Multiphase carbon dioxide decontamination recovery system and decontamination recovery process

Abstract

The invention relates to the technical field of nuclear facility decontamination, and provides a multiphase carbon dioxide decontamination recovery system and a decontamination recovery process, the decontamination recovery system comprises a dry ice supply loop, a high pressure CO2 supply loop, a decontamination loop and a CO2 recovery loop; the tail ends of the dry ice supply loop and the high-pressure CO2 supply loop are communicated with the decontamination loop; the tail end of the decontamination loop is communicated with the CO2 recovery loop; the decontamination recovery process comprises the following steps: taking ethanol or acetone as an entrainer, dissolving a decontaminating agent by using supercritical carbon dioxide to carry out soaking decontamination pretreatment on the radioactive contamination surface, taking high-pressure carbon dioxide as power, carrying dry ice particles and spraying out from a high-pressure spraying pipe to impact the radioactive contamination surface, and recycling the radioactive contamination surface. Recycling of carbon dioxide is realized through two-stage depressurization separation and first-stage filtration; the carbon dioxide radioactive decontamination capability and efficiency can be remarkably improved, the secondary waste generation amount is reduced, and the personnel irradiation risk is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear facility decontamination, and in particular to a multiphase carbon dioxide decontamination and recovery system and a decontamination and recovery process. Background Art

[0002] Radioactive decontamination of nuclear facilities is the activity of removing or reducing unwanted radionuclides from the surface of the target object by using appropriate methods. Nuclear facility decontamination plays an important role in the development of the nuclear industry. For in-service nuclear facilities, decontamination can reduce the radioactivity level on site and reduce the exposure dose to personnel. For decommissioned nuclear facilities, decontamination not only reduces the exposure dose to personnel, but also achieves waste downgrading and even clean release, which is convenient for waste disposal and material recycling. However, traditional decontamination methods often have problems such as large amount of secondary waste, small decontamination factor, and low decontamination efficiency, which seriously restrict the development of the nuclear industry. Supercritical carbon dioxide and dry ice particles can both be used to remove radioactive contamination. They have the advantages of less secondary pollution, easy waste collection, and little damage to the substrate of the object. They are an important development direction for nuclear facility decontamination and have very broad application prospects in the field of 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 the target object. Compressed air is used as the power to push dry ice particles to spray onto the surface of the object to be decontaminated. The impact force, sublimation, melting and other energy conversions of high-speed solid dry ice particles are used to quickly remove the contamination on the surface of the decontaminated object, and can remove non-fixed contamination such as dust and oil. Supercritical carbon dioxide (P>7.38MPa, T>31.19℃) has similar gas diffusivity and liquid solubility. It can be used as a solvent to directly dissolve or dissolve the target through a cleaning agent, and then remove the target through pressure reduction and separation to achieve the purpose of decontamination. The kinetic energy provided by the carrier medium of ordinary dry ice decontamination is not high, so it is difficult to remove fixed contamination, and it is difficult to recover carbon dioxide after decontamination. Supercritical carbon dioxide has been used for drug extraction and device cleaning in the general industrial field, but its ability to remove radioactive contamination is insufficient and has not been well applied in the field of nuclear industry decontamination.

[0004] In order to enhance the decontamination capacity of carbon dioxide, reduce secondary waste emissions and improve the recycling rate of decontaminants, the advantages of dry ice decontamination and supercritical carbon dioxide are comprehensively utilized, and the present invention proposes a multiphase carbon dioxide decontamination and recovery system and a decontamination and recovery process. Summary of the invention

[0005] In order to solve the problems of low carbon dioxide removal capacity and efficiency of fixed radioactive contamination, low decontaminant recovery rate and large secondary waste emission, the present invention provides a multiphase carbon dioxide decontamination and recovery system and a decontamination and recovery process, which can significantly improve the carbon dioxide radioactive decontamination capacity and efficiency, reduce the amount of secondary waste generated, and reduce the risk of personnel radiation.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] A multiphase carbon dioxide decontamination and recovery system, comprising 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;

