Micro gas-liquid countercurrent catalytic exchange device for tritium water treatment

Abstract

The invention discloses a tritium water treatment-oriented miniature gas-liquid countercurrent catalytic exchange device. The tritium water treatment-oriented miniature gas-liquid countercurrent catalytic exchange device comprises a gas feeding pipe, a gas discharging pipe, a liquid feeding pipe, a liquid discharging pipe, a micro-channel, a fluid constraint structure and a catalyst, according to the micro gas-liquid countercurrent catalytic exchange device disclosed by the invention, a gas-liquid countercurrent process under a micro scale is realized by utilizing a fluid constraint structure; a catalytic exchange process is realized by using a catalyst; a micro gas-liquid catalytic exchange place is constructed by utilizing the micro-channel, so that an efficient mass transfer process under a micro scale is realized, the gas-liquid catalytic exchange effect is enhanced, and the retention amount of materials is reduced. The device is simple in structure, easy to seal, long in catalyst service life, small in tritium retention amount, capable of effectively improving the tritium separation efficiency and high in safety.

Description

Technical Field

[0001] The present invention relates to the technical field of radioactive wastewater treatment, and particularly relates to a micro gas-liquid countercurrent catalytic exchange device for tritium water treatment. Background Art

[0002] The safe and efficient development of nuclear energy is one of the important strategic decisions for energy development. However, during the operation of nuclear power facilities, it is inevitable to generate tritium-containing wastewater (HTO) with different concentrations and radioactive hazards. HTO and its vapor can enter the human body through breathing, infiltration, etc. and participate in metabolism, causing long-term harm to human health. In addition, it will also cause radioactive pollution to the environment. Therefore, it is of great significance to develop tritium removal treatment technology for tritium-containing wastewater and reduce the tritium concentration of emissions.

[0003] At present, the tritium-containing wastewater treatment technologies mainly include water rectification technology, electrolysis technology, and hydrogen-water isotope catalytic exchange technology. Among them, the hydrogen-water isotope catalytic exchange technology has the advantages of high efficiency, high selectivity, low energy consumption, and environmental protection, and has good application prospects. The hydrogen-water isotope catalytic exchange technology can be further divided into three types according to different exchange processes: high-temperature gas-phase catalytic exchange, liquid-phase catalytic exchange, and combined electrolysis catalytic exchange. Among them, the liquid-phase catalytic exchange process has mild operating conditions, low energy consumption, high separation efficiency, and simple and reliable equipment process, and is one of the most valuable tritium-containing wastewater treatment technologies. Traditional liquid-phase catalytic exchange devices often use the method of filling hydrophilic fillers and hydrophobic catalysts to achieve a continuous multi-stage gas-liquid countercurrent separation process and a hydrogen-water isotope catalytic exchange process. However, this device structure will cause the catalyst to come into direct contact with the liquid, resulting in some hydrophobic catalysts being immersed in the liquid phase and deactivated. In addition, the distribution of hydrophobic catalysts and hydrophilic fillers will affect the gas-liquid flow process, causing local backmixing problems, resulting in a decrease in mass transfer efficiency and a weakening of tritium removal ability. Especially when treating high-concentration tritium water, the traditional liquid-phase catalytic exchange device often has a large tritium retention amount and a large amount of hydrogen consumption, posing a safety risk. Therefore, it is urgent to optimize the structure of the hydrogen-tritium water catalytic exchange device, improve the mass transfer performance and the tritium removal efficiency of the device, reduce tritium retention, and then enhance the safety of the device. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a micro gas-liquid countercurrent catalytic exchange device for tritium water treatment, which has the characteristics that the catalyst does not come into direct contact with the liquid, the gas-liquid countercurrent is stable, the mass transfer efficiency is high, and the tritium removal ability is strong.

