Method for operating a steam turbine installation

Abstract

To provide an operation method of a steam turbine facility capable of reducing a loss due to moisture of steam and a risk of erosion in the steam turbine facility of a low output zone.SOLUTION: The method includes a step of driving the high-pressure turbine and the low-pressure turbine under a condition in which a ratio of a difference between an inlet pressure of the low-pressure turbine and an outlet pressure of the low-pressure turbine to a difference between an inlet pressure of the high-pressure turbine and an outlet pressure of the low-pressure turbine is 0.16 or less and under a condition in which power is equal to or lower than a 500MW.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for operating a steam turbine installation. [Background technology]

[0002] Generally, in steam turbines for nuclear power plants, the temperature and pressure of steam at the inlet of the low-pressure turbine are lower than in steam turbines for thermal power plants, and the steam becomes wet soon after entering the low-pressure turbine, resulting in a high degree of wetness at the outlet of the low-pressure turbine. High steam wetness in steam turbines leads to increased moisture loss and erosion due to water droplets, so measures must be taken.

[0003] Patent Document 1 discloses a nuclear power plant in which a steam pipe with a larger diameter than conventional is installed between a high-pressure turbine and a low-pressure turbine. By using a steam pipe with a larger diameter than conventional, the inlet pressure of the low-pressure turbine is reduced compared to conventional cases, slowing the steam flow rate and lengthening the residence time of steam in a moisture separator heater installed in the steam pipe, thereby improving the performance of the moisture separator heater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 029911 Summary of the Invention [Problem to be solved by the invention]

[0005] In a steam turbine for a nuclear power plant, when trying to suppress the effects of high steam wetness (wetness loss and erosion), it is possible to reduce the steam pressure at the low-pressure turbine inlet as described in Patent Document 1, or to increase the steam temperature at the low-pressure turbine inlet.

[0006] However, the temperature of the steam at the inlet of the low-pressure turbine is limited by factors such as the temperature of the heat source for reheating the steam flowing from the high-pressure turbine to the low-pressure turbine, and so there is a limit to how high it can be increased. Also, as described in Patent Document 1, the steam pressure at the inlet of the low-pressure turbine can be reduced by increasing the diameter of the piping between the high-pressure turbine and the low-pressure turbine, but if the piping diameter is increased, it becomes difficult to manufacture a large-capacity valve that fits the piping, so there is a limit to how low the steam pressure at the inlet of the low-pressure turbine can be reduced.

[0007] For this reason, conventional nuclear power plants operate steam turbine equipment under operating conditions where the steam in the steam turbine has a relatively high wetness. To combat this, a drain catcher is installed on the first stage of the low-pressure turbine. The drain catcher includes a recess in the wall of the casing, and is designed to catch and collect water droplets that are thrown radially outward by the centrifugal force of the rotor blades.

[0008] Meanwhile, there is an increasing demand for small modular reactors (SMRs), which are smaller and designed for lower power output than conventional nuclear reactors. In low-power nuclear plants using SMRs and other reactors, it is desirable to operate steam turbines under conditions that can suppress the effects of steam wetness (wetness loss and erosion).

[0009] In view of the above circumstances, at least one embodiment of the present invention aims to provide a method for operating steam turbine equipment that can reduce the risk of steam wetness and erosion in steam turbine equipment in a low power range. [Means for solving the problem]

[0010] A method for operating a steam turbine facility according to at least one embodiment of the present invention includes: 1. A method for operating a steam turbine facility including a high-pressure turbine supplied with steam generated by utilizing heat generated in a nuclear reactor, and a low-pressure turbine supplied with steam discharged from the high-pressure turbine, comprising: driving the high-pressure turbine and the low-pressure turbine under steam conditions in which a ratio of a difference between the inlet pressure of the high-pressure turbine and the outlet pressure of the low-pressure turbine to a difference between the inlet pressure of the low-pressure turbine and the outlet pressure of the low-pressure turbine is 0.16 or less, and under output conditions of 500 MW or less. [Effects of the Invention]

[0011] According to at least one embodiment of the present invention, there is provided a method for operating a steam turbine facility in a low power range, which can reduce the risk of steam loss and erosion due to steam wetness. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating a steam turbine installation according to an embodiment. [Figure 2] 1 is a schematic diagram showing the configuration of a nuclear reactor according to an embodiment. [Figure 3] 1 is a schematic diagram illustrating a configuration of a turbine blade of a steam turbine according to an embodiment. [Figure 4] This is an IS diagram showing the relationship between specific enthalpy and specific entropy during expansion of working fluid (steam) in several low-pressure turbines. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0014] (Configuration of steam turbine equipment) Fig. 1 is a schematic diagram showing an example of steam turbine equipment to which an operation method according to some embodiments is applied. Fig. 2 is a schematic diagram showing the configuration of a nuclear reactor according to one embodiment. Fig. 3 is a schematic diagram showing the configuration of turbine blades of a steam turbine according to one embodiment.

