TW202432945A - A steam turbine, a power plant and a small modular reactor comprising the turbine and a method of manufacturing or servicing of said turbine - Google Patents

Abstract

There is provided a reaction blade stage for a steam turbine, wherein the reaction blade stage has a ratio of a blade profile chord length of the fixed blades to a blade profile chord length of the moving blades equal to 1.5 – 2.5 and the reaction blade stage is located on and / or after the Wilson point of the steam turbine.

Description

Steam turbine, power plant and small modular reactor including turbine, and method for manufacturing or repairing turbine

The present invention relates to steam turbines, and more particularly, to steam turbines for use in power plants. The steam turbine includes a reaction blade stage that increases the efficiency of the steam turbine by addressing droplet behavior. Aspects of the present invention include the manufacture and overhaul of steam turbines, and power plants and small modular reactors including the steam turbines.

Achieving higher efficiency of steam turbines is a long-term and ongoing goal for all manufacturers, upgraders, and users of steam turbines. For applications in energy production, this is because higher efficiency of steam turbines triggers higher efficiency of power plants that include the steam turbines. Other applications of steam turbines also benefit from higher efficiency of steam turbines.

In particular, the effect of condensing steam and the presence of condensate (also known as wet steam) reduces efficiency. Furthermore, degradation of the steam turbine is attributed to the wet steam. Degradation over time also leads to reduced efficiency. It can be seen that there is a need to increase efficiency while reducing degradation of the steam turbine.

The efficiency of a steam turbine is reduced due to losses. There are various types of losses, for example, losses due to aerodynamic phenomena, including leakage losses due to water leaking onto the cover at the top or bottom of the steam turbine blades, blade profile losses, etc.

Document JP5936992B2 aims to increase efficiency by dealing with supersaturation and losses in a steam turbine. The supersaturation and losses are caused by droplet nucleation after the transition from supersaturated steam to saturated steam. This document cites chord length, but as will be explained in detail in the description, it does not change the chord length of the blade to achieve higher efficiency. Usually, the chord length is related to the distance between the root and the tip of the steam turbine blade. However, this document proposes to change the width at the center part of the steam turbine blade for the last three stages in a given section of the steam turbine. This modification suppresses supersaturation and losses and is therefore aimed at higher efficiency. Reducing the degradation of the steam turbine is not disclosed therein.

The degradation of different components of a steam turbine creates different problems for power plant owners and maintenance teams. It is well known that the stator or (commonly known) fixed blades are simpler and less time-consuming to overhaul when compared to the moving blades and the rotor. This stems from the way the fixed blades or the stator including the fixed blades are manufactured. At the same time, the manufacture or overhaul of a rotor with moving blades is therefore complicated due to how strongly the moving blades have to be connected to the rotor. Prolonged overhauls create problems for maintaining the continuity of energy production of the power plant, and there are benefits to maintaining the continuity of energy production of the power plant.

In view of this, it is an object to further increase the efficiency of a steam turbine while reducing the degradation of the steam turbine. Furthermore, there is a need for a steam turbine that is durable and which thus ensures a more sustainable energy production continuity of a power plant comprising the steam turbine. A further object is to have a steam turbine that is easy to service.

The present invention disclosed herein provides a further increase in efficiency and at the same time reduces the degradation of the steam turbine. In addition, the steam turbine according to the present invention is easy to repair. The principle of the present invention will be disclosed and explained below. It should be noted that any explanation is provided for a better understanding of the present invention and should not be construed as exhaustive or limiting the present invention.

As mentioned previously, the formation of water droplets of various sizes due to pressure and/or temperature changes can affect the efficiency of the steam turbine and contribute to steam turbine degradation.

The present invention achieves improved efficiency by specifically and dramatically modifying the deposition and size of water droplets within a steam turbine, which according to the present invention increases efficiency. In general, the present invention limits the interaction between the moving blades and the water droplets, so that less efficiency loss is observed on the moving blades. Due to the smaller losses, the efficiency of the steam turbine according to the present invention is higher when compared to a steam turbine that does not include the present invention. At the same time, the manner in which the interaction is modulated by the present invention reduces the degradation of the steam turbine, which results from the formation of droplets and films on the blades of the steam turbine.

