Molten salt scrubber for capturing radioactive off-gases generated in molten salt reactor and method for separating particle using molten salt scrubber

Abstract

The present invention provides a molten salt scrubber which comprises: a reactor of which one side is opened; a molten salt container positioned inside the reactor and having a double layer structure; a cover positioned on an upper side of the reactor to cover an opening of the reactor; and a dispersion pipe inserted into the molten salt container through the cover and extending to a lower portion of the molten salt container.

Description

Molten salt scrubber for treatment of radioactive exhaust gas generated by molten salt reactors and particle separation method using a molten salt scrubber

[0001] The present invention relates to a molten salt scrubber in the form of a bubble tower for treating radioactive exhaust gas generated in a molten salt reactor, and a method for separating particles using the molten salt scrubber.

[0002] A scrubber is a device that removes gaseous hazardous substances or particles contained within a gas stream, and is broadly classified into dry scrubbers and wet scrubbers. Among these, wet scrubbers are widely used industrially as they remove hazardous substances within the gas by contacting the gas with a liquid through methods such as absorption, neutralization, and precipitation. In a typical wet scrubber, the liquid is sprayed from the top to the bottom of the scrubber, and a countercurrent flow is induced in which the gas is injected from the bottom to the top to capture specific hazardous substances contained within the gas.

[0003] In molten salt reactors, wet scrubbers are used to purify exhaust gases containing radioactive materials before they are released from inside the reactor to the outside. Radioactive materials generated during the operation of molten salt reactors include gases such as inert gases, chlorides, iodides, hydrides, and sulfides, as well as fine particulate matter. Wet scrubbers in the reactor play a role in preventing the leakage of radioactive materials that may occur during the reactor's emergency or operation.

[0004] In particular, while conventional commercial wet scrubbers use a liquid in which sodium hydroxide (NaOH) or potassium hydroxide (KOH) is dissolved in water, water is difficult to use considering the high discharge temperature (around 600°C) of the exhaust gas generated from molten salt reactors. Therefore, molten salt scrubbers are being developed that utilize a eutectic salt composed of sodium hydroxide, potassium hydroxide, or both sodium hydroxide and potassium hydroxide as a liquid. Furthermore, in the United States, molten salt scrubbers for application in molten salt reactors are being developed using a method that applies the countercurrent flow of the exhaust gas to the molten salt, which is widely used industrially (J. McFarlane et al. Fission Product Volatility and Off-Gas Systems for Molten Salt Reactors, ORNL / TM-2019 / 1299, PNNL-28974, 2019).

[0005] As mentioned above, wet scrubbers operate by injecting molten salt from the top of the scrubber to capture reactive gases and particulate matter within the liquid through the reaction between the exhaust gas and molten salt droplets in the internal packing layer. However, considering the specific circumstances of molten salt reactors, wet scrubbers present challenges when applied to the treatment of their exhaust gases. This type of scrubber requires the use of pumps capable of transporting the molten salt for circulation; however, ensuring safety is difficult given that molten salt reactors operate continuously for 20 to 30 years, and the injection method used to spray the molten salt can lead to clogging of the injection nozzles. Furthermore, since the molten salt must remain in a liquid state within the scrubber, the entire device must be heated above the melting point of the salt, and operation of the scrubber becomes difficult if even a single part of the device cools down. In the prior art US 2024-0084783 A1, a system for recovering molten salt material from electrolysis is disclosed, but a new type of molten salt scrubber is not disclosed.

[0006] Accordingly, a new type of molten salt scrubber is required to solve the problems of existing injection-type molten salt scrubbers.

[0007] The object of the present invention is to provide a molten salt scrubber in the form of a bubble tower, which is a new type that can be operated without having an overall heating or insulation system, and a method for separating particles using the molten salt scrubber.

[0008] Another objective of the present invention is to provide a molten salt scrubber and a method for separating particles using the molten salt scrubber to secure high capture efficiency.

[0009] Another objective of the present invention is to provide a molten salt scrubber capable of continuous operation for a long period without a separate molten salt transfer pump and without replacing the molten salt, and a method for separating particles using the molten salt scrubber.