[0015] As shown in FIG. 1, a steam turbine facility 1 according to one embodiment includes a steam generating section 2 for generating steam by utilizing heat generated in a nuclear reactor 100 (FIG. 2), a high-pressure turbine 6 to which steam (main steam) from the steam generating section 2 is supplied, and a low-pressure turbine 10 to which steam discharged from the high-pressure turbine 6 is supplied.

[0016] Steam (main steam) generated in the steam generating section 2 is guided to a high-pressure turbine 6 via a high-pressure steam line 4. A valve 5 for adjusting the flow rate of steam supplied to the high-pressure turbine 6 may be provided on the high-pressure steam line 4. The steam whose temperature and pressure have been reduced after performing work in the high-pressure turbine 6 is discharged from the high-pressure turbine 6 and guided to a low-pressure turbine 10 via a low-pressure steam line 8. A valve 9 for adjusting the flow rate of steam supplied to the low-pressure turbine 10 may be provided on the low-pressure steam line 8.

[0017] The low-pressure steam line 8 is provided with a reheat section 20 for reheating steam flowing from the outlet of the high-pressure turbine 6 to the inlet of the low-pressure turbine 10. The reheat section 20 may include a moisture separator heater configured to remove moisture contained in the steam and heat it. As shown in FIG. 1, the reheat section 20 may be configured to heat the low-pressure steam line 8 using steam generated in the steam generating section 2 as a heat source. In the exemplary embodiment shown in FIG. 1, main steam from the steam generating section 2 is supplied to the reheat section 20 via a branch line 18 branching off from the high-pressure steam line 4.

[0018] The steam, whose temperature and pressure have dropped after performing work in the low-pressure turbine 10, is discharged from the low-pressure turbine 10 and led to the condenser 16. In the condenser 16, the steam is condensed by heat exchange with a coolant (seawater, etc.), and condensate is produced. The condensate produced in the condenser 16 is returned to the steam generating section 2 via a condensate line 14.

[0019] 1, the steam turbine equipment 1 may include a generator 12 connected to the rotating shafts of the high-pressure turbine 6 and the low-pressure turbine 10 and configured to be rotationally driven by the high-pressure turbine 6 and the low-pressure turbine 10. In other words, the steam turbine equipment 1 may be a power generation plant.

[0020] 2, the nuclear reactor 100 includes a primary cooling loop 30 through which primary cooling water (primary coolant) flows, and a pressure vessel (reactor vessel) 32, a pressurizer 34, a steam generating unit (steam generator) 2, and a primary coolant pump (coolant pump) 38 provided in the primary cooling loop 30. The primary coolant pump 38 is configured to circulate the primary coolant in the primary cooling loop 30. The pressurizer 34 is configured to pressurize the primary coolant in the primary cooling loop 30 so that the primary coolant does not boil. The pressure vessel 32, the pressurizer 34, the steam generating unit 2, and the primary coolant pump 38 are housed in a reactor containment vessel 40.

[0021] The pressure vessel 32 contains fuel rods containing pellet-shaped nuclear fuel (e.g., uranium fuel, MOX fuel, etc.), and the thermal energy generated by the nuclear fission reaction of this fuel heats the primary coolant inside the pressure vessel 32. The pressure vessel 32 is provided with control rods that absorb and adjust the number of neutrons generated in the core containing the nuclear fuel in order to control the reactor power. The primary coolant heated inside the pressure vessel 32 is sent to the steam generating section 2, and by heat exchange, heats the secondary coolant (secondary coolant) flowing through a secondary cooling loop including the high-pressure steam line 4, the low-pressure steam line 8, and the condensate line 14, thereby generating steam.

