Steam extraction and belt connection system suitable for daily start-stop period of electric power spot mode unit and operation method of steam extraction and belt connection system

Abstract

The invention discloses a steam extraction connecting belt system adapting to the intraday start-stop period of an electric power spot mode unit and an operation method, and relates to the field of energy electric power. During intraday start-stop peak regulation of a thermal power unit, steam generated by a boiler is supplied to the outside through industrial steam extraction by commissioning a high-low bypass connecting belt in a shutdown and non-boiler-shutdown mode; and steam resources are fully utilized. The system is characterized in that a boiler main steam pipeline is connected with a high-pressure bypass, a branch of the high-pressure bypass is communicated with a turbine high-pressure cylinder, and steam after acting enters a boiler reheater and is communicated with a water outlet main pipe of a three-stage high-pressure heater; a boiler reheater is connected with a steam turbine medium-pressure cylinder through a pipeline, the gas outlet end of the medium-pressure cylinder is divided into two paths, one path is communicated with a low-pressure cylinder, the other path is communicated with a heating gas extraction mother pipe, and a reheater outlet pipeline is branched into a low-pressure bypass which can be used for punching and extracting steam to an industrial gas extraction mother pipe. The steam utilization rate and the unit flexibility and economy are improved, and safe and stable operation of the system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of energy and electricity, and in particular to a steam extraction connection system and an operation method adapted to the daily start and stop period of a power spot mode unit. Background Art

[0002] With the vigorous development of new energy, the utilization hours of thermal power units are decreasing year by year due to the influence of wind power and photovoltaic power. In particular, the large-scale operation of photovoltaic power stations is subject to the promotion of energy storage technology. In order to increase the amount of photovoltaic power grid-connected electricity, the load of thermal power units is gradually reduced during the day, and the output of new energy is reduced at night. Thermal power plants need to increase their output and operate, and thermal power units need to cooperate to connect more loads before the evening peak. Therefore, it has become normal for thermal power plants to start and stop peak load regulation during the day.

[0003] At present, in the spring and autumn seasons when the output of new energy is large, thermal power units need to start and stop during the day to adjust the peak in some periods, and the general downtime is about 4-6 hours. If the shutdown method is adopted, it takes 4 hours from the ignition of the boiler to the start-up conditions. During the temperature and pressure increase period, the air exhaust and main steam pipeline drainage need to be opened. During this period, the steam generated by the boiler cannot be used, and there is a situation where the steam flow is small and the temperature and pressure increase are slow. The time from ignition to parallel operation of the unit is long, and the flexibility and economy of the unit in adapting to the spot market are reduced.

[0004] A system is designed to supply external heat by putting high and low bypass industrial extraction steam into operation during the daily start-up and shutdown peak-shaving period of thermal power units. The steam generated by the boiler during this period is kept to meet the turbine start-up requirements, and the steam parameters during the extraction period are kept to meet the turbine start-up requirements. This system is expected to fully utilize the steam during the daily start-up and shutdown peak-shaving period and solve the problems of poor flexibility and reduced economy of the units in adapting to the spot market. Summary of the invention

[0005] The purpose of the present invention is to provide a steam extraction connection system and operation method that is adaptable to the daily start-up and shutdown period of the power spot mode unit. During the daily start-up and shutdown peak regulation period of the unit, the unit is shut down without stopping the boiler, and high and low bypass industrial steam extractions are put into operation to supply heat to the outside with the steam generated by the boiler, and the main and re-steam parameters during the steam extraction are maintained to meet the turbine start-up requirements, so as to fully utilize the steam during the daily start-up and shutdown peak regulation to solve the above-mentioned problems.

