CN112893328A - Method for cleaning alkali metal residues and application thereof - Google Patents
Method for cleaning alkali metal residues and application thereof Download PDFInfo
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- CN112893328A CN112893328A CN202110129357.XA CN202110129357A CN112893328A CN 112893328 A CN112893328 A CN 112893328A CN 202110129357 A CN202110129357 A CN 202110129357A CN 112893328 A CN112893328 A CN 112893328A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B13/00—Accessories or details of general applicability for machines or apparatus for cleaning
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention relates to the field of industrial cleaning, in particular to a method for cleaning alkali metal residues and application thereof. The method comprises the following steps: contacting the dry gas stream with the surface having the alkali metal attached thereto, such that the alkali metal is released from the surface; the dry gas flow comprises a carrier gas and a solid cleaning medium, the cleaning medium comprises dry ice, and the content of the dry ice is more than 90 wt% based on the total weight of the cleaning medium. The method can realize drying and cleaning, avoids sodium water reaction and greatly improves the safety; residual sodium and other dirt can be removed quickly and effectively; the cleaning agent can almost have no residue and no secondary pollution after cleaning, and is clean and environment-friendly; can reduce the corrosion and damage to the cleaning surface and prolong the service life of the product.
Description
Technical Field
The invention relates to the field of industrial cleaning, in particular to a method for cleaning alkali metal residues and application thereof.
Background
The nuclear power has important significance for solving the problem of insufficient energy and coping with environmental deterioration and climate warming. The sodium-cooled fast reactor technology is a reactor type which is developed with emphasis on the intrinsic safety and high economy. The metal sodium as heat transfer medium and coolant has high chemical activity and can be burnt in oxygen, chlorine, fluorine and bromine steam; hydrogen is released by violent reaction in water or water vapor, and a large amount of heat is released to generate combustion or explosion; exposed in air, can be combusted automatically and explode to splash the melt; capable of reacting violently with halogens, phosphorus, many oxides, oxidants and acids.
At present, 6 methods are adopted for cleaning the sodium-cooled fast reactor at home and abroad: water cleaning, steam cleaning, water mist cleaning, alcohol cleaning, vacuum distillation, and vacuum cleaning. The water washing method is a simple and direct method for washing sodium equipment, namely, the sodium-sticking equipment is placed under a water spray head for showering, and sodium can be completely removed. The steam cleaning method is the same principle as the water cleaning method, for example, after cleaning a sodium-binding device with a mixture of nitrogen and 15% steam, rinsing with deionized water, and then drying with nitrogen or vacuum. The water mist cleaning method is that a nozzle is arranged on the wall of a cleaning trap, water mist is generated by the nozzle, and carrier gas is nitrogen, carbon dioxide or the mixture of the nitrogen and the carbon dioxide; sodium reacts gradually with water mist formed by the mixture of the water droplets and the carrier gas at ambient temperature to generate sodium hydroxide, and hydrogen is filtered and diluted and then discharged into the ventilation duct. The alcohol washing method is to replace water with alcohol to react with sodium. The vacuum distillation method comprises placing sodium-containing equipment into a cleaning container, heating to 200 deg.C under normal pressure to melt sodium, discharging, cleaning the container to 500 deg.C, vacuumizing to distill residual sodium on the equipment, and recovering sodium to obtain carbonate. The vacuum cleaning method is that sodium interacts with water and aqueous solution under vacuum, and reaction heat is carried out by water evaporation under vacuum.
The six existing methods for cleaning the sodium-cooled fast reactor have a plurality of defects such as serious potential safety hazards in actual operation, and the cleaning specification and related safety specification aiming at the sodium-cooled fast reactor are in blank states.
From the experience of foreign decommissioning work, the removal of residual sodium accounts for a significant amount of work in the cleaning process. Therefore, finding a safer, more efficient and more environment-friendly sodium removal process has very important significance for the cleaning treatment of the sodium-cooled fast reactor.