[0022] In some embodiments, the nuclear reactor 100 may include a small modular reactor (SMR). A small modular reactor is a small nuclear reactor that can be transported to an installation site after manufacturing, and has a lower output than the reactors used in general nuclear power plants (output: approximately 1000 MW or more), with the output of a power plant using a small modular reactor being approximately 500 MW or less.

[0023] The small modular reactor may be a small modular reactor using a light water reactor, a molten salt reactor, or a high-temperature gas reactor. The light water reactor as a small modular reactor may be a miniaturized version of a conventional pressurized water reactor (PWR) or a boiling water reactor (BWR), or may be an integral pressurized water reactor (iPWR) in which a steam generator and reactor internals are integrated. Note that the reactor 100 shown in FIG. 2 is an example of a pressurized water reactor (PWR).

[0024] 3 is a partial schematic diagram of a low-pressure turbine 10 according to one embodiment. As shown in FIG. 3, the low-pressure turbine 10 includes stationary blades 101 (101A, 101B), an outer ring 102, an inner ring 103, rotor blades 104 (104A, 104B), and a disk 105.

[0025] The inner ring 103 is an annular member provided along the circumferential direction of the turbine rotor. The inner ring 103 has a hollow portion 115 inside. The outer ring 102 is an annular member provided radially outside the inner ring 103 along the circumferential direction of the turbine rotor. The stator vanes 101 are supported by a casing 110 via the outer ring 102. A plurality of stator vanes 101 are fixedly provided between the outer ring 102 and the inner ring 103 along the circumferential direction of the turbine rotor. A plurality of rotor blades 104 are attached to the outer periphery of a disk 105 along the circumferential direction of the turbine rotor.

[0026] A typical low-pressure turbine 10 includes multiple stages of rows of stator vanes and rotor blades arranged along the axial direction. The low-pressure turbine 10 shown in Fig. 3 includes a front stage stator vane 101A, a front stage rotor blade 104A, a rear stage stator vane 101B, and a rear stage rotor blade 104B. The rear stage stator vane 101B and the rear stage rotor blade 104B are located downstream of the front stage stator vane 10A and the front stage rotor blade 104A in the axial direction.

[0027] At least some of the multiple stages of stator vanes 101 are provided with moisture recovery structures 106. In the exemplary embodiment shown in Fig. 3, the rear stage stator vane 101B includes a drain catcher 107 as the moisture recovery structure 106. The drain catcher 107 includes a protrusion 108 that protrudes radially outward from the upstream end of the outer ring 102.

[0028] During operation of the steam turbine equipment 1, if the working fluid flowing through the low-pressure turbine 10 is wet steam, moisture (water droplets) 120 contained in the steam is scattered radially outward by the rotation of the front-stage rotor blades 104A. The drain catcher 107 captures the scattered moisture, thereby preventing the water droplets from flowing into the rear-stage stator blades 101B. This reduces the moisture in the rear stages of the low-pressure turbine 10.

[0029] (Method of operating steam turbine equipment) Next, a method for operating the steam turbine system 1 according to some embodiments will be described. In some embodiments, the inlet pressure P H1 and the outlet pressure P of the low-pressure turbine 10 L2 The difference between (P H1 -P L2 ) the inlet pressure P of the low-pressure turbine 10 L1 and the outlet pressure P of the low-pressure turbine 10 L2 The difference between (P L1 -P L2 ) ratio (P L1 -P L2 ) / (P H1 -P L2 In some embodiments, the high-pressure turbine 6 and the low-pressure turbine 10 are driven under steam conditions where the ratio (P L1 -P L2 ) / (P H1 -P L2 The high-pressure turbine 6 and the low-pressure turbine 10 are driven under steam conditions where the ratio of the heat energy to the heat energy is 0.15 or less or 0.14 or less, and under output conditions of 500 MW or less.

[0030] Figure 4 is an isotropy diagram showing the relationship between specific enthalpy (vertical axis) and specific entropy (horizontal axis) during the expansion of working fluid (steam) in several low-pressure turbines. The graph in Figure 4 includes isothermal lines LT1 (250°C) and T2 (350°C), isobars LP1 (0.005 MPa(a)), LP2 (0.5 MPa(a)), and LP3 (1.0 MPa(a)), as well as isohumidity lines LM0 (saturation line), LM1 (10%), and LM2 (15%). Note that (a) in the pressure unit notation means absolute pressure.

