Device and method for purifying radioactive inert gas in local space

Abstract

The invention relates to a device and a method for purifying radioactive inert gas in local space, the device comprises a plurality of groups of adsorption beds, each adsorption bed is internally provided with a coil pipe for a cold source or a heat source to flow so as to control the temperature of the adsorption bed, and the periphery of the coil pipe is filled with an adsorption medium to detain the inert gas; the retention bed is arranged on one side of the exhaust port of the equipment and is used for secondarily adsorbing and recycling the radioactive inert gas separated out from the adsorption bed in the reverse desorption process; the cold water tank and the compressor are used for providing a low-temperature environment and a high-pressure environment for the adsorption bed in the forward adsorption process, providing a working environment for the adsorption bed and promoting adsorption and recovery of inert gas in the to-be-purified gas; the hot water tank and the vacuum pump are used for providing a temperature environment and an airflow environment for the adsorption bed in the reverse desorption process; and automatic control: controlling a plurality of groups of adsorption beds to alternately perform forward adsorption and desorption, and circulating. The device has the advantages of being high in treatment efficiency, small in occupied area and suitable for large-flow radioactive waste gas treatment.

Description

Technical Field

[0001] This invention relates to the field of radioactive inert gas purification, specifically to an apparatus and method for purifying radioactive inert gases in a local space. Background Technology

[0002] Nuclear facilities generate a certain amount of radioactive inert gases during operation. Most of these gases are purified by a dedicated radioactive waste gas treatment system through a condensate venting system to ensure that the gas emissions from the nuclear facility meet environmental and national standards. During this process, a small amount of radioactive gas may enter the air of the relevant system buildings due to system leaks or other reasons, affecting the health of staff and potentially impacting the normal operation of the nuclear facility. In the event of an accident, a large amount of radioactive inert gas is released into the reactor building. To ensure air cleanliness in critical areas such as the main control room and to guarantee the habitability of personnel, it is necessary to develop a device for the rapid and continuous purification of radioactive inert gases in localized spaces.

[0003] Currently, the main technologies for treating radioactive inert gases in nuclear facilities are compression storage and activated carbon retention. However, both of these technologies have certain limitations. Compression storage is complex and requires a large amount of equipment. Activated carbon retention at room temperature and pressure has a small processing capacity and is generally used for purifying small-flow process waste gases. Low-temperature activated carbon retention requires a complex low-temperature system to ensure the effectiveness of the process and is not suitable for the continuous and rapid purification of radioactive inert gases in local spaces.

[0004] Activated carbon temperature / pressure swing adsorption (TSA) technology utilizes the differences in adsorption capacity of various components in a mixed gas at different temperatures and pressures to achieve gas component separation. Under high pressure, readily adsorbed substances are adsorbed onto the surface of activated carbon; under low pressure, these substances are desorbed, thus regenerating the adsorbent. Continuous gas separation can be achieved using a multi-tower TSA unit. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides an apparatus and method for purifying radioactive inert gases in a local space, aiming to partially solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, a device for purifying radioactive inert gases in a local space is proposed, comprising: Multiple adsorption beds are provided, each group consisting of two or more adsorption beds. Each adsorption bed is equipped with a coil for the flow of a cold or heat source to control the temperature of the adsorption bed. The coil is filled with an adsorption medium to retain inert gas. The inlet and outlet of the adsorption bed are both connected by flanges. Gas monitoring sensors are installed upstream and downstream of each adsorption bed. The retention bed is located on one side of the equipment exhaust port and is used for secondary adsorption to recover the radioactive inert gas released from the adsorption bed during the reverse desorption process. The cold water tank and compressor are used to provide a low-temperature and high-pressure environment for the adsorption bed during the forward adsorption process, and to provide a working airflow environment of -2 to 5°C and 0.3 to 0.8 MPa for the adsorption bed, so as to promote the adsorption and recovery of inert gases in the gas to be purified. A hot water tank and a vacuum pump are used to provide a temperature environment greater than 45°C and an airflow environment less than 0.1 MPa for the adsorption bed during the reverse desorption process. The automatic control system includes multiple solenoid valves and multiple functional sensors installed in the circuit of the device, which automatically switch the opening and closing states of the solenoid valves based on sensor data; wherein, the automatic control includes controlling multiple adsorption beds to alternately perform forward adsorption and desorption, in a continuous cycle.

