A temperature balance structure between interlayers of a high-power steam turbine cylinder

Abstract

The invention discloses a high-power steam turbine cylinder body interlayer temperature balance structure, comprising a steam turbine outer cylinder, a steam turbine inner cylinder and a steam inlet pipe, a cooling gas pipe is arranged on the steam inlet pipe, the cooling gas pipe is connected to the pipe interlayer of the steam inlet pipe, and there is an angle between the axis of the cooling gas pipe and the axis of the steam inlet pipe. The advantages of the invention are: taking into account the control of the difference in high and low temperature steam flow in the interlayer and blocking the backflow of interstage leakage steam in the interlayer, reducing the expansion difference change of the steam turbine cylinder body, avoiding deformation and fatigue damage of the inner and outer cylinders, and improving the thermal efficiency and service life of the steam turbine.

Description

Technical Field

[0001] The invention is applied to the technical fields of steam turbines such as thermal power and nuclear power, and specifically relates to a temperature balance structure between interlayers of a cylinder body of a high-power steam turbine. Background Art

[0002] In order to facilitate loading and unloading, transportation and prevent deformation of the cylinder, the high, medium and low pressure cylinders of high-power steam turbines are generally divided into two upper and lower half cylinders for splicing and assembly, and a sandwich is formed between the inner and outer cylinders of the cylinder. The steam medium of the steam turbine is connected to the inner cylinder of the steam turbine through the steam inlet pipe arranged on the steam inlet chamber through a sealing structure. The steam enters the steam inlet chamber through the steam inlet pipe and expands through the flow blade grid to do work. In the long-term use process, affected by repeated start-stop, high-temperature steam, oxidation and other factors, the sealing effect of the end steam seal, the butterfly steam seal around the steam inlet pipe and other structures is weakened, and the gap value between the seals changes on the basis of the designed gap. At the same time, the high-temperature steam leaks into the sandwich between the inner and outer cylinders through the gap, affecting the work efficiency of the steam turbine, increasing the thermal efficiency in the sandwich, causing the expansion difference between the stator and the rotating parts of the steam turbine to deviate from the design value, affecting the service life and safety of the cylinder.

[0003] Due to the failure of the sealing structure, the high-temperature main steam leaks through the steam inlet pipes of the upper and lower cylinders of the steam inlet chamber and the front axle, and flows into the interlayer, increasing the temperature in the interlayer. In particular, the temperature of the main steam medium of the steam turbine is high. Therefore, in order to reduce the temperature of the high-temperature steam leaking in the interlayer, cooling gas is introduced from the low-temperature and low-pressure extraction chamber of the steam turbine into the steam inlet chamber. For the steam turbine cylinder body with steam inlet pipes arranged in both the upper and lower cylinders, the reason for the high temperature difference in the interlayer is mainly related to the distribution of the cooling gas flow rate. Under the influence of gravity, the main steam and cooling gas leaking from the lower cylinder flow directly out of the exhaust pipe along the lower cylinder interlayer, and most of the high-temperature and high-pressure steam in the interlayer comes from the leakage of the steam inlet pipe of the upper cylinder. The cooling gas from the upper cylinder is affected by the distribution of its inlet pipe, so that the cooling gas steam flows directly along the cylinder wall to the lower cylinder with lower pressure. The uneven distribution of the cooling gas flow in the interlayer makes the steam temperature of the upper cylinder higher than that of the lower cylinder, resulting in high-temperature creep and uneven deformation of the cylinder, causing damage to varying degrees. At the same time, after the high-temperature main steam flows into the flow blades, part of it flows to the exhaust pipe, and part of it flows to the interstage suction port and enters the inner and outer cylinder interlayer for reflux oscillation, causing the temperature in the interlayer to fluctuate, resulting in fatigue damage and affecting the work efficiency and safety of the turbine.