[0006] To achieve the above object, the present invention provides the following technical solutions: A steam extraction and connection system adapted to the daily start-up and shutdown of power spot mode units, including a boiler main steam pipeline, characterized in that the boiler main steam pipeline is connected to a high-pressure bypass, the high-pressure bypass is branched into two pipelines, and are respectively connected to the air inlet ends on both sides of the high-pressure cylinder of the steam turbine, and the high-pressure cylinder of the steam turbine is passed to the boiler reheater through the residual steam channel after working; the high-pressure cylinder of the steam turbine works under the impetus of steam, and the steam after working still has a certain amount of energy, and enters the boiler reheater through the residual steam channel for reheating to increase the temperature and energy of the steam, in preparation for the subsequent work process. The residual steam channel is also connected to the outlet mother pipe of the three-stage high-pressure heater; The boiler reheater is connected to the turbine intermediate pressure cylinder through the reheater outlet pipe, and the turbine intermediate pressure cylinder outlet end is divided into two paths, one is connected to the turbine low pressure cylinder through the intermediate and low pressure connecting pipe, and the other is connected to the heating exhaust main pipe through the heating pipe; A low-pressure bypass is branched from the reheater outlet pipeline. A suitable position is selected in the low-pressure bypass to drill holes for steam extraction. The extracted steam is passed to the industrial exhaust main pipe to realize external industrial heat and steam supply. The low-pressure bypass terminal is branched into two pipelines, both of which are passed into the condenser. In order to maintain the balance of the unit's steam-water system, it is connected to an external condensate system. The connection of the condensate system can recycle the condensate in the condenser to maintain the water balance and energy balance of the steam-water system. The outlet pipeline of the condensate system branches into two pipelines, which are respectively connected to the two pipelines branched at the low-pressure bypass terminal.

[0007] A steam control valve is installed in the high-pressure bypass and is used to accurately control the steam flow and pressure in the high-pressure bypass to meet the needs of the unit under different operating conditions.

[0008] The high-pressure bypass and the low-pressure bypass are always in a hot standby state when the unit is running. The hot standby state enables the bypass system to be put into operation at any time to cope with various situations that may occur in the unit and improve the reliability and stability of the unit.

[0009] A first switching butterfly valve is arranged on the pipeline connected to the industrial exhaust main pipe, and a second switching butterfly valve is arranged in the pipeline from the low-pressure bypass to the condenser at the same time. Both the first switching butterfly valve and the second switching butterfly valve are electrically driven and have interlocking control. The interlocking control can ensure that the actions of the two switching butterfly valves are coordinated and consistent, ensuring the safe operation of the system. When it is necessary to switch the steam flow direction, the interlocking control can automatically adjust the status of the two butterfly valves to avoid erroneous operation.

[0010] The material of the pipe connecting the industrial exhaust main pipe is the same as that of the low-pressure bypass, which can ensure that the material and performance of the pipes are the same, reduce potential problems caused by material differences, and improve the reliability and stability of the system.

[0011] Electric valves are installed between each pipeline of the system to improve the operating convenience and accuracy of the system.

[0012] The operation method includes an opening operation and an exit operation, and the opening operation comprises the following steps: S1: Before the bypass device is put into operation, the boiler main steam pipeline is drained, and then the steam control valve is gradually opened; the purpose of opening the drain is to remove condensed water in the pipeline to prevent water hammer from damaging the pipeline and equipment. Gradually opening the steam control valve can steadily increase the steam flow in the high-pressure bypass to avoid impact on the system.

[0013] S2: Check the electric valve between the pipes of the water outlet main pipe of the three-stage high-pressure heater, confirm that it is tightly closed, gradually open the flow of the water outlet main pipe of the three-stage high-pressure heater, and start water spraying; S3: Gradually open the low-pressure bypass electric valve to maintain the temperature after the valve at 280 - 320℃; maintaining the temperature after the valve within a certain range can ensure the safe operation of the system and the quality of steam.

[0014] S4: According to the steam flow of the low-pressure bypass, adjust the opening of the steam control valve, gradually increase the steam pressure of the high-pressure bypass, and adjust the opening of the electric valve of the water outlet mother pipe of the third-stage high-pressure heater to maintain the temperature of the residual steam channel before the boiler reheater not exceeding 350°C; S5: Gradually open the high-pressure bypass and low-pressure bypass electric valves, adjust the extraction steam flow rate according to the industrial extraction steam mother pipe pressure, and the maximum control does not exceed 150t / h; gradually open the electric valves to increase the steam flow rate steadily, and adjust the extraction steam flow rate according to the industrial extraction steam mother pipe pressure to ensure the stability and safety of external heat and steam supply. Maximum control of the extraction steam flow rate can avoid excessive impact on the unit operation.

[0015] S6: Closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, low-pressure cylinder exhaust temperature and other parameters to ensure they are within the normal range. Suspend operation if the axial displacement, thrust bearing temperature, or bearing temperature increases by 5°C; suspend operation if the axial displacement increases to 0.1mm. Closely monitoring these parameters can promptly detect abnormal conditions in the unit's operation, and take appropriate measures to adjust and handle them to ensure safe operation of the unit.

