Power plants – Combustion products used as motive fluid
Reexamination Certificate
1998-07-17
2001-05-01
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039182, C060S039530, C060S728000
Reexamination Certificate
active
06223523
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of operating a power-station plant according to the preamble of claims
1
and
2
.
2. Discussion of Background
In a power station plant which comprises a gasturbine group, a waste-heat steam generator arranged downstream, and an adjoining steam circuit, it is advantageous to provide a supercritical steam process in the steam circuit in order to achieve a maximum efficiency.
CH-480 535 has disclosed such a circuit. In this circuit, for the purpose of optimum utilization of the waste heat of the gas-turbine group in the lower temperature range of the waste-heat steam generator, a mass flow of the circuit medium of the gas turbine is branched off and utilized recuperatively in the gas turbine. Both the gas-turbine process and the steam process have sequential combustion. However, in the case of modern gas turbines preferably of single-shaft design, this configuration leads to an undesirable complication with regard to construction.
In a plant which has been disclosed and is equipped with an intercooler in operative connection with the compressor unit, a large portion, or even the entire quantity, of the accumulating hot water is directed out of this intercooler into a mixing preheater belonging to the steam circuit. With this measure, excess heat, which causes some of the water to evaporate, develops in the mixing preheater. The steam which is thus produced can then be fed via a line holding the vacuum to a steam turbine in which work is performed. However, such an arrangement has the disadvantage that the large-volume flow path of the low-pressure part of the steam turbine has to be enlarged even further. The work gain of this steam quantity is relatively small; at most it could just be sufficient to compensate for the adverse effect of the intercooler on the efficiency of the power station plant.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention, in a method of the type mentioned at the beginning, is to achieve a substantial increase in the efficiency with regard to output.
For this purpose, only a portion of the hot water from the intercooler is fed to the mixing preheater, while the other portion is fed directly or via a further heating-up means to the gas turbine at a suitable point, preferably upstream of the combustion chambers.
The essential advantage of the invention may be seen in the fact that the steam which is produced by this injection of hot water into the combustion chambers increases the output of at least one turbine of the gas-turbine group and thus directly increases the output delivered to the generator. In addition, this steam which is thus produced increases the exhaust-gas quantity, so that more steam is also generated in the waste-heat boiler. To this end, the feedwater quantity must of course be increased accordingly, with corresponding adaptation of the fuel feeds, so that the injected hot water can evaporate without any problem, and the steam which is thus produced is superheated to the nominal hot-gas temperatures.
It is certainly true that an increase in output can also be achieved by injection of cold water upstream of the combustion chamber of a gas turbine; however, an appreciable reduction in the efficiency is thus traded off, because the water must of course be preheated by fuel and evaporated, which is very unfavorable in terms of energy.
A further essential advantage of the invention may be seen in the fact that, in the case of gas turbines having sequential firing, only the hot water introduced into the first combustion chamber has to be evaporated by fuel and accordingly the steam has to be superheated. When the steam which is thus produced passes through the second combustion chamber, only reheat has to be supplied by fuel there, which is favorable in terms of energy.
In addition, the injection of hot water has a fuel-saving effect by virtue of the fact that the hot water of the intercooler, before its injection, can be heated up further in an economizer, which can still be readily accommodated from the thermodynamic point of view.
Advantageous and expedient developments of the achievement of the object according to the invention are defined in the further claims.
REFERENCES:
patent: 4569195 (1986-02-01), Johnson
patent: 4932204 (1990-06-01), Pavel et al.
patent: 5386685 (1995-02-01), Frutschi
patent: 5884470 (1999-03-01), Frutschi
patent: 6089024 (2000-07-01), Hatanaka
patent: 480535 (1969-12-01), None
patent: 2138664 (1973-03-01), None
patent: 3815993A1 (1989-11-01), None
patent: 4237665A1 (1994-05-01), None
patent: 0081996A2 (1983-06-01), None
patent: 0516995A1 (1992-12-01), None
patent: 2230864 (1974-12-01), None
patent: 1085425 (1967-10-01), None
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Freay Charles G.
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