A dual-flow oxygen top lance for RH refining furnace

Abstract

The present invention discloses a dual-flow oxygen top lance for an RH refining furnace, which relates to the field of top lances for RH refining furnaces. It includes a lance head and a lance body. The lance head is installed at the front end of the lance body. The lance body comprises an outer layer pipe, a middle layer pipe, an inner layer pipe and an oxygen pipe. An oxygen cavity is formed inside the oxygen pipe. An annular oxygen cavity is formed between the middle layer pipe and a baffle, and the annular oxygen cavity is communicated with an annular oxygen pipe. A nozzle is arranged in the middle of the lance head, and the nozzle is connected to a main oxygen pipe. A gas injection hole is formed on the side of the nozzle and is communicated with a gas cavity. An annular oxygen spray head is annularly arranged on the lance head outside the nozzle, and the annular oxygen spray head is communicated with the annular oxygen cavity. In the present invention, an additional controllable annular oxygen is added. When baking, epoxy is used to increase the flame length, reduce noise, and dual-flow oxygen can also be used simultaneously to achieve the effects of full combustion and oxygen-enriched baking. At the same time, during vacuum smelting, using epoxy for temperature rise will reduce the impact of oxygen on the molten steel in the furnace.

Description

Technical Field

[0001] The present invention relates to the technical field of the top lance of the RH refining furnace, and specifically relates to a double-flow oxygen top lance for the RH refining furnace. Background Art

[0002] The RH molten steel vacuum circulation refining equipment can refine almost all difficult-to-refine steel grades, including ultra-pure steel, ultra-pure ultra-low carbon steel, and ultra-pure low-carbon stainless steel. The molten steel is provided by an electric furnace (or a converter), and after refining, high-quality molten steel with good continuous casting performance that meets the requirements of composition and temperature is provided for continuous casting. It is an important central link connecting the upstream and downstream in the advanced metallurgical process of "large steel enterprises", "converter-refining-continuous casting" in modern times, and also an important link for optimizing the steelmaking process flow.

[0003] The double-flow oxygen top lance of the RH refining furnace is improved from the multi-functional top lance of the RH refining furnace. After long-term use, dents will form inside the lance tip of the original multi-functional top lance, and gas backflow is likely to occur after the gas flows out, resulting in steel slag adhesion and lance tip blockage. Summary of the Invention

[0004] In order to solve the problems that dents will form inside the lance tip after the existing top lance is used, and gas backflow is likely to occur after the gas flows out, resulting in steel slag adhesion and lance tip blockage, the present invention provides a double-flow oxygen top lance for the RH refining furnace.

[0005] To achieve the above object, a double-flow oxygen top lance for the RH refining furnace is provided, which includes a lance tip and a lance body. The lance tip is installed at the front end of the lance body. The lance body includes an outer layer pipe, a middle layer pipe, an inner layer pipe, and an oxygen pipe. An oxygen cavity is formed inside the oxygen pipe, and the oxygen cavity is communicated with the main oxygen pipe. A gas cavity is formed between the oxygen pipe and the inner layer pipe, and the gas cavity is communicated with the gas pipe. An annular oxygen cavity is formed between the middle layer pipe and a baffle, and the annular oxygen cavity is communicated with the annular oxygen pipe. An outer cooling water cavity and an inner cooling water cavity are formed between the middle layer pipe and the outer layer pipe, and the outer cooling water cavity and the inner cooling water cavity are separated by a baffle. The lower part of the outer cooling water cavity is connected to a cooling water inlet pipe, and the lower part of the inner cooling water cavity is connected to a cooling water outlet pipe. A nozzle is provided in the middle of the lance tip, and the nozzle is connected to the main oxygen pipe. Gas injection holes are opened on the side of the nozzle, and the gas injection holes are communicated with the gas cavity. Annular oxygen nozzles are annularly opened on the lance tip outside the nozzle, and the annular oxygen nozzles are communicated with the annular oxygen cavity.

[0006] Further, the nozzle is a Laval nozzle, and a sealing gasket is provided at the connection between the rear end of the nozzle and the port of the oxygen cavity.

[0007] Further, a first sealing plate is provided at the connection between the front end of the inner layer pipe and the lance tip, and the front end of the first sealing plate is welded to the lance tip, and a sealing gasket is provided at the connection between the rear end of the first sealing plate and the inner layer pipe.

[0008] Further, a second sealing plate is provided at the connection between the front end of the middle layer pipe and the gun head, and the front end of the second sealing plate is welded to the gun head, and a sealing gasket is provided at the connection between the rear end of the second sealing plate and the middle layer pipe.

[0009] Further, the degree of the expansion angle of the nozzle is 16°.

