US20130133335A1

US20130133335A1 - Power Plant Line Having a Variable-Speed Pump

Info

Publication number: US20130133335A1
Application number: US13/639,477
Authority: US
Inventors: Hartmut Graf; Karl Hilpert
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2010-04-09
Filing date: 2011-03-18
Publication date: 2013-05-30
Also published as: CN103221644B; DE102010014588A1; JP5738398B2; CN103221644A; WO2011124322A3; EP2556217A2; KR20130093484A; JP2013527895A; WO2011124322A2

Abstract

The invention relates to a power plant line, comprising a steam turbine and/or gas turbine that rotates at a constant speed in order to drive an electric generator; a variable-speed pump for conveying and/or compressing a working medium in order to drive and/or supply the process of the steam turbine and/or the gas turbine or to pump and/or compress an exhaust gas produced in the process supply or in the gas turbine. The invention is characterized in that the variable-speed pump is driven by the steam turbine and/or gas turbine and a speed-controllable gear train is arranged in the driving connection, said gear train having a power split, which comprises a mechanical main branch and a hydrodynamic secondary branch, wherein driving power is branched off from the mechanical main branch via a hydrodynamic coupling or a hydrodynamic converter by means of the hydrodynamic secondary branch and fed back to the mechanical main branch at the output side of the gear train in a variable-speed manner by means of a superimposing gear train.

