RU2595310C2 - Device for cleaning liquid metal medium from suspended impurities - Google Patents

Abstract

FIELD: nuclear energy.

SUBSTANCE: device for cleaning liquid metal medium from suspended impurities includes housing with inlet and outlet branch pipes and a filter inside the housing. Filter is made in the form of a core containing casing with inlet and outlet grates and arranged along the flow of liquid metal medium at least one section of coarse purification from suspended particles with size larger than or equal to 10 micrometers, and installed after it, at least one section of fine purification of suspended particles of micrometer or sub-micrometer size. Coarse section consists of at least one layer of filtering material with porosity of 80-90 % in the form of a needled fabric based on metal wool size of 40-60 mcm. Fine purification section consists of at least one layer of filtering material with porosity 70-80 % in the form of a needled fabric based on metal wool size of 10-40 mcm and/or glass fabric based on fibre with size of 6-20 mcm.

EFFECT: higher efficiency of cleaning liquid metal medium from suspended impurities is provided.

8 cl, 2 dwg

Description

Technical field

The invention relates to the field of chemical technology and nuclear energy and can be used to clean liquid, in particular, heavy metal, for example, a lead-bismuth eutectic alloy (45% Pb, 55% Bi) from suspended impurities.

State of the art

A device for pumping liquid metal and at the same time for cleaning it from ferromagnetic inclusions [SU 642503, publ. 01/18/1979, M. Cl. F04B 17/04]. The device is designed as an electromagnetic induction pump with a running magnetic field. In this case, the core serves as a metal path and a filter. The inhomogeneity of the magnetic field, affecting the efficiency of particle capture, is ensured by alternating in the flow part of the device protrusions and depressions, which respectively attract and subsequently hold ferromagnetic particles in the grooves.

The disadvantages of the known device are the inability to remove non-magnetic impurities and the complexity of the design due to the need to use an electromagnetic pump.

Closest to the claimed technical solution is a device for cleaning liquid metals from impurities in the form of microparticles ranging in size from 5 microns to 50 microns [SU 537120 A1, C22B 9/00, 11/30/1976].

The known device comprises a housing with inlet and outlet nozzles and a filter located inside the housing.

A disadvantage of the known device is: the inability to remove from a liquid metal suspensions of a nonmagnetic nature, for example, oxides: PbO, Bi ₂ O ₃ , Al ₂ O ₃ , etc., the relatively low efficiency of removing suspended particles of micron and submicron size (10-20% )

Disclosure of invention

The objective of the proposed solution is to increase the efficiency of purification of liquid metal in the circuit from suspended impurities, by increasing the capacity to retain impurities, increasing the heat resistance of the filter material and matching hydraulic resistance to the movement of a liquid metal medium (hereinafter also referred to as the coolant).

Technical results of the invention:

- increasing the efficiency of cleaning liquid metal coolant from suspended impurities, increasing the service life and capacity of the device, increasing the life of the reactor installation as a whole (by improving the quality (purity) of the coolant used);

- elimination of contamination of the main coolant circulation circuit with small hard-to-remove suspended suspended slag-forming impurities of colloidal size due to the use of needle-punched fabric with a fiber diameter minimally permissible under conditions of strength;

- a decrease in the concentration of particles in a circulating, for example, lead-bismuth coolant and, accordingly, in the gas system of nuclear power plants (to values that are safe for personnel during emergency depressurization of the gas circuit);

- providing savings due to the compactness of the device and the possibility of using the modular principle when creating cleaning devices of any performance;

- improving the reliability of the cleaning device due to the possibility of its operation in a wide range of temperatures and concentrations, ensuring the corrosion resistance of the materials used;

- ensuring high temperature resistance of the cleaning device.

The following distinctive features of the invention influence the achievement of each of the above technical results.

This object is achieved in that the device for cleaning liquid metal media from impurities contains a housing with inlet and outlet nozzles, a core located inside the housing with a shell filled with filter media, and gratings at the ends. The filtering filler is made in the form of a liquid-metal medium installed in the flow (in such a way that the coolant, when moving through the device from the inlet to the outlet, sequentially passes through each of the sections) sections. Sections are divided among themselves, for example, by plugs. Each section consists of one or more layers of filter material tightly laid on each other. At the same time, the first (one or several) sections along the stream are sections for rough cleaning of particles larger than or equal to ten micrometers, and one or more sections following in the direction of flow are sections for fine cleaning from micron or submicron particles. The coarse sections and the fine sections as filter material may contain, for example, needle-punched metal sheets. Coarse sections have a large porosity from 80 to 90%, a larger fiber size, for example, metal fibers, filter material from 40 to 60 microns. Fine sections have porosity from 70 to 80%, fiber size, for example, metal fibers from 10 to 40 microns. Fine sections may include, in addition to, or instead of metal fiber, fiberglass fibers based on fibers of 6 to 20 microns. The thickness of the filter material in the coarse and fine sections is from 3.0 to 7.0 mm. The number of fine and coarse sections can be selected, for example, from a ratio of 3: 1 to 10: 1, based on the corresponding estimated ratio of mass concentrations of micron or submicron particles and relatively large particles of a size greater than or equal to 10 μm in the liquid metal medium. In addition, the inlet and outlet nozzles are made with the possibility of hermetically connecting to the external elements of the inlet and outlet of the liquid metal medium. A choke made of porous cermet can be placed in front of the outlet pipes of the device to match the hydraulic resistance. It provides the required filter performance in relation to the total flow rate of the liquid metal medium along the circuit.

