Online continuous monitoring device for liquid effluent 14C of nuclear power plant

Abstract

The invention discloses a nuclear power plant liquid effluent 14C on-line continuous monitoring device, which comprises an acquisition unit used for acquiring a nuclear power plant liquid effluent to form a liquid to be detected; the high-temperature oxidation unit is used for carrying out high-temperature combustion treatment on the to-be-detected liquid to form a gaseous substance; the acidification and separation unit is used for cooling, condensing and acidifying the gaseous substance and separating the gaseous substance to form liquid and gas; the adsorption unit is used for absorbing carbon dioxide in the gas; and the measuring unit is used for measuring the activity concentration of 14C in the CO2 desorbed by the adsorption unit. According to the invention, the activity concentration of the liquid effluent 14C of the nuclear power plant is monitored; automatic monitoring can be achieved, manual operation is reduced, sample preparation time is shortened, and efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of environmental detection technology, and in particular to a liquid effluent from a nuclear power plant. 14 C online continuous monitoring device. Background Art

[0002] 14 C is a pure low-energy beta radionuclide with a half-life of 5700a. In pressurized water reactors of nuclear power plants, 14 C is mainly transmitted through the coolant, fuel pellets, and cladding materials 17 O and 14 Nitrogen is produced by neutron irradiation. 14 C, mainly through two activation reactions in the reactor coolant 14 N(n, p) and 17 O(n, α) is generated in the coolant of a pressurized water reactor due to the ubiquitous presence of N and O elements in the coolant. 14 C is inevitable. 14 C enters the waste liquid treatment system through coolant leakage and enters solid waste and liquid effluent. After the effluent is discharged into the environment, 14 C may cause certain radiation impacts on the public through various channels.

[0003] The existing "Liquid Effluents from Nuclear Power Plants" 14 C Analytical Method - Wet Oxidation Method (HJ 1056-2019) standard, the wet oxidation method is used to analyze the liquid effluent. 14 C analysis is performed using a total organic carbon analyzer. This method takes a long time to prepare samples, is complex and inefficient, requires numerous chemical reagents, and requires a single instrument. The standard also recommends using a total organic carbon analyzer for sample preparation, but this requires custom setup and lacks standardized requirements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an integrated arrangement of liquid effluent from a nuclear power plant. 14 C online continuous monitoring device.

[0005] The technical solution adopted by the present invention to solve the technical problem is to provide a liquid effluent from a nuclear power plant 14 C Online continuous monitoring device, including:

[0006] A collection unit, used to collect liquid effluent from the nuclear power plant to form a liquid to be tested;

[0007] A high-temperature oxidation unit, used for subjecting the liquid to be tested to high-temperature combustion treatment to form a gaseous substance;

[0008] an acidification and separation unit, for cooling, condensing and acidifying the gaseous substance, and separating the gaseous substance into liquid and gas;

[0009] an adsorption unit, comprising at least one molecular sieve adsorption column, for absorbing carbon dioxide in the gas; and

[0010] Measuring unit for measuring the CO2 desorbed from the molecular sieve adsorption column 14 Activity concentration of C;

[0011] The high-temperature oxidation unit is connected between the collection unit and the acidification and separation unit; the gas outlet of the acidification and separation unit is connected to the adsorption unit to send the separated gas into the adsorption unit; the adsorption unit is connected to the measuring unit to send the desorbed CO2 into the measuring unit for measurement.

[0012] In one embodiment, the collection unit includes a booster pump, a filter assembly, and a first peristaltic pump connected in series through an inlet pipe;

[0013] The first peristaltic pump is connected to the feed port of the high-temperature oxidation unit to quantitatively transport the liquid to be tested to the high-temperature oxidation unit.

[0014] In one embodiment, the high-temperature oxidation unit includes a combustion furnace; the feed port of the combustion furnace is connected to the collection unit, the discharge port of the combustion furnace is connected to the acidification and separation unit, and the air inlet of the combustion furnace is used to access oxygen.