[0016] S6: During the bypass operation, on-site inspection of the unit reheater and industrial exhaust main pipeline shows no obvious vibration. If the pipeline vibrates, stop increasing the steam extraction operation and analyze the cause.

[0017] The exit operation is as follows: S1: Exit the bypass heating system according to the instruction of the duty officer; S2: Slowly close the low-pressure bypass electric valve to maintain the temperature behind the valve stable, and other units cooperate to adjust the industrial steam extraction mother pipe pressure; Slowly closing the low-pressure bypass electric valve can steadily reduce the steam flow rate, and maintaining the temperature behind the valve stable can avoid impact on the system. Other units cooperate to adjust the industrial steam extraction mother pipe pressure to ensure the stability of external heat and steam supply.

[0018] S3: Gradually close the high-pressure bypass electric valve and steam control valve, gradually reduce the steam pressure after the high-pressure bypass, and adjust the low-pressure bypass temperature to a stable level; steadily reduce the steam flow and pressure in the high-pressure bypass, and adjust the low-pressure bypass temperature to a stable level to ensure safe exit of the system.

[0019] S4: Operate slowly when closing the high-pressure bypass and low-pressure bypass electric valves, and closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, pressure, low-pressure cylinder exhaust temperature, pressure and other parameters to ensure they are within the normal range; S5: After the bypass heating is shut down, close the outlet pipe of the third-stage high-pressure heater, and close the electric valve and steam control valve of the main steam pipeline of the boiler on site. Closing the outlet pipe and the electric valve of the main steam pipeline can cut off the water and steam sources of the system, allowing the system to exit safely.

[0020] During the bypass operation, check the stability of the steam source of the small unit. If the pressure drops rapidly, increase the extraction steam pressure in time. If necessary, switch the steam source of the auxiliary pump small unit to auxiliary steam. When the unit is adjusted deep and the load is brought to 180MW, switch the steam source of the auxiliary pump small unit back to the fourth extraction in time. Checking the stability of the steam source of the small unit can ensure the normal operation of the small unit. If the pressure drops rapidly, increase the extraction steam pressure in time to ensure the steam supply of the small unit. When necessary, switch the steam source of the auxiliary pump small unit to auxiliary steam to improve the reliability of the system. After the unit is adjusted deep and the load is brought to 180MW, switch the steam source of the auxiliary pump small unit back to the fourth extraction in time to restore the normal operation state.

[0021] The bypass operation process checks the outlet pipe of the three-stage high-pressure heater to ensure that the outlet pipe pressure of the three-stage high-pressure heater is always higher than the steam side pressure and the temperature is normal. Checking the outlet pipe pressure and temperature can ensure the normal operation of the system, avoid the situation of too low pressure or too high temperature, and ensure the safe operation of the three-stage high-pressure heater.

[0022] During the system startup phase, the boiler main steam pipeline is first opened to drain condensate, and the steam control valve is gradually opened to allow part of the steam to enter the high-pressure bypass, thereby driving the high-pressure cylinder of the steam turbine to work, and the steam after work enters the boiler reheater. At the same time, the flow of the three-stage high-pressure heater outlet pipe is opened and water is sprayed, and the low-pressure bypass electric valve is gradually opened. The steam control valve opening and the three-stage high-pressure heater outlet pipe electric valve opening are adjusted according to the low-pressure bypass steam flow, and the temperature is maintained within a suitable range. The bypass valve is gradually opened and the steam extraction flow is adjusted according to the industrial steam extraction pipe pressure to realize external heat and steam supply. During the operation phase, the various parameters of the unit and the vibration of the pipeline are closely monitored to ensure the stability of the steam source of the small machine and check the status of the three-stage high-pressure heater outlet pipe. During the exit phase, the low-pressure bypass electric valve is slowly closed according to the instruction of the duty officer, and the high-pressure bypass electric valve and the steam control valve are gradually closed. The relevant parameters are adjusted to be stable, and finally the three-stage high-pressure heater outlet pipe and the boiler main steam pipeline electric valve are closed to ensure the safe exit of the system.

[0023] Compared with the prior art, the present invention has the following beneficial effects: During the daily start-up and shutdown peak-shaving period of thermal power units, the method of shutting down the unit without stopping the boiler is adopted. By putting high and low bypass belts with industrial steam extraction into operation, the steam generated by the boiler is supplied to the outside for heating, thus achieving full utilization of the steam during the daily start-up and shutdown peak-shaving period.

