Steam turbine low-pressure inner cylinder with multi-stage steam extraction opening structure

Abstract

The invention discloses a steam turbine low-pressure inner cylinder with a multi-stage steam extraction opening structure, and belongs to the technical field of thermal power steam turbines. According to the low-pressure inner cylinder, through the asymmetric combination design of a steam turbine side partition plate holding ring and a motor side partition plate holding ring, a first-stage partition plate holding ring is independently arranged on the steam turbine side, a second-stage partition plate holding ring and a third-stage partition plate holding ring are integrated, the first-stage partition plate holding ring and the second-stage partition plate holding ring are integrated on the motor side, the third-stage partition plate holding ring is independently arranged on the motor side, and a fourth-stage steam extraction opening is integrated on the single inner cylinder in cooperation with a fourth-stage partition plate holding ring which is symmetrically arranged; the steam extraction pipes adopt a mode of combining same-side concentration and diagonal distribution, so that the degree of asymmetry of steam extraction is reduced; the problems that a traditional low-pressure inner cylinder structure is not universal, cannot be matched with a low-pressure heater and is uneven in multi-cylinder steam extraction amount are solved, module generalization and compact arrangement of a steam extraction cavity are achieved, the low-pressure inner cylinder structure is suitable for double-cylinder and three-cylinder configuration units, the economical efficiency and reliability of a steam turbine regenerative system are remarkably improved, and the manufacturing and maintenance cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power steam turbines, and particularly relates to a low-pressure inner cylinder of a steam turbine, and more particularly to a structural design capable of arranging multiple extraction ports on a single low-pressure inner cylinder. Background Art

[0002] In thermal power generation, a steam turbine is one of the core devices for energy conversion. To improve the thermal cycle efficiency, modern steam turbines generally adopt the feedwater regenerative cycle technology, that is, extracting a part of the steam from certain intermediate stages of the steam turbine to heat the feedwater, so as to reduce the heat released by the exhaust steam to the cold source, thereby significantly improving the cycle thermal efficiency. Theoretically, under the condition that the initial and final parameters of the thermal cycle remain unchanged, the higher the feedwater temperature and the more the number of regenerative stages, the higher the cycle efficiency. However, with the increase in the number of regenerative stages, the relative gain of the thermal efficiency gradually decreases, and the system complexity, equipment investment and maintenance costs increase significantly. Therefore, it is necessary to determine a reasonable number of regenerative stages according to the comprehensive technical economy of the unit. Modern steam turbines usually have a seven-stage or eight-stage feedwater regenerative system, and among them, setting four-stage regeneration in the low-pressure cylinder is a common configuration for conventional thermal power units and ultra-high-pressure nuclear power units.

[0003] For steam turbines in the million-kilowatt class, due to the large exhaust area, usually two double-flow low-pressure inner cylinders (cylinder A and cylinder B) are set as shown in Figure 1 -4, and the number of flow stages is generally 5 stages in both forward and reverse directions. The traditional extraction port arrangement method is to design cylinder A and cylinder B with different structures: two-stage extraction is set after the 1st stage and the 3rd stage in the low pressure of cylinder A, and two-stage extraction is set after the 2nd stage and the 4th stage in the low pressure of cylinder B, with a total of four-stage extraction. Although this structure has the advantages of convenient extraction port arrangement, large welding space in the cylinder, and easy manufacturing, it has obvious defects:

[0004] The structures of the two low-pressure cylinders are different and cannot be universal, increasing the costs of manufacturing, maintenance and spare parts management;

[0005] It cannot meet the unit requirements that the extraction steam after the 4th stage and the 5th stage in the low pressure enters the same combined low-pressure heater, because the extraction ports of these two stages are not on the same low-pressure inner cylinder, resulting in limited system design;

[0006] For units with larger power and three low-pressure cylinders, the traditional structure is difficult to evenly distribute the extraction steam volume of each low-pressure cylinder, affecting the economy and stability of the unit operation.