[0031] Curves A to C in the graph of Fig. 4 are expansion lines (curves showing changes in state quantities of steam) from the inlet (points A1 to C1) to the outlet (points A2 to C2) of the low-pressure turbine. Curve A is the expansion line of the low-pressure turbine 10 of the steam turbine equipment 1 (a low-output nuclear plant such as an SMR) according to the above-described embodiment, curve B is the expansion line of the low-pressure turbine of a steam turbine equipment in a conventional nuclear plant (one example) with a relatively high output, and curve C is the expansion line of the low-pressure turbine of a steam turbine equipment in a conventional thermal power plant (one example).

[0032] As shown in the graph of Figure 4, in a conventional nuclear power plant (curve B), the steam temperature (inlet temperature T L1 ) is about 250°C. In a conventional nuclear power plant (curve B), the steam pressure of the low-pressure turbine varies from the inlet pressure (about 1.0 MPa(a)) to the outlet pressure (about 0.005 MPa(a)). At the outlet of the low-pressure turbine, the steam wetness is about 15%.

[0033] In a conventional thermal power plant (curve C), the temperature of the steam at the inlet of the low-pressure turbine (point C1 on the graph) is approximately 350°C. In a conventional thermal power plant (curve C), the steam pressure of the low-pressure turbine varies from the inlet pressure (approximately 1.0 MPa(a)) to the outlet pressure (approximately 0.005 MPa(a)). At the outlet of the low-pressure turbine, the wetness of the steam is approximately 10%.

[0034] In a conventional nuclear power plant, the inlet pressure of the high-pressure turbine P H1 is about 5.5MPa(a), so in conventional nuclear power plants, the above pressure ratio (P L1 -P L2 ) / (P H1 -P L2 ) is about 0.18. In addition, the inlet temperature T H1 is about 270°C.

[0035] In contrast, according to the method of the above embodiment, the above pressure ratio (P L1 -P L2 ) / (P H1 -P L2 Since the steam turbine equipment 1 is operated under steam conditions where the temperature T L1 is set to the same as that of a conventional nuclear power plant (for example, about 250°C), the expansion line (curve A) will be similar to the curve B for a conventional nuclear power plant, which is moved parallel along the isothermal line, and the dryness / superheat of the steam at the inlet of the low-pressure turbine can be increased and the wetness of the steam at the outlet of the low-pressure turbine can be reduced. In other words, the wetness at the low-pressure turbine can be made the same as that of a conventional thermal power plant.

[0036] Furthermore, in the above-described embodiment, a low-power nuclear reactor such as a small modular reactor is used and is operated under low-power conditions of 500 MW or less, so even if the inlet pressure of the low-pressure turbine 10 is lowered as described above, the volumetric flow rate of steam does not become too large, and the diameter of the pipe connected to the inlet of the low-pressure turbine 10 (the pipe constituting the low-pressure steam line 8) does not become excessively large. Therefore, the size of the valve 9 provided on the pipe can be set within a range that can be realistically manufactured.

[0037] As described above, according to the method of the embodiment, in the steam turbine equipment 1 for a nuclear power plant, the inlet pressure PH1 and the outlet pressure P of the low-pressure turbine 10 L2 The inlet pressure P of the low-pressure turbine 10 relative to the difference L1 and the outlet pressure P of the low-pressure turbine 10 L2 Ratio of the difference (pressure difference ratio) (P L1 -P L2 ) / (P H1 -P L2 The high-pressure turbine 6 and the low-pressure turbine 10 are driven under steam conditions where the ratio of the wetness of steam to the wetness of steam is 0.16 or less, 0.15 or less, or 0.14 or less, and under an output condition of 500 MW or less. Therefore, the wetness fraction in the low-pressure turbine can be lowered compared to conventional steam turbines in the high-power range (e.g., over 1000 MW) for nuclear power plants. Therefore, in the steam turbine equipment 1 for low-power nuclear power plants, the risk of wetness loss and erosion due to wetness of steam can be reduced. Furthermore, in the method according to the above embodiment, the wetness in the low-pressure turbine 10 is the same as that of a conventional low-pressure turbine for a thermal power plant, so the same design concept as that of a low-pressure turbine for a thermal power plant can be used. For example, the installation position of the moisture recovery structure can be designed in accordance with that of a low-pressure turbine for a thermal power plant. This allows for the reduction of development costs for a low-pressure turbine for a low-power nuclear power plant.

