JPH09170402A - Nozzle for gas turbine and manufacture thereof, and gas turbine using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a casting property and heat resisting strength by composing an integrated type gas turbine nozzle having a monocrystal structure at one end of each of its blade part and side wall part, and having a columnar crystal structure solidified in one way or an eqiaxed crystal structure at a contiguous part from the monocrystal structure part. SOLUTION: In a nozzle of a gas turbine for power generation, an internal cooling structure from a cooling air inlet 4 to a cooling hole 5 is an insert type composed of silica as its main gradient, and casting is implemented using same. The nozzle is provided with a blade part 1 subjected to high temp./ pressure gas and side walls 2, 3 at both ends of the part 1, and is composed of an integrated casting, wherein especially, one end of each of the part 1 and the side wall 2 has a monocrystal structure, while a part of the portion except the one end of them has a monocrystal being contiguous from the monocrystal part, and the rest has a columnar crystal structure being solidified in one way in a continuous manner from the monocrystal structure. It is thus possible to improve high temp. strength and manufacture characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel gas turbine nozzle excellent in creep strength at high temperature and heat fatigue resistance, and further to a high efficiency gas turbine and a combined cycle power generation system using the nozzle.

[0002]

2. Description of the Related Art Ni is used in the nozzle of a power generation gas turbine.
Commonly cast base- or Co-base superalloys have been widely used, and recently, as the combustion gas temperature rises for the purpose of improving power generation efficiency, nozzles having cooling holes inside have become the mainstream. There is. However, increasing the amount of compressed air used for cooling to enhance internal cooling in response to the rise in combustion gas temperature may rather lead to a decrease in power generation efficiency. Since the thermal stress increases as the temperature difference between the insides increases, it is not possible to cope with the rise in the combustion gas temperature above the current level only by strengthening the internal cooling. Therefore, there is a need for a material having higher heat resistance than the above-mentioned Ni-based or Co-based superalloy ordinary cast products.

The above Ni-based ordinary casting alloy for nozzles is the alloy shown in US Pat. No. 4,039,330 or US Pat. No. 4,810,467, and the Co-based ordinary casting alloy for nozzles is US Pat. No. 3,383,205. The alloys and the like shown in the official gazette or Japanese Patent Laid-Open No. 3-215644 are mentioned.

[0004]

Ni for conventional nozzles
Materials having higher heat resistance than ordinary cast base- or Co-base alloys include Ni-base superalloy columnar and single crystal materials used in the blades or nozzles of aircraft gas turbines.

The columnar crystal material of Ni-base superalloy is mainly manufactured by the directional solidification method shown in US Pat. No. 3,260,505. This method is a method in which a mold is pulled out from a heated furnace and gradually solidified from the lower end. By this method, the creep stress can be improved by making the principal stress direction parallel to the crystal grain boundary direction.

This columnar crystal material is cast from the alloys shown in JP-A-56-108852, JP-A2-153037 and JP-A-3-97822. However, these conventional alloys for columnar crystals use B, C, and
It contains a large amount of grain boundary strengthening elements such as Zr and Hf.
These crystal grain boundary strengthening elements improve the strength of the crystal grain boundaries, but some segregate between the dendrite arms, and significantly lower the melting point of the segregated portion. Therefore, the conventional alloy for columnar crystals cannot increase the solution heat treatment temperature and the solution treatment is insufficient, so that the heat resistance strength cannot be significantly improved. Further, the cooling hole of the gas turbine nozzle is formed by using a ceramic core, but the molten metal is solidified in a state in which the core is cast, and then cooled to room temperature. Comparing the thermal expansion coefficients of the core and the alloy, the core shows a value that is about an order of magnitude smaller than that of the metal, so the alloy will contract around the core that does not shrink much, and a large tensile stress will be generated during the cooling process. Solidification cracks are likely to occur along the weak grain boundaries. This solidification cracking is remarkable in the thin blade portion to enhance the cooling effect, and the solidification cracking is more likely to occur in the nozzle of the gas turbine for power generation, which is larger than that for aircraft, and the yield deteriorates.

On the other hand, as a material having significantly improved heat resistance, there is a Ni-base superalloy single crystal material manufactured by the method disclosed in US Pat. No. 3,494,709. Has been applied to. As an alloy used for this, JP-A-58-63212, Japanese Patent Publication No.
There are alloys shown in Japanese Patent Publication No. 2-45694 and Japanese Patent Publication No. 3-75619, etc., but these all handle the grain boundary strengthening element as an impurity element, and since the content is minimized, the melting point of the segregation part is Rises, enabling complete solution heat treatment. Therefore, this single crystal alloy has a higher heat resistance strength of 40 to 50 ° C. than the columnar crystal alloy. However, since the alloys for single crystals have the grain boundary strengthening elements reduced as much as possible, the crystal grain boundaries are very weak, and if there are different crystals with different crystal orientations, cracks easily occur at the crystal grain boundaries. Usually, if there is a grain boundary, it becomes weak enough to cause cracking only by cooling after casting. Therefore, it is necessary for the nozzle cast using the alloy for single crystals to be a complete single crystal without foreign crystals. However, a gas turbine for power generation is larger than that for an aircraft, and it is very difficult to form a completely single-crystal nozzle having a complicated shape.

As described above, in the conventional columnar crystal nozzle, solidification cracking is likely to occur when the blade portion is thinned in order to enhance the cooling effect, and a large amount of grain boundary strengthening elements is used to prevent solidification cracking. When added, there was a drawback that the strength could not be improved, and the efficiency of the gas turbine could not be improved.

Further, the single crystal nozzle excellent in high temperature strength is
Since large crystals with a complicated shape are likely to produce foreign crystals, the yield is poor and it cannot be applied as a nozzle of a gas turbine for power generation, so that the efficiency of the gas turbine could not be improved.

An object of the present invention is to provide a gas turbine nozzle excellent in castability and heat resistance, a method for manufacturing the same, and a gas turbine using the same.

[0011]

Means for Solving the Problems The present invention was obtained as a result of studying the material composition capable of solution heat treatment at high temperature and having sufficient grain boundary strength as a gas turbine nozzle and the crystallinity of the gas turbine nozzle. It has been done.
The present invention is a gas turbine nozzle having a blade exposed to high-temperature and high-pressure gas and a sidewall that is a connecting portion at both ends of the blade, wherein one end of the blade and the sidewall is a single crystal. A gas turbine made of an integral casting in which a part of a portion excluding one end of the blade and the side wall is a single crystal continuous from the single crystal part, and the rest is a columnar crystal continuously unidirectionally solidified from the single crystal. It has become clear that a gas turbine nozzle that has both high temperature strength and manufacturability that have never been obtained can be obtained. In particular, the present invention can allow the orientation difference between the crystal grains to be within 8 degrees in the part of the wing portion and the side wall and to be 20 degrees in the remaining portion.

The sidewalls, which are the connecting portions, are usually on both sides of the blade portion in the first stage turbine, but may be on only one side in the second and subsequent stages. In this case, by forming the nozzle into an integral casting in which the wing portion is a single crystal and the rest is a columnar crystal continuously unidirectionally solidified from the single crystal, high temperature strength and manufacturability that have not been obtained in the past can be obtained. A combined gas turbine nozzle can be obtained.

The most important high temperature strength of the gas turbine nozzle is the blade. In addition, it is difficult to single crystallize a protrusion such as a sidewall. Therefore, a part or all of one end of the sidewall is a single crystal, the wing portion is a single crystal continuous from the single crystal portion of the one end of the sidewall, and the wing portion and the one end of the sidewall are excluded. A nozzle for a gas turbine, which is composed of a single crystal that is partially continuous from the single crystal portion or a columnar crystal that is unidirectionally solidified continuously from the single crystal, is preferable in terms of high temperature strength and manufacturability. Further, a part or all of one end of the sidewall is a columnar crystal in which the orientation difference between the adjacent crystal grains is within 8 degrees, and the wing portion has the orientation difference between the adjacent crystal grains in the sidewall within 8 degrees. The columnar crystals are unidirectionally solidified continuously from the columnar crystals of which the orientation difference between adjacent crystal grains is within 8 degrees, and a part of a portion excluding one end of the wing portion and the sidewall is the columnar crystal portion. The same applies to a nozzle for a gas turbine, which is composed of an integral casting made of columnar crystals in which the azimuth difference between adjacent crystal grains that are continuously unidirectionally solidified from is within 20 degrees.

That is, the blade portion must be a columnar crystal having an orientation difference of 8 degrees or less between adjacent crystal grains or, more preferably, a perfect single crystal in view of high temperature strength and prevention of grain boundary cracking in the thin portion. However, the strength of the wing is not required, and the other thicker parts have a difference in orientation between adjacent crystal grains of 2
It may be columnar crystals within 0 degree. Furthermore, it is possible to form equiaxed crystal depending on the part.

When a gas turbine nozzle having sidewalls at both ends is solidified in the direction from the sidewall at one end to the other sidewall, part or all of the sidewalls at the chill plate side and the blade portion are made of a single crystal. After that, in order to make a part or all of the sidewall on the side of the final solidified portion to be the overhanging portion a single crystal continuous from the single crystal portion, at least one portion of the single crystal portion and the final solidified portion are formed. It is effective to provide a solidification promoting passage between the side walls. This solidification promoting passage is effective in preventing casting defects such as shrinkage cavities even when the side wall on the final solidification portion side is not single-crystallized. In the gas turbine nozzle in which the sidewall is provided only at one end of the blade portion, the solidification promoting portion is provided between the sidewall or the single crystal expansion portion between the selector and the blade portion and the sidewall.

