Steam seal steam leakage cooling system of supercritical back pressure turbine

Abstract

The utility model discloses a steam-gas seal steam leakage cooling system of a supercritical back pressure steam turbine, and relates to the technical field of steam turbine power generation, a plurality of branch pipelines are branched from a high-pressure shaft end steam seal pipeline group and are communicated with a water spraying assembly, and a low-pressure shaft end steam seal pipeline group is also communicated with the water spraying assembly; an expansion chamber formed by local diameter expansion is arranged at the connection part of the water spraying assembly; the branch pipeline terminal and the low-pressure shaft end pipeline terminal converge to a cooling pipeline, the cooling pipeline is communicated with a cooler, and safety pipelines and electric valves are arranged on the upstream portions of the high-pressure shaft sealing pipeline set and the low-pressure shaft sealing pipeline set. When the system works, efficient cooling of steam seal leakage under supercritical parameters is achieved through graded water spraying cooling, chamber expanding for gas-liquid mixing strengthening, secondary cooling of a cooling pipeline and emergency switching of a safety pipeline, compared with a traditional technology, the cooling efficiency is improved, the safety redundancy is improved, and the system can adapt to steam turbine load fluctuation; the device has the advantages of high cooling efficiency, safety, reliability, convenient maintenance and the like.

Description

A steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine Technical Field

[0001] This utility model relates to the field of steam turbine power generation technology, specifically to a steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine. Background Technology

[0002] In the operation of supercritical back-pressure steam turbines, effective cooling of steam seal leakage is crucial for ensuring the unit's efficient and safe operation. With the power industry's increasing demands for energy efficiency and environmental protection, supercritical steam turbines, due to their higher steam parameters and thermal efficiency, are widely used in thermal power plants. However, if the high-temperature and high-pressure steam seal leakage generated at the high-pressure and low-pressure shaft ends cannot be cooled and recovered in a timely manner, it will not only cause significant energy loss but may also lead to deterioration of equipment material performance, aging of seals, and even safety accidents due to localized overheating.

[0003] Currently, traditional steam seal leakage cooling systems mostly employ single-stage water spray cooling and a single-pipe connection structure. This approach has several drawbacks: Firstly, single-stage water spray cannot adequately cool high-temperature, high-pressure leakage steam, especially under supercritical parameters where leakage steam temperatures exceed 480℃ and pressures exceed 3.2MPa. Single-stage water spray is prone to uneven cooling, localized overcooling or overheating, resulting in low cooling efficiency. Secondly, the single-pipe connection structure lacks flexibility and redundancy. When pipe blockage or water spray system failure occurs, it cannot quickly switch to a backup path, posing safety hazards. Furthermore, the system struggles to adapt to changes in leakage steam parameters during turbine load fluctuations. In addition, the connection method between the water spray components and the pipes in existing systems is relatively simple, resulting in poor gas-liquid mixing. Ordinary water spray interface designs cannot effectively promote sufficient contact between atomized water and leakage steam, leading to low atomized water evaporation efficiency and significantly reduced cooling effect. Moreover, in terms of system maintenance, traditional connection structures often use welding or fixed flange connections, making disassembly difficult. Once internal scaling or component damage occurs, repairs are time-consuming, severely impacting the unit's continuous operating time and overall economic efficiency.

[0004] With the continuous improvement of supercritical steam turbine parameters and the increasing demand for intelligent operation and maintenance, the shortcomings of traditional steam seal leakage cooling systems in terms of cooling efficiency, safety, flexibility, and ease of maintenance are becoming increasingly prominent. Therefore, there is an urgent need to develop a new type of steam seal leakage cooling system that can solve the problems of existing technologies through innovative connection structures and cooling methods, in order to meet the urgent needs of the modern power industry for efficient, reliable, and intelligent equipment. Summary of the Invention

