Device for electrocatalytic denitration in hot chamber and using method

Abstract

The invention discloses a device for electrocatalytic denitration in a hot chamber and a using method. The device comprises a double-oval container arranged in the hot chamber, an anode, an exhaust pipe and a liquid inlet pipe are arranged at the top of the double-oval container, a cathode is arranged on the side face of the double-oval container, and a liquid outlet pipe is arranged at the bottom of the double-oval container; wherein the anode is a platinum-plated black anode, the cathode is a titanium cathode metal bar, and a porous alumina ceramic sleeve is arranged outside the anode to isolate the anode from the cathode; the double-elliptical container is filled with a high-concentration nitrate solution; according to the method, the acidity can be adjusted without adding a dilute nitric acid solution, the acidity conditions required by anion resin, cation resin and extraction resin in the process of producing actinide 225 can be met, the volume of the solution cannot be increased, the influence on the volume of an upper column liquid for radiochemical separation in the next step can be avoided, and the yield of actinide 225 is improved. And the radioactive concentration of the actinide 225 product is reduced, and the yield of the actinide 225 product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of radionuclide production, and in particular to a device for electrocatalytic denitration in a hot chamber and a use method thereof. Background Art

[0002] Proton accelerator irradiation thorium target production 225 Ac is currently the most suitable for large-scale production 225 Ac method. by high energy proton irradiation 232 When Th undergoes spallation reaction, it will contain about hundreds of radioactive isotopes. Chemical separation methods such as ion exchange, chromatography extraction, and adsorption can be used to effectively separate actinium from other elements. 232 Th spallation reaction will produce 225 Ac, and 224 Ac, 226 Ac, 227 Ac, 228 Ac and 230 Ac isotopes, except 227 All other actinium isotopes except Ac can be removed by cooling for an appropriate period of time. 225 Ac contains a small amount of 227 Ac, where 227 The radioactivity of Ac is 225 Ac accounts for 0.1-0.2% of the product. Therefore, in order to obtain actinium-225 with a radioactive nucleus purity of not less than 99%, it is necessary to ensure 225 The process conditions for Ac separation and purification are accurate.

[0003] exist 225 During the production process of Ac, the thorium target is dissolved in high acid after being blasted by an accelerator. The solution is a high-concentration nitric acid with high radioactivity. The subsequent dissolving solution is separated and purified by anion resin, cationic resin and leaching resin under different acidity conditions. The acidity requirements of each link are different, and the difference in acidity before and after is large, which requires rapid acidity adjustment in the hot chamber. At present, the chemical reduction process is mainly used to achieve denitrification of high-radioactive waste solution. The chemical reduction process uses formaldehyde or formic acid as a reducing agent for chemical denitrification. Its kinetics are faster, more efficient and more economical. This method causes the volume of the solution to increase, thereby affecting the volume of the upper column liquid in the next step of radiochemical separation, and ultimately affecting the reduction of the radioactive concentration of the actinium-225 product, resulting in production losses. At the same time, it is not conducive to remote operation and safe control in the hot chamber. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a device and a method for using electrocatalytic denitrification in a hot chamber, which is used for quickly adjusting the concentration of nitric acid in the hot chamber without expanding the volume of the solution. Nitrogen oxide waste gas generated during the electrolysis process is transported through a pipeline to an exhaust gas treatment device in the shear dissolution hot chamber for treatment. The electrochemical device is placed in the hot chamber, is simple to operate, the electrode is easy to replace, and the equipment is stable to use.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, a device for electrocatalytic denitrification in a hot chamber is provided, comprising a double elliptical container arranged in the hot chamber, an anode, an exhaust pipe and a liquid inlet pipe are arranged on the top of the double elliptical container, a cathode is arranged on the side of the double elliptical container, and a liquid outlet pipe is arranged at the bottom of the double elliptical container; wherein the anode is a platinum-plated black anode, the cathode is a titanium cathode metal rod, and a porous alumina ceramic sleeve is arranged on the outside of the anode to isolate the anode and the cathode; the double elliptical container is filled with a high-concentration nitrate solution.

[0007] In some embodiments of the present invention, the exhaust pipe includes a first exhaust pipe and a second exhaust pipe, the first exhaust pipe is located in the porous alumina ceramic sleeve, and the second exhaust pipe is located in the double elliptical container.

