Steam leakage system for shaft seal end part of cylinder body of ultra-supercritical unit

Abstract

The utility model discloses an ultra-supercritical unit cylinder shaft seal end steam leakage system, which relates to the technical field of turbine power generation and comprises a sealing cover, a deaerator, a shaft seal steam leakage main pipeline, a shaft seal steam return main pipe, a steam return branch pipe and the like. The sealing cover wraps the two ends of the shaft seal and is connected with the main pipeline through a steam outlet, the main pipeline is provided with the electric control valve and the pressure sensor to achieve shaft seal cavity negative pressure closed-loop control, and the check valve prevents steam backflow of the deaerator. Steam treated by the deaerator is divided into two steam return branch pipes by a three-way valve through a steam return main pipe, flow sensors on the branch pipes are linked with regulating valves to regulate flow, and pressure balance at the two ends of the shaft seal is ensured. Through closed circulation of leaked steam collection, heat energy recovery and pressure regulation and control, the leaked steam recovery utilization rate is increased, shaft seal pressure is accurately controlled, full-load stable operation is achieved, and meanwhile the operation safety of the unit is guaranteed through the multi-layer safety design.

Description

A steam leakage system at the end of the cylinder block shaft seal of an ultra-supercritical unit Technical Field

[0001] This utility model relates to the field of steam turbine power generation technology, specifically to a steam leakage system at the end of the cylinder shaft seal of an ultra-supercritical unit. Background Technology

[0002] During the operation of ultra-supercritical units, steam leakage at the shaft seal end has long constrained the safety and economy of the units. Currently, traditional steam leakage recovery technologies at the cylinder block shaft seal end of ultra-supercritical units mainly suffer from problems such as low steam leakage utilization rate, unstable pressure control, and poor system safety, making it difficult to meet the demands of modern high-efficiency and energy-saving power generation.

[0003] In existing technologies, some units employ an open-emission system, directly venting leaking steam from shaft seals to the atmosphere or into a low-pressure heater for simple heat exchange. This approach not only wastes a significant amount of steam thermal energy and reduces unit thermal efficiency but also leads to increased energy consumption and operating costs. Furthermore, open-emission systems allow steam to easily enter the bearing housing, causing lubricating oil emulsification and deterioration, seriously threatening the safe and stable operation of the unit. Frequent equipment maintenance further increases operating costs.

[0004] Another type of technology, while employing a closed-loop recovery system, is mostly a single-path steam return design, which cannot effectively balance the circumferential pressure at both ends of the shaft seal. When the unit is running, uneven pressure at the shaft seal end will cause local steam leakage, resulting in low steam leakage recovery efficiency. Furthermore, the single-path steam return system lacks a flow regulation device, making it difficult to adapt to changes in unit load. Under low load conditions, the steam leakage recovery effect drops significantly, and may even require shutdown for adjustment, seriously affecting the continuous operation and power generation efficiency of the unit.

[0005] Furthermore, existing technologies have significant shortcomings in pressure control. Traditional systems rely heavily on manually adjusting valves to control shaft seal pressure, failing to achieve real-time dynamic monitoring and precise control, resulting in large pressure fluctuations within the shaft seal cavity. Excessive pressure exacerbates steam leakage, while insufficient pressure may allow air to backflow into the system, disrupting the vacuum and reducing the unit's economy and safety. Moreover, existing systems have relatively weak safety protection measures, lacking effective backflow and overpressure protection devices. Once abnormal operating conditions occur, serious accidents such as steam backflow and pipe ruptures can easily occur.

[0006] With the increasing demands for energy conservation, emission reduction, and equipment reliability in the power industry, existing steam leakage recovery technologies at the cylinder block shaft seal end of ultra-supercritical units are no longer sufficient to meet practical needs. There is an urgent need to develop a new steam leakage system that can efficiently recover leaked steam heat, precisely control shaft seal pressure, adapt to full-load operation, and possess high safety, in order to improve the overall performance and economic benefits of the unit and promote the sustainable development of the power industry. Summary of the Invention

