Power plants – Combustion products used as motive fluid – With combustible gas generator
Reexamination Certificate
2000-03-20
2001-03-27
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
With combustible gas generator
C060S039464
Reexamination Certificate
active
06205767
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an adapter fitting for use in a stationary gas turbine installation having a compressor, a turbine, a combustion chamber and an external pressure-supercharged fluidized-bed furnace, the adapter fitting having:
a housing which can be fitted between a combustion-chamber connection flange and a combined connection flange for process air compressed by the compressor and for flue gas being discharged toward the turbine,
a first line connection at the housing for fitting to the combined connection flange, with an inlet for process air compressed by the compressor and with an outlet for the flue gas, and
a second line connection at the housing for fitting to the combustion-chamber connection flange, with an inlet for the flue gas emanating from the combustion chamber and with an outlet for the process air compressed by the compressor.
Such an adapter fitting is known from an article entitled “Die Standard-Gasturbine im Druckwirbelschicht-Einsatz” [The Standard Gas Turbine in Pressurized Fluidized-Bed Mode] by F. Stuhlmüller et al., in VGB Kraftwerkstechnik (1995), Volume 12, Pages 1037-1042 or from UK Patent Application GB 2 017 219 A.
Conventional gas turbines in which a pressure-supercharged fluidized-bed furnace is used instead of the combustion chamber to generate the hot flue gas are suitable for use in power plants. For that purpose, it is possible to use conventional gas turbine installations with two externally flanged-on combustion chambers. In that case, in order to connect the gas turbines to the pressure-supercharged fluidized-bed furnace system, it is merely necessary to remove the two combustion chambers and replace them with a connection fitting for the fluidized-bed furnace system. That connection fitting may, for example, be a concentric double-tube configuration, in which the flue gas emanating from the fluidized-bed furnace is guided in an inner tube to the gas turbine, while in an outer annular space the compressed process air generated by the compressor of the gas turbine installation is guided to the fluidized-bed furnace system.
The disadvantage of the low turbine inlet temperature of the flue gas in such fluidized-bed systems is eliminated by a further development, in which some of the coal being introduced is gasified, and the low calorific value combustion gas is used for further heating of the fluidized-bed flue gas before it enters the turbine.
In tried-and-tested configurations of such a gas turbine with a pressure-supercharged fluidized-bed furnace, the low calorific value combustion gas is added at a high temperature level, in such a way that the hot flue gases from the pressurized fluidized bed are mixed with compressed air from the compressor outlet of the gas turbine installation and are used as combustion air. The air inlet temperature at those burners is approximately 760° C.
Various problems arise because of that configuration:
High NO
x
levels are to be expected with combustion using hot combustion air.
Difficulties arise with the combustion, on one hand, of natural gas and, on the other hand, of low calorific value coal gas using a single combustion chamber which is operated with a high air inlet temperature.
The fluidized-bed flue gas may entrain ash particles which, upon passing through the flame during the addition of the coal gas, may melt.
Complex hot-gas fittings are required.
It is difficult to protect the gas turbine from running up unintentionally as a result of fluidized-bed flue gases.
The prior art has already developed burner types which are constructed for the combustion of low calorific value synthesis gas using hot combustion air while at the same time achieving acceptable NO
x
emissions. However, the problems of melting ash particles, with the use of complex hot-gas fittings and the heat losses caused by the use of concentric tubes through the cooling of the internally guided flue gas, have remained unsolved.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an adapter fitting for use in a stationary gas turbine installation, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, in a stationary gas turbine installation including a compressor for generating process air, a turbine, a combustion chamber producing flue gas and having a connection flange, and an external pressure-supercharged fluidized-bed furnace producing flue gas, an adapter fitting comprising a combined connection flange; a housing to be fitted between the combustion-chamber connection flange and the combined connection flange for the process air generated by the compressor and for the flue gas discharged toward the turbine; a first line connection at the housing to be fitted to the combined connection flange, the first line connection having an inlet for the process air generated by the compressor and an outlet for the flue gas; a second line connection at the housing to be fitted to the combustion-chamber connection flange, the second line connection having an inlet for the flue gas emanating from the combustion chamber and an outlet for the process air generated by the compressor; a third line connection having an inlet for the flue gas emanating from the fluidized-bed furnace; a fourth line connection having an outlet for discharging compressed process air to the fluidized-bed furnace and/or a coal gasification installation; the compressed process air outlets of the second and fourth line connections jointly communicating with the inlet of the first line connection; closure members for alternately opening and closing the compressed process air outlets of the second and fourth line connections; a flow passage disposed between the burner-side inlet of the second line connection for the flue gas and the outlet of the first line connection leading to the turbine; and at least one closure member to be opened and closed, the at least one closure member connecting the flow passage to the inlet of the third line connection for the flue gas emanating from the fluidized-bed furnace, for mixing the flue gas emanating from the fluidized-bed furnace with the combustion-chamber flue gas.
The inventive structure of this adapter fitting allows conventional gas turbines with external combustion chambers to be used. In this case, the adapter fitting is fitted between the gas turbine itself and the corresponding combustion chamber.
As a result of the connection provided between the inlet for the flue gas emanating from the fluidized-bed furnace or firing and the flow passage between the burner-side inlet for the burner flue gas and its outlet leading to the turbine, it is possible to add hot flue gases from the fluidized-bed furnace downstream of the combustion chamber. Therefore, the flue gases from the fluidized-bed furnace do not pass through the flame in the combustion chamber, thus substantially preventing ash particles which may be entrained in the fluidized-bed flue gases from melting.
As a result of the inlet-side guidance of the compressed process air, this air is fed directly to the combustion chamber. Therefore, it is possible to operate with low air inlet temperatures of the combustion air corresponding to the compressor outlet temperature of approximately 400° C. to 420° C. This significantly reduces the NO
x
emissions when using burners of standard construction.
The inventive structure of the adapter fitting also allows compressed process air to be discharged simultaneously to the fluidized-bed furnace and/or a coal gasification installation, with the result that there is no need for independent installation components for supplying process air to these components.
In accordance with another feature of the invention, the housing is constructed substantially as a dish with an outer wall, a base, a cover and a concentrically disposed annular insert.
In accordance with a further feature of the inv
Casaregola Louis J.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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