Method and system for recycling krypton and xenon in nuclear industry waste gas
By designing a system of catalytic oxidation, gas combustion, alkaline solution washing and adsorption analysis, the problem of poor applicability of krypton-xenon separation in large-flow waste gas treatment in existing technologies was solved, and efficient and convenient krypton-xenon recovery was achieved.
Patent Information
- Application Number
- CN202510564183.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-29
- Publication Date
- 2025-09-26
AI Technical Summary
Existing gas adsorption separation technology is mainly limited to the laboratory level, with complex operation and narrow applicability, especially in the treatment of large-flow exhaust gases.
A system consisting of a catalytic oxidation tank, a mixed combustion device, an alkaline solution scrubber, a drying bed, a krypton-xenon extraction device, and a recovery tank was designed. Through multiple steps such as catalytic oxidation, gas combustion, alkaline solution scrubbing, and adsorption analysis, krypton and xenon in nuclear industrial waste gas can be efficiently separated and recovered.
It realizes simple and efficient krypton-xenon separation and recovery, is suitable for large-flow exhaust gas treatment, and improves the convenience of operation and separation efficiency.
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Figure CN120698424A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of radioactive gas separation and treatment, and in particular to a method and system for recovering krypton and xenon from nuclear industry waste gas. Background Art
[0002] The development background of radioactive gas separation technology is closely related to the production and application of radioactive noble gases. Radioactive noble gases such as xenon ( 133 Xe), Krypton ( 85 Kr) and other gases are important fission products, primarily produced in nuclear power plant reactors, underground nuclear testing, and spent fuel reprocessing. Due to their radioactive properties, these gases have important applications in nuclear arms control verification, nuclear environmental monitoring, and the nuclear fuel cycle.
[0003] In recent years, gas adsorption separation technology has garnered significant attention due to its simplicity and low cost. In particular, the use of solid porous adsorbent materials to selectively and efficiently separate target radioactive noble gases from complex ambient gases at room temperature is a simple and highly effective method. New porous materials, such as metal-organic frameworks (MOFs), have demonstrated excellent performance and promising application prospects in separating the noble gases krypton and xenon. These materials possess high porosity and adjustable pore size, enabling efficient and selective adsorption of specific gas molecules.
[0004] In the existing technology, gas adsorption separation technology is often limited to laboratory-level use, with complex operation and narrow applicability, especially for large-flow exhaust gas treatment conditions. Summary of the Invention
[0005] The present invention provides a method and system for recovering krypton and xenon from nuclear industrial waste gas, which is used to solve the problem that the prior art lacks a system for gas adsorption separation technology applicable to large-flow waste gas treatment.
[0006] The technical solutions of the present invention are as follows:
[0007] The present invention proposes a system for recovering krypton and xenon from nuclear industrial waste gas. The system includes a catalytic oxidation tank, a mixed combustion device, an alkaline solution scrubber, a drying bed, a krypton and xenon extraction device, and a recovery tank. The catalytic oxidation tank is sequentially connected to the mixed combustion device, the alkaline solution scrubber, the drying bed, the krypton and xenon extraction device, and the recovery tank through pipelines. The krypton and xenon extraction device absorbs and decomposes krypton and xenon gases through an adsorbent, thereby collecting the krypton and xenon gases from the waste gas.
[0008] In some embodiments, the catalytic oxidation tank oxidizes nitrogen monoxide in the exhaust gas into nitrogen oxides by adding an oxidant and a catalyst.
[0009] In some embodiments, the catalyst is a liquid phase catalyst comprising HNO3, KMnO4, NaClO2, NaClO, H2O2, KBrO3, K2Br2O7, Na3CrO4, and (NH4)2CrO7.
[0010] In some embodiments, the mixed combustion device protects multiple mixed combustion devices, oxygen and hydrogen are introduced into the mixed burners for combustion respectively, and the mixed combustion device removes carbon monoxide and oxygen in the exhaust gas by combustion; multiple mixed combustion devices are introduced with oxygen and hydrogen at the same time or oxygen and hydrogen are introduced successively, and multiple mixed burners are connected in parallel.
