Turbine medium-pressure rotor structure and medium-pressure cylinder exhaust steam parameter control method

Abstract

The invention discloses a steam turbine medium-pressure rotor structure and a medium-pressure cylinder exhaust steam parameter control method, and belongs to the technical field of steam turbine combined heat and power generation. The steam turbine medium-pressure rotor structure comprises a medium-pressure cylinder, a main shaft, a hollow rotor, a clutch, a variable-speed transmission device, a steam extraction opening and a control system. The main shaft is arranged in the medium-pressure cylinder, and a front-stage moving blade group is arranged on the main shaft; the hollow rotor coaxially sleeves the rear part of the main shaft and is provided with a rear-stage moving blade group; the clutch and the variable-speed transmission device are arranged outside the medium-pressure cylinder, the clutch controls the hollow rotor to be connected with the main shaft, and the variable-speed transmission device independently drives the hollow rotor to adjust the speed; the steam extraction opening is formed in the downstream of the rear-stage moving blade group; the control system is connected with the clutch and the variable-speed transmission device; the working amount of the rear-stage movable blade set is controlled by adjusting the rotating speed of the hollow rotor, continuous and accurate adjustment of steam exhaust parameters of the medium-pressure cylinder is achieved, steam impact harm of the rotating partition plate is eliminated, high-quality heat supply is achieved, no additional loss exists in the pure condensing working condition, and the high engineering practical value is achieved.

Description

Technical Field

[0001] This invention relates to a steam turbine intermediate-pressure rotor structure and a method for controlling the exhaust parameters of the intermediate-pressure cylinder, belonging to the field of steam turbine cogeneration technology. Background Technology

[0002] In combined heat and power (CHP) units, the intermediate-pressure cylinder is typically equipped with an adjustable steam extraction port to meet industrial or heating demands. There are two main traditional regulation schemes:

[0003] The first type is the rotating diaphragm extraction steam structure. Its working principle involves rotating a flat, disc-shaped baffle to change the overlap area between its opening and the opening on the fixed casing, thereby throttling and adjusting the steam flow. However, when high-pressure, high-temperature steam impacts the partially opened rotating diaphragm plane at high speed, it generates severe vertical rebound and turbulence. This rebounding steam directly acts on the outlet area of ​​the upstream moving blades, forming unstable periodic impact loads. Under long-term operation, especially under conditions of frequent deep grid peak shaving, this high-frequency fretting impact will cause fretting wear at the blade roots and induce high-cycle fatigue cracks, seriously threatening unit safety.

[0004] The second method is to extract steam by drilling holes in the medium and low pressure connecting pipe. This method directly extracts steam from the medium and low pressure connecting pipe. Although the structure is simple, the steam has already flowed through the later stages of the medium pressure cylinder (such as the 8th and 9th stages) and done sufficient work, resulting in a significant reduction in its pressure and temperature. This leads to lower heating parameters and fails to meet the demand for high-quality heating.

[0005] In addition, existing technologies include NCB (condensing extraction back-end) type steam turbine units, which disconnect the entire low-pressure cylinder via a clutch to achieve direct heating from the exhaust steam of the intermediate-pressure cylinder. However, this technology requires the generator to be located at the turbine head, which changes the conventional layout of traditional thermal power units, increases the complexity of plant design and equipment layout, and is not conducive to the retrofitting of existing power plants. Furthermore, its regulation target is the entire low-pressure cylinder, making it impossible to perform precise control of the downstream stages of the intermediate-pressure cylinder.

[0006] Therefore, there is an urgent need for a new structure that can fundamentally eliminate vertical steam impact, achieve high-parameter steam extraction, and is easy to modify. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a turbine intermediate-pressure rotor structure and an intermediate-pressure cylinder exhaust parameter control method, which can make the intermediate-pressure cylinder exhaust parameters meet the heating requirements and operate safely and reliably.

[0008] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0009] In a first aspect, the present invention provides a steam turbine intermediate-pressure rotor structure, comprising:

[0010] Medium pressure cylinder;

[0011] The main shaft is located inside the intermediate pressure cylinder, and a front-stage moving blade assembly is sequentially arranged along the axial direction on the main shaft;

[0012] A hollow rotor is coaxially sleeved on the rear outer side of the main shaft, and a rear-stage moving blade assembly is provided on the hollow rotor;

[0013] A cylinder body through-hole structure is provided at the exhaust end of the intermediate pressure cylinder to lead the rear end of the main shaft and the rear end of the hollow rotor to the outside of the cylinder body;

[0014] The clutch, located outside the intermediate pressure cylinder and connected to the rear end of the main shaft, is used to control the power connection state between the hollow rotor and the main shaft.

