DE69633140T2 - STEAM TURBINE - Google Patents

Description

technical area

The The invention relates to a steam turbine power plant with a combination a high-pressure turbine, an intermediate-pressure turbine and a low-pressure turbine, where a value of length of a blade (inch) times the number of revolutions (rpm) of one Blade of the final stage of the low-pressure turbine is at least 125,000.

State of technology

A Blade for a steam turbine is being turned off at the present time 12 Cr-Mo-Ni-V-N steel produced. In recent years, the Request arose, the thermal efficiency of a gas turbine to improve energy, and it is desired that the equipment of the gas turbine is made compact, in order to save space.

Around to improve the thermal efficiency of a gas turbine and To make their equipment compact, it is effective, the Shovels of a steam turbine longer to make, and for this purpose there is a tendency that the length of a Shovel of the final stage of a low-pressure steam turbine is increased every year. With this tendency, the operating conditions for blades become a steam turbine hard, which means that under these operating conditions the strength of the 12 Cr-Mo-Ni-V-N steel is no longer sufficient, and therefore the development of a new material is expected the greater strength Has. As strength of the material for blades of a steam turbine a tensile strength is required, which is a basic mechanical feature represents.

The Material for Shoveling a steam turbine must also have a great deal of toughness, in addition to one huge Strength to ensure safety from breakage.

When Structural material with a tensile strength higher than that of conventional 12 Cr-Mo-Ni-V-N steel (martensite-based steel) is general a Ni-based alloy and a Co-based alloy known; however, such a material is not desirable as a blade material, because its operability in heat, its workability and its periodic damping characteristic are bad.

One Disc material for For example, a gas turbine is disclosed in Japanese Patent Publications Sho 63-171856 and Hei 4-120246 known.

at the conventional one Steam turbine, the maximum steam temperature was set to 566 ° C, and the maximum vapor pressure was set to 246 atg.

in the In terms of exhaustion fossil fuels such as mineral oil or coal, to save energy and prevent pollution However, it is desirable the efficiency of a thermal power plant to increase; and to increase the efficiency of energy production, it is most effective to increase the steam temperature of a steam turbine.

The CA-2 142 924 A discloses a blade of the final stage of a low-pressure steam turbine, the is made of a Ti-based alloy. The one for the blades The Ti-based alloy used in the final stage is quite poor Machining properties, especially when cutting the material becomes. Therefore, it is difficult to turn the material into a desired one Shape the blade shape. Furthermore the Ti-based alloy material is quite expensive, so that the Use of tibasized alloy for the blades of the final stage not practical.

The The object underlying the invention is a steam turbine power plant with a combination of a high pressure turbine, an intermediate pressure turbine and a low pressure turbine to provide, wherein the Low-pressure turbine has a blade of the final stage, the outstanding Machining properties and both a high strength and a size toughness Has.

These Task is solved by a steam turbine power plant, the having the features of claim 1. Preferred embodiments are in the claims 2 to 10 claims. A method by which the blade of the Final stage of the low-pressure steam turbine can be produced The subject matter of claim 11.

The Blade of the final stage of the low-pressure turbine according to the invention is made of stainless steel, so that their machining properties are excellent and the cost compared to the cost of Ti-based alloy are substantially low.

A Blade of the final stage of a low-pressure steam turbine is one the crucial parts for the Determining the power of a turbine. To get a longer blade of the blade the final stage of the low-pressure steam turbine was to realize it is necessary to develop materials that are both of great strength as well as a big one toughness to have. The martensitic stainless steel used for the blade the final stage of the low-pressure steam turbine according to the invention is used, fulfilled these two requirements and allows the use of the blade the final stage with a value of at least 125,000 of a blade length (inches) times the number of revolutions (rpm) of a turbine.

According to the present Invention is at the steam turbine (number of revolutions: 3,600 Rpm) the length of the vane section of the low pressure turbine's final stage at 914 mm (36 inches) or more, preferably 965 mm (38 inches) or more; and at the steam turbine (number of revolutions: 3,000 rpm) the length of the vane section of the low-pressure turbine's final stage to 1,092 mm (43 inches) or more, preferably 1.168 mm (46 inches) or more. Furthermore, [the length of a blade section (inch)] times the number of revolutions (Rpm)] is set to 125,000 or more, preferably 138,000 or more.

