A device for wet oxidation of radioactive waste resin

Abstract

The present invention relates to a device for wet oxidation of radioactive waste resin. The device for wet oxidation of radioactive waste resin provided by the present invention is used to add an oxidant into a reactor by a continuous feeding method of a constant flow pump, so that the waste resin is oxidized and degraded in a sealed negative pressure system under certain temperature and stirring conditions, thereby preventing radioactive leakage; at the same time, the tail gas generated in the reaction process is led out of the reactor by a vacuum pump, and the gas and water are separated after cooling by a condenser, and the condensate is refluxed into the reactor or collected in a liquid collecting bottle. After the non-condensable gas is metered, it flows through a first-level gas washing bottle to remove the trace radioactive nuclides and inorganic acidic gases carried by the non-condensable gas, and then passes through a catalytic decomposition furnace to thoroughly oxidize and remove harmful gases in the non-condensable gas, and finally passes through a second-level gas washing bottle for safe discharge. The present invention adopts a two-stage gas washing device and a tail gas treatment process such as catalytic oxidation to recover the nuclides carried in the tail gas to the greatest extent, thereby ensuring the clean discharge of the tail gas.

Description

Technical Field

[0001] The invention belongs to the technical field of radioactive waste treatment, and in particular relates to a device for wet oxidation of radioactive waste resin. Background Art

[0002] The safe treatment of organic radioactive waste resin is still one of the difficulties and hot spots in the management of radioactive waste in China. Waste resin produced by domestic nuclear facilities is mostly treated by traditional cement solidification process, which has technical bottlenecks such as waste volume expansion and insufficient long-term stability of solidified bodies.

[0003] At present, China is conducting research on inorganic reduction technology for radioactive waste resin, including wet oxidation, supercritical water oxidation, steam reforming, etc. Wet oxidation of waste resin is a process in which waste resin is oxidized by oxidant H2O2 at low temperature (less than 100°C). 2 O 2 Fully oxidized to H 2 O、CO 2 and low-salt inorganic waste liquid. The waste liquid can be treated by cement solidification / drying / nuclides purification to achieve inorganic reduction of waste resin. Compared with other inorganic treatment processes for waste resin, the wet oxidation process has mild reaction conditions and can be compatible with the treatment of different types of waste resins. The tail gas composition is simple and easy to handle. Radioactive nuclides (except 14 C) are all retained in the inorganic waste liquid, and the process is economical and safe.

[0004] In response to the current domestic technical needs and gaps, the inventors designed and established a radioactive waste resin wet oxidation device based on the needs of research on the waste resin wet oxidation process. Summary of the invention

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a radioactive waste resin wet oxidation device to establish a waste resin wet oxidation device suitable for conducting wet oxidation process research, to achieve inorganic volume reduction treatment of different types of waste resins, and at the same time ensure the clean emission of exhaust gas.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a radioactive waste resin wet oxidation device, including a feeding unit, an oxidation degradation unit, a tail gas treatment unit and corresponding valves and connecting pipes, wherein:

[0007] The feeding unit includes a feeding mechanism and equipment for conveying waste resin, catalyst, inhibitor and oxidant into the reactor;

[0008] The oxidation degradation unit includes the reactor, a heater, a stirring motor, a stirring paddle, a temperature sensor, and a pressure sensor;

[0009] The tail gas treatment unit includes a condenser, a flow meter, a primary gas washing bottle, a catalytic decomposition furnace, a secondary gas washing bottle, and a vacuum pump; the condenser is connected to the reactor, and the non-condensable gas in the condenser enters the primary gas washing bottle for absorption and purification with alkali solution after being measured by the flow meter, and then enters the catalytic decomposition furnace; the tail gas after catalytic decomposition enters the secondary gas washing bottle for further absorption and purification with alkali solution.

[0010] Furthermore, the feed unit includes two ball valves, and the inhibitor is added into the reactor through the additive feed port on the reactor cover by means of a metering mechanism composed of the two ball valves and a pipeline;

[0011] The inhibitor feeding method is a fixed volume intermittent feeding method.

[0012] Furthermore, the feeding unit includes a pump, and the oxidant is fed into the reactor through a feed port on the reactor cover in a continuous feeding manner at a constant flow rate by means of the pump;

[0013] The pump is selected from one of a peristaltic pump, a diaphragm metering pump and a gear metering pump.