[0007] With the continuous improvement of the requirements of the power industry for unit efficiency, flexibility and cost control, the limitations of the existing extraction port arrangement structure of the low-pressure inner cylinder are becoming increasingly prominent, and there is an urgent need for an innovative design that can reasonably arrange multiple extraction ports on a single low-pressure inner cylinder, has a high degree of structural generalization and a wider application range. Summary of the Invention

[0008] The present invention aims to overcome the above-mentioned disadvantages of the prior art and provides a low-pressure inner cylinder of a steam turbine with a multi-stage steam extraction port structure.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A low-pressure inner cylinder of a steam turbine with a multi-stage steam extraction port structure includes a steam turbine side and a generator side. Separate low-pressure first-stage to fifth-stage diaphragm carrier rings are provided on the steam turbine side and the generator side of the low-pressure inner cylinder. By designing the diaphragm carrier rings on the steam turbine side and the generator side as an asymmetric structure, four steam extraction ports are formed on the same low-pressure inner cylinder. Among them, the low-pressure first-stage diaphragm carrier ring on the steam turbine side is a separate structure, the low-pressure second-stage and third-stage diaphragm carrier rings are an integral structure, the low-pressure first-stage and second-stage diaphragm carrier rings on the generator side are an integral structure, the low-pressure third-stage diaphragm carrier ring is a separate structure, and the low-pressure fourth-stage diaphragm carrier rings on both the steam turbine side and the generator side are separate structures and are symmetrically arranged. The low-pressure inner cylinder is also provided with baffle plates for isolating the steam after different stages.

[0011] Furthermore, on the steam turbine side, through the separate low-pressure first-stage diaphragm carrier ring and the integral low-pressure second- and third-stage diaphragm carrier rings, two steam extraction chambers are formed after the low-pressure first stage and the third stage. On the generator side, through the integral low-pressure first- and second-stage diaphragm carrier rings and the separate low-pressure third-stage diaphragm carrier ring, two steam extraction chambers are formed after the low-pressure second stage and the third stage.

[0012] Furthermore, the low-pressure fourth-stage diaphragm carrier rings on both the steam turbine side and the generator side are separate structures, and steam extraction chambers are respectively formed after the low-pressure fourth stage on the steam turbine side and the generator side, so that a total of four steam extraction chambers are formed on a single low-pressure inner cylinder.

[0013] Furthermore, the steam extraction pipes after the low-pressure first stage are all arranged on the steam turbine side, the steam extraction pipes after the low-pressure second stage are all arranged on the generator side, and the steam extraction pipes after the low-pressure third stage and the fourth stage are arranged diagonally on the steam turbine side and the generator side.

[0014] Furthermore, two steam extraction pipes after the low-pressure third stage and two steam extraction pipes after the low-pressure fourth stage are arranged on both the steam turbine side and the generator side to reduce the steam extraction asymmetry.

[0015] Furthermore, the baffle plates include a baffle plate for the steam extraction port after the low-pressure third stage and a baffle plate for the steam extraction port after the low-pressure fourth stage, both of which are welded by a U-shaped bent plate and an end plate.

[0016] Furthermore, the baffle plate for the steam extraction port after the low-pressure third stage is arranged in the steam extraction chamber after the low-pressure third stage to isolate the steam after the low-pressure fourth stage and prevent it from entering the steam extraction port after the low-pressure third stage.

[0017] Further, the baffle for the extraction port after the 4th stage of the low-pressure cylinder is arranged in the extraction chamber after the 4th stage of the low-pressure cylinder to isolate the steam after the 3rd stage of the low-pressure cylinder and prevent it from entering the extraction port after the 4th stage of the low-pressure cylinder.

[0018] Further, the low-pressure inner cylinder includes an upper half and a lower half, and a complete extraction chamber structure is formed through the cooperation of the upper and lower cylinder bodies.

[0019] Further, the low-pressure inner cylinder is designed with a structure that allows different modules to be borrowed from each other, which is applicable to units with integral low-pressure heaters and high-power units with three low-pressure cylinders, realizing the average distribution of the extraction steam volume.

[0020] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0021] Through the innovative design of the low-pressure inner cylinder structure, the present invention significantly improves the versatility, applicability and economy of the low-pressure cylinder of the steam turbine:

[0022] Generalization and modularization of the structure: Through the asymmetric combination of the diaphragm carrier rings on the turbine side and the motor side (the 1st stage diaphragm carrier ring is separately arranged on the turbine side and the 2nd and 3rd stages are integrated, and the 1st and 2nd stage diaphragm carrier rings are integrated on the motor side and the 3rd stage is separately arranged), combined with the symmetrically arranged 4th stage diaphragm carrier ring, four-stage extraction ports are integrated on a single low-pressure inner cylinder, enabling different low-pressure cylinder modules to be borrowed from each other, completely changing the drawback of different traditional A and B cylinder structures, and significantly reducing the manufacturing, maintenance and spare parts management costs.