Description

The present invention relates to a power plant train having a steam turbine and/or gas turbine revolving at a constant speed for driving an electric generator and also having a variable-speed pump, which is driven by the steam turbine and/or the gas turbine. The variable-speed pump is used to convey and/or compress a work medium for the drive and/or the process supply of the steam turbine and/or the gas turbine. Alternatively, the pump is used to convey and/or compress an exhaust gas or a component thereof which is arises or is conveyed, respectively, in the process supply or in the gas turbine.
Boiler feed pumps are known as such variable-speed pumps in power plants, the pumps being driven by the power plant train, by means of which pumps the feed water of the boiler of the steam generator for the steam turbine and therefore the working medium of the steam turbine being conveyed. Such boiler feed pumps have, according to an embodiment as it relates to the present invention, a power consumption of multiple megawatts, for example, 15 or 20 MW or more.
While the turbine, in particular the steam turbine, typically revolves at constant speed to drive an electric generator, which is in turn used for power generation at a constant frequency, the boiler feed pumps are operated at varying speed, depending on the requirements for the quantity of fresh steam. The boiler feed pumps are therefore typically driven via an electric motor, which in turn acquires its electrical power from the generator. Losses arise during the conversion of the steam power or the power of the working medium of the turbine in general, respectively, into electrical power and during the subsequent conversion of the electrical power into mechanical energy (rotational energy).
To provide a remedy here, it is conceivable that the variable-speed pump is driven by means of the steam turbine and/or the gas turbine, and mechanically without the intermediate conversion of the drive power into electrical power, and for an adjustable-speed transmission to be arranged between the steam turbine and/or the gas turbine and the variable-speed pump for the desired speed conversion, by means of which the drive power of the steam turbine is transmitted to the pump. Such an adjustable-speed transmission can be formed, for example, by a hydrodynamic control clutch or can comprise such a clutch, whose toroidal working chamber can be alternately filled more or less with working medium to change the speed on the output side of the hydrodynamic clutch. Providing such an adjustable-speed transmission with other speed conversion units also comes into consideration, which allow a torque transmission through electromagnetic fields or mechanically with varying slip. However, the large power consumption of the boiler feed pump and the power transmission connected thereto via the speed conversion unit in the adjustable-speed transmission is problematic in this case.
Similar problems result in the drive of a variable-speed pump, which could then also be referred to as a compressor, by means of which exhaust gas or a component thereof, for example, CO₂, is to be conveyed into an underground pressure accumulator to improve the CO₂balance of the power plant.
The present invention is based on the object of specifying a power plant train, which has an improved embodiment with respect to the efficiency and the design expenditure and the construction expenditure for the drive of such a pump.
The object according to the invention is achieved by a power plant train having the features of Claim 1. Advantageous and particularly expedient embodiments of the invention are specified in the dependent claims.
The power plant train according to the invention has a steam turbine and/or a gas turbine for driving an electrical generator. Accordingly, the generator is only driven by one or more steam turbines in a so-called steam power plant or is only driven by one or more gas turbines in a so-called gas power plant. However, so-called combined-cycle power plants or gas-and-steam power plants also come into consideration, in which one generator or multiple generators are driven both by at least one steam turbine and also by at least one gas turbine, the waste heat of the exhaust gas of the gas turbine typically being used for steam generation for the steam turbine.
The steam turbine and/or the gas turbine revolve or revolves at a constant speed, so that electrical energy having a predefined Hertz number can be generated by means of the electrical generator.
Furthermore, a variable-speed pump is driven by means of the steam turbine and/or the gas turbine and accordingly has a mechanical drive connection to the steam turbine or the gas turbine, respectively. The variable-speed pump can be implemented, for example, to convey and/or compress a working medium for driving the steam turbine and/or the gas turbine. For example, the pump is a boiler feed pump, which conveys the working medium of the steam turbine in a steam generation unit. However, other variable-speed pumps also come into consideration, which are required for the process supply of the steam turbine and/or the gas turbine, for example, oil pumps, air pumps, or the like. Furthermore, in the present case the term pump refers not only to conveyer units for conveying a non-compressible medium, but rather it is also to comprise compressors which are used to convey and/or compress a compressible medium.
According to a particular embodiment of the present invention, the pump (or the compressor) is used to convey and/or compress exhaust gas which arises in the process supply of the steam turbine and/or the gas turbine or in the gas turbine. Pumping the exhaust gas or a component thereof, in particular CO₂, into an underground accumulator, in particular a pressure accumulator, by means of the pump in order to improve the CO₂balance of the power plant in which the power plant train is provided, comes into consideration here in particular. Exhaust gas of the process supply means in particular the exhaust gas arising upon the combustion of a fossil fuel for steam generation or hot gas generation.