[0014] Furthermore, the reactor is a jacketed reactor, and a heat medium is introduced into the jacket of the reactor to provide the reaction temperature required for the reaction;

[0015] The heat medium is low-pressure steam, hot water or heat transfer oil;

[0016] After the heat medium is heated by the heater, it is driven by a circulation pump to circulate through the jacket of the reactor in a bottom-in and top-out manner.

[0017] Furthermore, the temperature sensor is inserted into the material in the reactor through the reactor cover to continuously monitor the temperature of the material in the reactor in real time;

[0018] The pressure sensor is installed on the reactor cover to continuously monitor the pressure change in the reactor in real time.

[0019] Furthermore, the stirring motor is a variable frequency stirring motor, and the stirring paddle is connected to the output shaft of the variable frequency stirring motor through a coupling;

[0020] The stirring paddle blade at the end of the stirring paddle is kept at a safe distance from the bottom of the reactor to prevent affecting the stirring.

[0021] Furthermore, the tail gas treatment unit also includes at least two one-way valves, and a one-way valve is provided upstream of the first-stage scrubbing bottle and upstream of the second-stage scrubbing bottle to prevent the liquid in the scrubbing bottle from flowing back under the negative pressure in the upstream container.

[0022] Furthermore, the tail gas treatment unit also includes a water chiller, and the refrigerant in the condenser is circulating cooling water in a bottom-in and top-out manner;

[0023] The cooling water circulates through the condenser and the chiller to cool the tail gas discharged from the reactor.

[0024] Furthermore, the tail gas treatment unit further comprises a liquid collecting bottle, and the condensate in the condenser flows back into the reactor or is collected in the liquid collecting bottle.

[0025] Furthermore, the vacuum pump is connected to the secondary gas washing bottle, and the radioactive waste resin wet oxidation device is regulated to operate under a negative pressure within a set range through a pressure regulating valve of the vacuum pump.

[0026] The beneficial effects of the present invention are as follows: by using the radioactive waste resin wet oxidation device provided by the present invention, an oxidant is added to the reactor by a continuous feeding method of a constant flow pump, and an inhibitor is added to the reactor by an intermittent feeding method of a constant volume, so that the waste resin is oxidized and degraded in a sealed negative pressure system under a certain temperature and stirring condition, thereby preventing radioactive leakage; at the same time, the tail gas generated during the reaction process is led out of the reactor by a vacuum pump, and the gas and water are separated after cooling by a condenser, and the condensate is refluxed to the reactor or collected in a liquid collecting bottle, and the non-condensable gas is metered and flows through a primary gas washing bottle to remove the trace radioactive nuclides and inorganic acidic gases carried by the non-condensable gas, and then passes through a catalytic decomposition furnace to thoroughly oxidize and remove harmful gases in the non-condensable gas, and finally passes through a secondary gas washing bottle for safe discharge. A one-way valve is provided upstream of the primary gas washing bottle and the secondary gas washing bottle provided by the present invention to prevent the liquid in the gas washing bottle from flowing back under the negative pressure in the upstream container. The present invention aims at the extremely small amount of nuclides that may be carried in the tail gas, adopts tail gas treatment processes such as a two-stage scrubber and catalytic oxidation, recovers the nuclides carried in the tail gas to the greatest extent, and ensures the clean discharge of the tail gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a radioactive waste resin wet oxidation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0029] like Figure 1 As shown, an embodiment of the present invention provides a radioactive waste resin wet oxidation device, the device comprising a feeding unit, an oxidation degradation unit and a tail gas treatment unit; wherein,

[0030] (1) Feeding unit

[0031] The feeding unit includes a feeding mechanism and equipment for conveying materials such as waste resin, catalyst, inhibitor and oxidant into the reaction kettle 2.

[0032] In this embodiment, the waste resin and the catalyst solution are weighed and mixed in proportion in advance, and the mixed waste resin and catalyst solution are added into the reactor 2 at one time from the feed port on the reactor cover 21; the inhibitor is added into the reactor 2 through the additive feed port on the reactor cover 21 through a metering mechanism composed of two ball valves and a pipeline, and is added in a fixed volume intermittent feeding manner; the oxidant is added into the reactor 2 through the feed port on the reactor cover 21 by a pump in a fixed flow continuous feeding manner, and the pump can be a peristaltic pump, a diaphragm metering pump, a gear metering pump, etc. In this embodiment, a peristaltic pump 1 is used to continuously feed into the reactor 2 through the feed port on the reactor cover 21.