[0015] A speed-changing transmission device is located outside the intermediate pressure cylinder and is connected between the main shaft, the clutch and the rear end of the hollow rotor, for driving the hollow rotor to rotate at an adjustable speed.

[0016] The steam extraction port is located in the exhaust area of ​​the intermediate-pressure cylinder downstream of the rear-stage moving blade assembly, and is used to connect to the external heating network;

[0017] The control system is signal-connected to the clutch and the transmission device, and is used to control the engagement and disengagement of the clutch according to the heating demand, and to control the transmission device to adjust the speed of the hollow rotor.

[0018] Furthermore, the front-stage moving blade group includes 1st to 7th stage moving blades, and the rear-stage moving blade group includes 8th and 9th stage moving blades.

[0019] Furthermore, it also includes a built-in support bearing, which is disposed between the front-stage moving blade assembly and the rear-stage moving blade assembly to support the front end of the hollow rotor; the built-in support bearing is a tilting pad bearing or a multi-oil wedge bearing, and is provided with a high-temperature resistant lubricating oil pipeline.

[0020] Furthermore, the connection sequence between the clutch and the transmission device is as follows: the rear end of the main shaft is sequentially connected to the clutch, the transmission device, and the rear end of the hollow rotor;

[0021] Alternatively, the rear end of the main shaft is sequentially connected to the transmission device, the clutch, and the rear end of the hollow rotor.

[0022] Furthermore, the speed transmission device is a gearbox or a variable frequency drive motor.

[0023] Furthermore, the clutch is a synchronous self-shifting clutch or an SSS clutch.

[0024] Furthermore, a sealing device is provided between the hollow rotor and the main shaft to prevent steam from leaking through the gap between them.

[0025] In a second aspect, the present invention provides a steam turbine, including the intermediate-pressure rotor structure of the steam turbine as described in any one of the first aspects.

[0026] Thirdly, the present invention provides a method for controlling the exhaust parameters of the intermediate-pressure cylinder of the steam turbine described in the second aspect, comprising:

[0027] Receive external heating load instructions and determine the required target parameters for intermediate pressure cylinder exhaust steam;

[0028] Based on the preset "hollow rotor speed - exhaust parameters" characteristic model, calculate the hollow rotor target speed corresponding to the intermediate pressure cylinder exhaust target parameters;

[0029] Determine the deviation between the target speed of the hollow rotor and the rated speed of the spindle:

[0030] If the target speed of the hollow rotor is equal to the rated speed of the main shaft, then the clutch is controlled to close, so that the hollow rotor rotates synchronously with the main shaft;

[0031] If the target speed of the hollow rotor is lower than the rated speed of the main shaft, the clutch is disengaged and the hollow rotor is driven to the target speed through the speed transmission device.

[0032] The exhaust parameters of the intermediate pressure cylinder are monitored in real time and compared with the target exhaust parameters. The rotational speed of the hollow rotor is corrected in a closed loop based on the deviation value until the exhaust parameters stabilize within the target range.

[0033] Furthermore, when the target speed of the hollow rotor is lower than the rated speed of the spindle, the speed adjustment range of the hollow rotor is 500 rpm to 2800 rpm.

[0034] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0035] 1. This invention provides a turbine intermediate-pressure rotor structure and an intermediate-pressure cylinder exhaust parameter control method. Both the clutch and the speed transmission device are located outside the intermediate-pressure cylinder, completely replacing the traditional rotating baffle structure located inside the cylinder. When the rotating baffle is partially open, high-temperature, high-pressure steam impacts the baffle plane at high speed vertically, generating severe rebound turbulence. Long-term operation can easily lead to fretting wear at the blade root and high-cycle fatigue cracks. This invention eliminates the in-cylinder throttling adjustment component, fundamentally eliminating the risk of vertical steam impact and significantly improving unit operating safety and blade life.

