A multi-phase carbon dioxide decontamination recovery system and decontamination recovery process

Abstract

The present application relates to the technical field of nuclear facility decontamination, and provides a multi-phase carbon dioxide decontamination recovery system and a decontamination recovery process, the decontamination recovery system comprising a dry ice supply loop, a high-pressure CO2 supply loop, a decontamination loop and a CO2 recovery loop; the dry ice supply loop and the high-pressure CO2 supply loop are both communicated with the decontamination loop; the decontamination loop is communicated with the CO2 recovery loop at the end; the decontamination recovery process comprises the following steps: using ethanol or acetone as a carrier, using supercritical carbon dioxide to dissolve a decontaminant to soak and decontaminate a radioactive contaminated surface for pretreatment, using high-pressure carbon dioxide as power to carry dry ice particles to be sprayed out of a high-pressure nozzle to impact the radioactive contaminated surface, and realizing the recovery and utilization of carbon dioxide through two-stage pressure reduction separation and one-stage filtration; the present application can significantly improve the carbon dioxide radioactive decontamination capacity and efficiency, reduce the generation amount of secondary waste and reduce the radiation risk of personnel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear facility decontamination, in particular to a multi-phase carbon dioxide decontamination recovery system and decontamination recovery process. BACKGROUND

[0002] Nuclear facility decontamination is an activity that removes or reduces the presence of unwanted radionuclides from the surface of a target object using a suitable method. Nuclear facility decontamination plays an important role in the development of the nuclear industry. For in-service nuclear facilities, decontamination can reduce the level of on-site radioactivity and reduce personnel exposure dose. For decommissioned nuclear facilities, decontamination not only reduces personnel exposure dose, but also achieves waste degradation or even clean release, facilitating waste disposal and material recycling. However, the traditional decontamination method often has problems such as large amount of secondary waste, small decontamination factor, and low decontamination efficiency, which seriously restricts the development of the nuclear industry. Supercritical carbon dioxide and dry ice particles can be used to remove radioactive contamination, have the advantages of less secondary pollution, easy waste collection, and less damage to the object substrate, and are an important development direction for nuclear facility decontamination, having a very broad application prospect in the maintenance and decommissioning of nuclear facilities.

[0003] Dry ice decontamination is a method that uses mechanical force and thermal energy to enhance the removal of surface contamination of a target object. Compressed air is used as a power source to propel dry ice particles to the surface of the object to be decontaminated. The impact force, sublimation, and melting of the high-speed moving solid dry ice particles convert energy, allowing the contamination on the surface to be decontaminated to be quickly stripped and removed, and can remove dust and oil stains and other non-fixed contamination. Supercritical carbon dioxide (P>7.38MPa, T>31.19℃) has diffusion properties similar to a gas and solubility similar to a liquid, and can be used as a solvent to directly dissolve or dissolve the target object through a cleaning agent, and then remove the target object by pressure reduction separation to achieve the purpose of decontamination. The kinetic energy provided by the carrier medium of ordinary dry ice decontamination is not high, making it difficult to remove fixed contamination, and it is difficult to recover carbon dioxide after decontamination. Supercritical carbon dioxide has been used in drug extraction and device cleaning in the general industrial field, but its ability to decontaminate radioactive contamination is insufficient and has not been well applied in the field of nuclear industry decontamination.

[0004] To enhance the decontamination ability of carbon dioxide, reduce the discharge of secondary waste, and improve the recovery rate of decontamination agents, the advantages of dry ice decontamination and supercritical carbon dioxide are combined, and a multi-phase carbon dioxide decontamination recovery system and decontamination recovery process are proposed. SUMMARY

[0005] The present application provides a multi-phase carbon dioxide decontamination recovery system and decontamination recovery process, which can significantly improve the carbon dioxide radioactive decontamination capacity and efficiency, reduce the generation of secondary waste, and reduce the radiation risk of personnel.

[0006] The embodiments of the present application are implemented by the following technical solutions:

[0007] A multi-phase carbon dioxide decontamination recovery system comprises a dry ice supply circuit, a high-pressure CO2 supply circuit, a decontamination circuit and a CO2 recovery circuit; the ends of the dry ice supply circuit and the high-pressure CO2 supply circuit are communicated with the decontamination circuit; and the end of the decontamination circuit is communicated with the CO2 recovery circuit.

