A 700 ℃ steam turbine key hot component test system and test method

Abstract

The application discloses a 700 DEG C steam turbine key thermal component test system and a test method, the system comprises a No.1 thermal power unit, a No.2 thermal power unit, a steam extraction unit, a steam heating unit, a test steam turbine unit, a driving unit, a back-steam treatment unit and a desuperheater, and the test method comprises steam source extraction, temperature rising, high-temperature component test, variable working condition simulation, exhaust steam waste heat recycling and uninterrupted continuous test. The application relies on the existing public system of a power plant, the desuperheating water is taken from a condensate water system, the cooling water is taken from a closed circulating water system, the drainage is connected to a cooling tower water supplement system, the power source is taken from a plant power system, and a control system is compatible with the existing DCS of the power plant, so that a complete auxiliary public system does not need to be additionally matched, construction investment and operation and maintenance cost are further compressed, and unified operation and management of the power plant is facilitated.

Description

Technical Field

[0001] This invention relates to a testing system and method for key thermal components of a steam turbine at 700℃. Background Technology

[0002] Advanced ultra-supercritical power generation technology at 700℃ represents a significant development direction for next-generation high-efficiency coal-fired power generation. Its main steam parameters can reach 700℃ / 35MPa, and its power generation efficiency can exceed 50%, which is of great importance for achieving efficient and low-carbon development of coal-fired power generation. However, key hot components of 700℃-class steam turbines (such as high-temperature blades, rotors, valve bodies, and steam pipes) require the use of novel high-temperature alloy materials. The long-term high-temperature performance, microstructure evolution, and lifespan characteristics of these materials must be verified through long-term, engineered testing.

[0003] Currently, high-temperature material testing is mostly conducted on small laboratory test benches, which has the following shortcomings: First, the laboratory test benches are small in scale and cannot simulate the high-flow, long-cycle, and variable-condition operating environment of real power plants; second, building a new independent 700℃ test unit requires huge investment, has a long construction period, and high operating costs; third, most existing test platforms are designed with a single steam source, and once the steam source unit is under maintenance or malfunctions, the test is forced to be interrupted, which cannot meet the long-cycle material verification needs of thousands or even tens of thousands of hours.

[0004] Therefore, there is an urgent need to develop a 700℃ steam turbine hot component test platform that can be constructed at low cost using existing power plant resources and can operate continuously for a long period of time, so as to support the engineering verification of high temperature alloy materials. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a testing system and method for key thermal components of a 700℃ steam turbine. Based on the modification tests conducted on the existing No. 1 and No. 2 thermal power units within the plant area, it effectively solves the problems pointed out in the background art.

[0006] The technical solution adopted in this invention is:

[0007] A test system for key thermal components of a steam turbine at 700℃, comprising:

[0008] Unit 1 and Unit 2 are used for normal thermal power generation within the plant area;

[0009] The steam extraction unit is connected to the high-temperature reheat steam pipelines of Unit 1 and Unit 2 through two sets of branches, and each set of branches is equipped with a steam extraction shut-off valve and a steam extraction regulating valve. The steam extraction unit is used to extract test steam from the high-temperature reheat steam pipelines of Unit 1 or Unit 2.

[0010] A steam heating unit, connected to the steam extraction unit, is used to electrically heat the extracted steam to 695~705℃;

[0011] The test turbine unit is connected to the steam heating unit and is used to introduce steam at 695~705℃ for long-term testing of key thermal components of the turbine.

[0012] A drive unit, connected to the test turbine unit, is used to drive the test turbine to run and adjust its speed to achieve variable operating condition testing;

[0013] The steam return treatment unit is connected at one end to the exhaust port of the test turbine unit, and at the other end to the boiler ash hopper heating system of thermal power unit 1 and thermal power unit 2 respectively through exhaust valve 1 and exhaust valve 2. It is used to de-temperature and depressurize the steam after the test and reuse it to the boiler ash hopper heating system of thermal power unit 1 or thermal power unit 2.