Disclosure of Invention
The invention aims to overcome the defects of serious potential safety hazard and the like in the existing cleaning process for treating sodium residues, and provides a method for cleaning alkali metal residues and application thereof. The method can realize drying and cleaning, avoids sodium water reaction and greatly improves the safety; residual sodium and other dirt can be removed quickly and effectively; the cleaning agent can almost have no residue and no secondary pollution after cleaning, and is clean and environment-friendly; can reduce the corrosion and damage to the cleaning surface and prolong the service life of the product.
The inventor of the present invention finds that the following problems are common to the current cleaning method of sodium-cooled reactor: firstly, the safety is extremely low, a large amount of heat and hydrogen are often generated in the treatment process, and the combustion and explosion can be caused by the untimely treatment; secondly, the cleaning treatment takes a long time and needs to be stopped for a long time; thirdly, a large amount of wastewater is generated, and a large amount of manpower, financial resources and time cost are needed for discharging the wastewater from the equipment and treating the wastewater subsequently; fourthly, when sand blasting or chemical purificant is used, the cleaning medium is polluted by radioactive elements, and the time and the fund for treating the waste water are increased; and the like.
The inventor of the invention researches and discovers that residual metal sodium and other dirt in equipment and parts can be effectively removed by using dry ice in the cleaning of a sodium-cooled reactor; the cleaning is quick and accurate, and long-time shutdown is not needed; high temperature and inflammable explosive gas are not generated in the cleaning process, and the safety is high; no waste water is generated after cleaning, and complex subsequent treatment is not needed. Further, the inventors of the present invention have intensively studied to find a more preferable cleaning method with higher cleaning efficiency and less usage of dry ice.
In a first aspect the present invention provides a method of cleaning alkali metal residue, the method comprising: contacting the dry gas stream with the surface having the alkali metal attached thereto, such that the alkali metal is released from the surface; the dry gas flow comprises a carrier gas and a solid cleaning medium, the cleaning medium comprises dry ice, and the content of the dry ice is more than 90 wt% based on the total weight of the cleaning medium.
In the invention, the airflow which is contacted with the alkali metal is dry airflow, namely the airflow does not contain liquid water, thereby avoiding serious potential safety hazard caused by a large amount of heat and hydrogen generated by the reaction between water and sodium and solving a plurality of problems of the method for cleaning the sodium-cooled fast reactor in the prior art; in order to effectively remove alkali metals, the cleaning medium takes dry ice as a main component, solid dry ice particles are sprayed to the surface at a high speed to generate impact micro-explosion, dirt is rapidly condensed, embrittled and dropped, carbon dioxide can be directly volatilized, and the cleaning medium has the characteristics of stability and non-flammability and can dilute oxygen.
Therefore, the above-mentioned method for cleaning alkali metal residues of the present invention has been made to solve the problems of the prior art and to achieve excellent effects. Further, the inventors of the present invention made intensive studies on a cleaning method to achieve higher cleaning efficiency and less usage of dry ice.
In preferred embodiments of the invention, the process of the invention may further define one or more of the following preferred features.
Since water can react violently with alkali metals, which brings safety concerns, the present invention has been limited to dry gas streams, i.e., not containing liquid water. The invention is not limited to solid water, and the cleaning medium may contain a small amount of solid water (ice) and/or hydrate within a safe range.
Preferably, the cleaning medium does not contain H2O (e.g., ice) for added safety and ease of subsequent handling.
The content of the dry ice in the cleaning medium is more than 90 percent, so that the effective cleaning effect can be realized. The cleaning medium of the present invention may also contain other ingredients without affecting the function of the dry ice. Preferably, the dry ice is contained in an amount of 95 wt% or more based on the total weight of the cleaning medium; more preferably, the cleaning medium contains 99% by weight or more of dry ice. From the viewpoint of facilitating the subsequent processing, the cleaning medium may be entirely dry ice.
In the present invention, the particle size of the dry ice may be selected in a wide range, and may be adjusted according to specific conditions, for example, the average particle size of the dry ice is 0.1-10mm, preferably 1-6 mm.
