Bottom powder spraying gun manufacturing method

Abstract

The invention provides a manufacturing method for prolonging the service life of a bottom powder spraying gun, which comprises the following steps: taking martensitic stainless steel 12Cr12Mo as an inner pipe of the spraying gun, penetrating through a central hole of a bottom flange plate and then welding into a framework of the spraying gun; zirconia titanium ceramics are processed into gun body refractory materials, and zirconium oxide is used for grouting after a central pipe of the spray gun framework penetrates through a zirconium oxide titanium ceramic sheath. A gun body refractory sheath made of martensitic stainless steel 12Cr12Mo is heated to 200-300 DEG C, and the outer side of the zirconium oxide titanium ceramic circular truncated cone is sleeved with the gun body refractory sheath in a heat preservation mode; welding and stably connecting with a spray gun flange; zirconium oxide-aluminum oxide refractory materials are coated outside the spray gun body through isostatic pressing, and the cylindrical spray gun which is coaxial with the central pipe and has the outer diameter of 210 mm is manufactured. Compared with the prior art, the spray gun manufacturing process has the advantages that the service life of the spray gun can be prolonged by more than 30%, the stability of the internal shape and the welding structure of the spray gun is obviously improved, the nondestructive rate of precise elements such as a spray gun alarm pipe reaches more than 95%, the quality stability of the spray gun is ensured, and the service life is obviously prolonged; and a key technical support is provided for industrialization of a converter bottom powder spraying process technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of sheet rolling and relates to a manufacturing method of a bottom powder injection gun. Background Art

[0002] In recent years, due to the adverse effects brought about by global warming, the concept of green and low-carbon development has penetrated into the steel industry, which is the key to the transformation and upgrading and high-quality development of the steel industry. As an important process in the steel production process, converter steelmaking needs to accelerate the process of low-carbon technology innovation. Due to its metallurgical advantages of high efficiency, cleanness, and low carbon, the converter bottom powder injection technology has become a research hotspot for low-carbon development and is an important measure for the steel industry to achieve extreme energy efficiency.

[0003] The converter bottom powder injection process is a new process for converter smelting in which the powder agent and the carrier gas are sprayed into the molten bath through a gun at the bottom of the furnace. Since the powder agent is sprayed from the bottom in this process, the contact area between the powder agent and the molten metal is significantly enlarged, and the local concentration of the powder agent is increased; at the same time, due to the stirring action of the gas, the mass transfer process is accelerated, thereby greatly improving the kinetic conditions of the reaction in the molten bath and accelerating the reaction rate. This process can achieve continuous and controllable batching and feeding, can more reasonably control the reaction in the molten steel and the temperature of the molten bath, avoids the sudden change of the slag composition and the molten bath temperature caused by the traditional feeding method, and can effectively suppress the occurrence of accidents such as converter splashing.

[0004] At present, the converter smelting adopts the method of combined blowing, that is, top-blowing supersonic oxygen jet and bottom-blowing nitrogen or argon for intensive stirring. In the process of conventional combined-blowing converter steelmaking, the following main problems exist: it is difficult to reduce phosphorus to 100 ppm efficiently and economically, especially for high-quality clean steel with a phosphorus content lower than 50 ppm, resulting in a long smelting cycle, high consumption of raw and auxiliary materials, and increased costs; when smelting low-carbon steel, the molten steel is severely peroxidized, the carbon-oxygen product is on the high side, and the quality of the molten steel is difficult to guarantee; the traditional bottom-blowing intensity is difficult to meet the requirements of the kinetic stirring in the converter furnace, and the chemical reaction in the furnace is difficult to reach equilibrium.

[0005] The process effect of the converter bottom powder injection technology is obvious, but the industrialization is extremely difficult, and the key technologies still need to be further developed. Among them, for the bottom powder injection gun, due to the harsh service conditions at the top of the gun, it is in direct contact with molten steel above 1600 °C, and the powder agent is transported at high speed by oxygen on the inner wall. The gun serves in a high-temperature oxidizing atmosphere, resulting in the service life of the gun not being synchronized with the converter campaign. Therefore, although this technical concept has been proposed for decades, it has not been widely applied. Summary of the Invention

[0006] The purpose of the present invention is to provide a manufacturing method of a bottom powder injection gun for the problems existing in the prior art that the service life of the existing bottom powder injection gun is relatively short.