[0004] In order to solve the shortcomings of the existing structure, while reducing the leakage of main steam, it is also necessary to balance the flow distribution of high-temperature leaked steam and cooling gas, so that the leaked high-temperature steam and cooling gas are evenly mixed to balance the steam temperature in the interlayer, reduce the temperature difference, reduce the fatigue damage of the turbine cylinder, and thus improve the use efficiency and safety of the turbine. Therefore, the present invention provides a structure that can reduce the steam temperature in the interlayer of the turbine cylinder and reduce the temperature difference between the upper and lower cylinders, which is a temperature balance structure between the inner and outer cylinder interlayers of a high-power turbine. Summary of the invention

[0005] The purpose of the present invention is to provide a temperature balance structure between the interlayers of a high-power steam turbine cylinder body, which takes into account controlling the difference in high and low temperature steam flow in the interlayer and blocking the backflow of interstage leakage steam in the interlayer, reducing the expansion difference of the steam turbine cylinder body, avoiding deformation and fatigue damage of the inner and outer cylinders, improving the thermal efficiency and service life of the steam turbine, and solving the problem of shortcomings in the high-power steam turbine cylinder body structure.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A high-power steam turbine cylinder body interlayer temperature balance structure comprises a steam turbine outer cylinder, a steam turbine inner cylinder and a steam inlet pipe, wherein a cooling gas pipe is arranged on the steam inlet pipe, the cooling gas pipe is connected to the pipe interlayer of the steam inlet pipe, and an angle exists between the axis of the cooling gas pipe and the axis of the steam inlet pipe.

[0008] Furthermore, the turbine outer cylinder and the turbine inner cylinder are both upper and lower half-cylinder spliced ​​assembly structures, and the steam inlet pipe includes an upper half-cylinder steam inlet pipe and a lower half-cylinder steam inlet pipe.

[0009] Furthermore, the upper half cylinder steam inlet pipe and the lower half cylinder steam inlet pipe are both arranged in double pipes.

[0010] Furthermore, the cooling gas pipeline on the upper half cylinder steam inlet pipeline is arranged as a double pipeline, including a first cooling gas pipeline and a second cooling gas pipeline.

[0011] Furthermore, the second cooling gas pipeline on the upper half cylinder steam inlet pipeline is closer to the rotor centerline than the first cooling gas pipeline, and the second cooling gas pipeline is located between the two upper half cylinder steam inlet pipelines.

[0012] Furthermore, center lines of the first cooling gas pipeline and the second cooling gas pipeline are on the same line.

[0013] Furthermore, the cooling gas pipeline on the steam inlet pipeline of the lower half cylinder is arranged as a single pipeline, including a first cooling gas pipeline.

[0014] Furthermore, the first cooling gas pipeline faces the rotor side, and the second cooling gas pipeline faces away from the rotor side.

[0015] Furthermore, the cooling gas pipelines are all located on the center plane of the steam inlet pipeline.

[0016] Furthermore, a heat insulation board structure is provided between the cylinder body interlayer between the outer cylinder of the steam turbine and the inner cylinder of the steam turbine, and the heat insulation board structure is located between the steam inlet side and the steam exhaust side.

[0017] Furthermore, the insulation board structure includes a toothed insulation board and annular ribs, the toothed insulation board is arranged on the inner wall of the outer cylinder of the turbine, the annular ribs are arranged on the insulation cover of the inner cylinder of the turbine, and the toothed insulation board and the annular ribs are arranged alternately.

[0018] Furthermore, there are two toothed heat insulation plates and two annular ribs, and the toothed heat insulation plates and the annular ribs are arranged in sequence with intervals.

[0019] Beneficial effects of the present invention:

[0020] (1) As a further structural improvement of the present invention, a cooling pipe with a certain design angle is arranged on the main steam inlet pipe, so that the cooling gas is evenly fed into the steam and fully and evenly mixed with the leaked high-temperature and high-pressure steam to ensure the cooling effect. Two small cooling gas input pipes with an inclined angle are arranged on the steam inlet pipe of the upper half cylinder of the steam turbine, and the center lines of the two small pipes are on a line. The small pipe closer to the center line of the rotor is arranged between the two main steam pipes, which is more conducive to the input cooling gas flowing along the upper half steam inlet pipe and the inner wall of the upper half cylinder to the upper half cylinder interlayer, condensing the high-temperature steam in the upper half cylinder interlayer, thereby reducing the temperature of the steam in the upper half cylinder, reducing the temperature difference between the upper and lower interlayers, reducing deformation excitation and expansion difference, and improving the service life and safety reliability of the steam turbine.