[0008] The dry ice supply circuit comprises a dry ice granulator and a dry ice storage and conveying device; the dry ice is manufactured by the dry ice granulator, then is conveyed to the dry ice storage and conveying device for storage through a pipeline, and is supplied to the ejector of the downstream decontamination circuit;

[0009] The high-pressure CO2 supply circuit comprises a CO2 storage tank for storing liquid CO2 and a first buffer tank; one end of the discharge pipe of the CO2 storage tank is communicated with the dry ice granulator, and the other end is communicated with the first buffer tank; and the end of the first buffer tank is communicated with the ejector of the decontamination circuit.

[0010] The decontamination circuit comprises an ejector and a decontamination container; the inlet ends of the ejector are communicated with the dry ice storage and conveying device and the first buffer tank respectively, and are used for mixing the dry ice in the dry ice storage and conveying device and the high-pressure CO2 fluid to form high-speed fluid jetting to the sample to be treated for decontamination; and the decontamination container is used for placing the sample and containing the CO2 fluid.

[0011] The CO2 recovery circuit comprises a separator, a filter, a second buffer tank and a cooler which are communicated in sequence; the feed end of the separator is communicated with the decontamination container, and the discharge end of the cooler is provided with a recovery circuit; and a booster pump for pressurizing and supplying CO2 to the CO2 storage tank is arranged on the recovery circuit.

[0012] The present application also provides a multi-phase carbon dioxide decontamination recovery process, which comprises the following steps:

[0013] (1) The dry ice and high-pressure CO2 fluid are sent to the ejector by the dry ice supply circuit and the high-pressure CO2 supply circuit for mixing, the CO2 is maintained in a supercritical state, and high-speed fluid jetting is formed to the sample to be treated placed in the decontamination container for decontamination;

[0014] (2) using ethanol or acetone as an entraining agent, using supercritical state carbon dioxide to carry the entraining agent to dissolve the decontaminant to soak the sample to be treated placed in the decontamination container for pre-treatment;

[0015] Meanwhile, under the stirring action of the stirrer in the decontamination container, using high-pressure carbon dioxide as power, carrying dry ice particles to be sprayed from the high-pressure nozzle to impact the surface of the sample to be treated to remove the radioactive contaminant on the surface of the sample to be treated;

[0016] (3) the CO2 recovery loop separator, filter, second buffer tank, cooler for decontamination of the decontamination container generated CO2 gas and solid pollutants two-stage pressure reduction separation and one-stage filtration, realizing the recycling of carbon dioxide.

[0017] The technical scheme of the embodiment of the present application has at least the following advantages and beneficial effects:

[0018] 1. The present application solves the problem of low carbon dioxide removal and low efficiency of fixed radioactive contamination, provides multiple decontamination methods to make the decontamination more thorough, and solves the problem of large amount of carbon dioxide emission by ordinary dry ice decontamination which cannot be recycled. By using the present application, through supercritical soaking, multi-phase state spraying and other decontamination methods, various degrees of pollution can be removed, including surface pollution and deeper fixed pollution.

[0019] 2. The present application greatly reduces the generation of secondary pollutants, reduces carbon dioxide emissions, and reduces the difficulty of waste collection and treatment. The CO2 used can be recycled, improving the cleanliness of the decontamination environment, reducing the risk of internal radiation and suffocation of the operator, and significantly reducing the decontamination cost, which is of great significance to improve the level of nuclear facility decommissioning in China. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0021] Figure 1 The multi-phase state carbon dioxide decontamination and recovery system schematic diagram provided for the embodiment 1 of the present application;

[0022] Figure 2 The multi-phase state carbon dioxide decontamination and recovery process flow chart provided for the embodiment 1 of the present application;

[0023] Icon: 1-steel cylinder, 2-dry ice granulator, 3-dry ice storage conveying device, 4-boosting pump, 5-first buffer tank, 6-ejector, 7-decontamination container, 8-separator, 9-filter, 10-second buffer tank, 11-cooler, 12-boosting pump, 13-CO2 storage tank, 14-pressure regulating valve, 15-circulation pump, 16-dosing device, 17-circulation pipeline. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturers are adopted. If the reagents or instruments used are not specified by the manufacturers, they are all conventional products that can be purchased in the market.