[0010] Further, the annular oxygen nozzle provided on the gun head is a circular hole annular setting, and the number of circular holes of the annular oxygen nozzle is not less than eight.

[0011] Further, the annular oxygen nozzle provided on the gun head is an annular groove, and the annular oxygen nozzle of the annular groove divides the gun head into two parts.

[0012] Further, the oxygen pressure inside the main oxygen pipe is 1.0 - 1.6 Mpa, and the oxygen flow rate is 4500 Nm 3 / h.

[0013] Further, the gas input inside the fuel gas pipe is one of fuel gas or natural gas.

[0014] Further, the annular oxygen flow rate provided inside the annular oxygen pipe is 700 Nm 3 / h.

[0015] Further, the cooling water pressure formed inside the outer cooling water chamber and the inner cooling water chamber is 0.6 - 0.8 Mpa, and the cooling water flow rate is 90 m 3 / h.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] By means of the Laval nozzle, the speed of oxygen ejection is increased, and at the same time, the backflow caused by oxygen hitting the steel slag surface when ejecting along the inner wall of the oxygen port of the gun head is avoided, and the injection angle of the fuel gas in the expansion section is increased, so that the fuel gas can be closer to the end face of the gun head. When injecting, it can take away part of the heat of the gun head, and at the same time, it can be more fully mixed with oxygen. At the same time, an additional controllable annular oxygen is added. Epoxy is used during baking to increase the flame length, reduce noise, and double-flow oxygen can also be used at the same time to achieve the effect of full combustion and oxygen-enriched baking. At the same time, during vacuum smelting, using epoxy for heating will reduce the impact of oxygen on the molten steel in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 is a schematic diagram of the gun head installation of the present invention;

[0020] Figure 3 is a schematic diagram of the gun head of the present invention.

[0021] In the figure: 1, the gun head; 11, the annular oxygen spray head; 12, the gas injection holes; 13, the nozzle; 2, the gun body; 21, the outer layer pipe; 22, the middle layer pipe; 23, the baffle; 24, the inner layer pipe; 25, the oxygen pipe; 3, the outer cooling water cavity; 31, the cooling water inlet pipe; 4, the inner cooling water cavity; 41, the cooling water outlet pipe; 5, the annular oxygen cavity; 51, the annular oxygen pipe; 6, the gas cavity; 61, the gas pipe; 7, the oxygen cavity; 71, the main oxygen pipe; 8, the first sealing plate; 9, the second sealing plate. Specific implementation mode

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Embodiment 1

[0024] Specific implementation mode 1: As Figure 1As shown in Fig. —3, a double-flow oxygen top lance for an RH refining furnace includes a lance head 1 and a lance body 2. The lance head 1 is installed at the front end of the lance body 2. The lance body 2 includes an outer layer pipe 21, a middle layer pipe 22, an inner layer pipe 24, and an oxygen pipe 25. An oxygen cavity 7 is formed inside the oxygen pipe 25, and the oxygen cavity 7 is communicated with a main oxygen pipe 71. The oxygen inside the main oxygen pipe 71 is used for decarburization and combustion support. A gas cavity 6 is formed between the oxygen pipe 25 and the inner layer pipe 24, and the gas cavity 6 is communicated with a gas pipe 61. The gas inside the gas pipe 61 is used for combustion and temperature increase. An annular oxygen cavity 5 is formed between the middle layer pipe 22 and a baffle 23, and the annular oxygen cavity 5 is communicated with an annular oxygen pipe 51. The oxygen inside the annular oxygen pipe 51 is used for oxygen-enriched baking to reduce impact. Moreover, the annular oxygen enclosure formed on the outside can reduce noise generation and enable full combustion, avoiding gas leakage. With the gas power remaining unchanged and the oxygen-fuel ratio increased, the output gas flow rate remains unchanged while the corresponding output oxygen flow rate increases, and the generated CO amount decreases. An outer cooling water cavity 3 and an inner cooling water cavity 4 are formed between the middle layer pipe 22 and the outer layer pipe 21, and the outer cooling water cavity 3 and the inner cooling water cavity 4 are separated by the baffle 23. A cooling water inlet pipe 31 is connected below the outer cooling water cavity 3, and a cooling water outlet pipe 41 is connected below the inner cooling water cavity 4. The outer cooling water cavity 3 and the inner cooling water cavity 4 are communicated, and the water body flows inside to achieve the cooling effect of the top lance. A nozzle 13 is provided in the middle of the lance head 1, and the nozzle 13 is connected to the main oxygen pipe 71. A gas injection hole 12 is opened at the front end of the side surface of the nozzle 13, forming a mixed combustion area with an external mixing structure at the end of the top lance head body. In this way, even if a larger amount of gas needs to be input due to the use of low-calorific-value self-produced coke oven gas, no great noise will be generated. At the same time, the gas channel and the oxygen channel are independent of each other. The nozzle adopts a Laval nozzle to reduce the influence of pressure difference and avoid the restrictive effect of oxygen on gas during transportation, thereby ensuring that the gas flow rate reaches the set value, providing sufficient heat for steelmaking, shortening the heating time and slag melting time. Multiple groups of gas injection holes 12 are evenly opened, and the gas ejected from the inside of the gas injection holes 12 forms a swirl, and the gas injection holes 12 are communicated with the gas cavity 6. An annular oxygen nozzle 11 is annularly opened on the lance head 1 outside the nozzle 13, and the annular oxygen nozzle 11 is communicated with the annular oxygen cavity 5. The high-pressure swirl air flow can obtain a supersonic air flow after passing through the Laval nozzle, which is beneficial to shortening the process time; the distance between the lance head and the molten pool can be increased, and the annular oxygen blown out on the outside suppresses the splashing of the molten pool, reducing the sticking of the top lance to the steel and improving the service life of the top lance; the impact force of the air flow on the liquid per unit area is smaller than that of a straight tube type, which can reduce splashing and improve the metal shrinkage rate; the processing and manufacturing are more difficult than that of a straight tube type.