[0007] To this end, the present invention adopts the following technical solutions: A method for manufacturing a bottom powder spray gun, comprising the following steps: (1) Use martensitic stainless steel 12Cr12Mo with an inner diameter of 18 - 22 mm and a wall thickness of 2 - 3 mm as the inner tube of the spray gun. Weld a flange with an installation hole of 18.5 - 22.5 mm at the bottom of the inner tube of the spray gun to form the spray gun skeleton, and the flange is perpendicular to the bottom of the inner tube of the spray gun; (2) Process a zirconia - titania ceramic frustum with an upper base diameter of 35 mm and a lower base diameter of 45 mm. Open a central hole along the center line on the zirconia - titania ceramic frustum to form a zirconia - titania ceramic sheath. The diameter of the central hole is 0.5 mm larger than the diameter of the inner tube of the spray gun. Sleeve the zirconia - titania ceramic sheath on the inner tube of the spray gun, and make the inner tube of the spray gun coaxial with the central hole; (3) Process a frustum sheath with a wall thickness of 1.5 mm and adapted to the zirconia - titania ceramic sheath. The frustum sheath is made of martensitic stainless steel 12Cr12Mo; (4) Use zirconia grouting from the gap between the zirconia - titania ceramic sheath and the inner tube of the spray gun. Stop grouting after the zirconia grouting flows out from the lower opening of the zirconia - titania ceramic sheath; (5) Heat the zirconia - titania ceramic sheath to 200 - 300 °C and keep it warm. After stopping grouting, quickly sleeve the frustum sheath from the top of the zirconia - titania ceramic sheath onto the zirconia - titania ceramic sheath to make the spray gun body; (6) Externally apply zirconia - alumina refractory material to the spray gun body by isostatic pressing to make the spray gun.

[0008] Further, the linear expansion coefficient of the martensitic stainless steel 12Cr12Mo for manufacturing the inner tube of the spray gun in step (1) is 10.5×10 - 6 / °C, Further, in step (2), the linear expansion coefficient of the zirconia - titania ceramic in the zirconia - titania ceramic sheath is 10.5×10 - 6 / °C.

[0009] The beneficial effects of the present invention are as follows: 1. The refractory material of the spray gun body of the present invention selects zirconia - titania ceramic material, which ensures that the gun body and the refractory material of the gun body expand uniformly under high - temperature environment, reduces the refractory loss caused by internal stress, and ensures the erosion - resistance of the refractory material around the gun body; 2. The present invention processes the gun body and the refractory material separately, and assembles them by using the method of zirconia powder grouting, avoiding directly pressing the refractory material of the gun body on the gun body by isostatic pressing technology, resulting in deformation inside the spray gun body and the problem of solder joint fracture; 3. In the present invention, the spray gun sheath is heated before assembly. By using the principle of thermal expansion and contraction, the sheath is in close and uniform contact with the refractory of the gun body, ensuring the uniformity of stress. At the same time, the excess moisture after grouting is evaporated by the temperature of the sheath, ensuring the stability of the grouting bond. 4. The erosion resistance of the refractory of the gun body in the present invention is improved. During use, the jet angle of the spray gun becomes smaller, increasing the distance between the upper end of the spray gun and the liquid metal, weakening the high-temperature melting loss at the end of the spray gun, and the service life of the spray gun can be increased compared with that when using magnesia-carbon bricks for the refractory of the gun body. 5. Using the new spray gun manufacturing process of the present invention, the service life of the spray gun can be increased by more than 30% compared with the original process. The stability of the internal shape and welding structure of the spray gun is significantly improved. The non-damage rate of precision components such as the alarm pipe of the spray gun reaches more than 95%, ensuring the stability of the spray gun quality, significantly increasing the service life, and providing key technical support for the industrialization of the bottom powder injection process technology for converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic structural diagram of the high-bottom powder injection gun of the present invention; In the figure, 1 - inner pipe of the spray gun, 2 - flange, 3 - mounting hole, 4 - zirconia-titanium ceramic frustum, 5 - central hole, 6 - frustum sheath, 7 - refractory of the gun body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The present invention will be described in detail below with reference to the embodiments: Embodiment 1 A method for manufacturing a bottom powder injection gun includes the following steps: (1) The inner pipe 1 of the spray gun is made of martensitic stainless steel 12Cr12Mo with an inner diameter of 18 mm and a wall thickness of 2 mm. A flange 2 is welded to the bottom of the inner pipe 1 of the spray gun to form a spray gun skeleton. The flange 2 is provided with a mounting hole 3 with a diameter of 18.5 mm. Before welding the flange 2, the bottom of the inner pipe 1 of the spray gun is passed through the mounting hole 3 of the flange 2, and the inner pipe 1 of the spray gun and the flange 2 are perpendicular to each other.

