Fault protection control method for check valve of four-suction deaerator

Abstract

The invention belongs to the technical field of steam turbines, and discloses a four-extraction to deaerator check valve fault protection control method, which comprises the following steps: S1, monitoring the change trend of temperature and pressure in real time, S2, triggering sound-light alarm by judging the temperature condition, S3, triggering sound-light alarm by judging the pressure condition, and S4, carrying out fault protection control on a check valve of a four-extraction to deaerator. S5, setting logic protection; S6, accessing a standby gas source; and S7, overhauling the overhauling equipment. The balance pipe and the four-suction-to-deaerator steam inlet check valve are arranged at the top of the deaerator, the check valve plays a role in preventing steam backflow and serves as first protection of the steam turbine, the balance pipe plays a role in balancing the pressure of the steam inlet pipe and the deaerator, the steam balance pipe does not play a role in normal operation, and therefore the steam inlet pipe is protected. And when the steam inlet pressure from the fourth extraction to the deaerator is lower than the pressure of the deaerator, the balance pipe check valve is opened, so that the pressure difference between the deaerator and the fourth extraction steam inlet is reduced, and water in the deaerator is prevented from flowing back.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbines, and in particular relates to a fault protection control method for a check valve of a four-extraction deaerator. Background Art

[0002] The deaerator in the steam turbine is a device used to remove dissolved oxygen from water. In the deaerator, water is heated to a certain temperature to separate the dissolved oxygen in the water and form a large amount of superheated steam, thereby achieving the purpose of removing dissolved oxygen.

[0003] The main structure of the deaerator includes the shell, baffle, nozzle, etc. When the boiler feed water is heated to a certain value by the heating device, it enters the high-pressure deaerator for heat exchange reaction. First, the water droplets precipitated on the tube wall flow back to the water tank due to gravity and re-participate in the circulation flow; secondly, the superheated steam formed in the water tank becomes low-temperature and low-pressure water vapor after throttling by the throttle valve, and enters the main steam drum from the water inlet main pipe to continue to participate in the circulation flow; then the cold water is sent to the evaporation section for evaporation treatment.

[0004] When a general steam turbine is in operation, a common fault of the deaerator inside it is water backflow. When the inlet water temperature is too high and cannot be detected and changed in time, the amount of oxygen dissolved in the water will decrease, thus affecting the deaerator's deoxygenation effect. When the water temperature is too high, the remaining oxygen will continue to reach the deaerator, increasing the oxygen concentration and causing the deaerator to backflow. Therefore, a protection method that can balance the internal pressure and temperature needs to be designed. Summary of the invention

[0005] The object of the present invention is to provide a four-pump deaerator check valve fault protection control method to solve the problems raised in the above background technology.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a fault protection control method for a check valve of a four-pump deaerator, the fault protection control method is:

[0007] S1, real-time monitoring of temperature and pressure trends, through various sensors inside the steam turbine, closely monitor the metal wall temperature of the fourth extraction steam, the steam inlet temperature from the fourth extraction steam to the deaerator, the steam inlet pressure from the fourth extraction steam to the deaerator, the steam inlet temperature from the fourth extraction steam to the small unit, and the steam inlet pressure from the fourth extraction steam to the small unit;

[0008] S2, triggering the sound and light alarm by judging the temperature condition, adding a sound and light alarm device, judging the triggering condition by judging the decrease of the steam temperature at the deaerator inlet: the steam inlet temperature from the four-stage extraction to the deaerator is 10℃ lower than the metal wall temperature of the four-stage extraction steam or the steam inlet temperature from the four-stage extraction to the deaerator is 10℃ lower than the metal wall temperature of the small unit steam inlet pipe, then the alarm can be triggered;

[0009] S3, triggering the sound and light alarm by judging the pressure condition, judging the triggering condition by judging the rising change of the deaerator pressure: when the deaerator pressure is higher than the four-stage steam extraction pressure or the deaerator pressure is higher than the small unit steam inlet pressure by 0.02MPa, the alarm can be triggered;

[0010] S4: After the alarm, the temperature and pressure are stabilized by increasing the load. After the unit triggers the alarm, preliminary load stabilization measures are immediately taken. If the temperature and pressure difference is still increasing, further stabilization measures are taken;

[0011] S5, set logic protection, by setting trigger conditions for the deaerator exhaust electric door and the four-stage steam extraction to deaerator steam inlet electric door, to achieve opening or closing, and adjust the temperature and pressure values;

[0012] S6, standby gas source access, when the unit load is below 40% of the rated load, manually open the auxiliary steam system warm-up pipe drain, and make preparations for standby steam source access to the small unit;

[0013] S7, perform maintenance on the maintenance equipment, and use the shutdown period to dismantle and inspect the four-pump main pipe check valve and the four-pump to deaerator steam inlet check valve.