Thermal fatigue resistance is important in a gas turbine nozzle. This is because in a gas turbine nozzle having both ends constrained by sidewalls, compressive stress acts in the direction perpendicular to the sidewalls of the blades during operation, and tensile stress acts in reverse when operation is stopped. In order to solve this, at least only the wings are single-crystallized,
Three <100> perpendicular to each other in the wing
A gas turbine nozzle in which one of the directions is grown in a direction perpendicular to the longitudinal direction of the sidewall and the other is grown in a direction parallel to the longitudinal direction of the sidewall is effective. This is because the Ni-based superalloy has the smallest Young's modulus in the <100> direction, so the direction in which the largest thermal strain occurs is <10
This is because if it is set to the 0> direction, the thermal stress in that direction can be reduced. In order to control the crystal orientation, a seed crystal composed of a single crystal whose crystal orientation is controlled in advance is usually used for the starter.

Usually, when a single crystal is cast using a plurality of seed crystals, the interfaces of the crystals grown from the respective seeds become grain boundaries, and the strength decreases. However, in the gas turbine nozzle of the present invention, the azimuth difference between adjacent crystal grains is 8 ° in the blade portion.
It is possible to manufacture an integral casting from a plurality of seed crystals, since up to 20 ° can be tolerated in other parts. Therefore, in order to single crystallize the two sidewalls that largely overhang from the blade, the solidification direction is either from the gas inlet side of the blade to the gas outlet side or from the gas outlet side of the blade to the gas inlet side. By unidirectionally solidifying the sidewalls by using different seed crystals, it becomes possible to single crystallize as many portions as possible including the wings. Further, also in a gas turbine nozzle having a plurality of blades in a single casting, it is possible to make a plurality of blades into single crystals by using two or more seed crystals.

In the gas turbine nozzle of the present invention, the blade surface may be coated with an alloy layer containing Cr, Al, and Y, which has excellent corrosion resistance, with one or both of Co and Ni as the balance. Further, in the gas turbine nozzle of the present invention, a thermal barrier coating made of a ceramic layer may be applied to the outermost surface of the blade portion and its periphery.

The gas turbine nozzle of the present invention can improve the high temperature strength by the solution treatment and can allow the presence of grain boundaries in a part or all other than the blade portion. This means that by weight%, Cr2 to 25%, Al4 to 7%, W2 to
15%, Ti 0.5-5%, Nb 0-3%, Mo 0-6
%, Ta 1-12%, Re 0-4%, Co 7.5-25
%, Fe 0.5% or less, C 0.20% or less, B 0.002
~ 0.035%, Hf0 ~ 2.0%, Zr0.02% or less,
And N containing 40% or more, preferably 45 to 85% Ni.
This is possible in castings that are i-based alloys.

In particular, in order to carry out a sufficient solution treatment without substantially causing the initial melting, the grain boundary strengthening element is C0.02% or less, B0.002-0.035%, Hf.
1 to 1.1% and Zr 0 to 0.02%, and the amounts of C and B are A (C 0.10%, B 0.002%), B (C0
%, B0.01%), C (C0%, B0.035%), D
It is preferably in the range of (C 0.1%, B 0.035%).

Prevention of intergranular cracking during casting, creep strength,
Gas turbine nozzles that have well-balanced properties of heat fatigue resistance, corrosion resistance, and oxidation resistance have a C
r6.0-9.0%, Al5-6%, W7-10%, Ti
0.5-1%, Mo 0.3-0.7%, Ta 2.5-5.0
%, Re0 to 3.2%, Co8 to 10.5%, C0.03 to
0.1%, B 0.002-0.035%, Hf 0.3-1.
A Ni-based alloy containing 8%, Zr 0.02% or less, and 60% or more, preferably 65 to 70% Ni is suitable.

The gas turbine nozzle according to the present invention can be used for any gas turbine having three or four stages of turbines, but in particular, the metal temperature is the highest and is restrained by the sidewalls at both ends. Therefore, it is suitable for the nozzle of the first-stage turbine which is subjected to a large thermal stress load. From the second stage onward, columnar crystals or equiaxed crystals are often used as a whole.

The nozzle for a gas turbine of the present invention is subjected to solution heat treatment for 2 to 60 hours within a range from the solid solution temperature of the precipitated γ'phase of the alloy after casting to the initial melting temperature, and further 900 to 1150.
The heat treatment is preferably performed at 4 ° C. for 20 to 20 hours and at 760 to 900 ° C. for 8 to 100 hours.

The gas turbine nozzle of the present invention comprises the steps of setting a mold for forming the nozzle on a water-cooled chill plate, heating the mold to a predetermined temperature in a vacuum heating furnace, and casting. A step of melting the raw material in the same vacuum chamber as the mold and casting the molten metal into the heated mold, and pulling out the mold containing the molten metal from the heating furnace,
At least only the wing portion is a single crystal, and a part of the portion other than the wing portion is a unidirectionally solidified single crystal continuous with the wing portion or a columnar crystal continuously unidirectionally solidified with the single crystal. It is cast in the casting process.

The above-mentioned drawing speed of the mold is preferably set to 15 cm / h or less in the production of the single crystal, and if it is confirmed that the blade portion is single-crystallized, the drawing speed is set to 20 to 45 cm / h in the rest. be able to. They are,
The earlier each can be manufactured, the better, but from the viewpoint of yield, about 10 cm / h is preferable for manufacturing a single crystal. Further, regarding the remaining columnar crystals, when it exceeds 50 cm / h, the difference in crystal orientation between the columnar crystals exceeds 20 ° and further becomes an equiaxed crystal. In order to obtain a good columnar crystal having a crystal orientation difference of 20 degrees or less, it is not preferable that the extraction speed is too slow, and preferably 30 to 45 cm / h.

According to the present invention, at least the blade portion is a single crystal, the high temperature strength can be improved by solution heat treatment, and the existence of crystal grain boundaries in a part or all of the portion other than the blade portion can be allowed to exist. However, as a result, the entire nozzle may be a single crystal. Further, the nozzle of the present invention is characterized by being made of an integral casting. That is,
The entire casting is made by remelting one master ingot and continuously solidifying in one direction from the chill plate to the final solidification part, and discontinuous solidification, that is, generation of equiaxed crystals, etc. is suppressed as much as possible. Is preferable from the viewpoint of high temperature strength. In the present invention, by changing the shape of the solidification interface,
Columnar crystals are generated from the single crystal part. The shape of the solidification interface is
It can be controlled by changing the mold withdrawal speed, mold heating temperature, casting cross section and mold cross section. The columnar crystals obtained by this method are good columnar crystals in which the crystal orientation difference between adjacent columnar crystals is 20 ° or less. The present invention is characterized in that columnar crystals having a small difference in orientation from the single crystal part can be obtained and a complicated joining process is not included. Further, if the composition of the present invention,
Since the crystal orientation difference between adjacent columnar crystals can be made larger than that of a normal single crystal alloy, it is possible to relax the limitation of the above-mentioned triaxial orientation difference, and to obtain a high-strength nozzle by performing solution heat treatment. It is possible.

A second aspect of the present invention is a gas turbine for driving a generator by burning air compressed by a compressor in a combustor and rotating a turbine disk with the combustion gas, wherein the gas turbine has three or more stages. The first stage nozzle of the turbine has a blade portion exposed to high temperature and high pressure gas, and a sidewall that is a connecting portion at both ends of the blade portion, and a part or all of one end of the sidewall is A single crystal, the wing portion is a single crystal continuous from the single crystal portion at one end of the sidewall, part or all of the portion except the one end of the wing portion and the sidewall from the single crystal portion A gas turbine characterized by comprising a continuous single crystal or an integral casting which is a columnar crystal continuously unidirectionally solidified from the single crystal.

The present invention is particularly applicable to the combustion gas temperature in the combustor.
500 ° C or higher, 1300 ° C or higher at the inlet of the first-stage turbine, and the first-stage nozzle of the turbine has a blade width of 70 mm.
It is suitable for the high temperature and large capacity gas turbine for power generation as described above. This is because the larger the gas turbine, the more difficult it is to single crystallize the entire nozzle, and the conventional columnar crystal nozzle lacks high-temperature strength, and cannot cope with the high temperature of the gas turbine.