[0023] Expansion of the applicable range: The unique layout of the extraction chamber and the arrangement of the diagonal extraction pipes support the arrangement of extraction ports at adjacent levels (such as after the 3rd and 4th stages) on the same low-pressure inner cylinder, perfectly adapting to units that require integral low-pressure heaters; at the same time, the symmetric and balanced extraction structure can ensure the average distribution of the extraction steam volume of high-power units with three low-pressure cylinders, solving the application limitations of traditional structures in multi-cylinder configurations.

[0024] Improvement of reliability and economy: The baffle (the baffle for the extraction ports after the 3rd and 4th stages) welded by the U-shaped bent plate and the end plate effectively isolates the steam flows at different levels, avoids cross-flow interference, and ensures the stability of the extraction parameters; the design of only adding one extraction chamber on one side realizes the compact arrangement of four-stage extraction ports on the premise of ensuring the welding space and manufacturing feasibility inside the cylinder, providing a structural guarantee for the high-efficiency regenerative cycle of high-parameter and high-power steam turbines, and significantly improving the thermal economy and operation reliability of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a sectional view of the traditional A low-pressure inner cylinder with two-stage extraction ports;

[0026] Figure 2 is Figure 1The top-down sectional view;

[0027] Figure 3 is the sectional view of the traditional B low-pressure inner cylinder with two-stage extraction ports;

[0028] Figure 4 is Figure 3 The top-down sectional view;

[0029] Figure 5 is the sectional view of the low-pressure inner cylinder of the present invention with a four-stage extraction port structure;

[0030] Figure 6 is Figure 5 The top-down sectional view;

[0031] Figure 7 is the schematic diagram of the baffle structure of the rear extraction port of the 3rd stage of the low-pressure of the present invention;

[0032] Figure 8 is the sectional view of the baffle of the rear extraction port of the 3rd stage of the low-pressure of the present invention;

[0033] Figure 9 is the schematic diagram of the baffle structure of the rear extraction port of the 4th stage of the low-pressure of the present invention;

[0034] Figure 10 is the sectional view of the baffle of the rear extraction port of the 4th stage of the low-pressure of the present invention.

[0035] Markings in the figure:

[0036] 1 - Upper half of A low-pressure inner cylinder, 2 - Lower half of A low-pressure inner cylinder, 3 - Diaphragm carrier ring of the 1st stage of the low-pressure, 4 - Diaphragm carrier ring of the 2nd stage of the low-pressure, 5 - Diaphragm carrier ring of the 3rd stage of the low-pressure, 6 - Diaphragm carrier ring of the 4th stage of the low-pressure, 7 - Diaphragm carrier ring of the 5th stage of the low-pressure, 8 - Rear extraction pipe of the 1st stage of the low-pressure, 9 - Rear extraction pipe of the 3rd stage of the low-pressure, 10 - Upper half of B low-pressure inner cylinder, 11 - Lower half of B low-pressure inner cylinder, 12 - Rear extraction pipe of the 2nd stage of the low-pressure, 13 - Rear extraction pipe of the 4th stage of the low-pressure, 14 - Upper half of the multi-stage extraction low-pressure inner cylinder, 15 - Lower half of the multi-stage extraction low-pressure inner cylinder, 16 - Baffle of the rear extraction port of the 3rd stage of the low-pressure, 17 - Baffle of the rear extraction port of the 4th stage of the low-pressure. Detailed implementation mode

[0037] The present invention will be described in detail below with reference to the accompanying drawings.

[0038] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] In this embodiment, as Figure 5As shown in FIGS. -10, a low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure includes a turbine side and a generator side. The turbine side and the generator side of the low-pressure inner cylinder are respectively provided with low-pressure first-stage to fifth-stage diaphragm carrier rings. By designing the diaphragm carrier rings on the turbine side and the generator side as an asymmetric structure, four extraction ports are formed on the same low-pressure inner cylinder. Among them, the low-pressure first-stage diaphragm carrier ring on the turbine side is a separate structure, the low-pressure second-stage and third-stage diaphragm carrier rings are an integral structure, the low-pressure first-stage and second-stage diaphragm carrier rings on the generator side are an integral structure, the low-pressure third-stage diaphragm carrier ring is a separate structure, and the low-pressure fourth-stage diaphragm carrier rings on the turbine side and the generator side are both separate structures and symmetrically arranged. The low-pressure inner cylinder is also provided with a baffle for isolating the steam after different stages.