[0014] Preferably, the fault protection control method is applied to a steam turbine, which includes four sections of steam extraction metal walls, four extraction deaerators and four extraction small machines, and sensors arranged therein.

[0015] Preferably, the preliminary load stabilization measures are:

[0016] Step 1: load adjustment: by adjusting the load in the power system to control the output power of the steam turbine and reduce load fluctuations;

[0017] Step 2: Adjusting the operating parameters; controlling the load fluctuation of the steam turbine by adjusting the operating parameters of the steam turbine.

[0018] Preferably, the triggering condition for the deaerator exhaust electric door protection in S5 is:

[0019] 1. The steam inlet temperature from the fourth extraction to the deaerator is 25℃ lower than the metal wall temperature of the fourth extraction;

[0020] 2. The steam inlet temperature from the fourth extraction to the deaerator is 25℃ lower than the metal wall temperature of the steam inlet pipe of the small unit;

[0021] 3. The deaerator pressure is 0.015MPa higher than the fourth stage steam extraction pressure;

[0022] 4. The deaerator pressure is 0.015MPa higher than the small unit steam inlet pressure;

[0023] If any two of the conditions are met, it will be triggered, and the deaerator will be automatically opened to start the exhaust steam electric door to reduce the deaerator pressure;

[0024] At the same time, when the deaerator pressure is lower than the four-stage extraction steam pressure by 0.025MPa or the deaerator pressure is lower than the small unit inlet steam pressure by 0.025MPa, the deaerator will be automatically closed and the exhaust steam electric door will be started.

[0025] Preferably, the triggering condition for the protection of the electric steam inlet door from the four-stage steam extraction to the deaerator in S5 is:

[0026] A. The steam inlet temperature from the fourth extraction to the deaerator is 30℃ lower than the metal wall temperature of the fourth extraction;

[0027] B. The steam inlet temperature from the fourth extraction to the deaerator is 30℃ lower than the metal wall temperature of the steam inlet pipe of the small unit;

[0028] C, the deaerator pressure is 0.035MPa higher than the fourth stage extraction steam pressure;

[0029] D. The deaerator pressure is 0.035MPa higher than the small unit steam inlet pressure;

[0030] If any two of the conditions are met, it will be triggered, and the electric steam inlet gate of the four-stage steam extraction to the deaerator will be automatically closed to reduce the pressure of the deaerator;

[0031] At the same time, the deaerator pressure is lower than the four-stage steam extraction pressure by 0.035MPa; the deaerator pressure is lower than the small unit steam inlet pressure by 0.035MPa, and the electric door from the four-stage steam extraction to the deaerator steam inlet is automatically opened.

[0032] Preferably, the further stabilization measure in S4 is to increase the load value, and the increasing method is: increasing the load by 10MW from the initial state in sequence until the pressure and temperature gradually tend to be stable.

[0033] Preferably, the preparation steps for connecting the standby steam source to the small machine are as follows:

[0034] 1. Confirm the availability of the backup steam source: First, confirm whether the backup steam source is available, including whether its pressure, temperature, and steam quality parameters meet the requirements;

[0035] 2. Prepare tools and materials: Before connecting to the backup steam source, prepare the necessary tools and materials;

[0036] 3. Confirm the status of the small steam turbine: Before connecting to the backup steam source, confirm the status of the small steam turbine;

[0037] Fourth, confirm the access plan: a plan for connecting the backup steam source to the small steam turbine needs to be formulated;

[0038] 5. Safety measures: Before connecting to the backup steam source, it is necessary to set up safety warning signs and prepare fire-fighting equipment and props;

[0039] 6. Personnel training: Relevant personnel need to be trained to ensure that they understand the scheme and steps for connecting the backup steam source to the small steam turbine and can operate it correctly;

[0040] 7. Confirm the safety of the backup steam source access system: its impact on the entire system and possible risk factors need to be confirmed;

[0041] 8. Records and reports: After connecting to the backup steam source, the entire process needs to be recorded and reported.

