A high-efficiency removal device for iodine in a spent fuel dissolving solution and a method thereof

Abstract

The present application relates to a kind of high-efficiency removal device and method for iodine in spent fuel solution, including iodine removal reactor, solution storage tank system, gas supply and preheating system, liquid delivery system, control system and tail gas treatment system, solution storage tank is connected with iodine removal reactor by liquid delivery system, gas supply and preheating system are connected with iodine removal reactor, tail gas treatment system is connected with the output end of iodine removal reactor, control system is connected with communication of iodine removal reactor, solution storage tank system, gas supply and preheating system, liquid delivery system and tail gas treatment system.The device disclosed in the present application, by the structure design of optimization and high-precision control system, realize the high-efficiency stable removal of iodine in spent fuel solution under the condition of temperature 75~98 ℃, gas-liquid ratio 80:1~160:1, realize long-distance operation maintenance, with good engineering amplification potential, suitable for continuous reliable operation in radioactive environment.

Description

Technical Field

[0001] This invention belongs to the field of spent fuel reprocessing, specifically relating to a highly efficient device and method for removing iodine from spent fuel dissolution liquid. Background Technology

[0002] With the continuous development of nuclear energy utilization technology, the treatment of iodine-containing radioactive waste generated during spent fuel reprocessing has become an important issue. Iodine (especially radioactive iodine isotopes, such as...) 129 I, 131 I) It has high volatility and bioaccumulation, and if not properly treated, it will cause serious harm to the environment and human health. At present, the treatment methods for iodine-containing waste liquid at home and abroad include adsorption, precipitation, distillation and gas stripping, but they generally suffer from problems such as low efficiency, complex operation, large equipment size and difficulty in achieving continuous engineering operation.

[0003] Especially during engineering scale-up, traditional laboratory equipment struggles to meet the requirements of high flow rates, high concentrations, and continuous, stable operation. Existing iodine removal equipment still needs improvement in terms of processing efficiency, gas-liquid mass transfer, temperature and pressure control accuracy, equipment reliability, and remote maintainability.

[0004] Therefore, there is an urgent need to develop an iodine removal device that is structurally sound, stable in operation, highly efficient, and has promising engineering applications. Summary of the Invention

[0005] To address the technical deficiencies of existing iodine treatment equipment in terms of processing efficiency, control precision, operational stability, and maintainability, the present invention aims to provide a highly efficient iodine removal device and method for spent fuel dissolution. This highly efficient iodine removal device overcomes the limitations of laboratory-grade devices in terms of processing capacity, operational stability, and continuous operating time. It provides a scalable device that can adapt to high flow rates (≥750 L / h) and high gas-liquid ratio conditions and has promising engineering applications, thereby solving the challenges of engineering scale-up.

[0006] By optimizing the reactor structure (such as a tower of specific dimensions and a high-efficiency gas distributor) and the precise control system, the iodine removal rate can be stably maintained at over 96% under a wide range of process conditions (such as temperatures of 75–98°C and gas-liquid ratios of 80:1–160:1), while also meeting stringent requirements for the residual nitrite concentration at the outlet (<4 × 10⁻⁶). -3 (mol / L) to improve iodine removal efficiency and stability.

[0007] By integrating high-precision temperature (control accuracy ±2℃), pressure (control accuracy ±0.1 MPa), flow rate (control accuracy ±0.1%) and liquid level monitoring and control systems, the coordinated operation of each process unit is ensured, achieving stable, controllable, and repeatable operation throughout the entire process, and realizing precise and coordinated control of process parameters.

[0008] For radioactive operating environments, a control system with complete safety interlock logic is designed, and a modular maintenance structure that supports remote and rapid disassembly and replacement of vulnerable parts is constructed. This significantly improves the inherent safety and maintainability of the device, reduces the risk of personnel exposure to radiation, and ensures operational safety and equipment reliability in radioactive environments.

[0009] By integrating the main iodine removal equipment with auxiliary systems (such as feeding, preheating, and exhaust gas treatment), a complete engineering prototype system with feasible processes, reliable equipment, and precise control is formed, providing a complete engineering solution and providing direct technical basis and practical experience for the design, construction, and operation of subsequent commercial-scale treatment plants.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] In a first aspect, the present invention discloses a high-efficiency iodine removal device for spent fuel dissolving liquid. The device includes an iodine removal reactor, a dissolving liquid storage tank system, a gas supply and preheating system, a liquid conveying system, a control system, and a tail gas treatment system. The dissolving liquid storage tank is connected to the iodine removal reactor via the liquid conveying system. The gas supply and preheating system is connected to the iodine removal reactor. The tail gas treatment system is connected to the output end of the iodine removal reactor. The control system is communicatively connected to the iodine removal reactor, the dissolving liquid storage tank system, the gas supply and preheating system, the liquid conveying system, and the tail gas treatment system.