[0025] Use and first perform pretreatment

[0026] All components in contact with the oxygen lance must not have oil stains. Otherwise, degreasing treatment must be carried out. The oxygen elbow must be degreased;

[0027] The oxygen pipes, inner pipes, middle pipes and outer pipes of the top lance are welded in sections. Gas shielded arc welding is used for the sections, and E4303 electrodes are used for continuous welding for the rest. Unless otherwise specified, the weld height shall not be less than the thickness of the thinner welded part, and the welds shall not have defects such as pores, sand holes, inclusions, residual stress, etc.;

[0028] After the top lance is installed, conduct a 2-hour bending test. Lift the oxygen blowing pipe so that its lower end touches the ground and its center line forms a 30° angle with the ground. After the bending test, if the welds are not damaged and the connectors are not loose, then it can be pressure tested;

[0029] The entire top lance shall be subjected to a pressure test. The part in contact with oxygen shall maintain a pressure of 1.8 MPA, and the part in contact with cooling water shall maintain a pressure of 1.5 MPA. After gently tapping the weld part with a small hammer for 30 minutes, if there is no leakage at the joints, seals and welds and the pressure drop is not greater than 0.1 MPA, then it can be used;

[0030] After the pressure test is qualified, blow dry the water in the inlet and outlet water pipes with nitrogen;

[0031] During the loading, unloading and transportation of the top lance, collision and bending deformation of the lance body are strictly prohibited. The nozzle shall be wrapped with cloth and then with linen. After the overall installation, all the air inlets, inlet and outlet water pipes shall be wrapped to prevent foreign matters from entering the pipes;

[0032] After completion, paint the surface with aluminum powder paint.

[0033] The oxygen pressure inside the main oxygen pipe 71 is 1.0 - 1.6 Mpa, and the oxygen flow rate is 4500 Nm 3 / h.

[0034] The gas input into the gas pipe 61 is one of gas or natural gas; among them, the natural gas flow rate is 350 Nm3 / h; the coke oven gas flow rate is 700 Nm3 / h.

[0035] The annular oxygen flow rate set inside the annular oxygen pipe 51 is 700 Nm 3 / h.

[0036] The cooling water pressure formed inside the outer cooling water chamber 3 and the inner cooling water chamber 4 is 0.6 - 0.8 Mpa, and the cooling water flow rate is 90 m 3 / h.

[0037] The nozzle 13 is a Laval nozzle, and a gasket is provided at the connection between the rear end of the nozzle 13 and the port of the oxygen chamber 7.

[0038] Example 2

[0039] The difference from Embodiment 1 lies in that: a first sealing plate 8 is provided at the connection between the front end of the inner layer pipe 24 and the gun head 1, the front end of the first sealing plate 8 is welded to the gun head 1, and a sealing gasket is provided at the connection between the rear end of the first sealing plate 8 and the inner layer pipe 24; a second sealing plate 9 is provided at the connection between the front end of the middle layer pipe 22 and the gun head 1, the front end of the second sealing plate 9 is welded to the gun head 1, and a sealing gasket is provided at the connection between the rear end of the second sealing plate 9 and the middle layer pipe 22.