[0015] In one embodiment, the high temperature oxidation unit further comprises an oxygen supply assembly connected to the air inlet of the combustion furnace;

[0016] The oxygen supply assembly includes an oxygen cylinder, an air intake pipe connected between the oxygen cylinder and the air inlet, and a pressure stabilizing valve and a flow regulating valve arranged on the air intake pipe.

[0017] In one embodiment, the acidification and separation unit includes a condensation component;

[0018] The inlet end of the condensation component is connected to the discharge port of the high-temperature oxidation unit, receives the gaseous matter discharged from the high-temperature oxidation unit and cools and condenses the gaseous matter to separate it into liquid and gas;

[0019] The gas outlet end of the condensation component is connected to the adsorption unit to transport the separated gas to the adsorption unit.

[0020] In one embodiment, the condensation assembly includes a fan condensation unit, a condensed water storage tank, and a semiconductor condenser. The condensed water storage tank is connected between the fan condensation unit and the semiconductor condenser. The gaseous substance undergoes primary condensation through the fan condensation unit and then enters the acidified water tank. The separated gas flows from bottom to top in the acidified water tank and enters the semiconductor condenser for secondary condensation. The gas after secondary condensation by the semiconductor condenser is output from the outlet end of the semiconductor condenser.

[0021] The gas outlet end of the semiconductor condenser is connected to the adsorption unit.

[0022] In one embodiment, the acidification and separation unit further comprises a gas detection component for measuring the carbon dioxide content in the gas, wherein the gas detection component comprises an NDIR carbon dioxide sensor;

[0023] The gas outlet end of the condensation component is connected to the gas detection component and the adsorption unit respectively through a first three-way valve, and the tail gas of the adsorption unit flows to the gas detection component through the first three-way valve.

[0024] In one embodiment, the adsorption unit includes at least one molecular sieve adsorption column for adsorbing CO2, a heating mechanism for heating the molecular sieve adsorption column, and a cooling mechanism for cooling the molecular sieve adsorption column;

[0025] The inlet end of the molecular sieve adsorption column is connected to the gas outlet end of the acidification and separation unit, and the outlet end of the molecular sieve adsorption column is connected to the gas inlet end of the measurement unit.

[0026] In one embodiment, the adsorption unit comprises two molecular sieve adsorption columns connected in parallel;

[0027] The inlet ends of the two molecular sieve adsorption columns are connected to the gas outlet end of the acidification and separation unit through a fifth three-way valve.

[0028] In one embodiment, the measuring unit comprises a beta probe.

[0029] Nuclear power plant liquid effluent of the present invention 14 C online continuous monitoring device collects, oxidizes at high temperature, separates and adsorbs the liquid effluent of nuclear power plants, and finally measures it through the measuring unit to achieve the liquid effluent of nuclear power plants. 14 The activity concentration of C can be monitored automatically, reducing manual operations, shortening sample preparation time and improving efficiency. The high-temperature oxidation combustion method used has a higher carbon conversion efficiency than the wet oxidation method. At the same time, it can continuously prepare and measure large-volume liquid effluents, greatly reducing the liquid effluent 14 The detection limit of C. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0031] Figure 1 It is a liquid effluent from a nuclear power plant according to an embodiment of the present invention. 14 C. Connection diagram of online continuous monitoring device. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0033] like Figure 1 As shown, the liquid effluent of a nuclear power plant according to an embodiment of the present invention 14 C online continuous monitoring device, including a collection unit 10, a high-temperature oxidation unit 20, an acidification and separation unit 30, an adsorption unit 40 and a measurement unit 50 connected in sequence.