[0040] The low-pressure inner cylinder is divided into a turbine side and a generator side, and the diaphragm carrier rings of each stage are asymmetrically distributed:

[0041] Turbine side: The first-stage diaphragm carrier ring is separately provided, and the second-stage and third-stage (5) diaphragm carrier rings are welded into an integral structure;

[0042] Generator side: The first-stage and second-stage diaphragm carrier rings are welded into an integral structure, and the third-stage diaphragm carrier ring is separately provided;

[0043] The fourth-stage diaphragm carrier rings on the turbine side and the generator side are both separately provided and symmetrically arranged;

[0044] A baffle is welded in the extraction chamber of the inner cylinder, which is formed by welding a U-shaped bent plate and an end plate, and is respectively located near the third and fourth extraction ports.

[0045] Specifically: Steam enters the low-pressure inner cylinder from the turbine side. After doing work through the first-stage diaphragm carrier ring, part of the steam is extracted through the first-stage extraction chamber on the turbine side. The remaining steam flows through the integral second-stage and third-stage diaphragm carrier rings to form an extraction chamber after the third stage. The steam on the generator side forms an extraction chamber after the second stage after passing through the integral first-stage and second-stage diaphragm carrier rings, and then does work through the separate third-stage diaphragm carrier ring to form another extraction chamber after the third stage. The symmetrically arranged fourth-stage diaphragm carrier rings respectively form the fourth-stage extraction chambers on both sides. The baffle blocks the steam between adjacent stages through the U-shaped bent plate, and the end plate is fixed to the cylinder wall to isolate the steam flow in different extraction chambers.

[0046] The asymmetric diaphragm carrier ring design enables the turbine side and the generator side to respectively form 2 extraction chambers, and the symmetric fourth-stage diaphragm carrier rings add 2 more chambers, finally integrating four extraction ports in a single inner cylinder. The baffle prevents steam from flowing through, ensuring the purity of the extracted steam. This structure breaks the traditional differential design of cylinders A and B, realizes module generalization, and reduces the manufacturing and maintenance costs.

[0047] Furthermore, on the turbine side, a separate low-pressure first-stage diaphragm carrier ring and an integral low-pressure second- and third-stage diaphragm carrier rings form two extraction chambers after the first stage and after the third stage; on the generator side, an integral low-pressure first- and second-stage diaphragm carrier ring and a separate low-pressure third-stage diaphragm carrier ring form two extraction chambers after the second stage and after the third stage.

[0048] Turbine side: An extraction chamber is formed between the separate first-stage diaphragm carrier ring and the integral second- and third-stage diaphragm carrier rings after the first stage; an extraction chamber is formed between the integral second- and third-stage diaphragm carrier rings and the fourth-stage diaphragm carrier ring after the third stage.

[0049] Generator side: An extraction chamber is formed between the integral first- and second-stage diaphragm carrier rings and the separate third-stage diaphragm carrier ring after the second stage; an extraction chamber is formed between the separate third-stage diaphragm carrier ring and the fourth-stage diaphragm carrier ring after the third stage.

[0050] Specifically: On the turbine side, the first-stage diaphragm carrier ring is independently arranged, and an annular extraction chamber is formed between its outlet and the inlet of the second-stage diaphragm carrier ring, and the steam is led out through the low-pressure first-stage extraction pipe; there is no independent chamber between the integral second- and third-stage diaphragm carrier rings. After the steam does work in the third stage, it is led out through the low-pressure third-stage extraction pipe from the chamber between the outlet of the third stage and the inlet of the fourth stage. On the generator side, there is no independent chamber between the integral first- and second-stage diaphragm carrier rings. After the steam does work in the second stage, it is led out through the low-pressure second-stage extraction pipe from the chamber between the outlet of the second stage and the inlet of the third stage; an extraction chamber is formed between the outlet of the separate third-stage diaphragm carrier ring and the inlet of the fourth stage after the third stage.

[0051] Through the "separate-integral" combination of the diaphragm carrier rings, two extraction chambers are respectively constructed on the turbine side and the generator side, without relying on the traditional differential design of cylinders A and B, enabling a single inner cylinder to have multi-stage extraction capacity, laying a structural foundation for the subsequent integration of four extraction ports.