[0005] The present invention provides a micro gas-liquid countercurrent catalytic exchange device for tritium water treatment, which is characterized in that,

[0006] It includes a microchannel, a gas inlet pipe, a gas outlet pipe, a liquid inlet pipe, a liquid outlet pipe, a fluid confinement structure, and a catalyst; the gas inlet pipe and the gas outlet pipe are respectively arranged on opposite sides of the microchannel, and the gas inlet pipe is connected to the lower part of the microchannel, and the gas outlet pipe is connected to the upper part of the microchannel; the liquid inlet pipe is connected to the center of the top cross-section of the microchannel, and the liquid outlet pipe is connected to the center of the bottom cross-section of the microchannel, so that the reaction gas and the reaction liquid entering the microchannel form a countercurrent contact inside the microchannel;

[0007] The fluid confinement structure is fixed inside the microchannel and connects the liquid inlet pipe and the liquid outlet pipe to guide the liquid to flow along the surface of the fluid confinement structure; the catalyst is fixed inside the microchannel, and the reaction gas undergoes a catalytic exchange reaction on the surface of the catalyst, and a gas-liquid mass transfer process occurs on the surface of the fluid confinement structure.

[0008] Preferably, the fluid confinement structure is a spiral structure, the length of the spiral structure is 50 - 1000 mm, the diameter of the spiral structure is 0.05 - 30 mm, the spiral gap is 0.01 - 5 mm, and the cross-sectional shape of the spiral line includes a circle or a rectangle, restricting the liquid to form a stable flow in the spiral gap and on the surface of the spiral structure.

[0009] Preferably, the fluid confinement structure is coaxially placed with the microchannel and does not contact the inner wall of the microchannel; the catalyst is particles containing platinum, nickel, etc. that can catalyze the hydrogen-water isotope exchange reaction, and the particle size is 1 nm - 500 μm, and is loaded on the inner wall of the microchannel by means of adhesion or deposition.

[0010] Preferably, the fluid confinement structure is formed on the inner wall of the microchannel by means of adhesion or etching, the catalyst is a porous rod-shaped material containing platinum, nickel, etc. that can catalyze the hydrogen-water isotope exchange reaction, the length of the rod-shaped material is 50 - 1000 mm, the pore diameter is 1 - 500 nm, and the catalyst is fixed inside the microchannel and does not contact the inner wall of the microchannel.

[0011] Preferably, the microchannel can be heated and temperature-controlled by a heating device.

[0012] Preferably, the heating device includes a heating plate or a heating tape.

[0013] Preferably, the micro gas-liquid countercurrent catalytic exchange device is set to be single-stage or cascade.

[0014] The beneficial effects of the present invention are:

[0015] The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment provided by the present invention separates the fluid constraint device from the catalyst and places them in non-contact with each other, avoiding the problem of catalyst deactivation; by combining microchannels with a fluid constraint structure, a micro gas-liquid catalytic exchange site is constructed inside the microchannels, realizing an efficient mass transfer process of gas-liquid countercurrent at the microscale, avoiding local backmixing problems, increasing the reaction area at the same time, strengthening the gas-liquid catalytic exchange effect, and improving the mass transfer efficiency and tritium removal ability.

[0016] The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment of the present invention has a simple structure, is easy to seal, has a long service life of the catalyst, a small tritium retention amount, and high device safety. Description of the Drawings

[0017] Figure 1 It is a schematic diagram of a catalyst loaded on the inner wall of a microchannel of the micro gas-liquid countercurrent catalytic exchange device for tritium water treatment in an embodiment of the present invention;

[0018] Figure 2 It is a schematic diagram of a catalyst fixed inside a microchannel of the micro gas-liquid countercurrent catalytic exchange device for tritium water treatment in an embodiment of the present invention;

[0019] Figure 3 It is a schematic diagram of the cascade connection and use of the micro gas-liquid countercurrent catalytic exchange device for tritium water treatment and an electrolytic cell in an embodiment of the present invention;

[0020] Figure 4 A schematic diagram of the cascade connection and use of the micro gas-liquid countercurrent catalytic exchange device for tritium water treatment, an electrolytic cell, and a hydrogen-oxygen recombiner in an embodiment of the present invention;

[0021] In the figure: 1. Micro gas-liquid countercurrent catalytic exchange device; 101. Microchannel; 102. Gas feed pipe; 103. Gas discharge pipe; 104. Liquid feed pipe; 105. Liquid discharge pipe; 106. Fluid constraint structure; 107. Catalyst; 1’. Rear-stage micro gas-liquid countercurrent catalytic exchange device; 101’. Rear-stage microchannel; 102’. Rear-stage gas feed pipe; 103’. Rear-stage gas discharge pipe; 104’. Rear-stage liquid feed pipe; 105’. Rear-stage liquid discharge pipe; 106’. Rear-stage fluid constraint structure; 107’. Rear-stage catalyst; 2. Electrolytic cell; 3. Hydrogen-oxygen recombiner. Detailed Embodiments