In the present invention, the average particle size, average diameter and average length can be observed by a low-temperature microscope.
In the present invention, the composition type of the dry ice may not be limited. For example, in one embodiment, the dry ice has an average particle size of 1.5 to 3.5 mm.
The carrier gas in the drying gas flow is compressed gas, preferably, the pressure of the carrier gas is 0.2-1.0Mpa, preferably 0.4-0.9Mpa, and more preferably 0.5-0.8 Mpa. In the present invention, the air pressure is an absolute pressure.
Preferably, the carrier gas is an inert gas, preferably nitrogen.
Preferably, the ice discharge rate of the dry ice in the dry gas stream is 0.001 to 0.1kg/s, preferably 0.01 to 0.09kg/s, and more preferably 0.03 to 0.06 kg/s.
When the alkali metal is completely removed, the amount of the cleaning medium to be used is usually 1 to 100g, preferably 30 to 70g, more preferably 40 to 60g in terms of dry ice per g of the alkali metal.
In a more preferred embodiment, the dry ice comprises class a dry ice, class B dry ice and class C dry ice, wherein class a dry ice is a sphere with an average particle size of 1-4mm (preferably 2-3mm), class B dry ice is a cylinder with an average diameter of 1-3mm (preferably 1.5-2.5mm) and an average length of 2-6mm (preferably 3-5mm), and class C dry ice is an irregular polyhedron (i.e. more angular) with an average particle size of 1-6mm (preferably 3-5 mm).
Preferably, the content of the grade A dry ice is 15-35 wt%, the content of the grade B dry ice is 10-40 wt%, and the content of the grade C dry ice is 30-60 wt% based on the total weight of the dry ice.
More preferably, the content of the grade A dry ice is 20-30 wt%, the content of the grade B dry ice is 20-30 wt%, and the content of the grade C dry ice is 40-55 wt%, based on the total weight of the dry ice.
The inventors of the present invention have found that by mixing the above specific types of dry ice in a specific ratio, more alkali metal residue can be removed at a faster rate with a smaller amount of dry ice. The control parameters of the drying gas stream containing such specific dry ice when contacted with the alkali metal may be selected in accordance with the aforementioned ranges.
The drying gas stream may be continuously contacted with the surface having the alkali metal attached thereto until the alkali metal is removed, or may be contacted in a pulsed manner. When contacting in a pulsed manner, preferably, the single contact time is 2 to 10s, and the interval time is 1 to 10 s; more preferably, the single contact time is 4 to 8 seconds with an interval time of 2 to 5 seconds.
The inventors of the present invention have further studied intensively and found that cleaning can be made more efficient when two different specific dry air streams are brought into contact with the surface to which the alkali metal is attached in an alternating manner.
According to a preferred embodiment, the drying gas stream comprises a first drying gas stream comprising 15-70% by weight of class B dry ice and 30-85% by weight of class C dry ice, and a second drying gas stream comprising 15-70% by weight of class a dry ice and 30-85% by weight of class B dry ice.
Preferably, the dry ice in the first dry gas stream comprises 20-60 wt% of class B dry ice and 40-80 wt% of class C dry ice; more preferably, the dry ice in the first stream of dry gas comprises 30-45% by weight of class B dry ice and 55-70% by weight of class C dry ice.
Preferably, the dry ice in the second dry gas stream comprises 30-70 wt% of grade a dry ice and 30-70 wt% of grade B dry ice; more preferably, the dry ice in the second stream of dry gas comprises 40-60% by weight of class a dry ice and 40-60% by weight of class B dry ice.
Preferably, the method comprises: alternately contacting the first dry gas stream and the second dry gas stream with the alkali metal-attached surface; the contact time is 2-10s each time, and the interval time is 1-10 s.
More preferably, each contact time is 4-8s and the interval time is 2-5 s.
