Energy-saving optimization method for starting process of thermal power 660mw unit

Abstract

The present application provides a kind of thermal power 660MW unit starting process energy-saving optimization method, comprising the following steps: S1, boiler cold flushing, S2, boiler hot water flushing, S3, the control of temperature and pressure speed after boiler hot flushing is qualified, S4, the parameter control of car, S5, steam turbine car, S6, unit grid, load, S7, unit load is from 134MW to 200MW, S8, unit load is from 200MW to 335MW and will be coordinated into.The present application is suitable for supercritical unit, unit starting process can effectively avoid the difficulty of large operation amount and large personnel scheduling amount in water filling pressure operation, effectively avoid the influence of running unit safety in starting machine, control water cooling wall stress problem to reduce water filling rate, to achieve the purpose of energy saving.

Description

Technical Field

[0001] This invention relates to the field of energy-saving technology, and in particular to an energy-saving optimization method for the startup process of a 660MW thermal power unit. Background Technology

[0002] With the rapid development of new energy power projects such as wind power, photovoltaic power and hydropower, the survival space of thermal power has been further reduced, and the requirements for energy-saving measures of thermal power units have been further increased.

[0003] Currently, during the unit startup process, there are several issues, such as the initial boiler ignition being limited by the rate of temperature rise of the water-cooled wall metal (mixer outlet water temperature ≤100℃, controlling the rate of temperature rise of the mixer outlet water temperature ≤1.1℃, mainly to prevent the water-cooled wall metal temperature from rising too quickly, causing uneven expansion of the water-cooled wall and resulting in damage), excessively long boiler hot flushing time, and excessively long medium-speed warm-up time, which lead to an excessively long overall unit startup time. Summary of the Invention

[0004] The purpose of this invention is to provide an energy-saving optimization method for the startup process of a 660MW thermal power unit, which can reduce the startup time of the unit and achieve the goal of energy saving and consumption reduction.

[0005] According to the purpose of this invention, an energy-saving optimization method for the start-up process of a 660MW thermal power unit is provided, comprising the following steps:

[0006] S1, Boiler cold flushing

[0007] S1.1 Deaerator steam heating is introduced before the boiler is filled with cold water;

[0008] S1.2 Start the electric feedwater pump or the steam-driven feedwater pump pre-pump to start the boiler water supply;

[0009] After the S1.3 boiler is filled with water, adjust the steam source pressure for deaerator steam heating, and keep the feedwater temperature between 80 and 110°C. After the boiler is full of water, start the boiler water circulation pump.

[0010] After the S1.4 boiler is filled with water, test the boiler water quality.

[0011] After the S1.5 boiler passes the cold flushing test, reduce the feedwater flow rate to 105t / h and maintain the boiler water circulation pump outlet flow rate at no less than 630t / h. The boiler is ready for ignition. During the single-unit start-up process, the start-up boiler is burned to ensure the auxiliary steam source. During the start-up process, the start-up steam enters the cold reheat through the high-pressure bypass, the low-pressure bypass is closed, and the cold reheat is opened to the auxiliary steam header regulating valve to connect the unit's auxiliary steam and generate steam for the shaft seal.

[0012] S2, Boiler hot water flushing

[0013] S2.1 After the boiler is ignited, when the water temperature at the mixer outlet reaches 100℃, control the heating rate of the boiler's third-stage superheater outlet temperature to be ≤2.0℃ / min, control the heating rate of the second-stage reheater outlet temperature to be ≤2.0℃ / min, increase the boiler's third-stage superheater outlet temperature and pressure, and shorten the heating and pressurization time.

[0014] After the S2.2 boiler is ignited, close the air vent valve when the pressure in the water storage tank reaches 0.1-0.2 MPa.

[0015] S2.3 After the boiler is ignited, adjust the matching relationship between the feedwater flow rate and the outlet flow rate of the boiler water circulation pump, and control the opening of the overflow pipe of the water storage tank to the minimum.

[0016] When the outlet water temperature of the boiler mixer reaches 190-210℃, the boiler enters hot water flushing. The feedwater flow rate is increased to 210-420t / h, while the boiler water circulation pump outlet flow rate is controlled at 630t / h and the economizer inlet flow rate is maintained at 1050t / h. The boiler water tank pressure is maintained by adjusting the combustion and using the high and low pressure bypasses, and the mixer outlet water temperature is maintained at 190-210℃ for hot water flushing.

[0017] The outlet water temperature of the mixer in the S2.5 boiler reached 190℃; the boiler water quality was tested.

[0018] After the S2.6 boiler hot flushing is completed, adjust the matching relationship between the feedwater flow rate and the boiler water circulation pump outlet flow rate, and control the opening of the overflow pipe electric regulating valve to the minimum.

[0019] After the S2.7 boiler passes the hot flushing test, the temperature and pressure should be increased in a timely manner according to the unit start-up curve.

[0020] After the S2.8 boiler passes the hot flushing test, the second pulverizing system is started in a timely manner, and the boiler continues to heat up and pressurize.