[0025] It should be noted that the various chemical equipment described in the embodiments can be selected from the corresponding equipment commonly used in the art, and the present application does not make any limitation. For example, the storage conveying device is a conventional storage tank, the separator is a separator commonly used in the chemical field, and the stirrer is a stirrer commonly used in the chemical field.

[0026] A multi-phase carbon dioxide decontamination recovery system and a decontamination recovery process provided by the embodiments of the present application will be described in detail below.

[0027] A multi-phase carbon dioxide decontamination recovery system, comprising: a dry ice supply loop, a high-pressure CO2 supply loop, a decontamination loop and a CO2 recovery loop;

[0028] The dry ice supply loop is used to manufacture dry ice and supply dry ice particles to the ejector; the dry ice supply loop comprises: a dry ice granulator 2, a dry ice storage conveying device 3; the front end of the dry ice granulator is communicated with a steel cylinder 1, dry ice particles are manufactured by the dry ice granulator, then the dry ice is conveyed to the dry ice storage conveying device 3 for storage through a pipeline, and the dry ice is supplied to the downstream ejector 6; wherein the conveying device has the ability to adjust the dry ice conveying flow;

[0029] In addition, the dry ice granulator 2, the dry ice storage conveying device 3, the ejector 6 and the decontamination container 7 are connected in a closed manner to ensure the manufacture, transmission and supply of dry ice under closed environmental conditions. A micro-positive pressure carbon dioxide is introduced into the bypass of the dry ice granulator 2 to prevent air from entering the system during the manufacture, transmission and storage process.

[0030] The high-pressure CO2 supply circuit is used for providing high-pressure CO2, and mainly comprises a CO2 storage tank 13, a booster pump 4, a first buffer tank 5, a pressure regulating valve 14, and instruments, etc. The steel cylinder 1 and the CO2 storage tank 13 are used for storing liquid CO2, and the users thereof are the downstream dry ice granulator 2 and the booster pump 4. The booster pump 4 pressurizes the fluid from the steel cylinder 1 or the CO2 storage tank 13 to a specified pressure for use in the decontamination circuit. The first buffer tank 5 is used for storing high-pressure CO2, providing sufficient CO2 capacity for the jet decontamination circuit, and maintaining CO2 in a supercritical state. The pressure regulating valve 14 is used for regulating the pressure before the decontamination circuit, and can realize the regulation of gaseous, liquid, and supercritical CO2.

[0031] The decontamination circuit is an execution part of sample decontamination, and mainly comprises two decontamination modes of jet decontamination and immersion decontamination, and specifically comprises a jet decontaminator 6, a decontamination container 7, and corresponding pipelines, valves, and instruments. The jet decontaminator 6 is in communication with the dry ice storage and conveying device 3 and the first buffer tank 5, and is used for mixing high-pressure CO2 fluid from the upstream with dry ice to form high-speed fluid jet to the sample for decontamination. The decontamination container 7 is used for placing the sample and containing the CO2 fluid, and contains a magnetic stirrer, is externally connected with a bypass circuit, and can realize the functions of jet decontamination, immersion decontamination, and stirring decontamination, and the combination thereof. The decontamination container 7 is further provided with a temperature regulator, a pressure regulator, and a sample fixing device, and has the functions of temperature regulation, pressure regulation, sample fixing, and adjustment. The decontamination process is in a closed environment, and has no influence on the external environment. In the jet decontamination, a low-pressure state is maintained in the interior, and in the immersion decontamination, a stable high-pressure state is maintained, so that CO2 is in a supercritical state. The decontamination container 7 is provided with a preheater outside the decontamination container 7 for providing heat preservation function for the container, and is provided with a lead shielding inside the decontamination container 7. A sample support is fixed inside the decontamination container 7, and is used for fixing the sample, adjusting the jet distance and angle of the sample, etc. A bypass circuit is further provided on one side of the decontamination container 7, and comprises a discharge pipe arranged at the bottom of the decontamination container 7 and a circulating pipeline in communication with one side of the discharge pipe. The end of the circulating pipeline is in communication with the decontamination container 7, and a circulating pump and a chemical feeder are arranged on the circulating pipeline. The local high-flow circulation decontamination of the decontamination container 7 is realized.