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

[0009] 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 pelletizer, 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;

[0010] The decontamination circuit comprises: an ejector and a decontamination container; the inlet end of the ejector is respectively connected to the dry ice storage and conveying device and the first buffer tank, and is used to mix the dry ice in the dry ice storage and conveying device and the first buffer tank with the high-pressure CO2 fluid to form a high-speed fluid that is ejected onto the sample to be processed for decontamination; the decontamination container is used to place the sample and contain the CO2 fluid;

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

[0012] The present invention also provides a multiphase carbon dioxide decontamination and recovery process, comprising the following steps:

[0013] (1) using a dry ice supply circuit and a high-pressure CO2 supply circuit to deliver dry ice and high-pressure CO2 fluid to an ejector for mixing, maintaining CO2 in a supercritical state, and forming a high-speed fluid to be ejected onto a sample to be treated placed in a decontamination container for decontamination;

[0014] (2) using ethanol or acetone as an entrainer, using carbon dioxide in a supercritical state to carry the entrainer to dissolve the decontaminant to perform a soaking decontamination pretreatment on the sample to be treated placed in the decontamination container;

[0015] At the same time, under the stirring action of the stirrer in the decontamination container, high-pressure carbon dioxide is used as a power to carry dry ice particles and spray out from the high-pressure nozzle to impact the surface of the sample to be processed, thereby removing radioactive contaminants on the surface of the sample to be processed;

[0016] (3) The CO2 gas and solid pollutants generated by decontamination in the decontamination container are separated by two-stage pressure reduction and filtered by one-stage through the separator, filter, second buffer tank and cooler of the CO2 recovery loop to achieve the recovery and utilization of carbon dioxide.

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

[0018] 1. The present invention solves the problem of low ability and efficiency of carbon dioxide in removing radioactive fixed pollution, provides multiple decontamination methods to make decontamination more thorough, and solves the problem that ordinary dry ice decontamination emits a large amount of carbon dioxide that cannot be recovered. The present invention can remove various degrees of pollution, including surface pollution and deeper fixed pollution, through decontamination methods such as supercritical immersion and multiphase injection.

[0019] 2. The present invention greatly reduces the generation of secondary pollutants, reduces carbon dioxide emissions, and reduces the difficulty of waste collection and treatment through separation, filtration, and recycling after decontamination. The CO2 used can be reused, which improves the cleanliness of the decontamination environment, reduces the risks of internal irradiation and suffocation of operators, and significantly reduces the cost of decontamination, which is of great significance to improving the level of decommissioning of nuclear facilities in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 A schematic diagram of a multiphase carbon dioxide decontamination and recovery system provided in Example 1 of the present invention;

[0022] Figure 2 A multiphase carbon dioxide decontamination and recovery process flow chart provided in Example 1 of the present invention;

[0023] Icons: 1-steel cylinder, 2-dry ice pelletizer, 3-dry ice storage and conveying device, 4-boosting pump, 5-first buffer tank, 6-injector, 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-doser, 17-circulation pipeline. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0025] It should be noted that the various chemical equipment described in this embodiment can all be selected from corresponding equipment commonly used in the field, and the present invention is not limited thereto. For example, the storage and conveying device is a traditional storage tank, the separator is a separator commonly used in the chemical field, and the agitator is a agitator commonly used in the chemical field.

[0026] A multiphase carbon dioxide decontamination and recovery system and a decontamination and recovery process provided by an embodiment of the present invention are described in detail below.