[0033] (2) Oxidative degradation unit

[0034] The oxidative degradation unit includes a reaction kettle 2, a heater 23, a stirring motor and a stirring paddle, a temperature sensor 24, a pressure sensor 25, and corresponding valves, connecting pipes and other equipment and components.

[0035] In this embodiment, the reactor 2 is a reactor with a jacket, and a heat medium is introduced into the reactor jacket 22 to provide the reaction temperature required for the reaction; the heat medium in the reactor jacket 22 can be low-pressure steam, hot water or thermal oil. After the heat medium is heated by the heater 23, it is driven by a circulation pump to circulate through the reactor jacket 22 in a bottom-in and top-out manner. The temperature sensor 24 is inserted into the material in the reactor through the reactor cover 21 to continuously monitor the temperature of the material in the reactor in real time; the pressure sensor 25 is installed on the reactor cover 21 to continuously monitor the pressure change in the reactor in real time.

[0036] The stirring motor is a variable frequency stirring motor 26, and the stirring paddle is connected to the output shaft of the variable frequency stirring motor through a coupling; the variable frequency stirring motor 26 runs at a set speed, and the stirring paddle continuously stirs the materials in the reactor. The stirring paddle extends into the reactor through a reserved hole on the reactor cover, and the stirring paddle blade 27 at the end of the stirring paddle must have a certain safety distance from the bottom of the reactor to prevent affecting the stirring; the stirring paddle blade 27 at the end of the stirring paddle is made of polytetrafluoroethylene, and the stirring paddle shaft is made of stainless steel wrapped with polytetrafluoroethylene; it can ensure long-term stability and facilitate decontamination. The reactor discharge port located at the bottom of the reactor is used to collect the oxidation residual liquid.

[0037] (3) Exhaust gas treatment unit

[0038] The tail gas treatment unit includes a condenser 31, a chiller 32, a liquid collecting bottle 33, a flow meter 34, a one-way valve 35, a primary gas washing bottle 36, a catalytic decomposition furnace 37, a secondary gas washing bottle 38, a vacuum pump 39, and corresponding valves, connecting pipes and other equipment and components.

[0039] In this embodiment, the refrigerant in the condenser 31 is circulating cooling water in a bottom-in and top-out manner, and the cooling water circulates through the condenser 31 and the chiller 32 to cool the tail gas discharged from the reactor 2; the tail gas discharged from the reactor 2 is cooled by the condenser 31 and gas-liquid separation occurs, and the condensate in the condenser 31 flows back to the reactor 2 or is collected in the liquid collecting bottle 33, and the remaining non-condensable gas enters the primary gas washing bottle 36 for alkaline solution absorption and purification after being measured by the flow meter 34, and then enters the catalytic decomposition furnace 37; according to the process requirements, oxygen is added to the catalytic decomposition furnace 37 according to a certain proportion according to the flow rate of the non-condensable gas. After catalytic decomposition, the tail gas enters the secondary gas washing bottle 38 for further alkaline solution absorption and purification.

[0040] The vacuum pump 39 is connected to the secondary scrubbing bottle 38 and is arranged at the tail end of the radioactive waste resin wet oxidation device. The pressure regulating valve of the vacuum pump 39 is used to control the entire radioactive waste resin wet oxidation device to operate under a negative pressure within a preset range.

[0041] At the same time, one-way valves 35 are provided upstream of the primary washing bottle and the secondary washing bottle to prevent the liquid in the washing bottle from flowing back under the negative pressure in the upstream container.

[0042] The radioactive waste resin wet oxidation device provided in the embodiment of the present invention adopts a continuous feeding method of constant flow pumping to add an oxidant into the reactor 2, and adopts a fixed volume intermittent feeding method to add an inhibitor into the reactor 2. The waste resin is oxidized and decomposed under a certain temperature and stirring conditions. The tail gas generated in the reaction process is led out of the reactor 2 by a vacuum pump 39, and the gas and water are separated after cooling by a condenser 31. The condensate flows back to the reactor 2 or is collected in a liquid collecting bottle 33; the non-condensable gas is measured by a flow meter 34, and then flows through a primary gas washing bottle 36 to remove the trace radioactive nuclides and inorganic acidic gases carried by the non-condensable gas, and then the harmful gases in the non-condensable gas are thoroughly oxidized and removed by a catalytic decomposition furnace 37. The non-condensable gas is safely discharged after passing through a secondary gas washing bottle 38. A one-way valve 35 is set upstream of the primary gas washing bottle 36 and the secondary gas washing bottle 38 to prevent the liquid in the gas washing bottle from flowing back under the negative pressure in the upstream container. In addition, an air inlet is set before the vacuum pump 39 to adjust the pressure in the reactor 2.