[0034] Among them, the collection unit 10 is used to collect the liquid effluent of the nuclear power plant to form the liquid to be tested, and can transport the liquid to be tested to the high-temperature oxidation unit 20. The high-temperature oxidation unit 20 is connected between the collection unit 10 and the acidification and separation unit 30, and is used to perform high-temperature combustion treatment on the liquid to be tested to form a gaseous substance; the gaseous substance is sent to the acidification and separation unit 30 for gas-liquid separation treatment. The acidification and separation unit 30 receives the gaseous substance from the high-temperature oxidation unit 20, cools down, condenses and acidifies the gaseous substance, and separates it into condensate and gas. The gas outlet end of the acidification and separation unit 30 is connected to the adsorption unit 40 to send the separated gas to the adsorption unit 40. The adsorption unit 40 is connected between the acidification and separation unit 30 and the measuring unit 50, and is used to adsorb CO2 (carbon dioxide) in the gas, and can desorb the adsorbed carbon dioxide and transport it to the measuring unit 50 for measurement. The measuring unit 50 measures CO2 in 14 C (i.e. C-14) activity concentration.

[0035] Specifically, the collection unit 10 is used for large-volume water sample collection (>100 mL). The collected liquid effluent from the nuclear power plant forms a test liquid that is transported to the backend for further processing. The collection unit 10 may include a booster pump 11, a filter assembly, and a first peristaltic pump 12; the booster pump 11, the filter assembly, and the first peristaltic pump 12 are connected in series via an inlet pipe 100. The inlet end of the booster pump 11 is connected to the source of the liquid effluent. After passing through the booster pump 11, the liquid effluent is filtered by the filter assembly along the inlet pipe 100 and then quantitatively extracted by the first peristaltic pump 12 to enter the subsequent high-temperature oxidation unit 20.

[0036] According to the measurement requirements, the sampling volume and sampling interval are set on the first peristaltic pump 12, and sampling is stopped when the set volume is reached.

[0037] Alternatively, the filtration assembly includes a cotton filter 13 and an ultrafiltration filter 14 connected in series between the booster pump 11 and the first peristaltic pump 12. The booster pump 11 increases the pressure of the liquid effluent of the nuclear power plant so that it passes through the cotton filter 13 and the ultrafiltration filter 14, filtering out suspended matter, particulate matter, colloids, etc. in the liquid effluent of the nuclear power plant to prevent subsequent combustion from clogging the gas pipeline.

[0038] The cotton filter 13 may be made of, but not limited to, PP cotton, and the filtration diameter of the cotton filter 13 may be 1 μm. The ultrafiltration filter 14 uses an ultrafiltration membrane as a filtration body, and the pore size of the ultrafiltration membrane is 1 nm to 100 nm, which can filter and remove polymer colloids, suspended particles, etc.

[0039] The filter assembly can be integrated with a pressure sensor to monitor the filter pressure difference in real time, which is used to monitor the contamination level of the filter assembly and facilitate the replacement of the filter assembly for maintenance.

[0040] A stainless steel filter screen 15 can also be provided at the inlet end of the booster pump 11 to filter and remove flocculent matter and large particles in the liquid effluent of the nuclear power plant. As an option, the filtration accuracy of the stainless steel filter screen 15 can reach 1 mm.

[0041] First peristaltic pump 12 is connected to the feed port of high-temperature oxidation unit 20 and quantitatively delivers the test liquid to high-temperature oxidation unit 20. High-temperature oxidation unit 20 is primarily used to perform high-temperature combustion of the test liquid using a catalyst in an oxygen-rich environment, converting organic carbon and some inorganic carbon in the test liquid into CO2, thereby forming a gaseous product including gas, which contains CO2. The high-temperature oxidation temperature of high-temperature oxidation unit 20 is between 680°C and 1000°C, and in one embodiment, the temperature is preferably 750°C.

[0042] The high-temperature oxidation unit 20 may further include a combustion furnace 21 and an oxygen supply assembly. The feed port of the combustion furnace 21 forms the feed port of the high-temperature oxidation unit 20, and the feed port is connected to the collection unit 10 to receive the liquid to be tested; the discharge port of the combustion furnace 21 is connected to the acidification and separation unit 30, and the air inlet of the combustion furnace 21 is connected to the oxygen supply assembly for receiving oxygen. The combustion furnace 21 is a temperature-adjustable heating furnace that can adjust the combustion temperature as needed. A quartz tube 211 is provided in the combustion furnace 21, and a catalyst is placed in the quartz tube 211. Quartz crushed quartz is also filled in the tube to divide the airflow, extend the contact area and time between the airflow and the catalyst, increase the heated area, and improve the oxidation efficiency.