[0014] The desuperheater is installed on the exhaust pipe of the test turbine unit and is used to de-temperature and reduce the pressure of the steam discharged from the test turbine unit.

[0015] Preferably, the desuperheating water used by the desuperheater is connected to the condensate system of thermal power unit 1 and thermal power unit 2 through desuperheating water branch line 1 and desuperheating water branch line 2 respectively. Desuperheating water branch line 1 and desuperheating water branch line 2 are respectively equipped with desuperheating water shut-off valve 1 and desuperheating water shut-off valve 2.

[0016] Preferably, the steam extraction unit is equipped with an electric regulating valve and an electric gate valve.

[0017] Preferably, the steam heating unit is a 2MW-class steam electric heater.

[0018] Preferably, the inlet and outlet steam turbine units of the test turbine unit are made of high-temperature alloy material with a design temperature of 710℃.

[0019] Preferably, the drive unit is a 100kW variable speed motor, which is coaxially connected to the test turbine unit. The operating conditions of the test turbine unit are controlled by adjusting the speed of the variable speed motor.

[0020] Preferably, the system also includes a condensate expansion container and a shaft seal cooler. The condensate expansion container is used to receive steam condensate from the steam pipeline and steam leakage from the inner baffle of the steam seal. The shaft seal cooler is used to cool steam leakage from the outer baffle of the steam seal. The drainage from both the condensate expansion container and the shaft seal cooler is connected to the cooling tower makeup water system.

[0021] Meanwhile, the present invention also provides a test method for key thermal components of a steam turbine at 700℃, comprising the following steps:

[0022] S1. Extract test steam from the high-temperature reheat steam pipeline of an existing ultra-supercritical thermal power unit;

[0023] S2. The extracted steam is heated to 695~705℃ through a steam heating unit;

[0024] S3. High-temperature steam at 695~705℃ is introduced into the test turbine unit to conduct long-cycle operation tests on the key thermal components of the turbine.

[0025] S4. Drive the test turbine unit through the drive unit and adjust the speed to simulate different operating conditions;

[0026] S5. The steam discharged from the test turbine unit is de-heated and depressurized by a desuperheater and then reused in the boiler ash hopper heating system of the thermal power unit.

[0027] S6. Configure dual redundant steam sources for thermal power units No. 1 and No. 2. When the main unit is shut down, it will automatically switch to the standby unit to ensure continuous operation of the test.

[0028] Preferably, in step S2, the steam parameters before heating by the steam heating unit are 6.8 MPa and 628°C, and the steam parameters after heating by the steam heating unit are 1.0 MPa and 700°C, with a steam flow rate of 10 t / h. In step S3, the steam inlet pipe of the test turbine unit is made of a high-temperature alloy material with a design temperature of 710°C and a design pressure of 1.2 MPa.

[0029] Preferably, in step S5, the desuperheating water used by the desuperheater is taken from the condensate system of thermal power unit No. 1 or thermal power unit No. 2. In step S6, when the dual redundant steam sources are switched, the process includes the simultaneous switching of the extraction steam unit, the return steam processing unit, and the desuperheating water branch of the desuperheater.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. Significantly reduce the construction and operation costs of the test platform.

[0032] This invention fully utilizes the high-temperature reheat steam of existing ultra-supercritical thermal power units as the test steam source. It only requires raising the steam temperature from 628°C to 700°C through a steam electric heater to meet the test requirements. There is no need to build a new independent boiler system and a complete power island. Compared with the investment of hundreds of millions of yuan required to build a new independent 700°C test unit, this solution has a lower construction cost and significantly reduces the entry threshold for 700°C high-temperature material testing. At the same time, it only consumes a small amount of electricity for supplemental heating during daily operation, which significantly improves the economic efficiency of operation.

