Dehydrogenation system

Abstract

The utility model discloses a hydrogen removal system which comprises a first hydrogen removal module, a second hydrogen removal module and a third hydrogen removal module, the reactor coolant system comprises a reactor coolant system main loop and a voltage stabilizer; the first hydrogen removal module is connected with a main loop of the reactor coolant system, and the first hydrogen removal module is used for carrying out circulating degassing on a coolant in the main loop of the reactor coolant system before shutdown, so that the hydrogen concentration of the coolant is within a preset range; the second hydrogen removal module is connected with the voltage stabilizer; the second hydrogen removal module is used for reducing the hydrogen concentration of a gaseous space in the voltage stabilizer after shutdown; and the third hydrogen removal module is connected with the reactor coolant system main loop and is used for carrying out chemical hydrogen removal on the reactor coolant system main loop after the reactor is shut down and the temperature of the coolant is lower than the preset temperature until the hydrogen concentration is reduced to be lower than the preset concentration. Therefore, long hydrogen removal time of the reactor coolant system in the maintenance process is avoided, and the hydrogen removal efficiency is improved.

Description

Technical Field

[0001] The embodiment of the utility model relates to the technical field of hydrogen removal, in particular to a hydrogen removal system. Background Art

[0002] Before the major overhaul or minor overhaul (minor overhaul when the reactor cover is opened) of a nuclear power plant, in order to prevent the hydrogen in the primary loop from accumulating in the containment and causing an explosion under the "cold state" of the unit, it is necessary to perform hydrogen removal operations on the primary loop system and its related systems. However, the current third-generation nuclear power adopts a simplified system design and there is no volume control tank in the design. Therefore, before the reactor shutdown, nitrogen purging cannot be performed to replace hydrogen, and only hydrogen removal can be carried out by means of intermittent exhaust or by adding hydrogen peroxide and other means, resulting in a long time occupied by the hydrogen removal process and low hydrogen removal efficiency of the primary loop of the reactor coolant system. Content of the Utility Model

[0003] The utility model provides a hydrogen removal system, which avoids the long time occupied by the hydrogen removal of the primary loop of the reactor coolant system during the overhaul process and improves the hydrogen removal efficiency.

[0004] In a first aspect, the embodiment of the utility model provides a hydrogen removal system for the hydrogen removal application of a reactor coolant system. The hydrogen removal system includes: a first hydrogen removal module, a second hydrogen removal module, and a third hydrogen removal module; the reactor coolant system includes a primary loop of the reactor coolant system and a pressurizer.

[0005] The first hydrogen removal module is connected to the primary loop of the reactor coolant system. The first hydrogen removal module is used to perform circulating degassing on the coolant in the primary loop of the reactor coolant system before the reactor shutdown, so that the hydrogen concentration of the coolant is within a preset range.

[0006] The second hydrogen removal module is connected to the pressurizer; the second hydrogen removal module is used to reduce the hydrogen concentration in the gaseous space of the pressurizer after the reactor shutdown.

[0007] The third hydrogen removal module is connected to the primary loop of the reactor coolant system. The third hydrogen removal module is used to perform chemical hydrogen removal on the primary loop of the reactor coolant system after the reactor shutdown and when the temperature of the coolant is lower than a preset temperature until the hydrogen concentration is reduced below a preset concentration.

[0008] Optionally, the first hydrogen removal module includes a first switch unit, a heat exchange unit, a purification and separation unit, and a coolant return unit.

[0009] One end of the first switching unit is connected to the main loop of the reactor coolant system, the other end of the first switching unit is connected to the heat exchange unit, and the heat exchange unit is connected to the purification and separation unit; the first switching unit is used to control the flow rate of the coolant entering the heat exchange unit; the heat exchange unit is used to cool down the coolant; the purification and separation unit is used to filter and purify the flowing coolant and separate the coolant into gas and liquid, wherein the gas part is discharged after purification, and the liquid part circulates into the coolant return unit;

[0010] One end of the coolant return unit is connected to the purification and separation unit, the other end of the coolant return unit is connected to the heat exchange unit, and the heat exchange unit is connected to the main loop of the reactor coolant system; the coolant return unit is used to return the liquid part of the coolant to the main loop of the reactor coolant system through the heat exchange unit, and the heat exchange unit is also used to heat the coolant.

[0011] Optionally, the purification and separation unit includes a demineralization bed mixed bed, a degassing tower and a delay bed;

[0012] The demineralization bed mixed bed is connected to the heat exchange unit, the demineralization bed mixed bed is connected to the degassing tower, and the gas output end of the degassing tower is connected to the delay bed; the liquid output end of the degassing tower is connected to the coolant return unit; the demineralization bed mixed bed is used to purify the coolant; the degassing tower is used to separate the coolant into gas and liquid, wherein the gas part enters the delay bed and the liquid part enters the coolant return unit; the delay bed is used to purify the separated gas.

[0013] Optionally, the coolant return unit includes a discharge pump, a liquid storage tank and a makeup water pump. The degassing tower is connected to the discharge pump, the discharge pump is connected to the liquid storage tank, the liquid storage tank is connected to the makeup water pump, and the makeup water pump is connected to the main loop of the reactor coolant system through the heat exchange unit.