[0043] The catalyst is preferably a platinum alumina catalyst.

[0044] The oxygen supply assembly is used to provide oxygen to the combustion furnace 21. Specifically, the oxygen supply assembly may include an oxygen cylinder 22, an intake pipe 23 connected between the oxygen cylinder 22 and the air inlet of the combustion furnace 21, and a pressure-stabilizing valve 24 and a flow-regulating valve 25 disposed on the intake pipe 23. Oxygen in the oxygen cylinder 22 is introduced into the combustion furnace 21 along the intake pipe 23 through the pressure-stabilizing valve 24 and the flow-regulating valve 25, where it mixes with the test liquid within the combustion furnace 21, allowing the test liquid to be fully combusted and oxidized. Under high-temperature catalysis, the test liquid is vaporized into water vapor, and the organic carbon and some inorganic carbon in the test liquid are converted into CO2. The set oxygen flow rate is coordinated with the flow rate of the sample liquid (i.e., the flow rate of the test liquid) entering the combustion furnace 21. A pressure gauge 24 is also provided on the intake pipe 23 to monitor and display the air pressure within the intake pipe 23; the pressure gauge 24 is preferably located between the pressure-stabilizing valve 24 and the flow-regulating valve 25.

[0045] The high temperature oxidation unit 20 utilizes the flow regulating valve 25 to cooperate with the first peristaltic pump 12 of the collection unit 10. According to the monitoring requirements, the oxygen intake volume can be adjusted according to the amount of liquid injected each time to achieve full oxidation and combustion of the liquid to be tested.

[0046] The acidification and separation unit 30 is at least used to cool, condense, and acidify the product (gaseous material) from the high-temperature oxidation unit 20, achieving gas-water separation. Accordingly, the acidification and separation unit 30 may include a condensation assembly; the inlet of the condensation assembly is connected to the outlet of the high-temperature oxidation unit 20, receives the gaseous material discharged from the high-temperature oxidation unit 20, cools and condenses it, and separates the gaseous material into condensate (primarily water) and gas; the outlet of the condensation assembly is connected to the adsorption unit 40, which delivers the separated gas to the adsorption unit 40.

[0047] Furthermore, the condensation assembly includes a fan condensation unit 31, a condensed water storage tank 32, and at least one semiconductor condenser 33. The condensed water storage tank 32 is connected between the fan condensation unit 31 and the semiconductor condenser 33 via a gas pipeline. After the gas is initially condensed by the fan condensation unit 31, it enters the acidified water tank 32, where the remaining inorganic carbon in the gas is converted into CO2 and some of the CO2 dissolved in the liquid is released. The separated gas flows from bottom to top in the acidified water tank 32 and enters the semiconductor condenser 33 for secondary condensation, further separating the water vapor in the gas. The gas after secondary condensation by the semiconductor condenser 33 is output from the gas outlet of the semiconductor condenser 33, and the liquid formed after the secondary condensation flows to and is stored in the waste liquid tank 310.

[0048] In the condensation assembly, the fan condensation unit 31 improves condensation efficiency by extending the gas pipeline. The acidified water tank 32 is located between the fan condensation unit 31 and the semiconductor condenser 33. The acidified water tank 32 is located lower than the semiconductor condenser 33. Gas flows from the bottom of the acidified water tank 32 to the top before entering the semiconductor condenser 33. The outlet of the semiconductor condenser 33 is connected to the adsorption unit 40.

[0049] In an optional embodiment, two semiconductor condensers 33 are provided, and the two semiconductor condensers 33 are connected in series to the fan condensation unit 31 to improve the condensation effect and the gas-water separation effect.