Preferably, the ice discharge speed of the dry ice in the first drying gas flow is 1.5 to 3 times, more preferably 2 to 2.5 times, the ice discharge speed of the dry ice in the second drying gas flow; and the ice discharging speed of the dry ice in the second drying airflow is 0.01-0.05kg/s, and further preferably 0.02-0.04 kg/s.
Preferably, the carrier gas pressure of the first drying gas stream is from 0.4 to 0.9MPa, preferably from 0.6 to 0.8 MPa; and the carrier gas pressure of the second dry gas stream is 0.3 to 0.7MPa, more preferably 0.4 to 0.6 MPa.
And calculating the required dry ice amount according to the content of alkali metal in the specific working condition, and calculating the use amount of each dry airflow based on the dry ice amount and the ratio between the two dry airflows.
In the present invention, the alkali metal is potassium or sodium.
In the present invention, it is preferable that the surface to which the alkali metal is attached is a surface of a device or a component to which metallic sodium is attached in a sodium-cooled reactor.
The second aspect of the invention provides the application of the method of the first aspect of the invention in cleaning alkali metal residues in a sodium-cooled fast reactor.
In the application of the invention, the parts of the equipment and the parts of the sodium-cooled fast reactor with sodium residues can be treated according to the method of the invention.
In the application of the present invention, the equipment used may be self-made or commercially available equipment capable of high-pressure dry ice blasting. For example, according to one embodiment, an apparatus for carrying and releasing the cleaning medium comprises:
a cleaning medium storage assembly comprising a first container for storing the cleaning medium;
a carrier gas storage assembly comprising a second container for providing a carrier gas carrying the cleaning medium;
a release assembly comprising a spray head for releasing a gas stream containing the cleaning medium to a target site;
a pressurizing assembly for pressurizing the carrier gas to form the gas flow containing the cleaning medium, comprising a third container capable of being pressurized, at least one inlet of the third container is communicated with the carrier gas storage assembly, at least one outlet is communicated with the releasing assembly, and the cleaning medium storage assembly is communicated with the inlet and/or the outlet of the pressurizing assembly so that the cleaning medium is mixed in before and/or after the carrier gas is pressurized;
the guide assembly is communicated with the pressurizing assembly and the releasing assembly, and the position and the angle of the releasing assembly can be adjusted;
and optionally (with or without) a control component, wherein the control component is used for adjusting the pressure of the pressurizing component according to the condition of the alkali metal residue, adjusting the proportion of the cleaning medium discharged from the cleaning medium storage component to the carrier gas discharged from the carrier gas storage component, and adjusting the release amount of the release component; and controlling movement of the drive assembly and the guide assembly to cause the release assembly to change the direction of release.
Thus, in the application and method of the present invention,
pressurizing the carrier gas from the carrier gas storage component through the pressurizing component to obtain high-pressure carrier gas;
the high-pressure carrier gas carries the cleaning medium from the cleaning medium storage component to obtain an air flow containing the cleaning medium;
the airflow containing the cleaning medium is released to the part to be treated through the releasing component, so that the alkali metal is cleaned;
the power assembly drives the equipment to move and drives the guide assembly to move so as to carry the release assembly to move to a new part to be treated.
In the invention, the shape, the size, the distribution of the spray holes, the shape and the size of the spray holes and the like of the release component (such as a spray head) can be set, so that the release component can be better suitable for the equipment of the sodium-cooled fast reactor, and the dry air flow can be smoothly released to all corners.
