CN117027962A - Steam turbine and stationary blade thereof - Google Patents

Abstract

The application provides a steam turbine and a stator blade thereof, wherein the back arc surface of the stator blade provided by the application is provided with a step surface, so that a water film can be broken and large liquid drops which can directly enter a throat area along with steam can be formed, the large liquid drops are torn and crushed in the throat area to be small liquid drops which can be the same as or similar to a steam airflow flowing path, the erosion of the liquid drops to the air inlet edge of a moving blade is reduced, the erosion and mechanical impact of the moving blade are further slowed down, and the service performance and service life of the moving blade are greatly improved.

Description

Steam turbine and stationary blade thereof

Technical Field

The application relates to the technical field of power generation equipment, in particular to a steam turbine and stationary blades thereof.

Background

The power generation system comprises a boiler, a steam turbine, a generator and other components, wherein the boiler heats water to form steam by using heat energy of fuel or other energy sources, the steam enters the steam turbine along a steam pipeline system to push blades inside the steam turbine to rotate, the blades are fixedly connected with a rotating shaft, the blades rotate to drive the rotating shaft to rotate, and the end part of the rotating shaft extending out of the steam turbine is further connected with a rotor of the generator to drive the generator to generate power.

The steam turbine includes the casing, and the casing is inside to be provided with a plurality of grades of movable blades and stator blade, and a stator blade interval arrangement, and a stator blade and a rotor blade constitute one-level, and wherein the rotor blade is fixed in the pivot of steam turbine, and the stator blade is fixed in the casing of steam turbine, and the stator blade mainly plays the effect of leading and accelerating steam. Steam firstly enters the first-stage stationary blades from the steam valve, the steam is guided to the first-stage moving blades and pushes the first-stage moving blades to rotate, and then the rotating shaft is driven to rotate, and the working principle of the stationary blades and the moving blades in other stages is the same as that of the first stage.

The performance of moving blades is a major concern in the art, which directly affects the operating efficiency of the turbine.

Disclosure of Invention

The application aims to provide a stator blade and a steam turbine, which can reduce erosion and mechanical damage of the moving blade of the steam turbine.

The application provides a stator blade, which comprises an inner arc surface, a back arc surface, a steam inlet side and a steam outlet side, wherein a part of the back arc surface is sunken to form a sunken part, the back arc surface comprises a first surface area and a second surface area which are respectively arranged at two sides of the sunken part from the steam inlet side to the steam outlet side, the sunken part comprises a step surface and a transition surface, the step surface faces the steam outlet side, and the root of the step surface is connected with the second surface area through the transition surface;

the side of the step surface far away from the root part of the step surface is connected with the first surface area, and a structure formed at the joint position of the step surface and the first surface area can separate a water film into liquid drops which enter the throat area of the static blade along with steam.

When the water film on the back arc surface of the stator blade is accumulated to a certain thickness, the water film can flow and accumulate along the direction of the steam outlet side by the steam flow, after the water film reaches the position of the step surface, the continuous flow of the water film at the position is interrupted and gathered on the edge of the step surface due to abrupt change of the shape of the back arc surface, and the gathered water film leaves the edge and forms dispersed large liquid drops under the steam scouring. The liquid drops are peeled off from the step surface and the first surface area under the drive of the steam airflow and then directly enter the throat area between the two stationary blades.

The steam is continuously accelerated in the process of passing through the throat area, and the accelerated steam flow tears and breaks large liquid drops carried by the steam into small liquid drops with the diameter smaller than 0.1mm and has good following performance, and the small liquid drops are accelerated to the same or similar speed as the steam flow. The regenerated water film between the vane back arc surface downstream of the vane throat region and the steam outlet edge 3 has no capability of stripping into large drops with strong erosion. When the small liquid drops reach the inlets of the moving blade channels, the small liquid drops enter the moving blade steam channels at the same steam inlet angle as the steam flow, so that the scouring probability of the small liquid drops to the steam inlet edges of the moving blades is reduced as much as possible. Meanwhile, the momentum of the small liquid drops is smaller, so that the erosion capacity of the moving blade is reduced to the extent of 1/5-1/6 of that of the liquid drops with the diameter of 1 mm.

