CN113860415B - Deoxygenation method, water supply system and catalytic deoxygenation device for emergency water supply tank of nuclear power plant - Google Patents
Deoxygenation method, water supply system and catalytic deoxygenation device for emergency water supply tank of nuclear power plant Download PDFInfo
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- CN113860415B CN113860415B CN202111126291.5A CN202111126291A CN113860415B CN 113860415 B CN113860415 B CN 113860415B CN 202111126291 A CN202111126291 A CN 202111126291A CN 113860415 B CN113860415 B CN 113860415B
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21D—NUCLEAR POWER PLANT
- G21D1/00—Details of nuclear power plant
- G21D1/02—Arrangements of auxiliary equipment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/08—Seawater, e.g. for desalination
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
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Abstract
The invention discloses a nuclear power plant emergency water supply tank deoxidization method, an emergency water supply system and a catalytic deoxidization device, wherein the catalytic deoxidization device comprises a water inlet isolation valve, a water supply pump, an oxyhydrogen mixer, a catalytic deoxidization resin bed and a water outlet isolation valve, wherein a water inlet of the water inlet isolation valve and a water outlet of the water outlet isolation valve are connected with an external water tank body; the catalytic deoxidizing device comprises a first control module, a second control module and a water supply pump, wherein the first control module is used for measuring the oxygen content value of the water tank body and comparing the oxygen content value with a preset oxygen content threshold value to obtain a first opening value for controlling the water inlet and outlet isolation valve assembly and the water supply pump; the water inlet and outlet isolation valve assembly comprises a water inlet isolation valve and a water outlet isolation valve. According to the nuclear power plant emergency water supply tank deoxygenation method, the water supply system and the catalytic deoxygenation device, the oxygen content value of the water tank body is measured, the first opening value is output according to the oxygen content value, the opening and closing conditions of the water inlet and outlet isolation valve assembly and the water supply pump are controlled, and the automatic control of catalytic deoxygenation of the water tank of the emergency water supply system is realized.
Description
Technical Field
The invention relates to the field of nuclear power plants, in particular to a method for deoxidizing an emergency water supply tank of a nuclear power plant, a water supply system and a catalytic deoxidizing device.
Background
In recent years, nuclear power industry in China is rapidly developed. With the start-up construction of Hua-long No. one and the successful research and development of CAP1400 as marks, china becomes a country with independent autonomous third-generation nuclear power technology and full industry chain after the nuclear power of the United states, france, russia and the like is strong.
The Hualong first nuclear power unit is a third generation nuclear power unit, and when normal water supply systems such as a main water supply flow control system (ARE) and a starting and stopping water supply system (AAD) ARE unavailable, an emergency water supply system (ASG) supplies emergency water to the steam generator so as to meet the functional requirement of continuously discharging waste heat of the Steam Generator (SG). The residual heat of the reactor coolant system (RCP) generates steam in a steam generator that is vented through a turbine bypass vent system (GCT-c), if available, or a steam atmospheric vent system (VDA).
The emergency water supply system functions as follows:
when a main steam line rupture (MSLB) event occurs, excess feedwater injection into the steam generator is prevented from causing core supercooling by isolating the emergency water injection lines (ASG system piping) of the affected steam generator.
The ASG system must ensure that emergency feedwater is provided to an intact steam generator during expected operating event (DBC-2), rare accident (DBC-3), extreme accident (DBC-4) conditions, core decay heat and sensible heat of the reactor coolant system (RCP) system is conducted out through the steam generator, and continued until the safety injection system (RIS) operates in a residual heat removal mode (RHR).
In the event of se:Sub>A complex sequence of events (DEC-se:Sub>A), such as se:Sub>A plant outage (SBO) or complete loss of cold chain (TLOCC), the ASG system provides emergency feedwater to the steam generator, through which core decay heat and sensible heat of the RCP system are exported, bringing the plant to se:Sub>A final state.
Under the accident condition that the secondary side of the steam generator is communicated, such as the rupture of a heat transfer tube (SGTR), an emergency water injection pipeline (ASG system pipeline) of the affected steam generator is isolated, and the release of radioactive substances to the environment is prevented, so that the containment of the radioactive substances is realized.
Under the working condition of water supply pipeline rupture (FLB) or MSLB accident in the containment, an emergency water injection pipeline (ASG system pipeline) of the affected steam generator is isolated, the flow of high-temperature and high-pressure fluid sprayed into the containment through the rupture is reduced, and the failure of the integrity of the third barrier caused by continuous rising of the pressure and the temperature of the containment is prevented.
During normal shutdown of the power plant, water is injected into the steam generator, and chemical agents provided by a nuclear island chemical dosing System (SIH) are injected into the steam generator at the same time to complete wet maintenance operation.
During normal power plant start-up, the steam generator is initially filled with water. Before the average temperature of the first loop reaches 80 ℃, the steam generator is supplemented with water necessary to maintain the normal water level. During water filling, the SIH system provides chemicals to ensure that the feedwater meets the water quality requirements of the steam generator.
