JPH10317105A - High strength steel, steam turbine long blade and steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the turbine blade excellent in tensile strength and impact value by using a high strength steel made of a Ni-Cr martensitic steel containing Nb, Ta etc., for the steam turbine long blade. SOLUTION: A 12 Cr martensitic steel, which contains, by weight, 0.10-0.24% C, <=0.25% Si, <=0.90% Mn, 8.0-13.0% Cr, 2.0-4.0% Ni, 1.5-3.0% Mo, further 0.04-0.24% in total one or two kinds among Nb, Ta as a strength/toughness improvement element, 0.02-0.10% N, further 0.01-0.05% V as having a C/V ratio of 0.75-5, is used for the steam turbine long blade. This slab, after forged into a turbine blade, is hardened at 1000-1100 deg.C and is subjected to primary tempering at 550-570 deg.C, further secondary tempering at a slightly higher temp. of 560-590 deg.C. the turbine blade having the tensile strength at a room temp. of >=120 kgf/mm<2> and the impact value of >=7 kgfm/cm<2> is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel high-strength steel, a turbine long blade thereof, and a novel steam turbine using the long blade.

[0002]

2. Description of the Related Art At present, 12Cr-
Mo-Ni-VN steel is used.

In recent years, it has been desired to improve the thermal efficiency of a gas turbine from the viewpoint of energy saving, and to reduce the size of the equipment from the viewpoint of space saving.

[0004] To improve the thermal efficiency and make the equipment compact, it is effective means to increase the length of the steam turbine blades. Therefore, the blade length of the last stage of the low-pressure steam turbine tends to increase year by year. Along with this, the operating conditions of the blades of the steam turbine have become severe, and the strength of the conventional 12Cr-Mo-Ni-VN steel is insufficient, and a material having higher strength is required. As the strength of the long wing material, a tensile strength, which is a basic mechanical property, is required.

[0005] Further, from the viewpoint of ensuring safety against fracture, a certain degree of toughness is required.

[0006] The conventional 12Cr-Mo-Ni-
Ni-based alloys and Co-based alloys are generally known as structural materials higher than VN steel (martensitic steel), but they are inferior in hot workability, machinability and vibration damping properties.
It is not desirable as a wing material.

As a blade material for a steam turbine, Japanese Patent Application Laid-Open No.
No. 13466, JP-A-56-35754, JP-A-5-311
No. 347 discloses that 12% Cr-based martensitic steel is used.

[0008]

SUMMARY OF THE INVENTION In order to cope with the recent increase in the length of low-pressure steam turbine blades, the present invention has improved tensile strength and toughness over these conventional materials.

An object of the present invention is to provide a martensitic steel having a high tensile strength, a steam turbine long blade using the same, a method for producing the same, a steam turbine having a high thermal efficiency, and a thermal power plant.

[0010]

Means for Solving the Problems The present inventors have studied the optimum amount of each element to achieve higher strength and higher toughness than conventional alloy steel. On the other hand, without adding V, which was considered an essential element,
It has been found that by adding an appropriate amount of b (or Ta), the strength and toughness can be further enhanced, and the present invention has been achieved.

That is, in the present invention, C0.10 by weight ratio.
0.24%, Si 0.25% or less, Mn 0.90% or less,
Cr 8.0 to 13.0%, Ni 2.0 to 4.0%, Mo 1.
More than 5% and 3.0% or less, the total amount of one or two of Nb and Ta is 0.04 to 0.24%, and N is 0.02 to 0.1.
A high-strength and high-toughness steel containing 0%, with the balance being Fe and unavoidable impurities. In the steel of the present invention, V must be set to 0.01% or more and less than 0.05%.

According to the present invention, C.sub.0.10 to 0.24 by weight is used.
%, Si 0.25% or less, Mn 0.1-0.50%, Cr
8.0-13.0%, Ni 2.0-4.0%, Mo 1.0-2.0%
3.0%, the total amount of one or two of Nb and Ta is 0.0
4 to 0.24% and N 0.02 to 0.10%, the C + Nb content is 0.21 to 0.40% or the (Mn / Ni) ratio is 0.1 or less, and the balance is Fe And high-strength steel comprising unavoidable impurities, and further containing V as described above.

According to the present invention, C0.15 to 0.24 by weight is used.
%, Si 0.25% or less, Mn 0.90% or less, Cr 8.0 to 0.8%
13.0%, Ni 2.0-4.0%, Mo 1.5-3.0
%, V 0.05 to 0.20%, one or two of Nb and Ta
The total amount of seeds is 0.04-0.24%, and N 0.02-0.2.
The high strength steel contains 10%, the (C / V) ratio is 0.75 to 5, and the balance is Fe and inevitable impurities.

The present invention resides in a long blade of a steam turbine having the above composition and having a fully tempered martensite structure. The steam turbine long blade must have high tensile strength and high cycle fatigue strength to withstand high centrifugal stress and vibration stress due to high-speed rotation. Therefore, the metal structure of the blade material must be a fully tempered martensitic structure, since the presence of harmful δ ferrite significantly reduces the fatigue strength.

According to the present invention, the weight ratio exceeds C 0.15% to 0.24% or less, Si 0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.0%, Ni 2.0 to 4.0%. 0%, Mo
1.0 to 3.0%, the total amount of one or two of Nb and Ta is 0.04 to 0.24%, and N is 0.02 to 0.10%, and the balance is Fe and inevitable impurities. And a long blade of a steam turbine characterized by having a fully tempered martensite structure, and further includes V as described above.

The steel of the present invention has a Cr equivalent calculated by the following equation of 1
It is necessary to adjust the components so as to be 0 or less so that the δ ferrite phase is not substantially contained.

Cr equivalent = -40C-2Mn-4Ni-2
Co-30N + 6Si + Cr + 4Mo + 11V + 5Nb
+2.5 Ta [Each element is calculated based on the content (% by weight) in the alloy] To withstand the above high centrifugal stress, the tensile strength of the long wing material is 120 kgf / mm ² or more, preferably 128.5 kgf / mm ²
In addition to the above, it is preferable to set the impact value to 7 kgf-m / cm ² or more from the viewpoint of securing reliability against brittle fracture.

Further, the present invention provides a heat treatment for refining Cr8.
The alloy after melting and forging a martensitic steel alloy containing 0 to 13.0% by weight is subjected to quenching in which the steel is kept at 1000 ° C. to 1100 ° C., preferably for 0.5 to 3 hours and then rapidly cooled to room temperature. At 550 ° C to 570 ° C, preferably 1 to
The primary tempering is performed after cooling for 6 hours and then cooling to room temperature, and the secondary tempering is further performed twice or more each time for cooling to room temperature after maintaining at 560 ° C. to 590 ° C., preferably for 1 to 6 hours.

According to the present invention, the last stage blade length of the low pressure turbine is set to 83
8 mm (33 ") or more, preferably 1016 mm (40")
The blade length of the last stage of the 3600 rpm steam turbine and the low-pressure turbine is 1016 mm (40 ″) or more, preferably 1
A 3000 rpm steam turbine with a diameter of at least 092 mm (43 ") has been made more efficient and more compact than conventional turbines.

(1) The reason for limiting the component range of the 12% Cr-based martensitic steel used in the last stage blade of the low-pressure steam turbine in the present invention will be described.

C is at least 0.1 to obtain high tensile strength.
0% is necessary, and if C is excessively increased, the toughness is reduced. In particular, it is preferred that 0.12 to 0.22% exceeds 0.14 to 0.20% or 0.15%.

Si is a deoxidizing agent and Mn is a desulfurizing / deoxidizing agent added during melting of steel, and is effective even in a small amount. Si is a δ-ferrite forming element, and a large amount thereof causes harmful δ-ferrite formation which deteriorates fatigue and toughness. Therefore, it must be 0.25% or less. In addition, according to the carbon vacuum deoxidation method, the electroslag melting method, or the like, there is no need to add Si, and the addition of Si is preferable. In particular, it is preferably 0.10% or less, more preferably 0.05% or less.

A large amount of Mn lowers the toughness.
Should be no more than 9%. In particular, since Mn is effective as a deoxidizing agent, it is 0.4% or less, more preferably 0.4%, from the viewpoint of improving toughness.
It is preferably at most 2%. Further, it is preferable to add 0.1% or more.

Cr enhances corrosion resistance and tensile strength.
% Or more causes formation of a δ ferrite structure.
If less than 8%, the corrosion resistance and tensile strength are insufficient, so
Cr was determined to be 8 to 13%. Especially from the point of strength 1
0.5 to 12.5% is more preferable.

Mo has the effect of increasing the tensile strength by the action of solid solution strengthening and precipitation strengthening. Mo has an effect of improving the tensile strength, but when it exceeds 3%, it causes the formation of δ ferrite. Therefore, it is limited to more than 1.5 and 3.0% or less. Especially,
1.8-2.7% is more preferable, and 2.0-2.5% is more preferable. Note that W and Co have the same effect as Mo.

In the past, V was usually added to high-strength 12Cr steel. However, in order to obtain high toughness, V should be set to 0.20% or less, or not added to a specific composition. More preferred. It is preferable to make the content less than 0.05% with respect to the case where no addition is made, and the lower limit is 0.01
%. Also, 0.2 for a specific composition
It can be added up to 0%, but the amount added is 0.05%.
% Or more, preferably 0.05 to 0.20%, more preferably 0.07 to 0.15%.

Nb has the effect of precipitating carbides to increase tensile strength and to improve toughness. If the Nb content is less than 0.04%, the effect is insufficient, and if the Nb content is more than 0.24%, harmful δ ferrite is formed. In particular, Nb is 0.06
0.20%, more preferably 0.10% to 0.18%. N
Ta can be added in exactly the same manner as in place of b, or a complex can be added.

Ni has the effect of increasing the low-temperature toughness and preventing the formation of δ ferrite. This effect is achieved by Ni 2.0%
The following is not enough. If the addition exceeds 4%, the martensitic transformation end temperature becomes too low, and a uniform whole martensite structure cannot be obtained. In particular, at 2.1% or more,
More preferably, it is 2.3 to 3.6%. More preferably 2.4
~ 3.2%.

N is effective in improving tensile strength and preventing the formation of δ-ferrite, but if it is less than 0.02%, its effect is not sufficient, and if it exceeds 0.1%, toughness is reduced. In particular, excellent characteristics can be obtained in the range of 0.04 to 0.08%, and more preferably 0.06 to 0.08%. Further, from the balance between strength and toughness, it is preferable to set the N / C ratio to 0.20 to 0.75.

The reduction of Si, P and S has the effect of increasing the low-temperature toughness without impairing the tensile strength, and it is desirable to reduce the reduction as much as possible. From the viewpoint of improving low-temperature toughness, Si 0.1% or less,
P is preferably 0.015% or less and S 0.015% or less.
In particular, Si 0.05% or less, P0.010% or less, S0.0.
010% or less is preferable. The reduction of Sb, Sn and As also has the effect of increasing the low-temperature toughness, and it is desirable to reduce it as much as possible.
015% or less, Sn 0.01% or less, and As0.02
%. In particular, Sb0.001, Sn0.0
05 and As 0.01% or less are desirable. In the present invention, the Mn / Ni ratio is preferably 0.15 or less, more preferably 0.11 or less, and further preferably 0.10 or less.

Further, for the purpose of improving strength and toughness, Co ≦ 10%, Cu ≦ 3%, W ≦ 1.5%, T
i ≦ 0.5%, Zr ≦ 0.1% and rare earth element ≦ 0.2%
May be added.

In the above composition, the amount of C + Nb / Ta is 0.221 to 0.40%, or the amount of 10C + Mo is 3.0 to 5.0.
% Is preferable.

The steam turbine long blade must have high tensile strength and high cycle fatigue strength in order to withstand high centrifugal stress and vibration stress due to high-speed rotation.
Therefore, the metal structure of the blade material, if harmful δ ferrite is present, significantly reduces the fatigue strength. Therefore, the component is adjusted so that the Cr equivalent calculated by the above-mentioned formula becomes 10 or less, and the δ ferrite phase is changed. It has a fully tempered martensite structure that is substantially not included.

Further, in order to obtain a homogeneous and high-strength long blade material of a steam turbine, a refining heat treatment is performed after melting and forging.
After heating and holding at 00 ° C to 1100 ° C, preferably for 0.5 to 3 hours, quenching is performed by rapidly cooling to room temperature.
Two or more tempering heat treatments, each of which is subjected to primary tempering at 570 ° C. for preferably 1 to 6 hours and then cooling to room temperature, followed by secondary tempering at 560 ° C. to 680 ° C. and preferably to 1 to 6 hours and cooling to room temperature. Is applied.

(2) The present invention is applied to the following steam turbine and a power plant using the same.

In the rotor shaft for a high-pressure, medium-pressure and high-medium-pressure integrated steam turbine according to the present invention, the rotor journal portion and the low-temperature region have a weight ratio of C 0.06 to 0.14% and Si 0.10%.
5% or less, Mn 2% or less, Cr 7 to 12%, Ni 0.1
1.0%, V 0.05-0.35%, Nb or Ta 0.01
0.20% or a total amount of Ta and Nb of 0.01 to
0.20%, N 0.005 to 0.1%, one or two of Mo and W is 3.5% or less, B is not added or 0.015% or less, preferably 0.005% or less, more preferably 0.005% or less. 0.0
It consists of martensitic steel containing less than 03% and Co1-10%, and the rotor body has a weight ratio of C0.06-0.1.
4%, Si 0.1% or less, Mn 1% or less, Cr 8-12
%, Ni 0.1 to 1.0%, V 0.05 to 0.35%, Nb
Or Ta 0.01 to 0.20% or Ta and Nb in a total amount of 0.01 to 0.20%, N 0.005 to 0.035%, Mo
And W or 3.5% or less, B 0.005 to
It consists of martensitic steel containing 0.03% and 1-10% Co, and the body has an alloy composition in which the high temperature strength is higher than that of the journal or the weldability of the journal is higher than that of the body.

