CN113606959B - Condenser cooling system and power generation system - Google Patents
Condenser cooling system and power generation system Download PDFInfo
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- CN113606959B CN113606959B CN202110505857.9A CN202110505857A CN113606959B CN 113606959 B CN113606959 B CN 113606959B CN 202110505857 A CN202110505857 A CN 202110505857A CN 113606959 B CN113606959 B CN 113606959B
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- condenser
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- 238000001816 cooling Methods 0.000 title claims abstract description 70
- 238000010248 power generation Methods 0.000 title claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 198
- 239000000498 cooling water Substances 0.000 claims abstract description 37
- 238000013507 mapping Methods 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims description 46
- 230000008859 change Effects 0.000 claims description 10
- 239000013535 sea water Substances 0.000 abstract description 9
- 238000004781 supercooling Methods 0.000 abstract description 5
- 239000003921 oil Substances 0.000 description 26
- 230000001276 controlling effect Effects 0.000 description 12
- 239000010687 lubricating oil Substances 0.000 description 12
- 230000000712 assembly Effects 0.000 description 7
- 238000000429 assembly Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000005461 lubrication Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 239000011150 reinforced concrete Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 230000009545 invasion Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B1/00—Condensers in which the steam or vapour is separate from the cooling medium by walls, e.g. surface condenser
- F28B1/02—Condensers in which the steam or vapour is separate from the cooling medium by walls, e.g. surface condenser using water or other liquid as the cooling medium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K9/00—Plants characterised by condensers arranged or modified to co-operate with the engines
- F01K9/003—Plants characterised by condensers arranged or modified to co-operate with the engines condenser cooling circuits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K9/00—Plants characterised by condensers arranged or modified to co-operate with the engines
- F01K9/006—Vacuum-breakers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B11/00—Controlling arrangements with features specially adapted for condensers
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Structure Of Emergency Protection For Nuclear Reactors (AREA)
Abstract
The invention provides a condenser cooling system and a power generation system, wherein the cooling system comprises: a cooling water source, a drainage structure and a DCS control system; the cooling water source is communicated with the condenser through a water inlet pipe, the water draining structure is communicated with the condenser through a water draining pipe, a water pump is arranged on the water inlet pipe, and a motor is connected on the water pump; the cooling water source is internally provided with a thermometer and is electrically connected with the DCS, and the thermometer is used for detecting the temperature of the cooling water source and transmitting the detected real-time temperature value signal to the DCS; the DCS is electrically connected with the frequency converter and is used for feeding back a frequency signal corresponding to the temperature value signal to the frequency converter according to a mapping table of the temperature and the frequency stored in the DCS; the frequency converter is electrically connected with the motor and is used for adjusting the frequency of the motor according to the frequency signal and adjusting the water outlet flow of the water pump. The invention can automatically regulate and control the circulating water quantity according to different seawater temperatures, solves the problem of supercooling of the condenser caused by excessively low water temperature in winter at the north nuclear power plant site, and reduces the shutdown and shutdown probability caused by cold source blockage.
Description
Technical Field
The invention relates to the technical field of nuclear power equipment, in particular to a condenser cooling system and a power generation system.
Background
With the continuous development of nuclear power in China, nuclear power plant sites are not limited to the coasts in the south and the coasts in the north, and nuclear power plants are built successively, and currently, plant sites such as Liaoning Honghe river, jiangsu field bay and the like exist. The temperature of the northern seawater in winter is low, and the circulating water quantity required by a circulating water system of the nuclear power station is greatly reduced. The circulating water quantity is determined according to parameters such as the annual average seawater temperature, and the circulating water quantity can not be regulated according to the monthly average temperature, even the time-by-time temperature. If the rated flow water supply is continuously adopted, too much circulating water in winter can cause too low steam back pressure of the condenser and even cause the supercooling degree of the condensed water to be increased.
When the back pressure of the turbine unit is lower than a certain back pressure caused by low-temperature seawater in winter, the output of the turbine unit is not increased, but the stress borne by the final-stage blades of the turbine is continuously increased, and shock waves are easily generated due to the increase of the stress of the final-stage blades, so that the vibration of the turbine unit is aggravated, and the turbine unit runs under the condition for a long time, so that the safety of the final-stage blades is greatly influenced. The increase of the supercooling degree of the condensed water accelerates the corrosion of a condenser and a pipeline, and reduces the use safety and reliability of equipment; too low a condensation water temperature affects the economy of the power plant, which is equivalent to a 1% reduction in the thermal economy of the power plant for every 7 ℃ reduction. The circulating water pump in winter provides excessive circulating water, so that unnecessary power consumption is increased, the economy of the nuclear power station is affected, and the national policy of energy conservation and emission reduction is also overcome.
