Steam turbine

Abstract

A steam turbine is provided with: a stator blade; a rotor blade; a turbine chamber that accommodates the stator blades and the rotor blades; and a nanodroplet supply device for supplying steam containing the atomized droplets to the turbine chamber, and supplying nanodroplets to the main steam, the nanodroplets having a D10 particle diameter, which is an arithmetic average of the particle diameters of the droplets, of 0.5 [mu] m or less, and a mass ratio of 0.01-0.5% with respect to the main steam flowing into the turbine chamber.

Description

Technical Field

[0001] The invention relates to a steam turbine.

[0002] This application claims priority based on Japanese Patent Application No. 2022-171274 filed with the Japan Patent Office on October 26, 2022, and the contents of which are incorporated herein by reference. Background Art

[0003] If the steam in the turbine chamber becomes supercooled, the volume flow rate decreases, so the flow rate of the steam flowing into the blade row is significantly reduced from the design point, resulting in a significant reduction in performance. In addition, the latent heat released as the steam returns to the equilibrium state from the supercooled state is discharged to the outside of the system, so heat loss also occurs. In order to suppress this supersaturation loss (supercooling loss) in the steam turbine, the steam turbine disclosed in Patent Document 1 calculates the supersaturation zone distribution of the steam flow, and injects wet steam in the downstream direction of the steam flow based on the calculated supersaturation zone distribution. In this document, the average particle size of the water droplets contained in the wet steam is less than 1μm in terms of median particle size.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-181670 Summary of the invention

[0007] Technical issues to be solved by the invention

[0008] In order to achieve efficient operation of the steam turbine, it is necessary to further suppress supersaturation loss.

[0009] An object of the present invention is to provide a steam turbine capable of suppressing supersaturation loss without causing heat loss of working steam, thereby improving operating efficiency.

[0010] Means for solving technical problems

[0011] A steam turbine according to at least one embodiment of the present invention includes:

[0012] Stationary blades;

[0013] Moving blades;

[0014] a turbine chamber for accommodating the stationary blades and the moving blades; and

[0015] The nano water droplet supply device supplies steam containing atomized water droplets to the turbine chamber, and is used to supply the arithmetic mean particle size of the water droplets, i.e., D 10Nano water droplets having a particle size of 0.5 μm (500 nm) or less and a mass ratio of 0.01% to 0.5% with respect to the main steam flowing into the turbine chamber.

[0016] Here, in this specification, the nano water droplets refer to water droplets having a particle size of 0.5 μm or less.

[0017] Effects of the Invention

[0018] According to the present invention, it is possible to provide a steam turbine capable of improving operation efficiency by suppressing supersaturation loss without causing heat loss of working steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram showing a cross section of a steam turbine according to one embodiment.

[0020] Figure 2 This is a schematic diagram showing the results of obtaining the relationship between the water droplets supplied by the nano water droplet supplying device according to one embodiment and the total moisture loss through a simulation experiment.

[0021] Figure 3 This is a schematic diagram showing the results of obtaining the relationship between water droplets supplied by the nano water droplet supplying device according to one embodiment and supersaturation loss through a simulation experiment.

[0022] Figure 4 This is a graph showing the results of obtaining the relationship between the operating conditions of the steam turbine and the moisture loss according to one embodiment through a simulation experiment. DETAILED DESCRIPTION

[0023] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described as embodiments or shown in the accompanying drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0024] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" indicating relative or absolute configuration not only indicate such configuration in a strict sense, but also indicate a state of relative displacement at an angle or distance with a tolerance or a degree to which the same function can be achieved.

[0025] For example, expressions such as “identical”, “equal” and “homogeneous” that indicate that things are in the same state not only indicate the same state in a strict sense, but also indicate a state with tolerance or difference in the degree to which the same function can be obtained.

[0026] For example, expressions indicating shapes such as a quadrilateral and a cylinder not only indicate shapes such as a quadrilateral and a cylinder in a strict geometric sense, but also indicate shapes including concave and convex portions, chamfered portions, etc. within a range that can obtain the same effect.