A fourth aspect of the present invention is directed to a gas turbine driven by high temperature and high pressure combustion gas, an exhaust heat recovery boiler for generating high pressure steam by combustion exhaust gas of the gas turbine, and driven by the high pressure steam. In a companded cycle power plant including a steam turbine and a generator driven by the gas turbine and the steam turbine, the gas turbine has three or more stages of turbines, and the combustion gas temperature is 1500 ° C. in a combustor. Above, 1300 ℃ or more at the inlet of the first stage turbine, 56 at the outlet of the final turbine
The temperature is 0 ° C. or higher, the temperature of the steam obtained in the exhaust heat recovery boiler is 530 ° C. or higher, the steam turbine is a high-low pressure integrated type, the power generation capacity of the gas turbine is 50,000 KW or higher, and the power generation of the steam turbine is The capacity is 30,000 kW or more, the total power generation efficiency of the entire plant is 45% or more, the first-stage turbine nozzle of the gas turbine has a blade width of 100 mm or more, and the blade portion exposed to high-temperature high-pressure gas, and the blade portion. Has a sidewall that is a connecting portion at both ends, a part or all of one end of the sidewall is a single crystal, and the wing portion is a single crystal continuous from a single crystal portion at one end of the sidewall, A part or all of a portion excluding one end of the wing portion and the sidewall is made of a single crystal that is a single crystal that is continuous from the single crystal portion or a columnar crystal that is unidirectionally solidified continuously from the single crystal, The above Things the foregoing is used.

The nozzle of the gas turbine is used in a gas at a temperature above the melting point of the Ni-base superalloy. Therefore, the nozzle normally introduces a part of the compressed air of the compressor into the nozzle and is cooled so that the surface temperature of the nozzle becomes about 1000 ° C. or less. In this case, the air further flows out in layers from the holes provided on the blade surface to cool the surface. Furthermore, it is possible to cool the nozzle with higher cooling efficiency by using a medium having a larger specific heat than air. in this case,
Since the cooling medium is circulated and used in the closed cooling passage, the nozzle has no cooling holes other than the inlet and the outlet of the cooling medium. This cooling method is called a closed cooling method, and steam is often used as a cooling medium. In this closed cooling system, the leakage of the cooling medium to the outside leads to a significant decrease in efficiency. With conventional nozzles,
Since it is not a rotating body, it has been designed to allow the existence of cracks. However, in the nozzle of the present invention, the blade portion is made into a single crystal, and the direction in which the thermal fatigue is severer is aligned with the <100> orientation in which the thermal stress is the smallest, so that the thermal fatigue resistance is excellent and cracks are generated. Hard to occur. Therefore, it can be said that the nozzle of the present invention is suitable for a closed cooling type gas turbine.

In the gas turbine nozzle according to the present invention, the blade portion is a single crystal, and a part other than the blade portion is a unidirectionally solidified columnar crystal,
The difference in crystal orientation between adjacent crystal grains in the columnar crystal portion was made as small as possible, and particularly the difference was within 20 °. Therefore, it is possible to fabricate a healthy columnar crystal blade in which vertical cracks do not occur in the columnar crystal part during solidification even though the addition amount of the grain boundary strengthening element is reduced to enable solution heat treatment. Becomes

A further important point in the present invention is that the optimum addition amount of the grain boundary strengthening element was found in the gas turbine nozzle having the above-described controlled crystal orientation difference between adjacent crystal grains. . This optimum addition amount prevents solution cracking during solidification, and a solution heat treatment for solid-solutioning about 50% by volume or more of the precipitated γ'phase in the γ phase without causing initial melting of about 5% or more. In the prior art of enabling it, the contradictory problems are simultaneously solved. As a result, a gas turbine nozzle having a high yield and a high creep strength can be obtained. here,
If the difference in crystal orientation exceeds 20 degrees, the strength of the single crystal becomes 10
Not only does the creep strength decrease to about 50%, but vertical cracks easily occur at the crystal grain boundaries during solidification, resulting in a significant decrease in yield. When the initial melting amount exceeds about 8% by volume, the creep strength is not improved and the thermal fatigue resistance is significantly deteriorated even if about 50% by volume or more of the precipitated γ'phase is dissolved in the γ phase. .

An alloy containing the grain boundary strengthening element described above,
Of course, it is also possible to make the entire nozzle a single crystal. This nozzle is inferior in creep strength at high temperature compared to that cast with a single crystal alloy that does not contain a grain boundary strengthening element, but the orientation difference between adjacent crystal grains is high except for the surface of the blade where the temperature becomes high. Since it can be up to 20 °, it is possible to greatly simplify the crystal orientation measurement by X-ray, which was necessary in the conventional single crystal blade. Further, there is no effective inspection means for crystal defects inside the blade, and normally the blade is cut and inspected by a sampling test. However, with a nozzle for a power generation gas turbine, which has a large blade, it is difficult to secure reliability in a sampling test, which has been a major obstacle in applying the single crystal nozzle to a power generation gas turbine. However, in the present invention, since the misorientation between the adjacent crystal grains can be allowed up to 20 ° except for the blade portion, the reliability of the nozzle can be significantly improved, and the high-strength nozzle can be applied to the gas turbine for power generation. It was

In the present invention, the optimum addition amount of the grain boundary strengthening element was determined as shown below.

Hf has the effect of preventing vertical cracking during solidification and improves the ductility of grain boundaries at high temperatures. But,
Excessive addition markedly increases the amount of eutectic tissue formed during solidification and makes effective solution heat treatment impossible, so the maximum addition amount is limited to 2.0% or less. Since part of the effect of Hf can be substituted with Zr or B, it is possible to add no Hf, but it is preferable to add 0.1 to 1.1% of Hf.

B and Zr are the most effective elements for preventing vertical cracks during solidification and improving the high temperature strength of crystal grain boundaries, and the effect appears from several tens of ppm. However, both Ni
And eutectic with a low melting point are formed, and the solid solubility limit with respect to Ni is extremely small, so the addition amount is severely limited. The proper addition amount is B: 0.002 to 0.035%, Zr: 0.0.
It is at most 02%.

C forms carbides and improves the high temperature strength of grain boundaries. However, if added excessively, a large amount of unnecessary carbides will be generated in the crystal grains, and the high temperature strength will be rather deteriorated. Therefore, the addition amount is limited to 0.20% or less, and preferably 0.03 to 0.1%.

Some of the effects of B and C on the grain boundaries are common, and synergistic effects are required. From this, from the viewpoint of prevention of vertical cracks during solidification, availability of effective solution heat treatment, and high-temperature strength, the relationship between the C content and the B content is A (C
0.10%, B0.002%), B (C0%, B0.01)
%), C (C0%, B0.035%), D (C0.1%,
B0.035%) is preferable.

Ni constituting the gas turbine rotor blade of the present invention
The effects of other elements contained in the base superalloy are shown below.

Co dissolves in the matrix to improve the high-temperature strength and contributes to the improvement of the corrosion resistance. However, if added in excess, it promotes the precipitation of harmful intermetallic compounds, resulting in a decrease in the high-temperature strength. Therefore, the addition amount is set to 7.5 to 25% or less, particularly preferably in the range of 7.5 to 10.5%, and the optimum addition amount is 8 to 10.5%.

Cr is an essential element for improving the corrosion resistance, but if added in excess, harmful intermetallic compounds are precipitated,
The high temperature strength is significantly reduced. Therefore, the addition amount is 2 to 2.
It is set to 5% or less, particularly preferably in the range of 2 to 16%, and the optimum addition amount is 6 to 9%. Al and Ti are the strengthening factors of the Ni-based superalloy, that is, γ'phase, that is, Ni ₃ (Ai, Ti)
Is an essential element for precipitating, and to obtain sufficient high temperature strength as a nozzle material for a gas turbine for power generation,
It is necessary to add Al: 1 to 7% and Ti: 0.5 to 5%. Furthermore, it is desirable that Al: 4 to 7% and Ti: 0.5.
~ 5%, the most preferred range is Al: 5-6%, T
i: 0.5 to 1%.

Nb and Ta form a solid solution in the γ'phase, which is a precipitation strengthening phase, and contribute to the improvement of high temperature strength. However, if added in excess, they segregate at grain boundaries and rather lower the high temperature strength. The addition amount is Nb: 3% or less and Ta: 1 to 12%.
The preferable range of Ta is 2.5 to 5%.

W, Mo and Re solidify the γ phase of the matrix by solid solution and are particularly effective in improving the long-term strength. However, if added excessively, intermetallic compounds, W, Mo and R
e leading to the precipitation of the primary solid solution, which rather reduces the high temperature strength. Therefore, the addition amount is W: 2 to 15%, M
o: 6% or less, Re: 4% or less, especially W: 7 to 10
%, Mo 0.3 to 0.7% or less, Re: 0 to 3.2% is preferable.

[0044]

Embodiment 1 FIG. 1 is a perspective view of a gas turbine nozzle for power generation according to the present invention. Cooling air inlet 4 to cooling hole 5
FIG. 2 is a plan view of a core containing silica as a main component, and casting is performed using the internal cooling structure up to.
The core is removed with an alkaline solution after casting.

