Power plants – Combustion products used as motive fluid
Reexamination Certificate
1998-11-06
2001-04-03
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
C060S039281, C060S039300
Reexamination Certificate
active
06209310
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of gas turbines. It refers to a method for monitoring the supply system of a gas turbine having a multiburner system, said supply system comprising at least one distribution system, via which a pressurized medium required for operating the multiburner system is distributed to a plurality of individual burners opening into a combustion chamber.
The invention refers, furthermore, to an apparatus for carrying out the method, comprising a plurality of burners which open into a combustion chamber and which are supplied via a fuel distribution system with a pressurized liquid fuel.
2. Discussion of Background
In modern gas turbines which are equipped with low-emission multiburner systems, the fuel is conveyed to the burners or fuel lances via a complex fuel distribution system. The same applies to water which is distributed to the burners via a corresponding water distribution system for the purpose of reducing the NOx emission. A series of switching valves, nonreturn valves and filters, which allow the fuel (water) to be distributed properly to the burners, is installed in the fuel and water lines.
While the plant is being assembled or operated, malfunctions of the fuel or water system may occur. For example, individual nonreturn valves may fail or switching valves may be wrongly activated. Moreover, in many cases, it has been shown, in practice, that impurities in the fuel system lead to the clogging of individual filters or fuel nozzles. In other cases, the regulating valves and fuel nozzles are subject to erosion phenomena due to small solid particles entrained in the fuel.
All the abovementioned irregularities in fuel distribution (or water distribution) lead to an uneven load on the burners and, consequently, to increased thermal load on individual hot gas parts. They thus shorten the lifetime of the gas turbine. It is therefore desirable to have the possibility of detecting malfunctions in the supply systems, in particular in fuel or water distribution, reliably at an early stage and thereby enable the operator of the gas turbine to conduct a clear analysis of the state of his plant.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a novel method, by means of which the supply system of a gas turbine can be monitored in a simple and reliable way and, if deviations occur, relevant countermeasures can be taken early, and to specify an apparatus for carrying out the method.
In a method of the type mentioned initially, the object is achieved in that, while the gas turbine is operating, the pressure loss in the at least one distribution system is measured continuously, in that the measured pressure loss is compared with a desired value characteristic of the respective operating state of the gas turbine, and in that a communication is issued when the measured pressure loss deviates from the associated desired value by a predetermined value. The supply systems of the gas turbine, in particular the fuel systems and fuel nozzles, may be operated in the form of a line-up of appliances having a fixed throughflow. The result of this is that, for any desired load state, there is, for example, a clearly defined fuel pressure loss or necessary fuel pressure. If, then, irregularities occur in the fuel distribution system, the fuel pressures actually measured deviate from the theoretic curve. The method according to the invention makes use of this fact.
A first preferred embodiment of the method according to the invention is distinguished in that, in order to measure the pressure loss in the at least one distribution system, the pressure at the inlet of the distribution system and in the combustion chamber is measured and the pressure difference is formed from the two pressure values, in that the medium to be distributed is fed to the at least one distribution system via a pump and a regulating valve located downstream of the pump, and in that, in order to determine the pressure in the distribution system, the pressure at the outlet of the regulating valve is measured. By selecting the measurement locations, the pressure drop (pressure loss) over the entire distribution system is measured in a simple way, without the constantly changing position of the regulating valve being able to have a noticeable falsifying effect.
In order to obtain in a simple manner a reference curve of desired values which has evidential force, said reference curve making it possible to detect all the changes in the plant during subsequent operation, is desirable if, according to a second preferred embodiment of the method according to the invention, in order to provide the desired values of the pressure loss of the at least one distribution system, the pressure loss in this distribution system is measured and stored for various possible operating states when the gas turbine is first commissioned.
The apparatus according to the invention for carrying out the method comprises a plurality of burners which open into a combustion chamber and which are supplied via a fuel distribution system with a pressurized liquid fuel. Said apparatus is defined in that a pressure transducer is arranged in each case both on the fuel distribution system and on the combustion chamber, and in that the pressure transducers are connected to a common monitoring unit.
A preferred embodiment of the apparatus according to the invention is defined in that the burners are combined in burner groups, in that each burner group is assigned its own fuel distribution system or water distribution system, and in that a pressure transducer is arranged for monitoring in each fuel distribution system or water distribution system and is connected to the monitoring unit.
Further embodiments emerge from the dependent claims.
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Sobey et al.Control Of Aircraft And missile PowerplantsWiley and Sons, New York, 1963. pp. 317&320.
Küenzi Thomas
Muller Gerhard
Asea Brown Boveri AG
Burns Doane Swecker & Mathis L.L.P.
Casaregola Louis J.
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