[0033] 2. To achieve long-term, uninterrupted, continuous testing

[0034] This invention adopts a dual-unit triple redundancy design: the extraction steam, return steam, and desuperheating water are all connected to thermal power units No. 1 and No. 2 respectively, and each is equipped with an independent shut-off valve for switching control. When one unit is shut down for maintenance or fails to operate, the valve group can be used to switch to the corresponding system of the other unit to maintain the continuous operation of the test platform. This solves the problem of test interruption caused by main unit maintenance in traditional single steam source test platforms. It can meet the needs of long-cycle performance verification of high-temperature alloy materials for thousands or even tens of thousands of hours, and the continuity and reliability of test data are greatly improved.

[0035] 3. Achieve cascaded recovery and utilization of experimental steam energy.

[0036] The high-temperature steam discharged from the test turbine is de-cooled and depressurized before being reused in the boiler ash hopper heating system to replace the original steam used for heating the ash hopper. This realizes the recovery and utilization of waste heat from the test steam, avoids energy waste caused by direct steam discharge, further improves the operational economy of the test platform, and reduces test energy consumption.

[0037] 4. Flexible operating condition adjustment and high test coverage.

[0038] The test turbine is driven by a 100kW variable speed motor on the same shaft. The operating conditions of the test turbine can be flexibly controlled within a wide range by adjusting the speed of the motor. It can simulate a variety of real operating scenarios such as start-up, speed-up, rated operation, load change, load shedding, and shutdown. Compared with a constant speed test bench, it can cover more material performance assessment under more operating conditions, and the test data is more comprehensive and has higher guiding value for engineering applications.

[0039] 5. The test environment closely resembles real engineering conditions.

[0040] The test platform is built directly in an existing power plant. The steam parameters, flow rate, and operating mode are close to the actual operating environment of the real unit. The test results can more realistically reflect the performance of materials in engineering applications. Compared with small laboratory test benches, the test data has higher engineering credibility and more direct guiding significance for the design and material selection of 700℃ units.

[0041] 6. High system integration, making full use of existing power plant resources.

[0042] The entire test platform relies heavily on the power plant's existing public systems. The desuperheating water is taken from the condensate system, the cooling water is taken from the closed-loop circulating water system, the drainage is connected to the cooling tower makeup water system, the power supply is taken from the plant's power system, and the control system is compatible with the power plant's existing DCS. There is no need to build an additional complete auxiliary public system, which further reduces construction investment and operation and maintenance costs, while facilitating the unified operation and management of the power plant. Attached Figure Description

[0043] Figure 1This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0045] Example 1

[0046] A test system for key thermal components of a steam turbine at 700℃, comprising:

[0047] Unit 1 and Unit 2 are used for normal thermal power generation within the plant area.

[0048] The extraction steam unit 3 is connected to the high-temperature reheat steam pipelines of No. 1 thermal power unit 1 and No. 2 thermal power unit 2 through two sets of branches respectively. Each set of branches is equipped with an extraction steam shut-off valve 4 and an extraction steam regulating valve 15. The extraction steam unit 3 is used to extract test steam from the high-temperature reheat steam pipelines of No. 1 thermal power unit 1 or No. 2 thermal power unit 2.

[0049] Steam heating unit 5, connected to the steam extraction unit 3, is used to electrically heat the extracted steam to 695~705℃;

[0050] The test turbine unit 6 is connected to the steam heating unit 5 and is used to introduce steam at 695~705℃ for long-term testing of key thermal components of the turbine.

[0051] A drive unit, connected to the test turbine unit, is used to drive the test turbine to run and adjust its speed to achieve variable operating condition testing;

[0052] The steam return treatment unit 7 is connected at one end to the exhaust port of the test turbine unit 6, and at the other end to the boiler ash hopper heating system of thermal power unit 1 and thermal power unit 2 respectively through exhaust valve 8 and exhaust valve 9. It is used to de-temperature and depressurize the test steam and reuse it to the boiler ash hopper heating system of thermal power unit 1 or thermal power unit 2.