FIG. 3 is a schematic view of an apparatus for showing a manufacturing method for solidifying the nozzle of the present invention from the inner peripheral side to the outer peripheral side. The same apparatus can be used to solidify from the outer peripheral side to the inner peripheral side. First, the ceramic mold 16 whose main component is alumina is fixed on the water-cooled copper chill plate 11. It is heated in the mold heating furnace 18 to a temperature above the melting point of the Ni-based superalloy. Next, the alloy was melted in the melting furnace 19, the molten metal was cast into the ceramic mold 16, and after holding for about 5 minutes, the water-cooled copper chill plate 11 was pulled out downward from the mold heating furnace 18 to solidify the alloy in one direction. . In unidirectional solidification, many crystals are first generated in the starter 12, and then only one crystal is selectively grown by the selector 13, and the portion above the selector is made into a single crystal. This single crystal is enlarged by the enlarged portion 14, but in the present embodiment, since there is a large overhang portion in the direction perpendicular to the solidification direction, a plurality of these enlarged portions were provided. As a result, the sidewall 2 can be made into a complete single crystal as shown in FIG. 4, but columnar crystals may exist in a part shown in FIG. Furthermore, in some cases, equiaxed crystals were present at the ends of the sidewall 2 shown in FIG. In the figure, SC is a single crystal and DS is a columnar crystal. The ratio is about 50% for completely becoming a single crystal and about 3% for the presence of equiaxed crystals. When the alloys shown in Table 1 are used, in the nozzle, even if columnar crystals are present in the sidewall, there is no serious problem in strength. Also, depending on the operating conditions of the actual machine, the presence of equiaxed crystals in the sidewall may not cause a problem. In this case, it is possible to omit the parts other than the enlarged part connected to the wing part, but it is easy to cause a hollow at the end of the sidewall 2, so it is preferable to provide a plurality of enlarged parts in terms of yield. In the side wall 3 on the outer peripheral side, it is relatively easy to form a single crystal or columnar crystal in which the central portion is unidirectionally solidified continuously from the blade portion. However, in order to make the overhanging portion of the sidewall 3 a single crystal or a columnar crystal, it is effective to provide the solidification promoting passage 15 as shown in FIG.

[0046]

[Table 1]

In the present invention, this is used not only for single crystallizing the overhanging portion but also for columnar crystallizing. Therefore, the starting point of the solidification promoting passage may be not only the single crystal portion but also the columnar crystal portion. In this embodiment, a plurality of solidification promoting passages are provided from the single crystal portion or columnar crystal portion of the sidewall 2 on the chill plate side to the projecting portion of the sidewall 3. As a result, the entire sidewall 3 can be made into a single crystal or a columnar crystal with a yield of about 80% or more. As described above, with the alloys shown in Table 1, even if the side wall 3 is a columnar crystal, it has a strength that does not cause a problem in operation in an actual machine. In this embodiment, the sidewall 2
Approximately 5% of the entire nozzles, including the end portions of 3 and 3, were completely single crystals. This result indicates that the yield is about 5% when the alloy for exclusive use of the single crystal is used. In this example, the yield is improved by using the alloy containing the grain boundary strengthening element shown in Table 1. I could improve to about 70%. The above crystallinity is 100% hydrochloric acid:
It was confirmed by macro etching with an etching solution of 100% hydrogen peroxide solution = 9: 1.

The mold heating furnace 18 is a ceramic mold 1.
6 was fully drawn out and kept hot until the solidification was complete. Further, all the melting and solidifying steps were performed in vacuum. Table 2 shows the casting conditions. The mold heating temperature is the mold 16
The measurement was performed by inserting a thermocouple into the portion corresponding to the wing portion 1 in the. In order to facilitate solidification in one direction, the heating furnace 18 has a two-stage heating system, and further, a partition plate and a spiral water-cooled copper pipe are installed in the lower part to increase the temperature gradient at the solidification interface. .

The length between the sidewalls of the blade portion 1 of the nozzle of this embodiment is about 100 mm.

[0050]

[Table 2]

Example 2 Using the alloys shown in Table 3, a gas turbine nozzle for power generation was cast according to the method shown in Example 1. As shown in FIG. 4, in this nozzle, the wing portion 1 and the sidewall 2 were completely single crystals, and in the sidewall 3, there were some columnar crystals in which the orientation difference between adjacent crystal grains was within 20 °. . Further, no casting crack along the crystal grain boundary was observed.

The above nozzle was placed in a vacuum at 1250-12
The solution heat treatment was performed at 80 ° C. for 4 to 12 hours. By this heat treatment, the coarse precipitation γ ′ phase in the region of 50 to 90% by volume could be solutionized without causing the initial melting of 5% or more. After solution heat treatment, 1000-1150
A two-step aging heat treatment was performed at 2 ° C. for 2 to 10 hours and at 800 to 950 ° C. for 4 to 50 hours to deposit a fine γ ′ phase having a grain size of about 0.5 μm in the region where the γ ′ phase was solutionized. The azimuth difference between the stress axis and the <100> direction is 10 ° from the blade of this nozzle.
2.5mm in thickness, 4mm in width and 2 in parallel section length
A 00 mm plate-shaped test piece was sampled and the creep strength of the nozzle was evaluated.

FIG. 7 is a diagram showing the relationship between the creep rupture time of the solution-treated nozzle and the γ'phase, which is about 1.5 to 2.5 times that of the nozzle without solution heat treatment. Improved.

[0054]

[Table 3]

Since the conventional casting method for columnar crystals could not control the crystal orientations of the columnar crystals in the direction perpendicular to the growth direction, the grain boundary with a large orientation difference (about 20 ° or more) between adjacent crystal grains. Therefore, grain boundary cracking occurred during casting, and the yield was poor. In the method of the present invention, by making the solidification start portion a single crystal, to grow a columnar crystal using this single crystal as a seed,
Even in the columnar crystal portion, the orientation difference between adjacent crystal grains is 20
Since it can be within °, grain boundary cracking does not occur,
It has become possible to manufacture high-strength nozzles with high yield. As a result, the yield is improved by about 5 times from 15% to 70% as compared with the conventional columnar crystal nozzle, and the solution treatment is performed, and the creep rupture time under the conditions of 1040 ° C. and 14 kgf / mm ² is From 193h to 456h and 2
More than doubled. Further, although a part of the sidewall portion of the nozzle of the present invention is columnar crystal, the creep rupture time of the columnar crystal portion is about twice that of the conventional columnar crystal nozzle by performing the solution heat treatment.

Comparing the nozzle of the present invention with the single crystal nozzle, the nozzle of the present invention is inferior to the single crystal nozzle in high temperature creep strength. However, since the nozzle of the present invention contains the crystal grain boundary strengthening element, the existence of the crystal grain boundary can be allowed in the portion other than the blade portion. Therefore, the manufacturing yield is dramatically improved as compared with the conventional single crystal nozzle in which the existence of crystal grain boundaries cannot be tolerated. Further, the columnar crystal portion of the nozzle of the present invention is 700 ° C.
The tensile strength in the vicinity was about 10% higher than that of the single crystal nozzle.
It is considered that the grain boundaries of the columnar crystals contribute to the improvement of the tensile strength, but what is required for the sidewall portion is not the creep strength at high temperature but the tensile strength in the temperature range near 700 ° C. Because of its strength, it can be said that the structure in which the blade portion is a single crystal and the portion other than the blade portion is a columnar crystal is extremely effective as a gas turbine nozzle for power generation.

Table 4 shows casting conditions and alloy compositions of the nozzle of the present invention and the conventional nozzle.

[0058]

[Table 4]

Example 3 In Example 2, the solution heat treatment was performed on the nozzle of the present invention containing the grain boundary strengthening element by controlling the addition amounts of C, B, Hf and Zr and melting point of the eutectic structure. Is to raise. The method of increasing the melting point of the eutectic structure while maintaining the strength of the grain boundaries will be described below.

Conventional alloys containing grain boundary strengthening elements are C,
Since a large amount of B, Hf, Zr, etc. are contained and the melting point of the eutectic part is low, sufficient solution heat treatment cannot be performed. Therefore,
By weight, Cr: 2.0 to 16.0% Co: 7.5 to 10.5% W: 2.0 to 15.0% Re: 0 to 4.0% Mo: 0 to 6.0% Ta : 2.0 to 12.0% Al: 4.0 to 7.0% Ti: 0.5 to 5.0% Zr: 0 to 0.02% Hf: Ni containing 0.1 to 1.1% For the base alloy, a solution that changes the ratio of the C content and the B content of the alloy to form a solid solution of 50% or more by volume of precipitated γ'phase in the γ phase without causing initial melting by 5% or more by volume. A composition that enables chemical heat treatment and does not cause intergranular cracking during casting was investigated. The examination was conducted by actually casting a nozzle having the shape shown in FIG.

In order to form a solid solution of 50% or more by volume of precipitated γ'phase in the γ phase without causing initial melting of 5% or more by volume, C content is 0.2% or less and B content is B content. To 0.035
It had to be below%. But in this range,
When an ordinary columnar crystal nozzle in which the orientation difference between adjacent crystal grains was random was cast, grain boundary cracking occurred on almost the entire surface except for the end portions of the sidewalls. A typical morphology of intergranular cracks is shown in FIG.

Next, a nozzle was cast by the method shown in Example 1. In this case, as shown in FIG. 9, in the blade portion where the core is cast around to solidify and has a thin wall, as shown in FIG. No cracking occurred. Further, in the sidewall portion, grain boundary cracking did not occur if the orientation difference between adjacent crystal grains was within 20 °.

Further, when the C content was 0.025% or less and the B content was 0.005% or less, grain boundary cracking occurred in the entire surface including the end portions of the sidewalls in the ordinary columnar crystal nozzle. In the nozzle cast by the method described in Example 1, the orientation difference between adjacent crystal grains is 2 in the sidewall portion.
Even if it was within 0 °, grain boundary cracking occurred at 8 ° or more. No grain boundary cracking occurred in the blade portion if the difference in orientation between adjacent crystal grains was within 5 °.