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

[0028] The dry ice supply circuit is used to manufacture dry ice and supply dry ice particles to the ejector; the dry ice supply circuit comprises: a dry ice pelletizer 2 and a dry ice storage and conveying device 3; the front end of the dry ice pelletizer is connected to a cylinder 1, dry ice particles are manufactured by the dry ice pelletizer, and then the dry ice is conveyed to the dry ice storage and conveying device 3 through a pipeline for storage, 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 rate;

[0029] In addition, the dry ice pelletizer 2, the dry ice storage and transportation device 3, the ejector 6, and the decontamination container 7 are tightly connected to ensure the manufacture, transportation, and supply of dry ice in a closed environment. A slightly positive pressure carbon dioxide is introduced into the bypass of the dry ice pelletizer 2 to prevent air from entering the system during the manufacture, transportation, and storage process.

[0030] The high-pressure CO2 supply circuit is used to provide high-pressure CO2; it mainly includes a CO2 storage tank 13, a booster pump 4, a first buffer tank 5, a pressure regulating valve 14 and instruments, etc.; wherein, the steel cylinder 1 and the CO2 storage tank 13 are used to store liquid CO2, and its users 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 to store high-pressure CO2, providing sufficient CO2 capacity for the injection decontamination circuit, and can maintain CO2 in a supercritical state; the pressure regulating valve 14 is used to adjust the pressure before the decontamination circuit, and can realize gaseous, liquid and supercritical CO2 regulation;

[0031] The decontamination circuit is the execution part of sample decontamination, which mainly includes two decontamination methods: spray decontamination and immersion decontamination; specifically, it includes: an ejector 6, a decontamination container 7 and corresponding pipelines, valves and instruments; the ejector is connected to the dry ice storage and conveying device 3 and the first buffer tank 5 respectively, and is used to mix the high-pressure CO2 fluid from the upstream with the dry ice to form a high-speed fluid that is sprayed onto the sample for decontamination; the decontamination container 7 is used to place the sample and contain the CO2 fluid, and the decontamination container 7 contains a magnetic stirrer and is externally connected to a bypass circuit, which can realize the separate decontamination functions of spray decontamination, immersion decontamination and stirring decontamination and their combined decontamination functions, and the decontamination container 7 is also provided with a temperature regulator, a pressure regulator and a sample fixing device, which have the functions of temperature regulation, pressure regulation, sample fixing and regulation, and the decontamination process is in a closed environment and has no effect on the external environment; the internal low pressure state is maintained during spray decontamination, and the stable high pressure state can be maintained during immersion decontamination, so that CO2 is in a supercritical state. A preheater is arranged on the periphery of the decontamination container 7 to provide heat preservation for the container, and a lead shield is arranged. A sample holder is fixed inside to fix the sample and adjust the injection distance and angle of the sample. A bypass loop is also arranged on one side of the decontamination container 7, including a discharge pipe arranged at the bottom of the decontamination container 7 and a circulation pipe connected to one side of the discharge pipe. The end of the circulation pipe is connected to the decontamination container 7, and a circulation pump and a dosing device are arranged on the circulation pipe. The local large-flow circulation decontamination of the decontamination container 7 is realized.

[0032] The CO2 recovery loop is used to recover the CO2 for use, and mainly includes 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 connected to the decontamination container 7, and the separator 8 is used to separate the CO2 gas and solid pollutants generated by decontamination; the filter further separates to improve the purity of the recovered CO2; the second buffer tank 10 is used to collect CO2 from the decontamination circuit to provide a certain storage capacity for CO2 recovery; the cooler 11 cools the gas to prepare for compressing CO2 to a liquid state; a recovery loop is provided at the discharge end of the cooler 11, and a booster pump 12 is provided on the recovery loop to pressurize the CO2 and supply it to the CO2 storage tank 13.

