Device and method for treating and recycling radioactive CO2 gas in nuclear-grade waste combustion product

Abstract

The invention discloses a device and a method for treating and recycling radioactive CO2 gas in nuclear-grade waste combustion products. The device comprises a combustion unit, a combustion unit and a recycling unit, the filtering unit is connected with the combustion unit and used for filtering mixed gas containing radioactive CO2 generated in the nuclear-grade waste combustion process; the cooling unit is connected with the filtering unit; the purification unit is connected with the cooling unit; the trapping and regenerating unit is connected with the purifying unit; and the circulating unit is connected with the combustion unit and the trapping and regenerating unit. The device is simple in structure, the adsorption material is convenient to regenerate and replace, the device can be repeatedly used for a long time, CO2 can be selectively adsorbed from nuclear power plant mixed waste gas or other mixed gas, the development requirements of carbon emission control and carbon neutralization are met, environmental radiation pollution caused by nuclear power plant waste gas or other waste gas in the nature can be relieved, and the environmental pollution is reduced. Meanwhile, carbon isotope resources can be effectively recycled, the process is safe and controllable, and the risk of radioactive substance leakage is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field, and in particular relates to a device and method for disposing and recovering radioactive CO2 gas in nuclear waste combustion products. Background Art

[0002] Carbon dioxide (CO2) is a colorless and odorless gas at room temperature and pressure, and its aqueous solution has a slightly sour taste. It is also a common greenhouse gas, with a content of 0.03%-0.04% v / v in the air. There are three main isotopes of carbon, namely C-12, C-13 and C-14, with abundances of 98.89%, 1.108% and 1.2×10 -10 %, of which C-12 and C-13 are stable nuclides, and C-14 is a radioactive nuclide. C-14 is a long-lived radionuclide with a half-life of 5730 years. It is a pure weak β radioactive nuclide with a maximum β-ray energy of 0.156 MeV and an average energy of 0.0449 MeV. As a cosmic radionuclide, the concentration of radioactive C-14 in the atmosphere remained stable for a long time before the atmospheric nuclear weapon test. In nature, the total amount under equilibrium conditions is about 80 tons. The annual production of C-14 is about 9.8 kg, which is about 4.37×10 3 Ci. From the 1950s to the 1980s, nuclear weapons experiments significantly increased the concentration of C-14 in the environment, with a total of about 9.6×10 5Ci. With the rapid development of nuclear power in the 1970s, the contribution of nuclear power radioactive emissions has also increased significantly. Compared with pressurized water reactor nuclear power plants (0.22TBq / GWa) and boiling water reactor nuclear power plants (0.51TBq / GWa), the release of heavy water reactor nuclear power plants (1.6TBq / GWa) is relatively large. At the same time, graphite reactors also produce a large amount of C-14 during operation. In addition, C-14 is one of the important nuclides in the environmental impact assessment of heavy water reactor nuclear power plants. C-14 is produced by the reaction of fission seeds in nuclear power plants with nitrogen, hydrogen and oxygen in reactor materials. During the operation of the reactor, the produced C-14 is mainly discharged into the environment in the form of gas, most of which will be solidified and sealed by resin adsorption, while the other part of C-14 still exists in solid form, such as C-14 in graphite reactors. Although the C-14 emitted by nuclear power plants is much lower than the C-14 production in nature (1400TBq / year) and the C-14 produced by atmospheric nuclear tests, in the long run, the C-14 emitted by nuclear power plants may lead to an increase in the concentration of C-14 in the atmosphere. In addition, carbon is an important element of life, and radioactive C-14 can enter the biosphere through photosynthesis and then enter the human body through food. The C-14 in the human body is emitted at a rate of about 1-2 hours half-life. According to the literature, the gaseous release of C-14 from nuclear power plants is mainly discharged in the form of carbon dioxide, so the exhaust gas emissions from nuclear power plants need to be further processed and purified before they can be discharged into the surrounding environment. Carbon dioxide capture and storage (CCS) technology, one of the most important technologies for addressing global climate change in the short term, has its place here. In this technology, carbon dioxide is captured and stored in places isolated from the atmosphere such as the seabed or underground. In CCS technology, the methods of carbon dioxide capture are divided into physical and chemical methods, and molecular sieve capture is one of the physical methods.

[0003] Molecular sieve is a synthetic hydrated aluminosilicate with the function of screening molecules. It has many channels with uniform pores and holes for arranging steam in its structure. Molecular sieves with different pores separate molecules of different sizes and shapes. Therefore, the adsorption and separation function of molecular sieve depends on the size of its channels and pore volume. The adsorption of molecular sieve is a physical change process. The main reason is a kind of "surface force" generated by the molecular gravity acting on the solid surface. When the fluid flows through, some molecules of the fluid collide with the adsorbent surface due to irregular motion, resulting in molecular concentration on the surface, which reduces the number of such molecules in the fluid and achieves the purpose of separation and removal. Since adsorption does not cause chemical changes, as long as the molecules concentrated on the surface are driven away (heating), the molecular sieve will have adsorption capacity again. This process is the reverse process of adsorption, which is called analysis or regeneration. Since the molecular sieve has uniform pore size, it can easily enter the crystal cavity and be adsorbed only when the molecular kinetic diameter is smaller than the pore size of the molecular sieve. Therefore, the molecular sieve is like a sieve for gas and liquid molecules, and whether it is adsorbed depends on the size of the molecule. Since the molecular sieve has strong polarity in the crystal cavity, it can interact strongly with molecules containing polar groups on the molecular sieve surface, or induce polarizable molecules to polarize, thereby generating strong adsorption. The characteristic that polar or easily polarizable molecules are easily adsorbed by polar molecular sieves reflects another adsorption selectivity of molecular sieves.