[0014] Optionally, the second hydrogen removal module includes a second switching unit, a third switching unit, a pressure sensor, a reactor coolant drain tank and an exhaust gas treatment unit;

[0015] The pressurizer is connected to the reactor coolant drain tank through the second switching unit, and the reactor coolant drain tank is connected to the exhaust gas treatment unit through the third switching unit; the second switching unit is used to control the intake air volume of the gas from the pressurizer entering the reactor coolant drain tank; the third switching unit is used to conduct the pipeline to discharge the gas to the exhaust gas treatment unit when the detection value of the pressure sensor exceeds the pressure threshold.

[0016] Optionally, the outlet end of the exhaust pipeline from the second switching unit to the reactor coolant drain tank is arranged at the bottom of the reactor coolant drain tank, and the outlet end of the exhaust pipeline is a porous port.

[0017] Optionally, the second hydrogen removal module further includes a drain pump, a fourth switching unit, and a wastewater treatment unit;

[0018] The drain pump is arranged in the reactor coolant drain tank, and the drain pump is connected to the wastewater treatment unit through the fourth switching unit; the drain pump is used for discharging the liquid to the wastewater treatment unit in cooperation with the conduction state of the fourth switching unit when the liquid level in the reactor coolant drain tank reaches a preset level.

[0019] Optionally, the second hydrogen removal module further includes a pressure reducing valve and a safety valve;

[0020] One end of the pressure reducing valve is connected to the reactor coolant drain tank, and the other end of the pressure reducing valve is connected to an inert gas output device; the pressure reducing valve is used for controlling the input gas volume of the inert gas; one end of the safety valve is connected to the reactor coolant drain tank, and the other end of the safety valve is connected to an external discharge port, and the safety valve is used for discharging the excessive gas in the reactor coolant drain tank to avoid overpressure in the reactor coolant drain tank.

[0021] Optionally, the pressure value at which the safety valve jumps to the conduction state is at least 160 kPa.

[0022] Optionally, the third hydrogen removal module includes: a chemical addition tank, a chemical and volume system make-up water pump, and a fifth switching unit;

[0023] The chemical addition tank is connected to the chemical and volume system make-up water pump, and the chemical and volume system make-up water pump is connected to the main loop of the reactor coolant system through the fifth switching unit.

[0024] The technical solution of the embodiment of the present invention, by connecting the main loop of the reactor coolant system to the first hydrogen removal module and the third hydrogen removal module respectively, and connecting the pressurizer to the second hydrogen removal module, so before the overhaul shutdown, the first hydrogen removal module can be used to circulate and degas the coolant in the main loop of the reactor coolant system, so that the hydrogen concentration of the coolant is within a preset range, meeting the hydrogen concentration requirement under the condition of non-stop operation. After the reactor is shut down, the second hydrogen removal module is used to reduce the hydrogen concentration in the gaseous space of the pressurizer, and after the temperature of the coolant is lower than the preset temperature, the third hydrogen removal module is used to chemically remove hydrogen from the main loop of the reactor coolant system until the hydrogen concentration is reduced below the preset concentration. Through a multi-stage hydrogen removal process, the time occupied by hydrogen removal is avoided, and the hydrogen removal efficiency is improved. Description of the Drawings

[0025] Figure 1 The structural schematic diagram of a hydrogen removal system is provided for an embodiment of the present utility model;

[0026] Figure 2 The structural schematic diagram of a first hydrogen removal module is provided for an embodiment of the present utility model;

[0027] Figure 3 The structural schematic diagram of a second hydrogen removal module is provided for an embodiment of the present utility model;

[0028] Figure 4 The structural schematic diagram of the output end of an exhaust pipeline is provided for an embodiment of the present utility model;

[0029] Figure 5 The structural schematic diagram of a third hydrogen removal module is provided for an embodiment of the present utility model;

[0030] Figure 6 The process schematic diagram of a hydrogen removal method is provided for an embodiment of the present utility model;

[0031] Figure 7 The process schematic diagram of another hydrogen removal method is provided for an embodiment of the present utility model. Specific embodiments

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0033] The coolant in the main loop of the nuclear reactor coolant system will decompose under the action of strong radiation to generate strongly oxidizing substances, and the strongly oxidizing substances cause corrosion of nuclear power equipment and reduce the reliability of the equipment. Therefore, during the operation of the main loop of the reactor coolant system, hydrogen is usually added to the coolant to inhibit the radiation decomposition of the coolant, and hydrogen accumulates in the coolant, the gas phase of the pressurizer and their connecting pipelines. Before the unit is shut down for maintenance, in order to avoid hydrogen-oxygen mixed explosion, hydrogen removal operation is required to ensure that the hydrogen concentration in the coolant of the primary loop after the gas extinguishing chamber of the pressurizer is reduced to less than 5 cc / kg. However, the current third-generation nuclear power adopts a simplified system design and there is no volume control tank in the design. Therefore, nitrogen purge cannot be performed to replace hydrogen before shutdown, and only hydrogen removal can be carried out by means of intermittent exhaust or by adding hydrogen peroxide and other means, resulting in a long time occupied by the hydrogen removal process and low hydrogen removal efficiency of the main loop of the reactor coolant system.