In addition, in recent years, a plurality of nuclear power plants at home and abroad generate a plurality of plug invasion events, so that a cold source system of the nuclear power plant is blocked, and a nuclear power unit shutdown event is caused.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art, and provides a condenser cooling system which adopts temperature control variable-frequency speed regulation operation or manual input frequency value to regulate cooling water quantity, thereby not only effectively solving the problem of condenser supercooling caused by too low water temperature in winter at the northern nuclear power plant site, improving the plant site adaptability of the nuclear power plant and remarkably saving the operation cost; on the other hand, through means of variable flow operation, the shutdown and shutdown probability caused by cold source blockage can be reduced, and the operation safety and stability of the nuclear power unit are improved. A generator with the condenser cooling system is correspondingly provided.
The technical scheme adopted for solving the technical problems of the invention is as follows:
a condenser cooling system comprising: a cooling water source, a cooling unit, a drainage structure and a DCS control system;
the cooling unit comprises a water inlet pipe, a water outlet pipe, a water pump, a frequency converter and a thermometer, wherein the cooling water source is communicated with the condenser through the water inlet pipe, the water outlet structure is communicated with the condenser through the water outlet pipe, the water pump is arranged on the water inlet pipe, and the water pump is connected with a motor;
the thermometer is arranged in the cooling water source and is electrically connected with the DCS control system and is used for detecting the temperature of the cooling water source and transmitting a detected real-time temperature value signal to the DCS control system;
the DCS control system is electrically connected with the frequency converter and is used for feeding back a frequency signal corresponding to the real-time temperature value signal to the frequency converter according to a mapping table of the temperature and the frequency stored in the DCS control system;
the frequency converter is electrically connected with the motor and is used for adjusting the frequency of the motor according to the frequency signal and adjusting the water outlet flow of the water pump.
Optionally, the temperature-frequency mapping table includes: the temperature of the cooling water source is 14-34 ℃, and the input frequency of the frequency converter is 50Hz; the temperature of the cooling water source is 8-14 ℃, and the input frequency of the frequency converter is 40Hz; the temperature of the cooling water source is lower than 8 ℃, and the input frequency of the frequency converter is 32.8Hz.
Optionally, the cooling unit further comprises a first breaker and a second breaker,
the first circuit breaker is arranged in parallel with the frequency converter, and the motor, a loop in parallel connection with the frequency converter and the power frequency power supply are connected in series; the second circuit breaker is arranged in a loop of the first circuit breaker connected with the frequency converter in parallel, and the second circuit breaker is connected with the frequency converter in series.
Optionally, the DCS control system is connected to the first circuit breaker and the second circuit breaker respectively, and is used for controlling the second circuit breaker to be opened and controlling the first circuit breaker to be opened according to the failure signal of the frequency converter, or is used for controlling the first circuit breaker to be opened and controlling the second circuit breaker to be opened according to the signal of the frequency converter recovering to be normal;
the first circuit breaker is used for feeding back an on-off signal of the first circuit breaker to the DCS control system;
the second circuit breaker is used for feeding back the on-off signal of the second circuit breaker to the DCS control system.
Optionally, the cooling unit further comprises a liquid level meter, the liquid level meter is arranged in the cooling water source, the liquid level meter is electrically connected with the DCS control system and used for detecting liquid level change in the cooling water source and transmitting a detected liquid level change signal to the DCS control system, and the DCS control system is further electrically connected with the water pump and used for controlling the start and stop of the water pump according to the liquid level change signal; and/or the number of the groups of groups,
the cooling unit further comprises a liquid level difference meter, a filter screen is arranged in the cooling water source, the liquid level difference meter is arranged on the filter screen, the liquid level difference meter is electrically connected with the DCS control system and used for detecting the water loss value of the filter screen and transmitting the detected water loss signal of the filter screen to the DCS control system, and the DCS control system is electrically connected with the water pump and used for controlling the start and stop of the water pump according to the water loss signal of the filter screen.
