order so z. B. to avoid curling of the turbine rotor. If the turbine runner is driven directly to a standstill, there is a risk that it will bend when cooled. A speedy restart would be impossible. So far there are z. B. turning means, which are coupled as needed, ie at the turbine start or when driving off the turbine mecha ^¬ nically with the turbine rotor or the turbine rotor shaft. For example, there are Schwenkritzelanordnun- gene, in which an electric motor driven pinion is brought into engagement with a ring gear on the circumference of the turbine rotor shaft. Another known possibility is to provide a turbine runner with a so-called Pelton wheel and to drive this Pelton wheel when necessary with a jet of (high-pressure) oil.

It is an object of the present invention to avoid the problems in connection with the known rotating devices in a steam turbine plant of the type mentioned and to provide a structurally simple and reliable Mög ^¬ probability for rotational driving of the turbine rotor shaft at a start of operation and / or end of operation. According to the invention, the rotating means is an electric motor whose rotor is formed by a shaft portion of the Turbinenläuferwel ^¬ le, wherein the stator of the electric motor surrounds the rotor at its outer periphery. According to a preferred use of the rotating device, this is activated both at the start of operation and at the end of operation of the turbine.

The invention can be realized structurally simple and has a high reliability. Apart from the already rotating turbine rotor shaft, advantageously no further moving components are required for the realization of the rotating device. In addition, a wear is advantageously avoided, as it may arise in known mechanically coupled rotating devices. Also, the solution of the invention does not require the use of significant amounts of oil as in the known rotating device based on an oil-driven Pelton wheel.

In one embodiment, the steam turbine plant comprises egg ^¬ nen from the steam turbine via the turbine rotor shaft drehan- driven electrical generator for generating electrical energy. Alternatively or additionally, the steam turbine plant may comprise another type of work machine which is driven via the turbine rotor shaft. For the concrete arrangement instead of an electric motor out ^¬ formed rotator there are many ways. In a preferred embodiment it is provided that the rotor of the electric motor forming shaft portion of the turbine rotor shaft outside of a steam flowing through Turbi ^¬ nengehäuses the steam turbine is provided. For example, this shaft portion between the steam turbine and ei ^¬ ner thereof rotationally driven via the turbine rotor shaft the driven machine (z. B. electric generator) may be provided.

The function of each electric motor based on the ^¬ together menwirkung of magnetic fields that are generated on the one hand of "rotor magnet" and the other part of "stator". The terms "rotor magnet" and "stator magnet" are very broad meaning here, so including only "Perma ^¬ nentmagnete" fall by no means, but in particular magnetic coils or a plurality of magnetic coils formed magnetic coils, is irrelevant whether the of such turns or Coils generated magnetic field is caused by active current or by an induced current.

In a preferred embodiment, rotor magnets of the electric motor are designed as permanent magnets or as short-circuited magnetic coils or magnetic coils. This advantageously eliminates the need for a supply of electric current to the respective shaft section of the turbine rotor shaft, or a "commutator". In contrast, the stator magnets of the electric motor before Trains t ^¬ as magnetic coils to generate a rotating magnetic field formed, in the simplest case is considered as an exaggerated drehstrombe- arrangement of three in the circumferential direction by 120 ° to each other arranged magnet coils.

The electric motor can thus be designed in particular as a so-called asynchronous motor with squirrel cage. The invention will be further described below with reference to two embodiments ^¬ examples with reference to the accompanying drawings. They show:

Fig. 1 is a schematic longitudinal sectional view of a

Steam turbine plant according to a Ausführungsbei ^¬ game, and

Fig. 2 shows a detail (rotating device) of Fig. 1, but according to a modified embodiment.