When the volume fraction of the initially melted portion exceeded 5%, the creep rupture time at 1040 ° C. and 14 kgf / mm ² was less than 300 hours. Also, the solutionized precipitate γ ′
Even when the volume ratio of the phases was 50% or less, it was less than 300 hours. When the amount of C is 0.1% or more, the initial melting does not occur in 5% or more by volume ratio, and even if the precipitated γ'phase of 50% or more in volume ratio is dissolved in the γ phase, the breaking time is 300 h.
Sometimes fell below. The above results are shown together in FIG. From this figure, it can be seen that the nozzle, which has excellent high temperature strength and does not cause intergranular cracking, has an orientation difference of 8 ° between the crystal grains adjacent to the blade.
The columnar crystals within, the side wall is a columnar crystal in which the orientation difference between adjacent crystal grains is within 20 °, and the amount of C and the amount of B are A (C
0.10%, B0.002%), B (C0%, B0.01)
%), C (C0%, B0.035%), D (C0.1%, B
It can be seen that it can be manufactured by setting the range to 0.035%).

[Embodiment 4] In Embodiment 1, the nozzle is solidified in the direction perpendicular to the longitudinal direction of the sidewall. In this case, the growth direction is the <100> direction, and this direction coincides with the direction of the nozzle where the thermal stress is the most severe, which is convenient for relaxing the thermal stress. However, from the viewpoint of casting, since there are many overhangs in the direction perpendicular to the solidification direction, solidification is likely to be discontinuous, and there are problems such as equiaxed crystals and shrinkage cavities. Therefore, in this example, the nozzle was solidified in the direction parallel to the longitudinal direction of the sidewall. The solidification direction was from the gas inlet side of the blade to the gas outlet side, and as shown in FIG. 11, casting was performed using a seed crystal in order to align the <100> direction with the direction perpendicular to the sidewall longitudinal direction where the thermal stress becomes the most severe. . The <100> direction was set to the solidification direction. The casting method is shown in FIG. The enlarged part was divided into three parts, and the overhang part was provided with a coagulation accelerating passage. In this method, the crystal defect occurrence rate in the sidewall portion was lower than that in the method shown in Example 1.

[Embodiment 5] FIG. 13 is a perspective view of a nozzle having two blades in a single casting. This type of nozzle has a very large overhang portion in the direction perpendicular to the solidification direction as compared with a nozzle having a single blade, and thus it is very difficult to single crystallize by the conventional method. Therefore, as shown in FIG. 14, the casting direction was perpendicular to the longitudinal direction of the sidewall, and the seed crystal was provided under each blade. The orientation of the seed crystal was such that the solidification direction was the <100> direction and the direction parallel to the longitudinal direction of the sidewall was the other <100> direction. The composition of the alloy used for casting is the same as that shown in Table 1. When casting is performed using a plurality of seed crystals, the interface between the crystal grains having different seed crystals as nuclei becomes a grain boundary. This is because when casting a large product by the unidirectional solidification method, the orientation in the direction perpendicular to the solidification direction gradually rotates during solidification. However, it is difficult to keep the orientation difference of the united part within about 3 °. For this reason, it is very difficult to cast using a plurality of seed crystals as described above in a conventional single crystal alloy in which the existence of crystal grain boundaries cannot be tolerated. However, if there is only one seed crystal, a different crystal is likely to be generated in the overhang portion, and it is difficult to make only the blade portion into a single crystal. Therefore, according to the conventional method, it is difficult to manufacture a nozzle for a large-scale gas turbine for power generation, in which at least the blade portion is made of a single crystal and a plurality of blade portions are included in an integral casting. However, in the present invention, the orientation difference between adjacent crystal grains can be allowed up to 8 °, and particularly up to 20 ° in the sidewall. Therefore, by using a plurality of seed crystals, at least only the blade portion is made to be a single crystal. It has become possible to manufacture large nozzles. Further, even in the case of a nozzle having one wing portion, according to the method of the present invention, the overhang portion can be made into a single crystal by using a plurality of seed crystals.

FIG. 15 is a plan view in which a two-crystal flat plate having a thickness of 15 mm is cast in order to evaluate the strength of the crystal grain boundary of a single crystal grown from two seed crystals. The test piece was cut out in a direction perpendicular to and parallel to the crystal grain boundaries as shown in FIG. Further, the difference in crystal orientation in the solidification direction of the two-crystal flat plate used in the test was within 1 °.

Table 5 shows the composition of the alloy used in the test. Among them, the comparative alloy is a single crystal alloy disclosed in Japanese Patent Publication No. 3-75619, and the heat treatment described in Japanese Patent Publication No. 3-75619 was applied. The heat treatment condition of the alloy of the present invention is 1250 in vacuum.
After solution heat treatment at 1280 ° C. for 4 to 20 hours, 1000
~ 1150 ° C for 2-10h and 800-950 ° C for 4 ~
It was a two-step aging heat treatment for 50 hours. Table 6 shows the test results. From this result, the alloy of the present invention has a difference in crystal orientation of 20 °.
It is found that the comparative alloy, which is a single crystal alloy, cannot tolerate even a slight difference in crystal orientation, while no significant decrease in strength is observed.

[0069]

[Table 5]

[0070]

[Table 6]

[Embodiment 6] A gas turbine nozzle of the present invention is manufactured in the same manner as described above corresponding to the following claims.

FIG. 16 corresponds to claim 3, and FIG.
18 corresponds to claim 6, FIG. 18 corresponds to claim 6, FIG. 19 corresponds to claim 7, FIG. 20 corresponds to claim 8, and FIG. 21 corresponds to claim 10. 22 corresponds to claim 11, and FIG. 23 corresponds to claim 13.

[Embodiment 7] FIG. 24 is a sectional view of a rotating portion of a gas turbine. 30 is a turbine stub shaft, 3
3 is a turbine rotor blade, 40 is a turbine nozzle, and 43 is a turbine stacking bolt. The gas turbine of the present invention is composed of a single-axis type stacking rotor, has 17 stages of compressor disks 36, and has a turbine disk 3
4 is 3 steps. The blades and nozzles of the first-stage and second-stage turbines are air-cooled. The combustor is a verse-flow type slot cool type with 16 cans. The compression ratio of the compressor is 14: 1
And the outlet temperature is 400 ° C. The combustion gas temperature at the combustor is 1475 ° C, and the gas temperature at the turbine inlet is 135
0 ° C.

The weight of the distant piece 49, turbine disk 34, spacer 48, and stacking bolt 43 is C: 0.01 to 0.05%, Si: 0.10 to 0.30.
%, Mn 0.10 to 0.30%, Cr: 13.0 to 19.0
%, Fe: 35.0-45.0%, Mo: 0.1-1.0
%, Nb: 2.0 to 4.0%, Ti: 1.0 to 2.5%, A
l: 0.1 to 0.3%, Co: 0.1 to 0.9%, balance Ni
A Ni-based superalloy consisting of is used. Tensile strength of 100 to 115 kgf / mm ² ,
0.2% yield strength 80-90 kgf / mm ² , elongation 10-25
%, And the draw ratio was 35 to 65% (all values at 538 ° C.).

The turbine nozzle 40 has three stages, and the product of the present invention was applied to the first stage of them. There are a total of 82 first-stage nozzles, each of which consists of a single casting with one blade, four of which are nozzles manufactured by the selector method shown in Example 1, and the other four are those of Example 4. The nozzle manufactured by the seed crystal method shown in FIG. Among these, the nozzle manufactured by the seed crystal method was unidirectionally solidified in a direction parallel to the longitudinal direction of the sidewall, the solidification direction was <100> orientation, and the vertical direction to the sidewall longitudinal direction was <100>. Two pieces each, one with <110> and one with <110>. Also,
Nozzle manufactured by the selector method has one complete single crystal up to the side wall, two nozzles with part of the outer peripheral side wall having columnar crystals, and part of the outer peripheral side wall with columnar crystal One sheet having equiaxed crystals at the end portions of the sidewalls on the circumferential side and the outer circumferential side was used. As the alloy, alloy E in Table 7 was used, and the heat treatment conditions were 1250 to 12 in vacuum.
80 ℃, water cooling after 4 ~ 20h + 1080 ℃ -4h after air cooling +
It was air-cooled after 871 ° C. for 20 hours. The second stage nozzle is of a type in which the sidewall is only on one side, but a nozzle in which the blade portion is a single crystal and a portion of the sidewall is a columnar crystal is used for eight of these. This nozzle was cast by the selector method and solidified in one direction in the sidewall direction from the blade side. As the alloy, the alloy F in Table 7 was used. The third stage nozzle was also a cantilever type, and the equiaxed crystal of alloy F in Table 7 was used. The heat treatment conditions of the second and third nozzles were air cooling after 1230 ° C.-2 hours + air cooling after 1080 ° C.-4 hours + air cooling after 871 ° C.-20 hours.