As shown in fig. 1, the ASG system consists of three separate emergency feedwater pump trains. Each ASG emergency feed pump series contains the following equipment:
a concrete tank;
an emergency water supply pump;
a steam generator level regulating valve;
an external containment isolation valve;
associated valves and pipes.
The ASG water tank is mainly technically characterized in that:
concrete structure, cuboid, stainless steel lining for inner surface, inner bottom area 77.5m 2 The net height is 8.94m;
minimum effective water volume 516.2m 3 To meet the safety requirement of 24 hours of hot shutdown; alarming when the liquid level is lower than 2;
the water temperature is 10-50 ℃ (24 hours in accident, 10-60 ℃);
normal charging of the partial alkaline demineralized water distribution System (SER) demineralized water, emergency water replenishment from the secondary side passive waste heat drain system (ASP), mobile water source as backup;
the installation is arranged at the level of-4.9 m of the safety factory building, and the top is opened to the atmosphere;
provided with a separate mixing pump and lines;
the water in the water tank is oxygen-containing desalted water, SER oxygen-containing water is used for supplementing water or filling water, and nitrogen is not used for covering. A nuclear island chemical dosing System (SIH) dosing line is effective only when filling a Steam Generator (SG) with water downstream of an ASG pump outlet water level regulator valve.
The water stored in the ASG water tank of Hualong No. one is designed to be oxygen-containing water, so that a plurality of safety problems and unit availability influence are caused. The following is a description of specific problems.
1. Safety problem:
the corrosion of the structural materials of the secondary side of the steam generator, the leakage of water supply and a condenser are the main sources of impurities of the secondary side. If the impurities are not removed by the condensate polishing system or the steam generator sewage system, dirt is enriched and formed in the steam generator, so that problems of corrosion of a heat transfer pipe of the steam generator, reduction of heat transfer efficiency, reduction of pressure of main steam and the like are caused.
Table 1 shows the requirements of the water quality of SG by Hualong No. I chemical specification and preliminary safety analysis report.
Description:
when starting from hot standby, pH, NH 4 + 、O 2 The Fe value may be higher.
ADG (feedwater deaerator system) monitoring as an AHP backup monitoring point.
TABLE 1 steam generator normal feedwater chemical specification requirements
According to the analysis, the water quality of SG can be influenced by injecting the oxygen-containing water of the ASG water tank of Hualong No. one into the SG steam generator, thereby influencing the service life of SG, and even causing the steam generator to leak out of a heat transfer tube, thereby influencing the integrity of the steam generator. The following two conditions of Hualong one lead to the oxygen water in the ASG water tank entering SG:
(1) Under the accident condition, when the normal water supply is lost, the SG is low by 2 liquid levels, an off-site electricity (LOOP) signal and a safe injection signal are lost, and the ASG auxiliary water supply is started. Due to the oxygen-containing water quality of the ASG water tank, the accident water supply corrodes the SG, affecting the integrity and life of the steam generator.
(2) The Hualong No. one ASG system operates the periodic test, has effects on SG water quality: the water in the ASG water tank is actually injected into the steam generator when the ASG pump full flow test (once per fuel cycle), ASG system cavitation margin test (once per two fuel cycles), ASG power limiting valve mechanical limit test (once per 10 fuel cycles), and the like are tested.
Under the condition of the accident of condenser seawater leakage, the chemical technical specification and the operation program of the second generation unit require that the corresponding circulating water system (CRF) pump is shut down, the power is reduced to the thermal shutdown as soon as possible, and when the power is less than 2%Pn, the water supply of the steam generator is switched to ASG, so that the ARE water supply is directly replaced. In the Hualong No. I, due to the design of the oxygen-containing water of the ASG water tank, the ASG deoxygenated water cannot be used for supplying water to the SG, the unit cannot stay in the mode 1 or the mode 2, and the unit needs to be withdrawn to the mode 4 of the safety injection system (RIS) operated in the residual heat removal mode (RHR), so that the water quality deterioration time of the SG and the maintenance period of the unit are increased.
Since routine island maintenance involving condenser vacuum failure during the day-to-day period of the unit requires a loop to be retracted in coordination with mode 4 in which the safety injection system (RIS) is operated in the residual heat removal mode (RHR), unlike the second generation nuclear power unit which only requires retraction to a hot shutdown or hot standby state. The Hualong first unit increases the risk of back-off operation and mode conversion operation and also increases the risk of human error and equipment impact damage.
Under the conditions of temporary shutdown, important fault maintenance of a conventional island, overhaul and the like, the unit can transition between power operation and operation of a safety injection system in a residual heat removal mode (RIS/RHR) for a plurality of times in one fuel cycle, the frequency of using an isolation valve between the RIS and the RCP is greatly increased compared with that of a secondary nuclear power unit, the frequency of valve faults is also increased, and then the safety influence is brought.
2. Unit availability impact:
the design of the oxygen-containing water supply of the ASG water tank of the Hua-long one number can affect the overhaul period and the period of unscheduled shutdown overhaul.