[0052] Furthermore, the low-pressure fourth-stage diaphragm carrier ring is a separate structure on both the turbine side and the generator side, forming extraction chambers after the low-pressure fourth stage on the turbine side and the generator side respectively, thus cumulatively forming four extraction chambers on a single low-pressure inner cylinder.

[0053] The fourth-stage diaphragm carrier ring is an independent structure on both the turbine side and the generator side. An annular chamber is formed between its inlet and the outlet of the third-stage diaphragm carrier ring and between its outlet and the inlet of the fifth-stage diaphragm carrier ring, serving as the extraction chamber after the fourth stage on the turbine side and the generator side respectively.

[0054] After the steam flows through the third-stage diaphragm carrier ring, it enters the chamber (turbine side / generator side) before the fourth-stage diaphragm carrier ring. Part of the steam is led out through the low-pressure fourth-stage extraction pipe from the symmetric extraction chambers after the fourth stage on both sides, and the remaining steam enters the fourth stage to do work.

[0055] The symmetrically arranged 4th-stage partition retaining ring forms independent extraction chambers on both sides, which cooperate with the chambers behind the 1st and 3rd stages on the turbine side and the 2nd and 3rd stages on the generator side to cumulatively form four extraction ports. This design breaks through the limitation of traditional single cylinders that can only arrange two-stage extractions, supports extractions at adjacent stages (such as behind the 3rd and 4th stages) on the same inner cylinder, and is applicable to units that require integral low-pressure heaters.

[0056] Furthermore, the extraction pipes behind the 1st stage of the low-pressure section are all arranged on the turbine side, the extraction pipes behind the 2nd stage of the low-pressure section are all arranged on the generator side, and the extraction pipes behind the 3rd and 4th stages of the low-pressure section are arranged diagonally on the turbine side and the generator side.

[0057] Furthermore, two extraction pipes behind the 3rd stage of the low-pressure section and two extraction pipes behind the 4th stage of the low-pressure section are arranged on the turbine side and the generator side respectively to reduce the extraction asymmetry.

[0058] Extraction pipes behind the 1st stage of the low-pressure section: 2 pieces, both vertically welded to the cylinder wall of the extraction chamber behind the 1st stage on the turbine side;

[0059] Extraction pipes behind the 2nd stage of the low-pressure section: 2 pieces, both vertically welded to the cylinder wall of the extraction chamber behind the 2nd stage on the generator side;

[0060] Extraction pipes behind the 3rd stage and the 4th stage of the low-pressure section: 2 pieces each, respectively welded to the cylinder walls on the turbine side and the generator side at a 45° oblique angle, showing a diagonal distribution (for example, the extraction pipe of the 3rd stage is arranged above on the turbine side, and the extraction pipe of the 4th stage is arranged below on the generator side, and vice versa).

[0061] The extraction pipes are directionally arranged according to the chamber positions: the steam behind the 1st stage is only led out from the turbine side, and the steam behind the 2nd stage is only led out from the generator side to avoid the intersection of the extraction pipelines on both sides; the extraction pipes of the 3rd and 4th stages are diagonally distributed to balance the extraction amounts on both sides. When the steam passes through the extraction pipes, the diagonal layout reduces the difference in flow resistance and lowers the extraction asymmetry.

[0062] The targeted extraction pipe layout (concentrated on the same side + diagonal balance) solves the problem of interference of multi-stage extraction pipelines, ensures the symmetry of the four-stage extractions on a single inner cylinder, and provides structural support for the average distribution of the extraction amounts of the three low-pressure cylinder units.

[0063] Furthermore, the baffle plates include the baffle plates for the extraction ports behind the 3rd stage of the low-pressure section and the baffle plates for the extraction ports behind the 4th stage of the low-pressure section, both of which are welded by U-shaped bent plates and end plates.

[0064] Furthermore, the baffle plate for the extraction port behind the 3rd stage of the low-pressure section is arranged in the extraction chamber behind the 3rd stage of the low-pressure section to isolate the steam behind the 4th stage of the low-pressure section and prevent it from entering the extraction port behind the 3rd stage of the low-pressure section.

[0065] Furthermore, the baffle plate for the extraction port behind the 4th stage of the low-pressure section is arranged in the extraction chamber behind the 4th stage of the low-pressure section to isolate the steam behind the 3rd stage of the low-pressure section and prevent it from entering the extraction port behind the 4th stage of the low-pressure section.