According to the invention, an adjustable-speed transmission, comprising a power split having a mechanical, in particular exclusively mechanical main branch and a hydrodynamic secondary branch, is arranged in the drive connection between the variable-speed pump and the steam turbine and/or gas turbine driving it. Drive power is branched off by means of the hydrodynamic secondary branch via a hydrodynamic clutch and/or a hydrodynamic converter from the main branch and is supplied back to the main branch on the transmission output side by means of an adjoining superposition transmission. A speed adaptation can be achieved by means of the hydrodynamic clutch or the hydrodynamic converter, which, through the superposition on the main branch on the transmission output side allows a speed adaptation of the constant speed present at the transmission input to the desired speed of the pump.
The majority of the power transmitted by means of the adjustable-speed transmission is advantageously mechanically transmitted directly via the mechanical main branch to the transmission output of the adjustable-speed transmission, and the secondary branch having the hydrodynamic machine is only used for speed adaptation and transmits, for example, at most 30% or 35% of the total power transmitted using the adjustable-speed transmission or the consumed power of the variable-speed pump, respectively. For example, the power in the secondary branch in relation to the rated power of the pump can be 20% to 3S % of the total power, or the power in the secondary branch in the control range of the pump can be 0% to 35% of the total power.
It is advantageous if the superposition transmission of the adjustable-speed transmission is implemented as a planetary gear. In particular the ring gear of the planetary gear can be mechanically connected to the input shaft, the planet carrier can be mechanically connected to the secondary side of the hydrodynamic machine, in particular the turbine wheel of the hydrodynamic converter, and the sun wheel can be mechanically connected to the output shaft of the transmission. In particular an embodiment of the adjustable-speed transmission as is disclosed in the international patent application having the publication number WO 2010/009836 A1 or the prior art described therein also comes into consideration.
It is particularly favorable if a step-down transmission is connected upstream from the adjustable-speed transmission, to step down the speed of the steam turbine and/or the gas turbine, so that the input shaft of the adjustable-speed transmission revolves at a lower speed than the steam turbine and/or the gas turbine. Such a step-down transmission can advantageously be flanged externally onto the adjustable-speed transmission. If the step-down transmission comprises a planetary stage or a planetary gear, respectively, the planet carrier can be carried by the adjustable-speed transmission, in particular its housing.
The step-down transmission will typically have a fixed step-down transmission ratio. According to an advantageous embodiment, however, the step-down transmission ratio is variable at least or exclusively at a standstill, in order to achieve an input speed adaptation of the adjustable-speed transmission for the respective intended use, in order to either achieve standardization of the adjustable-speed transmission used in various facilities and/or to optimize the efficiency of the adjustable-speed transmission.
For example, the steam turbine and/or the gas turbine revolves at 3000 or 3600 RPM, while in contrast the input shaft of the adjustable-speed transmission revolves at 1500 to 1800 RPM.
Of course, it is also possible to equip the step-down transmission with a spur gear or a further form of transmission additionally or alternatively to the planetary gear.
A particularly favorable embodiment of the invention provides that the step-down transmission also has a power split function and distributes the drive power fed in at its transmission input from the steam turbine and/or the gas turbine to two or more transmission outputs. For example, one pump is connected to each transmission output. According to one embodiment, all connected pumps are variable-speed pumps and are then advantageously each driven via an adjustable-speed transmission after the transmission output of the step-down transmission. According to an alternative embodiment, a pump revolving at constant speed is attached at least to one transmission output of the step-down transmission, which operates in particular as a backing pump to the variable-speed pump or pumps attached to the other transmission output or the other transmission outputs and accordingly is connected upstream from the variable-speed pump or pumps with respect to the medium conveyed through the pumps. It also applies here that the term pump is also to comprise compressors for compressing a medium.
In particular if the pumps at the various transmission outputs of the step-down transmission are each driven via an adjustable-speed transmission, it is advantageous if the respective pump or the upstream adjustable-speed transmission, respectively, is assigned a parking brake and/or a disconnecting clutch, by means of which the corresponding part of the drivetrain can be decoupled or stopped, respectively, to perform maintenance work, for example. The drive of the other pump or pumps can be continued simultaneously.
According to one embodiment according to the invention, the adjustable-speed transmission, via which the variable-speed pump is driven, has at least one oil pump or lubricant pump in general, which is used for the lubricant oil supply/lubricant supply of the adjustable-speed transmission, the steam turbine and/or the gas turbine, the step-down transmission, and/or a secondary assembly provided for operating the steam turbine and/or the gas turbine. Such a secondary assembly can be, for example, a fan, a safety unit, a process monitoring unit, or another assembly. Of course, the lubricant oil supply/lubricant supply of the generator by means of the at least one oil pump integrated in the adjustable-speed transmission is also possible.
If multiple adjustable-speed transmissions are provided for driving multiple pumps, they can be arranged in parallel in the power plant train, as shown, in particular after a step-down transmission having multiple outputs, and can also advantageously be carried by means of a shared foundation frame. This is correspondingly true for the various pumps.