[0010] To achieve the above-mentioned purpose, the apparatus comprises: a reactor having an open side; a molten salt vessel located inside the reactor and having a double-layer structure; a cover located above the reactor and covering the opening of the reactor; a dispersion tube inserted into the interior of the molten salt vessel through the cover and extending to the bottom of the molten salt vessel to transport gas introduced from the outside and disperse it in the form of bubbles; and a plurality of pressure transducers located outside the molten salt vessel that convert the lower pressure value and the upper pressure value inside the molten salt vessel into data and transmit them to an external data storage facility, wherein the molten salt vessel comprises a first part formed in the shape of a cylinder or polygonal prism with an open top side; The present invention provides a molten salt scrubber comprising a first part and a second part located above the first part and having a cross-sectional size larger than that of the first part, wherein the upper end of the first part protrudes above the lower end of the second part so that at least a portion of the second part surrounds the upper end of the first part from the outside, thereby forming a ring-shaped sedimentation area between the outer side of the first part and the inner side of the second part, wherein among a plurality of pressure transducers, the first pressure transducer converts a lower pressure value measured at the first connecting pipe into data, and the second pressure transducer converts an upper pressure value measured at the second connecting pipe into data, wherein the first connecting pipe extends through the cover to the lower part of the first part, and the second connecting pipe extends through the cover to the upper part of the first part.

[0011] In addition, to achieve the above-mentioned objective, the present invention may provide a particle removal system comprising a molten salt scrubber including a molten salt container having a double-layer structure; and an extraction unit for separating particles generated by the operation of the molten salt scrubber and settled in a sedimentation area, wherein the extraction unit includes an extraction tube inserted into the molten salt container to extract particles settled in the sedimentation area; an outer container for receiving particles extracted from the sedimentation area; and a pressure reduction pump for forming a pressure difference between the extraction tube and the outer container, wherein the molten salt container includes a first part formed in the shape of a cylinder or polygonal prism with an open top and a second part located above the first part and having a cross-sectional size larger than that of the first part, and the sedimentation area is formed in a ring shape between the outer side of the first part and the inner side of the second part, such that the upper end of the first part protrudes above the lower end of the second part, and at least a portion of the second part wraps around the upper end of the first part from the outside.

[0012] In addition, to achieve the above-mentioned objective, the present invention may provide a method for separating particles using a molten salt scrubber, comprising the steps of: introducing molten salt into a molten salt container having a double-layer structure; injecting gas into a reactor through a dispersion tube inserted into the molten salt container; and, wherein the gas injected through the dispersion tube is discharged from a gas discharge tube located at the bottom of the dispersion tube and becomes a bubble by bubbling, and the bubble-shaped gas containing particles rises to the top of a first part formed in the shape of a cylinder or polygonal column with an open top, and the bubble-shaped gas is separated from the particles by the top of the first part, and the separated particles settle at the bottom of a second part located at the top of the first part and having a cross-sectional size larger than that of the first part, and then extracting the settled particles.

[0013] The effects of the present invention obtained through the above-described solution are as follows.

[0014] Through the present invention, unlike conventional molten salt scrubbers that require overall heating, a new type of molten salt scrubber in the form of a bubble tower that can be operated without heating the entire molten salt scrubber, and a method for separating particles using the molten salt scrubber can be provided.

[0015] In addition, through the double-layer structure of the molten salt scrubber, reactive gases and particulate matter can be captured with higher efficiency than conventional molten salt scrubbers, and the amount of reaction dispersions and particulate matter remaining in the molten salt can be minimized.

[0016] In addition, by minimizing reaction dispersions and particulate matter remaining in the molten salt through the double-layer structure of the molten salt scrubber, a separate molten salt transfer pump is not required, and the molten salt scrubber can be operated continuously without interruption using the existing molten salt without replacing the molten salt.

[0017] FIG. 1 is a conceptual diagram showing a molten salt scrubber proposed in the present invention.

[0018] Figure 2 is a photograph showing the gas discharge pipe of the dispersion pipe in the molten salt scrubber of the present invention.

[0019] Figure 3 is a photograph showing a perforated basket, which is an example of an adsorbent receiving portion among the components of the molten salt scrubber proposed in the present invention.

[0020] Figure 4 is a graph showing the change in gas retention amount and flow characteristics according to the gas flow rate in the molten salt scrubber of the present invention.

[0021] Figure 5 is a graph showing the flow region transition characteristics in a typical bubble tower reactor.

[0022] Figure 6 is a photograph showing a connecting pipe connected to a pressure transducer among the components of the molten salt scrubber proposed in the present invention.

[0023] Figure 7 is a graph showing the lower pressure and upper pressure values ​​converted by the pressure transducer in the configuration of the molten salt scrubber proposed in the present invention.

[0024] FIG. 8 is a conceptual diagram showing a particle removal system equipped with a molten salt scrubber of the present invention.

[0025] FIG. 9 is a flowchart illustrating a particle separation method using a molten salt scrubber proposed in the present invention.

[0026] FIG. 10 is a conceptual diagram of discharging particulate matter by gas dispersion in a molten salt scrubber of the present invention.

[0027] Hereinafter, a molten salt scrubber and a particle separation method using a molten salt scrubber related to the present invention will be described in more detail with reference to the drawings.

[0028] In this specification, identical or similar reference numbers are assigned to identical or similar components even in different embodiments, and redundant descriptions thereof are omitted.