The present invention relates to a steam turbine power plant equipped with a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine or a high-medium-pressure turbine and a low-pressure turbine. The inlet temperature is 610 to 660 ° C., and the low-pressure turbine has a steam inlet temperature to the first stage blade of 380 to 475.
° C, the rotor shaft exposed to the steam inlet temperature of the high-pressure turbine and the intermediate-pressure turbine, or the rotor shaft and at least one of the moving blade, the stationary blade, and the inner casing are 8 to 13% by weight of Cr and Nb or Ta 0.01. ~
It consists of high-strength martensitic steel containing 0.20%, and the bearing portion of the rotor shaft is made of martensitic steel having lower strength or higher welding than the body.

The present invention has a rotor shaft, a rotor blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam to the rotor blade, and an inner casing for holding the stationary blade. The temperature at which steam enters the first stage of the rotor blade is 60
0-660 ° C and pressure 250 kg / cm ² or more or 150-
A steam turbine comprising a high-pressure, medium-pressure, or high-medium-pressure turbine of 200 kg / cm ² , wherein the rotor shaft or at least the first stage of the rotor blade and the moving blade and the stationary blade flows into the first stage of the moving blade. 1 at a temperature corresponding to
0 ⁵ h creep rupture strength fully tempered martensite containing 0.01 to 0.20% in a total amount of one or two of Cr9～13% and Nb and Ta in weight is 10 kgf / mm ² or more tissue And the inner casing is made of a martensitic cast steel containing 8 to 13% by weight of Cr having a 10 ⁵ hour creep rupture strength of 10 kgf / mm ² or more at a temperature corresponding to the steam temperature. Specifically, the rotor shaft is C 0.05-0.20%, Si 0.15% or less, Mn
0.03 ~ 1.5%, Cr 9.5 ~ 13%, Ni 0.05 ~
1.0%, V 0.05-0.35%, Nb or Ta 0.0
1 to 0.20% or a total amount of Ta and Nb of 0.01 to
0.20%, N 0.005 to 0.06%, Mo and W
3.5% or less, Co1-10%, B0.0
005-0.03%, or Nb 0.01-0.20%
% And more than 0.5% and less than 1.0% of Mo and made of high-strength martensite steel having Fe of 78% or more, and the bearing portion of the rotor shaft has lower strength or higher weldability than the body portion. Made of steel.

According to the present invention, a high-pressure turbine and a medium-pressure turbine, a low-pressure turbine and a low-pressure turbine, or a high-pressure turbine and a low-pressure turbine, and a medium-pressure turbine and a low-pressure turbine are connected. In a steam turbine power plant in which two low-pressure turbines are connected to each other, the high-pressure turbine and the intermediate-pressure turbine or the high- and
00 to 660 ° C (preferably 600 to 620 ° C, 620
630 ° C, 630 ° C to 640 ° C), the low pressure turbine has a steam inlet temperature to the first stage rotor blade of 350 to 4 ° C.
For the range of 00 ° C., at least one of the rotor shaft or rotor shaft exposed to the steam inlet temperature of the high-pressure turbine and the intermediate-pressure turbine or the high-to-medium pressure turbine, and at least one of the first stage of the moving blade and the stationary blade and the inner casing is in weight. The blade length of the last stage rotor blade of the low-pressure turbine is constituted by high-strength martensitic steel containing 8 to 13% of Cr and one or two of Nb and Ta in a total of 0.01 to 0.20%. (Inch) x number of rotations (rpm)] is 125,
It consists of martensitic steel of more than 000.

Further, the present invention has a rotor shaft, a moving blade implanted on the rotor shaft, a stationary blade for guiding the flow of steam to the moving blade, and an inner casing for holding the stationary blade. The temperature at which the steam flows into the first stage of the rotor blade is 600 to 660 ° C and the pressure is 250 kgf / cm ² or more (preferably 246 to 316 kgf / cm ² ) or 170 to 316 kgf / cm ^2.
A steam turbine of 200 kgf / cm ² , wherein the rotor shaft or the rotor shaft and at least the first stage of the moving blade and the stationary blade have respective steam temperatures (preferably 610 ° C., 62
5 ℃, 640 ℃, is 650 ℃, 660 ℃) 10 ⁵ h creep rupture strength at a temperature corresponding to the 10 kgf / mm ² or more (preferably 17 kgf / mm ² or more) Cr9.5～1
3% by weight (preferably 10.5 to 11.5% by weight) of the aforementioned high-strength martensitic steel having a fully tempered martensitic structure, wherein the inner casing has a temperature corresponding to each of the steam temperatures. 10 ⁵ hour creep rupture strength of 10 kgf / mm ² or more (preferably 10.5 kgf / mm ^2
2 or more), which is made of a martensitic cast steel containing 8 to 9.5% by weight of Cr. In the high-to-medium pressure integrated steam turbine that is sent to the medium pressure turbine.

In the high-pressure turbine and the intermediate-pressure turbine or the high-intermediate-pressure integrated steam turbine, at least the first stage of the rotor shaft or the moving blade and the stationary blade has a weight of C0.0.
5 to 0.20%, Si 0.15% or less, Mn 0.05 to
1.5%, Cr 9.5-13%, Ni 0.05-1.0%,
V 0.05 to 0.35%, one or two of Nb and Ta in a total amount of 0.01 to 0.20%, N 0.01 to 0.1%, Mo
And W of 3.5% or less, Co1-10
%, B containing 0.0005-0.03%, and 78% or more of F
e of high strength martensitic steel,
Preferably, it corresponds to a steam temperature of 640 ° C., said inner casing being C 0.06-0.16% by weight, Si 0.5
% Or less, Mn 1% or less, Ni 0.2 to 1.0%, Cr8
-12%, V 0.05-0.35%, Nb 0.01-0.1
5%, N 0.01 to 0.8%, Mo 1% or less, W1 to 4
%, B 0.0005 to 0.003%, and is preferably made of a high-strength martensitic steel having 85% or more of Fe.

In the high-pressure steam turbine according to the present invention,
The rotor blade has at least 9 stages, preferably at least 10 stages, the first stage has a double flow, and the rotor shaft has a bearing center distance.
(L) is 5000 mm or more (preferably 5100 to 6500
mm) and the minimum diameter (D) at the portion where the vane is provided
Is 660 mm or more (preferably 680 to 740 mm), and the (L / D) is 6.8 to 9.9 (preferably 7.9).
To 8.7) of a high-strength martensitic steel containing 9 to 13% by weight of Cr.

In the medium-pressure steam turbine according to the present invention,
The rotor blade has a double flow structure in which each of the rotor blades has six or more stages symmetrically, and a first stage is implanted at the center of the rotor shaft. The rotor shaft has a bearing center distance (L) of 5000 mm or more (preferably 5100 mm or more). 6500 mm) and the minimum diameter (D) at the portion where the stator vanes are provided is 630 mm or more (preferably 650-710 mm), and the (L / D) is 7.0-9.2 (preferably 7 .8 to 8.3)
It is preferably made of a high-strength martensitic steel containing up to 13% by weight.

[0044] In a low-pressure steam turbine having a high-pressure turbine and a medium-pressure turbine separately, the rotor blade has a double flow structure in which each of the blades has six or more stages symmetrically to each other, and a first stage is implanted in the center of the rotor shaft. The rotor shaft has a bearing center distance (L) of 6500 mm or more (preferably 6600 mm).
７7100 mm) and the minimum diameter (D) at the portion where the stator vanes are provided is 750 mm or more (preferably 760 to 900 mm).
mm), and wherein the (L / D) is 7.8 to 10.2 (preferably 8.0 to 8.6), and 3.25 to 4.25% by weight of Ni.
And the final stage rotor blade has a value of [blade length (inch) × rotation speed (rpm)] of 1
12% which is 18,800 or more, more preferably 125,000 or more
It is preferably made of a Cr-based high-strength martensitic steel.

Further, the present invention relates to a high-pressure turbine and an intermediate-pressure turbine, a low-pressure turbine and a low-pressure turbine, or a high-pressure turbine and a low-pressure turbine and an intermediate-pressure turbine and a low-pressure turbine are connected. In a steam turbine power plant in which two low-pressure turbines are connected, the high-pressure turbine and the medium-pressure turbine or the high-medium-pressure turbine have a steam inlet temperature to the first stage rotor blade of 600.
660 ° C., the low-pressure turbine has a steam inlet temperature to the first-stage rotor blade of 350 to 400 ° C., and the metal temperature of the first-stage rotor blade implanted portion of the rotor shaft of the high-pressure turbine and the metal temperature of the first-stage rotor blade are lower than that of the high-pressure turbine. 40 ° C. or more from the steam inlet temperature to the first stage blade (preferably 20 to
Lower the temperature by 35 ° C) so that the temperature of the first stage rotor blades on the rotor shaft of the intermediate pressure turbine and the metal temperature of the first stage rotor blades are at least 75 ° C higher than the steam inlet temperature to the first stage rotor blades of the intermediate pressure turbine. (Preferably 50-
The rotor shafts of the high-pressure turbine and the intermediate-pressure turbine and at least the first stage rotor blades are made of the above-mentioned martensitic steel containing 9.5 to 13% by weight of Cr. When the value of the stage rotor is [wing length (inch) x rotation speed (rpm)] is 118,800 or more,
More preferably, it is made of 12% Cr-based high-strength martensitic steel of 125,000 or more.

Further, the present invention provides a coal-fired boiler, a steam turbine driven by steam obtained by the boiler, and a single or two steam turbine driven by the steam turbine.
In a coal-fired thermal power plant comprising at least two, preferably two generators having a power output of at least 1000 MW, said steam turbine is a high-pressure turbine and a medium-pressure turbine and a low-pressure turbine and a low-pressure turbine, or a high-pressure turbine and a low-pressure turbine. And a medium-pressure turbine and a low-pressure turbine are connected, or a high-medium-pressure turbine is connected to one or two tandem low-pressure turbines, and the high-pressure turbine and the medium-pressure turbine or the high-medium-pressure turbine The inlet temperature is 600 to 660 ° C and the low-pressure turbine has a steam inlet temperature to the first stage rotor blade of 350 to 400 ° C, and the superheater of the boiler is 3 ° C or more higher than the steam inlet temperature to the first stage rotor blade of the high-pressure turbine. (Preferably 3-10 ° C,
More preferably, the steam heated to a high temperature flows into the first stage rotor of the high-pressure turbine, and the steam exiting the high-pressure turbine is sent to the first stage rotor of the intermediate-pressure turbine by the reheater of the boiler. Is heated to a temperature 2 ° C. or higher (preferably 2 to 10 ° C., and more preferably 2 to 5 ° C.) higher than the steam inlet temperature of the steam turbine, flows into the first stage moving blades of the intermediate-pressure turbine, and exits from the intermediate-pressure turbine. Is preferably 3 ° C. or more (preferably 3 to 10 ° C.) from the steam inlet temperature to the first stage rotor blade of the low pressure turbine by the boiler's economizer.
° C, more preferably 3 to 6 ° C) and heated to a high temperature to flow into the first stage blade of the low-pressure turbine, and the last stage blade of the low-pressure turbine is [blade length (inch) x rotation speed
(rpm)) is 118,800 or more, more preferably 125,000
It is preferable to use the above-described 12% Cr-based high-strength martensitic steel.

Further, in the low-pressure steam turbine according to the present invention, the temperature of the steam inlet to the first-stage bucket may be 350 to 400.
° C (preferably from 360 to 380 ° C), and the rotor shaft is C 0.2 to 0.3%, Si 0.05% by weight.
Below, Mn 0.1% or less, Ni 3.25-4.25%, C
r 1.25 to 2.25%, Mo 0.07 to 0.20%, V
It is preferably made of a low alloy steel having a content of 0.07 to 0.2% and Fe of 92.5% or more.

In the above-mentioned high-pressure steam turbine, the moving blade has 7 stages or more (preferably 9 to 12 stages), and the blade portion has a length of 25 to 180 mm from the upstream side to the downstream side of the steam flow. The diameter of the implanted portion of the moving blade is larger than the diameter of the portion corresponding to the stationary blade, and the axial width of the implanted portion is three or more steps (preferably 4 to 7 steps) on the downstream side compared with the upstream side. Large, and the ratio to the wing length is 0.2 to 1.6 (preferably 0.30 to
(1.30, more preferably 0.65 to 0.95), and preferably decreases from the upstream side to the downstream side.

Further, in the above high-pressure steam turbine,
According to the present invention, the moving blade has 7 stages or more (preferably 9 stages or more) and the blade length is 25 to 25 from the upstream side to the downstream side of the steam flow.
180mm, the ratio of the wing length of each adjacent stage is 2.3
Hereinafter, it is preferable that the ratio is gradually increased on the downstream side, and the length of the wing portion is larger on the downstream side than on the upstream side.

Further, in the high-pressure steam turbine described above,
According to the present invention, the moving blade has 7 stages or more (preferably 9 stages or more) and the blade length is 25 to 25 from the upstream side to the downstream side of the steam flow.
The rotor shaft has a width in the axial direction of a portion corresponding to the stationary blade portion of the rotor shaft, the downstream side being smaller than the upstream side by two or more stages (preferably 2 to 4 stages) in a stepwise manner. It is preferable that the ratio gradually decreases toward the downstream side when the ratio to the side wing length is 4.5 or less.

In the above-mentioned medium-pressure steam turbine, the moving blade has a double flow structure having 6 or more stages (preferably 6 to 9 stages) in a symmetrical manner, and the blade length is 60 to 300 mm from the upstream side to the downstream side of the steam flow. The diameter of the implanted portion of the rotor blade of the rotor shaft is larger than the diameter of a portion corresponding to the stationary blade, and the axial width of the implanted portion is two or more steps (preferably 2 steps) at the downstream side as compared to the upstream side. ~ 6 stages), and the ratio to the wing length is 0.1%.
It is preferably from 35 to 0.80 (preferably from 0.5 to 0.7) and decreases from the upstream side to the downstream side.

