STEEL FURNACE BURNER PROTECTION DEVICE

Abstract

This utility model relates to ferrous metallurgy and can be used in steel production in steelmaking furnaces. The burner protection device for a steelmaking furnace consists of a cooled tubular body made of concentrically mounted outer and inner tubes, with a tip, a mounting panel, and openings for the supply and discharge of coolant. A linear expansion compensator is installed between the upper and lower sections of the inner tube and coaxially with it. The technical result is increased durability. 2 ill.

Description

[0001] Technical field

[0002] The utility model relates to the field of ferrous metallurgy and can be used in the production of steel in steel-smelting furnaces.

[0003] Technology Level

[0004] During steel production, replaceable process equipment is used in steelmaking furnaces, specifically burners and other equipment used in steelmaking operations (e.g., tuyeres, thermocouples, etc.), installed within the furnace's working volume. Temperatures in the furnace reach 1500-1800°C, which is higher than the melting point of the structural steels from which this equipment is made. To protect the replaceable process equipment from such temperatures, protective cooling devices are used, which are installed within the furnace's working volume, and the equipment itself is then installed within these cooled devices.

[0005] A panel for water-cooled burners and / or injectors (patent RU 2634523 C2) (hereinafter referred to as the panel) is known. It consists of the following main elements: a main body, first and second cooling circuits, formed as round pipes, with sides: rear, front, top, right, left, and bottom. This panel has a clear drawback: the central areas of the left and right sides are located at a significant distance from the cooling channels. To ensure the required cooling of these central areas of the left and right sides, it is necessary to significantly increase the heat transfer coefficient from the cooling channels by increasing the speed of the cooling water, which leads to:

[0006] to the large temperature difference between the wall of the cooling channel and the central area of ​​the left and right sides;

[0007] increased hydraulic resistance due to the need to pump more cooling water in order to increase its flow rate.

[0008] A large temperature difference in the metal of the main body leads to a significant difference in thermal expansion in the metal of the main body, the occurrence of mechanical stress in the metal body, which, as experience in operating systems with such a defect shows, ultimately leads to cracking of the metal and depressurization of the cooling channels, causing the failure of the device.

[0009] Increased hydraulic resistance of cooling channels leads to unnecessary energy costs for pumping cooling water.

[0010] A device for intensifying melting in an electric arc furnace (patent RU 2601848) is known. Its main elements include a water-cooled copper body with longitudinal drillings and pipes forming cooling channels. A disadvantage of this device is the high cost of the final product due to the entire body being manufactured from copper, an expensive material, the technological complexity of deep drilling, and the need to manufacture the body from a single piece.

[0011] A caisson for mounting a replaceable process tool is known (patent RU 76846 U1, accepted as a prototype) (hereinafter referred to as the caisson), consisting of the following main elements: a tubular body made of two concentric pipes with a copper tip equipped with flow channels for cooling water. The copper tip is fixed to the tubular body (usually steel) by welding. In the intertube space, longitudinal dividing partitions are installed, forming flow channels for the coolant in it, communicating with the flow channels of the copper tip, in which these channels are designed as flow gaps between ribs made in the body of the copper tip, and the ribs are covered by a plate in the form of a lid fixed in the copper tip with a tight fit to the tops of these ribs. This caisson design has the following disadvantages:

[0012] Uneven cooling of the copper tip and the weld joint "copper head-steel tubular body." This is due to the fact that the channels in the copper tip, formed by the fins, have different lengths. The channels closest to the diameter are the longest, while the peripheral channels are the shortest. Different channel lengths result in different hydraulic resistance, resulting in different water flow through these channels: the greatest flow through the short channels, and the least through the long ones. Consequently, the cooling water flow becomes uneven. Uneven cooling water flow across the copper tip results in different cooling intensities, creating zones of ineffective cooling, which can lead to burnout of the copper tip.After passing the copper tip, an uneven water flow is applied to cool the weld, which also cools unevenly, leading to uneven thermal expansion. This, in turn, causes mechanical stress in the weld metal and cracking, leading to depressurization of the water cavity and failure of the caisson. Uneven cooling can also lead to burnout of the weld due to the presence of insufficiently cooled zones.