[0032] The CO2 recovery circuit is used for recovering used CO2, and mainly comprises a separator 8, a filter 9, a second buffer tank 10, a cooler 11, a booster pump 12 and related valves and instruments connected in sequence; specifically, the front end of the separator 8 is communicated with the decontamination container 7, and the separator 8 is used for separating CO2 gas and solid pollutants generated in decontamination; the filter is further separated to improve the purity of the recovered CO2; the second buffer tank 10 is used for collecting CO2 from the decontamination circuit to provide a certain storage capacity for CO2 recovery; the cooler 11 cools the gas to prepare for compression of the CO2 to a liquid state; the discharge end of the cooler 11 is provided with a recovery circuit, and the booster pump 12 is arranged on the recovery circuit, so that the CO2 is pressurized and supplied to the CO2 storage tank 13.

[0033] A multi-phase state carbon dioxide decontamination recovery process, comprising the following steps: in a supercritical state, using ethanol or acetone as an entrainer, using supercritical state carbon dioxide to carry the entrainer to dissolve sodium formate or ammonium salt decontaminant to soak the radioactive contaminated surface for decontamination pretreatment; at the same time, under the action of magnetic stirring, using high-pressure carbon dioxide as power to carry dry ice particles to spray from a high-pressure nozzle to impact the radioactive contaminated surface to realize radioactive pollution removal, and through two-stage pressure reduction separation and one-stage filtration, the carbon dioxide is recycled.

[0034] The pretreatment pressure during the soaking decontamination pretreatment is 7.38-30 MPa, and the treatment temperature is 31-80 DEG C; the working pressure of the high-pressure carbon dioxide is 0.1-20 MPa; in two-stage pressure reduction separation: the first-stage pressure reduction separation pressure is 15-20 MPa, the second-stage pressure reduction separation pressure is 5-15 MPa, and the working environment temperature is 0-45 DEG C.

[0035] More specifically, the multi-phase state carbon dioxide decontamination cycle process mainly comprises a multifunctional decontamination process and a carbon dioxide recycling process.

[0036] 1) Multifunctional decontamination process

[0037] a. Supercritical carbon dioxide soaking decontamination: liquid CO2 from the cylinder 1 and the CO2 storage tank 13 is supplied to the booster pump 4, the booster pump 4 increases the pressure of the CO2 to a supercritical pressure, and the CO2 is directly supplied to the decontamination container 7 through the bypass of the first buffer tank 5. The supercritical state is maintained in the decontamination container 7, the pressure in the container is maintained by the booster pump 4, the temperature is maintained at a suitable temperature by the water bath heating device of the decontamination container 7, and the sample surface pollutants are dissolved by the supercritical CO2, so that the pollutants are more easily removed.

[0038] b. Multi-phase carbon dioxide injection decontamination: liquid CO2 from the CO2 cylinder 1 is divided into two paths, one path is supplied to the dry ice granulator 2, and the dry ice produced is transported to the dry ice storage conveyor 3 through a closed loop, and the other path is supplied to the booster pump 4, which raises the CO2 pressure to the specified pressure and supplies it to the first buffer tank 5. When the injection starts, the CO2 fluid from the first buffer tank 5 is supplied to the injector 6 after being adjusted to the specified pressure by the pressure regulating valve 14 on the pipeline at the discharge end of the first buffer tank 5, and the dry ice from the dry ice storage conveyor 3 is supplied to the injector 6 after being adjusted by the flow regulating device, and the CO2 fluid carrying the dry ice is injected into the contaminated sample (i.e. the sample to be treated) to achieve the purpose of decontamination. The pressure-adjusted CO2 fluid can be in gaseous, liquid or supercritical state, and different states of fluid can be provided for injection cleaning according to the degree of sample contamination.

[0039] c. Stirring decontamination: the stirring device in the decontamination container 7 can provide stirring power to accelerate the circulation of fluid in the decontamination container 7 and flush away the surface contamination of the soaked sample.

