An internal sealed cooling stirring paddle device for molten iron pretreatment in a steel plant

Abstract

An internal sealed cooling stirring paddle device for molten iron pretreatment in a steel plant belongs to the technical field of molten iron pretreatment in steelmaking. The present invention mainly solves the problem of internal cooling of the stirring paddle. The device designs the core cooling circuit of the stirring paddle 8 and the stirring paddle shaft 9 into a one-way flow cooling circuit. The installation and disassembly of the stirring paddle 8 and the forced convection cooling circuit of the core of the stirring paddle shaft 9 are convenient and simple to construct and automatically recover synchronously. It also solves the risk of the fin inner tube 1 19 falling off caused by the end-face extrusion sealing connection of the fin inner tube 12 and the fin inner tube 2 18. The forced convection cooling of the core of the stirring paddle shaft 9 under working conditions by adjusting the pressure and flow of the cooling medium controls the temperature rise of the stirring paddle shaft 9 within a reasonable range, ensuring that the stirring paddle shaft 9 has good comprehensive mechanical properties. During the one-way flow of the cooling medium in the cooling circuit, the flow is sealed throughout the entire process, which creates conditions for the recycling of the cooling medium, saves power energy, and protects the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of molten iron pretreatment in steelmaking, and in particular to an internal sealed cooling stirring paddle device for molten iron pretreatment in a steel plant. A cooling medium is introduced into a cylindrical annular gap on the core of the stirring paddle shaft for unidirectional flow and forced convection cooling, thereby achieving overall cooling and lowering of the stirring paddle rotating in the high-temperature molten iron. Since the cooling circuit has good sealing performance, the cooling medium can be recycled, thereby saving power and energy and protecting the environment. Background Art

[0002] Hot metal pretreatment refers to the desulfurization, desiliconization, and dephosphorization process performed before the hot metal is added to the steelmaking furnace. The mechanical agitation desulfurization method (KR method) involves inserting a refractory-lined agitator into the hot metal ladle. The agitator rotates and stirs the hot metal, creating a vortex. A weighed desulfurizer is then added to the hot metal's surface via a telescopic chute and drawn into the vortex, where it mixes and reacts with the hot metal, achieving the desired desulfurization effect. This desulfurization method significantly improves the desulfurization kinetics and offers high desulfurization efficiency, relatively stable desulfurization results, low desulfurizer consumption, short operation time, high metal yield, and low refractory consumption. Currently, the KR mechanical agitation method is the primary method for hot metal pretreatment, providing high-quality, low-sulfur hot metal for clean steel production systems. It features efficient process equipment configuration, a stable desulfurization process, and a compact process layout. KR mechanical agitation desulfurization technology has become an important component of establishing a high-efficiency, low-cost clean steel production process platform. It plays a significant role in providing high-quality, low-sulfur molten iron, reducing converter smelting workloads, and reducing converter consumption indicators. The temperature of the agitator paddle rotating in high-temperature molten iron rises significantly. Forced convection cooling through the cylindrical annular gap within the agitator shaft, forming a one-way cooling circuit, is the most effective method for cooling the entire agitator shaft to the desired temperature and achieving good mechanical properties. Summary of the Invention

[0003] The purpose of the present invention is to provide an internal sealed cooling stirring paddle device for molten iron pretreatment in a steel plant, which is used in the mechanical stirring KR method molten iron desulfurization process in the steel plant. The core annular seam of the stirring paddle shaft 9 of the stirring paddle 8 inserted into the molten iron tank at a certain depth below the liquid surface of the molten iron with a temperature of about 1290℃ to 1340℃ and rotating and stirring is cooled by forced flow of cooling medium, thereby effectively preventing the temperature of the stirring paddle shaft 9 from excessively rising, so that the stirring paddle 8 has good comprehensive mechanical properties. This invention belongs to the technical field of molten iron pretreatment in steelmaking.