[0034] In view of this, Figure 1 The present embodiment of the utility model provides a schematic structural diagram of a hydrogen removal system, see Figure 1 , which is used for the hydrogen removal application of the reactor coolant system. The hydrogen removal system includes: a first hydrogen removal module 110, a second hydrogen removal module 120, and a third hydrogen removal module 130; the reactor coolant system includes a main loop 140 of the reactor coolant system and a pressurizer 150;

[0035] The first hydrogen removal module 110 is connected to the main loop 140 of the reactor coolant system. The first hydrogen removal module 110 is used to circulate and degas the coolant in the main loop 140 of the reactor coolant system before shutdown, so that the hydrogen concentration of the coolant is within a preset range;

[0036] The second hydrogen removal module 120 is connected to the pressurizer 150; the second hydrogen removal module 120 is used to reduce the hydrogen concentration in the gaseous space of the pressurizer 150 after shutdown;

[0037] The third hydrogen removal module 130 is connected to the main loop 140 of the reactor coolant system. The third hydrogen removal module 130 is used to perform chemical hydrogen removal on the main loop 140 of the reactor coolant system after shutdown and when the temperature of the coolant is lower than a preset temperature until the hydrogen concentration is reduced below the preset concentration.

[0038] Specifically, in the coolant system of nuclear power technology, also known as the primary loop system, the reactor coolant system mainly consists of a reactor coolant pump, a reactor, a pressurizer 150, a steam generator, and the corresponding reactor coolant system loop pipes. The main function of the reactor coolant system is to carry out the heat generated in the reactor core and transfer it to the secondary loop system through the steam generator, and the generated steam drives the steam turbine generator set to generate electricity.

[0039] The pressurizer 150 is mainly used to control the pressure change of the main loop 140 of the reactor coolant system in the nuclear reactor coolant system. It monitors and adjusts the pressure in the system to ensure that the main loop 140 of the reactor coolant system can operate stably under various working conditions. The interior of the pressurizer 150 is divided into an upper steam space and a lower water space, which is in a two-phase equilibrium state. The pressure in its steam space is used to represent the operating pressure of the main loop 140 of the reactor coolant system.

[0040] The first hydrogen removal module 110 is connected to the pipeline corresponding to the main loop 140 of the reactor coolant system. The coolant in the main loop of the reactor coolant system can be deaerated through the first hydrogen removal module 110, and then the first hydrogen removal module 110 returns the coolant to the main loop 140 of the reactor coolant system again. Therefore, cyclic degassing can be carried out in advance without shutting down the reactor. For example, cyclic degassing can be carried out within one to four weeks before the major overhaul, so that the concentration of dissolved hydrogen in the coolant of the main loop 140 of the reactor coolant system is controlled within the preset range required by the technical requirements. In some embodiments, when the concentration of dissolved hydrogen in the coolant needs to be greater than or equal to 5 cc / kg according to the technical requirements without shutting down the reactor, the preset range can be set to be greater than or equal to 5 cc / kg.

[0041] When the reactor is shut down to zero power and in the stage from the gas removal cavity to the water entity of the pressurizer 150, there is a large amount of hydrogen in the gas phase space of the pressurizer 150. To ensure that the hydrogen concentration in the coolant is less than the required concentration when degassing the pressurizer 150, it is necessary to discharge the hydrogen in the pressurizer 150. The gas discharged from the pressurizer 150 passes through the second hydrogen removal module 120, and the second hydrogen removal module 120 removes hydrogen and harmlessly processes the discharged gas, thereby reducing the hydrogen concentration in the gas phase space of the pressurizer 150.

[0042] The third hydrogen removal module 130 is connected to the pipeline corresponding to the main loop 140 of the reactor coolant system. When the reactor is shut down and the temperature of the coolant system in the main loop 140 of the reactor coolant system meets the requirements, the third hydrogen removal module 130 is used to add hydrogen peroxide to the main loop of the reactor coolant system for chemical hydrogen removal. Since the coolant inventory is large and the hydrogen concentration is high, in some embodiments, the third hydrogen removal module 130 can be used to add hydrogen peroxide multiple times to reduce the hydrogen concentration in the main loop of the reactor coolant system below the preset concentration.

[0043] The technical solution of the embodiment of the present utility model is that by connecting the main loop of the reactor coolant system to the first hydrogen removal module and the third hydrogen removal module respectively, and connecting the pressurizer to the second hydrogen removal module, before the major overhaul shutdown, the first hydrogen removal module can be used to carry out cyclic degassing on the coolant in the main loop of the reactor coolant system, so that the hydrogen concentration of the coolant is within the preset range, meeting the hydrogen concentration requirements without shutting down the reactor. After shutdown, the second hydrogen removal module is used to reduce the hydrogen concentration in the gas phase space of the pressurizer, and after the temperature of the coolant is lower than the preset temperature, the third hydrogen removal module is used to carry out chemical hydrogen removal on the main loop of the reactor coolant system until the hydrogen concentration is reduced below the preset concentration. Through the multi-stage hydrogen removal process, the time occupied by hydrogen removal is avoided and the hydrogen removal efficiency is improved.

[0044] Figure 2 The structure diagram of a hydrogen removal system is provided for the embodiment of the present utility model. Refer to Figure 2, the first dehydrogenation module 110 includes a first switching unit 141, a heat exchange unit 142, a purification and separation unit 143, and a coolant return unit 144;

[0045] One end of the first switching unit 141 is connected to the main loop 140 of the reactor coolant system, the other end of the first switching unit 141 is connected to the heat exchange unit 142, and the heat exchange unit 142 is connected to the purification and separation unit 143; the first switching unit 141 is used to control the flow rate of the coolant entering the heat exchange unit 142; the heat exchange unit 142 is used to cool down the coolant; the purification and separation unit 143 is used to filter and purify the flowing coolant and separate the coolant into gas and liquid phases, wherein the gas part is discharged after purification, and the liquid part circulates into the coolant return unit 144;

[0046] One end of the coolant return unit 144 is connected to the purification and separation unit 143, the other end of the coolant return unit 144 is connected to the heat exchange unit 142, and the heat exchange unit 142 is connected to the main loop 140 of the reactor coolant system; the coolant return unit 144 is used to return the liquid part of the coolant to the main loop 140 of the reactor coolant system through the heat exchange unit 142, and the heat exchange unit 142 is also used to heat the coolant.