In the inventive 12 Cr-based heat-resistant steel, especially when used in steam at a temperature of 625 ° C or more, the material exhibits preferably more than 10 ⁵ h creep rupture strength of 10 kgf / mm ² or more and an impact absorption energy (at room temperature) of 1 kgf-m or more.

(1) It will be the reason for the limit of the content of each component of 12% Cr-based Steel, for used the blade of the final stage of the low-pressure turbine according to the invention is explained.

C is required to be in an amount of at least 0.08% by weight supplied to ensure the tensile strength. If C in too much quantity added becomes, becomes toughness reduced. The content of C is preferably 0.10 to 0.18% by weight, more preferably 0.12 to 0.16 % By weight.

Si and Mn are used as a deoxidizer in melting the steel and added as a deoxidizer or desulfurizer. These Effect can be done by adding of the element can be achieved in a small amount. Si is a δ-ferrite producing Element, and therefore, the addition of Si in a large amount can produce undesirable δ-ferrite, a reduction in fatigue resistance and toughness causes. The content of Si must be 0.25% by weight or less. In the case when using a carbon / vacuum oxidation process or an electroslag smelting process is applied, no Si need be added, and Si should not added become. In particular, the content of Si may be in a range of 0.10 weight% or less, preferably in one range of 0.05% by weight or less.

The infliction from Mn in big Quantity reduces the toughness. The content of Mn must be 0.9% by weight or less. Especially can improve toughness the content of Mn, which acts as a deoxidizer, in a range of 0.4% by weight or less, preferably 0.2% by weight or fewer.

Cr causes an increase the corrosion resistance and the tensile strength of the alloy; however, can the addition of Cr in an amount of 13% by weight or more, a δ-ferrite structure cause. The addition of Cr in an amount of less than 8% by weight is not enough out, so that Cr an increase of Corrosion resistance and tensile strength causes. The salary Cr may be in a range of 8 to 13% by weight. To the Increase strength, the content of Cr is preferably in a range of 10.5 to 12.5 % By weight, more preferably 11 to 12% by weight.

Not a word causes an increase the tensile strength of the alloy by its function of promotion of solid solution and precipitation. However, this effect is not very strong, and the addition of Mo in an amount of 3% by weight or more may lead to δ-ferrite. Of the Mo content is limited to a range of 1.5 to 3.0% by weight. Especially For example, the content of Mo is preferably in a range of 1.8 to 2.7 % By weight, more preferably 2.0 to 2.5% by weight. It should be emphasized that W and Co have the same effect as Mo.

V and Nb cause an increase the tensile strength and improve the toughness by their function of precipitation of carbides. When the content of V is 0.05% by weight or less is and the content of Nb is 0.02% by weight or less the above effect is insufficient. The addition of V in an amount of 0.35% by weight or more and Nb in an amount of 0.2% by weight or more may lead to δ-ferrite. In particular, the Content of V in a range of 0.15 to 0.30% by weight, preferably 0.25 to 0.30% by weight; and the content of Nb can be in one Range from 0.04 to 0.15% by weight, preferably 0.06 to 0.12% by weight. It should be emphasized that Ta is in place of or added in combination with Nb can be.

Ni causes an increase toughness at low temperatures and prevents the appearance of δ-ferrite. When the content of Ni is 2% by weight or less, may this effect can not be achieved sufficiently. If he is more is 3% by weight, the infliction works filling. In particular, the content of Ni is preferably in one range from 2.3 to 2.9% by weight, more preferably 2.4 to 2.8% by weight.

N causes an improvement in the tensile strength and prevents the occurrence of δ-ferrite. If the Content of N is less than 0.02% by weight, the effect can not achieved to a sufficient degree become. If it is more than 0.1% by weight, the toughness becomes reduced. In particular, the content of N is preferably in one Range of 0.04 to 0.08% by weight, more preferably 0.06 to 0.08% by weight.

The Reducing the content of Si, P and S causes an increase in the toughness at low temperatures while ensures the tensile strength becomes. The content of Si, P and S is desirably so far as possible reduced. Toughness At low temperatures, the content of Si are in a range of 0.1% by weight or less; the salary P may be in a range of 0.015% by weight or less; and the content of S may be in a range of 0.015% by weight or less lie. In particular, the content of Si is preferably in a range from 0.05% by weight or less; the content of P is preferred in a range of 0.010% by weight or less; and the salary S is preferably in a range of 0.010% by weight or less. The reduction in the content of Sb, Sn and As also causes a increase toughness at low temperatures, and therefore it is desirable to increase the content Sb, Sn and As as far as possible to reduce. Considering the existing technical level However, in steelmaking, the content of Sb can be in one range of 0.0015% by weight or less; the content of Sn can in a range of 0.01% by weight or less; and the Content of As can be in a range of 0.02% by weight or less lie. In particular, the content of Sb is preferably in a range of 0.001% by weight or less; the content of Sn is preferred in a range of 0.005% by weight or less; and the salary an As is preferably in a range of 0.01% by weight or fewer.