The invention will be explained in greater detail hereafter as an example on the basis of exemplary embodiments and the figures. In the figures:

FIG. 1 shows a first exemplary embodiment of a power plant train according to the invention having a boiler feed pump driven by a steam turbine via an adjustable-speed transmission;

FIG. 2 shows an exemplary embodiment implemented according to the invention having two boiler feed pumps;

FIG. 3 shows an exemplary embodiment according to FIG. 1, but having an additional step-down transmission connected upstream from the adjustable-speed transmission and flanged thereon;

FIG. 4 shows an exemplary embodiment similar to that of FIG. 3, in which, however, the step-down transmission is positioned at a distance from the adjustable-speed transmission;

FIG. 5 shows a further exemplary embodiment having a boiler feed pump attached to a first output of the step-down transmission via an adjustable-speed transmission and a constant-speed backing pump attached directly to a second output of the step-down transmission;

FIG. 6 shows an exemplary embodiment of a possible adjustable-speed transmission.

FIG. 1 shows a power plant train implemented according to the invention having a steam turbine 1, which drives an electrical generator 2. Furthermore, a variable-speed boiler feed pump 3 is arranged in the main train of the power plant drivetrain, which is driven via an adjustable-speed transmission 4 by means of the steam turbine 1. The adjustable-speed transmission 4 has a mechanical main branch 5 and a hydrodynamic secondary branch 6. The majority of the drive power is transmitted via the mechanical main branch 5 from the input of the adjustable-speed transmission to its output. Only a comparatively smaller part is transmitted via the hydrodynamic secondary branch 6 for the speed adaptation of the transmission output or the boiler feed pump 3, respectively.
In addition, as indicated by the dashed lines, a backing pump 7 could be assigned to the boiler feed pump 3, which can be arranged either after the boiler feed pump 3 or also at another point, in particular before the adjustable-speed transmission 4, in the direction of the drive power flow. The backing pump 7 is either also implemented as a variable-speed pump, as shown, or, in particular if it is arranged before the adjustable-speed transmission 4 in the direction of the drive power flow viewed from the steam turbine 1, as a pump which revolves at constant speed.
According to the embodiment in FIG. 2, two boiler feed pumps 3 are driven via two adjustable-speed transmissions 4 by means of the steam turbine 1, and optionally two corresponding backing pumps 7. For this purpose, a power split transmission having one transmission input and two transmission outputs, to which the power of the transmission input is allocated, and which is advantageously, but not necessarily implemented as a step-down transmission 8, is provided before the adjustable-speed transmission 4 in the direction of the drive power flow from the steam turbine 1 to the boiler feed pumps 3.
According to the embodiment in FIG. 3, a step-down transmission 8 is also provided. It is flanged on the input side onto the adjustable-speed transmission 4 and forms a structural unit therewith. It is also not absolutely necessary here for the power split to be performed in a step-down transmission. In general, a power split transmission could also be provided, whose input shaft revolves at the same speed as the output shafts or even at a comparatively lower speed.
In the embodiment according to FIG. 4, the step-down transmission 8 is arranged separately from the adjustable-speed transmission 4 and before it in the direction of the drive power flow.
In the embodiment according to FIG. 5, a power split transmission is again provided, advantageously implemented as a step-down transmission 8, on whose first output an adjustable-speed transmission 4 having a mechanical main branch 5 and a hydrodynamic secondary branch 6 is attached, by means of which a boiler feed pump 3 is driven. A backing pump 7 is attached to the second output of the step-down transmission 8, the pump being operated at constant speed, so that an adjustable-speed transmission between the step-down transmission 8 and the backing pump 7 can be omitted.
In FIG. 6, an exemplary embodiment of an adjustable-speed transmission 4 having flanged-on step-down transmission 8 is shown. The mechanical main branch 5 of the adjustable-speed transmission 4 is formed by an input shaft 9 of the adjustable-speed transmission 4 and an adjoining planetary gear 10 and the output shaft 11. The input shaft 9 drives the ring gear 12 of the planetary gear 10, which is mechanically connected via the planets 13 to the sun wheel 14. The sun wheel 14 has a mechanical connection to the output shaft 11 or is carried thereby.
The hydrodynamic secondary branch 6 is formed by a hydrodynamic converter 15, implemented here as an adjustable converter, and mechanical transmission stages adjoining thereon. These mechanical transmission stages are in turn connected to the planet wheels 13 or the planet carrier 26, respectively, of the planetary gear 10.
FIG. 6 shows two possible exemplary embodiments for the mechanical transmission stages of the hydrodynamic secondary branch, specifically a first exemplary embodiment above the input shaft 9 and a second exemplary embodiment below the input shaft 9. In both exemplary embodiments, the pump wheel 16 of the hydrodynamic converter 15 is mechanically attached to the input shaft 9 or is carried thereby, respectively. In both exemplary embodiments, the turbine wheel 17 of the hydrodynamic converter 15 has a drive connection via an intermediate gear wheel 18 to either an intermediate shaft 20 according to the first exemplary embodiment or a ring gear 21 according to the second exemplary embodiment. The connection between the turbine wheel 17 and intermediate gear wheel 18 is implemented in both exemplary embodiments via a hollow shaft 19, which carries an external gear wheel 22.
The intermediate shaft 20 carries, according to the first exemplary embodiment, a first gear wheel 23, which meshes with the intermediate gear wheel 18, and a second gear wheel 24, which meshes with a third gear wheel 25, which carries the planet carrier 26 so it is rotatable. According to the second exemplary embodiment, the hollow shaft 21 meshes with the intermediate gear wheel 18, a plurality of which can also be provided, and carries the planet carrier 26, either so it is rotatable or rotationally fixed. In the second exemplary embodiment, the gear wheels 22, 18 and the gear teeth of the hollow shaft 21 can represent a planetary gear, in particular if two, three, or more intermediate gear wheels 18 are provided. As shown, in the exemplary embodiment, the hollow shaft 21 is provided with internal gear teeth. This can be achieved in that an internally-toothed spur wheel is attached to a hollow shaft or the hollow shaft has internal gear teeth.
The hydrodynamic converter 15 also has an adjustable guide vane ring 27. Notwithstanding the embodiment shown here, further guide vane rings and/or vane wheels could also be provided.
The step-down transmission 8 is flanged using its transmission housing 31 on the housing 32 of the adjustable-speed transmission 4, for example, by screwing on, welding on, or another suitable removable or non-removable fastening. The step-down transmission 8 has an input shaft 28 and an output shaft 29. The output shaft 29 can be implemented in one piece with the input shaft 9 of the adjustable-speed transmission 4, or can be suitably attached in a formfitting and/or friction-locked manner removably or non-removably thereon.
The input shaft 28 is mechanically connected via a planetary gear 30 to the output shaft 29. The planetary gear 30 represents a step-down transmission stage, so that the input shaft 28 revolves at a higher speed than the output shaft 29, for example, at twice the speed.
The planet carrier 33 of the planetary gear 30 is carried by the housing 32 of the adjustable-speed transmission 4. Of course, it would also be possible to provide another step-down transmission, for example, in the form of a spur gear, instead of the planetary gear 30.