[0038] In some embodiments, the inlet pressure P of the low-pressure turbine 10 L1 Alternatively, in some embodiments, the high-pressure turbine 6 and the low-pressure turbine 10 may be driven under steam conditions in which the inlet pressure P L1 The high-pressure turbine 6 and the low-pressure turbine 10 may be driven under steam conditions in which the pressure is 0.5 MPa(a) or more and 0.6 MPa(a) or less.

[0039] In the above embodiment, the inlet pressure P L1Since the high-pressure turbine 6 and the low-pressure turbine 10 are driven under steam conditions where the inlet pressure P of the low-pressure turbine 10 is 0.5 MPa(a) or more or 0.4 MPa(a) or more, the plant performance can be improved while keeping the steam flow rate at the valve 9 provided in the inlet piping of the low-pressure turbine 10 (piping constituting the low-pressure steam line 8) within an appropriate range. L1 Since the high-pressure turbine 6 and the low-pressure turbine 10 are driven under steam conditions where the pressure difference is 0.7 MPa(a) or less or 0.6 MPa(a) or less, the pressure difference ratio can be easily set to 0.16 or less, 0.15 or less, or 0.14 or less in a steam turbine facility 1 with an output of 500 MW or less that uses a small modular reactor or the like. Therefore, according to the method of the above embodiment, in a steam turbine facility 1 for a low-power nuclear power plant, the plant performance can be improved while reducing the risk of wetness loss and erosion caused by wet steam.

[0040] In some embodiments, the inlet temperature T of the low-pressure turbine 10 L1 The high-pressure turbine 6 and the low-pressure turbine 10 are driven under steam conditions where the temperature of the steam is 220°C or higher and 280°C or lower.

[0041] According to the above-described embodiment, the inlet temperature T L1 is about the same as that of a conventional nuclear power plant, a configuration similar to that of a conventional nuclear power plant can be adopted as a configuration for reheating steam flowing from the outlet of the high-pressure turbine 6 to the inlet of the low-pressure turbine 10. Therefore, according to the above-described embodiment, it is possible to relatively easily reduce the risk of wetness loss and erosion caused by wetness of steam as described above.

[0042] In some embodiments, the low-pressure turbine 10 includes a front stage stator vane 101A that does not have a moisture recovery structure (such as a drain catcher), and a rear stage stator vane 101B that is provided downstream of the front stage stator vane 101A and has a moisture recovery structure 106 (a drain catcher 107 in FIG. 3), as shown in Fig. 3 for example. Drain (moisture such as water droplets) inside the low-pressure turbine 10 is recovered by the moisture recovery mechanism 106 provided in the rear stage stator vane 101B of the low-pressure turbine 10.

[0043] The front stage stator vanes 101A are upstream stator vanes 101 including the first stage stator vanes 101 among the multiple stages of stator vanes 101, and the rear stage stator vanes 101A are downstream stator vanes 101 including the final stage stator vanes 101 among the multiple stages of stator vanes 101. In some embodiments, of the multiple stages of stator vanes 101 of the low-pressure turbine 10, the front stage stator vanes 101A including the first stage stator vanes 101 may not be provided with a moisture recovery structure (drain catcher, etc.), and the rear stage stator vanes 101B including the final stage stator vanes 101 may be provided with a moisture recovery structure (drain catcher, etc.).

[0044] In the method according to the above-described embodiment, the wetness in the low-pressure turbine 10 is comparable to that of a conventional low-pressure turbine for a thermal power plant, so that the same design concept as that of a low-pressure turbine for a thermal power plant can be utilized. For example, as described above, a configuration can be adopted in which the moisture recovery structure 106 (drain catcher 107, etc.) is not provided on the front stage stator vanes 101A but only on the rear stage stator vanes 101B, as in a typical low-pressure turbine for a thermal power plant. This allows the development costs of a low-pressure turbine for a low-power nuclear power plant to be reduced. Therefore, in the steam turbine equipment 1 for a low-power nuclear power plant, the risk of moisture loss and erosion due to steam wetness can be reduced at low cost.

[0045] In some embodiments, steam from the high-pressure turbine 6 is introduced to the low-pressure turbine 10 via piping provided between the high-pressure turbine 6 and the low-pressure turbine 10 and having a diameter of 50 inches or more. In other words, the diameter of the piping that constitutes the low-pressure steam line 8 provided between the high-pressure turbine 6 and the low-pressure turbine 10 may be 50 inches or more.