According to the invention The relationship (Mn / Ni) preferably in a range of 0.11 or less.

The heat treatment the material of the invention is preferred by uniform heating of the material to a temperature that is a perfect Austenitumwandlung allowed, i. in a range of 1,000 to 1,100 ° C, followed of rapid cooling (preferably oil cooling) of the Materials, heating to a temperature and maintaining a temperature from 550 to 570 ° C, followed by a cool of the material (primary Tempering), and heating to a temperature and maintaining a Temperature of 560 to 680 ° C, followed from a cooling down of material (secondary Tempering), thereby a martensite structure with full hardness to obtain.

Short description the drawings

1 Fig. 15 is a graph showing a relationship between a tensile strength and a (Ni-Mo) amount (weight%);

2 Fig. 15 is a graph showing a relationship between a notch impact strength and a (Ni-Mo) amount (% by weight);

3 Fig. 15 is a graph showing a relationship between a tensile strength and a quenching temperature;

4 Fig. 15 is a graph showing a relationship between a tensile strength and a tempering temperature;

5 Fig. 15 is a graph showing a relationship between a notch impact strength and a quenching temperature;

6 Fig. 12 is a graph showing a relationship between a notch impact strength and a tempering temperature;

7 Fig. 12 is a graph showing a relationship between a notch impact strength and a tensile strength;

8th is a sectional view of a structure of a low-pressure steam turbine according to the invention;

9 is a perspective view of a turbine blade according to the invention;

10 is a sectional view of a low-pressure steam turbine according to the invention;

11 is a sectional view of a rotor shaft for the low-pressure steam turbine according to the invention; and

12 is a perspective view of a Leitendabschnitts a turbine blade according to the invention.

Best way of performing the Invention (embodiment 1)

table Figure 1 shows chemical compositions (% by weight) of 12% Cr based steels, as a material for Long shovels for used in steam turbines. Each sample of 150 kg was through melted a vacuum arc melt, to a temperature of less than 1,150 ° C heated and forged to produce an experimental material. Sample No. 1 was at 1,000 ° C heated for one hour and by oil quenching to room temperature chilled and subsequently at 570 ° C heated, this temperature being maintained for two hours, and air-cooled. Sample No. 2 was heated for one hour at 1050 ° C and by oil quenching cooled to room temperature, and subsequently at 570 ° C heated, this temperature being maintained for two hours, and air-cooled. Each of Sample Nos. 3 to 6 was heated at 1,050 ° C for one hour and by oil quenching cooled to room temperature, and subsequently at 560 ° C heated, this temperature being maintained for two hours, and air-cooled (primary tempering), and continue to 580 ° C heated, this temperature being maintained for two hours, and oven-cooled (secondary Tempering).

In Table 1 are samples Nos. 3 and 4 of the present invention, samples Nos. 5 and 6 are comparative materials; and Samples Nos. 1 and 2 existing materials for Long blades.

Table 2 shows mechanical properties of these samples at room temperature. The results shown in Table 2 show that each of the inventive materials (Sample Nos. 3 to 5) has sufficient tensile strength (120 kgf / mm ² or more, or 128.5 kgf / mm ² or more) and sufficient toughness at low Temperatures has (Charpy-V notch impact strength (at 20 ° C): 2.5 kgf-m / cm ² or more), which is required for a long-blade material for a steam turbine.

In contrast, each of the samples Nos. 1 and 6 as comparative materials exhibits a tensile strength and impact resistance lower than required for a long blade for a steam turbine. Sample No. 2 as a comparative material has a low tensile strength and toughness. Sample No. 5 shows an impact strength of 3.8 kgf-m / cm ² , which is slightly lower than a value of 4 kgf-m / cm ² or more, which is required for a long-blade of 43 inches or more.