[0022] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0023] A micro gas-liquid countercurrent catalytic exchange device for tritium water treatment, as Figure 1 and 2As shown, it includes a microchannel 101, a gas feed pipe 102, a gas discharge pipe 103, a liquid feed pipe 104, a liquid discharge pipe 105, a fluid confinement structure 106, and a catalyst 107; the gas feed pipe 102 and the gas discharge pipe 103 are respectively arranged on opposite sides of the microchannel 101, and the gas feed pipe 102 is connected to the lower part of the microchannel 101, and the gas discharge pipe 103 is connected to the upper part of the microchannel 101; the liquid feed pipe 104 is connected to the center of the top cross-section of the microchannel 101, and the liquid discharge pipe 105 is connected to the center of the bottom cross-section of the microchannel 101, so that the reaction gas and the reaction liquid entering the microchannel 101 form a countercurrent contact inside the microchannel 101;

[0024] The fluid confinement structure 106 is fixed inside the microchannel 101 and connects the liquid feed pipe 104 and the liquid discharge pipe 105 to guide the liquid to flow along the surface of the fluid confinement structure 106; the catalyst 107 is fixed inside the microchannel 101, and the reaction gas undergoes a catalytic exchange reaction on the surface of the catalyst 107, and a gas-liquid mass transfer process occurs on the surface of the fluid confinement structure 106.

[0025] Preferably, the fluid confinement structure 106 is a spiral structure, the length of the spiral structure is 50 - 1000 mm, the diameter of the spiral structure is 0.05 - 30 mm, the spiral gap is 0.01 - 5 mm, and the cross-sectional shape of the spiral line includes a circle or a rectangle, so as to confine the liquid to form a stable flow in the spiral line gap and on the surface of the spiral structure.

[0026] Preferably, the fluid confinement structure 106 is coaxially placed with the microchannel 101 and does not contact the inner wall of the microchannel 101; the catalyst 107 is particles containing platinum, nickel, etc. that can catalyze the hydrogen-water isotope exchange reaction, and the particle size is 1 nm - 500 μm, which is loaded on the inner wall of the microchannel 101 by means of adhesion or deposition.

[0027] Preferably, the fluid confinement structure 106 is formed on the inner wall of the microchannel 101 by adhesion or etching, the catalyst 107 is a porous rod-shaped material containing platinum, nickel, etc. that can catalyze the hydrogen-water isotope exchange reaction, the length of the rod-shaped material is 50 - 1000 mm, the pore diameter is 1 - 500 nm, the catalyst 107 is fixed inside the microchannel 101 and does not contact the inner wall of the microchannel 101.

[0028] Preferably, the microchannel 101 can be heated and temperature-controlled by a heating device.

[0029] Preferably, the heating device includes a heating plate or a heating tape.

[0030] Preferably, the micro gas-liquid countercurrent catalytic exchange device 1 is set to be single-stage or cascade.

[0031] Example 1

[0032] As an example, as Figure 1 shown, the helical structure length of the fluid confinement structure 106 is 200 mm, the helical structure diameter is 1.5 mm, the helical gap is 0.4 mm, the cross-section of the helical line is circular, and it is coaxially placed with the microchannel 101 for confining the liquid to form a stable flow in the helical gap and on the surface of the helical structure; the catalyst 107 is platinum-loaded nanoparticles with a particle size of 100 nm, which are loaded on the inner wall of the microchannel 101; during the whole process, the temperature in the microchannel 101 is maintained at 60 °C by a heating device.

[0033] During use, tritiated light water with a tritium activity concentration of 2.0×10 5 Bq / L flows into the liquid feed pipe 104 at a flow rate of 10 μL / min and flows downward along the fluid confinement structure 106; hydrogen gas is introduced into the gas feed pipe 102 at a flow rate of 25 mL / min; the hydrogen gas undergoes a hydrogen-water isotope catalytic exchange reaction with the water vapor generated by the vaporization of tritiated water on the surface of the catalyst 107 at an operating temperature of 60 °C, and the tritium is exchanged into the hydrogen gas; the tritiated hydrogen gas generated after the catalytic exchange escapes from the gas discharge pipe 103, and the treated tritium-depleted light water flows out from the liquid discharge pipe 105. After the above process, the tritium activity concentration in the treated tritium-depleted light water is 1.3×10 5 Bq / L, and the height equivalent to a theoretical plate is 4.1 cm.