[0042] The beneficial effects of the present invention are as follows:

[0043] There are eight stages of steam extraction, of which four stages of steam extraction pass through four-stage non-return valve and four-stage electric valve to provide working steam source for small steam turbine and deaerator respectively. Figure 2 As shown, the deaerator adopts a built-in horizontal deaerator, which normally operates with the sliding pressure of the unit; the other four sections of extracted steam are sent to the steam exhaust pipe below the water surface of the deaerator for mixed heating to achieve the secondary deoxygenation effect. A balance pipe and a four-extraction to deaerator steam inlet check valve are arranged on the top of the deaerator. The check valve prevents steam backflow. As the first line of protection for the steam turbine, the balance pipe balances the pressure of the steam inlet pipe and the deaerator. The steam balance pipe does not work during normal operation. When the four-extraction to deaerator steam inlet pressure is lower than the deaerator pressure, the balance pipe check valve opens, thereby reducing the pressure difference between the deaerator and the four-extraction steam inlet, preventing water backflow in the deaerator. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A simplified diagram of the steps of the fault protection control method of the present invention;

[0045] Figure 2 It is a brief schematic diagram of the four-stage steam extraction of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 to Figure 2 As shown, the embodiment of the present invention provides a four-pump to deaerator check valve fault protection control method, and the fault protection control method is:

[0048] S1, real-time monitoring of temperature and pressure trends, through various sensors inside the steam turbine, closely monitor the metal wall temperature of the fourth extraction steam, the steam inlet temperature from the fourth extraction steam to the deaerator, the steam inlet pressure from the fourth extraction steam to the deaerator, the steam inlet temperature from the fourth extraction steam to the small unit, and the steam inlet pressure from the fourth extraction steam to the small unit;

[0049] S2, triggering the sound and light alarm by judging the temperature condition, adding a sound and light alarm device, judging the triggering condition by judging the decrease of the steam temperature at the deaerator inlet: the steam inlet temperature from the four-stage extraction to the deaerator is 10℃ lower than the metal wall temperature of the four-stage extraction steam or the steam inlet temperature from the four-stage extraction to the deaerator is 10℃ lower than the metal wall temperature of the small unit steam inlet pipe, then the alarm can be triggered;

[0050] S3, triggering the sound and light alarm by judging the pressure condition, judging the triggering condition by judging the rising change of the deaerator pressure: when the deaerator pressure is higher than the four-stage steam extraction pressure or the deaerator pressure is higher than the small unit steam inlet pressure by 0.02MPa, the alarm can be triggered;

[0051] S4: After the alarm, the temperature and pressure are stabilized by increasing the load. After the unit triggers the alarm, preliminary load stabilization measures are immediately taken. If the temperature and pressure difference is still increasing, further stabilization measures are taken;

[0052] S5, set logic protection, by setting trigger conditions for the deaerator exhaust electric door and the four-stage steam extraction to deaerator steam inlet electric door, to achieve opening or closing, and adjust the temperature and pressure values;

[0053] S6, standby gas source access, when the unit load is below 40% of the rated load, manually open the auxiliary steam system warm-up pipe drain, and make preparations for standby steam source access to the small unit;

[0054] S7, perform maintenance on the maintenance equipment, and use the shutdown period to dismantle and inspect the four-pump main pipe check valve and the four-pump to deaerator steam inlet check valve.

[0055] The fault protection control method is applied to a steam turbine, which includes four sections of steam extraction metal walls, four extractions to deaerators and four extractions to small machines, as well as sensors arranged inside the steam turbine.

[0056] Among them, the initial load stabilization measures are:

[0057] Step 1: load adjustment: by adjusting the load in the power system to control the output power of the steam turbine and reduce load fluctuations;

[0058] Step 2: Adjusting the operating parameters; controlling the load fluctuation of the steam turbine by adjusting the operating parameters of the steam turbine.

[0059] Among them, the triggering conditions for the deaerator exhaust electric door protection in S5 are:

[0060] 1. The steam inlet temperature from the fourth extraction to the deaerator is 25℃ lower than the metal wall temperature of the fourth extraction;

[0061] 2. The steam inlet temperature from the fourth extraction to the deaerator is 25℃ lower than the metal wall temperature of the steam inlet pipe of the small unit;

[0062] 3. The deaerator pressure is 0.015MPa higher than the fourth stage steam extraction pressure;

[0063] 4. The deaerator pressure is 0.015MPa higher than the small unit steam inlet pressure;

[0064] If any two of the conditions are met, it will be triggered, and the deaerator will be automatically opened to start the exhaust steam electric door to reduce the deaerator pressure.