Further, according to the present invention, in the above-mentioned medium-pressure steam turbine, the moving blade has a double-flow structure having six or more stages symmetrically in a left-right direction, and the blade length is 60 from the upstream side to the downstream side of the steam flow.
And the length of the adjacent wings is larger on the downstream side than on the upstream side, and the ratio is 1.3 or less (preferably 1.1 to 1.2) and gradually decreases on the downstream side. Preferably it is larger.

Further, in the present invention, in the above-mentioned medium-pressure steam turbine, the moving blade has a double flow structure having six or more stages symmetrically in a left-right direction, and a blade portion length of 60 from upstream to downstream of the steam flow.
And the axial width of the portion of the rotor shaft corresponding to the stationary blade portion is gradually reduced by two or more stages (preferably 3 to 6 stages) on the downstream side as compared with the upstream side. The ratio of the moving blade to the downstream wing length is 0.
It is preferable that the ratio gradually decreases in the range of 80 to 2.50 (preferably 1.0 to 2.0) toward the downstream side.

The present invention relates to a low-pressure steam turbine in a power plant in which the above-described high-pressure turbine and medium-pressure turbine are separately provided, wherein the moving blades have six or more stages (preferably eight to ten stages) in left-right symmetry. The double flow structure and the wing length are from 80 to 1300 from upstream to downstream of the steam flow.
mm, the diameter of the implanted portion of the rotor blade of the rotor shaft is larger than the diameter of a portion corresponding to the stationary blade, and the axial width of the implanted portion is preferably three or more steps in the downstream side as compared with the upstream side ( (More preferably 4 to 7 steps), and the ratio to the wing length is 0.2.
It is preferably from 0.7 to 0.7 (preferably from 0.3 to 0.55), decreasing from the upstream side to the downstream side.

Further, the present invention relates to a low-pressure steam turbine having the above-mentioned high-pressure turbine and medium-pressure turbine separately, wherein the moving blade has a double-flow structure having six or more stages in each case in a symmetrical manner, and a blade length of the steam flow. It has 80 to 1300 mm from the upstream side to the downstream side, and the wing length of each adjacent stage is larger on the downstream side than on the upstream side, and the ratio is 1.2 to 1.8 (preferably 1.0. Preferably, the ratio gradually increases on the downstream side in the range of 4 to 1.6).

Further, the present invention provides the low-pressure steam turbine according to the above-mentioned low-pressure steam turbine, wherein the rotor blades are symmetrically arranged in each of at least six stages, preferably at least eight stages, and the blade portion has a blade length from upstream to downstream of the steam flow. 80 to 1300 mm, and the axial width of the portion corresponding to the stationary blade portion of the rotor shaft is preferably larger in three stages or more (more preferably 4 to 7 stages) on the downstream side than on the upstream side. The ratio of the moving blade to the length of the adjacent downstream blade portion is 0.2 to 1.4 (preferably 0.25 to 1.25, particularly 0.2.
It is preferable that the ratio gradually decreases in the range from 5 to 0.9) toward the downstream side.

In the above-described high-pressure steam turbine, the rotor blade has at least seven stages, preferably at least nine stages, and the rotor shaft has a portion corresponding to the stationary blade and having a diameter corresponding to the blade implant portion. Smaller than the diameter, the axial width of the diameter corresponding to the stationary blade is gradually increased in two or more stages (preferably two to four stages) on the upstream side of the steam flow as compared with the downstream side, The width between the last stage of the rotor blade and the front thereof is 0.75 to 0.95 times (preferably 0.8 to 0.9) the width between the second and third stages of the rotor blade. More preferably 0.82 to 0.88), and the axial width of the rotor shaft implant portion at the downstream side of the steam flow is three or more stages (preferably 4 to 0.8). 7
And the axial width of the last stage of the rotor blade is 1 to 2 with respect to the axial width of the second stage.
It is preferably a factor of (preferably 1.4 to 1.7 times).

In the above-described medium-pressure steam turbine, the rotor blade has six or more stages, and the rotor shaft has a portion corresponding to the stationary blade having a diameter smaller than that of the portion corresponding to the rotor blade implantation portion. The axial width of the diameter corresponding to the stationary blade is preferably increased stepwise at two or more stages (more preferably 3 to 6 stages) on the upstream side of the steam flow as compared with the downstream side. The width between the last stage and the front of the blade is 0.5 to 0.5 of the width between the first stage and the second stage of the bucket.
0.9 times (preferably 0.65 to 0.75 times), and the width of the rotor shaft in the axial direction of the moving blade portion implanted portion is preferably two stages on the downstream side of the steam flow as compared with the upstream side. As described above (preferably in 3 to 6 stages), the axial width of the last stage of the rotor blade is 0.8 to 2 times (preferably 1 to 2) the axial width of the first stage. .2 to 1.5
Times).

In the low-pressure steam turbine described above, the moving blade has a double flow structure having eight or more stages symmetrically, and the rotor shaft has a portion corresponding to the stationary blade and having a diameter corresponding to the moving blade implanted portion. And the axial width of the diameter corresponding to the stator vanes is preferably larger at three or more stages (more preferably at four to seven stages) on the upstream side of the steam flow than on the downstream side. The width between the last stage of the moving blade and the front of the last stage is equal to the width of the first stage of the moving blade.
1.5 to 3.0 times the width between the steps (preferably 2.0 to 3.0 times)
2.7 times), and the width of the rotor shaft in the axial direction of the moving blade portion implantation portion is preferably three or more stages (more preferably four to seven stages) on the downstream side of the steam flow as compared with the upstream side. The axial width of the last stage of the rotor blade is 5 to 8 times (preferably 6.2 to 7.0 times) the axial width of the first stage. preferable.

The structure of the high-pressure, medium-pressure or high-medium-pressure integrated turbine and the low-pressure turbine described above can be the same at any of the steam temperatures of 610 to 660 ° C.

In the rotor material of the present invention, the Cr equivalent calculated by the following equation is adjusted to 4 to 8 in order to obtain high high-temperature strength, low-temperature toughness and high fatigue strength as a fully tempered martensite structure. Is preferred.

In the high / intermediate pressure integrated steam turbine according to the present invention, the high pressure side moving blade has 7 stages or more, preferably 8 stages or more, and the medium pressure side moving blade has 5 or more stages, preferably 6 or more stages. The distance (L) between the bearing centers is 6000 mm or more (preferably 6100 to 7000 mm), and the minimum diameter (D) at the portion where the stationary blade is provided is 660 mm or more (preferably 620 to 760 mm). D) is 8.0
It is preferably made of a high-strength martensitic steel containing 9 to 13% by weight of Cr as described above, which is 〜11.3 (preferably 9.0 to 10.0).

The low-pressure steam turbine for the high-medium pressure integrated turbine of the present invention has the following requirements.

In the low-pressure steam turbine, the rotor blades have left-right symmetrical stages of 5 or more, preferably 6 or more, and have a double-flow structure in which the first stage is implanted at the center of the rotor shaft. Bearing center distance (L) is 65
00 mm or more (preferably 6600 to 7500 mm) and the minimum diameter (D) at the portion where the stationary blade is provided is 750 mm or more
(Preferably 760 to 900 mm), and the (L / D)
Is 7.2 to 10.0 (preferably 8.0 to 9.0).
Ni-Cr-Mo containing 3.25 to 4.25% by weight
-V low alloy steel, the last stage blade is [wing length (inch)
× number of rotations (rpm)] is 118,800 or more, more preferably 1
It is preferable to use a 12% Cr-based high-strength martensitic steel of 25,000 or more.

In the rotor shaft, the diameter (D) of the stator blade portion is 750 to 1300 mm, the distance (L) between the bearing centers is 5.0 to 9.5 times that of D, and the weight is C0.2 to C2. 0.
3%, Si 0.05% or less, Mn 0.1% or less, Ni3.
0-4.5%, Cr 1.25-2.25%, Mo 0.07-
It consists of a low alloy steel having 0.20%, V 0.07 to 0.2% and Fe of 92.5% or more.

The blade has a double-flow structure having five or more stages, preferably six or more stages in a bilaterally symmetrical manner, and the blade length is within a range of 80 to 1300 mm from the upstream side to the downstream side of the steam flow. The diameter of the implanted portion of the rotor blade is larger than the diameter of the portion corresponding to the stationary blade, the width of the root portion in the axial direction of the implanted portion is larger than the width of the blade implanted portion in a divergent manner, and from the downstream side to the upstream side. It gradually decreases, and the ratio to the wing length is 0.1.
25-0.80.

The blade has a double-flow structure having at least 5 stages, preferably at least 6 stages, in a symmetrical manner, and the blade portion length is within the range of 80 to 1300 mm from the upstream side to the downstream side of the steam flow. The length of the wing is larger on the downstream side than on the upstream side, and the ratio is 1.2 to 1.7.
In the range, the wing portion length is gradually increased on the downstream side.

The moving blade has a double flow structure having at least five stages, preferably at least six stages, in a symmetrical manner, and the blade length increases from upstream to downstream of the steam flow.
0 mm, and the axial width of the root portion of the implanted portion of the rotor blade of the rotor shaft is larger at at least three stages on the downstream side than on the upstream side. It is getting bigger.

The high and medium pressure integrated steam turbine of the present invention has the following configuration.

The moving blade on the high pressure side has at least seven stages and a blade length of 40 to 200 mm from the upstream side to the downstream side of the steam flow. The width of the root portion in the axial direction of the implanted portion is larger stepwise on the upstream side than on the downstream side, and the ratio to the wing length is 0.20 to 1.
60, preferably from 0.25 to 1.30, increasing from the upstream side to the downstream side, the blades on the medium pressure side have five or more stages symmetrically in the left-right direction, and the blade length is on the upstream side of the steam flow. From 100 to 350 mm on the downstream side, the impeller diameter of the rotor blade of the rotor shaft is larger than the diameter of the portion corresponding to the stationary blade, and the axial width of the root portion of the implant is the same as that of the rotor except for the last stage. The downstream side is larger than the upstream side, and the ratio to the wing length is 0.35 to 0.8.
0, and preferably from 0.40 to 0.75, decreasing from the upstream side to the downstream side.

The blade has at least seven stages and a blade length of 25 to 200 mm from the upstream side to the downstream side of the steam flow, and the ratio of the blade length of each adjacent stage is 1.05 to 1.35. The blade length is gradually increased on the downstream side as compared with the upstream side, and the blades in the intermediate pressure section have five or more stages, and the blade length is 100 to 100 downstream from the upstream side of the steam flow. ~ 350mm
The length of the adjacent wings is greater on the downstream side than on the upstream side, and the ratio is 1.10 to 1.30, and gradually increases on the downstream side.

The rotor blade on the high pressure side has six or more stages, preferably seven or more stages, and the rotor shaft has a portion corresponding to the stationary blade having a diameter smaller than a diameter of a portion corresponding to the rotor blade implant. The axial width of the root portion of the implanted portion of the blade is largest at the first stage, and is gradually increased in two or more stages, preferably three or more stages from the upstream side to the downstream side of the steam flow, The rotor blade has five or more stages, and the rotor shaft has a portion corresponding to the stationary blade having a diameter smaller than that of the portion corresponding to the rotor blade implanted portion, and an axial direction of a root portion of the implanted portion of the rotor blade. The upstream side of the steam flow preferably differs stepwise in four or more stages as compared with the downstream side, and the first stage of the blade is larger than the second stage, the last stage is larger than the other stages, and the first stage and the second stage are different. The stage is widening.

The length of the last stage blade portion of the low pressure turbine according to the present invention is 838 mm (33 ″) or more, preferably 914 mm (3 ″).
6 ″) or more, more preferably 965 mm (38 ″) or more, 3600 rpm steam turbine and low pressure turbine final stage blade length is 1016 mm (40 ″) or more, preferably 1092 mm or more.
mm (43 ") or more, more preferably 1168 mm (46") or more, and a 3000 rpm steam turbine, and the value of [wing length (inch) × number of revolutions (rpm)] is 118,800 or more, preferably 1
It is 25,000 or more, more preferably 138,000 or more.

Further, in the casing material made of the heat-resistant cast steel of the present invention, the tempered martensite (δ
(Ferrite 5% or less) In order to obtain a high temperature adjustment, a low temperature toughness and a high fatigue strength by adjusting the alloy composition so as to have a microstructure, the Cr equivalent calculated assuming that the content of each element of the following formula is 4% by weight is 4%. It is preferable to adjust the components to 10 to 10.

Cr equivalent = Cr + 6Si + 4Mo + 1.5
W + 11V + 5Nb-40C-30N-30B-2Mn
-4Ni-2Co + 2.5Ta In the 12Cr heat resistant steel of the present invention, especially when used in steam at 621 ° C. or more, 625 ° C., 10 ⁵ h creep rupture strength 10 kgf / mm ² or more, room temperature impact absorption energy 1 kgf It is preferred to be -m or more.

(3) High-pressure and medium-pressure or high-to-medium pressure integrated rotor, blade, nozzle, internal casing fastening bolt, and ferrite heat-resistant steel constituting the first stage diaphragm of the medium pressure part of the steam turbine of the present invention at 600 to 660 ° C. The reason for the limitation of the composition will be described. C secures hardenability,
It is an element indispensable for increasing the high-temperature strength by precipitating carbides during the tempering heat treatment process. In addition, 0.05% or more is necessary to obtain high tensile strength, but 0.20%
Exceeding the temperature will cause the metal structure to become unstable when exposed to high temperatures for a long time, and will reduce the long-term creep rupture strength.
It is limited to 0.05 to 0.20%. Desirably 0.08 ~
0.13%, and particularly preferably 0.09 to 0.12%.