[0011] In some embodiments, an alkaline liquid is placed in the alkali liquid scrubber, which is used to remove nitrogen oxides and carbon dioxide in the exhaust gas. The alkaline liquid is sodium hydroxide; the drying bed is filled with molecular sieves, which is used to reduce the humidity of the exhaust gas.
[0012] In some embodiments, a krypton-xenon extraction device includes an absorption tower, a desorption tower, and an oil-gas separator. An adsorbent is placed in the absorption tower. The adsorbent absorbs the krypton-xenon gas in the exhaust gas and then enters the desorption tower. The desorption tower heats the adsorbent to separate the krypton-xenon gas from the adsorbent. The separated krypton-xenon gas enters the oil-gas separator for separation to obtain pure krypton-xenon gas.
[0013] In some embodiments, the gas absorbed by the adsorbent in the absorption tower is passed through a pipeline back into the catalytic oxidation tank for cyclic absorption; a circulation loop of the adsorbent is provided between the absorption tower and the desorption tower, and the adsorbent is circulated to the absorption tower for reuse after being cooled in the desorption tower.
[0014] In some embodiments, the adsorbent is kerosene, and the oil-gas separator uses a wire mesh to recover the kerosene droplets mixed with krypton and xenon gases precipitated from the desorption tower. The kerosene separated by the oil-gas separator is input into the absorption tower through a pipeline.
[0015] In some embodiments, a cooling device is provided between the desorption tower and the oil-gas separator, and the krypton-xenon gas separated by the desorption tower is cooled in the cooling device before entering the oil-gas separator.
[0016] The present invention proposes a system for recovering krypton and xenon from nuclear industry waste gas, the method comprising:
[0017] Step 1: The exhaust gas passes through a catalytic oxidation tank to oxidize the nitrogen monoxide in the exhaust gas into nitrogen oxides, and the oxidized exhaust gas enters a mixed combustion device;
[0018] Step 2: The oxidized waste gas is introduced into a gas mixing combustion device with oxygen and hydrogen for mixed combustion to remove carbon monoxide and oxygen in the waste gas. The burned waste gas then enters an alkaline solution scrubber.
[0019] Step 3: The exhaust gas after combustion passes through an alkaline liquid scrubber to remove nitrogen oxides and carbon dioxide in the exhaust gas, and the exhaust gas after alkaline liquid washing enters the drying bed;
[0020] Step 4: The waste gas after alkali washing passes through the drying bed to reduce the humidity of the waste gas, and the dried waste gas enters the absorption tower;
[0021] Step 5: The dried exhaust gas passes through an absorption tower to absorb the krypton and xenon gases in the exhaust gas into kerosene. The gas absorbed by the absorption tower is then re-introduced into the catalytic oxidizer, and the kerosene that has absorbed the krypton and xenon gases enters the desorption tower.
[0022] Step 6: The kerosene that has absorbed the krypton-xenon gas is heated in a desorption tower to separate the krypton-xenon gas and the kerosene. The krypton-xenon gas enters a cooling device, and the kerosene is cooled and flows into an absorption tower.
[0023] Step 7: The separated krypton-xenon gas is cooled in a cooling device, and the cooled krypton-xenon gas enters an oil-gas separator;
[0024] Step 8: The cooled krypton-xenon gas is de-oiled through an oil-gas separator to obtain pure krypton-xenon gas which is stored in a recovery tank. The kerosene in the oil-gas separator flows into an absorption tower.
[0025] The implementation of the present invention has the following beneficial effects:
[0026] The present invention provides a system and method for recovering krypton and xenon from nuclear industrial waste gas. The process flow is simple, the operation is convenient, and the separation efficiency is high. The system and method can efficiently separate and recover the krypton and xenon components in nuclear industrial waste gas by setting up multiple steps such as catalytic oxidation, gas combustion, alkaline solution washing, and adsorption analysis. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is a schematic diagram of a system for recovering krypton and xenon from nuclear industry waste gas proposed in an embodiment of the present invention;
[0028] Figure 2 This is a step diagram of a method for recovering krypton and xenon from nuclear industry waste gas proposed in an embodiment of the present invention. DETAILED DESCRIPTION
[0029] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0030] like Figure 1As shown, the present invention proposes a system for recovering krypton and xenon from nuclear industry waste gas. The system includes a catalytic oxidation tank, a mixed combustion device, an alkaline solution scrubber, a drying bed, an absorption tower, a desorption tower, a cooling device, an oil-gas separator, and a recovery tank. The catalytic oxidation tank is sequentially connected to the mixed combustion device, the alkaline solution scrubber, the drying bed, the absorption tower, the desorption tower, the cooling device, the oil-gas separator, and the recovery tank through pipelines. The waste gas contains NO, N2, CO, CO2, O2, H2O, Kr, Xe, etc., and the remaining impurity gases other than krypton and xenon need to be removed through the above-mentioned devices.