[0021] (2) As a further structural improvement of the present invention, a heat insulation plate structure is provided in the inner and outer cylinder interlayers. By providing annular ribs and tooth structure heat insulation plates, the pressure in the cylinder interlayer is increased, the flow of steam on the steam inlet side and the steam exhaust side in the interlayer is restricted, the heat radiation of the high-temperature leaked steam on the steam inlet side to the steam exhaust side is blocked, and the leakage of high-temperature steam is reduced. The annular rib structure is arranged after the tooth structure heat insulation plate, further blocking the backflow of interstage steam in the interlayer, improving the thermal efficiency of the steam turbine and reducing energy consumption.

[0022] (3) As a further structural improvement of the present invention, the heat insulation board structure in the steam turbine interlayer is arranged to be staggeredly composed of two annular ribs and two tooth structure heat insulation boards, forming a wall tooth steam seal structure, which complicates the flow path of the steam in the interlayer at the steam seal structure, increases the friction effect of high-temperature steam flowing to the exhaust area, and reduces the expansion difference change of the cylinder body. In order to avoid uneven collision damage between the steam seal teeth and the cylinder body caused by the eccentric displacement of the rotor during the operation of the steam turbine, the steam seal gap adopts a circumferentially uniform distribution form to increase the service life of the tooth structure.

[0023] The aforementioned main scheme of the present invention and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection by the present invention; and in the present invention, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present invention, those skilled in the art can understand that there are many combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present invention, and they are not exhaustively listed here. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a front cross-sectional view of the structure of the present invention.

[0025] Figure 2 It is a side sectional view of the structure of the present invention.

[0026] Figure 3 It is a schematic diagram of the cooling pipeline arrangement of the upper half cylinder steam inlet pipeline of the present invention.

[0027] Figure 4 It is a schematic diagram of the cooling pipe arrangement of the lower half cylinder intake pipe of the present invention.

[0028] Figure 5 It is a structural schematic diagram of the heat insulation board structure of the present invention.

[0029] In the figure: 1-turbine outer cylinder; 2-turbine inner cylinder; 3-heat insulation cover; 4-steam inlet pipe; 4A-upper half cylinder steam inlet pipe; 4B-lower half cylinder steam inlet pipe; 5-exhaust pipe; 6A-first cooling gas pipe; 6B-second cooling gas pipe; 7A-toothed heat insulation board; 7B-annular rib. DETAILED DESCRIPTION

[0030] The following non-limiting examples serve to illustrate the invention.

[0031] Embodiment 1:

[0032] refer to Figure 1 to Figure 5As shown, a high-power steam turbine cylinder body interlayer temperature balance structure includes a steam turbine outer cylinder 1, a steam turbine inner cylinder 2, a heat shield 3, a steam inlet pipe 4, a steam exhaust pipe 5, a cooling gas pipe and a heat insulation board structure. It is suitable for steam inlet pipe insertion occasions of steam turbine cylinder bodies with steam inlet pipes and cooling pipes in both upper and lower cylinders.

[0033] The steam turbine outer cylinder 1 and the steam turbine inner cylinder 2 are both upper and lower half-cylinder splicing and assembling structures, and a cylinder body sandwich is formed between the steam turbine outer cylinder 1 and the steam turbine inner cylinder 2.