Mn is added for a deoxidizing agent and the like, and its effect is achieved by adding a small amount, and adding a large amount exceeding 1.5% is not preferable because it reduces the creep rupture strength. Especially 0.03 to 0.20% or 0.3 to 0.7%
Is preferable, and 0.35 to 0.65% is more preferable for the larger one. Higher strength is obtained with less Mn. In addition, the higher the Mn content, the better the workability.

Although Si is also added as a deoxidizing agent, according to a steelmaking technique such as vacuum C deoxidizing method, Si deoxidizing is unnecessary. By lowering Si, there is an effect of preventing formation of a harmful δ ferrite structure and preventing a decrease in toughness due to segregation at crystal grain boundaries. Therefore, when adding, 0.1.
It must be suppressed to 15% or less, preferably 0.07%
Or less, and particularly preferably less than 0.04%.

Ni is a very effective element for increasing the toughness and preventing the formation of δ ferrite.
If it is less than 5%, the effect is not sufficient, and if it exceeds 1.0%, the creep rupture strength is lowered, so that it is not preferable. In particular, it is preferably 0.2 to 0.7%, more preferably 0.4 to 0.65%.

Cr is an element indispensable for enhancing high-temperature strength and high-temperature oxidation resistance, and at least 9% is required.
If it exceeds, a harmful δ ferrite structure is formed and the high-temperature strength and toughness are reduced, so that the content is limited to 9 to 12%. In particular, it is preferably 10 to 12%, more preferably 10.8 to 11.8%.

The addition of Mo is performed to improve the high-temperature strength. When containing Ta, 3.5% or less, preferably 1%
Below, when Nb is contained, if it is less than 0.5%, sufficient toughness and fatigue strength cannot be obtained, and it is contained more than 0.5% to 3.5% or less, preferably less than 1.0%. Especially 0.55
~ 0.85% is preferred.

W suppresses coarsening and coarsening of carbides at a high temperature and solid-solution strengthens the matrix, so that it has an effect of remarkably increasing the high-temperature long-term strength of 620 ° C. or more. 620
1 to 1.5% below ℃, 1.6 to 2.30% below 630 ° C.
0%, 2.1-2.5% below 640 ° C, 2.6-3.0% below 650 ° C, 3.1-3.5 below 660 ° C.
% Is preferable. When W exceeds 3.5%, δ
Since ferrite is formed and toughness is reduced, the content is limited to 3.5% or less, preferably 1 to 3.5%. Particularly preferably, it is 1 to 3%, more preferably 1.5 to 3.0%, and further preferably 2.0 to 2.7%.

V has the effect of increasing the creep rupture strength by precipitating carbonitrides of V, but if it is less than 0.05%, the effect is insufficient, and if it exceeds 0.35%, δ ferrite is formed and the fatigue strength is increased. Lower. In particular, 0.10 to 0.25% is preferable, and 0.15 to 0.23% is more preferable.

Nb and Ta may be added alone or in combination.
It is a very effective element for precipitating NbC and TaC carbides and increasing the high-temperature strength. However, if added in an excessively large amount, coarse eutectic NbC and TaC carbides are generated, especially in large ingots, and the strength is rather reduced. Therefore, it is necessary to suppress the content of δ ferrite alone or in combination to 0.20% or less, since this may cause precipitation of δ ferrite which lowers the fatigue strength. Also 0.
If it is less than 01%, the effect is insufficient. Especially 0.02 ~
0.15% is more preferable, and 0.04 to 0.10% is more preferable. C
o is an important element that distinguishes the present invention from the conventional invention. In the present invention, the high temperature strength is remarkably improved by the addition of Co, and the toughness is also increased. This is considered to be due to the interaction with W, and is a characteristic phenomenon in the alloy of the present invention containing 1% or more of W. In order to realize such an effect of Co, Co in the alloy of the present invention is used.
The lower limit of is 1.0%, but not only does a greater effect not be obtained even if added excessively, but also the ductility is reduced,
The upper limit is 10%. Desirably, 1-3% for 600-620 ° C, 3.5-4.5% for 630 ° C,
5-6% for 640 ° C, 6.60% for 650 ° C.
5 to 7.5%, and preferably 8 to 9% for 660 ° C.

N is also an important element that distinguishes the present invention from the prior art. N is effective in improving the creep rupture strength and preventing the formation of the δ ferrite structure, but is effective at 0.0.
If it is less than 1%, its effect is not sufficient, and if it exceeds 0.05%, the toughness is reduced and the creep rupture strength is also reduced. In particular, 0.01-0.03% is more preferably 0.015-
0.025% is preferred.

[0086] B is a solid solution in the grain boundary strength effects and M ₂₃ C ₆ carbide is effective to increase the high-temperature strength by the action preventing the aggregation and coarsening of M ₂₃ C ₆ type carbide, added in excess of 0.001% Is effective, but if it exceeds 0.03%, the weldability and forgeability are impaired, so it is limited to 0.001 to 0.03%. Desirably 0.001 to 0.01%, or 0.01 to 0.01%
0.02% is preferred.

The addition of Ti and Zr has the effect of increasing toughness, and sufficient effects can be obtained by adding Ti 0.1% or less and Zr 0.1% or less alone or in combination.

The heat-resistant steel according to the present invention contains 0.001 of rare earth elements such as La and Ce, Ca, Mg and Y alone or in combination.
０0.03%. These elements provide particularly strong deoxidation, have a desulfurizing action, and can improve toughness. Preferably 0.003-0.010%
It is.

The first stage of the rotor shaft and at least one of the moving blade and the stationary blade in the present invention has a C of 0.09 to 0.20%, a Si of 0.15% or less, and a Mn of 0.05 to 5 for steam temperatures of 620 to 630 ° C. 1.0%, Cr 9.5 to 12.5%, N
i 0.1 to 1.0%, V 0.05 to 0.30%, N 0.01
0.06%, Nb or Ta 0.02 to 0.08% or T
a and Nb total amount 0.02-0.08%, Mo and W 1
Species or two are less than 3.5%, preferably the former is less than 1.0% and the latter is 2-3.5%. Furthermore, Co2
4.5%, B 0.001-0.030%, 77% or more of F
It is preferable to use a steel made of steel having a fully tempered martensitic structure having e. Also, 635-660
With respect to the steam temperature of ° C., the above-mentioned amount of Co is set to 5 to 8%,
It is preferable to be constituted by a steel having a fully tempered martensite structure having 78% or more of Fe. In particular, high strength can be obtained by reducing the Mn content to 0.03 to 0.2% and the B content to 0.001 to 0.01% at both temperatures.

The Cr equivalent obtained by the following equation is preferably 4 to 10.5, particularly 6.5 to 9.5 with respect to the rotor shaft, and the same applies to other components.

In the high-pressure and medium-pressure rotor materials of the steam turbine of the present invention, when the δ ferrite structure is mixed, the fatigue strength and the toughness are reduced, so that the structure is preferably a uniform tempered martensite structure. In order to obtain a tempered martensite structure, the Cr equivalent calculated by the above equation must be reduced to 10 or less by adjusting the components. If the Cr equivalent is too low, the creep rupture strength decreases, so it must be 4 or more. In particular, a Cr equivalent of 5 to 8 is preferable.

In the rotor of the present invention, an alloy material having a target composition is melted in an electric furnace, carbon is deoxidized in a vacuum, cast into a mold, and forged to produce an electrode rod. This electrode rod is redissolved in electroslag, and forged into a rotor shape and molded. This forging must be performed at a temperature of 1150 ° C. or less in order to prevent forging cracks. Further, the forged steel can be used in steam at 620 ° C. or higher by performing a quenching process of heating to 1000 ° C. to 1100 ° C. and quenching twice in the order of 550 ° C. to 650 ° C. and 670 ° C. to 770 ° C. after annealing heat treatment. A steam turbine rotor can be manufactured.

The blade, nozzle, internal casing tightening bolt, and intermediate pressure section first stage diaphragm of the present invention are melted by vacuum melting and cast in a mold under vacuum to produce an ingot. The ingot is hot forged into a predetermined shape at the same temperature as described above, heated at 1050 to 1150 ° C, water-cooled or oil-quenched, then tempered at 700 to 800 ° C, and cut into a blade having a desired shape. Become. Vacuum melting is performed under 10- ¹ ~10- ⁴ mmHg. In particular, the heat-resistant steel in the present invention can be used in all stages of the blades and nozzles in the high-pressure section and the medium-pressure section, but is particularly necessary in the first step of both.

(4) The steam turbine rotor shaft made of 12% by weight Cr-based martensite steel according to the present invention preferably has a build-up welded layer having high bearing properties formed on the surface of the base material forming the journal portion. Preferably, the build-up welding layer of 3 to 10 layers is formed using a welding material consisting of, and the Cr amount of the welding material from the initial layer to any of the second to fourth layers is sequentially reduced and The fourth and subsequent layers are welded using a welding material made of steel having the same Cr content, and the Cr content of the welding material used for welding the first layer is reduced by about 2 to 6% by weight from the Cr content of the base material. The Cr content of the fourth and subsequent welding layers is 0.5 to 3% by weight (preferably 1 to 3% by weight).
2.5% by weight).

In the present invention, overlay welding is preferable for improving the bearing characteristics of the journal portion in that the safety is the highest. Further, a sleeve made of a low alloy steel having a Cr content of 1 to 3% may be formed by shrink fitting or fitting.

To increase the number of welding layers and gradually reduce the Cr content, three or more layers are preferable, and even more than ten layers cannot be obtained. As an example, about 18 in the final finish
mm thickness is required. In order to form such a thickness, at least five build-up weld layers are preferable even if the final finishing allowance by cutting is excluded. The third and subsequent layers preferably have a tempered martensite structure mainly and have carbides precipitated. In particular, the weight of the composition of the fourth and subsequent welding layers is C
0.01-0.1%, Si 0.3-1%, Mn 0.3-1.5
%, 0.5 to 3% of Cr, and 0.1 to 1.5% of Mo.

(5) The high pressure turbine, the intermediate pressure turbine, the internal casing control valve valve box, the combined reheat valve valve box, the main steam reed pipe, the main steam inlet pipe, the reheat inlet pipe, and the high pressure turbine of the present invention. The reasons for limiting the composition of the heat-resistant ferritic steel constituting the nozzle box, the first stage diaphragm of the intermediate pressure turbine, the main steam inlet flange of the high pressure turbine, the elbow, and the main steam stop valve will be described.

In the case of a heat-resistant ferritic cast steel casing material, in particular, by adjusting the Ni / W ratio to 0.25 to 0.75, the super-supercritical turbine high-pressure and medium-pressure internal casing of 621 ° C. and 250 kgf / cm ² or more are used. 625 ° C, required for main steam stop valve and control valve casing
A heat-resistant cast steel casing material having a 10 ⁵ h creep rupture strength of 9 kgf / mm ² or more and a shock absorption energy at room temperature of 1 kgf-m or more can be obtained.

In the heat-resistant ferritic cast steel casing material of the present invention, in order to obtain high high-temperature strength, low-temperature toughness, and high fatigue strength, the Cr equivalent calculated by the above-mentioned formula is set to 4 to 4.
It is preferable to adjust the components to 10.

In the 12Cr heat resistant steel of the present invention, 62
625 ° C, 10 ⁵
h The creep rupture strength must be 9 kgf / mm ² or more, and the impact absorption energy at room temperature must be 1 kgf-m or more. Furthermore,
To ensure higher reliability, 625 ° C., 10 ⁵
h The creep rupture strength is preferably 10 kgf / mm ² or more, and the impact absorption energy at room temperature is 2 kgf-m or more.

C is 0.06% to obtain high tensile strength.
The above elements are necessary. However, if the content exceeds 0.16%, the metal structure becomes unstable when exposed to a high temperature for a long time, and the creep rupture strength is reduced for a long time.
Limited to 6%. In particular, 0.09 to 0.14% is preferable.

N has the effect of improving the creep rupture strength and preventing the formation of the δ ferrite structure. However, if it is less than 0.01%, the effect is not sufficient, and if it exceeds 0.1%, there is no remarkable effect. Conversely, it reduces toughness and creep rupture strength. In particular, 0.02 to 0.06% is preferable.

Mn is added as a deoxidizing agent.
The effect can be achieved with a small amount of addition, and a large amount of more than 1% lowers the creep rupture strength, especially from 0.4 to 0.7.
% Is preferred.

Although Si is also added as a deoxidizing agent, according to steelmaking techniques such as vacuum C deoxidizing method, Si deoxidizing is unnecessary. Also, lowering Si has an effect of preventing formation of a harmful δ ferrite structure. Therefore, when it is added, it must be suppressed to 0.5% or less, especially 0.5%.
1-0.4% is preferred.

V has the effect of increasing the creep rupture strength, but if it is less than 0.05%, the effect is insufficient and 0.35%
If the ratio exceeds δ, δ ferrite is formed to lower the fatigue strength. In particular, 0.15 to 0.25% is preferable.

Nb is a very effective element for increasing the high-temperature strength. However, if it is added in an excessively large amount, coarse eutectic Nb carbides are generated, especially in large steel ingots, which rather lowers the strength or reduces the fatigue strength. Must be suppressed to 0.15% or less because it causes δ ferrite to precipitate.
On the other hand, if the content of Nb is less than 0.01%, the effect is insufficient. Especially in the case of large steel ingots, 0.02 to 0.1% is more preferable.
~ 0.08% is preferred.

Ni is a very effective element for increasing the toughness and preventing the formation of δ ferrite.
%, The effect is not sufficient, and the addition exceeding 1.0% is not preferable because it lowers the creep rupture strength.
Particularly, it is preferably from 0.4 to 0.8%.