[0012] An iodine removal reactor is used to react the dissolving liquid and the removal gas, thereby removing iodine from the liquid phase into the gas phase.

[0013] The solution storage tank system is used to temporarily store the solution and preheat it to a set temperature;

[0014] A gas supply and preheating system is used to prepare the purging gas and heat it to a set temperature. The purging gas includes air and nitrogen oxides.

[0015] A liquid delivery system is used to transport the solution from the solution storage tank to the iodine removal reactor;

[0016] The control system is used for data recording, valve control, interlocking operations, status display, and abnormal alarms throughout the entire process.

[0017] The exhaust gas treatment system is used to treat iodine-containing gases.

[0018] Furthermore, the iodine removal reactor includes a solution inlet at the bottom, a gas inlet on the top cover, a first gas distributor connected to the gas inlet on the top cover, a second gas distributor, a liquid overflow outlet, a gas-liquid separator, and a gas outlet. The gas-liquid separation and demisting device is located at the top of the tower, and the gas distributor is located at the bottom of the tower. The first gas distributor is used to disperse the gas containing nitrogen oxides, so that it can fully contact and react with the solution; the second gas distributor is used to disperse the hot air, so that it can remove iodine to the gas phase; and the gas-liquid separator is used to separate the entrained liquid in the gas.

[0019] Furthermore, the solution storage tank system includes at least one solution storage tank, the volume of which meets the requirements for continuous feeding; a heating device and a liquid level sensor are installed inside the solution storage tank.

[0020] Furthermore, the gas supply and preheating system includes an air compressor, a nitrogen oxide supply unit, and a mixed gas preheater. The air compressor is used to provide the gas source; the nitrogen oxide unit is used to provide nitrogen oxides at a set flow rate. The gases provided by the two are mixed to form a mixed gas, which is then heated to a set temperature by the mixed gas preheater.

[0021] Furthermore, the liquid delivery system includes an inlet pump, a drain pump, and a raw material pump.

[0022] Furthermore, the top cover of the iodine removal reactor is equipped with a quick-locking device, which supports disassembly and assembly by robotic arms or hoisting equipment, facilitating remote maintenance.

[0023] Secondly, the present invention discloses a highly efficient method for removing iodine from spent fuel dissolution fluid, based on the highly efficient iodine removal device for spent fuel dissolution fluid described in the first aspect of the present invention and any optional embodiment thereof, the method comprising the following steps:

[0024] S1. The solution preheated to the set temperature in the solution storage tank is transported to the iodine removal reactor through the liquid delivery system;

[0025] S2. The gas supply and preheating system heats the air containing nitrogen oxides in a certain proportion to a set temperature and introduces it into the bottom and middle of the iodine removal reactor, and then into the iodine removal reactor through the gas distributor.

[0026] S3. The nitrogen oxide-containing air entering the iodine removal reactor reacts and bubbles fully with the solution to remove iodine.

[0027] S4. The dissolved solution after removal overflows from the iodine removal reactor and enters the dissolved solution storage tank for temporary storage; the iodine-containing gas after removal enters the tail gas treatment system.

[0028] Furthermore, the gas-liquid ratio entering the iodine removal reactor is between 80:1 and 160:1.

[0029] The beneficial technical effects of this invention are as follows: The highly efficient iodine removal device and method disclosed in this invention for spent fuel solvent can achieve efficient, continuous, and reliable iodine removal operation. Specifically, the beneficial effects are reflected in:

[0030] (1) Stable and reliable operation: Through optimized reactor structure design and gas-liquid mass transfer process, efficient removal of iodine from spent fuel solution was achieved. Within a wide operating range of 75–98℃ and gas-liquid ratio of 80:1–160:1, the iodine removal rate remained consistently above 96%, and the residual nitrite concentration at the outlet was below 4 × 10⁻⁶. -3 The concentration of mol / L meets the stringent requirements for engineering processing. The equipment exhibits excellent load adaptability and anti-interference capabilities, with continuous operation time exceeding 80 hours and cumulative operation exceeding 240 hours without failure, and process repeatability deviation less than 5%.