Optionally, the cooling unit still includes the vacuum break valve, all be equipped with on inlet tube and the drain pipe the vacuum break valve, DCS control system is connected with the vacuum break valve electricity for according to the start-stop signal of water pump, the break-make of control vacuum break valve.
Optionally, the vacuum break valve is a pneumatic diaphragm valve controlled by a pilot solenoid valve.
Optionally, the cooling unit further comprises a user input switch, and the user input switch is connected in series between the power frequency power supply and the frequency converter and is electrically connected with the input end and the output end of the DCS control system respectively.
The invention also provides a power generation system which comprises the condenser and the condenser cooling system.
Optionally, the condenser is provided with a plurality of cooling assemblies, two sets of cooling assemblies are arranged in the condenser, the cooling unit is correspondingly provided with two sets of cooling assemblies, the cooling unit further comprises a plurality of water inlet branch pipes and a plurality of water outlet branch pipes, the water inlet branch pipes are in one-to-one correspondence with the cooling assemblies corresponding to the condensers, the water outlet branch pipes are in one-to-one correspondence with the cooling assemblies corresponding to the condensers, the water inlet branch pipes are communicated between the water inlets of the corresponding water inlet pipes and the corresponding cooling assemblies, and the water outlet branch pipes are communicated between the corresponding water outlet pipes and the water outlets of the corresponding cooling assemblies; each water inlet branch pipe and each water outlet branch pipe are provided with a vacuum breaking valve.
Optionally, each water inlet branch pipe and each water outlet branch pipe are provided with an electric valve.
According to the invention, the temperature change signal transmitted by the thermometer is transmitted to the frequency converter through the DCS control system, and the frequency converter adjusts the frequency of the motor according to the temperature change signal, so that the water outlet flow of the water pump is adjusted, and the circulating water quantity can be regulated and controlled according to different seawater temperatures in different seasons, so that the problem of supercooling of the condenser caused by too low water temperature in winter in a northern nuclear power plant site is effectively solved, the running cost can be obviously saved, in addition, the shutdown and shutdown probability caused by a cold source plug is reduced through variable flow running, the running safety and stability of a nuclear power unit are improved, and the method has important engineering application value and economic benefit.
Drawings
Fig. 1 is a schematic structural diagram of a condenser cooling system provided in embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of switching between frequency conversion and power frequency schemes in embodiment 1 of the present invention;
FIG. 3 is a schematic illustration of a gearbox drive train connection to a lubrication system.
In the figure: 1. the remote transmission thermometer, 2, the remote transmission liquid level meter, 3, the filter screen, 4, the circulating water pump, 5, the converter, 6, the circulating water inlet tube, 7, the electric valve, 8, the condenser, 9, the DCS control system, 10, the vacuum break valve, 11, the circulating water drain pipe, 12, the siphon well, 13, the shield drain pipe, 14, the drainage culvert, 15, the drainage open channel, 16, the contactor switch, 17, the first circuit breaker, 18, the second circuit breaker, 19, the motor, 20, the door.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent, and the embodiments described in detail, but not necessarily all, in connection with the accompanying drawings. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
In the description of the present invention, it should be noted that the orientation or positional relationship indicated by "upper" or the like is based on the orientation or positional relationship shown in the drawings, and is merely for convenience and simplicity of description, and is not meant to indicate or imply that the apparatus or element to be referred to must be provided with a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "connected," "configured," "mounted," "secured," and the like are to be construed broadly and may be either fixedly connected or detachably connected, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood by those skilled in the art in specific cases.
The invention provides a condenser cooling system, comprising: a cooling water source, a cooling unit, a drainage structure and a DCS control system;
the cooling unit comprises a water inlet pipe, a water outlet pipe, a water pump, a frequency converter and a thermometer, wherein the cooling water source is communicated with the condenser through the water inlet pipe, the water outlet structure is communicated with the condenser through the water outlet pipe, the water pump is arranged on the water inlet pipe, and the water pump is connected with a motor;
the thermometer is arranged in the cooling water source and is electrically connected with the DCS control system and is used for detecting the temperature of the cooling water source and transmitting a detected real-time temperature value signal to the DCS control system;
the DCS control system is electrically connected with the frequency converter and is used for feeding back a frequency signal corresponding to the real-time temperature value signal to the frequency converter according to a mapping table of the temperature and the frequency stored in the DCS control system;
the frequency converter is electrically connected with the motor and is used for adjusting the frequency of the motor according to the frequency signal and adjusting the water outlet flow of the water pump.
