Prime-mover dynamo plants – Turbogenerators
Patent
1995-12-14
1998-07-14
Stephan, Steven L.
Prime-mover dynamo plants
Turbogenerators
290 2, 290 4C, 290 4D, 290 4R, 60 3931, 60 39182, 4152131, F01D 1510, F02C 600, H02K 718, H02D 904
Patent
active
057809321
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an electricity generating unit having a combined cycle, and comprising, mounted in succession along a common line of shafts via rigid couplings, the rotor of a gas turbine, the rotors of a steam turbine having a plurality of modules, and the rotor of an electricity generator, the gas turbine being mounted to move in axial translation, the line of shafts being provided with an abutment that is constrained to move in axial translation with the non-rotary portions of the gas turbine or of the first module of the steam turbine.
By associating two axial-flow turbo-machines on the same line of shafts, it is possible to reduce the dimensions of the machine room compared with a unit in which each turbo-machine drives its own electricity generator. Furthermore, only one alternator is needed.
Unfortunately, this results in very long lines of shafts, giving rise to considerable cumulative axial expansion of the various rotors, and making it necessary to provide large axial clearances in the flow-sections of the turbo-machines.
Such large axial clearances significantly affect the performance levels of the electricity generating unit.
BACKGROUND OF THE INVENTION
EP-A-0 407 132 relates to an electricity generating unit having a combined cycle and comprising, mounted in succession on a common line of shafts via rigid couplings, the rotor of a gas turbine, the rotors of a steam turbine having a plurality of modules, and the rotor of an electricity generator. The line of shafts is provided with an abutment secured to the fixed rear bearing of the gas turbine. The non-rotary portion of the gas turbine is mounted to move axially, the front of the non-rotary portion of the first module of the steam turbine is fixed to the foundations. In this way, the axial expansion is small between the gas turbine and the first module of the steam turbine, the non-rotary portion of the gas turbine expanding towards the front of the abutment like the associated portion of the line of shafts, and the non-rotary portion of the first module of the steam turbine expanding towards the rear of the abutment like the associated portion of the line of shafts.
One of the drawbacks of that configuration lies in the fact that the relative axial expansion between the rotary portions and the non-rotary portions of the turbines is poorly controlled, and this gives rise to relative axial displacement between the rotary portions and the non-rotary portions of the turbines, which displacement affects the performance levels of the electricity generating unit.
U.S. Pat. No. 5,271,217 relates to an electricity generating unit having a combined cycle and comprising, mounted in succession on a common line of shafts via rigid couplings, the rotor of a gas turbine, the rotors of a steam turbine, and the rotor of an electricity generator, the non-rotary portion of the gas turbine being mounted to move in axial translation, the non-rotary portion of the steam turbine being secured at both of its ends to the foundations. The non-rotary portions of the gas turbine and of the steam turbine are connected together via links. That configuration makes it possible to limit the relative axial displacement between the rotary portions and the non-rotary portions. However, it gives rise to other drawbacks, in particular the relative axial expansion between the links and the line of shafts, or the positions of the fixed points of the non-rotary portion of the steam turbine.
SUMMARY OF THE INVENTION
The present invention provides an electricity generating unit having a combined cycle, and comprising, from the front to the rear, mounted on foundations, a gas turbine followed by a steam turbine having at least one hot module and a cold module, followed by an electricity generator, the rotors of the gas turbine, of the steam turbine and of the electricity generator forming a common line of shafts via rigid couplings, the stator of the gas turbine being mounted to move in axial translation, the line of shafts being provided
REFERENCES:
patent: 5271217 (1993-12-01), Knuijt
Patent Abstracts Of Japan, vol. 7, No. 169 (M-231) 91314), 26 Jul. 1983 corresponding to JP, A, 58 074809 (Mitsubishi) dated May 6, 1983.
Enad Elvin G.
Gec Alsthom Electromecanique SA
Stephan Steven L.
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