[0007] As a preferred technical solution, the number of adsorption beds is set to: n > t a / t e , where t a The total time required for a single adsorption bed to complete one reverse desorption process; t e The total time required for a single adsorption bed to complete one forward adsorption process, where n is an integer greater than or equal to 2.

[0008] As a preferred technical solution, it also includes a gas-water separator and a first drying bed. The gas-water separator is located after the compressor, and the first drying bed is located after the gas-water separator to control the humidity of the gas entering the adsorption bed to be less than 15%.

[0009] As a preferred technical solution, the bottom of the adsorption bed is provided with an activated carbon outlet.

[0010] As a preferred technical solution, an inert gas monitor is installed at the outlet end of the retention bed.

[0011] As a preferred technical solution, flow meters are installed upstream and downstream of the adsorption bed to control the airflow velocity passing through the adsorption bed during the adsorption or desorption process.

[0012] As a preferred technical solution, during the reverse desorption process, the temperature of the desorption gas stream is greater than 45℃ and the working environment pressure is less than 0.1MPa.

[0013] As a preferred technical solution, the system also includes a gas storage tank and a second drying bed. The gas storage tank is located at the inlet end of the equipment circuit, and the second drying bed is connected to the outlet end of the gas storage tank.

[0014] On the other hand, a method for purifying radioactive inert gases in a local space is proposed, utilizing the device for purifying radioactive inert gases in a local space as described above. The specific method of using the device includes: Start the compressor. The radioactive gas flow is transformed into high-pressure gas by the compressor. After passing through the steam-water separator and the first drying bed, the water vapor is removed. Control the valve to make the radioactive gas flow only through adsorption bed A in the first group of adsorption beds. At the same time, start the cold water tank and adsorption bed A begins to perform forward adsorption. Calculate the detection data of the upstream and downstream gas sensors of adsorption bed A. When the downstream data reaches 5% to 10% of the upstream data, control the valve to switch so that the radioactive gas flow passes through adsorption bed C in the second group of adsorption beds. Control the cold water tank to start supplying refrigerant to adsorption bed C, and adsorption bed C starts to work in the forward adsorption. Switch the control valve, turn on the vacuum pump and hot water tank to connect to adsorption bed A, adsorption bed A performs a reverse desorption process, and the gas is discharged to the outside after secondary adsorption through the retention bed; After adsorption bed C completes adsorption, it undergoes a desorption process similar to that of adsorption bed A. At this time, adsorption bed B in the first group of adsorption beds is controlled to start the adsorption process. After adsorption bed A completes desorption, adsorption bed C begins desorption. Multiple adsorption beds alternately perform forward adsorption and desorption in a continuous cycle.

[0015] As a preferred technical solution, the reverse desorption process is completed before the next forward adsorption of a single activated carbon bed, and the temperature and pressure of the adsorption bed are restored to their initial state.

[0016] Compared with existing technologies, the technical solution of this application has the following advantages: the device and method achieve continuous adsorption and safe recovery of radioactive inert gases by using multiple sets of adsorption beds for alternating adsorption and desorption, combined with temperature and pressure coordinated control and automatic valve switching. This invention has the advantages of high processing efficiency, small footprint, and applicability to the treatment of large-volume radioactive waste gases. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a device frame for purifying radioactive inert gases in a local space, as proposed in an embodiment of the present invention. Figure 2 This is a schematic diagram of a method for purifying radioactive inert gas in a local space according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached drawings: Adsorption bed 1; Retention bed 2; Cold water tank 3; Compressor 4; Hot water tank 5; Vacuum pump 6; First drying bed 7; Second drying bed 8; Gas storage tank 9; Gas-water separator 10; Activated carbon outlet 11. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This embodiment provides a device for the rapid and continuous purification of radioactive inert gas in a local space. The overall process of the device involves controlling the incoming external gas to enter the adsorption bed under high pressure and low temperature. Most of the inert gas is adsorbed by the adsorption bed. After working for a period of time, once the desired breakthrough point is reached (the breakthrough point is used to characterize the critical state of dynamic failure of the adsorption bed. Its core determination criterion is to set a threshold ratio of adsorbate concentration in the effluent to feed concentration after experimentally measuring the breakthrough curve), the adsorption bed is depressurized and heated to promote the desorption of inert gas and recover the precipitated inert gas. The incoming external gas is then adsorbed by the next set of adsorption beds. After multiple cycles, the inert gas content in the local space is reduced. This device can be considered as designed to ensure the gas safety of a local space in emergency situations (such as inert gas leaks in factories, nuclear safety accidents, etc.), and is itself an emergency protection solution.