[0029] In describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted.

[0030] The attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0031] In the following description, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0032] In this application, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0033] Hereinafter, the molten salt scrubber proposed in the present invention will be described.

[0034] FIG. 1 is a conceptual diagram showing a molten salt scrubber (100) in the form of a bubble tower proposed in the present invention. Referring to FIG. 1, the molten salt scrubber (100) includes a reactor (110), a molten salt container (120), a cover (130), a dispersion tube (140), a heater (150), a metal sieve plate (160), an adsorbent receiving portion (170), and a plurality of pressure transducers (P1, P2).

[0035] The reactor (110) is formed with one side open so that a molten salt container (120) can be inserted into the reactor (110). Here, one side may refer to the upper side. The reactor (110) is located adjacent to the heater (150), and the reactor (110) may be made of a heat-resistant metal material so as to maintain its physical properties even when heat is applied.

[0036] The molten salt container (120) may be located inside the reactor (110) and may be formed to contain molten salt inside. Since the molten salt container (120) is a space for containing molten salt, which is a salt in a liquid state, the molten salt container (120) may be made of a metal material having heat resistance and corrosion resistance. Here, the metal forming the molten salt container (120) may have heat resistance so as to maintain its physical properties even when heat is applied, and the metal may have corrosion resistance so as to prevent corrosion caused by the molten salt.

[0037] Meanwhile, the molten salt container (120) may have a double-layer structure with a difference in the size of the cross-sections at the bottom and top. Here, a cross-section refers to the surface that appears when the molten salt container (120) is cut horizontally and viewed from above. The molten salt container (120) viewed from above may have two cross-sections, and the cross-section at the bottom and the cross-section at the top may have a difference in size.

[0038] A molten salt container (120) having a double-layer structure can be described as comprising a first part (121) and a second part (122). The first part (121) is formed with an open upper side and may be in the form of a cylinder or a polygonal prism. Accordingly, the lower cross-section corresponding to a part of the first part (121) may be a circle or a polygon.

[0039] A second part (122) connected to a first part (121) is located above the first part (121) and may have a cross-sectional area larger than that of the first part (121). Accordingly, at least a portion of the second part (122) is structured to surround at least a portion of the first part (121).

[0040] At this time, the upper part of the first part (121) may be formed to protrude above the lower part of the second part (122) so that at least a portion of the second part (122) wraps around the upper part of the first part (121) from the outside. From this structure, a ring-shaped sedimentation area (P) may be formed between the outer side of the first part (121) and the inner side of the second part (122). The sedimentation area (P) may have a structure in which particulate matter separated from bubbles during the operation of the molten salt scrubber (100) can settle.

[0041] If the upper part of the first part (121) is not formed in a structure that protrudes above the lower part of the second part (122), the upper part of the first part (121) and the lower part of the second part (122) are simply connected. In this case, a ring-shaped sedimentation area (P) enclosed by the outer side of the first part (121) and the inner side of the second part (122) is not formed.

[0042] Here, the ring of the sedimentation area (P) formed between the outer side of the first part (121) and the inner side of the second part (122) does not mean only a circular shape, but may be a polygonal shape. In this case, the inner side of the ring may be formed based on the top of the first part (121), and the outer side of the ring may be formed based on the outer side of the second part (122).

[0043] Meanwhile, the depth of the ring-shaped sedimentation area (P) formed between the outer side of the first part (121) and the inner side of the second part (122) may be 5 cm or less. Since particulate matter separated from bubble-shaped gas settles into the sedimentation area (P), if the depth of the sedimentation area (P) exceeds 5 cm, an excessive amount of particulate matter may accumulate, making extraction difficult.

[0044] The molten salt scrubber (100) proposed in the present invention may include a cover (130) positioned above the reactor (110) to cover the opening of the reactor (110). By covering the opening of the reactor (110), the cover (130) can prevent the immediate release of gas and prevent the escape of molten salt. Since the cover (130) comes into contact with the molten salt, just like the molten salt container (120), it may be made of a metal material having heat resistance and corrosion resistance. Here, the metal forming the cover (130) may have heat resistance to maintain its physical properties even when heat is applied, and the metal may have corrosion resistance to prevent corrosion caused by the molten salt.

[0045] Additionally, the molten salt scrubber (100) proposed in the present invention may include a dispersion tube (140). The dispersion tube (140) penetrates the cover (130) and is inserted into the interior of the molten salt container (120), and may extend to the bottom of the molten salt container (120). The dispersion tube (140) may serve to disperse helium-based radioactive exhaust gases discharged from the molten salt reactor into the molten salt in the form of small bubbles so as to react with the molten salt. To this end, the dispersion tube (140) may penetrate the cover (130) and extend to the bottom of the molten salt container (120), and the dispersion tube (140) may include a sparger, which is a gas discharge tube (141), at the bottom.