[0024] It avoids the long waiting time required from boiler ignition to reaching the start-up conditions and the problem of steam being unavailable during the heating and pressure increase period under the traditional shutdown mode, thereby improving energy utilization efficiency.

[0025] The high-pressure bypass and the low-pressure bypass are always in hot standby state when the unit is running, so that the bypass system can be put into operation at any time, can quickly respond to various operating needs of the unit, and improve the flexibility of the unit to adapt to the spot market.

[0026] The start-up and exit steps in the operation method are relatively simple, and the system operating status can be quickly adjusted according to actual conditions, further enhancing the flexibility of the unit.

[0027] Full utilization of steam reduces energy waste and lowers unit operating costs.

[0028] The time from ignition to parallel operation of the unit is shortened, the operating efficiency of the unit is improved, and thus the economy is improved.

[0029] Electric valves are installed between each pipeline of the system, which improves the convenience and accuracy of operation, and also facilitates precise control of the system to ensure safe operation of the system.

[0030] Close monitoring of various parameters during the operation method, such as axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, low-pressure cylinder exhaust temperature, etc., as well as inspection of pipeline vibration, can promptly detect abnormal conditions in system operation and take corresponding measures to deal with them, ensuring safe and stable operation of the system.

[0031] The two switching butterfly valves with interlock control ensure the accuracy and coordination of steam flow direction switching, avoiding safety risks caused by incorrect operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a diagram of a steam extraction and connection system adapted to the daily start and stop period of a power spot mode unit of the present invention; In the figure: 1, steam turbine high-pressure cylinder; 11, steam control valve; 2, steam turbine intermediate-pressure cylinder; 3, steam turbine low-pressure cylinder (3); 4, boiler reheater; 5, condenser; 61, first switching butterfly valve; 62, second switching butterfly valve. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be fully described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0034] like Figure 1 As shown, a steam extraction and connection system adapted to the daily start-up and shutdown of the power spot mode unit includes a boiler main steam pipeline, characterized in that the boiler main steam pipeline is connected to a high-pressure bypass, the high-pressure bypass is branched into two pipelines, and are respectively connected to the air inlet ends on both sides of the steam turbine high-pressure cylinder 1, and the steam turbine high-pressure cylinder 1 is connected to the boiler reheater 4 through the residual steam channel after working; the residual steam channel is also connected to the water outlet mother pipe of the three-stage high-pressure heater; The boiler reheater 4 is connected to the turbine intermediate pressure cylinder 2 through the reheater outlet pipe, and the outlet end of the turbine intermediate pressure cylinder 2 is divided into two paths, one of which is connected to the turbine low pressure cylinder 3 through the intermediate and low pressure connecting pipe, and the other is connected to the heating exhaust main pipe through the heating pipe; A low-pressure bypass is branched out from the reheater outlet pipeline, and a suitable position is selected in the low-pressure bypass to drill holes for steam extraction. The extracted steam is introduced into the industrial exhaust main pipe to realize external industrial heating and steam supply. The low-pressure bypass is branched into two pipelines at the end point, both of which are introduced into the condenser 4. In order to maintain the balance of the unit's steam-water system, an external condensate system is connected. The condensate system outlet pipeline branches into two pipelines, which are respectively connected to the two pipelines branched at the end point of the low-pressure bypass.

[0035] A steam control valve 11 is installed in the high-pressure bypass.

[0036] The high-pressure bypass and the low-pressure bypass are always in a hot standby state when the unit is running.

[0037] A first switching butterfly valve 61 is arranged on the pipeline connected to the industrial exhaust main pipe, and a second switching butterfly valve 62 is arranged in the pipeline from the low-pressure bypass to the condenser 5. Both the first switching butterfly valve 61 and the second switching butterfly valve 62 are electrically driven and have interlocking control.

[0038] The material selection of the pipeline connecting the industrial exhaust main pipe is consistent with that of the low-pressure bypass.

[0039] Electric valves are installed between each pipeline of the system.