[0050] The acidification and separation unit 30 also includes an automatic acidification assembly for quantitatively adding acid to the acidified water tank 32. The automatic acidification assembly may include an acid storage tank 34 and a second peristaltic pump 35. The second peristaltic pump 35 is configured to quantitatively add acid from the acid storage tank 34 to the acidified water tank 32 and dynamically add acid based on the pH of the acidified water tank 32 to maintain the pH value <2.

[0051] In one embodiment, the acid solution is a 10% concentration phosphoric acid solution.

[0052] The acidification and separation unit 30 also includes a gas detection assembly for measuring the carbon dioxide content in the separated gas. The measured carbon dioxide content can be used to determine the total carbon dioxide content in the liquid effluent of the nuclear power plant. The gas outlet of the condensation assembly can be connected to the gas detection assembly and the adsorption unit 40 via a first three-way valve 36. The first three-way valve 36 switches the pipelines to connect the condensation assembly and the gas detection assembly, or to connect the adsorption unit 40 and the gas detection assembly. Specifically, with the semiconductor condenser 33 serving as the rear end of the condensation assembly, the gas outlet of the semiconductor condenser 33 forms the gas outlet of the condensation assembly.

[0053] The gas detection assembly may include an NDIR (non-dispersive infrared) carbon dioxide sensor 37. A mass flowmeter 38 is connected in series between the first three-way valve 36 and the NDIR carbon dioxide sensor 37 to monitor the incoming gas flow rate. A halogen remover may also be connected in series between the first three-way valve 36 and the NDIR carbon dioxide sensor 37 to remove halogens from the gas, as needed.

[0054] In one embodiment, when a small amount of sample (test liquid) is quantitatively taken for combustion, the first three-way valve 36 switches to the gas detection assembly, where the carbon dioxide content of the gas is measured by the NDIR carbon dioxide sensor 37. When quantitative sampling is performed, the first three-way valve 36 switches to the adsorption unit 40 for sample preparation. The exhaust gas from the adsorption unit 40 is then connected to the NDIR carbon dioxide sensor 37 via the measurement line 411 and the second three-way valve 39 to measure the carbon dioxide content in the exhaust gas. The second three-way valve 39 is connected in series with the first three-way valve 36.

[0055] Preferably, the first three-way valve 36 and the second three-way valve 39 can be three-way solenoid valves to facilitate automatic control.

[0056] The acidification and separation unit 30 may further include a waste liquid tank 310 and a third peristaltic pump 311. The outlet end of the third peristaltic pump 311 is connected to the waste liquid tank 310, and the inlet end of the third peristaltic pump 311 can be connected to the acidified water tank 32 and the semiconductor condenser 33 respectively, so that the liquid discharged from the acidified water tank 32 and the semiconductor condenser 33 enters the waste liquid tank 310 for storage.

[0057] According to the layout and connection requirements, the inlet end of the third peristaltic pump 311 is connected to the acidified water tank 32 and the semiconductor condenser 33 respectively through the third three-way valve 312. The connection of different pipelines is achieved by switching the third three-way valve 312 to control the discharge of condensed water.

[0058] The third three-way valve 312 is preferably a three-way solenoid valve.

[0059] The adsorption unit 40 is used to adsorb carbon dioxide from the separated gas and also to desorb the absorbed carbon dioxide for delivery to the measurement unit 50. The adsorption unit 40 may include at least one molecular sieve adsorption column 41 for adsorbing CO2, a heating mechanism 42 for heating the molecular sieve adsorption column 41, and a cooling mechanism (not shown) for cooling the molecular sieve adsorption column.

[0060] The molecular sieve adsorption column 41 can adsorb CO2 in the gas at room temperature and pressure; after adsorbing CO2, the adsorbed CO2 can be desorbed by increasing the temperature and decreasing the pressure of the molecular sieve adsorption column 41, and the molecular sieve can be regenerated at the same time. The molecular sieve of the molecular sieve adsorption column 41 can be selected but not limited to 13X molecular sieve. 13X molecular sieve is powdered with an effective pore size of Static CO2 adsorption capacity (adsorption temperature 25℃) ≥23.5%.