According to a first aspect of the present invention, a steam turbine is provided, which includes at least one steam turbine section. The steam turbine section can be selected from a group including a high pressure section, a medium pressure section, and a low pressure section. The medium pressure section is also called an intermediate pressure section. The parameters of these sections are known in the field of steam turbines, and therefore no further details are required here. Embodiments of the present invention include any, some, or all combinations of high pressure sections, medium pressure sections, and low pressure sections in the steam turbine according to the present invention.

The at least one steam turbine section comprises a plurality of blade stages, and each blade stage comprises a row of fixed blades and an adjacent row of moving blades downstream of the row of fixed blades. The term "downstream" refers to the normal flow of steam, and thus the steam flows from the row of fixed blades to the row of moving blades. A person having ordinary knowledge in the art understands that in a steam turbine, the interaction between a row of fixed blades and an adjacent row of moving blades is responsible for inducing the rotation of the steam turbine and, in power plant applications, ultimately for energy production. It should be noted that the term "stage" (also referred to herein as "blade stage") also has an established meaning in the field of steam turbine engineering and therefore requires no further explanation. The same description applies to "fixed blades" and "moving blades".

At least one of the plurality of blade stages is located above or after the Wilson point of the steam turbine. The Wilson point is the main starting point of spontaneous condensation along the steam path within the steam turbine. In other words, above and after the location of the Wilson point in the steam turbine, we observe droplets (wet steam) forming within the steam turbine. The steam path includes the trajectory of individual water particles (droplets) as they travel through the turbine. The Wilson point is a term known to those of ordinary skill in the art, and the location of the Wilson point can be determined by using numerical methods or by measurements for a given design of the steam turbine. Furthermore, the Wilson point locations can be selected by a specific design of a steam turbine. The purpose of the locations above and/or after the Wilson point is that the present invention affects droplets and droplets are observed at locations above and after the Wilson point within the steam turbine. At the same time, nothing prohibits placing the at least one blade stage according to the present invention before the Wilson position. However, this configuration will not improve efficiency as explained herein.

The at least one blade stage is a reaction blade stage having a ratio of a fixed blade profile chord length to a moving blade profile chord length of from 1.5 to 2.5. The term "profile chord length" is well known and describes the length (or distance) between the leading edge and the trailing edge of an airfoil profile. It should be noted that the profile chord length can be selected individually for each blade. General practice is to have a single (same or similar) profile chord length for all blades (i.e. for fixed blades and for moving blades).

In known designs, droplets are deposited and form a film on both the stationary blades and the moving blades. The moving blades centrifuge the droplets (or the film created by the droplets) so that the droplets/film are removed from the flow (e.g. by deposition on a steam turbine shell). One explanation for the increased efficiency by the present invention is that the profile chord length according to the present invention together with the reaction technology etc. influences this deposition by reducing the droplet deposition on the stationary blades. The reduction of the film on the stationary blades results in a reduction of large droplets that break away from the stationary blades and subsequently impact and slow down the moving blades. Testing of the present invention has revealed that, although certain losses (e.g., aerodynamic force) are increased, blade braking losses are substantially reduced, and as a result, the efficiency of a steam turbine according to the present invention is higher than that of a steam turbine with a standard reaction blade layout. Another non-binding explanation for the observed efficiency increase is that the present invention has increased droplet deposition on the moving blades. These droplets form a film that is centrifuged to the housing and then removed from the flow path, resulting in lower wetting-induced losses in the downstream stages (due to lower droplet count, lower average droplet size, and/or lower wetting fraction).

Reaction, also called stage reaction or stage reaction, is a parameter known to those skilled in the art and used in the field of steam turbine engineering. It is related to the angle at which the steam leaves the fixed blades and the moving blades. Regardless of the way in which the stage reaction is defined, it defines a certain design of a blade stage and therefore describes the configuration of the blades in a steam turbine. It can be seen that those skilled in the art understand how to make a blade stage or a steam turbine with a given stage reaction.