[0046] According to the above-described embodiment, the diameter of the pipe for guiding steam from the high-pressure turbine 6 to the low-pressure turbine 10 is 50 inches or more, so in the steam turbine equipment 1 with an output of 500 MW or less, the above-described pressure difference ratio (P L1 -P L2 ) / (P H1 -P L2 ) can be easily set to 0.16 or less, 0.15 or less, or 0.14 or less. Therefore, according to the above-described embodiment, it is possible to reduce the risk of wetness loss and erosion caused by wetness of steam in the steam turbine equipment 1 of a low-power nuclear power plant.

[0047] The contents described in each of the above embodiments can be understood, for example, as follows.

[0048] [1] A method for operating a steam turbine facility (1) according to at least one embodiment of the present invention includes: A method for operating a steam turbine facility including a high-pressure turbine (6) supplied with steam generated by utilizing heat generated in a nuclear reactor (100), and a low-pressure turbine (10) supplied with steam discharged from the high-pressure turbine, comprising: The inlet pressure of the high-pressure turbine (P H1 ) and the outlet pressure of the low-pressure turbine (P L2 ) to the inlet pressure (P L1 ) and the outlet pressure of the low-pressure turbine (P L2 ) and the ratio of the difference (P H1 -P L2 ) / (P L1 -P L2 ) is 0.16 or less and at an output condition of 500 MW or less.

[0049] According to the method [1] above, in a steam turbine facility for a nuclear power plant, the high-pressure turbine and the low-pressure turbine are driven under steam conditions where the ratio of the difference between the inlet pressure of the high-pressure turbine and the outlet pressure of the low-pressure turbine to the difference between the inlet pressure of the low-pressure turbine and the outlet pressure of the low-pressure turbine (pressure difference ratio) is 0.16 or less, and under an output condition of 500 MW or less. Therefore, compared to conventional steam turbines for high-power nuclear power plants (e.g., over 1000 MW), the wetness fraction in the low-pressure turbine can be lowered. Therefore, in steam turbine facilities for low-power nuclear power plants, the risk of wetness loss and erosion due to wet steam can be reduced. Furthermore, in the method [1] above, the wetness in the low-pressure turbine is the same as that of a low-pressure turbine for a conventional thermal power plant, so the moisture removal mechanism of the low-pressure turbine for a thermal power plant can be used as is. Therefore, the low-pressure turbine for a conventional thermal power plant can be used in a nuclear power plant, which reduces the development costs of a low-pressure turbine for a low-power nuclear power plant.

[0050] [2] In some embodiments, in the method of [1] above, The high-pressure turbine and the low-pressure turbine are driven under steam conditions such that the inlet pressure of the low-pressure turbine is 0.4 MPa(a) or more and 0.7 MPa(a) or less.

[0051] In the method [2] above, the high-pressure turbine and the low-pressure turbine are driven under steam conditions where the low-pressure turbine inlet pressure is 0.4 MPa(a) or higher, thereby maintaining the steam flow rate at the valve of the low-pressure turbine inlet piping within an appropriate range and improving plant performance. Furthermore, in the method [2] above, the high-pressure turbine and the low-pressure turbine are driven under steam conditions where the low-pressure turbine inlet pressure is 0.7 MPa(a) or lower, making it easier to achieve the above-mentioned pressure difference ratio of 0.16 or less in steam turbine equipment with an output of 500 MW or less. Therefore, in steam turbine equipment for low-power nuclear power plants, the method [2] above can reduce the risk of wetness loss and erosion due to steam wetness while maintaining good plant performance.

[0052] [3] In some embodiments, in the method of [1] or [2] above, The inlet temperature of the low-pressure turbine (T L1 The high-pressure turbine and the low-pressure turbine are driven under steam conditions in which the temperature of the high-pressure turbine is 220°C or higher and 280°C or lower.

[0053] According to the method of [3] above, since the inlet temperature of the low-pressure turbine is about the same as that of a conventional nuclear power plant, a configuration similar to that of a conventional system can be adopted for reheating the steam flowing from the outlet of the high-pressure turbine to the inlet of the low-pressure turbine. Therefore, according to the configuration of [3] above, it is possible to relatively easily reduce the risk of moisture loss and erosion caused by the moisture content of the steam, as described in [1] above.