[0047] Specifically, the first switch unit 141 is used to control the pipeline between the main loop 140 of the reactor coolant system and the heat exchange unit 142 to be in a conducting or cut-off state. Exemplarily, the first switch unit 141 may adopt an isolation valve. In order to improve the stability of gas isolation, multiple isolation valves may be arranged in series. In the embodiment of the present invention, three isolation valves are taken as an example. When the first switch unit 141 is in a conducting state, that is to say, the corresponding isolation valves are all in a conducting state, the coolant in the main loop 140 of the reactor coolant system enters the heat exchange unit 142 through the first switch unit 141, and the coolant is cooled down by the heat exchange unit 142. The cooled coolant enters the purification and separation unit 143. The purification and separation unit 143 filters and separates the gas and liquid of the coolant. The purified gas part is discharged, and the liquid part circulates into the coolant return unit 144. The coolant return unit 144 then transports the coolant to the heat exchange unit 142, and after being heated by the heat exchange unit 142, it flows back to the main loop 140 of the reactor coolant system again, thereby realizing a cycle of degassing process. By circulating degassing, the concentration of dissolved hydrogen in the coolant of the main loop 140 of the reactor coolant system can be reduced. Among them, the heat exchange unit 142 may include a regenerative heat exchanger ME01 and a letdown heat exchanger ME02. The first input end of the regenerative heat exchanger ME01 is connected to the first switch unit 141, the first output end of the regenerative heat exchanger ME01 is connected to the letdown heat exchanger ME02, and the letdown heat exchanger ME02 is connected to the purification and separation unit 143. The regenerative heat exchanger ME01 is a device that uses a heat storage body for heat exchange. It can effectively transfer heat between different fluids, thereby realizing the recovery and utilization of energy. The letdown heat exchanger ME02 transfers the heat of the high-pressure fluid to the fluid with a lower pressure through the heat exchange process. The coolant in the main loop 140 of the reactor coolant system enters the regenerative heat exchanger ME01, and a part of the heat can be stored in the heat storage body. The letdown heat exchanger ME02 is used to further cool down the coolant. In the subsequent process, the coolant return unit 144 can transport the coolant to the regenerative heat exchanger ME01, and after the regenerative heat exchanger ME01 heats up the coolant, it flows back to the main loop 140 of the reactor coolant system, reducing the influence brought by the change of coolant temperature.

[0048] Continue to refer to Figure 2 , optionally, the purification and separation unit 143 includes a demineralizer mixed bed MV02, a degassing tower MV03, and a delay bed MV04;

[0049] The demineralization bed mixed bed MV02 is connected to the heat exchange unit 142, the demineralization bed mixed bed MV02 is connected to the degassing tower MV03, and the gas output end of the degassing tower MV03 is connected to the delay bed MV04; the liquid output end of the degassing tower MV03 is connected to the coolant return unit 144; the demineralization bed mixed bed MV02 is used to purify the coolant; the degassing tower MV03 is used to separate the gas and liquid of the coolant, wherein the gas part enters the delay bed MV04 and the liquid part enters the coolant return unit 144; the delay bed MV04 is used to purify the separated gas.

[0050] Specifically, the demineralization bed mixed bed MV02 is used for industrial water treatment. By mixing and filling anion and cation exchange resins in a certain proportion in the same exchanger and performing anion and cation exchange in a uniformly mixed state, the salts in the water are removed. The demineralization bed mixed bed MV02 is used to purify and desalt the coolant flowing out of the heat exchange unit 142. In some embodiments, in order to avoid radiation hazards, a containment is provided around the primary loop 140 of the reactor coolant system as physical protection. The demineralization bed mixed bed MV02 is arranged on one side inside the containment, and the degassing tower MV03 is arranged on one side outside the containment. Therefore, a set of isolation valves V44 inside the containment, a penetration C01 through the containment, and an isolation valve V5 outside the containment need to be provided between the demineralization bed mixed bed MV02 and the degassing tower MV03. The coolant purified by the demineralization bed mixed bed MV02 enters the degassing tower MV03 through the isolation valve V4 inside the containment, the penetration C01 through the containment, and the isolation valve V5 outside the containment. Through gas-liquid separation, the gas part enters the delay bed MV04. The delay bed MV04 refers to a device with a specific delay function, which delays the gas discharge by means of gas adsorption and other methods, so that the discharged gas stays in the delay bed MV04 for a period of time, enabling the radioactive elements in the gas to decay, further purifying the discharged gas, and reducing the impact of radiation pollution.