[0076]

[Table 7]

The turbine rotor blade 33 has three stages, of which the first stage (blade length 235 mm) was a cast single crystal blade of alloy E in Table 7. The heat treatment conditions were the same as for the first stage nozzle. In addition, the second stage rotor blade (wing length 280 mm) and the third stage rotor blade
(Wing length 350mm) 0.07% C-6.0% Cr-9.3
% Co-0.5% Mo-8.4% W-2.9% Re-3.4
% Ta-5.7% Al-0.7% Ti-0.015% B-
A columnar crystal blade cast from an alloy of 0.005% Zr-1.4% Hf-balance Ni (weight%) was used. The heat treatment condition is 108
It was air-cooled after 0 ° C.-4 hours and air-cooled after 871 ° C.-20 hours.

The power generation output obtained by this embodiment is 60
With MW, thermal efficiency as high as 34% or more can be obtained.

The gas turbine of this example was periodically inspected about one year later, and the damage condition of the nozzle of the present invention applied to the first stage was investigated. 0.15% used at the same time as the nozzle of the present invention
C-20% Co-23% Cr-2% W-0.01% B-
0.5% Fe-3.7% Ti-1.0% Nb-1.4% Ta
In the equiaxed crystal nozzle having a composition of -1.9% Al-the balance Ni (% by weight), the blade portion had many cracks in the vertical direction with respect to the sidewall, and part thereof reached the sidewall. It is considered that this crack was caused by thermal stress. On the other hand, among the nozzles of the present invention, those prepared by the selector method and those prepared by the seed crystal method and having the vertical azimuth of <100> in the longitudinal direction of the sidewall were cracked even after about 1 year of use. Did not exist at all. Further, no crack was found in the sidewall portion where columnar crystals and equiaxed crystals exist. However, a very small number of cracks were found on the wings in the case where the vertical direction was <110> in the longitudinal direction of the sidewall. The above results show the excellent thermal stress resistance of the nozzle of the present invention in which the blade portion is made of a single crystal and the longitudinal direction of the sidewall and the vertical direction are <100>. It shows that even if columnar crystals or equiaxed crystals are present in the side wall portions that do not exist, there is no problem in actual operation. FIG. 25 shows the high temperature low cycle fatigue test results of alloy E in Table 7 used in the nozzle of the present invention. From these results, when the crystal orientations are the same, the fatigue lives of the single crystal and the columnar crystals are almost the same. Therefore, if the direction with the highest thermal stress is set to the <100> direction, the columnar crystals are equivalent to the single crystal. It can be seen that the fatigue life of is obtained.

[Embodiment 8] FIG. 26 is a schematic diagram showing a single-shaft combined cycle power generation system using a gas turbine and a steam turbine of Embodiment 6 together.

When power is generated using a gas turbine,
In recent years, a gas turbine is driven by using liquefied natural gas (LNG) as a fuel, and a steam turbine is driven by steam obtained by recovering exhaust gas energy of the gas turbine, and a generator is driven by the steam turbine and the gas turbine. There is a tendency to adopt the so-called combined power generation method.
In this combined power generation system, the following system configuration enables high thermal efficiency of approximately 46% or higher, which is higher than the thermal efficiency of 40% in the case of the conventional steam turbine alone.

First, air enters the air compressor of the gas turbine through the intake filter and the steam silencer. About 1 here
The air that has been compressed four times and reached about 400 ° C. is introduced into a low NOx type combustor. In the combustor, fuel is injected into the compressed air to generate a high temperature and high pressure gas of 1470 ° C., and this gas works in a turbine to generate power.

Exhaust gas at 530 ° C. or higher discharged from the turbine is sent to the exhaust heat recovery boiler through the exhaust silencer, and high-pressure steam at 530 ° C. or higher is obtained from this thermal energy. This boiler is provided with a denitration device by dry ammonia catalytic reduction. The exhaust gas is discharged to the outside from a stack of tripods having a height of about 200 m. High-pressure and low-pressure steam generated in the exhaust heat recovery boiler is sent to a steam turbine composed of a high-low pressure integrated rotor.

The steam that has worked in the steam turbine becomes condensed water that has been degassed in a vacuum in the condenser, is pressurized by the condensate pump, and is supplied to the boiler as feed water. The gas turbine and the steam turbine drive the generator from both ends of one generator to generate electricity. For cooling the high temperature part of the gas turbine used in such a combined cycle power generation system, steam used in a steam turbine may be used in addition to ordinary compressed air. Since steam has a larger specific heat and is lighter than air, it has a higher cooling efficiency than air. In this case, in order to improve efficiency, a system in which steam circulates in a closed space is formed, and the blades and nozzles are of a closed type having no cooling holes like air cooling. As shown in Example 6, the nozzle of the present invention is less likely to cause cracks due to thermal fatigue, and is therefore suitable as a closed type nozzle.

In this combined power generation system, the gas turbine generates 60 MW and the steam turbine generates 30 MW. Since this system is more compact than a steam turbine of the same power generation capacity, it can be manufactured at a lower cost than a steam turbine.

The steam turbine according to the present invention is a high-low pressure integrated steam turbine, and the steam pressure at the main steam inlet of this high-low pressure integrated steam turbine is raised to 100 atg and the temperature is increased to 538 ° C. Can be increased. The blade length of the final stage rotor blade is set to 30 in response to the increase in single machine output.
Increased to more than an inch and increased steam flow rate.

The steam turbine according to the present invention is provided with 13 or more stages of moving blades planted in the high and low pressure integrated rotor shaft, and the steam passes through the steam control valve from the steam inlet to the steam pressure of 100 atg, as described above. Temperature is 538 ℃
Flows in. Steam flows in one direction from the inlet, and steam pressure is 7
22 mmHg and steam temperature 33 ° C., and the gas is discharged from the steam outlet at the rear of the final stage moving blade. Ni-Cr-Mo-V low alloy steel is used for the high-low pressure integrated rotor shaft according to the present invention. The rotor blade embedded portion of the rotor shaft has a dovetail shape and is cut from the rotor shaft. The length of the dovetail portion becomes longer as the moving blade becomes shorter, so that the vibration is reduced.

The high / low pressure integrated rotor shaft according to this embodiment has C: 0.18 to 0.30%, Si: 0.1% or less, M
n 0.3% or less, Ni: 1.0 to 2.0%, Cr: 1.0 to
1.7%, Mo: 1.0 to 2.0%, V: 0.20 to 0.3
It consists of 0% and balance Fe, and is quenched by water spray cooling at 900 to 1050 ° C, and then tempered at 650 to 680 ° C.

The plant configuration is not limited to a uniaxial type in which a gas turbine, a steam turbine and a generator are uniaxial, and a plurality of combinations of one generator is installed for one gas turbine, and a plurality of gas generators are installed. It is also possible to collect the exhaust gas of the turbine into one steam turbine and use the one steam turbine to drive one different generator to form a multi-shaft type.

The combined cycle power generation system consists of a combination of a gas turbine that can be started in a short time and a steam turbine that is small and has a simple structure. Therefore, output adjustment is easy, and intermediate load thermal power that responds quickly to changes in demand. As is the best.

The reliability of the gas turbine has been dramatically improved due to the recent development of technology, and since the combined cycle power plant has a system composed of a combination of small capacity machines, a failure should occur. However, the effect can be stopped locally.

[0092]

According to the present invention, it becomes possible to manufacture a large-sized nozzle having excellent high temperature strength with a high yield. Therefore, remarkable effects such as improvement of power generation efficiency due to increase of combustion gas temperature or improvement of plant reliability due to extension of nozzle life are exhibited.

[Brief description of the drawings]

FIG. 1 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 2 is a plan view of a core for producing cooling holes according to this embodiment.

FIG. 3 is a configuration diagram showing an outline of an apparatus for manufacturing a gas turbine nozzle according to the present invention.

FIG. 4 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 5 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 6 is a perspective view of a nozzle for a gas turbine according to the present invention.

FIG. 7 is a comparative diagram showing high temperature strength of a nozzle obtained according to the present invention and a conventional nozzle.

FIG. 8 is a sketch diagram showing a state of intergranular cracking observed in a conventional columnar crystal nozzle.

FIG. 9 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 10 is a diagram showing the relationship between the amount of C and the amount of B in which the precipitated γ ′ phase can be solutionized without causing initial melting of the alloy and grain boundary cracking does not occur.

FIG. 11 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 12 is a configuration diagram showing a casting method plan in the case where the solidification direction is parallel to the sidewall longitudinal direction in the present invention.

FIG. 13 is a perspective view of a nozzle having a structure having two blades in one casting according to the present invention.

FIG. 14 is a configuration diagram showing a casting method of a nozzle having a structure having two blades in one casting in the present invention.

FIG. 15 is a schematic view showing a two-crystal flat plate used to evaluate the strength of a crystal grain boundary and a sampling direction of a test piece shown in this example.

FIG. 16 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 17 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 18 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 19 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 20 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 21 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 22 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 23 is a perspective view of a gas turbine nozzle according to the present invention.

FIG. 24 is a configuration diagram of a gas turbine according to the present embodiment.

FIG. 25 is a comparison diagram of high temperature low cycle fatigue strength of a single crystal and a columnar crystal shown in this example.