[0021] S3. Control of heating and pressurization rate after boiler hot flushing is qualified.

[0022] S3.1 When the pressure in the water storage tank reaches 1.2MPa, close the manual and electric drain valves of the superheater system to reduce the boiler steam discharge.

[0023] S3.2 When the steam temperature before the turbine reaches the start-up requirement, boiler desuperheating water is introduced;

[0024] After the S3.3 unit is connected to the grid, the unit load will increase. When the unit load increases to 230-260MW, the boiler will be switched to dry operation.

[0025] S4, Stamping Parameter Control

[0026] S4.1 Main steam pressure 5MPa, main steam temperature ≥360℃, main steam superheat ≥56℃;

[0027] S4.2 Reheat steam pressure 0.8MPa, temperature 320℃, reheat steam superheat ≥56℃;

[0028] S4.3 Check that the high bypass ratio is 60%, and reduce or increase the fuel quantity if the high bypass ratio is greater than 65% or less than 40%.

[0029] S5, Steam Turbine Stamping Machine

[0030] The S5.1 unit is remotely or locally tripped at 400 r / min to perform friction checks;

[0031] S5.2 Reset the steam turbine, set the turbine speed to 2000 rpm, the speed increase rate to 150 rpm / min, and increase the turbine speed.

[0032] S5.3 speed up to 600rpm, check the lubricating oil temperature at 40℃, the low-pressure cylinder automatic water spray valve opens, the eccentric recorder will automatically disengage at 600rpm, and the vibration recorder will start working; the eccentric value should be checked between 400-600rpm; when the speed increases to 1950r / min, the jacking oil pump will be shut down and put into standby mode.

[0033] S5.4 Once the turbine speed reaches 2000 rpm, warm-up begins and lasts for 150 minutes.

[0034] S5.5 When the regulating stage metal temperature is >280℃, the high-pressure and low-pressure expansion difference is within the control range, and the total turbine expansion is 8mm;

[0035] After S5.6 inspection is completed and no abnormalities are found, set the turbine speed to 2900 rpm and the acceleration rate to 200 rpm / min. When the turbine speed reaches 2850 rpm, the acceleration rate will automatically decrease to 50 rpm / min. When the turbine speed reaches 2900 rpm, the acceleration will automatically stop. When it is confirmed that the metal temperature of the steam chamber is greater than the saturated steam temperature under the throttling pressure, the high-pressure main steam valve and high-pressure regulating valve control can be switched.

[0036] During the pressure test, the A-type open water pump was operated, the circulating pump was stopped, the hydraulic butterfly valve at the circulating pump outlet was opened by 10°-15°, the circulating water connection to the shutdown side was opened by 15%-20%, the small turbine and the booster pump were stopped, without disrupting the vacuum, and the shaft seals of the main unit and the small turbine were kept engaged, maintaining the vacuum at -78KPA. The temperature difference between the upper and lower cylinders of the main unit and the small turbine, as well as the exhaust temperature, were all within the normal range.

[0037] S5.7 sets the target speed to 3000 r / min and the acceleration rate to 50 rpm / min. When the speed is increased to a constant speed, the main steam temperature is maintained at 420℃ and the reheat steam temperature is maintained at 360℃.

[0038] The S5.8 steam turbine speed was increased to 3000 r / min and operated stably for 30 minutes before the low-pressure heater was put into operation.

[0039] S6. Unit connected to the grid, under load.

[0040] The S6.1 generator is connected to the grid with an initial load of 33MW. The generator is warmed up according to the unit's cold start curve for 30 minutes.

[0041] S6.2 unit warms up at 33MW load for 30 minutes. After the unit finishes warming up at low load, the main steam temperature is 450℃ and the reheat temperature is 390℃.

[0042] S6.3 load 33MW warm-up completed;

[0043] S7, unit load increased from 134MW to 200MW

[0044] S7.1 sets the target load to 200MW, the load increase rate to 3MW / min, the maximum load limit to 660MW, and the minimum load limit to 134MW on the coordination screen;

[0045] When the S7.2 unit load reaches 200MW, the main steam pressure is maintained at 8.92MPa, the main steam temperature at 500℃, and the reheat temperature at 430℃.

[0046] When the S7.3 unit is warmed up for 30 minutes at a load of 200MW, the main steam temperature should rise to 520℃ and the reheat steam temperature should rise to 450℃ after the 200MW warm-up is completed.

[0047] S8, the unit load will be increased from 200MW to 335MW and will be put into operation in a coordinated manner.

[0048] Furthermore, in S1, the boiler cold flushing time is controlled to be carried out 4 hours before boiler ignition.

[0049] Furthermore, in S1.2, the boiler water filling time is controlled to be carried out 8 hours before boiler ignition.