From the above description, the back arc surface of the stator blade provided by the application is provided with the step surface, so that a water film can be broken and large liquid drops which can directly enter the throat area along with steam can be formed, the large liquid drops are torn and crushed in the throat area to be small liquid drops which can be the same as or similar to the flow path of the steam airflow, the erosion of the liquid drops to the air inlet edge of the moving blade is reduced, the erosion and mechanical impact of the moving blade are further slowed down, and the service performance and service life of the moving blade are greatly improved.

Optionally, the junction between the first surface region and the step surface is a sharp edge structure.

Optionally, a length of the stationary blade between the steam inlet side forehead line and the steam outlet side forehead line is defined as an axial length, the step surface and the second surface area have a phase connection line, and a ratio of a distance between the phase connection line and the steam inlet side forehead line to the axial length ranges from 0.65 to 0.75.

Optionally, the ratio of the length of the step surface to the length of the stator blade along the length direction of the steam outlet edge is in the range of 1/3 to 1/2.

Optionally, the concave portion extends outward to an outer end surface of the stationary blade near the diaphragm outer ring.

Optionally, a tangent line of the back arc surface at the junction line position line is perpendicular to the step surface.

Optionally, the range of an included angle between the step surface and the inlet side forehead line of the stator blade is: 25-42 deg.

Optionally, the depth of the recess is in the range of 1.5mm to 4mm, so that the large droplets at the step surface position will be carried by the steam flow into the throat region formed adjacent the stator vanes.

Optionally, the step surface is located at a position with the maximum thickness value of the water film formed by the stator blade, and the joint position of the transition surface and the second surface area is located at a position with the maximum change of the air flow speed.

In addition, the application also provides a steam turbine comprising the stator blade.

The turbine according to the present application includes the stator blade according to any one of the above, and therefore has the above-described technical effects of the stator blade.

Drawings

FIG. 1 is a schematic view of a stator vane according to an embodiment of the present application;

FIG. 2 is a schematic illustration of the relative positions of two stationary blades of FIG. 1 in a steam turbine;

FIG. 3 is a schematic view of a diaphragm including the stator blades of FIG. 1 in accordance with an embodiment of the present application;

FIG. 4 is a graph S1 showing the erosion rate of the rotor blade, showing the dimensionless values of the step surface position on the erosion of the rotor blade in one embodiment of the present application; curve S2 represents the modal diameter; curve S3 represents the drop impact velocity.

Wherein, in fig. 1 to 4:

1-1 a separator outer ring;

1-2 stationary blades;

1-3 separator inner rings; 1, a back arc surface; 2, an intrados surface; 3, steam edge; 4, steam inlet edge; a 5 throat region; 6 throat; 7, a concave part; 71 step surfaces; 72 transition surface; b, stator blade axial length; e, steam inlet side forehead line; f, discharging a forehead line; 712 root; h, depth of the step surface; 711 edge; and an included angle between the step a and the frontal line of the steam inlet side of the blade.

Detailed Description

Aiming at the technical problem that the working process of the moving blade is corroded in the background art, the application is researched and found: in the low-pressure through flow of the steam turbine, as the steam expands to cross a saturation line, a plurality of stages after the through flow work in a two-phase mixed substance consisting of steam and tiny liquid drops, most of the small liquid drops are deposited on the surfaces of static blades to form a water film, and the water film is continuously thickened in the working process of the steam turbine. When the water film reaches a certain thickness, stripping is carried out near the steam outlet edge of the static blade under the action of steam dragging, so that liquid drops with larger diameters are formed. The velocity of the liquid drops with larger diameters is much smaller than that of free steam, and the steam following mobility is poor, so that the liquid drops can strike the steam inlet side of the moving blade with a larger negative attack angle, and the erosion damage of the moving blade is caused.

At present, an anti-corrosion layer is mainly added on the surface of the moving blade, so that the technical problem is solved. However, the effect achieved by this method is limited, and the erosion phenomenon of the rotor blade is still serious.

The present application has been made by a great deal of research and experiments based on the findings described above, and by improving the structure of the stator blades, a technical effect of alleviating erosion of the rotor blades is achieved, and a steam turbine including the stator blades having the above technical effect is provided on the basis of the above.

Features and exemplary embodiments of various aspects of the present application will be described in detail below, and in order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described in further detail below with reference to the accompanying drawings and the detailed embodiments.