A. Actual construction period of overhaul becomes long
In the start-stop stage, due to the design of oxygen-containing water of an ASG water tank, an ASG cannot be used for cooling a loop when a unit goes down, and a turbine bypass exhaust system (GCT-c) and a main water supply system (ARE) ARE required to operate to take out heat of a steam generator until the temperature of the loop reaches 120 ℃, and a waste heat discharge mode (RIS/RHR) of a safety injection system is connected; leaving RIS/RHR mode before 120deg.C during upstream requires turbine bypass bleed system (GCT-c) and ARE to run cooling one loop, making two loop preparation, flushing, etc. work in parallel with the one loop warming up, boosting up to critically. The two-loop water supply loop and the steam loop are stopped and the two-loop maintenance and the one-loop maintenance cannot be carried out simultaneously as a whole, the two-loop maintenance availability time becomes very short, the two-loop maintenance becomes a critical path, and the actual period of overhaul is prolonged. The CPR1000 unit descends to switch the water supply of the steam generator from ARE to ASG when the reactor thermal power is less than 2%Pn, and adopts an atmospheric emission system (GCT-a) to cool the primary loop, at the moment, the primary steam isolation valve can be closed, the primary loop and the secondary loop ARE separated, and the shutdown and maintenance of the secondary loop ARE started. Similarly, when CPR1000 is up, the steam generator is supplied with water from the ASG before the reactor thermal power is 2% Pn, and the atmospheric exhaust system (GCT-a) is used to cool the primary circuit without the need for two-circuit operation.
Table 2 Hualong No. one major repair routine island construction period calculation
Since the Hua-Lon No. one unit has no multiple overhaul examples, as shown in Table 2, the data of about 9 major repairs of a certain CPR1000 unit is used for calculation, and the conventional island construction period of the unit is added with about 5 days (the two circuits are matched with one circuit to cause downstream delay and upstream advance time) to be used as the Hua-Lon No. one conventional island major repair period. The calculation result shows that 8 major repair of the island is all the key path, and the major repair period is prolonged by 2-5 days to a different degree beyond the original actual period, so that huge economic loss is caused.
B. Effect on daily unscheduled overhauls:
routine island defects need to be salvaged and the nuclear island of CPR1000 need only be backed up to a hot standby or hot shutdown state. But the Hualong first unit needs to be retracted to a mode 4 in which a safety injection system (RIS) operates in a residual heat removal mode (RHR), and is retracted deeper; for example the following routine maintenance works:
the shafting of the turbo generator set works, a steam turbine steam bypass discharge system (GCT-c) is disassembled and overhauled, a condenser is required to break vacuum, and a vehicle is stopped;
two-circuit water side related defects: the main water supply isolation valve cannot be closed, a main water supply system (ARE) pipeline test pore plate or venturi tube leaks or fails, a condensate pump inlet or outlet main tube leaks little, a deaerator body steam side pipeline leaks and the like, two loops of water supply cannot be immediately lost but cannot be isolated, the efficiency of a unit is reduced, and the unit has great industrial safety risk;
the two pumps are stopped completely due to the problems of high pressure difference of the drum net and the like caused by faults or foreign sea factors of the circulating water pump.
C. Influence on daily planned temporary stops
At present, the nuclear power unit is involved in power grid peak shaving and is stopped for many times each year according to the power grid requirement, so that the unit can stay in an NS/SG mode by matching Hualong No. one ARE+GCT-c, but the Hualong design is an NS/SG mode and an unstable operation mode; under the working condition, the APA pump is always in a low-flow operation working condition, and the reliability of the APA pump and the deaerator is influenced at the moment; therefore, in the normal temporary stop condition, the machine set needs to be withdrawn to the mode 4 in which the safety injection system (RIS) operates in the residual heat removal mode (RHR), which results in that the time for cooling down, heating up and boosting is much longer than that of the CPR1000 in the start-stop stage, and corresponding economic loss is brought.
Disclosure of Invention
Aiming at the defects, the invention provides an improved method for deoxidizing an emergency water supply tank of a nuclear power plant, an emergency water supply system and a catalytic deoxidizing device.
The technical scheme adopted for solving the technical problems is as follows: the catalytic deoxidization device comprises a water inlet isolation valve, a water supply pump, an oxyhydrogen mixer, a catalytic deoxidization resin bed and a water outlet isolation valve which are sequentially connected, wherein a water inlet of the water inlet isolation valve and a water outlet of the water outlet isolation valve are respectively connected with an external water tank body;
the catalytic deoxidizing device further comprises a first control module, wherein the first control module is used for measuring the oxygen content value of the water tank body and comparing the oxygen content value with a preset oxygen content threshold value to obtain a first opening value for controlling the water inlet and outlet isolation valve assembly and the water feed pump; the water inlet and outlet isolation valve assembly comprises the water inlet isolation valve and the water outlet isolation valve.
Preferably, the catalytic deoxidizing device further comprises a second control module, wherein the second control module is used for measuring the liquid level value of the water tank body and comparing the liquid level value with a preset liquid level threshold value so as to obtain a second opening value for controlling the water inlet and outlet isolation valve assembly and the water feeding pump.