[0066] Low-pressure third-stage extraction port baffle: The opening of the U-shaped bent plate faces the fourth-stage diaphragm carrier ring, and the end plate is welded to the cylinder wall of the third-stage extraction chamber near the fourth stage to form an isolation barrier.

[0067] Low-pressure fourth-stage extraction port baffle: The opening of the U-shaped bent plate faces the third-stage diaphragm carrier ring, and the end plate is welded to the cylinder wall of the fourth-stage extraction chamber near the third stage.

[0068] When the steam flows through the third-stage extraction chamber, the U-shaped bent plate of the baffle blocks the steam from the fourth-stage direction, forcing the steam after the third stage to flow out only from the low-pressure third-stage extraction pipe; similarly, the baffle blocks the steam from the third-stage direction from entering the fourth-stage extraction chamber, ensuring that the steam after the fourth stage is led out only from the low-pressure fourth-stage extraction pipe.

[0069] The baffle avoids the mixing of steam in adjacent stages through physical isolation, solves the problem of cross-flow caused by the proximity of extraction ports in the traditional structure, ensures the stability of extraction parameters, and improves the efficiency of the regenerative system.

[0070] Furthermore, the low-pressure inner cylinder includes an upper half and a lower half, and a complete extraction chamber structure is formed through the cooperation of the upper and lower cylinder bodies.

[0071] Component settings and connection relationships:

[0072] The low-pressure inner cylinder is divided into an upper half and a lower half, which are connected by cylinder flange bolts. The upper half of the cylinder body is provided with the upper half of the extraction chamber, and the lower half of the cylinder body is provided with the lower half of the extraction chamber. After the cylinders are combined, a complete annular extraction chamber is formed; the diaphragm carrier ring is fixed in the carrier ring grooves of the upper and lower cylinder bodies through bolts.

[0073] During the operation of the unit, the upper and lower cylinder bodies are closely fitted under the steam pressure, and the diaphragm carrier ring is fixed in the cylinder body groove, forming a separation between the steam flow path and the extraction chamber. The extraction chamber is formed by splicing the grooves of the upper and lower cylinder bodies, ensuring that the steam is evenly distributed in the chamber and led out through the extraction pipe.

[0074] The modular design of the upper and lower cylinder bodies and the groove fixation of the diaphragm carrier ring simplify the manufacturing process of the inner cylinder. Only one extraction chamber is added on one side, and a compact layout is achieved on the premise of ensuring the welding space, improving the manufacturing feasibility.

[0075] Furthermore, the low-pressure inner cylinder is designed with a structure that allows different modules to be borrowed from each other, which is applicable to units equipped with integral low-pressure heaters and high-power units with three low-pressure cylinders, realizing the average distribution of extraction steam volume.

[0076] On the turbine side, the "single first stage + integrated second and third stages" and on the motor side, the "integrated first and second stages + single third stage" form an asymmetric diaphragm carrier ring combination. Together with the symmetric fourth-stage diaphragm carrier ring and the diagonal extraction steam pipes, a universal inner cylinder module is constituted. The extraction steam port positions and diaphragm carrier ring interfaces of each module are unified and can be used interchangeably.

[0077] When applied to a double-low-pressure cylinder unit, both inner cylinder modules can independently achieve four-stage extraction steam without distinguishing between cylinder A and cylinder B; when applied to a triple-low-pressure cylinder unit, the extraction steam pipe layout of each module is balanced, and the extraction steam volume can be evenly distributed. The adjacent-stage extraction steam required for the integral low-pressure heater (such as after the third and fourth stages) can be obtained within the same module without cross-cylinder connection.

[0078] The collaborative design of the asymmetric combination and the symmetric layout endows the inner cylinder module with both multi-stage extraction steam capacity and universality, completely solving the adaptability problem caused by the cylinder body differentiation in the traditional structure, supporting various unit configurations (double cylinder / triple cylinder, integral heater), and significantly expanding the application scenarios.