[0027] On the other hand, the expression “having”, “including” or “having” a constituent element is not an exclusive expression that excludes the existence of other constituent elements.

[0028] In addition, the same symbols are attached to the same structures, and the description thereof may be omitted.

[0029] <Overview of Steam Turbine 1>

[0030] Figure 1 1 is a schematic diagram showing a cross section of a steam turbine 1 according to an embodiment of the present invention. The steam turbine 1 includes a rotor 2, a plurality of moving blades 6 fixed to the outer peripheral surface of the rotor 2, and an inner casing 3 that accommodates the rotor 2 and the plurality of moving blades 6. A turbine chamber 11 to which a plurality of stationary blades 4 are fixed is formed on the inner peripheral side of the inner casing 3. The turbine chamber 11 accommodates the rotor 2, the plurality of stationary blades 4, and the plurality of moving blades 6. Furthermore, a steam passage 10 is formed between the turbine chamber 11 and the rotor 2.

[0031] In this example, a plurality of stationary blades 4 arranged in the circumferential direction and a plurality of stationary blades 4 arranged in the circumferential direction are alternately arranged on the outer peripheral surface of the rotor 2 along the axial direction of the rotor 2. Furthermore, the plurality of stationary blades 4 and the plurality of moving blades 6 adjacent in the axial direction constitute a turbine stage 18. The plurality of moving blades 6 constituting the turbine stage 18 are located on the downstream side (at the bottom) of the plurality of stationary blades 4 in the flow direction of steam. Figure 1 on the right in the example).

[0032] In the steam turbine 1 having the above-described structure, working steam (also referred to as main steam or turbine steam) introduced as working fluid into the turbine chamber 11 from a chamber inlet (not shown) flows through the steam passage 10. The steam flow that is expanded and accelerated when passing through the stationary blades 4 in the steam passage 10 performs work on the moving blades 6, thereby driving the rotor 2 to rotate.

[0033] <Nano water droplet supply device 20 according to one embodiment>

[0034] refer to Figure 1, a nano-water droplet supply device 20 involved in one embodiment of the present invention is described. In the present application, tiny water droplets with a particle size of less than 0.5μm are defined as nano-water droplets. First, an overview of the nano-water droplet supply device 20 is described. At least a portion of the steam, i.e., the main steam, flowing into the turbine chamber 11 from the machine chamber inlet condenses while flowing through the steam channel 10. During its expansion process, the main steam will not begin to condense until a certain supersaturation is reached. It is known that the temperature of the steam at the beginning of condensation is temporarily lower than the saturation temperature, which is called supercooling. In order to suppress the supercooling phenomenon, the inventor conceived that it is sufficient to prepare an environment in the turbine chamber 11 in which the water molecules constituting the main steam grow and easily become droplets. Moreover, a nano-water droplet supply device 20 for intentionally generating an environment in the turbine chamber 11 that can suppress the supercooling phenomenon is conceived.

[0035] An example of the structure of the nano-water droplet supply device 20 configured to supply the fluid accompanying the water droplets generated by condensation from the supersaturated steam formed inside the nano-water droplet supply device 20, such as the accompanying steam or accompanying air containing a very small amount of water molecules compared to the main steam, to the turbine chamber 11 is described. The nano-water droplet supply device 20 includes a nano-water droplet supply source (not shown), a nano-water droplet conduit 22 connected to the nano-water droplet supply source, and a nano-water droplet spraying unit 24 for spraying the nano-water droplets guided by the nano-water droplet conduit 22 into the turbine chamber 11.

[0036] As an example, the nano water droplet supply source is configured to include a chamber for storing pure water and a vibrator sunk into the stored pure water, and the nano water droplets are generated from the surface of the pure water by the vibration of the vibrator. By adjusting the vibration frequency and output of the vibrator, the particle size of the nano water droplets and the flow rate of the nano water droplets can be controlled. Therefore, the nano water droplet supply source can supply a companion fluid containing micronized water droplets (for example, a companion steam containing water molecules).