[0040] The operation method includes an opening operation and an exit operation, and the opening operation comprises the following steps: S1: Before the bypass device is put into operation, the boiler main steam pipeline is opened to drain water, and then the steam control valve 11 is gradually opened; S2: Check the electric valve between the pipes of the water outlet main pipe of the three-stage high-pressure heater, confirm that it is tightly closed, gradually open the flow of the water outlet main pipe of the three-stage high-pressure heater, and start water spraying; S3: Gradually open the low-pressure bypass electric valve to maintain the temperature after the valve at 280-320℃; S4: According to the steam flow of the low-pressure bypass, adjust the opening of the steam control valve 11, gradually increase the steam pressure of the high-pressure bypass, adjust the opening of the electric valve of the water outlet mother pipe of the third-stage high-pressure heater, and maintain the temperature in the residual steam channel before the boiler reheater 4 not exceeding 350°C; S5: Gradually open the high-pressure bypass and low-pressure bypass electric valves, and adjust the steam extraction flow rate according to the industrial steam extraction mother pipe pressure, with the maximum control not exceeding 150t / h; S6: Closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, low-pressure cylinder exhaust temperature and other parameters to ensure they are within the normal range. If the axial displacement, thrust bearing temperature, or bearing temperature increases by 5°C, suspend operation. If the axial displacement increases to 0.1mm, suspend operation. S6: During the bypass operation, check on-site that there is no obvious vibration of the unit reheater 4 and the industrial exhaust main pipeline. If the pipeline vibrates, stop increasing the steam extraction operation and analyze the cause.

[0041] The exit operation is as follows: S1: Exit the bypass heating system according to the instruction of the duty officer; S2: Slowly close the low-pressure bypass electric valve to maintain the temperature after the valve stable, and other units cooperate to adjust the industrial steam extraction main pipe pressure; S3: gradually close the high-pressure bypass electric valve and steam control valve 11, gradually reduce the steam pressure after the high-pressure bypass, and adjust the low-pressure bypass temperature to a stable state; S4: Operate slowly when closing the high-pressure bypass and low-pressure bypass electric valves, and closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, pressure, low-pressure cylinder exhaust temperature, pressure and other parameters to ensure they are within the normal range; S5: After the bypass heating is exited, close the outlet pipe of the third-stage high-pressure heater, and close the electric valve of the boiler main steam pipeline and the steam control valve 11 on site.

[0042] During the bypass operation, check the stability of the small unit steam source. If the pressure drops rapidly, increase the extraction steam pressure in time. If necessary, switch the auxiliary pump small unit steam source to auxiliary steam. When the unit deep adjustment ends and the load is brought to 180MW, switch the auxiliary pump small unit steam source back to the fourth extraction in time.

[0043] The bypass operation process checks the outlet water main pipe of the third-stage high-pressure heater to ensure that the outlet water main pipe pressure of the third-stage high-pressure heater is always higher than the steam side pressure and the temperature is normal.

[0044] A specific implementation method of a steam extraction connection system adapted to the daily start-up and shutdown of a power spot mode unit is as follows: the system includes a boiler main steam pipeline, a high-pressure bypass is connected from the boiler main steam pipeline, and the high-pressure bypass is branched into two pipelines, which are respectively connected to the air inlet ends on both sides of the high-pressure cylinder 1 of the steam turbine. After the high-pressure cylinder 1 of the steam turbine works, it is passed to the boiler reheater 4 through the residual steam channel, and the residual steam channel is also connected to the water outlet mother pipe of the three-stage high-pressure heater. The boiler reheater 4 is connected to the steam turbine intermediate pressure cylinder 2 through the reheater outlet pipe, and the outlet end of the steam turbine intermediate pressure cylinder 2 is divided into two paths, one of which is connected to the steam turbine low pressure cylinder 3 through the medium and low pressure connecting pipeline, and the other is connected to the heating extraction mother pipe through the heating pipeline. A low-pressure bypass is branched from the reheater outlet pipeline. A suitable position is selected in the low-pressure bypass to drill holes for steam extraction. The extracted steam is passed to the industrial exhaust main pipe to realize external industrial heat and steam supply. The low-pressure bypass terminal is branched into two pipelines, both of which are passed into the condenser 5 and connected to the external condensate system to maintain the balance of the unit's steam-water system. A steam control valve 11 is installed in the high-pressure bypass, and the high-pressure bypass and the low-pressure bypass are always in hot standby state when the unit is running. A first switching butterfly valve 61 is set on the pipeline connecting the industrial exhaust main pipe, and a second switching butterfly valve 62 is set in the pipeline from the low-pressure bypass to the condenser 5. Both switching butterfly valves are electrically driven and have interlocking control. The pipeline material connecting the industrial exhaust main pipe is consistent with the low-pressure bypass, and electric valves are installed between each pipeline in the system.

