Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
2002-04-18
2003-06-10
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
C416S24100B
Reexamination Certificate
active
06574966
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a new gas turbine for power generation, which is capable of enhancing the heat efficiency by increasing a turbine inlet temperature up to 1200° C. or more, and a combined power generation system using the gas turbine.
BACKGROUND ART
In recent years, it is expected to improve the heat efficiency of a gas turbine from the viewpoint of energy saving. To improve the heat efficiency of a gas turbine, it is most effective to increase the gas temperature and gas pressure thereof. For example, by increasing the gas temperature from 1200° C. to 1650° C. and also increasing the gas compression ratio to about 15, it is possible to make the heat efficiency larger than that of the conventional gas turbine operated at 1200° C. or less by about 3% or more.
Along with the increases in gas temperature and gas compression ratio, however, it is required to use materials having higher strengths, particularly, higher creep rupture strengths which exert the largest effect on the high temperature characteristics of the materials. In general, an austenite steel, an Ni-based alloy, a Co-based alloy, and a martensite steel are known as structural materials higher in creep rupture strength. Of these materials, the Ni-based alloy and Co-based alloy are undesirable in terms of hot workability, machinability, and vibration damping property; and the austenite steel is also undesirable in terms of poor high-temperature strength at a temperature ranging from 400 to 450° C. and of matching with the entire material configuration of the gas turbine. On the other hand, the martensite steel is desirable in matching with materials of other components of the gas turbine and also sufficient in high-temperature strength. The use of the martensite steel has been known, for example, from Japanese Patent Laid-open Nos. Sho 63-60262 and Hei 5-263657. The martensite steel disclosed in these documents, however, is not necessarily high in creep rupture strength at a temperature ranging from 400 to 500° C., and therefore, it cannot be used as the material as it is for a turbine disk or the like provided in a gas turbine operated at a high temperature.
To meet the requirement to increase the gas temperature and gas pressure of a gas turbine, it is insufficient to use materials which are only high in strength. To be more specific, to cope with the tendency to increase the gas temperature of a gas turbine, it is required to use heat-resistant materials which are high not only in strength but also in toughness. In general, however, if the strength of a material is increased, the toughness thereof is reduced.
Accordingly, it is generally difficult to obtain a martensite steel which is high in both strength and toughness.
An object of the present invention is to provide a gas turbine for power generation, which is improved to increase the heat efficiency and also increase the gas temperature by combination of the use of a material high in both strength and toughness and a technique of cooling the gas turbine, and to provide a combined power generation system of the gas turbine and a steam turbine combined therewith.
DISCLOSURE OF INVENTION
According to the present invention, there is provided a gas turbine for power generation, including a compressor, a combustor, three stages or more turbine blades fixed to turbine disks, and three stages or more turbine nozzles provided in matching with the turbine blades, characterized in that the gas turbine has an air cooling line for cooling the turbine disks in a range from shells of the turbine disks to the turbine blades by using air compressed by the compressor; and the turbine disks are each made from a martensite steel.
According to the present invention, there is also provided a gas turbine for power generation, including a compressor, a combustor, three stages or more turbine blades fixed to turbine disks, and three stages or more turbine nozzles provided in matching with the turbine blades, characterized in that the gas turbine has a steam cooling line for cooling the turbine disks in a range from shells of the turbine disks to the turbine blades by using steam; and the turbine disks are each made from a martensite steel.
According to the present invention, there is also provided a gas turbine for power generation, including a compressor, a combustor, three stages or more turbine blades fixed to turbine disks, and three stages or more turbine nozzles provided in matching with the turbine blades, characterized in that a gas temperature at the inlet of the first stage turbine nozzle is in a range of 1200 to 1650° C.; the gas turbine has an air cooling line for cooling the first stage turbine nozzle and also cooling the first and second stage turbine disks in a range from shells of the first and second stage turbine disks to the first and second stage turbine blades by using air compressed by the compressor and cooled by a cooler; the gas turbine further has an air cooling line for cooling the second and third stage turbine nozzles by using air; and the turbine disks are each made from a martensite steel.
According to the present invention, there is also provided a gas turbine for power generation, including a compressor, a combustor, three stages or more turbine blades fixed to turbine disks, and three stages or more turbine nozzles provided in matching with the turbine blades, characterized in that a gas temperature at the inlet of the first stage turbine nozzle is in a range of 1200 to 1650° C.; the gas turbine has a steam cooling line for cooling the first stage turbine nozzle and also cooling the first and second stage turbine in a range from shells of the first and second stage turbine disks to the first and second stage turbine blades by using steam; the gas turbine further has an air cooling line for cooling the second and third stage turbine nozzles by using air; and the turbine disks are each made from a martensite steel.
The above-described gas turbine for power generation is preferably configured such that the gas temperature at the inlet of the first stage turbine nozzle is in a range of 1200 to 1295° C.; and the martensite steel contains, on the weight basis, 0.05-0.20% of C, 0.15% or less of Si, 1.0% or less of Mn, 0.50-3.0% of Ni, 8.0-13.0% of Cr. 1.0-4.0% of Mo, 0.10-0.40% of V, and 0.025-0.125% of N.
The gas turbine for power generation is also preferably configured such that the gas temperature at the inlet of the first stage turbine nozzle is in a range of 1300 to 1395° C.; and the martensite steel contains, on the weight basis, 0.05-0.20% of C, 0.15% or less of Si, 1.0% or less of Mn, 0.50-3.0% of Ni, 8.0-13.0% of Cr, 1.0-4.0% of Mo, 0.10-0.40% of V, 0.01-0.20% of Nb, and 0.025-0.125% of N.
The gas turbine for power generation is also preferably configured such that the gas temperature at the inlet of the first stage turbine nozzle is in a range of 1400 to 1650° C.; and the martensite steel contains, on the weight basis, 0.05-0.20% of C; 0.15% or less of Si; 0.20% or less of Mn; 0.5-3.0% of Ni, preferably, 0.50-2.50% of Ni; 8.0-13.0% of Cr, preferably, 10.5-12.5% of Cr; 1.0-4.0% of Mo, preferably, 1.7-2.1% of Mo; 0.10-0.40% of V, preferably, 0.15-0.25% of V; 0.01-0.20% of Nb, preferably, 0.06-0.12% of Nb; 0.025-0.125% of N, preferably, 0.025-0.070% of N; and 1.0-5.0% of Co. When the gas inlet temperature is in the above range of 1400 to 1650° C., the temperature of the first stage turbine disk is increased to about 500° C.; however, the first stage turbine disk, which is made from the above martensite steel, sufficiently withstands such a high temperature. Although the temperature of each of the second and third stage turbine disks is slightly lower than that of the first stage turbine disk, it reaches 450° C. or more.
The martensite steel, used in either of the above three temperature ranges, preferably further contains one kind or more of 0.2-2.0% of W and 0.0005-0.010% of B. The above martensite steel can be used for at least one of a distant piece, a turbine spacer, a final stage compressor disk, a turbine stacki
Fujita Toshio
Fukui Yutaka
Hidaka Kishio
Hiraga Ryo
Nakamura Shigeyoshi
Casaregola Louis J.
Mattingly Stanger & Malur, P.C.
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