[0004] At present, there are patents reporting the use of molecular sieves to adsorb ordinary CO2 molecules to achieve the purpose of gas purification or CO2 gas removal, such as patent number CN202410622629.3, patent name A method for removing water and carbon dioxide from a mixed gas, patent number CN202410237240.7, patent name A medical molecular sieve adsorption oxygen generator, patent number CN202410137106.X, patent name Electronic grade acetylene gas purification method, etc. However, since the CO2 in the combustion products of nuclear-grade waste is radioactive, unlike ordinary CO2, there are higher requirements for its treatment methods, process and equipment. The above patents are not suitable for recycling radioactive CO2. There is currently no reliable treatment method, nor a technical method for effectively recycling C-14 resources in radioactive CO2, and there is a large market gap. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide a device and method for disposing and recovering radioactive CO2 gas in nuclear waste combustion products.

[0006] In order to achieve the above purpose and the above technical effect, the technical solution adopted by the present invention is:

[0007] A device for treating and recovering radioactive CO2 gas in nuclear waste combustion products, comprising:

[0008] Combustion unit, used to burn nuclear grade waste;

[0009] A filter unit, connected to the combustion unit, is used to filter the mixed gas containing radioactive CO2 generated during the combustion of nuclear waste;

[0010] A cooling unit connected to the filtering unit;

[0011] a purification unit connected to the cooling unit;

[0012] A capture and regeneration unit connected to the purification unit;

[0013] The circulation unit is connected with the combustion unit and the capture and regeneration unit.

[0014] Furthermore, the combustion unit includes a combustion device, an air inlet end of the combustion device is connected to a buffer tank, the buffer tank is connected to an O2 cylinder, and an air outlet end of the combustion device is connected to a filter unit.

[0015] Furthermore, the O2 cylinder is connected to the buffer tank through a pressure reducing valve, an O2 input port solenoid valve, and a one-way valve and then connected to the combustion device.

[0016] Furthermore, a first temperature transmitter and a first pressure transmitter are provided at the gas outlet end of the combustion device.

[0017] Furthermore, the filtration unit includes a 75 μm filter and a 2 μm filter, and the 75 μm filter is connected to the 2 μm filter.

[0018] Furthermore, the cooling unit includes a condensing device, and a second temperature transmitter is provided on the condensing device.

[0019] Furthermore, the purification unit includes a purification device and a water removal column, and the purification device is connected to the water removal column.

[0020] Furthermore, the capture regeneration unit includes a capture column, the air inlet end of the capture column is provided with a second pressure transmitter, an upper solenoid valve of the capture column, and a desorption outlet solenoid valve, the air outlet end is provided with a third pressure transmitter and a lower solenoid valve of the capture column, and the second pressure transmitter is interlocked with the O2 input port solenoid valve.

[0021] Furthermore, the circulation unit includes a buffer tank, a gas circulation pump, and a CO2 analyzer. The gas circulation pump is provided on the pipeline between the buffer tank and the combustion device, and the CO2 analyzer 23 is provided on the pipeline between the buffer tank and the capture column.

[0022] The present invention also discloses a method for treating and recovering radioactive CO2 gas in nuclear waste combustion products, using the above-mentioned device for treating and recovering radioactive CO2 gas in nuclear waste combustion products to treat and recover radioactive CO2 gas in nuclear waste combustion products, and the method comprises the following steps:

[0023] Load the nuclear-grade waste to be burned into the combustion device, close the solenoid valve at the O2 input port and the solenoid valve at the desorption outlet, open the solenoid valve, the solenoid valve at the upper end of the capture column, and the solenoid valve at the lower end of the capture column, and close the interlock between the solenoid valve at the O2 input port and the second pressure transmitter. Use a vacuum pump to evacuate the device from the solenoid valve, then close the solenoid valve, open the pressure reducing valve and the solenoid valve at the O2 input port, and pass the O2 gas in the O2 cylinder until the pressure in the combustion device is 0kPa, then close the solenoid valve at the O2 input port, and repeat the above steps of evacuating and passing O2 gas several times to completely replace the gas in the device with O2 gas;

[0024] Turn on the gas circulation pump, open the interlock between the O2 input solenoid valve and the second pressure transmitter, and continue to input O2 gas into the combustion device. When the pressure in the combustion device reaches the maximum value of the interlock setting pressure, the O2 input solenoid valve is closed;