[0004] The present invention includes: a rotating shaft 1, a rotating joint 2, an upper bearing 3, a lower bearing 4, a flange 5, a connecting key 6, a stirring paddle connecting device 7, a stirring paddle 8, a stirring paddle shaft 9, a refractory material 10, a stirring head 11, a fin inner tube 12, a screw 13, a flange 14, an O-type sealing ring 15, an O-type sealing ring 2 16, an O-type sealing ring 3 17, a fin inner tube 2 18, a fin of the fin inner tube 1 19, a lower part of the fin inner tube 20, a lower end surface 21 of the rotating shaft, an upper end surface 22 of the stirring shaft, an upper part 23 of the fin inner tube 2, and a fin 24 of the fin inner tube 2.

[0005] A blind hole is formed in the center of the rotating shaft 1, into which the finned inner tube 12 is inserted, and screws 13 and flange 14 are used to secure the finned inner tube 19. A cooling medium enters the inner tube 12, and the inner cylindrical surface of the blind hole of the rotating shaft 1 and the outer cylindrical surface of the finned inner tube 12 form an annular gap space for the cooling medium to reflux. The rotating shaft 1 is connected to the flange 5 via a connecting key 6. The stirring paddle 8 is composed of a stirring paddle shaft 9, a refractory material 10, and a stirring head 11. A blind hole is formed in the center of the stirring paddle shaft 9, into which the finned inner tube 18 is inserted, positioned circumferentially by gravity, within the finned inner tube 24. When the stirring paddle 8 is in operation, it has a certain amount of vertical upward movement. A cooling medium enters the inner tube 18, and the inner cylindrical surface of the blind hole of the stirring paddle shaft 9 and the outer cylindrical surface of the finned inner tube 18 form an annular gap space for the cooling medium to reflux, thereby achieving forced convection cooling of the core cylindrical surface of the stirring paddle shaft 9. The stirring paddle 8 is connected to the flange 5 via the stirring paddle connection device 7. A 1mm gap is maintained between the flange 5, the lower end face 21 of the rotating shaft, and the upper end face 22 of the stirring shaft for structural connection and disassembly. The rotary joint 2 is circumferentially fixed, providing both the introduction and return of the cooling medium. The outer rings of the upper and lower bearings 3 and 4 are circumferentially fixed, while the inner rings are interference-fitted with the rotating shaft 1. The rotating shaft 1 receives the rotational motion and dynamic torque to enable the stirring head 11 to stir.

[0006] The advantages of the present invention are that the core cooling circuit of the stirring paddle shaft 9 of the stirring paddle 8 is designed as a unidirectional flow cooling circuit, the installation and disassembly of the stirring paddle 8, the forced convection cooling circuit of the core of the stirring paddle shaft 9 are convenient and simple to construct and automatically recover synchronously, and the risk of the fin inner tube 1 19 falling off caused by the end-face extrusion sealing connection of the fin inner tube 12 and the fin inner tube 2 18 is solved; the forced cooling of the core of the stirring paddle shaft 9 by adjusting the pressure and flow of the cooling medium allows the temperature rise of the stirring paddle shaft 9 under working conditions to be controlled within a reasonable range, ensuring that the stirring paddle shaft 9 has good comprehensive mechanical properties. During the unidirectional flow of the cooling medium in the cooling circuit, the flow is sealed throughout the entire process, creating conditions for the recycling of the cooling medium, saving power energy, and protecting the environment.

