Method for replacing and regenerating adsorption bed containing radioactive waste gas

Abstract

The invention belongs to the technical field of nuclear power, and particularly relates to a method for replacing and regenerating an adsorption bed containing radioactive waste gas. According to the replacement and regeneration method for the adsorption bed containing the radioactive waste gas, the adsorption and purification performance of the adsorption bed containing the radioactive waste gas can be recovered in a carrier gas protection and heating regeneration mode, the method has good universality, the technological process is simple and convenient, the operation cost is low, safety is high, and the popularization and application prospects are wide; the cost reduction and efficiency improvement of the radioactive waste gas treatment process of the nuclear power plant are promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power, and in particular relates to a method for replacing and regenerating an adsorption bed containing radioactive waste gas. Background Art

[0002] Nuclear power plants, research reactors, fuel cycles and other nuclear facilities will produce radioactive waste gas during operation, especially radionuclides with a long half-life. Once uncontrolled emissions, they will lead to long-term radioactive pollution and pose a potential safety and health threat to the public and the environment. Therefore, scientific disposal is needed to ensure nuclear safety, personnel safety and environmental safety, and promote the sustainable development of my country's nuclear industry system.

[0003] Radioactive waste gas contains a variety of airborne radioactive pollutants, including xenon-133, krypton-85, iodine-131, iodine-129, C-14 and other radioactive nuclides in addition to radioactive aerosols. In addition to inert gases, some nuclides also exist in different chemical forms, such as iodine I 2 and CH 3 I. Carbon CO 2 and CH 4 At present, the mainstream method for the treatment of radioactive gas pollutants is adsorption, which mainly uses a large number of active sites inside porous materials to interact with radioactive gas molecules, and adsorbs, separates, retains and purifies them through effective selective adsorption.

[0004] First, porous materials have a certain adsorption capacity for target radioactive gases, and new adsorption beds need to be replaced after a period of use to ensure the adsorption and purification effect; secondly, different types of nuclides and different chemical forms also make radioactive pollutants exhibit different physical and chemical properties, and have different interaction strengths with porous materials. In order to reduce operating costs and reduce the amount of radioactive solid waste generated, materials need to be regenerated and reused. Generally, porous materials are loaded in adsorption beds to adsorb and purify radioactive waste gases. In view of the above practical needs, it is urgent to find a method system for replacing and regenerating adsorption beds. Summary of the invention

[0005] In order to overcome the problems existing in the related art, a method for replacing and regenerating an adsorption bed containing radioactive waste gas is provided.

[0006] According to one aspect of an embodiment of the present disclosure, a method for replacing and regenerating an adsorption bed containing radioactive waste gas is provided, the method comprising:

[0007] Step 1: When the radioactive gas penetrating downstream of the first adsorption bed reaches a preset concentration, the first adsorption bed is determined to be ineffective, and the gas path switches downstream and upstream of the first adsorption bed are closed successively;

[0008] Step 2, after step 1, opening the upstream and downstream gas path switches of the spare second adsorption bed, and starting the second adsorption bed to perform adsorption and purification of radioactive waste gas;

[0009] Step 3, after step 1, the first adsorption bed is removed from the gas line and transported to a storage plant;

[0010] Step 4, regenerating the failed first adsorption bed in the storage plant and storing the regenerated radioactive waste gas;

[0011] Step 5, after the first adsorption bed is regenerated, it is reinstalled into the gas circuit, and after the second adsorption bed fails, it starts to work, and the second adsorption bed is replaced and regenerated.

[0012] In a possible implementation, the first adsorption bed and the second adsorption bed are filled with any one or more materials selected from the group consisting of activated carbon, zeolite molecular sieve, silica gel, metal organic framework, and resin.

[0013] In a possible implementation, the outer shells of the first adsorption bed and the second adsorption bed are made of any one of stainless steel, fiberglass, and plexiglass, and have radiation protection function.

[0014] In a possible implementation, the first adsorption bed and the second adsorption bed adopt a one-in-use and one-in-standby working mode, and are connected to the main gas line by using a tee.

[0015] In a possible implementation, the first adsorption bed and the second adsorption bed are connected to a tee by using a self-locking quick connector, and an openable and closable valve is provided between the self-locking quick connector and the tee.

[0016] In a possible implementation, the transfer device in step 3 has radiation protection and leakage prevention functions.

[0017] In a possible implementation, the regeneration method in step 4 is heating regeneration under an inert gas carrier gas, the regeneration temperature is 40 to 200°C, the cross-sectional flow rate of the inert gas carrier is 0.01 to 0.5 m / s; the heating rate of the inert gas carrier is 1 to 20°C / min.

[0018] In a possible implementation, the inert gas carrier gas is any one or more of nitrogen, helium, and argon.