[0037] The nano-water droplet conduit 22 includes one end (outside the figure) connected to the nano-water droplet supply source and the other end 22A arranged on the inner side of the hole 3A penetrating the inner shell 3. The nano-water droplet spraying section 24 is a pipe connected to the other end 22A of the nano-water droplet conduit 22, and extends in the radial direction of the rotor 2. The nano-water droplet spraying section 24 is arranged on the inlet side of any turbine stage 18 (the upstream side of the stationary blades 4 or the moving blades 6). In addition, the nano-water droplet spraying section 24 has a plurality of nozzles 25 for spraying the accompanying fluid containing nano-water droplets introduced from the nano-water droplet conduit 22, and the plurality of nozzles 25 are arranged at intervals in the radial direction of the rotor 2. Each nozzle 25 is directed toward the downstream side (at the downstream side) in the steam channel 10. Figure 1 on the right side in the example.

[0038] In the nano-water droplet supplying device 20 having the above structure, the accompanying fluid containing atomized water droplets supplied from the nano-water droplet supply source to the nano-water droplet spraying unit 24 via the nano-water droplet conduit 22 is sprayed into the turbine casing 11 from the plurality of nozzles 25 and mixed with the main steam.

[0039] The nano water droplet supplying device 20 of the present invention is configured to supply steam such that the water droplets D 10 The particle size is 0.5 μm or less, and the mass ratio of the water droplets supplied to the main steam is 0.01% or more and 0.5% or less. 10 The particle size is the particle size of the water droplets equivalent to the arithmetic mean of the particle sizes of the water droplets, D 10 The particle size of 0.5 μm or less means that the arithmetic mean of the particle sizes of water droplets is 0.5 μm or less.

[0040] Here, the particle size of water droplets is explained. It is known that inside the steam turbine 1, due to thermodynamic effects, the particle size of water droplets generated by uniform nucleation of steam in a supercooled state has a relatively uniform particle size. On the other hand, in spray injection, water droplets generated due to kinetic effects have a wide distribution of droplet diameters, and in the description of their average droplet diameter, various definition formulas are used, starting with the median diameter. However, if limited to the average droplet diameter inside the steam turbine 1, it is rarely defined by the median diameter in academics and engineering, and the average droplet diameter defined by the general mean diameter represented by the following formula (1) is usually used.

[0041] [Formula 1]

[0042]

[0043] Here, when p=1 and q=0, the above formula (1) naturally represents the arithmetic mean particle size. The nano-sized ultrafine water droplets generated by uniform nucleation have a relatively uniform particle size because the critical nucleus radius is dominated by the surface tension and Gibbs free energy of water under steam conditions. Therefore, when discussing the effect of reducing supersaturation loss caused by spraying nano-water droplets in this application, it can be judged that the effect of D 10 It is more convenient and reasonable to describe water droplets by particle size when understanding the average water droplet diameter. This application follows the definition of General mean diameter. If there is no special explanation, D 10 The particle size was set as the arithmetic mean diameter, and no labeling based on the median diameter was used.

[0044] According to the above structure, the steam flowing into the turbine chamber 11 from the chamber inlet, i.e., the main steam, can grow into water droplets with the nano water droplets supplied by the nano water droplet supply device 20 as nuclei. Thus, the overcooling phenomenon generated during the condensation of the main steam is suppressed, and as a result, the moisture loss can be reduced. Thus, the steam turbine 1 is realized in which the supersaturation loss is suppressed and the operation efficiency is improved.