[0021] Example 1 Please see Figure 1 This embodiment presents a device for purifying radioactive inert gases in a local space, comprising: Multiple adsorption beds 1 are provided, each group comprising two or more adsorption beds 1. Each adsorption bed 1 has an internal coil for supplying a cold or hot source to control its temperature. The coil is surrounded by an adsorption medium to retain inert gases. The inlet and outlet of each adsorption bed 1 are flanged connections, and an activated carbon outlet 11 is located at the bottom for easy unloading. Gas monitoring sensors are installed upstream and downstream of each adsorption bed 1 group. Copper tubing is preferred for the coils, and their specific dimensions are determined by the size of the adsorption bed 1.

[0022] Regarding the adsorption medium, activated carbon and metal framework materials have different adsorption capacities for different inert gases, each with its own advantages and disadvantages. The medium used is determined after fully considering factors such as adsorption effect and cost during the design of the device.

[0023] Preferably, each adsorption bed 1 is equipped with a built-in pressure sensor and temperature sensor to acquire real-time pressure and temperature data inside the adsorption bed 1. Specifically, the expected size and floor area of ​​the equipment are related to the size of the local space. Specifically, the air volume to be treated is estimated by the size of the local space, and the purification device is designed based on the air volume to be treated. The filling volume of the adsorption bed 1 is calculated and the key equipment is selected. Finally, the size and floor area of ​​the purification device are determined by combining the components.

[0024] Retention bed 2 is used to recover the radioactive inert gas released from adsorption bed 1 during the reverse desorption process. Preferably, an inert gas monitor is installed at the outlet of retention bed 2 to monitor the concentration of inert gas in the gas discharged to the outside in real time, ensuring safety.

[0025] The cold water tank 3 and compressor 4 are used to provide a low-temperature and high-pressure environment for the adsorption bed 1 during the forward adsorption process. During the forward adsorption process, the cold water tank 3 and compressor 4 are started to ensure that the activated carbon bed in the forward adsorption circuit is in a relatively low-temperature (preferably -2 to 5°C) and high-pressure (preferably 0.3 to 0.8 MPa) working airflow environment, which promotes the adsorption and recovery of inert gases in the gas to be purified.

[0026] The hot water tank 5 and vacuum pump 6 are used to provide a high-temperature and vacuum environment for the adsorption bed 1 during the reverse desorption process. During the reverse desorption process, the hot water tank 5 and vacuum pump 6 are activated to ensure that the gas flow temperature in the reverse desorption circuit is greater than 45°C and the working environment pressure is less than 0.1 MPa, thereby promoting the adsorption and recovery of inert gases adsorbed by the activated carbon bed in the aforementioned steps.

[0027] The automatic control system includes multiple solenoid check valves and three-way valves installed in the device's circuit, each of which can be remotely controlled, as well as multiple functional sensors. The automatic control system automatically switches the opening and closing states of the solenoid valves based on sensor data. Most importantly, the automatic control includes controlling multiple adsorption beds 1 to alternately perform forward adsorption and desorption, in a cyclical manner. Specifically, when one adsorption bed 1 in a group completes its forward adsorption process, the valve is remotely switched, and that adsorption bed 1 directly performs the reverse desorption process. Simultaneously, the valve is switched again, and the next adsorption bed 1 in the next group continues the forward adsorption process, thus repeating the cycle.