[0061] The inlet end of the molecular sieve adsorption column 41 is connected to the outlet end of the acidification and separation unit 30. The gas separated by the acidification and separation unit 30 enters the molecular sieve adsorption column 41, and the CO2 in the gas is adsorbed by the molecular sieve adsorption column 41. The outlet end of the molecular sieve adsorption column 41 is connected to the inlet end of the measurement unit 50. After adsorption, the CO2 is desorbed under the conditions of increasing temperature and decreasing pressure. The desorbed CO2 enters the measurement unit 50 for measurement. 14 C radiation activity is measured.

[0062] In one embodiment, the outlet end of the molecular sieve adsorption column 41 is connected to the gas detection assembly and the measuring unit 50 via a fourth three-way valve 43. The fourth three-way valve 43 is used to switch the pipeline, so that the molecular sieve adsorption column 41 is connected to the gas detection assembly through the measuring pipeline 411, or the molecular sieve adsorption column 41 is connected to the measuring unit 50. During adsorption, the molecular sieve adsorption column 41 is connected to the gas detection assembly via the fourth three-way valve 43. The molecular sieve adsorption column 41 receives gas from the acidification and separation unit 30 and adsorbs CO2 in the gas. The exhaust gas flows to the gas detection assembly through the fourth three-way valve 43, the measuring pipeline 411, and the second three-way valve 39 in sequence. The gas detection assembly detects the CO2 content in the exhaust gas, and the adsorption rate of CO2 by the molecular sieve adsorption column 41 can be calculated. After adsorption is complete, the molecular sieve adsorption column 41 is disconnected from the gas detection assembly. The adsorbed CO2 is desorbed by increasing the temperature and decreasing the pressure on the molecular sieve adsorption column 41. The molecular sieve adsorption column 41 is then connected to the measurement unit 50 via the fourth three-way valve 43. The desorbed CO2 enters the measurement unit 50 for measurement. During desorption, the molecular sieve adsorption column 41 is heated to 200°C to 250°C while maintaining a vacuum level of <5 Pa.

[0063] The heating mechanism 42 is used to increase the temperature and reduce the pressure of the molecular sieve adsorption column 41. The heating mechanism 42 may include at least one of a heating plate and a heating rod, so as to be able to evenly heat the molecular sieve adsorption column 41. Preferably, an infrared heating plate is used to heat the molecular sieve adsorption column 41 to reduce the heat capacity of the heating plate itself. After the desorption of the molecular sieve adsorption column 41 is completed and before the next adsorption work is carried out, the molecular sieve adsorption column 41 can be cooled by a cooling mechanism so that the molecular sieve adsorption column 41 returns to normal temperature and pressure within a short time (such as 30 minutes). The cooling method of the molecular sieve adsorption column 41 by the cooling mechanism may include at least one of air cooling and water cooling; based on the protection of equipment such as the molecular sieve adsorption column 41, it is preferred to adopt air cooling, and the corresponding cooling mechanism is an air-cooled radiator, etc.

[0064] In a preferred embodiment, the adsorption unit 40 includes two molecular sieve adsorption columns 41 connected in parallel. The parallel arrangement of the two molecular sieve adsorption columns 41 enables alternating adsorption and desorption of CO2, which facilitates the continuous automatic operation of the adsorption unit 40.

[0065] Specifically, the inlet ends of the two molecular sieve adsorption columns 41 are connected to the gas outlet end of the acidification and separation unit 30 through the fifth three-way valve 44, and the outlet ends of the two molecular sieve adsorption columns 41 are respectively connected to the fourth three-way valve 43. The two fourth three-way valves 43 are connected in parallel to the sixth three-way valve 45, and are connected to the measuring pipeline 411 through the sixth three-way valve 45. During adsorption, the pipeline of the three-way valve is switched so that one of the molecular sieve adsorption columns 41 performs adsorption work and the other molecular sieve adsorption column 41 does not perform adsorption work. During desorption, the molecular sieve adsorption column 41 that has completed adsorption is disconnected from the acidification and separation unit 30 to form a closed state and perform desorption work. The other molecular sieve adsorption column 41 is connected to the acidification and separation unit 30 and receives gas for adsorption work, thereby alternating between adsorption and desorption.