[0033] A multiphase carbon dioxide decontamination and recovery process comprises the following steps: in a supercritical state, using ethanol or acetone as an entrainer, using carbon dioxide in a supercritical state to carry the entrainer to dissolve sodium formate or an ammonium salt-based decontaminant to soak and decontaminate the radioactive contaminated surface for pre-treatment; at the same time, under the action of magnetic stirring, using high-pressure carbon dioxide as a power to carry dry ice particles and spray out from a high-pressure nozzle to impact the radioactive contaminated surface to achieve radioactive contamination removal, and after two-stage pressure reduction separation and one-stage filtration, the carbon dioxide is recycled;

[0034] The pretreatment pressure during the immersion decontamination pretreatment is 7.38MPa-30MPa, and the treatment temperature is 31°C-80°C; the working pressure of the high-pressure carbon dioxide is 0.1MPa-20MPa; during the 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 working environment temperature is 0-45°C.

[0035] More specifically, the multiphase carbon dioxide decontamination recycling process of the present invention mainly includes a multifunctional decontamination process and a carbon dioxide recycling process.

[0036] 1) Multifunctional decontamination process

[0037] a. Supercritical carbon dioxide immersion decontamination: Liquid CO2 from the steel cylinder 1 and the CO2 storage tank 13 is supplied to the booster pump 4, which increases the CO2 pressure to the supercritical pressure and directly supplies it to the decontamination container 7 through the bypass of the first buffer tank 5. The decontamination container 7 is kept in a supercritical state, the pressure in the container is maintained by the booster pump 4, and the water bath heating device of the decontamination container 7 is kept at a suitable temperature. The supercritical CO2 dissolves the pollutants on the sample surface, making it easier to remove the pollutants.

[0038] b. Multiphase carbon dioxide spray decontamination: Liquid CO2 from the steel cylinder 1 and CO2 storage tank 13 is divided into two routes, one route is supplied to the dry ice granulator 2, and the dry ice produced is transported to the dry ice storage and transportation device 3 through a closed loop, and the other route is supplied to the booster pump 4, which increases the CO2 pressure to the 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 supplied to the ejector 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 and transportation device 3 is supplied to the ejector 6 after being adjusted by the flow regulating device. The CO2 fluid carries the dry ice and sprays it to the contaminated sample (i.e., the sample to be processed) to achieve the purpose of decontamination. The pressure-regulated CO2 fluid can be in a gaseous, liquid or supercritical state, and fluids in different states can be provided for spray cleaning according to the degree of sample contamination.

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

[0040] 2) Carbon dioxide recycling process

[0041] The CO2 used by the decontamination container 7 is discharged to the downstream separator 8 to separate the CO2 gas and solid pollutants generated by the 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 buffering for the downstream equipment and have a certain storage capacity; the gas is cooled by the cooler 11, and then the CO2 is pressurized and supplied to the CO2 storage tank 13 through the booster pump 12 to complete the recovery of CO2.

[0042] The decontamination recovery system of the present invention has the functions of manufacturing dry ice particles, generating high-pressure carbon dioxide jet fluid, constructing a supercritical carbon dioxide decontamination environment, injecting entrainers and decontaminants, separating carbon dioxide and pollutants, etc., and uses carbon dioxide in multiple phases such as solid, liquid, gaseous, and supercritical to perform chemical complexation and mechanical and physical impact to perform composite decontamination; the decontamination recovery process and the decontamination recovery system of the present invention can well realize supercritical carbon dioxide immersion decontamination, multi-phase carbon dioxide jet decontamination, stirring decontamination and combined decontamination processes.

[0043] Example 1

[0044] This embodiment provides a multiphase carbon dioxide decontamination and recovery system and process, including multiple decontamination processes such as immersion decontamination, spray decontamination and stirring decontamination, and a carbon dioxide recovery and utilization process, which specifically includes the following steps:

[0045] 1) Dry ice supply: Liquid CO2 from the steel cylinder 1 and the CO2 storage tank 13 is supplied to the dry ice granulator 2 for making dry ice particles. The made dry ice is transported to the storage and transportation device 3 for storing and transporting dry ice to the ejector 6, which can realize direct processing and supply of dry ice. The dry ice supply pipeline is airtight and has a slight positive pressure inside, which can ensure the purity of dry ice and carbon dioxide. The transportation device 3 can automatically adjust the dry ice transportation rate and change the flow rate during injection.