[0005] The purpose of this utility model is to provide a steam seal leakage cooling system for a supercritical back-pressure steam turbine. Multiple branch pipes from the high-pressure shaft end steam seal pipe group and the low-pressure shaft end steam seal pipe group are connected to the water spray pipe assembly for atomization and cooling. After enhanced mixing in the expanded chamber, the water flows into the cooling pipe and is then condensed into liquid water by the cooler. At the same time, the upstream and downstream safety pipes ensure safe operation in case of system abnormalities.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A steam seal leakage cooling system for a supercritical back-pressure steam turbine includes a back-pressure steam turbine, wherein the shaft seals at both ends of the back-pressure steam turbine are respectively connected to a high-pressure shaft end steam seal pipe group and a low-pressure shaft end steam seal pipe group, characterized in that the low-pressure shaft end steam seal pipe group is connected to a water spray pipe assembly;

[0008] The high-pressure shaft end steam seal pipe component has multiple branch pipes, and each branch pipe is connected to a water spray pipe assembly.

[0009] The multiple branch pipes are merged into a single pipe, and the single pipe is merged with the low-pressure shaft end steam seal pipe group into a cooling pipe. The cooling pipe is then connected to the cooler.

[0010] The cooling pipe is connected to a water spray pipe assembly.

[0011] The water spray pipe assembly includes a desuperheating water pipe, which is equipped with a desuperheating water pipe electric valve. The end of the valve that is away from the pipe in the system is connected to the desuperheating water supply, and the end that is connected to the pipe in the system is equipped with an adjustable atomizing nozzle.

[0012] The high-pressure shaft end steam seal pipe assembly has a safety pipe installed in the area in front of the branch pipe. The safety pipe is connected to the cooler and is equipped with a safety pipe electric valve.

[0013] The low-pressure shaft end steam seal pipe assembly is provided with a safety pipe in the area in front of the water spray pipe assembly. The safety pipe is connected to the cooler and is equipped with a safety pipe electric valve.

[0014] An enlarged chamber is provided at the point where the water spray pipe assembly connects to the pipe within the system. The enlarged chamber is formed by locally expanding the diameter of the pipe within the system.

[0015] When the steam seal leakage cooling system of this supercritical back-pressure steam turbine is working, the leakage steam generated by the shaft seals at both ends of the back-pressure steam turbine is transmitted through the high-pressure shaft seal pipeline group and the low-pressure shaft seal pipeline group, respectively. Multiple branch pipes branching off from the high-pressure shaft seal pipeline group are connected to the water spray pipeline assembly. Desuperheating water is sprayed into the branch pipes through desuperheating water pipes and electric valves, then mixed with the leakage steam by atomizing nozzles for cooling. The low-pressure shaft seal pipeline group is also connected to the water spray pipeline assembly for atomized cooling. Furthermore, the pipeline within the system at the water spray assembly connection point is locally enlarged to form an enlarged chamber to enhance the gas-liquid mixing effect. The single pipe formed by the merging of multiple branch pipe terminals converges with the terminal of the low-pressure shaft seal pipeline group to the cooling pipe. If the temperature inside the cooling pipe is too high, the connected water spray assembly initiates secondary cooling. Finally, the leakage steam enters the cooler and condenses into liquid water. Simultaneously, safety pipes are installed upstream of the water spray assembly for both the high-pressure and low-pressure shaft seal pipeline groups. When the main pipeline or water spray system fails, the electric valve on the safety pipe opens, allowing the leakage steam to flow directly into the cooler, ensuring safe system operation.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] Staged cooling improves cooling efficiency: The high-pressure shaft end steam seal pipeline has multiple branch pipelines and is equipped with water spray components to achieve staged atomization cooling of high-temperature and high-pressure leaking steam, which improves the efficiency by 30% compared with the traditional single-stage water spray cooling and avoids equipment damage caused by local overheating.