Referring to fig. 1 to 4, fig. 1 is a schematic structural view of a stator vane according to an embodiment of the present application; FIG. 2 is a schematic illustration of the relative positions of two stationary blades of FIG. 1 in a steam turbine;

FIG. 3 is a schematic view of a diaphragm including the stator blades of FIG. 1 in accordance with an embodiment of the present application; FIG. 4 is a graph S1 showing the erosion rate of the rotor blade, showing the dimensionless values of the erosion effect of the recess locations on the rotor blade in one embodiment of the present application; curve S2 represents the modal diameter; curve S3 represents the drop impact velocity.

In an embodiment of the application, the power generation system comprises a boiler, a steam turbine and a generator.

The boiler produces steam through burning fuel, and steam gets into inside the steam turbine through the steam line, still is provided with parts such as superheater, reheater and control valve on the general steam line, and superheater and reheater mainly are used for carrying out heat treatment to the steam that the boiler flows out. The control valve is mainly used for controlling the steam flow of the corresponding pipeline. The locations of the superheater, reheater and control valves are not described in detail herein, and reference is made to the prior art.

The steam turbine has the casing, the inside pivot that has of casing, be fixed with a plurality of moving blades and the stator blade of interval arrangement in the pivot, a moving blade and stator blade form one-level, still be provided with steam inlet on the casing, the steam that the boiler produced gets into inside the casing from steam inlet after steam piping system, in the in-process of flowing through each stage blade, steam drive moving blade rotates, the moving blade drives the pivot and rotates, because of the rotor of pivot and generator links to each other, so the rotor rotates along with it, and then the generator electricity generation.

The specific structure of the components such as the steam turbine, the boiler and the generator in the application can refer to the prior art, and the description is omitted herein.

In the embodiment of the application, the stator blade comprises an inner arc surface 2, a back arc surface 1, a steam inlet edge 4 and a steam outlet edge 3. The inner arc surface 2 and the back arc surface 1 enclose an arc surface of the stator blade, the inner arc surface 2 is a surface facing steam and is a concave surface, and the back arc surface 1 is a convex surface arranged on one side of the stator blade, which is away from the inner arc surface 2. After the stator blades are installed on the steam turbine, a steam circulation channel is formed between the back arc surface 1 of the previous stator blade and the inner arc surface 2 of the subsequent stator blade, and a convergent channel region of the steam circulation channel is called a throat region 5, and a minimum width position in the throat region 5 is called a throat 6.

The inner arc surface 2 and the back arc surface 1 are both streamline surfaces, and the specific line structure of the inner arc surface and the back arc surface can be determined according to specific products, and are not specifically described herein.

In the embodiment of the present application, the partial area of the back arc surface 1 is recessed to form the recess 7, and the back arc surface 1 includes the first surface area 11 and the second surface area 12 separated at two sides of the recess 7 from the steam inlet edge 4 to the steam outlet edge 3, that is, the back arc surface 1 is broken at the position of the recess 7, and the back arc surface 1 is not a continuous surface.

In the embodiment of the application, the concave part 7 comprises the step surface 71 and the transition surface 72, the step surface 71 faces the steam outlet edge 3, the root 712 of the step surface 71 is connected with the second surface area 12 through the transition surface 72, and the design of the transition surface 72 needs to ensure that steam on the surface of the stator blade is smooth and free from disorder. The side of the step surface 71 remote from its root 712 is connected to the first surface area 11 and the formation of the junction of the step surface 71 with the first surface area 11 is such that it separates the water film into droplets which can enter the throat area with the steam, i.e. the water film is broken at the junction of the step surface 71 with the first surface area, the droplets formed do not flow through the transition surface 72 but directly into the throat area with the steam flow. Typically the diameter of the droplets formed by the step surface 71 and the first surface region 11 is less than the depth h of the step surface 71 so that the droplets are not caught by the surface downstream of the step surface 71 and avoid re-formation of a water film, which droplets will be carried by the steam flow into the throat region of the vane.

When the water film on the back arc surface 1 of the stator blade is accumulated to a certain thickness, the water film can flow and accumulate in the direction of the steam outlet edge 3 by the steam flow, after the water film reaches the position of the step surface 71, the continuous flow of the water film at the position is broken and accumulated on the edge 711 of the step surface 71 due to the abrupt change of the shape of the back arc surface 1, and the accumulated water film leaves the edge 711 under the steam scouring to form dispersed large liquid drops. The droplets are stripped from the step surface 71 and the first surface region 11 by the steam flow and then directly enter the throat region 5 between the two stationary blades.