[0007] The purpose of this utility model is to provide a steam leakage system at the end of the cylinder block shaft seal of an ultra-supercritical unit. The system collects the leaking steam through a sealed cover, introduces it into the deaerator through the main steam leakage pipeline of the shaft seal to recover heat energy, and then distributes it to two return steam branch pipes through a three-way valve to regulate the flow rate and maintain the negative pressure in the shaft seal cavity, thus forming a closed-loop system for steam leakage collection, heat energy recovery and pressure regulation.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a steam leakage system for the end of a cylinder block shaft seal in an ultra-supercritical unit, comprising a sealing cover and a deaerator. The sealing cover is respectively wrapped and sealed at both ends of the cylinder block shaft seal of the ultra-supercritical unit. The sealing cover at both ends is connected to the main steam leakage pipeline of the shaft seal via a steam outlet. The other end of the main steam leakage pipeline is connected to the deaerator. The main steam leakage pipeline is equipped with an electric regulating valve and a pressure sensor. The electric regulating valve adjusts its opening according to the detection signal from the pressure sensor. A check valve is installed near the deaerator end of the main steam leakage pipeline. After treatment by the deaerator, the main steam leakage pipeline is led out to the main steam return pipe of the shaft seal. The main steam return pipe branches into a first return pipe and a second return pipe via a three-way valve. The first return pipe and the second return pipe are respectively connected to the return steam interfaces at both ends of the cylinder block shaft seal.

[0009] The first and second return steam branch pipes are respectively equipped with flow regulating valves and flow sensors. The flow regulating valves independently adjust the steam flow of each branch pipe according to the detection signal of the flow sensor.

[0010] The main pipe for steam leakage of the shaft seal is made of stainless steel and is wrapped with an insulation layer. The insulation layer is a 100mm thick rock wool board and covered with a 0.16mm thick aluminum sheet.

[0011] A safety valve is installed on the shaft seal return steam main, and the opening pressure of the safety valve is set to 0.3 MPa.

[0012] Bypass pipes are installed before and after the electric regulating valve on the main steam leakage pipeline of the shaft seal, and manual shut-off valves are installed on the bypass pipes.

[0013] A quick-closing solenoid valve is added to the first and second return steam branch pipes. When the unit vacuum is lower than -87 kPa, the quick-closing solenoid valve closes.

[0014] When the ultra-supercritical unit's cylinder block shaft seal end leakage system is working, the sealing cover collects the leakage steam from both ends of the shaft seal and introduces it into the deaerator through the shaft seal leakage steam main pipeline. The pressure sensor on the main pipeline monitors the pressure in real time, and the electric regulating valve adjusts the opening to maintain negative pressure accordingly. The check valve prevents steam backflow. The steam treated by the deaerator is distributed to the first and second return steam branch pipes through the shaft seal return steam main pipe by a three-way valve. The flow sensor on each branch pipe is linked with the regulating valve to adjust the flow rate, so that the pressure at both ends of the shaft seal is balanced. At the same time, the safety valve on the shaft seal return steam main pipe prevents system overpressure. The bypass pipeline and the manual shut-off valve ensure system operation in case of electric regulating valve failure. The quick-closing solenoid valve closes to maintain vacuum when the unit vacuum is insufficient, thus forming a closed loop of "leakage steam collection - heat energy recovery - pressure regulation", realizing efficient utilization of leakage steam and stable system operation.

[0015] Compared with the prior art, the beneficial effects of this utility model are:

[0016] By enclosing the shaft seal end with a sealed cover and introducing the leaked steam into the deaerator, a complete closed-loop system is formed. Compared with traditional open discharge or simple recovery methods, the leakage steam recovery and utilization rate is greatly improved, effectively reducing energy waste and lowering the unit's operating costs.

[0017] The pressure sensor on the main pipeline for shaft seal leakage is linked with the electric regulating valve to monitor and adjust the pressure inside the shaft seal cavity in real time, so that the pressure is kept stable within the set range. Compared with the large pressure fluctuations in the existing technology, this can effectively prevent steam leakage and air seepage, and ensure the safe and stable operation of the unit.

[0018] The first and second return steam branch pipes are equipped with flow sensors and regulating valves, which can independently adjust the steam flow of each branch pipe according to the detection signal, ensuring uniform circumferential pressure at both ends of the cylinder shaft seal. This overcomes the defect of uneven pressure in the existing single-path return steam system, which leads to severe local steam leakage, and extends the service life of the shaft seal components.

[0019] A check valve is installed near the deaerator end of the main shaft seal leakage pipeline to prevent backflow of steam in the deaerator from causing system failure; a safety valve is installed on the shaft seal return steam main pipe to automatically release pressure when the system pressure exceeds 0.3MPa; a fast-closing solenoid valve is added to the return steam branch pipe to quickly close when the unit vacuum is below -87kPa. The multi-layer safety protection design significantly enhances safety compared to existing technologies.