[0007] The KR method of mechanical stirring desulfurization is to insert the stirring head 11 of a stirring paddle 8 with a stirring paddle shaft 9 lined with refractory material 10 and an inner finned tube 18 into a certain depth below the liquid surface of the molten iron tank, and then rotate the stirring paddle 8. When a "V"-shaped vortex is formed on the liquid surface of the molten iron, the added desulfurizer is drawn into the interior of the molten iron for sufficient mixing and reaction, thereby achieving the purpose of desulfurization. The stirring head 11 of the stirring paddle 8 rotates for about 15 minutes each time in the high-temperature molten iron at about 1290℃~1340℃. The stirring paddle shaft 9 is responsible for transmitting power torque and rotational motion. Under the high-temperature temperature field, due to contact heat transfer, material heat conduction and heat radiation, the temperature rise of the entire stirring paddle 8 is relatively obvious, which seriously affects the comprehensive mechanical properties of the stirring paddle shaft 9. The selection of refractory lining 10 with good heat resistance is a necessary method to protect the stirring paddle shaft 9 from excessive temperature rise. The cooling medium is introduced into the inner tube 18 of the fin to force convection cooling of the inner cylindrical surface of the stirring paddle shaft 9 to form a one-way cooling circuit, which is the most effective method to cool the stirring paddle shaft 9, reach the required temperature and obtain good mechanical properties. At the same time, the refractory material 10 lining the stirring paddle 8 will be severely peeled off and consumed due to the erosion of high-temperature molten iron during operation, and the entire stirring paddle 8 needs to be disassembled and repaired; coupled with the large amount of dust on the working surface and other working environment, it is indispensable to provide sealing protection for the forced convection cooling circuit inside the stirring paddle shaft 9; after the stirring paddle 8 is reinstalled, the forced convection cooling circuit of the stirring paddle shaft 9 can be easily and synchronously restored automatically.

[0008] The cooling medium is introduced into the cooling circuit and sealed internally. The seal after the connection between the fin inner tube 12 and the fin inner tube 2 18 uses a cylindrical piston O-ring extrusion seal. The two pieces are easy to connect and disassemble, eliminating the risk of the fin inner tube 1 fin 19 falling off due to the two-piece extrusion seal. The O-ring 3 17 seal between the outer cylindrical surface of the lower part 20 of the fin inner tube and the inner cylindrical surface of the upper part 23 of the fin inner tube 2 has a good sealing effect due to the small pressure difference on the sealing surface, and there will be no crossflow during the unidirectional flow of the cooling medium. Due to the structural connection and disassembly requirements, a 1mm gap is left between the lower end face 21 of the rotating shaft and the upper end face 22 of the stirring shaft. The external secret uses an end seal plus an extrusion seal, which is called an end face axial O-ring extrusion seal. The O-ring 2 16 forms the first external seal, and the O-ring 1 15 forms the second external seal, which also serves as a dustproof function. The establishment of the two seals has a good sealing effect, ensuring that the cooling medium will not leak or be contaminated during the reflux cooling process, creating conditions for the recycling of the cooling medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a structural diagram of an internal sealed cooling stirring paddle device for molten iron pretreatment in a steel plant. Figure 2 A partially enlarged view of an internal sealed cooling stirring paddle device for molten iron pretreatment in a steel plant, where the arrows indicate the direction of cooling medium flow. DETAILED DESCRIPTION

[0010] The present invention includes: a rotating shaft 1, a rotating joint 2, an upper bearing 3, a lower bearing 4, a flange 5, a connecting key 6, a stirring paddle connecting device 7, a stirring paddle 8, a stirring paddle shaft 9, a refractory material 10, a stirring head 11, a fin inner tube 12, a screw 13, a flange 14, an O-type sealing ring 15, an O-type sealing ring 2 16, an O-type sealing ring 3 17, a fin inner tube 2 18, a fin of the fin inner tube 1 19, a lower part of the fin inner tube 20, a lower end surface 21 of the rotating shaft, an upper end surface 22 of the stirring shaft, an upper part 23 of the fin inner tube 2, and a fin 24 of the fin inner tube 2.

[0011] The specific implementation of the present invention will be described in detail below with reference to the accompanying drawings.

[0012] See also Figure 1 、 Figure 2 A 1mm gap is required between the lower end surface 21 of the rotating shaft and the upper end surface 22 of the stirring shaft due to structural connection and disassembly. When inspecting the stirring paddle 8, the stirring paddle connector 7 is disassembled, the stirring paddle 8 is removed, and the O-ring 15, O-ring 2, and O-ring 3 17 that need to be replaced are replaced. To reinstall the stirring paddle 8, the lower portion 20 of the finned inner tube is inserted into the upper portion 23 of the finned inner tube 2, restoring the connection function of the stirring paddle connector 7. This facilitates the simple, synchronous, and automatic restoration of the forced convection cooling circuit of the stirring paddle shaft 9.