The invention also provides a power generation system which comprises the condenser and the condenser cooling system.
Example 1:
the embodiment provides a condenser cooling system for cooling a condenser of a nuclear power plant or a thermal power plant.
As shown in fig. 1, it includes: a cooling water source, a cooling unit, a drainage structure and a DCS control system 9.
The cooling unit comprises a filter screen 3, a water inlet pipe 6, a water outlet pipe 11, a water pump 4, a frequency converter 5 and a thermometer 1. The cooling water source is communicated with the condenser 8 through the water inlet pipe 6, and the drainage structure is communicated with the condenser 8 through the drainage pipe 11. The water pump 4 is arranged on the water inlet pipe 6, the motor 19 is connected to the water pump 4, and the thermometer 1 is arranged in a cooling water source.
In this embodiment, the condenser 8 is equipped with three, is equipped with two sets of cooling module in the condenser 8, and cooling unit is equipped with two sets correspondingly, and every set of cooling unit still includes three water inlet branch pipe and three drainage branch pipe, and three water inlet branch pipe and the corresponding cooling module one-to-one of three condenser 8, and three drainage branch pipe and the corresponding cooling module one-to-one of three condenser 8 are intake branch pipe intercommunication between the water inlet of corresponding inlet tube 6 and corresponding cooling module, and the drainage branch pipe communicates between corresponding drain pipe 11 and the outlet of corresponding cooling module.
The drainage structure comprises a siphon well 12, a shield drain pipe 13, a drainage culvert 14 and a drainage open channel 15, wherein the siphon well 12, the shield drain pipe 13, the drainage culvert 14 and the drainage open channel 15 are sequentially communicated, a gate 20 is arranged at an inlet of the siphon well 12, and a gate 20 is also arranged at an inlet of the drainage culvert 14.
In this embodiment, the cooling water source is sea water, and the filter screen 3 is disposed in the sea water and in front of the water pump. Seawater is filtered by the filter screen 3 and then enters the condenser 8 through the circulating water inlet pipe 6 after being lifted by the circulating water pump 4, the outdoor part of the circulating water inlet pipe 6 is cast-in-situ reinforced concrete lining glass reinforced plastic pipe, the indoor part is an inner and outer wall reinforced corrosion-resistant carbon steel pipe, then enters the siphon well 12 through the circulating water drain pipe 11, the outdoor part of the circulating water drain pipe 11 is cast-in-situ reinforced concrete pipe, the indoor part is an inner and outer wall reinforced corrosion-resistant carbon steel pipe, a practical weir is arranged in the siphon well 12, and finally is discharged into the sea through the shield drain pipe 13, the drainage culvert 14 and the drainage open channel 15.
With continued reference to fig. 1, the thermometer 1 is electrically connected to an input end of the DCS control system 9, and is configured to detect a temperature of the cooling water source and transmit a detected real-time temperature value signal to the DCS control system 9;
the circuit input end of the frequency converter 5 is electrically connected with a power frequency power supply, the output end of the DCS control system 9 is electrically connected with a communication interface of the frequency converter 5, and is used for feeding back a frequency signal corresponding to a real-time temperature value signal to the frequency converter 5 according to a mapping table of temperature and frequency stored in the frequency converter;
the circuit output end of the frequency converter 5 is electrically connected with the motor and is used for adjusting the frequency of the motor 19 according to the frequency signal and adjusting the water outlet flow of the water pump 4.
Therefore, the circulating water pump 4 adopts variable frequency control, and the circulating water pump 4 runs in variable flow when the water temperatures in winter and summer are different, namely, the flow of the circulating water pump 4 is regulated according to the seawater temperature. The flow of the circulating water pump 4 is controlled (average is obtained) through two remote-transmission thermometers 8, and after the running is stable, the flow regulation can be realized through a set temperature and flow relation curve.
The invention determines the reasonable control logic relationship between the circulating water temperature and the circulating water flow through the cold end optimization calculation of the circulating water system. I.e. the following temperature versus frequency map: the design flow of the circulating water pump is A (14-34 ℃), and the corresponding input frequency is 50Hz; the minimum flow is C (lower than 8 ℃), and the corresponding input frequency is 32.8Hz; when the flow is B (8-14 ℃), the corresponding input frequency is 40Hz (the 3 gears are primarily determined, and the frequency modulation gear is determined according to the actual situation in the later period).