[0013] in addition, in this caisson, the cooling of the copper tip is organized by washing it with a stream of water directed parallel to the end surface, which is not the most effective method. In accordance with the theory of heat transfer ([1] - Mukhachev G.A., Shchukin V.K. Thermodynamics and heat transfer: Textbook for aviation universities - 3rd ed., revised - M: Higher school, 1991. - 480 p: ill. ISBN 5-06-001910-1, p. 291) when the wall is washed with liquid, a dynamic boundary layer is formed containing a laminar boundary layer (hereinafter referred to as LBL), or a turbulent boundary layer with a viscous sublayer. In the LBL, as in the viscous sublayer, heat is transferred mainly by thermal conductivity, and since liquids have low thermal conductivity, which creates high resistance to heat transfer ([1], Fig. 5.2).To increase heat transfer, it is necessary to reduce the thickness of the LPS or viscous sublayer by increasing the velocity component normal to the surface, ensuring convective heat transfer instead of conductive heat transfer ([1], p. 291, paragraph 2). Logically, the greatest increase in heat transfer is achieved when the entire flow velocity, and not just a portion of it, is directed normal to the washed surface; - the outer concentric pipe heats up significantly more than the inner one, which is located in the "cold" zone of the caisson. This leads to the fact that the linear expansion of the outer pipe is greater than that of the inner one. Elements compensating for this difference in linear expansion are absent in the design under consideration, which leads to destruction of the "copper tip-plate" weld and failure of the caisson.

[0014] The essence of the utility model

[0015] The objective of this utility model is to increase the durability of a device for protecting replaceable process equipment (hereinafter referred to as the protection device), in particular a burner. This problem is solved by compensating for the difference in the linear thermal expansion of its components.

[0016] The technical result for the protective device is to increase its durability by providing compensation for the difference in thermal linear expansion.

[0017] The technical result of the device is achieved through the design of a protective device consisting of a cooled tubular body made of concentrically installed outer and inner tubes, with a tip, mounting panel, and openings for the supply and discharge of coolant. A linear expansion compensator is installed between the upper and lower sections of the inner tube, coaxially with it.

[0018] Brief description of drawings

[0019] The details, features, and advantages of the utility model are evident from the following description of the implementation of the claimed technical solution, using figures showing examples of the protective device. Figure 1 shows a cross-sectional view of the protective device, and Figure 2 shows an example of a cross-sectional view of the protective device.

[0020] The following positions are indicated by numbers on the figures:

[0021] 1 - outer pipe, 2 - inner pipe, 3 - tip, 4 - cylindrical flange of the tip, 5 - end inner surface of the tip, 6 - lower part of the inner pipe, 7 - cover, 8 - balancing partition, 9 - holes of the balancing partition (hereinafter referred to as the holes), 10 - linear expansion compensator, 11 - front panel, 12 - side strips, 13 - mounting panel, 14 - discharge channels (left and right), 15 - coolant inlet fitting, 16 - coolant outlet pipe, 17 - axial cooling channel, 18 - inlet manifold, 19 - end cavity, 20 - cooled gap, 21 - connecting seam "tip-outer pipe" (hereinafter referred to as the connecting seam), 22 - outer pipe cover, 23 - inner pipe cover.

[0022] Disclosure of Utility Model

[0023] The protection device includes: an outer pipe (1), an inner pipe (2), a tip (3) with at least one opening having a cylindrical flange (4), an opening for supplying coolant, a linear expansion compensator (10), a mounting panel (13) with openings for draining coolant.

[0024] An outer pipe (1) is attached to the furnace surface at a vertical angle, for example, to the front panel (11) at its top through the outer pipe cover (22). A tip (3) with openings for accommodating replaceable process equipment, in particular a burner, is attached to the end of the outer pipe (1) using a known method (e.g., welding). The main elements of the protective device are made of a metal-containing material, such as copper, stainless steel, or other metals or alloys suitable for heat dissipation.

[0025] A linear expansion compensator (10) is attached between the lower and upper parts of the inner pipe (2), which is installed coaxially with the inner pipe (2).