[0013] See also Figure 1 、 Figure 2 When the agitator 8 rotates, the cooling medium is connected through the rotary joint 2 and enters the inner fin tube 12 and the inner fin tube 2 18 in sequence. During this period, it is sealed by the O-ring 3 17 and then flows back to the bottom of the agitator shaft 9 into the cylindrical annular gap space formed by the agitator shaft 9 and the inner fin tube 2 18. The cooling medium implements forced convection cooling on the core of the agitator shaft 9, effectively reducing the temperature rise of the agitator shaft 9 under working conditions. By adjusting the flow rate and pressure of the cooling medium, the required temperature of the agitator shaft 9 is obtained, so that the agitator 8 has good mechanical properties to meet working needs. The cooling medium continues to flow and enters the annular gap space formed by the rotating shaft 1 and the inner fin tube 12. During this period, it is sealed and protected from dust by the O-ring 15 and the O-ring 2 16, and is discharged through the rotary joint 2. During the unidirectional flow of the cooling medium, the flow is sealed throughout, creating conditions for the recycling of the cooling medium.

Claims

1. A sealed cooling stirring paddle device for molten iron pretreatment in a steel plant, characterized in that: The invention comprises a rotating shaft (1), a rotating joint (2), an upper bearing (3), a lower bearing (4), a flange (5), a connecting key (6), a stirring paddle connecting device (7), a stirring paddle (8), a fin inner tube 1 (12), a screw (13), a flange (14), an O-type sealing ring 1 (15), an O-type sealing ring 2 (16), an O-type sealing ring 3 (17), a fin inner tube 2 (18), a fin of the fin inner tube 1 (19), a lower portion of the fin inner tube (20), a lower end surface of the rotating shaft (21), an upper end surface of the stirring shaft (22), an upper portion of the fin inner tube 2 (23), and a fin of the fin inner tube 2 (24); A blind hole is opened in the center of the rotating shaft (1), and the fin inner tube (12) is installed therein, and is fixed by screws (13) and flanges (14) under the positioning of the fin inner tube (19); a cooling medium enters the fin inner tube (12); an annular gap space is formed between the inner cylindrical surface of the blind hole of the rotating shaft (1) and the outer cylindrical surface of the fin inner tube (12) to allow the cooling medium to reflux; the rotating shaft (1) is connected to the flange (5) through a connecting key (6); The stirring paddle (8) is composed of a stirring paddle shaft (9), a refractory material (10), and a stirring head (11); the stirring paddle shaft (9) is lined with a refractory material (10), a blind hole is opened in the center of the stirring paddle shaft (9), and the fin inner tube 2 (18) is positioned circumferentially in the fin inner tube 2 (24) by gravity, and the stirring paddle (8) has a certain amount of vertical upward movement under working conditions; the cooling medium enters the fin inner tube 2 (18); the inner cylindrical surface of the blind hole of the stirring paddle shaft (9) and the outer cylindrical surface of the fin inner tube 2 (18) form an annular gap space for the cooling medium to reflux; the stirring paddle (8) is connected to the flange (5) through the stirring paddle connecting device (7), and a certain gap is left between the flange (5) and the lower end face (21) of the rotating shaft and the upper end face (22) of the stirring shaft due to the need for structural connection and disassembly; the rotary joint (2) is fixed circumferentially to complete the introduction and reflux of the cooling medium; The seal after the fin inner tube 1 (12) and the fin inner tube 2 (18) are connected adopts a cylindrical piston type O-ring extrusion type seal; a sealing O-ring 3 (17) is installed between the outer cylindrical surface of the lower part (20) of the fin inner tube and the inner cylindrical surface of the upper part (23) of the fin inner tube 2; a certain gap is left between the lower end face (21) of the rotating shaft and the upper end face (22) of the stirring shaft due to the need for structural connection and disassembly, the O-ring 2 (16) forms the first external seal, and the O-ring 1 (15) forms the second external seal; The outer rings of the upper bearing (3) and the lower bearing (4) are fixed in the annular direction, and the inner rings are interference-connected with the rotating shaft (1). The rotating shaft (1) receives the rotating motion and the dynamic torque to realize the stirring work of the stirring head (11).

Images