[0053] The desuperheater 10 is installed on the exhaust pipe of the test turbine unit 6 and is used to desuperheat and depressurize the steam discharged from the test turbine unit 6.

[0054] The condensate expansion container 13 and the shaft seal cooler 14 are used to receive steam condensate from the steam pipeline and steam leakage from the inner baffle of the steam seal. The shaft seal cooler 14 is used to cool steam leakage from the outer baffle of the steam seal. The drainage from the condensate expansion container 13 and the shaft seal cooler 14 is connected to the cooling tower water supply system.

[0055] The desuperheating water used by the desuperheater 10 is connected to the condensate system of thermal power unit 1 and thermal power unit 2 through desuperheating water branch line 1 and desuperheating water branch line 2 respectively. Desuperheating water branch line 1 and desuperheating water branch line 2 are respectively equipped with desuperheating water shut-off valve 1 and desuperheating water shut-off valve 2.

[0056] The steam extraction unit 3 is equipped with an electric regulating valve 11 and an electric gate valve 12.

[0057] The steam heating unit 5 is a 2MW-class steam electric heater.

[0058] The inlet and outlet steam turbine unit 6 of the test unit uses a high-temperature alloy material with a design temperature of 710℃ for the front part of the desuperheater.

[0059] The drive unit is a 100kW variable speed motor, which is coaxially connected to the test turbine unit 6. The operating conditions of the test turbine unit 6 are controlled by adjusting the speed of the variable speed motor.

[0060] This embodiment is implemented on-site using two 660MW ultra-supercritical single-reheat coal-fired power units. The seismic fortification intensity of the plant site is 6 degrees, the altitude of the plant area is 5.05m (85 National Elevation), and the maximum wind speed during a 50-year return period is 26.8m / s. The newly built test plant is located in the green belt at the northwest corner of the power plant's cooling tower. The plant has a plan dimension of 21.1m×7m, a building height of 7.9m, a fire resistance rating of Class II, a fire hazard rating of Class D, a frame structure, and a design service life of 50 years. The supporting concrete pipe rack connects to the existing integrated pipe rack of the power plant to the west. The existing main and secondary roads, fire lanes, and outdoor fire hydrant system of the plant area are fully reused. All of the projects rely on the renovation of the existing public systems of the power plant. There are no new independent boilers, circulating water systems, or fire protection main systems.

[0061] The two extraction steam branch configuration of extraction steam unit 3:

[0062] The extraction steam branch of Unit 1: taken from the high-temperature reheat pipeline of Unit 1, made of A355P92 steel; equipped with extraction steam shut-off valve, extraction steam regulating valve, temperature measuring point, pressure measuring point, and drain manifold; The extraction steam branch of Unit 2: taken from the high-temperature reheat pipeline of Unit 2, made of A355P92 steel, with valves, measuring points, and drain configuration completely identical to those of the extraction steam branch of Unit 1, achieving full redundancy in extraction steam.

[0063] Extraction steam operating parameters: Original parameters of reheat steam under rated unit conditions: 6.8MPa, 628℃; after the extraction steam branch regulating valve, the pressure is stabilized to 1.0MPa, the rated extraction steam flow rate is 10t / h, and the two extraction steam branches are equipped with interlocking switching logic: when the load of the main unit is <30% or the unit trips / under maintenance, the main extraction steam shut-off valve is automatically closed, and the standby unit extraction steam branch is opened simultaneously. The entire switching process is ≤60s, and the steam pressure fluctuation during the switching process is ≤±0.05MPa.

[0064] Drainage system: The two extraction steam pipelines continuously drain water from their low points and converge to the drainage expansion tank 13. The drainage pipelines are made of A355P92 steel. The drainage expansion tank has a design volume of 2.5m³ and a design pressure of 1.2MPa. It is equipped with condensate desuperheating water spray cooling system. The drainage from the expansion tank flows by gravity to the power plant cooling tower makeup water header.