Cr has the effect of improving high strength and high-temperature oxidation. If it exceeds 12%, a harmful δ ferrite structure is formed, and if it is less than 8%, the oxidation resistance to high-temperature and high-pressure steam becomes insufficient. Further, the addition of Cr has the effect of increasing the creep rupture strength, but the excessive addition causes the formation of a harmful δ ferrite structure and a decrease in toughness. Especially 8.
0-10%, more preferably 8.5-9.5%.

W has the effect of significantly increasing the high-temperature long-time strength. If W is less than 1%, the effect is insufficient for heat-resistant steel used at 620 to 660 ° C. If W exceeds 4%, the toughness decreases. 1.0-1.5 at 620 ° C
%, 1.6-2.0% at 630 ° C, 2.1% at 640 ° C
~ 2.5%, 2.6-3.0% for 650 ° C, 66
At 0 ° C, 3.1 to 3.5% is preferred.

W and Ni have a correlation with each other, and Ni /
By setting the W ratio to 0.25 to 0.75, high strength and toughness can be obtained.

The addition of Mo is performed to improve the high-temperature strength. However, when the content of W exceeds 1% as in the cast steel of the present invention, the addition of Mo of 1.5% or more lowers the toughness and fatigue strength. Therefore, the content of Mo is preferably 1.5% or less. 0.
8%, more preferably 0.55 to 0.70%.

The addition of Ta, Ti and Zr has the effect of increasing toughness, and sufficient effects can be obtained by adding Ta 0.15% or less, Ti 0.1% or less and Zr 0.1% or less alone or in combination. When 0.1% or more of Ta is added, N
The addition of b can be omitted.

In the heat-resistant cast steel casing material of the present invention, if the δ ferrite structure is mixed, the fatigue strength and the toughness are reduced, and therefore, the structure is preferably a uniform tempered martensite structure. In order to obtain a tempered martensite structure, the Cr equivalent calculated by the above equation must be reduced to 10 or less by adjusting the components. If the Cr equivalent is too low, the creep rupture strength decreases, so it must be 4 or more. Particularly, a Cr equivalent of 6 to 9 is preferable.

The addition of B significantly increases the high temperature (620 ° C. or higher) creep rupture strength. If the B content exceeds 0.003%, the weldability deteriorates, so the upper limit is limited to 0.003%. In particular, the upper limit of the B content of the large casing is 0.0.
028%, more preferably 0.0005 to 0.0025%, particularly 0.001 to 0.002%.

Since the casing covers high-pressure steam of 620 ° C. or higher, a high stress acts due to the internal pressure. Therefore, from the viewpoint of preventing creep rupture, a creep rupture strength of 10 ⁵ h of 10 kgf / mm ² or more is required. In addition, at the time of startup, thermal stress acts when the metal temperature is low, so that room temperature impact absorption energy of 1 kgf-m or more is required from the viewpoint of preventing brittle fracture. On the higher temperature side, strengthening can be achieved by containing 10% or less of Co. In particular, 1-2% for 620, 2.5-3.5% for 630 ° C, 4-5% for 640 ° C, 6%
5.5 to 6.5% for 50 ° C and 7 to 8% for 660 ° C are preferred. At 600 to 620 ° C, it may not be added.

To produce a casing with few defects,
Since the weight of the ingot becomes as large as about 50 tons, advanced manufacturing technology is required. The heat-resistant ferritic cast steel casing material of the present invention can be made sound by melting an alloy material having a target composition in an electric furnace, refining the ladle, and then casting it in a sand mold. By performing sufficient refining and deoxidation before casting, casting defects such as shrinkage cavities can be reduced.

The above cast steel is heated at 1000 to 1150 ° C.
A steam turbine that can be used in steam at 621 ° C or higher by performing normalizing heat treatment of heating to 1000 to 1100 ° C and quenching after annealing heat treatment, and tempering twice in the order of 550 to 750 ° C and 670 to 770 ° C. Casing can be manufactured.
If the annealing and normalizing temperatures are lower than 1000 ° C., the carbonitrides cannot be sufficiently dissolved, and if they are too high, the crystal grains become coarse. In addition, the twice-tempering completely decomposes the retained austenite and can provide a uniform tempered martensite structure. A steam turbine that can be used in steam at 620 ° C. or higher by producing 625 ° C. and 10 ⁵ h creep rupture strength of 10 kgf / mm ² or more and room temperature impact absorption energy of 1 kgf-m or more by manufacturing by the above method. Can be made into a casing.

If O exceeds 0.015%, the high-temperature strength and toughness are reduced. Therefore, O is preferably 0.015% or less, particularly preferably 0.010% or less.

The casing in the present invention has the above-mentioned Cr equivalent and preferably has a δ ferrite content of 5% or less, more preferably 0%.

It is preferable that the inner casing is made of forged steel except that it is made of cast steel.

(6) Others (a) The low-pressure steam turbine rotor shaft has a weight of C
0.2 to 0.3%, Si 0.1% or less, Mn 0.2% or less, Ni 3.2 to 4.0%, Cr 1.25 to 2.25%, M
o A low alloy steel having a fully tempered bainite structure having 0.1 to 0.6% and a V of 0.05 to 0.25% is preferable, and is preferably manufactured by the same manufacturing method as the above-described high-pressure and medium-pressure rotor shafts. . In particular, the Si content is 0.05% or less,
Super clean using a raw material in which impurities such as P, S, As, Sb, Sn, etc. are reduced as much as possible in addition to Mn 0.1% or less, and a raw material containing few impurities is used so that the total amount is 0.025% or less. It is preferred that the production is simplified. P and S each 0.010% or less, Sn and As 0.005%
Hereinafter, 0.001% or less of Sb is preferable.

(B) The nozzles other than the last stage of the low pressure turbine blade and the nozzles are C 0.05-0.2%, Si 0.1-0.1%.
5%, Mn 0.2-1.0%, Cr 10-13%, Mo 0.2%
Preference is given to a fully tempered martensitic steel having a content of between 0.4 and 0.2%.

(C) Both the inner and outer casings for the low-pressure turbine are C-0.2-0.3%, Si-0.3-0.7%, M
Carbon cast steel with n1% or less is preferred.

(D) The main steam stop valve casing and the steam control valve casing are C 0.1-0.2%, Si 0.1-0.4.
%, Mn 0.2 to 1.0%, Cr 8.5 to 10.5%, Mo
0.3 to 1.0%, W 1.0 to 3.0%, V 0.1 to 0.3
%, Nb 0.03 to 0.1%, Nb 0.03 to 0.08%,
A fully tempered martensitic steel containing B 0.0005 to 0.003% is preferred.

(E) As the last stage rotor blade of the low pressure turbine, 1
In addition to 2% Cr steel, a Ti alloy is used, and particularly for a length exceeding 40 inches, Al 5 to 8% by weight and V 3 to 6
A Ti alloy with% by weight is used. In particular, at 43 inches, Al 5.5-6.5%, V 3.5-4.5
For 46 inches, a high-strength material having 4 to 7% of Al, 4 to 7% of V, and 1 to 3% of Sn is preferable.

(F) The high pressure turbine, the medium pressure turbine, and the outer casing for the high and medium pressure turbine have C0.10 to 0.20.
%, Si 0.05-0.6%, Mn 0.1-1.0%, Ni
0.1 to 0.5%, Cr 1 to 2.5%, Mo 0.5 to 1.5
%, V0.1-0.35%, preferably Al0.0
25% or less, B 0.0005 to 0.004% and Ti0.0
It is preferable to manufacture the cast steel containing at least one of 5 to 0.2% and having a fully tempered bainite structure.
In particular, C 0.10 to 0.18%, Si 0.20 to 0.60%,
Mn 0.20-0.50%, Ni 0.1-0.5%, Cr
1.0 to 1.5%, Mo 0.9 to 1.2%, V 0.2 to 0.3
%, 0.001 to 0.005% of Al, 0.045 to 0.10 of Ti
% And B 0.0005-0.0020%. More preferably, the Ti / Al ratio is from 0.5 to 10.

(G) As a first stage blade of a high-pressure, medium-pressure, or high-pressure turbine at a steam temperature of 625 to 650 ° C. (high pressure side and medium pressure side), C 0.03 to 0.20% (preferably 0.03 to 0.20%) by weight 0.15%), Cr 12-20%, Mo9
-20% (preferably 12-20%), Co 12% or less (preferably 5-12%), Al 0.5-1.5%, Ti
1-3%, Fe 5% or less, Si 0.3% or less, Mn 0.2
% Or less, B 0.003 to 0.015%, and a Ni-based alloy containing at least one of Mg 0.1% or less, rare earth element 0.5% or less, and Zr 0.5% or less is used. 0% for
Including. After forging, a solution treatment is performed, and an aging treatment is performed at 700 to 870 ° C.

[0128]

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 150 kg of each sample having the composition (% by weight) shown in Table 1 was dissolved, heated to 1150 ° C., and forged to obtain a material. Sample No. 1 was heated at 1000 ° C. for 1 hour, cooled to room temperature by oil quenching, and then heated to 570 ° C. for 2 hours.
After the holding, it was air-cooled to room temperature. Sample No. 2 was heated at 1050 ° C. for 1 h, cooled to room temperature by oil quenching,
After heating to 70 ° C. and holding for 2 hours, the mixture was air-cooled to room temperature. Sample No.
No. 3 to No. 6 were heated at 1050 ° C. for 1 hour, cooled to room temperature by oil quenching, then heated to 560 ° C., held for 2 hours, air-cooled to room temperature (primary tempering), and further heated to 570 ° C. for 2 hours.
After the holding, the furnace was cooled to room temperature (secondary baking was also returned).

From the heat-treated material, a tensile test piece and V
Notch Charpy impact test pieces were collected and used for the experiment.

In Table 1, Test Nos. 3 and 4 are the materials of the present invention, and Test Nos. 1, 2, 5 and 5 are comparative materials. Test Nos. 1 and 2 are current long wing materials.

Table 2 shows the mechanical properties of these samples. The material of the present invention (Trial Nos. 2 and 3) has a tensile strength (≧ 120 kgf / mm ² or ≧ 12 kg) required as a long blade material for a steam turbine.
8.5 kgf / mm ² ) and low temperature toughness (20 ° C. V notch Charpy impact value ≧ 7 kgf-m / cm ² ) were confirmed to be sufficiently satisfied.

On the other hand, the comparative materials Nos. 1 and 2 have low tensile strengths for use in long blades for steam turbines. Comparative sample Nos. 5 and 6 have low toughness.

[0133]

[Table 1]

[0134]

[Table 2]

Embodiment 2 In response to a rise in fuel after an oil shock, a pulverized coal direct combustion boiler and a steam turbine at a steam temperature of 600 ° C. to 649 ° C. are required in order to improve thermal efficiency by improving steam conditions. Table 3 shows an example of a boiler under such steam conditions.

[0136]

[Table 3]

With the increase in capacity, the furnace for pulverized coal combustion became larger, and the furnace width was 10 m and the furnace width was 31 m, and the furnace depth was 16
m, 1400MW class, furnace width 34m, furnace depth 18m
Becomes

Table 4 shows the main specifications of the steam turbine at 625 ° C. and 1050 MW. In this embodiment, the last stage blade length in a cross-compound type four-flow exhaust, low-pressure turbine is 43 inches, and A is 3 for two HP-IP and LP units.
000 r / min and B are HP-LP and IP-LP having the same rotation speed of 3000 r / min, respectively, and are constituted by the main materials shown in the table in the high temperature part. High pressure section (H
The steam temperature of P) is 625 ° C. and a pressure of 250 kgf / cm ² , and the steam temperature of the medium pressure part (IP) is heated to 625 ° C. by a reheater and operated at a pressure of 45 to 65 kgf / cm ^2. . The low pressure section (LP) enters at a steam temperature of 400 ° C,
It is sent to the condenser under a vacuum of 722 mmHg below 00 ° C.

[0139]

[Table 4]

FIG. 1 is a sectional view of the high-pressure and intermediate-pressure steam turbines in the turbine configuration A shown in Table 4. The high-pressure steam turbine is provided with a high-pressure axle (high-pressure rotor shaft) 23 in which high-pressure moving blades 16 are implanted in a high-pressure inner casing 18 and a high-pressure outer casing 19 outside thereof. The aforementioned high-temperature and high-pressure steam is obtained by the aforementioned boiler, passes through the main steam pipe, passes through the main steam inlet 28 through the flange and elbow 25 constituting the main steam inlet, and is guided from the nozzle box 38 to the first stage double-flow blade. I will The first stage is a double flow, and eight stages are provided on one side. A stationary blade is provided for each of these moving blades. The blade is a saddle-type dovetil type, double tinon, and the first stage blade length is about 35 mm. The length between the axles is about 5.8 m, the diameter of the smallest part corresponding to the stationary blade part is about 710 mm, and the ratio of the length to the diameter is about 8.2.

The widths of the rotor blade implanted portions of the first stage and the last stage of the rotor shaft are almost equal, and the width of the rotor shaft is stepwise in five stages of the second stage, the third to fifth stages, the sixth stage, and the seventh to eighth stages. The axial width of the second stage implant is 0.71 times as large as that of the last stage.

The portion of the rotor shaft corresponding to the stationary blade has a smaller rotor shaft diameter than the rotor blade implanted portion. The axial width of that part is gradually reduced to the width between the final stage rotor blade and the rotor blade in front of it between the second stage rotor blade and the third stage rotor blade. The width of the latter is 0.86 times smaller than the width of the former. 2nd stage ~
The size is reduced in two stages, up to the sixth stage and the sixth to ninth stages.