[0046] FIG. 2 is a photograph showing the gas discharge pipe (141) of the dispersion pipe (140) in the molten salt scrubber (100) of the present invention. Referring to FIG. 2, the gas discharge pipe (141) may be formed of a cross-shaped sparger, and the sparger may include two or more dispersion holes. At this time, the dispersion holes may be arranged radially at regular intervals to ensure even generation of bubbles.

[0047] Meanwhile, the gas discharge pipe (141) may have a cross shape or a radial shape. If it has a cross shape or a radial shape, the surface area of ​​the gas discharge pipe (141) increases, which can increase the number of bubbles discharged per unit area and make it possible to generate small bubbles evenly in the radial direction.

[0048] The size of the dispersion hole can be 0.1 mm or larger and 0.5 mm or smaller, and the size may vary depending on the particle size contained in the exhaust gas. Since the particle size generated in the molten salt reactor can be 1 to 10 μm in the case of molten salt aerosol and 0.01 to 10 μm in the case of noble metal insoluble in the molten salt, preferably, the size of the dispersion hole of the gas discharge pipe (141) for the dispersion of radioactive exhaust gas can be 0.1 mm. If the size of the dispersion hole is smaller than 0.1 mm, clogging of the dispersion hole may occur due to particles contained in the exhaust gas and particulate impurities generated in the molten salt. On the other hand, if the size of the dispersion hole is larger than 0.5 mm, the size of the bubbles emitted from the dispersion hole may become excessively large.

[0049] As the range of diameters provided by the multiple dispersion spheres is presented as above, the diameter of the bubbles discharged from the dispersion spheres may be 5 mm or less.

[0050] The length of the sparger, which is the gas discharge pipe (141), can be positioned 5 to 10 mm inward from the inner wall of the molten salt container (120) for radial even dispersion within the molten salt container (120).

[0051] Referring again to FIG. 1, the molten salt scrubber (100) proposed in the present invention may include a heater (150) surrounding the outside of a reactor (110). The heater (150) may heat the molten salt located within the molten salt container (120) to maintain it in a liquid state. The molten salt in a liquid state condition may cause exhaust gas injected from the dispersion pipe (140) to come out of the gas discharge pipe (141) and rise in the form of bubbles toward the opening of the molten salt container (120). The heater (150) used in the present invention may be an electric furnace.

[0052] Meanwhile, the molten salt scrubber (100) proposed in the present invention may further include a metal sieve plate (160). Generally, bubbles generated at the bottom of a bubble tower reactor grow larger as they rise along the top of the reactor. As the size of the bubbles increases, the rising speed of the bubbles increases, which not only reduces reaction efficiency but also causes a large amount of liquid to be discharged. To minimize this phenomenon, a metal sieve plate (160) may be positioned on the rising path of bubbles that rise along the molten salt container (120) after being discharged from a gas discharge pipe (141) located at the bottom of a dispersion pipe (140).

[0053] Therefore, the metal sieve plate (160) can prevent the aggregation of bubbles and improve reactivity by increasing the residence time of bubbles in the molten salt.

[0054] Preferably, the metal sieve plate (160) may be installed at a height corresponding to 2 to 3 times the inner diameter or the inner diameter (D) of the inscribed circle from the bottom of the molten salt container (120) or the bottom of the sedimentation area (P), and the metal sieve plate (160) may be made of a metal material having heat resistance and corrosion resistance. The metal forming the metal sieve plate (160) may have heat resistance so as to maintain its physical properties even when heat is applied, and the metal may have corrosion resistance so as to prevent corrosion by the molten salt.

[0055] In the present invention, the flow rate of the gas injected into the dispersion tube (140) can be set to 1 cm / s or more and 2 cm / s or less.

[0056] FIG. 4 is a graph showing the change in gas retention amount and the change in flow characteristics according to the gas flow rate in the molten salt scrubber (100) of the present invention. Referring to FIG. 4, Ug shown on the x-axis represents the gas flow rate, and ε grepresents the gas retention amount. To exhibit uniform flow characteristics, a speed of 2 cm / s or less must be maintained. If the speed is higher than 2 cm / s, non-uniform flow characteristics may occur. On the other hand, if the gas flow velocity is less than 1 cm / s, the gas retention amount decreases and bubble-shaped gas does not rise sufficiently, so particles contained in the bubbles may not be separated smoothly.

[0057] At this time, the inner diameter of the first part (121) or the inner diameter (D) of the inscribed circle may be 100 mm or more. If the first part (121) is in the shape of a cylinder, the inner diameter (D) may be 100 mm or more because the cross-section corresponds to a circle. Also, if the first part (121) is in the shape of a polygonal prism, the inner diameter (D) of the inscribed circle tangent to the polygon may be 100 mm or more because the cross-section corresponds to a polygon.