[0034] The steam inlet pipe 4 includes an upper half cylinder steam inlet pipe 4A and a lower half cylinder steam inlet pipe 4B, and both the upper half cylinder steam inlet pipe 4A and the lower half cylinder steam inlet pipe 4B are arranged in a bilaterally symmetrical double pipe arrangement. The upper half cylinder steam inlet pipe 4A and the lower half cylinder steam inlet pipe 4B pass through the outer cylinder from the upper and lower halves of the steam inlet side of the intermediate pressure cylinder and are connected to the inner cylinder. The exhaust pipe 5 is connected to the lower half of the outer cylinder 1 of the steam turbine.

[0035] The steam inlet pipe 4 is a sleeve-type structure with an inner and outer sleeve, and a pipe interlayer is formed between the inner and outer sleeves of the steam inlet pipe 4. The outer sleeve of the steam inlet pipe 4 is connected to the outer cylinder 1 of the turbine and communicated with the cylinder interlayer, and the inner sleeve of the steam inlet pipe 4 is connected to the inner cylinder 2 of the turbine and communicated with the cylinder.

[0036] The exhaust pipe 5 is a single-tube structure, which is connected to the outer cylinder 1 of the steam turbine and communicated with the interlayer of the cylinder body.

[0037] A cooling gas pipeline is provided on the steam inlet pipeline 4. The cooling gas pipeline is located on the center plane of the steam inlet pipeline 4. The cooling gas pipeline is connected to the pipeline interlayer of the steam inlet pipeline 4. The cooling gas pipeline is designed in an inclined form. There is an angle θ between the axis of the cooling gas pipeline and the axis of the steam inlet pipeline 4, 0<θ<90°, so that the cooling gas is fully mixed with the leaked high-temperature and high-pressure steam.

[0038] The cooling gas pipeline on the upper half cylinder steam inlet pipeline 4A is arranged as a double pipeline, including a first cooling gas pipeline 6A and a second cooling gas pipeline 6B, and the center lines of the first cooling gas pipeline 6A and the second cooling gas pipeline 6B are on the same line. The first cooling gas pipeline 6A faces the rotor side, and the second cooling gas pipeline 6B faces away from the rotor side. The second cooling gas pipeline 6B on the upper half cylinder steam inlet pipeline 4A is closer to the rotor center line than the first cooling gas pipeline 6A, ensuring that the second cooling gas pipeline 6B is located between the two upper half cylinder steam inlet pipelines 4A. Under the impact of the steam leakage in the steam inlet pipeline, the cooling gas flowing through this pipeline guides more cooling gas along the upper half cylinder steam inlet pipeline 4A and the inner wall of the cylinder body to flow to the upper half cylinder, reducing the temperature of the upper half cylinder and further reducing the temperature difference between the upper and lower cylinders.

[0039] The cooling gas pipeline on the lower half cylinder steam inlet pipeline 4B is arranged as a single pipeline, including a first cooling gas pipeline 6A.

[0040] A heat insulation board structure is provided between the cylinder body interlayer between the steam turbine outer cylinder 1 and the steam turbine inner cylinder 2. The heat insulation board structure is located between the steam inlet side and the steam exhaust side. A heat insulation cover 3 is provided inside the steam turbine inner cylinder 2.

[0041] The steam seal gap of the insulation board structure is evenly distributed circumferentially to form a wall-tooth steam seal structure, which complicates the steam flow path in the interlayer. On the one hand, it increases the flow resistance of main steam leakage, increases the pressure in the interlayer, and reduces the leakage of shaft seal steam. On the other hand, it reduces the reflux amount of steam on the exhaust side in the interlayer, thereby improving the working efficiency of the steam turbine.

[0042] The heat insulation plate structure includes a toothed heat insulation plate 7A and an annular rib 7B. The toothed heat insulation plate 7A is arranged on the inner wall of the steam turbine outer cylinder 1, and the annular rib 7B is arranged on the heat insulation cover 3 of the steam turbine inner cylinder 2. The toothed heat insulation plate 7A and the annular rib 7B are arranged alternately. There are two toothed heat insulation plates 7A and two annular ribs 7B, and the toothed heat insulation plates 7A and the annular ribs 7B are arranged alternately in sequence.