In this example, all of the materials shown in Table 5 described later were made of 12% Cr-based steel containing no W, Co and B except that the first stage blade and the nozzle were used. The blade length of the rotor blade in this embodiment is 35 to 50 mm in the first stage and becomes longer in each stage from the second stage to the last stage. Particularly, the length from the second stage to the last stage depends on the output of the steam turbine. Is 65-180mm,
The number of stages is 9 to 12, and the length of the wing portion of each stage is 1.10 to 1.15, which is the length of the downstream side adjacent to the upstream side, and the ratio is Is gradually increasing.

The medium-pressure steam turbine rotates the generator discharged from the high-pressure steam turbine together with the high-pressure steam turbine by the steam heated again by the reheater to 625 ° C. The rotation speed is 3000 times / min. Rotated. The medium-pressure turbine has a medium-pressure inner casing 21 and an outer casing 22 like the high-pressure turbine. The moving blade 17 has two flows in six stages,
It is provided on the left and right almost symmetrically with respect to the longitudinal direction of the medium pressure axle (medium pressure rotor shaft). Bearing center distance is about 5.8m
The first stage blade length is about 100 mm, and the last stage blade length is about 230
mm. The first and second stage dovetails are inverted chestnut type.
The diameter of the rotor shaft corresponding to the stationary blade before the last stage rotor blade is about 630 mm, and the ratio of the distance between bearings to the diameter is about 9.2 times.

In the rotor shaft of the medium-pressure steam turbine according to the present embodiment, the axial width of the rotor blade implanted portion gradually increases in three stages from the first stage to the fourth stage, the fifth stage, and the last stage.
The width at the last stage is about 1.4 times larger than that at the first stage.

Further, the rotor shaft of the present steam turbine has a smaller diameter at a portion corresponding to the stationary blade portion, and the width thereof is stepwise in four stages according to the first-stage moving blade, the second to third stages, and the last-stage moving blade side. The width of the latter in the axial direction with respect to the former is reduced to about 0.75 times.

In this embodiment, a 12% Cr steel containing no W, Co and B is used except that the materials shown in Table 5 described later are used for the first stage blade and the nozzle. The length of the blade portion of the moving blade in this embodiment is longer at each stage as it goes from the first stage to the last stage, and the length from the first stage to the last stage is 60 to 300 mm depending on the output of the steam turbine.
In the nine stages, the length of the wing portion of each stage is longer at a ratio of 1.1 to 1.2 as the length on the downstream side is adjacent to the upstream side.

The implanted portion of the moving blade has a diameter larger than that of the portion corresponding to the stationary blade, and the implant width is larger as the blade length of the moving blade is larger. The ratio of the width to the blade length of the rotor blade is 0.1 in the first stage to the last stage.
35 to 0.8, and gradually decreases from the first stage to the last stage.

FIG. 2 is a sectional view of the low-pressure turbine. The low pressure turbine is connected in two tandems and has almost the same structure. Each of the moving blades 41 has eight stages on the left and right sides and is substantially symmetrical on the left and right sides, and stationary blades 42 are provided corresponding to the moving blades. The blade length of the last stage is 43 inches.
7, 12% Cr steel is used, has a double tinon and saddle type dovetail shown in FIG. 3, and the nozzle box 38 is a double flow type. The rotor shaft 44 is made of Ni 3.75%, Cr
1.75%, Mo 0.4%, V 0.15%, C 0.25%
Forged steel having a fully tempered bainite structure of a super clean material consisting of Ni, Si 0.05%, Mn 0.10%, and residual Fe is used. A 12% Cr steel containing 0.1% Mo is used for both the moving blades and the stationary blades other than the last stage.
The inner and outer casing members are made of C25% cast steel. The center-to-center distance of the bearing 43 in this embodiment is 750.
0mm, the rotor shaft diameter corresponding to the stator vane is about 12
The diameter at the blade implantation part is 2275 mm. The distance between the bearing centers for this rotor shaft diameter is about 5.
9.

3 is a perspective view of a blade having a blade length of 1092 mm (43 ″) made of 12% Cr martensitic steel according to the present invention.
52 is a blade-implanted portion on the rotor shaft, 53 is a hole for inserting a pin for supporting the centrifugal force of the blade, and 54 is an erosion shield for preventing erosion due to water droplets in steam (by weight, Cr 28%, W4%). , A C-based alloy stellite plate containing 1% of C and joined by welding), and 57 is a cover. In this embodiment, it is formed by cutting after the whole forging. The cover 57
Can be formed mechanically integrally. Erosion shield: Cr 25-30%, W1-7% and C0.5
Rolled sheets of Co-based alloys containing up to 1.5% are preferred.

The 43 "long wing was made by melting using an electroslag remelting method and subjected to forging heat and treatment. Forging was performed at a temperature in the range of 850 to 1150 ° C., and heat treatment was performed in the same manner as in Example 1 described above. Table 5 shows the chemical composition (% by weight) of the long wing material, the balance being Fe, and the metal structure of the long wing material was a fully tempered martensite structure.

[0152]

[Table 5]

Table 6 shows the room temperature tensile strength, elongation, draw ratio, and 20 ° C. V notch Charpy impact value. The mechanical properties of this 43 ″ long wing are the required properties, tensile strength 128.5k
gf / mm ² or more, 20 ° C V notch Charpy impact value 7kgf
-M / cm ² or more, which was confirmed to be sufficiently satisfied.

[0154]

[Table 6]

In the low-pressure turbine of this embodiment, the axial width of the moving blade implanted portion is from the first stage to the third stage, the fourth stage, the fifth stage, the sixth stage, the seventh stage and the eighth stage.
The width gradually increases in four stages, and the width of the last stage is about 6.8 times larger than the width of the first stage.

The diameter of the portion corresponding to the stationary blade portion is reduced, and the axial width of the portion is gradually increased in the third, fifth, sixth, and seventh stages from the first stage blade side. The width of the last stage is about 2.
It is five times larger.

The rotor blades in this embodiment have six stages, and the length of the blade portion increases in each stage from the initial stage of approximately 3 ″ to the final stage of 43 ″. Depending on the output of the steam turbine, the blade length is increased from the initial stage to the final stage. The length of the step is 80 ~ 1100mm, 8 steps or 9 steps, and the wing length of each step is 1.2 to 1.8 times as long as the downstream side is adjacent to the upstream side. I have.

The implanted portion of the moving blade has a diameter larger than that of the portion corresponding to the stationary blade, and the implant width is larger as the blade length of the moving blade is larger. The ratio of the width to the blade length of the rotor blade is 0.1 in the first stage to the last stage.
15 to 0.91, and gradually decreases from the first stage to the last stage.

Further, the width of the rotor shaft corresponding to each stationary blade is gradually increased in each stage from the first stage and the second stage to the last stage and the front stage. The ratio of the width to the blade length of the rotor blade is 0.25 to 1.25, and decreases from upstream to downstream.

In addition to the present embodiment, a steam inlet temperature of 610 ° C. for the high-pressure steam turbine and the medium-pressure steam turbine, and a steam inlet temperature of 385 ° C. for the two low-pressure steam turbines at 1000 MW
A similar configuration can be applied to a large-scale large-capacity power plant.

The high-temperature high-pressure steam turbine plant in this embodiment is mainly composed of a coal-fired boiler, a high-pressure turbine, a medium-pressure turbine, two low-pressure turbines, a condenser, a condensate pump, a low-pressure feedwater heater system, a deaerator, and a booster pump. , Feed water pump,
It is composed of a high pressure feed water heater system. That is, the ultra-high-temperature and high-pressure steam generated in the boiler enters the high-pressure turbine to generate power, is reheated again in the boiler, and enters the medium-pressure turbine to generate power. This medium-pressure turbine exhaust steam enters the low-pressure turbine and generates power,
Condenses in the condenser. This condensate is sent to the low pressure feed water heater system and deaerator by the condensate pump. The feedwater degassed by this deaerator is sent to a high-pressure feedwater heater by a booster pump and a feedwater pump to be heated, and then returned to the boiler.

Here, in the boiler, feed water passes through a economizer, an evaporator, and a superheater to become high-temperature and high-pressure steam. On the other hand, the boiler combustion gas that heated the steam exited the economizer,
Enter the air heater to heat the air. Here, the feedwater pump is driven by a feedwater pump drive turbine that operates with the extracted steam from the medium pressure turbine.

In the high-temperature high-pressure steam turbine plant configured as described above, the temperature of the feedwater exiting the high-pressure feedwater heater system 63 is much higher than the temperature of the feedwater in the conventional thermal power plant. The temperature of the combustion gas leaving the economizer inside the boiler will also be much higher than in a conventional boiler. Therefore, heat is recovered from the boiler exhaust gas so as not to lower the gas temperature.

It should be noted that the same high pressure turbine,
A medium-pressure turbine and one or two low-pressure turbines may be connected in tandem, and a single generator may be rotated to generate power, and a tandem compound-type power plant may be similarly configured. As in the present embodiment, in a generator having an output of 1050 MW class, a higher strength generator shaft is used. In particular, C 0.15 to 0.30%,
Si 0.1-0.3%, Mn 0.5% or less, Ni 3.25-
4.5%, Cr 2.05 to 3.0%, Mo 0.25 to 0.6
0% has a fully tempered bainite structure containing V0.05～0.20% at room temperature tensile strength of 93kgf / mm ² or more, particularly 100 kgf / mm ² or more, 50% FATT is 0 ℃ or less,
Particularly, it is preferable that the temperature be -20 ° C or less,
And the total amount of P, S, Sn, Sb and As as impurities is 0.02.
It is preferable that the Ni / Cr ratio be 5% or less and the Ni / Cr ratio be 2.0 or less.

The high-pressure turbine shaft has a structure in which nine stages of blades are planted around the first stage blade planting portion on the multi-stage side. The medium-pressure turbine shaft has a multi-stage blade provided on the left and right with approximately six stages of symmetrical blade installation portions, and substantially centered on the center. Although the rotor shaft for the low-pressure turbine is not shown, a center hole is provided in any of the rotor shafts of the high-pressure, medium-pressure, and low-pressure turbines, and through this center hole, the presence or absence of a defect is determined by ultrasonic inspection, visual inspection, and fluorescence inspection. Is inspected. Further, the inspection can be performed by ultrasonic inspection from the outer surface, and the center hole may not be provided.

Table 7 shows the chemical compositions (% by weight) used for the main parts of the high-pressure turbine, medium-pressure turbine and low-pressure turbine of this embodiment. In the present embodiment, since the one of the thermal expansion coefficient of about 12 × 10- ⁶ / ℃ having a crystal structure of the whole ferritic high temperature portion of the high pressure portion and the intermediate pressure, at all problems due to difference in thermal expansion coefficient Did not.

The rotor shafts of the high-pressure turbine and the intermediate-pressure turbine were prepared by melting 30 tons of the heat-resistant cast steel shown in Table 7 in an electric furnace, deoxidizing carbon in a vacuum, casting it in a mold, forging and elongating an electrode rod. Then, the electroslag was melted again as the electrode rod so as to melt from the upper part to the lower part of the cast steel, and forged into a rotor shape (diameter 1050 mm, length 3700 mm) and formed. This forging is carried out at 1150 to prevent forging cracks.
Performed at a temperature of less than or equal to ° C After annealing this forged steel,
This was obtained by heating to 1050 ° C., performing water spray cooling and quenching, tempering twice at 570 ° C. and 690 ° C., and cutting into the shapes shown in FIGS. In the present embodiment, the upper side of the electroslag steel ingot is the first stage blade side, and the lower side is the last stage side.

The high-pressure and medium-pressure blades and nozzles were prepared by melting the heat-resisting steel shown in Table 7 in a vacuum arc melting furnace to form a blade and nozzle material (width 150 mm, height 50 mm, length 1000 mm). Forged and molded. The forging was performed at a temperature of 1150 ° C. or less in order to prevent forging cracks. The forged steel was heated to 1050 ° C., subjected to oil quenching, tempered at 690 ° C., and then cut into a predetermined shape.

The internal casing of the high pressure section and the intermediate pressure section, the main steam stop valve casing and the steam control valve casing are shown in Table 7.
Was melted in an electric furnace, and after ladle refining, it was cast into a sand mold to produce. By performing sufficient refining and deoxidation before casting, a casting free of casting defects such as shrinkage cavities was obtained. Weldability evaluation using this casing material
The measurement was performed according to IS Z3158. The pre-heating, inter-pass and post-heating onset temperatures were 200 ° C, and the post-heat treatment was 400 ° C x 30 minutes. No weld crack was observed in the material of the present invention, and the weldability was good.

[0170]

[Table 7]

Table 8 shows the mechanical properties and heat treatment conditions of the main members of the high temperature steam turbine made of ferritic steel described above.

As a result of examining the center of the rotor shaft, it was found that the characteristics (62
5 ° C., 10 ⁵ h strength ≧ 10 kgf / mm ² , 20 ° C. shock absorption energy ≧ 1.5 kgf-m). This demonstrated that a steam turbine rotor usable in steam at 620 ° C. or higher can be manufactured. Also, as a result of investigating the characteristics of this blade, the characteristics (625 ° C., 10
It was confirmed that ⁵ h strength ≧ 15 kgf / mm ² ) was sufficiently satisfied. This demonstrated that a steam turbine blade usable in steam at 620 ° C. or higher can be manufactured.

[0173] Further results of the examination of the characteristics of the casing, high pressure, properties required for the intermediate pressure turbine casings (625 ℃, 10 ⁵ h strength ≧ 10kgf / mm ^2, 20 ℃ impact absorption energy ≧ 1 kgf-m) sufficient Satisfaction and weldability were confirmed. Thereby, 620 ° C
It was proved that a steam turbine casing usable in the above steam could be manufactured.

[0174]

[Table 8]

In this embodiment, a Cr-Mo low alloy steel was build-up welded on the journal portion of the rotor shaft to improve the bearing characteristics. The overlay welding is as follows.

A coated arc welding rod (diameter: 4.0 φ) was used as a test welding rod. Table 9 shows the chemical composition (% by weight) of the deposited metal obtained by welding using the welding rod. The composition of the deposited metal is almost the same as the composition of the welding material.