[0031] (2) High control precision and good system coordination are achieved. The integrated high-precision control system realizes precise control of key parameters such as temperature (±2℃), pressure (±0.1 MPa), flow rate (±0.1%) and liquid level. Through the perfect safety interlock logic, the coordinated operation between various process units is ensured, and abnormal conditions such as over-temperature and over-pressure are effectively avoided, which significantly improves the automation level and operational safety of the equipment.

[0032] (3) It is highly maintainable and suitable for radioactive environments. The device adopts a modular design, and key components have quick-connect interfaces. The reactor top cover is equipped with a special locking device, which supports remote disassembly and assembly operations by robotic arms or hoisting equipment; vulnerable parts such as pumps, valves, and sensors can be replaced remotely. This feature greatly reduces the radiation risk to maintenance personnel, making the device particularly suitable for long-term operation in high-radioactive environments.

[0033] (4) The project has wide applicability and small scale-up effect. Based on the experimental verification of the engineering prototype, the structure of this device is reasonable and the range of process parameters is clear, providing a reliable technical basis for the design of commercial-scale treatment plants. Its modular configuration and standardized interface facilitate flexible configuration and expansion according to the processing capacity, effectively reducing the technical risks and investment uncertainties in the process of scaling up the device.

[0034] (5) The system has a high degree of integration and good environmental compatibility. The device achieves system integration of iodine removal and tail gas treatment, and can be seamlessly linked with the iodine capture engineering prototype to form a complete iodine treatment process chain. The entire system adopts corrosion-resistant materials and a sealed structure, which effectively prevents the leakage of radioactive materials and has excellent environmental compatibility and safety performance. Attached Figure Description

[0035] Figure 1This is a schematic diagram of a highly efficient iodine removal device for spent fuel solvent, as shown in Embodiment 1 of the present invention. Detailed Implementation

[0036] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment of the invention provides a high-efficiency iodine removal device for spent fuel dissolution liquid, including an iodine removal reactor, a dissolution liquid storage tank system, a gas supply and preheating system, a liquid conveying system, a control system, and a tail gas treatment system. The dissolution liquid storage tank is connected to the iodine removal reactor through the liquid conveying system. The gas supply and preheating system is connected to the iodine removal reactor. The tail gas treatment system is connected to the output end of the iodine removal reactor. The control system is communicatively connected to the iodine removal reactor, the dissolution liquid storage tank system, the gas supply and preheating system, the liquid conveying system, and the tail gas treatment system.

[0039] The iodine removal reactor is used to react the dissolving solution and the removal gas, removing iodine from the liquid phase to the gas phase; the dissolving solution storage tank is used to temporarily store the dissolving solution and preheat it to a set temperature; the gas supply and preheating system is used to prepare the removal gas and heat it to a set temperature, and the removal gas includes air and nitrogen oxides; the liquid conveying system is used to transport the dissolving solution from the dissolving solution storage tank to the iodine removal reactor; the control system is used to record data, control valves, perform interlock operations, display status, and provide alarms for abnormalities throughout the entire process; and the exhaust gas treatment system is used to treat the iodine-containing gas.

[0040] A liquid delivery system transports preheated solution from a storage tank to a set temperature to the iodine removal reactor. Simultaneously, a gas supply and preheating system heats air containing nitrogen oxides in a specific ratio to a set temperature and introduces it into the bottom and middle sections of the reactor. The air then enters the reactor through a gas distributor, where it fully contacts and reacts with the solution, causing bubbling and achieving iodine removal. The removed solution overflows from the reactor and is temporarily stored in a storage tank; the iodine-containing gas enters the exhaust gas treatment system. The entire process is controlled by a system that manages operation, data recording, and status display.

[0041] The iodine removal reactor is the main equipment for iodine removal; its main structure is a vertical tower.

[0042] The iodine removal reactor includes a solution inlet at the bottom, a gas inlet on the top cover, a first gas distributor connected to the gas inlet on the top cover, a second gas distributor, a liquid overflow outlet, a gas-liquid separator, and a gas outlet. The first gas distributor is used to disperse the gas containing nitrogen oxides, so that it can fully contact and react with the solution; the second gas distributor is used to disperse hot air, so that it can remove iodine to the gas phase; the gas-liquid separator is used to separate the entrained liquid in the gas.

[0043] The iodine removal reactor has a cross-sectional width of 500 mm, a cross-sectional length of 2500 mm, and an internal height of 4500 mm. It is equipped with an overflow port at a height of 3600 mm, an iodine blowing port section at a height of 3900 mm, and an aeration plate section at a height of 2×300 mm. It is made of 316L stainless steel, which is corrosion-resistant and high-temperature resistant. A gas-liquid separation and demister is installed at the top of the tower, and a liquid inlet / outlet and a gas distributor are installed at the bottom of the tower.