[0065] Implementation parameters for steam heating unit 5 (2MW steam electric heater):

[0066] 1. Equipment body parameters: Rated heating power 2000kW, 6kV high voltage power supply, rated steam inlet 1.0MPa, 628℃, outlet 1.0MPa, 700℃, rated flow rate 10t / h; heating element adopts nickel-based high temperature alloy electric heating tube, cylinder is lined with HT700P high temperature resistant lining, cylinder design temperature 710℃.

[0067] 2. Electrical Support Implementation: The high-voltage power supply is drawn from the plant's public 6kV A section, with 1250A vacuum circuit breakers installed in each bay. The cables used are ZRC-YJV-6 / 6kV 3×185 copper core flame-retardant cables. It is equipped with independent temperature control and over-temperature interlock protection. When the heater outlet steam temperature is >705℃, the power is automatically reduced, and when it is >710℃, a full-power trip is triggered, and the extraction steam regulating valve is closed slightly.

[0068] 3. Insulation and protection: The heater cylinder is equipped with a 150mm thick high-temperature resistant aluminum silicate insulation layer, and is wrapped with an aluminum alloy protective shell. Contact thermocouples are installed on the surface to prevent personnel from being burned by high temperature. The equipment base is equipped with spring vibration damping supports to reduce the transmission of operating vibration.

[0069] Supplementary equipment and measuring points for Unit 6 of the test steam turbine:

[0070] A small-scale experimental steam turbine customized by Shanghai Steam Turbine Factory was selected. The flow passage section was equipped with key thermal components such as high-temperature alloy blades, rotor discs, and valve bodies to be tested. High-precision displacement, vibration, and temperature sensors were installed at both ends of the rotor. Twenty-four high-temperature thermocouples were arranged in sections of the cylinder to monitor the metal wall temperature in real time, covering the steam inlet side, interstage, exhaust side, and shaft seal area. Creep measuring points and ultrasonic non-destructive testing pre-embedded interfaces were installed in all high-temperature pipelines and the steam turbine body. An online metallographic monitoring module was also provided to record the material microstructure evolution data under long-term operation. The data was connected to the power plant's unified DCS system for storage, with a storage period of ≥10,000 hours.

[0071] Drive unit (100kW variable speed motor):

[0072] 1. Motor parameters: Rated power 100kW, frequency conversion speed regulation range 0~6000r / min, coaxial rigid connection to test turbine rotor, equipped with independent frequency conversion control cabinet, power supply from the 400V MCC section of the factory.

[0073] 2. Operating condition simulation function: It can automatically simulate the full operating conditions of unit start-up and speed-up, stable operation at rated 3000r / min, speed reduction under 50% load change, instantaneous load shedding, and coasting during shutdown, with a speed adjustment accuracy of ±1r / min;

[0074] 3. Interlock protection: Triple protection is set for vibration over-limit, shaft temperature over-limit, and overspeed (>6300r / min). In case of failure, the motor power supply is quickly cut off, and the steam extraction and heating systems are simultaneously reduced in load.

[0075] Steam return processing unit 7: Dual return branches: Branch 1 returns to the boiler ash hopper heating system of thermal power unit 1, and branch 2 returns to the boiler ash hopper heating system of thermal power unit 2. Both branches are on standby simultaneously and are interlocked with the extraction steam branch for switching.

[0076] Desuperheater: Multi-hole spray water mixing desuperheater, spray pipe material 20G, desuperheating water is taken from the unit's condensate system, and two desuperheating water branches are equipped with shut-off valves, flow regulating valves and filters respectively; the rated supply pressure of desuperheating water is 1.2MPa, the water temperature is 32℃, and the maximum spray volume is 1.5t / h. It can reduce the temperature of the turbine exhaust steam from 650℃ to 220℃ before sending it to the ash hopper heating system, completely replacing the original auxiliary steam of the power plant and realizing the cascade utilization of waste heat.