[0036] 2. The hollow rotor of this invention is equipped with a rear-stage moving blade assembly, which can be separated from the main shaft by a clutch. The speed transmission device can independently drive the hollow rotor to operate at a speed lower than the rated speed. When the hollow rotor decelerates, the work extracted from the steam by the rear-stage moving blade assembly decreases, and the enthalpy drop of the steam decreases as it flows through the later stages. This maintains the exhaust pressure and temperature of the intermediate-pressure cylinder at a relatively high level, close to the inlet steam parameters of the intermediate-pressure cylinder, thus meeting the high-parameter heating requirements for industrial or heating applications and solving the problem of low extraction steam parameters in traditional connecting pipe systems.

[0037] 3. The control system of this invention can selectively control the hollow rotor to rotate synchronously with the main shaft or to rotate independently at a controlled speed, depending on the heating demand. In pure condensing mode, the clutch is engaged, the hollow rotor rotates synchronously with the main shaft, the downstream moving blade assembly performs normal work, the steam expands fully, and the unit's heat consumption rate is comparable to the original design, with no additional energy loss. In heating mode, the hollow rotor can be independently speed-regulated, optimizing the rotational speed according to the heat load demand, achieving on-demand energy distribution and avoiding energy waste.

[0038] 4. This invention explicitly defines that both the clutch and the transmission device are located outside the intermediate-pressure cylinder. This arrangement keeps the precision transmission components away from the high-temperature, high-pressure, and high-humidity environment inside the intermediate-pressure cylinder, avoiding the deteriorating effects of high-temperature steam on the lubricating oil, seals, and transmission mechanism, significantly reducing the equipment failure rate. At the same time, it facilitates daily inspection, maintenance, and replacement, and is particularly suitable for the flexible retrofitting of existing thermal power units.

[0039] 5. The control system of this invention is signal-connected to the clutch and transmission device, and can adjust the speed of the hollow rotor in real time according to the heating demand. Combined with the control method described in claim 11, through the preset "speed-exhaust parameter" characteristic model and closed-loop correction control, continuous and precise adjustment of exhaust pressure can be achieved. The response speed is far superior to the mechanical throttling adjustment of traditional rotating baffles, and it can quickly adapt to the operating requirements of deep peak shaving of the power grid and heat load fluctuations.

[0040] 6. This invention coaxially mounts the hollow rotor on the outer rear part of the main shaft, and the clutch and speed transmission device are both arranged outside the cylinder body at the exhaust end of the intermediate pressure cylinder. There is no need to move the generator position, and the shaft system layout and plant structure of the traditional thermal power unit are not changed. The original intermediate pressure cylinder space can be directly used for modification, which is highly adaptable to existing power plants and avoids the complexity of plant design and equipment layout caused by the need to place the generator at the turbine head in NCB (condensing extraction back) type units. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of a steam turbine intermediate pressure rotor structure provided in an embodiment of the present invention.

[0042] In the diagram: 1. Intermediate-pressure cylinder; 2. Main shaft; 3. Stages 1-7 moving blades; 4. Hollow rotor; 5. Stage 8 moving blade; 6. Stage 9 moving blade; 7. Built-in support bearing; 8. Cylinder body through-hole structure; 9. Clutch; 10. Speed ​​transmission device; 11. Steam extraction port; 12. Control system; 13. Rear end of intermediate-pressure rotor main shaft; 14. Rear end of hollow rotor; 15. Sealing device; 16. High-temperature resistant lubricating oil pipeline; 17. Connecting pipe between intermediate and low-pressure cylinders; 18. Low-pressure cylinder steam inlet regulating valve; 19. Heating steam extraction regulating valve; 20. First station of heating network; 21. Low-pressure cylinder; 22. Low-pressure rotor; 23. Generator; 24. Generator rotor; 25. Rigid coupling. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] Example 1: Retrofitting a 300MW-class generating unit;

[0045] Taking a 300MW subcritical cogeneration unit as an example, the original design of the compressor cylinder had seven stages of moving blades, with a rotating baffle steam extraction port after the seventh stage for winter heating. Due to long-term operation, the root of the seventh-stage moving blade has experienced fretting wear, posing a safety hazard. Simultaneously, with increasing heat user demand, the original steam extraction parameters are no longer sufficient. Therefore, the intermediate-pressure rotor structure of the turbine provided in this embodiment is used for modification.

[0046] Step 1: Unit structural modification;

[0047] like Figure 1 As shown, the original rotating partition and the original rotors of stages 8 and 9 are removed. The intermediate-pressure rotor structure of the turbine described in this embodiment is then installed:

[0048] Retain the original main shaft 2 and the first to seventh stage moving blades 3;

[0049] A hollow rotor 4 is coaxially sleeved on the outer rear part of the main shaft 2, and the eighth stage moving blade 5 and the ninth stage moving blade 6 are installed on the hollow rotor 4.