Preferably, the catalytic deoxidizing device further comprises a third control module, wherein the third control module is used for receiving the first opening value and the second opening value, and comparing the first opening value with the second opening value to obtain a third opening value for controlling the water inlet and outlet isolation valve assembly and the water feeding pump.
Preferably, the catalytic deoxidizing device further comprises a degassing tower and a degassing fan, wherein the degassing fan is used for blowing gas into the degassing tower, the degassing tower is connected with the catalytic deoxidizing resin bed, and the degassing tower is used for discharging hydrogen in the catalytic deoxidizing resin bed.
Preferably, the catalytic deoxygenation device further comprises a resin trap disposed between the catalytic deoxygenation resin bed and the effluent isolation valve, the resin trap for capturing resin.
The utility model also provides a nuclear power plant emergency water supply tank deoxidization method, which comprises the following steps:
s1, measuring an oxygen content value of a water tank body;
s2, judging whether the oxygen content value exceeds a preset first oxygen content threshold value, if so, executing a step S3; if not, the current situation is maintained;
s3, outputting a first opening signal, and opening a water inlet and outlet isolation valve assembly of the catalytic deoxidizing device and the water supply pump according to the first opening signal;
s4, judging whether the oxygen content value is lower than a preset second oxygen content threshold value, and if so, outputting a first closing signal; if not, the current situation is maintained; the water inlet and outlet isolation valve assembly and the water feed pump are closed according to the first closing signal;
wherein the first opening value comprises the first opening signal and the first closing signal.
Preferably, the method for deoxidizing the emergency water supply tank of the nuclear power plant further comprises the following steps:
s5, measuring the liquid level value of the water tank body,
s6, judging whether the liquid level value is lower than a preset liquid level threshold value, if so, executing a step S7; if not, executing step S8;
s7, outputting a second closing signal, wherein the water inlet and outlet isolation valve assembly and the water supply pump are closed according to the second closing signal;
s8, keeping the current situation;
wherein the second opening value comprises the second closing signal.
Preferably, the method for deoxidizing the emergency water supply tank of the nuclear power plant further comprises the following steps:
s9, receiving the first opening value and the second opening value;
s10, judging whether the first opening value is a first opening signal and the second opening value is a second closing signal, if yes, executing a step S11;
s11, outputting a third opening value, wherein the third opening value comprises a third closing signal, and the water inlet and outlet isolation valve assembly and the water feeding pump are closed according to the third closing signal.
The emergency water supply system of the nuclear power plant comprises a water tank assembly and the catalytic deoxidizing device;
the water tank assembly comprises a water tank body, an oxygen analyzer and a liquid level meter, wherein the oxygen analyzer and the liquid level meter are respectively connected with the water tank body; the catalytic deoxidizing device is connected with the water tank assembly.
Preferably, the water tank assembly further comprises a nitrogen gas supply isolation valve and a nitrogen gas pressure regulating valve which are respectively connected with the water tank body, wherein the nitrogen gas supply isolation valve is used for introducing nitrogen gas, and the nitrogen gas pressure regulating valve is used for regulating nitrogen gas pressure.
The implementation of the invention has the beneficial effects that: according to the nuclear power plant emergency water supply tank deoxidizing method, the emergency water supply system and the catalytic deoxidizing device, the oxygen content value of the water tank body is measured, and the first opening value is output according to the oxygen content value, so that the opening and closing conditions of the water inlet and outlet isolation valve assembly and the water supply pump are controlled, and the automatic catalytic deoxidizing control of the water tank of the emergency water supply system is realized.
The invention discloses a method for deoxidizing an emergency water supply tank of a nuclear power plant, an emergency water supply system and a catalytic deoxidizing device, which are designed for deoxidizing an emergency water supply system (ASG) water tank of a Hua-Dragon-I nuclear power unit (a third-generation nuclear power unit), deoxidize the ASG water tank, keep the oxygen content of water in the ASG water tank lower than the limit value of the water inlet oxygen content of a steam generator, and greatly improve the safety, flexibility and unit availability of the Hua-Dragon-I nuclear power unit.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a prior art emergency water supply system for a nuclear power plant;
FIG. 2 is a schematic diagram of a nuclear power plant emergency feedwater system in accordance with some embodiments of the present invention;
FIG. 3 is a schematic diagram of a catalytic deoxygenation device in accordance with some embodiments of the present invention;
FIG. 4 is a flow chart of a method of deoxygenating an emergency feedwater tank of a nuclear power plant in some embodiments of the present invention;
FIG. 5 is a flow chart of a method for deoxygenating an emergency feedwater tank of a nuclear power plant in accordance with further embodiments of the present invention;
FIG. 6 is a flow chart of a method for deoxygenating an emergency water supply tank of a nuclear power plant in accordance with certain preferred embodiments of the present invention.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.
Fig. 2 illustrates an emergency water supply system for a nuclear power plant according to some embodiments of the present invention, which is configured to perform chemical catalytic deoxygenation for an ASG water tank by using a catalytic deoxygenation device 10, so as to ensure that water stored in the ASG water tank is deoxygenated water, thereby eliminating or reducing the influence of defects in the prior art on safety and availability of a unit. The emergency water supply system of the nuclear power plant comprises a water tank assembly 20 and a catalytic deoxidizing device 10, wherein the catalytic deoxidizing device 10 is connected with the water tank assembly 20.