[0040] 2) Carbon dioxide recycling process

[0041] The CO2 used in the decontamination container 7 is discharged to the downstream separator 8 to separate the CO2 gas and solid contaminants generated by decontamination; the filter 9 provides further separation to improve the purity of the recovered CO2; the separated and filtered CO2 is transmitted to the second buffer tank 10 to provide buffer for downstream equipment and has a certain storage capacity; the gas is cooled by the cooler 11, and then the CO2 is pressurized by the booster pump 12 and supplied to the CO2 storage tank 13 to complete the recovery of CO2.

[0042] The decontamination and recovery system of the present application has the functions of dry ice particle manufacturing, high-pressure carbon dioxide injection fluid generation, supercritical carbon dioxide decontamination environment construction, entraining agent and decontaminant injection, carbon dioxide and contaminant separation, etc., and utilizes solid, liquid, gaseous, supercritical state and other multiple phase carbon dioxide for chemical complexation and mechanical physical impact for combined decontamination; the decontamination and recovery process and the decontamination and recovery system of the present application can well realize supercritical carbon dioxide soaking decontamination, multi-phase carbon dioxide injection decontamination, stirring decontamination and combined decontamination process.

[0043] Example 1

[0044] The present embodiment provides a multi-phase carbon dioxide decontamination and recovery system and process, including various decontamination processes such as soaking decontamination, injection decontamination and stirring decontamination, as well as carbon dioxide recycling process, specifically including the following steps:

[0045] 1) Dry ice supply: Liquid CO2 from the steel cylinder 1, CO2 tank 13 is supplied to the dry ice granulator 2 for the manufacture of dry ice particles, and the manufactured dry ice is transported to the storage and transport device 3 for storage and transport of dry ice to the sprayer 6, which can realize direct processing and supply of dry ice, the dry ice supply pipeline is sealed, the internal micro-positive pressure can ensure the purity of dry ice and carbon dioxide, and the transport device 3 can automatically adjust the dry ice transport rate to change the flow rate during spraying.

[0046] 2) Carbon dioxide pressure boosting and state adjustment: Liquid CO2 from the steel cylinder 1, CO2 tank 13 is supplied to the booster pump 4, and the booster pump 4 raises the CO2 pressure. Through the cooperation of the booster pump 4, the first buffer tank 5, and the pressure regulating valve 14, gaseous, liquid, and supercritical state CO2 can be generated for downstream soaking decontamination or spraying decontamination.

[0047] 3) Soaking decontamination: Liquid CO2 from the steel cylinder 1, CO2 tank 13 is supplied to the booster pump 4, and the booster pump 4 raises the CO2 pressure to supercritical pressure, which is directly supplied to the decontamination container 7 through the bypass of the first buffer tank 5. The supercritical state is maintained in the decontamination container 7, the pressure in the container is maintained by the booster pump 4, and the appropriate temperature is maintained by the water bath heating device of the decontamination container 7. If necessary, chemical reagents can be added through the circulating pump 31 and the dosing system for pretreatment. Specifically, ethanol or acetone is used as a carrier to dissolve the decontamination agent in the supercritical state of carbon dioxide to soak the sample placed in the decontamination container 7 for soaking decontamination pretreatment. The pretreatment pressure is 15 MPa, and the treatment temperature is 50°C. The supercritical CO2 soaking dissolves the surface contaminants of the sample, making it easier to remove the contaminants.

[0048] 4) Spraying decontamination: Liquid CO2 from the steel cylinder 1, CO2 tank 13 is divided into two paths, one path is supplied to the dry ice granulator 2, and the manufactured dry ice is transported to the dry ice storage and transport device 3 through a closed loop, and the other path is supplied to the booster pump 4, which raises the CO2 pressure to a specified pressure and supplies it to the first buffer tank 5. When the spraying starts, the CO2 fluid from the first buffer tank 5 is adjusted to 10 MPa by the pressure regulating valve 14 and then supplied to the sprayer 6, and the dry ice from the dry ice storage and transport device 3 is adjusted by the flow regulating device and then supplied to the sprayer 6. The sprayer 6 sprays the contaminated sample with the CO2 fluid carrying the dry ice through the spraying interface to achieve the purpose of decontamination. The adjusted CO2 fluid can be in gaseous, liquid, or supercritical state, and different states of fluid can be provided for spraying cleaning according to the degree of sample contamination.