[0051] Optionally, the coolant return unit 144 includes a discharge pump MP01, a liquid storage tank MT01, and a makeup water pump MP. After the degassing tower MV03 separates the gas and liquid of the coolant, the liquid part flows into the liquid storage tank MT01 through the discharge pump MP01. When the liquid storage tank MT01 stores a certain volume of liquid, the makeup water pump MP returns the liquid to the primary loop 140 of the reactor coolant system through the heat exchange unit 142. In some embodiments, the heat exchange unit 142 is arranged on one side inside the containment, and the makeup water pump MP is arranged on one side outside the containment. Therefore, an isolation valve V4 inside the containment, a penetration C01 through the containment, and an isolation valve V5 outside the containment also need to be provided between the heat exchange unit 142 and the makeup water pump MP.

[0052] Figure 3 The structural schematic diagram of a second hydrogen removal module is provided for the embodiments of the present invention. Refer to Figure 3, the second dehydrogenation module 120 includes a second switch unit 121, a third switch unit 122, a pressure sensor PT01, a reactor coolant drain tank MT02, and an exhaust gas treatment unit 123;

[0053] The pressurizer 150 is connected to the reactor coolant drain tank MT02 through the second switch unit 121, and the reactor coolant drain tank MT02 is connected to the exhaust gas treatment unit 123 through the third switch unit 122; the second switch unit 121 is used to control the intake air volume of the gas in the pressurizer 150 entering the reactor coolant drain tank MT02; the third switch unit 122 is used to conduct the pipeline to discharge the gas to the exhaust gas treatment unit 123 when the detected value of the pressure sensor PT01 exceeds the pressure threshold.

[0054] Specifically, the second switch unit 121 is used to control the pipeline between the pressurizer 150 and the reactor coolant drain tank MT02 to be in a conducting or cut-off state. When the reactor is shut down to zero power and in the stage from the gas cavity to the water entity in the pressurizer 150, the second switch unit 121 is in a conducting state, and the gas in the pressurizer 150 is discharged to the reactor coolant drain tank MT02. Among them, since the pressure of the pressurizer 150 is greater than the pressure of the reactor coolant drain tank MT02, in order to avoid a large amount of gas surging in when the second switch unit 121 is opened, the second switch unit 121 adopts an intermittent opening method, so that the gas in the pressurizer 150 enters the reactor coolant drain tank MT02. The reactor coolant drain tank MT02 is provided with a pressure sensor PT01. When the detected value of the pressure sensor PT01 exceeds the pressure threshold, the third switch unit 122 is opened, and the gas in the reactor coolant drain tank MT02 enters the exhaust gas treatment unit 123. Since the gas in the pressurizer 150 includes radioactive gas, the exhaust gas treatment unit 123 is required to treat the radioactive exhaust gas to meet the safety requirements. In some embodiments, a set of delay beds MV04 can be further provided between the third switch unit 122 and the exhaust gas treatment unit 123 to further improve the purification of the gas. The second switch unit 121 can adopt a remote control valve to improve the operation safety. In some embodiments, the reactor coolant drain tank MT02 is arranged on one side inside the containment, and the exhaust gas treatment unit 123 is arranged on one side outside the containment. Therefore, the third switch unit 122 can also adopt a set of isolation valves V4 inside the containment and isolation valves V5 outside the containment, and a containment penetration C01 is arranged between the isolation valves V4 inside the containment and the isolation valves V5 outside the containment.

[0055] In some embodiments, optionally, the second dehydrogenation module 120 further includes a drain pump MP03, a fourth switch unit 124, and a wastewater treatment unit 125; the drain pump MP03 is disposed in the reactor coolant drain tank MT02, and the drain pump MP03 is connected to the wastewater treatment unit 125 through the fourth switch unit 124; the drain pump MP03 is configured to discharge the liquid to the wastewater treatment unit 125 in cooperation with the conduction state of the fourth switch unit 124 when the liquid in the reactor coolant drain tank MT02 reaches a preset liquid level. Specifically, when the liquid in the reactor coolant drain tank MT02 reaches a certain liquid level, the drain pump MP03 is started to discharge the liquid to the wastewater treatment unit 125, and the radioactive liquid waste is treated by the wastewater treatment unit 125 to meet the safety requirements.

[0056] In some embodiments, optionally, the second dehydrogenation module 120 further includes a pressure reducing valve V12 and a safety valve V13; one end of the pressure reducing valve V12 is connected to the reactor coolant drain tank MT02, and the other end of the pressure reducing valve V12 is connected to an inert gas output device; the pressure reducing valve V12 is configured to control the input gas volume of the inert gas; one end of the safety valve V13 is connected to the reactor coolant drain tank MT02, and the other end of the safety valve V13 is connected to an external discharge port, and the safety valve V13 is configured to discharge the excessive gas in the reactor coolant drain tank MT02 to prevent the pressure in the reactor coolant drain tank MT02 from overpressuring.

[0057] Specifically, since there are radioactive gases and hydrogen in the pressurizer 150, the gases received by the reactor coolant drain tank MT02 also contain radioactive gases and hydrogen. To ensure safety, the reactor coolant drain tank MT02 needs to be covered with inert gas. Exemplarily, the inert gas here can be nitrogen. The process of nitrogen coverage can be that the external inert gas output device inputs inert gas into the reactor coolant drain tank MT02 through the pressure reducing valve V12, thereby performing nitrogen coverage to maintain a slightly positive pressure in the reactor coolant drain tank MT02. In addition, since the air pressure in the pressurizer 150 is relatively high, to prevent the reactor coolant drain tank MT02 from overpressuring, the reactor coolant drain tank MT02 is also provided with a safety valve V13 for protection. When the reactor coolant drain tank MT02 is overpressured, the safety valve V13 jumps to conduct and exhausts to relieve pressure, improving safety. Further, to ensure that the reactor coolant drain tank MT02 can receive more gases from the pressurizer 150, the pressure-bearing value of the reactor coolant drain tank MT02 should be increased as much as possible in the design. Therefore, the jump pressure value of the safety valve V13 is at least 160 kPa.