Table 2

1 Fig. 15 is a graph showing a relationship between a (Ni-Mo) amount and a tensile strength. In this embodiment, both the strength and the toughness at low temperatures are improved by adjusting the content of Ni and Mo so that both are substantially equal. As the difference between the content of Ni and Mo becomes larger, the strength becomes lower. As in 1 As shown, the strength decreases rapidly when the Ni content is smaller than the Mo content by 0.6% or more. On the other hand, if the Ni content is larger than the Mo content by 1.0% or more, the strength also decreases rapidly. As a result, the (Ni-Mo) amount capable of increasing the strength is in the range of -0.6% to 1.0%.

2 Fig. 15 is a graph showing a relationship between a (Ni-Mo) amount and a impact resistance. As shown in the figure, the impact resistance is low in the vicinity of -0.5% of the (Ni-Mo) amount, and is high in the ranges of less than -0.5% and more than 0.5% of the ( Ni-Mo) amount.

4 to 6 are graphs showing effects of heat treatment conditions (quenching temperature and secondary inlet temperature) on tensile strength and impact resistance for Sample No. 3. The quenching temperature is in a range of 975-1,125 ° C, and the primary rim temperature is in the range of 550-560 ° C, and the secondary rim temperature is in the range of 560 ° C-590 ° C. The results shown in the figures confirm that Sample No. 3 heat-treated under the above-mentioned heat treatment conditions has characteristics required for a long-blade material (tensile strength ≥ 128.5 kgf / mm ² , Charpy-V impact value (at 20 ° C) ≥ 4 kgf-m / cm ² ). In addition, the secondary inlet temperature is in 3 and 5 at 575 ° C, and the quenching temperature in each of the 4 and 6 is 1,050 ° C.

7 Fig. 15 is a graph showing a relationship between tensile strength and impact resistance. The 12% Cr-based steel in this embodiment, as described above, preferably has a tensile strength of 120 kgf / mm ² or more and an impact resistance of 4 kgf-m / cm ² or more, and more preferably has an impact resistance (y). which is not lower than a value obtained by an equation of [-0.45 × (tensile strength) + 61.5].

Of the 12% Cr-based according to the invention Steel preferably has such a composition that the (C + Nb) amount in a range of 0.18 to 0.35%, the ratio (Nb / C) in a range of 0.45 to 1.00 and the ratio (Nb / N) in a range of 0.8 to 3.0.

Embodiment 2

A sudden increase in fuel costs following the oil crisis, as a turning point, required that a direct coal burning boiler with a steam temperature of 600 to 649 ° C and a steam turbine be used for the purpose of improving the thermal efficiency by the Requirements for the steam were tightened. An example of a boiler used under these more stringent steam requirements is shown in Table 3.

Table 3

With the increase in power plant output increases the size of one Pulverized coal combustion furnace. For a power plant output the class of 1,050 MW has e.g. the oven has a width of 31 m and a depth of 16 m; and for The stove has a power output of 1,400 MW Width of 34 m and a depth of 18 m.

Table 4 shows a main specification of a steam turbine in which the steam temperature is set to 625 ° C and the power plant output is set to 1,050 MW. The steam turbine in this embodiment is a twin-shaft / quadruple-flow exhaust turbine. In this steam turbine, the length of an end stage vane in a low pressure turbine is 43 inches. A turbine assembly A has a turbine combination of [(HP-IP) + 2 × LP] and is operated at a revolution number of 3,000 rpm, and a turbine assembly B has a turbine combination of [(HP-LP) + (IP-LP)]. and is operated at a speed of 3000 rpm. The main components of the high pressure section are made of materials shown in Table 4. In the high temperature section (HP), the steam temperature is 625 ° C and the steam pressure is 250 kgf / cm ² . The steam supplied from the HP section is heated by a reheater to 625 ° C and is supplied to the intermediate pressure section (IP). The intermediate pressure section is operated at a steam temperature of 625 ° C and a steam pressure of 45 to 65 kgf / cm ² . The steam is supplied into the low pressure section (LP) at a steam temperature of 400 ° C, and the steam is supplied to a steam condenser at a steam temperature of 100 ° C or less and under a reduced pressure of 722 mm Hg.