[0025] A combustion program of the combustion device is set, and then the combustion device is turned on to perform high-temperature combustion on the nuclear-grade waste to be burned. The combustion process generates a mixed gas containing radioactive CO2. After being filtered by the filtration unit, condensed by the condensation unit, and purified by the purification unit, the mixed gas components are CO2, O2, and CO. The mixed gas then enters the capture column, where the CO2 is captured by the adsorption material in the capture column, and the remaining gas continues to circulate into the combustion device through the gas circulation pump to participate in the reaction. After the combustion is completed, the CO2 capture process of the capture column is completed, the pressure reducing valve is closed, the O2 input port solenoid valve is closed, and the interlock between the second pressure transmitter is closed, the gas circulation pump is closed, and the O2 input port solenoid valve, the upper end solenoid valve of the capture column, and the lower end solenoid valve of the capture column are closed. At this point, the radioactive CO2 gas generated by the combustion of the nuclear-grade waste can be completely adsorbed in the adsorption material in the capture column;

[0026] When desorption is required, close the solenoid valve at the upper end of the capture column and the solenoid valve at the lower end of the capture column, connect the desorption outlet solenoid valve to the vacuum pump, turn on the vacuum pump, open the desorption outlet solenoid valve, evacuate the capture column, remove the small amount of impurity gas remaining in the column that has not been adsorbed, and then close the desorption outlet solenoid valve; connect the container for collecting the desorbed radioactive CO2 gas or the equipment that directly uses the analytical gas to the outlet port of the vacuum pump, turn on the heating device outside the capture column to start heating, open the desorption outlet solenoid valve, turn on the vacuum pump, and the desorbed radioactive CO2 gas is discharged through the desorption outlet solenoid valve and the vacuum pump until the desorption process is completed, then close the desorption outlet solenoid valve and remove the vacuum pump.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention discloses a device and method for disposing of and recovering radioactive CO2 gas in nuclear-grade waste combustion products. The device and method have a simple overall structure, and the adsorption material is easy to regenerate and replace and can be reused for a long time. The device and method can not only selectively adsorb CO2 from mixed waste gas from nuclear power plants or other mixed gases, but also realize the capture of radioactive CO2 gas in nuclear-grade waste combustion products and realize temporary storage and solid-state transportation, which meets the development requirements of carbon emission control and carbon neutrality, and can also reduce environmental radiation pollution caused by nuclear power plant waste gas or other waste gas in nature. At the same time, the device and method can recover CO2 by heating desorption, thereby realizing the resource utilization of radioactive CO2. The overall operation steps are simple, the process is safe and controllable, and there is no risk of leakage of radioactive substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0030] The present invention is described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0031] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0032] like Figure 1 As shown, the present invention discloses a device for treating and recovering radioactive CO2 gas in nuclear waste combustion products, comprising:

[0033] Combustion unit, used to burn nuclear grade waste;

[0034] A filter unit, connected to the combustion unit, is used to filter the mixed gas containing radioactive CO2 generated during the combustion of nuclear waste;

[0035] A cooling unit connected to the filtering unit;

[0036] a purification unit connected to the cooling unit;

[0037] A capture and regeneration unit connected to the purification unit;

[0038] The circulation unit is connected with the combustion unit and the capture and regeneration unit.

[0039] In the present invention, the combustion unit includes: an O2 cylinder 1, a pressure reducing valve 2, an O2 input port electromagnetic valve 3, a one-way valve 4, a combustion device 8, a first temperature transmitter 9, and a first pressure transmitter 10. The O2 cylinder 1 is connected to the buffer tank 5 through the pressure reducing valve 2, the O2 input port electromagnetic valve 3, and the one-way valve 4, the air inlet end of the combustion device 8 is connected to the buffer tank 5, and the air outlet end of the combustion device 8 is connected to the filter unit.

[0040] The combustion device 8 is used for burning nuclear waste, and can be a high-temperature tube furnace, or other forms of incinerators, heating furnaces, etc. The rear part of the gas outlet of the combustion device 8 is connected to the first temperature transmitter 9 and the first pressure transmitter 10 for monitoring the pressure and temperature of the combustion gas.

[0041] The filter unit includes: a 75μm filter 11 and a 2μm filter 12, wherein the 75μm filter 11 is connected to the 2μm filter 12. The rear of the first pressure transmitter 10 at the gas outlet of the combustion device 8 is connected to the 75μm filter 11 and the 2μm filter 12, which are used to filter dust particles and aerosol particles brought in by the airflow. The filter can be a ferrule metal filter, a filter mesh or other filtering devices for filtering tiny particles. The pore size and number of the filters can be changed according to the combustion conditions, and the number of filters can be increased or decreased.

[0042] The cooling unit comprises: a condensing device 13 , on which a second temperature transmitter 14 is arranged.

[0043] The purification unit comprises: a purification device 15 and a water removal column 16 , wherein the purification device 15 is connected to the water removal column 16 .

[0044] The capture regeneration unit includes a capture column 20, the air inlet end of the capture column 20 is provided with a second pressure transmitter 17, an upper end solenoid valve 18 of the capture column, and a desorption outlet solenoid valve 19, the air outlet end is provided with a third pressure transmitter 21 and a lower end solenoid valve 22 of the capture column, and the second pressure transmitter 17 is interlocked with the O2 input port solenoid valve 3.

[0045] The circulation unit includes a buffer tank 5, a gas circulation pump 7, and a CO2 analyzer 23. The buffer tank 5 is provided with a solenoid valve 6. The pipeline between the buffer tank 5 and the combustion device 8 is provided with a gas circulation pump 7. The pipeline between the buffer tank 5 and the capture column 20 is provided with a CO2 analyzer 23.