[0058] Optionally, Figure 4 The present invention provides a schematic structural diagram of the output end of an exhaust pipeline. Refer to Figure 4, the exhaust pipeline output end of the second switch unit 121 to the reactor coolant drain tank MT02 is arranged at the bottom of the reactor coolant drain tank MT02, and the exhaust pipeline output end is a porous port. That is to say, the exhaust pipeline output end is distributed at the bottom of the reactor coolant drain tank MT02. When there is liquid in the reactor coolant drain tank MT02, the liquid will submerge the exhaust pipeline output end, and the exhaust pipeline output end is a porous port. The discharged gas can be sprayed into the liquid in the reactor coolant drain tank MT02 in a porous manner, thus avoiding the concentrated release of gas at a certain point in the pressurizer 150, resulting in a concentrated temperature causing the liquid in the reactor coolant drain tank MT02 to vaporize.

[0059] Figure 5 The structure diagram of a third hydrogen removal module 130 is provided for an embodiment of the present invention. Refer to Figure 5 , the third hydrogen removal module 130 includes: a chemical addition tank MT03, a chemical and volume system make-up water pump MP02, and a fifth switch unit 131; the chemical addition tank MT03 is connected to the chemical and volume system make-up water pump MP02, and the chemical and volume system make-up water pump MP02 is connected to the main loop 140 of the reactor coolant system through the fifth switch unit 131.

[0060] Specifically, in the later stage of reactor shutdown, when the coolant temperature drops to the preset requirement, for example, when the coolant temperature drops to about 177 °C, it is considered to meet the requirement, and then chemical deoxidation can be carried out by adding hydrogen peroxide to the coolant system of the main loop 140 of the reactor coolant system. A certain volume of hydrogen peroxide solution is added to the chemical addition tank MT03, and then the chemical and volume system make-up water pump MP02 is started. The hydrogen peroxide solution enters the coolant system of the main loop 140 of the reactor coolant system through the fifth switch unit 131. After circulating through the coolant system of the main loop 140 of the reactor coolant system, the hydrogen concentration is reduced to below the preset concentration. Since the coolant inventory is large and the hydrogen concentration is high, in some embodiments, hydrogen peroxide can be added multiple times to the chemical addition tank MT03 to reduce the hydrogen concentration in the main loop 140 of the reactor coolant system. In some embodiments, the chemical and volume system make-up water pump MP02 is arranged on one side outside the containment, so the fifth switch unit 131 can also adopt a set of in-containment isolation valves V4 and out-of-containment isolation valves V5, and a containment penetration C01 is arranged between the in-containment isolation valve V4 and the out-of-containment isolation valve V5. In some embodiments, the chemical and volume system make-up water pump MP02 used at the rear end of the chemical addition tank MT03 can share the make-up water pump MP in the coolant return unit 144. Therefore, only two branches are separated at the input end of the chemical and volume system make-up water pump MP02, one branch is connected to the chemical addition tank MT03, and the other branch is connected to the liquid storage tank MT01.

[0061] Figure 6The present embodiment of the utility model provides a flow schematic diagram of a hydrogen removal method. This embodiment is applicable to the hydrogen removal of the reactor coolant system. This method can be executed by a hydrogen removal device, and the device can be implemented in a hardware and / or software manner. The method specifically includes the following steps:

[0062] S110. Before reactor shutdown, the first hydrogen removal module performs cyclic degassing on the coolant in the main loop of the reactor coolant system to make the hydrogen concentration in the coolant within a preset range;

[0063] Specifically, in the reactor coolant system of nuclear power technology, also known as the primary loop system, the reactor coolant system mainly consists of a reactor coolant pump, a reactor, a pressurizer 150, a steam generator, and the corresponding main return pipes of the reactor coolant system. The main function of the reactor coolant system is to carry out the heat generated in the reactor core and transfer it to the secondary loop system through the steam generator, and the generated steam drives the steam turbine generator set to generate electricity. The pressurizer 150 is mainly used to control the pressure change of the main loop 140 of the reactor coolant system in a nuclear reactor. It monitors and adjusts the pressure in the system to ensure that the main loop 140 of the reactor coolant system can operate stably under various working conditions. The interior of the pressurizer 150 is divided into an upper steam space and a lower water space, and is in a two-phase equilibrium state. The pressure in its steam space is used to represent the operating pressure of the main loop 140 of the reactor coolant system.

[0064] The first hydrogen removal module 110 is connected to the corresponding pipeline of the main loop 140 of the reactor coolant system. The coolant in the main loop 140 of the reactor coolant system can be dehydrogenerated through the first hydrogen removal module 110, and then the first hydrogen removal module 110 returns the coolant to the main loop 140 of the reactor coolant system again. Therefore, cyclic degassing can be carried out in advance without reactor shutdown. For example, cyclic degassing is carried out within one to four weeks before the major overhaul, so that the concentration of dissolved hydrogen in the coolant of the main loop 140 of the reactor coolant system is controlled within the preset range required by the technology. In some embodiments, when the concentration of dissolved hydrogen in the coolant needs to be greater than or equal to 5 cc / kg according to the technical requirements without reactor shutdown, the preset range can be set to be greater than or equal to 5 cc / kg.