Table 4

8th Figure 11 is a sectional view of two tandem turbines, the construction of which is substantially the same. Two sets, each of which consists of blades 41 composed of eight stages, are distributed substantially symmetrically right and left, and vanes 42 are according to the blades 41 intended. The End Blade has a length of 43 inches and is made of 12% Cr-based steel, which corresponds to Sample No. 7 shown in Table 1. The End Blade is a Double Spigot / Saddle Dovetail Type which is used in 9 shown, and a nozzle box 44 is of a double flow type. A rotor shaft 43 is made of a forged high-grade steel, which has a bainitic structure with full hardness. More specifically, the forged steel contains 3.75 weight% Ni, 1.75 weight% Cr, 0.4 weight% Mo, 0.15 weight% V, 0.25 weight% C, 0.05 weight % Si and 0.10% by weight Mn, the balance being Fe. The blades, except for the end blade, and the vanes are made of a 12% Cr-based steel containing 0.1% Mo by weight. The inner and outer casings are made of cast steel containing 0.25% C by weight. In this embodiment, the distance between the centers of bearings 43 7,500 mm; the diameter of an ab Section of the rotor shaft, which belongs to the vane, is approximately 1280 mm; and the diameter of a blade insert portion of the rotor is 2,275 mm. The ratio of the distance between the bearings to the diameter of the portion of the rotor shaft associated with the vane is about 5.9.

9 Figure 10 is a perspective view of a 1.092 mm (43 inch) long bucket. The reference number 51 denotes a blade portion to which high-velocity steam collides; 52 is an insert portion of the rotor shaft; 53 is an opening into which a pin is inserted to hold the blade to which a centrifugal force is applied; 54 is an erosion protection shield (a plate made of stellite, which is a Co-based alloy, and fixed by welding) for preventing erosion caused by water drops in the vapor; and 57 is a cover. In this embodiment, the long blade is made by cutting a one-piece, forged part. It is worth noting that the cover 57 can be mechanically formed in a state in which it is integral with the long blade.

The 43 inch long blade is made by melting a material an electroslag remelting process is prepared followed by Forging and heat treatment. The forging was at a temperature in the range of 850 up to 1,150 ° C carried out, and the heat treatment was performed under the conditions described in the first embodiment are described. Sample No. 7 in Table 1 shows a chemical Composition (% by weight) of the material of the long blade. The Metal structure of the material of the long blade was a martensite structure with full hardness.

The tensile strength at room temperature and the Charpy-V impact strength (at 20 ° C) of Sample No. 7 are shown in Table 1. It is confirmed that the 43 inch long blade exhibits sufficient mechanical properties with the required characteristics, in particular a tensile strength of 128.5 kgf / mm ² or more and a Charpy-V notched impact strength (at 20 ° C) of 4 kgf-m / mm ² or more.

at the low-pressure turbine of this embodiment increases the axial Foot width a blade insert portion of the rotor shaft stepwise in four steps in the following order: first to third Stage, fourth stage, fifth Level, sixth and seventh level, and eighth level. The axial foot width of the last stage bucket insert section becomes 6.8 times greater than that of the first stage blade insert section.

The Diameter of the sections of the rotor shaft leading to vanes belong, are small. The axial foot width of the section belonging to the vane gradually increases in three steps in the following order: fifth step, sixth step and seventh step from the side of the first stage blade. The axial Foot width of the section leading to the vane on the side of the power amplifier belongs, will be 2.5 times larger than that of the section leading to the vane between the blades heard the first and second stage.

at this embodiment is the number of blades six. The length of the blade section of the Blade rises from about 3 inches at the first stage to 43 inches at the power amplifier. Dependent From the power of the steam turbine, each of the lengths of the Blade sections from the first to the last blade in a range of 80 to 1,100 mm set; the number of stages is 8 or 9; and the length the blade portion of the blade on the downstream side gets bigger than that of the blade portion of the adjacent blade on the upstream Side, in a relationship from 1.2 to 1.8.

Of the Diameter of the section where the blades are larger than that of the section that belongs to the vane. The larger the length of the blade section the blade is the bigger the width of the blade insert section. The ratio of Width of the blade insert section to the length of the Blade portion of the blade is in the range of 0.15 to 0.91 and will be in order from the first stage to the last Step by step smaller.

The axial foot width the portion of the rotor shaft associated with the vane becomes progressively smaller, from that between the blades the first and second stages to that between the blade the power amp and the previous one. The ratio of the axial foot width the portion of the rotor shaft associated with the vane, to the Length of the Blade portion of the blade is in the range of 0.25 to 1.25 and is from the upstream side to the downstream side smaller.

The structure of this embodiment can be applied to a large-capacity power plant (the class of 1,000 MW) in which the temperature at a steam inlet to a high pressure steam turbine and an intermediate pressure steam turbine is set to 610 ° C and the temperature to a steam let each set to two low-pressure steam turbines at 385 ° C.