[0012] (2) Using zirconia-titanium ceramic as the base material, a zirconia-titanium ceramic frustum 4 with an upper base diameter of 35 mm and a lower base diameter of 45 mm is processed, and a central hole 5 with a diameter 0.5 mm larger than the outer diameter of the inner pipe 1 of the spray gun is processed on the center line of the zirconia-titanium ceramic frustum 4 to form a zirconia-titanium ceramic sheath. The zirconia-titanium ceramic sheath is sleeved on the inner pipe 1 of the spray gun, and the inner pipe of the spray gun and the central hole 5 are coaxially arranged; (3) Based on the outer diameter dimension of the zirconia-titanium ceramic sheath, a frustum sheath 6 with a wall thickness of 1.5 mm and adapted to the zirconia-titanium ceramic sheath is processed. The processed frustum sheath 6 should ensure a tight fit with the zirconia-titanium ceramic sheath; (4) Use zirconia grouting in the gap between the zirconia-titanium ceramic sheath and the inner tube 1 of the spray gun. During the grouting process, the zirconia-titanium ceramic sheath can be slightly rotated. Stop grouting after the zirconia grouting flows out from the lower opening of the zirconia-titanium ceramic sheath. (5) Heat the frustum-shaped sheath 6 to 200 °C and keep it warm. After stopping the grouting, quickly put the frustum-shaped sheath 6 on the zirconia-titanium ceramic sheath from the top of the zirconia-titanium ceramic sheath to make the spray gun body. The heat of the frustum-shaped sheath 6 is transferred to the zirconia-titanium ceramic sheath. The zirconia-titanium ceramic sheath expands due to the temperature rise, thereby ensuring full contact between the inner tube 1 of the zirconia-titanium ceramic sheath spray gun and the upper surface of the flange 2. At the same time, the grouting between the inner tube 1 of the spray gun and the zirconia-titanium ceramic sheath solidifies rapidly when heated, ensuring a stable connection between the zirconia-titanium ceramic sheath and the inner tube 1 of the horse spray gun.

[0013] (6) Externally apply the gun body refractory 7 made of magnesia-carbon material to the outside of the spray gun body by isostatic pressing to make a spray gun with a cylindrical shape coaxial with the central tube and an outer diameter of 210 mm.

[0014] Through the improvement of the gun body refractory and the manufacturing method, compared with the original process, the service life of the spray gun can be increased by 31%. The stability of the internal shape and welding structure of the spray gun is significantly improved. The non-damage rate of precision components such as the alarm pipe of the spray gun reaches 99%, ensuring the stability of the spray gun quality and significantly improving the service life, providing key technical support for the industrialization of the bottom powder injection process technology for converters.

[0015] Example 2 (1) Make the inner tube 1 of the spray gun with martensitic stainless steel 12Cr12Mo with an inner diameter of 22 mm and a wall thickness of 3 mm. Weld a flange 2 at the bottom of the inner tube 1 of the spray gun to form a spray gun skeleton. There are mounting holes 3 on the flange 2, and the diameter of the mounting holes 3 is 22.5 mm. Before welding the flange 2, pass the bottom of the inner tube 1 of the spray gun through the mounting holes 3 of the flange 2, and make the inner tube 1 of the spray gun perpendicular to the flange 2.

