Subcritical turboset nozzle blade boriding sealing device

Abstract

The invention discloses a subcritical turboset nozzle blade boriding sealing device which comprises a base provided with a first containing groove; the inner circle positioning plate is arranged on the base and covers part of the first containing groove; the outer circle positioning plate is arranged on the base, located on the outer side of the inner circle positioning plate and covers part of the first containing groove. The cover plate is arranged on the inner circle positioning plate and the outer circle positioning plate and is matched with the base, the inner circle positioning plate and the outer circle positioning plate to form a containing cavity for containing the nozzle blades; and the gap between the accommodating cavity and the nozzle blade is smaller than or equal to 0.02 mm, so that the deformation of a workpiece in a high-temperature environment during boronizing is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbines, and in particular to a boronized sealing device for nozzle blades of a subcritical steam turbine unit. Background Art

[0002] The inlet steam temperature of the subcritical steam turbine nozzle is as high as 538℃, and the nozzle is subjected to a high temperature and high pressure steam environment. Due to the high air flow velocity at the nozzle, the solid oxide particles erode the nozzle blades very severely, causing great loss of the steam flow channel, which not only easily causes the operating efficiency of the steam turbine unit to decrease, but also greatly shortens the overhaul interval of the unit.

[0003] The existing technology of nozzle blade boronizing heat treatment is usually to install the nozzle blade into a sealing device with an annular channel, and there is usually a gap of more than 0.2mm between the blade and the channel wall to facilitate the installation and removal of the blade. Since there is a steam channel gap inside the nozzle blade structure, the part is a thin-walled part, which is very easy to deform at high temperature. Since the gap between the channel wall and the blade of the boronizing device is relatively large and cannot restrain the deformation of the blade, the size of the steam channel gap is easily out of tolerance, resulting in the scrapping of the blade, and it is easy to get stuck in the annular groove and difficult to remove. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a subcritical steam turbine unit nozzle blade boronizing sealing device, which can reduce the deformation of the workpiece in a high temperature environment during boronizing.

[0005] The present invention adopts the following technical solutions:

[0006] A subcritical steam turbine unit nozzle blade boriding sealing device comprises: a base having a first accommodating groove; an inner circle positioning plate arranged on the base and covering a portion of the first accommodating groove; an outer circle positioning plate arranged on the base and located outside the inner circle positioning plate and covering a portion of the first accommodating groove; a cover plate arranged on the inner circle positioning plate and the outer circle positioning plate and cooperating with the base, the inner circle positioning plate and the outer circle positioning plate to form an accommodating cavity for accommodating the nozzle blade; the gap between the accommodating cavity and the nozzle blade is less than or equal to 0.02mm.

[0007] Preferably, the base, the inner circle positioning plate, the outer circle positioning plate and the cover plate together form an accommodating cavity for accommodating the nozzle blades.

[0008] Preferably, the nozzle blade comprises a blade body, an upper convex portion, a lower convex portion, a first shoulder and a second shoulder located on both sides of the upper convex portion, and a lower shoulder located on one side of the lower convex portion.

[0009] Preferably, the inner circular positioning plate covers part of the first receiving groove to form a lower receiving cavity for receiving the lower protrusion.

[0010] Preferably, the first accommodating groove has a stepped portion, and the outer circular positioning plate covers a portion of the first accommodating groove and cooperates with the stepped portion to form an upper accommodating cavity for accommodating the upper protrusion.

[0011] Preferably, there are four inner circle positioning plates, each of which has an angle of 90 degrees and can move radially relative to the nozzle blades.

[0012] Preferably, there are gap filling blocks between adjacent inner circle positioning plates.

[0013] Preferably, the outer circular positioning plate is arranged on the base by bolts or pins.

[0014] Compared with the prior art, the present invention has the following advantages: the present invention provides a subcritical steam turbine unit nozzle blade boronizing sealing device, including a base, an inner circle positioning plate, an outer circle positioning plate and a cover plate, which can be combined to form a accommodating cavity for accommodating the nozzle blade, and the gap between the accommodating cavity and the nozzle blade is less than or equal to 0.02mm, which limits the deformation of the workpiece in a high temperature environment during boronizing. At the same time, the split design adopted facilitates the removal of the workpiece after boronizing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the explosion structure of the nozzle blade boronizing sealing device.