[0079] Through the asymmetric distribution of the diaphragm carrier ring, the directional layout of the extraction steam pipes, and the isolation design of the baffle plates, the above-mentioned embodiments construct a compact structure with four extraction steam ports on a single low-pressure inner cylinder. The setting principles of each component are all centered around "universalization, equalization, and reliability": the asymmetric diaphragm carrier ring realizes efficient chamber division, the diagonal extraction steam pipes balance the flow resistance, the baffle plates eliminate the risk of cross-flow, and the modularization of the upper and lower half cylinder bodies reduces the manufacturing difficulty. It solves the adaptability and economic defects of the traditional structure and provides an innovative technical solution for the regenerative system of high-parameter steam turbines.

[0080] The above are only the preferred embodiments of the invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure, including a steam turbine side and a motor side, characterized in that: On the turbine side and the generator side of the low-pressure inner cylinder, there are respectively arranged diaphragm carrier rings for the 1st to 5th low-pressure stages. By designing the diaphragm carrier rings on the turbine side and the generator side as an asymmetric structure, four-stage extraction ports are formed on the same low-pressure inner cylinder. Among them, the diaphragm carrier ring for the 1st low-pressure stage on the turbine side is a separate structure, the diaphragm carrier rings for the 2nd and 3rd low-pressure stages are an integral structure, the diaphragm carrier rings for the 1st and 2nd low-pressure stages on the generator side are an integral structure, the diaphragm carrier ring for the 3rd low-pressure stage is a separate structure, and the diaphragm carrier ring for the 4th low-pressure stage is a separate structure on both the turbine side and the generator side and is symmetrically arranged. The low-pressure inner cylinder is also provided with baffle plates for isolating the steam after different stages.

2. The low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to claim 1, characterized in that: On the turbine side, through the separate diaphragm carrier ring for the 1st low-pressure stage and the integral diaphragm carrier rings for the 2nd and 3rd low-pressure stages, two extraction chambers are formed after the 1st low-pressure stage and after the 3rd low-pressure stage. On the generator side, through the integral diaphragm carrier rings for the 1st and 2nd low-pressure stages and the separate diaphragm carrier ring for the 3rd low-pressure stage, two extraction chambers are formed after the 2nd low-pressure stage and after the 3rd low-pressure stage.

3. The low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to claim 2, characterized in that: The diaphragm carrier ring for the 4th low-pressure stage is a separate structure on both the turbine side and the generator side, and extraction chambers are respectively formed after the 4th low-pressure stage on the turbine side and the generator side, so that four-stage extraction chambers are cumulatively formed on a single low-pressure inner cylinder.

4. A low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to claim 3, characterized in that: The extraction pipes after the 1st low-pressure stage are all arranged on the turbine side, the extraction pipes after the 2nd low-pressure stage are all arranged on the generator side, and the extraction pipes after the 3rd and 4th low-pressure stages are arranged diagonally on the turbine side and the generator side.

5. The low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to claim 4, characterized in that: There are 2 extraction pipes after the 3rd low-pressure stage and 2 extraction pipes after the 4th low-pressure stage arranged on both the turbine side and the generator side to reduce the extraction asymmetry.

6. The low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to claim 1, characterized in that: The baffle plates include the baffle plate for the extraction port after the 3rd low-pressure stage and the baffle plate for the extraction port after the 4th low-pressure stage, and are both welded by a U-shaped bent plate and an end plate.

7. The low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to claim 6, characterized in that: The baffle plate for the extraction port after the 3rd low-pressure stage is arranged in the extraction chamber after the 3rd low-pressure stage to isolate the steam after the 4th low-pressure stage and prevent it from entering the extraction port after the 3rd low-pressure stage.

8. A low-pressure inner cylinder of a steam turbine with a multi-stage steam extraction port structure according to claim 6, characterized in that: The baffle plate for the extraction port after the 4th low-pressure stage is arranged in the extraction chamber after the 4th low-pressure stage to isolate the steam after the 3rd low-pressure stage and prevent it from entering the extraction port after the 4th low-pressure stage.

9. The low-pressure inner cylinder of a steam turbine with a multi-stage steam extraction port structure according to claim 1, characterized in that: The low-pressure inner cylinder includes an upper half and a lower half, and a complete extraction chamber structure is formed through the cooperation of the upper and lower cylinder bodies.

10. A low-pressure inner cylinder of a steam turbine with a multi-stage extraction port structure according to any one of claims 1-9, characterized in that: The low-pressure inner cylinder is designed as a structure where different modules can be borrowed from each other, and is applicable to units with integral low-pressure heaters and high-power units with three low-pressure cylinders to achieve an average distribution of the extraction steam volume.

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