[0028] Preferably, since the adsorption time is shorter than the desorption time, to ensure that the adsorption bed 1 is completely desorbed before it adsorbs again, the number of adsorption beds 1 is set to: n > t. a / t e , where t a The total time required for a single adsorption bed 1 to complete one reverse desorption process; t eThe total time required for a single adsorption bed 1 to complete one forward adsorption process, where n is an integer greater than or equal to 2. Furthermore, increasing the number of adsorption beds 1 results in a larger gas throughput, but also increases the integration difficulty. The specific number should be determined based on experimental results and actual throughput requirements.

[0029] Preferably, the system also includes a vapor-water separator 10 and a first drying bed 7. The vapor-water separator 10 is located after the compressor 4, and the first drying bed 7 is located after the vapor-water separator 10 to control the humidity of the gas entering the adsorption bed 1 to be below 15%. The drying bed is filled with molecular sieves, silica gel, or other desiccants. The regeneration cycle of the drying bed is related to the cumulative gas processing volume. After processing a certain amount of gas, the drying bed needs to be regenerated. The specific operation mode is to first isolate the drying bed, and then introduce a hot gas flow of 150℃-300℃ into it for a certain period of time to complete the regeneration.

[0030] Preferably, flow meters are installed upstream and downstream of the adsorption bed 1 to control the airflow velocity passing through the adsorption bed 1 during the adsorption or desorption process.

[0031] Preferably, during the reverse desorption process, the temperature of the desorption gas stream is greater than 45°C and the working environment pressure is less than 0.1 MPa.

[0032] Preferably, the system also includes a gas storage tank 9 and a second drying bed 8. The gas storage tank 9 is located at the inlet end of the equipment circuit, and the second drying bed 8 is connected to the outlet end of the gas storage tank 9. The gas storage tank 9 is used to buffer and store untreated gas.

[0033] Example 2 like Figure 2 As shown in this embodiment, a method for purifying radioactive inert gas in a local space is proposed. The method specifically includes the following steps: Taking the workflow of two sets of four adsorption beds as an example: S01: Start compressor 4. The radioactive gas flow is transformed into high-pressure gas by compressor 4. After passing through steam-water separator 10 and first drying bed 7, the water vapor is removed. Control valve to make the radioactive gas flow only through adsorption bed A in the first group of adsorption beds. At the same time, start cold water tank 3. Adsorption bed A starts forward adsorption. S02: Calculate the detection data of the upstream and downstream gas sensors of adsorption bed A. When the downstream data reaches 5% to 10% of the upstream data, control the valve to switch so that the radioactive gas flow passes through adsorption bed C in the second group of adsorption beds. Control the cold water tank 3 to start supplying refrigerant to adsorption bed C, and adsorption bed C starts to work in the forward adsorption. S03: Control valve switching, turn on vacuum pump 6 and hot water tank 5 to connect to adsorption bed A, adsorption bed A performs reverse desorption process, gas is discharged to the outside after secondary adsorption through retention bed 2; S04: After adsorption bed C completes adsorption, it undergoes a desorption process similar to that of adsorption bed A. At this time, adsorption bed B in the first adsorption bed 1 is controlled to start the adsorption process. After adsorption bed A completes desorption, adsorption bed C begins desorption.

[0034] The above example illustrates the working process of two sets of four adsorption beds. If there are multiple sets of adsorption beds, as shown in the example above, the multiple sets of adsorption beds alternately perform forward adsorption and desorption, repeating the cycle, which can quickly purify the air in a local space.

[0035] This setup enables the cyclic adsorption and desorption process, allowing for rapid and continuous purification of radioactive inert gases within a localized space.