[0045] exist Figure 1 The turbine chamber 11 shown in the example has a supersaturated region S. The supersaturated region S is a region (space) in the turbine chamber 11 where at least a portion of the main steam becomes supersaturated and begins to condense during operation of the steam turbine 1. Figure 1 In the example of the example, the main steam changes from a superheated state to a saturated state, and supersaturation increases as supercooling advances in the supersaturated zone S, generating condensation nuclei and growing toward water droplets. That is, in the process of the main steam passing through the supersaturated zone S, supercooling of the main steam occurs. The position where the supersaturated zone S is formed changes depending on the conditions of the steam turbine 1 in operation. For example, the higher the temperature of the main steam at the inlet of the machine room, the more the supersaturated zone S is formed toward the downstream side.

[0046] The nano-water droplet spraying unit 24 of the nano-water droplet supplying device 20 according to one embodiment of the present invention is arranged at a position further upstream than the supersaturated zone S formed in the turbine chamber 11, regardless of the conditions of the steam turbine 1 in operation. According to the above structure, the nano-water droplet supplying device 20 can spray nano-water droplets toward the supersaturated zone S where the supercooling phenomenon occurs, thereby promoting the condensation of the main steam in the supersaturated zone S, and effectively suppressing the supersaturation loss by releasing latent heat.

[0047] <Relationship between nano-water droplets supplied by the nano-water droplet supply device 20 and supersaturation loss>

[0048] Figure 3 This is a conceptual diagram of the relationship between the water droplets supplied by the nano water droplet supply device 20 and the supersaturation loss obtained through a simulation experiment. The conditions of the simulation experiment are as follows. The inlet pressure is set to 3.0ata, the inlet temperature is set to 130°C to 320°C, and the analysis is carried out under a wide range of temperature conditions from the condition of becoming dry steam to the condition of becoming wet steam at the turbine inlet. In addition, with the purpose of investigating how the details of the loss in the graded inlet humidity change, an analysis of sprinkling the turbine inlet humidity from 0% to 12% was implemented under the condition that the inlet became saturated. In addition, under the inlet humidity condition, an analysis of sprinkling the water droplet diameter from 0.1μm to 100μm was implemented, and the two parameters of the inlet water droplet diameter and humidity (the mass ratio of the water droplets supplied to the main steam) were analyzed in detail to determine the sensitivity of the two parameters to the details of the wet steam loss, especially to the amount of supersaturation loss.

[0049] Figure 3 The horizontal axis of the graph is the D of the water droplets supplied by the nano water droplet supply device 20. 10 The vertical axis represents the mass ratio of the water droplets supplied to the main steam. In the graph, the supersaturation loss shown in the densely shaded area is greater than the supersaturation loss shown in the area where the shaded area is not densely shaded. For example, the supersaturation loss of the area indicated by the shaded line HC is greater than the supersaturation loss of the area indicated by the shaded line HB. In addition, the supersaturation loss of the area indicated by the symbol HA is smaller than the supersaturation loss of the area indicated by the shaded line HB.

[0050] As from Figure 3 It can be seen that with D 10 The smaller the particle size, the smaller the supersaturation loss. This is because, when the total volume of the supplied water droplets is constant (the mass ratio of the water droplets supplied to the main steam is constant), the smaller the particle size of the water droplets, the more the number of water droplets increases and the larger the total surface area of ​​the water droplets. The larger the total surface area, the more opportunities there are for the nano water droplets supplied by the nano water droplet spraying unit 24 to contact the water molecules that constitute the main steam. Therefore, in the process of the nano water droplets contacting the main steam and growing by absorbing the water vapor, latent heat is released, thereby suppressing the supercooling of the main steam. In addition, in the simulation experiment, for example, when the mass ratio of the water droplets supplied to the main steam is 1%, when the D 10 The supersaturation loss of the lowest classification (the region indicated by the symbol HA) is confirmed in the region of the graph where the particle size is 0.5 μm (500 nm) or less. Also, in the region of the graph above, it is confirmed that the region indicated by the symbol HA accounts for a high proportion in the region of the graph where the mass ratio of the steam supplied to the main steam is 0.01% or more. In addition, it can be seen that Figure 3 As shown, in D 10 Under the condition that the particle size is constant, if the mass ratio of the nano water droplets supplied from the nano water droplet supply device 20 to the main steam becomes larger, the supersaturation loss becomes smaller. This is because even if the particle size is the same, if the mass ratio of the nano water droplets supplied to the main steam is high, the total surface area of ​​the water droplets (the surface area of ​​each water droplet × the number of water droplets) increases, so the mean free path of water molecules to reach the water droplets decreases, the release of latent heat based on condensation becomes active, and the supersaturation loss is reduced.