In this embodiment, as shown in fig. 2, the cooling unit further includes a first breaker 17 and a second breaker 18, where the motor 19, the first breaker 17 and the power frequency power supply are sequentially connected in series, and the first breaker 17 is arranged in parallel with the frequency converter 5; the second circuit breaker 18 is provided in a loop in which the first circuit breaker 17 is connected in parallel with the frequency converter 5, and the second circuit breaker 18 is connected in series with the frequency converter 5.
The power frequency bypass is assisted on the basis of variable frequency speed regulation, so that the power frequency bypass can normally operate when the variable frequency fails. The two second circuit breakers 18 are arranged, one second circuit breaker 18 is arranged between the frequency converter 5 and the power frequency power supply, and the other second circuit breaker 18 is arranged between the frequency converter 5 and the motor.
During variable frequency operation, the two second circuit breakers 18 are closed, and the first circuit breaker 17 is opened; the first circuit breaker 17 is closed and the two second circuit breakers 18 are opened during the power frequency operation. The motor 19 of the circulating water pump 4 adopts an asynchronous motor which is suitable for the requirements of a frequency converter, and the asynchronous motor is connected with the circulating water pump 4 through a gearbox transmission mechanism. The gearbox transmission mechanism ensures that the circulating water pump 4 can still operate at the designed rotating speed when the frequency converter is switched to the power frequency operation by fault.
As shown in fig. 3, the gearbox drive is connected to a lubrication system. The lubrication oil system includes a high pressure oil system and a low pressure oil system. The low-pressure oil system comprises a first lubricating oil branch, a second lubricating oil branch and a third lubricating oil branch which are connected in parallel.
The first lubricating oil branch comprises a small electric auxiliary oil pump, the small electric auxiliary oil pump is connected with the gear box to form a first lubricating oil loop, the second lubricating oil branch comprises a large electric auxiliary oil pump, the large electric auxiliary oil pump is connected with the gear box to form a second lubricating oil loop, the third lubricating oil branch comprises a mechanical oil pump, and the mechanical oil pump is connected with the gear box to form a third lubricating oil loop. Because the rotation speed of the water pump and the gearbox is lower when the frequency conversion system operates at low flow, the situation of insufficient oil supply can occur, and the gearbox is damaged. In order to improve the operation stability of the gearbox, the low-pressure oil system is provided with a mechanical oil pump, a large electric auxiliary oil pump and a small electric auxiliary oil pump. During normal operation, the mechanical oil pump supplies oil; and the large electric auxiliary oil pump supplies oil during starting, stopping and accident conditions. When the rotation speed of the gear box is low, oil is supplied by a small electric auxiliary oil pump.
The bottom of the gear box is provided with an axial thrust bearing, and a journal of an output shaft of the gear box is arranged in the axial thrust bearing; the high-pressure oil system comprises a fourth lubricating oil branch connected with an oil inlet hole of an axial thrust bearing of the gear box, a high-pressure oil pump is arranged in the fourth lubricating oil branch, and the high-pressure oil pump is connected with the gear box to form a fourth lubricating oil loop.
And the high-pressure oil system jacks up the axial thrust bearing at the bottom of the gear box at high pressure in the starting and stopping stages of the circulating water pump, lubricates the thrust bearing bush, and prevents the damage of the thrust bearing bush caused by dry friction of the thrust bearing bush when the gear box is started.
In this embodiment, the DCS control system 9 is connected to the input terminals of the first circuit breaker 17 and the second circuit breaker 18, respectively, for controlling the second circuit breaker 18 to open and the first circuit breaker 17 to open according to the failure signal of the frequency converter 5, or for controlling the first circuit breaker 17 to open and the second circuit breaker 18 to open according to the signal for recovering the frequency converter to be normal;
the output end of the first circuit breaker 17 is connected with the DCS control system 9 and is used for feeding back the on-off signal of the first circuit breaker 17 to the DCS control system 9;
the output end of the second circuit breaker 18 is connected with the DCS control system 9 and is used for feeding back the on-off signal of the second circuit breaker 18 to the DCS control system 9.
Therefore, the power frequency and variable frequency start-stop of the circulating water pump 4 are realized through the local and remote DCS, the frequency conversion/power frequency switching is realized through a manual mode on the spot, and the flow can be regulated by setting any frequency (50 Hz-32.8 Hz) at the DCS during operation. The adjustment of the water pump flow can be achieved at the remote DCS by manual/automatic means.