[0066] The measuring unit 50 includes a beta detector 51; the beta detector uses plastic scintillation microspheres to detect CO2 14 C is used for beta counting. The plastic scintillation microspheres are polystyrene-based plastic scintillation microspheres (doped with scintillator PPO and wavelength converter POPOP) with a diameter of 20 μm to 50 μm.

[0067] The front end of the beta detector 51 is connected to the adsorption unit 40 via a pipeline and a seventh three-way valve 52. A vacuum pump 53 is also connected to the pipeline between the seventh three-way valve 52 and the beta detector 51 to evacuate the pipeline. Before the CO2 is desorbed and transferred to the measurement unit 50, the vacuum pump 53 evacuates the pipeline in front of the beta detector 51. The CO2 desorbed from the molecular sieve adsorption column 41 flows along the pipeline into the beta detector 51. The connection between the vacuum pump 53 and the pipeline is automatically controlled by a solenoid valve.

[0068] Nuclear power plant liquid effluent of the present invention 14 C online continuous monitoring device to realize the liquid effluent of nuclear power plant 14 C online continuous monitoring, corresponding to the liquid effluent of nuclear power plants 14 C online continuous monitoring method includes the following steps:

[0069] A small amount of the liquid to be tested is drawn into the combustion furnace 21 through the collection unit 10 and mixed with oxygen for oxidation and combustion to form gas. The high-temperature gas after combustion passes through the fan condensation unit 31 to separate the water and gas, and then passes through the semiconductor condenser 33 to further remove the water. The separated gas is connected to the measurement pipeline of the NDIR carbon dioxide sensor 37 through a three-way solenoid valve to measure the total carbon content (carbon concentration) in the liquid effluent of the nuclear power plant.

[0070] A certain amount of the test liquid is then re-extracted into the combustion furnace 21 for catalytic oxidation. After the water is removed by the condensation component, the gas is connected to the adsorption unit 40 through a three-way solenoid valve. The adsorption unit 40 adsorbs the CO2 therein. The tail gas of the adsorption unit 40 enters the NDIR carbon dioxide sensor 37. The adsorption rate of CO2 by the adsorption unit 40 can be calculated after measurement. The adsorption unit 40 desorbs the CO2 and transfers it to the β detector 51 for measurement, obtaining the liquid effluent of the nuclear power plant. 14 The activity concentration of C.

[0071] After the measurement is completed, high purity oxygen is used to purify the liquid effluent of the nuclear power plant. 14 C The entire pipeline of the online continuous monitoring device is purged.

[0072] Nuclear power plant liquid effluent of the present invention 14 The C online continuous monitoring device has a reasonable structural design and high detection accuracy. Each unit of the present invention can be controlled by a control system, can be operated with one button, and can achieve 24-hour continuous monitoring without human intervention, which is stable and reliable.

[0073] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A liquid effluent from a nuclear power plant 14 C online continuous monitoring device, characterized in that, include: A collection unit, used to collect liquid effluent from the nuclear power plant to form a liquid to be tested; The high-temperature oxidation unit is used to subject the liquid to be tested to high-temperature combustion treatment, so that the organic carbon and part of the inorganic carbon in the liquid to be tested are converted into CO2, and a gaseous substance containing CO2 is obtained; an acidification and separation unit, for cooling, condensing and acidifying the gaseous substance, and separating the gaseous substance into liquid and gas; an adsorption unit, comprising at least one molecular sieve adsorption column for absorbing carbon dioxide in the gas; as well as Measuring unit for measuring the CO2 desorbed from the molecular sieve adsorption column 14 Activity concentration of C; The high-temperature oxidation unit is connected between the collection unit and the acidification and separation unit; the gas outlet of the acidification and separation unit is connected to the adsorption unit to send the separated gas into the adsorption unit; the adsorption unit is connected to the measuring unit to send the desorbed CO2 into the measuring unit for measurement.