[0018] Enlarging the chamber enhances the mixing effect: The pipe at the water spray component inlet is partially enlarged to form an enlarged chamber. Through the expansion of the flow field, the gas-liquid contact area is increased by 40%, the mixing time is extended by 1.5 times, and the evaporation efficiency of atomized water is improved.

[0019] Multi-layer safety redundancy design: Safety pipes and electric valves are installed upstream of both high and low pressure shaft seal pipe groups. When the main pipe is blocked or the water spray system fails, it will automatically switch to the bypass path within 0.5 seconds to avoid shaft end pressure exceeding the limit. The system safety redundancy is improved by 50% compared with the existing technology.

[0020] Precise temperature control throughout the entire process: The cooling pipes are connected to the water spray assembly to achieve secondary cooling. Combined with the flow control of the adjustable atomizing nozzles, the temperature fluctuation range of the cooler inlet is controlled within ±5℃, which meets the equipment design requirements under supercritical parameters.

[0021] Adaptable to a wide range of operating conditions: Through the graded control of branch pipelines and the coordinated work of safety pipelines, the system can maintain a stable cooling effect even when the turbine load fluctuates, and its operational adaptability is better than that of traditional fixed pipeline structures. Attached Figure Description

[0022] Figure 1 is a diagram of the steam-gas seal leakage cooling system of a supercritical back-pressure steam turbine according to this utility model;

[0023] In the diagram: 1. Back-pressure steam turbine; 11. High-pressure shaft end steam seal piping assembly; 12. Low-pressure shaft end steam seal piping assembly; 121. Branch piping; 13. Cooling piping; 2. Water spray piping assembly; 21. Desuperheating water piping; 22. Adjustable atomizing nozzle; 23. Electric valve for desuperheating water piping; 24. Enlarged chamber; 3. Cooler; 31. Safety piping; 32. Electric valve for safety piping. Detailed Implementation

[0024] The technical solutions of the present invention will now be described in detail with reference to the accompanying drawings of the embodiments.

[0025] As shown in Figure 1, a steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine includes a back-pressure steam turbine 1. The shaft seals at both ends of the back-pressure steam turbine 1 are respectively connected to a high-pressure shaft end steam seal pipe assembly 11 and a low-pressure shaft end steam seal pipe assembly 12. The low-pressure shaft end steam seal pipe assembly 12 is characterized in that it is connected to a water spray pipe assembly 2.

[0026] The high-pressure shaft end steam seal pipe assembly 11 branches into multiple branch pipes 121, and each branch pipe 121 is connected to a water spray pipe assembly 2.

[0027] The multiple branch pipes 121 are merged into a single pipe at their terminals. The single pipe and the low-pressure shaft end steam seal pipe group 12 are merged into the cooling pipe 13 at their terminals. The cooling pipe 13 is connected to the cooler 3 at its terminal.

[0028] The cooling pipe 13 is connected to the water spray pipe assembly 2.

[0029] The water spray pipe assembly 2 includes a desuperheating water pipe 21, which is equipped with a desuperheating water pipe electric valve 23. The end of the valve that is away from the pipe in the system is connected to the desuperheating water, and the end that is connected to the pipe in the system is equipped with an adjustable atomizing nozzle 22.

[0030] The high-pressure shaft end steam seal pipe assembly 11 has a safety pipe 31 installed in the area in front of the branch pipe 121. The safety pipe 31 is connected to the cooler 3, and a safety pipe electric valve 32 is installed on the safety pipe 31.

[0031] The low-pressure shaft end steam seal pipe assembly 12 is provided with a safety pipe 31 in the area in front of the water spray pipe assembly 2. The safety pipe 31 is connected to the cooler 3, and a safety pipe electric valve 32 is provided on the safety pipe 31.

[0032] The water spray pipe assembly 2 is connected to the pipe section within the system and an enlarged chamber 24 is provided. The enlarged chamber 24 is formed by locally enlarging the diameter of the pipe within the system.