[0046] 2) Carbon dioxide pressure increase and state regulation: Liquid CO2 from the steel cylinder 1 and the CO2 storage tank 13 is supplied to the booster pump 4, which increases 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 CO2 can be generated for downstream immersion decontamination or spray decontamination.

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

[0048] 4) Decontamination by spraying: Liquid CO2 from the steel cylinder 1 and CO2 storage tank 13 is divided into two routes, one route is supplied to the dry ice granulator 2, and the dry ice produced is transported to the dry ice storage and conveying device 3 through a closed loop, and the other route is supplied to the booster pump 4, which increases the CO2 pressure to the 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 supplied to the ejector 6 after being adjusted to 10MPa by the pressure regulating valve 14, and the dry ice from the dry ice storage and conveying device 3 is supplied to the ejector 6 after being adjusted by the flow regulating device. The ejector 6 is used to remove the contaminated CO2 fluid through the spray interface, and the dry ice is sprayed to the contaminated sample to achieve the purpose of decontamination. The CO2 fluid after pressure regulation can be in gaseous, liquid or supercritical state, and fluids in different states can be provided for spraying and cleaning according to the degree of sample contamination.

[0049] 5) Stirring for decontamination: The stirring device provided in the decontamination container 7 (conventional stirring devices in the art may be used, and the present invention does not impose any limitation thereto) can provide stirring power, accelerate the circulation of the fluid in the container, and rinse away the contamination on the surface of the immersed sample.

[0050] 6) Recycling: The CO2 used in the decontamination container 7 is discharged to the downstream separator 8 to separate the CO2 gas and solid pollutants generated by the decontamination; when the separator 8 is separating: the decompression separation pressure is 15MPa, and the working environment temperature is 25°C; then it is sent to the filter 9 for further separation, and the decompression separation pressure is 10MPa, so as 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 the downstream equipment and have a certain storage capacity; the gas is cooled by the cooler 11, and then the CO2 is pressurized and supplied to the CO2 storage tank 13 through the booster pump 12 to complete the recovery of CO2.

[0051] After being treated by the treatment method of this embodiment, the surface radioactive loose pollution removal rate reaches 99.99%; the rust spraying decontamination rate is 98.6%, and the decontamination efficiency is 0.06m 2 / min; oil jet removal rate 90.8%, decontamination efficiency 0.07m 2 / min; the carbon dioxide recovery rate reached 86%.

[0052] Example 2

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

[0054] During the soaking and decontamination in step 3), the pretreatment pressure is 20 MPa and the treatment temperature is 60°C.

[0055] During the decontamination spraying in step 4), the pressure is adjusted to 5 MPa by the pressure regulating valve and then supplied to the ejector;

[0056] When recycling in step 6), the pressure of the separator for decompression separation is 16 MPa, and the working environment temperature is 15° C.; then it is sent to the filter for further separation, and the decompression separation pressure is 5 MPa.

[0057] After being treated by the treatment method of this embodiment, the surface radioactive loose pollution removal rate reaches 99.98%; the rust spraying decontamination rate is 98.5%, and the decontamination efficiency is 0.05m 2 / min; oil jet removal rate 90.9%, decontamination efficiency 0.06m 2 / min; the carbon dioxide recovery rate reaches 85%.

[0058] Example 3

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

[0060] During the soaking and decontamination in step 3), the pretreatment pressure is 30MPa and the treatment temperature is 70°C.

[0061] During the decontamination spraying in step 4), the pressure is adjusted to 18 MPa by the pressure regulating valve and then supplied to the injector;

[0062] When recycling in step 6), the pressure of the separator for decompression separation is 20 MPa, and the working environment temperature is 30° C.; then it is sent to the filter for further separation, and the decompression separation pressure is 15 MPa.