Corrosion damage on the moving blades is reduced due to a smaller number of droplets falling from the stationary blades (due to reduced droplet deposition on the stationary blades). Steam turbine degradation results in service interruptions (due to the need for repairs), reduced energy production due to machine downtime, and reduced efficiency. It can be seen that the present invention allows for more sustainable energy production of power plants including steam turbines according to the present invention. Alternatively or additionally, the present invention extends the life of the steam turbine.

The highest efficiency of the steam turbine is achieved when all of the blade stages located above and after the Wilson point of the steam turbine are reaction blade stages, which have a ratio of a fixed blade profile chord length to a moving blade profile chord length of from 1.5 to 2.5.

For a chord length of 1.75 to 2.25, the best results were obtained with a medium reaction ranging from 40 to 45% to 55 to 60%.

The steam turbine section according to the present invention can be selected from a high pressure section, a medium pressure section, or a low pressure section. Since the present invention can be implemented in all types of sections of steam turbines, the present invention is universal.

In further embodiments, the steam turbine may include various numbers and types of sections. In one embodiment, the steam turbine may include two steam turbine sections, each having a high pressure section and a low pressure section. In another embodiment, the steam turbine includes three steam turbine sections: a high pressure section, a medium pressure section, and a low pressure section. In other words, all known configurations of steam turbines can be realized by the present invention. The versatility of the present invention is one of its advantages.

A combination of sections comprising the present invention may further increase the efficiency of the steam turbine. The efficiency increase may include synergistic effects. This is because the present invention affects the size of droplets travelling through all sections of the steam turbine. Alternatively or additionally, the protection against degradation is not a linear combination of sections according to the present invention, but a synergistic combination of the effects provided by the present invention.

A small modular reactor including a steam turbine according to an embodiment of the present invention is another aspect of the present invention. The application of the steam turbine according to the present invention in a small modular reactor (SMR) is relevant to the efficiency of such size-limited reactors. Moreover, the longer-lasting steam turbine according to the present invention will bring more sustainability to SMR energy production.

Another aspect of the present invention is related to a power plant. The power plant may include a fossil power plant, a combined cycle power plant, a renewable energy power plant, a waste-to-energy power plant, and a nuclear power plant. In addition, the steam turbine of the embodiment of the present invention may be implemented as an industrial steam turbine.

Steam turbines can be used as an upgrade to existing coal-fired power plants or as part of any ongoing effort to build new coal-fired power plants. Higher efficiency for coal-fired power plants means less coal is needed to produce the same amount of energy. Therefore, steam turbines according to embodiments of the present invention reduce the environmental impact of any coal-fired power plant.

The steam turbine according to the embodiment of the present invention can be used in combination with a gas turbine cycle, that is, in a combined cycle power plant. The combined cycle power plant has similar benefits as the thermal power plant.

The renewable energy power plant may include a steam turbine according to the present invention. As a result, the power plant can achieve the desired efficiency to meet its power production expectations. The higher efficiency of the renewable energy power plant will allow it to maximize its use, for example, when the sun is running.

Embodiments of the present invention will allow nuclear power plants to maximize the use of their nuclear sources. It should be noted that the present invention can be used with the world's largest steam turbines (such as half-speed units), such as implementing the Arabelle product line steam turbines. Increasing the efficiency of an existing fleet of nuclear power plants is beneficial to any power plant owner because it allows for higher energy production without the need to build additional nuclear power plants or without the need to significantly modify nuclear power plants. This allows for a significant reduction in the time required to produce more energy from a nuclear power plant, because the typical way to increase power production involves building a new power plant or adding a new unit to an existing one, and will take years to complete.

Power plants of all types would benefit from maintaining steady energy production provided by a steam turbine according to embodiments of the present invention.