Through the technical scheme, compared with the prior art, the invention at least has the following advantages:
(1) the drying and cleaning are realized, the sodium water reaction is avoided, and the generated carbon dioxide has stable property and can dilute oxygen, so that the safety is greatly improved;
(2) the treatment is quick and efficient, the time consumption is short, the production can be quickly recovered, and the long-time shutdown is avoided;
(3) the fixed-point treatment of the alkali metal surfaces under different conditions is more targeted and more accurate, which is beneficial to the full cleaning of the alkali metal surfaces and avoids the ineffective cleaning of the metal-less surfaces, thereby improving the overall efficiency of the cleaning procedure;
(4) the cleaning product is gaseous carbon dioxide, can be directly volatilized, does not bring burden to the environment, does not generate secondary pollutants such as wastewater and the like, does not need subsequent treatment, and is green and environment-friendly;
(5) the financial cost of subsequent treatment is reduced, and a large amount of labor and time cost is saved;
(6) the corrosion and damage to the cleaning surface can be reduced, and the service life of the equipment is prolonged;
(7) the risk of sodium leakage in nuclear power operation is reduced, and the safety of nuclear power is improved;
(8) equipment does not need to be disassembled, and the precision of the equipment is guaranteed;
(9) can effectively clean corners, gaps and dead corners, and has no pollution and residue.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
Detailed Description
The present invention will be described in detail below by way of examples. The described embodiments of the invention are only some, but not all embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following examples, in order to ensure comparability between effects, the cleaning object of each example was selected from a pipeline "having an inner diameter of about 40mm and a length of about 600mm, and about 300g of sodium remained" meeting the following requirements, and if there were no multiple pipelines meeting the requirements at the same time, the pipeline meeting the requirements after the next production was selected and cleaned according to the method of the corresponding example and recorded.
The dry ice used in the following examples includes:
grade A dry ice: spherical or approximately spherical, with an average particle size of 2.6 mm;
grade B dry ice: a cylinder having an average diameter in the range of 1.8mm and an average length in the range of 3.8 mm;
grade C dry ice: irregular polyhedra having an average particle size in the range of 4.2 mm.
The following group a examples are given to illustrate the same composition of the drying air stream.
Example A1
(1) Preparing dry ice: consisting of 25% by weight of grade a dry ice, 25% by weight of grade B dry ice and 50% by weight of grade C dry ice.
(2) Alternately spraying a first drying airflow and a second drying airflow into the pipeline, wherein the carrier is nitrogen, and the single spraying time is 7s and the interval is 3 s;
the ice discharging speed is 0.06kg/s, and the gas pressure of the carrier gas is 0.78 MPa;
the cleaned sodium and other impurities are blown out at the outlet and collected (sodium is mainly in the form of sodium carbonate), the content of sodium on the tube wall is detected by a probe, 35 times of spraying are performed in total when the sodium is cleaned, the total consumption of dry ice is 14.5kg, and 5min50s is consumed.
Example A2
(1) Preparing dry ice: consisting of 20 weight percent class a dry ice, 25 weight percent class B dry ice and 55 weight percent class C dry ice.
(2) Alternately spraying a first drying airflow and a second drying airflow into the pipeline, wherein the carrier is nitrogen, and the single spraying time is 6s and the interval is 4 s;
the ice discharging speed is 0.05kg/s, and the gas pressure of the carrier gas is 0.65 MPa;
when the sodium is cleaned, a total of 52 times of spraying are needed, the total amount of dry ice is 15.5kg, and 8min50s is consumed.
Example A3
(1) Preparing dry ice: consisting of 30 weight percent class a dry ice, 30 weight percent class B dry ice, and 40 weight percent class C dry ice.
(2) Alternately spraying a first drying airflow and a second drying airflow into the pipeline, wherein the carrier is nitrogen, and the single spraying time is 8s and the interval is 2 s;
the ice discharging speed is 0.042kg/s, and the gas pressure of the carrier gas is 0.52 MPa;
when the sodium is cleaned, a total of 50 times of spraying are needed, the total amount of dry ice is 16.6kg, and the time is 8min and 15 s.
Example A4
The process of example A1 was followed, except that grade A dry ice was used in its entirety.
When the sodium is cleaned, a total of 48 sprays are needed, the total amount of dry ice is 20kg, and 7min is consumed, namely 55 s.
Example A5
The method of example A1, except that instead of spraying in an intermittent fashion, a continuous spray is used.
When the sodium is cleaned, the total spraying time is 7min and 5s, and the total consumption of dry ice is 25 kg.