[0077] Shaft seal cooler 14: High-temperature steam leakage from the inner section of the turbine is sent to the condensate expansion tank, while low-temperature steam leakage from the outer section of the shaft seal enters the shaft seal cooler; the closed-loop cooling water is taken from the closed water system of Unit 1 / Unit 2, with dual backup, and the return water after cooling is returned to the unit's closed water header. It is equipped with a shaft seal variable frequency fan to maintain a slight negative pressure in the cooler. The cooler condensate flows by gravity to the cooling tower for water replenishment. The fan is located outdoors in the plant and is equipped with a soundproof cover to reduce noise.

[0078] Example 2

[0079] A test method for key thermal components of a steam turbine at 700℃ includes the following steps:

[0080] S1. Extract test steam from the high-temperature reheat steam pipeline of an existing ultra-supercritical thermal power unit:

[0081] Normal operating mode: Set No. 1 thermal power unit as the main steam source, open the extraction steam shut-off valve of the extraction steam branch of No. 1 thermal power unit, fully open the pipeline drain, and close the drain bypass after the drain expansion tank stops draining continuously.

[0082] Unit maintenance and switching procedure: When Unit 1 needs to be shut down, the switching procedure is triggered as follows: ① Slowly open the extraction steam shut-off valve of the extraction steam branch of Unit 2 to establish a backup steam passage; ② Simultaneously open the exhaust steam shut-off valves of the desuperheating water branch and the return steam reuse branch of Unit 2; ③ Slowly close the extraction steam regulating valve of Unit 1 and simultaneously open the extraction steam regulating valve of Unit 2 to maintain a stable total flow rate of 10t / h; ④ Completely close the extraction steam, return steam, and desuperheating water valves on the side of Unit 1 to complete the switching. The steam flow fluctuation throughout the process is ≤0.5t / h, and the turbine speed is tested without significant disturbance.

[0083] Safety interlock logic: Both extraction steam branches must not be fully closed simultaneously. If any one branch valve fails, the backup branch will automatically open to prevent a malfunction.

[0084] S2. The extracted steam is heated to 700℃ using a steam heating unit:

[0085] Preheating stage: 628℃ steam is first introduced into the steam heating unit and slowly heated to 680℃ at a rate of 50℃ / h. The temperature is kept constant for 2 hours to fully preheat the temperature-controlled pipeline and the test turbine cylinder to eliminate thermal stress.

[0086] Rated heating stage: Continue to increase the temperature to 700℃ at a rate of 30℃ / h, stabilize the temperature for 1 hour, and confirm that the temperature difference at all metal wall temperature measuring points is <15℃ before the test turbine can be introduced to carry out the formal test.

[0087] Temperature fault tolerance control: The allowable temperature range during operation is 695~705℃. If the temperature exceeds the range, the power of the steam heating unit will be automatically adjusted. If the temperature exceeds 710℃, the shutdown protection will be triggered.

[0088] S3. High-temperature steam at 695~705℃ is introduced into the test turbine unit to conduct long-cycle operation tests on the key thermal components of the turbine. The steam inlet pipe of the test turbine unit is made of high-temperature alloy material with a design temperature of 710℃ and a design pressure of 1.2MPa.

[0089] Standard long-cycle test conditions: steam stable at 1.0MPa, 700℃, and flow rate of 10t / h; steam turbine unit rated at 3000r / min continuous operation; single continuous test duration ≥1000h; total test cycle up to 10000h.

[0090] Periodic testing operation: The machine is stopped once every 200 hours to carry out non-destructive testing (ultrasound, metallographic scanning) on ​​high-temperature components and record material microstructure and creep deformation data; after the test is completed, the machine is restarted according to the S2 heating procedure without interrupting the overall test cycle;

[0091] Safety Management: Rigid isolation barriers are installed in high-temperature pipeline areas. When the unit is running at high load, the frequency of on-site inspections is reduced, and remote video inspections are only carried out periodically, relying on DCS remote monitoring.