The water tank assembly 20 comprises a water tank body 21, and an oxygen analyzer 22 and a liquid level meter 23 which are respectively connected with the water tank body 21. The oxygen analyzer 22 is used for measuring the oxygen content value in the water tank 21, and the liquid level meter 23 is used for measuring the liquid level value.
In some preferred embodiments, the tank assembly 20 further includes a nitrogen gas supply isolation valve 25 and a nitrogen gas pressure regulating valve 26 connected to the tank body 21, respectively, the nitrogen gas supply isolation valve 25 being used for introducing nitrogen gas, and the nitrogen gas pressure regulating valve 26 being used for regulating the nitrogen gas pressure. The advantage of setting up nitrogen gas supply isolation valve 25 and nitrogen gas pressure control valve 26 is that water tank box 21 adopts the mode that nitrogen gas covered, reducible or prevent that oxygen from getting into water tank box 21 from leading to the deoxidization water oxygen content in the water tank box 21 to rise, simultaneously, sets up water tank nitrogen gas pressure control valve 26, guarantees that water tank box 21 pressure is the micro-positive pressure. The nitrogen pressure regulating valve 26 exhausts to the outside of the factory building, so that nitrogen is prevented from gathering in the factory building, and industrial safety risks are brought.
The catalytic deoxidizing device comprises a water inlet isolation valve, a water supply pump, an oxyhydrogen mixer, a catalytic deoxidizing resin bed, a water outlet isolation valve, a degassing tower, a degassing fan, a resin catcher, a first control module, a second control module and a third control module, and is shown in the combination of fig. 2 and 3. In the catalytic deoxidizing device, the water feeding pump absorbs water from the outlet pipeline of the water tank body through the water inlet isolation valve, and the liquid in the water tank body returns to the water tank body after deoxidizing through the oxyhydrogen mixer and the catalytic deoxidizing resin bed, so that the dissolved oxygen level is kept within the chemical limit range.
Wherein, inlet isolation valve 191, feed pump 11, oxyhydrogen blender 12, catalytic deoxidization resin bed 13 and play water isolation valve 192 connect gradually, and inlet isolation valve 191's water inlet, play water isolation valve 192's delivery port is connected outside water tank box 21 respectively.
The oxyhydrogen mixer 12 is a stainless steel in-line static mixer, and the liquid in the tank body 21 of the water tank is driven by the feed pump 11 into the oxyhydrogen mixer 12 to be mixed with the injected hydrogen. Hydrogen gas is injected from the bottom of the oxyhydrogen mixer 12 and is dissolved in water while flowing upward through the oxyhydrogen mixer 12.
Undissolved hydrogen leaves the oxyhydrogen mixer 12 and enters the catalytic deoxygenation resin bed 13. After adding hydrogen gas to the oxyhydrogen mixer 12, water enters a catalytic deoxidizing resin bed 13, and the catalytic deoxidizing resin bed 13 contains an anionic resin as a catalyst for converting an oxygen-hydrogen mixture into water. The hydrogen and oxygen are combined in the catalytic deoxygenation resin bed 13 by catalytic reaction to produce by-product water. Equation of reaction is 2H 2 +O 2 ＝2H 2 O. The deoxygenated water flows out of the catalytic deoxygenated resin bed 13 back into the tank body 21.
It will be appreciated that the inlet isolation valve 191, feed pump 11, oxyhydrogen mixer 12, catalytic deoxygenation resin bed 13, and outlet isolation valve 192 constitute a catalytic deoxygenation process. The water inlet isolation valve 191 and the water outlet isolation valve 192 are respectively used for water inlet and water outlet, the water supply pump 11 is used for providing power, the oxyhydrogen mixer 12 is used for mixing hydrogen, and the catalytic deoxidizing resin bed 13 is used for catalytic deoxidizing. The inlet isolation valve 191, the feed pump 11, the oxyhydrogen mixer 12, the catalytic deoxygenation resin bed 13 and the outlet isolation valve 192 constitute the most basic catalytic deoxygenation process.
In some preferred embodiments, the catalytic deoxygenation device 10 further comprises a degassing tower 15 and a degassing fan 151, the degassing fan 151 is used for blowing gas into the degassing tower 15, the degassing tower 15 is connected with the catalytic deoxygenation resin bed 13, and the degassing tower 15 is used for discharging hydrogen in the catalytic deoxygenation resin bed 13. Specifically, a continuous discharge line is provided to the forced air purged deaeration tower 15, and the deaeration tower 15 is discharged to the atmosphere outside the plant. The provision of the degassing tower 15 and the degassing fan 151 has the advantage of preventing any accumulation of hydrogen in the catalytic deoxidizing resin bed 13.