A brief description of the drawings.

FIG. 1. One of the variants of the device.

FIG. 2. Cross section AA of the device.

The implementation of the invention

In FIG. 1 shows: 1 - housing with a cover, 2 - inlet pipe, 3 - output pipes, 4 - core with a shell, 5 and 6 - gratings, 7 - coarse sections, 8 - fine sections, 9 - filter material, 10 - dividing sleeve, 11 - mesh, 12 - throttle.

In FIG. 2 shows: 1 - housing, 3 - output pipes, 4 - core with a shell, 9 - filter material.

One of the possible (but not the only) designs of the proposed device (Fig. 1 and 2) comprises a housing 1 with a cover, input 2 and output 3 pipes, a core with a sheath 4, separating bushings 10, which can be made, for example, of stainless steel 12X18H10T. Case 1 has a thickness of 4 mm, a height of 500 mm and an outer diameter of 85 mm. The spherical housing cover has a height of 60 mm. A core with a shell 4 and filtering material 9 is placed inside the housing 1, forming a gap of 10 mm with it. Through the inlet pipe 2 and through the grill 5, the coolant enters the inner cavity of the core 4, filled with filter medium 9 of a volume type. At the output of the core 4 there is a lattice 6 fixed, which secures the filter material 9. The filter material 9 is placed in sections divided by bushes 10 with a thickness of 0.8 mm. Each section above and below is limited by a grid 11. In the lower part of the annular gap on the side of the cleaned coolant, a choke 12 made of porous sintered metal can be placed in front of the outlet pipes to match the hydraulic resistance. It provides the required filter performance in relation to the total flow of the coolant along the circuit. The parameters of the throttle 12 are confirmed by calculation or direct measurements of hydraulic resistance during tests in specific operating conditions.

The filter material 9 located inside the core 4 is made of stacked needles made of needle-punched metal sheets, divided into coarse sections 7 and fine sections 8. The coarse material has a large porosity of 80 to 90% and a larger fiber size in the filter nozzle from 40 to 60 microns. Each section of fine cleaning contains 5 layers of needle-punched metal cloth 9, has a porosity of 70 to 80%, the size of the fibers of the filter material from 10 to 40 microns and / or fiberglass based on fibers from 6 to 20 microns. The selection of porosity of the filter material provides a uniform distribution gradient of microparticles. The thickness of the filter material in the sections of rough cleaning 7 and fine cleaning 8 is from 3.0 to 7.0 mm The diameter of the fibers in the sections of coarse 7 and fine 8 cleaning is selected from the condition of the maximum possible approximation to the size of the captured particles. The minimum diameter of the fibers of the filter material of the thin sections 8 is due to their strength, able to withstand the temperature and hydrodynamic effects of the coolant.

The inlet and outlet nozzles are made with the possibility of hermetically connecting to the external elements of the inlet and outlet of the liquid metal coolant in a nuclear power plant. In general, the installation is equipped with an external electric heater, which provides preliminary heating of the coolant before and during operation with a temperature not less than the melting temperature of the purified heavy liquid metal (not shown in Fig. 1).

Industrial applicability is confirmed by the following.

Through the inlet 2 and outlet 3 nozzles, the device is hermetically included in the flow path of the cleaned liquid metal coolant. Through the inlet pipe 2, the coolant enters the inner cavity of the core 4, filled with filtering material 9 volume type. In the first sections of coarse cleaning 7, the coolant, due to the sieve effect, undergoes cleaning mainly of large suspended particles with a size of more than 10 microns. Then, passing the subsequent sections of fine cleaning 8, the coolant is purified from suspensions of predominantly colloidal micron and submicron sizes. Moreover, in the free space of sections 7 and 8, formed by the bushings 10 of the core 4, the accumulation of slag deposits from the retained particles of the coolant in accordance with the pores formed by the diameter of the fibers of the filter material and the adhesion of colloidal suspensions to the fibers.