[0092] S4. Drive the test turbine unit through the drive unit and adjust the speed to simulate different operating conditions:

[0093] Variable load conditions: The speed of the variable speed motor is adjusted in steps between 1500 and 6000 r / min, and each speed is operated stably for 72 hours. The temperature field and stress distribution of the blade and rotor are recorded at different speeds.

[0094] Load shedding simulation: When running at a rated speed of 3000 r / min, the motor drive is instantly cut off to simulate the actual load shedding coasting process of the unit and record the thermal shock data of high-temperature components;

[0095] Start-stop cycle simulation: Automatically completes one full heating-cooling start-stop cycle per day to assess the material's thermal fatigue performance under alternating hot and cold conditions;

[0096] S5. The steam discharged from the test turbine unit is desuperheated and depressurized by a desuperheater and then reused in the boiler ash hopper heating system of the thermal power unit. The desuperheating water used by the desuperheater is taken from the condensate system of thermal power unit No. 1 or thermal power unit No. 2.

[0097] Desuperheating water volume linkage regulation: The opening of the desuperheating water regulating valve is adjusted in real time according to the exhaust steam temperature of the test turbine unit to stabilize the outlet steam at 220℃ for heating the ash hopper;

[0098] Energy recovery calculation: After the rated 10t / h, 700℃ steam does work, all the waste heat of the exhaust steam is recovered, which can save about 240t of auxiliary steam in the power plant per day, significantly reducing the energy consumption of the test operation.

[0099] Hydrostatic synergy: The drains from the desuperheater and shaft seal cooler are uniformly collected into the cooling tower makeup water, with no wastewater discharge;

[0100] S6. Configure dual redundant steam sources for thermal power units No. 1 and No. 2. When the main unit is shut down, it will automatically switch to the standby unit to ensure continuous operation of the test. The switching of the dual redundant steam sources includes the synchronous switching of the extraction steam unit, the return steam treatment unit, and the desuperheating water branch of the desuperheater.

[0101] Pre-switch verification: The DCS automatically detects the steam pressure, condensate pressure, and ash hopper heating pipeline pressure of the standby unit. Switching is only allowed after the conditions are met.

[0102] Switching process parameter constraints: Steam flow fluctuation ≤ 0.5 t / h, temperature fluctuation ≤ ±10℃, and test turbine unit speed fluctuation ≤ ±50 r / min during the switching period;

[0103] Post-switch inspection: After the switch is completed, an operation report is automatically generated, recording the valve status, temperature, and pressure curves of the two systems, and retaining the test data for traceability.

[0104] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A test system for key thermal components of a steam turbine at 700℃, characterized in that, include: Unit 1 (1) and Unit 2 (2) are used for normal thermal power generation within the plant area; the extraction steam unit (3) is connected to the high-temperature reheat steam pipelines of Unit 1 (1) and Unit 2 (2) through two sets of branches, and each set of branches is equipped with an extraction steam shut-off valve (4) and an extraction steam regulating valve (15). The extraction steam unit (3) is used to extract test steam from the high-temperature reheat steam pipelines of Unit 1 (1) or Unit 2 (2); the steam heating unit (5) is connected to the extraction steam unit (3) and is used to electrically heat the extracted steam to a temperature of 695~705℃; the test turbine unit (6) is connected to the steam heating unit (5) and is used to introduce steam at 695~705℃ for steam generation. Long-cycle testing of key thermal components of the turbine; drive unit, connected to the test turbine unit, used to drive the test turbine to run and adjust the speed to achieve variable operating condition testing; return steam treatment unit (7), one end is connected to the exhaust port of the test turbine unit (6), and the other end is connected to the boiler ash hopper heating system of No. 1 thermal power unit (1) and No. 2 thermal power unit (2) respectively through exhaust valve No. 1 (8) and exhaust valve No. 2 (9), used to de-heat and depressurize the steam after the test and reuse it to the boiler ash hopper heating system of No. 1 thermal power unit (1) or No. 2 thermal power unit (2); desuperheater (10), installed on the exhaust pipe of the test turbine unit (6), used to de-heat and depressurize the steam discharged from the test turbine unit (6).