The following group B examples are given to illustrate the drying air flow as two air flows alternating.
Example B1
The method for processing the glass fiber reinforced plastic comprises the following steps:
(1) two sets of dry ice sets were prepared
A first group: consists of 40 weight percent of B grade dry ice and 60 weight percent of C grade dry ice;
second group: consisting of 40% by weight of grade a dry ice and 60% by weight of grade B dry ice.
(2) Alternately spraying a first drying airflow and a second drying airflow into the pipeline, wherein the carrier is nitrogen, and the single spraying time is 7s and the interval is 3 s; wherein the content of the first and second substances,
the first dry airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.08kg/s, and the gas pressure of the carrier gas is 0.75 MPa;
the second drying airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.04kg/s, and the gas pressure of the carrier gas is 0.6 MPa;
the cleaned sodium and other impurities were blown out at the outlet and collected (sodium is mainly in the form of sodium carbonate) and the sodium was cleaned up for a total of 30 shots, with a total dry ice consumption of 12.5kg, taking 5min2 s.
Example B2
In the sodium-cooled fast reactor, a pipeline with the inner diameter of 40mm and the length of about 600mm is selected, and about 300g of sodium remains on the pipeline. The method for processing the glass fiber reinforced plastic comprises the following steps:
(1) two sets of dry ice sets were prepared
A first group: consists of 30 weight percent of B grade dry ice and 70 weight percent of C grade dry ice;
second group: consisting of 50% by weight of grade a dry ice and 50% by weight of grade B dry ice.
(2) Alternately spraying a first drying airflow and a second drying airflow into the pipeline, wherein the carrier is nitrogen, and the single spraying time is 8s and the interval is 5 s; wherein the content of the first and second substances,
the first drying airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.075kg/s, and the carrier gas pressure is 0.6 MPa;
the second drying airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.03kg/s, and the gas pressure of the carrier gas is 0.4 MPa;
when the sodium is cleaned, a total of 32 sprays are needed, the total amount of dry ice is 13.2kg, and 6min50s is consumed.
Example B3
In the sodium-cooled fast reactor, a pipeline with the inner diameter of 40mm and the length of about 600mm is selected, and about 300g of sodium remains on the pipeline. The method for processing the glass fiber reinforced plastic comprises the following steps:
(1) two sets of dry ice sets were prepared
A first group: consists of 45 weight percent of B grade dry ice and 55 weight percent of C grade dry ice;
second group: consists of 60% by weight of grade a dry ice and 40% by weight of grade B dry ice.
(2) Alternately spraying a first drying airflow and a second drying airflow into the pipeline, wherein the carrier is nitrogen, and the single spraying time is 4s and the interval is 2 s; wherein the content of the first and second substances,
the first dry airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.07kg/s, and the gas pressure of the carrier gas is 0.7 MPa;
the second dry gas flow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.035kg/s, and the gas pressure of the carrier gas is 0.45 MPa.
When the sodium is cleaned, a total of 64 shots are needed, the total amount of dry ice is 13.4g, and 6min22s is consumed.
Example B4
The method of embodiment B1 is followed except that the parameters of the first drying gas stream and the second drying gas stream are varied, specifically,
the first dry airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.06kg/s, and the gas pressure of the carrier gas is 0.7 MPa;
the second dry airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.06kg/s, and the carrier gas pressure is 0.7 MPa.
When the sodium is cleaned, a total of 32 sprays are needed, the total consumption of dry ice is 13.8kg, and 5min30s is consumed.
Example B5
The method of embodiment B1 is followed except that the parameters of the first drying gas stream and the second drying gas stream are varied, specifically,
the first dry airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.04kg/s, and the gas pressure of the carrier gas is 0.5 MPa;
the second dry airflow consists of carrier gas and the first group of dry ice, the ice discharging speed is 0.08kg/s, and the gas pressure of the carrier gas is 0.7 MPa.