In some preferred embodiments, catalytic deoxygenation device 10 further includes a resin trap 14 disposed between catalytic deoxygenation resin bed 13 and effluent isolation valve 192, resin trap 14 being used to capture resin. Specifically, a resin trap 14 is provided on the outlet line of the catalytic deoxygenated resin bed 13. The benefit of providing resin trap 14 is that if a failure occurs inside catalytic deoxygenated resin bed 13, resin trap 14 will trap resin.
In some embodiments, catalytic deoxygenation device 10 further includes a first control module 16, a second control module 17, and a third control module 18.
The first control module 16 is configured to measure an oxygen content value of the water tank 21, and compare the oxygen content value with a preset oxygen content threshold value to obtain a first opening value for controlling the water inlet and outlet isolation valve assembly and the water feed pump 11; the inlet and outlet isolation valve assembly includes an inlet isolation valve 191 and an outlet isolation valve 192. The second control module 17 is configured to measure a liquid level value of the tank body 21, and compare the liquid level value with a preset liquid level threshold value to obtain a second opening value for controlling the water inlet/outlet isolation valve assembly and the water feed pump 11. The third control module 18 is configured to receive the first opening value and the second opening value, and compare the first opening value with the second opening value to obtain a third opening value for controlling the water inlet and outlet isolation valve assembly and the water feed pump 11.
As can be appreciated, the first control module 16 is connected to the oxygen analyzer 22 to measure the oxygen content value of the tank 21; the second control module 17 is connected with the liquid level meter 23 so as to measure the liquid level value of the water tank body 21; the third control module 18 is connected to the first control module 16 and the second control module 17, thereby obtaining a first opening value and a second opening value. The first control module 16, the second control module 17 and the third control module 18 are all connected with the water inlet and outlet isolation valve assembly and the water feed pump 11, so that the first opening value, the second opening value and the third opening value are sent to the water inlet isolation valve 191, the water outlet isolation valve 192 and the water feed pump 11, and the opening and closing states of the water inlet isolation valve 191 and the water outlet isolation valve 192 and the starting and stopping of the water feed pump 11 are controlled.
The provision of the first control module 16, the second control module 17 and the third control module 18 has the advantage that the catalytic deoxygenator device 10 can be activated and deactivated in situ or "automatically". When the unit is switched to a remote control mode on the local control cabinet, the catalytic deoxidizing device 10 can be controlled remotely and receives a remote start permission command and a remote stop permission command sent by the main control room. The specific mode is as follows:
in the automatic control state, the catalytic deoxidizing device 10 is interlocked with the oxygen analyzer 22 and the liquid level meter 23 of the water tank body 21. If the oxygen analyzer 22 has high oxygen content signal, the water inlet isolation valve 191 is automatically opened, the catalytic deoxygenation process is automatically started, and the water outlet isolation valve 192 is also automatically opened; if the oxygen content is low, the catalytic deoxidization process is automatically stopped, and the water inlet isolation valve 191 and the water outlet isolation valve 192 are automatically closed; if a low liquid level signal of the water tank body 21 is received, the catalytic deoxygenation process is automatically stopped, and the low liquid level signal is superior to the signal of the oxygen analyzer 22, so as to ensure that the water supply pump 11 of the catalytic deoxygenation device 10 has a sufficient net suction pressure head.
Alternatively, the first control module 16, the second control module 17 and the third control module 18 may or may not be provided. When the first control module 16, the second control module 17 and the third control module 18 are not provided, the water inlet and outlet isolation valve assembly and the water feed pump 11 are manually controlled, that is, the water inlet isolation valve 191 and the water outlet isolation valve 192 are manually opened or closed by a manual mode, and the water feed pump 11 is manually started or stopped.
The following describes specific steps of a method for deoxygenating an emergency water supply tank of a nuclear power plant in accordance with some embodiments of the present invention in conjunction with FIGS. 2-6. The nuclear power plant emergency water supply tank deoxidization method is used for carrying out chemical catalytic deoxidization on an ASG water tank through the chemical catalytic deoxidization device 10, and ensures that the stored water in the ASG water tank is deoxidized water, thereby eliminating or reducing the influence of defects in the prior art on the safety and availability of a unit.
Referring to fig. 2-4, the method for deoxidizing an emergency water supply tank of a nuclear power plant in some embodiments includes steps S1-S4:
s1, measuring an oxygen content value of a water tank body 21;
s2, judging whether the oxygen content value exceeds a preset first oxygen content threshold value, if so, executing a step S3; if not, the current situation is maintained;
s3, outputting a first opening signal, and opening the water inlet and outlet isolation valve assembly of the catalytic deoxidizing device 10 and the water supply pump 11 according to the first opening signal;
s4, judging whether the oxygen content value is lower than a preset second oxygen content threshold value, and if so, outputting a first closing signal; if not, the current situation is maintained; the water inlet and outlet isolation valve assembly and the feed pump 11 are turned off according to the first turn-off signal.