[0050] An internal support bearing 7 is installed between the 7th and 8th stage moving blades, with a tilting pad structure and a high-temperature resistant lubricating oil pipeline 16.

[0051] A cylinder body through-out structure 8 is provided at the exhaust end of the intermediate pressure cylinder to lead the rear end 13 of the main shaft and the rear end 14 of the hollow rotor to the outside of the cylinder body.

[0052] A clutch 9 (using an SSS clutch) and a transmission device 10 (using a gearbox with a reduction ratio of 2:1) are connected sequentially outside the cylinder block.

[0053] A steam extraction port 11 is installed in the exhaust area of ​​the intermediate pressure cylinder downstream of the 9th stage moving blade, and connected to the first station of the heating network;

[0054] Connect the clutch 9 and the transmission device 10 to the unit's DCS control system 12.

[0055] In the modified unit, the main shaft 2 is connected to the low-pressure rotor 22 via a rigid coupling 25. The exhaust steam from the intermediate-pressure cylinder enters the low-pressure cylinder 21 through the intermediate-low-pressure cylinder connecting pipe 17 and the low-pressure cylinder inlet steam regulating valve 18 to continue doing work. During heating, the steam drawn from the extraction port 11 enters the first station 20 of the heating network through the heating extraction steam regulating valve 19.

[0056] Step 2: Operating mode and parameters;

[0057] 1. Pure condensation mode (summer);

[0058] Control system 12 receives pure condensate operation command;

[0059] When the clutch 9 is engaged, the hollow rotor 4 rotates synchronously with the main shaft 2 at 3000 rpm.

[0060] The 8th and 9th stage moving blades perform normal work, and the steam is discharged into the low-pressure cylinder after it has fully expanded.

[0061] Steam extraction port 11 is closed or allowed to flow only a small amount;

[0062] The unit operates at full load of 300MW with a heat rate comparable to the original design, without any additional losses.

[0063] 2. Heating mode (winter);

[0064] The control system 12 receives the heating load command, requiring the intermediate pressure cylinder exhaust pressure to reach 0.6MPa and the temperature to reach 360℃;

[0065] Based on the preset "speed-exhaust parameter" characteristic model, the target speed of the hollow rotor that meets the above parameters is calculated to be 1500 rpm.

[0066] When the control clutch 9 is disengaged, the transmission device 10 (gearbox) drives the hollow rotor 4 to 1500 rpm;

[0067] The 8th and 9th stage moving blades rotate at 1500 rpm, reducing the amount of work done. The enthalpy drop decreases when steam flows through these two stages, and the pressure and temperature at the exhaust port 11 stabilize at 0.6 MPa and 360℃.

[0068] High-temperature and high-pressure steam is drawn to the first station of the heating network through steam extraction port 11 to meet industrial heating needs;

[0069] Real-time monitoring of exhaust parameters and closed-loop correction of the hollow rotor speed based on deviation values ​​ensure stable heating parameters.

[0070] Step 3: Security Protection Mechanism;

[0071] Multiple protection systems are in place to ensure the safe operation of the unit:

[0072] Hard speed constraint: The control system 12 sets the maximum speed of the hollow rotor 4 to not exceed 3000 rpm and the minimum speed to not be lower than 500 rpm, to avoid overspeed or low speed operation.

[0073] Bearing temperature monitoring: The built-in support bearing 7 is equipped with a temperature measuring point. When the temperature exceeds the set value, it will automatically alarm and adjust the operating parameters.

[0074] Clutch status interlock: When clutch 9 is detected to have disengaged or become stuck, the system automatically switches to safe operating mode and issues an alarm.

[0075] Example 2: Another arrangement of the clutch and transmission;

[0076] This embodiment is basically the same as embodiment 1, except that the connection order of the clutch 9 and the transmission device 10 is different. This embodiment adopts scheme B: the rear end 13 of the main shaft is sequentially connected to the transmission device 10, the clutch 9, and the rear end 14 of the hollow rotor.

[0077] In this arrangement, the input shaft of the transmission device 10 (using a variable frequency drive motor) always rotates at 3000 rpm along with the main shaft, and the output shaft speed can be adjusted as needed. When heating is required, the clutch 9 disengages, and the transmission device 10 drives the hollow rotor 4 to the target speed; when pure condensation is required, the clutch 9 engages, and the transmission device 10 synchronizes the hollow rotor 4 to 3000 rpm at a 1:1 transmission ratio.