[0043] The ribs and the tooth-shaped structure are overlapped and staggered in height, and the ribs are located on the rear side of the tooth-shaped structure. The ribs and the tooth-shaped structure together constitute a steam seal structure in the form of city wall teeth. The circumferential gap is evenly distributed, which further increases the airflow resistance of the leaked steam from the high-temperature and high-pressure area of ​​the cylinder into the exhaust area and reduces the change of the cylinder expansion difference.

[0044] The working principle of the present invention is as follows: In the structural form in which a cooling gas pipeline is arranged on the steam inlet pipeline of the turbine cylinder body, a small cooling gas pipeline is arranged on the steam inlet pipeline at a certain design angle θ, so that the cooling gas and the leaked high-temperature and high-pressure steam are mixed more evenly. A small cooling gas pipeline inclined downward is added between the two steam inlet pipelines of the upper cylinder, so that more cooling gas flows along the pipe wall to the upper cylinder, reducing the temperature difference between the upper and lower cylinders, reducing deformation excitation, expansion difference and fatigue damage to the cylinder. The heat insulation plate structure of the wall tooth steam seal is arranged in the interlayer, and the tooth structure and the annular rib structure are staggered to increase the flow resistance of the front and rear steam in the interlayer, reduce the steam leakage of the shaft seal and the steam reflux in the exhaust area, improve the thermal efficiency of the steam turbine, and reduce energy consumption.

[0045] The above basic examples of the present invention and their further optional examples can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and claimed for protection by the present invention. In the scheme of the present invention, each optional example can be arbitrarily combined with any other basic examples and optional examples.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-power steam turbine cylinder interlayer temperature balance structure, comprising a steam turbine outer cylinder (1), a steam turbine inner cylinder (2) and a steam inlet pipe (4), characterized in that: The steam inlet pipe (4) is provided with a cooling gas pipe, the cooling gas pipe is connected to the pipe interlayer of the steam inlet pipe (4), and an angle exists between the axis of the cooling gas pipe and the axis of the steam inlet pipe (4); The steam turbine outer cylinder (1) and the steam turbine inner cylinder (2) are both upper and lower half-cylinder spliced ​​assembly structures, and the steam inlet pipe (4) comprises an upper half-cylinder steam inlet pipe (4A) and a lower half-cylinder steam inlet pipe (4B); The cooling gas pipeline on the upper half cylinder steam inlet pipeline (4A) is arranged as a double pipeline, including a first cooling gas pipeline (6A) and a second cooling gas pipeline (6B); The second cooling gas pipeline (6B) on the upper half cylinder steam inlet pipeline (4A) is closer to the rotor centerline than the first cooling gas pipeline (6A), and the second cooling gas pipeline (6B) is located between the two upper half cylinder steam inlet pipelines (4A); The center lines of the first cooling gas pipeline (6A) and the second cooling gas pipeline (6B) are on the same line; The cooling gas pipeline on the lower half cylinder steam inlet pipeline (4B) is arranged as a single pipeline, including a first cooling gas pipeline (6A); The first cooling gas pipeline (6A) faces the rotor side, and the second cooling gas pipeline (6B) faces away from the rotor side; The cooling gas pipelines are all located on the center plane of the steam inlet pipeline (4).

2. The high-power steam turbine cylinder interlayer temperature balance structure according to claim 1 is characterized in that: A heat insulation board structure is provided between the cylinder body interlayer between the steam turbine outer cylinder (1) and the steam turbine inner cylinder (2), and the heat insulation board structure is located between the steam inlet side and the steam exhaust side.

3. The high-power steam turbine cylinder interlayer temperature balance structure according to claim 2 is characterized in that: The heat insulation plate structure comprises a toothed heat insulation plate (7A) and an annular rib (7B), wherein the toothed heat insulation plate (7A) is arranged on the inner wall of the steam turbine outer cylinder (1), and the annular rib (7B) is arranged on the heat insulation cover (3) of the steam turbine inner cylinder (2), and the toothed heat insulation plate (7A) and the annular rib (7B) are arranged in an alternating manner.

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