Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
1999-12-13
2001-10-30
Rosenbaum, I Cuda (Department: 3726)
Metal working
Method of mechanical manufacture
Impeller making
C029S889000, C029S401100
Reexamination Certificate
active
06308407
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the technological field of steam turbines. It relates to a method of manufacturing a plurality of steam turbines for use in various applications which differ in the respective thermodynamic parameters such as, for example, cooling-water temperature, ambient temperature, given boiler data, process-steam requirement, etc., the steam turbines in each case having at least one high-pressure stage with first blading and a control-wheel stage for part-load operation.
2. Background of the Invention
In the manufacture of steam turbines, which may exist as individual high-pressure (HP) machines or as combined high-pressure/intermediate-pressure (HPIP) machines, the blading of the high-pressure and/or intermediate-pressure part, in the event of an order being placed, is designed individually to the data required or specified for the respective application. This also includes—if there is a control-wheel stage for part-load operation—the individual design of the control-wheel stage with respectively adapted duct height (of the wheel duct) and an adapted number of wheel blades or nozzles arranged in an annular shape upstream of the control wheel in the direction of flow (for details of such control-wheel stages, reference may be made, for example, to publications U.S. Pat. No. 4,812,107, U.S. Pat. No. 4,881,872 and U.S. Pat. No. 4,979,873).
The result of this individual adaptation of the steam turbine is that, with each order, new customer-specific production documents have to be prepared for the entire blading including the small accessories and the control-wheel stage. A repetition effect during the production, of the control wheel too, is thus largely ruled out. This procedure certainly has the advantage that any customer-specific variation within the blading can be realized with the existing design tools. A disadvantage, however, is that possible cost-saving potentials are very small and are restricted to fine design details permitted by the existing design tools.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a novel method with which steam turbines can be manufactured for different applications and different thermodynamic parameters in a simple manner and with a high proportion of cost-saving standard components.
One of the objectives of the present invention consists in combining fixed standard blading in the high-pressure stage with a control-wheel stage varying in design from application to application, in order to adapt the steam turbine to the respective thermodynamic parameters of the application (e.g. condenser vacuum (cooling-water temperature), ambient temperatures, given boiler data of various manufactures, requisite process steam, etc.). The entire thermodynamic variability of the steam turbine is thus restricted to a single component (here the control-wheel stage), specifically both in terms of production and procurement. Since in particular the blading with the machining interface (turned recesses) at casing and shaft has an enormous simplification and cost-saving potential with regard to repetition effects, a considerable advantage is achieved by the standardization of the blading.
A first preferred embodiment of the method according to the invention is distinguished by the fact that the steam turbines in each case additionally have an intermediate-pressure part and a low-pressure part having second blading and third blading, and that standard blading likewise identical for all the steam turbines is used as second blading and third blading. By the use of such standard blading, an even greater simplification/saving is achieved in this case.
A second preferred embodiment of the method according to the invention is distinguished by the fact that the control-wheel stage has a control wheel sitting on the rotor and a plurality of nozzles arranged concentrically around the rotor axis, and that, in order to design the control-wheel stage, the control wheel and/or the nozzles are varied in their arrangement and/or configuration.
A preferred development of this embodiment is distinguished by the fact that the number of nozzles is varied and/or that the geometry of the individual nozzles is varied.
In another preferred development of this embodiment, the control wheel has a third blading variation, in which the wheel-blade geometry, in particular the blade-body thickness and/or the blade-body height and/or the curvature, is varied.
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Graf Peter
Herzog Maurus
Meylan Pierre
Romer Harald
ABB Alstom Power ( Schweiz) AG
Burns Doane Swecker & Mathis L.L.P.
Cuda Rosenbaum I
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