[0050] Furthermore, in S1.3, after the boiler water circulation pump starts normally, the outlet flow rate of the boiler water circulation pump is increased to control the outlet flow rate of the boiler water circulation pump to ≥630t / h, the feedwater flow rate is adjusted to 400t / h, and the economizer inlet flow rate is maintained at 1050t / h to perform high-flow-rate high-speed circulation cleaning of the boiler water-cooled wall heating surface. During the cold flushing process of the boiler, the feedwater temperature is increased to 80-110℃, and the boiler mixer outlet water temperature is gradually increased to 100℃. The circulating water in the heat pump is guided to the water injection tower basin, and the replenishment water flow rate is controlled by the electric valves at the inlet and outlet of the heat pump.

[0051] Furthermore, in S1, when the flow rate of the steam-driven feedwater pump pre-pump cannot meet the requirements of the boiler cold flushing during S1.5, the steam pump pre-pump is started to supply water to the boiler.

[0052] Furthermore, in S1, during the boiler cold water flushing process in S1.7, when the iron content of the water sampled from the overflow pipe is ≥1000mg / L, the boiler water in the condensate tank is discharged to the No.1 unit water tower; when the iron content of the water sampled from the overflow pipe is <1000mg / L, the boiler water in the condensate tank is recycled to the No.1 unit condenser for closed-loop cleaning of the unit.

[0053] Furthermore, in S3.1, when the temperature before the reheater desuperheater is ≥200℃, the electric and manual drain valves of the secondary reheater inlet header are closed to reduce steam emissions.

[0054] Furthermore, in S3, after the boiler hot flushing is completed, the main steam pressure, main steam temperature, reheater pressure, and reheater temperature are quickly raised to the turbine flushing parameter requirements:

[0055] Main steam pressure 0.60~1.08MPa, pressurization rate controlled ≤0.03MPa / min;

[0056] Main steam pressure 1.08~1.85MPa, pressurization rate controlled ≤0.05MPa / min;

[0057] Main steam pressure 1.85~3.00MPa, pressurization rate controlled ≤0.075MPa / min;

[0058] Main steam pressure 3.00~6.50MPa, pressurization rate controlled ≤0.10MPa / min;

[0059] Main steam pressure is 6.50~8.92MPa, and the pressure increase rate is controlled to be ≤0.08MPa / min.

[0060] Furthermore, in S5, with the turbine speed at 3000 rpm, the following checks are performed:

[0061] S5.9.1 Confirm that the DEH speed control is stable and confirm that all tests before the unit is connected to the grid are completed;

[0062] S5.9.2 Check and confirm that the main oil pump outlet oil pressure is approximately 2.0 MPa and the inlet oil pressure is approximately 0.23 MPa. Check and confirm that the diaphragm valve oil pressure is 0.8 MPa. Stop starting the oil pump.

[0063] S5.9.3 If the lubricating oil pressure is normal and stable, and the AC lubricating oil pump current decreases, stop the high-pressure sealing oil pump and the AC lubricating oil pump.

[0064] Furthermore, in S6.3, after the warm-up is completed, the maximum rate of temperature rise in the regulating stage chamber is not more than 110℃ / hour; the temperature difference between the inner surface of the horizontal flange of the high and medium pressure outer cylinder and the bolts of the horizontal flange is not more than 100℃.

[0065] The technical solution of this invention is applicable to supercritical units. During the unit startup process, it can effectively avoid the difficulties of large water pressure operation and large personnel scheduling. At the same time, it can effectively avoid affecting the safety of the operating unit during startup, control the water supply rate to reduce the stress on the water-cooled wall, and achieve the purpose of energy saving. Detailed Implementation

[0066] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0067] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0068] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] Example 1

[0070] An energy-saving optimization method for the start-up process of a 660MW thermal power unit includes the following steps:

[0071] S1, Boiler cold flushing

[0072] S1.1 Before the boiler is filled with cold water, the deaerator is put into operation to heat the steam and increase the feedwater temperature. The feedwater temperature is controlled appropriately according to the boiler heating surface wall temperature.

[0073] When the boiler is ready for water filling, start the electric feedwater pump or the steam-driven feedwater pump pre-pump to fill the boiler with water. The boiler water filling time should be controlled 8 hours before the boiler is ignited.

[0074] After the boiler is filled with water (S1.3), adjust the steam source pressure for deaerator steam heating to prevent the feedwater temperature from dropping and ensure it is between 80 and 110°C to guarantee the effectiveness of cold water flushing. After the boiler is full (water level in the storage tank ≥ 9.7 meters), start the boiler water circulation pump. Once the pump is running normally, increase the outlet flow rate to ≥ 630 t / h. Adjust the feedwater flow rate to approximately 400 t / h and maintain the economizer inlet flow rate at approximately 1050 t / h to perform high-flow-rate high-speed circulation cleaning of the boiler water-cooled wall heating surfaces, improving the cold water flushing effect. During the cold flushing process, increase the feedwater temperature to 80–110°C to prevent a drop in feedwater temperature from affecting the cold flushing effect. Gradually increase the boiler mixer outlet water temperature to 100°C. Increase the feedwater temperature to raise the water-cooled wall metal temperature and mixer outlet water temperature. Use a "no-fire start" instead of the initial low-temperature fuel oil time during ignition.