[0045] During the opening operation, before the bypass device is put into operation, open the boiler main steam pipeline to drain water, and then gradually open the steam control valve 11; check the pipeline electric valve of the three-stage high-pressure heater outlet main pipe, confirm that it is tightly closed, gradually open the flow of the three-stage high-pressure heater outlet main pipe and start water spraying; gradually open the low-pressure bypass electric valve to maintain the temperature after the valve at 280-320℃; adjust the opening of the steam control valve 11 according to the low-pressure bypass steam flow, gradually increase the steam pressure of the high-pressure bypass, adjust the opening of the electric valve of the three-stage high-pressure heater outlet main pipe, and maintain the temperature in the residual steam channel before the boiler reheater 4 not exceeding 350℃; gradually open the high-pressure bypass and low-pressure bypass electric valves, adjust the extraction flow according to the industrial extraction main pipe pressure, and the maximum control does not exceed 150t / h; closely monitor the unit axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, low-pressure cylinder exhaust temperature and other parameters within the normal range, and the axial displacement, thrust bearing temperature, bearing temperature increase by 5℃ or the axial displacement increases to 0.1mm The operation will be suspended. During the bypass operation, the unit reheater will be checked on site. There will be no obvious vibration of the industrial exhaust main pipeline. If the pipeline vibrates, stop increasing the steam extraction operation and analyze the cause.

[0046] When exiting the operation, exit the bypass heating system according to the instruction of the duty officer; slowly close the low-pressure bypass electric valve to maintain the temperature after the valve stable, and other units cooperate to adjust the industrial steam extraction mother pipe pressure; gradually close the high-pressure bypass electric valve and steam control valve 11, gradually reduce the steam pressure after the high-pressure bypass, and adjust the low-pressure bypass temperature to stability; operate slowly during the process of closing the high-pressure bypass and low-pressure bypass electric valves, and closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, pressure, low-pressure cylinder exhaust temperature, pressure and other parameters within the normal range; after the bypass heating is exited, close the three-stage high-pressure heater outlet mother pipe, and close the boiler main steam pipeline electric valve and steam control valve 11 on site. During the bypass operation, check the stability of the small unit steam source. If the pressure drops rapidly, increase the extraction steam pressure in time, and switch the auxiliary pump small unit steam source to auxiliary steam when necessary. After the unit deep adjustment is completed and the load is brought to 180MW, switch the auxiliary pump small unit steam source back to the four extractions in time; during the bypass operation process, check the water outlet main pipe of the three-stage high-pressure heater to ensure that the pressure of the water outlet main pipe of the three-stage high-pressure heater is always higher than the steam side pressure and the temperature is normal.

Claims

1. A steam extraction and connection system adapted to the daily start-up and shutdown of a power spot mode unit, comprising a boiler main steam pipeline, characterized in that: The main steam pipe of the boiler is connected to a high-pressure bypass, and the high-pressure bypass is branched into two pipes, which are respectively connected to the air inlet ends on both sides of the high-pressure cylinder (1) of the steam turbine. After the high-pressure cylinder (1) of the steam turbine is operated, it is passed to the boiler reheater (4) through the residual steam channel; the residual steam channel is also connected to the water outlet mother pipe of the three-stage high-pressure heater; The boiler reheater (4) is connected to the turbine intermediate pressure cylinder (2) through the reheater outlet pipe, and the outlet end of the turbine intermediate pressure cylinder (2) is divided into two paths, one of which is connected to the turbine low pressure cylinder (3) through the intermediate and low pressure connecting pipe, and the other is connected to the heating exhaust main pipe through the heating pipe; A low-pressure bypass is branched from the reheater outlet pipeline. A suitable position is selected in the low-pressure bypass to drill holes for steam extraction. The extracted steam is introduced into the industrial exhaust main pipe to realize external industrial heat and steam supply. The low-pressure bypass terminal is branched into two pipelines, both of which are introduced into the condenser (4). In order to maintain the balance of the unit's steam-water system, an external condensate system is connected. The condensate system outlet pipeline is branched into two pipelines, which are respectively connected to the two pipelines branched at the low-pressure bypass terminal.

2. According to the steam extraction system adapted to the daily start-up and shutdown of a power spot mode unit according to claim 1, a steam control valve (11) is installed in the high-pressure bypass.

3. According to the steam extraction connection system adapted to the daily start-up and shutdown of the power spot mode unit in claim 1, the high-pressure bypass and the low-pressure bypass are always in hot standby state when the unit is running.