In this embodiment, the cooling unit further includes a user input switch 16, where the user input switch 16 is connected in series between the power frequency power supply and the circuit input end of the frequency converter 5, and the user input switch 16 is electrically connected to the input end and the output end of the DCS control system 9 respectively. Specifically, the user input switch 16 is a contactor.
Therefore, the water pump start-stop signal is indirectly transmitted to the DCS control system 9 by the user input switch 16, and the DCS control system 9 can also indirectly control the start-stop of the water pump by controlling the on-off of the user input switch 16.
In this embodiment, the cooling unit further includes a plurality of liquid level meters 2 and a plurality of sets of liquid level difference meters.
The liquid level meter 2 is arranged in the cooling water source, the liquid level meter 2 is electrically connected with the input end of the DCS control system 9, the liquid level meter 2 is used for detecting liquid level change in the cooling water source and transmitting a detected liquid level change signal to the DCS control system 9, and the DCS control system 9 is also electrically connected with the water pump 4 and used for controlling the start and stop of the water pump 4 according to the liquid level change signal.
The liquid level difference meter is arranged on the filter screen and is electrically connected with the input end of the DCS control system 9, and is used for detecting the water level difference before and after the filter screen, namely the water loss value of the filter screen, transmitting the detected water loss signal of the filter screen to the DCS control system 9, and controlling the start and stop of the water pump 4 by the DCS control system 9 according to the water loss signal of the filter screen.
Every three remote liquid level meters 2 correspond to one circulating water pump 4. Setting a start pump liquid level, a low liquid level alarm, a low stop pump liquid level, a high liquid level alarm and a stop pump safety liquid level.
Three sets of liquid level difference meters are arranged on the filter screen 3, and when two sets of signals in the three sets of liquid level difference meters are less than 0.1m water column, the drum-shaped filter screen runs at a low speed (the linear speed is 2.5 m/min). When the signals of two sets of liquid level difference meters in the three sets are more than or equal to 0.1m water column, the drum filter screen is switched to run at a medium-speed motor (the linear speed is 10 m/min), and an alarm is given once. When the signals of two sets of liquid level difference meters in the three sets are more than or equal to 0.2m water column, the drum filter screen is switched from medium speed to high speed operation (the linear speed is 20 m/min), and secondary alarm is carried out. When one set of liquid level difference meter signal in the three sets is more than or equal to 0.3m water column, a third alarm signal is sent to the main control room, and an operator checks the filter screen. When two sets of liquid level difference meter signals in the three sets are more than or equal to 0.8m water column, a fourth alarm signal is sent to the DCS control system 9, and the circulating water pump 4 is automatically tripped.
The circulating water pump 4 is started up and disabled due to reasons or stopped due to reasons, and alarms are given out in the DCS control system 9.
In this embodiment, the cooling unit further includes a vacuum breaking valve 10, the water inlet pipe 6 and the water outlet pipe 11 are both provided with the vacuum breaking valve 10, and the output end of the dcs control system 9 is electrically connected with the vacuum breaking valve 10, for controlling the on-off of the vacuum breaking valve 10 according to the start-stop signal of the water pump 4. When the water pump 4 is stopped, the vacuum break valve 10 is turned on, and when the water pump 4 is turned on, the vacuum break valve 10 is turned off.
The three water inlet branch pipes of each set of cooling unit are communicated through a public collecting water inlet pipe, and the three water outlet branch pipes of each set of cooling unit are communicated through a public collecting water outlet pipe. The common collecting water inlet pipe and the common collecting water outlet pipe are both provided with vacuum breaking valves 10. When the circulating water pump 4 is stopped, the vacuum breaking valve 10 of the corresponding circulating water loop is automatically opened to prevent the occurrence of a water hammer of the stopped pump.
The condenser inlet is in negative pressure operation under the working condition of small flow rate when water is normally supplied at the average low tide level or below, so that the condenser inlet cannot be provided with a vent valve in the selection of the measure of preventing water hammer, and a vacuum breaking valve is needed. For the power frequency system, a vacuum breaking valve is usually only arranged on the water outlet side of the circulating water of the condenser. And for the variable frequency system, through analysis and calculation, not only the vacuum breaking valve is arranged on the water outlet side of the circulating water of the condenser, but also the vacuum breaking valve is arranged on the water inlet side of the circulating water of the condenser, so that the condenser is prevented from being vaporized when the power-off and the pump-off of the lower tide level are realized, and the system can be in safe transition.
