Electromagnetic pump for pumping liquid metal and molten salts

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to magnetic-induction (magnetohydrodynamic) pumps for pumping molten metals. An electromagnetic pump for pumping liquid metal and molten salts includes a vertically oriented rotor, a motor functionally connected to the rotor, which is a shaft with permanent magnets of alternating polarity of radial magnetization, and a screw channel formed inside two coaxially located cylinders made in the form of a cylindrical body with a bottom. The outer cylinder has an inlet for liquid metal on the opposite side from the engine location and an outlet pipe for liquid metal located on the same side as the engine, connected to the spiral channel. The stator is located outside the outer cylinder and is made of soft magnetic metal. The shaft is located inside the inner cylinder and is designed to rotate inside it.EFFECT: ability to pump liquid metals and salt solutions from a residual liquid level of no more than 50 mm, measured from the centre of the inlet section of the pump nozzle, while simultaneously reducing the overall dimensions of the pump and maintaining or increasing the efficiency of the pump.4 cl, 4 dwg

Description

[0001] The invention relates to the field of electrical engineering, namely to magnetic-induction (magnetohydrodynamic) pumps for pumping molten metals.

[0002] A cylindrical induction pump is known (patent RU 2766431, published 15.11.2020, IPC: H02K 44 / 06, H02K 1 / 14), which comprises a cylindrical pump casing, inductors with inductor magnetic circuits and inductance coils arranged in a linear pattern along the surface of the pump casing. It also comprises a core coaxially located inside the casing to form an annular working channel with the core's magnetic circuits located inside the casing of its central cylindrical part. The inductor magnetic circuits are manufactured in the form of sets of E-shaped, parallel lamination plates made of electrical steel of variable height. The core's magnetic circuits are manufactured in the form of sets of longitudinal laminations made of electrical steel of variable height, arranged in longitudinal sectors formed by a supporting crosspiece with longitudinal ribs installed inside the core along its axis.The orientation of the laminations of the inductor magnetic circuits coincides with the orientation of the laminations of the corresponding magnetic circuits of the core inside the casing of the central cylindrical part of the core.

[0003] The common features of the known and claimed pumps are the presence of a cylindrical body, a channel for pumping the working medium, an active inductor for creating a working magnetic field and a passive inductor for closing it.

[0004] However, the location of the magnetic system and the channel configuration of the known pump do not allow it to be used for pumping liquid metals with a minimum residual level, as well as to ensure the effective lifting of liquid metal.

[0005] An induction pump is known (patent RU 2436223, published 10.12.2011, IPC: H02K 44 / 06) for pumping molten metal, comprising: a motor; a shaft operatively connected to the motor; at least one permanent two-pole magnet operatively connected to the shaft, and a non-magnetic channel for passing molten metal; wherein the motor drives said shaft and magnet relative to said channel with the possibility of inducing an electric current in molten metal located in the channel for pumping molten metal through the channel, which comes into contact only with said channel.

[0006] Common features of the known and claimed pumps are the presence of a motor, a shaft connected to the motor, at least one permanent magnet connected to the shaft and a channel for the passage of molten metal.

[0007] The disadvantage of this design is the low intensity of the generated magnetic field, which, along with the layout limitations, does not allow the pump to be used for pumping liquid metal with a minimum residual level.

[0008] An electromagnetic induction pump (application SU 526994 A1) is known. Its metal piping is made with a helical partition made of a cylindrical spiral with a flexible element inside. The partition is made of a cylindrical spiral of a non-magnetic material, wound with tightly fitting turns. The spiral diameter corresponds to the distance between the shells. This induction pump has improved energy characteristics—higher efficiency and stable performance—because the spiral partition offers little impedance to the current flow from one turn to the next through the metal and effectively inhibits the reverse flow of liquid metal.

[0009] The common features of the known and declared pumps is the presence of a spiral channel.

[0010] The main disadvantages of the known pump design are the increased dimensions caused by the use of electromagnetic coils and the need for a high residual metal level for starting and operation.

[0011] The need to develop universal electromagnetic pumps that will ensure pumping of liquid metals or salt solutions at low liquid levels is a pressing issue.

[0012] Technical solutions are known (in particular, application WO2022138199A1 (published on June 30, 2022, IPC: F27D 27 / 00, H02K 44 / 06) and patent US 11717884 B2 (published on August 8, 2023, IPC: B22D 17 / 30, B22D 35 / 00, H02K 44 / 06)), in which the magnetic system is located inside the device, with a channel for liquid inlet located at the bottom. The magnetic system provides suction of molten metal, which allows the use of such systems at a sufficiently low liquid level.

[0013] The common features of the known and claimed pumps are the location of the magnetic system inside the device and the provision of the ability to suck metal into the channel for the movement of liquid metal or salt solution.

[0014] However, the lack of a guide channel and the location of the magnetic system prevents the effective lifting of the liquid metal to the outlet.