[0049] 5) Stirring decontamination: The stirring device (any conventional stirring device in the art can be used, and the present application does not limit it) of the decontamination container 7 can provide stirring power to accelerate the circulation of fluid in the container and flush away the surface contaminants of the soaked sample.

[0050] 6) Recycling: The CO2 used in the decontamination container 7 is discharged to the downstream separator 8, which separates the CO2 gas and solid contaminants generated by decontamination; when the separator 8 is separated: the pressure reduction separation pressure is 15 MPa, and the working environment temperature is 25℃; then sent to the filter 9 for further separation, the pressure reduction separation pressure is 10 MPa, to improve the purity of the recovered CO2; the separated and filtered CO2 is transmitted to the second buffer tank 10 to provide buffering for downstream equipment and has a certain storage capacity; the gas is cooled by the cooler 11, and then the CO2 is pressurized by the booster pump 12 to supply the CO2 storage tank 13, completing the recovery of CO2.

[0051] After the treatment method of this embodiment is processed, the removal rate of loose contamination of surface radioactivity is 99.99%; the decontamination rate of rust injection is 98.6%, and the decontamination efficiency is 0.06m 2 / min; the decontamination rate of oil injection is 90.8%, and the decontamination efficiency is 0.07m 2 / min; the carbon dioxide recovery rate reaches 86%.

[0052] Example 2

[0053] The difference between this embodiment and Example 1 is:

[0054] In step 3), the pretreatment pressure for immersion decontamination is 20 MPa, and the treatment temperature is 60℃

[0055] In step 4), the injection decontamination is supplied to the injector after being adjusted to 5 MPa by the pressure regulating valve.

[0056] In step 6), the pressure reduction separation pressure of the separator is 16 MPa, and the working environment temperature is 15℃; then sent to the filter for further separation, the pressure reduction separation pressure is 5 MPa.

[0057] After the treatment method of this embodiment is processed, the removal rate of loose contamination of surface radioactivity is 99.98%; the decontamination rate of rust injection is 98.5%, and the decontamination efficiency is 0.05m 2 / min; the decontamination rate of oil injection is 90.9%, and the decontamination efficiency is 0.06m 2 / min; the carbon dioxide recovery rate reaches 85%.

[0058] Example 3

[0059] The difference between this embodiment and Example 1 is:

[0060] In step 3), the pretreatment pressure for immersion decontamination is 30 MPa, and the treatment temperature is 70℃

[0061] In step 4), the injection decontamination is supplied to the injector after being adjusted to 18 MPa by the pressure regulating valve.

[0062] In the recycling in step 6), the pressure of pressure reduction separation of the separator is 20 MPa, and the working environment temperature is 30℃; then the product is sent to a filter for further separation, and the pressure of pressure reduction separation is 15 MPa.

[0063] After the treatment method in the embodiment is used, the removal rate of loose contamination on the surface is 99.99%, the decontamination rate of rust spraying is 98.8%, the decontamination efficiency is 0.07 m / min, the decontamination rate of oil stain spraying is 90.7%, the decontamination efficiency is 0.07 m / min, and the recovery rate of carbon dioxide is 88%. 2 2 The whole process of the embodiment can realize multifunctional decontamination, makes the decontamination more thorough, realizes the recycling of CO2, greatly reduces the secondary waste emission, and significantly reduces the decontamination cost.

[0064] The whole process of the embodiment can realize multifunctional decontamination, makes the decontamination more thorough, realizes the recycling of CO2, greatly reduces the secondary waste emission, and significantly reduces the decontamination cost.