The High temperature / high pressure steam turbine plant of this embodiment mainly includes one Coal combustion boiler, a high-pressure turbine, an intermediate-pressure turbine, two low-pressure turbines, a steam condenser, a condensate pump, a low pressure feed water heater system, a degassing apparatus, a boost pump, a feedwater pump and a high pressure feedwater heater system. In this turbine plant flows Ultra high temperature / high pressure steam; which is generated by the boiler The high-pressure turbine is used to generate energy reheated the boiler and flows into the intermediate pressure turbine, to generate energy. The Dampof, from the intermediate pressure turbine dissipated becomes, flows into the low-pressure turbine to generate energy, and is subsequently discharged from condensed the capacitor. The condensed water is through the condensate pump the low pressure feedwater heater system and the degassing device supplied. The water of the Degassing device was degassed is by the boost pump and the feedwater pump of the high-pressure feedwater heater supplied through heated the heater and then returned to the boiler.

In The boiler is fed by a preheater, an evaporator and water a superheater converted into high temperature / high pressure steam. At the same time the fuel gas flows in the boiler, which is used to heat the steam, from the preheater and enters an air heater. In addition, a turbine, the operated by extraction steam from the intermediate pressure turbine, used to drive the feedwater pump.

at the high-temperature / high-pressure steam turbine plant with the above-described Build up will be the temperature of the fuel gas flowing in from the preheater removed the boiler is necessarily much higher than in a conventional one Boiler, since the temperature of feedwater, that of the high pressure feedwater heating system dissipated will, much higher is considered the temperature of the feedwater in a conventional Thermal power plant. Accordingly, the heat recovered from the exhaust of the boiler to the gas temperature reduce.

Of the Structure of this embodiment can be applied to a tandem combined cycle power plant, in which a high-pressure turbine, an intermediate-pressure turbine and one or two Low-pressure turbines are connected in tandem to one another Turn generator to generate energy. At the generator, the in this embodiment has a power of the class of 1,050 MW, is a generator shaft made of a material of high strength.

The High-pressure turbine shaft has a construction in which nine blade stages are used on each multi-stage side, the center of a Blade insert portion of the first stage is. The mid-pressure turbine shaft is with two sentences each of which consists of six blade stages, the essentially symmetrical right and left with respect to an approximately central Section of the turbine shaft are arranged. While the rotor shaft of the low-pressure turbine is not shown in any of the drawings, also has one of the rotor shafts the high pressure, intermediate pressure or low pressure turbine has a central opening, through the material quality by ultrasonic testing, visual examination and dye penetration test is checked. The material quality The rotor shaft can be checked from its outer surface by ultrasonic testing. In this case it is possible that the above-mentioned central opening is not formed in the rotor shaft.

Table 5 shows a main specification of a steam turbine in which the steam temperature is set to 600 ° C and the power plant capacity is set to 600 MW. In this embodiment, the steam turbine is a tandem compound / double flow type, and the length of a final stage blade in a low pressure turbine is 43 inches. A turbine assembly C has a turbine combination of [(HP / IP) one-piece type + LP), and a turbine assembly D has a turbine combination of [(HP / IP) one-piece type + 2 x LP], each operating at a speed of 3000 rpm becomes. The main components of the high pressure section are made of materials shown in Table 9. In the high temperature section (HP), the steam temperature is 600 ° C and the steam pressure is 250 kgf / cm ² . The steam supplied from the HP section is heated to 600 ° C by a reheater and is supplied to the intermediate pressure section (IP). The intermediate pressure section is operated at the steam temperature of 600 ° C and a steam pressure of 45 to 65 kgf / cm ² . The steam is supplied to the low pressure section (LP) at a steam temperature of 400 ° C, and the steam is supplied to a steam condenser at a steam temperature of 100 ° C or less and in a vacuum of 722 mm Hg.