In steps S1-S4, the first control module 16 measures the oxygen content value of the water tank 21, and compares the oxygen content value with a preset oxygen content threshold value to obtain a first opening value for controlling the water inlet/outlet isolation valve assembly and the water feed pump 11. The oxygen content threshold comprises a first oxygen content threshold and a second oxygen content threshold, and the first opening value comprises a first opening signal and a first closing signal. If the oxygen content value exceeds a preset first oxygen content threshold value, outputting a first opening signal to enable the water inlet and outlet isolation valve assembly and the water feed pump 11 to be opened; if the oxygen content value is lower than a preset second oxygen content threshold value, a first closing signal is output, so that the water inlet and outlet isolation valve assembly and the water feeding pump 11 are closed. The inlet and outlet isolation valve assembly includes an inlet isolation valve 191 and an outlet isolation valve 192. In some preferred embodiments, the first oxygen content threshold is 15 μg/kg or 20 μg/kg and the second oxygen content threshold is 5 μg/kg. The oxygen content threshold can be set according to actual requirements, and is not limited herein, so long as the related functions can be realized.
Specifically, if the oxygen analyzer 22 receives a high oxygen content signal, the water inlet isolation valve 191 is automatically opened, the catalytic deoxygenation process is automatically started, and the water feed pump 11 and the water outlet isolation valve 192 are also automatically opened; if the oxygen content is low, the catalytic deoxygenation process is automatically stopped, and the water inlet isolation valve 191, the water feed pump 11 and the water outlet isolation valve 192 are automatically closed.
Referring to fig. 2-5, the method for deoxidizing an emergency water supply tank of a nuclear power plant in some embodiments further includes steps S5-S8:
s5, measuring the liquid level value of the water tank body 21,
s6, judging whether the liquid level value is lower than a set liquid level threshold value, if so, executing a step S7; if not, executing step S8;
s7, outputting a second closing signal, and closing the water inlet and outlet isolation valve assembly and the water feed pump 11 according to the second closing signal;
s8, keeping the current situation;
wherein the second opening value comprises a second closing signal.
In steps S5-S8, the second control module 17 is configured to measure a liquid level value of the tank body 21, and compare the liquid level value with a preset liquid level threshold value, so as to obtain a second opening value for controlling the water inlet/outlet isolation valve assembly and the water feed pump 11. If the liquid level value is lower than a preset liquid level threshold value, outputting a second closing signal to close the water inlet and outlet isolation valve assembly and the water feed pump 11; if the liquid level value is not lower than the preset liquid level threshold value, the current state is maintained. Preferably, the liquid level threshold is 0.5m. The liquid level threshold can be set according to actual requirements, and is not limited herein, so long as the relevant functions can be realized.
Referring to fig. 2-6, the method for deoxidizing an emergency water supply tank of a nuclear power plant in some embodiments further includes steps S9-S11:
s9, receiving a first opening value and a second opening value;
s10, judging whether the first opening value is a first opening signal and the second opening value is a second closing signal, if yes, executing a step S11;
s11, outputting a third opening value, wherein the third opening value comprises a third closing signal, and the water inlet and outlet isolation valve assembly and the water feed pump 11 are closed according to the third closing signal.
In steps S9-S11, the third control module 18 receives the first opening value and the second opening value, and compares the first opening value with the second opening value to obtain a third opening value for controlling the water inlet and outlet isolation valve assembly and the feed pump 11. If the first opening value is a first opening signal and the second opening value is a second closing signal, outputting a third closing signal to close the water inlet and outlet isolation valve assembly and the water feed pump 11; if the first opening value is not the first opening signal and the second opening value is the second closing signal, the current state is not output, namely, the current state is maintained. The advantage of this is that the level value of the level gauge 23 is better than the oxygen content value of the oxygen analyzer 22 to ensure a sufficient net suction head of the feedwater pump 11 of the catalytic deoxygenation device 10.
In other embodiments of the present invention, a catalytic deoxygenation device 10 is provided, which is identical to the catalytic deoxygenation device 10 in the previous embodiments, and will not be described herein, so long as the related functions can be implemented.
In some embodiments of the invention, a set of catalytic deoxidizing device 10 is arranged for the water tank of the emergency water supply ASG system of the Hualong first nuclear power unit, so that the water in the ASG water tank can be deoxidized manually or automatically, and the oxygen content of the ASG water tank is kept within the limit value. Compared with the prior art that the ASG water tank is oxygen-containing water, the method effectively avoids corrosion of the steam generator caused by water injection of the ASG water tank into the steam generator under accident working conditions and test conditions, and avoids the shortened service life of the steam generator. Meanwhile, the ASG can realize the cooling function of the steam generator during normal uplink and downlink, thereby greatly improving the flexibility and the availability of the unit.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.