[0033] During the operation of a supercritical back-pressure steam turbine, the leaking steam generated by the shaft seals at both ends is transmitted through the high-pressure shaft-end steam seal pipeline group 11 and the low-pressure shaft-end steam seal pipeline group 12, respectively. Multiple branch pipelines 121 branching from the high-pressure shaft-end steam seal pipeline group 11 are all connected to the water spray pipeline assembly 2. Desuperheating water, after passing through the desuperheating water pipeline 21 and the desuperheating water pipeline electric valve 23, is sprayed into the branch pipelines 121 by adjustable atomizing nozzles 22 to mix with the leaking steam and cool it. The low-pressure shaft-end steam seal pipeline group 12 is also connected to the water spray pipeline assembly 2 for atomized cooling. Furthermore, the pipeline within the system at the water spray assembly connection point is locally enlarged to form an enlarged chamber 24 to enhance the gas-liquid mixing effect. Multiple branch pipes 121 are merged into a single pipe and then converge with the low-pressure shaft end steam seal pipe group 12 to the cooling pipe 13. If the temperature inside the cooling pipe 13 is too high, the water spray assembly connected to it will start secondary cooling. Finally, the leaking steam enters the cooler 3 and condenses into liquid water. At the same time, both the high-pressure and low-pressure shaft end steam seal pipe groups are equipped with safety pipes 31 and safety pipe electric valves 32 upstream of the water spray assembly. When the main pipe or the water spray system fails, the safety pipe electric valve 32 will open quickly to allow the leaking steam to flow directly into the cooler 3. The entire system dynamically adjusts the opening degree of each valve and the water spray parameters according to the changes in the turbine load to ensure the efficient and stable operation of the system.

Claims

1. A steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine, comprising a back-pressure steam turbine (1), wherein the shaft seals at both ends of the back-pressure steam turbine (1) are respectively connected to a high-pressure shaft end steam seal pipe assembly (11) and a low-pressure shaft end steam seal pipe assembly (12), characterized in that, The low-pressure shaft end steam seal pipe group (12) is connected to the water spray pipe assembly (2); the high-pressure shaft end steam seal pipe group (11) branches into multiple branch pipes (121), each of which is connected to the water spray pipe assembly (2); the multiple branch pipes (121) are merged into a single pipe at the end, and the single pipe and the low-pressure shaft end steam seal pipe group (12) are merged into a cooling pipe (13) at the end, and the cooling pipe (13) is connected to the cooler (3) at the end.

2. The steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine according to claim 1, characterized in that, The cooling pipe (13) is connected to a water spray pipe assembly (2).

3. A steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine according to any one of claims 1-2, characterized in that, The water spray pipe assembly (2) includes a desuperheating water pipe (21), which is equipped with a desuperheating water pipe electric valve (23). The end of the desuperheating water pipe (21) away from the pipe in the system is connected to the desuperheating water, and the end connected to the pipe in the system is equipped with an adjustable atomizing nozzle (22).

4. The steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine according to claim 1, characterized in that, The high-pressure shaft end steam seal pipe assembly (11) has a safety pipe (31) installed in the area in front of the branch pipe (121). The safety pipe (31) is connected to the cooler (3), and a safety pipe electric valve (32) is installed on the safety pipe (31).

5. The steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine according to claim 1, characterized in that, The low-pressure shaft end steam seal pipe assembly (12) is provided with a safety pipe (31) in the area in front of the water spray pipe assembly (2). The safety pipe (31) is connected to the cooler (3). A safety pipe electric valve (32) is provided on the safety pipe (31).

6. The steam-gas seal leakage cooling system for a supercritical back-pressure steam turbine according to claim 1, characterized in that, The water spray pipe assembly (2) is connected to the pipe section of the system and an enlarged chamber (24) is provided. The enlarged chamber (24) is formed by the partial enlargement of the pipe section of the system.

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