[0058] Figure 5 is a graph showing the flow domain transition characteristics in a typical bubble tower reactor. The flow domain transition characteristics of a bubble tower reactor represent the characteristics of bubble flow at room temperature. Generally, the flow characteristics in a bubble tower change from a homogeneous to a heterogeneous flow form depending on the gas flow rate.

[0059] For a uniform flow to occur, the bubbles must either be of a uniform shape (perfect bubbly) or, even if non-uniform, have similar bubble sizes (imperfect bubbly or bad bubbly). Non-uniform flow exhibits low efficiency due to a reduction in the surface area between the gas and the molten salt caused by large bubbles rising rapidly in the molten salt layer, and can discharge a large amount of liquid from the top of the molten salt layer.

[0060] Non-uniform flow can appear in two types. It can appear as churn turbulent flow, where the gas and liquid are mixed at high speed and flow violently and disorderly, or as slug flow, where the gas and liquid flow separately, with the gas existing in the form of long, continuous bubbles and the liquid trapped between the bubbles.

[0061] Referring to FIG. 5, under conditions where the superficial gas velocity is 1 cm / s or more and 2 cm / s or less, if the inner diameter of the first part (121) or the inner diameter (D) of the inscribed circle is 100 mm or more, a uniform flow region can be represented. If, under appropriate superficial gas velocity conditions, the inner diameter of the first part (121) or the inner diameter (D) of the inscribed circle is smaller than 100 mm, a non-uniform flow shape is formed.

[0062] Referring again to FIG. 1, in the molten salt scrubber (100) proposed in the present invention, the cover (130) may form an outlet through which gas is discharged. The gas, in a form from which particles have been removed, is discharged to the outside of the molten salt container (120) through the outlet. At this time, in the case of reactive gases contained in the radioactive exhaust gas discharged from the molten salt reactor, some moisture may be generated and discharged through reaction with the molten salt. In addition, some molten salt aerosol or some particulate matter that does not remain in the molten salt may be discharged to the outside of the molten salt scrubber (100). To minimize the discharge of moisture and particulate matter, the molten salt scrubber (100) proposed in the present invention may further include an adsorbent receiving section (170) installed within the reactor (110). The adsorbent receiving section (170) may be located upstream of the gas discharge path through the outlet.

[0063] The adsorbent receiving portion (170), like the metal sieve plate (160), is located within the molten salt container (120) and can be made of a metal material having heat resistance and corrosion resistance. Here, the metal forming the adsorbent receiving portion (170) may have heat resistance to maintain its physical properties even when heat is applied, and the metal may have corrosion resistance to prevent corrosion caused by the molten salt.

[0064] Additionally, the adsorbent receiving portion (170) may be formed in the shape of a column with holes so as to be in contact with gas. In this case, the column shape may be in the shape of a cylinder or a polygonal column.

[0065] FIG. 3 is a photograph showing a perforated basket, which is an embodiment of the adsorbent receiving portion (170) of the molten salt scrubber proposed in the present invention. Referring to FIG. 3, it can be seen that the perforated basket for receiving the adsorbent has one side open and is made of a surface with holes drilled to allow contact with gas. Here, the perforated basket is formed in the shape of a cylinder with one side open.

[0066] The adsorbent received in the adsorbent receiving portion (170) can adsorb moisture and particulate matter contained in the gas. The adsorbent is a material having the property of adsorbing substances on its surface, and in the molten salt scrubber (100) proposed in the present invention, zeolite, activated carbon, silica gel, etc. can be used as the adsorbent.

[0067] In addition, the molten salt scrubber (100) proposed in the present invention may include a plurality of pressure transducers (P1, P2).

[0068] Referring again to FIG. 1, a plurality of pressure transducers (P1, P2) may be located outside the molten salt container (120), and may convert the lower pressure value and the upper pressure value inside the molten salt container (120) into data and transmit them to an external data logger. The lower pressure data and upper pressure data transmitted to the data logger may then be transmitted to a computer.

[0069] FIG. 6 is a photograph showing a connecting pipe connected to a pressure converter (P1, P2) in the configuration of a molten salt scrubber (100) proposed in the present invention.

[0070] Referring to FIG. 6, the first pressure transducer (P1) can convert the lower pressure value measured at the first connecting pipe (L1) into data. The first connecting pipe (L1) can extend through the cover (130) to the lower part of the first part (121) and can be made of a metal material having heat resistance and corrosion resistance.

[0071] The second pressure transducer (P2) can convert the upper pressure value measured at the second connecting pipe (L2) into data. The second connecting pipe (L2) can extend through the cover (130) to the upper part of the first part (121), and the second connecting pipe (L2) can be made of a metal material having heat resistance and corrosion resistance, just like the first connecting pipe (L1).