[0065] S120. After reactor shutdown, the second hydrogen removal module reduces the hydrogen concentration in the gaseous space of the pressurizer;

[0066] Specifically, when the reactor is shut down to zero power and during the process of the pressurizer 150 transitioning from the gas-filled cavity to the water entity, there is a large amount of hydrogen in the gas phase space of the pressurizer 150. To ensure that the hydrogen concentration in the coolant is less than the required concentration when the pressurizer 150 is in the gas-removing cavity, it is necessary to discharge the hydrogen in the pressurizer 150. The gas discharged from the pressurizer 150 passes through the second hydrogen removal module 120, and the second hydrogen removal module 120 removes hydrogen and performs harmless treatment on the discharged gas, thereby reducing the hydrogen concentration in the gas phase space of the pressurizer 150.

[0067] S130: After the reactor is shut down and the temperature of the coolant is lower than the preset temperature, the third hydrogen removal module performs chemical hydrogen removal on the main loop of the reactor coolant system until the hydrogen concentration is reduced below the preset concentration.

[0068] Specifically, the third hydrogen removal module 130 is connected to the corresponding pipeline of the main loop 140 of the reactor coolant system. When the reactor is shut down and the temperature of the coolant system of the main loop 140 of the reactor coolant system meets the requirements, hydrogen peroxide is added to the coolant system of the main loop 140 of the reactor coolant system by using the third hydrogen removal module 130 for chemical hydrogen removal. Since the coolant inventory is large and the hydrogen concentration is high, in some embodiments, the third hydrogen removal module 130 can be used to add hydrogen peroxide multiple times to reduce the hydrogen concentration in the main loop 140 of the reactor coolant system below the preset concentration.

[0069] Figure 7 This is a schematic flow chart of another hydrogen removal method provided by the embodiments of the present invention. Referring to FIGS. 2 Figure 3 and Figure 5 , see Figure 7 ,

[0070] S210: The first stage: Carry out the degassing cycle operation within one to four weeks before the major overhaul for physical hydrogen removal to keep the dissolved hydrogen concentration of the coolant in the main loop of the reactor coolant system at a low level.

[0071] Specifically, the coolant in the main loop 140 of the reactor coolant system flows through the first isolation valve V1, the second isolation valve V2, and the third isolation valve V3, then passes through the regenerative heat exchanger ME01 and the letdown heat exchanger ME02. After being cooled, the coolant flows through the demineralizer mixed bed MV02 for purification. The purified coolant flows through a group of in-containment isolation valves V4, the containment penetration C01, and the out-of-containment isolation valve V5, and then enters the degassing tower MV03 for gas-liquid separation. After separation, the gas part enters the delay bed MV04 for purification and is then discharged to the atmosphere; the liquid part is transported to the liquid storage tank MT01 by the discharge pump MP01. The coolant in the liquid storage tank MT01 finally enters the regenerative heat exchanger ME01 through the makeup water pump MP, a group of in-containment isolation valves V4, the containment penetration C01, and the out-of-containment isolation valve V5. After being heated by the regenerative heat exchanger ME01, the coolant returns to the main loop 140 of the reactor coolant system. The hydrogen in the coolant of the main loop 140 of the reactor coolant system is released in the degassing tower MV03 and discharged to the atmosphere, ultimately reducing the hydrogen concentration in the main loop 140 of the reactor coolant system.

[0072] S220, Second stage: In the initial stage of reactor shutdown, reduce the hydrogen in the gaseous space of the pressurizer;

[0073] Specifically, intermittently open the second switch unit 121 to allow the gas in the pressurizer 150 to enter the reactor coolant drain tank MT02. When the gas pressure in the reactor coolant drain tank MT02 reaches the set value, open the third switch unit 122 to discharge the gas from the reactor coolant drain tank MT02 to the waste gas treatment unit 123, and the waste gas treatment unit 123 treats and discharges the waste gas. When the liquid in the reactor coolant drain tank MT02 reaches a certain level, start the drain pump MP03 to drain the wastewater to the wastewater treatment unit 125, and the wastewater treatment unit 125 treats and discharges the wastewater.

[0074] S230, Third stage: In the later stage of reactor shutdown, add hydrogen peroxide to the reactor coolant system to reduce the hydrogen concentration in the main loop of the reactor coolant system until the requirement for opening the reactor pressure vessel cover is met.