[0046] The O2 input port solenoid valve 3, solenoid valve 6, and desorption outlet solenoid valve 19 are set to be normally closed, and the upper end solenoid valve 18 of the capture column and the lower end solenoid valve 22 of the capture column are set to be normally open.

[0047] Nuclear-grade waste can be waste graphite containing C-14 from graphite reactors, waste resins adsorbed with C-14 from nuclear power reactors, or other combustible waste containing radioactive carbon isotopes.

[0048] The implementation process of the present invention is illustrated by taking the molecular sieve treatment and recovery of radioactive CO2 gas in nuclear-grade waste combustion products as an example. It can directly treat and recover the radioactive CO2 waste gas emitted by the nuclear power industry, and the usage logic is also applicable to other molecular sieve treatment and recovery processes of other corresponding gases.

[0049] The O2 input port solenoid valve 3 is interlocked with the second pressure transmitter 17. When the device pressure decreases after the capture column 20 captures CO2 gas, the corresponding solenoid valve opens to replenish O2. When O2 is replenished until the pressure is restored, the corresponding solenoid valve closes to stop O2 input. The pressure range of the interlock control is confirmed and adjusted according to the actual combustion consumption rate of O2 and the CO2 capture rate.

[0050] The gas circulation pump 7 is connected to the buffer tank 5 and the combustion device 8 to ensure that the gas circulates in the device system.

[0051] The filter unit is connected to the condensing device 13, which is used to cool the combustion gas. It can be a circulating water cooling system, or other condensers, cooling pipes, etc. used to cool high-temperature gas.

[0052] The condensing device 13 is connected to the purification device 15. The purification device 15 is independently and specially designed according to the impurity gas components that may be generated after the combustion of the combustibles, and is used to remove gases other than CO2, CO, O2, and H2O.

[0053] The water removal column 16 can be dehydrated by low temperature condensation or by loading water absorbing materials, etc. The water removal column 16 is loaded with water absorbing silica gel, water absorbing molecular sieve, polymer water absorbing materials, etc. The water removal column 16 can also be replaced by other forms of water removal equipment. The low temperature condensation is controlled at -30 to 25°C, preferably 0 to 10°C.

[0054] The water removal column 16 is connected to the capture column 20 through the electromagnetic valve 18 at the upper end of the capture column, and a second pressure transmitter 17 is connected between the two to monitor the pressure of this section and interlock with the electromagnetic valve 3 at the O2 input port.

[0055] The desorption outlet electromagnetic valve 19 is used to desorb CO2 gas and discharge it, and is connected to the CO2 analyzer 23, and the CO2 analyzer 23 is connected to the buffer tank 5 to form an overall loop.

[0056] The number of the capture columns 20 can be one or more, and they can be connected in series or in parallel. Each capture column can be switched in series and in parallel and disconnected by a solenoid valve group.

[0057] The capture column 20 can be used for adsorption by adsorbent materials or for CO2 capture by low temperature condensation. The low temperature condensation is generally controlled at a temperature of -150 to -78°C, preferably -80 to -100°C.

[0058] Taking molecular sieve as an example of the adsorption material, the desorption temperature is 200-400°C, preferably 300-350°C.

[0059] The adsorption material in the capture column 20 can be a material that can selectively adsorb CO2 gas, such as a solid molecular sieve, a surface-modified solid molecular sieve, a solid base, a metal framework material (MOFs), or the like.

[0060] Solid bases include inorganic bases and organic bases.

[0061] After the radioactive CO2 gas is captured by the capture column 20, it can be temporarily stored or transported in a solid form.

[0062] The capture column 20 is provided with a temperature control jacket or other types of heating devices, which can control the temperature of the capture column to achieve temperature control or desorption operation. By heating the capture column 20 at high temperature, the molecular sieve adsorbed with radioactive CO2 gas can be desorbed, CO2 is released for subsequent recovery, and the molecular sieve is regenerated at the same time.

[0063] The third pressure transmitter 21 is used to monitor the pressure inside the capture column during desorption.

[0064] The O2 input solenoid valve 3, the solenoid valve 6, the upper end solenoid valve 18 of the capturing column, the desorption outlet solenoid valve 19, the lower end solenoid valve 22 of the capturing column, the first temperature transmitter 9, the second temperature transmitter 14, the first pressure transmitter 10, the second pressure transmitter 17, the third pressure transmitter 21, and the CO2 analyzer 23 can be connected to the remote control system 24 for remote monitoring and control. The remote control system 24 can be a PLC, a DCS or other control systems.

[0065] The valves used in the present invention can be solenoid valves, pneumatic valves, pneumatic control elements and other valves that can be connected to the remote control system 24. If remote operation is not required, manual valves can also be used instead.