[0016] Figure 2 This is a partial structural schematic diagram of the nozzle blade boronizing sealing device.

[0017] Figure 3 A cross-sectional view of the nozzle blade boronized seal.

[0018] Figure 4 for Figure 3 A partial enlarged view of part A.

[0019] Figure 5 A cross-sectional view of the nozzle blade.

[0020] Figure 6 for Figure 5 A partial enlarged view of part B.

[0021] In the figure, a base 1, a first accommodating groove 1-1, a stepped portion 1-2, an inner circular positioning plate 2, an outer circular positioning plate 3, a cover plate 4, a nozzle blade 5, a blade body 5-1, an upper protrusion 5-2, a lower protrusion 5-3, a first shoulder 5-4, a second shoulder 5-5, a lower shoulder 5-6, an accommodating chamber 6, a lower accommodating chamber 6-1, an upper accommodating chamber 6-2, and a gap filling block 7. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the technical solution of the present invention, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0023] Example 1

[0024] The conventional boriding process is: the boriding heating temperature is between 900 and 960°C, the holding time is ≥5h, and the thickness of the boriding layer is ≥0.05mm. After boriding, the workpiece is tempered to complete the entire boriding and tempering process. The boriding layer on the surface of the workpiece is mainly Fe2B, with only a small amount of FeB, and its thickness is ≥0.05mm. The outer layer is FeB, followed by Fe2B. The organizational morphology is uniform and dense, and the boriding layer is firmly bonded to the matrix. The hardness of the boriding layer after boriding is 1400~1700HV0.2, which is equivalent to more than 70HRC, which can greatly improve the wear resistance of the product and extend its service life. The boriding process of the nozzle blade requires the nozzle blade to be installed in the fixture, then filled with the boriding agent, and then the entire fixture is placed in the heating furnace for processing through the above-mentioned boriding process.

[0025] like Figure 1-2 As shown, a subcritical steam turbine unit nozzle blade boronizing sealing device is a disc-shaped structure as a whole, comprising:

[0026] A base 1 having a first receiving groove 1-1;

[0027] An inner circle positioning plate 2 is disposed on the base 1 and covers a portion of the first receiving groove 1-1;

[0028] The outer circle positioning plate 3 is an annular structure, which is arranged on the base 1, located outside the inner circle positioning plate 2, and covers part of the first accommodating groove 1-1;

[0029] The cover plate 4 is arranged on the inner circle positioning plate 2 and the outer circle positioning plate 3, and cooperates with the base 1, the inner circle positioning plate 2 and the outer circle positioning plate 3 to form an accommodating cavity 6 for accommodating the nozzle blade 5;

[0030] The gap between the accommodating cavity 6 and the nozzle blade 5 is less than or equal to 0.02 mm.

[0031] When in use, the nozzle blade 5 is placed in the accommodating cavity 6, and then the boriding process is carried out. Since the gap between the nozzle blade 5 and each surface in the accommodating cavity 6 is small, the deformation of the workpiece in a high temperature environment during boriding can be limited.

[0032] Specifically, the base 1, the inner circle positioning plate 2, the outer circle positioning plate 3 and the cover plate 4 together form a accommodating cavity 6 for accommodating the nozzle blade 5. During installation, the nozzle blade 5 is first placed in the first accommodating groove 1-1 of the base 1, and then the inner circle positioning plate 2 and the outer circle positioning plate 3 are placed on the base 1 in turn, and finally the cover plate 4 is covered on the inner circle positioning plate 2 and the outer circle positioning plate 3, and connected and fixed by bolts or pins.

[0033] like Figure 5-6In the present embodiment, the nozzle blade 5 comprises a blade body 5-1, an upper protrusion 5-2, a lower protrusion 5-3, a first shoulder 5-4 and a second shoulder 5-5 located on both sides of the upper protrusion 5-2, and a lower shoulder 5-6 located on one side of the lower protrusion 5-3.