[0072] FIG. 7 is a graph showing the lower pressure value and the upper pressure value converted by the pressure converter (P1, P2) in the configuration of the molten salt scrubber (100) proposed in the present invention.

[0073] Referring to FIG. 7, the lower pressure data converted at the first pressure transducer (P1) is P L It may correspond to, and the upper pressure data converted at the second pressure transducer (P2) is P U It may apply to.

[0074] When the gas flow velocity is 0.01 m / s, or 1 cm / s, there is no significant change in pressure values, whereas when the gas flow velocity increases to 0.03 m / s and 0.05 m / s, it can be observed that the change in pressure values ​​becomes relatively larger. It is determined that the increase in pressure values ​​is the result of unstable conditions being formed as the number of bubbles generated inside the molten salt scrubber increases due to the increase in gas flow velocity.

[0075] Meanwhile, the molten salt used in the molten salt scrubber (100) proposed in the present invention may be any one of sodium hydroxide, potassium hydroxide, and sodium hydroxide-potassium hydroxide eutectic salt.

[0076] Sodium hydroxide (NaOH) is a basic substance with a melting point of about 323°C and can be effective in absorbing chlorine-based gases and acidic gases. Potassium hydroxide (KOH) is a basic substance with a melting point of about 410°C and can be used to remove acidic gases such as chlorine and hydrogen fluoride.

[0077] Sodium hydroxide-potassium hydroxide eutectic salts can maintain a molten state at a lower temperature than using sodium hydroxide or potassium hydroxide alone, thereby exhibiting high energy efficiency and reducing high-temperature corrosion problems. The molar ratios of sodium hydroxide and potassium hydroxide contained in the sodium hydroxide-potassium hydroxide eutectic salt may correspond to 0.51 mol% and 0.49 mol%, respectively. A sodium hydroxide-potassium hydroxide eutectic salt having the above molar ratios may have a melting temperature of 170°C.

[0078] Hereinafter, a particle removal system equipped with a molten salt scrubber proposed in the present invention will be described.

[0079] FIG. 8 is a conceptual diagram showing a particle removal system equipped with a molten salt scrubber according to the present invention. Referring to FIG. 8, the particle removal system equipped with a molten salt scrubber may include a molten salt scrubber (100) and an extraction unit (180). Here, the molten salt scrubber (100) may include a molten salt container (120) having a double-layer structure with a difference in cross-sectional size between the lower and upper parts, and the extraction unit (180) may separate particles generated by the operation of the molten salt scrubber (100) and settled in a sedimentation area (P).

[0080] Here, the molten salt container (120) may include a first part (121) and a second part (122) as mentioned above. The first part (121) is formed in the shape of a cylinder or polygonal prism with an open top, and the second part (122) is located on top of the first part (121) and may have a cross-sectional size larger than that of the first part (121).

[0081] The extraction section (180) may include an extraction pipe (181), gas valves (182a, 182b), an outer container (183), a pressure reducing pump (184), connecting pipes (185a, 185b), and an insulating material (186). At this time, the extraction pipe (181) and the connecting pipes (185a, 185b) may be pipes made of a metal material having heat resistance and corrosion resistance. The metal forming the extraction pipe (181) and the connecting pipes (185a, 185b) may have heat resistance to maintain physical properties even when heat is applied, and the metal may have corrosion resistance to prevent corrosion by molten salt.

[0082] The extraction tube (181) and connecting tubes (185a, 185b) are insulated by an insulating material (16), and the temperature of the extraction tube (181) and connecting tubes (185a, 185b) must be maintained above the melting point so that the salt does not cool down.

[0083] Among the components of the extraction unit (180), the extraction tube (181) is inserted into the molten salt container (182) to extract particles precipitated in the precipitation area (P). When a pressure difference occurs between the extraction tube (181) and the outer container (183), the extraction tube (181) can extract molten salt containing a large amount of small particles.

[0084] The outer container (183) can receive particles extracted from the sedimentation area (P). For the pressure to be reduced by the pressure reduction pump (184), the gas valve (182b) adjacent to the pressure reduction pump (184) must be open. Subsequently, the outer container (183) under reduced pressure conditions can receive particles from the extraction pipe (181) due to the pressure difference. For the outer container (183) to receive particles, the gas valve (182a) adjacent to the extraction pipe (181) must be open.

[0085] The amount of particles that can be accommodated may vary depending on the size of the outer container (183), and the outer container (183) may be made of a metal material having heat resistance and corrosion resistance. The metal forming the outer container (183) may have heat resistance to maintain its physical properties even when heat is applied, and the metal may have corrosion resistance to prevent corrosion by molten salt.