[0034] Example 2

[0035] As an example, as Figure 3 shown, the micro gas-liquid countercurrent catalytic exchange device 1, the subsequent micro gas-liquid countercurrent catalytic exchange device 1', and the electrolytic cell 2 are used in series in sequence. Among them, the helical structure lengths of the fluid confinement structures 106 in the micro gas-liquid countercurrent catalytic exchange device 1 and the subsequent fluid confinement structure 106' are both 300 mm, the helical structure diameters are both 2.0 mm, the helical gaps are both 0.5 mm, and the cross-sections are both circular; the catalysts 107 and the subsequent catalyst 107' are both platinum-loaded nanoparticles with a particle size of 200 nm, which are respectively loaded on the inner walls of the microchannel 101 and the subsequent microchannel 101'; during the whole process, the temperatures in the microchannel 101 and the subsequent microchannel 101' are maintained at 60 °C by a heating device.

[0036] Deionized water flows into the liquid feed pipe 104 of the micro gas-liquid countercurrent catalytic exchange device 1 at a flow rate of 30 μL / min, forms a stable liquid flow along the fluid confinement structure 106, and flows out from the liquid discharge pipe 105, and is combined with tritiated light water with a tritium activity concentration of 2.0×10 5Mix with tritiated light water at a flow rate of 20 μL / min and a concentration of Bq / L, and flow in from the liquid feed pipe 104' of the downstream micro gas-liquid countercurrent catalytic exchange device 1'. After flowing downward along the downstream fluid constraint structure 106' to participate in the reaction, it flows into the electrolytic cell 2 from the downstream liquid discharge pipe 105'. The hydrogen gas generated after electrolysis enters the downstream microchannel 101' from the electrolytic cell 2 through the downstream gas feed pipe 102'. After participating in the hydrogen-water isotope catalytic exchange reaction in the downstream microchannel 101', it escapes from the downstream gas discharge pipe 103 and enters the microchannel 101 through the gas feed pipe 102 of the micro gas-liquid countercurrent catalytic exchange device 1. After the hydrogen-water isotope catalytic exchange reaction is carried out again, it is discharged from the gas discharge pipe 103.

[0037] After the above process, the treated tritiated light water is sampled from the liquid discharge pipe 105' at a flow rate of 5 μL / min, and the activity concentration of tritium is 5.8×10 5 Bq / L, and the height equivalent to a theoretical plate is 4.3 cm.

[0038] Example 3

[0039] As an example, as Figure 4 shown, the hydrogen-oxygen recombiner 3, the micro gas-liquid countercurrent catalytic exchange device 1, the downstream micro gas-liquid countercurrent catalytic exchange device 1', and the electrolytic cell 2 are used in series in sequence. Among them, the spiral structure lengths of the fluid constraint structures 106 and the downstream fluid constraint structure 106' in the micro gas-liquid countercurrent catalytic exchange device 1 and the downstream micro gas-liquid countercurrent catalytic exchange device 1' are both 100 mm, the spiral structure diameters are both 1.0 mm, the spiral gaps are both 0.25 mm, and the cross-sections are both circular; the catalysts 107 and the downstream catalyst 107' are both platinum-loaded nanoparticles with a particle size of 30 nm, which are respectively loaded on the inner walls of the microchannel 101 and the downstream microchannel 101'; during the whole process, the temperature in the microchannel 101 and the downstream microchannel 101' is maintained at 50 °C through a heating device.