[0065] At the same time, when the deaerator pressure is lower than the four-stage extraction steam pressure by 0.025MPa or the deaerator pressure is lower than the small unit inlet steam pressure by 0.025MPa, the deaerator will be automatically closed and the exhaust steam electric door will be started.

[0066] Among them, the triggering conditions for the electric steam door protection from the four-stage steam extraction to the deaerator inlet in S5 are:

[0067] A. The steam inlet temperature from the fourth extraction to the deaerator is 30℃ lower than the metal wall temperature of the fourth extraction;

[0068] B. The steam inlet temperature from the fourth extraction to the deaerator is 30℃ lower than the metal wall temperature of the steam inlet pipe of the small unit;

[0069] C, the deaerator pressure is 0.035MPa higher than the fourth stage extraction steam pressure;

[0070] D. The deaerator pressure is 0.035MPa higher than the small unit steam inlet pressure;

[0071] If any two of the conditions are met, it will be triggered, and the electric steam inlet gate of the four-stage steam extraction to the deaerator will be automatically closed to reduce the pressure of the deaerator;

[0072] At the same time, the deaerator pressure is lower than the four-stage steam extraction pressure by 0.035MPa; the deaerator pressure is lower than the small unit steam inlet pressure by 0.035MPa, and the electric door from the four-stage steam extraction to the deaerator steam inlet is automatically opened.

[0073] Among them, the further stabilization measure in S4 is to increase the load value, and the increase method is: increase the load by 10MW from the initial state until the pressure and temperature gradually tend to be stable.

[0074] The preparation steps for connecting the standby steam source to the small machine are as follows:

[0075] 1. Confirm the availability of the backup steam source: First, you need to confirm whether the backup steam source is available, including whether its pressure, temperature, and steam quality parameters meet the requirements.

[0076] 2. Prepare tools and materials: Before connecting to the backup steam source, prepare the necessary tools and materials.

[0077] 3. Confirm the status of the small steam turbine: Before connecting to the backup steam source, confirm the status of the small steam turbine, including its speed, load, operating mode, etc.

[0078] 4. Confirm the access plan: A plan for connecting the backup steam source to the small steam turbine needs to be developed, including the location, method, and steps of connection.

[0079] 5. Safety measures: Before connecting to the backup steam source, it is necessary to set up safety warning signs and prepare fire-fighting equipment and props.

[0080] 6. Personnel training: Relevant personnel need to be trained to ensure that they understand the plan and steps for connecting the backup steam source to the small steam turbine and can operate it correctly.

[0081] 7. Confirm the safety of the backup steam source access system: It is necessary to confirm its impact on the entire system and possible risk factors.

[0082] 8. Records and reports: After connecting to the backup steam source, the entire process needs to be recorded and reported.

[0083] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0084] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Fault protection control method for check valve of four-stage extraction to deaerator, It is characterized in that The fault protection control method is: S1, real-time monitoring of temperature and pressure trends, through various sensors inside the steam turbine, closely monitor the metal wall temperature of the fourth extraction steam, the steam inlet temperature from the fourth extraction steam to the deaerator, the steam inlet pressure from the fourth extraction steam to the deaerator, the steam inlet temperature from the fourth extraction steam to the small unit, and the steam inlet pressure from the fourth extraction steam to the small unit; S2, triggering the sound and light alarm by judging the temperature condition, adding a sound and light alarm device, judging the triggering condition by judging the decrease of the steam temperature at the deaerator inlet: the steam inlet temperature from the four-stage extraction to the deaerator is 10℃ lower than the metal wall temperature of the four-stage extraction steam or the steam inlet temperature from the four-stage extraction to the deaerator is 10℃ lower than the metal wall temperature of the small unit steam inlet pipe, then the alarm can be triggered; S3, triggering the sound and light alarm by judging the pressure condition, judging the triggering condition by judging the rising change of the deaerator pressure: when the deaerator pressure is higher than the four-stage steam extraction pressure or the deaerator pressure is higher than the small unit steam inlet pressure by 0.02MPa, the alarm can be triggered; S4: After the alarm, the temperature and pressure are stabilized by increasing the load. After the unit triggers the alarm, preliminary load stabilization measures are immediately taken. If the temperature and pressure difference is still increasing, further stabilization measures are taken; S5, set logic protection, by setting trigger conditions for the deaerator exhaust electric door and the four-stage steam extraction to deaerator steam inlet electric door, to achieve opening or closing, and adjust the temperature and pressure values; S6, standby gas source access, when the unit load is below 40% of the rated load, manually open the auxiliary steam system warm-up pipe drain, and make preparations for standby steam source access to the small unit; S7, perform maintenance on the maintenance equipment, and use the shutdown period to dismantle and inspect the four-pump main pipe check valve and the four-pump to deaerator steam inlet check valve.