[0020] The main pipeline for shaft seal leakage is made of stainless steel and wrapped with a 100mm thick rock wool insulation layer, and covered with a 0.16mm thick aluminum sheet, which effectively reduces heat loss and pipeline corrosion. Bypass pipelines and manual shut-off valves are set before and after the electric regulating valve, which can be manually operated in case of automatic regulating system failure, ensuring continuous and stable system operation and reducing the frequency of downtime maintenance. Attached Figure Description

[0021] Figure 1 is a diagram of a steam leakage system at the end of the cylinder shaft seal of an ultra-supercritical unit according to the present invention.

[0022] In the diagram: 1. Enclosed hood; 2. Deaerator; 11. Shaft seal leakage main pipe; 12. Electric regulating valve; 13. Pressure sensor; 14. Check valve; 21. Shaft seal return steam main pipe; 22. Three-way valve; 23. First return steam branch pipe; 24. Second return steam branch pipe; 216. Flow regulating valve; 26. Flow sensor; 17. Insulation layer; 27. Safety valve; 116. Bypass pipe; 16. Manual shut-off valve; 28. Quick-closing solenoid valve. Detailed Implementation

[0023] The technical solutions of the present invention will now be described in detail with reference to the accompanying drawings of the embodiments.

[0024] As shown in Figure 1, a steam leakage system for the cylinder block shaft seal end of an ultra-supercritical unit includes a sealing cover 1 and a deaerator 2. The sealing cover 1 is respectively wrapped and sealed at both ends of the cylinder block shaft seal of the ultra-supercritical unit. The system is characterized in that the two sealing covers 1 are connected to the main steam leakage pipeline 11 of the shaft seal through steam outlets. The other end of the main steam leakage pipeline 11 is connected to the deaerator 2. The main steam leakage pipeline 11 is equipped with an electric regulating valve 12 and a pressure sensor 13. The electric regulating valve 12 adjusts the opening degree according to the detection signal of the pressure sensor 13. The end of the main steam leakage pipeline 11 near the deaerator 2 is provided with a check valve 14. After treatment by the deaerator 2, the pipeline is led out to the shaft seal return steam main pipe 21. The shaft seal return steam main pipe 21 branches into a first return steam branch pipe 23 and a second return steam branch pipe 24 through a three-way valve 22. The first return steam branch pipe 23 and the second return steam branch pipe 24 are respectively connected to the return steam interfaces at both ends of the cylinder block shaft seal.

[0025] The first return steam branch pipe 23 and the second return steam branch pipe 24 are respectively equipped with a flow regulating valve 216 and a flow sensor 26. The flow regulating valve 216 independently adjusts the steam flow of each branch pipe according to the detection signal of the flow sensor 26.

[0026] The shaft seal leakage main pipeline 11 is made of stainless steel and is wrapped with an insulation layer 17 on the outer surface. The insulation layer 17 is a 100mm thick rock wool board covered with a 0.16mm thick aluminum sheet.

[0027] The shaft seal return steam main pipe 21 is equipped with a safety valve 27, and the opening pressure of the safety valve 27 is set to 0.3MPa.

[0028] The main steam leakage pipeline 11 of the shaft seal is equipped with bypass pipelines 116 before and after the electric regulating valve 12, and a manual shut-off valve 16 is installed on the bypass pipeline.

[0029] A quick-closing solenoid valve 28 is added to the first return steam branch pipe 23 and the second return steam branch pipe 24. When the unit vacuum is lower than -87kPa, the quick-closing solenoid valve 28 closes.

[0030] During operation of the ultra-supercritical unit, the sealing cover 1 tightly wraps around both ends of the cylinder shaft seal, forming a sealed space to completely collect the leaking steam generated by the shaft seal. The leaking steam merges into the main leakage steam pipeline 11 through the steam outlet of the sealing cover 1. On the main pipeline, the pressure sensor 13 monitors the pressure data in the pipeline in real time and transmits the signal to the control system. The electric regulating valve 12 automatically adjusts its opening according to the detection signal of the pressure sensor 13. When the pressure is higher than the set value, the electric regulating valve 12 opens wider to accelerate the discharge of leaking steam; when the pressure is lower than the set value, the valve closes to maintain the pressure in the shaft seal cavity within the range of -1.2 to -1.8 kPa.

[0031] The leaking steam in the main steam pipe 11 of the shaft seal is ultimately introduced into the deaerator 2. A check valve 14 installed near the deaerator 2 effectively prevents steam backflow within the deaerator. After the deaerator 2 processes the leaking steam, the steam is led out through the shaft seal return steam main pipe 21. A safety valve 27 is installed on the shaft seal return steam main pipe 21. When the system pressure exceeds 0.3 MPa, the safety valve 27 automatically opens to release pressure, ensuring system safety.