[0031] When exhaust gas enters the device, it first enters the catalytic oxidation tank, where it oxidizes the nitrogen monoxide in the exhaust gas into nitrogen oxides such as NOx. The catalytic oxidation tank contains an oxidant and a catalyst. The catalysts used are liquid-phase catalysts, including HNO3, KMnO4, NaClO2, NaClO, H2O2, KBrO3, K2Br2O7, Na3CrO4, (NH4)2CrO7, etc.
[0032] After passing through the catalytic oxidation tank, the exhaust gas enters the mixed combustion device, which is fed with oxygen and hydrogen separately and removes carbon monoxide, oxygen, and other gases from the exhaust gas through combustion. The mixed combustion device contains one or more mixed burners. Multiple mixed burners can be fed with auxiliary combustion gases such as oxygen and hydrogen simultaneously or sequentially. Multiple mixed burners are connected in parallel.
[0033] After passing through the mixed combustion device, the exhaust gas enters the alkali scrubber, where an alkaline liquid, such as sodium hydroxide, is placed to remove nitrogen oxides and other gases such as carbon dioxide from the exhaust gas, reducing their impact on krypton and xenon adsorption in subsequent processes. The alkali scrubber also cools the gas entering the kerosene adsorption tower, maintaining a suitable temperature range of 30-50°C to ensure smooth dissolution and absorption of krypton and xenon.
[0034] After passing through the alkali liquid scrubber, the exhaust gas enters the drying bed, which is filled with materials such as molecular sieves to reduce the humidity of the exhaust gas and avoid bringing moisture into the kerosene absorption tower;
[0035] After passing through the drying bed, the waste gas enters the adsorption tower and then enters the continuous countercurrent packed kerosene absorption tower. The krypton and xenon in the waste gas are adsorbed into the kerosene. At the same time, the waste gas absorbed by the absorption tower contains a large amount of nitrogen and a small amount of undissolved krypton and xenon. These waste gases are transported to the catalytic oxidizer through a pipeline for the next round of recovery to improve the recovery efficiency.
[0036] The kerosene, which has absorbed krypton and xenon gases, passes through the adsorption tower and enters the desorption tower. The adsorbed kerosene is heated thoroughly in the desorption tower, causing the gases, krypton and xenon, to precipitate, with boiling points lower than the kerosene. By heating the kerosene to a temperature above the boiling points of krypton and xenon, their precipitation is encouraged. A kerosene circulation loop exists within the absorption and desorption towers, and a cooling process is implemented during the kerosene's return from the desorption tower to the absorption tower. This ensures that the kerosene entering the absorption tower is at an appropriate temperature, ranging from 10-30°C, to ensure the subsequent adsorption of krypton and xenon by the kerosene.
[0037] The gas desorbed from the desorption tower is cooled by a cooling device to reduce the temperature of the krypton-xenon gas separated from the desorption tower to a temperature range of -135 to -170°C, while promoting the condensation of oil in the gas.
[0038] The desorbed gas then cools and enters the oil-gas separator. The cooled gas then passes through the oil mist separator, which uses a screen or other oil-gas separation device to recover the kerosene droplets mixed with the krypton and xenon gases precipitated from the desorption tower, resulting in pure inert gases krypton and xenon. The kerosene separated by the oil-gas separator is then piped into the absorption tower, where the pure inert gases krypton and xenon are ultimately stored in a recovery tank.