[0040] The seals are all made of high-temperature-resistant fluororubber. When installing, the concentricity and straightness of each layer of steel pipe must be ensured by means of tooling, and forced assembly is strictly prohibited to avoid damaging the roundness of each sleeve and the surface quality of the nozzle. When assembling the gun body, install bearings on the equal-height tooling so that the sleeve enters another layer of sleeve through the rolling bearing; when assembling at the position with the sealing ring, slowly press it in with a hydraulic jack; the connection form between the gun body and the metal hose can adopt a quick joint or a flange connection form. If a flange connection is adopted, generally the flange on the metal hose is designed as a loose flange to facilitate the installation and replacement of the top gun and the hose.

[0041] Embodiment 3

[0042] The difference from Embodiment 1 lies in that: the degree of the expansion angle of the nozzle 13 is 16°; the size of the expansion angle plays an important role in the fluid jet, and the fluid jet state also has a certain relationship with the length of the expansion section. Due to the limitation of the structure of the top gun for RH vacuum refining, if the expansion section is too long, processing is difficult, and if the expansion section is too short, the gas holes cannot be arranged. Therefore, it is most appropriate to take 16° for the expansion angle.

[0043] Embodiment 4

[0044] The difference from Embodiment 1 lies in that: the annular oxygen nozzle 11 opened on the gun head 1 is arranged in a circular hole shape, and the number of circular holes of the annular oxygen nozzle 11 is not less than eight, and the formed gun head 1 is an integral structure, which is convenient for installation and production.

[0045] Embodiment 5

[0046] The difference from Embodiment 1 lies in that: the annular oxygen nozzle 11 opened on the gun head 1 is an annular groove, and the annular oxygen nozzle 11 of the annular groove divides the gun head 1 into two parts. Although the installation of the gun head 1 will have an eccentricity problem, it can form a completely enclosed annular oxygen hood, and the effect of reducing noise is better.

[0047] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual-flow oxygen top lance for an RH refining furnace, comprising a lance head (1) and a lance body (2), characterized in that: The front end of the gun body (2) is equipped with a gun head (1). The gun body (2) includes an outer layer pipe (21), a middle layer pipe (22), an inner layer pipe (24), and an oxygen pipe (25). An oxygen cavity (7) is formed inside the oxygen pipe (25), and the oxygen cavity (7) is communicated with the main oxygen pipe (71). A gas cavity (6) is formed between the oxygen pipe (25) and the inner layer pipe (24), and the gas cavity (6) is communicated with a gas pipe (61). The gas input inside the gas pipe (61) is one of gas or natural gas. A first sealing plate (8) is arranged at the connection between the front end of the inner layer pipe (24) and the gun head (1), and the front end of the first sealing plate (8) is welded to the gun head (1). A sealing gasket is arranged at the connection between the rear end of the first sealing plate (8) and the inner layer pipe (24). An annular oxygen cavity (5) is formed between the middle layer pipe (22) and the baffle (23), and the annular oxygen cavity (5) is communicated with an annular oxygen pipe (51). The annular oxygen flow rate inside the annular oxygen pipe (51) is 700 Nm 3 / h. An outer cooling water cavity (3) and an inner cooling water cavity (4) are formed between the middle layer pipe (22) and the outer layer pipe (21), and the outer cooling water cavity (3) and the inner cooling water cavity (4) are separated by a baffle (23). A second sealing plate (9) is arranged at the connection between the front end of the middle layer pipe (22) and the gun head (1), and the front end of the second sealing plate (9) is welded to the gun head (1). A sealing gasket is arranged at the connection between the rear end of the second sealing plate (9) and the middle layer pipe (22). A cooling water inlet pipe (31) is connected below the outer cooling water cavity (3), and a cooling water outlet pipe (41) is connected below the inner cooling water cavity (4). A nozzle (13) is arranged in the middle of the gun head (1), and the nozzle (13) is connected to the main oxygen pipe (71). The oxygen pressure inside the main oxygen pipe (71) is 1.0 - 1.6 Mpa, and the oxygen flow rate is 4500 Nm 3 / h. A gas injection hole (12) is opened on the side of the nozzle (13), and the gas injection hole (12) is communicated with the gas cavity (6). An annular oxygen nozzle (11) is annularly opened on the gun head (1) outside the nozzle (13), and the annular oxygen nozzle (11) is communicated with the annular oxygen cavity (5). The nozzle (13) is a Laval nozzle, and a sealing gasket is arranged at the connection between the rear end of the nozzle (13) and the port of the oxygen cavity (7). The expansion angle of the nozzle (13) is 16°. The annular oxygen nozzles (11) opened on the gun head (1) are arranged in a circular hole shape, and the number of circular holes of the annular oxygen nozzles (11) is not less than eight. The annular oxygen nozzles (11) opened on the gun head (1) are annular grooves, and the annular oxygen nozzles (11) of the annular grooves divide the gun head (1) into two parts.

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