External dehumidification device for low-pressure wet steam intermediate machine of steam turbine

Abstract

Disclosed in the present invention is an external dehumidification device for a low-pressure wet steam intermediate machine of a steam turbine, comprising a shell provided with a wet steam inlet and a dry steam outlet, and further comprising first-stage steam-water separation corrugated plates and second-stage steam-water separation corrugated plates which are arranged in the shell, wherein the second-stage steam-water separation corrugated plates are arranged downstream of the first-stage steam-water separation corrugated plates, and the distance between every two adjacent corrugated plates among the first-stage steam-water separation corrugated plates is greater than the distance between every two adjacent corrugated plates among the second-stage steam-water separation corrugated plates. According to the present invention, the resistance to steam is reduced on the whole, smooth flow of steam is ensured, the dehumidification efficiency is improved, water-steam separation is carried out twice, and the technical means of coarse dehumidification and fine dehumidification effectively ensures the dehumidification effect. In addition, by means of the arrangement of a gland steam pipe, it can be ensured that the dryness of the steam reaches 100%, thereby reducing the operation risk of the steam turbine, and improving the steam-water cycle efficiency.

Description

A steam turbine low-pressure wet steam intermediate external dehumidification equipment

[0001] The present invention claims priority to a Chinese patent application filed with the Patent Office of China on June 26, 2023, with application number 202310760554.0 and invention name “A steam turbine low-pressure wet steam intermediate external dehumidification device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of external dehumidification of steam turbines, and more particularly to an external dehumidification device for intermediate low-pressure wet steam of steam turbines. Background Art

[0003] After steam performs work in the turbine cylinder, its pressure and temperature decrease. If dehumidification is not performed, depending on the main steam parameters and back pressure design, the humidity in the final stage may exceed 14%. Such wet steam will cause severe water erosion on the final stage blades. The current anti-water erosion solutions in the industry are also unable to solve the problem of water erosion on blades with such high humidity, and the stable operation of the turbine will not be guaranteed. To avoid the above situation, it is necessary to reduce the humidity of the steam in the final stage and improve the working conditions of the final stage blades. To this end, those skilled in the art have designed a steam turbine external dehumidification device. The steam turbine external dehumidification device mainly includes an outer shell and a plurality of steam-water separation corrugated plates arranged in the outer shell.

[0004] However, if the spacing between two adjacent steam-water separation corrugated plates is small, the steam resistance will increase, which is not conducive to the flow of steam, thereby reducing the dehumidification efficiency; if the spacing between two adjacent steam-water separation corrugated plates is large, the dehumidification quality will be reduced.

[0005] Therefore, how to ensure the dehumidification quality while reducing the steam resistance and improving the dehumidification efficiency is a key issue that needs to be solved urgently by those skilled in the art.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to ensure dehumidification quality while reducing steam resistance and improving dehumidification efficiency. To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A steam turbine low-pressure wet steam intermediate external dehumidification device includes an outer shell having a wet steam inlet and a dry steam outlet, and also includes a first-level steam-water separation corrugated plate and a second-level steam-water separation corrugated plate arranged in the outer shell, the second-level steam-water separation corrugated plate being arranged downstream of the first-level steam-water separation corrugated plate, and the spacing between two adjacent corrugated plates in the first-level steam-water separation corrugated plate is greater than the spacing between two adjacent corrugated plates in the second-level steam-water separation corrugated plate.

[0009] Preferably, the spacing between two adjacent corrugated plates in the first-stage steam-water separation corrugated plates is 9-11 mm; the spacing between two adjacent corrugated plates in the second-stage steam-water separation corrugated plates is 6-8 mm.

[0010] Preferably, the bending angle of the corrugated plate in the first-stage steam-water separation corrugated plate is 100-130°, and the bending angle of the corrugated plate in the second-stage steam-water separation corrugated plate is 100-130°.

[0011] Preferably, a partition extending along the central axis of the shell is provided in the inner cavity of the shell, the partition divides the shell into a first cavity and a second cavity, a connecting cavity is formed between the bottom of the partition and the bottom of the shell, the first cavity is connected with the second cavity through the connecting cavity, the wet steam inlet is directly connected to the first cavity, the dry steam outlet is directly connected to the second cavity, the first-level steam-water separation corrugated plate is arranged in the first cavity, and the second-level steam-water separation corrugated plate is arranged in the second cavity.

[0012] Preferably, a heating device is provided in the housing and downstream of the secondary steam-water separation corrugated plate, and the heating device is used to heat the steam dehumidified by the secondary steam-water separation corrugated plate.