Another aspect of the invention relates to the use of a steam turbine of an embodiment of the invention for increasing the power production of a power plant. The power plant may be any known or newly established power plant. Additionally, the power plant may be a thermal power plant, a cycle power plant, a renewable energy power plant, or a nuclear power plant. It should be noted that increasing the efficiency by embodiments of the invention, even to levels of several percentages (for the most efficient embodiments of the invention, from 0.1%, 0.2%, 0.3%, 0.4%, up to 0.5%, and including 0.5% or more), translates into a significant increase in the power production of the power plant. A typical increase would be 0.5%, with higher values expected for higher steam humidification. For any power plant, an increase in electricity generation of a small or even a few percentage points translates into large benefits. These benefits may include better use of resources (e.g., coal, nuclear power, solar power), more stable energy generation when demand for electricity increases, or less waste generation by the power plant.

Another aspect of the invention includes a method of manufacturing or overhauling a steam turbine. In an embodiment, the steam turbine includes a plurality of blade stages, wherein the at least one steam turbine section includes at least one blade stage, each blade stage including a row of fixed blades and an adjacent row of moving blades downstream of the row of fixed blades. In an embodiment, the manufacturing method includes providing a ratio of a fixed blade profile chord length to a moving blade profile chord length of from 1.5 to 2.5 for at least one blade stage of the plurality of blade stages located above or after a Wilson point of the steam turbine, and wherein the at least one blade stage is a reaction blade stage. An embodiment of the method includes providing a ratio of a fixed blade profile chord length to a moving blade profile chord length of from 1.5 to 2.5 for all blade stages of the plurality of blade stages located above and after the Wilson point of the steam turbine, and wherein all of the blade stages are reaction blade stages.

While manufacturing is concerned with providing new steam turbines, overhaul is concerned with improving or maintaining existing steam turbines. The present invention can be easily implemented as an overhaul method to an existing steam turbine by replacing only the fixed blades. This benefit arises from the overhaul difference between the fixed blades and the moving blades. It is well known that due to the tensions to which the rotor blades are subjected during operation, the moving blades must be securely connected to the rotor. At the same time, the fixed blades can be replaced together with the stator and the casing, that is, there is no need to disconnect the fixed blades from the casing or the stator. In addition, the connection between the fixed blades and the stator or the casing does not have the same strength when compared to the connection used for the moving blades. It can be seen that both the installation and the replacement of the rotor blades are technically challenging and may even result in damage to the rotor and/or the moving blades. This leads to an increase in waste materials and the need to manufacture new components. The technical challenges of overhauling the moving blades are transferred to the time required to overhaul the rotor blades and its impact on downtime. For power plants that include a steam turbine under overhaul, the downtime results in a shortfall in energy production. Therefore, the longer the overhaul of the steam turbine takes, the longer the downtime lasts. When compared to overhauls that involve replacing the moving blades or replacing both the moving blades and the fixed blades, the present invention allows for a faster increase in efficiency by affecting only the fixed blades.

It will be understood that unless otherwise specified, the use of the terms "first," "second," and the like in this patent specification are intended merely to help distinguish similar features and are not intended to indicate the relative importance of one feature over another.

Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives set forth in this disclosure, as well as the claims and/or the following descriptions and drawings (and specifically the individual features thereof) may be employed independently or in any combination. That is, all embodiments and all features of any embodiment may be combined in any manner and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claims or to file any new claims accordingly, including amending any originally filed claims to be attached to and/or merged with any features of any other claims that were not originally claimed in that manner.

The following non-limiting embodiments of the present invention are described with reference to a reaction blade stage in a steam turbine.

In the conventional reaction blade stage as shown in Fig. 1, the blades of the stator 20 and the rotor 22 have similar blade chord lengths for reasons of cost and performance ratio. As a result, the vapor droplets are deposited uniformly on the fixed blades 20 and the moving blades 22, which affects the wettability loss and efficiency of the reaction blade stage.