Table 5

10 is a sectional view of the low-pressure turbine, and 11 is a sectional view of a rotor shaft of in 10 shown low-pressure turbine. A low pressure turbine is connected in tandem with the high pressure / intermediate pressure side. Two sets, each consisting of six stages of blades 41 exist are arranged substantially symmetrically right and left. vanes 42 are arranged so that they correspond to the blades. The blade of the final stage has a length of 43 inches and is made of a 12% Cr based steel as shown in Table 1. A rotor shaft 43 is made of a forged high-grade steel, which has a bainitic structure with full hardness. More specifically, the forged steel contains 3.75 weight% Ni, 1.75 weight% Cr, 0.4 weight% Mo, 0.15 weight% V, 0.25 weight% C, 0.05 weight % Si and 0.10% by weight Mn, with Fe forming the balance. The blades, except those of the final stage and the preceding stage, and the vanes are made of a 12% Cr-based steel containing 0.1% Mo by weight. The inner and outer casings are made of cast steel containing 0.25% C by weight. In this embodiment, the distance between the centers of the bearings 43 7,000 mm; the diameter of a portion of the rotor shaft associated with the vane is about 800 mm. The diameter of the blade insert portion of the rotor shaft does not change from the first stage to the last stage. The ratio of the distance between the bearings to the diameter of the portion of the rotor shaft associated with the vane is about 8.8.

The axial foot width the blade insert section of the rotor shaft of the low-pressure turbine, is the smallest at the first level and gradually increases four steps to the downstream Page. The axial foot width at the second stage is equal to that at the third stage, and the axial foot width at the fourth stage is the same at the fifth stage. The axial foot width at the output stage is 6.2 to 7.0 times larger than at the first stage. The axial foot width each at the second and third stages is 1.15 to 1.40 times greater than at the first stage; the axial foot width respectively at the fourth and fifth Stage is 2.2 to 2.6 times larger than each at the second and third stages; and the axial foot width at the final stage is 2.8 to 3.2 times larger than at the fourth and and fifth Step. In the drawing, the width of a blade insert section indicated by a distance between two points the downwardly extending lines of the bucket insert section cut the diameter of the rotor shaft.

at this embodiment the length increases of the blade portion of the blade of about 4 inches at the first stage at 43 inches at the final stage. Depending on the power of the steam turbine lies each of the lengths the vane sections from the first to the last blade in a range of 100 to 1,270 mm; the number of levels is maximum 8th; and the length the blade portion of the blade on the downstream side rises opposite that of the vane portion of the adjacent vane on the upstream side in a relationship from 1.2 to 1.9.

in the Compared to the shape of the portion associated with the vane extends down the shape of the blade insert section. The bigger the Length of the Blade portion of the blade is the larger the width of the blade insert section. The ratio of Width of the blade insert section to the length of the Blade portion of the blade, which is in the range of 0.30 is up to 1.5, becomes direct from the first stage to the stage gradually smaller before the power amp. At the downstream side will the ratio at one level 0.15 to 0.40 times smaller than the previous one Step. The relationship at the output stage is in a range of 0.50 to 0.65.

The moving blade of the final stage in this embodiment is the same as described for embodiment 1. 12 FIG. 15 is a perspective view in which a substantial portion is cut away, showing a state in which an erosion protection shield (a stellite alloy) is cut off; FIG. 54 by electron beam welding or TIG welding, as indicated by the reference numeral 56 shown. As shown in the drawing, the shield is 54 welded at two points on the front and back.

Of the Structure of this embodiment can for a power plant with high capacity (the class of 1,000 MW) are applied at which the temperature at a steam inlet to a high pressure / intermediate pressure steam turbine 610 ° C or is more and the temperatures of a steam inlet and a steam outlet to and from a low-pressure steam turbine about 400 ° C and 60 ° C, respectively.

The High temperature / high pressure steam turbine power plant of this embodiment includes mainly a boiler, a high pressure / intermediate pressure turbine, a low pressure turbine, a steam condenser, a condensate pump, a low pressure feed water heating device system, a degassing device, a boosting pump, a feedwater pump and a high pressure feed water heating device system. Ultra high temperature / high pressure steam, generated by the boiler flows into the high-pressure side turbine, to generate energy is reheated by the boiler and flows into the intermediate pressure side turbine, to generate energy. The steam coming from the high pressure / intermediate pressure turbine dissipated becomes, flows in the low-pressure turbine to generate energy and is subsequently from condensed the capacitor. The condensed water is through the condensate pump the low pressure feedwater heating system and the degassing device supplied. That of the degassing device Degassed water is through the boost pump and the feedwater pump the high-pressure feedwater heating device supplied is heated by the heating device and then in returned to the boiler.

In The boiler is fed by a preheater, an evaporator and water a superheater converted into high temperature / high pressure steam. Meanwhile, the fuel gas flows in the boiler, which is used to heat the steam, from the preheater and enters an air heater. In addition, a turbine, the operated by extraction steam from the intermediate pressure turbine, used to drive the feedwater pump.