[0075] S1.4 The cold flushing time of the boiler shall be controlled to be 4 hours before the boiler is ignited.

[0076] If the flow rate of the steam-driven feedwater pump pre-pump cannot meet the requirements of the boiler cold flushing during the S1.5 boiler cold flushing process, the steam pump pre-pump will be started to supply water to the boiler. This can save energy and also better control the water supply speed.

[0077] After maintenance, the circulating water tower basin is filled with water through the circulating water return water connection valve. Since the water flow rate of the circulating water tower basin cannot be monitored after the return water connection is opened, an increase in the water flow rate may cause the liquid level in the circulating water forebay on the operating side to drop rapidly, affecting the safe operation of the circulating pump. After adding a heat pump, the circulating water in the heat pump can be diverted to the tower basin that needs water filling. The water replenishment flow rate can also be controlled by the electric valves at the inlet and outlet of the heat pump. This can reduce the need to start the water replenishment pump at the water source for centralized water replenishment and reduce the water filling time of the tower basin by 5-6 hours.

[0078] After the S1.6 boiler is filled with water (water level in the storage tank ≥ 9.7 meters), chemical testing personnel should test the boiler water quality. During the boiler cold water flushing process, the number of boiler water tests should be increased to avoid waste of boiler water due to untimely water quality testing.

[0079] During the cold water flushing process of boiler S1.7, when the iron content of the water sampled from the overflow pipe is ≥1000mg / L, the boiler water in the start-up condensate tank will be discharged to the No.1 unit water tower; when the iron content of the water sampled from the overflow pipe is <1000mg / L, the boiler water in the start-up condensate tank will be promptly recovered to the No.1 (No.2) condenser (no longer discharged) for closed-loop cleaning of the unit.

[0080] After the S1.8 boiler passes the cold flushing test, reduce the feedwater flow rate to 105t / h and maintain the boiler water circulation pump outlet flow rate at no less than 630t / h. The boiler is then ready for ignition.

[0081] During the initial startup of a single unit, since there is no steam source in the auxiliary steam header and no steam supply to the unit's shaft seals, the start-up boiler can be used to ensure the auxiliary steam source, thereby reducing coal consumption and increasing power consumption. During startup, the startup steam enters the cooling reheat through the high-pressure bypass, the low-pressure bypass is closed slightly, and the cooling reheat valve is opened wide to the auxiliary steam header regulating valve, connecting to the unit's auxiliary steam to generate steam for the shaft seals.

[0082] S2, Boiler hot water flushing

[0083] S2.1 After the boiler is ignited, when the water temperature at the mixer outlet reaches 100℃, the boiler heating rate is increased, the heating rate of the boiler's third-stage superheater outlet is controlled to be ≤2.0℃ / min, the heating rate of the second-stage reheater outlet is controlled to be ≤2.0℃ / min, the boiler's third-stage superheater outlet temperature and pressure are increased, and the heating and pressurization time is shortened.

[0084] After the S2.2 boiler is ignited, the air vent valve should be closed when the pressure in the water storage tank reaches 0.1 to 0.2 MPa to prevent unnecessary steam waste.

[0085] S2.3 After the boiler is ignited, adjust the matching relationship between the feedwater flow rate and the boiler water circulation pump outlet flow rate according to the boiler steam production requirements, control the overflow pipe opening of the water storage tank to the minimum (preferably control the electric regulating valve opening of the water storage tank overflow pipe to 0%), and reduce the feedwater flow rate.

[0086] When the outlet water temperature of the boiler mixer reaches 190-210℃, the boiler enters hot water flushing. The feedwater flow rate is increased to 210-420t / h, while the outlet flow rate of the boiler water circulation pump is controlled at about 630t / h, and the inlet flow rate of the economizer is maintained at 1050t / h. The pressure of the boiler water tank is maintained by adjusting the combustion and using the high and low pressure bypasses, and the outlet water temperature of the mixer is maintained at 190-210℃ for hot water flushing.

[0087] When the outlet water temperature of the mixer in the S2.5 boiler reaches 190℃, chemical testing personnel will test the boiler water quality and increase the frequency of boiler water testing to prevent the boiler hot flushing time from being too long due to untimely boiler water testing.

[0088] After the S2.6 boiler hot flushing is completed, adjust the matching relationship between the feedwater flow rate and the boiler water circulation pump outlet flow rate, and control the opening of the overflow pipe electric regulating valve to the minimum to prevent the boiler drainage from being too large and affecting the boiler heating and pressurization speed.

[0089] After the S2.7 boiler passes the hot flushing test, the temperature and pressure should be increased in a timely manner according to the unit start-up curve. It is forbidden to stay at the hot flushing parameters for a long time.

