Power plants – Combustion products used as motive fluid – With combustible gas generator
Reexamination Certificate
2001-02-20
2001-10-16
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
With combustible gas generator
C060S039190, C060S728000
Reexamination Certificate
active
06301873
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a gas turbine and steam turbine installation with a waste-heat steam generator connected downstream of a gas turbine. The heating surfaces of the waste-heat steam generator are connected into the water/steam cycle of a steam turbine. A gasification device for gasifying fuel is connected, with a fuel line, upstream of a combustion chamber of the gas turbine. A saturator is connected into the fuel line. The gasified fuel is guided in counterflow to a water flow which is guided in a saturator cycle.
A gas turbine and steam turbine installation with integrated gasification of fossil fuel usually includes a fuel gasification device which is connected, at the outlet end, to the combustion chamber of the gas turbine via a number of components provided for gas cleaning. The waste-heat steam generator can then be connected downstream of the gas turbine, at a flue gas side. The heating surfaces of the waste-heat steam generator are connected into the water/steam cycle of the steam turbine. Such an installation is known, for example, from Published UK Patent Application GB-A 2 234 984.
In order to reduce the pollutant emission during the combustion of the gasified fossil fuel, a saturator is connected, in this installation, into the fuel line between the gasification device and the combustion chamber of the gas turbine. The gasified fuel is loaded with water vapor in the saturator. For this purpose, the gasified fuel flows through the saturator in counterflow to a flow of water which is guided within a water cycle. This water cycle is designated as saturator cycle. In order to set a temperature level in the saturator which is sufficient for loading the gasified fuel with water vapor, heat is coupled into the saturator cycle by cooling the tapped or extracted air and/or by cooling the crude gas from the fuel gasification.
In this installation, however, the operation of the saturator depends on the operating condition of the gasification device and/or on the operating condition of an air separation unit connected upstream of the gasification device, so that this concept only has limited flexibility. With respect to control, furthermore, such a concept is comparatively complicated and therefore susceptible to failure.
U.S. Pat. No. 5,319,924 discloses to preheat, in a heat exchanger, the feed water to be fed into a saturator, wherein it is possible to provide the heat exchanger with uncleaned crude gas on the primary side. In addition, a saturator configured as a fuel humidifier is known from Published, Non-Prosecuted Patent Application DE 43 21 081 in which a heat exchanger, which is supplied with feed water on the primary side, is provided for preheating the saturator water.
In the article “Effiziente und umweltfreundliche Stromerzeugung im GUD-Kraftwerk mit integrierter Vergasung” [Efficient and environmentally friendly power production in a gas and steam power plant with integrated gasification] by G. Haupt in “Elektrotechnik und Informationstechnik” [Electrical engineering and information technology], AT, Springer Verlag, Vienna, Volume 113, No. 1,2 (Feb. 1996), pages 102-105, the heating in a heat exchanger of a water flow which is to be fed into a saturator is described. The water flow is heated in a heat exchange with feed water extracted from the water/steam cycle of the steam turbine and supplied in a dedicated reservoir (“flash tank”) connected into a circulating circuit. A heat exchanger is connected into this circulating circuit and in the heat exchanger the feed water absorbs heat from a partial flow of compressed air, the air being appropriately cooled in the process.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a turbine installation which overcomes the above-mentioned disadvantages of the heretofore-known turbine installations of this general type and which allows, in a particularly simple manner, reliable operation of the saturator even under different operating conditions.
With the foregoing and other objects in view there is provided, in accordance with the invention, a turbine installation, including:
a gas turbine having a combustion chamber and a flue gas side;
a steam turbine having a water/steam cycle;
a waste-heat steam generator connected downstream of the flue gas side of the gas turbine, the waste-heat steam generator having heating surfaces connected into the water/steam cycle of the steam turbine;
a fuel line;
a gasification device for providing gasified fuel, the gasification device being connected upstream of the combustion chamber of the gas turbine via the fuel line;
a saturator cycle for guiding a waterflow;
a saturator connected into the saturator cycle and into the fuel line, the saturator guiding the gasified fuel in a counterflow to the water flow guided in the saturator cycle;
a saturator-water heat exchanger connected, with a secondary side thereof, into the saturator cycle, the saturator-water heat exchanger being supplied, on a primary side thereof, with feed water extracted from the water/steam cycle of the steam turbine, the saturator-water heat exchanger heating the water flow and cooling the feed water;
an air separation unit connected upstream of the gasification device;
an air compressor;
an extraction air line connecting the air compressor to the air separation unit for providing a partial flow of compressed air to the air separation unit;
a feed water tank allocated to the waste-heat steam generator;
a feed water line connecting the saturator-water heat exchanger at an outlet side thereof to the feed water tank; and
a further heat exchanger connected with a primary side thereof in the extraction air line, the further heat exchanger being connected with a secondary side thereof into the feed water line, and the further heat exchanger heating the feed water and cooling the partial flow of compressed air.
In other words, the object of the invention is achieved by a saturator-water heat exchanger, which is connected on the secondary side into the saturator cycle to heat the water flow, and which can be supplied, on the primary side, with feed water extracted from the water/steam cycle of the steam turbine, wherein it is possible to heat the feed water cooled in the saturator-water heat exchanger through the use of a partial flow of compressed air, wherein it is possible to supply the partial flow of compressed air to an air separation unit connected upstream of the gasification device, and wherein it is possible to connect a further heat exchanger on the primary side in an extraction air line connecting the air compressor to the air separation unit in order to cool the partial flow of compressed air, the secondary side of the further heat exchanger is connected into a feed water line connecting the saturator-water heat exchanger at the outlet end to a feed water tank associated with the waste-heat steam generator.
According to another feature of the invention, the air separation unit has an inlet side and receives at the inlet side the partial flow of compressed air compressed in the air compressor associated with the gas turbine; and the gasification device receives oxygen from the air separation unit.
According to a further feature of the invention, the saturator cycle defines a flow direction for the water flow; and a feed line opens into the saturator cycle upstream of the saturator-water heat exchanger as seen in the flow direction of the water flow.
The invention is based on the consideration that a reliable operation of the saturator is made possible even when there are differing operating conditions, and therefore a particularly high flexibility of the gas turbine and steam turbine installation is achieved in that the saturator can be operated independently of the operating parameters of the gasification device and the air separation unit. In this connection, the coupling of the heat into the saturator cycle, in particular, should not take place directly through the use of a medium flowing out of the gasi
Hannemann Frank
Schiffers Ulrich
Freay Charles G.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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