Fig. 1 shows a steam turbine plant, comprising a steam turbine ^¬ 10, which is coupled via a turbine rotor shaft 12 with a rotary driven work machine 14. The

Steam turbine plant further comprises a controllable Drehein ^¬ direction 16 for rotational driving of the turbine rotor shaft 12 at a start of operation or an end of operation ("shutdown") of the steam turbine. The turbine 10 includes a turbine housing 18 having a turbine runner 20 rotatably mounted therein about an axial axis A. Rotor blades 22 are secured to the circumference of the turbine runner 20 and cooperate with stationary vanes 24 mounted in the turbine housing 18 in operation of the turbine 10; in order to convert energy from supplied steam into mechanical rotational energy of the turbine rotor shaft 12 during a steam flow. The arrows ^¬ is recorded in Fig. 1 illustrate this steam flow from a steam inlet 26 to an exhaust vapor outlet 28th

The pivot bearing of the turbine rotor shaft 12 is accomplished in Darge ^¬ presented embodiment by means of a thrust bearing 30, a first radial bearing 32 and a second radial bearing 34. Furthermore, one recognizes in Fig. 1, a first bearing housing 36, a second bearing housing 38 and

Sealing rings 40, 42, 44 and 46. The turbine rotor shaft 12 extends in the axial direction over the entire area of the steam turbine installation shown in FIG. 1, ie, starting from the area of the first bearing housing 36 over the area of the steam-flow turbine housing 18 and the area of the second bearing housing 38 into the area of the work machine 14, the here z. B. is designed as an electrical generator for generating electrical energy. From the working machine 14 of the

Steam turbine plant is in the figure for the sake of simplicity, only the turbine 10 facing end wall of a Ar ^¬ beitsmaschinengehäuses 48 (eg generator housing) Darge ^¬ represents.

The turbine runner 20 thus forms a part of the turbine rotor shaft 12, namely the shaft portion of the Turbi ^¬ nenläuferwelle 12 located in axial direction in the region of the turbine housing 18th

Especially in larger steam turbine plants, the turbine rotor shaft is composed of several parts. In this regard, for example, a flange connection 50 (eg. B. bolted flange) is in the embodiment according to Fig. 1, by means of which as separate pieces gefer ^¬ preferential shaft portions of the turbine rotor shaft 12 in the ones shown, easily assembled state are joined together.

A symbolized in Fig. 1 control device ST is used to control the operation of the steam turbine 10, in particular for STEU ^¬ tion or control of the live steam supply at the inlet 26 and other controllable system components, the z. B. in connection with the (not shown) steam treatment can be used to reprocess the effluent at the outlet 28 exhaust steam and supply live steam again at the inlet 26.

In addition, the control device ST controls the operation of the rotary device 16 described in more detail below, by means of which, when the turbine 10 starts operating, the turbine Rotor shaft 12 is set in rotation or the start-up of the turbine 10 is supported.

The rotating device 16 is an electric motor whose rotor 52 is formed by a shaft portion 56 of the turbine rotor shaft 12 which is fitted with rotor magnets 54, the stator 58 of the electric motor being formed by stator magnets 62 mounted in a stator housing 60 and surrounding the rotor 52 at its outer periphery.

In the illustrated embodiment, the rotor magnets 54 are provided as permanent magnets (adhered z. B. or raised ^¬ screwed) on the outer circumference of the Wel ^¬ lenabschnittes 56 are attached. In a simple case, for. B. three rotor magnet 54 in the circumferential direction evenly distributed (in

120 ° intervals) arranged on the shaft portion 56. The stator ^¬ magnets 62 are formed in the illustrated embodiment as ak ^¬ tively energizable solenoids. In a simple case, it is again three circumferentially evenly distributed magnets.

When the steam turbine 10 starts to operate, the control device ST initiates energization of the stator magnet 62 in order to generate a rotating magnetic field in order to bring about or assist in starting up the turbine 10. In the example shown, in which the rotor magnets 54 are formed as permanent magnets, the rotation field generation in response to the current angle of rotation of the rotor is suitable to control. This control can se in a known per se WEI are bewerk ^¬ stelligt by a so-called electronic commutation. It is then a synchronous motor.