[0013] Preferably, the heating device is a shaft sealing steam pipe, and a shaft sealing steam inlet and a shaft sealing steam outlet are provided on the shell of the outer shell. One end of the shaft sealing steam inlet is connected to the shaft sealing system of the steam turbine through a pipeline, and the other end is connected to the inlet of the shaft sealing steam pipe. One end of the shaft sealing steam outlet is connected to the outlet of the shaft sealing steam pipe, and the other end is connected to the exhaust pipeline.

[0014] Preferably, the shaft sealing steam pipes are multiple and arranged in parallel, and the multiple shaft sealing steam pipes are arranged at intervals.

[0015] Preferably, a drain groove is provided at the bottom of the shell, and the drain groove is located below the partition plate, for receiving water separated by the primary steam-water separation corrugated plate and the secondary steam-water separation corrugated plate.

[0016] Preferably, a through opening communicating with the drain groove and an external drain pipe is provided at the bottom of the drain groove.

[0017] Preferably, a steam uniform distribution mesh plate is further provided between the wet steam inlet and the first-stage steam-water separation corrugated plate.

[0018] The above technical solution demonstrates that the low-pressure wet steam entering the housing through the wet steam inlet has a high water content. Even if the spacing between the corrugated plates in the first-stage steam-water separation corrugated plates is large, a large amount of water can still be separated from the low-pressure wet steam. The large spacing between the corrugated plates in the first-stage steam-water separation corrugated plates significantly reduces resistance to the steam, thereby facilitating steam flow. After steam separation by the first-stage steam-water separation corrugated plates, the water content in the steam is significantly reduced. If the spacing between the corrugated plates in the second-stage steam-water separation corrugated plates is too large, further steam separation becomes difficult. Therefore, the present invention reduces the spacing between the corrugated plates in the second-stage steam-water separation corrugated plates to improve the secondary steam separation efficiency, thereby effectively ensuring the dehumidification efficiency of the external dehumidification equipment.

[0019] The present invention not only reduces the resistance to steam as a whole, ensures the smooth flow of steam, thereby improving the dehumidification efficiency, but also separates water vapor twice, and the technical means of coarse dehumidification first and then fine dehumidification effectively ensures the dehumidification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0021] FIG1 is a plan view of a steam turbine low-pressure wet steam intermediate external dehumidification device provided by a specific embodiment of the present invention;

[0022] FIG2 is a schematic structural diagram of two adjacent corrugated plates in a primary steam-water separation corrugated plate provided by a specific embodiment of the present invention.

[0023] Among them, 1-wet steam inlet, 2-dry steam outlet, 3-external drain pipe, 4-shaft seal steam inlet, 5-shaft seal steam outlet, 6-first-stage steam-water separation corrugated plate, 7-second-stage steam-water separation corrugated plate, 8-drain groove, 61-corrugated plate in the first-stage steam-water separation corrugated plate. DETAILED DESCRIPTION

[0024] The invention discloses an external dehumidification device for low-pressure wet steam of a steam turbine. The external dehumidification device can ensure the dehumidification quality, reduce the steam resistance and improve the dehumidification efficiency.

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "upper" and "lower" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0027] Please refer to Figures 1 and 2.

[0028] The present invention discloses an external dehumidification device for low-pressure wet steam from a steam turbine. The external dehumidification device includes a housing, a first-stage steam-water separation corrugated plate 6, and a second-stage steam-water separation corrugated plate 7. The housing has a wet steam inlet 1 and a dry steam outlet 2. The first-stage steam-water separation corrugated plate 6 and the second-stage steam-water separation corrugated plate 7 are disposed within the housing, with the first-stage steam-water separation corrugated plate 6 located upstream of the second-stage steam-water separation corrugated plate 7. The low-pressure wet steam from the steam turbine enters the housing through the wet steam inlet 1, then undergoes steam-water separation in the first-stage steam-water separation corrugated plate 6 and the second-stage steam-water separation corrugated plate 7, in sequence, before being discharged through the dry steam outlet 2.

[0029] The primary steam-water separation corrugated plates 6 include multiple corrugated plates arranged side by side. The secondary steam-water separation corrugated plates 7 also include multiple corrugated plates arranged side by side. The spacing between two adjacent corrugated plates 61 in the primary steam-water separation corrugated plates 6 is S1, and the spacing between two adjacent corrugated plates in the secondary steam-water separation corrugated plates 7 is S2. In the present invention, S1>S2.