[0051] Therefore, it can be seen that if the D of the water droplets supplied by the nano water droplet supply device 20 is 10 When the particle size is 0.5 μm (500 nm) or less and the mass ratio of the water droplets supplied to the main steam is 0.01% (ie, 0.0001) or more, the supersaturation loss of the steam turbine 1 is effectively suppressed.

[0052] Generally, as shown in the Baumann rule, if the number of water droplets supplied increases, the moisture loss such as pump loss, braking loss, and acceleration loss increases compared to the effect of reducing the supersaturation loss caused by the increase in nano-water droplets, which leads to an increase in the moisture loss of the steam turbine 1. Therefore, the overall moisture loss increases and the performance cannot be improved. The present application is based on the following premise: according to the Baumann rule, based on the increase in various moisture losses, the turbine efficiency decreases by 1% relative to the additional water droplet mass flow rate of 1%.

[0053] Figure 2 This is a conceptual diagram of the relationship between the water droplets supplied by the nano-water droplet supply device 20 and the total moisture loss due to pump loss, braking loss, acceleration loss, etc. obtained through simulation experiments. Figure 3 The same is true for the supersaturation loss shown in the figure. In the graph, the moisture loss shown in the densely hatched area is greater than the moisture loss shown in the area where the hatching is not dense. For example, the moisture loss of the area represented by the hatching HC is greater than the moisture loss of the area represented by the hatching HB. And, the total moisture loss of the area represented by the symbol HA is smaller than the moisture loss of the area represented by the hatching HB.

[0054] When the total volume of the supplied water droplets is constant (the mass ratio of the water droplets supplied to the main steam is constant), the smaller the particle size, the lower the moisture loss. Figure 3 For example, if the mass flow rate of water droplets supplied from the nano-water droplet supply device 20 is 0.5% relative to the main steam mass flow rate, then D 10 The smaller the particle size, the more the effect of reducing moisture loss can be expected. However, for example, when observing in the range of particle size below 0.5μm, if the mass ratio of the water droplets supplied to the main steam exceeds 0.5%, there is a tendency for the moisture loss to increase instead. That is, in the case of excessive additional water droplets, the overall moisture loss based on the additional water droplets will exceed the benefit based on the reduction of supersaturation loss. If the water droplet diameter is the same, the greater the water droplet mass flow rate, the more the effect of reducing supersaturation loss can be expected, but the moisture loss other than the supersaturation loss will increase in proportion to the water droplet flow rate. Therefore, at an appropriate water droplet flow rate, the overall moisture loss becomes minimal. That is, the heat loss of the working steam (main steam) can be avoided.

[0055] Therefore, it can be seen that if one wants to reduce the supersaturation loss by supplying water droplets through the nano water droplet supplying device 20 while suppressing the increase in moisture loss caused by the supplied water droplets, the particle size of the nano water droplets can be made as small as possible, and can be set to less than 0.5μm. If the mass ratio of the supplied nano water droplets is further set to greater than 0.01% and less than 0.5%, the total moisture loss including that excluding the supersaturation loss can be suppressed.