A steam turbine according to one embodiment of the present invention is shown in FIG. 2 . In this embodiment, the steam turbine includes a plurality of reaction blade stages. Each reaction blade stage includes a row of fixed blades and an adjacent row of moving blades downstream of the row of fixed blades. The row of fixed blades may be included in a stator or in a housing for a steam turbine. The adjacent row of moving blades is included in a rotor. In use, steam flows through the rows of fixed blades 30 and the rows of moving blades 32 so as to cause each reaction blade stage to convert thermal energy from the steam into mechanical energy via a rotating output shaft of the steam turbine.

The ratio of the fixed blade profile chord length s _{fixed blade} to the moving blade profile chord length s _{moving blade} R _chord is defined by Equation 1. (1)

For example, the blade profile chord length of the fixed blade s _{fixed blade} and the blade profile chord length of the moving blade s _{moving blade} may be in the range of 20 mm and 400 mm, the blade stagger angle of the fixed blade and the moving blade may be in the range of 45° and 65°, and the aspect ratio of the fixed _{blade and the rotor blade may be in the range of 1 and 7. The aspect ratio of the fixed blade is the ratio of the blade height of the fixed blade h fixed blade} to the blade profile chord length s _{fixed blade} . The aspect ratio of the rotor is the ratio of the blade height of the rotor h _{moving blade} to the blade profile chord length s _{moving blade} .

In use, the moving blades 32 of the rotor tend to centrifuge the water film resulting from the deposition of steam droplets on the moving blades 32, and this film is removed at the shell of the steam turbine. Large water droplets transferred from the fixed blades 30 to the moving blades 32 have an adverse effect on the rotation of the moving blades 32 by increasing the braking losses in the rotor.

The inventors have found that a steam turbine with reduced losses is achieved by setting the value of R _chord for the reaction blade stages in the range of 1.5 and 2.5. Preferably, this value of R _chord applies to all reaction blade stages.

In an embodiment, by increasing the blade profile chord length s _{fixed blade} of the fixed blade, the deposition of steam droplets on the fixed blade 30 can be reduced, which has the effect of reducing the amount of large water droplets that drip from the trailing edge 30 of the fixed blade to the leading edge 32 of the moving blade, and thus reducing the braking losses in the rotor due to the impact of the droplets on the moving blade 32. In addition, reducing the droplet deposition reduces the surface degradation of the moving blades 30, 32. Moreover, by reducing the blade profile chord length s _{moving blade} of the rotor, the secondary flow losses in the rotor can be reduced.

FIG3 shows droplet deposition in (a) a conventional reaction blade stage and (b) a reaction blade stage of the present invention. The flow paths of the droplets are graphically shown as flow lines, each of which extends through a number of spaced circles. It can be seen from the flow lines in FIG3 that the amount of droplet deposition on the stationary blades of the reaction blade stage of the present invention is reduced compared to the amount of droplet deposition on the stationary blades of the conventional reaction blade stage.

Figures 4 and 5 compare the results obtained for six blade stages of a steam turbine.

FIG. 4 compares the relative amount of droplet deposition on the fixed blades of the stator for a known reaction blade stage and a reaction blade stage of the present invention. The left hand side of the graph compares the amount 34 of small droplets (e.g., 2* ^10-6 m in size) deposited for the known reaction blade stage versus the amount 36 of small droplets deposited for the reaction blade stage of the present invention. The values vary from about 20% to 15%. The right hand side of the graph compares the amount 38 of large droplets (e.g., 1* ^10-5 m in size) deposited for the known reaction blade stage versus the amount 40 of large droplets deposited for the reaction blade stage of the present invention. The values vary from about 97% to 70%. In an embodiment, the average size of the large droplets is approximately one order of magnitude larger than the average size of the small droplets.

As can be seen from FIG. 4 , a 25% reduction in droplet deposition on the fixed blades was observed for the reaction blade stage of the present invention for both small and large droplets, compared to the known reaction blade stage.

FIG. 5 compares the relative amount of droplet deposition on the moving blades of the rotor for a known reaction blade stage and the reaction blade stage of the present invention. The sizes of the small droplets and large droplets are the same as those used in the embodiment of FIG. 4 , respectively. The left hand side of the graph compares the amount of small droplet deposition 42 for the known reaction blade stage versus the amount of small droplet deposition 44 for the reaction blade stage of the present invention. The values vary from about 9% to 13%. The right hand side of the graph compares the amount of large droplet deposition 46 for the known reaction blade stage versus the amount of large droplet deposition 48 for the reaction blade stage of the present invention. The values vary from about 40% to 53%.