[0044] The solution storage tank system includes at least one solution storage tank with a volume that meets the requirements for continuous feeding; a heating device is installed inside the tank with a temperature control accuracy of ±2℃; and a liquid level sensor is installed with an accuracy of ±50 mm.

[0045] Gas supply and preheating system: Includes an air compressor, a nitrogen oxide supply unit, and a mixed gas preheater. The air compressor supplies air; the nitrogen oxide unit supplies a set flow rate of nitrogen oxides. Nitrogen oxides require a carrier gas, which is air. The two gases are mixed to form a mixed gas, which is then heated to a set temperature by the mixed gas preheater. The nitrogen oxide ratio can be freely adjusted; air flow rate control accuracy is ±0.4 m³ / h, nitrogen oxide flow rate control accuracy is ±0.1 m³ / h, and gas preheating temperature control accuracy is ±2℃.

[0046] The liquid delivery system includes an inlet pump, a drain pump, and a raw material pump, with a flow control accuracy of ±0.01 m³ / h. The pump body adopts a mechanical seal structure and has the capability for leak detection and remote replacement.

[0047] The control system integrates a PLC and a human-machine interface to achieve real-time monitoring and control of temperature, pressure, flow rate, and liquid level; it has data recording, curve plotting, safety interlocking, and alarm functions; and it supports remote operation and fault diagnosis.

[0048] The exhaust gas treatment system is linked with the iodine capture device to achieve subsequent treatment of iodine-containing exhaust gas.

[0049] The top cover of the iodine removal reactor is equipped with a quick-locking device, which supports disassembly and assembly by robotic arms or hoisting equipment, facilitating remote maintenance.

[0050] Modular design is used for key vulnerable components (such as pump seals, valves, and sensors) to support remote replacement.

[0051] The working principle of a high-efficiency iodine removal device for spent fuel solvent provided in this embodiment of the invention is as follows:

[0052] Simulated spent fuel dissolved fluid (containing IO3) - Iodine in the form of NO2 and other forms is transported from the solution storage tank to the bottom of the iodine removal reactor via the inlet pump. At the same time, the preheated mixed gas (containing NO2 and air) is blown into the tower through the gas distributor. Under the set temperature (75~98℃), pressure (atmospheric pressure~0.1 MPa) and gas-liquid ratio (80:1~160:1) conditions, the reduction, oxidation and stripping of iodine are completed. Finally, iodine enters the tail gas system in gaseous form, achieving efficient removal of iodine.

[0053] Example 2

[0054] Iodine removal was performed using a high-efficiency iodine removal device for spent fuel dissolution provided in this embodiment of the invention. The specific parameters are as follows: dissolution solution: total iodine concentration 0.07 g / L, nitric acid concentration 3.5 mol / L; gas composition: NO2 volume concentration 10%, air flow rate 120 m³ / h; operating temperature: 85℃; gas-liquid ratio: 120:1; residence time: 3 h.

[0055] Results: The iodine removal rate remained stable at 96.8%, and the system ran continuously for 80 hours without failure.

[0056] Example 3

[0057] Iodine removal was performed using a high-efficiency iodine removal device for spent fuel solvent provided in this embodiment of the invention. The iodine removal operation was carried out under low temperature conditions: operating temperature: 75℃; gas-liquid ratio: 160:1; residence time: 4 h; NO2 concentration: 20%; total iodine concentration: 0.09 g / L.

[0058] Results: The iodine removal rate reached 96.1%, the system operated stably, and met the requirements of low-temperature conditions.

[0059] Example 4

[0060] The high-efficiency iodine removal device for spent fuel solvent provided in this embodiment of the invention is used for iodine removal. Under high iodine concentration conditions: total iodine concentration: 0.5 g / L; operating temperature: 98℃; gas-liquid ratio: 140:1; NO2 concentration: 30%.

[0061] Results: The iodine removal rate reached 98.4%, and the system showed good adaptability and stability.

[0062] Example 5

[0063] Iodine removal was performed using the high-efficiency iodine removal device for spent fuel solvent provided in Embodiment 1 of the present invention, and remote maintenance verification was conducted: the reactor top cover was disassembled and assembled using a simulated robotic arm; vulnerable parts such as the mechanical seal of the inlet pump and gas valves were replaced;

[0064] Results: All operations were completed within the preset time, verifying the remote maintainability of the device.