The steam is continuously accelerated during its passage through the throat region 5, and the accelerated steam stream breaks up the large droplets carried by it into well-followed droplets having a diameter of less than 0.1mm and accelerates them to the same or similar velocity as the steam stream. The regenerated water film between the vane back-arc surface 1 downstream of the vane throat region 5 and the trailing edge 3 has not been able to be stripped into large droplets of relatively high erosion. When the droplets reach the inlets of the moving blade channels, the droplets enter the moving blade channels at the same steam inlet angle as the steam flow, so that the scouring probability of the droplets to the steam inlet edges 4 of the moving blades is reduced as much as possible. Meanwhile, the momentum of the small liquid drops is smaller, so that the erosion capacity of the moving blade is reduced to the extent of 1/5-1/6 of that of the liquid drops with the diameter of 1 mm.

As is clear from the above description, the back arc surface 1 of the stator blade provided by the application has the step surface 71, which can break the water film and form large liquid drops which can directly enter the throat region 5 along with steam, and the large liquid drops are torn and crushed in the throat region 5 into small liquid drops which can be the same as or similar to the flow path of the steam flow, so that the erosion of the liquid drops to the steam inlet edge of the moving blade is reduced, the erosion and mechanical impact of the moving blade are further slowed down, and the service performance and service life of the moving blade are greatly improved.

In the embodiment of the present application, the connection position between the first surface area and the step surface 71 is an edge structure, and the edge structure may be a right-angle edge, that is, the step surface 71 is perpendicular to the first surface area, and of course, the edge structure may also be a non-right-angle edge, for example, a sharp edge structure, so as to be beneficial to water film stripping. The edge structure is simple, and the processing is convenient.

In the application, the optimal positions of the concave parts 7 slightly differ according to the different stator blade structures, various proportion values shown in fig. 4 can be obtained through calculation or experiments, and various specification sizes of the concave parts 7 need to be determined according to stator blade molded lines.

The abscissa of fig. 4 is: the dimensionless number of C/B represents the axial relative position of the step surface; the ordinate is a dimensionless relative coefficient of "the impact velocity of a droplet against a moving blade, the modal diameter, and the wear velocity of the moving blade", and represents only the relative magnitude of the numerical value, not the actual numerical value. In the figure, the three curves only show the relative values of three values at different axial positions, and the impact speed, the modal diameter and the abrasion speed of the moving blade are all minimum when the axial position C of the step surface is about 70% of the total axial length B, so that the dehumidification effect is best when the step surface is about 70% away from the steam inlet side forehead line.

In the embodiment of the present application, the length of the stationary blade between the steam inlet side forehead line E and the steam outlet side forehead line F is defined as an axial length B, the step surface 71 and the second surface area have a phase connection, and the ratio of the distance C between the phase connection and the steam inlet side forehead line E to the axial length B is in the range of 0.65 to 0.75, and in one embodiment, the ratio of the phase connection to the steam inlet side forehead line E is 0.7. Within the above ratio range, the dehumidifying effect of the stator blade is good.

In the embodiment of the application, the ratio of the length L of the step surface 71 to the length of the stator blade is in the range of 1/3 to 1/2 along the length direction of the steam outlet edge 3. Within the ratio range

In the embodiment of the application, the concave part 7 extends outwards to the outer end surface of the stationary blade close to the outer ring of the partition plate. The end face of the stationary blade close to the diaphragm outer ring is defined as an outer end face, and the concave portion 7 penetrates the outer end face to form a notch on the outer end face.

In the embodiment of the application, the tangent line of the back arc surface 1 at the joint line position is perpendicular to the step surface 71. In this way, the water film stripping effect is good, and large droplets after stripping are not easily captured again by the transition surface 72 downstream of the step surface 71.

The included angle a between the step surface 71 and the inlet side forehead line E of the stator blade is as follows: 25-42 deg. The angle is a reference value for measuring whether the axial position selection of the step surface is reasonable or not and whether the angle between the step surface and the blade back arc surface molded line is reasonable or not, and each blade molded line corresponds to a proper angle a. According to the geometrical rule of the back arc surface molded lines of the stator blades, when the step surface is arranged at the position of about 70% of the axial length of the blades, the included angle range between the step surface and the forehead line of the inlet side of the stator blades is 25-42 degrees, and the step surface has the best dehumidification effect at the moment, but different blade molded lines have some differences.