[0066] The working principle of the present invention is:

[0067] The nuclear-grade waste to be burned is loaded into the combustion device 8, the O2 input port solenoid valve 3 and the desorption outlet solenoid valve 19 are closed, the solenoid valve 6, the upper end solenoid valve 18 of the capture column, and the lower end solenoid valve 22 of the capture column are opened, the O2 input port solenoid valve 3 and the second pressure transmitter 17 are interlocked and closed, and the device is evacuated from the solenoid valve 6 using a vacuum pump, and then the solenoid valve 6 is closed, and the pressure reducing valve 2 and the O2 input port solenoid valve 3 are opened, and the O2 gas in the O2 cylinder 1 is introduced until the pressure in the combustion device 8 is 0kPa, and then the O2 input port solenoid valve 3 is closed, and the above-mentioned vacuuming and O2 gas introduction steps are repeated several times to completely replace the gas in the device with O2 gas;

[0068] Turn on the gas circulation pump 7, open the interlock between the O2 input port solenoid valve 3 and the second pressure transmitter 17, and continue to input O2 gas into the combustion device 8. After the pressure in the combustion device 8 reaches the maximum value of the interlock setting pressure, the O2 input port solenoid valve 3 is closed;

[0069] The combustion program of the combustion device 8 is set, including the combustion temperature, time and heating rate, etc., and then the combustion device 8 is turned on to perform high-temperature combustion on the nuclear-grade waste to be burned. The combustion process produces a mixed gas containing radioactive CO2. The mixed gas is filtered by the filtering unit (75μm filter 11, 2μm filter 12), condensed by the condensing equipment 13, and purified by the purification unit (purification equipment 15, dehydration column 16) in sequence. The mixed gas components are CO2, O2 and CO, and then enters the capture column 20, where the CO2 is captured by the adsorption material in the capture column 20, and the remaining gas continues to circulate through the gas circulation pump 7 to enter the combustion device 8 to participate in the reaction. After the combustion is completed, the CO2 capture process of the capture column 20 is completed, the pressure reducing valve 2 is closed, the O2 input port solenoid valve 3 is closed, and the interlock between the second pressure transmitter 17 is closed, the gas circulation pump 7 is closed, the O2 input port solenoid valve 3, the capture column upper end solenoid valve 18, and the capture column lower end solenoid valve 22 are closed. At this point, the radioactive CO2 gas generated by the combustion of nuclear waste can be completely adsorbed in the adsorption material in the capture column 20, and can be stored or transported in solid form later;

[0070] When desorption is required, close the electromagnetic valve 18 at the upper end of the capture column and the electromagnetic valve 22 at the lower end of the capture column, connect the desorption gas outlet electromagnetic valve 19 to the vacuum pump, turn on the vacuum pump, open the desorption gas outlet electromagnetic valve 19, evacuate the capture column 20, remove the small amount of impurity gas remaining in the column that has not been adsorbed, and then close the desorption gas outlet electromagnetic valve 19; connect the container for collecting the desorbed radioactive CO2 gas or the equipment that directly uses the analytical gas to the gas outlet port of the vacuum pump, turn on the heating device outside the capture column 20 to start heating, open the desorption gas outlet electromagnetic valve 19, turn on the vacuum pump, and the desorbed radioactive CO2 gas is discharged through the desorption gas outlet electromagnetic valve 19 and the vacuum pump until the desorption process is completed, then close the desorption gas outlet electromagnetic valve 19 and remove the vacuum pump;

[0071] During operation, the capture column 20 can be switched according to the capture saturation degree of the capture column 20. When the capture column 20 is saturated, the capture column 20 of this level is disconnected from the device, and the capture column 20 of this level can be desorbed through the temperature control jacket outside the capture column 20. After the desorption operation, the capture column 20 of this level is regenerated and can be connected to the device for operation again.

[0072] Example 1

[0073] Non-radioactive simulation experiments were conducted using ordinary graphite as a substitute for nuclear-grade waste.

[0074] The combustion device 8 uses a single temperature zone tubular furnace, the condensing device 13 uses a -10°C condenser, and the purification device 15 uses a purification column filled with porous balls of Na2CO3 as a removal device for chlorine-containing gas that may be generated during graphite combustion.

[0075] The dewatering column 16 is filled with about 300 g of 3A water-absorbing molecular sieve, and the trapping column 20 is filled with 600 g of 13X molecular sieve.

[0076] 1) Weigh 20 g of ordinary graphite and place it in a tubular furnace;

[0077] 2) The O2 input port solenoid valve 3 and the desorption outlet solenoid valve 19 are closed, the solenoid valve 6, the upper end solenoid valve 18 of the capture column, and the lower end solenoid valve 22 of the capture column are opened, the O2 input port solenoid valve 3 and the second pressure transmitter 17 are interlocked and closed, and the device is evacuated from the solenoid valve 6 using a vacuum pump, and then the solenoid valve 6 is closed, and the pressure reducing valve 2 and the O2 input port solenoid valve 3 are opened, and the O2 gas in the O2 cylinder 1 is introduced until the pressure in the tubular furnace is 0 kPa, and then the O2 input port solenoid valve 3 is closed, and the above vacuuming and O2 gas introduction steps are repeated twice to completely replace the gas in the device with O2 gas;

[0078] Turn on the gas circulation pump 7, open the interlock between the O2 input port electromagnetic valve 3 and the second pressure transmitter 17 (the interlocking control pressure range is -2 to 2 kPa), and continue to input O2 gas into the tubular furnace. After the pressure in the tubular furnace reaches 2 kPa, the O2 input port electromagnetic valve 3 is closed;