Claims (6)
1. The catalytic deoxidization device is characterized by comprising a water inlet isolation valve (191), a water supply pump (11), an oxyhydrogen mixer (12), a catalytic deoxidization resin bed (13) and a water outlet isolation valve (192) which are sequentially connected, wherein a water inlet of the water inlet isolation valve (191) and a water outlet of the water outlet isolation valve (192) are respectively connected with an external water tank body (21);
the water inlet isolation valve (191) is used for water inlet, and the water outlet isolation valve (192) is used for water outlet;
the catalytic deoxidizing device (10) further comprises a first control module (16), wherein the first control module (16) is used for measuring an oxygen content value of the water tank body (21) and comparing the oxygen content value with a preset oxygen content threshold value to obtain a first opening value for controlling the water inlet and outlet isolation valve assembly and the water supply pump (11); the water inlet and outlet isolation valve assembly comprises the water inlet isolation valve (191) and the water outlet isolation valve (192);
the catalytic deoxidizing device (10) further comprises a second control module (17), wherein the second control module (17) is used for measuring the liquid level value of the water tank body (21) and comparing the liquid level value with a preset liquid level threshold value to obtain a second opening value for controlling the water inlet and outlet isolation valve assembly and the water feeding pump (11);
the catalytic deoxidizing device (10) further comprises a third control module (18), wherein the third control module (18) is used for receiving the first opening value and the second opening value, and comparing the first opening value with the second opening value to obtain a third opening value for controlling the water inlet and outlet isolation valve assembly and the water feeding pump (11).
2. The catalytic deoxygenation device of claim 1, wherein the catalytic deoxygenation device (10) further comprises a degassing tower (15) and a degassing fan (151), the degassing fan (151) is configured to blow gas into the degassing tower (15), the degassing tower (15) is connected to the catalytic deoxygenation resin bed (13), and the degassing tower (15) is configured to discharge hydrogen from the catalytic deoxygenation resin bed (13).
3. The catalytic deoxygenation device of claim 1, wherein the catalytic deoxygenation device (10) further comprises a resin trap (14) disposed between the catalytic deoxygenation resin bed (13) and the effluent isolation valve (192), the resin trap (14) for capturing resin.
4. A method for deoxidizing an emergency water supply tank of a nuclear power plant, which is characterized in that the method for deoxidizing an emergency water supply tank of a nuclear power plant uses the catalytic deoxidizing device as set forth in any one of claims 1-3; the method for deoxidizing the emergency water supply tank of the nuclear power plant comprises the following steps:
s1, measuring an oxygen content value of a water tank body (21);
s2, judging whether the oxygen content value exceeds a preset first oxygen content threshold value, if so, executing a step S3; if not, the current situation is maintained;
s3, outputting a first opening signal, and opening a water inlet and outlet isolation valve assembly of the catalytic deoxidizing device (10) and the water feeding pump (11) according to the first opening signal;
s4, judging whether the oxygen content value is lower than a preset second oxygen content threshold value, and if so, outputting a first closing signal; if not, the current situation is maintained; the water inlet and outlet isolation valve assembly and the water feed pump (11) are closed according to the first closing signal;
wherein the first opening value comprises the first opening signal and the first closing signal;
s5, measuring a liquid level value of the water tank body (21);
s6, judging whether the liquid level value is lower than a preset liquid level threshold value, if so, executing a step S7; if not, executing step S8;
s7, outputting a second closing signal, wherein the water inlet and outlet isolation valve assembly and the water feeding pump (11) are closed according to the second closing signal;
s8, keeping the current situation;
wherein the second opening value comprises the second closing signal;
s9, receiving the first opening value and the second opening value;
s10, judging whether the first opening value is a first opening signal and the second opening value is a second closing signal, if yes, executing a step S11;
s11, outputting a third opening value, wherein the third opening value comprises a third closing signal, and the water inlet and outlet isolation valve assembly and the water feeding pump (11) are closed according to the third closing signal.
5. A nuclear power plant emergency water supply system, characterized by comprising a water tank assembly (20) and a catalytic deoxygenation device (10) according to any one of claims 1-3;
wherein the water tank assembly (20) comprises a water tank body (21), and an oxygen analyzer (22) and a liquid level meter (23) which are respectively connected with the water tank body (21); the catalytic deoxygenation device (10) is connected with the water tank assembly (20).
6. The emergency water supply system of a nuclear power plant according to claim 5, wherein the water tank assembly (20) further comprises a nitrogen gas supply isolation valve (25) and a nitrogen gas pressure regulating valve (26) respectively connected with the water tank body (21), the nitrogen gas supply isolation valve (25) is used for introducing nitrogen gas, and the nitrogen gas pressure regulating valve (26) is used for regulating nitrogen gas pressure.
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| CN115475417A (en) * | 2022-08-23 | 2022-12-16 | 中核核电运行管理有限公司 | Method and device for reducing oxygen content of medium in floating roof tank of nuclear power plant |
| CN117168585B (en) * | 2023-11-03 | 2024-02-13 | 福建福清核电有限公司 | Online verification device and method for liquid level switch of auxiliary water supply tank |
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| CN208103985U (en) * | 2018-02-02 | 2018-11-16 | 深圳市中电加美电力技术有限公司 | A kind of catalytic deoxidation system of nuclear power station |
| CN112503509A (en) * | 2020-12-01 | 2021-03-16 | 中广核工程有限公司 | Nuclear power station drainage treatment system and method |
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| US4527626A (en) * | 1984-05-07 | 1985-07-09 | Conoco Inc. | Process and apparatus for removing dissolved oxygen |
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