[0090] After the S2.8 boiler passes the hot flushing test, the second pulverizing system is started in a timely manner (fuel is added in a timely manner according to the rate of increase of steam temperature and steam pressure during the start-up process, and the pulverizing system is started in a timely manner according to the coal quality and combustion conditions), and the boiler continues to increase temperature and pressure.

[0091] S3. Control of heating and pressurization rate after boiler hot flushing is qualified.

[0092] S3.1 When the pressure in the water storage tank reaches 1.2MPa, close the manual and electric drain valves of the superheater system to reduce the boiler steam discharge; when the temperature before the reheater desuperheater is ≥200℃, close the electric and manual drain valves of the secondary reheater inlet header to reduce the steam discharge.

[0093] S3.2 When the steam temperature before the machine reaches the start-up requirement, boiler desuperheating water is introduced to prevent the boiler pressure rise from being affected by the steam temperature exceeding the start-up parameters.

[0094] After the S3.3 boiler hot flushing is completed, quickly raise the main steam pressure, main steam temperature, reheater pressure, and reheater temperature to the turbine flushing parameter requirements:

[0095] Main steam pressure is 0.60~1.08MPa, and the pressure increase rate is controlled to be ≤0.03MPa / min.

[0096] Main steam pressure is 1.08~1.85MPa, and the pressure increase rate is controlled to be ≤0.05MPa / min.

[0097] Main steam pressure is 1.85~3.00MPa, and the pressure increase rate is controlled to be ≤0.075MPa / min.

[0098] Main steam pressure is 3.00~6.50MPa, and the pressure increase rate is controlled to be ≤0.10MPa / min.

[0099] Main steam pressure is 6.50~8.92MPa, and the pressure increase rate is controlled to be ≤0.08MPa / min.

[0100] After the S3.4 unit is connected to the grid, the unit load increases. When the unit load increases to 230-260MW, the boiler should be switched to dry operation in a timely manner.

[0101] S4, Stamping Parameter Control

[0102] S4.1 Main steam pressure 5MPa, main steam temperature ≥360℃, main steam superheat ≥56℃.

[0103] S4.2 Reheat steam pressure 0.8MPa, temperature 320℃, reheat steam superheat ≥56℃.

[0104] S4.3 Check that the high bypass ratio is around 60%. If the high bypass ratio is greater than 65% or less than 40%, reduce or increase the fuel quantity accordingly.

[0105] S5, Steam Turbine Stamping Machine

[0106] The S5.1 unit was remotely or locally tripped at 400 r / min for friction checks. The high and medium pressure automatic main steam valves and regulating valves were checked and found to be closed, resulting in a decrease in turbine speed. Local checks revealed no metallic friction sounds inside the turbine and at the shaft seals. The generator sound was listened to and found to be normal. Bearing oil flow and unit vibration were checked and found to be good.

[0107] S5.2 Reset the turbine, set the turbine start-up speed to 2000 rpm, and the speed increase rate to 150 rpm / min. Press "Proceed" to increase the turbine speed. Monitor the turbine speed increase on the CRT. When the speed exceeds the critical point, the increase rate will automatically increase to 300 r / min.

[0108] S5.3 speed up to 600 rpm, check lubricating oil temperature (40℃), low-pressure cylinder automatic water spray valve opens. At approximately 600 rpm, the eccentric recorder will automatically disengage, and the vibration recorder will start working. Eccentricity value should be checked between 400-600 rpm. When the speed reaches 1950 r / min, the jacking oil pump is shut down and put into standby mode. Check the vibration value of the recording unit when it exceeds the critical speed.

[0109] S5.4 After the turbine speed reaches 2000 rpm, warm-up begins, which typically takes about 150 minutes. However, due to reduced turbine start-up parameters and increased steam flow, the warm-up time may be shortened. Also, if warm-up is too rapid, vibrations in the 1st and 2nd watts will increase. If the vibration is less than 80 μm, the unit's heating rate can be maintained. If the vibration is greater than 100 μm, the heating rate can be appropriately reduced to prevent the unit's expansion from lagging behind due to rapid heating, which could cause abnormalities in the 1st and 2nd watts due to prolonged vibration. During warm-up, the main steam temperature can rise to 420℃, but the temperature rise rate must not exceed 55℃ / hour. To avoid turbine resonance, constant speed within the critical speed range is prohibited. Critical speeds of steam turbines: First critical speed 780-880 rpm; Second critical speed 1450-1700 rpm; Third critical speed 2150-2250 rpm. At this time, the opening of the high-pressure cylinder start-up discharge valve should be adjusted to control the high-pressure discharge temperature to be less than 300℃. Note that the high-pressure discharge desuperheating water should be put in.

[0110] S5.5 When the regulating stage metal temperature > 280℃ (approximately 2 hours for medium-speed warm-up, check if it can be achieved), the high-pressure and low-pressure expansion difference is within the control range, and the total turbine expansion is 8mm. Warm-up ends when all control indicators are within limits and relatively stable. During medium-speed warm-up, the main reheat steam temperature is appropriately increased according to boiler requirements to meet the regulating stage temperature rise requirements.