Claims

1-10. (canceled)

11. A power plant train comprising:

a steam turbine and/or gas turbine, which revolves at a constant speed, for driving an electric generator;

a variable-speed pump for conveying and/or compressing a working medium for the drive and/or the process supply of the steam turbine and/or the gas turbine or for conveying and/or compressing an exhaust gas arising in the process supply or the gas turbine; characterized in that

the variable-speed pump is driven by means of the steam turbine and/or gas turbine and an adjustable-speed transmission is arranged in the drive connection, comprising a power split having a mechanical main branch and a hydrodynamic secondary branch,

by means of the hydrodynamic secondary branch, drive power is branched off via a hydrodynamic clutch or a hydrodynamic converter from the mechanical main branch and is supplied back to the mechanical main branch on the transmission output side at variable speed by means of a superposition transmission.

12. The power plant train according to claim 11, characterized in that the variable-speed bump is a boiler feed pump for conveying the working medium of the steam turbine.

13. The power plant train according to claim 11, characterized in that the hydrodynamic secondary branch is configured to transmit at most 30% or 35% of the power of the mechanical main branch or all of the power transmittable using the adjustable-speed transmission.

14. The power plant train according to claim 12, characterized in that the hydrodynamic secondary branch is configured to transmit at most 30% or 35% of the power of the mechanical main branch or all of the power transmittable using the adjustable-speed transmission.