[0065] The above is only the preferred embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A multiphase carbon dioxide decontamination and recovery process, characterized in that: A multiphase carbon dioxide decontamination and recovery system is used; the multiphase carbon dioxide decontamination and recovery system includes a dry ice supply circuit, a high-pressure CO2 supply circuit, a decontamination circuit, and a CO2 recovery circuit; the ends of the dry ice supply circuit and the high-pressure CO2 supply circuit are both connected to the decontamination circuit; the end of the decontamination circuit is connected to the CO2 recovery circuit. The dry ice supply circuit includes: a dry ice granulator and a dry ice storage and conveying device; dry ice is produced by the dry ice granulator, and then transported to the dry ice storage and conveying device for storage through pipelines, and the dry ice is supplied to the injectors of the downstream decontamination circuit; The high-pressure CO2 supply circuit includes: a CO2 storage tank for storing liquid CO2 and a first buffer tank; one end of the discharge pipe of the CO2 storage tank is connected to the dry ice granulator, and the other end is connected to the first buffer tank; the end of the first buffer tank is connected to the ejector of the decontamination circuit. The decontamination circuit includes: an ejector and a decontamination container; the inlet end of the ejector is connected to a dry ice storage and conveying device and a first buffer tank respectively, and is used to mix the dry ice in the dry ice storage and conveying device and the first buffer tank with high-pressure CO2 fluid to form a high-speed fluid that is sprayed onto the surface of the sample to be treated for decontamination; the decontamination container is used to place the sample and contain the CO2 fluid. The CO2 recovery circuit includes a separator, a filter, a second buffer tank, and a cooler connected in sequence; the feed end of the separator is connected to the decontamination container, and the discharge end of the cooler is provided with a recovery circuit, which is equipped with a booster pump for pressurizing and supplying CO2 to the CO2 storage tank. The decontamination and recovery process of the multiphase carbon dioxide decontamination and recovery system includes the following steps: (1) Dry ice and high-pressure CO2 fluid are sent to the ejector for mixing using a dry ice supply circuit and a high-pressure CO2 supply circuit, and a high-speed fluid is sprayed onto the surface of the sample to be treated placed in the decontamination container for decontamination. (2) Supercritical carbon dioxide is directly supplied to the decontamination container by the bypass of the first buffer tank of the high-pressure CO2 supply circuit. Ethanol or acetone is used as the entrainer. The supercritical carbon dioxide carries the entrainer to dissolve the decontaminant and soaks the sample to be treated in the decontamination container for decontamination pretreatment. Meanwhile, the sample is stirred in the decontamination container and driven by high-pressure carbon dioxide to carry dry ice particles out of the high-pressure nozzle to impact the surface of the sample and remove radioactive contaminants from the surface of the sample. (3) The CO2 gas and solid pollutants generated in the decontamination container are separated by two stages of pressure reduction and filtered by one stage through the separator, filter, second buffer tank and cooler of the CO2 recovery loop to realize the recovery and utilization of carbon dioxide. The pretreatment pressure during the soaking and decontamination pretreatment is 7.38MPa-30MPa, and the treatment temperature is 31℃-80℃.

2. The multiphase carbon dioxide decontamination and recovery process according to claim 1, characterized in that, The dry ice granulator, dry ice storage and conveying device, ejector, and decontamination container are connected in a sealed manner.

3. The multiphase carbon dioxide decontamination and recovery process according to claim 1, characterized in that, A booster pump is installed on the pipeline connecting the CO2 storage tank and the first buffer tank; a pressure regulating valve is installed on the pipeline connecting the first buffer tank and the injector.

4. The multiphase carbon dioxide decontamination and recovery process according to claim 1, characterized in that, The decontamination container is equipped with a stirrer, and a bypass circuit is connected to the outside of the decontamination container for localized high-flow-rate circulating decontamination.

5. The multiphase carbon dioxide decontamination and recovery process according to claim 1, characterized in that, The decontamination container is also equipped with a temperature regulator, a pressure regulator, and a sample fixing device.

6. The multiphase carbon dioxide decontamination and recovery process according to claim 4, characterized in that, The bypass circuit includes a discharge pipe located at the bottom of the decontamination container and a circulation pipe connected to one side of the discharge pipe. The end of the circulation pipe is connected to the inner cavity of the decontamination container, and a circulation pump and a dosing device are installed on the circulation pipe.

7. The multiphase carbon dioxide decontamination and recovery process according to claim 1, characterized in that, The working pressure of the high-pressure carbon dioxide is 0.1MPa-20MPa.

8. The multiphase carbon dioxide decontamination and recovery process according to claim 1, characterized in that, In two-stage pressure reduction separation: the first-stage pressure reduction separation pressure is 15MPa-20MPa, the second-stage pressure reduction separation pressure is 5MPa-15MPa, and the operating ambient temperature is 0-45℃.

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