The welding conditions were as follows: welding current 170 A, voltage 24
V, speed 26 cm / min.

[0178]

[Table 9]

As shown in Table 10, the overlay welding was carried out on the surface of the base metal to be tested by combining the welding rods used for each layer and eight layers. The thickness of each layer was 3-4 mm, the total thickness was about 28 mm, and the surface was ground about 5 mm.

The welding conditions are preheating, inter-pass, stress relief annealing (SR) start temperature of 250 to 350 ° C., and SR processing conditions of 630 ° C. × 36 hours.

[0181]

[Table 10]

In order to confirm the performance of the welded portion, the plate material was similarly overlaid and subjected to a side bending test at 160 °, but no crack was found in the welded portion.

Further, a bearing sliding test by rotation in the present invention was performed.
It was also excellent in oxidation resistance.

Instead of this embodiment, a high-pressure steam turbine, a medium-pressure steam turbine, and one or two low-pressure steam turbines are connected in tandem to provide a tandem-type power plant with 3600 rpm and a turbine configuration B in Table 4. The high-pressure turbine, the intermediate-pressure turbine and the low-pressure turbine of the present embodiment can be similarly combined and configured.

Example 3 Table 11 shows that the steam temperature was 600 ° C.
This is the main specification of a 600 MW steam turbine. In this embodiment, the final stage blade length in a tandem compound double flow type, low pressure turbine is 43 inches, and HP / IP
3000r for integrated type and 1 LP (C) or 2 LP (D)
/ Min, and is composed of the main materials shown in the table in the high temperature part. The high-pressure section (HP) has a steam temperature of 600 ° C. and a pressure of 250 kgf / cm ² , and has a medium-pressure section (I
The vapor temperature of P) is heated to 600 ° C. by a reheater,
It is operated at a pressure of 45~65kgf / cm ^2. Low pressure part (L
P) has a steam temperature of 400 ° C.
It is sent to the condenser at a vacuum of 2 mmHg.

[0186]

[Table 11]

FIG. 6 is a sectional view of a high-pressure / intermediate-pressure integrated steam turbine, and FIG. 7 is a sectional view of its rotor shaft.
The high-pressure side steam turbine is provided with a high-to-medium pressure axle (high-pressure rotor shaft) 23 in which the high-pressure side moving blades 16 are implanted in the inner casing 18 and the outer casing 19 outside thereof. The high-temperature and high-pressure steam is obtained by the boiler, passes through the main steam pipe, passes through the main steam inlet 28 through the flange and elbow 25 constituting the main steam inlet, and is guided from the nozzle box 38 to the first stage rotor blades. . The rotor blades are provided in eight stages on the high pressure side on the left side in the figure and six stages on the medium pressure side (about half of the right side in the figure). A stationary blade is provided for each of these moving blades. The moving blade has a saddle type or a getter type, a dove-til type, a double tinon, a high pressure side first stage blade length of about 40 mm, and a medium pressure side first stage blade length of 100 mm. Bearing 4
The length between the three is about 6.7 m and the diameter of the smallest part corresponding to the stationary blade portion is about 740 mm, and the ratio of the length to the diameter is about 9.0.

The first stage and the last stage of the rotor blade implant root portion of the high pressure side rotor shaft have the largest width at the first stage, the second stage to the seventh stage are smaller than that, and 0.40 to 0.56 times the first stage. Are the same size, the last stage is between the first stage and the size of the second to seventh stages, and is 0.46 to 0.62 times the size of the first stage.

On the high pressure side, the blades and nozzles were made of 12% Cr-based steel shown in Table 7.
The blade length of the rotor blade in this embodiment is 35 to 50 in the first stage.
mm, the length of each stage increases from the second stage to the last stage. Particularly, the length from the second stage to the last stage is in the range of 50 to 150 mm depending on the output of the steam turbine, and the number of stages is seven.
The length of the wings of each stage is within the range of 1.05 to 1.35 times that of the downstream side adjacent to the upstream side, and the downstream side The ratio is gradually increasing.

The medium-pressure steam turbine rotates the generator discharged from the steam discharged from the high-pressure steam turbine together with the high-pressure steam turbine by the steam heated again to 600 ° C. by the reheater, and is rotated at a rotation speed of 3000 RPM. You. The intermediate-pressure turbine has an inner casing 21 and an outer casing 22 similarly to the high-pressure turbine, and stationary vanes are provided to oppose the moving blades 17. The bucket 17 has six stages. The length of the first stage blade is about 130 mm and the length of the last stage blade is about 260 mm. Dovetil is an inverted chestnut type. The diameter of the rotor shaft corresponding to the stationary blade is about 740 mm.

In the rotor shaft of the medium-pressure steam turbine, the axial width of the root portion of the rotor blade implant is largest at the first stage, smaller at the second stage, smaller at the third to fifth stages less than the second stage, and the same. The width of the last stage is between the third and fifth stages and the second stage, and is 0.48 to 0.64 times the width of the first stage. The first stage is 1.1 to 1.5 times the second stage.

On the medium pressure side, a blade and a nozzle made of a 12% Cr-based steel shown in Table 7 are used. The length of the blade portion of the moving blade in this embodiment is longer at each stage as it goes from the first stage to the last stage, and the length from the first stage to the last stage is 90 to 350 mm, and the number of stages is 6 to 6 depending on the output of the steam turbine. 9
It is within the range of the stage, and the length of the wing portion of each stage is longer at a ratio of 1.10 to 1.25 as the length of the downstream side is adjacent to the upstream side.

The implanted portion of the moving blade has a larger diameter than the portion corresponding to the stationary blade, and the width thereof is related to the length and position of the blade portion of the moving blade. The ratio of the width to the blade length of the rotor blade is the largest in the first stage, 1.35 to 1.80 times, the second stage is 0.88 to 1.18 times, and the third to sixth stages are the final stages It is smaller and is 0.40 to 0.65 times. FIG. 8 is a sectional view of the low-pressure turbine, and FIG. 9 is a sectional view of the rotor shaft. The low pressure turbine is tandemly coupled to high and medium pressure by one unit. The moving blades 41 have six stages on the left and right sides and are substantially symmetrical on the left and right, and stationary blades 42 are provided corresponding to the moving blades. The blade length of the last stage is 43 inches, and 12% Cr steel shown in Table 1 of Example 1 and Table 5 of Example 2 is used. The rotor shaft 44 is made of Ni 3.75%, Cr 1.
75%, Mo 0.4%, V 0.15%, C 0.25%, S
A forged steel having a fully tempered bainite structure of a super clean material consisting of 0.05% of i, 0.10% of Mn, and the remaining Fe is used. A 12% Cr steel containing 0.1% Mo is used for each of the moving blades and stationary blades other than the last stage and the preceding stage. 0.25% cast steel is used for the inner and outer casing materials. The center-to-center distance of the bearing 43 in this embodiment is 7
000 mm, the diameter of the rotor shaft corresponding to the stationary blade portion is about 800 mm, and the diameter at the blade implant portion is the same for each stage.
The distance between the bearing centers for the rotor shaft diameter corresponding to the vanes is about 8.8.

In the low-pressure turbine, the axial width of the root portion of the blade implantation is the smallest at the first stage, and the downstream stages are equal in the second and third stages, the fourth and the fifth stages are equal, and gradually increased in the four stages. The width of the last stage is 6.2 to 7.0 times larger than the width of the first stage. A few steps are 1.15 to 1.40 times the first step,
4,5 stage is 2.2-2.6 times of 2-3 stage, last stage is 4,5
It is 2.8 to 3.2 times the stage. The width of the root portion is indicated by a point connecting the extended line extending to the diameter of the rotor shaft.

In this embodiment, the blade length of the rotor blade increases in each stage from the initial stage of 4 ″ to the final stage of 43 ″. Depending on the output of the steam turbine, the length of the blade from the initial stage to the final stage is 100 to 100 μm. Within 1270mm, up to 8 steps,
The wing length of each stage is longer within a range of 1.2 to 1.9 times as long as the downstream side is adjacent to the upstream side.

The implanted root portion of the moving blade has a large diameter and widens as compared with the portion corresponding to the stationary blade, and its width increases as the blade length of the moving blade increases. The ratio of the width to the blade length of the rotor blade is 0.30 to 1.5 from the first stage to the last stage, and the ratio gradually decreases from the first stage to the last stage before the last stage. Is 0.15 higher than the previous one
It gradually decreases within the range of -0.40. The last stage has a ratio of 0.50 to 0.65.

The final stage rotor blade in this embodiment is the same as that in the first embodiment. FIG. 11 shows that the erosion shield (stellite alloy) 54 in this embodiment is welded by electron beam welding or T-beam welding.
It is the cross section and the perspective view which show the state where it joined by IG welding. As shown in the figure, the erosion shield 54 is welded at two places, a front side and a back side.

In addition to the present embodiment, the steam inlet temperature of the high- and medium-pressure steam turbine is 610 ° C. or higher, the steam inlet temperature to the low-pressure steam turbine is about 400 ° C., and the outlet temperature is about 60 ° C.
The same configuration can be applied to a MW class large-capacity power plant.

The high-temperature high-pressure steam turbine power plant in this embodiment is mainly composed of a boiler, high-medium-pressure turbine, low-pressure turbine, condenser, condensate pump, low-pressure feedwater heater system, deaerator, booster pump, feedwater pump, high-pressure feedwater. It is composed of a heater system. That is, the ultra-high-temperature and high-pressure steam generated in the boiler enters the high-pressure side turbine and generates power, and is then reheated in the boiler again to enter the medium-pressure side turbine and generate power. The high- and medium-pressure turbine exhaust steam enters the low-pressure turbine and generates power, and then condenses in the condenser.
This condensate is sent to the low pressure feed water heater system and deaerator by the condensate pump. The feedwater degassed by this deaerator is sent to a high-pressure feedwater heater by a booster pump and a feedwater pump to be heated, and then returned to the boiler.

Here, in the boiler, the water supply passes through a economizer, an evaporator, and a superheater to become high-temperature and high-pressure steam. On the other hand, the boiler combustion gas that heated the steam exited the economizer,
Enter the air heater to heat the air. Here, the feedwater pump is driven by a feedwater pump drive turbine that operates with the extracted steam from the medium pressure turbine.

In the high-temperature high-pressure steam turbine plant configured as described above, the temperature of the feedwater exiting the high-pressure feedwater heater system 63 is much higher than the feedwater temperature in the conventional thermal power plant, so that it is inevitable. The temperature of the combustion gas leaving the economizer inside the boiler will also be much higher than in a conventional boiler. Therefore, heat is recovered from the boiler exhaust gas so as not to lower the gas temperature.

In this embodiment, a high-medium pressure turbine and one low pressure turbine are connected to one generator tandem to form a tandem compound double flow type power plant. As another embodiment, a turbine configuration (D) shown in Table 11 is used, and two low-pressure turbines are connected in tandem, so that power generation with an output of 1050 MW class can be configured in the same manner as this embodiment. A higher strength shaft is used as the generator shaft. In particular, C0.1
5 to 0.30%, Si 0.1 to 0.3%, Mn 0.5% or less, Ni 3.25 to 4.5%, Cr 2.05 to 3.0%, M
o It has a fully tempered bainite structure containing 0.25 to 0.60% and V 0.05 to 0.20%, and has a tensile strength at room temperature of 93 kg.
f / mm ² or more, especially 100 kgf / mm ² or more, 50% FAT
It is preferable that T is 0 ° C. or less, particularly −20 ° C. or less, that the magnetizing force at 21.2 KG is 985 AT / cm or less, and that the total amount of P, S, Sn, Sb and As as impurities is 0.025. % Or less, and the Ni / Cr ratio is preferably 2.0 or less.

Table 7 above shows the chemical compositions (% by weight) used for the main parts of the high-medium pressure turbine and the low pressure turbine of this embodiment. In this embodiment, the high-temperature part integrated with the high-pressure side and the medium-pressure side is the same as that shown in Table 7 except that the martensitic steel No. 9 of Example 4 described later is used. since those of thermal expansion coefficient 12 × 10- ⁶ / ℃ with, problems with thermal expansion coefficient difference was no.

The rotor shaft in the high / medium pressure section is N
Melt 30 tons of the heat-resistant cast steel described in o.1 in an electric furnace, deoxidize carbon in vacuum, cast it into a mold, forge and stretch to make an electrode rod, and melt it from the top to the bottom of the cast steel as this electrode rod Then, the electroslag was melted again and forged into a rotor shape (diameter 1450 mm, length 5000 mm) and molded. The forging was performed at a temperature of 1150 ° C. or less in order to prevent forging cracks. After annealing the forged steel, 1050 ° C
To 570 ° C and 690 ° C
Tempering twice, and obtained by cutting into the shape shown in FIG. The materials and manufacturing conditions of the other parts are the same as in the second embodiment. Further, overlay welding to the bearing journal 45 was performed in the same manner.

Table 12 shows the composition of the high-pressure, medium-pressure or high-medium-pressure integrated rotor shaft in this embodiment.
Alloys of these compositions are cast into 10 kg ingots by vacuum melting and forged into 30 mm square. In the case of a large-sized steam turbine rotor shaft, after simulating the center part and holding at 1050 ° C. × 5 hours, quenching at a cooling rate of 100 ° C./h cooling at the center part, and 570 ° C. × 20 hours
Next tempering, secondary tempering at 690 ° C. × 20 hours and quenching at 1100 ° C. × 1 hour for blades, 750 ° C. ×
Tempering for 1 hour, 680 ° C, 17.5kgf / mm ²
A creep rupture test and an impact test were carried out. Table 13 shows the results.