15. The power plant train according to claim 11, characterized in that a step-down transmission is connected upstream from the adjustable-speed transmission, which is particularly flanged externally onto the adjustable-speed transmission.

16. The power plant train according to claim 12, characterized in that a step-down transmission is connected upstream from the adjustable-speed transmission, which is particularly flanged externally onto the adjustable-speed transmission.

17. The power plant train according to claim 13, characterized in that a step-down transmission is connected upstream from the adjustable-speed transmission, which is particularly flanged externally onto the adjustable-speed transmission.

18. The power plant train according to claim 14, characterized in that a step-down transmission is connected upstream from the adjustable-speed transmission, which is particularly flanged externally onto the adjustable-speed transmission.

19. The power plant train according to claim 15, characterized in that the step-down transmission comprises a planetary gear, whose planet carrier is carried by the adjustable-speed transmission, in particular its housing.

20. The power plant train according to claim 16, characterized in that the step-down transmission comprises a planetary gear, whose planet carrier is carried by the adjustable-speed transmission, in particular its housing.

21. The power plant train according to claim 17, characterized in that the step-down transmission comprises a planetary gear, whose planet carrier is carried by the adjustable-speed transmission, in particular its housing.

22. The power plant train according to claim 18, characterized in that the step-down transmission comprises a planetary gear, whose planet carrier is carried by the adjustable-speed transmission, in particular its housing.

23. The power plant train according to claim 15, characterized in that the step-down transmission has a transmission input in drive connection to the steam turbine and/or the gas turbine, furthermore at least two or precisely two transmission outputs and a power split, which distributes the drive power from the transmission input to the transmission outputs, and a pump is attached to each transmission output, in particular via an adjustable-speed transmission, comprising a power split having a mechanical main branch and a hydrodynamic secondary branch, drive power being branched off via a hydrodynamic clutch or a hydrodynamic converter from the mechanical main branch by means of the hydrodynamic secondary branch and being supplied back to the mechanical main branch at the transmission output side at variable speed by means of a superposition transmission.

24. The power plant train according to claim 23, characterized in that a pump revolving at constant speed is attached to one transmission output and a variable-speed pump is attached via an adjustable-speed transmission to the other transmission output, the pump revolving at constant speed being connected upstream as the backing pump with respect to the conveyed medium from the variable-speed pump.

25. The power plant train according to claim 23, characterized in that a parking brake and/or a disconnecting clutch is arranged in each case in the drive connection between one transmission output or both transmission outputs and the respective pump.

26. The power plant train according to claim 11, characterized in that the adjustable-speed transmission has an oil pump, which is used for the lubricant oil supply of the adjustable-speed transmission, the steam turbine and/or the gas turbine, the generator, the step-down transmission, and/or a secondary assembly provided for the operation of the steam turbine and/or the gas turbine.

27. The power plant train according to claim 12, characterized in that the adjustable-speed transmission has an oil pump, which is used for the lubricant oil supply of the adjustable-speed transmission, the steam turbine and/or the gas turbine, the generator, the step-down transmission, and/or a secondary assembly provided for the operation of the steam turbine and/or the gas turbine.

28. The power plant train according to claim 13, characterized in that the adjustable-speed transmission has an oil pump, which is used for the lubricant oil supply of the adjustable-speed transmission, the steam turbine and/or the gas turbine, the generator, the step-down transmission, and/or a secondary assembly provided for the operation of the steam turbine and/or the gas turbine.

29. The power plant train according to claim 14, characterized in that the adjustable-speed transmission has an oil pump, which is used for the lubricant oil supply of the adjustable-speed transmission, the steam turbine and/or the gas turbine, the generator, the step-down transmission, and/or a secondary assembly provided for the operation of the steam turbine and/or the gas turbine.

30. The power plant train according to claim 11, characterized in that the pump pumps exhaust gas or a component thereof of the gas turbine and/or a hot steam generator for the steam turbine into an underground accumulator.