[0065] As can be seen from the above embodiments, the efficient removal device and method for iodine in spent fuel solvent disclosed in this invention can achieve high-precision coordinated control of multiple parameters, overcome the limitations of laboratory-level devices in terms of processing capacity, operational stability and continuous operation time, adapt to high flow rate (≥750 L / h) and high gas-liquid ratio conditions, and has promising engineering application prospects.

[0066] The apparatus and method described in this invention are not limited to the embodiments described in the specific implementation. Other implementation methods derived by those skilled in the art based on the technical solution of this invention also fall within the scope of technical innovation of this invention.

Claims

1. A highly efficient device for removing iodine from spent fuel solvent, characterized in that: The apparatus includes an iodine removal reactor, a solution storage tank system, a gas supply and preheating system, a liquid conveying system, a control system, and a tail gas treatment system. The solution storage tank is connected to the iodine removal reactor via the liquid conveying system. The gas supply and preheating system is connected to the iodine removal reactor. The tail gas treatment system is connected to the output end of the iodine removal reactor. The control system is communicatively connected to the iodine removal reactor, the solution storage tank system, the gas supply and preheating system, the liquid conveying system, and the tail gas treatment system. An iodine removal reactor is used to react the dissolving liquid and the removal gas, thereby removing iodine from the liquid phase into the gas phase. The solution storage tank system is used to temporarily store the solution and preheat it to a set temperature; A gas supply and preheating system is used to prepare the purging gas and heat it to a set temperature. The purging gas includes air and nitrogen oxides. A liquid delivery system is used to transport the solution from the solution storage tank to the iodine removal reactor; The control system is used for data recording, valve control, interlocking operations, status display, and abnormal alarms throughout the entire process. The exhaust gas treatment system is used to treat iodine-containing gases.

2. The high-efficiency iodine removal device for spent fuel solvent according to claim 1, characterized in that: The iodine removal reactor includes a solution inlet at the bottom, a gas inlet on the top cover, a first gas distributor connected to the gas inlet on the top cover, a second gas distributor, a liquid overflow outlet, a gas-liquid separator, and a gas outlet. The gas-liquid separation and demisting device is located at the top of the tower, and the gas distributor is located at the bottom of the tower. The first gas distributor is used to disperse the gas containing nitrogen oxides, so that it can fully contact and react with the solution; the second gas distributor is used to disperse the hot air, so that it can remove iodine to the gas phase; the gas-liquid separator is used to separate the entrained liquid in the gas.

3. The high-efficiency iodine removal device for spent fuel solvent according to claim 1, characterized in that: The solution storage tank system includes at least one solution storage tank, the volume of which meets the requirements for continuous feeding; a heating device and a liquid level sensor are installed inside the solution storage tank.

4. The high-efficiency iodine removal device for spent fuel solvent according to claim 1, characterized in that: The gas supply and preheating system includes an air compressor, a nitrogen oxide supply unit, and a mixed gas preheater. The air compressor is used to provide the gas source; the nitrogen oxide unit is used to provide nitrogen oxides at a set flow rate. The gases provided by the two are mixed to form a mixed gas, which is then heated to a set temperature by the mixed gas preheater.

5. The high-efficiency iodine removal device for spent fuel solvent according to claim 1, characterized in that: The liquid delivery system includes an inlet pump, a drain pump, and a raw material pump.

6. The high-efficiency iodine removal device for spent fuel solvent according to claim 1, characterized in that: The top cover of the iodine removal reactor is equipped with a quick-locking device, which supports disassembly and assembly by robotic arms or hoisting equipment, facilitating remote maintenance.

7. A method for efficiently removing iodine from spent fuel solvent, based on the efficient iodine removal device for spent fuel solvent as described in any one of claims 1-6, characterized in that, The method includes the following steps: S1. The solution preheated to the set temperature in the solution storage tank is transported to the iodine removal reactor through the liquid delivery system; S2. The gas supply and preheating system heats the air containing nitrogen oxides in a certain proportion to a set temperature and introduces it into the bottom and middle of the iodine removal reactor, and then into the iodine removal reactor through the gas distributor. S3. The nitrogen oxide-containing air entering the iodine removal reactor reacts and bubbles fully with the solution to remove iodine. S4. The dissolved solution after removal overflows from the iodine removal reactor and enters the dissolved solution storage tank for temporary storage; the iodine-containing gas after removal enters the tail gas treatment system.

8. The method for efficient removal of iodine from spent fuel solvent according to claim 7, characterized in that: The gas-liquid ratio entering the iodine removal reactor is between 80:1 and 160:1.

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