[0016] (2) Using zirconia-titanium ceramic as the base material, process a zirconia-titanium ceramic frustum 4 with an upper base diameter of 35 mm and a lower base diameter of 45 mm, and process a central hole 5 with a diameter 0.5 mm larger than the outer diameter of the inner tube 1 of the spray gun on the center line of the zirconia-titanium ceramic frustum 4 to form a zirconia-titanium ceramic sheath. Set the zirconia-titanium ceramic sheath on the inner tube 1 of the spray gun, and make the inner tube of the spray gun coaxial with the central hole 5. (3) Based on the outer diameter size of the zirconia-titanium ceramic sheath, process a frustum-shaped sheath 6 with a wall thickness of 1.5 mm and adapted to the zirconia-titanium ceramic sheath. The processed frustum-shaped sheath 6 should ensure a tight fit with the zirconia-titanium ceramic sheath. (4)Use zirconia grouting in the gap between the zirconia-titanium ceramic sheath and the inner pipe 1 of the spray gun. During the grouting process, the zirconia-titanium ceramic sheath can be slightly rotated. Stop grouting after the zirconia grouting flows out from the lower opening of the zirconia-titanium ceramic sheath; (5)Heat the frustum-shaped sheath 6 to 200 °C and keep it warm. After stopping grouting, quickly put the frustum-shaped sheath 6 on the zirconia-titanium ceramic sheath from the top of the zirconia-titanium ceramic sheath to form the spray gun body. The heat of the frustum-shaped sheath 6 is transferred to the zirconia-titanium ceramic sheath. The zirconia-titanium ceramic sheath expands due to the temperature rise, thereby ensuring full contact between the inner pipe 1 of the zirconia-titanium ceramic sheath spray gun and the upper surface of the flange 2. At the same time, the grouting between the inner pipe 1 of the spray gun and the zirconia-titanium ceramic sheath solidifies rapidly when heated, ensuring a stable connection between the zirconia-titanium ceramic sheath and the inner pipe 1 of the spray gun.

[0017] (6)Externally apply the gun body refractory 7 made of magnesia-carbon material to the outside of the spray gun body by isostatic pressing to make a spray gun with a coaxial center pipe and a 210 mm outer diameter cylinder.

Claims

1. A method for manufacturing a bottom powder spray gun, characterized in that: The following steps are involved: (1) A martensitic stainless steel 12Cr12Mo with an inner diameter of 18-22 mm and a wall thickness of 2-3 mm is used as the inner tube of the spray gun, and a flange with a mounting hole of 18.5-22.5 mm is welded at the bottom of the inner tube of the spray gun to form a spray gun frame, and the flange and the bottom of the inner tube of the spray gun are arranged perpendicular to each other; (2) processing a zirconia titanium ceramic truncated cone with an upper bottom diameter of 35 mm and a lower bottom diameter of 45 mm, opening a center hole along the center line of the zirconia titanium ceramic truncated cone to form a zirconia titanium ceramic sheath, wherein the diameter of the center hole is 0.5 mm larger than the diameter of the inner tube of the spray gun, and the zirconia titanium ceramic sheath is sleeved on the inner tube of the spray gun, and the inner tube of the spray gun is made coaxial with the center hole; (3) machining a truncated cone sleeve with a wall thickness of 1.5 mm and adapted to the zirconia titanium ceramic sleeve, wherein the truncated cone sleeve is made of martensitic stainless steel 12Cr12Mo; (4) Use zirconia grouting in the gap between the zirconia titanium ceramic sheath and the inner tube of the spray gun, and stop grouting after the zirconia grouting flows out from the lower port of the zirconia titanium ceramic sheath; (5) Heat the truncated cone jacket to 200-300°C and keep it warm. After stopping the grouting, quickly put the truncated cone jacket from the top of the zirconium titanium ceramic jacket to the zirconium titanium ceramic jacket to form the spray gun body; (6) The spray gun is manufactured by applying zirconium oxide-aluminum oxide refractory material to the outside of the spray gun body by isostatic pressing.

2. A method for manufacturing a bottom powder spray gun according to claim 1, characterized in that: The linear expansion coefficient of the martensitic stainless steel 12Cr12Mo used to manufacture the spray gun inner tube in step (1) is 10.5×10-6 / °C.

3. A method for manufacturing a bottom powder spray gun according to claim 1, characterized in that: In the step (2), the linear expansion coefficient of the zirconium oxide titanium ceramic in the zirconium oxide titanium ceramic sheath is 10.5×10-6 / °C.

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