[0078] The advantages of this scheme are: the clutch 9 is located after the transmission device 10, and does not bear any torque in the heating mode, resulting in a longer service life; at the same time, the speed regulation control of the transmission device 10 is decoupled from the clutch action, making the control logic simpler.

[0079] Example 3: Heating optimization with wide-range speed adjustment;

[0080] This embodiment is designed for application scenarios with large heat load variations. It uses a variable frequency motor as the speed transmission device 10 to achieve stepless speed regulation of the hollow rotor 4 within the range of 500-2800 rpm.

[0081] According to thermodynamic calculations, the work capacity of stages 8 and 9 differs at different speeds, thus affecting the exhaust parameters of the intermediate-pressure cylinder. Through experimental calibration, a precise "speed-exhaust parameter" characteristic curve was established and embedded into the control system 12.

[0082] When the heat load demand changes, the control system 12 calculates the required speed in real time according to the characteristic curve and adjusts it precisely through the variable frequency motor. Tests show that within the range of 1500-2800 rpm, the exhaust pressure regulation accuracy can reach ±0.01 MPa, and the exhaust temperature regulation accuracy can reach ±2℃, fully meeting the requirements for high-quality heating.

[0083] When the speed drops below 1500 rpm, the work capacity of the 8th and 9th stage moving blades is significantly reduced, and the exhaust parameters are close to the inlet parameters of the intermediate pressure cylinder, which can meet the heating demand of higher parameters. However, excessively low speed may cause flow stability problems. Therefore, in this embodiment, 500 rpm is set as the minimum operating speed.

[0084] Example 4: Lubrication and cooling of the built-in support bearing;

[0085] The built-in support bearing 7 is located between the 7th and 8th stages, and operates in a high-temperature environment (approximately 300-350℃), which places higher demands on lubrication and cooling.

[0086] In this embodiment, the built-in support bearing 7 adopts a tilting pad structure and is equipped with an independent high-temperature resistant lubricating oil pipeline 16. The lubricating oil is a synthetic high-temperature resistant turbine oil, which is supplied to the bearing through a high-pressure oil pump, serving both a lubricating function and removing heat from the bearing. The returned oil is cooled and then recycled.

[0087] The bearing is equipped with temperature and vibration sensors to monitor its operating status in real time. When the bearing temperature exceeds the set value (e.g., 120℃), the control system 12 automatically increases the lubricating oil flow or reduces the speed of the hollow rotor 4 to ensure the safe operation of the bearing.

[0088] Example 5: Optimization of the sealing structure;

[0089] To prevent high-pressure steam from leaking through the gap between the main shaft 2 and the hollow rotor 4, this embodiment incorporates a multi-stage labyrinth seal device 15 between them. The labyrinth seal's teeth are designed to be floating to adapt to thermal expansion under different operating conditions, ensuring that the sealing gap is always within the optimal range, minimizing steam leakage loss, and improving unit efficiency.

[0090] As can be seen from the above embodiments, the present invention realizes the active adjustment of the exhaust parameters of the intermediate pressure cylinder, which not only solves the blade impact problem of the rotating baffle, but also achieves high-quality heating. Moreover, it is feasible to implement in engineering and has significant technical progress and practical value.

[0091] Example 6: This example provides a steam turbine, including the intermediate pressure rotor structure of the steam turbine as described in any one of Examples 1.

[0092] Example 7: This example provides a method for controlling the exhaust parameters of the intermediate-pressure cylinder of the steam turbine described in Example 6, including:

[0093] Receive external heating load instructions and determine the required target parameters for intermediate pressure cylinder exhaust steam;

[0094] Based on the preset "hollow rotor speed - exhaust parameters" characteristic model, calculate the hollow rotor target speed corresponding to the intermediate pressure cylinder exhaust target parameters;

[0095] Determine the deviation between the target speed of the hollow rotor and the rated speed of the spindle:

[0096] If the target speed of the hollow rotor is equal to the rated speed of the main shaft, then the clutch is controlled to close, so that the hollow rotor rotates synchronously with the main shaft;

[0097] If the target speed of the hollow rotor is lower than the rated speed of the main shaft, the clutch is disengaged and the hollow rotor is driven to the target speed through the speed transmission device.