[0086] The pressure reduction pump (184) can create a pressure difference between the extraction tube (181) and the outer container (183). If the pressure reduction pump (184) is not operated, the pressure between the extraction tube (181) and the outer container (183) is equal, making it difficult to move particles contained in the molten salt.

[0087] Hereinafter, a particle separation method using a molten salt scrubber proposed in the present invention will be described.

[0088] FIG. 9 is a flowchart illustrating the operation method of a molten salt scrubber proposed in the present invention. Referring to FIG. 9, the operation method of the molten salt scrubber of the present invention begins with the step (S110) of introducing molten salt into a molten salt container (120) having a double-layer structure. Here, the molten salt may be introduced after the dispersion tube (140) is inserted into the molten salt container (120), and the dispersion tube (140) may be inserted into the molten salt container (120) after the molten salt is introduced.

[0089] At this time, the amount of molten salt introduced can be filled up to the top height of the first part (121) in the molten salt container. In order for the molten salt to be filled up to the top height of the first part (121), the volume of the dispersion tube (140) must be taken into account.

[0090] In the step (S110) of introducing molten salt into the molten salt container (120) having a double-layer structure, the ratio of the height of the molten salt layer filled in the molten salt container (120) to the inner diameter of the first part (121) or the inner diameter (D) of the inscribed circle may be 4 to 10 times. At this time, the ratio of the height of the molten salt layer to the inner diameter or the inner diameter (D) of the inscribed circle corresponds to the diameter-to-height ratio. If the ratio of diameter to height exceeds 10 times, large bubbles may be formed due to the aggregation of bubbles, which may cause a decrease in reactivity due to the reduction of plug flow and back mixing phenomena. On the other hand, if the ratio of diameter to height does not exceed 4 times, the residence time of the gas is short, resulting in low reaction efficiency.

[0091] After the step (S110) of introducing molten salt into the molten salt container (120), the step (S120) of injecting gas into the reactor (110) through the dispersion tube (140) inserted into the molten salt container (120) is carried out. The gas injected into the reactor (110) mainly consists of helium gas and may also consist of radioactive exhaust gases. The radioactive exhaust gases may consist of inert gases such as krypton, xenon, and argon, gases such as chlorides, iodides, hydrides, and sulfides, and fine particulate matter such as fuel salt aerosols.

[0092] After the step (S120) of injecting gas into the reactor (110), the gas injected through the dispersion pipe (140) is discharged from the gas discharge pipe (141) located at the bottom of the dispersion pipe (140) and becomes a bubble form by bubbling. The bubble-shaped gas containing particles rises to the top of the first part (121), which is formed in the shape of a cylinder or polygonal column with an open top. The bubble-shaped gas is separated from the particles by the top of the first part (121). When the separated particles settle at the bottom of the second part (122), which is located at the top of the first part (121) and has a cross-sectional size larger than that of the first part (121), the step (S130) of extracting the settled particles is performed.

[0093] Since the molten salt in a liquid state is contained inside the molten salt container (120), the gas injected through the dispersion tube (140) can be discharged by bubbling from the dispersion port of the sparger, which is the gas discharge tube (141) located at the bottom of the dispersion tube (140). At this time, the bubbles generated by bubbling may contain particulate matter.

[0094] Thus, the gas in the form of bubbles containing particles can rise to the top of the first part (121), which is formed in the shape of a cylinder or polygonal column with an open top, in the configuration of the molten salt container (120). Since the molten salt is filled up to a height corresponding to the top of the first part (121), the gas in the form of bubbles can rise to the top of the first part (121).

[0095] When the bubble-shaped gas rises to the top of the first part (121) of the molten salt container (120), the bubble-shaped gas can be separated from the particles by the top of the first part (121). The bubble-shaped gas that occurs first can be pushed out to the outer part of the molten salt layer by the continuous rise of the bubble-shaped gas that occurs later. In the process, the bubble-shaped gas comes into contact with the top of the first part (121) and bursts, and the particles attached to the bubble can be detached from the bubble.

[0096] FIG. 10 is a conceptual diagram of the discharge of particulate matter by gas dispersion in the molten salt scrubber of the present invention. Referring to FIG. 10, when large bubbles burst, a large amount of particulate matter is dispersed compared to small bubbles. Therefore, small bubbles must be maintained, and the risk of particles detached from small bubbles being dispersed is lower compared to large bubbles.

[0097] When the gas in the form of bubbles is separated from the particles, the separated particles are located at the top of the first part (121) and can settle at the bottom of the second part (122), which has a cross-sectional size larger than that of the first part (121). Since the particles have a solid form and are denser than the molten salt in liquid form, they can settle at the bottom of the second part (122).

[0098] After the particles settle, the settled particles can be extracted. The settled particles can be extracted by the extraction tube (181) in the composition of the extraction unit (180) and can be received in an external container (183) by passing through the connecting tube (185a).