[0019] In a possible implementation, in step 4, the heating method is heating the inert gas carrier or heating the adsorption bed, or a combination thereof.

[0020] In a possible implementation, in step 4, the regeneration process takes 2 to 100 minutes, and radioactivity detection is required after the failed adsorption bed is regenerated to determine the regeneration level. The radioactive waste gas storage tank has radiation protection and leakage prevention functions.

[0021] The beneficial effects of the present disclosure are as follows: the present disclosure provides a method for replacing and regenerating an adsorption bed containing radioactive waste gas, which can restore the adsorption and purification performance of the radioactive waste gas adsorption bed by utilizing carrier gas protection and heating regeneration. The method has good universality, a simple and convenient process, low operating cost and high safety, and broad prospects for promotion and application, which will help reduce costs and increase efficiency in the radioactive waste gas treatment process of nuclear power plants. DETAILED DESCRIPTION

[0022] The present disclosure is further described in detail below in conjunction with specific embodiments.

[0023] Unless otherwise defined, the technical and scientific terms used in the present disclosure have the same meanings as those generally understood by those skilled in the art to which the present disclosure belongs; the terms used in the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure; the term "including" and any variations thereof in the present disclosure are intended to cover non-exclusive inclusions. Obviously, the embodiments described in the present disclosure are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative efforts are within the scope of protection of the present disclosure.

[0024] Reference to "embodiments" in this disclosure means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] The present disclosure provides a method for replacing and regenerating an adsorption bed containing radioactive waste gas to meet the actual needs of reducing operating costs and reducing the amount of solid waste in the existing technical system. The method of the present disclosure includes the following steps:

[0026] Step 1: When the radioactive gas penetrating downstream of the first adsorption bed reaches a preset concentration, the first adsorption bed is determined to be ineffective, and the downstream and upstream gas path switches of the first adsorption bed are closed in turn.

[0027] Step 2, after step 1, open the upstream and downstream gas path switches of the spare second adsorption bed, and start the second adsorption bed to perform adsorption and purification of radioactive waste gas.

[0028] Step 3, after step 1, the first adsorption bed is removed from the gas line and transported to a storage plant.

[0029] Step 2 and step 3 may be performed simultaneously or in sequence.

[0030] Step 4, regenerating the failed first adsorption bed in the storage plant and storing the regenerated radioactive waste gas.

[0031] Step 5, after the first adsorption bed is regenerated, it is reinstalled into the gas circuit, and after the second adsorption bed fails, it starts to work, and the second adsorption bed is replaced and regenerated.

[0032] In a possible implementation, the first adsorption bed and the second adsorption bed are filled with any one or more of activated carbon, zeolite molecular sieve, silica gel, metal organic framework, and resin. The present disclosure does not limit the type of filling material for the adsorption bed.

[0033] In a possible implementation, the outer shell material of the first adsorption bed and the second adsorption bed is any one of stainless steel, fiberglass, and plexiglass, and a certain radiation protection function is also taken into consideration.

[0034] In a possible implementation, the first adsorption bed and the second adsorption bed adopt a one-in-use and one-in-standby working mode, and are connected to the main gas line by using a tee.

[0035] In a possible implementation, the first adsorption bed and the second adsorption bed are connected to a tee by a self-locking quick connector, and an openable and closable valve is provided between the self-locking quick connector and the tee.

[0036] In a possible implementation, the transfer device in step 3 has radiation protection and leakage prevention functions.

[0037] In one possible implementation, the regeneration method in step 4 is heating regeneration under an inert gas carrier gas, and the regeneration temperature is 40 to 200°C, for example, 50°C, 80°C, 100°C, 150°C, 180°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 40 to 200°C.

[0038] In a possible implementation, the inert gas carrier gas is any one or more of nitrogen, helium, and argon. For example, the combination of inert gas carriers may include: a combination of nitrogen and helium, a combination of helium and argon, a combination of nitrogen, helium, and argon, etc.

[0039] In a possible implementation, the cross-sectional flow rate of the inert gas carrier is 0.01-0.5 m / s. The heating rate of the inert gas carrier is 1-20°C / min, but is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable, preferably 1-20°C / min.

[0040] In step 4, the heating method is one or a combination of heating the inert gas carrier or heating the adsorption bed.

[0041] In step 4, the regeneration process takes 2 to 100 minutes.

[0042] In step 4, after the failed adsorption bed is regenerated, radioactivity detection is required to determine the regeneration level.

[0043] In step 4, the radioactive waste gas storage tank has radiation protection and leakage prevention functions.

[0044] The present invention provides a method for replacing and regenerating an adsorption bed containing radioactive waste gas. By utilizing carrier gas protection and heating regeneration, the adsorption and purification performance of the radioactive waste gas adsorption bed can be restored. The method has good universality, a simple and convenient process, low operating cost and high safety, and broad prospects for promotion and application. It will help reduce costs and increase efficiency in the radioactive waste gas treatment process of nuclear power plants.