In this embodiment, through the instantaneous flow numerical simulation calculation of the circulating water system, reasonable water hammer prevention measures and instrument control schemes are determined, namely: before the circulating water pump starts, the DCS interlocking vacuum breaking valve is in a closed state. When the circulating water pump stops operating, the vacuum breaking valves at the top of the water inlet pipe and the water outlet pipe of the condenser are automatically and quickly opened within 0.4s, so that vaporization of the condenser is prevented, and the safe transition of the circulating water system is ensured.
The vacuum break valve 10 is a pneumatic diaphragm valve controlled by a pilot solenoid valve with a maximum opening time of 0.4 seconds.
In order to prevent large impact on the power grid, the time required for the frequency converter to automatically switch to the power frequency operation is about 2s. But is calculated by transient analysis of the circulating water system: in order to ensure that the condenser is not vaporized when the pump is stopped, a vacuum breaking valve arranged at the inlet and outlet of the condenser must be opened within 0.4 s; if the vacuum breaking valve arranged at the inlet and outlet of the condenser is opened for 2 seconds, the water chamber of the condenser is seriously vaporized. Meanwhile, under the condition that the vacuum breaking valve is fully opened, the circulating water pump is prohibited from being started. Whether the frequency conversion is switched to the power frequency or the power frequency is switched to the frequency conversion, a manual switching mode is recommended.
In addition, each water inlet branch pipe and each water outlet branch pipe are provided with an electric valve 7. The electric valve 7 is electrically connected with the output end of the DCS control system 9, so that the on-off of the electric valve 7 is remotely controlled through the DCS control system 9, and then the on-off of cooling water corresponding to the cooling component of the condenser 8 is controlled.
Example 2:
the present embodiment provides a power generation system, which includes a condenser 8 and further includes the condenser cooling system of embodiment 1.
The invention can be applied to the circulating water system of the nuclear power station and can be widely applied to the circulating water system of the thermal power station. Taking a nuclear power station as an example, after two million nuclear power units apply the system, the operation cost is saved by about 1137 ten thousand yuan annually, and the system has important engineering application value and obvious economic and social benefits.
It is to be understood that the above embodiments are merely illustrative of the application of the principles of the present invention, but not in limitation thereof. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the invention, and are also considered to be within the scope of the invention.
Claims (9)
1. A condenser cooling system for a nuclear power plant, comprising: a cooling water source, a cooling unit, a drainage structure and a DCS control system (9);
the cooling unit comprises a water inlet pipe (6), a water outlet pipe (11), a water pump (4), a frequency converter (5) and a thermometer (1), wherein a cooling water source is communicated with a condenser (8) through the water inlet pipe (6), a water outlet structure is communicated with the condenser (8) through the water outlet pipe (11), the water pump (4) is arranged on the water inlet pipe (6), and a motor (19) is connected to the water pump (4);
the thermometer (1) is arranged in the cooling water source and is electrically connected with the DCS control system (9) and is used for detecting the temperature of the cooling water source and transmitting a detected real-time temperature value signal to the DCS control system (9);
the DCS control system (9) is electrically connected with the frequency converter (5) and is used for feeding back a frequency signal corresponding to the real-time temperature value signal to the frequency converter (5) according to a mapping table of the temperature and the frequency stored in the DCS control system;
the frequency converter (5) is electrically connected with the motor and is used for adjusting the frequency of the motor (19) according to the frequency signal and adjusting the water outlet flow of the water pump (4);
the temperature and frequency mapping table includes: the temperature of the cooling water source is 14-34 ℃, and the input frequency of the frequency converter (5) is 50Hz; the temperature of the cooling water source is 8-14 ℃, and the input frequency of the frequency converter (5) is 40Hz; the temperature of the cooling water source is lower than 8 ℃, and the input frequency of the frequency converter (5) is 32.8Hz;
the cooling unit further comprises a liquid level difference meter, a filter screen is arranged in the cooling water source, the liquid level difference meter is arranged on the filter screen, the liquid level difference meter is electrically connected with the DCS control system (9) and used for detecting the water loss value of the filter screen and transmitting the detected water loss signal of the filter screen to the DCS control system (9), and the DCS control system (9) is electrically connected with the water pump (4) and used for controlling the start and stop of the water pump (4) according to the water loss signal of the filter screen:
three sets of liquid level difference meters are arranged on the filter screen, and when two sets of signals in the three sets of liquid level difference meters are less than 0.1m water column, the filter screen runs at a low speed with the linear speed of 2.5 m/min; when the signals of two sets of liquid level difference meters in the three sets are more than or equal to 0.1m water column, the filter screen is switched to run at a medium speed with the linear speed of 10m/min, and an alarm is given for one time; when the signals of two sets of liquid level difference meters in the three sets are more than or equal to 0.2m water column, the filter screen is switched from medium speed to high-speed operation with the linear speed of 20m/min, and secondary alarm is carried out; when one set of liquid level difference meter signal in the three sets is more than or equal to 0.3m water column, sending a third alarm signal to the main control room; when two sets of liquid level difference meter signals in the three sets are more than or equal to 0.8m water column, a fourth alarm signal is sent to the DCS control system (9), and the water pump (4) is automatically tripped.