[0030] The low-pressure wet steam entering the housing through the wet steam inlet 1 has a high water content. Even if the spacing between the corrugated plates 61 in the first-stage steam-water separation corrugated plates 6 is large, a large amount of water can be separated from the low-pressure wet steam. Since the spacing between the corrugated plates 61 in the first-stage steam-water separation corrugated plates 6 is large, the resistance to the steam can be significantly reduced, thereby facilitating the flow of steam. After water vapor separation by the first-stage steam-water separation corrugated plates 6, the water content in the steam is significantly reduced. If the spacing between the corrugated plates in the second-stage steam-water separation corrugated plates 7 is too large, it will be difficult to further separate the steam from the water vapor. Therefore, the present invention designs the spacing between the corrugated plates in the second-stage steam-water separation corrugated plates 7 to be smaller, so as to improve the separation effect of the secondary steam water vapor separation, thereby effectively ensuring the dehumidification effect of the external dehumidification equipment.

[0031] The present invention not only reduces the resistance to steam as a whole, ensures the smooth flow of steam, thereby improving the dehumidification efficiency, but also separates water vapor twice, and the technical means of coarse dehumidification first and then fine dehumidification effectively ensures the dehumidification effect.

[0032] In a specific embodiment of the present invention, the spacing S1 between two adjacent corrugated plates in the first-stage steam-water separation corrugated plates 6 is 9-11 mm, preferably 10 mm. The spacing S2 between two adjacent corrugated plates in the second-stage steam-water separation corrugated plates 7 is 6-8 mm, preferably 7 mm.

[0033] The principle of corrugated plate separation is this: when a stream of gas containing droplets passes through the corrugated plates, the curvature of the flow path causes the mixture to follow a sinusoidal trajectory rather than a straight line. During this motion, when droplets pass through a bend, the difference between centrifugal force and inertial force prevents them from moving with the gas stream and instead are thrown onto the corrugated plates. Because the corrugated plates use metal walls with excellent adsorption properties, droplets that strike the walls are attracted to form a water film, which then flows downward along the plates under the influence of gravity.

[0034] The bend angle of the corrugated plate cannot be too small, otherwise it will increase the resistance to the steam flow and hinder the flow of steam. At the same time, the bend angle of the corrugated plate cannot be too large, otherwise the steam-water separation effect will be ineffective. Therefore, the present invention limits the bend angle of the corrugated plate to 100-130°.

[0035] The inner cavity of the shell is divided into two left and right cavities by a partition, namely the first cavity and the second cavity. The partition extends along the centerline axis of the shell. There is a certain distance between the bottom of the partition and the bottom of the shell, forming a connecting cavity, and the first cavity is connected to the second cavity through the connecting cavity. The wet steam inlet 1 is directly connected to the first cavity, and the dry steam outlet 2 is directly connected to the second cavity. The first-level steam-water separation corrugated plate 6 is arranged in the first cavity, and the second-level steam-water separation corrugated plate 7 is arranged in the second cavity. Such an arrangement can make the structure of the external dehumidification equipment compact. After passing through the first-level steam-water separation corrugated plate 6, the steam goes around the connecting cavity under the bottom plate, and then flows upward through the second-level steam-water separation corrugated plate 7.

[0036] Corrugated plate dehumidification belongs to mechanical dehumidification, and mechanical dehumidification cannot reach 100%. After dehumidification by the primary steam-water separation corrugated plate 6 and the secondary steam-water separation corrugated plate 7, the dryness of the steam is about 99.5%. The remaining moisture in the steam will increase the risk for the operation of the steam turbine and reduce the circulation efficiency for the steam-water cycle. For this reason, the present invention provides a heating device downstream of the secondary steam-water separation corrugated plate 7, or above the secondary steam-water separation corrugated plate 7. After the steam undergoes two water vapor separations, when it passes through the heating device, the moisture in the steam will be converted into saturated steam, thereby making the steam dryness reach 100%. In this way, the risk of steam turbine operation can be reduced and the circulation efficiency of the steam-water cycle can be improved.

[0037] The present invention takes into account the high enthalpy of the turbine's shaft seal steam. If the shaft seal steam is simply used to heat condensate, the shaft seal steam cannot be effectively utilized. However, if the shaft seal steam is used to heat steam after two steam-water separations, it will ensure that the steam becomes saturated steam, thereby achieving a steam dryness of 100%. Therefore, the present invention provides a heating device as a shaft seal steam pipe, and the shell of the outer shell is provided with a shaft seal steam inlet 4 and a shaft seal steam outlet 5. One end of the shaft seal steam inlet 4 is connected to the turbine's shaft seal system via a pipeline, for introducing shaft seal steam into the shaft seal steam inlet 4, and the other end is connected to the inlet of the shaft seal steam pipe. The shaft seal steam from the shaft seal system enters the shaft seal steam pipe through the pipeline and the shaft seal steam inlet 4. In the shaft seal steam pipe, the shaft seal steam releases heat to the steam in the outer shell to vaporize the steam. The shaft seal steam is then discharged from the outer shell through the shaft seal steam outlet 5.