[0045] In an application example, the krypton-85 concentration downstream of the first adsorption bed filled with zeolite molecular sieve exceeds the set concentration (radioactivity) index, and after closing the downstream and upstream switches of the first adsorption bed, the processing gas path is connected to the second adsorption bed.

[0046] Open the self-locking quick connector upstream and downstream of the first adsorption bed, and use a device with radiation and leakage protection functions to transfer the failed first adsorption bed to the storage plant.

[0047] The failed first adsorption bed was heated and regenerated by heating the nitrogen gas flow using nitrogen as the carrier gas. The carrier gas flow rate was 0.05 m / s, the heating rate was 10°C / min, and the regeneration temperature was 100°C. During the regeneration process, the regeneration gas flow was collected. After 60 minutes of continuous regeneration, the radioactivity detection level of the first adsorption bed reached the regeneration requirement.

[0048] After the first adsorption bed is successfully regenerated, it is transferred and reconnected to the radioactive waste gas treatment gas path to serve as a backup adsorption bed for the second adsorption bed.

[0049] In another application example, the 14CH4 concentration downstream of the second adsorption bed filled with metal organic framework material exceeds the set concentration (radioactivity) index, and after closing the downstream and upstream switches of the second adsorption bed, the treatment gas path is connected to the first adsorption bed.

[0050] Open the self-locking quick connector on the downstream of the second adsorption bed, and use a device with radiation protection and leakage prevention functions to transfer the failed second adsorption bed to the storage plant.

[0051] Helium was used as carrier gas and the failed second adsorption bed was heated and regenerated by heating the nitrogen gas flow. The carrier gas flow rate was 0.15 m / s, the heating rate was 15 °C / min, and the regeneration temperature was 80 °C. During the regeneration process, the regeneration gas flow was collected. After 30 minutes of continuous regeneration, the radioactivity detection level of the second adsorption bed reached the regeneration requirement.

[0052] After the second adsorption bed is successfully regenerated, it is transferred and reconnected to the radioactive waste gas treatment gas path to serve as a backup adsorption bed for the first adsorption bed.

[0053] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for replacing and regenerating an adsorption bed containing radioactive waste gas, characterized in that: The method comprises: Step 1: When the radioactive gas penetrating downstream of the first adsorption bed reaches a preset concentration, the first adsorption bed is determined to be ineffective, and the gas path switches downstream and upstream of the first adsorption bed are closed successively; Step 2, after step 1, opening the upstream and downstream gas path switches of the spare second adsorption bed, and starting the second adsorption bed to perform adsorption and purification of radioactive waste gas; Step 3, after step 1, the first adsorption bed is removed from the gas line and transported to a storage plant; Step 4, regenerating the failed first adsorption bed in the storage plant and storing the regenerated radioactive waste gas; Step 5, after the first adsorption bed is regenerated, it is reinstalled into the gas circuit, and after the second adsorption bed fails, it starts to work, and the second adsorption bed is replaced and regenerated.

2. The method according to claim 1, characterized in that: The materials filled in the first adsorption bed and the second adsorption bed are any one or more of activated carbon, zeolite molecular sieve, silica gel, metal organic framework and resin.

3. The method according to claim 1, characterized in that The shells of the first adsorption bed and the second adsorption bed are made of any one of stainless steel, fiberglass and organic glass, and have radiation protection function.

4. The method according to claim 1, characterized in that The first adsorption bed and the second adsorption bed adopt a one-in-use and one-in-standby working mode, and are connected to the main gas circuit by a tee.

5. The method according to claim 1, characterized in that The first adsorption bed and the second adsorption bed are connected with a tee by a self-locking quick connector, and an openable and closable valve is arranged between the self-locking quick connector and the tee.

6. The method according to claim 1, characterized in that The transfer device in step 3 has radiation protection and leakage prevention functions.

7. The method according to claim 1, characterized in that The regeneration method in step 4 is heating regeneration under an inert gas carrier gas, the regeneration temperature is 40-200°C, the cross-sectional flow rate of the inert gas carrier is 0.01-0.5 m / s; the heating rate of the inert gas carrier is 1-20°C / min.

8. The method according to claim 1, characterized in that The inert gas carrier gas is any one or more of nitrogen, helium, and argon.

9. The method according to claim 1, characterized in that: In step 4, the heating method is one or a combination of heating the inert gas carrier or heating the adsorption bed.

10. The method according to claim 1, characterized in that In step 4, the regeneration process takes 2 to 100 minutes. After the failed adsorption bed is regenerated, radioactivity detection is required to determine the regeneration level. The radioactive waste gas storage tank has radiation protection and leakage prevention functions.