2. Condenser cooling system according to claim 1, wherein the cooling unit further comprises a first circuit breaker (17) and a second circuit breaker (18),
the first circuit breaker (17) is arranged in parallel with the frequency converter (5), and the motor (19), a loop in which the first circuit breaker (17) is connected in parallel with the frequency converter (5) and a power frequency power supply are connected in series; the second circuit breaker (18) is arranged in a loop of the first circuit breaker (17) and the frequency converter (5) in parallel, and the second circuit breaker (18) is connected with the frequency converter (5) in series.
3. Condenser cooling system according to claim 2, characterized in that the DCS control system (9) is connected to the first circuit breaker (17) and the second circuit breaker (18), respectively, for controlling the second circuit breaker (18) to open and the first circuit breaker (17) to open according to a failure signal of the frequency converter (5), or for controlling the first circuit breaker (17) to open and the second circuit breaker (18) to open according to a signal for the frequency converter to return to normal;
the first circuit breaker (17) is used for feeding back an on-off signal of the first circuit breaker (17) to the DCS control system (9);
the second circuit breaker (18) is used for feeding back the on-off signal of the second circuit breaker (18) to the DCS control system (9).
4. A condenser cooling system according to claim 2 or 3, characterized in that the cooling unit further comprises a liquid level meter (2), the liquid level meter (2) is arranged in the cooling water source, the liquid level meter (2) is electrically connected with a DCS control system (9) for detecting liquid level changes in the cooling water source and transmitting detected liquid level change signals to the DCS control system (9), and the DCS control system (9) is further electrically connected with the water pump (4) for controlling the start and stop of the water pump (4) according to the liquid level change signals.
5. The condenser cooling system according to claim 4, wherein the cooling unit further comprises a vacuum breaking valve (10), the vacuum breaking valve (10) is arranged on the water inlet pipe (6) and the water outlet pipe (11), and the DCS control system (9) is electrically connected with the vacuum breaking valve (10) and is used for controlling the on-off of the vacuum breaking valve (10) according to the start-stop signal of the water pump (4).
6. Condenser cooling system according to claim 5, wherein the vacuum break valve (10) is a pilot solenoid valve controlled pneumatic diaphragm valve.
7. The condenser cooling system according to claim 5, wherein the cooling unit further comprises a user input switch (16), the user input switch (16) being connected in series between the mains frequency power supply and the frequency converter (5) and being electrically connected to an input and an output of the DCS control system (9), respectively.
8. A power generation system comprising a condenser (8), characterized by further comprising a condenser cooling system according to any one of claims 1-7.
9. The power generation system according to claim 8, wherein the condenser (8) is provided with a plurality of condensers, two sets of cooling components are arranged in the condenser (8), the cooling unit is provided with two sets respectively, the cooling unit further comprises a plurality of water inlet branch pipes and a plurality of water outlet branch pipes, the water inlet branch pipes are in one-to-one correspondence with the cooling components corresponding to the condensers (8), the water outlet branch pipes are communicated between the water inlet pipe (6) and the water inlet of the corresponding cooling components, and the water outlet branch pipes are communicated between the water outlet pipe (11) and the water outlet of the corresponding cooling components; each water inlet branch pipe and each water outlet branch pipe are provided with a vacuum breaking valve (10).
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