As can be seen from Figure 5, an increase in small and large droplet deposition on the moving blades is observed for the reaction blade stage of the present invention compared to the known reaction blade stage. This increase in deposition increases the amount of film that is centrifuged to the outer flow path region where it can be removed by the water extraction feature. This reduces the steam moisture content and reduces losses in the downstream stages, further increasing turbine efficiency.

FIG6 compares the aerodynamic losses, other lubrication losses, and brake losses of a series of conventional reaction turbine blade stages A1, A2, A3 and a series of reaction turbine blade stages B1, B2, B3 of the present invention. In the graph of FIG6 , the aerodynamic losses, other lubrication losses, and brake losses are shown in order from left to right for each reaction turbine blade stage. Although the air dynamic losses for the reaction blade stages B1, B2, B3 of the invention are slightly increased compared to the air dynamic losses for the known reaction blade stages A1, A2, A3, the braking losses for the reaction blade stages B1, B2, B3 of the invention are significantly reduced compared to the braking losses for the known reaction blade stages A1, A2, A3. In other words, the increase in the magnitude of the air dynamic losses is much smaller than the decrease in the magnitude of the braking losses, resulting in an overall increase in efficiency.

The listing or discussion of an apparently previously published document or apparently previously published information in this specification should not necessarily be taken as an admission that the document or information is part of the state of the art or is common general knowledge.

Unless the context indicates otherwise, preferences and options for a given aspect, feature, or parameter of the invention should be considered disclosed in combination with any and all preferences and options for all other aspects, features, and parameters of the invention.

The above description of the embodiments of the present disclosure (including those described in the Abstract) is not intended to be comprehensive or to limit the disclosed embodiments to those precisely disclosed. Specific embodiments and examples are described herein for illustrative purposes, and modifications are possible as one of ordinary skill in the art will appreciate. Specifically, components, assemblies, steps, and aspects from different embodiments may be combined in other embodiments or adapted for use in other embodiments, even if not described in the present disclosure or depicted in the drawings. It should be understood that other similar embodiments may be used, or that modifications and additions may be made to the described embodiments for performing the same, similar, alternative, or replacement functions of the disclosed subject matter without departing therefrom. References to "one embodiment" of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

The terms "including" and "in which" are the plain English equivalents of the terms "comprising" and "wherein," respectively. The terms "first," "second," "third," etc. are used merely as labels and are not intended to impose numerical or positional requirements on such objects. The term "about" is intended to describe a tolerance that can be reasonably achieved for engineering purposes.

20: stator; fixed blades 22: rotor; moving blades 30: fixed blades; fixed blade trailing edge 32: moving blades; moving blade leading edge 34: quantity 36: quantity 38: quantity 40: quantity 42: quantity 44: quantity 46: quantity 48: quantity A1, A2, A3: reaction turbine blade stage; reaction blade stage B1, B2, B3: reaction blade stage

Embodiments of the present invention will now be described with reference to the accompanying drawings by way of non-limiting examples, including preferred embodiments, wherein: [FIG. 1] shows a conventional reaction blade stage of a steam turbine; [FIG. 2] shows a reaction blade stage of a steam turbine according to an embodiment of the present invention; [FIG. 3(a)] shows the droplet distribution and size of the blade stage of a general steam turbine, and [FIG. 3(b)] shows a reaction blade stage of a steam turbine according to an embodiment of the present invention. [FIG. 4] shows a comparison of droplet deposition on fixed blades between a general design of a steam turbine and a steam turbine according to the present invention, and [FIG. 5] shows a comparison of droplet deposition on moving blades between a general design of a steam turbine and a steam turbine according to the present invention; and [FIG. 6] shows a comparison of losses between a general design of a steam turbine and a steam turbine according to an embodiment of the present invention.