[0056] <Relationship between supersaturation loss and moisture loss>

[0057] The inventor conducted an operation simulation experiment in which a steam turbine 1 was applied to a low-pressure turbine installed in a thermal power generation device. The operating conditions in the simulation experiment were that the steam flow rate supplied to the steam turbine 1 was 360 ton / h, and the humidity at the outlet of the turbine stage 18 located at the most downstream was 11%. Although detailed illustrations are omitted, according to the results of the simulation experiment, it can be seen that supersaturation loss accounts for about 60% of the wet steam loss of the steam turbine 1. Based on this result, it can also be confirmed that the operating efficiency of the steam turbine 1 is improved by suppressing supersaturation loss. In addition, in addition to supersaturation loss, wet steam loss also includes acceleration loss, capture loss, pump loss, braking loss and condensation loss. In this simulation experiment, the proportion of each loss is also determined, but the detailed description is omitted.

[0058] <Relationship between operating conditions and moisture loss>

[0059] Figure 4 This is a schematic diagram showing the result of determining the relationship between the state quantity humidity and moisture loss of the stage average under the operating conditions of the steam turbine 1 through simulation experiments. The state quantity humidity is the humidity of the static field determined by the state of the pressure or temperature of the saturated steam. In the actual steam turbine, there will be supercooling caused by adiabatic expansion or moisture loss caused by the wall surface, so the state quantity humidity will not be consistent with the actual humidity. However, in order to calculate the actual humidity, advanced simulation experiments based on computational fluid dynamics are required, and the state quantity humidity is currently used in the estimation of moisture loss in the design. For example, it is known that in a low-pressure steam turbine, if the steam pressure equivalent to about 3% (equivalent to the value of "J" in the graph) is not reached in the state quantity humidity meter, condensation will not actually occur. The horizontal axis of the graph represents the average value of the state quantity humidity at the inlet and outlet of the turbine stage 18 located downstream of the nano water droplet spraying section 24, and the vertical axis represents the moisture loss generated in the turbine stage 18.

[0060] In the "Comparative Example 1: Baumann's Rule" in the chart, if the classification average value of the state quantity humidity of any turbine stage 18 increases by 1%, the efficiency of the turbine stage 18 decreases by 1%. The decrease in classification efficiency caused by the increase in the state quantity humidity is called moisture loss. It can be seen that when the nano water droplet supply device 20 is not provided, the moisture loss shown in Comparative Example 1 will be approximately generated. The "Comparative Example 2: Dry Steam" in the chart shows the relationship between the state quantity humidity and moisture loss when dry steam is supplied from the nano water droplet spraying section 24. "Comparative Example 3: Water droplets (3.0μm)" indicates that D 10The relationship between the state humidity and the moisture loss when the water droplets have a particle size of 3.0 μm and a mass ratio of 0.1% to the main steam is drawn to be almost the same curve as that of dry steam. On the other hand, the "Comparative Example 4: Water Droplets (2.0 μm)" in the graph indicates that D 10 The relationship between the downstream state quantity humidity and moisture loss when the water droplets have a particle size of 2.0 μm and a mass ratio of 0.1% relative to the main steam. Regardless of whether water droplets are supplied, the main steam undergoes a phase change and increases in humidity during its own expansion process. The effect of reducing supersaturation loss generated in this process is almost not observed in water droplets larger than 2.0 μm (i.e., Comparative Examples 2 and 3). "Example 1: Nano water droplets (0.5 μm)" and "Example 2: Nano water droplets (0.1 μm)" in the graph respectively indicate that D was supplied at a mass ratio of 0.1% relative to the main steam. 10 The particle size of the water droplets becomes 0.5 μm (500 nm), D 10 Relationship between the state quantity humidity and moisture loss when the particle size is 0.1 μm (100 nm) nano water droplets. Comparison of Comparative Example 1 with Examples 1 and 2 shows that when nano water droplets are sprayed from the nano water droplet spraying unit 24 under the conditions of Examples 1 and 2, supersaturation loss is suppressed.