[0075] Specifically, when the coolant temperature of the main loop 140 of the reactor coolant system has been reduced to about 177 °C, a certain volume of hydrogen peroxide solution is added to the chemical addition tank MT03. Subsequently, the chemical and volume system makeup water pump MP02 is started. The hydrogen peroxide solution enters the coolant system of the main loop 140 of the reactor coolant system after passing through the containment isolation valve V5, the containment penetration C01, and the in-containment isolation valve V4. Finally, after circulating through the coolant system of the main loop 140 of the reactor coolant system, the hydrogen concentration is reduced to below 5 cc / kg. Due to the large coolant inventory and high hydrogen concentration, in some embodiments, hydrogen peroxide can be added multiple times to the chemical addition tank MT03 to reduce the hydrogen concentration in the main loop of the reactor coolant system to below the preset concentration.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen removal system, characterized in that, For the hydrogen removal application of the reactor coolant system, the hydrogen removal system includes: a first hydrogen removal module, a second hydrogen removal module, and a third hydrogen removal module; the reactor coolant system includes the main loop of the reactor coolant system and a pressurizer; The first hydrogen removal module is connected to the main loop of the reactor coolant system, and the first hydrogen removal module is used to circulate and degas the coolant in the main loop of the reactor coolant system before reactor shutdown, so that the hydrogen concentration of the coolant is within a preset range; The second hydrogen removal module is connected to the pressurizer; the second hydrogen removal module is used to reduce the hydrogen concentration in the gaseous space of the pressurizer after reactor shutdown; The third hydrogen removal module is connected to the main loop of the reactor coolant system, and the third hydrogen removal module is used to perform chemical hydrogen removal on the main loop of the reactor coolant system after reactor shutdown and when the temperature of the coolant is lower than a preset temperature until the hydrogen concentration is reduced below the preset concentration.

2. The hydrogen removal system according to claim 1, wherein: The first hydrogen removal module includes a first switch unit, a heat exchange unit, a purification and separation unit, and a coolant return unit; One end of the first switch unit is connected to the main loop of the reactor coolant system, the other end of the first switch unit is connected to the heat exchange unit, and the heat exchange unit is connected to the purification and separation unit; the first switch unit is used to control the flow rate of the coolant entering the heat exchange unit; The heat exchange unit is used to cool down the coolant; the purification and separation unit is used to filter and purify the flowing coolant and separate the coolant into gas and liquid, wherein the gas part is discharged after purification, and the liquid part circulates into the coolant return unit; One end of the coolant return unit is connected to the purification and separation unit, the other end of the coolant return unit is connected to the heat exchange unit, and the heat exchange unit is connected to the main loop of the reactor coolant system; the coolant return unit is used to return the liquid part of the coolant to the main loop of the reactor coolant system through the heat exchange unit, and the heat exchange unit is also used to heat the coolant.

3. The hydrogen removal system according to claim 2, characterized in that: The purification and separation unit includes a demineralized bed mixed bed, a degassing tower, and a delay bed; The demineralized bed mixed bed is connected to the heat exchange unit, the demineralized bed mixed bed is connected to the degassing tower, and the gas output end of the degassing tower is connected to the delay bed; the liquid output end of the degassing tower is connected to the coolant return unit; the demineralized bed mixed bed is used to purify the coolant; the degassing tower is used to separate the coolant into gas and liquid, wherein the gas part enters the delay bed, and the liquid part enters the coolant return unit; the delay bed is used to purify the separated gas.

4. The hydrogen removal system according to claim 3, wherein: The coolant return unit includes a discharge pump, a liquid storage tank, and a makeup water pump. The degassing tower is connected to the discharge pump, the discharge pump is connected to the liquid storage tank, the liquid storage tank is connected to the makeup water pump, and the makeup water pump is connected to the main loop of the reactor coolant system through the heat exchange unit.

5. The dehydrogenation system according to any one of claims 2-4, characterized in that: The second hydrogen removal module includes a second switch unit, a third switch unit, a pressure sensor, a reactor coolant drain tank, and an exhaust gas treatment unit; The pressure stabilizer is connected to the reactor coolant drain tank through the second switch unit, and the reactor coolant drain tank is connected to the waste gas treatment unit through the third switch unit; the second switch unit is used to control the intake air volume of the gas from the pressure stabilizer entering the reactor coolant drain tank; the third switch unit is used to conduct the pipeline to discharge the gas to the waste gas treatment unit when the detected value of the pressure sensor exceeds the pressure threshold.

6. The hydrogen removal system according to claim 5, wherein: The output end of the exhaust pipeline from the second switch unit to the reactor coolant drain tank is arranged at the bottom of the reactor coolant drain tank, and the output end of the exhaust pipeline is a multi-hole port.

7. The hydrogen removal system according to claim 6, characterized in that: The second hydrogen removal module further includes a drain pump, a fourth switch unit, and a wastewater treatment unit; The drain pump is arranged in the reactor coolant drain tank, and the drain pump is connected to the wastewater treatment unit through the fourth switch unit; the drain pump is used to discharge the liquid to the wastewater treatment unit when the liquid level in the reactor coolant drain tank reaches the preset liquid level, in cooperation with the conducting state of the fourth switch unit.

8. The hydrogen removal system according to claim 5, characterized in that: The second hydrogen removal module further includes a pressure reducing valve and a safety valve; One end of the pressure reducing valve is connected to the reactor coolant drain tank, and the other end of the pressure reducing valve is connected to the inert gas output device; the pressure reducing valve is used to control the input gas volume of the inert gas; one end of the safety valve is connected to the reactor coolant drain tank, and the other end of the safety valve is connected to the external discharge port. The safety valve is used to discharge the excessive gas in the reactor coolant drain tank to avoid overpressure in the reactor coolant drain tank.

9. The hydrogen removal system according to claim 8, characterized in that: The pressure value at which the safety valve jumps to the conducting state is at least 160 kPa.

10. The hydrogen removal system according to claim 1, characterized in that: The third hydrogen removal module includes: a chemical addition tank, a chemical and volume system make-up water pump, and a fifth switch unit; The chemical addition tank is connected to the chemical and volume system make-up water pump, and the chemical and volume system make-up water pump is connected to the main loop of the reactor coolant system through the fifth switch unit.

Images