FIG. 26 is a configuration diagram of a combined cycle power plant according to the present embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wing part, 2 ... Side wall (inner peripheral side), 3 ... Side wall (outer peripheral side), 4 ... Cooling air inlet, 5 ... Cooling hole, 11 ... Water-cooled copper chill plate, 12 ... Starter, 13
... selector, 14 ... enlarged part, 15 ... coagulation accelerating passage, 16
… Ceramic molds, 17… feeders, 18… Mold heating furnaces,
19 ... Melting furnace, 20 ... Vacuum pump, 21 ... Intergranular crack, 2
2 ... Seed crystal, 23 ... Crystal grain boundary, 24 ... Parallel direction test piece,
25 ... Vertical test piece, 26 ... Crystal 1 orientation, 27 ... Crystal 2 orientation, 28 ... Crystal 1 and crystal 2 orientation difference, 30 ... Turbine stub shaft, 33 ... Turbine blade, 34 ... Turbine disk, 36 … Compressor disk, 37…
Compressor blade, 38 ... Compressor stacking bolt, 39 ... Compressor stub shaft, 40 ... Turbine nozzle, 43 ... Turbine stacking bolt, 48
… Spacer, 49… Distant piece.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Todan Saito 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Noriyuki Watanabe Seven-mika-cho, Oita, Ibaraki 1-1-1, Hitachi Ltd., Hitachi Research Laboratory (72) Inventor Hiroyuki Doi 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Factory

Claims (29)