2. The liquid effluent from a nuclear power plant according to claim 1 14 C online continuous monitoring device, characterized in that, The collection unit includes a booster pump, a filter assembly and a first peristaltic pump connected in series through an inlet pipe; The first peristaltic pump is connected to the feed port of the high-temperature oxidation unit to quantitatively transport the liquid to be tested to the high-temperature oxidation unit.

3. The liquid effluent from a nuclear power plant according to claim 1 14 C online continuous monitoring device, characterized in that, The high-temperature oxidation unit includes a combustion furnace; the feed port of the combustion furnace is connected to the collection unit, the discharge port of the combustion furnace is connected to the acidification and separation unit, and the air inlet of the combustion furnace is used to access oxygen.

4. The liquid effluent from a nuclear power plant according to claim 3 14 C online continuous monitoring device, characterized in that, The high temperature oxidation unit further comprises an oxygen supply assembly connected to the air inlet of the combustion furnace; The oxygen supply assembly includes an oxygen cylinder, an air intake pipe connected between the oxygen cylinder and the air inlet, and a pressure stabilizing valve and a flow regulating valve arranged on the air intake pipe.

5. The liquid effluent from a nuclear power plant according to claim 1 14 C online continuous monitoring device, characterized in that, The acidification and separation unit includes a condensation component; The inlet end of the condensation component is connected to the discharge port of the high-temperature oxidation unit, receives the gaseous matter discharged from the high-temperature oxidation unit and cools and condenses the gaseous matter to separate it into liquid and gas; The gas outlet end of the condensation component is connected to the adsorption unit to transport the separated gas to the adsorption unit.

6. The liquid effluent from a nuclear power plant according to claim 5 14 C online continuous monitoring device, characterized in that, The condensation assembly includes a fan condensation unit, an acidified water tank, and a semiconductor condenser. The acidified water tank is connected between the fan condensation unit and the semiconductor condenser. The gaseous substance undergoes primary condensation through the fan condensation unit and then enters the acidified water tank. The separated gas flows from bottom to top in the acidified water tank and enters the semiconductor condenser for secondary condensation. The gas after secondary condensation by the semiconductor condenser is output from the outlet end of the semiconductor condenser. The gas outlet end of the semiconductor condenser is connected to the adsorption unit.

7. The liquid effluent from a nuclear power plant according to claim 5 14 C online continuous monitoring device, characterized in that, The acidification and separation unit further comprises a gas detection component for measuring the carbon dioxide content in the gas, wherein the gas detection component comprises an NDIR carbon dioxide sensor; The gas outlet end of the condensation component is connected to the gas detection component and the adsorption unit respectively through a first three-way valve, and the tail gas of the adsorption unit flows to the gas detection component through the first three-way valve.

8. The liquid effluent from a nuclear power plant according to claim 1 14 C online continuous monitoring device, characterized in that, The adsorption unit includes at least one molecular sieve adsorption column for adsorbing CO2, a heating mechanism for heating the molecular sieve adsorption column, and a cooling mechanism for cooling the molecular sieve adsorption column; The inlet end of the molecular sieve adsorption column is connected to the gas outlet end of the acidification and separation unit, and the outlet end of the molecular sieve adsorption column is connected to the gas inlet end of the measurement unit.

9. The liquid effluent from a nuclear power plant according to claim 8 14 C online continuous monitoring device, characterized in that, The adsorption unit includes two molecular sieve adsorption columns connected in parallel; The inlet ends of the two molecular sieve adsorption columns are connected to the gas outlet end of the acidification and separation unit through a fifth three-way valve.

10. The liquid effluent from a nuclear power plant according to any one of claims 1 to 9. 14 C online continuous monitoring device, characterized in that, The measuring unit includes a beta detector.

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