[0008] In some embodiments of the present invention, the first exhaust pipe and the second exhaust pipe are both connected to a three-way joint via a quick-connect joint, the three-way joint is connected to an exhaust gas reaction container, the exhaust gas reaction container performs exhaust gas reaction, and the exhaust gas reaction container is connected to an exhaust gas treatment device in an adjacent hot chamber via a gas pipeline in the hot chamber.

[0009] In some embodiments of the present invention, the platinum-plated black anode is a 50% hollow mesh, the electrode thickness is 1-2 mm, and the platinum-plated layer thickness is 5-10 μm.

[0010] In some embodiments of the present invention, the porous alumina ceramic sleeve and the double elliptical container are screwed together by threads, and the pore size of the porous alumina ceramic sleeve is 1-5 μm.

[0011] In some embodiments of the present invention, a liquid level gauge is also provided on the top of the double elliptical container.

[0012] In some embodiments of the present invention, both the liquid inlet pipe and the liquid outlet pipe are provided with controllable switch valves.

[0013] In some embodiments of the present invention, the double elliptical container is placed vertically, and the middle position of the double elliptical container is fixedly mounted on a stand.

[0014] In some embodiments of the present invention, the anode is electrically connected to a positive electrode of a power source, and the cathode is electrically connected to a negative electrode of a power source.

[0015] In a second aspect of the present invention, a method for using a device for electrocatalytic denitration in a hot chamber is provided, wherein a manipulator in the hot chamber performs the following operation steps:

[0016] Add high-concentration nitrate into the double elliptical container through the liquid inlet pipe, and the liquid level meter returns the reading in real time. When the liquid reaches the set height of the container, close the controllable switch valve and stop adding;

[0017] The porous alumina ceramic sleeve is screwed into the double oval container, the top exhaust pipe quick-plug connector is connected to the male connector, and the platinum-plated black anode is connected to the positive pole of the power supply;

[0018] The exhaust pipe on the top of the double oval container is connected to a quick-connect fitting, and the titanium metal rod on the side wall is connected to the negative electrode of the power supply; the other ends of the two exhaust pipes are connected to the oval reaction container through a quick-connect fitting;

[0019] Start the power supply and start the electrolysis reaction. During the process, the controllable switch valve on the bottom liquid outlet pipe is adjusted to sample and analyze the acidity. When the acidity reaches the acidity conditions required by the anion resin, cationic resin and leaching resin respectively, the power supply is turned off and the controllable switch valve is opened to collect the solution after the reaction.

[0020] One or more technical solutions of the present invention have the following beneficial effects:

[0021] (1) The device for electrocatalytic denitration in a hot chamber provided by the present invention is arranged in a hot chamber for producing actinium-225, and can adjust the acidity without adding a dilute nitric acid solution, and can meet the acidity conditions required by anion resins, cationic resins and leaching resins in the process of producing actinium-225, and will not cause an increase in the volume of the solution, and can avoid affecting the volume of the upper column liquid in the next step of radiochemical separation, thereby reducing the radioactivity concentration of the actinium-225 product and increasing the yield of the actinium-225 product.

[0022] (2) The device for electrocatalytic denitration in a hot chamber provided by the present invention uses titanium or platinum-plated titanium as cathode and anode materials, which are resistant to nitric acid corrosion, electrochemical corrosion at high potential values, and strong radioactive radiation. The use of the device and remote operations such as taking out or replacing electrodes can be quickly and easily operated using a manipulator.

[0023] (3) The device and method for electrocatalytic denitrification in a hot chamber provided by the present invention are developed and designed for the purpose of large-scale production of actinium-225 and to reduce the operation time for separation and purification of actinium-225. The device can maximize the production of actinium-225. The device can be easily operated, maintained, and quickly replaced by a robot, thereby reducing the time required for the separation and purification process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of the device for electrocatalytic denitration in a hot chamber of the present invention.

[0025] In the figure: 1. Test bench; 2. Titanium cathode metal rod; 3. Liquid inlet pipe; 4. Porous alumina ceramic sleeve; 5. Platinum-plated black anode; 6. Three-way joint; 7. Waste gas reaction container; 8. Exhaust pipe; 9. Double elliptical container; 10. Liquid outlet pipe; 11. First controllable switch valve; 12. Second controllable switch valve. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Example 1

[0028] In a typical embodiment of the present invention, a device for electrocatalytic denitration in a hot chamber is provided, such as Figure 1 As shown, it includes a double elliptical container 9 arranged in a hot chamber, an anode, an exhaust pipe and a liquid inlet pipe 3 are arranged on the top of the double elliptical container 9, a cathode is arranged on the side of the double elliptical container 9, and a liquid outlet pipe 10 is arranged at the bottom of the double elliptical container 9; wherein the anode adopts a platinum-plated black anode 5, the cathode adopts a titanium cathode metal rod 2, and a porous alumina ceramic sleeve 4 is arranged outside the anode to isolate the anode and the cathode; the double elliptical container 9 is filled with a high-concentration nitrate solution.