Claims (15)

A steam turbine comprises at least one steam turbine section, wherein the at least one steam turbine section includes a plurality of blade stages, each blade stage comprises a row of fixed blades and an adjacent row of moving blades downstream of the row of fixed blades, and wherein at least one blade stage among the plurality of blade stages has a ratio of a fixed blade profile chord length to a moving blade profile chord length of from 1.5 to 2.5, and is a reaction blade stage located above or after the Wilson point of the steam turbine. A steam turbine as claimed in claim 1, wherein all blade stages located above and after the Wilson point of the steam turbine are reaction blade stages, having a ratio of a fixed blade profile chord length to a moving blade profile chord length ranging from 1.5 to 2.5. A steam turbine as claimed in any one of claims 1 to 2, wherein the ratio of the chord length of a fixed blade profile to the chord length of a moving blade profile is from 1.75 to 2.25. A steam turbine as claimed in any one of claims 1 to 3, wherein the stage reaction for said reaction blade stages is from 40% to 60%. A steam turbine as claimed in claim 4, wherein the reaction of the stage is from 45% to 55%. A steam turbine as in any one of claims 1 to 5, wherein the steam turbine section is selected from a group consisting of a high pressure section, a medium pressure section, and a low pressure section. A steam turbine as claimed in any one of claims 1 to 6, wherein the steam turbine comprises two steam turbine sections, one of which is a high pressure section and one of which is a low pressure section, or wherein the steam turbine comprises three steam turbine sections, one of which is a high pressure section, one of which is a medium pressure section, and one of which is a low pressure section. A small modular reactor, wherein the small modular reactor includes a steam turbine as described in any one of claims 1 to 7. A power plant selected from a group consisting of a thermal power plant, a cycle power plant, a renewable energy power plant, a waste-to-energy power plant, and a nuclear power plant, wherein the power plant includes a steam turbine as described in any one of claims 1 to 7. A use of a steam turbine as claimed in any one of claims 1 to 7 for increasing the power production of a power plant, or for increasing the efficiency of an industrial process, or for ensuring sustainable energy production in a power plant. A method for manufacturing or overhauling a steam turbine, wherein the steam turbine comprises at least one steam turbine section, wherein the at least one steam turbine section comprises at least one blade stage, each blade stage comprising a row of fixed blades and an adjacent row of moving blades downstream of the row of fixed blades, the method comprising providing at least one blade stage of the plurality of blade stages located above or after the Wilson point of the steam turbine with a rotation speed of from 1.5 to 2.5 A ratio of a fixed blade profile chord length to a moving blade profile chord length, and wherein the at least one blade stage is a reaction blade stage; or the row of fixed blades of at least one blade stage located above or after the Wilson point of the steam turbine is configured to obtain a ratio of a fixed blade profile chord length to a moving blade profile chord length of from 1.5 to 2.5, and the at least one blade stage is a reaction blade stage. A method for manufacturing or overhauling a steam turbine as claimed in claim 11, wherein the manufacturing method includes providing a ratio of a fixed blade profile chord length to a moving blade profile chord length ranging from 1.5 to 2.5 for all blade stages among the plurality of blade stages located above and after the Wilson point of the steam turbine, and wherein all of the blade stages are reaction blade stages, or wherein the overhaul method includes configuring the rows of fixed blades of all blade stages among the plurality of blade stages located above or after the Wilson point of the steam turbine to obtain a ratio of a fixed blade profile chord length to a moving blade profile chord length ranging from 1.5 to 2.5, and making the blade stages reaction blade stages. A method for manufacturing or overhauling a steam turbine as claimed in claim 12, wherein the ratio of the chord length of a fixed blade profile to the chord length of a moving blade profile is from 1.75 to 2.25. A method of manufacturing or overhauling a steam turbine as claimed in any one of claims 11 to 13, wherein the stage reaction for said reaction blade stages is from 40% to 60%. A method for manufacturing or overhauling a steam turbine as claimed in claim 14, wherein the stage reaction is from 45% to 55%.