[0039] like Figure 2 As shown, the present invention provides a method for recovering krypton and xenon from nuclear industry waste gas, the method comprising:
[0040] Step 1: Exhaust gas enters the catalytic oxidation tank, which oxidizes the nitrogen monoxide in the exhaust gas into nitrogen oxides such as NOx. The oxidized exhaust gas then enters the mixed combustion device. The catalytic oxidation tank is equipped with an oxidant and a catalyst. The catalysts used are liquid-phase catalysts, including HNO3, KMnO4, NaClO2, NaClO, H2O2, KBrO3, K2Br2O7, Na3CrO4, (NH4)2CrO7, etc.
[0041] Step 2: The oxidized waste gas is then fed with oxygen and hydrogen in a gas mixing and combustion device for mixed combustion. This removes carbon monoxide, oxygen, and other gases from the waste gas, which then enters an alkaline scrubber. The mixed combustion device contains one or more mixing burners, which can be fed with auxiliary combustion gases such as oxygen and hydrogen simultaneously or sequentially.
[0042] Step 3: The exhaust gas after combustion passes through an alkaline liquid scrubber to remove nitrogen oxides and carbon dioxide present in the exhaust gas. The exhaust gas after alkaline liquid washing enters the drying bed and passes through the alkaline liquid scrubber to reduce its impact on krypton-xenon adsorption in subsequent process flows.
[0043] Step 4: After washing with alkali solution, the exhaust gas passes through the drying bed to reduce the humidity of the exhaust gas. The dried exhaust gas enters the absorption tower. The drying bed is filled with materials such as molecular sieves or other substances that can reduce humidity to prevent moisture from entering the kerosene absorption tower.
[0044] Step 5: The dried exhaust gas passes through an absorption tower, where the krypton and xenon gases in the gas are absorbed into kerosene. The dried exhaust gas then passes through the kerosene absorption tower with continuous countercurrent packing, where the krypton and xenon in the gas are adsorbed into the kerosene. The krypton and xenon adsorption process utilizes the solubility differences of the gases in kerosene at different temperatures to achieve separation. The kerosene that has absorbed the krypton and xenon gases enters the desorption tower. Simultaneously, the absorption tower discharges the absorbed gas, which contains a large amount of nitrogen and a small amount of undissolved krypton and xenon. This absorbed gas is then fed back into the catalytic oxidizer for the next round of recovery, improving recovery efficiency.
[0045] Step 6: The kerosene that has absorbed the krypton-xenon gas is heated in a desorption tower, and its temperature is controlled to be higher than the boiling point of krypton-xenon, thereby promoting its precipitation. The krypton-xenon gas, which has a lower boiling point than the kerosene, is also promoted to precipitate, thereby separating the krypton-xenon gas and the kerosene. The krypton-xenon gas enters a cooling device, and the kerosene is cooled by the cooling device and then flows into the absorption tower.
[0046] Step 7: The separated krypton-xenon gas is cooled in a cooling device and then enters the oil-gas separator. During the gas cooling process, the temperature of the separated krypton-xenon gas is controlled. At this time, the oil is easy to condense, which is convenient for subsequent filtration and removal.
[0047] Step 8: The cooled krypton-xenon gas is de-oiled through an oil-gas separator. The oil-gas separator uses a wire mesh or other oil-gas separation device to recover the kerosene droplets mixed in the cooled krypton-xenon gas, obtaining pure krypton-xenon gas and storing it in a recovery tank. The kerosene in the oil-gas separator flows into the absorption tower.
[0048] The above embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
Claims
1. A system for recovering krypton and xenon from nuclear industry waste gas, characterized in that: The system includes a catalytic oxidation tank, a mixed combustion device, an alkali solution scrubber, a drying bed, a krypton-xenon extraction device and a recovery tank. The catalytic oxidation tank is sequentially connected to the mixed combustion device, the alkali solution scrubber, the drying bed, the krypton-xenon extraction device and the recovery tank through pipelines. The krypton-xenon extraction device absorbs and decomposes krypton-xenon gas through an adsorbent, and collects krypton-xenon gas from the exhaust gas.
2. A system for recovering krypton and xenon from nuclear industry waste gas according to claim 1, characterized in that: The catalytic oxidation tank oxidizes nitrogen monoxide in the exhaust gas into nitrogen oxides by adding an oxidant and a catalyst.
3. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 2, characterized in that: The catalyst is a liquid phase catalyst, and the catalyst comprises HNO3, KMnO4, NaClO2, NaClO, H2O2, KBrO3, K2Br2O7, Na3CrO4 and (NH4)2CrO7.
4. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 3, characterized in that: The mixed combustion device protects multiple mixed combustion devices, oxygen and hydrogen are respectively introduced into the mixed combustion devices for combustion, and the mixed combustion device removes carbon monoxide and oxygen in the exhaust gas through combustion; multiple mixed combustion devices are introduced with oxygen and hydrogen at the same time or successively, and the multiple mixed combustion devices are connected in parallel.
5. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 1, characterized in that: An alkaline liquid is placed in the alkali liquid scrubber, which is used to remove nitrogen oxides and carbon dioxide in the exhaust gas. The alkaline liquid is sodium hydroxide; a molecular sieve is filled in the drying bed, which is used to reduce the humidity of the exhaust gas.
6. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 1, characterized in that: The krypton-xenon extraction device includes an absorption tower, a desorption tower, and an oil-gas separator. An adsorbent is placed in the absorption tower. The adsorbent absorbs krypton-xenon gas in the exhaust gas and then enters the desorption tower. The desorption tower heats the adsorbent to separate the krypton-xenon gas from the adsorbent. The separated krypton-xenon gas enters the oil-gas separator for separation to obtain pure krypton-xenon gas.
7. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 6, characterized in that: The gas absorbed by the adsorbent in the absorption tower is passed through a pipeline into the catalytic oxidation tank again for cyclic absorption; a circulation loop of the adsorbent is provided between the absorption tower and the desorption tower, and the adsorbent is circulated to the absorption tower for reuse after being cooled in the desorption tower.
8. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 7, characterized in that: The adsorbent is kerosene, and the oil-gas separator uses a wire mesh to recover the kerosene droplets mixed with krypton and xenon gases precipitated from the desorption tower. The kerosene separated by the oil-gas separator is input into the absorption tower through a pipeline.
9. The system for recovering krypton and xenon from nuclear industry waste gas according to claim 6, characterized in that: A cooling device is provided between the desorption tower and the oil-gas separator. The krypton-xenon gas separated by the desorption tower is cooled in the cooling device and then enters the oil-gas separator.
10. A system for recovering krypton and xenon from nuclear industry waste gas according to any one of claims 1 to 9, characterized in that: The method comprises: Step 1: The exhaust gas passes through a catalytic oxidation tank to oxidize the nitrogen monoxide in the exhaust gas into nitrogen oxides, and the oxidized exhaust gas enters a mixed combustion device; Step 2: The oxidized waste gas is respectively introduced into a gas mixing combustion device with oxygen and hydrogen for mixed combustion to remove carbon monoxide and oxygen in the waste gas, and the burned waste gas enters an alkali liquid scrubber; Step 3: The exhaust gas after combustion passes through an alkaline liquid scrubber to remove nitrogen oxides and carbon dioxide present in the exhaust gas, and the exhaust gas after alkaline liquid washing enters a drying bed; Step 4: The waste gas after alkali solution washing passes through a drying bed to reduce the humidity of the waste gas, and the dried waste gas enters an absorption tower; Step 5: The dried exhaust gas passes through an absorption tower to absorb the krypton and xenon gases in the exhaust gas into kerosene. The gas absorbed by the absorption tower is re-introduced into the catalytic oxidizer, and the kerosene that absorbs the krypton and xenon gases enters a desorption tower. Step 6: The kerosene that has absorbed the krypton-xenon gas is heated in a desorption tower to separate the krypton-xenon gas and the kerosene. The krypton-xenon gas enters a cooling device, and the kerosene is cooled and flows into the absorption tower. Step 7: The separated krypton-xenon gas is cooled in the cooling device, and the cooled krypton-xenon gas enters the oil-gas separator; Step 8: The cooled krypton-xenon gas passes through the oil-gas separator to remove oil, obtaining pure krypton-xenon gas and storing it in a recovery tank, and the kerosene in the oil-gas separator flows into the absorption tower.