[0038] To ensure uniform heating of the shaft seal steam, the present invention provides multiple shaft seal steam pipes to form a shaft seal steam pipe bundle. The multiple shaft seal steam pipes are evenly distributed above the secondary steam-water separation corrugated plate 7 so that the steam in the space above the secondary steam-water separation corrugated plate 7 is evenly heated.

[0039] In order to evenly distribute the steam entering from the wet steam inlet 1 of the shell, the present invention provides a steam evenly distributing mesh plate between the wet steam inlet 1 and the first-stage steam-water separation corrugated plate 6. After the action of the steam evenly distributing mesh plate, the steam will be evenly distributed on the cross section of the first chamber, thereby improving the uniformity of dehumidification.

[0040] The present invention provides a drain groove 8 at the bottom of the housing, located below the partition. The drain groove 8 communicates with both the first and second chambers. After separation of water by the primary water-separation corrugated plates 6, water adhering to the surface of the primary water-separation corrugated plates 6 flows downward along the plates under the action of gravity and falls into the drain groove 8. Similarly, after separation of water by the secondary water-separation corrugated plates 7, water adhering to the surface of the secondary water-separation corrugated plates 7 flows downward along the plates under the action of gravity and falls into the drain groove 8.

[0041] In order to drain the water in the drain groove 8, the present invention provides a through hole at the bottom of the drain groove 8, which is used to connect the drain groove 8 and the external drain pipe 3. The external drain pipe 3 is provided with a valve to drain the water in the drain groove 8 regularly.

[0042] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0043] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0044] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A steam turbine low-pressure wet steam intermediate external dehumidification device, comprising a housing, the housing having a wet steam inlet (1) and a dry steam outlet (2), characterized in that: It also includes a primary steam-water separation corrugated plate (6) and a secondary steam-water separation corrugated plate (7) arranged in the shell, wherein the secondary steam-water separation corrugated plate (7) is arranged downstream of the primary steam-water separation corrugated plate (6), and the spacing between two adjacent corrugated plates (61) in the primary steam-water separation corrugated plate (6) is greater than the spacing between two adjacent corrugated plates in the secondary steam-water separation corrugated plate (7).

2. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 1, characterized in that: The spacing between two adjacent corrugated plates (61) in the first-stage steam-water separation corrugated plate (6) is 9-11 mm; the spacing between two adjacent corrugated plates in the second-stage steam-water separation corrugated plate (7) is 6-8 mm.

3. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 1, characterized in that: The bending angle of the corrugated plate (61) in the primary steam-water separation corrugated plate (6) is 100-130°, and the bending angle of the corrugated plate in the secondary steam-water separation corrugated plate (7) is 100-130°.

4. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 1, characterized in that: A partition extending along the central axis of the shell is arranged in the inner cavity of the shell, the partition divides the shell into a first cavity and a second cavity, a connecting cavity is formed between the bottom of the partition and the bottom of the shell, the first cavity is connected with the second cavity through the connecting cavity, the wet steam inlet (1) is directly connected to the first cavity, the dry steam outlet (2) is directly connected to the second cavity, the first-level steam-water separation corrugated plate (6) is arranged in the first cavity, and the second-level steam-water separation corrugated plate (7) is arranged in the second cavity.

5. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 1, characterized in that: A heating device is provided in the shell and downstream of the secondary steam-water separation corrugated plate (7), and the heating device is used to heat the steam dehumidified by the secondary steam-water separation corrugated plate (7).

6. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 5, characterized in that: The heating device is a shaft seal steam pipe. The shell of the outer shell is provided with a shaft seal steam inlet (4) and a shaft seal steam outlet (5). One end of the shaft seal steam inlet (4) is connected to the shaft seal system of the steam turbine through a pipeline, and the other end is connected to the inlet of the shaft seal steam pipe. One end of the shaft seal steam outlet (5) is connected to the outlet of the shaft seal steam pipe, and the other end is connected to the exhaust pipeline.

7. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 6, characterized in that: The shaft sealing steam pipes are multiple and arranged in parallel, and the multiple shaft sealing steam pipes are arranged at intervals.

8. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 4, characterized in that: A drainage groove (8) is provided at the bottom of the shell. The drainage groove (8) is located below the partition plate and is used to receive water separated by the primary steam-water separation corrugated plate (6) and the secondary steam-water separation corrugated plate (7).

9. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 8, characterized in that: The bottom of the drain groove (8) is provided with a through opening communicating with the drain groove (8) and the external drain pipe (3).

10. The steam turbine low-pressure wet steam intermediate external dehumidification equipment according to claim 1, characterized in that: A steam distribution mesh plate is also provided between the wet steam inlet (1) and the first-level steam-water separation corrugated plate (6).

Images