[0029] In this embodiment, a double elliptical container 9 is used as an electrolytic cell and is made of metal titanium. The double elliptical container 9 is placed vertically, and the middle position of the double elliptical container is fixedly mounted on the stand 1.

[0030] In this embodiment, the exhaust pipe 8 includes a first exhaust pipe and a second exhaust pipe. The first exhaust pipe is located in the porous alumina ceramic sleeve 4 and is used to discharge the exhaust gas generated during the anode reaction. The second exhaust pipe is located in the double elliptical container 9 and is used to discharge the exhaust gas in the electrolytic cell.

[0031] Furthermore, the first exhaust pipe and the second exhaust pipe are both connected to the three-way joint 6 through a quick-plug joint, the three-way joint 6 is connected to the exhaust gas reaction container 7, the exhaust gas reaction container 7 performs exhaust gas reaction, and the exhaust gas reaction container 7 is connected to the exhaust gas treatment device in the adjacent hot chamber through the gas pipeline in the hot chamber.

[0032] In a specific implementation of this embodiment, the exhaust gas reaction container 7 is an elliptical reaction container, in which the exhaust gas reaction is carried out: 2NO+O2=2NO2, and the nitrogen oxide exhaust gas after the reaction is transmitted through the gas pipeline in the hot chamber to the exhaust gas treatment device in the adjacent hot chamber for treatment of the nitrogen oxide exhaust gas.

[0033] In this embodiment, the platinum-plated black anode is a 50% hollow mesh, the electrode thickness is 1-2 mm, and the platinum-plated layer thickness is 5-10 μm. The hollow mesh structure can increase the anode reaction surface area, increase the contact surface area between the solution and the electrode, and improve the reaction rate and electrode efficiency. The platinum-plated layer thickness is 5-10 μm. Under this condition, the electrolysis efficiency is higher, and under high acid concentration, the oxidation of nitric acid causes less electrode loss.

[0034] When in use, the anode is electrically connected to the positive electrode of the power supply, and the cathode is electrically connected to the negative electrode of the power supply. Porous alumina ceramics are used to isolate the cathode and the anode, which can not only effectively isolate the cathode reaction and the anode reaction areas, but also realize the transfer of ions in the solution and promote the reaction.

[0035] Specifically, the reaction formula of the anode is:

[0036] 2H2O→4H + +O2+4e - .

[0037] The cathode reaction is:

[0038] NO3 - +4H + +3e - →NO+2H2O

[0039] NO3 - +2H + +e - →NO2+H2O

[0040] NO3 - +3H + +2e - →HNO2+H2O

[0041] In this electrochemical process, the cathode and anode materials are made of titanium or platinum-plated titanium, which are resistant to nitric acid corrosion, electrochemical corrosion at high potential values, and strong radioactive radiation. The denitrification of high-concentration nitrate solutions is achieved through the electrolysis process, and the concentration of the nitrate solution is changed to adjust the nitrate concentration. The concentration of the nitrate solution can be reduced from 8M to 4M within 2-3 hours without expanding the volume of the solution, providing the required acidity conditions for the ion resin, cationic resin and leaching resin processes.

[0042] In this embodiment, the porous alumina ceramic sleeve 4 and the double elliptical container 9 are screwed together by threads. The pore size of the porous alumina ceramic sleeve 4 is 1-5 μm, and the pore size can play a selective role in the transfer of ions.

[0043] In this embodiment, a liquid level meter is also provided on the top of the double elliptical container 9 for detecting the liquid level height in the double elliptical container in real time.

[0044] In this embodiment, the liquid inlet pipe is provided with a first controllable switch valve 11, which is closed during electrolysis to prevent gas from entering the container. The liquid outlet pipe is provided with a second controllable switch valve 12, which is used to control the outflow of the electrolyzed solution and collect it in a sample bottle.