[0040] The tritium activity concentration is 3.2×10 5Tritiated heavy water with an activity concentration of 1 Bq / L and a flow rate of 10 μL / min flows into the post-stage microchannel 101' through the post-stage liquid feed pipe 104' of the post-stage catalytic exchange device 1'. After flowing downward through the post-stage fluid constraint structure 106', it flows into the electrolytic cell 2 from the post-stage liquid discharge pipe 105'. The hydrogen gas generated after electrolysis enters the post-stage microchannel 101' from the electrolytic cell 2 through the post-stage gas feed pipe 102'. After participating in the catalytic exchange reaction of hydrogen-water isotopes in the post-stage microchannel 101', it escapes from the post-stage gas discharge pipe 103' and enters the microchannel 101 through the gas feed pipe 102 of the micro-miniature gas-liquid countercurrent catalytic exchange device 1. After the catalytic exchange reaction of hydrogen-water isotopes is carried out again, it enters the hydrogen-oxygen recombiner 3 from the gas discharge pipe 103 to complete the hydrogen-oxygen recombination. The tritium-depleted heavy water generated after the hydrogen-oxygen recombination is withdrawn at a flow rate of 8 μL / min. The unwithdrawn liquid enters the microchannel 101 through the liquid feed pipe 104 of the micro-miniature gas-liquid countercurrent catalytic exchange device 1 to participate in the catalytic exchange reaction of hydrogen-water isotopes, and then flows out from the liquid discharge pipe 105 and into the post-stage microchannel 101' through the liquid feed pipe 104' of the post-stage micro-miniature gas-liquid countercurrent catalytic exchange device 1' to participate in the reaction in this cycle.

[0041] After the above process, the treated tritium-rich heavy water is withdrawn from the post-stage liquid discharge pipe 105' at a flow rate of 2 μL / min, and the activity concentration of tritium in it is 8.6×10 5 Bq / L, and the height equivalent to a theoretical plate is 4.9 cm.

[0042] The present invention has been described in detail above in combination with specific embodiments and exemplary examples. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments; the above description should not be construed as a limitation of the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention; the protection scope of the present invention is subject to the appended claims.

Claims

1. A micro gas-liquid countercurrent catalytic exchange device for tritium water treatment, characterized in that: The invention comprises a microchannel, a gas feed pipe, a gas discharge pipe, a liquid feed pipe, a liquid discharge pipe, a fluid restraint structure and a catalyst; the gas feed pipe and the gas discharge pipe are respectively arranged on opposite sides of the microchannel, and the gas feed pipe is connected to the lower part of the microchannel, and the gas discharge pipe is connected to the upper part of the microchannel; the liquid feed pipe is connected to the center of the top cross section of the microchannel, and the liquid discharge pipe is connected to the center of the bottom cross section of the microchannel, so that the reaction gas and the reaction liquid entering the microchannel form countercurrent contact inside the microchannel; The fluid constraint structure is fixed inside the microchannel and connected to a liquid feed pipe and a liquid discharge pipe to guide the liquid to flow along the surface of the fluid constraint structure; the catalyst is fixed inside the microchannel, the reaction gas undergoes a catalytic exchange reaction on the catalyst surface, and a gas-liquid mass transfer process occurs on the surface of the fluid constraint structure.

2. The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment according to claim 1 is characterized in that: The fluid restraining structure is a spiral structure with a length of 50 to 1000 mm, a diameter of 0.05 to 30 mm, a spiral gap of 0.01 to 5 mm, and a spiral cross-sectional shape including a circle or a rectangle, constraining the liquid to form a stable flow in the spiral gap and the spiral structure surface.

3. The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment according to claim 2 is characterized in that: The fluid constraint structure is placed coaxially with the microchannel and does not contact the inner wall of the microchannel; the catalyst is particles containing platinum, nickel, etc. that can catalyze hydrogen-water isotope exchange reactions, with a particle size of 1nm to 500μm, and is loaded on the inner wall of the microchannel by adhesion or deposition.

4. The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment according to claim 2 is characterized in that: The fluid constraint structure is formed on the inner wall of the microchannel by adhesion or etching. The catalyst is a porous rod-shaped material containing platinum, nickel, etc. that can catalyze hydrogen-water isotope exchange reactions. The rod-shaped material has a length of 50 to 1000 mm and a pore size of 1 to 500 nm. The catalyst is fixed inside the microchannel and does not contact the inner wall of the microchannel.

5. The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment according to claim 1 is characterized in that: The microchannel can be heated and temperature-controlled by a heating device.

6. The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment according to claim 5, characterized in that: The heating device comprises a heating plate or a heating belt.

7. The micro gas-liquid countercurrent catalytic exchange device for tritium water treatment according to any one of claims 1 to 6, characterized in that: The micro gas-liquid countercurrent catalytic exchange device is arranged as a single stage or a cascade stage.

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