When the sodium is cleaned, a total of 36 times of spraying are needed, the total amount of dry ice is 15.2kg, and 6min is consumed, namely 5 s.
Comparative example 1
The treatment method adopts a steam cleaning method, and comprises the following specific steps: the equipment to be cleaned with residual sodium is a sodium pipeline with an inner diameter of 40mm and a length of 607mm, and the sodium content is 306.7 g. Establishing an inert environment according to the cleaning process steps to ensure that the system is filled with nitrogen to 0.01MPa, hoisting the pipeline to be cleaned and preheating the system to ensure that the temperature of the cleaning tank is 70 ℃, the pipeline of the electrothermal steam generator connected with the cleaning tank is 100 ℃, when nitrogen is introduced to adjust the pressure of the cleaning tank to be 0.15MPa, opening a steam inlet valve, controlling the temperature of superheated steam to be 120 ℃, controlling the flow of the steam to be 72.1kg/h and the flow of the nitrogen to be 43.9m3H is used as the reference value. After 15min, the hydrogen analyzer reads 1% (volume percent), and the steam inlet valve is automatically closed; after 3min, the hydrogen content is less than 0.5%, and the steam inlet valve is manually opened; repeating the above operations until the content of hydrogen in the exhaust gas is stable and less than 0.5%; and then closing the nitrogen inlet valve, continuously introducing water vapor for 10min, and ending the cleaning operation of the water vapor and the nitrogen if no reading is displayed by the hydrogen analyzer. Noncondensable gases such as nitrogen and reaction product hydrogen in cleaning are separated by a gas-liquid separator 9 and discharged, and water vapor is changed into condensate and discharged into a waste liquid collecting tank 6.
In the water wash stage, no hydrogen content greater than 0.5% occurs. After finishing water washing, finishing the treatment and the discharge process of drying, washing waste liquid, opening the flange on the washing tank, taking out the sodium pipeline from the hanging basket, finding that the sodium in the sodium pipeline is washed clean, and having no abnormal phenomenon in appearance.
Compared with the embodiment and the comparative example, the method can quickly remove the alkali metal remained on the surface of the equipment, the time consumption is far less than that of the comparative example, the equipment does not need to be disassembled, and the quick recovery of production is facilitated; the product of the invention is carbon dioxide, does not produce secondary pollutants such as wastewater and the like, does not need subsequent treatment, and is green and environment-friendly; the reaction process does not generate heat and hydrogen, and the hydrogen concentration does not need to be monitored at any time as in comparative example 1, so that the safety is greatly improved. It can also be seen by comparison between the examples that more preferred embodiments enable lower dry ice usage and/or shorter time consumption.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A method of cleaning alkali metal residue, the method comprising: contacting the dry gas stream with the surface having the alkali metal attached thereto, such that the alkali metal is released from the surface; the dry gas flow comprises a carrier gas and a solid cleaning medium, the cleaning medium comprises dry ice, and the content of the dry ice is more than 90 wt% based on the total weight of the cleaning medium.
2. The method according to claim 1, wherein the dry ice is 95 wt% or more based on the total weight of the cleaning medium and does not contain H2O。
3. A method according to claim 1 or 2, wherein the dry ice has an average particle size of 0.1-10mm, the gas pressure of the carrier gas is 0.2-1.0Mpa and the ice discharge rate of the dry ice in the drying gas stream is 0.001-0.1 kg/s;
preferably, the average particle size of the dry ice is 1-6mm, the gas pressure of the carrier gas is 0.4-0.9MPa, and the ice discharging speed of the dry ice in the drying gas flow is 0.01-0.09 kg/s.
4. The method according to claim 1 or 2, wherein the dry ice comprises class a dry ice, class B dry ice and class C dry ice, wherein class a dry ice is a sphere with an average particle size of 1-4mm, class B dry ice is a cylinder with an average diameter of 1-3mm and an average length of 2-6mm, and class C dry ice is an irregular polyhedron with an average particle size of 1-6 mm.