[0043] The method described in the present invention is not limited to the specific embodiments described. The above embodiments are only examples of the present invention. The present invention can also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described embodiments should be regarded as illustrative rather than restrictive in any respect. The scope of the present invention should be described by the attached claims, and any changes equivalent to the intent and scope of the claims should also be included in the scope of the present invention.

Claims

1. A device for wet oxidation of radioactive waste resin, characterized in that: The device comprises a feed unit, an oxidation degradation unit, a tail gas treatment unit, and corresponding valves and connecting pipes, wherein: The feeding unit includes a feeding mechanism and equipment for conveying waste resin, catalyst, inhibitor and oxidant into the reactor; The oxidative degradation unit comprises the reaction kettle (2), a heater (23), a stirring motor, a stirring paddle, a temperature sensor (24), and a pressure sensor (25); The tail gas treatment unit comprises a condenser (31), a flow meter (34), a primary gas washing bottle (36), a catalytic decomposition furnace (37), a secondary gas washing bottle (38), and a vacuum pump (39); the condenser (31) is connected to the reaction kettle (2); the non-condensable gas in the condenser (31) is metered by the flow meter (34) and enters the primary gas washing bottle (36) for alkaline solution absorption and purification, and then enters the catalytic decomposition furnace (37); the tail gas after catalytic decomposition enters the secondary gas washing bottle (38) for further alkaline solution absorption and purification.

2. A radioactive waste resin wet oxidation device according to claim 1, characterized in that: The feed unit comprises two ball valves, and the inhibitor is added into the reactor (2) through the additive feed port on the reactor cover (21) by means of a metering mechanism composed of the two ball valves and a pipeline; The inhibitor feeding method is a fixed volume intermittent feeding method.

3. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The feeding unit comprises a pump, and the oxidant is fed into the reactor (2) through the feed port on the reactor cover (21) in a continuous feeding manner at a constant flow rate by means of the pump; The pump is selected from one of a peristaltic pump, a diaphragm metering pump and a gear metering pump.

4. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The reactor (2) is a jacketed reactor, and a heat medium is introduced into the reactor jacket (22) to provide the reaction temperature required for the reaction; The heat medium is low-pressure steam, hot water or heat transfer oil; After the heat medium is heated by the heater (23), it is driven by a circulation pump to circulate through the jacket (22) of the reactor in a bottom-in and top-out manner.

5. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The temperature sensor (24) is inserted into the material in the reactor through the reactor cover (21) to continuously monitor the temperature of the material in the reactor in real time; The pressure sensor (25) is installed on the reactor cover (21) to continuously monitor the pressure change in the reactor in real time.

6. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The stirring motor is a variable frequency stirring motor (26), and the stirring paddle is connected to the output shaft of the variable frequency stirring motor (26) via a coupling; The stirring paddle blade (27) at the end of the stirring paddle is kept at a safe distance from the bottom of the reaction kettle to prevent affecting the stirring.

7. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The tail gas treatment unit further comprises at least two one-way valves (35), wherein a one-way valve (35) is provided upstream of the first-stage scrubbing bottle (36) and upstream of the second-stage scrubbing bottle (38) to prevent the liquid in the scrubbing bottle from flowing back under the negative pressure in the upstream container.

8. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The tail gas treatment unit further comprises a water chiller (32), and the refrigerant in the condenser (31) is circulating cooling water in a bottom-in and top-out manner; The cooling water circulates through the condenser (31) and the chiller (32) to cool the tail gas discharged from the reactor.

9. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The tail gas treatment unit further comprises a liquid collecting bottle (33), and the condensate in the condenser (31) flows back into the reaction kettle (2) or is collected in the liquid collecting bottle (33).

10. The device for wet oxidation of radioactive waste resin according to claim 1, characterized in that: The vacuum pump (39) is connected to the secondary gas washing bottle (38), and the radioactive waste resin wet oxidation device is regulated to operate under a negative pressure within a set range through a pressure regulating valve of the vacuum pump (39).

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