[0079] The combustion program of the tubular furnace 8 is set as follows: the combustion temperature is 860°C, the combustion time is 1.5h, and the heating rate is 10°C / min. The tubular furnace is turned on to perform high-temperature combustion on ordinary graphite. A mixed gas containing radioactive CO2 is generated during the combustion process. The mixed gas is filtered by the filtering unit (75μm filter 11, 2μm filter 12), condensed by the condensing equipment 13, and purified by the purification unit (purification equipment 15, dehydration column 16) in sequence. The combustion gas components are CO2, O2 and CO. The gas enters the capture column 20, where the CO2 is captured by the 13X molecular sieve, and the remaining gas continues to circulate through the gas circulation pump 7 to enter the tubular furnace 8 to participate in the reaction; after the combustion is completed, the CO2 capture process of the capture column 20 is completed, the pressure reducing valve 2 is closed, the interlock between the O2 input solenoid valve 3 and the second pressure transmitter 17 is closed, the gas circulation pump 7 is closed, the O2 input solenoid valve 3, the upper end solenoid valve 18 of the capture column, and the lower end solenoid valve 22 of the capture column are closed. At this point, the radioactive CO2 gas generated by the combustion of nuclear waste can be completely adsorbed in the adsorption material in the capture column 20, and can be stored or transported in solid form later;

[0080] When desorption is required, close the electromagnetic valve 18 at the upper end of the capture column and the electromagnetic valve 22 at the lower end of the capture column, connect the desorption gas outlet electromagnetic valve 19 to the vacuum pump, turn on the vacuum pump, open the desorption gas outlet electromagnetic valve 19, evacuate the capture column 20, remove the small amount of impurity gas remaining in the column that has not been adsorbed, and then close the desorption gas outlet electromagnetic valve 19; connect the gas outlet port of the vacuum pump to an air bag for collecting the desorbed gas, turn on the external temperature control jacket of the capture column 20 to start heating, set the heating temperature to 350°C, open the desorption gas outlet electromagnetic valve 19, turn on the vacuum pump to evacuate the gas bag, and the desorbed radioactive CO2 gas is discharged through the desorption gas outlet electromagnetic valve 19 and the vacuum pump until the desorption process is completed, close the desorption gas outlet electromagnetic valve 19, and remove the vacuum pump;

[0081] During operation, the capture column 20 can be switched according to the capture saturation degree of the capture column 20. When the capture column 20 is saturated, the capture column 20 of this level is disconnected from the device, and the capture column 20 of this level can be desorbed through the temperature control jacket outside the capture column 20. After the desorption operation, the capture column 20 of this level is regenerated and can be connected to the device for operation again.

[0082] After testing, the volume of gas in the airbag was 41.6L, of which the CO2 content was 99.97%.

[0083] Example 2

[0084] Nuclear-grade waste uses radioactive waste graphite containing C-14 from graphite reactors.

[0085] The combustion device 8 uses a single-temperature zone tubular furnace, the condensing device 13 uses a circulating water cooling device, and the purification device 15 uses a purification column filled with porous balls of Na2CO3 as a removal device for chlorine-containing gas that may be generated during graphite combustion.

[0086] The dewatering column 16 is filled with about 300 g of 3A molecular sieve, and the trapping column 20 is filled with 1000 g of 13X molecular sieve.

[0087] 1) Weigh 25 g of radioactive waste graphite and place it in a tube furnace;

[0088] 2) The O2 input port solenoid valve 3 and the desorption outlet solenoid valve 19 are closed, the solenoid valve 6, the upper end solenoid valve 18 of the capture column, and the lower end solenoid valve 22 of the capture column are opened, the O2 input port solenoid valve 3 and the second pressure transmitter 17 are interlocked and closed, and the device is evacuated from the solenoid valve 6 using a vacuum pump, and then the solenoid valve 6 is closed, and the pressure reducing valve 2 and the O2 input port solenoid valve 3 are opened, and the O2 gas in the O2 cylinder 1 is introduced until the pressure in the tubular furnace is 0 kPa, and then the O2 input port solenoid valve 3 is closed, and the above vacuuming and O2 gas introduction steps are repeated twice to completely replace the gas in the device with O2 gas;

[0089] Turn on the gas circulation pump 7, open the interlock between the O2 input port solenoid valve 3 and the second pressure transmitter 17 (the interlocking control pressure range is -2 to 2 kPa), and continue to input O2 gas into the tubular furnace. After the pressure in the tubular furnace reaches 5 kPa, the O2 input port solenoid valve 3 is closed;

[0090] The combustion program of the tubular furnace 8 is set as follows: the combustion temperature is 900°C, the combustion time is 2h, and the heating rate is 10°C / min. The tubular furnace is turned on to burn ordinary graphite at high temperature. The combustion process produces a mixed gas containing radioactive CO2. The mixed gas is filtered by the filtering unit (75μm filter 11, 2μm filter 12), condensed by the condensing device 13, and purified by the purification unit (purification device 15, water removal column 16). The combustion gas composition is CO2 (containing 14C-CO2), O2 and CO, the gas enters the capture column 20, the CO2 in it is captured by the 13X molecular sieve, and the remaining gas continues to circulate through the gas circulation pump 7 and enters the tubular furnace 8 to participate in the reaction; after the combustion is completed, the capture column 20 ends the CO2 capture process, closes the pressure reducing valve 2, closes the O2 input port solenoid valve 3, closes the interlock between the second pressure transmitter 17, closes the gas circulation pump 7, closes the O2 input port solenoid valve 3, the capture column upper end solenoid valve 18, and the capture column lower end solenoid valve 22. At this point, the radioactive CO2 gas generated by the combustion of nuclear-grade waste can be completely adsorbed in the adsorption material in the capture column 20, and can be stored or transported in solid form later;