[0034] like Figure 3-4 As shown, the inner circle positioning plate 2 covers part of the first receiving groove 1-1 to form a lower receiving cavity 6-1 for receiving the lower protrusion 5-3; the first receiving groove 1-1 has a stepped portion 1-2, and the outer circle positioning plate 3 covers part of the first receiving groove 1-1 and cooperates with the stepped portion 1-2 to form an upper receiving cavity 6-2 for receiving the upper protrusion 5-2. The first limiting surface 1-3 of the first receiving groove 1-1 cooperates with the first shoulder 5-4, the inner limiting surface 3-1 of the outer circle positioning plate 3 cooperates with the second shoulder 5-5, and the outer limiting surface 2-1 of the inner circle positioning plate 2 cooperates with the lower shoulder 5-6, so that the gap between each surface of the nozzle blade 5 and each wall surface of the receiving cavity 6 is less than or equal to 0.02mm, preferably 0.02mm, which can effectively limit the deformation caused by the stress release of the nozzle blade 5 at high temperature.

[0035] As a preferred embodiment, the inner circle positioning plates 2 have four pieces, each of which has an angle of 90 degrees and can move radially relative to the nozzle blades 5, and the outer circle positioning plates 3 are set on the base 1 by bolts or pins. During the boronizing process, the boronizing agent is poured into the accommodating cavity 6 and filled to carry out the boronizing process. After the boronizing process is completed, the bolts or pins are removed, the cover plate 4 is removed, and then the outer circle positioning plates 3 are removed along the axial direction. The four inner circle positioning plates 2 can be removed along the radial direction, and finally the nozzle blades 5 are removed.

[0036] As a preferred embodiment, gap filling blocks 7 are provided between adjacent inner circle positioning plates 2 , and the size of the outer surface of the inner circle positioning plates 2 can be adjusted by the gap filling blocks 7 .

[0037] The above are only preferred embodiments of the present invention. The protection scope of the present invention shall be based on the scope defined by the claims. Several improvements and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A boronized sealing device for nozzle blades of a subcritical steam turbine unit, characterized in that: include: A base (1) having a first receiving groove (1-1); An inner circle positioning plate (2) is arranged on the base (1) and covers a portion of the first receiving groove (1-1); An outer circular positioning plate (3) is arranged on the base (1), is located outside the inner circular positioning plate (2), and covers a portion of the first receiving groove (1-1); A cover plate (4) is arranged on the inner circle positioning plate (2) and the outer circle positioning plate (3), and cooperates with the base (1), the inner circle positioning plate (2) and the outer circle positioning plate (3) to form a receiving cavity (6) for receiving the nozzle blade (5); The gap between the accommodating cavity (6) and the nozzle blade (5) is less than or equal to 0.02 mm.

2. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 1, characterized in that: The base (1), the inner circle positioning plate (2), the outer circle positioning plate (3) and the cover plate (4) together form a receiving cavity (6) for receiving the nozzle blades (5).

3. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 1, characterized in that: The nozzle blade (5) comprises a blade body (5-1), an upper convex portion (5-2), a lower convex portion (5-3), a first shoulder (5-4) and a second shoulder (5-5) located on both sides of the upper convex portion (5-2), and a lower shoulder (5-6) located on one side of the lower convex portion (5-3).

4. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 3, characterized in that: The inner circle positioning plate (2) covers a portion of the first accommodating groove (1-1) to form a lower accommodating cavity (6-1) for accommodating the lower convex portion (5-3).

5. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 3, characterized in that: The first accommodating groove (1-1) has a stepped portion (1-2), and the outer circular positioning plate (3) covers a portion of the first accommodating groove (1-1) and cooperates with the stepped portion (1-2) to form an upper accommodating cavity (6-2) for accommodating the upper protrusion (5-2).

6. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 1, characterized in that: The inner circle positioning plates (2) have four pieces, each of which has an angle of 90 degrees and can move radially relative to the nozzle blades (5).

7. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 6, characterized in that: There are gap filling blocks (7) between adjacent inner circle positioning plates (2).

8. The subcritical steam turbine nozzle blade boronizing sealing device according to claim 6, characterized in that: The outer circular positioning plate (3) is arranged on the base (1) via bolts or pins.

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