As a result of the proposed technical solution in the inner cavity of the core 4 there is a more uniform retention of suspensions, thereby increasing its resource capabilities and capacity. The liquid metal coolant, having passed all sections of the filter, cleaned from suspensions, through the outlet pipes 3 “leaves” the device and mixes with the general coolant flow.

In the process of cleaning the coolant, the device is gradually filled with impurities, accompanied by a decrease in its performance, an increase in hydraulic resistance, and a change in the linear flow rate to a minimum. With the appropriate testimony of control devices, indicating the development of a resource, the device must be replaced with a new one.

The test results of the experimental device in production conditions, with a nominal productivity for the cleaned coolant equal to 1 m ³ / h and a temperature of 350-500 ° C, showed that the proposed solution provides a hydrodynamic resistance of not more than 0.05 MPa and cleaning efficiency by weighted impurities up to 80-90% when the concentration of iron in the coolant is ~ 5 · 10 ^-4 % of the mass. and its linear velocity up to 2.0 cm / s. The device has low hydraulic resistance, increased cleaning efficiency and increased capacity for collecting impurities. Compared with strainers and filters based on cermets, the resource has been significantly increased - more than 2 years. The device has increased heat resistance - more than 550 ° C, determined by the strength of the used fibrous filter material.

Using the proposed device allows you to:

- to exclude contamination of the main circuit by small hard-to-remove suspended weighed slag-forming impurities of colloidal size due to the use of needle-punched fabric with a fiber diameter minimally acceptable according to the strength conditions;

- reduce the concentration of particles in the circulating lead-bismuth coolant and, accordingly, in the gas system of nuclear power plants; (to values that are safe for personnel during emergency depressurization of the gas circuit);

- to provide savings due to the compactness of the device and the possibility of using the modular principle when creating cleaning devices of any performance;

- to increase the reliability of the cleaning device due to the possibility of its operation in a wide range of temperatures and concentrations, ensuring the corrosion resistance of the materials used;

- provide high temperature resistance of the cleaning device.

The device of the claimed design is also promising for fine cleaning of liquid metal media in the nuclear, chemical and other industries, as it has high cleaning efficiency due to greater porosity, a more developed filter surface formed by micron-sized fibers in comparison with analogs, and ensures uniform distribution of the retention impurities in the cross section of the filter sections and the height of the device, has a greater capacity for retained impurities and, accordingly, is higher resources, for motion less hydraulic resistance of coolant and high thermal stability.

The device can be used for cleaning heavy liquid metals both in the conditions of their industrial production and in the operation of nuclear power plants in which these liquid metals are used as a coolant. In particular, the device can be used in a nuclear power plant for deep cleaning of lead-bismuth coolant from suspended impurities of any origin and dispersion, including those based on magnetite Fe ₃ O ₄ oxides Cr ₂ O ₃ , MnO, PbO, Bi ₂ O ₃ , polonides of PbPo and others.

Claims (8)

1. A device for cleaning a liquid-metal medium from suspended impurities, comprising a housing with inlet and outlet nozzles and a filter located inside the housing, characterized in that the filter is made in the form of a core containing a shell with gratings at the inlet and outlet and placed in it along the flow of the liquid-metal medium at least one section of coarse cleaning of suspended particles with a size greater than or equal to ten micrometers, and installed after it at least one section of fine cleaning of suspended micron particles or submicron size, wherein the coarse section consists of at least one layer of filter material with porosity from 80-90% in the form of a needle-punched fabric based on metal fibers with a size of 40-60 microns, the fine section consists of at least one layer of filter material with porosity of 70-80% in the form of a needle-punched web based on metal fibers of 10-40 microns in size and / or fiberglass based on fibers of 6-20 microns in size. 2. The device according to claim 1, characterized in that the ratio of the number of fine and coarse sections is selected taking into account the corresponding ratio in the liquid metal medium of the mass concentration of micron or submicron particles and suspended particles of a size greater than or equal to ten micrometers. 3. The device according to claim 1, characterized in that the sections installed downstream of the liquid metal medium are separated by bushes. 4. The device according to p. 1, characterized in that the ratio of the number of sections of fine cleaning to the number of sections of rough cleaning is selected in the range from 3: 1 to 10: 1. 5. The device according to p. 1, characterized in that in the rough cleaning section, the thickness of one layer of filter material is from 3.0 to 7.0 mm 6. The device according to p. 1, characterized in that the inlet and outlet nozzles are made with the possibility of tight connection to the elements of the inlet and outlet of the liquid metal medium. 7. The device according to claim 1, characterized in that a throttle is placed in front of the outlet pipe to provide a given performance with respect to the total flow rate of the liquid metal medium. 8. The device according to p. 7, characterized in that the throttle is made of porous cermet.

Images