[Claims] 1. A gas turbine nozzle having a blade portion exposed to high-temperature high-pressure gas and a sidewall that is a connecting portion at both ends of the blade portion, wherein one end of the blade portion and the sidewall is a single crystal, A nozzle for a gas turbine, characterized in that the balance is made of an integral casting having columnar crystals or equiaxed crystals that are unidirectionally solidified in a portion continuous from the single crystal. 2. A gas turbine nozzle having a blade exposed to high-temperature and high-pressure gas and a sidewall that is a connecting portion at both ends of the blade, and between the crystal grains in which one end of the blade and the sidewall are adjacent to each other. Is a columnar crystal having an orientation difference of 8 degrees or less, and the remaining portion has an orientation difference of 2 between adjacent crystal grains.
A nozzle for a gas turbine, which is composed of columnar crystals within 0 degree. 3. A gas turbine nozzle having a blade portion exposed to high-temperature and high-pressure gas, and a sidewall that is a connecting portion at one end of the blade portion, wherein the blade portion is a single crystal and the rest is a single crystal. A nozzle for a gas turbine, which is composed of an integral casting having continuous unidirectionally solidified columnar crystals. 4. A gas turbine nozzle having a blade portion exposed to high-temperature and high-pressure gas and a sidewall that is a connecting portion at one end of the blade portion, wherein the orientation difference between the crystal grains adjacent to the blade portion is 8 degrees. Nozzle for a gas turbine, characterized in that the remaining portion is a columnar crystal having an orientation difference of 20 degrees or less between adjacent crystal grains. 5. A gas turbine nozzle having a blade portion exposed to high-temperature and high-pressure gas and a sidewall as a connecting portion at both ends of the blade portion, wherein a central portion of one end of the sidewall is a single crystal, and both end portions are formed. Is at least one of a columnar crystal and an equiaxed crystal, the wing portion is a single crystal continuous from the single crystal portion of the sidewall, and the other sidewall is a unidirectionally solidified columnar crystal continuous from the wing portion. And a gas turbine nozzle made of an integral casting having at least one of equiaxed crystals. 6. A gas turbine nozzle having a blade portion exposed to high-temperature high-pressure gas, and sidewalls that are connecting portions at both ends of the blade portion. Columnar crystals with a difference of 8 degrees or less,
The corner portions at both ends are equiaxed crystals, and the wing portion has a misorientation between adjacent crystal grains which is unidirectionally solidified continuously from columnar crystals in which the adjoining crystal grains of the sidewall are within 8 degrees. Is 8
Columnar crystals of which the orientation difference between adjoining crystal grains is 20 degrees or less. A nozzle for a gas turbine, which is composed of an integral casting and is made of an equiaxed crystal. 7. A gas turbine nozzle having a blade portion exposed to high-temperature and high-pressure gas and a sidewall that is a connecting portion at one end of the blade portion, wherein the blade portion is a single crystal, and a central portion of the sidewall. Is a columnar crystal that is unidirectionally solidified continuously from a single crystal that is continuous from the single crystal part, and is made of an integral casting in which the corners are equiaxed crystals. 8. A gas turbine nozzle having a blade portion exposed to high-temperature high-pressure gas and a sidewall as a connecting portion at one end of the blade portion, wherein the blade portion has an orientation difference of 8 degrees between adjacent crystal grains. Columnar crystals within, the central portion of the side wall is columnar crystals with an orientation difference of 20 degrees or less between adjacent crystal grains continuously unidirectionally solidified from the wing portion, and corner portions are equiaxed crystals. A nozzle for a gas turbine, which is characterized by being formed of an integral casting. 9. A wing part exposed to a high temperature and high pressure gas, and sidewalls that are connecting parts at both ends of the wing part, and part or all of the chill plate side wall and the wing part are single crystals. There is a method for manufacturing a gas turbine nozzle, wherein a part or all of the sidewalls on the final solidification portion side is made of an integral casting having columnar crystals continuously and unidirectionally solidified from the single crystal portion, wherein the single crystal Has a solidification accelerating passage between at least one part of the portion and the sidewall on the final solidification portion side, and a part or all of the sidewall on the final solidification portion side is a single crystal or one continuous from the single crystal. A method for manufacturing a nozzle for a gas turbine, which is characterized in that columnar crystals are directionally solidified. 10. A wing part exposed to a high temperature and high pressure gas, and a sidewall that is a connecting part at one end of the wing part, wherein the wing part is a single crystal, and a part or all of the sidewall is the single crystal. A method for producing a nozzle for a gas turbine, which is made of an integral casting which is a columnar crystal continuously unidirectionally solidified from a crystal part, wherein a solidification promoting passage is provided between at least one location of the single crystal part and the sidewall. A method for manufacturing a nozzle for a gas turbine, characterized in that a part or all of the sidewall is formed into a single crystal or a columnar crystal continuously unidirectionally solidified from the single crystal. 11. A gas turbine nozzle having a blade exposed to high-temperature high-pressure gas and a sidewall as a connecting portion at both ends of the blade, part or all of the inner sidewall is a single crystal. The wing portion is a single crystal continuous from the single crystal portion of the inner sidewall, and a part or all of the outer sidewall is a single crystal continuous from the single crystal portion or from the single crystal A nozzle for a gas turbine, which is a columnar crystal that is continuously unidirectionally solidified, and is made of an integral casting that is unidirectionally solidified in a direction from the sidewall on the inner peripheral side to the sidewall on the outer peripheral side. 12. A gas turbine nozzle having a blade exposed to high-temperature high-pressure gas and a sidewall as a connecting portion at both ends of the blade, and at least only the blade is obtained by unidirectionally solidifying with a seed crystal. In the wing portion, one of the three <100> directions perpendicular to each other is perpendicular to the longitudinal direction of the sidewall, and the other one is parallel to the longitudinal direction of the sidewall. A gas turbine nozzle characterized by being grown. 13. A gas turbine nozzle having a blade portion exposed to high-temperature high-pressure gas and a sidewall as a connecting portion at both ends of the blade portion, which is unidirectionally solidified by using a seed crystal and at least the blade portions are adjacent to each other. A columnar crystal having an orientation difference of 8 degrees or less between the crystal grains, and one of the three <100> directions perpendicular to each other in the blade portion is within ± 10 ° from the vertical direction with respect to the sidewall longitudinal direction, A nozzle for a gas turbine, characterized in that the other one is grown within ± 10 ° from a direction parallel to the longitudinal direction of the sidewall. 14. A method for producing a gas turbine nozzle having a blade portion exposed to high-temperature and high-pressure gas and a sidewall as a connecting portion at both ends of the blade portion, in one direction solidification using two or more seed crystals. A method for manufacturing a nozzle for a gas turbine, which comprises: 15. The method for manufacturing a gas turbine nozzle according to claim 14, wherein at least the blade portion is a columnar crystal having an orientation difference of 8 degrees or less between adjacent crystal grains. Manufacturing method. 16. The method for manufacturing a gas turbine nozzle according to claim 15, wherein in the blade portion, one of three <100> directions perpendicular to each other is ±± from a direction perpendicular to the longitudinal direction of the sidewall. A method of manufacturing a nozzle for a gas turbine, characterized in that the other one is grown within ± 10 ° from a direction parallel to the longitudinal direction of the sidewall. 17. The method for manufacturing a gas turbine nozzle according to claim 12, wherein the gas is unidirectionally solidified from the gas inlet side of the blade portion toward the gas outlet side or from the gas outlet side of the blade portion toward the gas inlet side. A method for manufacturing a nozzle for a gas turbine, which is characterized in that 18. A gas turbine nozzle having a plurality of blades in a single casting, wherein at least the blades are single crystals, and the balance contains one or both of columnar crystals and equiaxed crystals. Characteristic gas turbine nozzle. 19. A method for manufacturing a gas turbine nozzle having a plurality of blades in a single casting, characterized in that two or more seed crystals are unidirectionally solidified so that at least the blades are single crystals. Gas turbine nozzle manufacturing method. 20. The gas turbine nozzle according to any one of claims 1 to 8 and 11 to 13, wherein Co, Ni or Co + Ni containing Cr, Al and Y is contained on the blade surface.
A nozzle for a gas turbine, which is coated with an alloy layer containing as a main component. 21. A gas turbine nozzle according to any one of claims 1 to 8, 11 to 13, and 20, wherein a gas having a thermal barrier coating made of a ceramic layer is formed on the outermost surface of the blade portion and its periphery. Turbine nozzle. 22. Claims 1-8, 11-13, 20, 21
5. The gas turbine nozzle according to claim 1, wherein the gas turbine nozzle comprises Cr2 to 25% and Al1 to 1% by weight.
7%, W2-15%, Ti0.5-5%, Nb0-3
%, Mo0-6%, Ta1-12%, Re0-4%, C
o 7.5-25%, Fe 0.5% or less, C 0.20% or less, B 0.002-0.035%, Hf 0-2.0%, Z
A nozzle for a gas turbine, comprising a casting of a Ni-based alloy containing Ni of not more than 0.02% and not less than 40%. 23. The gas turbine nozzle according to any one of claims 1 to 11, 20 and 21, wherein the gas turbine nozzle is, by weight%, Cr 2 to 16%, Al 4 to 7%, W2.
~ 15%, Ti 0.5-5%, Nb 0-3%, Mo 0-
6%, Ta2-12%, Re0-4%, Co7.5-1
0.5%, C 0.20% or less, B0.002-0.035
%, Hf 0.1 to 1.1%, Zr 0.02% or less, and 4
It is made of a Ni-based alloy containing 0% or more of Ni, and the C content and the B content are A (C 0.10%, B 0.002%) and B (C0
%, B0.01%), C (C0%, B0.035%), D
A nozzle for a gas turbine, which is made of a casting in the range of (C0.1%, B0.035%). 24. A wing part exposed to a high temperature and high pressure gas, and a sidewall as a connecting part at both ends of the wing part, wherein a part or all of one end of the sidewall is a single crystal, and the wing part. Is a single crystal continuous from a single crystal portion at one end of the sidewall, and a single crystal or a single crystal in which a part or all of the portion excluding one end of the wing and the sidewall is continuous from the single crystal portion. A nozzle for a gas turbine, which is composed of an integral casting which is a columnar crystal continuously unidirectionally solidified from, wherein the casting is in a weight% ratio of Cr 6.0 to 9.0%, Al 5
~ 6%, W7 ~ 10%, Ti0.5 ~ 1%, Mo0.3 ~
0.7%, Ta2.5-5.0%, Re0-3.2%, Co8
10.5%, C 0.03 to 0.1%, B 0,002 to 0.035
%, Hf 0.5 to 1.8%, Zr 0.02% or less, and 4
A gas turbine nozzle comprising a Ni-based alloy containing 0% or more of Ni. 25. A wing part exposed to a high temperature and high pressure gas, and sidewalls which are connecting parts at both ends of the wing part, and a part or all of one end of the sidewall is a single crystal, and the wing part Is a single crystal continuous from a single crystal portion at one end of the sidewall, and a single crystal or a single crystal in which a part or all of the portion excluding one end of the wing and the sidewall is continuous from the single crystal portion. In the nozzle for a gas turbine, which is made of an integral casting that is a unidirectionally solidified columnar crystal from the above, the gas turbine nozzle is, by weight%, Cr2 to
16%, Al 4-7%, W 2-15%, Ti 0.5-5
%, Nb0-3%, Mo0-6%, Ta2-12%, R
e0-4%, Co 7.5-10.5%, C 0.20% or less, B
0.002-0.035%, Hf 0.1-1.1%, Zr
It is composed of a Ni-based alloy containing Ni of 0.02% or less and 40% or more, and the C content and the B content are A (C 0.10%, B
0.002%), B (C0%, B0.01%), C (C0
%, B0.035%), D (C0.1%, B0.035%) in the range of castings, characterized by being a gas turbine nozzle. 26. A gas turbine in which air compressed by a compressor is combusted in a combustor, and a turbine disk is rotated by the combustion gas to drive a generator, wherein the gas turbine has three or more stages of turbines. The first-stage rotor blade of the turbine includes a blade portion exposed to the high-temperature and high-pressure gas, a platform that is an overhanging portion that is connected to the blade portion and shuts off the high-temperature and high-pressure gas, and is connected to the platform and between the blade portion and the disk. A shank portion having a distance for obtaining a sufficient temperature gradient, and a seal fin provided on the shank portion, which is a protrusion for blocking high-temperature high-pressure gas,
And a dovetail which is an embedded portion in a disc connected to the shank portion, the wing portion is a single crystal, and a part of a portion excluding the wing portion and the seal fin is continuous from the wing portion. The crystal, the remainder consists of an integral casting which is a columnar crystal continuously unidirectionally solidified from the single crystal, further, the first stage nozzle of the turbine, a blade portion exposed to high temperature and high pressure gas,
A single crystal having sidewalls that are connecting portions at both ends of the wing portion, a part or all of one end of the sidewall being a single crystal, and the wing portion being continuous from the single crystal portion at one end of the sidewall. And a part or all of the portion excluding one end of the wing portion and the sidewall is a single crystal continuous from the single crystal portion or a columnar crystal continuously unidirectionally solidified from the single crystal, an integral casting. A gas turbine comprising: 27. A gas turbine for driving a generator by burning air compressed by a compressor in a combustor and rotating a turbine disk with the combustion gas, wherein the gas turbine has a turbine of three stages or more, The combustion gas temperature is 1500 or more in the combustor and 1 at the inlet of the first stage turbine.
The temperature is 300 ° C. or higher, and the first stage nozzle of the turbine has a blade portion having a width of 70 mm or more, a blade portion exposed to high-temperature high-pressure gas, and sidewalls at both ends of the blade portion that are connecting portions. Part or all of one end of the wall is a single crystal, the wing portion is a single crystal continuous from the single crystal portion of one end of the sidewall, and one of the portions excluding the wing portion and one end of the sidewall Part or all consisting of a single crystal that is continuous from the single crystal part or a columnar crystal that is unidirectionally solidified continuously from the single crystal, and has a power generation capacity of 2.5.
A gas turbine characterized by having a capacity of 10,000 kW or more. 28. A gas turbine for driving a generator by burning air compressed by a compressor in a combustor and rotating a turbine disk with the combustion gas, wherein the gas turbine has a turbine of three or more stages, The combustion gas temperature is 1500 ° C. or higher in the combustor and 1300 ° C. or higher at the inlet of the first-stage turbine, and the first-stage nozzle of the turbine is
The wing has a width of 70 mm or more, and has a wing that is exposed to high-temperature and high-pressure gas, and sidewalls that are connecting portions at both ends of the wing, and one or all of one end of the sidewall is a single crystal. A single crystal in which the wing portion is a single crystal continuous from a single crystal portion at one end of the sidewall, and a part or all of the portion except the one end of the wing portion and the sidewall is continuous from the single crystal portion Alternatively, the casting consists of an integral casting, which is a columnar crystal continuously unidirectionally solidified from the single crystal, and the casting is wt%.
Then, Cr 6.0-9.0%, Al 5-6%, W7-10
%, Ti 0.5 to 1%, Mo 0.3 to 0.7%, Ta 2.5
~ 5.0%, Re0-3.2%, Co8-10.5%, C0.
03-0.1%, B0.002-0.035%, Hf0.5
~ 1.8%, Zr 0.02% or less, and 65% or more Ni
A gas turbine that is made of a Ni-based alloy that contains, and has a power generation capacity of 25,000 kW or more. 29. A gas turbine driven by high-temperature and high-pressure combustion gas, an exhaust heat recovery boiler that generates high-pressure steam by combustion exhaust gas of the gas turbine, a steam turbine driven by the high-pressure steam, and the gas. In a combined cycle power plant including a turbine and a generator driven by a steam turbine, the gas turbine has a turbine having three or more stages, the combustion gas temperature is 1500 ° C. or more in a combustor, and 1300 at an inlet of a first stage turbine. ℃ or more, 560 ℃ or more at the outlet of the final turbine, the temperature of the steam obtained in the exhaust heat recovery boiler is 530 ℃ or more, the steam turbine is a high-low pressure integrated type, the power generation capacity of the gas turbine is 5 Over 10,000 kW and steam turbine power generation capacity of 30,000 K
W or more, the total power generation efficiency of the entire plant is 45% or more, the first stage turbine nozzle of the gas turbine has a blade width of 100 mm or more, and a blade portion exposed to high temperature and high pressure gas,
The sidewall has a connecting portion at both ends of the blade, is cooled by a closed cooling method for using a medium other than air as a cooling medium, a part or all of one end of the sidewall is a single crystal, The wing portion is a single crystal continuous from the single crystal portion at one end of the sidewall, and a part or all of the portion except the one end of the wing portion and the sidewall is a single crystal continuous from the single crystal portion or It is composed of an integral casting which is a columnar crystal continuously and unidirectionally solidified from the single crystal. The casting is Cr 6.0 to 9.0% by weight and Al 5 to 6
%, W7 to 10%, Ti 0.5 to 1%, Mo 0.3 to 0.
7%, Ta2.5-5.0%, Re0-3.2%, Co8-
10.5%, C0.03-0.1%, B0.002-0.0
35%, Hf 0.5-1.8%, Zr 0.02% or less, and a composite power plant comprising a Ni-based alloy containing Ni of 65% or more.