[0045] The hot chamber is a shielded chamber for high-radioactivity testing and operation. To this end, after the electrocatalytic denitration device is placed in the hot chamber, it needs to be operated by an operator in the hot chamber. The thorium target is dissolved by high acid after accelerator target shooting. The solution is high-concentration nitric acid with high radioactivity. The electrocatalytic denitration device in the hot chamber of this embodiment is used to adjust the solubility of the nitrate solution. The specific operating steps are as follows:

[0046] High concentration nitrate is added into the double elliptical container through the liquid inlet pipe, the liquid level meter returns the reading in real time, and when the liquid reaches the set height of the container, the controllable switch valve is closed to stop adding; specifically, the set height is 2 / 3 of the height of the container.

[0047] The porous alumina ceramic sleeve is screwed into the double oval container, the top exhaust pipe quick-plug connector is connected to the male connector, and the platinum-plated black anode is connected to the positive pole of the power supply;

[0048] The exhaust pipe on the top of the double elliptical container is connected to a quick-plug connector, and the titanium metal rod on the side wall is connected to the negative pole of the power supply; the other ends of the two exhaust pipes are connected to the elliptical reaction container through a quick-plug connector.

[0049] Start the power supply to start the electrolysis reaction. During the electrolysis process, the controllable switch valve on the bottom liquid outlet pipe is adjusted to take samples for acidity analysis. The solution is adjusted to the column loading conditions before being loaded onto the resin column. It is added to the resin column through a syringe pump, the column loading speed is controlled, the effluent is collected, the acidity is adjusted, and the next resin column is loaded and unloaded using the same method.

[0050] The method of replacing the electrode by the manipulator in the hot chamber is that the manipulator controls the hexagonal metal opening at the bottom of the porous alumina ceramic sleeve, rotates the sleeve to take out, and replaces the new anode.

[0051] A specific size of the device for electrocatalytic denitrification in a hot chamber provided in this embodiment is that the thickness of the double elliptical container is 10 mm, the thickness of the platinum-plated black electrode is 2 mm, the thickness of the platinum-plated layer is 5 μm, the thickness of the external porous alumina ceramic sleeve is 5 mm, the diameter is 80 mm, the pore size is 3 μm, and the diameters of the liquid inlet pipe, exhaust pipe and liquid outlet pipe are all 10 mm.

[0052] Two specific application processes of the device for electrocatalytic denitration in the above-mentioned hot chamber are as follows:

[0053] 1. Add 500mL of 10M nitrate solution into the double elliptical container 9 through the liquid inlet pipe 3. After the addition is completed, close the first controllable switch valve 11. Connect the negative and positive electrodes of the power supply to the titanium cathode metal rod 2 and the platinum-plated black anode 5 respectively. Connect the other end of the exhaust pipe 8 to the exhaust gas reaction container 7 through a quick-plug connector to carry out a mixed reaction of nitrogen oxide exhaust gas and transfer it to the exhaust gas treatment equipment for treatment. Start the power supply and control the current density to 80mA / cm 2 Every 0.5 h, the second controllable switch valve 12 on the bottom liquid outlet pipe 10 is adjusted to take samples for acid-base titration analysis. After 3 h, the electrolyzed nitrate solution is collected and its acidity is measured to be 2.5M.

[0054] 2. Add 500mL of 10M nitrate solution into the double elliptical container 9 through the feed pipe 3. After the addition is completed, close the first controllable switch valve 11. Connect the negative and positive electrodes of the power supply to the titanium cathode metal rod 2 and the platinum-plated black anode 5 respectively. Connect the other end of the exhaust pipe 8 to the exhaust gas reaction container 7 through a quick-plug connector to carry out a mixed reaction of nitrogen oxide exhaust gas and transfer it to the exhaust gas treatment equipment for treatment. Start the power supply and control the current density to 50mA / cm 2 Every 0.5 h, the second controllable switch valve 12 on the bottom liquid outlet pipe 10 is adjusted to take samples for acid-base titration analysis. After 3 h, the electrolyzed nitrate solution is collected and its acidity is measured to be 4.5M.

[0055] From the above process, it can be seen that the current density will affect the denitrification rate of the nitrate solution. Therefore, the denitrification efficiency can be adjusted by changing the current density during use.