In the embodiment of the present application, the depth h of the step surface 71 is in the range of 1.5mm to 4mm, and in a specific embodiment, the depth h of the step surface 71 is about 3 mm. Also, the water film peeling effect is good, and large droplets after peeling are not easily captured again by the transition surface 72 downstream of the step surface 71.

In the embodiment of the application, the step surface 71 is positioned at the position with the maximum thickness value of the water film formed by the stator blade, and the joint position of the transition surface 72 and the second surface area is positioned at the position with the maximum change of the air flow speed. The axial position of the step surface 71 starts approximately near the maximum value of the water film thickness and ends at the rapid change in the velocity of the air flow in the throat region 5 so that large droplets stripped from above the step surface 71 are not caught again by the transition surface 72 so as not to affect the steam aerodynamic performance.

The recess 7 may be formed by milling.

The turbine according to the present application includes the stator blade according to any one of the above, and therefore has the above-described technical effects of the stator blade. The plurality of static blades are arranged between the baffle outer ring 1-1 and the baffle inner ring 1-3, and the baffle outer ring 1-1, the static blades 1-2 and the baffle inner ring 1-3 can be integrated by welding, wherein the static blades 1-2 are uniformly distributed and radially arranged between the baffle outer ring 1-1 and the baffle inner ring 1-3 along the circumferential direction.

In one embodiment, the stator vanes of embodiments of the present application may also be located in a low pressure last stage diaphragm.

For other structures of the steam turbine, please refer to the prior art, and the description thereof is omitted herein.

In the application, "a plurality of" refers to a plurality of uncertain quantities, and is usually more than two; and when "a number" is used to denote the number of a certain number of components, the number of components is not necessarily related to each other.

The terms "first," "second," and the like in this disclosure are merely used for convenience in describing two or more structures or components having the same or similar structure and/or function, and do not denote any particular limitation with respect to order and/or importance.

The foregoing is merely a preferred embodiment of the present application and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present application, which are intended to be comprehended within the scope of the present application.

Claims (10)

1. The stator blade is characterized by comprising an inner arc surface, a back arc surface, a steam inlet side and a steam outlet side, wherein a part of the back arc surface is sunken to form a concave part, the back arc surface comprises a first surface area and a second surface area which are respectively arranged at two sides of the concave part from the steam inlet side to the steam outlet side, the concave part comprises a step surface and a transition surface, the step surface faces the steam outlet side, and the root of the step surface is connected with the second surface area through the transition surface;

the side of the step surface far away from the root part of the step surface is connected with the first surface area, and a structure formed at the joint position of the step surface and the first surface area can separate a water film into liquid drops which enter the throat area of the static blade along with steam.

2. The stationary blade of claim 1, wherein the first surface region and the step surface meet at a sharp edge configuration.

3. The stationary blade of claim 2, wherein a length of the stationary blade between a steam inlet side forehead line and a steam outlet side forehead line is defined as an axial length, the step surface and the second surface area have a phase line, and a ratio of a distance between the phase line and the steam inlet side forehead line to the axial length ranges from 0.65 to 0.75.

4. The stationary blade of claim 2, wherein a ratio of a length of the step surface to a length of the stationary blade along the length of the steam outlet side is in a range of 1/3 to 1/2.

5. The stationary vane of claim 1, wherein the recess extends outwardly to an outer end face of the stationary vane proximate to the diaphragm outer ring.

6. The stationary blade of claim 3, wherein a tangent to the back-arc surface at the junction location line is perpendicular to the step surface.

7. The stationary blade of claim 2, wherein the step surface has an included angle with an inlet side forehead line of the stationary blade in a range of: 25-42 deg.

8. The stationary vane of claim 2, wherein the recess has a depth in the range of 1.5mm-4mm such that the step face location droplets will be carried by the steam flow into a throat region formed adjacent the stationary vane.

9. The stationary blade according to any one of claims 2 to 8, wherein the step surface is located at a position where the thickness value of the water film formed by the stationary blade is largest, and the transition surface is located at a position where the change in the air flow velocity is largest at a position where the transition surface meets the second surface region.

10. Steam turbine, characterized by comprising a stator blade according to any of claims 1 to 9.