[0111] After the boiler heating surface anti-wear and anti-explosion inspection is completed during unit shutdown, the primary and secondary steam systems must be pressurized and leak checked. During the pressure test, the turbine does not need to run continuously. This allows the unit vacuum to be broken, stopping the shaft seal steam supply and shutting down the relevant cooling water system on the turbine side. When restarting the turbine, the corresponding cooling water system on the turbine side needs to be activated, and the shaft seal needs to be engaged to establish a vacuum. The above process involves repetitive operations, delaying the primary steam-water pressure test by 3-4 hours and increasing the workload for operators. Without breaking the vacuum, the power consumption of the booster pump and circulating pump increases. To address this, the A-type open water pump is operated, the circulating pump is stopped, the circulating pump outlet hydraulic butterfly valve is opened 10°-15°, the circulating water connection on the shutdown side is opened 15%-20%, the turbine and booster pump are stopped, and the vacuum is maintained at -78 kPa without breaking the vacuum. The temperature difference between the upper and lower cylinders of the main unit and the turbine, as well as the exhaust temperature, are all within the normal range.

[0112] After S5.6 inspection is completed and no abnormalities are found, the turbine start-up speed is set to 2900 rpm, with an acceleration rate of 200 rpm / min. The acceleration rate automatically decreases to 50 rpm / min after the turbine speed reaches 2850 rpm. The acceleration automatically stops at 2900 rpm. Referring to the "Turbine Inlet Steam Status," confirm that the metal temperature of the steam chamber is greater than the saturated steam temperature under throttling pressure before switching between the high-pressure main steam valve and the high-pressure regulating valve. After the DEH issues the TV / GV switching command, the GV initially closes at a rate of 0.4% / s (adjustable). When the GV affects the turbine speed, the TV opens at 1% / s. When the TV opening reaches 100%, the turbine speed is controlled by the GV, and the TV / GV switching ends. Local checks show that with the TV fully open and the GV in regulation mode, the turbine speed will remain around 2900 RPM.

[0113] S5.7 Set the target speed to 3000 r / min and the acceleration rate to 50 rpm / min, then click "Proceed". Once the speed reaches the constant point, maintain the main steam temperature at 420℃ and the reheat steam temperature at 360℃.

[0114] After the S5.8 turbine speed reaches 3000 r / min and runs stably for 30 minutes, low-pressure heaters #5 and #6 are engaged. During the engagement of low-pressure heaters #5 and #6, the boiler fuel quantity can be appropriately increased to prevent a drop in main steam pressure.

[0115] When the S5.9 turbine speed is 3000 rpm, perform the following checks:

[0116] S5.9.1 Confirm that the DEH speed control is stable and confirm that all tests before the unit is connected to the grid are completed.

[0117] S5.9.2 Check and confirm that the main oil pump outlet oil pressure is approximately 2.0 MPa and the inlet oil pressure is approximately 0.23 MPa. Check and confirm that the diaphragm valve oil pressure is 0.8 MPa. Stop starting the oil pump. Note that the diaphragm valve oil pressure fluctuation is not significant.

[0118] S5.9.3 If the lubricating oil pressure is normal and stable, and the AC lubricating oil pump current decreases, stop the high-pressure sealing oil pump and the AC lubricating oil pump.

[0119] S6. Unit connected to the grid, under load.

[0120] The S6.1 generator is connected to the grid with an initial load of 33MW. Warm-up is performed according to the unit's cold start curve, taking 30 minutes. If the medium-speed warm-up time is too short, the total turbine expansion will be less than 8mm, and the vibration of the 1st and 2nd watts of the main turbine will be significant, requiring a warm-up time of 30-40 minutes. At this point, the main steam pressure reaches 8.93MPa.

[0121] S6.2 unit warms up for 30 minutes at a low load of 33MW. After the low-load warm-up, the main steam temperature is 450℃, and the reheat temperature is 390℃. This warm-up stage is to eliminate residual stress caused by uneven expansion and heating during the start-up phase. It also compensates for the short warm-up time at medium speed, which may have resulted in insufficient turbine expansion.

[0122] After the S6.3 load of 33MW has finished warming up, further load increases should be applied to control the temperature rise rate of the regulating stage chamber to not exceed 110℃ / hour; the temperature difference between the inner surface of the horizontal flange of the high-pressure outer cylinder and the bolts of the horizontal flange should not exceed 100℃.

[0123] S7, unit load increased from 134MW to 200MW

[0124] S7.1 sets the target load to 200MW, the load increase rate to 3MW / min, the maximum load limit to 660MW, and the minimum load limit to 134MW on the coordination screen.

[0125] When the S7.2 unit load reaches 200MW, the main steam pressure is maintained at 8.92MPa, the main steam temperature at 500℃, and the reheat temperature at 430℃.