[0063] After being treated by the treatment method of this embodiment, the removal rate of loose radioactive contamination on the surface reaches 99.99%; the rust spraying decontamination rate is 98.8%, and the decontamination efficiency is 0.07m 2 / min; oil jet removal rate 90.7%, decontamination efficiency 0.07m 2 / min; the carbon dioxide recovery rate reaches 88%.

[0064] The entire process of the present invention can realize multifunctional decontamination, make the decontamination more thorough, realize the recycling of CO2, greatly reduce the discharge of secondary waste, and significantly reduce the cost of decontamination.

[0065] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multiphase carbon dioxide decontamination and recovery system, characterized in that: It 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 comprises: a dry ice pelletizer and a dry ice storage and conveying device; the dry ice is produced by the dry ice pelletizer, then the dry ice is conveyed to the dry ice storage and conveying device through a pipeline for storage, and the dry ice is supplied to the ejector 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 pelletizer, 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 comprises: an ejector and a decontamination container; the inlet end of the ejector is respectively connected to the dry ice storage and conveying device and the first buffer tank, and is used to mix the dry ice in the dry ice storage and conveying device and the first buffer tank with the high-pressure CO2 fluid to form a high-speed fluid that is ejected onto the surface of the sample to be processed for decontamination; the decontamination container is used to place the sample and contain the CO2 fluid; The CO2 recovery loop comprises a separator, a filter, a second buffer tank, and a cooler which are connected in sequence; the feed end of the separator is connected to the decontamination container, the discharge end of the cooler is provided with a recovery loop, and the recovery loop is provided with a booster pump for pressurizing CO2 and supplying it to the CO2 storage tank.

2. The multiphase carbon dioxide decontamination and recovery system according to claim 1, characterized in that: The dry ice granulator, the dry ice storage and transportation device, the ejector and the decontamination container are tightly connected.

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

4. The multiphase carbon dioxide decontamination and recovery system according to claim 1, characterized in that: The decontamination container is provided with a stirrer, and the outside of the decontamination container is connected with a bypass circuit for local large-flow circulation decontamination of the decontamination container.

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

6. The multiphase carbon dioxide decontamination and recovery system according to claim 4, characterized in that: The bypass loop includes a discharge pipe arranged 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 doser are arranged on the circulation pipe.

7. A decontamination and recovery process of a multiphase carbon dioxide decontamination and recovery system according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) using a dry ice supply circuit and a high-pressure CO2 supply circuit to deliver dry ice and high-pressure CO2 fluid to an ejector for mixing, maintaining CO2 in a supercritical state, and forming a high-speed fluid to be ejected onto the surface of a sample to be treated placed in a decontamination container for decontamination; (2) using ethanol or acetone as an entrainer, using carbon dioxide in a supercritical state to carry the entrainer to dissolve the decontaminant to perform a soaking decontamination pretreatment on the sample to be treated placed in the decontamination container; At the same time, stirring is performed in the decontamination container, and high-pressure carbon dioxide is used as a power to carry dry ice particles and spray out from the high-pressure nozzle to impact the surface of the sample to be processed, thereby removing radioactive contaminants on the surface of the sample to be processed; (3) The CO2 gas and solid pollutants generated by decontamination in the decontamination container are separated by two-stage pressure reduction and filtered by one-stage through the separator, filter, second buffer tank and cooler of the CO2 recovery loop to achieve the recovery and utilization of carbon dioxide.

8. The multiphase carbon dioxide decontamination and recovery process according to claim 7, characterized in that: The pretreatment pressure during the soaking decontamination pretreatment is 7.38MPa-30MPa, and the treatment temperature is 31°C-80°C.

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

10. The multiphase carbon dioxide decontamination and recovery process according to claim 7, characterized in that: When two-stage pressure reduction and separation is used: the pressure of the first stage pressure reduction and separation is 15MPa-20MPa, the pressure of the second stage pressure reduction and separation is 5MPa-15MPa, and the working environment temperature is 0-45℃.

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