[0054] [4] In some embodiments, in any of the methods [1] to [3] above, The low-pressure turbine includes a plurality of stages of stator vanes (101A, 101B) arranged in an axial direction, The plurality of stages of stator vanes include: a forward stage vane (101A) without a moisture recovery structure (106); a rear stage vane (101B) provided axially downstream of the front stage vane and having a moisture recovery structure (106); Including, The method for operating the steam turbine facility includes: The method includes recovering drainage from the low-pressure turbine using the moisture recovery structure.

[0055] According to the method [4] above, moisture is removed from the low-pressure turbine through slits in the stator vanes, just like in conventional low-pressure turbines for thermal power plants, so that conventional low-pressure turbines for thermal power plants can be used in nuclear power plants. This eliminates the development costs of low-pressure turbines for low-power nuclear power plants, and therefore reduces the risk of moisture loss and erosion caused by steam moisture in steam turbine equipment for low-power nuclear power plants at low cost.

[0056] [5] In some embodiments, in any of the methods [1] to [4] above, The method for operating the steam turbine includes: The method includes introducing steam from the high-pressure turbine to the low-pressure turbine via a pipe disposed between the high-pressure turbine and the low-pressure turbine and having a diameter of 50 inches or greater.

[0057] According to the method [5] above, since the diameter of the pipe that guides steam from the high-pressure turbine to the low-pressure turbine is 50 inches or more, it is easy to keep the pressure difference ratio at 0.16 or less in steam turbine equipment with an output of 500 MW or less. Therefore, according to the method [5] above, it is possible to reduce the risk of wetness loss and erosion caused by wet steam in steam turbine equipment for low-power nuclear power plants.

[0058] The above describes an embodiment of the present invention, but the present invention is not limited to the above-described embodiment, and also includes forms in which the above-described embodiment is modified, or forms in which these forms are appropriately combined.

[0059] In this specification, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions representing shapes such as a rectangular shape or a cylindrical shape not only represent rectangular shapes or cylindrical shapes in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components. [Explanation of symbols]

[0060] 1. Steam turbine equipment 2 Steam generation section 4 High-pressure steam line 5 valves 6. High-pressure turbine 8 Low pressure steam line 9 valves 10 Low-pressure turbine 12. Generator 14 Condensate line 16 Condenser 18 Branch Line 20 Reheat section 30 Primary cooling loop 32 Pressure vessels 34 Pressurizer 38 Primary coolant pump 40 Reactor containment vessel 100 reactor 101 Stator blade 102 outer ring 103 Inner Circle 104 Moving blade 105 discs 106 Moisture recovery structure 107 Drain Catcher 108 Protrusion 110 Cabin 120 Moisture (water droplets)

Claims

1. 1. A method for operating a steam turbine facility including a high-pressure turbine supplied with steam generated by utilizing heat generated in a nuclear reactor, and a low-pressure turbine supplied with steam discharged from the high-pressure turbine, comprising: driving the high-pressure turbine and the low-pressure turbine under steam conditions in which a ratio of a difference between an inlet pressure of the high-pressure turbine and an outlet pressure of the low-pressure turbine to a difference between an inlet pressure of the low-pressure turbine and an outlet pressure of the low-pressure turbine is 0.16 or less, and under output conditions of 500 MW or less. How to operate steam turbine equipment.

2. The high-pressure turbine and the low-pressure turbine are driven under steam conditions such that the inlet pressure of the low-pressure turbine is 0.4 MPa (a) or more and 0.7 MPa (a) or less. The method for operating a steam turbine facility according to claim 1 .

3. The high-pressure turbine and the low-pressure turbine are driven under steam conditions in which the inlet temperature of the low-pressure turbine is 220°C or higher and 280°C or lower. The method for operating a steam turbine facility according to claim 1 or 2.

4. the low-pressure turbine includes a plurality of stages of stator vanes arranged in an axial direction; The plurality of stages of stator vanes include: a front stage vane having no moisture recovery structure; a rear stage vane provided axially downstream of the front stage vane and having a moisture recovery structure; Including, and recovering drainage from the low-pressure turbine using the moisture recovery structure. The method for operating a steam turbine facility according to claim 1 or 2.

5. introducing steam from the high-pressure turbine to the low-pressure turbine through a pipe having a diameter of 50 inches or more and disposed between the high-pressure turbine and the low-pressure turbine. The method for operating a steam turbine facility according to claim 1 or 2.

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