Rotary kinetic fluid motors or pumps – Method of operation
Reexamination Certificate
2001-08-29
2003-06-03
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Method of operation
C415S145000, C415S155000
Reexamination Certificate
active
06572328
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention lies in the field of steam turbines. More particularly, it relates to a combined gas and steam turbine power plant. In addition, the present invention relates to a method of feeding bypass steam into the steam turbine.
In power plant technology, power plant types may be differentiated according to their type of power generation or according to their field of application. One power plant type includes the industrial power plant, which generates current only as a secondary product. However, the more important energy product is the heating energy or the process steam for industrial or chemical processes.
Examples of a power plant type for commercial power generation include the steam-turbine power plant or the gas-turbine power plant.
A combination of a steam-turbine process with a gas-turbine process leads to a “combined-cycle process”, in which at least one gas turbine is interconnected with a steam turbine. The power-generation efficiencies, which can be achieved thereby are comparatively high. Such a combined gas and steam turbine power plant is also termed a combined-cycle power plant.
However, a disadvantage of the combined-cycle power plants is that the quantity of electricity, which can be generated, depends to a great extent on the gas turbines. Gas turbines are standardized products, whose output or power generation depends significantly on ambient conditions, such as ambient temperatures. Even including the downstream steam-turbine process, the quantity of electricity generated, for example in the summer, is only about 80% of the quantity of electricity generated in the winter.
However, it is sometimes necessary for a higher quantity of electricity to be generated even in the summer months, than which can be delivered by the combined-cycle process: for example, in the event of an increased demand for electricity, during this period due to air-conditioning units being connected to the system. In order to meet this extra demand for electricity, combined-cycle power plants having supplementary firing are used. A steam generator, also called a heat recovery boiler in combined-cycle power plants, is not only fed with hot exhaust gases from the gas turbine, but is also loaded with an additional energy input by the combustion of a fossil fuel. Accordingly, the heat recovery boiler can produce a correspondingly larger steam quantity as “live steam” and also achieve a higher live-steam pressure. The output of the steam turbine increases accordingly, but the heat recovery boiler, the live-steam lines and other components of the live-steam path must be designed in accordance with this comparatively rare, but maximum, live-steam state.
The design is therefore affected by unusual conditions. The “100% load case”, at comparatively low values of the live-steam pressure, leads to a decreased efficiency of the combined-cycle power plant. In addition, the combined-cycle power plant is equipped with components of comparatively large dimensions, which are more expensive.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a steam turbine and a method of feeding bypass steam that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that has an increased output with a comparatively low technical outlay.
With the foregoing and other objects in view, there is provided, in accordance with the present invention, a steam turbine including at least one valve arrangement, the valve arrangement having at least one quick-closing valve and at least one live-steam control valve, the live-steam control valve being assigned to the quick-closing valve is provided. A steam-turbine inlet region, a high-pressure region, and a first turbine moving-blade row, a live-steam bypass having at least one bypass line and a bypass feed are provided. The bypass feed is coupled to the bypass line. The live-steam bypass feed live steam as bypass steam into the high-pressure region, after the first turbine moving-blade row, as viewed from downstream of the steam-turbine inlet region. At least one bypass control valve is also provided. Further, both the at least one live-steam control valve and the at least one bypass control valve are assigned to the at least one quick-closing valve.
In accordance with another feature of the present invention, the at least one bypass control valve, the at least one quick-closing valve and the at least one live-steam control valve are disposed in a common valve casing.
In accordance with another feature of the present invention, the live-steam bypass includes precisely one bypass line and precisely one bypass feed.
In accordance with another feature of the present invention, the top steam turbine further includes a top steam-turbine outer casing.
In accordance with another feature of the present invention, the at least one bypass feed is disposed in the high-pressure region such that a dismantling of the bypass feed is avoided during a dismantling of the top steam-turbine outer casing.
In accordance with another feature of the present invention, there is provided at least two adjacent blade rows and a bypass inlet region. The bypass feed feeds bypass steam into the high-pressure region through the bypass inlet region. The bypass inlet region is freely selectable in an axial direction between the two adjacent blade rows.
In accordance with another feature of the present invention, there is provided a torus-like annular space, a U-shaped profile element, an inner casing, a turbine shaft section, and a blade passage disposed between the inner casing and the turbine shaft section. The torus-like annular space is defined by an outside diameter and an inside diameter.
In accordance with another feature of the present invention, the bypass steam is uniformly distributed over a circumference in the bypass inlet region by the torus-like annular space.
In accordance with another feature of the present invention, the torus-like annular space is formed by the U-shaped profile element defining a boundary of the outside diameter and at least a partial axial boundary on both sides.
In accordance with another feature of the present invention, the torus-like annular space is formed by an appropriate configuration of the inner casing for defining a boundary of the inside diameter and at least a partial axial boundary on both sides.
In accordance with another feature of the present invention, the U-shaped profile element is configured so as to be self-sealing against a partly expanded steam in the blade passage in the bypass inlet region, when a bypass-steam having a comparatively higher bypass-steam pressure in the torus-like annular space is utilized.
In accordance with another feature of the present invention, the inner casing, in the bypass inlet region, includes apertures. The apertures are disposed as at least one connection between the torus-like annular space and the blade passage. The apertures are further disposed and configured such that a homogeneous mixing of the bypass steam bypass-steam having a comparatively higher bypass-steam pressure from the torus-like annular space and the partly expanded steam in the blade passage is achieved in the bypass inlet region.
With the foregoing and other objects in view, there is provided, in accordance with the present invention, a method of feeding bypass steam into a steam turbine, which includes the steps of controlling a live steam through at least one valve arrangement, feeding the live steam via a quick-closing valve, and partially feeding the live steam to a turbine inlet region via at least one live-steam control valve. The method further includes the step of partially feeding the live steam as bypass steam to a bypass inlet region in a high-pressure region of the steam turbine via at least one bypass control valve.
In accordance with another feature of the present invention, the bypass steam is fed into a high-pressure region via a bypass line and via a bypass feed, although the bypass s
Tremmel Alexander
Welz Patrick
Alstom (Switzerland) Ltd.
Greenberg Laurence A.
Locher Ralph E.
Look Edward K.
McCoy Kimya N
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