[0026] The supply and discharge of coolant to the protection device can be carried out using any known solutions. For example, as in the technical solutions specified in the prior art, according to patent RU 2601848 or patent RU 76846U1. The supply and discharge of coolant can also be carried out using the following elements. A balancing partition (8) containing holes (9) is attached to the tip (3), at some distance from the end inner surface of the tip (5). The lower part of the inner pipe (6) is attached to the balancing partition (8) and coaxially with it, with its end surface opposite to that to which the linear expansion compensator (10) is attached. A cover (7) is attached at a distance from the balancing partition (8) with a gap to the holes (9). The cover (7), tip (3), balancing partition (8) and the lower part of the inner pipe (6) form an inlet manifold (18).The coolant supply hole is located in the cover (7), onto which the coolant supply nipple (15) is attached, which is connected to the inlet manifold (18) through the hole in the cover (7). In this case, the outer pipe (1), the cylindrical flange of the tip (4), the linear expansion compensator (10), the inner pipe (2) and, for example, the outer pipe cover (22), the inner pipe cover (23) and the cutout in the front panel (11) form an axial cooling channel (17). The balancing partition (8) and the tip (3) form an end cavity (19). The mounting panel (13), the inner pipe (2) and, for example, the side strips (12) and the front panel (11) form a cooled gap (20). The outlet channels (left and right) (14) are attached to the holes in the mounting panel (13), on the side opposite to the outer pipe (1). On the same side, the coolant drain pipe (16) is attached to the hole in the mounting panel (13).The coolant outlet pipe (16) and the outlet channels (14) are hydraulically connected to each other, and the outlet channels (14) are also hydraulically connected to the cooled gap (20).

[0027] The proposed technical solution provides compensation for the difference in the linear expansions of the outer pipe (1) and the inner pipe (2), thus removing the mechanical load from the elements connecting the outer pipe (1) and the inner pipe (2), for example, from the connecting seam “tip (3) - cover (7)”, from which the cyclic mechanical impact leading to its fatigue failure is removed, thus increasing the durability of the device.

[0028] Compensation for the difference in linear expansion of the outer pipe (1) and the inner pipe (2) in the protection device is carried out as follows: when the outer pipe (1) is heated, its length along its axis increases, this elongation is transmitted to the linear expansion compensator (8) through the tip (3) and the elements connecting the tip (3) and the lower part of the inner pipe (6).

[0029] Cooling of the protective device is carried out in a known manner or, for example, as follows: coolant (e.g., water) is supplied to the coolant inlet nipple (15), then the coolant enters the inlet manifold (18), where it is distributed throughout the cavity of this manifold and then directed into the openings (9). In the openings (9), coolant flows are formed at a certain speed and directed perpendicular to the end inner surface of the tip (5), most effectively cooling this surface and, accordingly, the tip (3) itself.The number of holes (9), the specific points of their installation, their shape and size, the gaps from them to the cover (7) and to the end inner surface of the tip (5), and, in the case of using jet tubes, their length are selected by computer modeling of the hydraulic flow of the coolant in specialized software to ensure an equal flow of coolant through these holes (9), as well as a uniform flow of liquid in the axial cooling channel (17). Next, the coolant, having passed the end cavity (19), having cooled the tip (3), is directed into the axial cooling channel (17). At the initial section of this axial cooling channel (17), the coolant evenly washes and, accordingly, uniformly cools the connecting seam (21).After passing through the axial cooling channel (17), the coolant enters the cooled gap (20), where it is divided into 2 directions: 1 - into the upper left and right parts of this gap, 2 - into the lower part of this gap. Passing in these two directions, the coolant cools the mounting panel (13), the front panel (11), and the side strips (12). From the first direction, the coolant is supplied to the outlet channels (left and right) (14). From the second direction, the coolant is supplied to the coolant outlet pipe (16), where it combines with the coolant from the outlet channels (left and right) (14) and is then discharged from the device.

Claims

A device for protecting a burner of a steel-smelting furnace, consisting of a cooled tubular body made of concentrically installed outer and inner tubes, with a tip, a mounting panel and openings for the supply and discharge of cooling liquid, characterized in that a linear expansion compensator is installed between the upper and lower parts of the inner tube and coaxially with it.

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