[0056] Example 2

[0057] In a typical embodiment of the present invention, a method for using a device for electrocatalytic denitration in a hot chamber is provided, wherein a manipulator in the hot chamber performs the following operation steps:

[0058] Add high-concentration nitrate into the double elliptical container through the liquid inlet pipe, and the liquid level meter returns the reading in real time. When the liquid reaches the set height of the container, close the controllable switch valve and stop adding;

[0059] The porous alumina ceramic sleeve is screwed into the double oval container, the top exhaust pipe quick-plug connector is connected to the male connector, and the platinum-plated black anode is connected to the positive pole of the power supply;

[0060] The exhaust pipe on the top of the double elliptical container is connected to a quick-plug connector, and the titanium metal rod on the side wall is connected to the negative pole of the power supply; the other ends of the two exhaust pipes are connected to the elliptical reaction container through a quick-plug connector.

[0061] Start the power supply to start the electrolysis reaction. During the electrolysis process, the controllable switch valve on the bottom liquid outlet pipe is adjusted to take samples for acidity analysis. The solution is adjusted to the column loading conditions before being loaded onto the resin column. It is added to the resin column through a syringe pump, the column loading speed is controlled, the effluent is collected, the acidity is adjusted, and the next resin column is loaded and unloaded using the same method.

[0062] The entire process can be easily operated, maintained, and quickly replaced by the robot, which can reduce the time required for the separation and purification process and improve the production efficiency of actinium-225.

[0063] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A device for electrocatalytic denitration in a hot chamber, characterized in that: It comprises a double elliptical container arranged in a hot chamber, wherein an anode, an exhaust pipe and a liquid inlet pipe are arranged on the top of the double elliptical container, a cathode is arranged on the side of the double elliptical container, and a liquid outlet pipe is arranged at the bottom of the double elliptical container; wherein the anode is a platinum-plated black anode, the cathode is a titanium cathode metal rod, and a porous alumina ceramic sleeve is arranged outside the anode to isolate the anode and the cathode; the double elliptical container is filled with a high-concentration nitrate solution.

2. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: The exhaust pipe comprises a first exhaust pipe and a second exhaust pipe, wherein the first exhaust pipe is located in the porous alumina ceramic sleeve, and the second exhaust pipe is located in the double elliptical container.

3. The device for electrocatalytic denitration in a hot chamber according to claim 2, characterized in that: The first exhaust pipe and the second exhaust pipe are both connected to the three-way joint through a quick-insert joint, the three-way joint is connected to the exhaust gas reaction container, the exhaust gas reaction container performs exhaust gas reaction, and the exhaust gas reaction container is connected to the exhaust gas treatment device in the adjacent hot chamber through the gas pipeline in the hot chamber.

4. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: The platinum-plated black anode is a 50% hollow mesh, the electrode thickness is 1-2 mm, and the platinum-plated layer thickness is 5-10 μm.

5. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: The porous alumina ceramic sleeve and the double elliptical container are screwed together by threads, and the pore size of the porous alumina ceramic sleeve is 1-5 μm.

6. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: A liquid level gauge is also provided on the top of the double elliptical container.

7. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: The liquid inlet pipe and the liquid outlet pipe are both provided with controllable switch valves.

8. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: The double elliptical container is placed vertically, and the middle position of the double elliptical container is fixedly installed on the stand.

9. The device for electrocatalytic denitration in a hot chamber according to claim 1, characterized in that: The anode is electrically connected to the positive electrode of the power supply, and the cathode is electrically connected to the negative electrode of the power supply.

10. A method for using the device for electrocatalytic denitration in a hot chamber according to any one of claims 1 to 9, characterized in that: The following steps are performed by the robot in the hot chamber: High-concentration nitrate is added into the double elliptical container through the liquid inlet pipe, and the liquid level meter returns the reading in real time. When the liquid reaches the set height of the container, the controllable switch valve is closed to stop adding; The porous alumina ceramic sleeve is screwed into the double oval container, the top exhaust pipe quick connector is connected to the male connector, and the platinum-plated black anode is connected to the positive pole of the power supply; The exhaust pipe on the top of the double oval container is connected to a quick-connect fitting, and the titanium metal rod on the side wall is connected to the negative electrode of the power supply; the other ends of the two exhaust pipes are connected to the oval reaction container through a quick-connect fitting; Start the power supply to start the electrolysis reaction. During the electrolysis process, the controllable switch valve on the bottom liquid outlet pipe is adjusted to take samples for acidity analysis. The solution is adjusted to the column loading conditions before being loaded onto the resin column. It is added to the resin column through a syringe pump, the column loading speed is controlled, the effluent is collected, the acidity is adjusted, and the next resin column is loaded and unloaded using the same method.

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