[0091] When desorption is required, close the solenoid valve 18 at the upper end of the capture column and the solenoid valve 22 at the lower end of the capture column, connect the desorption outlet solenoid valve 19 to the vacuum pump, turn on the vacuum pump, open the desorption outlet solenoid valve 19, evacuate the capture column 20, remove the small amount of impurity gas remaining in the column that has not been adsorbed, and then close the desorption outlet solenoid valve 19; connect the vacuum pump outlet port to an air bag for collecting desorbed gas, turn on the external temperature control jacket of the capture column 20 to start heating, set the heating temperature to 350°C, open the desorption outlet solenoid valve 19, turn on the vacuum pump to evacuate the air bag, and the desorbed radioactive CO2 gas is discharged through the desorption outlet solenoid valve 19 and the vacuum pump until the desorption process is completed, close the desorption outlet solenoid valve 19, and remove the vacuum pump.

[0092] After testing, the volume of gas in the airbag was 52.7L, of which the CO2 content was 99.95%.

[0093] Example 3

[0094] Nuclear-grade waste uses radioactive waste graphite containing C-14 from graphite reactors.

[0095] The combustion device 8 uses a single-temperature zone tubular furnace, the condensing device 13 uses a circulating water cooling device, and the purification device 15 uses a purification column filled with porous balls of Na2CO3 as a removal device for chlorine-containing gas that may be generated during graphite combustion.

[0096] The dewatering column 16 is filled with about 600 g of 3A molecular sieve, and the trapping column 20 is filled with 3000 g of 13X molecular sieve.

[0097] 1) Weigh 80 g of radioactive waste graphite and place it in a tube furnace;

[0098] 2) The O2 input port solenoid valve 3 and the desorption outlet solenoid valve 19 are closed, the solenoid valve 6, the upper end solenoid valve 18 of the capture column, and the lower end solenoid valve 22 of the capture column are opened, the O2 input port solenoid valve 3 and the second pressure transmitter 17 are interlocked and closed, and the device is evacuated from the solenoid valve 6 using a vacuum pump, and then the solenoid valve 6 is closed, and the pressure reducing valve 2 and the O2 input port solenoid valve 3 are opened, and the O2 gas in the O2 cylinder 1 is introduced until the pressure in the tubular furnace is 0 kPa, and then the O2 input port solenoid valve 3 is closed, and the above vacuuming and O2 gas introduction steps are repeated twice to completely replace the gas in the device with O2 gas;

[0099] Turn on the gas circulation pump 7, open the interlock between the O2 input port solenoid valve 3 and the second pressure transmitter 17 (the interlocking control pressure range is -1.5 to 6 kPa), and continue to input O2 gas into the tubular furnace. After the pressure in the tubular furnace reaches 6 kPa, the O2 input port solenoid valve 3 is closed;

[0100] The combustion program of the tubular furnace 8 is set as follows: the combustion temperature is 1000°C, the combustion time is 4.5h, and the heating rate is 10°C / min. The tubular furnace is turned on to burn ordinary graphite at high temperature. The combustion process produces a mixed gas containing radioactive CO2. The mixed gas is filtered by the filtering unit (75μm filter 11, 2μm filter 12), condensed by the condensing device 13, and purified by the purification unit (purification device 15, water removal column 16). The combustion gas composition is CO2 (containing 14 C-CO2), O2 and CO, the gas enters the capture column 20, the CO2 in it is captured by the 13X molecular sieve, and the remaining gas continues to circulate through the gas circulation pump 7 and enters the tubular furnace 8 to participate in the reaction; after the combustion is completed, the capture column 20 ends the CO2 capture process, closes the pressure reducing valve 2, closes the O2 input port solenoid valve 3, closes the interlock between the second pressure transmitter 17, closes the gas circulation pump 7, closes the O2 input port solenoid valve 3, the capture column upper end solenoid valve 18, and the capture column lower end solenoid valve 22. At this point, the radioactive CO2 gas generated by the combustion of nuclear-grade waste can be completely adsorbed in the adsorption material in the capture column 20, and can be stored or transported in solid form later;

[0101] When desorption is required, close the solenoid valve 18 at the upper end of the capture column and the solenoid valve 22 at the lower end of the capture column, connect the desorption outlet solenoid valve 19 to the vacuum pump, turn on the vacuum pump, open the desorption outlet solenoid valve 19, evacuate the capture column 20, remove the small amount of impurity gas remaining in the column that has not been adsorbed, and then close the desorption outlet solenoid valve 19; connect the vacuum pump outlet port to an air bag for collecting desorbed gas, turn on the external temperature control jacket of the capture column 20 to start heating, set the heating temperature to 350°C, open the desorption outlet solenoid valve 19, turn on the vacuum pump to evacuate the air bag, and the desorbed radioactive CO2 gas is discharged through the desorption outlet solenoid valve 19 and the vacuum pump until the desorption process is completed, close the desorption outlet solenoid valve 19, and remove the vacuum pump.

[0102] 12) After testing, the volume of gas in the airbag was 167.3L, of which the CO2 content was 99.98%.