The alloys of the present invention No. 1 to No. 9 in Table 12 are as follows:
It is preferable to apply to steam conditions of 620 ° C. or higher, and it is understood that the creep rupture life is long. Although the creep rupture time improves as the amount of Co increases, the increase in the amount of Co tends to cause heat embrittlement when heated at 600 to 660 ° C.
The preferred range is 2 to 5% for 630 to 630 ° C, and 5.5 to 8% for 630 to 660 ° C. B shows excellent strength when 0.03% or less. At 620 to 630 ° C, the amount of B is 0.0.
0.01 to 0.01% and the Co content is 2 to 4%, 630 to 66
On the higher temperature side of 0 ° C., the B content is set to 0.01 to 0.03%,
High strength can be obtained by increasing the Co content to 5 to 7.5%.

It was clarified that N was strengthened when the temperature was higher than 600 ° C. in the examples of the present invention, and that the N was higher in strength than that having a large amount of N. The N content is 0.01 to 0.1.
04% is preferred. Since N is hardly contained in the vacuum melting, it is added by the master alloy.

As is clear from the fact that No. 8 having a low Mn content of 0.09% shows a higher strength as compared with the same Co content, the Mn content is set to be 0.03% or more for further strengthening. 0.2
It is preferably set to 0%.

[0209]

[Table 12]

[0210]

[Table 13]

[Embodiment 4] The rotors of the high-pressure turbine, the medium-pressure turbine and the high-medium-pressure turbine of Examples 2 and 3 are shown in Table 1.
4 shows an example in which the body and the shaft described in No. 4 were manufactured with different compositions. In each case, 30 tons of heat-resistant cast steel related to each part is melted in an electric furnace, carbon is vacuum deoxidized, cast into a mold, and forged to produce an electrode rod. Immediately after melting, the body portion was electro-dissolved immediately, and the bearing portion was further electro-slag-dissolved thereon.
(0 mm, length 3700 mm). The forging was performed at a temperature of 1150 ° C. or less in order to prevent forging cracks. Further, after the annealing heat treatment, the forged steel was heated to 1050 ° C., subjected to water spray cooling and quenching, and tempered twice at 570 ° C. and 690 ° C., and was obtained by cutting into the shapes shown in FIGS. The body and the bearing are joined at a position shown by a dotted line. As shown in FIG. 4, in the rotor shaft for the high-pressure steam turbine, between the downstream and the last stage of the blade and immediately before the blade, in the rotor shaft for the medium-pressure steam turbine shown in FIG. This is a connection between the last stage on the downstream side and the front side. In the present embodiment, the upper side of the electroslag steel ingot is set to the first stage side of the body, and the lower side is set to the last stage side.

The high-pressure and medium-pressure blades and nozzles were prepared by melting the heat-resisting steel shown in Table 5 in a vacuum arc melting furnace into a blade and nozzle material shape (width 150 mm, height 50 mm, length 1000 mm). Forged and molded. The forging was performed at a temperature of 1150 ° C. or less in order to prevent forging cracks. The forged steel is heated to 1050 ° C., subjected to oil quenching, tempered at 690 ° C., and then cut into a predetermined shape.

The internal casing, the main steam stop valve casing, and the steam control valve casing of the high pressure section, the medium pressure section, and the high pressure section and the intermediate pressure section of the high pressure and medium pressure integrated type are prepared by melting a heat-resistant cast steel shown in Table 7 in an electric furnace. After the refining, it was cast into a sand mold. By performing sufficient refining and deoxidation before casting, a casting free of casting defects such as shrinkage cavities was obtained. Weldability evaluation using this casing material was performed according to JIS Z3158. Preheat, interpass and postheat onset temperatures are 200
° C, and the post heat treatment was performed at 400 ° C for 30 minutes. No weld crack was observed in the material of the present invention, and the weldability was good.

[0214]

[Table 14]

[Embodiment 5] In this embodiment, the steam temperature of the high-pressure steam turbine, the medium-pressure steam turbine or the high-medium-pressure steam turbine is changed to 649 ° C instead of 625 ° C, and the structure and the size are implemented. It is obtained with almost the same design as in Examples 2 to 4. What differs from the first embodiment is a rotor shaft, first stage moving blades, first stage stationary blades, and an inner casing of a high-pressure, medium-pressure or high-medium-pressure integrated steam turbine which is in direct contact with this temperature. Among these materials except for the inner casing, the B content of the materials shown in Table 9 was 0.02.
0.03% and the amount of Co to 5 to 7%. As the inner casing material, the W amount is increased to 2 to 3%.
%, There is a great merit that the required strength is satisfied and the conventional design can be used. That is, in the present embodiment, the conventional design concept can be used as it is in that all the structural materials exposed to high temperatures are made of ferritic steel. Since the steam inlet temperature of the moving blade and the stationary blade of the second stage is about 610 ° C., it is preferable to use the material used in the first stage of the second embodiment.

Further, the steam temperature of the low-pressure steam turbine is about 405 ° C., which is slightly higher than about 380 ° C. in the second embodiment.
The final stage rotor blade is made of the above-described high-strength 12% Cr-based martensitic steel, and the rotor shaft itself is used in Example 2.
Since the material has sufficiently high strength, a super clean material is also used.

Further, in contrast to the cross-compound type in this embodiment, a tandem type in which the whole was directly connected was 3600 rpm.
It can also be carried out at a rotational speed of.

[0218]

According to the present invention, 120 kgfm / mm ²
A martensitic high-strength steel having a high tensile strength of at least 7 kgf-m / cm ^{2 and} a high impact value of at least 7 kgfm / cm ² can be obtained.
It can be used for the last stage blade of a low-pressure turbine for a super-supercritical steam turbine of 0 to 660 ° C. class, and has remarkable effects of achieving extremely high thermal efficiency and a compact steam turbine.

Conventionally, at such a temperature, an austenitic alloy had to be formed, and it was not possible to produce a sound large-sized rotor from the viewpoint of manufacturability. Large rotors can be manufactured.

Further, since the all-ferritic steel high-temperature steam turbine of the present invention does not use an austenitic alloy having a large coefficient of thermal expansion, rapid start-up of the turbine is facilitated and thermal fatigue damage is reduced. There are advantages.

[Brief description of the drawings]

FIG. 1 is a sectional view of a high-pressure, medium-pressure steam turbine according to the present invention.

FIG. 2 is a sectional structural view of the low-pressure steam turbine according to the present invention.

FIG. 3 is a perspective view of a turbine blade according to the present invention.

FIG. 4 is a sectional view of a rotor shaft for a high-pressure steam turbine.

FIG. 5 is a sectional view of a rotor shaft for a medium-pressure steam turbine.

FIG. 6 is a cross-sectional view of a high- and medium-pressure steam turbine according to the present invention.

FIG. 7 is a sectional view of a rotor shaft for a high- and medium-pressure steam turbine according to the present invention.

FIG. 8 is a sectional view of the low-pressure steam turbine according to the present invention.

FIG. 9 is a sectional view of a rotor shaft for a low-pressure steam turbine according to the present invention.

FIG. 10 is a perspective view of the tip of a turbine blade of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st bearing, 2 ... 2nd bearing, 3 ... 3rd bearing, 4 ... 4th
Bearing, 5: Thrust bearing, 10: First shaft packing, 1
DESCRIPTION OF SYMBOLS 1 ... 2nd shaft packing, 12 ... 3rd shaft packing, 13 ... 4th shaft packing, 14 ... High-pressure diaphragm, 1
5: Medium pressure diaphragm, 16: High pressure blade, 17: Medium pressure blade, 18
... High-pressure internal casing, 19 ... High-pressure external casing, 20 ... Medium-pressure internal first casing, 21 ... Medium-pressure internal second casing, 22 ... Medium-pressure external casing, 23 ... High-pressure axle, 24 ... Medium pressure Axle, 25 ... flange, elbow, 26 ... front bearing box, 27 ... journal,
28: Main steam inlet, 29: Reheat steam inlet, 30: High pressure steam exhaust port, 31: Cylinder connecting pipe, 38: Nozzle box (high pressure first stage), 39: Thrust bearing wear cutoff device, 40 ...
Warm-up steam inlet, 41: moving blade, 42: stationary blade, 43: bearing,
44: rotor shaft, 51: wing portion, 52: wing implant portion, 53: hole, 54: erosion shield, 55: tie boss, 56: welded portion, 57: cover.

──────────────────────────────────────────────────続 き Continuing on the front page (51) Int.Cl. ⁶ Identification code FI F01D 5/28 F01D 5/28 (72) Inventor Haruo Urushiya 3-1-1 Kochicho, Hitachi-shi, Hitachi, Ibaraki Prefecture Hitachi, Ltd. Hitachi factory

Claims (12)

[Claims] C. 0.10 to 0.24% by weight, Si
0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo exceeding 1.5% and 3.0%
Hereinafter, the total amount of one or two of Nb and Ta is 0.04.
A high-strength steel containing up to 0.24% and N from 0.02 to 0.10%, with the balance being Fe and unavoidable impurities. 2. C. 0.10 to 0.24% by weight, Si
0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo exceeding 1.5% and 3.0%
Hereinafter, V 0.01% or more and less than 0.05%, the total amount of one or two of Nb and Ta is 0.04 to 0.24%, and N
A high-strength steel containing 0.2 to 0.10%, with the balance being Fe and unavoidable impurities. 3. The composition according to claim 1, wherein C is 0.10 to 0.24% by weight,
0.25% or less, Mn 0.1-0.50%, Cr 8.0-1
3.0%, Ni 2.0-4.0%, Mo 1.0-3.0%,
The total amount of one or two of Nb and Ta is 0.04 to 0.2
4%, and 0.02 to 0.10% of N,
b amount is 0.21 to 0.40% or (Mn / Ni) ratio is 0.1
A high-strength steel, wherein the balance is Fe and unavoidable impurities. 4. A composition in which C.sub.0.10 to 0.24% by weight, Si
0.25% or less, Mn 0.1 to 0.5%, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo 1.0-3.0%, V
0.01% or more and less than 0.05%, the total amount of one or two of Nb and Ta is 0.04 to 0.24%, and N is 0.02 to 0.02%.
10%, and the amount of C + Nb is 0.21 to 0.40%
Or (Mn / Ni) ratio is 0.1 or less, and the balance is Fe
And high-strength steel comprising unavoidable impurities. 5. The method according to claim 1, wherein C is 0.15 to 0.24% by weight,
0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo 1.5-3.0%, V
0.05 to 0.20%, the total amount of one or two of Nb and Ta is 0.04 to 0.24%, and N 0.02 to 0.10.
%, And the (C / V) ratio is 0.75 to 5;
A high-strength steel, the balance being Fe and inevitable impurities. 6. A steam turbine long blade made of the high-strength steel according to any one of claims 1 to 5, having a fully tempered martensite structure. 7. The weight ratio of C is more than 0.15% to 0.24% or less, Si is 0.25% or less, Mn is 0.90% or less, and Cr is 8.0 to 8.0%.
13.0%, Ni 2.0-4.0%, Mo 1.0-3.0
%, The total amount of one or two of Nb and Ta is 0.04 to
A long blade of a steam turbine containing 0.24% and N of 0.02 to 0.10%, with the balance being Fe and inevitable impurities and having a fully tempered martensite structure. 8. The weight ratio of C is more than 0.15% to 0.24% or less, Si is 0.25% or less, Mn is 0.90% or less, and Cr is 8.0 to 8.0%.
13.0%, Ni 2.0-4.0%, Mo 1.0-3.0
%, V 0.01% or more and less than 0.05%, 1 of Nb and Ta
The total amount of the species or two is 0.04 to 0.24%;
A long blade of a steam turbine characterized by containing 0.2 to 0.10%, the balance being Fe and unavoidable impurities, and having a fully tempered martensite structure. 9. An alloy made of martensitic steel containing 8.0 to 13.0% by weight of Cr is melted and forged, and then melted at 1000 ° C.
After quenching after heating and holding at ~ 1100 ° C,
The primary tempering is performed after cooling at 550 ° C. to 570 ° C., followed by cooling.
A method for manufacturing a long blade of a steam turbine, wherein a secondary tempering for cooling after heating at 590 ° C. is performed twice or more each time. 10. In a weight ratio of C 0.10 to 0.24%, Si
0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo 1.5-3.0%, V
Melting and forging an alloy of martensitic steel containing 0.20% or less, the total amount of one or two of Nb and Ta containing 0.04 to 0.24%, and 0.02 to 0.10% of N Later, 1
After quenching after heating and holding at 000 ° C. to 1100 ° C., quenching is performed, and then primary tempering is performed after cooling at 550 ° C. to 570 ° C., and further, at 560 ° C. to 590 ° C., which is higher than the primary tempering temperature. A method for manufacturing a long blade of a steam turbine, wherein a secondary tempering for cooling after heating and holding is performed twice or more. 11. A weight ratio of C 0.10 to 0.24%, Si
0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo 1.5-3.0%, V
Martensite having a total tempered martensite structure containing not more than 0.20%, the total amount of one or two of Nb and Ta being 0.04 to 0.24%, and N being 0.02 to 0.10%. A steam turbine made of steel, having a room temperature tensile strength of at least 120 kgf / mm ² , an impact value of at least 7 kgfm / cm ² , a final stage blade length of at least 838 mm, and rotating at 3600 rpm. . 12. A weight ratio of C0.10 to 0.24%, Si
0.25% or less, Mn 0.90% or less, Cr 8.0 to 13.
0%, Ni 2.0-4.0%, Mo 1.5-3.0%, V
Martensite having not more than 0.20%, the total amount of one or two of Nb and Ta being 0.04 to 0.24%, and 0.02 to 0.10%, and having a fully tempered martensite structure made of steel, the tensile strength at room temperature is 120 kgf / mm ² or more, the impact value is at 7kgf-m / cm ² or more, the final stage blade length is not less than 1016 mm, the steam turbine, characterized in that rotating at 3000rpm .