[0061] Furthermore, it can be seen from the comparison of "Comparative Example 1", "Comparative Example 2", "Comparative Example 3", "Comparative Example 4", "Example 1" and "Example 2" that in the range of humidity greater than 0% and less than 5% (not shown), it is confirmed that the moisture loss in "Example 1" and "Example 2" is relatively low, and the operation efficiency of the steam turbine 1 is the highest. Furthermore, as shown in "Comparative Example 3" and "Comparative Example 4", it is confirmed that if the particle size of the water droplets supplied from the nano water droplet spraying unit 24 is D 10 When the particle size is 2.0 μm or more, the supersaturation loss generated in the area where the state humidity is 5% or less is almost not reduced. This means that the smaller the water droplet, the higher the effect of reducing the supersaturation loss, and the larger the water droplet, the lower the effect of reducing the supersaturation loss.

[0062] From the above results, it can be seen that the particle size of the water droplets supplied by the nano-water droplet spraying unit 24 is D 10 When the particle size is 0.5 μm (500 nm) or less and the mass ratio of the water droplets to the main steam in the nano water droplet spraying unit 24 is 0.01% or more and 0.5% or less, supersaturation loss is suppressed and the operating efficiency of the steam turbine 1 is improved.

[0063] Summary

[0064] The contents described in the above-mentioned several embodiments can be understood, for example, as follows.

[0065] 1) A steam turbine 1 according to at least one embodiment of the present invention includes:

[0066] Stationary blade 4;

[0067] Moving blade 6;

[0068] A turbine chamber 11 for accommodating the stationary blades 4 and the moving blades 6; and

[0069] The nano water droplet supply device 20 supplies steam containing atomized water droplets to the turbine chamber 11 and is used to adjust the arithmetic mean of the particle size of the water droplets, i.e., D 10 The nano water droplets having a particle diameter of 0.5 μm or less and a mass ratio of 0.01% to 0.5% with respect to the main steam flowing into the turbine chamber are supplied to the main steam.

[0070] According to the structure of 1) above, the steam flowing into the turbine chamber 11 from the chamber inlet, i.e., the main steam (working steam), can undergo a phase change with the nano water droplets supplied by the nano water droplet supply device 20 as the core. As a result, the overcooling phenomenon caused by the condensation delay of the main steam is suppressed, and as a result, the moisture loss can be reduced. As a result, a steam turbine 1 that improves the operating efficiency by suppressing the supersaturation loss without causing the heat loss of the working steam can be realized. In addition, compared with the main steam mass flow rate, the accompanying steam mass flow rate for supplying water droplets is small to a negligible degree.

[0071] 2) In some embodiments, in the steam turbine 1 described in 1) above, the nano-water droplet supplying device 20 includes a nano-water droplet spraying unit 24 configured to spray the steam upstream of the supersaturated zone S generated in the turbine chamber 11 .

[0072] According to the structure of 2), the nano water droplet spraying unit 24 can spray nano water droplets toward the supersaturated region S where supercooling occurs, thereby promoting the release of latent heat caused by phase change of the main steam in the supersaturated region S, thereby effectively suppressing supersaturation loss.

[0073] Explanation of symbols

[0074] 1-steam turbine, 2-rotor, 3-inner casing, 3A-hole, 4-stationary blade, 6-moving blade, 10-steam channel, 11-turbine chamber, 18-turbine stage, 20-nano-water droplet supply device, 22-nano-water droplet conduit, 22A-other end, 24-nano-water droplet spraying part, 25-nozzle, HA, HB-hatched lines, R-dash-dot line, S-supersaturated zone.

Claims

1. A steam turbine comprising: Stationary blades; Moving blades; a turbine chamber for accommodating the stationary blades and the moving blades; and The nano water droplet supply device supplies steam containing micronized water droplets to the turbine chamber and is used to adjust the arithmetic mean of the particle size of the water droplets, i.e., D 10 Nano water droplets having a particle size of 0.5 μm or less and a mass ratio of 0.01% to 0.5% with respect to the main steam flowing into the turbine chamber are supplied to the main steam.

2. The steam turbine according to claim 1, wherein: The nano-water droplet supplying device includes a nano-water droplet spraying unit configured to spray the nano-water droplets upstream of a supersaturated zone generated in the turbine chamber.

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