5. The method as claimed in claim 4, wherein the grade A dry ice is present in an amount of 15-35% by weight, the grade B dry ice is present in an amount of 10-40% by weight, and the grade C dry ice is present in an amount of 30-60% by weight, based on the total weight of the dry ice.
6. The method of claim 5, wherein the contacting is pulsed, with a single contact time of 2-10s and a separation time of 1-10 s;
preferably, the single contact time is 4 to 8s and the interval time is 2 to 5 s.
7. The method of claim 4, wherein the flow of dry gas comprises a first flow of dry gas comprising 15-70% by weight of class B dry ice and 30-85% by weight of class C dry ice, and a second flow of dry gas comprising 15-70% by weight of class A dry ice and 30-85% by weight of class B dry ice;
preferably, the dry ice in the first dry gas stream comprises 20-60 wt% of class B dry ice and 40-80 wt% of class C dry ice; more preferably, the dry ice in the first stream of dry gas comprises 30-45% by weight of class B dry ice and 55-70% by weight of class C dry ice.
8. The method according to claim 7, wherein the ice out-speed of the dry ice in the first drying gas stream is 1.5-3 times the ice out-speed of the dry ice in the second drying gas stream, and the ice out-speed of the dry ice in the second drying gas stream is 0.01-0.05 kg/s;
preferably, the ice discharging speed of the dry ice in the first drying air flow is 2-2.5 times of the ice discharging speed of the dry ice in the second drying air flow, and the ice discharging speed of the dry ice in the second drying air flow is 0.02-0.04 kg/s.
9. The method of claim 7, wherein the carrier gas pressure of the first dry gas stream is 0.4-0.9MPa and the carrier gas pressure of the second dry gas stream is 0.3-0.7 MPa;
preferably, the carrier gas pressure of the first dry gas stream is from 0.6 to 0.8MPa and the carrier gas pressure of the second dry gas stream is from 0.4 to 0.6 MPa.
10. Use of the method according to any one of claims 1 to 9 for cleaning alkali metal residues in sodium-cooled fast reactors.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110054668A (en) * | 2009-11-18 | 2011-05-25 | 주식회사 아이엠티 | Dry ice cleaning apparatus |
| CN102335879A (en) * | 2011-09-30 | 2012-02-01 | 电子科技大学 | Dry ice particle spray rinsing device and use method thereof |
| US20120298138A1 (en) * | 2011-05-26 | 2012-11-29 | Don Gurley | Process for cleaning surfaces using dry ice |
| CN103302061A (en) * | 2013-05-08 | 2013-09-18 | 广东电网公司电力科学研究院 | Dry ice washing efficiency detecting method |
| CN105107795A (en) * | 2015-07-29 | 2015-12-02 | 山西金鼎高宝钻探有限责任公司 | Method for cleaning surfaces of electric device and precise hydraulic part by dry ice |
-
2021
- 2021-01-29 CN CN202110129357.XA patent/CN112893328B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110054668A (en) * | 2009-11-18 | 2011-05-25 | 주식회사 아이엠티 | Dry ice cleaning apparatus |
| US20120298138A1 (en) * | 2011-05-26 | 2012-11-29 | Don Gurley | Process for cleaning surfaces using dry ice |
| CN102335879A (en) * | 2011-09-30 | 2012-02-01 | 电子科技大学 | Dry ice particle spray rinsing device and use method thereof |
| CN103302061A (en) * | 2013-05-08 | 2013-09-18 | 广东电网公司电力科学研究院 | Dry ice washing efficiency detecting method |
| CN105107795A (en) * | 2015-07-29 | 2015-12-02 | 山西金鼎高宝钻探有限责任公司 | Method for cleaning surfaces of electric device and precise hydraulic part by dry ice |
Non-Patent Citations (1)
| Title |
|---|
| 张剑波，孙良欣，胡建信，熊康，李永红: "《清洗技术基础教程》", 31 July 2004, 中国环境科学出版社 * |
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