[0032] Steam in the shaft seal return steam main 21 branches into a first return steam branch 23 and a second return steam branch 24 via a three-way valve 22, which are respectively connected to the return steam interfaces at both ends of the cylinder block shaft seal. A flow sensor 26 and a flow regulating valve 216 are installed on the first return steam branch 23 and the second return steam branch 24, respectively. The flow sensor 26 monitors the steam flow in each branch in real time and feeds the data back to the control system. The flow regulating valve 216 independently adjusts the steam flow in each branch according to the detection signal of the flow sensor 26 to ensure pressure balance at both ends of the shaft seal.

[0033] The main steam leakage pipeline 11 is made of stainless steel, with a 100mm thick rock wool insulation layer 1677 wrapped around its outer surface and covered with a 0.16mm thick aluminum sheet to reduce heat loss. Bypass pipelines 116 are installed before and after the electric regulating valve 12, and manual shut-off valves 16 are installed on the bypass pipelines. When the electric regulating valve 12 malfunctions, the pipeline can be opened or closed via the manual shut-off valve 16 to ensure continuous system operation.

[0034] A quick-closing solenoid valve 28 is added to the first return steam branch pipe 23 and the second return steam branch pipe 24. When the unit vacuum level is lower than -87 kPa, the quick-closing solenoid valve 28 closes rapidly to prevent air from entering the system and maintain the unit vacuum level. Through the coordinated operation of the above components, efficient recovery of steam leakage at the cylinder shaft seal end of the ultra-supercritical unit and stable system operation are achieved.

Claims

1. A steam leakage system for the cylinder block shaft seal end of an ultra-supercritical unit, comprising a sealing cover (1) and a deaerator (2), wherein the sealing cover (1) respectively wraps and seals the ends of the cylinder block shaft seal of the ultra-supercritical unit, characterized in that, The two-end sealing cover (1) is connected to the main steam leakage pipe (11) of the shaft seal through the steam outlet. The other end of the main steam leakage pipe (11) of the shaft seal is connected to the deaerator (2). The main steam leakage pipe (11) of the shaft seal is equipped with an electric regulating valve (12) and a pressure sensor (13). The electric regulating valve (12) adjusts the opening according to the detection signal of the pressure sensor (13). The main steam leakage pipe (11) of the shaft seal is equipped with a check valve (14) near the deaerator (2). After the deaerator (2) processes the steam, it is led out to the main steam return pipe (21) of the shaft seal. The main steam return pipe (21) of the shaft seal is branched into a first steam return branch pipe (23) and a second steam return branch pipe (24) through a three-way valve (22). The first steam return branch pipe (23) and the second steam return branch pipe (24) are respectively connected to the steam return interfaces at both ends of the shaft seal of the cylinder block.

2. The steam leakage system at the end of the cylinder block shaft seal of an ultra-supercritical unit according to claim 1, characterized in that, The first return steam branch pipe (23) and the second return steam branch pipe (24) are respectively equipped with a flow regulating valve (216) and a flow sensor (26). The flow regulating valve (216) independently adjusts the steam flow of each branch pipe according to the detection signal of the flow sensor (26).

3. The steam leakage system of the cylinder seal end portion of the ultra-supercritical unit according to claim 1, characterized in that, The shaft seal leakage main pipeline (11) is made of stainless steel and is wrapped with an insulation layer (17) on the outer surface. The insulation layer (17) is a 100mm thick rock wool board and covered with a 0.16mm thick aluminum sheet.

4. The steam leakage system at the end of the cylinder block shaft seal of an ultra-supercritical unit according to claim 1, characterized in that, The shaft seal return steam main pipe (21) is equipped with a safety valve (27), and the opening pressure of the safety valve (27) is set to 0.3MPa.

5. The steam leakage system of the cylinder seal end portion of the ultra-supercritical unit according to claim 1, characterized in that, The electric regulating valve (12) on the shaft seal leakage steam main pipeline (11) is provided with bypass pipelines (116) before and after it, and a manual shut-off valve (16) is provided on the bypass pipeline.

6. The steam leakage system at the end of the cylinder block shaft seal of an ultra-supercritical unit according to claim 1, characterized in that, A quick-closing solenoid valve (28) is added to the first return steam branch pipe (23) and the second return steam branch pipe (24). When the unit vacuum is lower than -87kPa, the quick-closing solenoid valve (28) closes.

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