In the high-temperature / high-pressure steam turbine plant having the above construction, the temperature of the fuel gas discharged from the preheating in the boiler is necessarily much higher than that in a conventional boiler because the temperature of the feed water discharged from the high-pressure reservoir sewasser-Erhitzungsvorrichtungssystem is much higher than the temperature of the feedwater in a conventional thermal power plant. Accordingly, the heat of the exhaust gas of the boiler is recovered to lower the gas temperature.

Even though in this embodiment applied the present invention in a tandem compound / double-power plant in which a high pressure / intermediate pressure turbine and a low pressure turbine connected in tandem with a generator can, the present invention also in the turbine construction D applied, the high performance of the class of 1,050 MW has, as shown in Table 5, and which is characterized that two low-pressure turbines are connected in tandem. at the generator with a capacity of 1,050 MW is one Generator shaft made of a material with high strength.

Claims (11)

A steam turbine power plant with a combination of a high pressure turbine, an intermediate pressure turbine and a low pressure turbine, wherein a value of the length of a blade (inches) times the number of revolutions (rpm) of a rotor of the final stage of the low pressure turbine is at least 125,000, characterized in that the rotor of the final stage of Martensitic stainless steel low-pressure turbine which is 0.08 to 0.18 weight percent C, 0.25 weight percent or less Si, 0.90 weight percent or less Mn, 8.0 to 13.0 weight percent Cr, 2 to 3 weight percent Ni, 1.5 to 3.0 wt% Mo, 0.05 to 0.35 wt% V, 0.02 to 0.20 wt% total of at least one of Nb and Ta, and 0.02 to 0.10 wt% N contains. Steam turbine power plant according to claim 1, characterized in that the tensile strength of the martensitic stainless steel at room temperature is 120 kgf / mm ² or more. Steam turbine power plant according to claim 1, characterized in that that the martensitic stainless steel has a martensite structure with full hardness Has. Steam turbine power plant according to claim 1, characterized in that that the martensitic stainless steel contains substantially no δ-ferrite. Steam turbine power plant according to claim 1, characterized in that that in the martensitic stainless steel a relationship between Mn amount and Ni amount is 0.11 or less. Steam turbine power plant according to claim 1, characterized in that that the martensitic stainless steel is made that a P amount of 0.015 wt% or less, an S amount to 0.015% by weight or less, an amount of Sb to 0.0015 Percent by weight or less, an amount of Sn to 0.01 wt% or less and an amount of As to 0.02 wt% or less limited is. Steam turbine power plant according to claim 1, characterized in that that the steam inlet temperature for a blade of the first High-pressure turbine stage is in the range of 600 to 660 ° C. Steam turbine power plant according to claim 1, characterized in that that the steam inlet temperature for a blade of the first Low-pressure turbine stage is in the range of 380 to 475 ° C. Steam turbine power plant according to claim 1, characterized in that that the high pressure turbine and the intermediate pressure turbine formed integrally are. Steam turbine power plant according to claim 1, characterized in that the low-pressure turbine in a rotor shaft ( 43 ) used blades ( 41 ) and vanes ( 42 ) for guiding the steam flow to the blades ( 41 ), five stages of blades ( 41 ) or more, which are arranged symmetrically, and has a double-flow structure, in which the first-stage moving blade is arranged in the middle part of the rotor shaft. A method of manufacturing a turbine blade of the low pressure turbine power plant in a steam turbine power plant having a high pressure turbine, an intermediate pressure turbine, and a low pressure turbine, wherein a value of a blade length (inches) times the number of revolutions (rpm) of the blade of the low pressure turbine final stage is at least 125,000 by melting a steel material, 0.08 to 0.18 weight percent C, 0.25 weight percent or less Si, 0.90 weight percent or less Mn, 8.0 to 13.0 weight percent Cr, 2 to 3 weight percent Ni, 1.5 to 3.0 Weight percent Mo, 0.05 to 0.35 weight percent V, 0.02 to 0.20 weight percent total of at least one of the elements Nb and Ta and 0.02 to 0.10 weight percent N contains, for the production of a banquet, and by forging banana, quenching the bar by heating the bar and holding the bar at a) temperature of 1,000 to 1,100 ° C and rapid cooling of the bar, by primary tempering of the bar by heating the bar and holding the bar at a temperature of 550 to 570 ° C and cooling the billet and secondarily tempering the billet by heating the billet and holding the billet to a temperature of 560 to 590 ° C and cooling the billet to form a hardened martensite structure.