[0015] The closest analogue (prototype) is a screw induction pump (patent RU141500, published 10.06.2014, IPC: H02K 44 / 06, H02K 1 / 22), including a spiral channel for pumped electrically conductive medium, formed inside two coaxially located cylinders, means for creating a magnetic field and an internal core, characterized in that the means for creating a magnetic field are placed in a glass and are installed with the possibility of rotation by means of an electromechanical drive relative to the spiral channel and the internal core and are made in the form of blocks of permanent magnets arranged around a circle, enclosed in a shell made of soft magnetic material and separated from each other by gaskets made of non-magnetic material, each of which has a central segment magnetized radially, and two side segments magnetized at an angle with respect to the central one, and the central segments are placed with alternation of poles around the circumference.

[0016] Common features of the known and claimed pumps are the presence of a spiral channel for the pumped medium, formed inside two coaxially located cylinders, and means for creating a magnetic field, made with the possibility of rotation.

[0017] However, the known design has two key limitations: large dimensions due to the external location of the magnetic system and the requirement for a high starting level of the residual liquid column.

[0018] The objective of the present invention was to develop a design for an electromagnetic pump for pumping liquid metals and / or molten salts at a low level of residual liquid column while ensuring a reduction in the overall dimensions of the pump itself and maintaining or increasing the efficiency of the pump.

[0019] The technical result of the invention is the possibility of pumping liquid metals and salt solutions while ensuring a residual liquid level of no more than 50 mm, measured from the center of the inlet section of the pump pipe, while simultaneously reducing the overall characteristics of the pump and maintaining or increasing the efficiency of the pump.

[0020] The technical result is provided for an electromagnetic pump, which includes a vertically oriented rotor, a motor operatively connected to the rotor, which is a shaft with permanent magnets of alternating polarity arranged along the diameter, and a helical channel for liquid metal formed inside two coaxially arranged cylinders made in the form of a cylindrical body with a bottom, wherein the outer cylinder has an inlet for liquid metal on the opposite side from the motor location and an outlet pipe for liquid metal located on the same side as the motor, connected to the helical channel, and a stator located outside the outer cylinder and made of a soft magnetic metal, wherein the shaft is placed inside the inner cylinder with the creation of an air gap and is configured to rotate inside the inner cylinder, the magnetization of the magnets is radial.

[0021] The technical result is achieved through a pump design in which the motor rotates the shaft with magnets (the rotor), the magnetic flux of the inductor is closed in the outer magnetic-conducting tube (the passive stator), and the rotating magnetic field induces eddy currents. When these currents interact with the magnetic field, an electromagnetic force is created, causing the metal to move at a linear velocity in the direction of the rotating field.

[0022] The working fluid is drawn along with the rotating magnetic field, the direction of movement of the working fluid being determined by the spiral channel. This ensures that the liquid metal or molten salt rises up the spiral channel to the outlet.

[0023] The technical result is achieved through a pump design that guarantees a minimum residual liquid alloy level in the sump. Specifically, the pump's vertical configuration ensures optimal suction and compactness. The screw-type flow channel prevents axial movement of the liquid by swirling the reverse flow. A permanent magnet inductor generates a working magnetic flux both in the active section of the screw channel and in the "capture" zone of the working solution (liquid metal or salt solution).

[0024] The design of the inlet pipe with minimal local resistance is aimed at preventing cavitation phenomena and ensuring the stability of the pump's suction capacity.

[0025] The inlet located at the bottom of the outer cylinder ensures self-priming of the working channel, allowing the pump to start and operate at low residual liquid levels. Furthermore, the hollow inner cylinder with its shaft and magnets creates a magnetic field even at the lowest liquid level. The EMF induced in the metal generates a lifting force, causing the flow to move upward and drawing a new portion of liquid through the inlet into the spiral channel. This results in increased pumping efficiency and completeness, significantly reducing the amount of residual liquid.

[0026] The location of the shaft with permanent magnets (rotor) along the entire length of the spiral channel ensures the efficiency of the pump while simultaneously reducing the overall dimensions compared to known technical solutions.

[0027] Contactless current induction in liquid metal ensures high operational reliability and cleanliness of the liquid metal pumping process, safe working conditions and compliance with safety regulations.

[0028] The spiral channel can be single-, double-, or triple-flow. Double-flow is preferred. A double-flow helical structure (or two parallel channels) is optimal and allows for a reduction in fluid flow rate in each individual channel while maintaining the overall flow rate. This, in turn, reduces local pressure drops and decreases the likelihood of cavitation compared to a single-flow helical structure.

[0029] Using a three-way screw structure is not optimal, as it leads to an increase in the level of the residual liquid column in the sump where the pump is installed by the time the pumping starts.

[0030] The shaft can be a cylindrical magnetically conductive sleeve (magnetic yoke) with permanent magnets placed on it with alternating polarity along the diameter.

[0031] Magnets can be arranged in sectors. Four magnet sectors are preferred; this number of sectors ensures sufficient device efficiency while further simplifying the design. Magnets can also be arranged in rows, depending on manufacturing capabilities.

[0032] Samarium-cobalt (SmCo) rare earth permanent magnets can be used as permanent magnets. These permanent magnets have high saturation induction and coercivity. Other rare earth permanent magnets with high saturation induction and coercivity can also be used.

