Method and apparatus for achieving a high efficiency in an open gas-turbine (combi) process

Abstract

Method and apparatus for achieving high efficiency in an open gas-turbine process, in which a supercharger compresses air, which is burned together with a fuel in a first combustion chamber, which is followed by a first turbine, a second combustion chamber, a second turbine, and a preheating heat exchanger, in which primary bleed water vapor coming from the secondary process, or a mixture of the aforementioned water vapor and air coming from the supercharger are preheated. From the heat exchanger the combustion gases go to a waste-heat boiler, in which the secondary-process feed water is vaporized. The combustion gases are expanded in the second turbine to a pressure 0.5 bar lower than that of the surrounding atmospheric pressure. The remaining combustion gases are compressed by a combustion-gas supercharger to the surrounding atmospheric pressure. After the low-pressure turbine the water vapor is condensed in a condenser into water, which is compressed by a pump to a maximum pressure and is preheated and vaporized in the waste-heat boiler. After the waste-heat boiler the water vapor goes to a combined high / medium-pressure turbine, from which a secondary-process primary bleed is taken, which is injected into the gas-turbine process after the preheating heat exchange after the supercharger and / or at the latest to the start of the blades of the first turbine.

Description

FIELD OF INVENTION[0001]The invention relates to a method and apparatus for achieving a high efficiency in an open gas-turbine (combi) process.BACKGROUND OF INVENTION[0002]In existing gas-turbine combi processes, a supercharger compresses air, which is burned with fuel in a combustion chamber, which is followed by a turbine and a waste-heat boiler, in which water of the secondary-process circulation is vaporized. In the secondary-process circulation there is normally a vapor process, which, in the newest large plants, uses reheating of the water vapor. In the secondary process, after a low-pressure turbine, the water vapor condenses in a condenser into water, which is compressed by a pump to a maximum pressure, and preheated and vaporized in the waste-heat boiler. After the waste-heat boiler, the water vapor goes to the steam turbines of the process circulation.[0003]Using natural gas as the fuel, electricity is nowadays generally produced in a combined gas-turbine-steam power-plant...

AI Technical Summary

Benefits of technology

The patent claims that while the desired pressure for a certain process is 0.5 bar, it is more efficient to set the pressure to 0.2 bar. This change in pressure allows for better efficiency because it allows the water vapor that is created during combustion to cool down into liquid at a lower pressure than what the atmosphere currently has. This reduces energy loss and makes the process more effective.

Problems solved by technology

In existing combi processes incorporating two combustion chambers, a higher efficiency is not achieved.

The reason for this is not easy to determine, but closer investigation of the matter shows that the energy loss of the waste-heat boiler is great, because the exhaust temperature of the combustion gases after the second combustion chamber is high.

In addition, this US patent in question does not have a steam-turbine process.

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