2. The method for controlling the fault protection of the check valve of the four-pump deaerator according to claim 1, Features: The fault protection control method is applied to a steam turbine, which includes four sections of steam extraction metal walls, four extraction deaerators and four extraction small machines, as well as sensors arranged inside the steam turbine.

3. The four-pump to deaerator check valve fault protection control method according to claim 1, Features: The preliminary load stabilization measures are: Step 1: load adjustment: by adjusting the load in the power system to control the output power of the steam turbine and reduce load fluctuations; Step 2: Adjusting the operating parameters; controlling the load fluctuation of the steam turbine by adjusting the operating parameters of the steam turbine.

4. The four-pump to deaerator check valve fault protection control method according to claim 1, Features: The triggering condition of the deaerator exhaust electric door protection in S5 is:

1. The steam inlet temperature from the fourth extraction to the deaerator is 25℃ lower than the metal wall temperature of the fourth extraction; 2. The steam inlet temperature from the fourth extraction to the deaerator is 25℃ lower than the metal wall temperature of the steam inlet pipe of the small unit; 3. The deaerator pressure is 0.015MPa higher than the fourth stage steam extraction pressure; 4. The deaerator pressure is 0.015MPa higher than the small unit steam inlet pressure; If any two of the conditions are met, it will be triggered, and the deaerator will be automatically opened to start the exhaust steam electric door to reduce the deaerator pressure; At the same time, when the deaerator pressure is lower than the four-stage extraction steam pressure by 0.025MPa or the deaerator pressure is lower than the small unit inlet steam pressure by 0.025MPa, the deaerator will be automatically closed and the exhaust steam electric door will be started.

5. The four-pump to deaerator check valve fault protection control method according to claim 1, Features: The triggering conditions for the protection of the electric steam inlet door from the four-stage steam extraction to the deaerator in S5 are: A. The steam inlet temperature from the fourth extraction to the deaerator is 30℃ lower than the metal wall temperature of the fourth extraction; B. The steam inlet temperature from the fourth extraction to the deaerator is 30℃ lower than the metal wall temperature of the steam inlet pipe of the small unit; C, the deaerator pressure is 0.035MPa higher than the fourth stage extraction steam pressure; D. The deaerator pressure is 0.035MPa higher than the small unit steam inlet pressure; If any two of the conditions are met, it will be triggered, and the electric steam inlet gate of the four-stage steam extraction to the deaerator will be automatically closed to reduce the pressure of the deaerator; At the same time, the deaerator pressure is lower than the four-stage steam extraction pressure by 0.035MPa; the deaerator pressure is lower than the small unit steam inlet pressure by 0.035MPa, and the electric door from the four-stage steam extraction to the deaerator steam inlet is automatically opened.

6. The method for controlling the fault protection of the check valve of the four-pump deaerator according to claim 1, Features: The further stabilization measure in S4 is to increase the load value, and the increasing method is: increasing the load by 10MW from the initial state until the pressure and temperature gradually tend to be stable.

7. The method for controlling the fault protection of the check valve of the four-pump deaerator according to claim 1, Features: The preparation steps for connecting the standby steam source to the small machine are as follows:

1. Confirm the availability of the backup steam source: First, confirm whether the backup steam source is available, including whether its pressure, temperature, and steam quality parameters meet the requirements; 2. Prepare tools and materials: Before connecting to the backup steam source, prepare the necessary tools and materials; 3. Confirm the status of the small steam turbine: Before connecting to the backup steam source, confirm the status of the small steam turbine; Fourth, confirm the access plan: a plan for connecting the backup steam source to the small steam turbine needs to be formulated; 5. Safety measures: Before connecting to the backup steam source, it is necessary to set up safety warning signs and prepare fire-fighting equipment and props; 6. Personnel training: Relevant personnel need to be trained to ensure that they understand the scheme and steps for connecting the backup steam source to the small steam turbine and can operate it correctly; 7. Confirm the safety of the backup steam source access system: its impact on the entire system and possible risk factors need to be confirmed; 8. Records and reports: After connecting to the backup steam source, the entire process needs to be recorded and reported.

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