2. The 700℃ steam turbine key thermal component testing system according to claim 1, characterized in that, The desuperheater (10) uses desuperheating water that is connected to the condensate system of thermal power unit 1 and thermal power unit 2 through desuperheating water branch line 1 and desuperheating water branch line 2 respectively. Desuperheating water branch line 1 and desuperheating water branch line 2 are respectively equipped with desuperheating water shut-off valve 1 and desuperheating water shut-off valve 2.

3. The 700℃ steam turbine key thermal component testing system according to claim 2, characterized in that, The extraction unit (3) is equipped with an electric regulating valve (11) and an electric gate valve (12).

4. The 700℃ steam turbine key thermal component testing system according to claim 3, characterized in that, The steam heating unit (5) is a 2MW-class steam electric heater.

5. The 700℃ steam turbine key thermal component testing system according to claim 4, characterized in that, The inlet and outlet steam turbine units (6) of the test turbine unit (6) are made of high-temperature alloy material with a design temperature of 710℃.

6. The 700℃ steam turbine key thermal component testing system according to claim 5, characterized in that, The drive unit is a 100kW variable speed motor, which is coaxially connected to the test turbine unit (6). The operating conditions of the test turbine unit (6) are controlled by adjusting the speed of the variable speed motor.

7. The 700℃ steam turbine key thermal component testing system according to claim 6, characterized in that, It also includes a condensate expansion container (13) and a shaft seal cooler (14). The condensate expansion container (13) is used to receive steam condensate from the steam pipe and steam leakage from the inner baffle of the steam seal. The shaft seal cooler (14) is used to cool steam leakage from the outer baffle of the steam seal. The drainage from the condensate expansion container (13) and the shaft seal cooler (14) is connected to the cooling tower water supply system.

8. A test method for key thermal components of a steam turbine at 700℃, characterized in that, Includes the following steps: S1. Extract test steam from the high-temperature reheat steam pipeline of an existing ultra-supercritical thermal power unit; S2. Heat the extracted steam to 695~705℃ through a steam heating unit; S3. Introduce the high-temperature steam at 695~705℃ into the test turbine unit to conduct long-cycle operation tests on the key thermal components of the turbine. S4. Drive the test turbine unit through the drive unit and adjust the speed to simulate different operating conditions; S5. After the steam discharged from the test turbine unit is de-heated and depressurized by the desuperheater, it is reused in the boiler ash hopper heating system of the thermal power unit; S6. Configure dual redundant steam sources for thermal power unit No. 1 and thermal power unit No.

2. When the main unit is shut down, it will automatically switch to the standby unit to ensure continuous operation of the test.

9. The test method for key thermal components of a steam turbine at 700℃ according to claim 8, characterized in that, In step S2, the steam parameters before heating by the steam heating unit are 6.8 MPa pressure and 628°C temperature, and the steam parameters after heating by the steam heating unit are 1.0 MPa pressure and 700°C temperature, with a steam flow rate of 10 t / h. In step S3, the steam inlet pipe of the test turbine unit is made of high-temperature alloy material with a design temperature of 710°C and a design pressure of 1.2 MPa.

10. The test method for key thermal components of a steam turbine at 700℃ according to claim 9, characterized in that, In step S5, the desuperheating water used by the desuperheater is taken from the condensate system of thermal power unit No. 1 or thermal power unit No.

2. In step S6, when the dual redundant steam sources are switched, the process includes the simultaneous switching of the extraction steam unit, the return steam processing unit, and the desuperheating water branch of the desuperheater.

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