[0099] The foregoing description is merely illustrative, and various modifications may be made by those skilled in the art without departing from the scope and technical spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

[0100] The present invention can be used in related fields requiring the capture of reactive gases and particulate matter in molten salt scrubbers.

Claims

1. A reactor with one side open; A molten salt container located inside the above reactor and having a double-layer structure; A cover positioned above the reactor and covering the opening of the reactor; and A dispersion tube that penetrates the cover and is inserted into the interior of the molten salt container, extends to the bottom of the molten salt container to transport gas flowing in from the outside and disperse it in the form of bubbles; and It includes a plurality of pressure transducers located outside the molten salt container, which convert the lower pressure value and the upper pressure value inside the molten salt container into data and transmit them to an external data storage. The above molten salt container is, A first part formed in the shape of a cylinder or polygonal column with an open upper side; and It includes a second part located above the first part and having a cross-sectional area larger than that of the first part, As the upper part of the first part protrudes above the lower part of the second part so that at least a portion of the second part wraps around the upper part of the first part from the outside, a ring-shaped sedimentation area is formed between the outer side of the first part and the inner side of the second part. Among the plurality of pressure transducers, the first pressure transducer converts the lower pressure value measured at the first connecting pipe into data, and the second pressure transducer converts the upper pressure value measured at the second connecting pipe into data. The first connecting pipe extends through the cover to the lower part of the first part, and the second connecting pipe extends through the cover to the upper part of the first part. Molten salt scrubber.

2. In Paragraph 1, The flow velocity of the gas injected into the above dispersion tube is set to be 1 cm / s or more and 2 cm / s or less, and The inner diameter of the first part or the inner diameter of the inscribed circle is 100mm or more, Molten salt scrubber.

3. In Paragraph 1, The above molten salt scrubber further includes a metal sieve plate installed inside the molten salt container, The metal sieve plate is located on the rising path of bubbles that rise along the molten salt container after being discharged from the gas discharge pipe located at the bottom of the dispersion tube. Molten salt scrubber.

4. In Paragraph 3, The gas discharge pipe having a plurality of dispersion holes has a shape of either a cross shape or a radial shape, The diameter of the plurality of the above dispersion spheres is 0.1 mm or more and 0.5 mm or less, Molten salt scrubber.

5. In Paragraph 1, The above cover has a vent formed therein for discharging gas, and The above molten salt scrubber further includes an adsorbent receiving portion installed within the reactor, and The above-mentioned adsorbent receiving portion is located upstream of the gas discharge path through the above-mentioned outlet, and the above-mentioned adsorbent receiving portion contains an adsorbent that adsorbs moisture and particles contained in the gas. Molten salt scrubber.

6. A molten salt scrubber comprising a molten salt vessel having a double-layer structure; and It includes an extraction unit that separates particles generated by the operation of the above molten salt scrubber and settled in the sedimentation area, The above extraction unit is, An extraction tube inserted into the molten salt container to extract particles precipitated in the precipitation area; An outer container for receiving particles extracted from the above sedimentation area; and It includes a pressure reducing pump that forms a pressure difference between the extraction tube and the outer container, and The molten salt container comprises a first part formed in the shape of a cylinder or polygonal prism with an open top, and a second part located above the first part and having a cross-sectional size larger than that of the first part. The above sedimentation region is formed in a ring shape between the outer side of the first part and the inner side of the second part, such that the upper part of the first part protrudes above the lower part of the second part, and at least a portion of the second part wraps around the upper part of the first part from the outside. Particle removal system equipped with a molten salt scrubber.

7. A step of introducing molten salt into a molten salt container with a double-layer structure; A step of injecting gas into the reactor through a dispersion tube inserted inside the molten salt container; and The gas injected through the dispersion tube is discharged from a gas discharge tube located at the bottom of the dispersion tube and becomes a bubble by bubbling, and the gas in the form of bubbles containing particles rises to the top of a first part formed in the shape of a cylinder or polygonal prism with an open top, the gas in the form of bubbles is separated from the particles by the top of the first part, and the separated particles settle to the bottom of a second part located at the top of the first part and having a cross-sectional size larger than that of the first part, and the method includes the step of extracting the settled particles. Particle separation method using a molten salt scrubber.

8. In Paragraph 7, In the step of introducing the molten salt mentioned above, The height of the molten salt layer filled in the molten salt container is at least greater than the top height of the first part, Particle separation method using a molten salt scrubber.

9. In any one of paragraphs 1 through 5, The molten salt used in the above molten salt scrubber is, Corresponding to any one of sodium hydroxide, potassium hydroxide, and sodium hydroxide-potassium hydroxide eutectic salt Molten salt scrubber.

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