[0126] The S7.3 unit should be warmed up for 30 minutes at a load of 200MW. After the 200MW warm-up is completed, the main steam temperature should rise to 520℃ and the reheat steam temperature should rise to 450℃. This warm-up stage is to eliminate residual stress caused by uneven expansion and heating of the unit during the start-up phase.

[0127] S8, the unit load will be increased from 200MW to 335MW and will be put into operation in a coordinated manner.

[0128] This invention is applicable to supercritical units. During unit startup, it effectively avoids the difficulties of large-scale water pressurization operations and personnel scheduling. Simultaneously, it effectively prevents disruptions to the operating unit's safety during startup, controls the water supply rate to reduce stress on the water-cooled walls, and achieves energy savings. It ensures safe unit startup, shortens startup time, and guarantees the rapid commissioning of the denitrification and desulfurization systems to meet emission requirements. It also ensures that major pollutant indicators such as sulfides, nitrogen oxides, and particulate matter do not exceed limits.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing energy saving during the startup process of a 660MW thermal power unit, characterized in that, Includes the following steps: S1, Boiler cold flushing S1.1 Deaerator steam heating is introduced before the boiler is filled with cold water; S1.2 Start the electric feedwater pump or the steam-driven feedwater pump pre-pump to start the boiler water supply; S1.3 After the boiler is filled with water, adjust the steam source pressure for deaerator steam heating, and maintain the feedwater temperature at 80-110℃. After the boiler is full of water, start the boiler water circulation pump. In this step S1.3, after the boiler water circulation pump starts normally, increase the boiler water circulation pump outlet flow rate to control it to ≥630t / h. Adjust the feedwater flow rate to 400t / h and maintain the economizer inlet flow rate at 1050t / h to perform high-flow-rate high-speed circulation cleaning of the boiler water-cooled wall heating surface. During the cold flushing process, increase the feedwater temperature to 80-110℃ and gradually increase the boiler mixer outlet water temperature to 100℃. The circulating water in the heat pump is guided to the water injection tower basin, and the makeup water flow rate is controlled by the electric valves at the inlet and outlet of the heat pump. After the S1.4 boiler is filled with water, test the boiler water quality. After the S1.5 boiler passes the cold flushing test, reduce the feedwater flow rate to 105t / h and maintain the boiler water circulation pump outlet flow rate at no less than 630t / h. The boiler is ready for ignition. During the single-unit start-up process, the start-up boiler is burned to ensure the auxiliary steam source. During the start-up process, the start-up steam enters the cold reheat through the high-pressure bypass, the low-pressure bypass is closed, and the cold reheat is opened to the auxiliary steam header regulating valve to connect the unit's auxiliary steam and generate steam for the shaft seal. During the boiler cold water flushing process, when the iron content of the water sampled from the overflow pipe is ≥1000mg / L, the boiler water in the condensate tank is discharged to the No.1 unit water tower; when the iron content of the water sampled from the overflow pipe is <1000mg / L, the boiler water in the condensate tank is recycled to the No.1 unit condenser for closed-loop cleaning of the unit. S2, Boiler hot water flushing S2.1 After the boiler is ignited, when the outlet water temperature of the mixer rises to 100℃, control the heating rate of the boiler's third-stage superheater outlet temperature to be ≤2.0℃ / min, control the heating rate of the second-stage reheater outlet temperature to be ≤2.0℃ / min, increase the outlet temperature and pressure of the boiler's third-stage superheater, and shorten the heating and pressurization time. After the S2.2 boiler is ignited, close the air vent valve when the pressure in the water storage tank reaches 0.1-0.2 MPa. S2.3 After the boiler is ignited, adjust the matching relationship between the feedwater flow rate and the outlet flow rate of the boiler water circulation pump, and control the opening of the overflow pipe of the water storage tank to the minimum. When the outlet water temperature of the boiler mixer reaches 190-210℃, the boiler enters hot water flushing. The feedwater flow rate is increased to 210-420t / h, while the boiler water circulation pump outlet flow rate is controlled at 630t / h and the economizer inlet flow rate is maintained at 1050t / h. The boiler water tank pressure is maintained by adjusting the combustion and using the high and low pressure bypasses, and the mixer outlet water temperature is maintained at 190-210℃ for hot water flushing. The outlet water temperature of the mixer in the S2.5 boiler reached 190℃; the boiler water quality was tested. After the S2.6 boiler hot flushing is completed, adjust the matching relationship between the feedwater flow rate and the boiler water circulation pump outlet flow rate, and control the opening of the overflow pipe electric regulating valve to the minimum. After the S2.7 boiler passes the hot flushing test, the temperature and pressure should be increased in a timely manner according to the unit start-up curve. After the S2.8 boiler passes the hot flushing test, the second pulverizing system is started in a timely manner, and the boiler continues to heat up and pressurize. S3. Control of heating and pressurization rate after boiler hot flushing is qualified. S3.1 When the pressure in the water storage tank reaches 1.2MPa, close the manual and electric drain valves of the superheater system to reduce the boiler steam discharge. S3.2 When the steam temperature before the turbine reaches the start-up requirement, boiler desuperheating water is introduced; After the S3.3 unit is connected to the grid, the unit load will increase. When the unit load increases to 230-260MW, the boiler will be switched to dry operation. S4, Stamping Parameter Control S4.1 Main steam pressure 5MPa, main steam temperature ≥360℃, main steam superheat ≥56℃; S4.2 Reheat steam pressure 0.8MPa, temperature 320℃, reheat steam superheat ≥56℃; S4.3 Check that the high bypass ratio is 60%, and reduce or increase the fuel quantity if the high bypass ratio is greater than 65% or less than 40%. S5, Steam Turbine Stamping Machine The S5.1 unit is remotely or locally tripped at 400 r / min to perform friction checks; S5.2 Reset the steam turbine, set the turbine speed to 2000 rpm, the speed increase rate to 150 rpm / min, and increase the turbine speed. S5.3 speed up to 600rpm, check lubricating oil temperature at 40℃, low-pressure cylinder automatic water spray valve opens, eccentric recorder automatically disengages at 600rpm, vibration recorder starts working; eccentricity value should be checked between 400-600rpm; when speed reaches 1950r / min, jacking oil pump is shut down and put into standby. S5.4 Once the turbine speed reaches 2000 rpm, warm-up begins and lasts for 150 minutes. S5.5 When the regulating stage metal temperature is >280℃, the high-pressure and low-pressure expansion difference is within the control range, and the total turbine expansion is 8mm; After S5.6 inspection is completed and no abnormalities are found, set the turbine speed to 2900 rpm and the acceleration rate to 200 rpm / min. When the turbine speed reaches 2850 rpm, the acceleration rate will automatically decrease to 50 rpm / min. When the turbine speed reaches 2900 rpm, the acceleration will automatically stop. When it is confirmed that the metal temperature of the steam chamber is greater than the saturated steam temperature under throttling pressure, the high-pressure main steam valve and high-pressure regulating valve control can be switched. S5.7 sets the target speed to 3000 r / min and the acceleration rate to 50 rpm / min. When the speed is increased to a constant speed, the main steam temperature is maintained at 420℃ and the reheat steam temperature is maintained at 360℃. The S5.8 steam turbine speed was increased to 3000 r / min and operated stably for 30 minutes before the low-pressure heater was put into operation. S6. Unit connected to the grid, under load. The S6.1 generator is connected to the grid with an initial load of 33MW. The generator is warmed up according to the unit's cold start curve for 30 minutes. S6.2 unit warms up at 33MW load for 30 minutes. After the unit finishes warming up at low load, the main steam temperature is 450℃ and the reheat temperature is 390℃. S6.3 load 33MW warm-up completed; S7, unit load increased from 134MW to 200MW S7.1 sets the target load to 200MW, the load increase rate to 3MW / min, the maximum load limit to 660MW, and the minimum load limit to 134MW on the coordination screen; When the S7.2 unit load reaches 200MW, the main steam pressure is maintained at 8.92MPa, the main steam temperature at 500℃, and the reheat temperature at 430℃. When the S7.3 unit is warmed up for 30 minutes at a load of 200MW, the main steam temperature should rise to 520℃ and the reheat steam temperature should rise to 450℃ after the 200MW warm-up is completed. S8, the unit load increased from 200MW to 335MW and the boiler-turbine coordinated control operation mode was put into operation.