4. According to the steam extraction connection system adapted to the daily start-up and shutdown of the power spot mode unit as described in claim 1, a first switching butterfly valve (61) is arranged on the pipeline connected to the industrial exhaust main pipe, and a second switching butterfly valve (62) is simultaneously arranged in the pipeline from the low-pressure bypass to the condenser (5), and the first switching butterfly valve (61) and the second switching butterfly valve (62) are both electrically driven and have interlocking control.

5. According to the steam extraction connection system adapted to the daily start-up and shutdown of the power spot mode unit in claim 1, the material of the pipeline connecting the industrial exhaust main pipe is consistent with that of the low-pressure bypass.

6. According to the steam extraction connection system adapted to the daily start-up and shutdown of the power spot mode unit as described in claim 1, electric valves are installed between each pipeline of the system.

7. An operation method of a steam extraction system adapted to the daily start-up and shutdown of a power spot mode unit, characterized in that: The operation method includes an opening operation and an exit operation, and the opening operation comprises the following steps: S1: Before the bypass device is put into operation, the boiler main steam pipe is opened to drain water, and then the steam control valve (11) is gradually opened; S2: Check the electric valve between the pipes of the water outlet main pipe of the three-stage high-pressure heater, confirm that it is tightly closed, gradually open the flow of the water outlet main pipe of the three-stage high-pressure heater, and start water spraying; S3: Gradually open the low-pressure bypass electric valve to maintain the temperature after the valve at 280-320℃; S4: adjusting the opening of the steam control valve (11) according to the steam flow of the low-pressure bypass, gradually increasing the steam pressure of the high-pressure bypass, and adjusting the opening of the electric valve of the water outlet main pipe of the third-stage high-pressure heater to maintain the temperature of the residual steam channel before the boiler reheater (4) not exceeding 350°C; S5: Gradually open the high-pressure bypass and low-pressure bypass electric valves, and adjust the steam extraction flow rate according to the industrial steam extraction mother pipe pressure, with the maximum control not exceeding 150t / h; S6: Closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, low-pressure cylinder exhaust temperature and other parameters to ensure they are within the normal range. If the axial displacement, thrust bearing temperature, or bearing temperature increases by 5°C, suspend operation. If the axial displacement increases to 0.1mm, suspend operation. S6: During the bypass operation, check on-site that there is no obvious vibration of the unit reheater (4) and industrial exhaust main pipeline. If the pipeline vibrates, stop increasing the steam extraction operation and analyze the cause.

8. According to the method for operating the extraction steam connection system during the start-up and shutdown period of the power spot mode unit in claim 7, the exit operation comprises the following steps: S1: Exit the bypass heating system according to the instruction of the duty officer; S2: Slowly close the low-pressure bypass electric valve to maintain the temperature after the valve stable, and other units cooperate to adjust the industrial steam extraction main pipe pressure; S3: gradually close the high-pressure bypass electric valve and the steam control valve (11), gradually reduce the steam pressure after the high-pressure bypass, and adjust the low-pressure bypass temperature to a stable state; S4: Operate slowly when closing the high-pressure bypass and low-pressure bypass electric valves, and closely monitor the unit's axial displacement, thrust bearing temperature, vibration, bearing temperature, high-pressure cylinder exhaust temperature, pressure, low-pressure cylinder exhaust temperature, pressure and other parameters to ensure they are within the normal range; S5: After the bypass heating is terminated, the outlet pipe of the third-stage high-pressure heater is closed, and the electric valve and steam control valve (11) of the boiler main steam pipeline are closed locally.

9. According to the method for operating the steam extraction connection system adapted to the daily start-up and shutdown of the power spot mode unit in claim 7, during the bypass operation, the small machine steam source is checked for stability. If the pressure drops rapidly, the steam extraction pressure is increased in time, and if necessary, the auxiliary pump small machine steam source is switched to auxiliary steam. When the unit is adjusted deeply and the load is brought to 180MW, the auxiliary pump small machine steam source is switched back to the fourth extraction in time.

10. According to the method for operating a steam extraction connection system adapted to the daily start-up and shutdown of a power spot mode unit in claim 7, the bypass operation process checks the water outlet mother pipe of the third-stage high-pressure heater to ensure that the pressure of the water outlet mother pipe of the third-stage high-pressure heater is always higher than the steam side pressure and the temperature is normal.

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