The "rotary operation of the turbine 10", in which the Drehein ^¬ direction 16 is activated, can also be used advantageously in a shutdown of the turbine 10, such as to prevent a distortion of the turbine rotor 20. In the following description of a further embodiment, the same reference numbers are used for equivalent components, in each case supplemented by a small letter "a" to distinguish the embodiment. Here, essentially only the differences from the already described embodiment will be discussed and incidentally hereby expressly referred to the description of this previous embodiment. Fig. 2 shows a modified embodiment of a z. 1 rotatable means 16a, which is also designed as an electric motor, where ^{¬ is formed} at the rotor 52a of the electric motor by a shaft portion 56a with circumferentially arranged rotor magnet 54a and the stator 58a of the electric motor of in a Statorge ^¬ housing 60a accommodated stator 62a is formed. During operation of the electric motor, a magnetic rotating field is generated again by means of the stator magnets 62a. In contrast to the already described execution ^¬ for the rotor magnets 54a are vorgese ^¬ hen as short-circuited Mag ^¬ netwindungen in the form of a so-called squirrel-cage rotor. Thus, in this exemplary embodiment, the rotary device 16a is a squirrel-cage three-phase asynchronous motor.

It is understood that the Ausführungsbei ^¬ games described above can be modified in many ways. It is essential to use a specific shaft section of the respective turbine rotor shaft for forming the rotor of an electric motor. So that the desired rotation driving the turbine rotor shaft can in a simple and reli ^¬ permeable, in particular essentially accomplish wear-free manner.

Depending on the design of the electric motor or the associated electrical control circuit (inverter etc.) it is possible lent to use the electric motor (in a "generator mode") also to decelerate the turbine in question.

Claims

claims

1. Steam turbine plant comprising a steam turbine (10) with a turbine rotor shaft (12) and a controllable rotating device (16) for rotationally driving the turbine rotor shaft (12) at an operating start and / or operating ^¬ send the steam turbine (10), characterized in that said rotating means (16) is an electric ^¬ motor, wherein the rotor (52) of the electric motor by a shaft portion (56) of the turbine rotor shaft (12) is formed, and the stator (58) of Elektromo ^¬ gate rotor (52) at its Surrounds outer circumference.

2. Steam turbine plant according to claim 1, wherein the rotor (52) of the electric motor forming shaft portion (56) of the turbine rotor shaft (12) outside of a steam- ^flow turbine housing (18) of the steam turbine (10) is seen before ^¬ .

3. Steam turbine plant according to claim 2, wherein the Wellenab ^{¬ section} (56) between the steam turbine (10) and a da ^¬ of the turbine rotor shaft (12) rotationally driven working machine (14), in particular an electric Ge ^¬ generator, is provided.

4. Steam turbine plant according to one of the preceding claims, wherein rotor magnets (54) of the electric motor are designed as Perma ^¬ nentmagnete or short-circuited magnetic windings or as short-circuited magnetic coils.

5. Steam turbine plant according to one of the preceding Ansprü ^¬ che, wherein stator magnets (62) of the electric motor are formed as Mag ^¬ netspulen for generating a magnetic rotating field.

6. Steam turbine plant according to one of the preceding Ansprü ^¬ che, wherein the electric motor is designed as an asynchronous motor with squirrel cage (54a).

7. Use of a controllable rotating device (16) for rotationally driving a turbine rotor shaft (12) in a steam turbine (10), characterized in that an electric motor designed Dreheinrich ^¬ device (16) is used, wherein the rotor (52) of the Elek ^¬ romotors of a shaft portion (56) of the turbine rotor shaft (12) is formed and the stator (58) of the electric motor surrounds the rotor (52) on its outer circumference, and that the rotating means (16) operatively so ^¬ well at a start of operation and at a Operation ^¬ send the steam turbine (10) is used to thereby accomplish an electrical rotary drive of the turbine rotor shaft (12).