2. The energy-saving optimization method for the start-up process of a 660MW thermal power unit according to claim 1, characterized in that, In S3.1, when the temperature before the reheater desuperheater is ≥200℃, the electric and manual drain valves of the secondary reheater inlet header are closed to reduce steam emissions.

3. The energy-saving optimization method for the start-up process of a 660MW thermal power unit according to claim 1, characterized in that, In S3, after the boiler hot flushing is completed in S3.3, the main steam pressure, main steam temperature, reheater pressure, and reheater temperature are quickly raised to the turbine flushing parameter requirements: Main steam pressure 0.60~1.08MPa, pressurization rate controlled ≤0.03MPa / min; Main steam pressure 1.08~1.85MPa, pressurization rate controlled ≤0.05MPa / min; Main steam pressure 1.85~3.00MPa, pressurization rate controlled ≤0.075MPa / min; Main steam pressure 3.00~6.50MPa, pressurization rate controlled ≤0.10MPa / min; Main steam pressure is 6.50~8.92MPa, and the pressure increase rate is controlled to be ≤0.08MPa / min.

4. The energy-saving optimization method for the start-up process of a 660MW thermal power unit according to claim 1, characterized in that, In S6.3, after the warm-up is completed, the maximum rate of temperature rise in the regulating stage chamber should not exceed 110℃ / hour; the temperature difference between the inner surface of the horizontal flange of the high and medium pressure outer cylinder and the bolts of the horizontal flange should not exceed 100℃.