[0036] Preferably, the reverse desorption process has been completed before the next forward adsorption of a single activated carbon bed, and the temperature and pressure of adsorption bed 1 have returned to their initial state.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for purifying radioactive inert gases in a local space, characterized in that, include: Multiple adsorption beds are provided, each group of adsorption beds includes two or more adsorption beds, each adsorption bed is equipped with a coil for the flow of a cold source or heat source to control the temperature of the adsorption bed, the outer periphery of the coil is filled with an adsorption medium to retain inert gas, and the inlet and outlet of the adsorption bed are connected to the pipeline through flanges; gas monitoring sensors are provided upstream and downstream of each group of adsorption beds. A retention bed is provided on one side of the exhaust port of the device for secondary adsorption and recovery of radioactive inert gas released from the adsorption bed during the reverse desorption process; The cold water tank and compressor are used to provide a low temperature and high pressure environment for the adsorption bed during the forward adsorption process, and to provide the adsorption bed with a working airflow environment of -2 to 5°C and 0.3 to 0.8 MPa to promote the adsorption and recovery of inert gases in the gas to be purified. A hot water tank and a vacuum pump are used to provide a temperature environment greater than 45°C and an airflow environment less than 0.1 MPa for the adsorption bed during the reverse desorption process. The automatic control system includes multiple solenoid valves and multiple functional sensors installed in the circuit of the device, which automatically switch the opening and closing states of the solenoid valves according to the sensor data; wherein, the automatic control includes controlling the multiple adsorption beds to alternately perform forward adsorption and desorption.

2. The apparatus for purifying radioactive inert gases in a local space according to claim 1, characterized in that, The number of adsorption beds is set to: n > t a / t e , where t a The total time required for a single adsorption bed to complete one reverse desorption process; t e The total time required for a single adsorption bed to complete one forward adsorption process, where n is an integer greater than or equal to 2.

3. The apparatus for purifying radioactive inert gases in a local space according to claim 1, characterized in that, It also includes a vapor-water separator and a first drying bed. The vapor-water separator is located after the compressor, and the first drying bed is located after the vapor-water separator to control the humidity of the gas entering the adsorption bed to be less than 15%.

4. The apparatus for purifying radioactive inert gases in a local space according to claim 1, characterized in that, An inert gas monitor is installed at the outlet end of the retention bed.

5. The apparatus for purifying radioactive inert gases in a local space according to claim 1, characterized in that, Flow meters are installed upstream and downstream of the adsorption bed to control the airflow velocity passing through the adsorption bed during the adsorption or desorption process.

6. The apparatus for purifying radioactive inert gas in a local space according to claim 1, characterized in that, During the reverse desorption process, the temperature of the desorption gas stream is greater than 45°C, and the working environment pressure is less than 0.1 MPa.

7. The apparatus for purifying radioactive inert gases in a local space according to claim 1, characterized in that, It also includes a gas storage tank and a second drying bed. The gas storage tank is located at the inlet end of the device circuit, and the second drying bed is connected to the outlet end of the gas storage tank.

8. The apparatus for purifying radioactive inert gases in a local space according to any one of claims 1-7, characterized in that, The bottom of the adsorption bed is equipped with an activated carbon outlet.

9. A method for purifying radioactive inert gas in a local space, characterized in that, The method, using the apparatus for purifying radioactive inert gases in a local space as described in any one of claims 1-8, comprises: The compressor is started, and the radioactive gas flow is transformed into high-pressure gas through the compressor. After passing through the steam-water separator and the first drying bed, the water vapor is removed. The valve is controlled so that the radioactive gas flow only passes through adsorption bed A in the first group of adsorption beds. At the same time, the cold water tank is started, and adsorption bed A begins to perform forward adsorption. Calculate the detection data of the upstream and downstream gas sensors of the adsorption bed A. When the downstream data reaches 5% to 10% of the upstream data, control the valve to switch so that the radioactive gas flow passes through adsorption bed C in the second group of adsorption beds. Control the cold water tank to start providing refrigerant to adsorption bed C, and adsorption bed C starts to perform forward adsorption. Switch the control valve, turn on the vacuum pump and hot water tank to connect to the adsorption bed A, the adsorption bed A performs a reverse desorption process, and the gas is discharged to the outside after being adsorbed twice by the retention bed; After the adsorption bed C completes the adsorption, it undergoes a desorption process similar to that of the adsorption bed A. At this time, the adsorption bed B in the first group of adsorption beds is controlled to start the adsorption process. After the desorption of the adsorption bed A is completed, the adsorption bed C starts to desorb. Multiple adsorption beds alternately perform forward adsorption and desorption.

10. A method for purifying radioactive inert gas in a local space according to claim 9, characterized in that, Before a single activated carbon bed can undergo the next forward adsorption, the reverse desorption process has been completed, and the temperature and pressure of the adsorption bed have returned to their initial state.

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