[0033] Description of figures.

[0034] Figure 1 shows a general diagram of the device, where 1 is a shaft with permanent magnets of alternating polarity placed along the diameter (rotor), 2 is a screw channel, 3 is a stator, 4 is an outlet pipe.

[0035] Figure 2 shows a diagram of the pump from above.

[0036] Figure 3 shows a diagram of a two-pass channel, where 5 is the first pass, 6 is the second pass.

[0037] Figure 4 shows a diagram of a shaft with permanent magnets, where 7 are permanent magnets, 8 is a shaft.

[0038] An electromagnetic pump for pumping liquid metal and molten salts, which includes a vertically oriented motor (not shown in the figures), operatively connected to a rotor (1). The rotor is a shaft (8) with permanent magnets of alternating polarity (7) arranged along the diameter. The pump includes a screw channel (2) formed inside two coaxially located cylinders made in the form of a cylindrical body with a bottom. In this case, the outer cylinder (3) has an inlet for the liquid metal on the side opposite from the motor and an outlet pipe (4) for the liquid metal, located on the same side as the motor, connected to the spiral channel, and a stator located outside the outer cylinder and made of a soft magnetic metal. In this case, the shaft is placed inside the inner cylinder with the creation of an air gap and is configured to rotate inside the inner cylinder, the magnetization of the magnets is radial.

[0039] Below is an example of a particular implementation of an electromagnetic pump, which illustrates, but does not limit the invention.

[0040] The electromagnetic pump is placed vertically in liquid metal. The pump includes a pipeline consisting of two coaxial cylinders made of austenitic steel with a helical (spiral) channel located inside. Inner cylinder: inner diameter 86 mm, thickness 2 mm. Outer cylinder: inner diameter 105 mm, thickness 2 mm. The spiral channel inside the coaxial cylinders is the pipeline auger: a two-way spiral (5 - first run, 6 - second run), 6 full turns, pitch 52 mm, stroke 104 mm.

[0041] Rotor - shaft with permanent magnets. The rotor consists of a cylindrical magnetically conductive sleeve (magnetic yoke) with permanent magnets of alternating polarity across its diameter. The magnets are arranged in 4 sectors in 6 rows (6 rows is only due to the technological capabilities of magnet manufacturers). The magnets are radially magnetized. Within the existing dimensions, the optimal number of rotor pole pairs was selected (equal to p = 2 (2p = 4) based on the criterion of maximizing the working magnetic flux in the air gap), ensuring maximum electromagnetic power of the pump within the specified dimensions. The rotor is located inside the internal coaxial cylinder of the pipeline and is functionally connected to the motor.

[0042] The stator is located outside the outer coaxial cylinder of the pipeline. The stator is made of soft magnetic iron.

[0043] When the pump is operating, the motor rotates the shaft with permanent magnets (the rotor). The magnetic flux is closed in the outer magnetic flux tube (the passive stator). The rotating magnetic field induces eddy currents. This creates an EMF, which causes the liquid metal to move at a linear velocity in the direction of the rotating field. The direction of the working fluid is determined by a helical channel. This, in turn, ensures the liquid metal rises toward the outlet.

[0044] The minimum level of the residual liquid column (50 mm in the pump design) is determined based on the condition of creating a static pressure exceeding the saturated vapor pressure to completely eliminate cavitation.

[0045] The electromagnetic pump must provide a capacity of at least 1 m³ / h at a pressure of 2 atm. and a power consumption of no more than 850 W.

[0046] The technical result is achieved due to the pump design - vertical layout, rotor and stator arrangement, which ensures the working magnetic flux both in the active working zone (along the screw channel) and in the lower part of the pump - the zone of "capture" of liquid sodium or molten salts.

[0047] Thus, the proposed solution allows for a significant reduction in pump dimensions, an increase in its efficiency, and stable operation at a minimum liquid level.

Claims

1. An electromagnetic pump for pumping liquid metal and molten salts, which includes a vertically oriented rotor, a motor operatively connected to the rotor, which is a shaft with permanent magnets of alternating polarity arranged along the diameter, and a screw channel formed inside two coaxially arranged cylinders made in the form of a cylindrical body with a bottom, wherein the outer cylinder has an inlet for liquid metal on the opposite side from the motor location and an outlet pipe for liquid metal located on the same side as the motor, connected to the spiral channel, and a stator located outside the outer cylinder and made of a soft magnetic metal, wherein the shaft is placed inside the inner cylinder with the creation of an air gap and is configured to rotate inside the inner cylinder, the magnetization of the magnets is radial.

2. An electromagnetic pump for pumping liquid metal and molten salts according to paragraph 1, which includes a two-way screw channel.

3. An electromagnetic pump for pumping liquid metal and molten salts according to paragraph 1, which includes a shaft with permanent magnets of alternating polarity arranged in sectors along the diameter.

4. An electromagnetic pump for pumping liquid metal and molten salts according to paragraph 1, which includes a shaft with permanent magnets of alternating polarity arranged in rows along the diameter.

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