[0103] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0104] 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 specification, 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 device for treating and recovering radioactive CO2 gas in nuclear waste combustion products, characterized in that: include: Combustion unit, used to burn nuclear grade waste; A filter unit, connected to the combustion unit, is used to filter the mixed gas containing radioactive CO2 generated during the combustion of nuclear waste; A cooling unit connected to the filtering unit; a purification unit connected to the cooling unit; A capture and regeneration unit connected to the purification unit; The circulation unit is connected with the combustion unit and the capture and regeneration unit.

2. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 1, characterized in that: The combustion unit comprises a combustion device, an air inlet end of the combustion device is connected to a buffer tank, the buffer tank is connected to an O2 cylinder, and an air outlet end of the combustion device is connected to a filter unit.

3. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 2, characterized in that: The O2 cylinder is connected to the buffer tank through a pressure reducing valve, an O2 input port electromagnetic valve, and a one-way valve and then connected to the combustion device.

4. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 2, characterized in that: The gas outlet end of the combustion device is provided with a first temperature transmitter and a first pressure transmitter.

5. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 1, characterized in that: The filtration unit includes a 75 μm filter and a 2 μm filter, and the 75 μm filter is connected to the 2 μm filter.

6. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 1, characterized in that: The cooling unit comprises a condensing device, and a second temperature transmitter is arranged on the condensing device.

7. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 1, characterized in that: The purification unit comprises a purification device and a water removal column, and the purification device is connected to the water removal column.

8. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 1, characterized in that: The capture regeneration unit includes a capture column, the air inlet end of the capture column is provided with a second pressure transmitter, an upper electromagnetic valve of the capture column, and a desorption outlet electromagnetic valve, the air outlet end is provided with a third pressure transmitter and a lower electromagnetic valve of the capture column, and the second pressure transmitter is interlocked with the O2 input electromagnetic valve.

9. The device for treating and recovering radioactive CO2 gas in nuclear waste combustion products according to claim 1, characterized in that: The circulation unit comprises a buffer tank, a gas circulation pump, and a CO2 analyzer. A gas circulation pump is provided on the pipeline between the buffer tank and the combustion device, and a CO2 analyzer 23 is provided on the pipeline between the buffer tank and the capture column.

10. A method for disposing and recovering radioactive CO2 gas in nuclear waste combustion products, characterized in that: The radioactive CO2 gas in the nuclear waste combustion products is disposed and recovered by using a device for disposing and recovering the radioactive CO2 gas in the nuclear waste combustion products as described in any one of claims 1 to 9, and the method comprises the following steps: Load the nuclear-grade waste to be burned into the combustion device, close the solenoid valve at the O2 input port and the solenoid valve at the desorption outlet, open the solenoid valve, the solenoid valve at the upper end of the capture column, and the solenoid valve at the lower end of the capture column, and close the interlock between the solenoid valve at the O2 input port and the second pressure transmitter. Use a vacuum pump to evacuate the device from the solenoid valve, then close the solenoid valve, open the pressure reducing valve and the solenoid valve at the O2 input port, and pass the O2 gas in the O2 cylinder until the pressure in the combustion device is 0kPa, then close the solenoid valve at the O2 input port, and repeat the above steps of evacuating and passing O2 gas several times to completely replace the gas in the device with O2 gas; Turn on the gas circulation pump, open the interlock between the O2 input solenoid valve and the second pressure transmitter, and continue to input O2 gas into the combustion device. When the pressure in the combustion device reaches the maximum value of the interlock setting pressure, the O2 input solenoid valve is closed; A combustion program of the combustion device is set, and then the combustion device is turned on to perform high-temperature combustion on the nuclear-grade waste to be burned. The combustion process generates a mixed gas containing radioactive CO2. After being filtered by the filtration unit, condensed by the condensation unit, and purified by the purification unit, the mixed gas components are CO2, O2, and CO. The mixed gas then enters the capture column, where the CO2 is captured by the adsorption material in the capture column, and the remaining gas continues to circulate into the combustion device through the gas circulation pump to participate in the reaction. After the combustion is completed, the CO2 capture process of the capture column is completed, the pressure reducing valve is closed, the O2 input port solenoid valve is closed, and the interlock between the second pressure transmitter is closed, the gas circulation pump is closed, and the O2 input port solenoid valve, the upper end solenoid valve of the capture column, and the lower end solenoid valve of the capture column are closed. At this point, the radioactive CO2 gas generated by the combustion of the nuclear-grade waste can be completely adsorbed in the adsorption material in the capture column; When desorption is required, close the solenoid valve at the upper end of the capture column and the solenoid valve at the lower end of the capture column, connect the desorption outlet solenoid valve to the vacuum pump, turn on the vacuum pump, open the desorption outlet solenoid valve, evacuate the capture column, remove the small amount of impurity gas remaining in the column that has not been adsorbed, and then close the desorption outlet solenoid valve; connect the container for collecting the desorbed radioactive CO2 gas or the equipment that directly uses the analytical gas to the outlet port of the vacuum pump, turn on the heating device outside the capture column to start heating, open the desorption outlet solenoid valve, turn on the vacuum pump, and the desorbed radioactive CO2 gas is discharged through the desorption outlet solenoid valve and the vacuum pump until the desorption process is completed, then close the desorption outlet solenoid valve and remove the vacuum pump.

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