[0098] The exhaust parameters of the intermediate pressure cylinder are monitored in real time and compared with the target exhaust parameters. The rotational speed of the hollow rotor is corrected in a closed loop based on the deviation value until the exhaust parameters stabilize within the target range.

[0099] When the target speed of the hollow rotor is lower than the rated speed of the spindle, the speed adjustment range of the hollow rotor is 500 rpm to 2800 rpm.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A steam turbine intermediate-pressure rotor structure, characterized in that, include: Medium pressure cylinder; The main shaft is located inside the intermediate pressure cylinder, and a front-stage moving blade assembly is sequentially arranged along the axial direction on the main shaft; A hollow rotor is coaxially sleeved on the rear outer side of the main shaft, and a rear-stage moving blade assembly is provided on the hollow rotor; A cylinder body through-hole structure is provided at the exhaust end of the intermediate pressure cylinder to lead the rear end of the main shaft and the rear end of the hollow rotor to the outside of the cylinder body; The clutch, located outside the intermediate pressure cylinder and connected to the rear end of the main shaft, is used to control the power connection state between the hollow rotor and the main shaft. A speed-changing transmission device is located outside the intermediate pressure cylinder and is connected between the main shaft, the clutch and the rear end of the hollow rotor, for driving the hollow rotor to rotate at an adjustable speed. The steam extraction port is located in the exhaust area of ​​the intermediate-pressure cylinder downstream of the rear-stage moving blade assembly, and is used to connect to the external heating network; The control system is signal-connected to the clutch and the transmission device, and is used to control the engagement and disengagement of the clutch according to the heating demand, and to control the transmission device to adjust the speed of the hollow rotor.

2. The intermediate-pressure rotor structure of the steam turbine according to claim 1, characterized in that, The preceding blade group includes blades of stages 1-7, and the following blade group includes blades of stages 8 and 9.

3. The intermediate-pressure rotor structure of the steam turbine according to claim 1, characterized in that, It also includes a built-in support bearing, which is located between the front-stage moving blade assembly and the rear-stage moving blade assembly to support the front end of the hollow rotor; the built-in support bearing is a tilting pad bearing or a multi-oil wedge bearing, and is equipped with a high-temperature resistant lubricating oil pipeline.

4. The intermediate-pressure rotor structure of the steam turbine according to claim 1, characterized in that, The connection sequence between the clutch and the transmission device is as follows: the rear end of the main shaft is sequentially connected to the clutch, the transmission device, and the rear end of the hollow rotor. Alternatively, the rear end of the main shaft is sequentially connected to the transmission device, the clutch, and the rear end of the hollow rotor.

5. The intermediate-pressure rotor structure of the steam turbine according to claim 1, characterized in that, The speed transmission device is a gearbox or a variable frequency drive motor.

6. The intermediate-pressure rotor structure of the steam turbine according to claim 1, characterized in that, The clutch is a synchronous self-shifting clutch or an SSS clutch.

7. The intermediate-pressure rotor structure of the steam turbine according to claim 1, characterized in that, A sealing device is provided between the hollow rotor and the main shaft to prevent steam from leaking through the gap between them.

8. A steam turbine, characterized in that, Includes the intermediate-pressure rotor structure of a steam turbine as described in any one of claims 1 to 7.

9. A method for controlling the exhaust parameters of the intermediate-pressure cylinder of the steam turbine according to claim 8, characterized in that, include: Receive external heating load instructions and determine the required target parameters for intermediate pressure cylinder exhaust steam; Based on the preset "hollow rotor speed - exhaust parameters" characteristic model, calculate the hollow rotor target speed corresponding to the intermediate pressure cylinder exhaust target parameters; Determine the deviation between the target speed of the hollow rotor and the rated speed of the spindle: If the target speed of the hollow rotor is equal to the rated speed of the main shaft, then the clutch is controlled to close, so that the hollow rotor rotates synchronously with the main shaft; If the target speed of the hollow rotor is lower than the rated speed of the main shaft, the clutch is disengaged and the hollow rotor is driven to the target speed through the speed transmission device. The exhaust parameters of the intermediate pressure cylinder are monitored in real time and compared with the target exhaust parameters. The rotational speed of the hollow rotor is corrected in a closed loop based on the deviation value until the exhaust parameters stabilize within the target range.

10. The control method according to claim 9, characterized in that, When the target speed of the hollow rotor is lower than the rated speed of the spindle, the speed adjustment range of the hollow rotor is 500 rpm to 2800 rpm.

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